Influence of substrate bias on the composition of SiC thin films fabricated by PECVD and underlying mechanism

The influence of the substrate bias on the composition of SiC thin films synthesized by plasma-enhanced chemical vapor deposition was studied. Our results indicate that the ratio of Si to C in the thin films is almost stoichiometric at a bias of − 300 V, whereas excessive carbon is observed in the films if the bias is lower or higher. Very little oxygen can be detected in the film produced without biasing. The effects of the bias on the composition of the thin films can be attributed to the interaction between the positive ions in the plasma and the surface atoms. The underlying mechanism is also discussed.