阅读说明：本技术 Mems器件及其制备方法 (MEMS device and preparation method thereof ) 是由 周延青 潘华兵 郑泉智 胡铁刚 于 2021-08-17 设计创作，主要内容包括：本发明提供了一种MEMS器件及其制备方法,包括制备于同一衬底上的至少两个MEMS单元组,每个所述MEMS单元组包括若干MEMS单元,每两个所述MEMS单元组为同一级,同一级的两个MEMS单元组中的MEMS单元的背板和振膜相对位置不同,且一个MEMS单元组中的至少一个MEMS单元与另一个MEMS单元组中的至少一个MEMS单元电性连接。本发明中同一级的两个MEMS单元组可实现横向差分,相较于纵向差分来说,横向差分结构更容易制备,两个MEMS单元组的电容也更容易匹配；并且,不同级的MEMS单元组输出的MEMS信号后续可以实现信号级联,可用于制作多级级联结构的MEMS系统,从而提升灵敏度和信噪比。(The invention provides an MEMS device and a preparation method thereof, wherein the MEMS device comprises at least two MEMS unit groups prepared on the same substrate, each MEMS unit group comprises a plurality of MEMS units, each two MEMS unit groups are in the same level, the relative positions of a back plate and a vibrating diaphragm of the MEMS units in the two MEMS unit groups in the same level are different, and at least one MEMS unit in one MEMS unit group is electrically connected with at least one MEMS unit in the other MEMS unit group. In the invention, the two MEMS unit groups at the same level can realize transverse difference, compared with longitudinal difference, the transverse difference structure is easier to prepare, and the capacitances of the two MEMS unit groups are easier to match; moreover, the MEMS signals output by the MEMS unit groups of different levels can realize signal cascade subsequently, and can be used for manufacturing an MEMS system with a multistage cascade structure, so that the sensitivity and the signal-to-noise ratio are improved.)

1. The MEMS device is characterized by comprising at least two MEMS unit groups prepared on the same substrate, wherein each MEMS unit group comprises a plurality of MEMS units, every two MEMS unit groups are of the same level, the relative positions of a back plate and a vibrating diaphragm of the MEMS units in the two MEMS unit groups of the same level are different, and at least one MEMS unit in one MEMS unit group is electrically connected with at least one MEMS unit in the other MEMS unit group.

2. The MEMS device according to claim 1, wherein the two MEMS element groups at the same stage are a first MEMS element group and a second MEMS element group, respectively, each of the first MEMS element group and the second MEMS element group includes one MEMS element, and the MEMS elements in the first MEMS element group and the MEMS elements in the second MEMS element group are electrically connected to form a MEMS differential pair.

3. The MEMS device of claim 2, wherein the MEMS cells of the first group of MEMS cells draw a first MEMS signal through a pad, the MEMS cells of the second group of MEMS cells draw a second MEMS signal through a pad, the MEMS cells of the first group of MEMS cells and the MEMS cells of the second group of MEMS cells are connected by a pad, and the first MEMS signal and the second MEMS signal form a MEMS differential signal.

4. The MEMS device according to claim 1, wherein the two MEMS element groups at the same stage are a first MEMS element group and a second MEMS element group, respectively, each of the first MEMS element group and the second MEMS element group includes two MEMS elements connected in parallel, and one of the MEMS elements in the first MEMS element group is electrically connected to one of the MEMS elements in the second MEMS element group to form a MEMS differential pair.

5. The MEMS device of claim 4, wherein one of the MEMS cells of the first group of MEMS cells draws a first MEMS signal through a pad, one of the MEMS cells of the second group of MEMS cells draws a second MEMS signal through a pad, one of the MEMS cells of the first group of MEMS cells is connected to one of the MEMS cells of the second group of MEMS cells through a pad, and the first MEMS signal and the second MEMS signal form a MEMS differential signal.

6. The MEMS device of claim 1, wherein the electrical connection is through a pad.

7. The MEMS device of claim 1, wherein the electrical connection is by wire bonding.

8. The MEMS device of claim 1, wherein the MEMS elements of each of the groups of MEMS elements are the same MEMS structure.

9. The MEMS device according to claim 1, wherein the MEMS elements forming the MEMS differential signal between the MEMS elements of different MEMS element groups are at the same stage, when the MEMS elements at the same stage are excited, capacitance variation amounts of the MEMS elements at the same stage are in opposite directions and output the MEMS differential signal, and capacitance variation amounts of the MEMS elements in the same MEMS element group are in the same direction.

10. The MEMS device of claim 1, wherein the number of MEMS elements in any two of the groups of MEMS elements is the same or different.

11. The MEMS device according to claim 9, wherein two MEMS unit groups of the same stage correspond to one pad group, each of the pad groups includes at least three pads, and the two MEMS unit groups of the same stage output MEMS signals in common through the corresponding pad groups.

12. The MEMS device of claim 1, wherein the diaphragms of all of the MEMS cells in each of the MEMS cell groups are electrically connected to each other, and the back-plate electrodes of all of the MEMS cells in each of the MEMS cell groups are electrically connected to each other, such that at least two of the MEMS cells in each of the MEMS cell groups are connected in parallel.

13. The MEMS device of claim 9, wherein the diaphragms of all of the MEMS elements in two MEMS element groups of the same stage are electrically connected to each other.

14. The MEMS device of claim 9, wherein the back-plate electrodes of all the MEMS cells in two MEMS cell groups of the same stage are electrically connected to each other.

15. The MEMS device according to claim 13, wherein the diaphragms of the corresponding two MEMS elements in the two MEMS element groups of the same stage are directly electrically connected and led out through a pad or electrically connected through a pad.

16. The MEMS device of claim 14, wherein the back-plate electrodes of the two MEMS elements in the two MEMS element groups of the same stage are directly electrically connected and led out through a bonding pad or electrically connected through a bonding pad.

17. The MEMS device of claim 1, wherein in two MEMS element groups of the same stage, all of the MEMS elements in one MEMS element group are MEMS microphones with diaphragms above a back plate electrode, and all of the MEMS elements in the other MEMS element group are MEMS microphones with diaphragms below the back plate electrode.

18. The MEMS device of claim 13, wherein in two MEMS element groups of a same stage, the back-plate electrodes of all the MEMS elements in one MEMS element group are located at a first layer, the back-plate electrodes of all the MEMS elements in the other MEMS element group are located at a second layer, the diaphragms of all the MEMS elements in the two MEMS element groups are located at a third layer, the third layer is located between the first layer and the second layer, and the first layer is closer to the substrate than the second layer.

19. The MEMS device as claimed in claim 18, wherein a protective layer is formed on a side of the back plate electrodes of all the MEMS cells adjacent to the diaphragm thereof, the diaphragm of all the MEMS cells located on the third layer and having the back plate electrodes located on the first layer has a first protrusion facing the back plate electrodes thereof, and the protective layer of the diaphragm of all the MEMS cells located on the third layer and having the back plate electrodes located on the second layer has a second protrusion facing the diaphragm thereof.

20. The MEMS device of claim 14, wherein in two MEMS element groups of the same stage, the diaphragms of all the MEMS elements in one MEMS element group are located at a first layer, the diaphragms of all the MEMS elements in the other MEMS element group are located at a second layer, the back plate electrodes of all the MEMS elements in the two MEMS element groups are located at a third layer, the third layer is located between the first layer and the second layer, and the first layer is closer to the substrate than the second layer.

21. The MEMS device as claimed in claim 20, wherein a protective layer is formed on a side of the back plate electrodes of all the MEMS cells close to the diaphragm thereof, the protective layer on the back plate electrodes of all the MEMS cells of which the diaphragm is located at the first layer and the back plate electrodes are located at the third layer has a first protrusion facing the diaphragm thereof, the diaphragm is located at the second layer and the back plate electrodes have a second protrusion facing the back plate electrodes thereof on the diaphragm of all the MEMS cells of which the back plate electrodes are located at the third layer.

22. The MEMS device of claim 1, further comprising a support fence comprising a first support layer, a second support layer, and a third support layer stacked in sequence on the substrate, the first layer located at an interface of the first support layer and the second support layer, the second layer located on the third support layer, and the third layer located at an interface of the second support layer and the third layer.

23. The MEMS device of claim 22, wherein in two MEMS element groups of the same stage, the third support layer covers edges of back-plate electrodes of all the MEMS elements of one or both of the MEMS element groups; alternatively, the third support layer covers the edges of the diaphragms of all the MEMS elements of one or both of the groups of MEMS elements.

24. The MEMS device of claim 1, wherein the MEMS element groups are arranged in a first direction and the MEMS elements in each of the MEMS element groups are arranged in a second direction such that all of the MEMS element arrays are distributed.

25. The MEMS device of claim 24, wherein corresponding MEMS cells in each of the groups of MEMS cells are aligned in the first direction.

26. The MEMS device of claim 24 or 25, wherein the first direction is perpendicular to the second direction.

27. A method of fabricating a MEMS device, comprising:

providing a substrate; and the number of the first and second groups,

the method comprises the steps that at least two MEMS unit groups are prepared on the substrate, every two MEMS unit groups are in the same level, the relative positions of a back plate and a diaphragm of the MEMS units of the two MEMS unit groups in the same level are different, and at least one MEMS unit in one MEMS unit group is electrically connected with at least one MEMS unit in the other MEMS unit group.

28. The method of fabricating a MEMS device according to claim 27, wherein all of the MEMS elements are simultaneously fabricated on the substrate.

29. The method of fabricating a MEMS device as defined by claim 28 wherein the MEMS elements are MEMS microphones and the step of simultaneously fabricating all of the MEMS elements on the substrate includes:

forming a first sacrificial layer on the substrate;

forming back plate electrodes of all MEMS units of any one MEMS unit group in two MEMS unit groups of the same level on the first sacrificial layer;

forming a second sacrificial layer over the first sacrificial layer and the backplane structure;

forming a diaphragm of all the MEMS units on the second sacrificial layer;

forming a third sacrificial layer on all the diaphragms;

forming back plate electrodes of all MEMS units of another MEMS unit group in the two MEMS unit groups of the same level on the third sacrificial layer; and the number of the first and second groups,

and releasing the first sacrificial layer, the second sacrificial layer and the third sacrificial layer.

30. The method for manufacturing a MEMS device according to claim 29, wherein after the second sacrificial layer is formed, the second sacrificial layer is etched to form a plurality of first grooves, and the first grooves correspond to the back-plate electrodes formed on the first sacrificial layer in position; when the vibrating membranes of all the MEMS units are formed on the second sacrificial layer, the vibrating membrane corresponding to the back plate electrode formed on the first sacrificial layer fills the first groove to form a first protrusion; and the number of the first and second groups,

after the third sacrificial layer is formed, etching the third sacrificial layer to form a plurality of second grooves, wherein the positions of the second grooves correspond to the back plate electrodes formed on the third sacrificial layer; and before forming the back plate electrode on the third sacrificial layer, forming a protective layer on the third sacrificial layer, wherein the protective layer fills the second groove to form a second protrusion.

31. The method of fabricating a MEMS device as defined by claim 28 wherein the MEMS elements are MEMS microphones and the step of simultaneously fabricating all of the MEMS elements on the substrate includes:

forming a first sacrificial layer on the substrate;

forming a vibrating membrane of all MEMS units of any one of two MEMS unit groups of the same level on the first sacrificial layer;

forming a second sacrificial layer on the first sacrificial layer and the diaphragm;

forming back-plate electrodes of all the MEMS units on the second sacrificial layer;

forming a third sacrificial layer on all the backplane structures;

forming a vibrating membrane of all MEMS units of another MEMS unit group in two MEMS unit groups of the same level on the third sacrificial layer; and the number of the first and second groups,

and releasing the first sacrificial layer, the second sacrificial layer and the third sacrificial layer.

32. The method for manufacturing an MEMS device according to claim 31, wherein after the second sacrificial layer is formed, the second sacrificial layer is etched to form a plurality of first grooves, and the positions of the first grooves correspond to a diaphragm formed on the first sacrificial layer; before the back plate structures of all the MEMS units are formed on the second sacrificial layer, a protective layer is further formed on the second sacrificial layer and fills the first groove to form a first protrusion; and the number of the first and second groups,

after the third sacrificial layer is formed, etching the third sacrificial layer to form a plurality of second grooves, wherein the positions of the second grooves correspond to the vibration film formed on the third sacrificial layer; and when a vibrating membrane is formed on the third sacrificial layer, the vibrating membrane formed on the third sacrificial layer fills the second groove to form a second protrusion.

33. A method of fabricating a MEMS device according to any of claims 29 to 31, further comprising, prior to releasing the first, second and third sacrificial layers:

and forming a pad group on the third sacrificial layer, wherein each pad group corresponds to two MEMS unit groups of the same level, each pad group comprises at least three pads, and the two MEMS unit groups of the same level output MEMS signals together through the corresponding pad groups.

34. The method of manufacturing a MEMS device according to claim 33, wherein, when each diaphragm is formed, a corresponding diaphragm lead and a diaphragm contact point are also formed simultaneously, the diaphragm lead being used to electrically connect the diaphragm contact point with the corresponding diaphragm; when each backboard electrode is formed, a corresponding backboard lead and a backboard contact point are also synchronously formed, the backboard lead is used for electrically connecting the backboard contact point with the corresponding backboard electrode, and a pad in the pad group is electrically connected with the corresponding vibrating diaphragm contact point or the corresponding backboard contact point.

35. The method for manufacturing an MEMS device according to claim 34, wherein the vibrating membranes of the corresponding MEMS elements in the two MEMS element groups of the same stage share one of the vibrating membrane contact point and the bonding pad and are directly electrically connected; or the back plate electrodes of the corresponding MEMS units in the two MEMS unit groups at the same level share one back plate contact point and one bonding pad and are directly and electrically connected.

36. The method for manufacturing an MEMS device according to claim 34, wherein the vibrating membranes of two corresponding MEMS elements in two MEMS element groups of the same stage respectively correspond to one of the vibrating membrane contact point and the bonding pad, and the two corresponding bonding pads are electrically connected; or the vibrating membranes of two corresponding MEMS units in two MEMS unit groups at the same level respectively correspond to one vibrating membrane contact point and one bonding pad, and the two corresponding bonding pads are electrically connected.

37. The method according to claim 31, wherein after the first, second, and third sacrificial layers are released, the remaining first, second, and third sacrificial layers respectively constitute first, second, and third support layers, which constitute support fences, and in two MEMS element groups of the same stage, the third support layer covers edges of back plate electrodes of all the MEMS elements of one or two MEMS element groups; alternatively, the third support layer covers the edges of the diaphragms of all the MEMS elements of one or both of the groups of MEMS elements.

Technical Field

The invention relates to the technical field of semiconductors, in particular to an MEMS (micro-electromechanical system) device and a preparation method thereof.

