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US 6,806,593 B2Granted
Thin film electret microphone
AssigneeCalifornia Institute of Technology
InventorsYu-Chong Tai, Tseng-Yang Hsu, Wen H. Hsieh
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AssigneeCalifornia Institute of Technology
InventorsYu-Chong Tai, Tseng-Yang Hsu, Wen H. Hsieh
Estimating the term…
An electret formed by micro-machining technology on a support surface, including a self-powered electret sound transducer, preferably in the form of a microphone, formed by micro-machining technology. Each microphone is manufactured as a two-piece unit, comprising a microphone membrane unit and a microphone back plate, at least one of which includes an electret formed by micro-machining technology. When juxtaposed, the two units form a microphone that can produce a signal without the need for external biasing, thereby reducing system volume and complexity. The electret material used is a thin film of spin-on polytetrafluoroethylene (PTFE). An electron gun preferably is used for charge implantation. The electret has a saturated charged density in the range of about 2×10−5 C/m2 to about 8×10−4 C/m2. Thermal annealing is used to stabilize the implanted charge. An open circuit sensitivity of about 0.5 mV/Pa has been achieved for a hybrid microphone package.
A method of fabricating an electret by the step of forming, an electret layer on a support structure by spinning on the electret layer;
A method of fabricating an electret by the step of forming, by micro-machining techniques, an electret layer on a support structure, and forming charge on said electret layer;
A method of fabricating an electret by the step of forming, by micro-machining techniques, an electret layer on a support structure, and forming charge on said electret layer;
A method of fabricating an electret by the step of forming, by micro-machining techniques, an electret layer on a support structure, and forming charge on said electret layer;
A method, comprising:
A method, comprising:
Dependencies are inferred from the claim text.