Nickel-Tin Transient Liquid Phase (TLP) Wafer Bonding for MEMS Vacuum Packaging

This paper reports vacuum data for nickel-tin transient liquid phase (TLP) wafer bonding. Two wafers, one with a titanium getter and another with Pirani vacuum sensors, were bonded for 1.5 hours at 300 °C. Initial pressures were as low as 200 mTorr and have remained stable for half a month. After several days, some of the packages were heated to 400 °C for 10 minutes to test the thermal integrity of the TLP bond. The bond remained intact; the pressure inside each of the cavities dropped by further activating the getter and has remained steady at the new lower pressure for several weeks.