阅读说明：本技术 微机电结构及其制造方法、晶圆、麦克风和终端 (Micro-electro-mechanical structure and manufacturing method thereof, wafer, microphone and terminal ) 是由 孟燕子 荣根兰 孙恺 胡维 于 2021-09-03 设计创作，主要内容包括：本申请公开了一种微机电结构及其制造方法、晶圆、麦克风和终端,该制造方法包括：在衬底上方形成第一背板；在第一背板上形成第二牺牲层；在第二牺牲层上形成振膜,振膜沿第二牺牲层的侧壁、第一背板的侧壁延伸至衬底上；以及去除部分第二牺牲层,余下的第二牺牲层作为第二支撑部。该制造方法通过令振膜覆盖第二牺牲层的侧壁,减小了释放工艺中释放液从第二牺牲层的侧壁侵蚀的风险。(The application discloses a micro-electromechanical structure and a manufacturing method thereof, a wafer, a microphone and a terminal, wherein the manufacturing method comprises the following steps: forming a first backplane over a substrate; forming a second sacrificial layer on the first backplane; forming a vibrating diaphragm on the second sacrificial layer, wherein the vibrating diaphragm extends to the substrate along the side wall of the second sacrificial layer and the side wall of the first back plate; and removing part of the second sacrificial layer, wherein the rest second sacrificial layer is used as a second support part. According to the manufacturing method, the diaphragm covers the side wall of the second sacrificial layer, so that the risk that release liquid erodes from the side wall of the second sacrificial layer in the release process is reduced.)

1. A method of fabricating a microelectromechanical structure, comprising:

forming a first backplane over a substrate;

forming a second sacrificial layer on the first backplane;

forming a vibrating diaphragm on the second sacrificial layer, wherein the vibrating diaphragm extends to the substrate along the side wall of the second sacrificial layer and the side wall of the first back plate;

forming a cavity in the substrate; and

and removing part of the second sacrificial layer, wherein the rest second sacrificial layer is used as a second support part.

2. The manufacturing method according to claim 1, further comprising forming a first sacrificial layer on a substrate before forming the first backplate,

after the diaphragm is formed, the manufacturing method further includes removing a portion of the first sacrificial layer, the remaining first sacrificial layer serving as a first support portion,

the first back plate is located between the first sacrificial layer and the second sacrificial layer, and the diaphragm is also in contact with the side wall of the first sacrificial layer.

3. The manufacturing method of claim 2, further comprising, prior to forming the cavity:

forming a third sacrificial layer on the diaphragm;

forming a second backplane on the third sacrificial layer; and

and removing part of the third sacrificial layer, wherein the rest third sacrificial layer is used as a third supporting part.

4. The manufacturing method according to claim 3, wherein the step of forming the second back plate includes:

forming a lower dielectric layer on the third sacrificial layer;

forming a first groove extending from the surface of the lower medium layer to the surface of the diaphragm;

forming a conducting layer on the lower medium layer, wherein the conducting layer is also filled in the first groove and is connected with the vibrating diaphragm; and

forming an upper dielectric layer on the conductive layer,

and the conductive layer filled in the first groove is used as a sunken part of the second back plate.

5. The manufacturing method according to claim 4, wherein the conductive layer of the second back plate is a polysilicon conductive layer.

6. The method of manufacturing of claim 4, wherein forming the second backplane further comprises, prior to forming an upper dielectric layer on the conductive layer: forming a second groove extending from the surface of the conductive layer to the surface of the lower dielectric layer to divide the conductive layer on the third sacrificial layer into a central portion and an edge portion,

the edge part of the conducting layer surrounds the central part, the sunken part of the second back plate is connected with the edge part of the conducting layer, and the upper dielectric layer also covers the side surface and the bottom surface of the second groove.

7. The manufacturing method according to claim 3, further comprising, before forming the third sacrificial layer:

forming a third groove extending from the surface of the diaphragm to the surface of the second sacrificial layer to divide the diaphragm into a central portion and an edge portion,

wherein an edge portion of the diaphragm surrounds a center portion and extends onto the substrate along the sidewall of the second sacrificial layer, the sidewall of the first backplate, and the sidewall of the first sacrificial layer,

the third sacrificial layer is also filled in the third groove.

8. The manufacturing method according to any one of claims 2 to 7, further comprising, before forming the diaphragm:

forming an isolation groove extending from the surface of the second sacrificial layer to the surface of the substrate, wherein the isolation groove divides a laminated structure consisting of the first sacrificial layer, the first backboard and the second sacrificial layer into a plurality of units arranged in an array,

wherein the diaphragm covers the side surface and the bottom surface of the isolation groove.

9. The manufacturing method according to claim 8, wherein the step of forming the isolation groove includes:

removing a portion of the second back plate to expose a portion of the first sacrificial layer before forming the second sacrificial layer, the second sacrificial layer being formed thereafter to be connected to the exposed first sacrificial layer; and

and removing part of the second sacrificial layer and the first sacrificial layer at the joint of the second sacrificial layer and the first sacrificial layer to form the isolation groove.

10. The manufacturing method of claim 9, wherein the step of forming the isolation trench further comprises:

after removing part of the second back plate and before forming the second sacrificial layer, removing part of the first sacrificial layer to expose part of the substrate, wherein the second sacrificial layer formed later is also connected with the exposed substrate.

11. The manufacturing method according to claim 9, wherein a portion of the second sacrificial layer and the first sacrificial layer is removed by an isotropic wet etching process to bevel the side surfaces of the isolation trench,

wherein, the bottom surface width of the isolation groove is less than the opening width of the isolation groove.

