Abstract

A semiconductor layer annealing method comprises a step of heating a wafer consisting of a substrate and a semiconductor layer formed thereon by a heating means at a preheating temperature which will not exercise adverse thermal effect on the substrate, heating a portion of a small area of the semiconductor layer by a pulse of an excimer laser beam in one annealing cycle to a temperature higher than the preheating temperature and high enough to anneal the portion of the semiconductor layer, and repeating the annealing cycle to anneal the successive portions of the semiconductor layer sequentially. Since the semiconductor layer is preheated and the excimer laser beam needs only to raise the temperature of the semiconductor layer by a temperature far lower than the annealing temperature, the energy density of the excimer laser beam on the semiconductor layer may be smaller than that required by the prior art semiconductor layer annealing method and hence the area of a portion of the semiconductor layer which can be annealed by the semiconductor layer annealing method is greater than that can be annealed by the prior art semiconductor layer.