Hermetic Cavities Using Gold Wafer Level Thermocompression Bonding

This paper presents the study of gold/gold thermocompression bonding at silicon wafer level. The first samples contains sealing rings and electrical pads, and are characterized on pull, and shear test showing bond strength similar to silicon/glass anodic bonding (10 MPa–80 MPa). A sealed cavity and a piezoresistor on a 30 µm-thick silicon membrane are added in the second samples. Helium test, membrane deflection and piezoresistor signal monitoring after aging 14 days at 250 °C confirm the vacuum stability inside the cavity after bonding