A semiconductor device having: a substrate; a nitride semiconductor layer including a first semiconductor layer made of GaN or In.sub.xGa.sub.1-xN (0<x≦1) and formed on the substrate and a second semiconductor layer containing Al and formed on the first semiconductor layer; and a protective film formed on the set of nitride semiconductor layers. The nitride semiconductor layer has an active section and an inactive section surrounding the active section, and a portion of the second semiconductor layer has been removed from the inactive section.

A method of manufacturing an electrode structure for a device, such as a GaN or AlGaN device is described. In one example, the method includes providing a substrate (212) of GaN or AlGaN with a surface region of the GaN or AlGaN exposed through an opening (216) in a layer of silicon nitride (214) formed on the substrate. The method further includes depositing layers of W (222), in one example, or Ni (220) and W (222), in another example, on the substrate and the layer of silicon nitride using reactive evaporation and photoresist layers (230) having an undercut profile for liftoff. The method further includes removing the photoresist layers having the undercut profile, and depositing layers of WN (224) and Al over the underlying layers of W or Ni and W by sputtering.

A semiconductor structure and a method of fabricating therefor are disclosed. A second contact pad (500) is arranged lateral to a first contact pad (420) in an interconnect structure (400). As a result, during fabrication of the interconnect structure (400), the first contact pad (420) will not be present alone in a large bland area, due to the presence of the second contact pad (500). Thus, a pattern feature for the first contact pad (420) will not be over-resolved, increasing formation accuracy of the first contact pad (420) and thus guaranteeing good electrical transmission performance of the resulting interconnect structure (400).

Because of inclusion of: a source electrode that is formed on a front surface of a semiconductor substrate and that is joined to the semiconductor substrate both at a source electrode as a first contact region that is an ohmic contact region and at a source electrode as a second contact region that is a contact region with a non-ohmic contact or the like; a back-surface electrode formed on a back surface of the semiconductor substrate; and a through hole in which an interconnection is provided that connects the source electrode as the second contact region in the source electrode with the back-surface electrode; it is possible not only to improve the corrosion resistance but also to reduce the leakage current, so that a highly-reliable semiconductor device suited for high frequency operation is provided.

A high-frequency transistor includes a source electrode, a drain electrode, a gate electrode, and a gate drive line that applies a voltage to the gate electrode. An impedance adjustment circuit is connected between the gate electrode and the gate drive line. A characteristic impedance of the gate electrode is Z1, when a connecting point between the impedance adjustment circuit and the gate electrode is viewed from the impedance adjustment circuit. A characteristic impedance of the gate drive line is Z2, when a connecting point between the impedance adjustment circuit and the gate drive line is viewed from the impedance adjustment circuit. X that denotes a characteristic impedance of the impedance adjustment circuit is a value between Z1 and Z2.

A method to form a 3D integrated circuit, the method including: providing a first wafer including a first crystalline substrate, a plurality of first transistors, and first copper interconnecting layers, where the first copper interconnecting layers at least interconnect the plurality of first transistors; providing a second wafer including a second crystalline substrate, a plurality of second transistors, and second copper interconnecting layers, where the second copper interconnecting layers at least interconnect the plurality of second transistors; and then performing a face-to-face bonding of the second wafer on top of the first wafer, where the face-to-face bonding includes copper to copper bonding; and thinning the second crystalline substrate to a thickness of less than 5 micro-meters.

A nitride semiconductor device 1 includes a first nitride semiconductor layer that constitutes an electron transit layer, a second nitride semiconductor layer that is formed on the first nitride semiconductor layer, is larger in bandgap than the first nitride semiconductor layer, and constitutes an electron supply layer, a gate portion that is formed on the second nitride semiconductor layer, and a source electrode and a drain electrode that, on the second nitride semiconductor layer, are opposingly disposed across the gate portion. The gate portion includes a third nitride semiconductor layer of a ridge shape that is formed on the second nitride semiconductor layer and contains an acceptor type impurity and a gate electrode that is formed on the third nitride semiconductor layer. A film thickness of the third nitride semiconductor layer is greater than 100 nm.

A nitride semiconductor device 1 includes a first nitride semiconductor layer that constitutes an electron transit layer, a second nitride semiconductor layer that is formed on the first nitride semiconductor layer, is larger in bandgap than the first nitride semiconductor layer, and constitutes an electron supply layer, a gate portion that is formed on the second nitride semiconductor layer, and a source electrode and a drain electrode that, on the second nitride semiconductor layer, are opposingly disposed across the gate portion. The gate portion includes a third nitride semiconductor layer of a ridge shape that is formed on the second nitride semiconductor layer and contains an acceptor type impurity and a gate electrode that is formed on the third nitride semiconductor layer. A film thickness of the third nitride semiconductor layer is greater than 100 nm.

In an embodiment, a Group III nitride-based transistor device is provided that includes a Group III nitride-based body and a p-type Schottky gate including a metal gate on a p-doped Group III nitride structure. The p-doped Group III nitride structure includes an upper p-doped GaN layer in contact with the metal gate and having a thickness d.sub.1, a lower p-doped Group III nitride layer having a thickness d.sub.2 and including p-doped GaN that is arranged on and in contact with the Group III nitride-based body, and at least one p-doped Al.sub.xGa.sub.1-xN layer arranged between the upper p-doped GaN layer and the lower p-doped Group III nitride layer, wherein 0<x<1. The thickness d.sub.2 of the lower p-doped Group III nitride layer is larger than the thickness d.sub.1 of the upper p-doped GaN layer.

In an embodiment, a Group III nitride-based transistor device is provided that includes a Group III nitride-based body and a p-type Schottky gate including a metal gate on a p-doped Group III nitride structure. The p-doped Group III nitride structure includes an upper p-doped GaN layer in contact with the metal gate and having a thickness d.sub.1, a lower p-doped Group III nitride layer having a thickness d.sub.2 and including p-doped GaN that is arranged on and in contact with the Group III nitride-based body, and at least one p-doped Al.sub.xGa.sub.1-xN layer arranged between the upper p-doped GaN layer and the lower p-doped Group III nitride layer, wherein 0<x<1. The thickness d.sub.2 of the lower p-doped Group III nitride layer is larger than the thickness d.sub.1 of the upper p-doped GaN layer.