METAL IMPURITY TRAPPING EFFECT BY STRESS AT EDGES OF LOCAL OXIDATION OF SILICON STRUCTURE

In this study, the direct relationship between stress at edges of the local oxidation of silicon (LOCOS) structure and Fe atoms was investig ated employing secondary ion mass spectroscopy (SIMS), total reflectio n X-ray fluorescence (TXRF), transmission electron microscopy (TEM), a nd optical microscopy. Fe atoms contaminated from the back of the wafe r diffused to the front surface during the drive-in annealing and beca me trapped by the stress generated at LOCOS edges and aggregated to fo rm some kinds of defect. TXRF analysis suggested that even the lowest stress generated at LOCOS edges in practical LSI fabrication processes must gain sufficient ability to trap Fe atoms once contamination occu rs. There seemed to be a critical Fe concentration to form these defec ts.