Two-beam laser annealing with improved temperature performance

A method of annealing a semiconductor substrate having a patterned surface and a melt temperature, comprising:

• measuring, for a portion of the patterned wafer surface, first and second reflectivity maps at respective first and second wavelengths;
• using the first and second reflectivity maps, defining first and second intensities of first and second laser beams having the first and second wavelengths, respectively, that minimize an amount of surface temperature variation;
• and
• irradiating the portion of the patterned surface to anneal the semiconductor substrate without melting the semiconductor substrate using the first and second laser beams having the first and second intensities, respectively.

A system for laser annealing a semiconductor wafer having a patterned surface with first and second reflectivity maps at respective first and second wavelengths and an anneal temperature that is below a melt temperature of the wafer, comprising:

• a first laser system configured to generate a first laser beam having the first wavelength and a first intensity and scan the first laser beam over the patterned surface in a first incident plane to heat the patterned surface to a preheat temperature;
• a second laser system configured to generate a second laser beam having the second wavelength and a second intensity and scan the second laser beam over the patterned surface in a second incident plane relative to the first incident plane of the first laser beam, the second laser beam being configured to heat the patterned surface from the preheat temperature to the anneal temperature;
• and
• wherein the first and second intensities are selected based on the first and second reflectivity maps to reduce an amount of surface temperature variation during the scanning of the first and second laser beams as compared to annealing the patterned surface of the semiconductor wafer with only the second laser beam.