阅读说明：本技术 Mems传感器及其微机电结构、微机电结构的制造方法 (MEMS sensor, MEMS structure thereof and manufacturing method of MEMS structure ) 是由 孟燕子 孙恺 荣根兰 胡维 于 2021-02-25 设计创作，主要内容包括：本申请公开了一种MEMS传感器及其微机电结构、微机电结构的制造方法。该微机电结构包括：背板,具有至少一个通孔；感应膜,包括运动区、非运动区、连接运动区与非运动区的梁结构,运动区与背板构成可变电容；至少一个连接柱,每个连接柱的一端与感应膜的运动区固定连接；以及至少一个可动结构,分别位于相应的通孔中以与背板分离,每个可动结构与相应的连接柱的另一端固定连接,其中,可动结构在感应膜上的正投影与部分非运动区重合。该微机电结构通过可动结构对感应膜的形变程度进行限制,从而提高MEMS传感器的抗机械冲击能力。(The application discloses a Micro Electro Mechanical System (MEMS) sensor, a MEMS structure and a manufacturing method of the MEMS structure. The micro-electromechanical structure comprises: a back plate having at least one through hole; the sensing film comprises a motion area, a non-motion area and a beam structure for connecting the motion area and the non-motion area, wherein the motion area and the back plate form a variable capacitor; one end of each connecting column is fixedly connected with the moving area of the induction film; and at least one movable structure respectively positioned in the corresponding through holes to be separated from the back plate, wherein each movable structure is fixedly connected with the other end of the corresponding connecting column, and the orthographic projection of the movable structure on the sensing film is superposed with a part of the non-moving area. The micro-electro-mechanical structure limits the deformation degree of the sensing film through the movable structure, so that the mechanical impact resistance of the MEMS sensor is improved.)

1. A microelectromechanical structure, comprising:

a back plate having at least one through hole;

the induction film comprises a motion area, a non-motion area and a beam structure for connecting the motion area and the non-motion area, and the motion area and the back plate form a variable capacitor;

one end of each connecting column is fixedly connected with the moving area of the induction film; and

at least one movable structure respectively located in the corresponding through holes to be separated from the back plate, each movable structure being fixedly connected with the other end of the corresponding connecting column,

wherein an orthographic projection of the movable structure on the sensing film coincides with a part of the non-moving area.

2. The microelectromechanical structure of claim 1, characterized in that the connection post is adjacent to and not in contact with the beam structure.

3. The microelectromechanical structure of claim 1, characterized in that the beam structure comprises a bent beam.

4. The microelectromechanical structure of claim 1, further comprising:

a substrate having a back cavity;

the first supporting part is positioned on the substrate and surrounds the back cavity, the sensing film is positioned on the first supporting part, and the non-motion area is fixedly connected with the first supporting part; and

the second supporting part is positioned between the induction membrane and the back plate, and the non-moving area is fixedly connected with the second supporting part.

5. The microelectromechanical structure of claim 4, characterized in that the back plate comprises:

an insulating layer on the second support portion; and

a second conductive layer on the insulating layer,

wherein the position of the second conductive layer corresponds to the motion area.

6. The microelectromechanical structure of claim 5, characterized in that a plurality of the movable structures are evenly distributed at the edge of the second conductive layer.

7. The microelectromechanical structure of claim 1, characterized in that the connecting post is a unitary structure with the movable structure.

8. The microelectromechanical structure of claim 5, further comprising at least one anti-sticking portion on a surface of the insulating layer facing the sensing film, the anti-sticking portion being a unitary structure with the insulating layer,

the back plate further has at least one sound hole corresponding to a motion zone of the sensing membrane,

the induction membrane is provided with at least one air leakage hole and is positioned in the motion area.

9. The microelectromechanical structure of claim 5, characterized in that the second conductive layer is circular,

wherein, along the radial direction of the second conducting layer, the ratio of the length of the movable structure to the radius of the second conducting layer is 1:3 to 1:5,

the distance from the outer peripheral edge of the movable structure to the side wall of the corresponding through hole is 0.5-1.5 micrometers.

