Abstract
The oxygen incorporation mechanism at the growth interface during Czochralski (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 investigate the influence of melt convection in relation to the source of oxygen on the oxygen inhomogeneity in the grown crystal. Micro-Fourier transform infrared spectroscopy (micro-FTIR) measurement and preferential etching revealed that the oxygen variation in the crystal was determined 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 rotation was probably the inhomogeneous radial temperature gradient. This suggests that thermal asymmetry in the melt is a fatal factor in oxygen inhomogeneity in the crystal. We have postulated that the equilibrium oxygen segregation coefficient is not much smaller than unity, but is rather close to it.