Shrinkage of Grown-in Defects in Czochralski Silicon During Thermal Annealing in Vacuum

Abstract

We examined the effect of thermal annealing in vacuum on the behavior of dual-type octahedral void defects in Czochralski silicon. We found that the smaller void shrinks first at about 1100°C and that during the shrinkage of the smaller void to extinction, the bigger void maintains its structure and size. In addition, we found that shrinkage of the smaller void begins from the adjacent region between the two voids. We believe that the effect of minimizing the surface energy first takes place selectively in the smaller void and that after the extinction of the smaller void, the effect of minimizing the surface energy takes place in the bigger void.

A Selective Review of the Simulation of the Defect Structure of Dislocation-Free Silicon Single Crystals

“…The data of the computational experiment on the determination of the microvoid concentration correlate well with the experimentally observed results (10 4 -10 5 cm -3 ) [36]. For the A-microdefects, for which the concentration according to the experimental data is ~10 6 …10 7 cm -3 [14], the discrepancy is as large as three orders of magnitude.…”

“…In the second stage in the temperature range 1323…1173 K occurs precipitation of oxygen and carbon atoms on the inner side of the vacancy complex. These results were confirmed by subsequent researches [34,36].…”

“…The estimation of the characteristic times of the first and second stages, which is performed for the temperature range of microvoid formation, showed that the relation t I << t S << t II is satisfied. Hence, one can unambiguously conclude that a quasi-stationary pore profile is formed during silicon crystal growth if an excess vacancy concentration arises in the range of crystal cooling from 1403 to 1343 K. The conditions for decorating microvoids by background carbon and oxygen impurities (100) in the temperature range of 1343…1173 [34,36] are satisfied well. Our results confirm that an increase in temperature reduces the probability for decorating the pore profile by impurity.…”

Classification of microdefects in semiconducting silicon

“…This inference is supported by the TEM results for vacancy-type microdefects, which researchers termed as microvoids [28,29,34,39]. After short-time high-temperature processing microvoids become smaller in size and their images show dark spots of oxygen precipitates (secondary microdefects).…”

About the simulation of primary grown-in microdefects in dislocation-free silicon single-crystal formation

“…There, analysis of impurities, which influence the formation of grown-in defects, proves that formation of A-and B-microdefects is intensified when the crystal is carbon-doped and hampered when the crystal is oxygen-doped [21,22]. Oxygen concentration defines whether ordinary or double microvoids will be formed [20,31]. It is established that the presence of impurities (in particular, oxygen and carbon) is a key factor in the heterogeneous nature of grown-in microdefects formation [24][25][26].…”