10. A microelectromechanical structure of any of claims 1-9, characterized in that the movable structure has an orthographic shape in the thickness direction comprising at least one of a polygon, a circle, an ellipse, and a sector.

11. A MEMS sensor comprising a microelectromechanical structure of any of claims 1 to 10.

12. The microelectromechanical structure of claim 11, characterized in that the microelectromechanical structure comprises at least one of a microphone chip, a pressure sensor chip, a bone conduction chip.

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

forming a back plate having at least one through hole;

forming an induction film, wherein the induction film comprises a motion area, a non-motion area and a beam structure connecting the motion area and the non-motion area, and the motion area and the back plate form a variable capacitor;

forming at least one connecting column, wherein one end of each connecting column is fixedly connected with the motion area of the induction film; and

forming at least one movable structure, each movable structure being respectively located in the corresponding through hole to be separated from the back plate, each movable structure being fixedly connected with the other end of the corresponding connecting column,

wherein an orthographic projection of the movable structure on the sensing film coincides with a part of the non-moving area.

14. The method of manufacturing of claim 13, wherein the connecting stud is adjacent to and not in contact with the beam structure.

15. The method of manufacturing of claim 13, wherein the beam structure comprises a bent beam.

16. The method of manufacturing of claim 13, further comprising forming a first sacrificial layer on the substrate, wherein the step of forming the sensing film comprises:

forming a first conductive layer on the first sacrificial layer;

and etching the first conductive layer to form a groove so as to divide the first conductive layer into the motion area and the non-motion area and to form the beam structure.

17. The method of manufacturing of claim 16, further comprising:

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

etching the second sacrificial layer to form a connecting hole,

wherein the step of forming the back plate includes forming an insulating layer covering the second sacrificial layer and filled in the connection hole, the insulating layer filled in the connection hole being in contact with the sensing film to serve as the connection post.

18. The method of manufacturing of claim 17, wherein the step of forming the back plate further comprises:

forming a second conductive layer on the insulating layer; and

removing part of the insulating layer and part of the second conductive layer to form an isolation groove,

wherein the insulating layer and the second conductive layer surrounded by the isolation groove serve as a movable structure.

19. The method of manufacturing of claim 16, further comprising:

etching the second sacrificial layer to form a conductive hole, wherein the position of the conductive hole corresponds to the non-motion area;

filling a spacer in the conductive hole;

etching the insulating layer and the isolating part to form a conductive channel; and

forming a conductive portion in the conductive channel, the conductive portion being in contact with the non-motion region,

wherein the conductive hole and the connection hole are formed in the same step, the insulating layer is further filled in the conductive hole, and the insulating layer filled in the conductive hole serves as the isolation portion.

20. The method of manufacturing of claim 17, further comprising:

forming a back cavity in the substrate, the back cavity corresponding to the motion zone;

and removing the first sacrificial layer and the second sacrificial layer corresponding to the back cavity, wherein the first sacrificial layer which is not removed serves as a first supporting part, and the second sacrificial layer which is not removed serves as a second supporting part.

Technical Field

The present application relates to the field of semiconductor device manufacturing, and more particularly, to a MEMS sensor and a micro-electromechanical structure thereof, and a method for manufacturing the micro-electromechanical structure.

