TEMPERATURE DIAGNOSTICS FOR LASER WRITING

Infrared (IR), Raman, and luminescence measurements are discussed with respect to their application as temperature probe during laser writing. IR measurements on the high energy side of the Planck distribution can be applied to a large variety of materials and large temperature ranges. This technique is characterized by a good temperature (approximately 1 deg C) and reasonable spatial (approximately 3 mu m) resolution. Raman measurements require long integration times. The evaluation of temperature from such measurements is difficult: for intensity measurements the spatial and temporal averaging and the (unknown) scattering cross-sections have to be considered whereas pressure effects induced by nonuniform heating are a major problem for interpreting Raman frequency measurements. The application of luminescence measurements to temperature evaluation is limited to a few materials, e. g. III-V semiconductors. A high spatial resolution ( less than equivalent to 1 mu m) allowing evaluation of temperature profiles is demonstrated in (Al,Ga)As.