(Invited, Digital Presentation) Low-Temperature Direct Bonding of Wide-Bandgap Semiconductor Substrates

Abstract

For the next-generation semiconductor devices, our research group has developed direct bonding techniques of wide-bandgap materials, including SiC, Ga2O3, and diamond. It is known that the semiconductor substrates activated by oxygen plasma can form atomic bonds at low temperatures. In this case, a thick oxide layer, which may become a thermal and electrical barrier, is formed at the bonding interface. Meanwhile, our research group demonstrated that the OH-terminated Ga2O3 and diamond substrates were directly bonded without an oxide intermediate layer. In addition, the SiC substrate dipped into the HF acid can be bonded with the Ga2O3 substrate with an ~1-nm-thick amorphous layer. The dissimilar substrates bonded through the ultra-thin intermediate layer would contribute to efficient heat dissipation and future heterojunction devices.