Capacitive silicon microphone and fabrication method thereof

Patent metadata

Field	Value
Publication number	US-9913040-B2
Application number	US-201415033113-A
Country	US
Kind code	B2
Filing date	Sep 26, 2014
Priority date	Nov 29, 2013
Publication date	Mar 6, 2018
Grant date	Mar 6, 2018

Abstract

A capacitive silicon microphone comprises: a first dielectric layer sets on a substrate with a back cavity, a lower polar plate which is located over the back cavity, a first elastic member of which an inner edge is connected with the edge of the lower polar plate and an outer edge is located on the upper surface of the first dielectric layer, a second dielectric layer which is located on the outer edge of the first elastic member and right above the first dielectric layer, an upper polar plate which has a plurality of release holes and is formed above the lower polar plate with an air gap in between, a second elastic member of which an inner edge is connected with the edge of the upper polar plate and an outer edge is located on the upper surface of the second dielectric layer.

First claim

The invention claimed is:

1. A capacitive silicon microphone comprises:
a substrate with a back cavity;
a first dielectric layer, which is formed over the substrate;
a lower polar plate, which is located over the back cavity, as a vibrating diaphragm of the capacitive silicon microphone;
a first elastic member, which has an inner edge and an outer edge, the inner edge thereof being connected with edge of the lower polar plate, and the outer edge thereof being located on the upper surface of the first dielectric layer;
a second dielectric layer, which is located on the outer edge of the first elastic member and right above the first dielectric layer;
an upper polar plate as a back electrode of the capacitive silicon microphone, which has a plurality of release holes and is formed above the lower polar plate with an air gap in between;
a second elastic member, which has an inner edge and an outer edge, the inner edge thereof being connected with edge of the upper polar plate, and the outer edge thereof being located on the upper surface of the second dielectric layer;
wherein the vertical section of the first elastic member and/or the second elastic member is concave-convex shape, and the horizontal section of the first elastic member and/or the second elastic member is concave-convex shape.

2. The capacitive silicon microphone according to claim 1 , which is characterized in that, inner sidewall of the first dielectric layer has a first etch-stop layer, and/or inner side-wall of the second dielectric layer has a second etch-stop layer.

3. The capacitive silicon microphone according to claim 1 , which is characterized in that, the first elastic member has at least two first elastic elements that uniformly distribute at the periphery of the lower polar plate, and the second elastic member has at least two second elastic elements that uniformly distribute at the periphery of the upper polar plate, each of the first elastic elements has an inner edge connected with the edge of the lower polar plate and an outer edge located on the upper surface of the first dielectric layer, each of the second elastic elements has an inner edge connected with the edge of the upper polar plate and an outer edge located on the upper surface of the second dielectric layer.

4. The capacitive silicon microphone according to claim 1 , which is characterized in that, the first elastic member has a first elastic coefficient, and the second elastic member has a second elastic coefficient, the second elastic coefficient is higher than the first elastic coefficient.

5. The capacitive silicon microphone according to claim 4 , which is characterized in that, the first elastic member and the second elastic member are regarded as a spring, and the surface stress of the upper polar plate and the lower polar plate may be calculated from the following formula:
TS =(Asp/Asp−covered)·( K 1/Ssp)·(Wsp/ K 2)·(Thsp/ Th 0)· T 0

wherein TS indicates the surface stress of the lower polar plate when the first elastic member is set or the surface stress of the upper polar plate when the second elastic member is set, Asp indicates effective area of the corresponding spring, Asp-covered indicates region area of the corresponding spring, Ssp indicates the number of the coils of the corresponding spring, Wsp indicates the diameter of the corresponding spring, Thsp indicates the length of the corresponding spring, Th0 indicates the thickness of the air gap, T0 indicates the surface stress of the lower polar plate when the first elastic member is not set or the surface stress of the upper polar plate when the second elastic member is not set, K1 indicates the elastic coefficient of the corresponding spring in single turn, and K2 indicates the elastic coefficient of the corresponding spring in unit width.

6. The capacitive silicon microphone according to 1 , which is characterized in that, the structure of the upper polar plate or the lower polar plate is a polycrystalline silicon film.

7. The capacitive silicon microphone according to claim 2 , which is characterized in that, the structure of the upper polar plate or the lower polar plate is a polycrystalline silicon film.

8. The capacitive silicon microphone according to claim 3 , which is characterized in that, the structure of the upper polar plate or the lower polar plate is a polycrystalline silicon film.

9. The capacitive silicon microphone according to claim 1 , which is characterized in that, the structure of the upper polar plate or the lower polar plate is a polycrystalline silicon film.

10. The capacitive silicon microphone according to claim 4 , which is characterized in that, the structure of the upper polar plate or the lower polar plate is a polycrystalline silicon film.

11. The capacitive silicon microphone according to claim 5 , which is characterized in that, the structure of the upper polar plate or the lower polar plate is a polycrystalline silicon film.

Assignees

• Shanghai Ic R&D Ct Co Ltd
• Shanghai Ic R&D Ct Co Ltd

Inventors

• Zhao Yuhang
• Wang Yong
• Kang Xiaoxu
• Chen Yan

Classifications

• H04R31/006

  Interconnection of transducer parts (of diaphragm and outer suspension by moulding H04R31/003) · CPC title

• H04R19/005

  using semiconductor materials · CPC title

• H04R31/003

  for diaphragms or their outer suspension · CPC title

• H04R7/08

  comprising superposed layers separated by air or other fluid · CPC title

• H04R2201/003

  Mems transducers or their use · CPC title