MEMS microphone

Abstract

An MEMS microphone, comprising: a substrate provided with a back cavity (11) and a capacitance system arranged on the substrate. The capacitance system comprises a back plate (2) and a diaphragm (3) arranged opposite and spaced apart from the back plate (2), wherein the surface of the back plate (2) facing the diaphragm (3) or the surface of the diaphragm (3) facing the back plate (2) is provided with dimples (4), characterized in that when the diaphragm (3) moves to enable the dimples (4) to simultaneously come into contact with the diaphragm (3) and the back plate (2), the dimples (4) can elastically deform in the vibration direction of the diaphragm (3). The dimples (4) of the MEMS microphone have elasticity, which can provide a buffer for the movement of the diaphragm (3), and thus avoids rapid concentration of stress on the position where the diaphragm (3) is in contact with the dimples (4), thereby preventing pits from forming on the diaphragm (3) and preventing the diaphragm (3) from breaking under the repeated impact of the dimples (4).

Description

A MEMS microphone Technical Field

[0001] The present invention belongs to the field of acoustic and electrical technology, and in particular relates to a MEMS microphone. Background Art

[0002] The traditional MEMS microphone chip structure mainly includes a base structure with a back cavity, and a diaphragm and backplate structure located on the upper part of the base. The diaphragm and backplate structure constitute a capacitance system. When sound pressure acts on the diaphragm, there is a pressure difference between the two sides of the diaphragm facing the backplate and the backplate facing the backplate, causing the diaphragm to move closer to or away from the backplate, thereby causing a change in the capacitance between the diaphragm and the backplate, realizing the conversion of sound signals into electrical signals.

[0003] In related technologies, when the diaphragm moves closer to the backplate under the action of sound pressure, in order to prevent the microphone from short-circuiting due to contact between the diaphragm and the backplate, and to reduce the risk of film absorption, an anti-adhesion column (dimple) structure is usually set between the backplate and the diaphragm. The dimples can be set on the backplate side or the diaphragm side. However, for dimples set on the backplate side, when the diaphragm moves toward or away from the backplate under the action of large sound pressure, a pit will be left at the position where the diaphragm faces the dimples on the backplate. Repeated impact of the pit will cause stress concentration at this position. When the stress exceeds the breaking strength of the diaphragm material, the diaphragm will break. Similarly, for dimples set on the diaphragm side, the position where the backplate faces the dimples will also leave a pit due to repeated impact of the diaphragm, which also poses a hidden danger to the backplate breaking.

[0004] Therefore, it is necessary to provide a new MEMS microphone to solve the above technical problems. Technical issues

[0005] The object of the present invention is to provide a MEMS microphone that can solve the problem in the related art that the diaphragm is easily broken under repeated impact of dimples. Technical Solutions

[0006] A MEMS microphone comprises a substrate having a back cavity and a capacitor system arranged on the substrate, the capacitor system comprising a backplate and a diaphragm arranged opposite and spaced from the backplate, an anti-adhesion member being provided on a surface of the backplate facing the diaphragm or a surface of the diaphragm facing the backplate, and wherein when the diaphragm moves so that the anti-adhesion member contacts both the diaphragm and the backplate simultaneously, the anti-adhesion member can undergo elastic deformation along the vibration direction of the diaphragm.

[0007] Optionally, the anti-adhesion component includes a connecting portion connected to the back plate or the diaphragm, a bent portion extending from the connecting portion toward the diaphragm or the back plate, and an abutting portion connected to one end of the bent portion away from the connecting portion. When the diaphragm moves so that the anti-adhesion component contacts the diaphragm or the back plate, the abutting portion abuts against the diaphragm or the back plate.

[0008] Optionally, the capacitor system also includes a first electrode member arranged on a side of the back plate close to the diaphragm, the first electrode member is opposite to the diaphragm and spaced apart, and the connecting portion of the anti-adhesion member is fixed to a surface of the first electrode member away from the back plate.

[0009] Optionally, a surface of the first electrode element that is away from the back plate is flush with a surface of the back plate that faces the diaphragm.

[0010] Optionally, the anti-adhesion component is a spring, and the length of the anti-adhesion component extends along the vibration direction of the diaphragm.

[0011] Optionally, the interior of the anti-adhesion component is hollow or solid.

[0012] Optionally, the anti-adhesion member is an insulator or at least one end of the anti-adhesion member is an insulating end.

