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US 8,803,260 B2Granted
Low frequency CMUT with vent holes
AssigneeTexas Instruments Incorporated
InventorsSteven Adler, Peter Johnson, Ira Oaktree Wygant
Life of this patent
Estimating the term…
Abstract
A capacitive micromachined ultrasonic transducer (CMUT), which has a conductive structure that can vibrate over a cavity, has a number of vent holes that are formed in the bottom surface of the cavity. The vent holes eliminate the deflection of the CMUT membrane due to atmospheric pressure which, in turn, allows the CMUT to receive and transmit low frequency ultrasonic waves.
Claims19
A semiconductor transducer comprising:
- a substrate having a bottom surface, a top surface, and a plurality of vent holes that extend down from the top surface into the substrate, the substrate being conductive, the top surface lying in a plane;
- a post structure that touches the top surface of the substrate, the post structure having a top surface and being non-conductive, a portion of the post structure lying below the plane and a portion of the post structure lying above the plane;
- a non-conductive structure that touches the top surface of the substrate and lines the plurality of vent holes so that the plurality of vent holes remains open;
- and
- a conductive structure that touches the top surface of the post structure and lies directly vertically over the plurality of vent holes to form a cavity that lies directly vertically over the plurality of vent holes.
2 more elements
A method of forming a semiconductor transducer comprising:
- forming a post structure on a substrate, the substrate having a bottom surface and a top surface, the top surface lying in a plane, the post structure having a top surface and being non-conductive, a portion of the post structure lying below the plane and a portion of the post structure lying above the plane, the substrate being conductive;
- forming a plurality of vent holes in the top surface of the substrate, the plurality of vent holes extending down from the top surface of the substrate into the substrate;
- forming a non-conductive structure that touches the top surface of the substrate and lines the plurality of vent holes so that the plurality of vent holes remains open;
- and
- forming a conductive structure that touches the top surface of the post structure and lies directly vertically over the plurality of vent holes to form a cavity that lies directly vertically over the plurality of vent holes.
2 more elements
Dependencies are inferred from the claim text.