Thinning of 2-Inch SiC Wafer by Plasma Chemical Vaporization Machining Using Cylindrical Rotary Electrode
To reduce the on-resistance in vertical power transistors, backside thinning is required after device processing. However, it is difficult to thin a SiC wafer with a high removal rate by conventional mechanical machining because its high hardness and brittleness cause cracking and chipping during thinning. In this study, we attempted to thin a 2-inch 4H-SiC wafer by plasma chemical vaporization machining (PCVM), which is plasma etching using atmospheric-pressure plasma. By controlling the scanning speed of the table and optimizing the oxygen percentage in the CF4+O2+He mixture gas, a maximum removal rate of 0.56 μm/min was obtained over the entire wafer. Furthermore, the surface roughness was improved after thinning. Therefore, PCVM can be used as an effective method for thinning SiC wafers.
Edouard V. Monakhov, Tamás Hornos and Bengt. G. Svensson
Y. Sano et al., "Thinning of 2-Inch SiC Wafer by Plasma Chemical Vaporization Machining Using Cylindrical Rotary Electrode", Materials Science Forum, Vols. 679-680, pp. 481-484, 2011