Low Temperature Bonding Polycrystalline Diamond to Si by Using Au Thin-layer for High-power Semiconductor Devices

As the semiconductor devices are getting higher frequency, higher power and smaller size, the management of thermal dissipation becomes a big challenge. The application of diamond as heat dissipation substrate for high-power semiconductor devices has been placed great expectation due to its ultra-high thermal conductivity. In this study, Au thin layer was used for the low temperature bonding of polycrystalline diamond and Si. The Au-Au atomic diffusion bonding was successfully achieved. Clean processes were optimized. Scanning acoustic microscope (SAM) was used to determine the bonding porosity, which typically exceeded 10%. Atomic force microscope (AFM) tests indicated the diamond surface roughness (Ra>1nm). The poor surface flatness of diamond contributed to the degradation of bond-ability. The technological route of diamond heat dissipation substrate for high-power semiconductor devices needs more optimization.