TRANSIENT OPTICAL REFLECTIVITY STUDY OF LASER ANNEALING OF ION-IMPLANTED SILICON - THRESHOLDS AND KINETICS

By probing transient optical reflectivity, we have investigated the liquid phase epitaxial regrowth kinetics of ion-implanted silicon during laser annealing. For annealing of ion-implanted silicon with an 80-ns (FWHM) pulse of various intensities at 1.06 μm, the threshold energy density required for melting is observed to be a constant. Above this threshold value, annealing occurs via an amorphous-to-liquid-to-crystalline transition. Redistribution of As profiles as measured by He+ backscattering spectra is observed only when the incident energy density exceeds the threshold. Below this value, a reduction of dechanneled fraction is observed, but no dopant redistribution occurs. From the observed melting onset, a maximum heating rate of about 2×1010 deg sec-1 is observed.