12. The method of manufacturing of claim 8, wherein the diaphragm is a polysilicon diaphragm.

13. The manufacturing method of claim 12, wherein the isolation trench exposes a surface of the substrate, and the step of forming the diaphragm comprises:

depositing amorphous silicon on the surface of the second sacrificial layer, the side face of the isolation groove and the exposed surface of the substrate; and

and growing the amorphous silicon in contact with the exposed substrate along the crystal direction of the substrate by an annealing process.

14. The method of manufacturing of claim 12, wherein the polysilicon diaphragm has a dopant impurity comprising phosphorous.

15. The manufacturing method according to claim 13, further comprising, after removing part of the second sacrificial layer, cutting the substrate and the diaphragm along a dicing lane to separate a plurality of the cells arranged in an array,

wherein the scribing channel is corresponding to the isolation groove in position.

16. A wafer having scribe lanes, the wafer comprising:

a substrate;

a plurality of array units located above the substrate, adjacent array units being separated by the scribe lanes; and

a diaphragm covering the array units and the substrate surface where the scribing street is located,

each array unit comprises a first back plate and a second supporting part positioned on the first back plate.

17. The wafer of claim 16, wherein the substrate has cavities corresponding to the plurality of array units, each of the cavities has a central axis perpendicular to the corresponding first back plate, each of the second supports has an outer sidewall away from the corresponding central axis,

each array unit further comprises a first support part positioned between the corresponding first back plate and the substrate, each first support part has an outer side wall far away from the corresponding central axis,

the diaphragm extends to the surface of the substrate sequentially through the surface of the second supporting part, the outer side wall of the second supporting part, the side wall of the first back plate and the outer side wall of the first supporting part.

18. The microelectromechanical structure of claim 17, further comprising:

a plurality of third supporting parts located on the diaphragm and corresponding to the plurality of array units; and

and the second back plates are respectively positioned on the corresponding third supporting parts.

19. The microelectromechanical structure of claim 18, each of the third supports having an outer sidewall distal from the corresponding central axis,

each third supporting part is provided with a sunken part and extends to the vibrating diaphragm along the outer side wall corresponding to the third supporting part.

20. A microelectromechanical structure comprising:

a substrate having a cavity;

a first backplate located over the substrate;

the second supporting part is positioned on the first back plate;

the vibrating diaphragm is positioned on the second supporting part; and

a second backplate supported on the diaphragm in an insulating manner,

wherein the cavity has a central axis perpendicular to the first back plate, the second support portion has an outer sidewall far away from the central axis,

the diaphragm extends to the substrate sequentially through the surface of the second supporting part, the outer side wall of the second supporting part and the side wall of the first back plate and covers the surface edge of the substrate.

21. The microelectromechanical structure of claim 20, further comprising a first support between the substrate and the first back plate,

the first supporting part is provided with an outer side wall far away from the central axis, and the vibrating diaphragm also covers the outer side wall of the first supporting part.

22. The microelectromechanical structure of claim 21, further comprising a third support portion positioned between the diaphragm and the second back plate.

23. The microelectromechanical structure of claim 22 wherein the third support portion has an outer sidewall distal from the central axis, the second back plate comprising: a lower dielectric layer, a conductive layer, and an upper dielectric layer,

wherein a portion of the conductive layer is located between the lower dielectric layer and the upper dielectric layer,

and the other part of the conducting layer is used as a sunken part of the second back plate, penetrates through the lower dielectric layer and extends to the vibrating diaphragm along the outer side wall of the third supporting part.

24. The microelectromechanical structure of claim 23 wherein in the second back plate, the upper dielectric layer is connected to the lower dielectric layer through the conductive layer to separate the conductive layer on the third support portion into a center portion and an edge portion,

the edge part of the conducting layer surrounds the central part, and the sunken part of the second back plate is connected with the edge part of the conducting layer.

25. The microelectromechanical structure of claim 24 wherein a portion of the third support portion is coupled to the second support portion through the diaphragm to divide the diaphragm into a center portion and an edge portion,

the edge portion of the diaphragm surrounds the central portion, and the edge portion of the diaphragm extends to the substrate along the outer side wall of the second support portion, the side wall of the first back plate and the outer side wall of the first support portion.

26. The microelectromechanical structure of any of claims 21-25, wherein the outer sidewall of the second support, the sidewall of the first back plate, and the outer sidewall of the first support form a ramp.

27. A microphone comprising a microelectromechanical structure of any of claims 20-26.

28. A terminal comprising a microphone as claimed in claim 27.

Technical Field

The present application relates to the field of semiconductor device manufacturing, and more particularly, to a micro-electromechanical structure, a method of manufacturing the same, a wafer, a microphone, and a terminal.

Background

Microphones manufactured based on Micro Electro Mechanical Systems (MEMS) are called MEMS microphones, and mainly include a diaphragm and a back plate with a gap therebetween. The change of atmospheric pressure can lead to the vibrating diaphragm to warp, and the capacitance value between vibrating diaphragm and the electrode board changes to convert the signal of telecommunication output into.

In a common MEMS microphone, it is necessary to remove a part of the sacrificial layer by a release process so that a gap is formed between the backplate and the diaphragm. However, the release solution in the release process corrodes from the scribe streets to the lateral direction of the die, so that the outer side wall of the support part formed by each sacrificial layer is irregular in shape and difficult to control in size, and even the support part is completely corroded, which may cause stress variation of the back plate and the diaphragm of the die, and affect the performance of the product. In addition, the outer side wall of each supporting part is irregular in shape, so that the mechanical strength of the backboard and the vibrating diaphragm at the joint of the supporting parts is affected, the strength of the tube core is insufficient, and the failure can be caused by slight impact or falling.

