Impact of pattern and LSA stitching effects and processing parameters on reflectance and stress distribution for thermal annealing technologies

Ultra shallow junctions are increasingly important to overcome short channel effects, and sub-millisecond annealing offers the ability to control diffusion while simultaneously offering high activation levels. The ultra-fast annealing process needs tight uniformity control to provide consistent device performance across the wafer. The ultratech LSA-100A system features scan pattern overlap flexibility and closed-loop process temperature control to achieve such uniformity control. Generally speaking, pattern effects can arise from reflectance variations of the incident radiation source used for annealing. The reflectance variation of a long wavelength source at Brewster's angle and p-polarization used for laser spike annealing is compared to a broad-based light source. By the use of a stress measurement technology, the coherent gradient sensing (CGS) interferometer, a detailed characterization of deformation induced during sub-millisecond laser annealing is obtained and is also related to the radiation source.