[0013] Optionally, the MEMS microphone further includes a first insulating layer respectively connected to the substrate and the diaphragm, and a second insulating layer respectively connected to the diaphragm and the back plate, the back plate, the first insulating layer and the diaphragm together form a sound cavity, and the back plate is provided with a sound hole connected to the sound cavity.

[0014] Optionally, the MEMS microphone further includes a protective layer disposed outside the first insulating layer and the second insulating layer, wherein one side of the protective layer is connected to the substrate, and the other side of the protective layer extends to be flush with the second insulating layer. Beneficial effects

[0015] The beneficial effect of the present invention is that when the diaphragm vibrates under high sound pressure until the anti-adhesion member contacts the diaphragm and the backplate at the same time, the diaphragm continues to move under the action of the sound pressure and electric field force, compressing the anti-adhesion member until the restoring force provided by the anti-adhesion member is greater than the electric field force and the sound pressure, the diaphragm movement speed reaches zero, and the diaphragm begins to move away from the backplate. During this process, the anti-adhesion member provides a buffer for the diaphragm's movement, preventing the diaphragm from experiencing a rapid concentration of stress at the point where it contacts the anti-adhesion member, thereby preventing the formation of pits on the diaphragm and preventing the diaphragm from breaking under the repeated impact of the anti-adhesion member. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] FIG1 is a cross-sectional view of an anti-adhesion member provided by the present invention disposed on a back plate of a MEMS microphone;

[0017] Figure 2 is an enlarged view of detail A in Figure 1;

[0018] FIG3 is a cross-sectional view of an anti-adhesion member provided on a diaphragm in a MEMS microphone provided by the present invention;

[0019] FIG. 4 is an enlarged view of detail B in FIG. 3 . Modes for Carrying Out the Invention

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0021] Please refer to Figures 1 and 3. An embodiment of the present invention provides a MEMS microphone, including a substrate having a back cavity 11 and a capacitor system arranged on the substrate. The capacitor system includes a back plate 2 and a diaphragm 3 opposite to and spaced apart from the back plate 2. The surface of the back plate 2 facing the diaphragm 3 or the surface of the diaphragm 3 facing the back plate 2 is provided with an anti-adhesion member 4. When the diaphragm 3 moves so that the anti-adhesion member 4 contacts the diaphragm 3 and the back plate 2 at the same time, the anti-adhesion member 4 can undergo elastic deformation along the vibration direction of the diaphragm 3.

[0022] When the diaphragm 3 vibrates under high sound pressure until the anti-adhesion member 4 contacts both the diaphragm 3 and the back plate 2, the diaphragm 3 continues to move under the action of the sound pressure and electric field force, compressing the anti-adhesion member 4 until the restoring force provided by the anti-adhesion member 4 is greater than the electric field force and the sound pressure, the diaphragm 3 movement speed reaches 0, and the diaphragm 3 begins to move away from the back plate 2. During this process, the anti-adhesion member 4 provides a buffer for the movement of the diaphragm 3, preventing the diaphragm 3 from being subjected to a rapid concentration of stress at the point where it contacts the anti-adhesion member 4, thereby preventing the formation of pits on the diaphragm 3 and preventing the diaphragm 3 from breaking under the repeated impact of the anti-adhesion member 4.

[0023] Referring to Figures 2 and 4, in some embodiments, the anti-adhesion member 4 includes a connecting portion 41 connected to the back plate 2 or the diaphragm 3, a bent portion 42 extending from the connecting portion 41 toward the diaphragm 3 or the back plate 2, and an abutting portion 43 connected to the bent portion 42 at one end away from the connecting portion 41. When the diaphragm 3 moves to the point where the anti-adhesion member 4 contacts the diaphragm 3 or the back plate 2, the abutting portion 43 abuts against the diaphragm 3 or the back plate 2. Specifically, a gap is provided in the bent portion 42, allowing the anti-adhesion member 4 to elastically extend or contract along the vibration direction of the diaphragm 3, thereby providing a buffer for the movement of the diaphragm 3. Two bent portions 42 can be provided, the two bent portions 42 being connected, and the connecting portion 41 and the abutting portion 43 being respectively connected to the two bent portions 42. The bent portion 42 can be U-shaped to facilitate the elastic extension or contraction of the anti-adhesion member 4 along the vibration direction of the diaphragm.

[0024] It should be understood that the number of bending portions 42 is set according to actual needs, such as one, three, four, etc.; the bending portion 42 can also be V-shaped; the connecting portion 41 and the abutting portion 43 can be connected to the middle or end of the bending portion 42, for example, the connecting portion 41 is connected to the end of the bending portion 42, and the abutting portion 43 is connected to the middle of the bending portion 42.