Furthermore, because most of the materials of the diaphragm are made of polysilicon, the polysilicon material has an influence on the scribing process, and therefore, the diaphragm corresponding to the scribing position needs to be etched and removed. However, most of the substrate materials are monocrystalline silicon, and during the process of etching the diaphragm, the monocrystalline silicon substrate is also etched to form defects. In the subsequent release process, the substrate having defects causes the mechanical properties of the product to be deteriorated, thereby affecting the yield of the product.

Accordingly, it is desirable to provide an improved microelectromechanical structure to improve the performance of the product.

Disclosure of Invention

In view of the above, the present invention provides an improved micro-electromechanical structure, a method for manufacturing the same, a wafer, a microphone and a terminal, in which the risk of erosion of the release liquid from the outer sidewall of the second support portion in the release process is reduced by covering the outer sidewall of the second support portion with a diaphragm.

According to a first aspect of the embodiments of the present invention, there is provided a method for manufacturing a micro-electromechanical structure, including: forming a first backplane over a substrate; forming a second sacrificial layer on the first backplane; forming a vibrating diaphragm on the second sacrificial layer, wherein the vibrating diaphragm extends to the substrate along the side wall of the second sacrificial layer and the side wall of the first back plate; forming a cavity in the substrate; and removing part of the second sacrificial layer, wherein the rest second sacrificial layer is used as a second support part.

Optionally, before forming the first back plate, the manufacturing method further includes: forming a first sacrificial layer on a substrate, and after the diaphragm is formed, removing a part of the first sacrificial layer, wherein the remaining first sacrificial layer serves as a first supporting portion, the first back plate is located between the first sacrificial layer and the second sacrificial layer, and the diaphragm is further in contact with a side wall of the first sacrificial layer.

Optionally, the method further comprises: forming a third sacrificial layer on the diaphragm; forming a second backplane on the third sacrificial layer; and removing part of the third sacrificial layer, wherein the rest third sacrificial layer is used as a third supporting part.

Optionally, the step of forming the second back plate comprises: forming a lower dielectric layer on the third sacrificial layer; forming a first groove extending from the surface of the lower medium layer to the surface of the diaphragm; forming a conducting layer on the lower medium layer, wherein the conducting layer is also filled in the first groove and is connected with the vibrating diaphragm; and forming an upper dielectric layer on the conductive layer, wherein the conductive layer filled in the first groove is used as a sinking part of the second back plate.

Optionally, the conductive layer of the second backplane is a polysilicon conductive layer.

Optionally, before forming the upper dielectric layer on the conductive layer, the step of forming the second backplane further includes: and forming a second groove extending from the surface of the conductive layer to the surface of the lower medium layer to divide the conductive layer on the third sacrificial layer into a central part and an edge part, wherein the edge part of the conductive layer surrounds the central part, the sunken part of the second back plate is connected with the edge part of the conductive layer, and the upper medium layer also covers the side surface and the bottom surface of the second groove.

Optionally, before forming the third sacrificial layer, the manufacturing method further includes: forming a third groove extending from the surface of the diaphragm to the surface of the second sacrificial layer to divide the diaphragm on the second sacrificial layer into a central portion and an edge portion, wherein the edge portion of the diaphragm surrounds the central portion, the edge portion of the diaphragm sequentially extends to the substrate along the sidewall of the second sacrificial layer, the sidewall of the first back plate and the sidewall of the first sacrificial layer, and the third sacrificial layer is further filled in the third groove.

Optionally, before forming the diaphragm, the manufacturing method further includes: and forming an isolation groove extending from the surface of the second sacrificial layer to the surface of the substrate, wherein the isolation groove divides a laminated structure consisting of the first sacrificial layer, the first backboard and the second sacrificial layer into a plurality of units arranged in an array manner, and the vibration film covers the side surface and the bottom surface of the isolation groove.

Optionally, the step of forming the isolation trench includes: removing a portion of the second back plate to expose a portion of the first sacrificial layer before forming the second sacrificial layer, the second sacrificial layer being formed thereafter to be connected to the exposed first sacrificial layer; and removing a part of the second sacrificial layer and the first sacrificial layer at the joint of the second sacrificial layer and the first sacrificial layer to form the isolation groove.

Optionally, the step of forming the isolation trench further includes: after removing part of the second back plate and before forming the second sacrificial layer, removing part of the first sacrificial layer to expose part of the substrate, wherein the second sacrificial layer formed later is also connected with the exposed substrate.

Optionally, an isotropic wet etching process is used to remove a portion of the second sacrificial layer and the first sacrificial layer, so that the side surface of the isolation trench is an inclined surface, wherein the width of the bottom surface of the isolation trench is smaller than the width of the opening of the isolation trench.

Optionally, the diaphragm is a polysilicon diaphragm.

Optionally, the isolation groove exposes a surface of the substrate, and the step of forming the diaphragm includes: depositing amorphous silicon on the surface of the second sacrificial layer, the side face of the isolation groove and the exposed surface of the substrate; and growing amorphous silicon in contact with the exposed substrate along the crystal of the substrate by an annealing process.

Optionally, the polysilicon diaphragm has a doping impurity, and the doping impurity includes phosphorus.

Optionally, after removing a portion of the second sacrificial layer, the manufacturing method further includes cutting the substrate and the diaphragm along a scribe lane to separate the plurality of cells arranged in an array, where a position of the scribe lane corresponds to the isolation groove.

