Wafer Level Fabrication of cMUT using Bonding and Interconnection Technique without TSV/TGV

The paper presents a wafer-level fabrication of a capacitive micromachined ultrasonic transducer (cMUT) using a wafer bonding process and interconnection technique without through silicon vias (TSV)/through glass vias (TGV) process. Anodic bonding technique is utilized for the fabrication and bottom electrode connections are taken by etching the structural layer of Silicon and silicon dioxide. The developed approach is reliable, repeatable and suitable for integration. An element having an array of 125 circular cMUT cell is reported having center frequency of 4.4 MHz.