Pulsed laser modification of SiO2/Si interface properties and minority-carrier lifetime

Abstract

Effects of pulsed laser irradiation on the SiO2/Si interface are investigated by means of capacitance-voltage and capacitance-time experiments yielding values of surface state density (Nss), oxide charge (QFC), and minority carrier lifetime (MCL) which prove to be a sensitive probe of the laser damage thresholds. Increases of Nss and QFC and decreases of MCL of two to three orders of magnitude from controlled starting values are observed at incident energy densities from 0.7 to 1.1 J cm−2. Subsequent thermal treatments restore either QFC or both QFC and Nss to control values. The laser method gives a technique for localized lifetime reduction on silicon wafers while maintaining long lifetimes elsewhere on the wafers.