According to a second aspect of the embodiments of the present invention, there is provided a wafer having scribe lanes, the wafer including: a substrate; a plurality of array units located above the substrate, adjacent array units being separated by the scribe lanes; and the vibrating diaphragm covers the plurality of array units and the surface of the substrate where the scribing channel is located, wherein each array unit comprises a first back plate and a second supporting part located on the first back plate.

Optionally, the substrate has cavities corresponding to the plurality of array units, each of the cavities has a central axis corresponding to a perpendicular to the first back plate, each of the second support portions has an outer sidewall away from the corresponding central axis, each of the array units further includes a first support portion located between the corresponding first back plate and the substrate, each of the first support portions has an outer sidewall away from the corresponding central axis, and the diaphragm sequentially extends onto the surface of the substrate through the surface of the second support portion, the outer sidewall of the second support portion, the sidewall of the first back plate, and the outer sidewall of the first support portion.

Optionally, the method further comprises: a plurality of third supporting parts located on the diaphragm and corresponding to the plurality of array units; and a plurality of second back plates respectively positioned on the corresponding third supporting parts.

Optionally, each of the third supporting portions has an outer sidewall far from the corresponding central axis, and each of the third supporting portions has a sinking portion extending onto the diaphragm along the outer sidewall corresponding to the third supporting portion.

According to a third aspect of embodiments of the present invention, there is provided a micro-electromechanical structure, comprising: a substrate having a cavity; a first backplate located over the substrate; the second supporting part is positioned on the first back plate; the vibrating diaphragm is positioned on the second supporting part; and the second back plate is supported on the vibrating diaphragm in an insulating mode, the cavity is provided with a central axis perpendicular to the first back plate, the second supporting part is provided with an outer side wall far away from the central axis, and the vibrating diaphragm sequentially extends to the substrate through the surface of the second supporting part, the outer side wall of the second supporting part and the side wall of the first back plate and covers the surface edge of the substrate.

Optionally, the display device further includes a first supporting portion located between the substrate and the first back plate, wherein the first supporting portion has an outer sidewall far away from the central axis, and the diaphragm further covers the outer sidewall of the first supporting portion.

Optionally, the apparatus further includes a third supporting portion located between the diaphragm and the second back plate.

Optionally, the third support portion has an outer side wall away from a central axis of the cavity, and the second back plate includes: the second support part is arranged on the lower medium layer, the upper medium layer is arranged on the lower medium layer, and the lower medium layer is arranged on the upper medium layer.

Optionally, in the second back plate, the upper dielectric layer penetrates through the conductive layer and is connected to the lower dielectric layer, so as to separate the conductive layer on the third supporting portion into a central portion and an edge portion, wherein the edge portion of the conductive layer surrounds the central portion, and the sinking portion of the second back plate is connected to the edge portion of the conductive layer.

Optionally, a portion of the third supporting portion passes through the diaphragm and is connected to the second supporting portion, so as to divide the diaphragm located on the second supporting portion into a central portion and an edge portion, where the edge portion of the diaphragm surrounds the central portion, and the edge portion of the diaphragm sequentially extends to the substrate along an outer sidewall of the second supporting portion, a sidewall of the first back plate, and an outer sidewall of the first supporting portion.

Optionally, the outer sidewall of the second supporting portion, the sidewall of the first back plate, and the outer sidewall of the first supporting portion form an inclined plane, and an acute angle is formed between the outer sidewall of the first supporting portion and the inclined plane in a direction toward the central axis of the cavity.

According to a fourth aspect of embodiments of the present invention, there is provided a microphone comprising a microelectromechanical structure as described above.

According to a fifth aspect of embodiments of the present invention, there is provided a terminal including the microphone as described above.

In the manufacturing method of the micro-electromechanical structure provided by the embodiment of the invention, in the step of forming the diaphragm, the diaphragm extends to the substrate along the side wall of the second sacrificial layer and the side wall of the first back plate, so that when the second support part of the second sacrificial layer is utilized, the risk that release liquid erodes from the outer side wall of the second support part in the release process is reduced.

In a similar way, under the condition that the first supporting part is formed by the first sacrificial layer, the vibrating diaphragm covers the side wall of the first sacrificial layer, and the risk that the releasing liquid erodes from the outer side wall of the first supporting part in the releasing process is reduced.

The sinking portion is arranged in the second back plate, the second back plate sinking portion extends to the vibrating diaphragm from the outer side wall of the third supporting portion, and the second back plate sinking portion is continuous with the main body portion (the portion located on the third supporting portion) of the second back plate, so that the mechanical strength of the junction of the second back plate and the outer side wall of the third supporting portion is increased, and the performance of a product is improved. Meanwhile, the appearance and the peripheral size of the outer side wall of the third supporting part are further limited by the second back plate sinking part, the release solution of the release process is prevented from being corroded from the outer side wall of the third supporting part, and the consistency and the surface smoothness of the product are improved.

Because the material of the sinking part of the second back plate and the material of the vibrating diaphragm are both polysilicon, the single-material polysilicon protection wall formed by the area of the vibrating diaphragm covering the first back plate, the first supporting part and the second supporting part and the sinking part of the second back plate reduces the defect of a contact interface, thereby further improving the corrosion resistance of the released solution.

The side of the isolation groove is made into an inclined plane by adopting an isotropic wet etching process, the width of the bottom surface of the isolation groove is smaller than the width of the opening of the isolation groove, when a material for forming the vibrating diaphragm is deposited, the inclined plane is continuous and does not form a step, so that the side of the isolation groove can be more uniformly covered by the vibrating diaphragm material, the covering effect of the vibrating diaphragm is enhanced, the corrosion resistance to the release solution is further improved, and the protection effect of the vibrating diaphragm on the first supporting part, the second supporting part and the first back plate can be enhanced.