[0025] In other embodiments, the anti-adhesion member 4 is a spring, and the length of the anti-adhesion member 4 extends along its protruding direction, thereby achieving elastic extension or contraction of the anti-adhesion member 4 along its protruding direction.

[0026] The interior of the anti-adhesion member 4 is hollow or solid, as shown in Figures 2 and 4, preferably solid, which is conducive to reducing the manufacturing difficulty of the anti-adhesion member 4. The cross-sectional shape of the anti-adhesion member 4 can be a combination of one or more of a circle, a fan or a polygon, preferably a circle, which can reduce the contact area between the substrate and the anti-adhesion member 4, thereby reducing the adhesion between the substrate and the anti-adhesion member 4, effectively avoiding the adhesion between the diaphragm 3 and the substrate, and thus improving the reliability of the MEMS microphone. The number of anti-adhesion members 4 is set according to actual needs, such as one, three, seven and ten, etc. All anti-adhesion members 4 are spaced and evenly distributed along the circumference, which can make the stress on the diaphragm 3 or the back plate 2 more uniform, further avoiding the diaphragm 3 or the back plate 2 from being broken by stress.

[0027] Please refer to Figures 1 and 3. The capacitor system also includes a first electrode member 5 arranged on the side of the back plate 2 close to the diaphragm 3, and a second electrode member (not shown) arranged on the side of the diaphragm 3 close to the back plate 2. The first electrode member 5 and the second electrode member are spaced apart and arranged opposite to each other. When the diaphragm 3 vibrates in a direction close to or away from the back plate 2, the capacitance of the capacitor between the first electrode member 5 and the second electrode member changes.

[0028] Referring to Figures 1 and 2 , in some embodiments, an anti-adhesion member 4 is fixed to a surface of the first electrode member 5 facing away from the back plate 2. Multiple anti-adhesion members 4 may be provided, and the multiple anti-adhesion members 4 are evenly distributed on the first electrode member 5. Specifically, a mounting groove (not shown) is provided on the side of the back plate 2 near the diaphragm 3. The first electrode member 5 is mounted in the mounting groove so that the surface of the first electrode member 5 facing away from the back plate 2 is flush with the surface of the back plate 2 facing the diaphragm 3, thereby preventing contact between the diaphragm 3 and the back plate 2.

[0029] 3 and 4 , in other embodiments, the anti-adhesion member 4 is fixed to a surface of the second electrode member away from the diaphragm 3 . A plurality of anti-adhesion members 4 may be provided, and the plurality of anti-adhesion members 4 are evenly distributed on the second electrode member.

[0030] In the present invention, the first electrode member 5 and the second electrode member are always kept insulated to ensure that the capacitance of the capacitance system can be changed, thereby realizing the corresponding function of the microphone.

[0031] In some embodiments, the anti-adhesion member 4 is an insulator or at least one end of the anti-adhesion member 4 is an insulating end, so that when the diaphragm 3 moves to the point where the anti-adhesion member 4 is connected to the diaphragm 3 and the back plate 2 respectively, the diaphragm 3 and the back plate 2 are insulated. The anti-adhesion member 4 can be made entirely of an insulating material; or one end of the anti-adhesion member 4 can be made of an insulating material, for example, the end of the anti-adhesion member 4 connected to the back plate 2 or the diaphragm 3 is made of an insulating material; or both ends of the anti-adhesion member 4 can be made of an insulating material. It should be understood that when at least one end of the anti-adhesion member 4 is an insulating end, the anti-adhesion member 4 can be a conductor, that is, the anti-adhesion member 4 is made of a conductive material, and the insulating end of the anti-adhesion member 4 can be formed by coating an insulating layer.

[0032] It should be noted that both the first electrode member 5 and the second electrode member are conductive, made of polysilicon-doped or single-crystal silicon-doped conductive materials. When the MEMS microphone is powered on, the backplate 2 and diaphragm 3 carry charges of opposite polarity, forming a capacitive system. When the diaphragm 3 vibrates in response to sound waves, the distance between the first electrode member 5 and the second electrode member changes, causing the capacitance of the capacitive system to change, thereby converting the sound wave signal into an electrical signal, thus achieving the corresponding microphone function.

