TEM observation of grown-in defects in CZ and epitaxial silicon wafers detected with optical shallow defect analyzer

Abstract

In order to apply an optical shallow defect analyzer (OSDA) to wafer inspection effectively, we investigated the correspondence of the sizes and depths of the grown-in defects measured by OSDA in CZ-Si to those measured by TEM. A focused-ion-beam (FIB) microsampling technique was used for preparing cross-sectional TEM specimens from a plan-view TEM specimen. Both plan- and cross-sectional views of the identical defect were obtained. The defect depths measured by OSDA coincide with those estimated by stereo observation within an error of ±0.1 μm. The ratio of the OSDA-measured defect size to that estimated from the TEM image varies from 0.68 to 1.80. The variation of the ratio may be caused by the dependency of scattering intensity on incident beam angle to the defect. We also observed the grown-in defects in an epitaxial wafer. Lattice strains were found, which might be caused by particles stuck on the wafer surface during epitaxial growth.