Suppression of Dust Particle Contamination in a SiH₄/H₂ Plasma CVD Reactor Using a New Type of Modulated Plasma

Abstract

A new type of plasma modulation is proposed to suppress dust particle contamination in a thin-film fabrication process using a radio frequency plasma enhanced CVD reactor. The performance of the modulation, sine-wave modulation, in reducing dust particle generation and deposition is studied experimentally for an a-Si film fabrication process using SiH₄/H₂. The sine-wave modulation realizes a drastic reduction of the number density and the size of dust particles suspended in plasma, as well as the previously-proposed pulse-wave modulation. However, the sine-wave modulation reduces particle deposition on the films much better than the pulse-wave modulation, owing probably to a better stability of plasma. In addition, the smoothness of the film surfaces is not affected by the plasma modulation. Therefore, the sine-wave modulation is considered to be a useful and practical method to fabricate thin-films with less particle contamination.