INFLUENCE OF SURFACE MELT FLOW ON OXYGEN INHOMOGENEITY IN CZOCHRALSKI-GROWN SILICON SINGLE-CRYSTAL - STUDIED BY DOUBLE-LAYERED CZOCHRALSKI (DLCZ) MELT QUENCHING TECHNIQUE

The oxygen incorporation mechanism at the growth interface during Czoc hralski (CZ) silicon single crystal growth has been studied using melt quenching technique developed by the double-layered Czochralski (DLCZ ) process. A slow crystal rotation rate of 0.5 rpm was chosen to inves tigate the influence of melt convection in relation to the source of o xygen on the oxygen inhomogeneity in the grown crystal, Micro-Fourier transform infrared spectroscopy (micro-FTIR) measurement and preferent ial etching revealed that the oxygen variation in the crystal was dete rmined by the balance of the bulk melt with a high oxygen content and the oxygen-depleted melt from the free surface. The major cause of the periodic intake of the oxygen-depleted melt flow during one crystal r otation was probably the inhomogeneous radial temperature gradient. Th is suggests that thermal asymmetry in the melt is a fatal factor in ox ygen inhomogeneity in the crystal. We have postulated that the equilib rium oxygen segregation coefficient is not much smaller than unity, bu t is rather close to it.