By separating the conductive layer in the second backplane into a center portion and an edge portion, the sunken portion of the second backplane is connected to the edge portion of the conductive layer and electrically isolated from the center portion, thereby reducing parasitic capacitance in the product. By dividing the diaphragm into a center portion and an edge portion, the portion connected to the substrate is the edge portion of the diaphragm, electrically isolated from the center portion, thereby reducing parasitic capacitance in the product.

By extending the diaphragm into the scribe lane, the diaphragm in the scribe lane serves as an etch stop layer to protect the scribe lane under the condition of etching the structure above the diaphragm, and preferably, the polysilicon diaphragm is doped with phosphorus to further improve the etch selectivity, thereby more effectively protecting the substrate.

When the polysilicon diaphragm is formed, amorphous silicon (amorphous silicon α -Si), which is also called amorphous silicon, is a form of elemental silicon, is deposited in the isolation trench so that the amorphous silicon is in contact with the substrate on the bottom surface of the isolation trench. In the annealing process, the amorphous silicon on the bottom surface of the isolation groove grows along the crystal orientation growth crystal orientation of the substrate, so that the crystal orientation of the polycrystalline silicon diaphragm in contact with the substrate is consistent with the crystal orientation of the substrate, and the influence of the polycrystalline silicon diaphragm on the scribing process is small during scribing, so that the polycrystalline silicon diaphragm in the scribing channel does not need to be removed, and the damage to the substrate caused by removing the polycrystalline silicon diaphragm is avoided.

Therefore, the micro-electromechanical structure, the manufacturing method thereof, the wafer, the microphone and the terminal provided by the invention can greatly improve the performance of products.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings of the embodiments will be briefly introduced below, and it is apparent that the drawings in the following description only relate to some embodiments of the present application and are not limiting on the present application.

Fig. 1 shows a schematic view of a micro-electromechanical structure of a first embodiment of the invention.

Fig. 2a and 2g show schematic diagrams in the manufacturing steps of the micro-electromechanical structure according to the first embodiment of the present invention.

Fig. 3 shows a schematic view of a microelectromechanical structure of a second embodiment of the invention.

Detailed Description

The invention will be described in more detail below with reference to the accompanying drawings. Like elements in the various figures are denoted by like reference numerals. For purposes of clarity, the various features in the drawings are not necessarily drawn to scale. In addition, certain well known components may not be shown. For simplicity, the semiconductor structure obtained after several steps can be described in one figure.

It will be understood that when a layer or region is referred to as being "on" or "over" another layer or region in describing the structure of the device, it can be directly on the other layer or region or intervening layers or regions may also be present. And, if the device is turned over, that layer, region, or regions would be "under" or "beneath" another layer, region, or regions.

If for the purpose of describing the situation directly on another layer, another area, the expressions "directly on … …" or "on … … and adjacent thereto" will be used herein.

In the following description, numerous specific details of the invention, such as structure, materials, dimensions, processing techniques and techniques of the devices are described in order to provide a more thorough understanding of the invention. However, as will be understood by those skilled in the art, the present invention may be practiced without these specific details.

The present invention may be embodied in various forms, some examples of which are described below.

Fig. 1 shows a schematic diagram of a micro-electromechanical structure according to a first embodiment of the present invention, wherein a dot-dash line indicates a central axis perpendicular to a cavity 101a of a first backplate 120, a diaphragm 130, and a second backplate 140.

As shown in fig. 1, the micro-electromechanical structure of the first embodiment of the present invention includes: the diaphragm includes a substrate 101, a first supporting portion 111, a second supporting portion 112, a third supporting portion 113, a first back plate 120, a diaphragm 130, and a second back plate 140. The substrate 101 has a cavity 101 a. The first support 111 is located at an edge of the substrate 101, and has an inner sidewall close to a central axis of the chamber 101a and an outer sidewall far from the central axis of the chamber 101 a. The first back plate 120 is positioned on the first supporting part 111 and covers the chamber 101 a. The second supporting portion 112 is located on the first back plate 120 and corresponds to the first supporting portion 111, and the second supporting portion 112 has an inner sidewall close to the central axis of the chamber 101a and an outer sidewall far away from the central axis of the chamber 101 a. The diaphragm 130 is located on the second supporting portion 112, and has a gap 102 with the first back plate 120. The third supporting portion 113 is located on the diaphragm 130, and the position of the third supporting portion 113 corresponds to the second supporting portion 112, and the third supporting portion 113 has an inner sidewall close to the central axis of the cavity 101a and an outer sidewall far away from the central axis of the cavity 101 a. The second back plate 140 is located on the third supporting portion 113, and has a gap 103 with the diaphragm 130.

In this embodiment, the diaphragm 130 sequentially extends onto the substrate 101 along the surface of the second support portion 112, the outer sidewall of the second support portion 112, the sidewall of the first back plate 120, and the outer sidewall of the first support portion 111, and covers the surface edge of the substrate 101. In some specific embodiments, the outer sidewall of the second support portion 112, the sidewall of the first back plate 120, and the outer sidewall of the first support portion 111 form slopes. Wherein, the person skilled in the art can set the inclination angle of the inclined plane as required.

In this embodiment, the second backplate 140 has a sunken portion 140a, the sunken portion 140a of the second backplate has an inner side wall close to the central axis of the cavity 101a and an outer side wall far from the central axis of the cavity 101a, and the sunken portion 140a of the second backplate extends to the diaphragm 130 along the outer side wall of the third support portion 113.

