Capacitive micromachined ultrasonic transducer (CMUT) devices are becoming increasingly popular in medical applications. For example, CMUT devices have been used to improve medical ultrasound imaging probes. CMUT devices have also been used to provide high-intensity focused ultrasound for use in medical therapy. Conventional CMUT devices are typically produced directly on a silicon substrate. For instance, conventional CMUT devices are often fabricated using a micro-electro-mechanical system (MEMS) manufacturing technique in which a release layer is etched out, leaving a free-standing membrane. The membrane is then used to transmit and receive ultrasonic signals.