| 摘要 |
Thin-film transistors (TFTs) of peripheral logic circuits and TFTs of an active matrix circuit (pixel circuit) are formed on a single substrate by using a crystalline silicon film. The crystalline silicon film is obtained by introducing a catalyst element, such as nickel, for accelerating crystallization into an amorphous silicon film and heating it. In doing so, the catalyst element is introduced into regions for the peripheral logic circuits in a nonselective manner, and is selectively introduced into regions for the active matrix circuit. As a result, vertical crystal growth and lateral crystal growth are effected in the former regions and the latter regions, respectively. Particularly in the latter regions, the off-current and its variation can be reduced. The vertical growth and the lateral growth have a difference in the degree of crystal orientation. In general, the vertical growth does not provide so high of a degree of crystal orientation in which orientation in the (111) plane with respect to the substrate surface is dominate to a small extent. In contrast, remarkable orientation is found in the lateral growth. For example, the ratio of a reflection intensity of the (111) plane to the sum of reflection intensities of the (111), (220) and (311) planes can amount to more than 80 or 90%.
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