ULTRASONIC TRANSDUCERS IN COMPLEMENTARY METAL OXIDE SEMICONDUCTOR (CMOS) WAFERS AND RELATED APPARATUS AND METHODS

摘要

Micromachined ultrasonic transducers formed in complementary metal oxide semiconductor (CMOS) wafers are described, as are methods of fabricating such devices. A metallization layer of a CMOS wafer may be removed by sacrificial release to create a cavity of an ultrasonic transducer. Remaining layers may form a membrane of the ultrasonic transducer.

主权项

1. A method, comprising:
forming an acoustic membrane of an ultrasonic transducer in a complementary metal oxide semiconductor (CMOS) wafer by stacking multiple layers of the CMOS wafer including at least one dielectric layer, a first metallization layer and a second metallization layer of the CMOS wafer; forming at least one access hole to the first metallization layer of the CMOS wafer, the first metallization layer comprising an inner metal layer bounded by first and second conductive liner layers; forming a cavity in the CMOS wafer by removing at least a portion of the inner metal layer of the first metallization layer through the at least one access hole using a selective etch, thereby releasing the acoustic membrane while substantially retaining the first and second conductive liner layers, wherein the first conductive liner layer is disposed between the cavity and a semiconductor substrate of the CMOS wafer, and the second conductive liner layer is disposed in the acoustic membrane between the cavity and the second metallization layer; sealing the at least one access hole with an insulating material; and coupling the first and second conductive liner layers to integrated circuitry of the CMOS wafer.