Structure of ultrathin SiO{sub 2}/Si(111) interfaces studied by photoelectron spectroscopy

Journal Article · Thu Jul 01 04:00:00 EDT 1999 · Journal of Vacuum Science and Technology, A

DOI:https://doi.org/10.1116/1.581805· OSTI ID:359785

Keister, J W; Rowe, J E ^[1]; Kolodziej, J J ^[2]; Niimi, H ^[3]; Tao, H; Madey, T E ^[2]; Lucovsky, G ^[1]

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1. Department of Physics, North Carolina State University, Raleigh, North Carolina 27695-8202 (United States)
2. Department of Physics and Astronomy and Laboratory for Surface Modification, Rutgers University, Piscataway, New Jersey 08855-0849 (United States)
3. Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695-8202 (United States)

Device-grade ultrathin (9{endash}22 {Angstrom}) films of silicon dioxide, prepared from crystalline silicon by remote-plasma oxidation, are studied by soft x-ray photoelectron spectroscopy (SXPS). The 2p core-level spectra for silicon show evidence of five distinct states of Si, attributable to the five oxidation states of silicon between Si{sup 0} (the Si substrate) and Si{sup 4+} (the thin SiO{sub 2} film). The relative binding energy shifts for peaks Si{sup 1+} through Si{sup 4+} (with respect to Si{sup 0}) are in agreement with earlier work. The relatively weaker signals found for the three intermediate states (I{sub 1}, I{sub 2}, and I{sub 3}) are attributed to silicon atoms at the abrupt interface between the thin SiO{sub 2} film and substrate. Estimates of the interface state density from these interface signals agree with the values reported earlier of {approximately}2 monolayers (ML). The position and intensity of the five peaks are measured as a function of post-growth annealing temperature, crystal orientation, and exposure to He/N{sub 2} plasma. We find that annealing produces more abrupt interfaces (by reducing the suboxide interface state density), but never more abrupt than {approximately}1.5 monolayers. We observe a 15{percent}{endash}20{percent} drop in the interface thickness (in particular the {open_quotes}Si{sup 2+}{close_quotes} peak intensity) with increasing annealing temperature. Somewhat different behavior is observed with small amounts of nitrogen in the SiO{sub 2} film where an apparent increase in interface state density is seen. A quantitative analysis is presented which explores the effects of these sample preparation parameters in terms of relative interface state density and modeling of the SXPS data. {copyright} {ital 1999 American Vacuum Society.}

• OSTI ID: 359785
• Report Number(s): CONF-981126--
• Journal Information: Journal of Vacuum Science and Technology, A, Journal Name: Journal of Vacuum Science and Technology, A Journal Issue: 4 Vol. 17; ISSN 0734-2101; ISSN JVTAD6
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BINDING ENERGY
INTERFACES
OXIDATION
PHOTOELECTRON SPECTROSCOPY
PLASMA
SILICON
SILICON COMPOUNDS
SILICON OXIDES
THIN FILMS