A display device includes a gate pattern, a semiconductor pattern, a source pattern and a pixel electrode are provided. The gate pattern is formed on a base substrate and includes a gate line and a gate electrode. The semiconductor pattern is formed on the base substrate having the gate pattern and includes an oxide semiconductor. The source pattern is formed from a data metal layer and formed on the base substrate having the semiconductor pattern, and includes a data line, a source electrode and a drain electrode. The data metal layer includes a first copper alloy layer, and a lower surface of the data metal layer substantially coincides with an upper surface of the semiconductor pattern. The pixel electrode is formed on the base substrate having the source pattern and electrically connected to the drain electrode. Thus, manufacturing processes may be simplified, and reliability may be improved.