Initial stage of native oxide growth on hydrogen terminated silicon (111) surfaces

Ogawa, Hiroki; Ishikawa, Kenji; Inomata, Carlos; Fujimura, Shigefumi

doi:10.1063/1.360853

Cited by 62 publications

(49 citation statements)

References 16 publications

(29 reference statements)

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“…The latter value is close to the experimental value of 2250 cm -1 attributed to ν s (Si-H) with the three back bonds oxidized. 15 The calculated value is 37 cm -1 lower that the experimental value. However, we note that in our calculations only one of the four silicon atoms in the (2 × 2) unit cell has been oxidized (see Figure 2c).…”

Section: Resultsmentioning

confidence: 82%

Quantum Mechanical Investigation of the Influence of the Local Environment on the Vibrational Properties of Hydrogenated Si(111)

2008

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Periodic density functional calculations were performed to investigate the vibrational properties of hydrogenated and grafted Si(111) surfaces as a function of surface coverage and subsurface oxidation. Surfaces terminated with -CH 3 , -CCH, and -Cl groups were considered. Subsurface oxidation was taken into account by oxidizing one, two, and three silicon back bonds. The effect of anharmonicity was considered in the calculation of the stretching frequencies of the Si-H and C-H groups. The effect of the different adsorbates on the polarization of the electron density of the SiH group and on the electronic structure of the surface was investigated by means of electron density difference and density of states analyses. The Si-H stretching frequency increases with the surface coverage of -CCH and -Cl species, and it decreases with the increase in the surface coverage of -CH 3 . Positive (negative) frequency shifts correlate with the increase (decrease) of electron density along the Si-H bond. The Si-H stretching frequency shows a very good correlation with the Si-H bond length for all the systems investigated. The Si-C, C-H, and Si-Cl stretching frequencies increase linearly with the surface coverage of the -CH 3 , -CCH, and -Cl groups. The back-bond oxidation of a SiH group produces an increase in its stretching frequency and a decrease of the stretching frequency of the surrounding unoxidized SiH groups. All the calculated frequencies show very good agreement with the experimental values.

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Section: Resultsmentioning

confidence: 82%

Quantum Mechanical Investigation of the Influence of the Local Environment on the Vibrational Properties of Hydrogenated Si(111)

2008

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“…It is important to keep in mind, that in XPS, the photoelectrons are collected from a so called escape depth, which varies with the electron energy. For our experimental conditions, the escape depth may be estimated as (15-30) A, or (10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) monolayers of silicon in the (100) crystallographic direction [8]. Thus, atomic concentrations presented in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…According to this study, a silicon surface polished by colloidal silica is predominately covered by dihydride species, a significant fraction of which is backbonded to oxygen. Such a chemical structure of the silicon top layer resembles an early stage of silicon native oxidation [11,19,20].…”

Section: Thickness Of Silicon Oxide Layermentioning

confidence: 99%

Silicon surface preparation for two-dimensional dopant characterization

Ukraintsev

Potts

Wallace

et al. 1998

The 1998 International Conference on Characterization and Metrology for ULSI Technology

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Most two-dimensional (2D) dopant characterization techniques deal with near surface carrier concentration or surface potential measurements using a device cross-section. Thus, a reproducible and well-characterized surface condition is essential for accurate measurements. We report on an X-ray photoelectron spectroscopy study of surface preparation techniques commonly used in 2D dopant characterization: (i) hydrogen termination, (ii) colloidal silica polishing, (iii) low temperature silicon oxidation. Although the presented results may be applied to any other technique, in this report we concentrate on scanning capacitance microscopy (SCM). For high quality SCM a thin, uniform, and chargefree insulating film has to be formed on top of the silicon sample. Two phenomena may have a critical impact on accuracy of SCM: (i) leakage through the insulating layer and (ii) surface charging which may cause unpredictable variations in flat-band voltage. We found that samples polished by colloidal silica have about one monolayer of oxidized silicon. If the polishing is followed by baking at 200°C in the air then 1 to 2 monolayers of silicon are oxidized and an ultra-thin insulating layer of (4-6) ,~, is formed. A significant leakage through the silicon oxide layer, which may alter SCM measurements, is expected in both cases. Silicon oxidation under UV irradiation in ozone ambient improves insulating property of silicon oxide film. Interface equivalent to ca. (8-15) A of silicon dioxide is reproducibly formed by this technique. Importantly, all tested methods of silicon surface preparation are dopant independent. No noticeable surface charging has been observed for any studied method of silicon surface preparation. For silicon oxidized by UV-generated ozone the position of the Si 2p3/2 core-level relative to the Fermi level changes systematically with dopant type and concentration. The binding energy is higher for n-type silicon and lower for ptype doping. Such behavior is expected for silicon with a relatively low density of surface electronic states and hence unpinned Fermi level. We conclude that silicon oxidation by UV-generated ozone is a promising method of silicon surface preparation for high quality SCM.

