To reveal a difference of defect formation behaviors, i.e. grown-in void formation during crystal growth and oxide precipitation in nand p-type silicon, we have investigated by using heavily boronand arsenic-doped silicon crystals. The density of void defects in heavily boron doped silicon was decreased with a shrinking OSFring, but in arsenic doped silicon were increased with resistivities below 3.3mΩcm. On the other hand, for oxygen precipitation, the nucleation rate in boron doped silicon was enhanced with increasing resistivities, while decreased by one tenth in reference to lightly doped silicon for resistivities up to 4.4mΩcm in arsenic doped silicon. These contrastive phenomena between n-and p-type cannot be explained with a growth model of precipitates by an accelerated diffusion of oxygen in silicon. We believed that the nucleation rate of oxide precipitates related to a dependence of point defects on fermi level closely.

Development of point defect‐controlled Czochralski silicon (CZ‐Si) crystal growth technology by v/G control, i.e., the ratio of growth rate (v) to the axial temperature gradient (G) in the crystal near its melting point, is reviewed and nitrogen‐ and hydrogen‐doping technologies are proposed for 300‐mm magnetic‐field‐applied CZ‐Si (MCZ‐Si) crystals free of grown‐in defects with very low oxygen for application to future silicon power devices such as insulated gate bipolar transistors (IGBTs). Using a hot zone with a uniform G distribution in a crystal radial direction, v/G is maintained by controlling v of around the critical value at which the amount of vacancies is balanced with that of self‐interstitials so that the generation of grown‐in defects, such as voids and dislocation clusters, are suppressed. Nitrogen‐doping or hydrogen‐doping technology combined with v/G control also enables the enlarging of the process window for grown‐in defect‐free MCZ‐Si crystals that can be used as an alternative material to floating zone‐Si crystals. The advantages and disadvantages of both technologies are discussed from the view point of crystal quality required to guarantee higher performance of future IGBTs.

Dependence of mechanical strength of large diameter wafers as a function of impurity concentration and density of oxide precipitates has been studied in terms of brittle fracture and slip dislocation propagation.

The physical properties of point defects in Si crystal have not been established with certainty. That makes it difficult to calculate the behavior of grown in defects in CZ Si crystal growth. With high precision thermal analysis we studied the physical properties of point defects from which the grown in defects distribution could be calculated. In this study we focused the attention on the V I boundary in which the vacancy and self interstitial concentrations are balanced, which appears in case of slowly decreasing the crystal growth rate. we assumed that the determination of the physical properties was an optimization problem, and we applied a genetic algorithm method and a simulated annealing method. In addition, we examined the optimized physical properties with physical considerations and reproducibility of V I boundary shape in calculation. As a result, we estimated one promising set of the physical properties, which were used to calculate the grown in defect distribution. The calculation result showed that (1) it could reproduce the experimental results and (2) the concentration difference (DC ) between vacancy and self interstitial was related to grown in defect types.

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