Investigation of Excimer Laser Annealing of Si using Photoluminescence at Room Temperature

Laser annealing can be used for applications that require confinement of heat on the top surface in order to preserve the integrity of buried structures. To confine heat near the silicon surface, the most appropriate tool is UV laser. Here, two excimer lasers with different characteristics were used to anneal boron in silicon. The first one has pulse duration of about 180 ns and the second one of about 20 ns in scanning mode. Regarding the crystal damage characterization, we report that room temperature photoluminescence (RT-PL) is a powerful and non-destructive technique to monitor crystal damage evolution. In order to investigate the effect of a surface oxide on laser annealing, samples with different (1, 20 and 150 nm-thick) surface oxide layers have been annealed. From RT-PL data, the crystal quality is found to improve with increasing laser power density. However the presence of the oxide layer leads to sudden degradation of the PL response for laser energy densities exceeding the melting threshold of Si.