External gettering by aluminum–silicon alloying observed from carrier recombination at dislocations in float zone silicon wafers

Abstract

The influence of external gettering by a backside aluminum–silicon (Al–Si) alloy on the recombination strength of dislocation arrays in silicon was investigated. These arrays were made by scratching and bending float zone silicon wafers at 750 °C for 6 h. Light beam induced current maps showed that the recombination strength of these defects is drastically reduced at room temperature after the sample have been submitted to an external gettering treatment by means of Al–Si alloying at 900 °C. This can be explained by the removal of metallic impurities introduced by inadvertent contamination from dislocations and by their capture in the aluminum–silicon alloy by means of a segregation induced gettering mechanism.