Patent ID: 8592811

Claim:
An active matrix substrate comprising: a plurality of pixel electrodes arranged in a matrix; and a plurality of thin film transistors each connected to a corresponding one of the pixel electrodes, and each including a gate electrode provided on an insulating substrate, a gate insulating film covering the gate electrode, a semiconductor layer provided on the gate insulating film and having a channel region overlapping the gate electrode, and a source electrode and a drain electrode of copper or copper alloy provided on the gate insulating film and separated from each other by the channel region of the semiconductor layer, wherein the semiconductor layer is formed of an oxide semiconductor and covers the source and drain electrodes, an interlayer insulating film of a silicon oxide film is provided to cover each of the thin film transistors, each of the pixel electrodes is provided on the interlayer insulating film, and is connected to the drain electrode of a corresponding one of the thin film transistors via a contact hole formed in the interlayer insulating film and a contact hole formed in the semiconductor layer, and the contact hole formed in the interlayer insulating film is larger than the contact hole formed in the semiconductor layer as viewed from above, and a step-like portion is provided between an inner wall of the contact hole formed in the interlayer insulating film and an inner wall of the contact hole formed in the semiconductor layer.