Mechanical properties and plasma etching resistance of B4C–CNT composites fabricated by spark plasma sintering

High-density boron carbide (B 4 C)-carbon nanotube (CNT) ceramic matrix composites were fabricated for semiconductor plasma etching applications. Although B 4 C is widely recognized for its exceptional hardness, its practical implementation is limited by severe surface cratering during plasma etching. In this study, CNTs (0.5-2.0 wt.%) were incorporated into the B 4 C matrix and consolidated using spark plasma sintering. Beyond conventional toughening effects, the CNT-reinforced composites exhibited a distinct surface-stabilization behavior under CF 4 /Ar/O 2 plasma exposure. Compared with monolithic B 4 C, the composites showed significantly reduced etch rates. Surface analyses further revealed that CNTs act as structural anchoring sites that suppress ion-bombardment-induced crater formation in B 4 C ceramics. Among the investigated compositions, the composite containing 1.0 wt.% CNT exhibited the optimum combination of properties, achieving a relative density of 99.57%, a hardness of 36.84 GPa and a fracture toughness of 5.71 MPa·m 1/2 , with both mechanical properties obtained under an indentation load of 9.8 N. In addition, it showed the lowest etch rate (3.58 nm/min) and the smallest increase in surface roughness (7.8%) after plasma exposure. The CNT-induced structural anchoring effectively suppressed plasma-induced crater formation and surface degradation. These results highlight the potential of CNT-reinforced B 4 C composites as promising plasma-resistant ceramics for advanced semiconductor fabrication environments.