THE EFFECTS OF TRICHLOROETHANE HCI AND ION-IMPLANTATION ON THE OXIDATION RATE OF SILICON

The thermal oxidation of silicon was studied using a large-scale industrial oxidation system. The characteristics of the oxides resulting from pure hydrogen/oxygen (H2/O2), trichloroethane/oxygen (TCA/02) and hydrogen chloride/oxygen (HCl/O2) mixtures are compared. Both HCI and TCA addition to oxygen produced an enhanced oxidation rate. The oxidation rate for TCA/O2 was approximately 30-40% higher than for HCl/O2 mixtures. A molar ratio of TCA/O2 of 1% gives an optimum process for very-large-scale industrial (VLSI) applications. However, 3% HCl/O2 gives comparable results to 1% TCA. In addition, boron and phosphorus implantation are observed to increase the oxidation rate. Phosphorus doping of the silicon yields a higher rate than boron-doped wafers. This behaviour is explained in terms of surface damage and chemistry. It appears that the overall mechanisms governing all these processes are similar.