CN111115557A

CN111115557A - MEMS diaphragm and MEMS sensor chip

Info

Publication number: CN111115557A
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: 2020-05-08
Anticipated expiration: 2039-12-31
Also published as: CN111115557B

Abstract

The invention provides an MEMS diaphragm and an MEMS sensor chip, wherein the MEMS diaphragm 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 on the inner edge of the peripheral part, the two inner grooves are annularly arranged on 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 about the center of the sensing part.

Description

MEMS diaphragm and MEMS sensor chip

Technical Field

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

Background

The mems sensor is widely applied to various acoustic receivers or force sensors, and has characteristics of small size, low power consumption, high sensitivity, etc., which are the design targets, and it can be known from the theoretical simulation result that the influence of residual stress has a great influence on the mechanical sensitivity of the vibration film in the acoustic sensor.

The mems device includes a capacitive sensor structure, which is generally a sensing film coupled with a back electrode to form two parallel plate capacitor structures for sensing vibration or pressure change. The material properties of the sensing film determine the device sensitivity performance, but the thermal residual stress generated during the semiconductor processing process cannot be avoided. The existing process technology still cannot precisely control the film stress, and thus the sensitivity of the micro-electromechanical device is low or the sensitivity varies.

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

Disclosure of Invention

In view of this, the present invention provides a MEMS membrane with high mechanical sensitivity.

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

The invention provides an MEMS (micro-electromechanical system) 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 on the inner edge of the peripheral part, the two inner grooves are annularly arranged on 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 about 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, respectively, and the plurality of outer grooves extend along another circumferential direction, respectively, the another circumferential direction being concentric with the circumferential direction of the sensing portion.

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

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

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

Preferably, the first bent portion is U-shaped.

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

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

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

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

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

Preferably, the circumferential width of the first connecting arm decreases and then increases first along the radial direction of the MEMS diaphragm; and/or the circumferential width of the second connecting arm is first reduced and then increased along the radial direction of the MEMS diaphragm.

Preferably, each of the first connecting arms has the same circumferential width, and each of the second connecting arms has the same circumferential width.

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

In some embodiments, the width of the annular connecting arms is greater at the ends proximal to the inner and/or outer slots than at the ends distal thereto.

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

The invention provides an MEMS sensor chip which comprises the MEMS diaphragm.

In summary, the present invention provides a MEMS diaphragm, in which a plurality of outer grooves and two inner grooves are disposed between a sensing portion and an outer peripheral portion, ends of the outer grooves extend outward, and ends of the inner grooves extend inward. An annular connecting arm is formed between the outer grooves and the inner grooves, a first connecting arm is formed between every two adjacent outer grooves, and a second connecting arm is formed between every two adjacent inner grooves. The outer grooves are annularly arranged on the inner edge of the peripheral part, the two inner grooves are annularly arranged on the outer edge of the sensing part, and the two inner grooves are arranged to be symmetrical about the center of the sensing part, so that the sensitivity of the diaphragm is improved; when the MEMS diaphragm is subjected to pressure higher than a preset pressure, the sensing part moves in an arch mode relative to the peripheral part, stress is released in time, external mechanical force such as large pressure can be released, and the diaphragm is not resisted by the external mechanical force, so that the mechanical reliability of the MEMS diaphragm and the MEMS sensor chip is improved. The first connecting arm and the second connecting arm are arranged in a staggered mode in the circumferential direction, stress concentration can be reduced, the end of the outer groove extending in a bent mode and the end of the inner groove enable mechanical sensitivity of the sensing portion to be improved, and reliability of the diaphragm is improved.

Drawings

Fig. 1 is a schematic structural diagram of a MEMS membrane of the present invention.

FIG. 2 is a schematic structural view of the MEMS diaphragm of the present invention moving in an arcuate manner.

Detailed Description

Before the embodiments are described in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of components set forth in the following description or illustrated in the drawings. The invention is capable of embodiments in other forms of implementation. 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 "including," "comprising," "having," and the like, herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. In particular, when "a certain element" is described, the present invention is not limited to the number of the element being one, and may include a plurality of the elements.

