Balancing reinforcement and etch stability: SiC whisker effects in plasma-exposed AlN ceramics

AlN-based ceramics are a candidate for plasma-facing parts in semiconductor process chambers due to their high thermal conductivity and good electrical properties; however, improving their durability under aggressive fluorocarbon plasmas remains a key challenge. In this study, silicon carbide whisker (SiC w ) reinforced aluminum nitride (AlN) ceramics containing 5 wt% yttria (Y 2 O 3 ) and 0, 5, 10, 15, 20 and 30 wt% SiC w were synthesized by hot-press sintering and their microstructure, mechanical properties, and plasma etch resistance were analyzed. Increasing SiC w content improved the AlN microstructure while maintaining near-full densification, resulting in a monotonic improvement in Vickers hardness from around 10.3 to 14.4 GPa. Phase analysis confirmed AlN as the dominant phase with retained SiC and minor yttrium-aluminate (YAM) secondary phases, with no detectable bulk phase change after plasma exposure. Plasma durability was assessed under CF 4 /O 2 /Ar inductively coupled plasma reactive ion etching (ICP-RIE) (600 W ICP, 300 W bias, 120 min). Etch depth and etch rate exhibited a non-monotonic dependence on SiC w content, with the minimum etch depth (∼8.98 μm) and lowest etch rate (74.8 nm/min) achieved at 10 wt% SiC w , accompanied by comparatively smooth etched surfaces. In contrast, higher SiC w loadings (20-30 wt%) produced pronounced roughening and localized interfacial attack, leading to increased etch depth, etch rates, and surface roughness. Raman spectra of etched surfaces revealed AlN and SiC vibrational bands along with carbon-related features, indicating complex plasma-induced surface chemistry. These results demonstrate that ∼10 wt% SiC w provides the best balance between mechanical strengthening and fluorocarbon plasma etch resistance in AlN-based composites under the investigated conditions.