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 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.
N. Wright, C.M. Johnson, K. Vassilevski, I. Nikitina and A. Horsfall
K. M. Robb, "Plasma Etching for Backside Wafer Thinning of SiC", Materials Science Forum, Vols. 556-557, pp. 729-732, 2007