MICROPHONE MANUFACTURING METHOD

• US 20090181489A1
• Filed: 02/23/2007
• Published: 07/16/2009
• Est. Priority Date: 04/27/2006
• Status: Active Grant

• Current Assignee: MMI Semiconductor Company Limited
• Original Assignee: Omron Corporation
• Inventors: Horimoto, Yasuhiro, Kasai, Takashi
• Granted Patent: US 7,849,583 B2
• Time in Patent Office: Days
• US Class Current: 438/53
• CPC Class Codes: H04R 19/005 using semiconductor materials
• CPC Class Codes: H04R 19/04 Microphones H04R19/01 takes precedence
• CPC Class Codes: H04R 31/00 Apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor manufacture of microstructural arrangements of deformable or non-deformable structures in general B81C1/00182
• CPC Class Codes: Y10T 29/49002 Electrical device making
• CPC Class Codes: Y10T 29/49005 Acoustic transducer
• CPC Class Codes: Y10T 29/4908 Acoustic transducer

Abstract

A sacrifice layer 36 is exposed through a chemical charging port 31 so that the sacrifice layer 36 and sacrifice layer 35 are etched and removed by an etchant introduced from the chemical charging port 31. Since the surface of an Si substrate 22 is exposed to an etching window 34 corresponding to the removed portion of the sacrifice layer 35, the Si substrate 22 is crystal anisotropically etched below the etching window 34 to form a cavity 23. In contrast, in a space corresponding to the etched and removed portion of the sacrifice layer 36, since the surface of the Si substrate 22 is covered with a protective film 32, the Si substrate 22 is not etched to form a bent hole 26 therein. The cavity can be formed in the semiconductor substrate by an etching process from the surface side. Moreover, a bent hole having a great acoustic resistance can be easily formed.

Claims

1. A microphone manufacturing method comprising the steps of:

forming an etching protective film on a surface of a semiconductor substrate, and then opening an etching window through said etching protective film;

forming a sacrifice layer in said etching window as well as on an upper face of said etching protective film, with at least one portion thereof being connected to each other;

forming a vibration film above said sacrifice layer;

starting an etching process on said sacrifice layer from a portion that is sandwiched by said vibration film and said etching protective film and located apart from said etching window, by using an etchant to which said etching protective film is resistant, so that said etching window is opened; and

crystal anisotropically etching said semiconductor substrate from said etching window by using said etchant to which said etching protective film is resistant so that a cavity is formed on the surface side of said semiconductor substrate.

2. The microphone manufacturing method according to claim 1, further comprising the step of:

prior to forming said vibration film after forming said sacrifice layer forming a protective film on said sacrifice layer, by using a material that is resistant to said etchant used for etching said sacrifice layer as well as an etchant used for etching said semiconductor substrate.

3. The microphone manufacturing method according to claim 1, wherein a protective film is formed on said vibration film by using a material that is resistant to said etchant used for etching said sacrifice layer as well as an etchant used for etching said semiconductor substrate.

4. The microphone manufacturing method according to claim 1, wherein said sacrifice layer is isotropically etched and said semiconductor substrate is crystal anisotropically etched by using the same etchant.

5. The microphone manufacturing method according to claim 1, wherein said semiconductor substrate is crystal anisotropically etched by using an etchant that is different from said etchant used for etching said sacrifice layer.

6. The microphone manufacturing method according to claim 1, further comprising the step of:

forming a back plate having a fixed electrode above said vibration film.

7. The microphone manufacturing method according to claim 1, wherein said cavity is allowed to penetrate said semiconductor substrate from the surface side to back face side.

8. The microphone manufacturing method according to claim 1, wherein, by preliminarily forming said sacrifice layer on one portion of a formation area of said vibration film, said vibration film is allowed to bend.

9. The microphone manufacturing method according to claim 1, wherein, by preliminarily forming said sacrifice layer on one portion of a formation area of said vibration film, a protrusion is formed on the surface of said vibration film.