Method of making silicon-based miniaturized microphones

• US 20060291674A1
• Filed: 06/14/2005
• Published: 12/28/2006
• Est. Priority Date: 06/14/2005
• Status: Abandoned Application

• Current Assignee: Merry Electronics Company Limited
• Original Assignee: Merry Electronics Company Limited
• Inventors: Gong, Shih-Chin, Cheng, Cyuan-Sian, Lin, Zhong-Yuan, Huang, Yao-Min, Hsue, Shu-Yuan
• Application Number:
  US11/151,460
• Publication Number:
  US 20060291674A1
• Time in Patent Office: Days
• US Class Current: 381/174
• CPC Class Codes: H04R 19/04 Microphones H04R19/01 takes precedence

Abstract

A method of making a silicon-based miniaturized microphone by means of the application of a combination of processes including a semiconductor manufacturing process and a silicon micro-machining technology. A silicon-based miniaturized microphone made by means of this method has a silicon substrate, which defines a resonance cavity, a diaphragm, a backplate having sound holes, and solder pads. This method is easy to perform, and suitable for a mass production to reduce the manufacturing cost.

Claims

1. A method of making a silicon-based miniaturized microphone comprising the steps of:

a) preparing a silicon substrate having a dielectric layer respectively covered on top and bottom surfaces thereof and depositing a polysilicon material on the dielectric layer at the top surface of said silicon substrate to form a diaphragm, and then doping said diaphragm with ions selected from a group consisting of baron ions and phosphor ions, and then annealing said diaphragm, and then etching said diaphragm by a photo lithographic process subject to a predetermined pattern;

b) depositing a sacrificial layer on said diaphragm;

c) depositing an insulative layer on said sacrificial layer;

d) depositing a polysilicon film on said insulative layer and then doping the polysilicon film with ions selected from a group consisting of baron ions and phosphor ions and then annealing the polysilicon film to form a backplate, and then etching said backplate subject to a predetermined pattern;

e) depositing a passivation on said backplate and then etching said passivation to provide a contact window;

f) using a coating technology selected from a group consisting of a sputtering coating technology and an evaporation coating technology to form two solder pads, which are respectively and electrically connected to said backplate and said diaphragm, within said contact window;

g) etching said passivation, said backplate and said insulative layer, so as to form a plurality of sound holes;

h) stripping off the dielectric layer at the bottom surface of said silicon substrate, and then etching said silicon substrate, and then stripping off a part of the dielectric layer at the top surface of said silicon layer so as to form a resonance cavity; and

i) stripping off said sacrificial layer.

2. The method of making a silicon-based miniaturized microphone as claimed in claim 1, wherein the dielectric layers at the top and bottom surfaces of said silicon substrate are made from a material selected from a group consisting of silicon dioxide and silicon nitride.

3. The method of making a silicon-based miniaturized microphone as claimed in claim 1, wherein said diaphragm has a thickness ranging from about 0.1 to 4.0 μ

m.

4. The method of making a silicon-based miniaturized microphone as claimed in claim 1, wherein said sacrificial layer is made from a material selected from a group consisting of low temperature oxide and phosphorous silicon glass.

5. The method of making a silicon-based miniaturized microphone as claimed in claim 1, wherein said sacrificial layer has a thickness ranging from about 0.5 to 5.0 μ

m.

6. The method of making a silicon-based miniaturized microphone as claimed in claim 1, wherein said insulative layer is made from silicon nitride.

7. The method of making a silicon-based miniaturized microphone as claimed in claim 1, wherein said insulative layer has a thickness ranging from about 0.1 to 2.0 μ

m.

8. The method of making a silicon-based miniaturized microphone as claimed in claim 1, wherein said backplate has a thickness ranging about 1.0 to 6.0 μ

m.

9. The method of making a silicon-based miniaturized microphone as claimed in claim 1, wherein said passivation is made from silicon nitride.

10. The method of making a silicon-based miniaturized microphone as claimed in claim 1, wherein said solder pads are made from a metal selected from a group consisting of aluminum, gold, chrome, platinum, titanium, nickel, copper, and silver.

11. The method of making a silicon-based miniaturized microphone as claimed in claim 1, wherein said solder pads have a thickness raging about 0.1 to 1.5 μ

m.

12. The method of making a silicon-based miniaturized microphone as claimed in claim 1, wherein the depositing technique used is selected from a group consisting of low pressure chemical vapor deposition technique and plasma enhanced chemical vapor deposition technique.

13. The method of making a silicon-based miniaturized microphone as claimed in claim 1, wherein the process of etching said silicon substrate to form said resonance cavity is performed through an etching technique selected from a group consisting of an anisotropic chemical wet etching technology and an inductively coupled plasma dry etching technology.

14. The method of making a silicon-based miniaturized microphone as claimed in claim 1, wherein the step i) of stripping off said sacrificial layer is done by means of performing a chemical wet etching process with the use of an etchant selected from a group consisting of HF (Hydrofluoric Acid) and BOE (Buffered Oxide Etchant).

15. The method of making a silicon-based miniaturized microphone as claimed in claim 14, wherein the step i) of stripping off said sacrificial layer includes an organic drying process employed after the chemical wet etching process.

16. The method of making a silicon-based miniaturized microphone as claimed in claim 1, wherein said step i) of stripping off said sacrificial layer is done by means of performing a dry etching technology selected from a group consisting of hydrofluoric acid vapor etching technology and isotropic inductively coupled plasma dry etching technology.