Thermal budget considerations for excimer laser annealing of implanted dopants

For activation of implanted dopants in bulk silicon with excimer laser annealing, the optimal laser energy density will depend on the substrate heating, and the pulse width and shape. These parameters will determine the thermal cycle and the heat affected zone. The latter is particularly important for low thermal budget annealing of electronic devices. In this work, two methods were studied, both based on XeCl excimer laser setups. Either a long pulse (180 ns) single laser setup by Excico was used, or a double laser setup with 25 ns native pulse width in DIMES. In the latter, the pulse shape and the temporal thermal profile can be tailored with short pulse offsets. This way the total thermal budget can be increased while the laser energy of each pulse is decreased, for the same sheet resistance. In this paper, the two methods are compared by sheet resistance measurements on laser annealed arsenic implants. The temporal and spatial thermal profiles were also calculated for both methods. Results show that the laser energy density can range from 600-1850 mJ/cm(2) to give full activation with different thermal profiles based upon the method used.