Display device
Even when a light shielding film is provided between a transistor and a substrate, a threshold voltage of the transistor can be prevented or suppressed from being shifted. A display device includes light shielding films provided between a substrate and a semiconductor layer of a transistor including a gate electrode and the semiconductor layer. The semiconductor layer includes a source region and a drain region. Both of the light shielding films overlap the semiconductor layer when seen in a plan view, and are spaced apart from each other in a direction.
1. A display device comprising:
a transparent substrate;
a plurality of thin film transistors provided in the transparent substrate;
a source electrode and a drain electrode formed above or below a semiconductor layer via an insulating film;
a first contact hole for connecting the semiconductor layer and the source electrode, a second contact hole for connecting the semiconductor layer and the drain electrode; and
a first light shielding film and a second light shielding film provided between the plurality of thin film transistors and the transparent substrate,
wherein each thin film transistor includes:
a semiconductor layer; and
a first gate electrode and a second gate electrode formed above or below the semiconductor layer via an insulating film,
the first light shielding film overlaps with the semiconductor layer in a plan view from a part of the first gate electrode to the first contact hole, and the second light shielding film overlaps with the semiconductor layer in a plan view from a part of the second gate electrode to the second contact hole,
wherein the semiconductor layer includes, in a plan view:
a source region formed in a first portion of the semiconductor layer which is positioned on an opposite side to the second gate electrode across the first gate electrode when seen in a plan view,
a drain region formed in a second portion of the semiconductor layer which is positioned on an opposite side to the first gate electrode across the second gate electrode when seen in a plan view,
a first semiconductor region formed in a third portion which is positioned between the first gate electrode and the source region, and
a second semiconductor region formed in a fourth portion which is positioned between the second gate electrode and the drain region,
the first light shielding film includes a first end portion on the source electrode side and a second end portion on the drain electrode side, and the second light shielding film includes a third end portion on the source electrode side and a fourth end portion on the drain electrode side,
a distance from the first end portion of the first light shielding film to an overlapping region with the first semiconductor region is L 1 in the plan view, and an interlayer distance from the first light shielding film to the semiconductor layer is H 1 , the distance L 1 is formed to be equal to or greater than the interlayer distance H 1 ,
a distance from the fourth end portion of the second light shielding film to an overlapping region with the second semiconductor region is L 2 in the plan view, and an interlayer distance from the second light shielding film to the semiconductor layer is H 1 , the distance L 2 is formed to be equal to or greater than the interlayer distance H 1 .
2. The display device according to claim 1 , wherein
the first gate electrode has a first end portion on the source electrode side and a second end portion on the drain electrode side, and the second gate electrode has a third end portion on the source electrode side and a fourth end portion on the drain electrode side,
the first end portion of the first gate electrode is arranged on the first light shielding film,
the second end portion of the first gate electrode is not arranged on the first light shielding film,
the third end portion of the second gate electrode is not arranged on the second light shielding film, and
the fourth end portion of the second gate electrode is arranged on the second light shielding film.
3. The display device according to claim 1 ,
the first gate electrode and the second gate electrode are spaced apart from each other when seen in a plan view.
4. The display device according to claim 1 ,
the source region is formed by introducing impurities of a first conductivity type into the first portion of the semiconductor layer,
the drain region is formed by introducing the impurities of the first conductivity type into the second portion of the semiconductor layer,
the first semiconductor region is formed by introducing the impurities of the first conductivity type into the third portion of the semiconductor layer,
the second semiconductor region is formed by introducing the impurities of the first conductivity type into the fourth portion of the semiconductor layer,
a concentration of the impurities of the first conductivity type in the first semiconductor region is lower than a concentration of the impurities of the first conductivity type in the source region, and
a concentration of the impurities of the first conductivity type in the second semiconductor region is lower than a concentration of the impurities of the first conductivity type in the drain region.
5. The display device according to claim 4 ,
wherein the first semiconductor region is arranged in a region where the first light shielding film is formed when seen in a plan view, and
the second semiconductor region is arranged in a region where the second light shielding film is formed when seen in a plan view.
6. The display device according to claim 1 ,
wherein each of the first light shielding film and the second light shielding film is formed of a metal film or an alloy film.
7. The display device according to claim 6 ,
wherein each of the first light shielding film and the second light shielding film is in an electrically floating state.