Temperature distributions and molten zones induced by heating with line-shaped electron beams

Abstract

A recently developed time-resolved reflectivity technique has been used to characterize the temperature distributions and molten zones induced in silicon-on-insulator structures by heating with scanned line-shaped electron beams. Measured temperature distributions were compared to theoretical predictions from a one-dimensional heat-flow model, which assumes that the heat flow parallel to the surface can be ignored. The results from the experiments and the predictions from the numerical model were also compared to predictions from an analytical model for heating of a homogeneous material. The range of heating conditions for which the one-dimensional approximation was suitable was determined, and it was found to be satisfactory for heating with line beams of more than 200-μm width at sweep speeds greater than 5 cm/s. Conditions which produced melting of the silicon film were explored, and it was found that the numerical model did not adequately describe this phase transition. The discrepancy between the theoretical predictions and the observed results can be explained by the need to supercool the liquid silicon by approximately 155 °C before it freezes.