Plasma Parameters for Fast Deposition of Highly Crystallized Microcrystalline Silicon Films Using High-Density Microwave Plasma

Abstract

We have studied microcrystalline silicon (µc-Si) film growth using a high-density, low-temperature microwave plasma (MWP) of a SiH4–H2 mixture for fast deposition of highly crystallized µc-Si films with low defect density. A very high deposition rate of ∼65 Å/s has been achieved at a SiH4 concentration of 67% diluted by H2 with a high Raman crystallinity of Ic/Ia>3 and a low defect density of (1–2)×1016 cm-3 by adjusting the plasma condition. In contrast to the case of a conventional rf plasma, the defect density of the µc-Si films strongly depends on substrate temperature, Ts, increasing with Ts even at a Ts below 300°C. This suggests that the real surface temperature at the growing surface was higher than the monitored value. A sufficient supply of deposition precursors, such as SiH3, at the growth surface under an appropriate ion bombardment was effective for the fast deposition of highly crystallized µc-Si films as well as for the suppression of the incubation and transition layers at the initial growth stage.