Micromachined microphone and multisensor and method for producing same
First Claim
1. Apparatus comprising:
- a wafer having at least a first silicon layer, the wafer including a plurality of trenches formed through the first silicon layer;
a first oxide layer on a front side of the first silicon layer and lining the trenches;
a sacrificial polysilicon layer on the first oxide layer;
a second oxide layer on the sacrificial polysilicon layer; and
a plurality of polysilicon microphone structures, including a diaphragm, on the second oxide layer, wherein the sacrificial polysilicon layer includes an opening at a future pedestal site underlying at least a portion of the diaphragm, and wherein the first oxide layer, the sacrificial polysilicon layer and the second oxide layer are substantially vertically between the substrate and the diaphragm.
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Accused Products
Abstract
A micromachined microphone is formed from a silicon or silicon-on-insulator (SOI) wafer. A fixed sensing electrode for the microphone is formed from a top silicon layer of the wafer. Various polysilicon microphone structures are formed above a front side of the top silicon layer by depositing at least one oxide layer, forming the structures, and then removing a portion of the oxide underlying the structures from a back side of the top silicon layer through trenches formed through the top silicon layer. The trenches allow sound waves to reach the diaphragm from the back side of the top silicon layer. In an SOI wafer, a cavity is formed through a bottom silicon layer and an intermediate oxide layer to expose the trenches for both removing the oxide and allowing the sound waves to reach the diaphragm. An inertial sensor may be formed on the same wafer, with various inertial sensor structures formed at substantially the same time and using substantially the same processes as corresponding microphone structures.
229 Citations
11 Claims
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1. Apparatus comprising:
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a wafer having at least a first silicon layer, the wafer including a plurality of trenches formed through the first silicon layer; a first oxide layer on a front side of the first silicon layer and lining the trenches; a sacrificial polysilicon layer on the first oxide layer; a second oxide layer on the sacrificial polysilicon layer; and a plurality of polysilicon microphone structures, including a diaphragm, on the second oxide layer, wherein the sacrificial polysilicon layer includes an opening at a future pedestal site underlying at least a portion of the diaphragm, and wherein the first oxide layer, the sacrificial polysilicon layer and the second oxide layer are substantially vertically between the substrate and the diaphragm. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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Specification