Finite element modeling of a capacitive micromachined ultrasonic transducer

Capacitive micromachined ultrasonic transducers have been investigated using finite element analysis. Three ANSYS models have been developed to illustrate the collapse voltage and operating frequency of CMUTs. A 2D axisymmetric model is used to illustrate the relationship between collapse voltage and electrode radius. The model agrees with past results for electrode radius sizes between full membrane radius and half membrane radius. A 3D solid model is utilized to demonstrate the resonant frequency of the CMUT silicon nitride membrane. A reduced order model is also used to depict the resonant frequency. Both models demonstrate a resonant operating frequency around 2.3 MHz for a membrane with a radius of 50 microns, a thickness of 1 micron, a residual stress of 60 MPa (tension) and biased at 30 V/sub DC/. The results are validated using previously reported findings.