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

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, SiO
2
was deposited on diamond surface and used as intermediate layers for bonding. Results shows that the warpage and shape of SiO
2
/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.