Display device and manufacturing method thereof

A method of manufacturing a display device, the method comprising:

• preparing a first substrate having a display area and a non-display area;
• forming a gate line in the display area and forming a gate pad in the non-display area;
• forming a data line in the display area, the data line intersecting the gate line;
• forming a thin film transistor connected to the gate line and the data line;
• forming a step-difference pattern on the gate pad;
• and
• forming a protective layer comprising forming a first protective layer on the thin film transistor and forming a second protective layer on the step-difference pattern and the gate pad, the second protective layer having a protective-layer contact hole extending to the gate pad,
• wherein the second protective layer has a height less than a height of the first protective layer;
• and the second protective layer on the step-difference pattern has a height greater than a height of the second protective layer on the gate pad.