Fig. 1 is a schematic structural diagram of a MEMS diaphragm according to an embodiment of the present invention. The MEMS membrane 10 is used in a micro-electromechanical device, for example, in a micro-electromechanical sensor, a micro-electromechanical condenser microphone. The MEMS membrane 10 includes a sensing portion 12 and a peripheral portion 14, wherein the sensing portion 12 is located on an inner side of the MEMS membrane 10, and the peripheral portion 14 is located on an outer side of the MEMS membrane 10 and surrounds the sensing portion 12. The sensing portion 12 is used for sensing an external pressure, for example, sensing a sound pressure, and when the micro-electromechanical condenser microphone is applied, the sensing portion 12 moves relative to the backplate under the action of the sound pressure, so that a capacitance between the sensing portion and the backplate changes to generate a corresponding electrical signal. The peripheral portion 14 is used to connect and support the sensing portion 12.

The region 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 plurality of outer grooves 16 are annular and are arranged at the inner edge of the peripheral portion 14 at intervals, the plurality of outer grooves 16 jointly define an outer circle, the two inner grooves 18 are annular and are arranged at the outer edge of the sensing portion 12 at intervals, and the two inner grooves 18 jointly define an inner circle. In this embodiment, the outer circle and the inner circle are concentric. The outer slots 16 and the two inner slots 18 form an annular connecting arm 20 therebetween, and the peripheral portion 14 is connected to 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, so as to prevent the force generated by elastic deformation from being transmitted to the sensing region when the peripheral portion 14 is deformed, thereby improving the stability of the sensing portion 12 and the stability of the linear output of the MEMS diaphragm 10. The width of the annular connecting arm 20 may be determined according to actual design requirements for distributing stress and reducing stress concentration on the MEMS membrane 10.

In some embodiments, the annular connecting arm 20 has a uniform radial width, i.e., the outer slots 16 each extend in an outer circumferential direction and the two inner slots 18 each extend in an inner circumferential direction.

In other embodiments, the annular connecting arms 20 may also have varying radial widths, for example, increasing their radial width in areas of greater stress to increase their rigidity, for example, the annular connecting arms 20 may have a greater width near the ends of the inner and/or

outer slots

18, 16 than at the ends remote therefrom.

The end of the outer grooves 16 is provided with a first bending part, which may be arranged to extend towards the outside of the membrane or towards the inside of the membrane. The ends of both inner grooves 18 extend towards the inner side of the diaphragm, and the two inner grooves 18 are symmetrical about the center of the sensing part 12. For example, the two inner grooves 18 are symmetrical about at least one diameter direction of the sensing section 12, and in the illustrated embodiment, the two inner grooves 18 are symmetrical about both diameter directions L1 and L2 of the inner circle. The arrangement is such that when the MEMS membrane 10 is subjected to a pressure less than a predetermined pressure, the sensing portion 12 can perform a quasi-piston-like motion, i.e. a straight up and down motion, in a plane shape with respect to the peripheral portion 14 along a direction perpendicular to the MEMS membrane 10; when the MEMS membrane 10 is subjected to more than another predetermined pressure, in particular a larger pressure, the sensing portion 12 is able to move in an arcuate manner with respect to the 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 can be integrally formed. The MEMS membrane 10 may be made of carbon-based polymer, silicon nitride, polysilicon, silicon dioxide, silicon carbide, arsenide, carbon, and metals such as 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 shapes, and in this embodiment, a circle is illustrated. That is, the peripheral portion 14 is also circular.

It should be noted that the outer side and the inner side are relative 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. In this embodiment, the outer slots 16 together define an outer circle, the two inner slots 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 both circular, so that the center of the circle is also the center of the peripheral portion 14 and the sensing portion 12, or the center of the circle of the MEMS membrane 10, and the centers of the circles are the same. The center of the MEMS membrane 10 can also be understood as the center of the circle.

The two inner grooves 18 are symmetrical with respect to the center of the sensing part 12, that is, the two inner grooves 18 are symmetrical with respect to the center of the sensing part 12.

