A study of the growth kinetics for plasma-enhanced oxidation in an electrodeless RF system based on an earlier design is presented. Oxidation growth rates and thickness uniformity variations across 75 mm diam wafers for various plasma parameters are given. The time-dependence of the grown oxides were found to fit a power law model. Other parameters investigated include RF frequency in the range 6-21 MHz, RF power from 100-500 W, chamber pressure from 85 to 500 mtorr, and oxygen in argon concentration in the plasma from 1 to 100% oxygen. The etch rate of the plasma oxide in 10:1 buffered oxide etch was found to be comparable to that of thermally grown oxides. Defect levels (net coulombic charge) and breakdown values for postoxidation-annealed oxides were measured initially with poly-gated capacitors, prior and subsequent to post-poly anneal. Defect levels and breakdown values for postoxidation annealed oxides were also obtained with aluminum-gated capacitors, with thermal oxides used'as "controls" and subjected to the same annealing treatments. It was found that those oxides which had received a postoxidation anneal in oxygen at 1000~ for 15 rain were comparable to the thermal "controls" in defect level density and electric breakdown integrity.

This study discusses the sign of the charge of the gas phase species involved in the plasma oxidation of silicon and the oxidation mechanism itself in a system of a type previously reported in which oxidation occurs on a silicon surface facing. away from a confined plasma. Based on grid-biasing experiments, it was found that the gas-phase oxygen species responsible for oxidation are positively charged, in marked distinction to what has been proposed for plasma anodization processes. From 0 TM and Si 3~ double-marker experiments, coupled with other information, the oxidation process was found to proceed by oxygen ion transport to the Si-SiO2 interface with no outdiffusion of silicon being detected.