Wafer-bonded 2-D CMUT arrays incorporating through-wafer trench-isolated interconnects with a supporting frame

摘要: This paper reports on wafer-bonded, fully populated 2-D capacitive micromachined ultrasonic transducer (CMUT) arrays. To date, no successful through-wafer via fabrication technique has been demonstrated that is compatible with the wafer-bonding method of making CMUT As an alternative to vias, trench isolation a supporting frame incorporated into arrays provide electrical connections. The are built silicon-on-insulator (SOI) wafer, and all connections array elements brought back side wafer through highly conductive silicon substrate. Neighboring separated by trenches both device layer bulk silicon. A mesh structure, providing mechanical support, embedded between pillars, which electrically connect individual elements. We successfully fabricated 16 times 16-element using bonding yield 100%. Across array, pulse-echo amplitude distribution uniform (sigma = 6.6% mean amplitude). In one design, we measured center frequency 7.6 MHz, peak-to-peak output pressure 2.9 MPa at surface, 3-dB fractional bandwidth 95%. Volumetric ultrasound imaging was chip-to-chip custom-designed integrated circuit (IC). study shows trench-isolation viable solution for interconnects deliver good performance.