In the embodiment shown, the two inner grooves 18 are symmetrical in the diametrical direction of the inner circle, i.e. the circumferential lengths of the two inner grooves 18 are the same. The design is such that when the MEMS membrane 10 is subjected to a pressure higher than the other predetermined pressure, i.e. a larger impact, the sensing portion 12 moves in an arch manner relative to the outer peripheral portion 14, i.e. the sensing portion 12 portion enclosed by the two inner grooves 18 is tilted upward relative to the outer peripheral portion 14 at the same time, so as to form a leakage path to release the larger impact.

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

The eight outer slots 16 are evenly spaced circumferentially, and each outer slot 16 is uniform in shape and configuration. The two inner grooves 18 are evenly spaced circumferentially and each inner groove 18 is identical in shape and configuration. In some embodiments, the number of outer slots 16 is greater than the number of inner slots 18. The shape and structure of only one outer tank 16 and one inner tank 18 will be described below.

The end of the outer slot 16 is provided with a first bending part 22, and the first bending part 22 can extend towards the outside or towards the inside. The first bend 22 may comprise a curved segment, a straight segment, or a combination of curved and straight segments. That is, the end of the outer groove 16 may extend outward or inward in a curved shape, may extend outward or inward in a linear shape, or may extend outward or inward in a curved shape first and then in a linear shape or first and then in a curved shape.

In the illustrated embodiment, each outer slot 16 is provided at both ends with a first bend 22. In order to reduce stress concentration, the end of the first bent portion 22 may have a circular arc shape.

The end of the inner groove 18 is provided with a second bent portion 24, and the second bent portion 24 extends toward the inner side. The second bend 24 may also comprise a curved segment, a straight segment, or a combination of curved and straight segments. That is, the end of the inner tank 18 may extend inward in a curved shape, may extend inward in a straight shape, may extend inward in a curved shape first and then in a straight shape, or may extend inward in a straight shape first and then in a curved shape.

In the illustrated embodiment, the ends of each inner groove 18 are provided with second bends 24. In order to reduce stress concentration, the end of the second bent portion 24 may have a circular arc shape.

It should be understood that, in the present invention, the first bent portions 22 of all the outer slots 16 extend toward the outer side at the same time, or extend toward the inner side at the same time. The second bends 24 of all of the inner slots 18 extend simultaneously toward the inner side. In some embodiments, it is also possible that the first bent portion 22 of the partial outer groove 16 extends toward the outside, and the first bent 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 bent portion 22 at the end of the outer slot 16 extends toward the outside, and the first bent portion 22 is an arc-shaped segment, and the arc-shaped segment extends toward the outside in a half-round bracket shape. For an outer slot 16, the first bends 22 at the ends of the outer slot 16 can be considered as forming a complete bracket. For two adjacent outer slots 16, the two adjacent first bends 22 of the two adjacent outer slots 16 can be regarded as two opposite semicircular brackets. The second bend 24 at the end of the inner groove 18 is U-shaped. Specifically, the second bent portion 24 at the end of the inner groove 18 extends toward the inner side, and the second bent portion 24 is also an arc-shaped segment extending toward the inner side in a half-bracket shape. For an inner groove 18, the two second bent portions 24 at the two ends of the inner groove 18 can be regarded as forming a complete round bracket. For two adjacent inner slots 18, the two adjacent second bent portions 24 of the two adjacent inner slots 18 can 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, wherein in the illustrated embodiment, each first connecting arm 26 has the same structure and shape and the same circumferential width; each second connecting arm 28 has the same structure and shape and the same circumferential width, and the two second connecting arms 28 are symmetrical with respect to the inner circle diameter L2. The first connecting arm 26 extends outwardly from the outer edge of the annular connecting arm 20, the second connecting arm 28 extends inwardly 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 correspond to the center positions of the two circumferentially opposite outer grooves 16, respectively.

Since the first bent portion 22 is an arc-shaped segment extending outward in a half-bracket shape, and the second bent portion 24 is an arc-shaped segment extending inward in a half-bracket shape, the circumferential width of the first connecting arm 26 is first reduced and then increased outward in the radial direction of the MEMS diaphragm 10; the circumferential width of the second connecting arms 28 first decreases and then increases radially inward of the MEMS diaphragm 10.