In some embodiments, the first back-plate 120 includes a lower dielectric layer 121, a conductive layer 122, and an upper dielectric layer 123, wherein the conductive layer 122 is sandwiched between the upper dielectric layer 123 and the lower dielectric layer 121. The second back plate 140 includes a lower dielectric layer 141, a conductive layer 142 and an upper dielectric layer 143, wherein a portion of the conductive layer 142 is sandwiched between the upper dielectric layer 143 and the lower dielectric layer 141, and another portion of the conductive layer 142, which is used as a sunken portion 140a of the second back plate, penetrates through the lower dielectric layer 141 and extends onto the diaphragm 130 along an outer sidewall of the third support portion 113.

More specifically, the conductive layer 122 and the conductive layer 142 are both made of the same material as the diaphragm 130, such as polysilicon, the upper dielectric layer 123, the lower dielectric layer 121, the upper dielectric layer 143, and the lower dielectric layer 141 are all made of silicon nitride, the first support portion 111, the second support portion 112, and the third support portion 113 are all made of silicon oxide, and the substrate 101 is a silicon substrate or other substrates. Of course, other arrangements of the materials of the substrate 101, the first supporting portion 111, the second supporting portion 112, the third supporting portion 113, the first back plate 120, the diaphragm 130 and the second back plate 140 may be performed by those skilled in the art according to the needs.

In the present embodiment, the portions of the first backplate 120, the diaphragm 130, and the second backplate 140 corresponding to the gaps 102, 103 are effective portions, and a person skilled in the art can electrically isolate the substrate 101, the effective portion of the first backplate 120, the effective portion of the diaphragm 130, and the effective portion of the second backplate 140 from each other as needed. Taking the second back plate 140 as an example, in some specific embodiments, the upper dielectric layer 143 in the second back plate 140 is connected to the lower dielectric layer 141 through the conductive layer 142 to separate the conductive layer 142 on the third supporting portion 113 into a central portion and an edge portion, so that the central portion and the edge portion of the conductive layer 142 are electrically isolated, the edge portion of the conductive layer 142 surrounds the central portion, and the sunken portion 140a of the second back plate is connected to the edge portion of the conductive layer 142. The connection between the upper dielectric layer 143 and the lower dielectric layer 141 corresponds to the third supporting portion 113, such that the central portion of the conductive layer 142 includes the effective portion of the second back plate 140, and the effective portion of the second back plate 140 is electrically isolated from the sunken portion 140a of the second back plate.

In this embodiment, the diaphragm 130 covers the outer sidewall of the second supporting portion 112, the sidewall of the first back plate 120, and the orthographic projection of the outer sidewall of the first supporting portion 112 on the surface of the substrate 101 to form an annular surrounding cavity 101a, and the orthographic projection of the sinker 140a of the second back plate on the surface of the substrate 101 to form an annular surrounding cavity 101 a. The first support part 111 is a part left on the substrate 101 after the sacrificial layer is released, the first support part 111 is located on the peripheral edge of the substrate 101, and the first back plate 120 located above the first support part 111 is supported on the substrate 101 in a manner that the peripheral edge is fully supported. The second supporting portion 112 is a portion left on the first back plate 120 after the sacrificial layer is released, the second supporting portion 112 is located on the peripheral edge of the first back plate 120, and the diaphragm 130 located above the second supporting portion 112 is supported and fixed by a full-solid-supported manner of the peripheral edge. The third supporting portion 113 is a portion left on the diaphragm 130 after the sacrificial layer is released, the third supporting portion 113 is located on the peripheral edge of the diaphragm 130, and the second backplate 140 located above the third supporting portion 113 is supported and fixed by a full-clamped manner of the peripheral edge.

In this embodiment, the mems further includes a plurality of bonding pads (not shown) on the second backplate 140 for electrically connecting with the second backplate 140, the diaphragm 130 and the first backplate 120.

Further, the first backplate 120 has a plurality of sound holes 11, and the second backplate 140 has a plurality of sound holes 12 to use the mems structure for a microphone. The diaphragm 130 may further be provided with air release holes (not shown), wherein the number, shape and size of the sound holes 11 and the air release holes may be set as required by those skilled in the art. The mems structure of this embodiment further includes a plurality of anti-adhesion structures 150, which are located on the surface of the second backplate 140 close to the diaphragm 130 to prevent the adhesion between the second backplate 140 and the diaphragm 130, and the plurality of anti-adhesion structures 150 are also located on the surface of the diaphragm 130 close to the first backplate 120 to prevent the adhesion between the first backplate 120 and the diaphragm 130.

The mems structure shown in fig. 1 is a dual-backplate, single-diaphragm structure, and in some other embodiments, the third support portion 113 and the second backplate 140 may not be provided, so as to form a single-backplate, single-diaphragm structure. In still other embodiments, the first support part 111 may not be provided.

Fig. 2a and 2g show schematic diagrams in the manufacturing steps of the micro-electromechanical structure according to the first embodiment of the present invention.

As shown in fig. 2a, a first sacrificial layer 211 is formed on the substrate 101, and a first back plate 120 is formed on the first sacrificial layer 211.

In some specific embodiments, the step of forming the second back plate 120 includes: a lower dielectric layer 121 is formed on the first sacrificial layer 211, a conductive layer 122 is formed on the lower dielectric layer 121, and an upper dielectric layer 123 is formed on the conductive layer 122.

Further, a portion of the first backplane 120 is removed at the scribe lanes 20 to expose the first sacrificial layer 211, as shown in fig. 2 b. In some preferred embodiments, the first sacrificial layer 211 at the scribe lanes 20 is removed to expose portions of the substrate 101.

