Thin film transistor and display device comprising the same
According to one embodiment, a thin film transistor includes an oxide semiconductor layer provided above an insulating substrate and including a channel region between a source region and a drain region, a first insulating film provided in a region on the oxide semiconductor layer, which corresponds to the channel region, a gate electrode provided on the first insulating film, a first protective film provided on the oxide semiconductor layer, the first insulating film and the gate electrode, as an insulating film containing a metal, a second protective film provided on the first protective film and a third protective film provided on the second protective film, as an insulating film containing a metal.
1. A thin film transistor comprising:
an oxide semiconductor layer provided above an insulating substrate and including a source region, a drain region and a channel region between the source region and the drain region;
a first insulating film provided in a region on the oxide semiconductor layer, which corresponds to the channel region;
a gate electrode provided on the first insulating film;
a first protective film provided on the oxide semiconductor layer, the first insulating film and the gate electrode, as an insulating film containing a metal;
a second protective film provided on the first protective film; and
a third protective film provided on the second protective film, as an insulating film containing a metal, wherein the first protective film directly contacts sidewalls and a top surface of the gate electrode, wherein the third protective film is thicker than the first protective film.
2. The thin film transistors of claim 1 , wherein
the first protective film and the third protective film are each formed of aluminum oxide.
3. The thin film transistor of claim 1 , wherein
the second protective film is formed of at least one of silicon oxide, silicon nitride or silicon oxynitride.
4. A display device comprising the thin film transistor of claim 1 .
5. The display device of claim 4 , comprising an organic electroluminescence element.
6. The display device of claim 4 , comprising a liquid crystal layer.
7. The thin film transistor of claim 1 , wherein a top surface of the third protective film over the source region is closer to a top surface of the insulating substrate than a top surface of the third protective film over the gate electrode.