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The study of the optical behavior of oxygen in silicon is presented, based on infrared absorption measurements performed at liquid helium temperature. A total of six groups of silicon wafers characterized by different initial concentrations of interstitial oxygen from similar to 2 x 10(17) to similar to 10(18) atoms cm(-3) were analysed. The experimental conditions were chosen so as to distinguish the contributions from interstitial and precipitated oxygen, while the thermal treatment of the samples was studied in order to cause the growth of the grown-in precipitates. The relative concentrations of platelet and spheroid precipitates grown after the thermal treatment of the wafers are discussed. (C) 2000 Elsevier Science S.A. All rights reserved.

A detailed study performed by means of infrared spectroscopy on Si-H stretching in silicon-rich silicon oxide films deposited by chemical vapor deposition is presented. The experimental spectra of as-deposited and annealed samples are interpreted on the basis of a generalization of the random bonding model. The results indicate that two kinds of Si-H bonds exist, one much more stable than the other, whose properties depend on their nearest neighboring atoms. Copyright © 1996 Elsevier Science Ltd.

We studied oxygen precipitation in silicon upon brief sample annealing at 1100°C by high resolution Fourier transform infrared technique. This technique permits the detection of small agglomerates of disc-shaped precipitates formed in the bulk of annealed silicon wafers. Precipitates are characterized by a peak at 1230 cm -1 in the infrared absorption spectrum. It is further demonstrated that only the disc-shaped precipitates can contribute to the absorption band mentioned. Moreover, the exact wavenumber position of the peak can give additional information about the chemical composition of the oxide constituting the discs.

The spurious contribution of oxide precipitates to the infrared absorption of interstitial oxygen in silicon is determined from spectra collected at 7 K for samples with different initial interstitial oxygen O-i concentration subjected to a three-step thermal treatment. These data can be used to correct the residual O-i values determined at room temperature following the standard procedure from the intensity of the 1107 cm(-1) absorption band. The error in residual O-i is found to reach values on the order of 2x10(17) atoms/cm(3) for samples with initial O-i content higher than 6.5x10(17) atoms/cm(3). (C) 2001 American Institute of Physics

Interstitial oxygen profile across an epitaxial silicon and Czochralski silicon interface has been studied using high-spatial-resolution Fourier transform infrared spectroscopy. Systematic transmission measurements performed on a transversal wafer cross section evidenced oxygen contamination of the epilayer. This was due to solid-state outdiffusion from the substrate occurring during epilayer deposition. Oxygen diffusivity values resulting from the experiments suggest a mechanism scarcely influenced by the interface. Oxygen contamination is strictly related to the type of dopant present in the substrate and not to that present in the epilayer. The oxygen contamination of the epilayer (significant in n-type substrate samples) could explain the structural defects often observed in epitaxial layers by different techniques.

Carbon complex formation during annealing in the temperature range from 450 to 1150-degrees-C is studied in a carbon-rich polycrystalline edge-defined film-fed grown (EFG) silicon sheet. The result is compared with that obtained in Czochralski (CZ) single-crystal silicon. Infrared (IR) spectroscopy reveals that carbon removal from substitutional sites above 600-degrees-C is greatly inhibited in EFG silicon with respect to that seen in the CZ material. A broad IR peak attributed to C-O complexes appears only after annealing at highest temperatures, while there is no evidence for appearance of the sharp band at 794 cm-1 usually assigned to SiC precipitation. The suppression of carbon complex formation in EFG material is attributed to decreased availability of silicon self-interstitials necessary to promote removal of carbon from substitutional sites and to enhance its diffusivity

High-spatial resolution Fourier transform infrared spectroscopy permitted us to study the effects of incident light polarization on the absorption band related to aggregates of SiO2 disk-shaped precipitates present in annealed (100) Czochralski silicon samples. This is the first report documenting the strong dependence of such a band intensity on light polarization. Experimental results were compared with the simulation obtained using the effective medium theory. From this comparison we deduce that the precipitates only lie on the planes among {100} which are parallel to the wafer surface. This result can be related to the difference between the 〈100〉 direction and those crystallographically equivalent, introduced by the ingot growth process.

Edge-defined film-fed grown polycrystalline silicon sheets, grown with one face exposed to oxidizing CO gas added to the inert Ar atmosphere, were studied. Interaction of CO with molten silicon surface during growth produced SiC-like structures in a thin layer on the surface exposed to CO. Infrared spectroscopy results suggest that this layer is constituted of good quality SiC ; however, Raman and x-ray photoelectron spectroscopy showed that it consists of Si1− xCx in the form of small crystallites mixed with C- and O-rich silicon. Journal of Applied Physics is copyrighted by The American Institute of Physics.

In this paper we report the study of early stages of oxygen precipitation in commercial Czochralski silicon as-received wafers and in wafers treated at 1100-degrees for 80 min. The high spatial resolution infrared technique used is able to detect platelet shaped SiO2 precipitates, even in low concentrations. We detected a strong polarization dependence of the precipitate related infrared absorption band performing measurements with linearly polarized light. From these results a preferred orientation of a precipitate aggregation was deduced

High spatial resolution Fourier transform absorption measurements were performed with polarized light on oxygen precipitates grown in silicon samples briefly annealed. We demonstrate that the wave-number position and intensity of the 1230-cm-1 absorption band, directly related to the precipitates, give information regarding stoichiometry of the oxide constituting such precipitates and their density. In particular, the precipitates in our samples are made of amorphous suboxides, mainly SiO1.8, with 5 ppm local concentration. Moreover, our conclusions give evidence that disk-shaped precipitates in silicon have the same optical properties of thermal oxide films with comparable thickness grown on silicon. © 1992 The American Physical Society.

Oxygen content in the bulk of Czochralski silicon was analyzed by using micro‐Fourier transform infrared spectroscopy in a transversal wafer cross‐section configuration. This technique locally distinguishes between interstitial oxygen and oxygen precipitates in wafers used as substrates for epitaxial layer growth. Systematic measurements performed in the 5000–700 cm−1 wavenumber range clearly indicate the presence of oxygen microprecipitates in the bulk of the processed silicon wafers. Quantitative determination of oxygen precipitate density is reported and compared with the measured interstitial oxygen concentration.

A detailed analysis of infrared absorption spectra of porous silicon is performed on the basis of high spatial resolution measurements. Microscopic inhomogeneity and a strong influence of storage ambient are observed. Si atoms of the porous silicon surface are found to bind to H, O, C atoms and to CH3 and OH groups. The presence of free H2O molecules is also detected.