Activation of Silicon Implanted with Phosphorus Atoms by Infrared Semiconductor Laser Annealing

We activated silicon implanted with phosphorus atoms by infrared semiconductor laser annealing with a diamond-like carbon (DLC) optical absorption layer. The silicon samples implanted with phosphorus atoms at 10 and 70 keV with concentrations of 5 x 10(14), 1 X 10(15), and 2 x 10(15) cm(-2) were coated with 200-nm-thick DLC films. The samples were annealed by irradiation with a 940 nm continuous wave laser at 70 kW/cm(2) with a beam diameter of 180 mu m. The laser beam was scanned using a moving stage at 3-20cm/s, which gave an effective dwell time of 0.9-6.0 ms. The amorphized surface regions were recrystallized by laser annealing longer than 1.2 ins. The in-depth profile of phosphorus concentration hardly changed within 5 nm for laser annealing for 2.6 ms. The sheet resistance markedly decreased to 106 and 46 Omega/sq for the samples implanted with phosphorus atoms at 10 and 70 keV by laser annealing at a dwell time of 2.6 ms, respectively. Phosphorus atoms were effectively activated with a carrier density near the phosphorus concentration for implantation at 70keV. A low carrier generation rate was observed for implantation at 2 x 10(15) cm(-2) and 10keV. An intermediate SiO2 layer effectively blocked carbon incorporation to a level below 10(17)cm(-3).