Background

The MEMS microphone is a MEMS (Micro-Electro-Mechanical System) device manufactured by using a Micro-machining process. Due to the advantages of small volume, high sensitivity and good compatibility with the existing semiconductor technology, the MEMS microphone is more and more widely applied to mobile terminals such as mobile phones. The structure of the MEMS microphone includes a diaphragm and a back plate electrode facing each other with a cavity formed therebetween to provide a vibration space required for the diaphragm.

However, the MEMS microphone is limited by the manufacturing process, and the sensitivity and the signal-to-noise ratio cannot be further improved.

Disclosure of Invention

The invention aims to provide an MEMS device and a preparation method thereof, and aims to solve the problem that the sensitivity and the signal-to-noise ratio of the existing MEMS microphone cannot be further improved.

In order to achieve the above object, the present invention provides a MEMS device, which includes at least two MEMS unit groups prepared on the same substrate, each of the MEMS unit groups includes a plurality of MEMS units, each of the two MEMS unit groups is of the same stage, relative positions of a back plate and a diaphragm of the MEMS unit in the two MEMS unit groups of the same stage are different, and at least one MEMS unit in one MEMS unit group is electrically connected to at least one MEMS unit in another MEMS unit group.

Optionally, the two MEMS unit groups at the same stage are a first MEMS unit group and a second MEMS unit group, each of the first MEMS unit group and the second MEMS unit group includes a MEMS unit, and the MEMS unit in the first MEMS unit group and the MEMS unit in the second MEMS unit group are electrically connected to form a MEMS differential pair.

Optionally, a first MEMS signal is led out from a MEMS unit in the first MEMS unit group through a pad, a second MEMS signal is led out from a MEMS unit in the second MEMS unit group through a pad, the MEMS unit in the first MEMS unit group and the MEMS unit in the second MEMS unit group are connected through a pad, and the first MEMS signal and the second MEMS signal form a MEMS differential signal.

Optionally, the two MEMS unit groups at the same stage are a first MEMS unit group and a second MEMS unit group, each of the first MEMS unit group and the second MEMS unit group includes two MEMS units connected in parallel, and one of the MEMS units in the first MEMS unit group is electrically connected to one of the MEMS units in the second MEMS unit group to form a MEMS differential pair.

Optionally, one of the MEMS elements in the first MEMS element group leads out a first MEMS signal through a pad, one of the MEMS elements in the second MEMS element group leads out a second MEMS signal through a pad, one of the MEMS elements in the first MEMS element group and one of the MEMS elements in the second MEMS element group are connected through a pad, and the first MEMS signal and the second MEMS signal form a MEMS differential signal.

Optionally, the electrical connection is through a pad.

Optionally, the electrical connection is through a routing electrical connection.

Optionally, the MEMS units in each MEMS unit group are of the same MEMS structure.

Optionally, the MEMS units forming the MEMS differential signal between the MEMS units of different MEMS unit groups are of the same stage, when the MEMS unit of the same stage is excited, the capacitance variation of the MEMS unit of the same stage is reverse and outputs the MEMS differential signal, and the capacitance variation of the MEMS unit of the same MEMS unit group is in the same direction.

Optionally, the number of MEMS elements in any two of the groups of MEMS elements is the same or different.

Optionally, two MEMS unit groups at the same level correspond to one pad group, each pad group includes at least three pads, and the two MEMS unit groups at the same level output MEMS signals together through the corresponding pad groups.

Optionally, the vibrating membranes of all the MEMS units in each MEMS unit group are electrically connected to each other, and the back plate electrodes of all the MEMS units in each MEMS unit group are electrically connected to each other, so that at least two MEMS units in each MEMS unit group are connected in parallel.

Optionally, the diaphragms of all the MEMS units in two MEMS unit groups at the same stage are electrically connected to each other.

Optionally, the back plate electrodes of all the MEMS units in the two MEMS unit groups at the same stage are electrically connected to each other.

Optionally, the vibrating membranes of two corresponding MEMS units in two MEMS unit groups at the same stage are directly electrically connected and led out through a pad or electrically connected through a pad.

Optionally, the back plate electrodes of two corresponding MEMS units in two MEMS unit groups at the same stage are directly electrically connected and led out through a pad or electrically connected through a pad.

Optionally, in the two MEMS unit groups at the same stage, all the MEMS units in one MEMS unit group are MEMS microphones whose diaphragms are located above the back plate electrodes, and all the MEMS units in the other MEMS unit group are MEMS microphones whose diaphragms are located below the back plate electrodes.

Optionally, in two MEMS unit groups of the same stage, the back plate electrodes of all the MEMS units in one MEMS unit group are located on a first layer, the back plate electrodes of all the MEMS units in another MEMS unit group are located on a second layer, and the vibrating membranes of all the MEMS units in two MEMS unit groups are located on a third layer, where the third layer is located between the first layer and the second layer, and the first layer is closer to the substrate than the second layer.

Optionally, a protection layer is formed on one surface of each of the back plate electrodes of the MEMS units, which is close to the vibrating membrane, the vibrating membrane is located on the third layer, the back plate electrode is located on the first layer, the vibrating membranes of all the MEMS units have first protrusions facing the back plate electrodes of the MEMS units, the vibrating membrane is located on the third layer, and the protection layer on the back plate electrodes of all the MEMS units, which are located on the second layer, has second protrusions facing the vibrating membranes.

Optionally, in two MEMS unit groups of the same stage, one of the MEMS unit groups is located at a first layer, and the other is located at a second layer, and the two MEMS unit groups are located at a third layer, where the third layer is located between the first layer and the second layer, and the first layer is closer to the substrate than the second layer.

Optionally, a protective layer is formed on one surface of each of the back plate electrodes of the MEMS units, which is close to the vibrating membrane, the vibrating membrane is located on the first layer, the back plate electrode is located on the third layer, the protective layer on each of the back plate electrodes of the MEMS units has a first protrusion facing the vibrating membrane, the vibrating membrane is located on the second layer, and the back plate electrode is located on each of the vibrating membranes of the MEMS units on the third layer, and the second protrusion facing the back plate electrode is located on each of the vibrating membranes of the MEMS units on the second layer.

Optionally, the substrate further includes a supporting enclosure, where the supporting enclosure includes a first supporting layer, a second supporting layer, and a third supporting layer stacked on the substrate in sequence, the first layer is located at a junction between the first supporting layer and the second supporting layer, the second layer is located on the third supporting layer, and the third layer is located at a junction between the second supporting layer and the third layer.

Optionally, in two MEMS unit groups of the same stage, the third supporting layer covers edges of back plate electrodes of all the MEMS units of one or two MEMS unit groups; alternatively, the third support layer covers the edges of the diaphragms of all the MEMS elements of one or both of the groups of MEMS elements.

Optionally, the MEMS unit groups are arranged along a first direction, and the MEMS units in each MEMS unit group are arranged along a second direction, so that all the MEMS unit arrays are distributed.

Optionally, corresponding MEMS elements in each of the groups of MEMS elements are aligned in the first direction.

Optionally, the first direction is perpendicular to the second direction.

The invention also provides a preparation method of the MEMS device, which comprises the following steps:

providing a substrate; and the number of the first and second groups,

the method comprises the steps that at least two MEMS unit groups are prepared on the substrate, every two MEMS unit groups are in the same level, the relative positions of a back plate and a diaphragm of the MEMS units of the two MEMS unit groups in the same level are different, and at least one MEMS unit in one MEMS unit group is electrically connected with at least one MEMS unit in the other MEMS unit group.

Optionally, all the MEMS units are simultaneously prepared on the substrate.

Optionally, the MEMS unit is a MEMS microphone, and the step of synchronously preparing all the MEMS units on the substrate includes:

forming a first sacrificial layer on the substrate;

forming back plate electrodes of all MEMS units of any one MEMS unit group in two MEMS unit groups of the same level on the first sacrificial layer;

forming a second sacrificial layer over the first sacrificial layer and the backplane structure;

forming a diaphragm of all the MEMS units on the second sacrificial layer;

forming a third sacrificial layer on all the diaphragms;

forming back plate electrodes of all MEMS units of another MEMS unit group in the two MEMS unit groups of the same level on the third sacrificial layer; and the number of the first and second groups,

and releasing the first sacrificial layer, the second sacrificial layer and the third sacrificial layer.

Optionally, after the second sacrificial layer is formed, etching the second sacrificial layer to form a plurality of first grooves, where the positions of the first grooves correspond to the back plate electrodes formed on the first sacrificial layer; when the vibrating membranes of all the MEMS units are formed on the second sacrificial layer, the vibrating membrane corresponding to the back plate electrode formed on the first sacrificial layer fills the first groove to form a first protrusion; and the number of the first and second groups,

after the third sacrificial layer is formed, etching the third sacrificial layer to form a plurality of second grooves, wherein the positions of the second grooves correspond to the back plate electrodes formed on the third sacrificial layer; and before forming the back plate electrode on the third sacrificial layer, forming a protective layer on the third sacrificial layer, wherein the protective layer fills the second groove to form a second protrusion.

Optionally, the MEMS unit is a MEMS microphone, and the step of synchronously preparing all the MEMS units on the substrate includes:

forming a first sacrificial layer on the substrate;

forming a vibrating membrane of all MEMS units of any one of two MEMS unit groups of the same level on the first sacrificial layer;

forming a second sacrificial layer on the first sacrificial layer and the diaphragm;

forming back-plate electrodes of all the MEMS units on the second sacrificial layer;

forming a third sacrificial layer on all the backplane structures;

forming a vibrating membrane of all MEMS units of another MEMS unit group in two MEMS unit groups of the same level on the third sacrificial layer; and the number of the first and second groups,

and releasing the first sacrificial layer, the second sacrificial layer and the third sacrificial layer.

Optionally, after the second sacrificial layer is formed, etching the second sacrificial layer to form a plurality of first grooves, where the positions of the first grooves correspond to the vibration film formed on the first sacrificial layer; before the back plate structures of all the MEMS units are formed on the second sacrificial layer, a protective layer is further formed on the second sacrificial layer and fills the first groove to form a first protrusion; and the number of the first and second groups,

after the third sacrificial layer is formed, etching the third sacrificial layer to form a plurality of second grooves, wherein the positions of the second grooves correspond to the vibration film formed on the third sacrificial layer; and when a vibrating membrane is formed on the third sacrificial layer, the vibrating membrane formed on the third sacrificial layer fills the second groove to form a second protrusion.

Optionally, before releasing the first sacrificial layer, the second sacrificial layer, and the third sacrificial layer, the method further includes:

and forming a pad group on the third sacrificial layer, wherein each pad group corresponds to two MEMS unit groups of the same level, each pad group comprises at least three pads, and the two MEMS unit groups of the same level output MEMS signals together through the corresponding pad groups.

Optionally, when each vibration film is formed, a corresponding vibration film lead and a vibration film contact point are also synchronously formed, and the vibration film lead is used for electrically connecting the vibration film contact point with the corresponding vibration film; when each backboard electrode is formed, a corresponding backboard lead and a backboard contact point are also synchronously formed, the backboard lead is used for electrically connecting the backboard contact point with the corresponding backboard electrode, and a pad in the pad group is electrically connected with the corresponding vibrating diaphragm contact point or the corresponding backboard contact point.

Optionally, the vibrating membranes of the corresponding MEMS units in the two MEMS unit groups at the same stage share one vibrating membrane contact point and one bonding pad and are directly electrically connected; or the back plate electrodes of the corresponding MEMS units in the two MEMS unit groups at the same level share one back plate contact point and one bonding pad and are directly and electrically connected.

Optionally, the vibrating membranes of two corresponding MEMS units in two MEMS unit groups at the same stage respectively correspond to one vibrating membrane contact point and one bonding pad, and the two corresponding bonding pads are electrically connected; or the vibrating membranes of two corresponding MEMS units in two MEMS unit groups at the same level respectively correspond to one vibrating membrane contact point and one bonding pad, and the two corresponding bonding pads are electrically connected.

Optionally, after the first sacrificial layer, the second sacrificial layer, and the third sacrificial layer are released, the remaining first sacrificial layer, second sacrificial layer, and third sacrificial layer respectively form a first support layer, a second support layer, and a third support layer, the first support layer, the second support layer, and the third support layer form a support fence, and in two MEMS unit groups of the same stage, the third support layer covers edges of back plate electrodes of all the MEMS units of one or two MEMS unit groups; alternatively, the third support layer covers the edges of the diaphragms of all the MEMS elements of one or both of the groups of MEMS elements.

The MEMS device comprises at least two MEMS unit groups prepared on the same substrate, each MEMS unit group comprises a plurality of MEMS units, each two MEMS unit groups are in the same level, the relative positions of a back plate and a vibrating diaphragm of the MEMS units in the two MEMS unit groups in the same level are different, and at least one MEMS unit in one MEMS unit group is electrically connected with at least one MEMS unit in the other MEMS unit group. In the invention, the two MEMS unit groups at the same level can realize transverse difference, compared with longitudinal difference, the transverse difference structure is easier to prepare, and the capacitances of the two MEMS unit groups are easier to match; moreover, the MEMS signals output by the MEMS unit groups of different levels can realize signal cascade subsequently, and can be used for manufacturing an MEMS system with a multistage cascade structure, so that the sensitivity and the signal-to-noise ratio are improved.

Drawings

Fig. 1 is a flowchart of a method for manufacturing a MEMS device according to an embodiment of the present invention;

fig. 2a to fig. 2q are schematic structural diagrams corresponding to respective steps of a method for manufacturing a MEMS device according to an embodiment of the present invention;

fig. 3a and fig. 3b are schematic structural diagrams of a MEMS device according to a second embodiment of the present invention;

fig. 4 is a schematic structural diagram of a MEMS device according to a third embodiment of the present invention;

fig. 5 is a schematic structural diagram of a MEMS device according to a fourth embodiment of the present invention;

fig. 6n and fig. 6o are schematic structural diagrams corresponding to respective steps of a method for manufacturing an MEMS device according to a fifth embodiment of the present invention;

fig. 7a and 7b are schematic structural diagrams of a MEMS device according to a sixth embodiment of the present invention;

fig. 8 is a schematic structural diagram of a MEMS device according to a seventh embodiment of the present invention;

fig. 9 is a schematic structural diagram of a MEMS device according to an eighth embodiment of the present invention;

fig. 10 is a top view of a MEMS device according to a ninth embodiment of the invention;

fig. 11 is a top view of a MEMS device according to a tenth embodiment of the present invention;

fig. 12 is a top view of a MEMS device according to an eleventh embodiment of the invention;

wherein the reference numerals are:

01. 02, 03, 04-MEMS unit group; 011. 012, 021, 022, 031, 041-MEMS microphone; 100-a substrate; 110-a first acoustic chamber; 120-a second acoustic cavity; 201-a first sacrificial layer; 202-a second sacrificial layer; 203-a third sacrificial layer; 202 a-a first groove; 202 b-a first projection; 203 a-a second groove; 203 b-a second projection; 301 — a first protective layer; 302-a second protective layer; 302-a third protective layer; 304-a fourth protective layer; 324-a second opening; 304 a-a first opening; 401 — first backplane electrode; 402-first backplane leads; 401 a-a first release aperture; 403-first backplane contact points; 403 a-first backplane contact holes; 500-a third diaphragm; 501-a first diaphragm; 502-a first diaphragm lead; 511-a second diaphragm; 512-a second diaphragm lead; 600-diaphragm contact point; 600 a-diaphragm contact hole; 610-a first diaphragm contact point; 610 a-first diaphragm contact hole; 620-second diaphragm contact point; 700-a third backplane electrode; 701-a second backplane electrode; 701 a-a second release aperture; 702-second backplane leads; 703-second backplane contact points; 703 a-second backplane contact holes; 743 — a backplane contact; 800-backplane pads; 801-first backplane pad; 802-second backplane pad; 803-diaphragm pad; 803 a-first diaphragm pad; 803 b-second diaphragm pad;

910 — a first conductive layer; 920-a third conductive layer; 50-a fourth conductive layer; 70-a fifth conductive layer; 51. 52-a seventh conductive layer; 71. 72-sixth conductive layer.

