TFT substrate, TFT substrate production method, and display device

A method of producing a Thin Film Transistor (TFT) substrate, comprising the step of:

• (a) providing the following on a substrate:
• a first semiconductor film which serves as a channel of a TFT;
• a first electrically conductive member provided in a layer higher than the first semiconductor film;
• an interlayer insulating film which is provided in a layer higher than the first electrically conductive member and has a first through hole;
• a second semiconductor film provided in a layer higher than the interlayer insulating film;
• a second electrically conductive member provided in a layer higher than the second semiconductor film;
• an organic insulating film which is provided in a layer higher than the second electrically conductive member and has a second through hole;
• a third electrically conductive member provided in a layer higher than the organic insulating film;
• and
• a contact hole which has an end extending through the first through hole and the second through hole to the first electrically conductive member,
• wherein in the step (a), an entrance to the second through hole is formed so as to be larger than an entrance to the first through hole, and the second electrically conductive member and the third electrically conductive member are provided in a manner so as to overlap with an entrance to the contact hole, so that the third electrically conductive member is in contact with the first electrically conductive member and the second electrically conductive member;
• and
• the contact hole extends through a third through hole of the second semiconductor film.