Background

Sensors manufactured based on Micro Electro Mechanical Systems (MEMS) are called MEMS sensors, which are valued for their extremely small size and good performance. At present, the sensing membrane of the capacitive MEMS sensor is fixed by adopting a periphery fastening type or a beam structure fixing type. The stiffness of the sensing film is mainly determined by the pre-stress and the size. For the peripheral fastening type, the edges of the sensing film are fixed, so that the prestress of the sensing film is increased, the rigidity of the sensing film is increased, the deformation capability of the sensing film is poor, and compared with the beam structure fixed sensing film with the same size, the sensitivity is low, so that the size of the sensing film needs to be reduced by enlarging the area of the sensing film, and the sensitivity and the signal-to-noise ratio of the device are improved. However, as the size of the sensing film increases, the overall size of the MEMS sensor also increases, which is disadvantageous for miniaturization of the device. For the fixed type of the beam structure, the motion area and the non-motion area are separated by the sensing film through the grooves, the motion area is connected with the non-motion area by the beam structure, compared with the surrounding fastening type sensing film, the prestress is reduced, the stress concentration in the deformation process is also reduced, the higher signal-to-noise ratio can be obtained under the smaller size, and the product cost can be further reduced. And a foundation is laid for further miniaturization of electronic products.

However, when the sensing film is fixed by the beam structure, the size of the beam structure is small, so that the mechanical impact resistance of the product is poor, and the product is easy to fail in the application process.

Accordingly, it is desirable to provide an improved MEMS sensor and a micro-electromechanical structure thereof, so as to improve the mechanical shock resistance of the MEMS sensor while ensuring the performance of the MEMS sensor.

Disclosure of Invention

In view of the above, the present invention provides an improved MEMS sensor, a micro-electromechanical structure thereof, and a method for manufacturing the micro-electromechanical structure, wherein the degree of deformation of the sensing film is limited by the movable structure, so as to improve the mechanical shock resistance of the MEMS sensor.

According to a first aspect of embodiments of the present invention, there is provided a microelectromechanical structure, comprising: a back plate having at least one through hole; the induction film comprises a motion area, a non-motion area and a beam structure for connecting the motion area and the non-motion area, and the motion area and the back plate form a variable capacitor; one end of each connecting column is fixedly connected with the moving area of the induction film; and at least one movable structure respectively positioned in the corresponding through holes to be separated from the back plate, wherein each movable structure is fixedly connected with the other end of the corresponding connecting column, and the orthographic projection of the movable structure on the induction film is superposed with part of the non-moving area.

Optionally, the connecting column is adjacent to and not in contact with the beam structure.

Optionally, the beam structure comprises a bent beam.

Optionally, the method further comprises: a substrate having a back cavity; the first supporting part is positioned on the substrate and surrounds the back cavity, the sensing film is positioned on the first supporting part, and the non-motion area is fixedly connected with the first supporting part; and the second supporting part is positioned between the induction membrane and the back plate, and the non-moving area is fixedly connected with the second supporting part.

Optionally, the back plate comprises: an insulating layer on the second support portion; and the second conducting layer is positioned on the insulating layer, wherein the position of the second conducting layer corresponds to the motion area.

Optionally, the plurality of movable structures are uniformly distributed on the edge of the second conductive layer.

Optionally, the connecting column and the movable structure are of a unitary structure.

Optionally, the anti-sticking part is positioned on the surface of the insulating layer facing the sensing film.

Optionally, the anti-sticking part and the insulating layer are of an integral structure.

Optionally, the back plate further has at least one sound hole corresponding to the motion area of the sensing diaphragm, and the sensing diaphragm has at least one air release hole located in the motion area.

Optionally, an orthographic area of the back plate in the thickness direction is 6000 to 15000 times an orthographic area of each of the movable structures in the thickness direction.

Optionally, an orthographic area of the back plate in the thickness direction is 0.2 to 0.3 square millimeters, an orthographic area of the movable structure in the thickness direction is 20 to 30 square micrometers, the second conductive layer is circular, a ratio of a length of the movable structure to a radius of the second conductive layer in a radial direction of the second conductive layer is 1:3 to 1:5, and a distance from an outer peripheral edge of the movable structure to a side wall of the corresponding through hole is 0.5 to 1.5 micrometers.

Optionally, an orthographic shape of the movable structure in the thickness direction includes at least one of a polygon, a circle, an ellipse, and a fan.

