The chemical composition changes of silicon and phosphorus in the process of native oxide formation of heavily phosphorus doped silicon

• Published in: Applied surface science 2001-09, Vol.181 (1), p.1-14
• Main Authors: Ying, W.B, Mizokawa, Y, Kamiura, Y, Kawamoto, K, Yang, W.Y
• Format: Article
• Language: English
• Subjects: Angle dependent X-ray photoelectron spectroscopy (XPS); Chemical states of Si; Composition; defects and impurities; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Heavily P-doped Si; Materials science; Native oxide; Oxidation; Phosphorus segregation; Physics; Solid surfaces and solid-solid interfaces; Surface chemistry of Si; Surface treatments; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties)
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/S0169-4332(01)00202-1

The chemical composition changes of silicon and phosphorus in the process of native oxide formation of both heavily phosphorus-doped Si(1 0 0) and polycrystalline Si prepared by HF-treatment were monitored for a period of 1 year, using angle dependent X-ray photoelectron spectroscopy (XPS). Right after HF-treatment, significant amounts of unoxidized-P (P ∗) and a new chemical state of Si (Si ∗) having an unstable bond were detected in the surface region of heavily P-doped Si. With decreasing depth, the concentration of P ∗ increased, whereas the Si ∗ decreased. The surface segregated P ∗ was larger for P-doped Si(1 0 0) than for P-doped poly-Si. During the growth of native oxide, the distributions of P ∗ and Si ∗ in the underlying Si surface did not change largely with oxide thickness. A part of P atoms also reacted with oxygen and incorporated into Si–O–P network in the native oxide, and the amount of P-oxide increased with the progress of oxidation. The decomposed Si 2p spectra of growing oxide films on both heavily P-doped Si showed that the dominant component was not the Si 4+, but Si 3+ state until the oxide thickness went up to over about 1.5 nm, while that for the low P-content Si was Si 4+, except at the very narrow interface.