Fabrication of Capacitive Micromachined Ultrasonic Transducer Arrays Using Glass Reflow Process and Anodic Bonding

N.V. Toan, S. Hahng, Y. Song, T. Ono
Tohoku University,

Keywords: capacitive micromachined ultrasonic transducer, glass reflow process, anodic bonding


This paper presents a process for the fabrication of vacuum-sealed capacitive micromachined ultrasonic transducer (CMUT) arrays using glass reflow and anodic bonding techniques. The silicon through-wafer interconnects have been investigated by glass reflow process. Then, the patterned silicon-glass reflow wafer is anodically bonded to an SOI (silicon-on-insulator) wafer for the fabrication of CMUT devices. The CMUT 5 x 5 array has been successfully fabricated. The resonant frequency of the CMUT array with a one-cell radius of 100 ┬Ám and sensing gap of 3.2 um (distance between top and bottom electrodes) is observed at 2.83 MHz. The Q factor is approximately 1300 at vacuum chamber pressure of 0.01 Pa.