Designing SiC Based CMUT Structures: An Original Approach and Related Material Issues

Abstract

We present an epitaxy-based approach for realizing a 3C-SiC Capacitive Micromachined Ultrasonic Transducer (CMUT). The design requires to grow a 3C-SiC/Si/3C-SiC heterostructure on a Si substrate. This requires different growth steps of SiC on Si and Si on SiC. We present some specific growth related issues, namely the control of selectively grown Si on a masked SiC(100) layer and the further regrowth of 3C-SiC on a Si(110) layer. The final release of the SiC membrane, to define a CMUT, is also presented using a simple thermal treatment to reduce the total number of technological steps.