Corrosion resistance of sintered SiC against fluorinated plasmas

Abstract

α-SiC fabricated by the sintering method was developed as an alternative to the widely used β-SiC made by chemical vapor deposition for various functional components used in the plasma process chamber. By adapting the sintering method, larger and thicker SiC components can be fabricated practically compared with the chemical vapor deposition. Two sintering additives, Y2O3-Al2O3 and B4C, were used in the sintering processes, and the etching stability of sintered SiC against fluorinated plasmas, including SF6/Ar plasma and CF4/O2/Ar plasma, was investigated. For sintered SiC with Y2O3-Al2O3 additives, the etching rate was smaller than that of the chemical-vapor-deposited SiC, mainly because nonvolatile fluoride and/or oxides of Y and Al remained on the surface and served as a protective layer. For sintered SiC, the B4C additives, the etching rate, and the surface structure after plasma irradiation were similar to the case of the chemical-vapor-deposited SiC. The results suggest that the B4C additive has little effect on the etching stability, because fluorides of B and C are volatile, and no residue is formed, contrary to the case of the Y2O3-Al2O3 additives.