Detailed Description

The following describes in more detail embodiments of the present invention with reference to the schematic drawings. The advantages and features of the present invention will become more apparent from the following description. It is to be noted that the drawings are in a very simplified form and are not to precise scale, which is merely for the purpose of facilitating and distinctly claiming the embodiments of the present invention.

Example one

The embodiment provides a MEMS device, which includes at least two MEMS unit groups prepared on the same substrate, each of the MEMS unit groups includes a plurality of MEMS units, every two of the MEMS unit groups belong to the same stage, the relative positions of the back plate and the diaphragm of the MEMS unit in the two MEMS unit groups of the same stage are different, and at least one MEMS unit in one MEMS unit group is electrically connected with at least one MEMS unit in another MEMS unit group.

The MEMS device provided in this embodiment will be described in detail below by taking the MEMS elements as MEMS microphones. However, it should be understood that the MEMS unit in this embodiment is not limited to the MEMS microphone, and may also be other MEMS device units such as a MEMS force sensor, a MEMS acoustic transducer, or a MEMS microphone, and will not be described in detail herein.

Fig. 2q is a top view of a MEMS device. As shown in fig. 2q, the MEMS device comprises two MEMS element groups belonging to the same stage. The two MEMS unit groups are respectively a first MEMS unit group and a second MEMS unit group. For convenience of description, the first MEMS element group is referred to as a MEMS element group 01, the second MEMS element group is referred to as a MEMS element group 02, and the MEMS element group 01 and the MEMS element group 02 are both prepared on a substrate 100.

It should be understood that the MEMS device provided by the present invention is not limited to have two MEMS element groups, and as an alternative embodiment, the MEMS device may further have four, six, or eight even number of MEMS element groups, and the like, where each two MEMS element groups belong to the same stage, for example, when the MEMS device has four MEMS element groups, the MEMS device has two stages, and when the MEMS device has six MEMS element groups, the MEMS device has three stages, and the MEMS signal output by each stage may subsequently implement signal cascading, and may be used to fabricate a MEMS system with a multistage cascading structure, so as to improve sensitivity and signal-to-noise ratio, and redundant description is omitted here.

Further, the MEMS unit group 01 and the MEMS unit group 02 each have one MEMS unit, wherein the MEMS unit in the MEMS unit group 01 is a MEMS microphone 011, and the MEMS unit in the MEMS unit group 02 is a MEMS microphone 021. The MEMS microphone 011 and the MEMS microphone 021 form an MEMS differential pair after being electrically connected.

The MEMS unit group 01 and the MEMS unit group 02 correspond to a pad group, the MEMS unit group 01 and the MEMS unit group 02 respectively output a first MEMS signal and a second MEMS signal through a pad in the pad group, and because the capacitance variation of the MEMS unit group 01 and the MEMS unit group 02 in the stimulated state is reversed, the MEMS microphone 011 in the MEMS unit group 01 and the MEMS microphone 021 in the MEMS unit group 02 are connected through the pad in the pad group, and the first MEMS signal and the second MEMS signal form an MEMS differential signal.

In this embodiment, the MEMS microphone 011 is an MEMS microphone with a diaphragm above a back plate electrode, and the MEMS microphone 021 is an MEMS microphone with a diaphragm below a back plate electrode.

FIG. 2p is a cross-sectional view of FIG. 2q taken along the direction BC, CO, OD and DA. As shown in fig. 2p and 2q, the MEMS microphone 011 and the MEMS microphone 021 are both prepared on the substrate 100. Wherein the MEMS microphone 011 comprises a first diaphragm 501 and a first backplate structure; the MEMS microphone 021 includes a second diaphragm 511 and a second backplate structure.

Further, the substrate 100 is used for supporting a device, and a supporting wall is formed on the substrate 100, and the supporting wall encloses a first cavity and a second cavity. The first diaphragm 501 is suspended in the first cavity and has an edge extending into the supporting wall for fixing, and the first backplate structure is located below the first diaphragm 501 and has an edge extending into the supporting wall for fixing. A certain distance is provided between the lower surface of the first diaphragm 501 and the first backplate structure, so that the first diaphragm 501 can vibrate up and down in the first cavity. Similarly, the second diaphragm 511 is suspended in the second cavity and fixed by extending its edge into the supporting wall, and the second backplate structure is located above the second diaphragm 511 and fixed by extending its edge onto the supporting wall. The upper and lower surfaces of the second diaphragm 511 are spaced from the second backplate structure and the substrate 100 by a certain distance, so that the second diaphragm 511 can vibrate up and down in the second cavity.

Referring to fig. 2p and fig. 2q, in the present embodiment, the substrate 100 has a first acoustic cavity 110 and a second acoustic cavity 120 therein, the first acoustic cavity 110 and the second acoustic cavity 120 penetrate through the substrate 100 and are respectively communicated with the first cavity and the second cavity, and the cross-sectional shapes of the first acoustic cavity 110 and the second acoustic cavity 120 along the thickness direction may be an inverted trapezoid, a square, or a hexagon.

In this embodiment, the support wall includes three stacked film layers, and for convenience of description, the three film layers of the support wall sequentially stacked on the substrate 100 are referred to as a first support layer, a second support layer, and a third support layer. Edges of the first and second diaphragms 501 and 511 are fixed by being sandwiched between the second and third support layers. In this way, the heights of the first cavity and the second cavity can be controlled by controlling the thickness of the support wall, and the vibration spaces of the first vibration film 501 and the second vibration film 511 can be adjusted by adjusting the thickness ratio of the two adjacent film layers constituting the support wall. Typically, the spacing between the first diaphragm 501 and the first backplate structure and the second diaphragm 511 and the second backplate structure may each be from 1 micron to 7 microns.

In this embodiment, the cross-sectional shapes of the first cavity and the second cavity in the thickness direction are substantially inverted T-shaped, but the invention is not limited thereto.

As an alternative embodiment, the first and second diaphragms 501 and 511 may each include a diaphragm body including a middle portion and a peripheral portion surrounding the middle portion, an edge of the peripheral portion extending into the support wall. The diaphragm body is further provided with a corrugated structure for connecting the middle part and the peripheral part, the corrugated structure is a concentric annular corrugated part on the diaphragm body, and the middle part and the corrugated structure of the diaphragm body are parts of a movable area (a part which is not clamped by the support wall body). Alternatively, the corrugation structure may be a spiral corrugation, and the curvature radius of the thread of the corrugation structure is not changed or is changed with the position, for example, the curvature radius of each spiral thread is the same. The corrugation structure can be selected according to the requirements of practical application.

Compared with the diaphragm with a flat surface, the first diaphragm 501 and the second diaphragm 511 with the corrugated structure can improve the elastic characteristics of the diaphragm, control a part of movable area, improve the elastic coefficient of the diaphragm structure, and meet the requirement of performance design of the MEMS microphone. Further, the corrugated structure may extend to the peripheral portions of the first and second diaphragms 501 and 511, effectively releasing the stress of the first and second diaphragms 501 and 511, and improving the sensitivity of the MEMS microphone. Moreover, since the outer contour of the corrugated structure is located in the range of the first acoustic cavity 110 and the second acoustic cavity 120, the problem of reliability reduction of the MEMS microphone due to process fluctuation in mass production can be avoided, and the overall performance of the product can be improved.

Further, as an alternative embodiment, the middle portion of the diaphragm body has a relief hole therein for releasing stress and adjusting the frequency response curve (frequency response) of the microphone, and the relief hole penetrates the diaphragm body. The gas release hole is not limited to be one, can also be 2, 3, 4 or 5 etc, the gas release hole also is not limited to only be located the center of diaphragm body, can also be located one side of diaphragm body, perhaps, when the gas release hole is two at least, the gas release hole can also be followed the center circumference evenly distributed of diaphragm body, and here is no longer redundantly described.

With reference to fig. 2p and fig. 2q, the first backplane structure includes a first passivation layer 301, a second passivation layer 302, and a first backplane electrode 401. The first backplane electrode 401 is located between the first protection layer 301 and the second protection layer 302 to form a sandwich structure. The first protective layer 301 and the second protective layer 302 are each composed of any one of a Boron Nitride (BN) layer, a silicon nitride (SIN) layer, a silicon boron nitride (SIBN) layer, a borophosphosilicate glass (BPSG) layer, and a phosphosilicate glass (PSG) layer, in this embodiment, the first protective layer 301 and the second protective layer 302 are each a boron nitride layer.

The second backplane structure includes a third protection layer 303, a fourth protection layer 304, and a second backplane electrode 701. The second backplane electrode 701 is located between the third passivation layer 303 and the fourth passivation layer 304 to form a sandwich structure. The third protective layer 303 and the fourth protective layer 304 are each composed of any one of a Boron Nitride (BN) layer, a silicon nitride (SIN) layer, a silicon boron nitride (SIBN) layer, a borophosphosilicate glass (BPSG) layer, and a phosphosilicate glass (PSG) layer, and in this embodiment, the third protective layer 303 and the fourth protective layer 304 are each a boron nitride layer.

The first diaphragm 501 has a first protrusion 202b facing the first backplate structure, so as to prevent the first diaphragm 501 from adhering to the first backplate structure when vibrating to a large extent, thereby resulting in the loss of function of the MEMS microphone 011. The third protection layer 303 has a second protrusion 203b facing the second diaphragm 511, so as to prevent the second diaphragm 511 from being adhered to the second backplate structure when vibrating to a large extent, thereby preventing the MEMS microphone 021 from losing its function.

Optionally, the first protrusion 202b and the second protrusion 203b may be a polygonal pyramid, a polygonal prism, a cone, or a cylinder; the first protrusion 202b and the second protrusion 203b have a diameter of, for example, 0.5 to 1.5 micrometers, and a height of, for example, 0.5 to 1.5 micrometers.

It should be understood that the first protection layer 301 and the fourth protection layer 304 may act as a mechanical support layer for the first backplane electrode 401 and the second backplane electrode 701, respectively, to provide rigidity, such that the first backplane electrode 401 and the second backplane electrode 701 maintain a non-deformed state in an operating state. The second protective layer 302 can prevent the loss of mechanical bias voltage between the first diaphragm 501 and the first backplate electrode 401 due to contact leakage, and the third protective layer 303 can prevent the loss of mechanical bias voltage between the second diaphragm 511 and the second backplate electrode 701 due to contact leakage.

In this embodiment, the thickness of the first protective layer 301 and the fourth protective layer 304 is, for example, 0.08 to 0.25 micrometers; the thickness of the second protective layer 302 and the third protective layer 303 is, for example, 0.1 to 1.5 micrometers; the thickness of the first backplane electrode 401 and the second backplane electrode 701 is, for example, 0.3 to 1 micron.

In this embodiment, in a direction perpendicular to the thickness direction, the cross-sectional area of the first diaphragm 501 is larger than the maximum cross-sectional area of the first acoustic cavity 110, the cross-sectional area of the second diaphragm 511 is larger than the maximum cross-sectional area of the second acoustic cavity 120, the cross-sectional area of the first backplate electrode 401 is smaller than or equal to the minimum cross-sectional area of the first acoustic cavity 110, and the cross-sectional area of the second backplate electrode 701 is smaller than or equal to the minimum cross-sectional area of the second acoustic cavity 120. It should be noted that, when the cross-sectional shapes of the first acoustic cavity 110 and the second acoustic cavity 120 in the thickness direction are square, the cross-sectional areas of the first acoustic cavity 110 and the second acoustic cavity 120 are the same, and the only cross-sectional area is the minimum cross-sectional area; when the cross-sectional shapes of the first acoustic cavity 110 and the second acoustic cavity 120 in the thickness direction are an inverted trapezoid, a trapezoid, or a hexagon, the cross-sectional areas of the first acoustic cavity 110 and the second acoustic cavity 120 at the upper surface or the lower surface of the substrate 100 are the smallest. In some embodiments, the radius of the smallest cross-sectional area of the first acoustic cavity 110 and the second acoustic cavity 120 is 250 micrometers to 600 micrometers.

Alternatively, the first back plate electrode 401 is formed under a part of the movable region of the first diaphragm 501, and the first back plate electrode 401 and the first diaphragm 501 form two plates of a capacitor. The area of the first backplate electrode 401 is smaller than or equal to the area of the partial movable region of the first diaphragm 501, in this embodiment, the area of the first backplate electrode 401 is smaller than the area of the partial movable region of the first diaphragm 501, for example, the area of the first backplate electrode 401 is 70% to 100% of the area of the partial movable region of the first diaphragm 501, and since the area of the first backplate electrode 401 is smaller than or equal to the area of the partial movable region of the first diaphragm 501, an ineffective capacitance component is removed from the detection signal, so that the sensitivity of the detection signal is only related to the effective capacitance component, thereby improving the sensitivity of the MEMS microphone 011.

Similarly, the second back plate electrode 701 is formed above a part of the movable region of the second diaphragm 511, and the second back plate electrode 701 and the second diaphragm 511 constitute two plates of a capacitor. The area of the second back plate electrode 701 is smaller than or equal to the area of the partial movable region of the second diaphragm 511, in this embodiment, the area of the second back plate electrode 701 is smaller than the area of the partial movable region of the second diaphragm 511, for example, the area of the second back plate electrode 701 is 70% to 100% of the area of the partial movable region of the second diaphragm 511, and since the area of the second back plate electrode 701 is smaller than or equal to the area of the partial movable region of the second diaphragm 511, the invalid capacitance component is removed from the detection signal, so that the sensitivity of the detection signal is only related to the effective capacitance component, thereby improving the sensitivity of the MEMS microphone 021.