Further, a second sacrificial layer 212 is formed on the first back plate 120, as shown in fig. 2c, and the second sacrificial layer 212 is connected to the exposed first sacrificial layer 211 and the exposed substrate 101.

Further, in the vicinity of the scribe lane 20, a portion of the second sacrificial layer 212 and the first sacrificial layer 211 is removed to form an isolation trench 104, as shown in fig. 2 d.

In this step, the second sacrificial layer 212 and the first sacrificial layer 211 are made of the same material, for example, silicon oxide, and an isotropic wet etching process is used to remove a portion of the second sacrificial layer 212 and the first sacrificial layer 211, so that the side surfaces of the isolation trench 104 are inclined, wherein the width of the bottom surface of the isolation trench 104 is smaller than the width of the opening of the isolation trench 104.

In the embodiment, the isolation trench 104 extends from the surface of the second sacrificial layer 212 to the surface of the substrate 101, the surface of the substrate 101 at the scribe line 20 is exposed, and the isolation trench 104 divides the stacked structure composed of the first sacrificial layer 211, the first backplane 120 and the second sacrificial layer 212 into a plurality of cells arranged in an array.

Further, the diaphragm 130 is formed on the second sacrificial layer 212, and in each unit, the diaphragm 130 extends onto the substrate 101 along the surface of the second sacrificial layer 212, the sidewall of the first backplate 120, and the sidewall of the first sacrificial layer 211 in sequence, as shown in fig. 2 e.

In the present embodiment, the diaphragm 130 covers the side surfaces and the bottom surface (the surface of the substrate 101 exposed at the dicing streets 20) of the isolation grooves 104 in the vicinity of the streets 20. Since the side of the isolation groove 104 is a slope, the diaphragm 130 has better coverage in the isolation groove 104.

In the step of forming the diaphragm 130, for example, amorphous silicon is deposited on the surface of the second sacrificial layer 212, the side surface of the isolation groove 104 and the surface of the exposed substrate 101 by a deposition process, and then the diaphragm 130 is formed by growing the amorphous silicon through an annealing process, wherein the amorphous silicon in contact with the exposed substrate 101 grows along the crystal direction of the substrate 101 so as to complete the conversion from the amorphous silicon material to the polycrystalline silicon material. Optionally, the polysilicon diaphragm has doping impurities including, but not limited to, phosphorus atoms.

Further, a third sacrificial layer 213 is formed on the diaphragm 130, as shown in fig. 2 f.

In the present embodiment, the material of the third sacrificial layer 213 is the same as that of the second sacrificial layer 212, and the third sacrificial layer 213 covers the diaphragm 130 and fills the isolation groove 104. In some preferred embodiments, the surface of the third sacrificial layer 213 is planarized using a chemical mechanical polishing process.

Further, a second back plate 140 is formed on the third sacrificial layer 213 corresponding to each cell, as shown in fig. 2 f.

In this step, for example, a lower dielectric layer 141 is formed on the third sacrificial layer 213; then, for example, an etching process is used to form a first groove extending from the surface of the lower dielectric layer 141 to the surface of the diaphragm 130; then, forming a conductive layer 142 on the lower dielectric layer 141, wherein the conductive layer 142 is further filled in the first groove and connected to the diaphragm 130; finally, an upper dielectric layer 143 is formed on the conductive layer 142, wherein the conductive layer 142 filled in the first groove serves as a sunken portion of the second backplane 140.

In some preferred embodiments, the step of forming the second backplane 140 further comprises, before forming the upper dielectric layer 143 on the conductive layer 142: a second groove extending from the surface of the conductive layer 142 to the surface of the lower dielectric layer 141 is formed to separate the conductive layer 142 on the third sacrificial layer 213 into a central portion and an edge portion, wherein the edge portion of the conductive layer 142 surrounds the central portion, the sinking portion 140a of the second backplate 140 is connected to the edge portion of the conductive layer 142, and the upper dielectric layer 143 further covers the side surface and the bottom surface of the second groove.

Further, a cavity 101a is formed in the substrate 101 corresponding to each cell, as shown in fig. 2 f.

Further, a portion of the first sacrificial layer, a portion of the second sacrificial layer, and a portion of the third sacrificial layer are removed, the remaining first sacrificial layer serves as the first support portion 111, the remaining second sacrificial layer serves as the second support portion 112, and the remaining third sacrificial layer serves as the third support portion 113, as shown in fig. 2 g.

In this step, the third sacrificial layer 213 covers the diaphragm 130 and the substrate 101 at the scribe lanes 20 of the wafer, and in order to facilitate the subsequent scribing process, the third sacrificial layer 213 at the scribe lanes 20 needs to be removed. In the release process, the release solution removes a portion of the sacrificial layer through the sound hole of the second back plate, the sound hole of the first back plate, and the back cavity of the substrate to form the first support part 111, the second support part 112, and the third support part 113. At the same time, the release solution also removes the third sacrificial layer at the scribe streets 20 to re-expose the diaphragm 130 near the scribe streets 20. In this process, the diaphragm 130 and the sunken portion 140a of the second back plate serve as an etching stop layer to protect the substrate 101, the first support portion 111, the second support portion 112, and the third support portion 113.

Further, the substrate 101 and the diaphragm 130 are cut at the scribe line 20 to separate a plurality of units arranged in an array, so as to form the micro-electromechanical structure shown in fig. 1, where the manner of cutting the substrate 101 and the diaphragm 130 includes, but is not limited to, laser cutting.

Fig. 3 shows a schematic view of a microelectromechanical structure of a second embodiment of the invention.

