Display device and method of manufacturing display device

A display device comprising:

• a substrate including a display area and a non-display area around the display area;
• a first insulating layer disposed on the substrate;
• a second insulting layer disposed on the second insulating layer;
• a first semiconductor layer disposed on the second insulating layer;
• a third insulating layer on the first semiconductor layer;
• a first gate electrode on the third insulating layer;
• a fourth insulating layer disposed on the first gate electrode;
• a second gate electrode on the fourth insulating layer;
• a fifth insulating layer on the second gate electrode;
• a sixth insulating layer on the fifth insulating layer;
• a seventh insulating layer on the sixth insulating layer;
• a second semiconductor layer on the seventh insulating layer;
• an eighth insulating layer on the second semiconductor layer;
• a third gate electrode on the eighth insulating layer;
• a ninth insulating layer on the third gate electrode;
• a first source electrode or a second drain electrode on the nineth insulating layer;
• and
• a third source electrode or a fourth drain electrode on the nineth insulating layer, wherein
• a material of the sixth insulating layer is different from a material of the seventh insulating layer.
• the first source or the second drain electrode is electrically connected to the first semiconductor layer, and
• the third source electrode or the fourth drain electrode is electrically connected to the second semiconductor layer.