Plasma etching for backside wafer thinning of SiC

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 250 mu m thick substrates to a final thickness of 100 mu m. The bonded process was used to etch glass bonded SiC substrates mechanically ground to 130 mu m thick and plasma etched to a final thickness of 100 mu m. Etch rate measurements and surface analysis were performed using a profilometer and white light interferometry. Etch rates of 3.4 mu m/min were achieved for the bonded process and 2.0 mu m/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.