Gold-indium Transient Liquid Phase (TLP) wafer bonding for MEMS vacuum packaging

This paper reports the first wafer-level vacuum packages created with gold-indium transient liquid phase (TLP) wafer bonding. The packages were bonded at 200degC for 1 hour under a vacuum environment in a commercially available wafer bonder. After bonding, the integrated getters were activated for 1 hour resulting in internal pressures as low as 200 mTorr. The pressures have been stable for over 6 months as measured by integrated Pirani gauges. Although no leak rate trend has been observed, the worst case leak rate that fits within the error of the pressure measurement is 16 mTorr/year (1ldr10^-16 atm.cc.s^-1).