Surface reaction of hydrogen radical on plasma enhanced chemical vapor deposition of silicon thin films

摘要

Hydrogen (H) radicals have a significant role in the silicon film deposition for solar cell applications. It is important to recognize the behavior of H radicals in silane (SiH_4) and hydrogen molecule (H_2) plasma to fabricate high quality silicon films. In this study the absolute density and decay time constant of H radical in SiH_4/H_2 plasma were measured by using vacuum ultraviolet absorption spectroscopy. The surface loss probability was estimated from measured decay time constant. The H radical density in the plasma decreased 4.3 × 10~(12) to 6.8 × 10~(11) cm~(-3) and the surface loss probability increased 0.01 to 0.32 with increasing SiH4 flow rate from 0 to 3 sccm. It indicates that the radical density in the plasma strongly depend on the wall conditions.