An organic light emitting diode display is disclosed. The organic light emitting diode display includes: a substrate including a first region and a second region, a first gate electrode formed over the first region, a second gate electrode formed over the second region, a first gate insulator formed on the first gate electrode, a second gate insulator formed on the second gate electrode, a first semiconductor layer formed on the first gate insulator, the first semiconductor layer including a first channel region, a second semiconductor layer formed on the second gate insulator, the second semiconductor layer including a second channel region, an interlayer insulator formed over the substrate and over at least part of the first and second semiconductor layers, a first etching stop layer formed over the first channel region and surrounded by the interlayer insulator, a second etching stop layer formed over the second channel region and surrounded by the interlayer insulator, a first source electrode and a first drain electrode contacting the first semiconductor layer through the interlayer insulator, and a second source electrode and a second drain electrode contacting the second semiconductor layer through the interlayer insulator.