Design Of Capacitive Ultrasonic Transducer (CMUT)

The sensor market is still dominated by the piezoelectric ceramic sensor (PZT),but ithas some natural defects such as impedance mismatch and so on. Therefore, it requires usto study a new sensor to replace the PZT so that it will be more suitable to our needs;Withthe development of science and technology,the application of ultrasound is increasing sofast,including ultrasound diagnosis, nondestructive testing and so on.The core device in avariety of ultrasonic applications is also the ultrasonic sensor (CMUT), so this will furtherincrease the necessity and urgency of our research for the ultrasonic sensors.In this paper, we study the structural performance of CMUT design mainly based onthe standard CMOS process. Because the design for the CMUT structure is under theresearch and development stage, we focused on the CMUT simulation and theexperimental testing.Firstly, we propose a specific CMUT structure and the correspondingcircuit design under the requirements of the standard CMOS process. Then the staticanalysis simulation for the CMUT is investigated to meet our performance requirements.Consequencely we found that the structure with specific dimensions can achieve ourdesign requirements. But until now we also need to consider other factors, such as residualstress effect on the CMUT performance and the fatigue life of the CMUT, In the analysisprocess the finite element analysis software ANSYS, FE-SAFE is used. Secondly, after wehave a good simulation result for the CMUT and flow sheet to change our design intoproducts.In addition we use the candance for layout and then sent it to a special processingcompany for some post-processing，then we will get the final product.Unfortunately, we found out that the CMUT can not meet our requirements. And thereason may be the existence of adhesion between the film, so in the end of the paper wehave put forward specific solution for the thin-film adhesion for the follow-up study.