Thin film transistor substrate and liquid crystal display device provided with same

A thin film transistor substrate comprising:

• a substrate;
• a gate insulating film which is located to cover a gate electrode provided on the substrate;
• a thin film transistor, including:
• the gate electrode,
• a portion of the gate insulating film,
• an oxide semiconductor film provided on the gate insulating film and including a channel section located at a position opposing the gate electrode, and
• a source section and a drain section spaced apart from each other with the channel section sandwiched therebetween;
• a protective film which is provided to cover the thin film transistor and which includes a pixel contact hole extending to the drain section;
• and
• a pixel electrode provided on the protective film and directly electrically connected to the drain section by directly contacting the drain section within the pixel contact hole, wherein
• the source section is defined by metal layer positioned above both the gate insulating film and the oxide semiconductor film,
• the drain section is defined by only a low resistance area of the oxide semiconductor film including a surface of the oxide semiconductor film opposite to the gate insulating film, a resistance of the low resistance area is reduced as compared to other remaining portions of the oxide semiconductor film, and
• the low resistance area is provided at the pixel contact hole and has a total thickness which is ½ or less of a total thickness of an entirety of the oxide semiconductor film.