Chlorine Trifluoride Gas Etching Design for Quickly and Uniformly Removing a Thick C-Face 4H-Silicon Carbide Layer

Abstract

A process and a reactor for the quick, uniform, and deep etching of a C-face 4H-silicon carbide layer were developed using chlorine trifluoride gas. Based on the concept that the etching rate profile of the rotating wafer was the average of that on a concentric circle, the uniform etching rate profile was obtained by the average between the multiple wavy etching rate profiles and by sufficiently spreading the chlorine trifluoride gas. The etching rate variation and RMS microroughness could be reduced to 1.6% and about 0.2 nm, when the etching rate and depth were 20 µm min-1 and about 100 µm, respectively. The developed process could etch off the 150 µm deep layer without deteriorating the RMS microroughness for the total etching time within 8 minutes.