Selective Masking Effects of WO3 Resist on Impurity Diffusion and Oxidation in Silicon

Abstract
Selective masking effects of a WO3 electron resist on phosphorus diffusion and oxidation in silicon at 1000°C are described. Though the diffusion coefficient of phosphorus in the WO3 layer is about twice as large as that in the SiO2 layer, the WO3 resist is useful as a masking film for phosphorus diffusion at elevated temperatures around 1000°C. On the other hand, the masking effect of the WO3 layer on the oxidation of a silicon substrate is insufficient, since the diffusion coefficient of O2 molecules in the WO3 layer is about eight times as large as that in the SiO2 layer.