A method of inspecting the grain size of a polysilicon film. A substrate covered
by an amorphous silicon layer is provided. Next, the amorphous silicon layer is
annealed by a laser beam with a predetermined laser energy density to transfer
it to a polysilicon layer. Thereafter, the polysilicon layer is measured by a spectrometer
under a predetermined photon energy range to achieve an optical parameter. Finally,
the optical parameter is quantized to achieve a determining index, thereby monitoring
the grain size of the polysilicon layer.
