Grown-in defects in heavily phosphorus-doped Czochralski silicon

Abstract

Grown-in defects in an apparently dislocation-free heavily phosphorus (P)-doped Czochralski silicon (CZ-Si) crystal ingot were investigated by preferential etching and transmission electron microscopy (TEM). It was found that large-sized grown-in oxygen precipitates and the extended defects were present in the tang-end of the ingot. It is believed that oxygen precipitation in the tang-end ingot is enhanced by carbon (C) and by vacancies. Moreover, it was considered that phosphorus atoms might preferentially segregate on oxygen precipitates and caused high strain in silicon crystal. It is suggested that the large-sized precipitate might punch out dislocation loops under exceed stress during crystal growth. Finally, a tentative explanation for generation of grown-in defects in heavily P-doped CZ-Si is presented.