Effect of underlying silicon film on the evolution of microstructure and hardness of the high-temperature annealed carbon film on Si substrate

Effects of an amorphous silicon underlayer on the evolution of microstructure and hardness of an amorphous carbon film annealed at 900 °C for 0.5-1.5 h were investigated. The two-layer carbon/silicon film after annealing resulted in higher sp²/sp³ bonding ratio but lower hardness reduction compared to the single carbon film at the same total film thickness. The improved hardness reduction of the high-temperature annealed carbon film is attributed to the formation of polycrystals of the amorphous silicon together with the residual compressive stress of the two-layer C/Si films.