Compensation of the Warpage of CVD Diamond Wafers using Intermediate Layers for Surface Activated Bonding

Abstract

4 inch polycrystalline CVD diamond wafers were bonded to single crystalline oxide wafers by modified surface activated bonding (SAB). To compensate the warpage of diamond wafers, SiO2 was deposited on diamond surface and used as intermediate layers for bonding. Results shows that the warpage and shape of SiO2/diamond wafers influenced the bonded area greatly. For the convex shaped wafer, when the Peak-to-valley (Pv) value was smaller than 4 um, at least 50% of the surface could be bonded; while the Pv exceeded 7 um, the bonding failed. Compared with the saddle shape, convex shaped wafers tended to be bonded easily. Finally, 85% bonded area was achieved. SEM and STEM images demonstrates that the interface was uniformly bonded without any nano-voids.