Optionally, the first backplane electrode 401 and the second backplane electrode 701 may have a circular shape, a concentric circular ring shape, a circular shape with a radial strip beam at an edge, a triangular shape, a square shape, or other geometric shapes, which is not limited in the present invention.

Further, the first backplane structure has a first release hole array therein, the first release hole array includes a plurality of first release holes 401a, and the first release holes 401a penetrate through the second protection layer 302, the first backplane electrode 401 and the first protection layer 301. The second backplane structure has a second array of release holes therein, the second array of release holes includes a plurality of second release holes 701a, and the second release holes 701a penetrate through the fourth protection layer 304, the second backplane electrode 701, and the third protection layer 303. The first release hole 401a and the second release hole 701a may have a circular or polygonal shape. The first release hole 401a and the second release hole 701a not only serve as a supply channel of an etchant in a manufacturing process, but also serve as a sound hole in a finally formed MEMS microphone to reduce acoustic resistance.

In this embodiment, the first diaphragm 501, the second diaphragm 511, the first back plate electrode 401 and the second back plate electrode 701 are all made of doped polysilicon, or may be made of metal materials such as aluminum, copper, gold, titanium, nickel, tungsten and alloys thereof, so that the first diaphragm 501, the second diaphragm 511, the first back plate electrode 401 and the second back plate electrode 701 have conductivity.

The first vibration film 501 and the second vibration film 511 are located on the same layer, and the first back plate electrode 401 and the second back plate electrode 701 are distributed on two sides of the layer. That is, the first back-plate electrode 401 is located at a first layer, the first diaphragm 501 and the second diaphragm 511 are located at a third layer, the second back-plate electrode 701 is located at a second layer, the third layer is located between the first layer and the second layer, and the first layer is closer to the substrate than the second layer. In this embodiment, the first layer is located at a junction between the first supporting layer and the second supporting layer, the second layer is located on the third supporting layer, and the third layer is located at a junction between the second supporting layer and the third layer.

In this embodiment, the MEMS microphone 011 further includes a first diaphragm lead 502 disposed on the same layer as the first diaphragm 501, the MEMS microphone 021 further includes a second diaphragm lead 512 disposed on the same layer as the second diaphragm 511, the first diaphragm lead 502 and the second diaphragm lead 512 are disposed on the same layer as the diaphragm contact point 600, and the diaphragm contact point 600 is located between the first diaphragm lead 502 and the second diaphragm lead 512. The first diaphragm 501 and the second diaphragm 511 share the diaphragm contact point 600, the first diaphragm 501 is electrically connected to the diaphragm contact point 600 through the first diaphragm lead 502, and the second diaphragm 511 is electrically connected to the diaphragm contact point 600 through the second diaphragm lead 512. In this way, the first diaphragm 501 and the second diaphragm 511 are directly electrically connected through the first diaphragm lead 502, the second diaphragm lead 512 and the diaphragm contact point 600.

Further, the MEMS microphone 011 further has a first backplane lead 402 and a first backplane contact 403, the first backplane lead 402 and the first backplane contact 403 are disposed on the same layer as the first backplane electrode 401, and the first backplane electrode 401 is electrically connected to the first backplane contact 403 through the first backplane lead 402. Similarly, the MEMS microphone 021 further has a second backplate lead 702 and a second backplate contact point 703, the second backplate lead 702 and the second backplate contact point 703 are disposed on the same layer as the second backplate electrode 701, and the second backplate electrode 701 is electrically connected to the second backplate contact point 703 through the second backplate lead 702.

Further, in this embodiment, the pad group of the MEMS unit group 01 and the pad group of the MEMS unit group 02 includes three pads, which are the first backplate pad 801, the second backplate pad 802, and the diaphragm pad 803. The first backplate pad 801 passes through the support wall (third support layer and second support layer) and is electrically connected to the first backplate contact 403, the second backplate pad 802 passes through the fourth protective layer 304 and is electrically connected to the second backplate contact 703, and the diaphragm pad 803 passes through the fourth protective layer 304, the third protective layer 303 and the support wall (third support layer) and is electrically connected to the diaphragm contact 600. Thus, the first backplate pad 801 can be electrically connected to the first backplate electrode 401, the second backplate pad 802 is electrically connected to the second backplate electrode 701, the diaphragm pad 803 is electrically connected to the first diaphragm 501 and the second diaphragm 511, and the first diaphragm 501 and the second diaphragm 511 share the diaphragm pad 803. Thus, bias voltage can be applied to the MEMS microphone 011 and the MEMS microphone 021 through the pad group, and the pad group can also output the MEMS differential signal commonly output by the MEMS microphone 011 and the MEMS microphone 021.

It should be understood that, as an alternative embodiment, the number of the pads in the pad group is not limited to three, and may be more than three. Since there are three pads in this embodiment and three contact points accordingly, as an alternative embodiment, the number of contact points may also increase as the number of pads increases.

In this embodiment, the pad is made of a conductive material, such as any one of aluminum, gold, copper, nickel, titanium, chromium, or an alloy thereof, and has a thickness of, for example, 1 to 2 micrometers.

Further, the MEMS unit group 01 and the MEMS unit group 02 are arranged in a first direction, and the MEMS microphone 011 and the MEMS microphone 021 are aligned in the first direction. As such, the MEMS microphones 011 and 021 are also arranged in a first direction on the substrate 100; of course, the MEMS unit group 01 and the MEMS unit group 02 may be arranged along a second direction, and the MEMS microphone 011 and the MEMS microphone 021 are aligned in the second direction. As such, the MEMS microphones 011 and 021 are also arranged in the second direction on the substrate 100. In this embodiment, the first direction is a row direction, the second direction is a column direction, and as an optional embodiment, the first direction and the second direction are not limited to the row direction and the column direction, and the first direction and the second direction may be perpendicular or not.

Based on this, the present embodiment further provides a method for manufacturing a MEMS device, and fig. 1 is a flowchart of the method for manufacturing the MEMS device provided in the present embodiment. As shown in fig. 1, the method for manufacturing the MEMS device includes:

step S100: providing a substrate;

step S200: the method comprises the steps that at least two MEMS unit groups are prepared on the substrate, every two MEMS unit groups are in the same level, the relative positions of a back plate and a diaphragm of the MEMS units of the two MEMS unit groups in the same level are different, and at least one MEMS unit in one MEMS unit group is electrically connected with at least one MEMS unit in the other MEMS unit group.

Fig. 2a to fig. 2q are schematic structural diagrams corresponding to corresponding steps of the method for manufacturing the MEMS device provided in this embodiment. Next, a method for manufacturing the MEMS device will be described in detail with reference to fig. 2a to 2 q. In this embodiment, a method for manufacturing the MEMS device will be described in detail, taking as an example that all the MEMS elements are MEMS microphones and all the MEMS microphones are manufactured simultaneously, for convenience, fig. 2a to 2q only show the steps of manufacturing the MEMS device having a MEMS element group 01 and a MEMS element group 02, the MEMS element group 01 having a MEMS microphone 011, and the MEMS element group 02 having a MEMS microphone 021.

Referring to fig. 2a, step S100 is performed to provide a substrate 100, for example, the substrate 100 is a silicon wafer with a <100> crystal orientation, and the doping type of the substrate 100 is N-type, but it should be understood that the invention is not limited to the crystal orientation and the doping type of the substrate 100.

Further, for convenience of description, the substrate 100 is divided into regions, wherein a BO region is a region for forming the MEMS microphone 021, an AO region is a region for forming the MEMS microphone 011, and points C and D are centers of the MEMS microphone 021 and the MEMS microphone 011, respectively.

With reference to fig. 2a, step S200 is executed to form a first sacrificial layer 201 on the substrate 100, where the first sacrificial layer 201 is, for example, a silicon oxide layer. The method of forming the first sacrificial layer 201 is, for example: a silicon oxide layer is formed on the substrate 100 by thermal oxidation, low pressure chemical vapor deposition or plasma enhanced chemical vapor deposition, as the first sacrificial layer 201, in this embodiment, a part of the first sacrificial layer 201 will be used as a sacrificial layer for forming a part of the cavity, and the thickness of the first sacrificial layer 201 is, for example, 0.5 to 2 micrometers.

Referring to fig. 2b, a first protection layer 301 is formed on the first sacrificial layer 201. The method for forming the first protective layer 301 is, for example: a boron nitride layer is formed on the first sacrificial layer 201 by a plasma enhanced chemical vapor deposition method.

Referring to fig. 2c, a first backplane electrode 401, a first backplane lead 402 and a first backplane contact 403 are formed on a portion of the surface of the first protection layer 301, the first backplane lead 402 is used to electrically connect the first backplane electrode 401 with the first backplane contact 403, and the first backplane electrode 401, the first backplane lead 402 and the first backplane contact 403 are only located in the AO region. In this embodiment, the first backplane electrode 401, the first backplane lead 402, and the first backplane contact 403 are all located on the same layer and are all made of doped polysilicon. The method for forming the first backplane electrode 401, the first backplane lead 402, and the first backplane contact 403 is, for example: a doped polysilicon layer is formed on a portion of the surface of the first protective layer 301 using Low Pressure Chemical Vapor Deposition (LPCVD). The polysilicon layer is then patterned using photolithography and etching steps to form the pattern of the first backplane electrode 401, first backplane lead 402 and first backplane contact 403.

With reference to fig. 2c, a second passivation layer 302 is formed on the first backplane electrode 401, the first backplane lead 402, and the first backplane contact 403, and on the remaining surface of the first passivation layer 301. The method for forming the second protective layer 302 is, for example: the conformal boron nitride layer is formed by Plasma Enhanced Chemical Vapor Deposition (PECVD) or Low Pressure Chemical Vapor Deposition (LPCVD).

Referring to fig. 2d, the second protection layer 302 and the first protection layer 301 in the BO area are removed by etching, so that the surface of the first sacrificial layer 201 in the BO area is exposed.

Referring to fig. 2e, a plurality of first release holes 401a penetrating through the second passivation layer 302, the first backplane electrode 401 and the first passivation layer 301 are formed, and the plurality of first release holes 401a form a first release hole array, and the first release hole array is located in the AO region. The first release holes 401a are formed, for example, by: forming a resist layer on the surface of the second protective layer 302, and forming a pattern including an opening in the resist layer by using a photolithography process; the first release holes 401a are formed by removing the respective exposed portions of the second protective layer 302, the first backplane electrode 401, and the first protective layer 301 with a selective etchant using the resist layer as a mask. After etching, the resist layer may be removed by ashing or dissolution in a solvent.

As an alternative embodiment, a special deep trench etcher may be used to form the first release hole 401 a.

After the etching is completed, the remaining first protection layer 301, the first backplane electrode 401 and the second protection layer 302 are only located in the AO region and jointly form a first backplane structure, and the first backplane lead 402 and the first backplane contact 403 are also located in the AO region and are used for leading out the first backplane electrode 401 in the first backplane structure.

Referring to fig. 2f, a second sacrificial layer 202 is formed on the first backplate structure and the first sacrificial layer 201 in the BO area, and a plurality of first grooves 202a are formed on the upper surface of the second sacrificial layer 202, wherein the first grooves 202a are located in the AO area and correspond to the first backplate structure. In this embodiment, the second sacrificial layer 202 is a silicon oxide layer. The method for forming the second sacrificial layer 202 is, for example: as the second sacrificial layer 202, a silicon oxide layer is formed by a Low Pressure Chemical Vapor Deposition (LPCVD) or a Plasma Enhanced Chemical Vapor Deposition (PECVD). After the second sacrificial layer 202 is formed, the upper surface of the second sacrificial layer 202 is planarized, for example, using a chemical mechanical planarization process.

Similarly, a portion of the second sacrificial layer 202 will act as a sacrificial layer to form part of the cavity, and the thickness of the second sacrificial layer 202 is also used to define the spacing between the first backplate structure and the subsequently formed first diaphragm. The thickness of the second sacrificial layer 202 is chosen according to the electrical and acoustic properties of the MEMS microphone, for example 2 to 4 microns.

The first groove 202a is an opening of the surface of the second sacrificial layer 202 and extends downward. The first groove 202a may have a polygonal shape such as a circular hole, a square hole, or a triangular hole, when viewed from the surface of the second sacrificial layer 202. The first groove 202a has a rectangular shape or a trapezoidal shape or a V-shape having a bottom surface smaller than an opening surface when viewed from a cross section of the first groove 202 a.

The step of forming the first groove 202a may be: a resist layer is formed on the surface of the second sacrificial layer 202, and a pattern including an opening is formed in the resist layer by a photolithography process. The exposed portions of the second sacrificial layer 202 are removed with a selective etchant using the resist layer as a mask, thereby forming a plurality of first grooves 202 a. By controlling the etching time, the etching can be stopped at a predetermined depth to the second sacrificial layer 202. After etching, the resist layer may be removed by ashing or dissolution in a solvent.

Referring to fig. 2g, a first diaphragm 501, a second diaphragm 511, a first diaphragm lead 502, a second diaphragm lead 512 and a diaphragm contact point 600 are formed on the second sacrificial layer 202. The first vibration film 501 and the first vibration film lead 502 are located in an AO region, the second vibration film 511 and the second vibration film lead 512 are located in a BO region, the vibration film contact point 600 is located at a junction of the AO region and the BO region, and the first vibration film 501, the second vibration film 511, the first vibration film lead 502, the second vibration film lead 512 and the vibration film contact point 600 are all located on the same layer and are all composed of doped polycrystalline silicon. The first diaphragm lead 502 is used to electrically connect the first diaphragm 501 with the diaphragm contact point 600, and the second diaphragm lead 512 is used to electrically connect the second diaphragm 211 with the diaphragm contact point 600.

Further, the first diaphragm 501 fills the first recess 202a, thereby forming a first protrusion 202b for preventing the first diaphragm 501 from adhering to the first backplate structure, the shape of the first protrusion 202b conforming to the shape of the first recess 202 a.

The first diaphragm 501, the second diaphragm 511, the first diaphragm lead 502, the second diaphragm lead 512 and the diaphragm contact point 600 are formed by, for example: depositing polysilicon on the second sacrificial layer 202 by Low Pressure Chemical Vapor Deposition (LPCVD); and patterning the polysilicon layer by adopting photoetching and etching steps, so that the first vibration film 501, the second vibration film 511, the first vibration film lead 502, the second vibration film lead 512 and the vibration film contact point 600 are respectively formed in different areas of the polysilicon layer.

