CN111115557B

CN111115557B - MEMS membrane and MEMS sensor chip

Info

Publication number: CN111115557B
Application number: CN201911411308.4A
Authority: CN
Inventors: 何宪龙
Original assignee: Gettop Acoustic Co Ltd
Current assignee: Gettop Acoustic Co Ltd
Priority date: 2019-12-31
Filing date: 2019-12-31
Publication date: 2023-10-03
Anticipated expiration: 2039-12-31
Also published as: CN111115557A

Abstract

The application provides an MEMS membrane and an MEMS sensor chip, wherein the MEMS membrane comprises a sensing part and a peripheral part surrounding the periphery of the sensing part, a plurality of outer grooves and two inner grooves are arranged between the peripheral part and the sensing part, the outer grooves are annularly arranged at the inner edge of the peripheral part, the two inner grooves are annularly arranged at the outer edge of the sensing part, the tail ends of the inner grooves extend towards the inner side, and the two inner grooves are symmetrical with respect to the center of the sensing part.

Description

MEMS membrane and MEMS sensor chip

Technical Field

The application relates to the technical field of Micro Electro-mechanical systems (MEMS), in particular to an MEMS membrane and an MEMS sensor chip.

Background

The micro-electromechanical sensor is widely applied to various acoustic receivers or force sensors, has the characteristics of small volume, low power consumption, high sensitivity and the like, and becomes a design target, and according to the result of theoretical simulation, the influence of residual stress has a great influence on the mechanical sensitivity of a vibrating film in the acoustic sensor.

The mems device generally includes a capacitive sensor structure with a sensing film and a back electrode, which form two parallel plate capacitive structures for sensing vibration or pressure changes. The material characteristics of the sensing film determine the sensitivity performance of the device, but thermal residual stress generated during the semiconductor processing process is unavoidable. However, the existing process technology still cannot precisely control the film stress, and thus the sensitivity of the mems device is low or the sensitivity varies.

Therefore, how to provide a sensing film with good stress release effect and high mechanical sensitivity is a problem to be solved in the industry.

Disclosure of Invention

In view of this, the present application proposes a MEMS membrane with high mechanical sensitivity.

The application also provides an MEMS sensor chip applying the MEMS membrane.

The application provides an MEMS membrane which comprises a sensing part and a peripheral part surrounding the periphery of the sensing part, wherein a plurality of outer grooves and two inner grooves are arranged between the peripheral part and the sensing part, the outer grooves are annularly arranged at the inner edge of the peripheral part, the two inner grooves are annularly arranged at the outer edge of the sensing part, the tail ends of the inner grooves extend towards the inner side, and the two inner grooves are symmetrical with respect to the center of the sensing part.

Preferably, the two inner grooves are symmetrical with respect to at least one center line direction of the sensing part.

Preferably, the sensing portion is circular, the two inner grooves extend along a circumferential direction of the sensing portion, the plurality of outer grooves extend along another circumferential direction, and the other circumferential direction is concentric with the circumferential direction of the sensing portion.

Preferably, the number of outer tanks is greater than the number of inner tanks.

Preferably, the end of the outer groove is provided with a first bending part, and the first bending part extends towards the outer side of the MEMS membrane, or the first bending part extends towards the inner side of the MEMS membrane.

Preferably, the first bending part comprises an arc-shaped section, a straight-line section or a combination of the arc-shaped section and the straight-line section.

Preferably, the first bending part is U-shaped.

Preferably, the end of the inner groove is provided with a second bending part, and the second bending part extends towards the outer side of the MEMS membrane, or the second bending part extends towards the inner side of the MEMS membrane.

Preferably, the second bending part comprises an arc-shaped section, a straight-line section or a combination of the arc-shaped section and the straight-line section.

Preferably, the second bending part is U-shaped.

Preferably, the end of the first bending part is an arc-shaped end; or the tail end of the second bending part is an arc-shaped tail end.

