High-density microwave plasma of SiH4/H2for high rate growth of highly crystallized microcrystalline silicon films

Abstract

The plasma parameters for the fast deposition of highly crystallized microcrystalline silicon ( µ c-Si) films with low defect density are presented using a high-density and low-temperature SiH 4 -H 2 mixture microwave plasma. A very high deposition rate of 65 A/s was achieved for a SiH 4 concentration of 67% diluted in H 2 with a high Raman crystallinity I c / I a > 2.5 and a low defect density of 1−2 × 10 16 cm −3 by adjusting the plasma conditions. Contrary to the case of a conventional rf plasma, the defect density of the µ c-Si films strongly depends on substrate temperature, T s , and increases with increasing T s even if T s is below 300 °C. This indicates that the real temperature at the growing surface is higher than the monitored value. A sufficient supply of deposition precursors such as SiH 3 at the growing surface under an appropriate ion bombardment is effective for the fast deposition of highly crystallized µ c-Si films as well as for the suppression of the amorphous incubation and transition interface layers at the initial growth stage.