Referring to fig. 2h, a third sacrificial layer 203 is formed on the first vibration film 501, the second vibration film 511, the first diaphragm lead 502, the second diaphragm lead 512 and the diaphragm contact point 600, and a plurality of second grooves 203a are formed on the surface of the third sacrificial layer 203, wherein the second grooves 203a are located in a BO area and correspond to the second vibration film 511 in position. In this embodiment, the third sacrificial layer 203 is a silicon oxide layer. The method of forming the third sacrificial layer 203 is, for example: as the third sacrificial layer 203, a silicon oxide layer is formed by a Low Pressure Chemical Vapor Deposition (LPCVD) or a Plasma Enhanced Chemical Vapor Deposition (PECVD) method. After the third sacrificial layer 203 is formed, the upper surface of the third sacrificial layer 203 is planarized, for example, using a chemical mechanical planarization process.

Similarly, a portion of the third sacrificial layer 203 will act as a sacrificial layer to form a portion of the cavity, and the thickness of the third sacrificial layer 203 is also used to define the spacing between the second diaphragm 511 and the subsequently formed second backplate structure. The thickness of the third sacrificial layer 203 is chosen according to the electrical and acoustic properties of the MEMS microphone, for example 2 to 4 microns.

The second groove 203a is an opening of the surface of the third sacrificial layer 203 and extends downward. The second groove 203a may have a polygonal shape such as a circular hole, a square hole, or a triangular hole, when viewed from the surface of the third sacrificial layer 203. The second groove 203a has a rectangular shape or a trapezoidal shape or a V-shape having a bottom surface smaller than an opening surface when viewed from a cross section of the second groove 203 a.

The step of forming the second groove 203a may be: a resist layer is formed on the surface of the third sacrificial layer 203, and a pattern including an opening is formed in the resist layer by a photolithography process. The exposed portions of the third sacrificial layer 203 are removed with a selective etchant using the resist layer as a mask, thereby forming a plurality of second grooves 203 a. By controlling the etching time, the etching can be stopped at a predetermined depth to the third sacrificial layer 203. After etching, the resist layer may be removed by ashing or dissolution in a solvent.

Referring to fig. 2i, a third passivation layer 303 is formed on the third sacrificial layer 203. The third protective layer 303 is formed, for example, by: the conformal boron nitride layer is formed by Plasma Enhanced Chemical Vapor Deposition (PECVD) or Low Pressure Chemical Vapor Deposition (LPCVD).

The first protective layer 510 fills the second groove 203a to form a second protrusion 203b for preventing the second diaphragm 511 from adhering to the second backplate structure, and the shape of the second protrusion 203b conforms to the shape of the second groove 203 a.

With reference to fig. 2i, a second backplane electrode 701, a second backplane lead 702 and a second backplane contact 703 are formed on a portion of the surface of the third protection layer 303. The second backplane lead 702 is used to electrically connect the second backplane electrode 701 and the second backplane contact 703, and the second backplane electrode 701, the second backplane lead 702, and the second backplane contact 703 are only located in the BO area. In this embodiment, the second backplane electrode 701, the second backplane lead 702, and the second backplane contact 703 are all located on the same layer and are all made of doped polysilicon. The method for forming the second backplane electrode 701, the second backplane lead 702, and the second backplane contact 703 includes, for example: a doped polysilicon layer is formed on a portion of the surface of the third protective layer 303 using Low Pressure Chemical Vapor Deposition (LPCVD). Then, the polysilicon layer is patterned by photolithography and etching steps to form the patterns of the second backplane electrode 701, the second backplane lead 702, and the second backplane contact 703.

Referring to fig. 2j, the third protection layer 303 and the third sacrificial layer 203 are etched to form a diaphragm contact hole 600a, and the third protection layer 303, the third sacrificial layer 203 and the second sacrificial layer 202 are etched to form a first backplate contact hole 403 a. The diaphragm contact hole 600a is located above the diaphragm contact point 600 and penetrates through the third protective layer 303 and the third sacrificial layer 203 to expose the surface of the diaphragm contact point 600; the first backplane contact hole 403a is located above the first backplane contact 403, penetrates through the third protection layer 303 and the third sacrificial layer 203 and extends into the second sacrificial layer 202, and the first backplane contact hole 403a does not expose the first backplane contact 403.

Referring to fig. 2k, a fourth passivation layer 304 is formed on the second backplane electrode 701, the second backplane lead 702, and the second backplane contact 703, and on the remaining surface of the third passivation layer 303. The method for forming the fourth protection layer 304 is, for example: the conformal boron nitride layer is formed by Plasma Enhanced Chemical Vapor Deposition (PECVD) or Low Pressure Chemical Vapor Deposition (LPCVD).

Of course, due to the existence of the diaphragm contact hole 600a and the first backplate contact hole 403a, the fourth protection layer 304 also fills a part of the depth of the diaphragm contact hole 600a and the first backplate contact hole 403 a.

Referring to fig. 2l, the fourth passivation layer 304 is etched to form a second backplane contact hole 703a above the second backplane contact point 703; simultaneously removing the fourth protection layer 304 filled in the diaphragm contact hole 600a, so that the surface of the diaphragm contact point 600 is exposed again; and simultaneously removing the fourth protection layer 304 filled in the first backplane contact hole 403a and the second sacrificial layer 202 and the second protection layer 302 at the bottom of the first backplane contact hole 403a, so that the first backplane contact 403 is exposed.

Referring to fig. 2m, conductive materials are filled in the first backplate contact hole 403a, the second backplate contact hole 703a and the diaphragm contact hole 600a, so as to form a first backplate pad 801, a second backplate pad 802 and a diaphragm pad 803 in the first backplate contact hole 403a, the second backplate contact hole 703a and the diaphragm contact hole 600a, respectively. In this way, the first backplane pad 801 may be electrically connected to the first backplane electrode 401 through the first backplane contact 403 and the first backplane lead 402; the second backplane pad 802 is electrically connected to the second backplane electrode 701 through the second backplane contact 703 and the second backplane lead 702; the diaphragm pad 803 is electrically connected to the first diaphragm 501 through the diaphragm contact point 600 and the first diaphragm lead 502, and is electrically connected to the second diaphragm 511 through the diaphragm contact point 600 and the second diaphragm lead 512.

The method for forming the first backplate pad 801, the second backplate pad 802, and the diaphragm pad 803 is, for example: forming a metal layer on the surface of the fourth protection layer 304 by sputtering or evaporation, wherein the metal layer fills the first backplane contact hole 403a, the second backplane contact hole 703a and the diaphragm contact hole 600a and covers the surface of the fourth protection layer 304; the metal layer is patterned using conventional photolithography and etching steps to form the first backplate pad 801, the second backplate pad 802, and the diaphragm pad 803.

Referring to fig. 2n, a plurality of second release holes 701a penetrating through the fourth passivation layer 304, the second backplane electrode 701 and the third passivation layer 303 are formed, and the plurality of second release holes 701a form a second release hole array, which is located in the BO area and corresponds to the second diaphragm 511 in position. The second release holes 701a are formed, for example, by: forming a resist layer on the surface of the fourth protection layer 304, and forming a pattern including an opening in the resist layer by using a photolithography process; the second release holes 701a are formed by removing the respective exposed portions of the fourth protective layer 304, the second backplane electrode 701, and the third protective layer 303 with a selective etchant using the resist layer as a mask. After etching, the resist layer may be removed by ashing or dissolution in a solvent.

As an alternative embodiment, a special deep trench etching machine may be used to form the second release hole 701 a.

Referring to fig. 2o, the first opening 304a is formed by etching to remove a portion of the fourth protection layer 304 in the AO region, and the first opening 304a exposes a surface of the third sacrificial layer 203 in the AO region.

After the etching is completed, the fourth protection layer 304, the second backplane electrode 701 and the third protection layer 303 remaining in the BO area jointly form a second backplane structure, and the second backplane lead 702 and the second backplane contact point 703 are also located in the BO area and are used for leading out the second backplane electrode 701 in the second backplane structure.

With continued reference to fig. 2o, a first acoustic cavity 110 and a second acoustic cavity 120 are formed in the substrate 100, the first acoustic cavity 110 is located in the AO region, and the second acoustic cavity 120 is located in the BO region. In this embodiment, the substrate 100 is thinned to a design value, for example, 350 to 450 microns, preferably 400 microns, by a chemical mechanical planarization process. Then, a resist layer is formed on the lower surface of the substrate 100, and a pattern including an opening is formed in the resist layer using a photolithography process. The exposed portions of the substrate 100 are removed with a selective etchant using the resist layer as a mask, thereby forming the first acoustic cavity 110 and the second acoustic cavity 120. In this embodiment, the first acoustic cavity 110 and the second acoustic cavity 120 are openings having inverted trapezoidal cross-sectional shapes along the thickness direction, and optionally, the first acoustic cavity 110 and the second acoustic cavity 120 may also be openings having square or hexagonal cross-sectional shapes along the thickness direction. After etching, the resist layer may be removed by ashing or dissolution in a solvent.

Alternatively, the first acoustic cavity 110 and the second acoustic cavity 120 are formed by a conventional Bosch process in MEMS technology and a special deep trench etcher.

As an alternative embodiment, the process of etching the back surface of the substrate 100 to form the first acoustic cavity 110 and the second acoustic cavity 120 may also be performed in a hard mask manner, that is, a hard mask layer is formed on the back surface of the substrate 100, then a pattern is formed in the hard mask layer, and the substrate 100 is etched using the hard mask layer as a mask to form the first acoustic cavity 110 and the second acoustic cavity 120.

Referring to fig. 2p, a portion of the first sacrificial layer 201 and a portion of the second sacrificial layer 202 are removed through the first acoustic cavity 110, the second acoustic cavity 120 and the first release hole array, and a portion of the third sacrificial layer 203 is removed through the second release hole array and the first opening 304a, so as to release the first diaphragm 501 and the second diaphragm 511.

In this embodiment, hydrofluoric acid is used as the etchant, and the first acoustic cavity 110, the second acoustic cavity 120, the first release hole array, the second release hole array, and the first opening 304a are used as the access passage of the etchant. The first protective layer 301 and the second protective layer 302 serve as protective films for the first backplane electrode 401, and the third protective layer 303 and the fourth protective layer 304 serve as protective films for the second backplane electrode 701, so that the first backplane electrode 401 and the second backplane electrode 701 are not corroded in the corrosion step.

By using a vapor fumigation method with hydrofluoric acid or a wet etching method with hydrofluoric acid, the hydrofluoric acid contacts the first sacrificial layer 201, the second sacrificial layer 202, and the third sacrificial layer 203 with the first acoustic cavity 110, the second acoustic cavity 120, the first release hole array, the second release hole array, and the first opening 304a as a channel, so as to remove a portion of each of the first sacrificial layer 201, the second sacrificial layer 202, and the third sacrificial layer 203, and to re-expose a portion of the upper and lower surfaces of the first diaphragm 501 and the second diaphragm 511, thereby releasing the first diaphragm 501 and the second diaphragm 511.

After removing a portion of the first sacrificial layer 201, the second sacrificial layer 202, and the third sacrificial layer 203, the remaining first sacrificial layer 201, the second sacrificial layer 202, and the third sacrificial layer 203 respectively constitute a first support layer, a second support layer, and a third support layer of the support wall, so as to support the first vibration film 501 and the second vibration film 511. Meanwhile, the supporting wall encloses a first cavity and a second cavity, the first diaphragm 501 is suspended in the first cavity and divides the first cavity into an upper part and a lower part, and a first release hole (sound hole) 401a in the first release hole array and the first sound cavity 110 are respectively communicated with the lower half part of the first cavity and used for providing an airflow channel during the vibration of the first diaphragm 501; similarly, the second diaphragm 511 is suspended in the second cavity and divides the second cavity into two upper and lower portions, and the second release holes (sound holes) 701a in the second release hole array and the second sound cavity 120 are respectively communicated with the two upper and lower portions of the second cavity to provide an airflow channel during vibration of the second diaphragm 511.

With reference to fig. 2p and fig. 2q, after releasing a part of the first sacrificial layer 201, the second sacrificial layer 202, and the third sacrificial layer 203, an MEMS microphone 011 is formed in an AO region, an MEMS microphone 021 is formed in a BO region, a diaphragm and a back plate electrode of the MEMS microphone 011 are the first diaphragm 501 and the first back plate electrode 401, respectively, and a diaphragm and a back plate electrode of the MEMS microphone 021 are the second diaphragm 511 and the second back plate electrode 701, respectively. The MEMS microphone 011 is a MEMS microphone with a diaphragm above a back plate electrode, and the MEMS microphone 021 is a MEMS microphone with a diaphragm below a back plate electrode.

Example two

Fig. 3a and fig. 3b are schematic structural diagrams of the MEMS device provided in this embodiment, in which fig. 3b is a top view of the MEMS device, and fig. 3a is a cross-sectional view of fig. 3b along BC, CB1, A1D and DA directions. With reference to fig. 3a and 3b, the difference from the first embodiment is that in the present embodiment, two back plate pads and two diaphragm pads are provided, and the pad group corresponding to the MEMS microphone group 01 and the MEMS microphone group 02 has 4 pads.

Specifically, the 4 pads are a first backplate pad 801, a second backplate pad 802, a first diaphragm pad 803a and a second diaphragm pad 803b, respectively. The first backplane pad 801 and the second backplane pad 802 are electrically connected to the first backplane electrode 401 and the second backplane electrode 701, respectively, so as to lead out the first backplane electrode 401 and the second backplane electrode 701, respectively; the first diaphragm pad 803a and the second diaphragm pad 803b are electrically connected to the first diaphragm 501 and the second diaphragm 511, respectively, so as to lead out the first diaphragm 501 and the second diaphragm 511, respectively.

Further, the first diaphragm 501 is electrically connected to a first diaphragm contact point 610 through the first diaphragm lead 502, and the second diaphragm 511 is electrically connected to a second diaphragm contact point 620 through the second diaphragm lead 512. A gap is provided between the first diaphragm contact point 610 and the second diaphragm contact point 620, and the gap is filled with the third sacrificial layer 203, thereby achieving insulation between the first diaphragm contact point 610 and the second diaphragm contact point 620. The first diaphragm pad 803a is located above the first diaphragm contact point 610 and passes through the fourth protective layer 304, the third protective layer 303 and the support wall (third support layer) to be electrically connected to the first diaphragm contact point 610, and the second diaphragm pad 803b is located above the second diaphragm contact point 620 and passes through the fourth protective layer 304, the third protective layer 303 and the support wall (third support layer) to be electrically connected to the second diaphragm contact point 620.

Referring to fig. 3b, in the embodiment, the first diaphragm pad 803a and the second diaphragm pad 803b are electrically connected through the first conductive layer 910, so that the first diaphragm 501 and the second diaphragm 511 can also be electrically connected.

It is understood that the first diaphragm pad 803a and the second diaphragm pad 803b may also be electrically connected not by the first conductive layer 910, but by wire bonding.

