Investigation of Czochralski Silicon Grown with Different Interstitial Oxygen Concentrations and Point Defect Populations

Abstract

Czochralski silicon crystals, grown with different interstitial oxygen concentrations (group I) or different types of intrinsic defects (group II), were analyzed by X-ray section topography, diffuse X-ray scattering, surface photovoltage, microwave photoconductive decay, and Fourier infrared spectroscopy. The samples of group I showed that the main factor influencing the X-ray section topography images is the amount of precipitated oxygen. The increase in this amount involves a decrease in size and an increase in density of the oxygen precipitates. A strong reduction in the minority carrier diffusion length is observed after precipitation. These effects seem to be dependent on the positions along the ingot axis at which the samples were taken, which would indicate the influence of the sample thermal history on the detectability of oxygen precipitates by means of these techniques. The samples of group II are characterized by vacancy-rich, interstitial-rich, and defect-free regions. After copper decoration, the different defects were observed to have different sizes, densities, shapes, and depth distributions. This feature allows one to clearly distinguish between crystal zones where vacancy or interstitial clusters prevail and where defects are absent. Minority carrier lifetime values are directly related to the defect volume densities. The combined use of different characterization techniques proved itself a powerful tool to study different defect types in Czochralski silicon. © 2001 The Electrochemical Society. All rights reserved.