Etching Rate Behavior of 4H-Silicon Carbide Using Chlorine Trifloride Gas

Abstract

Dry etching of 4H-silicon carbide (SiC) is studied using chlorine trifluoride gas at 673-973K and atmospheric pressure in a horizontal reactor. The etch rate of C-face and Si-face of 4H-SiC can be greater than 10 um/min at substrate temperatures higher than 723 K. The etch rate of Si-face is lower than that of C-face. The etch rate increases with the chlorine trifluoride gas flow rate. The etched surface of Si-face shows many pits having a hexagonal edge shape and tends to be rough. However, the C-face maintains a very smooth surface after the etching. The average roughness of the etched surface tends to be low at the higher temperatures. The etch rate behavior is discussed from the view points of the transport phenomena in the reactor and the chemical process at the substrate surface; their rate constants are obtained.