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Temperature Dependence of Melt Duration during Excimer Laser Crystallization Using In-situ Optical Measurements
Chil-Chyuan Kuo, Wen-Chang Yeh, Ji-Feng Lee and Jeng-Ywan Jeng

Preheating the substrate by excimer laser crystallisation of silicon thin films will be shown to be theoretically and experimentally effective in enhancing of the grain size of polycrystalline silicon. The time for solidification of thin silicon films preheated at various substrate temperatures ranging from 100 &Mac176;C to 500 &Mac176;C were investigated experimentally using time-resolved optical reflectivity measurements during a short-pulse of an excimer laser annealing process. The temperature dependence of the melt solidification as a function of the excimer laser fluence was investigated. The longest period for molten silicon to solidify were amorphous silicon (a-Si) thin films, 50 nm and 90 nm thick. They took 480 ns and 711 ns, respectively. The diameter of the disk grain in the lateral growth regime was as large as 3 µm with excellent crystallinity and was accomplished by a single-shot of XeF excimer laser irradiation with a 90 nm-thick a-Si thin film at a substrate temperature of 500 &Mac176;C.

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