Low frequency CMUT with vent holes

摘要

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.

主权项

1. 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.