It should be understood that the preparation method of the MEMS device in this embodiment is similar to that of the MEMS device in the first embodiment, and only the difference is that two diaphragm contact points need to be prepared when the first diaphragm 501 and the second diaphragm 511 are prepared, and two diaphragm pads and the first conductive layer 910 need to be prepared when the pad group is prepared, and redundant description is omitted here.

EXAMPLE III

Fig. 4 is a schematic structural diagram of the MEMS device provided in this embodiment. As shown in fig. 4, the difference from the second embodiment is that, in this embodiment, there is no third support layer above the first diaphragm 501, the third support layer only covers the edge of the second diaphragm 511, and the first diaphragm 501 is directly disposed on the second support layer and fixed.

With reference to fig. 4, the first diaphragm pad 803a is directly formed on the first diaphragm contact point 610 and electrically connected to the first diaphragm contact point 610, and the first backplate pad 801 passes through the second support layer and the second protective layer 302 and is electrically connected to the first pad contact point 403.

Referring to fig. 4, in the present embodiment, the first diaphragm pad 803a and the second diaphragm pad 803b are electrically connected through a second conductive layer (not shown), so that the first diaphragm 501 and the second diaphragm 511 can be electrically connected. The first diaphragm pad 803a and the second diaphragm pad 803b may be subsequently led out by forming additional pads on the second conductive layer.

It should be understood that the fabrication method of the MEMS device in this embodiment is similar to that of the MEMS device in the second embodiment, except that after the second backplane electrode 701, the second backplane lead 702 and the second backplane contact 703 are formed, and before the fourth protection layer 304 is formed, the AA1 area is masked by a mask; then, before releasing the sacrificial layer, the mask is removed, and when the sacrificial layer is released, the third sacrificial layer in the AA1 area is completely exposed and can be completely removed, so that a third supporting layer is not formed on the AA1 area; then, a first diaphragm pad 803a is formed on the first diaphragm contact point 610, and a first backplate pad 801 is formed on the second support layer.

Example four

Fig. 5 is a schematic structural diagram of the MEMS device provided in this embodiment. As shown in fig. 5, the difference from the first embodiment is that, in this embodiment, there is no third support layer above the first diaphragm 501, the third support layer only covers the edge of the second diaphragm 511, and the first diaphragm 501 is directly disposed on the second support layer and fixed.

With reference to fig. 5, the diaphragm pad 803 is directly formed on the diaphragm contact point 600 and electrically connected to the diaphragm contact point 600, and the first backplate pad 801 passes through the second support layer and the second protective layer 302 and is electrically connected to the first pad contact point 403.

It should be understood that the fabrication method of the MEMS device in this embodiment is similar to that of the MEMS device in the first embodiment, except that after the second backplane electrode 701, the second backplane lead 702 and the second backplane contact 703 are formed, the OA region is masked with a mask before the fourth protection layer 304 is formed; then, before releasing the sacrificial layer, removing the mask, wherein when the sacrificial layer is released, the third sacrificial layer in the OA area is completely exposed and can be completely removed, so that the third supporting layer is not formed on the OA area; the diaphragm pads 803 are then formed on the diaphragm contact points 600 and the first backplate pads 801 are formed on the second support layer.

EXAMPLE five

Fig. 6n and fig. 6o are schematic structural diagrams of the MEMS device provided in this embodiment, where fig. 6o is a top view of the MEMS device, and fig. 6n is a cross-sectional view of fig. 6o along BC, CA1, B1D and DA directions. With reference to fig. 6n and 6o, the difference from the first embodiment is that in the present embodiment, the MEMS microphone 011 is a MEMS microphone with a diaphragm below a back-plate electrode, and the MEMS microphone 021 is a MEMS microphone with a diaphragm above a back-plate electrode.

Referring to fig. 6n as a continuation reference to fig. 6o, the first diaphragm 501, the first and second backplate structures, and the second diaphragm 511 are disposed from bottom to top. That is, the first diaphragm 501 is located in a first layer, the second diaphragm 511 is located in a second layer, the first back-plate electrode 401 and the second back-plate electrode 402 are located in a third layer, the third layer is located between the first layer and the second layer, and the first layer is closer to the substrate 100 than the second layer. In this embodiment, the first layer is located at a junction between the first supporting layer and the second supporting layer, the second layer is located on the third supporting layer, and the third layer is located at a junction between the second supporting layer and the third layer.

Specifically, the first diaphragm 501 is located below the first and second backplate structures, and the edge extends to the position between the first and second support layers for fixing; the second diaphragm 511 is located above the first backplate structure and the second backplate structure, and the edge of the second diaphragm is arranged on the third support layer for fixing; the first back plate structure and the second back plate structure are positioned on the same layer, and the edges of the first back plate structure and the second back plate structure extend to the position between the second supporting layer and the third supporting layer to be fixed. It should be understood that the first protection layer 301 and the fourth protection layer 304 are located on the same layer, the first backplane electrode 401 and the second backplane electrode 701 are located on the same layer, and the second protection layer 302 and the third protection layer 303 are located on the same layer.

Further, the first protection layer 301 has a first protrusion 202b facing the first diaphragm 501, so as to prevent the first diaphragm 501 from adhering to the first backplate structure when vibrating to a large extent, thereby resulting in a loss of function of the MEMS microphone 011. The second diaphragm 511 has a second protrusion 203b facing the second backplate structure, so as to prevent the second diaphragm 511 from adhering to the second backplate structure when vibrating to a large extent, thereby preventing the MEMS microphone 021 from losing its function.

Optionally, the first protrusion 202b and the second protrusion 203b may be a polygonal pyramid, a polygonal prism, a cone, or a cylinder; the first protrusion 202b and the second protrusion 203b have a diameter of, for example, 0.5 to 1.5 micrometers, and a height of, for example, 0.5 to 1.5 micrometers.

In this embodiment, the MEMS microphone 011 further includes a first diaphragm lead 502 and a first diaphragm contact point 610 disposed on the same layer as the first diaphragm 501, and the first diaphragm 501 is electrically connected to the first diaphragm contact point 610 through the first diaphragm lead 502. Similarly, the MEMS microphone 021 further has a second diaphragm lead 512 and a second diaphragm contact point 620, which are disposed on the same layer as the second diaphragm 511, and the second diaphragm 511 is electrically connected to the second diaphragm contact point 620 through the second diaphragm lead 512.

Further, the MEMS microphone 011 further has a first backplane lead 402 and a first backplane contact 403 disposed in the same layer as the first backplane electrode 401, and the first backplane electrode 401 is electrically connected to the first backplane contact 403 through the first backplane lead 402. Similarly, the MEMS microphone 021 further has a second backplate lead 702 and a second backplate contact 703 disposed on the same layer as the second backplate electrode 701, and the second backplate electrode 701 is electrically connected to the second backplate contact 703 through the second backplate lead 702. That is, the first backplane electrode 401, the first backplane lead 402, the first backplane contact 403, the second backplane electrode 701, the second backplane lead 702, and the second backplane contact 703 also belong to the same layer.

Further, in this embodiment, the pad group of the MEMS unit group 01 and the pad group of the MEMS unit group 02 includes four pads, and the four pads are a first back plate pad 801, a second back plate pad 802, a first diaphragm pad 803a, and a second diaphragm pad 803b, respectively. The first backplane pad 801 passes through the support wall (third support layer) and the second passivation layer 302 to be electrically connected to the first backplane contact 403, and the second backplane pad 802 passes through the support wall (third support layer) and the second passivation layer 302 to be electrically connected to the second backplane contact 703; the first diaphragm pad 803a passes through the support wall (the third support layer and the second support layer), the second passivation layer 302 and the first passivation layer to be electrically connected to the first diaphragm contact point 610, and the second diaphragm pad 803b is directly formed on the second diaphragm contact point 620 to be electrically connected to the second diaphragm contact point 620. In this way, the first backplate pad 801 may be electrically connected to the first backplate electrode 401, the second backplate pad 802 may be electrically connected to the second backplate electrode 701, the first diaphragm pad 803a may be electrically connected to the first diaphragm 501, and the second diaphragm pad 803b may be electrically connected to the second diaphragm 511. Thus, bias voltage can be applied to the MEMS microphone 011 and the MEMS microphone 021 through the pad group, and the pad group can also output the MEMS differential signal commonly output by the MEMS microphone 011 and the MEMS microphone 021.

Optionally, a third conductive layer 920 is further formed between the first backplane pad 801 and the second backplane pad 802, and the first backplane pad 801 and the second backplane pad 802 are electrically connected through the third conductive layer 920. In this way, the first backplane electrode 401 and the second backplane electrode 701 can be electrically connected.

It is understood that the first backplane pad 801 and the second backplane pad 802 may be electrically connected by a wire bonding method instead of the third conductive layer 920.

Based on this, this embodiment further provides a method for manufacturing a MEMS device, and fig. 6a to 6o are schematic structural diagrams corresponding to corresponding steps of the method for manufacturing a MEMS device provided in this embodiment. Next, a method for manufacturing the MEMS device will be described in detail with reference to fig. 6a to 6 o. In this embodiment, a method for manufacturing the MEMS device will be described in detail by taking an example that all the MEMS elements are MEMS microphones and all the MEMS microphones are manufactured simultaneously, and for convenience, fig. 6a to 6o only show that the MEMS device has a MEMS element group 01 and a MEMS element group 02, and the MEMS element group 01 has a MEMS microphone 011, and the MEMS element group 02 has a MEMS microphone 021.

Referring to fig. 6a, step S100 is performed to provide a substrate 100, for example, the substrate 100 is a silicon wafer with a <100> crystal orientation, and the doping type of the substrate 100 is N-type, but it should be understood that the invention is not limited to the crystal orientation and the doping type of the substrate 100.

Further, for convenience of description, the substrate 100 is divided into regions, wherein a BB1 region is a region for forming the MEMS microphone 021, an AA1 region is a region for forming the MEMS microphone 011, and points C and D are centers of the MEMS microphone 021 and the MEMS microphone 011, respectively.

With reference to fig. 6a, step S200 is executed to form a first sacrificial layer 201 on the substrate 100, where the first sacrificial layer 201 is, for example, a silicon oxide layer. The method of forming the first sacrificial layer 201 is, for example: a silicon oxide layer is formed on the substrate 100 by thermal oxidation, low pressure chemical vapor deposition or plasma enhanced chemical vapor deposition, as the first sacrificial layer 201, in this embodiment, a part of the first sacrificial layer 201 will be used as a sacrificial layer for forming a part of the cavity, and the thickness of the first sacrificial layer 201 is, for example, 0.5 to 2 micrometers.

Referring to fig. 6b, a first diaphragm 501, a first diaphragm lead 502 and a first diaphragm contact point 610 are formed on the first sacrificial layer 201. The first diaphragm 501, the first diaphragm lead 502 and the first diaphragm contact point 610 are all located in the AA1 area. The first diaphragm 501, the first diaphragm lead 502 and the first diaphragm contact point 610 are all located on the same layer and are all made of doped polysilicon. The first diaphragm lead 502 is used to electrically connect the first diaphragm 501 with the first diaphragm contact point 610.

The method for forming the first diaphragm 501, the first diaphragm lead 502 and the first diaphragm contact point 610 is, for example: depositing polysilicon on the first sacrificial layer 201 by Low Pressure Chemical Vapor Deposition (LPCVD); the polysilicon layer is patterned by photolithography and etching steps, so that the first diaphragm 501, the first diaphragm lead 502, and the first diaphragm contact point 610 are formed in different regions of the polysilicon layer, respectively.

Referring to fig. 6c, a second sacrificial layer 202 is formed on the first diaphragm 501, the first diaphragm lead 502, the first diaphragm contact point 610 and the exposed first sacrificial layer 201, and a plurality of first grooves 202a are formed on the upper surface of the second sacrificial layer 202, wherein the first grooves 202a are located in the AA1 area and correspond to the first diaphragm 501. In this embodiment, the second sacrificial layer 202 is a silicon oxide layer. The method for forming the second sacrificial layer 202 is, for example: a silicon oxide layer is formed as the second sacrificial layer 202 by a Low Pressure Chemical Vapor Deposition (LPCVD) or a Plasma Enhanced Chemical Vapor Deposition (PECVD). After the second sacrificial layer 202 is formed, the upper surface of the second sacrificial layer 202 is planarized, for example, using a chemical mechanical planarization process.

Similarly, a portion of the second sacrificial layer 202 will act as a sacrificial layer to form a portion of the cavity, and the thickness of the second sacrificial layer 202 is also used to define the spacing between the first diaphragm 501 and the subsequently formed first backplate structure. The thickness of the second sacrificial layer 202 is chosen according to the electrical and acoustic properties of the MEMS microphone, for example 2 to 4 microns.

The first groove 202a is an opening of the surface of the second sacrificial layer 202 and extends downward. The first groove 202a may have a polygonal shape such as a circular hole, a square hole, or a triangular hole, when viewed from the surface of the second sacrificial layer 202. The first groove 202a has a rectangular shape or a trapezoidal shape or a V-shape having a bottom surface smaller than an opening surface when viewed from a cross section of the first groove 202 a.

The step of forming the first groove 202a may be: a resist layer is formed on the surface of the second sacrificial layer 202, and a pattern including an opening is formed in the resist layer by a photolithography process. The exposed portions of the second sacrificial layer 202 are removed with a selective etchant using the resist layer as a mask, thereby forming a plurality of first grooves 202 a. By controlling the etching time, the etching can be stopped at a predetermined depth to the second sacrificial layer 202. After etching, the resist layer may be removed by ashing or dissolution in a solvent.

Referring to fig. 6d, the second sacrificial layer 202 is etched to form a first diaphragm contact hole 610a, the first diaphragm contact hole 610a is located above the first diaphragm contact point 610, and the first diaphragm contact hole 610a does not penetrate through the second sacrificial layer 202.

Referring to fig. 6e, a protective layer material is deposited on the second sacrificial layer 202, and the portion of the protective layer material on the second sacrificial layer 202 in the AA1 area constitutes the first protective layer 301, and the portion on the second sacrificial layer 202 in the BB1 area constitutes the fourth protective layer 304. The method for forming the fourth protection layer 304 is, for example: a boron nitride layer is formed on the second sacrificial layer 202 by Plasma Enhanced Chemical Vapor Deposition (PECVD) or Low Pressure Chemical Vapor Deposition (LPCVD).

Of course, due to the existence of the first diaphragm contact hole 610a, the first protection layer 301 may also fill a part of the depth of the first diaphragm contact hole 610 a.

Further, the first protective layer 301 fills the first groove 202a, thereby forming a first protrusion 202b for preventing the first diaphragm 501 from adhering to a subsequently formed first backplate structure, the shape of the first protrusion 202b conforming to the shape of the first groove 202 a.

