Plasma Etching for Backside Wafer Thinning of SiC

Abstract

In this initial phase of work, two methods of backside wafer thinning using ICP plasma etching of two-inch SiC substrates have been considered. Plasma processes were optimized for nonbonded and bonded wafers. The non-bonded process was used to etch 250μm thick substrates to a final thickness of 100μm. The bonded process was used to etch glass bonded SiC substrates mechanically ground to 130μm thick and plasma etched to a final thickness of 100μm. Etch rate measurements and surface analysis were performed using a profilometer and white light interferometry. Etch rates of 3.4μm/min were achieved for the bonded process and 2.0μm/min for the non-bonded process. The surface morphology for the non-bonded process was three to four times lower than the bonded process. The part mechanically ground samples showed evidence of surface damage from the grinding process after plasma etching.