The Effect of Geometric Shape of Amorphous Silicon on the MILC Growth Rate

Abstract

High quality polycrystalline silicon is very critical part of the high quality thin film transistor(TFT) for display devices. Metal induced lateral crystallization(MILC) is one of the most successful technologies to crystallize the amorphous silicon at low temperature(below <TEX>$550^{\circ}C$</TEX>) and uses conventional and large glass substrate. In this study, we observed that the MILC behavior changed with abrupt variation of the amorphous silicon active pattern width. We explained these phenomena with the novel MILC mechanism model. The 10 nm thick Ni layers were deposited on the glass substrate having various amorphous silicon patterns. Then, we annealed the sample at <TEX>$550^{\circ}C$</TEX> with rapid thermal annealing(RTA) apparatus and measured the crystallized length by optical microscope. When MILC progress from narrow-width-area(the width was <TEX>$w_2$</TEX>) to wide-width-area(the width was <TEX>$w_1$</TEX>), the MILC rate decreased dramatically and was not changed for several hours(incubation time). Also the incubation time increased as the ratio, <TEX>$w_1/w_2$</TEX>, get larger. We can explain these phenomena with the tensile stress that was caused by volume shrinkage due to the phase transformation from amorphous silicon to crystalline silicon.