Effects of process parameters on the properties of silicon oxide films using plasma enhanced chemical vapor deposition with tetramethoxysilane

Thin oxide films are deposited from tetramethoxysilane (TMOS) with some addition of O2O2 (or N2ON2O) gas in inductively coupled plasma (ICP) discharges supplied with radio frequency power. The effects of various deposition parameters such as O2O2 (or N2ON2O) partial pressure ratio, ICP power, and gas pressure on the growth characteristics and properties of the deposited films are investigated. The chemical bonding states of deposited films are analyzed by Fourier transform infrared spectroscopy, and the deposition rate and optical properties are determined from in-situ ellipsometry. For the TMOS/O2TMOS/O2 case, the deposition rate increases with increasing ICP power. Larger oxygen partial pressure ratio decreases the deposition rate. For the TMOS/N2OTMOS/N2O case, higher N2ON2O fraction results in a decrease in nitrogen content in the gas-phase and in the deposited films, thereby decreasing the refractive index. As the gas pressure increases, the deposition rate increases first and saturates later. Capacitance–voltage measurements are performed in MOS capacitors to obtain the electrical properties of the deposited films. The interface trap density is observed to decrease with increasing ICP power.