[0033] Referring to Figures 1 and 3 , the MEMS microphone further includes a first insulating layer 6 connected to the substrate and diaphragm 3, respectively, and a second insulating layer 7 connected to the diaphragm 3 and backplate 2, respectively. The backplate 2, first insulating layer 6, and diaphragm 3 collectively form an acoustic cavity 8, and the backplate 2 is provided with an acoustic hole 21 communicating with the acoustic cavity 8. Both the first insulating layer 6 and the second insulating layer 7 can be made of a semiconductor silicon oxide insulating material. The first insulating layer 6 supports the diaphragm 3 and ensures insulation between the diaphragm 3 and the substrate. The second insulating layer 7 supports the backplate 2 and ensures insulation between the backplate 2 and the diaphragm 3. The sound holes 21 can connect the sound cavity 8 and the external environment, so that the sound wave airflow can enter or flow out of the sound cavity 8; when the pressure (sound wave) acts on the diaphragm 3 through multiple sound holes 21, the diaphragm 3 vibrates in the direction of approaching or moving away from the back plate 2 so that the capacitance of the capacitor between the diaphragm 3 and the back plate 2 changes, thereby generating an electrical signal corresponding to the change in pressure (sound wave), which is output through an external circuit connected to the capacitor system, ultimately realizing the function of a MEMS microphone.

[0034] Referring to Figures 1 and 3, the MEMS microphone further includes a protective layer 9 disposed outside the first insulating layer 6 and the second insulating layer 7. One side of the protective layer 9 is connected to the substrate, and the other side extends to be flush with the second insulating layer 7. The protective layer 9 can be made of materials such as single crystal silicon, polycrystalline silicon, or silicon nitride, and can protect the diaphragm 3.

[0035] It should be noted that the positions of the back plate 2 and the diaphragm 3 can be adjusted as long as the two can form a capacitor system, that is, the back plate 2 can be located between the diaphragm 3 and the base, or the diaphragm 3 can be located between the back plate 2 and the base.

[0036] The above description is only an embodiment of the present invention. It should be pointed out that those skilled in the art can make improvements without departing from the creative concept of the present invention, but these improvements all fall within the scope of protection of the present invention.

Claims

1. A MEMS microphone, comprising a substrate having a back cavity and a capacitor system arranged on the substrate, wherein the capacitor system comprises a back plate and a diaphragm arranged opposite to and spaced from the back plate, and an anti-adhesion member is provided on a surface of the back plate facing the diaphragm or a surface of the diaphragm facing the back plate, wherein: When the diaphragm moves to make the anti-adhesion member contact the diaphragm and the back plate at the same time, the anti-adhesion member may be elastically deformed along the vibration direction of the diaphragm.

2. The MEMS microphone according to claim 1, characterized in that: The anti-adhesion component includes a connecting portion connected to the back plate or the diaphragm, a bending portion extending from the connecting portion toward the diaphragm or the back plate, and an abutting portion connected to one end of the bending portion away from the connecting portion. When the diaphragm moves so that the anti-adhesion component contacts the diaphragm or the back plate, the abutting portion abuts against the diaphragm or the back plate.

3. The MEMS microphone according to claim 2, characterized in that: The capacitor system also includes a first electrode member arranged on a side of the back plate close to the diaphragm, the first electrode member is opposite to the diaphragm and spaced apart, and the connecting portion of the anti-adhesion member is fixed to a surface of the first electrode member on a side away from the back plate.

4. The MEMS microphone according to claim 3, characterized in that: A surface of the first electrode element on one side away from the back plate is flush with a surface of the back plate facing the diaphragm.

5. The MEMS microphone according to claim 1, characterized in that: The anti-adhesion component is a spring, and the length of the anti-adhesion component extends along the vibration direction of the diaphragm.

6. The MEMS microphone according to claim 1, characterized in that: The interior of the anti-adhesion component is hollow or solid.

7. The MEMS microphone according to claim 1, characterized in that: The anti-adhesion member is an insulator or at least one end of the anti-adhesion member is an insulating end.

8. The MEMS microphone according to claim 1, characterized in that: The MEMS microphone further includes a first insulating layer respectively connected to the substrate and the diaphragm, and a second insulating layer respectively connected to the diaphragm and the back plate. The back plate, the first insulating layer and the diaphragm together form a sound cavity. The back plate is provided with a sound hole communicating with the sound cavity.

9. The MEMS microphone according to claim 8, characterized in that: The MEMS microphone further includes a protection layer disposed outside the first insulating layer and the second insulating layer, one side of the protection layer is connected to the substrate, and the other side of the protection layer extends to be flush with the second insulating layer.

Images