Low temperature bonding of diamond heat spreaders for advanced thermal management

Abstract Surface activated wafer bonding of Silicon (Si) to single crystal diamond (SCD) was performed on the EVG ComBond ® system with the goal of fabricating highly thermally conductive interfaces for advanced thermal management designs. AFM measurements were conducted which show the compatibility of SCD surfaces with ComBond ® . The interface of the bonded Si-SCD pairs was characterized by transmission electron microscopy which shows an amorphous layer with a thickness of around 3 nm at the bonding interface. Scanning acoustic microscopy shows a uniform bonding interface with minor pits. Time-domain thermoreflectance shows a Thermal Boundary Resistance of around 9.5 m 2 K GW −1 and pull strength tests show a bond strength of 55 MPa. Finite element analysis COMSOL ® thermal simulations highlight the efficiency of surface activated bonding for SCD as a heat spreader material, outperforming conventional methods like plasma activated fusion bonding with an intermediate SiO 2 layer or indirect bonding.