TIME-RESOLVED REFLECTIVITY MEASUREMENTS OF TEMPERATURE DISTRIBUTIONS DURING SWEPT-LINE ELECTRON-BEAM HEATING OF SILICON

Experiments have been carried out to determine the temperature distributions induced during swept-line electron-beam heating of silicon. In situ measurements of the reflectivity were used to determine the temperature rise, using as a basis the rise in reflectivity exhibited by silicon with increasing temperature. Sweep speeds between 10 and 60 cm/s were studied using line beams between 60 and 300-mu-m wide. The experimental results were compared with analytic one- and two-dimensional models assuming constant thermal properties, and with a one-dimensional (1D) numerical model which takes into account the variation of heat capacity and thermal conductivity with temperature. The analytic models were used to show the range of conditions over which the 1D approximation could be applied and to quantify the errors introduced as this approximation breaks down. The experimentally measured peak temperatures and those predicted by the numerical model were found to agree to within 5% for conditions where the heat flow was in the 1D regime. For other conditions, the experimental and numerical results were found to differ, but the size of this discrepancy was consistent with the errors introduced by making the 1D approximation in the numerical model.