Method of forming polycrystalline silicon layer on substrate by large area excimer laser irradiation

A method of forming a thin layer of polycrystalline silicon having an average grain size of about 150 nm on a substrate comprising:

• forming an amorphous silicon layer having a thickness of from about 30 nm to about 50 nm on a substrate using monosilane (SiH.sub.4) by a low pressure CVD method at a deposition temperature of less than about 500.degree. C.;
• heating the amorphous silicon layer and substrate to a temperature of from about 350.degree. C. to about 450.degree. C.;
• irradiating the heated amorphous silicon layer in a single shot with excimer laser light having substantially uniform intensity in a diametrical direction of flux and having a total energy of at least 10 J, an energy density of from about 280 mJ/cm.sup.2 to 330 mJ/cm.sup.2 at a pulse width of from about 140 ns to about 200 ns, whereby a polycrystalline silicon thin film having an average grain size of about 150 nm and a low electron trap density at grain boundaries and in grains is provided over a region of at least about 6 cm.times.6 cm in a single annealing treatment.