Cost-Effective Strategy for Developing Small Sized High Frequency PMUTs Toward Phased Array Imaging Applications

This article presents the development of small sized piezoelectric micromachined ultrasound transducer (PMUT) with cost effective fabrication process. Improved imaging quality requires sized, high frequency and performance PMUT cell further density arrays. Fabrication currently well developed sacrificial process benefits their mass production application. To determine AlN cell, commonly reported elastic layer materials including Si, Si3N4, SiO2 are compared by mathematic derivation under same stack thickness device frequency. has smallest Young modulus it serving as can yield expected one. Arranging at top is compatible phosphor silicate glass (PSG) manufacturing for fabrication. strategy downsizes size since extra protection omissible. We make 12MHz linear arrays diameter, element pitch to be $40~\mu \text{m}$ , notation="LaTeX">$1.9~\mu notation="LaTeX">$120~\mu . Their electrical results quite uniform both wafer levels. One line 20 parallelly connected units produce pulse-echo signal over 25dB SNR 10mm distance. Lateral axial resolutions ~1 mm ~0.3 obtained in practical verification. These indicate good our array. Plus advantages fabrication, using arranging a competitive develop phased array PMUTs. [2022-0184]