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“…27,28 Furthermore, the mechanism of oxidation on Si-H surfaces has been proposed to involve insertion of O into the Si-Si backbonds. [29][30][31] Previous core photoelectron spectroscopic studies of the Si(111)/SiO 2 interface have shown that Si(I) and Si(III) are more abundant than Si 2+ because disrupting an atomically flat (111) surface through layer-by-layer oxidation will cleave either 1 or 3 Si tetrahedral bonds. 6,14,[32][33][34][35] Two Si bonds will be cleaved only at step edges and etch defects, which are a minor component of Si(111) surfaces prepared in this manner.…”

Section: Discussionmentioning

confidence: 99%

High-Resolution Soft X-ray Photoelectron Spectroscopic Studies and Scanning Auger Microscopy Studies of the Air Oxidation of Alkylated Silicon(111) Surfaces

et al. 2006

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High-resolution soft X-ray photoelectron spectroscopy was used to investigate the oxidation of alkylated silicon(111) surfaces under ambient conditions. Silicon(111) surfaces were functionalized through a two-step route involving radical chlorination of the H-terminated surface followed by alkylation with alkylmagnesium halide reagents. After 24 h in air, surface species representing Si + , Si 2+ , Si 3+ , and Si 4+ were detected on the Cl-terminated surface, with the highest oxidation state (Si 4+ ) oxide signal appearing at +3.79 eV higher in energy than the bulk Si 2p 3/2 peak. The growth of silicon oxide was accompanied by a reduction in the surface-bound Cl signal. After 48 h of exposure to air, the Cl-terminated Si(111) surface exhibited 3.63 equivalent monolyers (ML) of silicon oxides. In contrast, after exposure to air for 48 h, CH 3 -, C 2 H 5 -, or C 6 H 5 CH 2 -terminated Si surfaces displayed <0.4 ML of surface oxide, and in most cases only displayed ≈0.20 ML of oxide. This oxide was principally composed of Si + and Si 3+ species with peaks centered at +0.8 and +3.2 eV above the bulk Si 2p 3/2 peak, respectively. The silicon 2p SXPS peaks that have previously been assigned to surface Si-C bonds did not change significantly, either in binding energy or in relative intensity, during such air exposure. Use of a high miscut-angle surface (7°vs e0.5°off of the (111) surface orientation) yielded no increase in the rate of oxidation nor change in binding energy of the resultant oxide that formed on the alkylated Si surfaces. Scanning Auger microscopy indicated that the alkylated surfaces formed oxide in isolated, inhomogeneous patches on the surface.

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Initial stage of native oxide growth on hydrogen terminated silicon (111) surfaces

Cited by 62 publications

References 16 publications

Quantum Mechanical Investigation of the Influence of the Local Environment on the Vibrational Properties of Hydrogenated Si(111)

Quantum Mechanical Investigation of the Influence of the Local Environment on the Vibrational Properties of Hydrogenated Si(111)

Silicon surface preparation for two-dimensional dopant characterization

High-Resolution Soft X-ray Photoelectron Spectroscopic Studies and Scanning Auger Microscopy Studies of the Air Oxidation of Alkylated Silicon(111) Surfaces

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