Performance assessment of CMUT arrays based on electrical impedance test results

A quantitative quality assessment method for capacitive micromachined ultrasonic transducer (CMUT) arrays based on electrical impedance measurements made at wafer level is proposed. The resonant response in air of CMUTs is described and then used to obtain a quantitative quality value. Several issues that could occur in CMUT arrays as well as their effect on the output of the assessment are analyzed. This method has been applied on a wafer containing several CMUT designs and the obtained results are summarized.