Referring to fig. 6f, a first backplane electrode 401, a first backplane lead 402 and a first backplane contact 403 are formed on the first protection layer 301, and a second backplane electrode 701, a second backplane lead 702 and a second backplane contact 703 are formed on the fourth protection layer 304.

The first backplane lead 402 is used to electrically connect the first backplane electrode 401 and the first backplane contact 403, and the first backplane electrode 401, the first backplane lead 402 and the first backplane contact 403 are only located in the AA1 area. The second backplane lead 702 is used to electrically connect the second backplane electrode 701 and the second backplane contact 703, and the second backplane electrode 701, the second backplane lead 702 and the second backplane contact 703 are only located in the BB1 area.

In this embodiment, the first backplane electrode 401, the first backplane lead 402, the first backplane contact 403, the second backplane electrode 701, the second backplane lead 702, and the second backplane contact 703 are all located on the same layer and are all made of doped polysilicon. The method for forming the first backplane electrode 401, the first backplane lead 402, the first backplane contact 403, the second backplane electrode 701, the second backplane lead 702, and the second backplane contact 703 is, for example: a doped polysilicon layer is formed on the surfaces of the first and fourth protective layers 301 and 304, respectively, using Low Pressure Chemical Vapor Deposition (LPCVD). Then, the polysilicon layer is patterned by photolithography and etching steps to form the patterns of the first backplane electrode 401, the first backplane lead 402, the first backplane contact 403, the second backplane electrode 701, the second backplane lead 702, and the second backplane contact 703.

With reference to fig. 6f, a passivation layer is deposited on the first backplane electrode 401, the first backplane lead 402, the first backplane contact 403, the second backplane electrode 701, the second backplane lead 702, and the second backplane contact 703, and on the remaining surfaces of the first passivation layer 301 and the fourth passivation layer 304, wherein the passivation layer forms the second passivation layer 302 in the AA1 region, and forms the third passivation layer 303 in the BB1 region. The second protective layer 302 and the third protective layer 303 are formed, for example, by: the conformal boron nitride layer is formed by Plasma Enhanced Chemical Vapor Deposition (PECVD) or Low Pressure Chemical Vapor Deposition (LPCVD).

Referring to fig. 6g, a plurality of first release holes 401a penetrating through the second passivation layer 302, the first backplane electrode 401 and the first passivation layer 301 are formed; and a plurality of second release holes 701a penetrating the fourth protective layer 304, the second backplane electrode 701, and the third protective layer 303 are formed. A plurality of the first release holes 401a constitute a first release hole array, which is located in the AA1 area; the plurality of second release holes 701a constitute a second release hole array located in the BB1 region at a position corresponding to the position of the first diaphragm 501. The first release hole 401a and the second release hole 701a are formed, for example, by: depositing a resist layer on the whole surface, and forming a pattern containing an opening in the resist layer by adopting a photoetching process; removing the respective exposed portions of the second protective layer 302, the first backplane electrode 401, and the first protective layer 301 with a selective etchant using the resist layer as a mask, thereby forming the first release holes 401 a; and removing the exposed portions of the fourth protective layer 304, the second back plate electrode 701, and the third protective layer 303, respectively, to form the second release holes 701 a. After etching, the resist layer may be removed by ashing or dissolution in a solvent.

As an alternative embodiment, a special deep trench etching machine may be used to form the first release hole 401a and the second release hole 701 a.

Referring to fig. 6h, etching is performed to remove a portion of the passivation layer between the second backplate contact 703 and the first backplate contact 403 to form the second opening 324, and simultaneously, the remaining first passivation layer 301 in the first diaphragm contact hole 610a is also completely removed to expose the second sacrificial layer 202. The second opening 324 divides the first protection layer 301 and the fourth protection layer 304 into two parts, and also divides the second protection layer 302 and the third protection layer 303 into two parts, and the surface of the second sacrificial layer 202 at the bottom of the second opening 324 is exposed.

After the etching is completed, the remaining first protection layer 301, the first backplane electrode 401 and the second protection layer 302 together form a first backplane structure, and the first backplane lead 402 and the first backplane contact 403 are used for leading out the first backplane electrode 401 in the first backplane structure. The remaining fourth protection layer 304, the second backplane electrode 701 and the third protection layer 303 together form a second backplane structure, and the second backplane lead 702 and the second backplane contact 703 are used for leading out the second backplane electrode 701 in the second backplane structure.

Referring to fig. 6i, a third sacrificial layer 203 is deposited on the whole surface, and a plurality of second grooves 203a are formed on the surface of the third sacrificial layer 203, wherein the second grooves 203a are located in the BB1 area and are located corresponding to the second backplane electrode 701. The third sacrificial layer 203 covers the second protective layer 302 and the third protective layer 303 and fills the second opening 324, the first release hole 401a, the second release hole 701a, and at least a portion of the depth of the first diaphragm contact hole 610 a. In this embodiment, the third sacrificial layer 203 is a silicon oxide layer. The method of forming the third sacrificial layer 203 is, for example: as the third sacrificial layer 203, a silicon oxide layer is formed by a Low Pressure Chemical Vapor Deposition (LPCVD) or a Plasma Enhanced Chemical Vapor Deposition (PECVD) method. After the third sacrificial layer 203 is formed, the upper surface of the third sacrificial layer 203 is planarized, for example, using a chemical mechanical planarization process.

Similarly, a portion of the third sacrificial layer 203 will act as a sacrificial layer to form part of the cavity, and the thickness of the third sacrificial layer 203 is also used to define the spacing between the second backplate structure and the subsequently formed second diaphragm. The thickness of the third sacrificial layer 203 is chosen according to the electrical and acoustic properties of the MEMS microphone, for example 2 to 4 microns.

The second groove 203a is an opening of the surface of the third sacrificial layer 203 and extends downward. The second groove 203a may have a polygonal shape such as a circular hole, a square hole, or a triangular hole, when viewed from the surface of the third sacrificial layer 203. The second groove 203a has a rectangular shape or a trapezoidal shape or a V-shape having a bottom surface smaller than an opening surface when viewed from a cross section of the second groove 203 a.

The step of forming the second groove 203a may be: a resist layer is formed on the surface of the third sacrificial layer 203, and a pattern including an opening is formed in the resist layer by a photolithography process. The exposed portions of the third sacrificial layer 203 are removed with a selective etchant using the resist layer as a mask, thereby forming a plurality of second grooves 203 a. By controlling the etching time, the etching can be stopped at a predetermined depth to the third sacrificial layer 203. After etching, the resist layer may be removed by ashing or dissolution in a solvent.

Referring to fig. 6j, a second diaphragm 511, a second diaphragm lead 512 and a second diaphragm contact point 620 are formed on the third sacrificial layer 203. The second diaphragm 511, the second diaphragm lead 512 and the second diaphragm contact point 620 are all located in the BB1 area. The second diaphragm 511, the second diaphragm lead 512 and the second diaphragm contact point 620 are all located on the same layer and are all made of doped polysilicon. The second diaphragm lead 512 is used to electrically connect the second diaphragm 511 and the second diaphragm contact point 620.

Further, the second diaphragm 511 fills the second groove 203a, thereby forming a second protrusion 203b for preventing the second diaphragm 511 from adhering to the second backplate structure, the shape of the second protrusion 203b conforming to the shape of the second groove 203 a.

The methods for forming the second diaphragm 511, the second diaphragm lead 512 and the second diaphragm contact point 620 are, for example: depositing polysilicon on the third sacrificial layer 203 using Low Pressure Chemical Vapor Deposition (LPCVD); and patterning the polysilicon layer by adopting photoetching and etching steps, so that the second vibration film 511, the second vibration film lead wire 512 and the second vibration film contact point 620 are respectively formed in different areas of the polysilicon layer.

Referring to fig. 6k, the third sacrificial layer 203 and the second protection layer 302 are etched to form a first backplate contact hole 403a, the third sacrificial layer 203 and the third protection layer 303 are etched to form a second backplate contact hole 703a, and the third sacrificial layer 203 and the second sacrificial layer 202 are etched such that the first diaphragm contact hole 610 extends downward to expose the first diaphragm contact point 610. The first backplane contact hole 403a is located above the first backplane contact 403 and penetrates through the third sacrificial layer 203 and the second protective layer 302 to expose the surface of the first backplane contact 403; the second backplane contact hole 703a is located above the second backplane contact 703, and penetrates through the third sacrificial layer 203 and the third passivation layer 303 to expose the surface of the second backplane contact 703.

Referring to fig. 6l, conductive materials are filled in the first backplate contact hole 403a, the second backplate contact hole 703a and the first diaphragm contact hole 610a, so as to form a first backplate pad 801, a second backplate pad 802 and a first diaphragm pad 803a in the first backplate contact hole 403a, the second backplate contact hole 703a and the first diaphragm contact hole 610a, respectively, and also form a second diaphragm pad 803b directly on the second diaphragm contact point 620. In this way, the first backplane pad 801 may be electrically connected to the first backplane electrode 401 through the first backplane contact 403 and the first backplane lead 402; the second backplane pad 802 is electrically connected to the second backplane electrode 701 through the second backplane contact 703 and the second backplane lead 702; the first diaphragm pad 803a is electrically connected to the first diaphragm 501 through the first diaphragm contact point 610 and the first diaphragm lead 502, and the second diaphragm pad 803b is electrically connected to the second diaphragm 511 through the second diaphragm contact point 620 and the second diaphragm lead 512.

The method for forming the first backplate pad 801, the second backplate pad 802, the first diaphragm pad 803a and the second diaphragm pad 803b is, for example: forming a whole metal layer by a sputtering or evaporation method, wherein the metal layer also fills the first backboard contact hole 403a, the second backboard contact hole 703a and the first diaphragm contact hole 610 a; the metal layer is patterned using conventional photolithography and etching steps to form the first backplate pad 801, the second backplate pad 802, the first diaphragm pad 803a and the second diaphragm pad 803 b.

Referring to fig. 6m, a first acoustic cavity 110 and a second acoustic cavity 120 are formed in the substrate 100, the first acoustic cavity 110 is located in the AA1 area, and the second acoustic cavity 120 is located in the BB1 area. In this embodiment, the substrate 100 is thinned to a design value, for example, 350 to 450 microns, preferably 400 microns, by a chemical mechanical planarization process. Then, a resist layer is formed on the lower surface of the substrate 100, and a pattern including an opening is formed in the resist layer using a photolithography process. The exposed portions of the substrate 100 are removed with a selective etchant using the resist layer as a mask, thereby forming the first acoustic cavity 110 and the second acoustic cavity 120. In this embodiment, the first acoustic cavity 110 and the second acoustic cavity 120 are openings having inverted trapezoidal cross-sectional shapes along the thickness direction, and optionally, the first acoustic cavity 110 and the second acoustic cavity 120 may also be openings having square or hexagonal cross-sectional shapes along the thickness direction. After etching, the resist layer may be removed by ashing or dissolution in a solvent.

Alternatively, the first acoustic cavity 110 and the second acoustic cavity 120 are formed by a conventional Bosch process in MEMS technology and a special deep trench etcher.

As an alternative embodiment, the process of etching the back surface of the substrate 100 to form the first acoustic cavity 110 and the second acoustic cavity 120 may also be performed in a hard mask manner, that is, a hard mask layer is formed on the back surface of the substrate 100, then a pattern is formed in the hard mask layer, and the substrate 100 is etched using the hard mask layer as a mask to form the first acoustic cavity 110 and the second acoustic cavity 120.

Referring to fig. 6n, since the surface of the third sacrificial layer 203 in the AA1 area is exposed, a portion of the first sacrificial layer 201, the second sacrificial layer 202 and the third sacrificial layer 203 can be removed through the first acoustic cavity 110, the second acoustic cavity 120, the first release hole array and the second release hole array to release the first diaphragm 501 and the second diaphragm 511.

In this embodiment, hydrofluoric acid is used as the corrosive agent, and the exposed surfaces of the first acoustic cavity 110, the second acoustic cavity 120, the first release hole array, the second release hole array, and the third sacrificial layer 203 are used as the access channels of the corrosive agent. The first protective layer 301 and the second protective layer 302 serve as protective films for the first backplane electrode 401, and the third protective layer 303 and the fourth protective layer 304 serve as protective films for the second backplane electrode 701, so that the first backplane electrode 401 and the second backplane electrode 701 are not corroded in the corrosion step.

By using a vapor phase fumigation method with hydrofluoric acid or a wet etching method with hydrofluoric acid, the hydrofluoric acid contacts the first sacrificial layer 201, the second sacrificial layer 202, and the third sacrificial layer 203 with the exposed surfaces of the first acoustic cavity 110, the second acoustic cavity 120, the first release hole array, the second release hole array, and the third sacrificial layer 203 as channels, so as to remove a portion of each of the first sacrificial layer 201, the second sacrificial layer 202, and the third sacrificial layer 203, and to re-expose a portion of the upper and lower surfaces of the first diaphragm 501 and the second diaphragm 511, thereby releasing the first diaphragm 501 and the second diaphragm 511.

After removing a portion of the first sacrificial layer 201, the second sacrificial layer 202, and the third sacrificial layer 203, the remaining first sacrificial layer 201, the second sacrificial layer 202, and the third sacrificial layer 203 respectively constitute a first support layer, a second support layer, and a third support layer of the support wall, so as to support the first vibration film 501 and the second vibration film 511. Meanwhile, the supporting wall encloses a first cavity and a second cavity, the first diaphragm 501 is suspended in the first cavity and divides the first cavity into an upper part and a lower part, and the first release holes (sound holes) 401a in the first release hole array and the first sound cavity 110 are respectively communicated with the two parts of the first cavity and used for providing an airflow channel during the vibration of the first diaphragm 501; the second diaphragm 511 is located on the second cavity, the second cavity is divided into two parts communicating with each other by second release holes (sound holes) 701a in the second release hole array, and the second cavity and the space above the second diaphragm 511 can be used to provide an air flow passage during vibration of the second diaphragm 511.

With reference to fig. 6n and 6o, after releasing a portion of the first sacrificial layer 201, the second sacrificial layer 202, and the third sacrificial layer 203, a MEMS microphone 011 is formed in an AA1 region, a MEMS microphone 021 is formed in a BB1 region, a diaphragm and a backplate electrode of the MEMS microphone 011 are the first diaphragm 501 and the first backplate electrode 401, respectively, and a diaphragm and a backplate electrode of the MEMS microphone 021 are the second diaphragm 511 and the second backplate electrode 701, respectively. The MEMS microphone 011 is a MEMS microphone with a diaphragm below a back plate electrode, and the MEMS microphone 021 is a MEMS microphone with a diaphragm above a back plate electrode.

Next, a third conductive layer 920 is formed simultaneously when the first diaphragm pad 803a and the second diaphragm pad 803b are formed, so that the first diaphragm pad 803a and the second diaphragm pad 803 are electrically connected through the third conductive layer 920. In this way, the first diaphragm 501 and the second diaphragm 511 can be electrically connected.

