Electrical Activation and Impurity Redistribution During Pulsed Laser Annealing of BF2+Implanted Amorphized Silicon

Results of experiments studying the electrical activation and impurity redistribution during annealing of BF2⁺implanted amorphized silicon with a Q-switched Nd:glass laser ( , = 1.06 µm) of 27.5 nm full-width half-maximum (FWHM) are presented. The experimental results are explained on the basis of a thermal melting model. The laser fluence necessary to initiate melting of the front surface was determined using time-resolved reflectivity measurements. The samples irradiated with laser fluences just below the melting threshold and with higher fluences producing melting to successively deeper regions inside the material were specifically investigated. It was found that for full electrical activation, the laser fluence should be large enough to melt past the original amorphouscrystalline interface and the underlying damaged layer, leading to liquid phase epitaxial regrowth and ~100 percent electrical activation.