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

Optionally, the micro-electromechanical structure comprises at least one of a microphone chip, a pressure sensor chip, and a bone conduction chip.

According to a third aspect of the embodiments of the present invention, there is provided a method for manufacturing a micro-electromechanical structure, including: forming a back plate having at least one through hole; forming an induction film, wherein the induction film comprises a motion area, a non-motion area and a beam structure connecting the motion area and the non-motion area, and the motion area and the back plate form a variable capacitor; forming at least one connecting column, wherein one end of each connecting column is fixedly connected with the motion area of the induction film; and forming at least one movable structure, wherein each movable structure is respectively positioned in the corresponding through hole to be separated from the back plate, each movable structure is fixedly connected with the other end of the corresponding connecting column, and the orthographic projection of the movable structure on the sensing film is overlapped with part of the non-moving area.

Optionally, the connecting column is adjacent to and not in contact with the beam structure.

Optionally, the beam structure comprises a bent beam.

Optionally, the method further includes forming a first sacrificial layer on the substrate, wherein the step of forming the sensing film includes: forming a first conductive layer on the first sacrificial layer; and etching the first conductive layer to form a groove so as to divide the first conductive layer into the motion area and the non-motion area and to form the beam structure.

Optionally, the method further comprises: forming a second sacrificial layer on the first conductive layer; and etching the second sacrificial layer to form a connecting hole, wherein the step of forming the back plate comprises forming an insulating layer which covers the second sacrificial layer and is filled in the connecting hole, and the insulating layer filled in the connecting hole is in contact with the sensing film to be used as the connecting column.

Optionally, the step of forming the back plate further comprises: forming a second conductive layer on the insulating layer; and removing part of the insulating layer and part of the second conductive layer to form an isolation groove, wherein the insulating layer and the second conductive layer surrounded by the isolation groove are used as movable structures.

Optionally, the method further comprises: etching the second sacrificial layer to form a conductive hole, wherein the position of the conductive hole corresponds to the non-motion area; filling a spacer in the conductive hole; etching the insulating layer and the isolating part to form a conductive channel; and forming a conductive part in the conductive channel, the conductive part being in contact with the non-motion region, wherein the conductive hole and the connection hole are formed in the same step, the insulating layer is further filled in the conductive hole, and the insulating layer filled in the conductive hole serves as the isolation part.

Optionally, the method further comprises: forming at least one recess on the surface of the second sacrificial layer; and forming an anti-sticking portion in each of the recesses, wherein the insulating layer is further filled in the recess, and the insulating layer filled in the recess serves as the anti-sticking portion.

Optionally, the method further comprises: forming a back cavity in the substrate, the back cavity corresponding to the motion zone; and removing the first sacrificial layer and the second sacrificial layer corresponding to the back cavity, wherein the first sacrificial layer which is not removed serves as a first supporting part, and the second sacrificial layer which is not removed serves as a second supporting part.

According to the MEMS sensor and the MEMS structure thereof provided by the embodiment of the invention, the sensing film is connected with the movable structure through the connecting column, and the movable structure can pass through the through hole on the backboard, when the sensing film moves towards the backboard, the movable structure cannot be blocked by the backboard to influence the displacement of the sensing film, when the sensing film moves back to the backboard, the maximum displacement of the sensing film is limited by the movable structure, because the orthographic projection of the movable structure on the sensing film is superposed with a part of non-movement area of the sensing film, when the sensing film moves back to a certain position, the movable structure can be blocked by the part of non-movement area of the sensing film, so that the sensing film is prevented from further moving back to the backboard, and the mechanical impact resistance of the MEMS sensor is improved.

Because the deformation amount of the motion area of the sensing film is the largest at the position close to the beam structure, the movable structure is arranged near the beam structure by enabling the connecting column to be adjacent to the beam structure of the sensing film, and the mechanical impact resistance of the MEMS sensor is further improved.

