Optical Measurement of the Melt Depth During Pulsed Laser Irradiation

Abstract
We propose a method of noncontact, nondestructive, and in situ evaluation of surface melting characteristics of semiconductors during pulsed laser irradiation. By regarding the melted layer caused by pulsed laser irradiation as thin films for optics, melting characteristics can be evaluated from time-resolved reflectivity measurements. We measure the surface melting characteristics of single crystal silicon caused by ArF excimer laser irradiation using this technique. From this experiment, it is found that maximum melt depth does not vary linearly with the incident energy density around the melting threshold.