An apparatus for annealing a layer of amorphous silicon, a method of annealing a layer of amorphous silicon, and a flat panel display

摘要

A laser beam source 30 and a beam scanner 34 for annealing amorphous silicon to form poly-silicon. The beam may preferably be split to form a set of sub beams 33. The beam or beams is scanned to selectively irradiate a plurality of specific regions of the layer of amorphous silicon and thereby generate a corresponding plurality of separated regions of polysilicon. The beam may be shaped to be rectangular (see figs ) by element 32, such as a diffraction element. The beam shape 8 is preferably made to match a specific isolated regions 6 of the amorphous silicon substrate, so that a polysilicon region 6 can have a TFT formed there that may drive a display pixel. Thus the apparatus can form an array of TFT regions as figure 6 shows. The beam may be scanned in across the substrate in direction 10 while the substrate is moved upwards using an oblique trajectory to compensate as figure 7 shows. This can result in a raster scan over the substrate as figures 9 and 10 show. The laser may be pulsed and apply one or more pulses to each region and the energy of the pulses may vary as figures 8-10 show.