By corresponding the conductive layer in the back plate to the motion area of the sensing film, parasitic capacitance is reduced in the micro-electromechanical structure.

The connecting column and the movable structure are arranged into an integral structure, so that the forming steps of the connecting column and the movable structure are simplified, and the firmness degree between the connecting column and the movable structure is increased.

The anti-sticking part is arranged on the surface, facing the sensing film, of the insulating layer of the back plate, so that the sensing film is prevented from being stuck to the back plate.

Through setting up the insulating layer of antiseized portion and backplate into an organic whole structure to simplified the formation step of antiseized portion, and increased the firm degree between antiseized portion and the backplate.

By having the conductive holes and the connection holes formed in the same step, the process steps are further simplified.

By uniformly distributing the movable structures on the edge of the second conducting layer, after the movable structures are blocked by partial non-moving areas of the sensing film, the uniformly distributed movable structures can increase the stress uniformity of the sensing film, and the service life of the sensing film is prolonged.

Therefore, the micro-electromechanical structure provided by the invention has the advantages of small size, low cost, high sensitivity and strong mechanical impact resistance, thereby achieving the purposes of improving the reliability of the MEMS sensor and reducing the cost while ensuring the performance of the MEMS sensor so as to be used for mass production.

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 illustrates a top view of a micro-electromechanical structure of an embodiment of the present invention.

Fig. 2 shows an enlarged schematic view of a part of the structure in fig. 1.

Fig. 3 shows a cross-sectional view along line AA in fig. 1.

Fig. 4 shows a schematic diagram of the operating principle of the micro-electromechanical structure of the embodiment of the invention.

Fig. 5-12 are schematic diagrams of structures in some steps of a micro-electromechanical structure being fabricated according to an embodiment of the present invention.

Fig. 13 shows a schematic structural diagram of a MEMS sensor according to an 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 top view of a micro-electromechanical structure according to an embodiment of the present invention, fig. 2 shows an enlarged schematic view of a part of the structure in fig. 1, and fig. 3 shows a cross-sectional view along line AA in fig. 1.

As shown in fig. 1 to 3, the micro-electromechanical structure according to the embodiment of the present invention includes: a back plate 100, a sensing film 200, a connecting column 300 and a movable structure 400. The back plate 100 has a through hole 101. The sensing film 200 includes: a motion zone 210, a non-motion zone 220, and a beam structure 230. The sensing film 200 has a groove 202, and a moving area 210 and a non-moving area 220 are separated by the groove 202. The beam structure 230 is used to connect the motion zone 210 with the non-motion zone 220. The motion region 210 of the sensing film 200 and the backplate 100 form a variable capacitor. One end of the connection column 300 is fixedly connected with the moving region 210 of the sensing film 200, and the other end is connected with the movable structure 400. The movable structures 400 are located in the through holes 101 and separated from the back plate 100, i.e. the outer circumferential edges 401 of the movable structures 400 are not in contact with the side walls of the through holes 101, it can be seen from fig. 2 that the outer circumferential edges 401 of the movable structures 400 and the side walls of the through holes 101 constitute isolation grooves, and the distance d from the outer circumferential edges 401 of the movable structures 400 to the side walls of the corresponding through holes 101 is 0.5 to 1.5 micrometers. Wherein, the orthographic projection of the movable structure 400 on the sensing film 200 is overlapped with the non-motion area 210 of part of the sensing film 200, the orthographic projection area of the movable structure 400 in the thickness direction is 20 to 30 square microns, and the orthographic projection shape of the movable structure 400 in the thickness direction comprises at least one of a polygon, a circle, an ellipse and a fan.

