| 摘要 |
PURPOSE: A TFT(Thin Film Transistor) is provided to reduce cost by decreasing the number of processes and to inhibit the increase of off-state current value of a TFT. CONSTITUTION: A Ta film for use in forming a source electrode(15) and a drain electrode(19), and an amorphous silicon film for using in forming an amorphous silicon semiconductor layer(17) with impurity are continuously etched without setting an etching selectivity ratio. As a result, the source electrode, the drain electrode and the amorphous silicon semiconductor layer can be formed by a single etching process. In the meantime, surface protrusions and recessions can be formed in a back channel region(17a) on the order of several hundreds of reflecting the crystal grain diameters of the Ta film. The protrusions and recessions offer effects of suppressing the increase in off-state current value of a TFT. The TFT can be manufactured through a reduced number of steps at lower cost.
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