Method for manufacturing accelerometer sensor
First Claim
1. A method of manufacturing an accelerometer sensor, said sensor comprising a silicon substrate;
- an epitaxial layer deposited on said substrate;
a strain gauge provided in said epitaxial layer; and
a mass portion joining with said epitaxial layer and located in an opening formed in said substrate, said method comprising the steps of;
forming a first P-type silicon area in a part of an upper area of a substrate made of P-type single crystal silicon, by means of impurity doping;
forming an epitaxial layer, made of N-type single crystal silicon, on a side of said silicon substrate, so that said first P-type silicon area is located between said silicon substrate and said epitaxial layer;
forming a second P-type silicon area in a part of said epitaxial layer by means of impurity doping, said first and second P-type silicon areas for use in the formation of an inner space in the sensor;
forming a strain gauge in a part of said epitaxial layer;
forming a resist over said epitaxial layer;
subjecting a composite of said silicon substrate and said epitaxial layer to an anodization in which said silicon substrate is used as an anode, thereby to convert said first and second P-type silicon areas to a porous silicon area;
providing a wiring pattern connected to said strain gauge;
forming a mask with an opening necessary for forming a mass portion on a lower surface of said silicon substrate; and
applying an etching through the opening of said mask to said porous silicon area as well as said silicon substrate, thereby forming a mass portion joining with said epitaxial layer and located in an opening formed in said substrate.
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Abstract
A method of manufacturing an accelerometer sensor having a mass portion is disclosed. A P-type silicon area is formed in an upper area of a P-type silicon substrate by means of impurity doping. An N-type silicon layer is formed on the silicon substrate through vapor phase epitaxy. A recess defining the mass portion is formed in the silicon substrate through an etching process. A current is supplied to the silicon substrate in an electrolytic solution, such as HF aq., while the substrate is connected to an anode of a power supply. The P-type silicon area is then converted to a porous silicon area. The porous silicon area is subjected to a wet etching to be hollowed, thus obtaining a mass portion of a desired shape.
27 Citations
6 Claims
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1. A method of manufacturing an accelerometer sensor, said sensor comprising a silicon substrate;
- an epitaxial layer deposited on said substrate;
a strain gauge provided in said epitaxial layer; and
a mass portion joining with said epitaxial layer and located in an opening formed in said substrate, said method comprising the steps of;forming a first P-type silicon area in a part of an upper area of a substrate made of P-type single crystal silicon, by means of impurity doping; forming an epitaxial layer, made of N-type single crystal silicon, on a side of said silicon substrate, so that said first P-type silicon area is located between said silicon substrate and said epitaxial layer; forming a second P-type silicon area in a part of said epitaxial layer by means of impurity doping, said first and second P-type silicon areas for use in the formation of an inner space in the sensor; forming a strain gauge in a part of said epitaxial layer; forming a resist over said epitaxial layer; subjecting a composite of said silicon substrate and said epitaxial layer to an anodization in which said silicon substrate is used as an anode, thereby to convert said first and second P-type silicon areas to a porous silicon area; providing a wiring pattern connected to said strain gauge; forming a mask with an opening necessary for forming a mass portion on a lower surface of said silicon substrate; and applying an etching through the opening of said mask to said porous silicon area as well as said silicon substrate, thereby forming a mass portion joining with said epitaxial layer and located in an opening formed in said substrate. - View Dependent Claims (2, 3)
- an epitaxial layer deposited on said substrate;
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4. A method of manufacturing an accelerometer sensor, said sensor comprising a silicone substrate;
- an epitaxial layer deposited on said substrate;
a strain gauge provided in said epitaxial layer; and
a mass portion joining with said epitaxial layer and located in an opening formed in said substrate, said method comprising the steps of;forming a P-type silicon area in a part of an upper area of a substrate made of P-type single crystal silicon, by means of impurity doping; forming an epitaxial layer, made of N-type single crystal silicon, on a side of said silicon substrate, so that said P-type silicon area is located between said silicon substrate and said epitaxial layer; forming a strain gauge, made of P-type silicon, in a part of said epitaxial layer; providing a wiring pattern connected to said strain gauge; forming a mask with an opening necessary for forming a mass portion on a lower surface of said silicon substrate; forming a recess which defines a mass portion in said silicon substrate by subjecting said silicon substrate to an etching through the opening of said mask; subjecting said silicon substrate to an anodization in which said silicon substrate is used as an anode, thereby to convert said P-type silicon area to a porous silicon area; and hollowing said porous silicon area by means of a wet etching of said porous silicon area.
- an epitaxial layer deposited on said substrate;
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5. A method of manufacturing an accelerometer sensor comprising a mass portion, said method comprising the steps of:
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providing a first silicon layer serving as a substrate; forming a P-type silicon area in an upper area of said first silicon layer, by means of impurity doping; forming a second silicon layer on said first silicon layer through vapor phase epitaxy, so that said P-type silicon area is located between said first and second silicon layers; forming a recess which defines a mass portion in said first silicon layer; supplying a current to said first and second silicon layers in an electrolytic solution while one of said first and second silicon layers is connected to an anode of a power supply, thereby converting said P-type silicon area to a porous silicon area; and hollowing said porous silicon area by means of a wet etching of said porous silicon area. - View Dependent Claims (6)
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Specification