Active matrix substrate and method for producing same

Abstract

An oxide semiconductor TFT () of an active matrix substrate includes an oxide semiconductor layer (), an upper gate electrode () disposed on a part of the oxide semiconductor layer via a gate insulating layer, and a source electrode () and a drain electrode (). As viewed from a normal direction of the substrate, the oxide semiconductor layer () includes a first portion (p) that overlaps the upper gate electrode, and a second portion (p) that is located between the first portion and the source contact region or drain contact region, such that the gate insulating layer does not cover the second portion. The upper gate electrode () has a multilayer structure including an alloy layer (L) that is in contact with the gate insulating layer and a metal layer (U) that is disposed on the alloy layer. The metal layer is made of a first metallic element M; the alloy layer is made of an alloy containing the first metallic element M; and the first metallic element M is Cu, Mo, or Cr.