Active matrix substrate having thin film transistors that each include copper gate electrode and oxide semiconductor layer

Abstract

An active matrix substrate includes a gate metal layer including a plurality of gate bus lines, and a thin film transistor arranged in each pixel region, wherein: the thin film transistor includes a gate electrode, an oxide semiconductor layer arranged on the gate electrode with a gate insulating layer interposed therebetween, wherein the gate electrode is formed in the gate metal layer and is electrically connected to a corresponding one of the plurality of gate bus lines, the gate metal layer has a layered structure including a copper alloy layer and a copper layer arranged on the copper alloy layer, wherein the copper alloy layer is of a copper alloy including Cu and at least one additive metal element, wherein the additive metal element includes Al, and an Al content of the copper alloy is 2 at % or more and 8 at % or less.