The formation behavior of grown-in defects in Czochralski silicon (CZ-Si) crystals was investigated using two crystals that were quenched during growth but in one case after crystal growth had been halted for 5 h. The distributions of grown-in defect density and size, and their micro-structures were analyzed as a function of temperature during crystal growth just before quenching by means of an optical precipitate profiler (OPP) and an atomic force microscope (AFM) coupled with a laser particle counter. The formation of grown-in defects, which are considered to be octahedral voids, was found to consist of two dominant processes. The first step involves rapid void growth in a narrow temperature range of about 30° C below 1100° C and the subsequent step consists of an oxide film growth on the inner surface of the void during the cooling process to about 900° C after void formation. It was also found that the growth of the oxide film in the voids is rate-limited by the diffusion rate of oxygen atoms in silicon. In addition, it is strongly suggested that void formation in such a narrow temperature range is due to a rapid agglomeration of vacancies.

Dislocation‐free Czochralski silicon wafers have been subjected to a two‐step annealing procedure to explore the intrinsic gettering (IG) phenomenon and the behavior of thermally induced microdefects using infrared absorption, preferential etching, and transmission electron microscopy (TEM). As a result, it is found that plastic lattice deformation introduced by dislocation and/or stacking faults is necessary for effective IG sinks. In spite of their extremely high density, microprecipitates with elastic strain but no plastic deformation do not result in effective IG. TEM observations clarify the change in density and/or structure of inner defects by precipitate dissolving after the second annealing at high temperature.

The effect of dopant-type, antimony (Sb), arsenic (As), and boron (B), on the outdiffusion of oxygen in heavily doped Czochralski (Cz) silicon wafers has been investigated using secondary ion mass spectroscopy. The results indicate that, although oxygen diffusion in Cz silicon is retarded in heavily B- and As-doped wafers during low temperature annealing (800 °C), it is not influenced by heavy Sb doping. This indicates that charge effects and atom size effects have negligible influence on the diffusion of oxygen. The B and As diffusion retardation effect is attributed to the existence of dopant-oxygen complexes. The oxygen solubility was largest in the most heavily B-doped samples annealed at low temperature.

Oxide precipitate growth in boron‐doped Czochralski silicon wafers with resistivities ranging from 6 to 40 mΩ cm has been studied following prolonged annealing from 800 to 1000°C. Transmission electron microscopy revealed that (i) the growth rate of oxide platelet precipitates is proportional to the square root of time in 40 mΩ cm samples and (ii) the precipitate morphology changes from plate to polyhedral and strain around the precipitate decreases during annealing at 900°C in 6, 9, and 18 mΩ cm samples. These results indicate that changes in precipitate morphology occur because the oxygen precipitation and boron atom size effects are enhanced by increasing boron concentration. © 1999 The Electrochemical Society. All rights reserved.

Etch structure on microdefects in floatingzone silicon wafers as affected by dopants and surface treatment