Preferably, a first connecting arm is formed between two adjacent outer grooves, a second connecting arm is formed between two adjacent inner grooves, an annular connecting arm is formed between the outer grooves and the two inner grooves, the annular connecting arm is connected to the peripheral portion through the first connecting arm, is connected to the sensing portion through the second connecting arm, and the first connecting arm and the second connecting arm are staggered in the circumferential direction of the annular connecting arm.

Preferably, the sensing portion moves relative to the peripheral portion in a direction perpendicular to the diaphragm when the MEMS diaphragm is subjected to less than a predetermined pressure, and a line connecting the two second connection arms divides an outer edge of the sensing portion into two parts, and a gap formed between an outer edge of each part and an inner edge of the peripheral portion is uniform along the outer edge of each part.

Preferably, the sensing portion moves in an arch-shaped manner relative to the peripheral portion when the MEMS diaphragm is subjected to a pressure greater than another predetermined pressure, and the connecting line of the two second connecting arms divides the outer edge of the sensing portion into two parts, and a gap formed between the outer edge of each part and the inner edge of the peripheral portion gradually increases from the two second connecting arms to the middle along the outer edge of each part.

Preferably, the circumferential width of the first connecting arm is firstly reduced and then increased along the radial outward direction of the MEMS membrane; and/or the circumferential width of the second connecting arm is firstly reduced and then increased along the radial inward direction of the MEMS membrane.

Preferably, the circumferential width of each first connecting arm is the same, and the circumferential width of each second connecting arm is the same.

In some embodiments, the annular connecting arms have a uniform radial width.

In some embodiments, the annular connecting arms have a width at an end proximate to the inner and/or outer slots that is greater than a width at an end distal to the inner slot.

In some embodiments, the radial width of the annular connecting arm adjacent to the second connecting arm is greater than the radial width of other portions of the annular connecting arm.

The application provides a MEMS sensor chip, which comprises the MEMS membrane.

In summary, the present application provides a MEMS membrane, in which a plurality of outer grooves and two inner grooves are disposed between a sensing portion and a peripheral portion, wherein the ends of the outer grooves extend toward the outside, and the ends of the inner grooves extend toward the inside. Annular connecting arms are formed between the outer grooves and the inner grooves, first connecting arms are formed between two adjacent outer grooves, and second connecting arms are formed between two adjacent inner grooves. The outer grooves are annularly arranged at the inner edge of the peripheral part, the two inner grooves are annularly arranged at the outer edge of the sensing part, and the two inner grooves are symmetrically arranged about the center of the sensing part, so that the sensitivity of the diaphragm is improved; when the MEMS membrane is subjected to pressure greater than a preset pressure, the sensing part moves in an arch mode relative to the peripheral part, so that the stress is released in time, external mechanical force such as larger pressure can be released, and the membrane is not resisted with the external mechanical force, so that the mechanical reliability of the MEMS membrane and the MEMS sensor chip is improved. The first connecting arm and the second connecting arm are staggered in the circumferential direction, so that stress concentration can be reduced, the tail end of the outer groove and the tail end of the inner groove which extend in a bending mode enable mechanical sensitivity of the sensing part to be improved, and reliability of the diaphragm is improved.

Drawings

FIG. 1 is a schematic diagram of a MEMS diaphragm of the present application.

FIG. 2 is a schematic diagram of the MEMS membrane of the present application moving in an arcuate manner.

Detailed Description

Before the embodiments are explained in detail, it is to be understood that the application is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The application is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of the terms "comprising," "including," "having," and the like are intended to encompass the items listed thereafter and equivalents thereof as well as additional items. In particular, when "a certain element" is described, the present application is not limited to the number of the element as one, but may include a plurality of the elements.