In some embodiments, the connecting column 300 is adjacent to and does not contact the beam structure 230 of the sensing film 200, the beam structure 230 is a bent beam, and the beam structure 230 can also be a cantilever beam. The number of the beam structures 230, the through holes 101, the connecting columns 300 and the movable structures 400 corresponds, for example, to 4. The connecting column 300 and the movable structure 400 are an integral structure. The backplate 100 also has a plurality of sound holes 102, the sound holes 102 corresponding to the motion zones 210 of the sensing diaphragm 200. The sensing diaphragm 200 also has a vent hole 201 located in the motion zone 220. However, the embodiments of the present invention are not limited thereto, and those skilled in the art may make other arrangements of the number of the beam structures 230, the through holes 101, the sound holes 102, the connecting columns 300, the movable structures 400, and the air release holes 201 as needed.

In some specific embodiments, the back plate 100 is composed of an insulating layer 110 and a conductive layer 120 (second conductive layer) connected, the insulating layer 110 is closer to the sensing film 200 than the conductive layer 120, and the position of the conductive layer 120 corresponds to the vibration region 210 of the sensing film 200. A plurality of movable structures 400 are uniformly distributed at the edge of the conductive layer 120. Wherein, the conductive layer 120 is circular (the orthographic projection of the conductive layer 120 in the thickness direction is circular), and the ratio of the length L of the movable structure 400 to the radius of the conductive layer 120 along the radial direction of the conductive layer 120 is 1:3 to 1:5, as shown in fig. 1. For example, the length L of the movable structure 400 is 50 micrometers, the radius of the conductive layer 120 is 200 micrometers, and the ratio of the length L of the movable structure 400 to the radius of the conductive layer 120 is 1: 4.

The orthographic projection area of the back plate 100 in the thickness direction is 6000 to 15000 times of the orthographic projection area of each movable structure 400 in the thickness direction, so that the influence of the movable structures 400 on the effective capacitance area of the micro-electromechanical structure is small, for example, in the case that the orthographic projection area of the movable structures 400 in the thickness direction is 20 to 30 square micrometers, the orthographic projection area of the back plate 100 in the thickness direction can be set to be 0.2 to 0.3 square millimeters, wherein the orthographic projection of the insulating layer 110 in the thickness direction is rectangular, the area is 0.2 to 0.3 square millimeters, the orthographic projection of the conductive layer 120 in the thickness direction is circular, and the area is 0.05 to 0.1 square millimeters. One skilled in the art can also adjust the relative dimensional ratio between the backplate 100 and the movable structure 400 as desired.

With further reference to fig. 1 to 3, the micro-electromechanical structure according to the embodiment of the present invention further includes: the substrate 500, the first support part 600, the second support part 700, the anti-adhesion structure 800, the first pad 910, and the second pad 920.

In this embodiment, the substrate 500 has a back cavity 501. The first support part 600 is located on the substrate 500 and surrounds the back cavity 501. The sensing film 200 is disposed on the first supporting portion 600, and the non-moving region 220 of the sensing film 200 is fixedly connected to the first supporting portion 600. The second supporting portion 700 is located between the sensing film 200 and the back plate 100, the non-moving area 220 of the sensing film 200 is fixedly connected to the second supporting portion 700, the second supporting portion 700 surrounds the back cavity 501 and is located corresponding to the first supporting portion 600, wherein the insulating layer 110 of the back plate 100 is located on the second supporting portion 700. In some other embodiments, the positions of the back plate 100 and the sensing film 200 can be reversed.

The anti-sticking portion 800 is located on the surface of the insulating layer 110 of the back sheet 100 facing the sensing film 200. In some preferred embodiments, the anti-sticking portion 800 is an integral structure with the insulating layer 110 of the back sheet 100.

The first bonding pad 910 is located on the insulating layer 110 of the backplate 100 and electrically connected to the conductive layer 120 of the backplate 100, and the second bonding pad 920 is located on the insulating layer 110 of the backplate 100 and electrically connected to the non-motion region 220 of the sensing film 200 through a conductive via.

