Double-pulse method for enlarging lateral grain growth of excimer laser annealed poly-Si thin films

Excimer laser annealing of a-Si (amorphous Silicon) using a double-pulse me thod has been investigated in order to obtain large poly-Si (polycrystallin e silicon) grains. The double-pulse method, i.e., the sequential irradiatio n of two KrF excimer lasers with nano-second order pulse-widths and interva l, can enlarge the poly-Si grains on glass substrate caused by gradual soli dification process after a long melting time. The surface melting time of a -Si films was estimated by transient surface reflection measurement to unde rstand the solidification process during the double-pulse irradiation. The reflection measurement revealed that the maximum melting time was lengthene d to 360ns by double-pulse irradiation, which was 4.5 times longer than tha t by conventional single-pulse irradiation. In addition, this analysis supp orted the supposition that the maximum grain size of 1.8 mum was obtained i n the condition of the maximum surface melting time.