Fig. 1 is a schematic structural diagram of a MEMS membrane according to an embodiment of the application. The MEMS diaphragm 10 is used in microelectromechanical devices, such as microelectromechanical sensors, microelectromechanical condenser microphones. The MEMS diaphragm 10 includes a sensing portion 12 and a peripheral portion 14, wherein the sensing portion 12 is located inside the MEMS diaphragm 10, and the peripheral portion 14 is located outside the MEMS diaphragm 10 and surrounds the periphery of the sensing portion 12. The sensing part 12 is used for sensing external pressure, such as sensing sound pressure, and when the sensing part 12 is applied to the micro-electromechanical capacitive microphone, the sensing part 12 moves relative to the back plate under the action of the sound pressure, so that the capacitance between the sensing part and the back plate changes to generate corresponding electric signals. The peripheral portion 14 is used to connect and support the sensing portion 12.

The area between the sensing portion 12 and the peripheral portion 14 is provided with a plurality of outer grooves 16 and two inner grooves 18, the outer grooves 16 are annular and are arranged at intervals on the inner edge of the peripheral portion 14, the outer grooves 16 jointly define an outer circle, the inner grooves 18 are annular and are arranged at intervals on the outer edge of the sensing portion 12, and the inner grooves 18 jointly define an inner circle. In this embodiment, the outer circle and the inner circle are concentric. An annular connecting arm 20 is formed between the plurality of outer grooves 16 and the two inner grooves 18, and the peripheral portion 14 is connected with the sensing portion 12 through the annular connecting arm 20. The outer groove 16, the inner groove 18 and the annular connecting arm 20 separate the peripheral portion 14 from the sensing portion 12, and avoid transmitting force generated by elastic deformation to the sensing region when the peripheral portion 14 is deformed, so as to improve stability of the sensing portion 12 and improve stability of linear output of the MEMS diaphragm 10. The width of the annular connecting arms 20 may be designed to distribute stress and reduce stress concentrations on the MEMS membrane 10, depending on the actual design requirements.

In some embodiments, the annular connecting arms 20 have a uniform radial width, i.e., the plurality of outer grooves 16 each extend in the outer circumferential direction, and the two inner grooves 18 each extend in the inner circumferential direction.

In other embodiments, the annular connecting arms 20 may also have varying radial widths, e.g., increasing their radial width in areas of greater stress to increase their rigidity, e.g., the annular connecting arms 20 have a greater width at the ends near the inner and/or outer slots 18, 16 than at the ends away from the ends.

The ends of the outer grooves 16 are provided with first bending portions, which may be arranged to extend towards the outer side of the membrane or towards the inner side of the membrane at the same time. The ends of both inner grooves 18 extend towards the inside of the diaphragm, and both inner grooves 18 are symmetrical about the center of the sensing portion 12. For example, the inner grooves 18 are symmetrical about at least one radial direction of the sensing portion 12, and in the illustrated embodiment, the inner grooves 18 are symmetrical about both radial directions L1 and L2 of the inner circle. The arrangement and design are such that when the MEMS diaphragm 10 is subjected to less than a predetermined pressure, the sensing portion 12 can perform an approximately piston-like movement, i.e., straight up and down, with respect to the peripheral portion 14 in a direction perpendicular to the MEMS diaphragm 10; when MEMS diaphragm 10 is subjected to a pressure greater than another predetermined pressure, and particularly a greater pressure, sensing portion 12 is able to move in an arcuate manner relative to peripheral portion 14, releasing the pressure in time.

In this embodiment, the sensing portion 12, the annular connecting arm 20 and the peripheral portion 14 may be integrally formed. The MEMS membrane 10 may be made of carbon-based polymer, silicon nitride, polysilicon, silicon dioxide, silicon carbide, arsenide, carbon, germanium, gallium, titanium, gold, iron, copper, chromium, tungsten, aluminum, platinum, nickel, tantalum, or alloys thereof. The MEMS membrane 10 may be square, circular, or other shape, in this embodiment illustrated as circular. That is, the peripheral portion 14 is also circular.

