Impact of plane thermal stress near the melt/solid interface on the ν/G criterion for defect-free large diameter single crystal Si growth

Abstract

Very recently, first experimental evidence was published that the compressive thermal stress near the melt/solid interface makes a growing 300mmdiameter Czochralski Si crystal more vacancy-rich. The purpose of this letter is to explain these experimental results quantitatively by determining the dependence of the formation enthalpies of the vacancy and the self-interstitial on compressive plane stress using density functional theory based calculations. It is found that compressive plane stress gives a higher stress dependence of the so-called "Voronkov criterion" compared to the isotropic stress. In most of the central region of a growing crystal, the dominant component of the thermal stress near the melt/solid interface is compressive plane stress. 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 the mass-production of 450 mm diameter defect-free Si crystals. © 2014 The Electrochemical Society.