Annealing of boron-implanted silicon using a CW CO2 Laser

Solid-phase epitaxial regrowth of boron ion-implanted silicon is obtained with scanned CW CO2 laser irradiation from the back surface. The crystal damage recovery, electrical activity, and concentration profile of boron ion-implanted silicon after laser and furnace annealing are analyzed by Hall-effect measurements in connection with a layer-removal technique, SIMS, and Rutherford backscattering with channeling. For samples implanted with 120 keV boron ions at a dose of 1016 cm−2, CO2 laser annealing produced better recrystallized layers than those obtained by conventional furnace annealing even at 1000 °C for 30 min. High penetrating CO2 laser irradiation appears to be an effective approach to suppress polycrystalline structure formation, which is the potential limitation of CW argon laser annealing in deeply implanted layers. For samples implanted with 35 keV boron ions at a dose of 1015 cm−2, CO2 laser irradiation-induced solid phase epitaxy was similar to furnace annealing at 1000 °C for 30 min. In both the cases, the carrier concentration profiles after laser annealing are identical to the as-implanted profiles without dopant redistribution. Damage-free crystalline layers are obtained with complete electrical activation of implanted ions.