シリコン単結晶育成中の点欠陥挙動に与える置換型ドーパントと熱応力の効果

Abstract

The mechanisms behind the experimentally observed impact of the type and concentration of substitutional dopants on intrinsic point defect behavior in growing single crystal Si are clarified. On the basis of the density functional theory (DFT) calculated results, an appropriate model of intrinsic point defect behavior in heavily doped Si is proposed. Also one has to take into account the impact of thermal stress on intrinsic point defect behavior during single crystal Si growth. In order to explain the experimental results quantitatively, the dependence of the formation enthalpies of vacancy (V) and self-interstitial (I) on compressive plane stress was determined using DFT calculations. It is found that the compressive plane stress around 20 MPa shifts a growing Si crystal to more V-rich. The calculated plane stress dependence is in excellent agreement with the published experimental values and should be taken into account in the development of pulling processes for 450 mm diameter defect-free Si crystals.