The effect of temperature oscillations at the growth interface on crystal perfection

Abstract

Dislocation-free silicon crystals are grown with the Czochralski technique under various growth conditions, including changed heater positions, pulling rates, and crystal and crucible rotation rates. The correlation between the microdefect density in crystals and temperature oscillations near the growth interface is investigated. It is found that the microdefect density decreases with higher heater position, increased pullong rate and decreased crystal rotation rate. Theseresults are in accord with the behavior of the temperature oscillation amplitude. Thus, the density of microdefects decreases as the oscillation amplitude is reduced. The relation between microdefect density and temperature oscillation amplitude is well explaines by the crystal remelt model. The microdefect density in a crystal varies for annealing at more than 1000δC immediately after growth. Thus, the reduction of microdefect density by annealing depends on the defect distribution in the as-grown crystals.