Capacitive Micromachined Ultrasonic Transducer (CMUT) with Different Insulation Layer Size

Parasitic capacitance has adverse effect on capacitive micromachined ultrasonic transducer (CMUT) performance. Reduction of parasitic capacitance, therefore, is essential for high performance CMUT device. Isolation layer between two electrodes of CMUT is one of parasitic capacitance source and used to prevent short connection during operation. Aim of this study is to show effect of insulation layer size on device performance. Partial insulation layer size rather than 100% coverage is investigated on device membrane displacement, capacitance, electromechanical coupling coefficient and transformer ratio. Three different partial insulation layer size used for calculation. These are 25%,50% and 75% of full coverage. Results of partial insulation layer size were compared to full coverage of insulation layer. It was concluded that reducing insulation layer can improve CMUT performance when short connect between electrodes is prevented.