High-sensitivity CMUT with interlayer metal architecture for medical ultrasonic systems

This paper presents an integration of the capacitive micromachined ultrasonic transducers (CMUTs) and the transimpedance amplifier in medical ultrasound systems. The proposed CMUT and the sensing circuits are both fabricated on the same chip in a 0.18μm CMOS MEMS technology. Two interlayer metal structures are proposed to improve the sensitivity. The CMUTs are designed with 2MHz cells for medical diagnosis. The conversion efficiency of the CMUTs is 4 times and 1.8 times higher than that in the published structures.