Makio Iida

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.

Investigation of Reoxidation and Phosphorus Behavior in HF-Treated Heavily Doped Silicon Surfaces

The thermally stimulated desorption (TSD) from aqueous HF-treated heavily phosphorus-doped Si(100) and polycrystalline Si surfaces was studied by Auger electron spectroscopy (AES), electron energy loss spectroscopy (EELS) and mass spectroscopy. Desorption analyses indicated that reoxidation takes place slightly, to the same extent in the doped Si(100) and polycrystalline Si surfaces owing to hydrogen desorption. Moreover, a large quantity of phosphorus segregates to the top few layers in the desorption process of the oxides. It was clarified that the HF-treated polycrystalline silicon surface is terminated by hydrogen and resists oxidation similarly to a single-crystal one.