High electron mobility transistor and fabrication method thereof

A high electron mobility transistor (HEMT), comprising:

• a group III-V channel layer, disposed on a substrate;
• a passivation layer, disposed on the group III-V channel layer and comprising a gate contact hole and at least one source/drain contact hole;
• a group III-V barrier layer, disposed between the group III-V channel layer and the passivation layer;
• a gate structure, comprising a group III-V gate layer, a gate etch stop layer, and a gate electrode being sequentially stacked, wherein the gate electrode is disposed in the gate contact hole and directly covers a portion of a top surface of the passivation layer;
• at least one source/drain electrode, disposed in the source/drain contact hole and directly covering another portion of the top surface of the passivation layer, wherein the gate electrode and the least one source/drain electrode are formed from the same layer, and a composition of the gate electrode is the same as a composition of the at least one source/drain electrode;
• and
• an interlayer dielectric, covering the passivation layer, the gate electrode, and the at least one source/drain electrode, and the interlayer dielectric being filled into the gate contact hole and the at least one source/drain contact hole.