Microphone manufacturing method
A microphone manufacturing method that includes forming an etching protective film on a surface of a semiconductor substrate, opening an etching window through the etching protective film, and forming a sacrifice layer in the etching window and also on an upper face of the etching protective film. The method includes forming a vibration film above said sacrifice layer and starting an etching process of said sacrifice layer through a preformed port at a location wherein said sacrifice layer is sandwiched by said vibration film and the etching protective film and located apart from the etching window. The etching process uses an etchant to which the etching protective film is resistant, to open the etching window. The method includes crystal anisotropically etching said semiconductor substrate through the port and the etching window by using an etchant to which the etching protective film is resistant so that a cavity is formed.
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 and on an upper face of said etching protective film;
forming a vibration film above said sacrifice layer;
starting an etching process of said sacrifice layer through a preformed port at a location wherein said sacrifice layer is sandwiched by said vibration film and said etching protective film and wherein said port is located at a position 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 through said port and said etching window by using an 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 and 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 , further comprising the step of forming a protective film on said vibration film 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 3 , wherein, by etching the protective film on one portion of a formation area of said vibration film, said vibration film is allowed to bend.
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 etched such as to penetrate said semiconductor substrate from the surface side to back face side.
8. 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.
9. The microphone manufacturing method according to claim 1 , wherein, by forming said sacrifice layer on at least one portion of a formation area of said vibration film, at least one stopper is formed on the surface of said vibration film.