Deposition of silicon dioxide films with a non-equilibrium atmospheric-pressure plasma jet

Silicon dioxide films were grown using an atmospheric-pressure plasma jet that was produced by flowing oxygen and helium between two coaxial metal electrodes that were driven by 13.56 MHz radio frequency power. The plasma exiting from between the electrodes was mixed with tetraethoxysilane (TEOS), and directed onto a silicon substrate held at 115-350 °C. Silicon dioxide films were deposited at rates ranging from 20±2 to 300±25 nm min^-1. The deposition rate increased with decreasing temperature and increasing TEOS pressure, oxygen pressure and RF power. For the latter two variables, the rate increased as follows: Rd∝P^0.3_O2(RF)^1.4. Films grown at 115 °C were porous and contained adsorbed hydroxyl groups, whereas films grown at 350 °C were smooth, dense and free of impurities. These results suggest that the mechanism in the atmospheric pressure plasma is the same as that in low-pressure plasmas.