In this embodiment, the insulating layer 110 of the backplate 100 is made of silicon nitride, the conductive layer 120 is made of polysilicon, the sensing film 200 is made of polysilicon, the connecting post 300 and the anti-sticking portion 800 are made of silicon nitride, the movable structure 400 and the backplate 100 are formed in the same process, the structural layers and materials of the movable structure are the same as those of the backplate 100, the substrate 500 is a silicon substrate, and the first supporting portion 600 and the second supporting portion 700 are made of silicon oxide. However, the embodiments of the present invention are not limited thereto, and those skilled in the art can make other arrangements of the materials in the micro-electromechanical structure as needed.

Fig. 4 shows a schematic diagram of the operating principle of the micro-electromechanical structure of the embodiment of the invention.

As shown in fig. 4, when the moving region 210 of the sensing film 200 moves in a direction away from the backplate 100, the connecting column 300 and the movable structure 400 are driven to move together, and when the deformation amount of the sensing film 200 exceeds the thickness of the second supporting portion 700, the movable structure 400 is blocked by a part of the non-moving region 220 of the sensing film 200, so that the sensing film 200 is prevented from further moving away from the backplate 100, and the sensing film 200 is prevented from failing due to an excessive deformation amount.

Fig. 5-12 are schematic diagrams of structures in some steps of a micro-electromechanical structure being fabricated according to an embodiment of the present invention. The method for manufacturing the micro-electromechanical structure according to the embodiment of the invention will be described in detail with reference to fig. 5 to 12.

As shown in fig. 5 to 7, a first sacrificial layer 610 is formed on the substrate 500, a first conductive layer is formed on the first sacrificial layer 610, and the first conductive layer is etched to form the sensing film 200 having the air-escape hole 201 and the groove 202, wherein fig. 5 is a top view of this step, fig. 6 is a partially enlarged view of a dotted frame in fig. 5, and fig. 7 is a cross-sectional view along line AA in fig. 5.

In the present embodiment, the groove 202 separates the sensing film 200 into the motion region 210 and the non-motion region 220 to expose the beam structure 230, the first sacrificial layer 610 through the air release hole 201 and the groove 202, and in the subsequent step, the first sacrificial layer 610 forms the first supporting portion 600.

Further, a second sacrificial layer 710 is formed on the sensing film 200, and the second sacrificial layer 710 is etched to form a connection hole 711 and a conductive hole 713, as shown in fig. 8 and 9, wherein fig. 8 is a top view of this step, and fig. 9 is a cross-sectional view along line AA in fig. 8.

In the present embodiment, the sensing film 200 is exposed through the connection hole 711 and the conductive hole 713, the connection hole 711 corresponding to the motion region of the sensing film 200, and the conductive hole 713 corresponding to the non-motion region of the sensing film 200. The second sacrificial layer 710 covers the air-escape holes and the grooves of the sensing film 200, and the second sacrificial layer 710 forms the second supporting portion 700 in the subsequent steps.

In some preferred embodiments, the second sacrificial layer 710 is further etched to form recesses 712, the depth of the recesses 712 is less than the thickness of the second sacrificial layer 710, the recesses 712 are used to define the locations of the anti-sticking structures, and the number of the recesses 712 corresponds to the moving area of the sensing film 200, which can be determined according to the needs of those skilled in the art.

Further, an insulating layer 111 covering the second sacrificial layer 710 and filling in the connection hole 711, the recess 712, and the conductive hole 713 is formed as shown in fig. 10. With further reference to fig. 8 and 11, the insulating layer 111 filled in the connection hole 711 is in contact with the sensing film 200 as the connection post 300, the insulating layer 111 filled in the recess 712 is as the anti-sticking portion 800, the insulating layer 111 on the surface of the second sacrificial layer 710 is as the insulating layer 110 of the back plate 100, and the insulating layer 111 filled in the conductive hole 713 is as the spacer. Further, a second conductive layer 120 is formed on the insulating layer 110.

