Two-beam laser annealing with improved temperature performance

Abstract

Systems and methods are disclosed for performing laser annealing in a manner that reduces or minimizes wafer surface temperature variations during the laser annealing process. The systems and methods include annealing the wafer surface with first and second laser beams that represent preheat and anneal laser beams having respective first and second intensities. The preheat laser beam brings the wafer surface temperate close to the annealing temperature and the anneal laser beam brings the wafer surface temperature up to the annealing temperature. The anneal laser beam can have a different wavelength, or the same wavelength but different orientation relative to the wafer surface. Reflectivity maps of the wafer surface at the preheat and anneal wavelengths are measured and used to select the first and second intensities that ensure good anneal temperature uniformity as a function of wafer position. The first and second intensities can also be selected to minimize edge damage or slip generation.