It should be noted that the outer side and the inner side are with respect to the central portion of the entire MEMS membrane 10, the outer side is a direction away from the central portion, and the inner side is a direction toward the central portion. Since the outer grooves 16 together define an outer circle, the inner grooves 18 together define an inner circle, the outer circle and the inner circle are concentric, and the peripheral portion 14 and the sensing portion 12 are circular, the center is also the center of the peripheral portion 14 and the sensing portion 12, which can be said to be the center of the MEMS membrane 10, and the centers are the same center. The center of MEMS diaphragm 10 may also be understood as the center.

The two inner grooves 18 are symmetrical about the center of the sensing portion 12, that is, the two inner grooves 18 are symmetrical about the center of the sensing portion 12.

In the embodiment shown, the two inner tanks 18 are symmetrical in the diameter direction of the inner circle, i.e. the circumferential lengths of the two inner tanks 18 are identical. The design is such that when the MEMS diaphragm 10 is subjected to a pressure greater than the other predetermined pressure, i.e. a larger impact, the sensing portion 12 moves in an arched manner relative to the peripheral portion 14, i.e. the portions of the sensing portion 12 respectively surrounded by the two inner grooves 18 simultaneously tilt up relative to the peripheral portion 14, thereby forming a leakage path to release the larger impact.

The number of the outer grooves 16 may be plural, preferably four or more, and more preferably eight, according to specific design requirements and actual use. In the embodiment shown in fig. 1-2, the number of outer slots 16 is set to eight.

The eight outer grooves 16 are arranged at regular intervals in the circumferential direction, and each outer groove 16 is uniform in shape and structure. The two inner tanks 18 are circumferentially uniformly spaced apart, and each inner tank 18 is identical in shape and structure. In some embodiments, the number of outer slots 16 is greater than the number of inner slots 18. Only the shape and structure of one outer tank 16 and one inner tank 18 will be described below.

The outer groove 16 has a first bending portion 22 at its end, and the first bending portion 22 may extend outward or inward. The first bending portion 22 may include an arcuate segment, a straight segment, or a combination of an arcuate segment and a straight segment. That is, the distal end of the outer groove 16 may extend in a curved shape toward the outside or the inside, may extend in a straight shape toward the outside or the inside, may extend in a curved shape and then a straight shape, or may extend in a curved shape and then extend toward the outside or the inside.

In the illustrated embodiment, each outer slot 16 is provided with a first bend 22 at both ends. In order to reduce stress concentration, the end of the first bending portion 22 may be arc-shaped.

The inner tank 18 is provided at its distal end with a second bent portion 24, the second bent portion 24 extending inward. The second bending portion 24 may also include an arcuate segment, a straight segment, or a combination of arcuate and straight segments. That is, the end of the inner tank 18 may extend in a curved shape toward the inside, may extend in a straight shape toward the inside, may extend in a curved shape and then in a straight shape, or may extend in a curved shape and then in the inside.

In the illustrated embodiment, each inner groove 18 is provided with a second bend 24 at both ends. In order to reduce stress concentration, the end of the second bending portion 24 may be arc-shaped.

It should be understood that in the present application, the first bent portions 22 of all the outer grooves 16 are extended simultaneously toward the outside or extended simultaneously toward the inside. The second bending portions 24 of all the inner tanks 18 extend toward the inner side at the same time. In some embodiments, the first bending portion 22 of the partial outer groove 16 may also extend toward the outside, and the first bending portion 22 of the partial outer groove 16 extends toward the inside.

