A transistor device includes a substrate and a gate structure. The gate structure is disposed on the substrate. The gate structure includes a first metal layer and a refractory metal layer disposed on the first metal layer, wherein the first metal layer is disconnected and the refractory metal layer is disconnected.

A nitride semiconductor laminate includes: a substrate comprising a group III nitride semiconductor and including a surface and a reverse surface, the surface being formed from a nitrogen-polar surface, the reverse surface being formed from a group III element-polar surface and being provided on the reverse side from the surface; a protective layer provided at least on the reverse surface side of the substrate and having higher heat resistance than the reverse surface of the substrate; and a semiconductor layer provided on the surface side of the substrate and comprising a group III nitride semiconductor. The concentration of O in the semiconductor layer is lower than 1×10.sup.17 at/cm.sup.3.

A semiconductor device is made by: forming an ohmic electrode including Al on a semiconductor substrate; forming a SiN film covering the ohmic electrode; forming a first photoresist on the SiN film, the first photoresist having an opening pattern overlapping the ohmic electrode; performing ultraviolet curing of the first photoresist; forming an opening in the SiN film exposed through the opening pattern and causing a surface of the ohmic electrode to be exposed inside the opening; forming a barrier metal layer on the first photoresist and on the ohmic electrode exposed through the opening; forming a second photoresist in the opening pattern; performing a heat treatment on the second photoresist and covering the barrier metal layer overlapping the opening with the second photoresist; and etching the barrier metal layer using the second photoresist.

Disclosed is a nitride semiconductor apparatus including a substrate, a first nitride semiconductor layer disposed above the substrate, and constituting an electron transit layer, a second nitride semiconductor layer formed on the first nitride semiconductor layer, and constituting an electron supply layer, a nitride semiconductor gate layer disposed on the second nitride semiconductor layer having a ridge portion at at least an area thereof, and containing an acceptor-type impurity, a gate electrode disposed on the ridge portion, a source electrode and a drain electrode disposed opposite to each other, with the ridge portion interposed therebetween, on the second nitride semiconductor layer, and a strip-shaped insulator disposed between the substrate and a surface layer portion of the first nitride semiconductor layer, and extending along a length direction of the ridge portion when viewed in plan.

A semiconductor device includes a transistor, a semiconductor layer, an active region and a conductive layer. The active region is in the semiconductor layer. The conductive layer is configured to maintain a channel in the active region when the transistor is triggered to be conducted.

A nitride semiconductor device includes an electron transit layer, an electron supply layer that is formed on the electron transit layer, a gate layer that is formed on the electron supply layer and contains an Al.sub.1-xGa.sub.xN (0 < × < 1) based material containing a first impurity, a gate electrode that is formed on the gate layer and is in Schottky junction with the gate layer, and a source electrode and a drain electrode that are electrically connected to the electron supply layer. By this arrangement, a gate withstand voltage can be improved and therefore, a nitride semiconductor device of high reliability can be provided.

The present invention provides an epitaxial structure of N-face group III nitride, its active device, and the method for fabricating the same. By using a fluorine-ion structure in device design, a 2DEG in the epitaxial structure of N-face group III nitride below the fluorine-ion structure will be depleted. Then the 2DEG is located at a junction between a i-GaN channel layer and a i-Al.sub.yGaN layer, and thus fabricating GaN enhancement-mode AlGaN/GaN high electron mobility transistors (HEMTs), hybrid Schottky barrier diodes (SBDs), or hybrid devices. After the fabrication step for polarity inversion, namely, generating stress in a passivation dielectric layer, the 2DEG will be raised from the junction between the i-GaN channel layer and the i-Al.sub.yGaN layer to the junction between the i-GaN channel layer and the i-Al.sub.xGaN layer.

A high electron mobility transistor (HEMT) includes a semiconductor channel layer, a semiconductor barrier layer, a patterned semiconductor capping layer, and a patterned semiconductor protection layer disposed on a substrate in sequence. The HEMT further includes an interlayer dielectric layer and a gate electrode. The interlayer dielectric layer covers the patterned semiconductor capping layer and the patterned semiconductor protection layer, and includes a gate contact hole. The gate electrode is disposed in the gate contact hole and electrically coupled to the patterned semiconductor capping layer, where the patterned semiconductor protection layer is disposed between the gate electrode and the patterned semiconductor capping layer. The resistivity of the patterned semiconductor protection layer is between the resistivity of the patterned semiconductor capping layer and the resistivity of the interlayer dielectric layer.

A semiconductor device structure comprises a region of semiconductor material comprising a first conductivity type, a first major surface, and a second major surface opposite to the first major surface. A first trench gate structure includes a first trench extending from the first major surface into the region of semiconductor material, a first dielectric structure is over sidewall surfaces and a portion of a lower surface of the first trench, wherein the first dielectric structure comprises a first opening adjacent to the lower surface of the first trench, a first recessed contact extends through the first opening, and a first contact region is over the first recessed contact within the first trench, wherein the first recessed contact and the first contact region comprise different materials. A first doped region comprising a second dopant conductivity type opposite to the first conductivity type is in the region of semiconductor material and is spaced apart from the first major surface and below the first trench. A gate contact region is in the region of semiconductor material and is electrically connected to the first doped region.

In one embodiment, an apparatus includes a source region, a drain region, a channel between the source and drain regions, and a polarization layer on the channel. The channel includes gallium and nitrogen, and the polarization layer includes a group III-nitride (III-N) material. The apparatus further includes a gate structure having a first region and a second region. The first region extends into the polarization layer and includes a metal. The second region is coupled to the first region and includes a polycrystalline semiconductor material.