Crystal Growth and Evaluation of Silicon for VLSI and ULSI

303Defects in Silicon Wafers

Inthe quenched crystal, the density of defects (silicon oxide precipitates) detected after heat

treatment at 1000°C for 12 h was reduced by about three orders of magnitude more than

the standard grown crystal when the crystals contain about 1 × 10

18

oxygen atoms per cm

3

.

Three types of microdefects, formed by the agglomeration of either self-interstitials or

vacancies, have been observed in dislocation-free single crystals grown using the ped-

estal pulling technique (crucible-less growth). Based on the microdefect distribution in

quenched crystals, Roksnoer [33] concluded that the dominant type of point defect at the

melting point of silicon is the vacancy, whereas an excess of self-interstitials is usually

present ...