Assessing the Microfabrication-Related Variability of the Performance of CMUT Arrays

This paper addresses the assessment of the variability of CMUT arrays’ electro-mechanical and acoustic performance, as related to the tolerance of the CMUT vertical dimensions due to the microfabrication process. A 3-factors 3-levels factorial sensitivity analysis is carried out to compute the main effects and the interaction effects of the moving plate thickness, the passivation layers thickness, and the sacrificial layer thickness, on the CMUT resonance frequency, collapse voltage, and static capacitance, as well as on the transmission and reception sensitivity amplitude and bandwidth and time delay in water-coupled condition. The analysis is performed by means of FEM simulations of the CMUT static behavior and dynamic response, and the findings are compared to experimental data.