Investigations of interstitial generations near growth interface depending on crystal pulling rates during CZ silicon growth by detaching from the melt

Abstract

In conventional CZ crystal growth, since formation of a cone tail takes a long time, from such a crystal to have been subject the long heat treatment it is not possible to observe actual distribution of vacancies (Vs) and interstitial atoms (Is) in a straight body of a crystal during growth. This experiment attempted to observe point defect distribution frozen by rapidly cooling a crystal that had been detached from a melt during growth to eliminate the effect of the time delay. Comparison between the experimental results of these specimens and the defect distributions of a conventionally pulled crystals revealed that Vs are introduced at a growth interface and the concentration of the Vs does not depend on the pulling rate. In addition, when the pulling rate is low, Is are generated by thermal stress which increases with increasing thermal gradient G because the amount of heat transfer by mass transfer is decreased and the crystal surface near the growth interface is cooled for longer period. As a result, the generation of Is due to the increase of the thermal stress is observed in an area referred to as an interstitial generation area (IGA) located above the vacancy region on the growth interface, where the crystal temperature is 1300°C or more. This paper describes the recombination (Rc) mechanism by which these Is created in the IGA are recombined with Vs transformed through the growth interface, thereby creating an observable Rc area at a location where no defect can be detected.