Tailoring the oxygen distribution in 300 mm Czochralski crystal of pure silicon using cusp magnetic field

Abstract

Oxygen content in the pure Silicon crystal is inevitable because of the significant rate of corrosion of the crucible walls at high temperature. Precise control of oxygen concentration in the crystal is possible only by manipulating underlying flow characteristics of the melt. Thermo-fluidics in this process are extremely complex and responsible for non-uniform oxygen striations. This work is focused to understand the melt flow complexities and its influence on oxygen distribution near the crystallization front. A global model which accounts for hardware configuration is considered for this purpose. The melt flow characteristics are investigated to study the effect of crystal and crucible rotations in absence and presence of the electromagnetic fields (EMs). Our simulation results show that strong buoyancy driven flow interaction generates non-uniformity in oxygen concentration near the edge of the crystal in the absence of magnetic field. Application of external field facilitates more pumping of melt underneath the crystal that prevents stratification of oxygen near the edge.

Silicon Crystallization Technologies

“…Different arrangements and modifications had been developed, like, e.g., axial magnetic fields (Kakimoto et al, 1996) versus transverse ones (Hoshi et al, 1985), as well as cusp fields (Watanabe et al, 1998), rotating magnetic fields (Dold, 2003;Kakimoto, 2002), or traveling ones . The benefits are obvious: with a proper field design, it is possible to reduce temperature fluctuations (Dold and Benz, 1995;Kanda et al, 1996), to minimize dopant striations (Kakimoto et al, 1995;Kim and Smetana, 1985), to stabilize the interface shape (Lu, 2007), and to lower the oxygen concentration (Gunjai and Ramchandran, 2009). The latter aspect is actually a hot topic: is it possible to reduce the oxygen level sufficiently to use MCz wafers instead of FZ wafers?…”

Investigation of Oxygen Behavior under Different Melt Flow, Diffusion Boundary Layer, and Crystal-Melt Interface in a 300 mm Silicon Crystal Growth with Cusp Magnetic Field

“…Nguyen [9] numerically investigated the effects of a balanced/unbalanced cusp magnetic field (CMF) and crystal crucible inversion/isorotation on the heat, flow, and oxygen distribution during the growth of 8-inch silicon crystals. In Gunjal [10], a global model was established to study the effect of crystal and crucible rotation on melt flow in the absence and presence of electromagnetic fields.…”