| 摘要 |
PURPOSE:To obtain a TFT structure in which hydrogenation effect can be sufficiently achieved without depending on a channel length by forming the thickness of a gate electrode to a specific value or less. CONSTITUTION:A TFT 100 is formed of a polycrystalline silicon having a source region 2, a drain region 3, a channel region 4, a gate insulating film 5, a polysilicon gate electrode 6, a protective PSG film 7, a source electrode 20, and a drain electrode 30 on an insulating substrate 1. Then, the thickness tG of the gate electrode 6 of the polysilicon is set to 1500Angstrom or less. When the tG becomes 2000Angstrom or less, muFE abruptly rises, and VTH decreases. This is because the residue of activated hydrogen absorbed to the electrode 6 arrives at the surface of the region 4 and unbonded polysilicon is bonded to hydrogen. No change in the characteristic even if the tG is set to 1000Angstrom or less is because, even if the hydrogen is invaded to the deep layer of the region 4, the formation of the channel is limited to an extremely thin layer of the surface. The gate electrode is formed to the thickness of the degree or less in which the hydrogenation is effected to uniformly hydrogenate the whole channel region.
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