Origin of local temperature variation during spike anneal and millisecond anneal

Local thermal variation occurring during light enhanced rapid thermal process (RTP) and millisecond anneals called “pattern effects” have various origin, with more or less impact as function of the used process. The main issues concern the variation of thermal conductivity and the variation of the light absorption by optical interference or diffraction effects. In this paper, a large panel of experiments is described in order to put in evidence the various root causes previously mentioned and their magnitudes are also determined as function of the used process. Experiments were done on full sheet wafer for all phenomena regarding stacked layers and specific patterned structure or full flow wafer are used to evaluate the impact of pattern on temperature variation. Theoretical computation by finite element methodology (FEM) allows a comparison with the experimental results. Thanks to all our results some ways for intradie dispersion reduction will be considered.