Small warpage dielectrically isolated wafer for power ICs by silicon wafer direct-bonding

Abstract

The warpage mechanism was investigated for dielectlically isolated wafers, fabricated by the direct bonding. Three factors affecting the warpage were revealed. They were elastic deformation, a phenomenon peculiar to the direct bonding and poly-Si deposition. The investigation on these factors reduce the warpage to a few microns for 3 inch diameter wafers. Six inch diameter wafers were directly bonded to obtain 5 inch diameter SO1 wafers. The warpage for the SO1 wafer was 13 to 34 p. These results show that a 5 inch dielectlically isolated wafer can be applicable t o power IC fabrications.