Determination of the phosphorus content of doped SiO₂films by IR absorption and activation analysis

Abstract

The phosphorus concentrations of P-doped SiO2 films deposited on to Si wafers by pyrolysis have been determined by activation analysis and using the data of diffusion layer prepared by the doped SiO2 film in the Si substrate. Using these P concentrations and the P=O infrared (IR) absorption bands of the films the constant K' of the IR P determination has been calculated. Inversely, measuring the IR absorption band corresponding to the P=O groups and knowing the constant K' can give estimates of the surface concentration of the diffusion layer prepared by the SiO2 diffusion source and the p-n junction's depth. The values of the constant K'; for SiO2 films doped by triethylphosphate and POCl3 are significantly different, explained by the difference in the ratio of the concentration of P=O bonds to the concentration of P atoms for the two doping materials.