Atomic structure of the silicon/silicon dioxide interface

Technical Report · Sun Dec 01 04:00:00 EST 1985

OSTI ID:5458575

Mazur, J H

The atomic structure of the Si-SiO/sub 2/ interfaces obtained by thermal oxidation of singular and vicinal surfaces of silicon in dry O/sub 2/ at temperatures above 960/sup 0/C has been studied in cross-section by high resolution electron microscopy (HREM). The interface between the silicon substrate and amorphous SiO/sub 2/ was very abrupt and flat over the entire area observed. Oxidized singular (111) Si surfaces revealed steps one (111) interplanar distance (0.314 nm) high. Width of the terraces between positive and negative steps was dependent upon defocus. Dry oxidation of vicinal (111) 3/sup 0/ (1 anti 10) Si surfaces resulted in an interface with atomically flat terraces about 6 nm wide with ledges 0.314 nm high, all with the same sign. For less inclined vicinal (111) 2/sup 0/ (1 anti 12) Si surfaces, ledges of both signs were observed. Observations of the Si-SiO/sub 2/ interface structure resulting from oxidation of exact (100) and (100) 2/sup 0/ (011) Si surfaces can be interpreted in terms of (100) terraces separated by ledges up to about one Si unit cell high, or as small (111) facets protruding into the SiO/sub 2/. These observations suggest a terrace-ledge-kink model for the Si-SiO/sub 2/ interface structure and a ledge mechanism for high temperature oxidation. The structure of the Si-SiO/sub 2/ interface suggests a very abrupt Si crystal to amorphous SiO/sub 2/ transition but requires the existence of Si atoms in incompletely oxidized states at oxidized Si surfaces for all orientations. Ratios of the Si/sup 1 +/:Si/sup 2 +/:Si/sup 3 +/ can vary depending on interface morphology for a given Si substrate orientation, and therefore might be affected by the oxidation kinetics. In the model, dangling bonds normal to (111) terraces are present on singular and vicinal (111) surfaces. The dangling bonds on a (100) substrate are located in a different ''topological'' environment corresponding to models of P/sub b0/ and P/sub b1/ EPR centers.

• Research Organization: Lawrence Berkeley Lab., CA (USA); California Univ., Berkeley (USA). Dept. of Materials Science and Mineral Engineering
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 5458575
• Report Number(s): LBL-20161; ON: DE86013462
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360604* -- Materials-- Corrosion
Erosion
& Degradation
ATOMIC MODELS
CHALCOGENIDES
CHEMICAL REACTIONS
CRYSTAL STRUCTURE
ELECTRON MICROSCOPY
ELEMENTS
INTERFACES
LAYERS
MATHEMATICAL MODELS
MICROSCOPY
OXIDATION
OXIDES
OXYGEN COMPOUNDS
SEMIMETALS
SILICON
SILICON COMPOUNDS
SILICON OXIDES
SURFACES
TRANSMISSION ELECTRON MICROSCOPY