FORMATION AND ANNIHILATION OF EPITAXIAL STACKING FAULTS GENERATED FROM PRE-EXISTING NUCLEATION SITES IN SILICON

摘要

Pre-existing saucer-pit induced epitaxial stacking fault formation has been investigated in silicon. Using inductively coupled plasma mass spectroscopy, metallic impurities and low temperature out-diffusion of Cu have been studied in the as-received wafers. It is revealed that near ten times higher Cu contamination than that of usual incoming levels is observed on the surface of the samples. The distribution of the defects revealed after epi growth is exactly corresponding to the striated off-centered patterns of the saucer pits (S-pit), which is strongly affected by the oxygen precipitates in the sample contaminated with homogeneous surface metallic impurities. We have also observed that the S-pits are not formed in the samples with oxygen contents of ～16 ppma and an optimized oxidation temperature for proper bulk defect density and oxidation-induced stacking faults at the wafer backside. This result indicates that the S-pit formation is suppressed by the improved intrinsic/extrinsic gettering efficiency.