Reduction of oxygen concentration in 300 mm diameter n-type Czochralski silicon crystal growth using an optimized heating zone with dual side-heaters

Abstract

In recent years, Czochralski silicon (Cz-Si) crystals have been progressing toward n-type, large diameter and low oxygen concentration. For this purpose, the modified heating zone structure for 300 mm diameter n-type Cz-Si crystal growth with dual side-heaters has been proposed; moreover, its feasibility and effectiveness were verified through numerical simulations and on-site experiments herein. The simulation results indicate that the proposed crystal growth technique with modified parameters can effectively enhance the uniformity of longitudinal temperature gradient in the silicon melt and lower the temperature at the silica crucible bottom, for reducing the oxygen concentration at the crystal head. Based on it, 300 mm diameter n-type recharged Cz-Si (RCz-Si) crystals with an oxygen concentration in the range of 9.5–10.5 ppma were grown in on-site experiments, which is much lower than that grown in a conventional heating zone structure. More importantly, the photoluminescence (PL) images of the quarter wafers taken at the as-grown Cz-Si crystal head, middle and bottom have shown that little metastable defects can be annealed out during typical high-temperature oxidation at 1000 °C, confirming the excellent stability of thermally induced degradation. Consequently, this manuscript has demonstrated that the proposed crystal growth technique can realize dual goals of oxygen concentration control and crystal quality assurance in 300 mm diameter n-type Cz-Si crystal growth, which may promote the development of large diameter Cz-Si crystal growth techniques and the related application industries.