N. Ikeda et al., NONCONTACT CHARACTERIZATION FOR GROWN-IN DEFECTS IN CZOCHRALSKI SILICON-WAFERS WITH A LASER MICROWAVE PHOTOCONDUCTANCE METHOD, Applied physics letters, 63(21), 1993, pp. 2914-2916
Minority-carrier recombination lifetime mapping has been performed wit
h a noncontact laser/microwave photoconductance method for as-polished
wafers containing a ring-shaped distribution of embryonic defects whi
ch form stacking faults during subsequent heat treatment. Using an alg
orithm for the separation of bulk and surface components of the recomb
ination lifetime, four regions, which cannot be distinguished with oth
er techniques such as x-ray topography and preferential chemical etchi
ng, were clearly observed in the maps as those with different lifetime
s. The result can be attributed to the inhomogeneous distribution of g
rown-in defects, most likely intrinsic point defects and/or oxygen rel
ated defects. Moreover, the lifetime was correlated to the surface mic
roroughness of the polished wafers.