Polycrystalline siliocn thin film transistors with the highest preorded performance have been successfully fabricated using novel technologies that combined solid phase crystallization, excimer laser annealing and post-heat reatment processes. The field effect mobility, threshold voltage and sub-threshold swing for the thin film transistors were 325 cm~2/V centre dot s, 0.15V and 0.08V/dec., respectively. This high-perfor,ance was achieved by reducing surface roughness and crystalline defects in the polycrystalline silicon films. For polycrystalline silicon thin film transistors in which boron ions were implanted in channel region for controlling threshold voltage, the elctrical activity of boron using the novel process was 1.5 times higher than that using the conventional soid phase crystallization process. The rate of decrease of field effect mobility for channel-doped polycrystalline silicon thin fim transistors fabricated using the novel process was smaller than those for conventional process, and the degradations of the sub-threshold swing were not observed up to a dose of 3 x 10~(12) cm~2.
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