Method of manufacturing a capacitance type acceleration sensor
First Claim
1. A method of manufacturing a capacitance type acceleration sensor including a p-type single crystal silicon base plate having an outer surface and a recess portion, a mass portion having an upper side, a lower side, and a lateral side, wherein the mass portion is movably arranged in said recess portion, a support for elastically supporting said mass portion from the lower side of said mass portion and a plurality of beams for elastically supporting said mass portion from the lateral side of said mass portion, said method comprising the steps of:
- embedding and forming a first p-type silicon layer in said p-type single crystal silicon base plate;
forming a second p-type silicon layer for communicating said embedded first p-type silicon layer with the outer surface of said p-type single crystal silicon base plate;
conducting anode formation on said first and second p-type silicon layers so as to change both p-type silicon layers into a porous silicon layer; and
conducting alkali-etching so as to remove said porous silicon layer and form said recess portion at a position where said porous silicon layer is removed and further to form said mass portion, said support and said beams in said recess portion.
0 Assignments
0 Petitions
Accused Products
Abstract
A compact capacitance type acceleration sensor in which a mass portion having a plurality of movable electrodes are arranged in a recess portion formed on the surface of a p-type single crystal silicon base plate under the condition that the mass portion can be displaced. A plurality of stationary electrodes are arranged at a position opposed to the movable electrodes being separate from the movable electrodes. The mass portion is elastically supported by a support from the lower side and also elastically supported by four beams from the lateral side. Due to the above structure, the damping characteristic of the mass portion can be improved.
22 Citations
11 Claims
-
1. A method of manufacturing a capacitance type acceleration sensor including a p-type single crystal silicon base plate having an outer surface and a recess portion, a mass portion having an upper side, a lower side, and a lateral side, wherein the mass portion is movably arranged in said recess portion, a support for elastically supporting said mass portion from the lower side of said mass portion and a plurality of beams for elastically supporting said mass portion from the lateral side of said mass portion, said method comprising the steps of:
-
embedding and forming a first p-type silicon layer in said p-type single crystal silicon base plate; forming a second p-type silicon layer for communicating said embedded first p-type silicon layer with the outer surface of said p-type single crystal silicon base plate; conducting anode formation on said first and second p-type silicon layers so as to change both p-type silicon layers into a porous silicon layer; and conducting alkali-etching so as to remove said porous silicon layer and form said recess portion at a position where said porous silicon layer is removed and further to form said mass portion, said support and said beams in said recess portion.
-
-
2. A method of manufacturing a capacitance type acceleration sensor including a p-type single crystal silicon base plate having an outer surface and a recess portion, a mass portion having an upper side, a lower side, and a lateral side, wherein the mass portion is movably arranged in said recess portion, a plurality of movable electrodes disposed on said mass portion, a plurality of stationary electrodes arranged so as to oppose said movable electrodes and being separate from said movable electrodes, a support for elastically supporting said mass portion from the lower side of said mass portion and a plurality of beams for elastically supporting said mass portion from the lateral side of said mass portion, comprising the steps of:
-
forming a first p-type silicon diffusion layer in a region on the surface of said p-type single crystal silicon base plate; forming an n-type silicon layer so as to cover said p-type silicon diffusion layer and where the n-type silicon layer has an outer surface; forming a second p-type silicon diffusion layer for communicating said embedded first p-type silicon diffusion layer with the outer surface of said n-type silicon layer; conducting anode formation on said first and second p-type silicon diffusion layers so as to change both p-type silicon diffusion layers into a porous silicon layer; forming said movable electrodes by physical film forming method on the surface of said p-type single crystal silicon base plate on which said n-type silicon is formed; conducting alkali-etching so as to remove said porous silicon layer and form said recess portion at a position where said porous silicon layer is removed and further to form said mass portion, said support and said beam in said recess portion; and conducting anode-junction so as to join a glass base plate on which said stationary electrodes are formed, to the surface of said p-type single crystal base plate. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10, 11)
-
Specification