The circumferential width of the first connecting arm 26 may be set to be greater than, equal to or less than the circumferential width of the second connecting arm 28 according to the specific design requirements and practical use of the MEMS membrane 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.

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

When the MEMS diaphragm 10 is subjected to less than the predetermined pressure, the sensing portion 12 moves relative to the peripheral portion 14 in a direction perpendicular to the diaphragm toward the direction of the force. Viewed from another perspective, the line connecting the two second connecting arms 28 divides the outer edge of the sensing portion 12 into two portions, and the gap formed between the outer edge of each portion and the inner edge of the peripheral portion 14 is uniform along the outer edge of each portion. At this time, the second connecting arm 28 moves vertically along 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 the MEMS diaphragm 10 is subjected to more than the further predetermined pressure, the sensing portion 12 moves in an arcuate manner with respect to the peripheral portion 14 towards the force-receiving direction, as shown in fig. 2. In another aspect, the line connecting 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 gradually increases from the two second connecting arms 28 to the middle along the outer edge of each part.

In summary, the present invention provides a MEMS diaphragm, in which a plurality of outer grooves and two inner grooves are disposed between a sensing portion and an outer peripheral portion, ends of the outer grooves extend outward, and ends of the inner grooves extend inward. An annular connecting arm is formed between the outer grooves and the inner grooves, a first connecting arm is formed between every two adjacent outer grooves, and a second connecting arm is formed between every two adjacent inner grooves. The plurality of outer grooves are annularly arranged on the inner edge of the peripheral portion, the two inner grooves are annularly arranged on the outer edge of the sensing portion, the two inner grooves are arranged to be symmetrical with respect to the center of the sensing portion, the sensitivity of the diaphragm is improved, when the MEMS diaphragm is under large pressure, the sensing portion can move in an arched mode relative to the peripheral portion, stress is released in time, external mechanical strength can be released if the external mechanical strength is large, the diaphragm is not resisted by the external mechanical strength, and therefore the mechanical reliability of the MEMS diaphragm and the MEMS sensor chip is improved. The first connecting arm and the second connecting arm are arranged in a staggered mode in the circumferential direction, stress concentration can be reduced, the end of the outer groove extending in a bent mode and the end of the inner groove enable mechanical sensitivity of the sensing portion 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 should be considered illustrative rather than limiting. The scope of the invention 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 diaphragm 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 outer grooves are annularly arranged on the inner edge of the peripheral part, the two inner grooves are annularly arranged on 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 about the center of the sensing part.

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 of claim 2 wherein the number of outer grooves is greater than the number of inner grooves.

4. The MEMS membrane according to claim 1, wherein the end of the outer groove is provided with a first bending portion, the first bending portion extends toward the outer side or the inner side of the MEMS membrane, the first bending portion is U-shaped or the end of the first bending portion is a circular arc-shaped end.

5. The MEMS diaphragm according to claim 1, wherein the end of the inner groove has a second bent portion extending toward the outer side or the inner side of the MEMS diaphragm, and the second bent portion is U-shaped or the end of the second bent portion is a circular arc-shaped end.

6. The MEMS membrane of any one of claims 1 to 5, wherein a first connecting arm is formed between two adjacent outer grooves, a second connecting arm is formed between two adjacent inner grooves, and a ring-shaped connecting arm is formed between the plurality of outer grooves and the two inner grooves, the ring-shaped connecting arm being connected to the peripheral portion by the first connecting arm and connected to the sensing portion by the second connecting arm, the first connecting arm and the second connecting arm being offset from each other in a circumferential direction of the ring-shaped connecting arm.

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

8. The MEMS diaphragm of claim 7,

the circumferential width of the first connecting arm is firstly reduced and then increased along the radial direction of the MEMS diaphragm; and/or

The circumferential width of the second connecting arm is firstly reduced and then increased along the radial direction of the MEMS diaphragm.

9. The MEMS diaphragm of claim 8,

the annular connecting arms have a uniform radial width; or

The width of the annular connecting arms is greater at the ends close to the inner and/or outer slots than at the ends remote therefrom.

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