Room-temperature bonding of single-crystal diamond and Si using Au/Au atomic diffusion bonding in atmospheric air

For developing a heat dissipation system for power devices, room-temperature bonding of a single-crystal diamond chip to a Si substrate was performed using the atomic diffusion bonding (ADB) method. The diamond chip was successfully bonded to the Si substrate using deposited Ti/Au (5/12 nm) intermediate layers. The bonding was so strong that the Si substrate was fractured during the shear test. The analysis of the fractured surface revealed that the bulk fracture within the Si substrate and plastic deformation of the Au intermediate layer occurred during the shear test instead of fractures at the Au/Au, Au/Ti, Ti/Si, and Ti/diamond interfaces. The TEM observation suggested that such strong bonding was attributed to atomic diffusion and grain growth across the Au/Au bonding interface and chemical reactions at Ti/Si and Ti/diamond interfaces. Because the deposited layers are extremely thin, an efficient thermal management system using a diamond heat spreader can be achieved at room temperature in atmospheric air using ADB. [Display omitted] •Diamond and Si were bonded using Ti/Au films at room temperature in atmospheric air.•Bulk fracture within Si and plastic deformation of Au occurred during shear test.•Au atomic diffusion enhanced strong bond formation and intimate contact at interface.•An efficient heat dissipation structure using diamond for power devices is expected.