High-density microwave plasma of SiH₄/H₂ for high rate growth of highly crystallized microcrystalline silicon films

Department of Functional Materials Science, Graduate School of Science and Technology, Saitama University, 255 Shimo-Okubo, Sakura, Saitama 338-8570, Japan

Corresponding author: jiahaijunlz@hotmail.com

Received: 20 June 2005
Revised: 14 October 2005
Accepted: 17 October 2005
Published online: 22 February 2006

Abstract

The plasma parameters for the fast deposition of highly crystallized microcrystalline silicon (µc-Si) films with low defect density are presented using a high-density and low-temperature SiH₄-H₂ mixture microwave plasma. A very high deposition rate of 65 Å/s was achieved for a SiH₄ concentration of 67% diluted in H₂ with a high Raman crystallinity I_c/I_a > 2.5 and a low defect density of 1−2 × 10¹⁶ cm⁻³ by adjusting the plasma conditions. Contrary to the case of a conventional rf plasma, the defect density of the µc-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 SiH₃ at the growing surface under an appropriate ion bombardment is effective for the fast deposition of highly crystallized µc-Si films as well as for the suppression of the amorphous incubation and transition interface layers at the initial growth stage.