It is understood that the first diaphragm pad 803a and the second diaphragm pad 803b may also be electrically connected not by the third conductive layer 920, but by wire bonding.

EXAMPLE six

Fig. 7a and 7b are schematic structural diagrams of the MEMS device provided in this embodiment, in which fig. 7b is a top view of the MEMS device, and fig. 7a is a cross-sectional view of fig. 7b along BC, CO, OD, and DA directions. With reference to fig. 7a and 7b, the difference from the fifth embodiment is that in the present embodiment, there is only one backplate pad, and the pad group corresponding to the MEMS microphone group 01 and the MEMS microphone group 02 has 3 pads.

Specifically, the 3 pads are a backplate pad 800, a first diaphragm pad 803a and a second diaphragm pad 803 b. Specifically, the first backplane electrode 401 is electrically connected to the backplane contact 743 through the first backplane lead 402, and the second backplane electrode 701 is electrically connected to the backplane contact 743 through the second backplane lead 702. The backplane contact 743 is located between the first backplane lead 402 and the second backplane lead 702 and electrically connects the first backplane lead 402 and the second backplane lead 702, and the first backplane electrode 401 and the second backplane electrode 701 share the backplane contact 743. The backplane pad 800 penetrates through the support wall (third support layer), the second protective layer 302 and the third protective layer 303 to be electrically connected to the backplane contact 743, so that the first backplane electrode 401 and the second backplane electrode 701 share the backplane pad 800, and the backplane pad 800 can lead out the first backplane electrode 401 and the second backplane electrode 701.

It should be understood that the preparation method of the MEMS device in this embodiment is similar to that of the MEMS device in the fifth embodiment, and the difference is only that only one backplane contact needs to be prepared when the first backplane electrode 401 and the second backplane electrode 701 are prepared, and only one backplane pad needs to be prepared when the pad group is prepared, and redundant description is omitted here.

EXAMPLE seven

Fig. 8 is a schematic structural diagram of the MEMS device provided in this embodiment. With reference to fig. 8, the difference from the fifth embodiment is that, in this embodiment, there is no third supporting layer above the first backplane structure, the third supporting layer only covers the edge of the second backplane structure, and the first backplane structure is directly formed on the second supporting layer and fixed.

With reference to fig. 8, the first backplate pad 801 is directly formed on the first backplate contact 403 and electrically connected to the first backplate contact 403, and the first diaphragm pad 803a passes through the second passivation layer 302, the first passivation layer 301 and the second supporting layer and electrically connected to the first diaphragm contact 610.

Referring to fig. 8, in the present embodiment, the second backplane pad 802 and the first backplane pad 801 are electrically connected through a fifth conductive layer (not shown), so that the second backplane pad 802 and the first backplane pad 801 can also be electrically connected. The second backplane pad 802 and the first backplane pad 801 may then be brought out by forming an additional pad on the fifth conductive layer.

It is to be understood that the manufacturing method of the MEMS device in this embodiment is similar to that of the MEMS device in the fifth embodiment, except that the third sacrificial layer 203 in the AA1 area is completely removed before the sacrificial layer is released; then, the third protective layer 302 on the first backplate contact point 403 and the first diaphragm contact point 610 is removed, contact holes exposing the first diaphragm contact point 610 and the second backplate contact point 703 are formed by etching, and then a first backplate pad 801, a second backplate pad 802, a first diaphragm pad 803a and a second diaphragm pad 803b are synchronously formed.

Example eight

Fig. 9 is a schematic structural diagram of the MEMS device provided in this embodiment. With reference to fig. 9, the difference from the sixth embodiment is that, in this embodiment, there is no third supporting layer above the first backplane structure, the third supporting layer only covers the edge of the second backplane structure, and the first backplane structure is directly formed on the second supporting layer and fixed.

With reference to fig. 9, the backplate pad 800 is directly formed on the backplate contact 743 and electrically connected to the backplate contact 743, and the first diaphragm pad 803a passes through the first passivation layer 301, the second passivation layer 302 and the second support layer and is electrically connected to the first diaphragm contact 610.

It is to be understood that the manufacturing method of the MEMS device in this embodiment is similar to that of the MEMS device in the sixth embodiment, except that the third sacrificial layer 203 of the OA region is completely removed before releasing the sacrificial layer; then, the third protective layer 302 on the backplate contact point 743 and the first diaphragm contact point 610 is removed, and a contact hole exposing the first diaphragm contact point 610 is formed by etching, and then the backplate pad 800, the first diaphragm pad 803a and the second diaphragm pad 803b are formed synchronously.

Example nine

Fig. 10 is a top view of the MEMS device provided in this embodiment. As shown in fig. 10, the difference from the first embodiment is that, in the present embodiment, each of the MEMS unit group 01 and the MEMS unit group 02 has two MEMS units, and one of the MEMS units of the MEMS unit group 01 is electrically connected to one of the MEMS units of the MEMS unit group 02 to form a MEMS differential pair. Two MEMS units in the MEMS unit group 01 are respectively an MEMS microphone 011 and an MEMS microphone 012, and two MEMS units in the MEMS unit group 02 are respectively an MEMS microphone 021 and an MEMS microphone 022.

Further, as an alternative embodiment, the MEMS element group 01 and the MEMS element group 02 are not limited to the same number of MEMS elements each, and the MEMS element group 01 and the MEMS element group 02 may have different numbers of MEMS elements. For example, the MEMS element group 01 has one MEMS element, and the MEMS element group 02 has two MEMS elements; alternatively, the MEMS unit group 01 has three MEMS units, and the MEMS unit group 02 has one MEMS unit, which is not described in detail herein.

Further, the MEMS microphone 011 and the MEMS microphone 012 are connected in parallel, and the MEMS microphone 021 and the MEMS microphone 022 are connected in parallel. Specifically, the vibrating membranes of the MEMS microphone 011 and the MEMS microphone 012 are electrically connected to each other, and the back plate electrodes of the MEMS microphone 011 and the MEMS microphone 012 are electrically connected to each other, so that the MEMS microphone 011 and the MEMS microphone 012 are connected in parallel; similarly, the diaphragm of the MEMS microphone 021 and the diaphragm of the MEMS microphone 022 are electrically connected to each other, and the back plate electrodes of the MEMS microphone 021 and the MEMS microphone 022 are electrically connected to each other, so that the MEMS microphone 021 and the MEMS microphone 022 are connected in parallel.

Taking the MEMS microphone 011 and the MEMS microphone 012 as examples, the MEMS microphone 011 has a first diaphragm 501 and a first back plate electrode 401, the MEMS microphone 012 has a third diaphragm 500 and a third back plate electrode 700, the first diaphragm 501 and the third diaphragm 500 are electrically connected through a fourth conductive layer 50, and the first back plate electrode 401 and the third back plate electrode 700 are electrically connected through a fifth conductive layer 70. Optionally, the fourth conductive layer 50, the first vibration film 501 and the third vibration film 500 are made of the same material and are synchronously prepared; the fifth conductive layer 70 is made of the same material as the first backplane electrode 401 and the third backplane electrode 700, and is prepared synchronously, so that the preparation process is simple.

Similar to the MEMS microphones 011 and 012, the MEMS microphones 021 and 022 have their diaphragms and back plate electrodes electrically connected by conductive layers.

In this embodiment, the MEMS unit group 01 and the MEMS unit group 02 belong to the same stage and correspond to a pad group, one of the MEMS units of the first MEMS unit group leads out a first MEMS signal through a pad, one of the MEMS units of the second MEMS unit group leads out a second MEMS signal through a pad, one of the MEMS units of the first MEMS unit group and one of the MEMS units of the second MEMS unit group are connected through a pad, and the first MEMS signal and the second MEMS signal form a MEMS differential signal.

In this embodiment, the pad group includes a first backplate pad 801, a second backplate pad 802, and a diaphragm pad 803.

The first backplate pad 801 is electrically connected with the backplate electrodes of the MEMS microphone 011 and the MEMS microphone 012, the second backplate pad 802 is electrically connected with the backplate electrodes of the MEMS microphone 021 and the MEMS microphone 022, and the diaphragm pad 803 is electrically connected with the diaphragm membranes of the MEMS microphone 011, the MEMS microphone 012, the MEMS microphone 021 and the MEMS microphone 022; in this way, bias voltages can be synchronously applied to the MEMS microphone 011, the MEMS microphone 012, the MEMS microphone 021 and the MEMS microphone 022 through the pad group, and meanwhile, the pad group can also output MEMS differential signals commonly provided by the MEMS microphone 012, the MEMS microphone 021 and the MEMS microphone 022.

In this embodiment, the first backplate pad 801 is located in the MEMS microphone 011, the second backplate pad 802 is located in the MEMS microphone 021, and the diaphragm pad 803 is located between the MEMS microphone 011 and the MEMS microphone 021, but this should not be limited thereto, and the first backplate pad 801, the second backplate pad 802, and the diaphragm pad 803 may also be distributed at any possible position on the substrate 100, and thus, redundant description is not repeated here.

Further, in this embodiment, the MEMS unit group 01 and the MEMS unit group 02 are arranged along a first direction, the MEMS microphone 011 and the MEMS microphone 012 are arranged along a second direction, the MEMS microphone 021 and the MEMS microphone 022 are also arranged along the second direction, the MEMS microphone 011 and the MEMS microphone 021 are arranged and aligned along the first direction, and the MEMS microphone 012 and the MEMS microphone 022 are arranged and aligned along the first direction. In this way, the MEMS microphones 011, 012, 021 and 022 are distributed in an array on the substrate 100, thereby saving the area of the device. In this embodiment, the first direction is a row direction, the second direction is a column direction, and as an optional embodiment, the first direction and the second direction are not limited to the row direction and the column direction, and the first direction and the second direction may be perpendicular or not.

It should be understood that the MEMS microphone 011 and the MEMS microphone 012 are the same MEMS structure, and the MEMS microphone 021 and the MEMS microphone 022 are the same MEMS structure. When the MEMS device is manufactured, the MEMS microphone 011, the MEMS microphone 012, the MEMS microphone 021 and the MEMS microphone 022 are all manufactured on the substrate 100 synchronously, that is: 4 MEMS microphones are simultaneously prepared on the substrate 100, thereby forming the MEMS device.

Example ten

Fig. 11 is a top view of the MEMS device provided in this embodiment. As shown in fig. 11, the difference from the ninth embodiment is that, in the present embodiment, the positions of the MEMS microphones 011 and 012 are diagonally distributed, and the positions of the MEMS microphones 021 and 022 are diagonally distributed. The diaphragms of the MEMS microphone 011 and 022 are electrically connected to each other through a seventh conductive layer 51, and the diaphragms of the MEMS microphone 021 and 012 are electrically connected to each other through a seventh conductive layer 52; the back plate electrodes of the MEMS microphone 011 and the MEMS microphone 012 are electrically connected to each other through a sixth conductive layer 72, and the back plate electrodes of the MEMS microphone 021 and the MEMS microphone 022 are electrically connected to each other through a sixth conductive layer 71.

EXAMPLE eleven

Fig. 12 is a schematic structural diagram of the MEMS device provided in this embodiment. Referring to fig. 12, the difference from the first embodiment is that, in the present embodiment, the MEMS device includes 4 MEMS element groups, where the MEMS element group 01 and the MEMS element group 02 belong to the same stage, the MEMS element group 03 and the MEMS element group 04 belong to the same stage, and the MEMS element group 01, the MEMS element group 02, the MEMS element group 03, and the MEMS element group 04 are all fabricated on the substrate 100.

Further, in the present embodiment, each of the MEMS element group 01, the MEMS element group 02, the MEMS element group 03, and the MEMS element group 04 has one MEMS element, but the present invention should not be limited thereto. The MEMS unit in the MEMS unit group 01 is an MEMS microphone 011, the MEMS unit in the MEMS unit group 02 is an MEMS microphone 021, the MEMS unit in the MEMS unit group 03 is an MEMS microphone 031, and the MEMS unit in the MEMS unit group 04 is an MEMS microphone 041.

The MEMS microphone 011 and the MEMS microphone 031 have the same structure and are MEMS microphones with vibrating membranes above a back plate electrode; the MEMS microphone 021 and the MEMS microphone 041 have the same structure, and are both MEMS microphones with a vibrating membrane below a back plate electrode.

Further, each stage of MEMS unit group has three pads, namely a first backplate pad 801, a second backplate pad 802, and a diaphragm pad 803, in the pad group, that is, the MEMS device has two first backplate pads 801, two second backplate pads 802, and two diaphragm pads 803. The two first backplate pads 801 are electrically connected to the backplate electrodes of the MEMS microphone 011 and the MEMS microphone 031, the two second backplate pads 802 are electrically connected to the backplate electrodes of the MEMS microphone 021 and the MEMS microphone 041, one of the diaphragm pads 803 is electrically connected to the diaphragm of the MEMS microphone 011 and the MEMS microphone 021, and the other diaphragm pad 803 is electrically connected to the diaphragm of the MEMS microphone 031 and the diaphragm of the MEMS microphone 041.

In the embodiment, MEMS signals output by each stage can be cascaded through the bonding pad between the two bonding pad groups or through routing, so that the sensitivity and the signal-to-noise ratio are improved.

The preparation method of the MEMS device in this embodiment is similar to that of the MEMS device in the first embodiment, and the difference is only that the MEMS microphone 031 and the MEMS microphone 041 are synchronously prepared when the MEMS microphone 011 and the MEMS microphone 021 are prepared, and that the pad group of the MEMS microphone 031 and the pad group of the MEMS microphone 041 are also synchronously prepared when the pad group of the MEMS microphone 011 and the MEMS microphone 021 is prepared.

In summary, in the MEMS device and the method for manufacturing the same provided by this embodiment, the MEMS device includes at least two MEMS unit groups manufactured on the same substrate, each of the MEMS unit groups includes a plurality of MEMS units, each of the two MEMS unit groups is of the same stage, relative positions of a back plate and a diaphragm of the MEMS unit in the two MEMS unit groups of the same stage are different, and at least one MEMS unit in one MEMS unit group is electrically connected to at least one MEMS unit in another MEMS unit group. In the invention, the two MEMS unit groups at the same level can realize transverse difference, compared with longitudinal difference, the transverse difference structure is easier to prepare, and the capacitances of the two MEMS unit groups are easier to match; moreover, the MEMS signals output by the MEMS unit groups of different levels can realize signal cascade subsequently, and can be used for manufacturing an MEMS system with a multistage cascade structure, so that the sensitivity and the signal-to-noise ratio are improved.

The above description is only a preferred embodiment of the present invention, and does not limit the present invention in any way. It will be understood by those skilled in the art that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.