Thin film transistor element substrate, method of producing the substrate, and organic EL display device including the thin film transistor element substrate
The thin film transistor element substrate of the present disclosure includes a first moisture barrier layer covering the gate insulating layer and the gate electrode, covering the contact regions of the oxide semiconductor layer other than the connecting portion of the contact region connected to the source electrode and the connecting portion of the contact region connected to the drain electrode, and covering an surface of the substrate on which the oxide semiconductor layer is not disposed. The first moisture barrier layer includes a metal oxide and is formed by atomic layer deposition. The first moisture barrier layer formed by atomic layer deposition is in contact with a pair of contact regions.
1. A method of producing an organic EL display device, comprising:
forming a thin film transistor element including:
forming an oxide semiconductor layer above a part of a substrate in a first direction;
forming a gate insulating layer above a channel region of the oxide semiconductor layer in the first direction;
forming a gate electrode above the gate insulating layer in the first direction;
forming a first moisture barrier layer containing a metal oxide by atomic layer deposition to cover and directly contact i) contact regions extending on both sides of the channel region of the oxide semiconductor layer in a second direction orthogonal to the first direction, and ii) the gate electrode;
forming a first contact hole and a second contact hole in the first moisture barrier layer, each of the first contact hole and the second contact hole penetrating the first moisture barrier layer and reaching the oxide semiconductor layer;
forming a source electrode above the first moisture barrier layer to directly cover and contact an area of the first moisture barrier layer surrounding the first contact hole and be connected to the oxide semiconductor layer through the first contact hole; and
forming a drain electrode above the first moisture barrier layer to directly cover and contact an area of the first moisture barrier layer surrounding the second contact hole and be connected to the oxide semiconductor layer through the second contact hole; and
forming an organic EL element above the first moisture barrier layer of the thin film transistor element, the organic EL element including a light emitting layer, a cathode and an anode, wherein:
the substrate includes a second moisture barrier layer, and
an end section of the cathode is located closer to the gate electrode than an end section of the first moisture barrier layer and an end section of the second moisture barrier layer.
2. The method according to claim 1 , wherein:
the substrate includes a resin substrate mainly made of a resin material and the second moisture barrier layer is above the resin substrate, and
the second moisture barrier layer is in contact with the first moisture barrier layer.
3. The method according to claim 2 , wherein:
the second moisture barrier layer is formed by one of chemical vapor deposition or atomic layer deposition.
4. The method according to claim 2 , wherein:
the metal oxide included in the first moisture barrier layer is different from a metal oxide included in the second moisture barrier layer.
5. The method according to claim 2 , wherein:
the first moisture barrier layer includes an oxide of aluminum, and
the second moisture barrier layer includes an oxide of zirconium.
6. The method according to claim 1 , wherein the contact regions have different electrical resistances from the channel region.
7. A method of producing an organic EL display device comprising:
forming an oxide semiconductor layer above a part of a substrate in a first direction;
forming a gate insulating layer above a channel region of the oxide semiconductor layer in the first direction;
forming a gate electrode above the gate insulating layer in the first direction;
forming a first moisture barrier layer containing a metal oxide by atomic layer deposition to cover and directly contact i) contact regions extending on both sides of the channel region of the oxide semiconductor layer in a second direction orthogonal to the first direction and ii) the gate electrode; and
forming an organic EL element above the first moisture barrier layer, the organic EL element including a light emitting layer, a cathode and an anode, wherein:
the substrate includes a second moisture barrier layer, and
an end section of the cathode is located closer to the gate electrode than an end section of the first moisture barrier layer and an end section of the second moisture barrier layer.
8. The method according to claim 7 , wherein the contact regions have different electrical resistances from the channel region.