Correlation Study of Bulk Si Stress and Lithography Defects Using Polarized Stress Imager

Polarized Stress Imaging is an excellent method for monitoring bulk stress distribution in silicon wafers. In this study, the correlation of bulk Si stress and lithography defects are shown using Semilab's Polarized Stress Imager (PSI) system. 300 mm diameter samples with 7 nm advanced node FinFET devices were investigated with PSI optical imaging metrology tool and AMAT's UVision wafer inspection tool. Two sets of samples were analyzed after shallow trench isolation etch and after gate etch. Results show that stress imaging can detect process deviations that lead to high defectivity and may have uses in failure analysis to pinpoint root causes of failures.