Investigation of oxygen precipitation related crystal defects in processed silicon wafers by infrared light scattering tomography

Infrared light scattering tomography (IR-LST) was used to study microdefects in processed silicon wafers. Both p- and n-type CZSi substrates with different initial oxygen concentrations from 7× 1017 to 11 × 1017 cm−3 were used. A variety of thermal pretreatments and their influence on the defect generation in a diode process were studied. Extended secondary defect formations like stacking faults with their surrounding Frank-loop and prismatic punching systems were identified directly by IR-LST. Correlations between defect densities obtained for different sizes of defects and the initial concentration of interstitial oxygen and the loss of interstitial oxygen during processing, respectively, have shown that the concentration and size of as-grown nuclei is strongly affecting the defect generation after different thermal pretreatments. The inverse effective carrier lifetime depends linearly on the defect density obtained by IR-LST.