Evaluation of the initial oxidation of heavily phosphorus doped silicon surfaces using angle-dependent X-ray photoelectron spectroscopy

Abstract The room temperature oxidation of heavily P-doped Si(100) and poly-Si prepared by HF-treatment has been monitored for a period of about 1 year, using angle-dependent X-ray photoelectron spectroscopy (XPS) and atomic force microscope (AFM), Immediately after HF-treatment, the P/Si atomic ratio increased with decreasing the photoelectron take-off angle, which implies that the more segregated-P existed in near the top surface region. The amount of activated Si, whose binding energy of Si2p was lower by 0.5 eV referred to that of lattice Si related to the amount of segregated-P closely. In the case of the P-doped samples, the chemical composition of the growing oxide films showed that not the Si ++ but the Si 3+ state was the dominant component until the oxide thickness, d , went up to over ~1.5 nm, while the Si 4+ was the major species for the moderately doped Si(100) and nondoped poly-Si, except in the very initial oxide ( d ). In contrast to the smooth AFM image of the moderately doped Si(100) surface, the heavily P-doped Si(100) showed very unique geometrical pattern.