In the embodiment shown in fig. 1-2, the first bend 22 at the end of the outer channel 16 is U-shaped. More specifically, the first bending portion 22 at the end of the outer groove 16 extends toward the outside, and the first bending portion 22 is an arc-shaped segment extending toward the outside in a half bracket shape. For an outer groove 16, the two first bends 22 at the ends of the outer groove 16 can be considered as forming a complete bracket. For two adjacent outer grooves 16, the two adjacent first bending portions 22 of the two adjacent outer grooves 16 can be regarded as two opposite semicircular brackets. The second bend 24 at the end of the inner tank 18 is U-shaped. Specifically, the second bending portion 24 at the end of the inner groove 18 extends toward the inner side, and the second bending portion 24 is also an arc-shaped segment, and the arc-shaped segment extends toward the inner side in a half bracket shape. For an inner tank 18, the two second bends 24 at the ends of the inner tank 18 can be considered as forming a complete bracket. For two adjacent inner grooves 18, the adjacent second bending portions 24 of the two adjacent inner grooves 18 may be regarded as two opposite semicircular brackets.

A first connecting arm 26 is formed between two adjacent outer slots 16, and a second connecting arm 28 is formed between two adjacent inner slots 18. In the illustrated embodiment, each first connecting arm 26 is identical in structure and shape and identical in circumferential width; each of the second connecting arms 28 is identical in structure and shape, and also identical in circumferential width, and the two second connecting arms 28 are symmetrical about the inner diameter L2. The first connecting arm 26 extends outward from the outer edge of the annular connecting arm 20, the second connecting arm 28 extends inward from the inner edge of the annular connecting arm 20, and the first connecting arm 26 and the second connecting arm 28 are offset from each other in the circumferential direction of the annular connecting arm 20. In the present embodiment, the two second connecting arms 28 respectively correspond to the central positions of the two circumferentially opposite outer slots 16.

Because the first bending portion 22 is an arc-shaped section extending outwards in a half-bracket shape, and the second bending portion 24 is an arc-shaped section extending inwards in a half-bracket shape, the circumferential width of the first connecting arm 26 is firstly reduced and then increased along the radial direction of the MEMS membrane 10; the circumferential width of the second connecting arm 28 decreases and then increases radially inward of the MEMS diaphragm 10.

The circumferential width of the first connecting arm 26 may be greater than, equal to, or less than the circumferential width of the second connecting arm 28, depending on the particular design requirements and actual use of the MEMS diaphragm 10. In the present embodiment, the circumferential widths of the first connecting arm 26 and the second connecting arm 28 are set to be the same.

Thus, the peripheral portion 14 is connected to the sensing portion 12 entirely by the first connecting arm 26, the annular connecting arm 20 and the second connecting arm 28.

When MEMS diaphragm 10 is subjected to less than the predetermined pressure, sensing portion 12 moves relative to peripheral portion 14 in a direction perpendicular to the diaphragm toward the direction of force. From another perspective, the connection of the two second connecting arms 28 divides the outer edge of the sensing portion 12 into two parts, and the gap formed between the outer edge of each part and the inner edge of the peripheral portion 14 is uniform along the outer edge of each part. The second connecting arm 28 moves vertically with the sensing portion 12, and the annular connecting arm 20 is connected between the first connecting arm 26 and the second connecting arm 28 in a buckling manner.

When MEMS diaphragm 10 is subjected to more than the other predetermined pressure, sensing portion 12 moves in an arcuate manner relative to peripheral portion 14 toward the direction of the force, as shown in fig. 2. From another perspective, the connection line of the two second connection arms 28 divides the outer edge of the sensing portion 12 into two parts, and the gap formed between the outer edge of each part and the inner edge of the peripheral portion 14 gradually increases from the two second connection arms 28 toward the middle along the outer edge of each part.

