Defects formed by pulsed laser annealing: electrical properties and depth profiles in n-type silicon measured by deep level transient spectroscopy

The ongoing downscaling of microelectronic devices requires dopant activation with diffusion kept to a minimum. One method considered in device processing is microsecond annealing by pulsed lasers. This is a highly non-equilibrium process during which intrinsic point defects generated at the surface diffuse into the material and form a variety of defects during cooling-down. Since the defects lie close to the surface, they may well affect the effective concentration and the formation of leakage currents in pn-junctions of advanced technologies. These defects may be clusters of intrinsic point defects or contain residual impurities like oxygen or dopants. In this work, a bare n-type silicon substrate ( phosphorus concentration 5 x 1014 cm(-3)) was annealed with a pulsed laser with maximum temperatures of about 800K up to 1650 K. The defects remaining after annealing were characterized by deep level transient spectroscopy (DLTS) to obtain their activation energies and capture cross-sections for majority carriers in n-type silicon. Additionally, the depth profiles of these defects were measured via a variation of the pulse voltage. The dominating defects found have levels at E-C - 0.41 eV, E-C - 0.31 eV, E-C - 0.3 eV, E-C - 0.22 eV, and E-C - 0.17 eV.