Density Functional Theory Study on Frenkel Pair Formation from Oxygen Clusters in Si Crystal

Abstract

Silicon (Si) wafers, which are the most widely used semiconductors for integrated circuit fabrication, are produced by polishing after slicing Czochralski (CZ) grown Si ingots. Oxygen (O) atoms with a concentration of 1×1018 atom/cm3 are incorporated from the melt of Si charged in the SiO2 crucible during crystal growth. The interstitial Oi atoms precipitate in the subsequent heat treatments and grow into oxide precipitates (SiOx). It is well known that self-interstitial (I) atoms are emitted from growing oxide clusters. In this emission, a remaining vacancy (V) contributes to relieve the compressive lattice strain around oxide clusters. That is, the Frenkel pair (self-interstitial I and vacancy V) formation occurs at oxygen clusters. Since these emitted atoms interact with dopant atoms, impurities, lattice defects, etc., and affect the performance of Si wafers, the mechanism of I emission from Oi clusters should be clarified and taken into consideration in the computer simulation of oxygen precipitation. In this study, we analyzed the Frenkel pair formation with and without oxygen clusters in Si crystal by density functional theory (DFT) study.