Further, a part of the insulating layer 110 and a part of the second conductive layer 120 are removed to form an isolation trench (via 101), and the insulating layer 110 and the second conductive layer 120 surrounded by the isolation trench serve as a movable structure 400, as shown in fig. 12.

Further, etching the insulating layer 110 and the isolation portion in the conductive hole 713 forms a conductive channel, forming a conductive portion in the conductive channel, the conductive portion contacting the non-motion region of the sensing film 200, and then forming a first pad 910 and a second pad 920 on the surface of the insulating layer 110 as shown in fig. 1, wherein the second pad 920 is electrically connected to the non-motion region of the sensing film 200 through the conductive portion.

Further, the substrate 500 is etched to form a back cavity 501 corresponding to the motion region of the sensing film 200, and then the first sacrificial layer and the second sacrificial layer corresponding to the back cavity 501 are removed, the first sacrificial layer that is not removed serves as the first support 600, and the second sacrificial layer that is not removed serves as the second support 700.

Fig. 13 shows a schematic structural diagram of a MEMS sensor according to an embodiment of the invention.

As shown in fig. 13, the MEMS sensor includes: the micro-electromechanical structure 10, the signal processing chip 20, the substrate 30 and the housing 40. The substrate 30 and the housing 40 serve as a package structure of the device. The micro-electromechanical structure 10 according to the embodiment of the present invention can refer to the descriptions of fig. 1 to fig. 12, and details are not repeated here, where the micro-electromechanical structure according to the embodiment of the present invention may be a microphone chip, or may be a pressure sensor chip, a bone conduction chip, or other MEMS sensor chips. The present invention does not limit the type of sensor chip. The signal processing chip 20 is, for example, an ASIC chip, and the substrate 30 is, for example, a lead frame or a PCB circuit board.

According to the MEMS sensor and the MEMS structure thereof provided by the embodiment of the invention, the sensing film is connected with the movable structure through the connecting column, and the movable structure can pass through the through hole on the backboard, when the sensing film moves towards the backboard, the movable structure cannot be blocked by the backboard to influence the displacement of the sensing film, when the sensing film moves back to the backboard, the maximum displacement of the sensing film is limited by the movable structure, because the orthographic projection of the movable structure on the sensing film is superposed with a part of non-movement area of the sensing film, when the sensing film moves back to a certain position, the movable structure can be blocked by the part of non-movement area of the sensing film, so that the sensing film is prevented from further moving back to the backboard, and the mechanical impact resistance of the MEMS sensor is improved.

Because the deformation amount of the motion area of the sensing film is the largest at the position close to the beam structure, the movable structure is arranged near the beam structure by enabling the connecting column to be adjacent to the beam structure of the sensing film, and the mechanical impact resistance of the MEMS sensor is further improved.

By corresponding the conductive layer in the back plate to the motion area of the sensing film, parasitic capacitance is reduced in the micro-electromechanical structure.

The connecting column and the movable structure are arranged into an integral structure, so that the forming steps of the connecting column and the movable structure are simplified, and the firmness degree between the connecting column and the movable structure is increased.

The anti-sticking part is arranged on the surface, facing the sensing film, of the insulating layer of the back plate, so that the sensing film is prevented from being stuck to the back plate.

Through setting up the insulating layer of antiseized portion and backplate into an organic whole structure to simplified the formation step of antiseized portion, and increased the firm degree between antiseized portion and the backplate.

By having the conductive holes and the connection holes formed in the same step, the process steps are further simplified.

By uniformly distributing the movable structures on the edge of the second conducting layer, after the movable structures are blocked by partial non-moving areas of the sensing film, the uniformly distributed movable structures can increase the stress uniformity of the sensing film, and the service life of the sensing film is prolonged.

Therefore, the micro-electromechanical structure provided by the invention has the advantages of small size, low cost, high sensitivity and strong mechanical impact resistance, thereby achieving the purposes of improving the reliability of the MEMS sensor and reducing the cost while ensuring the performance of the MEMS sensor so as to be used for mass production.

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.