Effects of High-Temperature Vacuum Annealing on the Microstructure, Mechanical Properties, and Plasma Etching Resistance of Bulk CVD-SiC

Bulk chemical vapor-deposited silicon carbide (CVD-SiC) requires high mechanical strength and plasma etching resistance for semiconductor process components. This study investigated the effects of vacuum annealing at 1400, 1800, and 2000 °C for 1 h on its morphology, composition, crystallographic characteristics, mechanical properties, and CF4/O2 plasma etching behavior. Scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, flexural testing, and density measurements were performed. The 3C-SiC phase remained dominant under all investigated conditions. At 1800 °C, the mean projected image-area fraction of pit-like features and the (111) peak full width at half maximum reached their minimum values of 0.48% and 0.1137°, respectively. Flexural strength increased by 74.3%, from 427.4 to 744.8 MPa, while density varied little. The surface Si/C atomic ratio decreased from 1.007 to 0.547 with increasing temperature. Mean cumulative mass loss after plasma etching decreased by 19.9%, from 0.1051 g for untreated specimens to 0.0842 g at 1800 °C; the difference between 1800 and 2000 °C was not statistically significant. Annealing-induced changes in morphology, composition, and crystallographic state were associated with the observed property changes. Among the investigated conditions, annealing at 1800 °C provided the highest flexural strength and lowest mean plasma-etching mass loss.