The synergistic roles of temperature and pressure in thermo-compression bonding of Au

Abstract Au-Au thermocompression bonding is a widely used technique for a variety of applications including hermetic sealing and packaging at a fine pitch. We have investigated the roles of pressure and temperature individually at different pressures (15 -100 MPa) and temperatures (150 and 250° C) of sputter deposited 1.2 μm thick Au thin films using a flattening technique. The initial surface root mean square (RMS) roughness of deposited films was 3-5 nm. Void morphology and the evolution of the interface was studied using atomic force microscopy. Power spectral density function plots were used to study variation in asperities at the surface. The void morphology and evolution was different when flattening and bonding at different temperatures and pressures.