As shown in fig. 3, the second embodiment of the present invention is different from the first embodiment in that a portion of the third support portion 113 is connected to the second support portion 112 through the diaphragm 130 to divide the diaphragm 130 into a central portion and an edge portion, wherein the edge portion of the diaphragm 130 surrounds the central portion, and the edge portion of the diaphragm 130 extends onto the substrate 101 along an outer sidewall of the second support portion 112, a sidewall of the first back plate 120, and an outer sidewall of the first support 111 portion in this order.

Accordingly, the manufacturing method of the micro-electromechanical structure according to the second embodiment of the present invention can refer to the descriptions of fig. 2a to fig. 2g, and will not be described again here. The difference is that before the third sacrificial layer 213 is formed, a third groove extending from the surface of the diaphragm 130 to the surface of the second sacrificial layer 212 needs to be formed to separate the diaphragm 130 into a central portion and an edge portion, wherein the edge portion of the diaphragm 130 surrounds the central portion and extends onto the substrate 101 along the sidewall of the second sacrificial layer 212, the sidewall of the first backplate 120, and the sidewall of the first sacrificial layer 211. After the third sacrificial layer 213 is formed, the third sacrificial layer 213 is also filled in the third groove.

The invention also provides a microphone comprising the micro-electromechanical structure.

The invention also provides a terminal comprising the microphone.

In the method for manufacturing a micro-electromechanical structure provided by the embodiment of the invention, in the step of forming the diaphragm, the diaphragm sequentially extends to the substrate along the side wall of the second sacrificial layer, the side wall of the first back plate and the side wall of the first sacrificial layer, so that when the first supporting part and the second supporting part are formed by using the first sacrificial layer and the second sacrificial layer, the risk that release liquid erodes from the outer side walls of the first supporting part and the second supporting part in a release process is reduced.

The sinking portion is arranged in the second back plate, the second back plate sinking portion extends to the vibrating diaphragm from the outer side wall of the third supporting portion, and the second back plate sinking portion is continuous with the main body portion (the portion located on the third supporting portion) of the second back plate, so that the mechanical strength of the junction of the second back plate and the outer side wall of the third supporting portion is increased, and the performance of a product is improved. Meanwhile, the appearance and the peripheral size of the outer side wall of the third supporting part are further limited by the second back plate sinking part, the release solution of the release process is prevented from being corroded from the outer side wall of the third supporting part, and the consistency and the surface smoothness of the product are improved.

Because the material of the sinking part of the second back plate and the material of the vibrating diaphragm are both polysilicon, the single-material polysilicon protection wall formed by the area of the vibrating diaphragm covering the first back plate, the first supporting part and the second supporting part and the sinking part of the second back plate reduces the defect of a contact interface, thereby further improving the corrosion resistance of the released solution.

The side of the isolation groove is made into an inclined plane by adopting an isotropic wet etching process, the width of the bottom surface of the isolation groove is smaller than the width of the opening of the isolation groove, when a material for forming the vibrating diaphragm is deposited, the inclined plane is continuous and does not form a step, so that the side of the isolation groove can be more uniformly covered by the vibrating diaphragm material, the covering effect of the vibrating diaphragm is enhanced, the corrosion resistance to the release solution is further improved, and the protection effect of the vibrating diaphragm on the first supporting part, the second supporting part and the first back plate can be enhanced.

By separating the conductive layer in the second backplane into a center portion and an edge portion, the sunken portion of the second backplane is connected to the edge portion of the conductive layer and electrically isolated from the center portion, thereby reducing parasitic capacitance in the product. By dividing the diaphragm into a center portion and an edge portion, the portion connected to the substrate is the edge portion of the diaphragm, electrically isolated from the center portion, thereby reducing parasitic capacitance in the product.

By extending the diaphragm into the scribe lane, the diaphragm in the scribe lane acts as an etch stop layer to protect the scribe lane in the event that structures above the diaphragm are etched. Preferably, the polysilicon diaphragm is doped with phosphorus to further improve the etching selection ratio, thereby more effectively protecting the substrate.

When forming the polycrystalline silicon vibrating diaphragm, through with amorphous silicon deposit in the isolation tank, make the substrate contact of amorphous silicon and isolation tank bottom surface, at the in-process of annealing, the amorphous silicon that is located the isolation tank bottom surface can be along the crystal orientation crystal growth of the crystal orientation growth of substrate, thereby make the polycrystalline silicon vibrating diaphragm crystal orientation and the substrate crystal orientation unanimous with the substrate contact, this polycrystalline silicon vibrating diaphragm is less to the influence of scribing technology when the scribing, consequently, the polycrystalline silicon vibrating diaphragm that is located the scribing way need not be got rid of, thereby avoided because of getting rid of the damage that the polycrystalline silicon vibrating diaphragm caused the substrate.

Therefore, the micro-electromechanical structure, the manufacturing method thereof, the wafer, the microphone and the terminal provided by the invention can greatly improve the performance of products.

In the above description, the technical details of patterning, etching, and the like of each layer are not described in detail. It will be appreciated by those skilled in the art that layers, regions, etc. of the desired shape may be formed by various technical means. In addition, in order to form the same structure, those skilled in the art can also design a method which is not exactly the same as the method described above. In addition, although the embodiments are described separately above, this does not mean that the measures in the embodiments cannot be used in advantageous combination.

The embodiments of the present invention have been described above. However, these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. The scope of the invention is defined by the appended claims and equivalents thereof. Various alternatives and modifications can be devised by those skilled in the art without departing from the scope of the invention, and these alternatives and modifications are intended to fall within the scope of the invention.