Study of Flow Pattern Defects and Oxidation Induced Stacking Faults in Czochralski Single-Crystal Silicon Growth

Abstract

This paper emphasizes that the furnace pressure, crucible rotation, and pulling rate have important effects on interstitial oxygen (Oi) concentrations and micro-defects during growth in a Czochralski single-crystal silicon (CZ-Si) growth furnace. Since oxygen in a silicon ingot influences minority carrier lifetime, different set-points of furnace pressure and crucible rotation were controlled to achieve different degrees of Oi. The Oi content has a positive correlation with furnace pressure and crucible rotation. Various numbers of micro-defects were generated under the influence of different pulling rates, owing to the transformation from liquid to solid. The sample also underwent Secco etching and a high-temperature wet oxidation to observe defects caused by the Oi concentration and pulling rate, namely, flow pattern defects (FPDs) and oxidation-induced stacking faults (OISFs). Optical microscopy was employed to confirm the surface topography, and for defect number counting, to observe the correlation between the defects and the minority carrier lifetime. The overall results show that the minority carrier lifetime is mainly dominated by OISFs under high Oi content and FPDs under low Oi content. Therefore, growth using a CZ-Si growth furnace should be carried out with low furnace pressure, low crucible rotation, and low pulling rate to reduce micro-defects.

Keywords

• Czochralski single-crystal silicon
• minority carrier lifetime
• flow pattern defects
• oxidation induced stacking faults