SOI wafer fabricated with a diamond BOX layer using surface activated bonding at room temperature

Abstract

We propose a fabrication process for a silicon on insulator (SOI) wafer with a diamond buried oxide (BOX) layer by combining nanodiamond-seeding deposition and a surface-activated bonding technique for high-frequency and power device applications. The diamond layer was deposited on a base wafer by the spin-coating of nanodiamonds and microwave-plasma-enhanced chemical vapor deposition. The thermal conductivity of this deposited diamond layer was three times that of a conventional SiO2 layer. A silicon wafer was then bonded to the diamond layer at room temperature in ultrahigh vacuum without forming any voids. Additionally, this SOI wafer was used to fabricate devices at 1000 °C. Therefore, we believe that this SOI wafer with a diamond BOX layer and its fabrication process are important for the realization of self-heating devices such as next-generation high-frequency and power devices.