Stoicheometry control of silicon oxide films by the reactive sputter deposition with constant power operation

Abstract

The mode transition of the DC reactive sputter deposition process has been studied for the fabrication and the stoichiometry control of SiO x films. At a fixed Ar flow rate of 20 sccm and a pressure of 1 Pa (hence the pumping speed was also fixed), oxygen flow rate was modified and the transition between the metal and oxide modes was monitored by the cathode voltage. With a constant current operation of a DC power source, well known steep and hysteretic mode transition appeared. On the other hand, gentler transition with no hysteretic character was observed in a constant power operation. In the latter case, the dependence of the deposited film composition on the oxygen gas flow rate was examined by X-ray photoelectron spectroscopy. The increase in the film composition x from 0.5 to 2.0 was observed in a smaller flow rate region compared to the process mode transition. It can be attributed to the non-uniform deposition of Si atoms which work as oxygen absorber.