Capacitive microphone and method therefor
First Claim
Patent Images
1. A capacitive microphone comprising:
- a substrate having a first surface, a second surface opposite to the first surface, and an atmospheric opening extending through the substrate from the second surface;
a doped polysilicon diaphragm of the capacitive microphone overlying the atmospheric opening;
a fixed capacitor plate formed from polysilicon wherein the fixed capacitor plate is aligned to the diaphragm; and
a silicon cap overlying the diaphragm and the fixed capacitor plate, the silicon cap forming a cavity with the diaphragm and the fixed capacitor plate therein.
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Abstract
A capacitive microphone (10) utilizes a polysilicon diaphragm (14) that overlies an atmospheric cavity (34). The diaphragm is doped and annealed to form a sensitivity of the microphone (10). A silicon cap covers and protects the diaphragm (14) and a fixed plate (18).
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Citations
11 Claims
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1. A capacitive microphone comprising:
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a substrate having a first surface, a second surface opposite to the first surface, and an atmospheric opening extending through the substrate from the second surface; a doped polysilicon diaphragm of the capacitive microphone overlying the atmospheric opening; a fixed capacitor plate formed from polysilicon wherein the fixed capacitor plate is aligned to the diaphragm; and a silicon cap overlying the diaphragm and the fixed capacitor plate, the silicon cap forming a cavity with the diaphragm and the fixed capacitor plate therein. - View Dependent Claims (2, 3, 4)
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5. A capacitive microphone comprising:
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a silicon substrate having an atmospheric opening through the substrate; an etch stop layer on the substrate, the etch stop layer having an opening aligned to the atmospheric opening; a polysilicon diaphragm on the etch stop layer and overlying the atmospheric opening; a polysilicon fixed plate overlying and spaced apart from the polysilicon diaphragm; and a cap overlying and spaced apart from the polysilicon fixed plate, the cap fixedly attached by a frit glass seal. - View Dependent Claims (6, 7, 8, 9, 10, 11)
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Specification