Influence of phosphorus diffusion on the recombination strength of dislocations in float zone silicon wafers

Abstract

Dislocation arrays are investigated in float zone (FZ) grown silicon wafers by the light beam induced current (LBIC) mapping technique at various wavelengths and by deep level transient spectroscopy (DLTS). The LBIC technique allows us to recognize and detect these arrays and to evaluate their recombination strength. Dislocations are found to be less recombining in (100)-oriented FZ samples than in (111) oriented ones. In FZ dislocated wafers, a phosphorus diffusion strongly attenuates the LBIC contrast of dislocations, depending on the duration and temperature of the treatment. Electrical activity of the defects, which are still physically present, as verified by x-ray topography, seems to disappear. Simultaneously, the peak intensities of DLTS spectra related to dislocations are reduced and this reduction depends on the phosphorus diffusion temperature and duration.