Room temperature bonding of GaN on diamond wafers by using Mo/Au nano-layer for high-power semiconductor devices

For overcoming the heat dissipation problem of GaN-based high-power semiconductor devices, GaN wafers were bonded on polycrystalline and single-crystalline diamond wafers by using Mo/Au nano-layer at room temperature. Mo/Au double layers (~5 nm/11 nm) were deposited on the surfaces of GaN and diamond wafers. The scanning acoustic microscope (SAM) analyzation and tensile strength testing results show that a low voidage of ≤1.5% can be obtained for Mo/Au nano-layer, along with a bonding strength of 6.8 MPa. In addition, the thermal-impact-resistance performance was evaluated with thermal cycling testing.