Systems and method for optimization of laser beam spatial intensity profile

Abstract

In a thin beam directional Crystallization System configured anneal a silicon layer on a glass substrate uses a special laser beam profile with an intensity peak at one edge. The system is configured to entirely melt a spatially controlled portion of a silicon layer causing lateral crystal growth. By advancing the substrate or laser a certain step size and subjecting the silicon layer to successive 'shots' rom the laser, the entire silicon layer is crystallized. The lateral crystal growth creates a protrusion in the center of the melt area. This protrusion must be re-melted. Accordingly, the step size must be such that there is sufficient overlap between successive shots, i.e., melt zones, to ensure the protrusion is melted. This requires the step size to be less than half the beam width. A smaller step size reduces throughput and increases costs. The special laser profile used in accordance with the systems and methods described herein can increase the step size and thereby increase throughput and reduce costs.