Review of the influence of micro-crystal defects in silicon single crystals on gate oxide integrity

Various micro crystal defects such as Flow Pattern Defects (FPDs), Crystal Originated Particles (COPs) and Laser Scattering Tomography Defects (LSTDs) in silicon single crystals which influence on the Gate Oxide Integrity (GOI) have been closely studied. We believe that FPD and COP are due to the same crystal defects generated during crystal growth, since those defects are not influenced by the interstitial oxygen or substitutional carbon concentration and exhibit close resemblance in the generation and annihilation behaviors. On the other hand, LSTDs are related to oxygen precipitates. The region of GOI degradation is in accordance with the D-region both of CZ and FZ wafers. D-defects, defined as the crystal defects existing in the D-region, are composed of plural kinds of crystal defects such as FPDs, COPs and LSTDs and responsible for the B-mode failure. After the oxidation at 1473K, GOI is recovered from 50% to 80% in CZ wafers and up to 100% in nitrogen non-doped FZ wafers. FPDs and COPs after such treatment seem to be annihilated completely and LSTDs is not sufficiently annihilated. However, GOI of CZ wafers is recovered up to 100% after the annealing in the hydrogen ambient, since LSTDs in the vicinity of the wafer surface are also annihilated. We need to study the micro structure of these crystal defects and also their formation mechanism.