In summary, the present application provides a MEMS membrane, in which a plurality of outer grooves and two inner grooves are disposed between a sensing portion and a peripheral portion, wherein the ends of the outer grooves extend toward the outside, and the ends of the inner grooves extend toward the inside. Annular connecting arms are formed between the outer grooves and the inner grooves, first connecting arms are formed between two adjacent outer grooves, and second connecting arms are formed between two adjacent inner grooves. The outer grooves are annularly arranged at the inner edge of the peripheral part, the two inner grooves are annularly arranged at the outer edge of the sensing part, the two inner grooves are arranged to be symmetrical about the center of the sensing part, the sensitivity of the membrane is improved, when the MEMS membrane is subjected to high pressure, the sensing part can move in an arch mode relative to the peripheral part, the stress is released in time, external mechanical force such as high pressure can be released, the membrane is not resisted with the external mechanical force, and therefore the mechanical reliability of the MEMS membrane and the MEMS sensor chip is improved. The first connecting arm and the second connecting arm are staggered in the circumferential direction, so that stress concentration can be reduced, the tail end of the outer groove and the tail end of the inner groove which extend in a bending mode enable mechanical sensitivity of the sensing part to be improved, and reliability of the diaphragm is improved.

The concepts described herein may be embodied in other forms without departing from the spirit or characteristics thereof. The particular embodiments disclosed are illustrative and not restrictive. The scope of the application is, therefore, indicated by the appended claims rather than by the foregoing description. Any changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Claims

1. The MEMS membrane comprises a sensing part and a peripheral part surrounding the periphery of the sensing part, and is characterized in that a plurality of outer grooves and two inner grooves are arranged between the peripheral part and the sensing part, the number of the outer grooves is larger than that of the inner grooves, the outer grooves are annularly arranged at the inner edge of the peripheral part, the two inner grooves are annularly arranged at the outer edge of the sensing part, the tail ends of the inner grooves extend towards the inner side, the two inner grooves are symmetrical relative to the center of the sensing part, and when the MEMS membrane is subjected to less than a preset pressure, the sensing part performs piston type movement relative to the peripheral part along the direction perpendicular to the MEMS membrane in a plane shape; the sensing portion moves in an arcuate manner relative to the peripheral portion when the MEMS diaphragm is subjected to more than another predetermined pressure.

2. The MEMS diaphragm of claim 1, wherein the two inner grooves are symmetrical about at least a centerline direction of the sensing portion.

3. The MEMS diaphragm according to claim 1, wherein the outer groove has a first bend at a distal end thereof, the first bend extending toward an outside or an inside of the MEMS diaphragm, the first bend being U-shaped or the first bend having a rounded distal end.

4. The MEMS diaphragm according to claim 1, wherein the inner groove has a second bend at an end thereof, the second bend extending toward an outside or an inside of the MEMS diaphragm, the second bend being U-shaped or having an arcuate end at an end thereof.

5. The MEMS diaphragm of any of claims 1-4, wherein a first connecting arm is formed between two adjacent outer grooves, a second connecting arm is formed between two adjacent inner grooves, annular connecting arms are formed between the plurality of outer grooves and the two inner grooves, the annular connecting arms are connected to the peripheral portion through the first connecting arms, are connected to the sensing portion through the second connecting arms, and the first connecting arms and the second connecting arms are offset from each other in a circumferential direction of the annular connecting arms.

6. The MEMS diaphragm according to claim 5, wherein the sensing portion moves in an arcuate manner relative to the peripheral portion when the MEMS diaphragm is subjected to greater than a predetermined pressure, and wherein a line connecting the two second connecting arms divides an outer edge of the sensing portion into two portions, wherein a gap formed between an outer edge of each portion and an inner edge of the peripheral portion increases gradually from the two second connecting arms toward the middle along the outer edge of each portion.

7. The MEMS diaphragm of claim 6,

the circumferential width of the first connecting arm firstly decreases and then increases along the radial direction of the MEMS membrane; and/or

The circumferential width of the second connecting arm firstly decreases and then increases along the radial inward direction of the MEMS membrane.

8. The MEMS diaphragm of claim 7,

the annular connecting arms have a uniform radial width; or alternatively

The annular connecting arms have a greater width at the ends proximate to the inner and/or outer slots than at the ends distal thereto.

9. A MEMS sensor chip, characterized in that it comprises a MEMS diaphragm according to any of claims 1 to 8.