Effect of Oxide Precipitate Sizes on the Mechanical Strength of Czochralski Silicon Wafers

概要

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The effect of oxide precipitate sizes on the mechanical strength of Czochralski silicon (CZ-Si) wafers has been studied with emphasis on the mechanism of slip dislocation generation by oxide precipitates. Thermal stresses, which are larger than those set up in wafers during actual device processes, were applied to two-step annealed wafers. It was determined by X-ray topography and transmission electron microscopy observations that both platelet and polyhedral precipitates can generate slip dislocations when their size is larger than approximately 200 nm. With further experiments, it is concluded that the precipitates cannot generate slip dislocations during actual device processing when the precipitate size is smaller than 200 nm, and this conclusion is independent of the precipitate density. The stress concentration of compressive thermal stresses applied to oxide precipitates should be the cause of slip dislocation generation. Three critical stress curves of slip dislocation generation were obtained for the wafers, in which the platelet sizes are approximately 70 nm, 200 nm and from 330 nm to 490 nm.
INSTITUTE OF PURE AND APPLIED PHYSICSの論文
1997-12-15