Double-channel HEMT device and manufacturing method thereof

A method of manufacturing of a high-electron-mobility transistor (HEMT) device, comprising:

• forming a heterojunction structure in a semiconductor body, the heterojunction structure including a channel layer, defining a main conductive channel of the HEMT device, and a barrier layer over the channel layer;
• forming an insulation layer on barrier layer;
• forming a gate region, including forming a conductive gate electrode and a gate dielectric that insulates electrically the conductive gate electrode from the semiconductor body;
• forming a drain electrode and a source electrode aligned with one another and with the gate electrode in a direction, wherein the drain electrode is formed facing a first side of the gate region, and the source electrode is formed facing a second side, opposite to the first side in said direction, of the gate region,
• forming an auxiliary channel layer on the barrier layer, in the insulation layer, and between the gate region and the drain electrode, the auxiliary channel layer being spaced apart from the gate electrode of the gate region by the gate dielectric and the insulation layer and is coplanar with a portion of the insulation layer on the barrier layer, the auxiliary channel layer forming a conductive path, additional to the main conductive channel, for charge carriers to flow between the source electrode and the drain electrode.

A high-electron-mobility transistor (HEMT) device, comprising:

• a semiconductor body including a heterojunction structure that includes a channel layer, which forms a main conductive channel of the HEMT device, and a barrier layer over the channel layer;
• a dielectric layer on the barrier layer;
• a gate structure, a drain electrode, and a source electrode that extend into the dielectric layer, the gate structure including a gate electrode and a gate dielectric layer, wherein the drain electrode faces a first side of the gate electrode, and the source electrode faces a second side, opposite to the first side, of the gate electrode;
• and
• an auxiliary channel layer, which extends in the dielectric layer, and over the barrier layer, between the gate electrode and the drain electrode, is in electrical contact with the drain electrode, is spaced apart from the gate electrode by a portion of the dielectric layer and the gate dielectric layer, and forms a conductive path additional to the main conductive channel for charge carriers to flow between the source electrode and the drain electrode, the auxiliary channel layer being coplanar with the portion of the dielectric layer and both the auxiliary channel layer and the dielectric layer contact a top surface of the barrier layer.