A semiconductor device including: a first silicon level including a first single crystal silicon layer and a plurality of first transistors; a first metal layer disposed over the first silicon level; a second metal layer disposed over the first metal layer; a third metal layer disposed over the second metal layer; a second level including a plurality of second transistors, the second level disposed over the third metal layer; a fourth metal layer disposed over the second level; a fifth metal layer disposed over the fourth metal layer, where the fourth metal layer is aligned to the first metal layer with a less than 40 nm alignment error; a via disposed through the second level, where each of the second transistors includes a metal gate, where a typical thickness of the second metal layer is greater than a typical thickness of the third metal layer by at least 50%.

A semiconductor device including: a first silicon level including a first single crystal silicon layer and a plurality of first transistors; a first metal layer disposed over the first silicon level; a second metal layer disposed over the first metal layer; a third metal layer disposed over the second metal layer; a second level including a plurality of second transistors, the second level disposed over the third metal layer; a fourth metal layer disposed over the second level; a fifth metal layer disposed over the fourth metal layer, where the fourth metal layer is aligned to the first metal layer with a less than 40 nm alignment error; a via disposed through the second level, where each of the second transistors includes a metal gate, where a typical thickness of the second metal layer is greater than a typical thickness of the third metal layer by at least 50%.

A nitride semiconductor device is provided that includes: a substrate; an n-type drift layer above the front surface of the substrate; a p-type base layer above the n-type drift layer; a gate opening in the base layer that reaches the drift layer; an n-type channel forming layer that covers the gate opening and has a channel region; a gate electrode above a section of the channel forming layer in the gate opening; an opening that is separated from the gate electrode and reaches the base layer; an opening formed in a bottom surface of said opening and reaching the drift layer; a source electrode covering the openings; and a drain electrode on the rear surface of the substrate.

A nitride semiconductor device is provided that includes: a substrate; an n-type drift layer above the front surface of the substrate; a p-type base layer above the n-type drift layer; a gate opening in the base layer that reaches the drift layer; an n-type channel forming layer that covers the gate opening and has a channel region; a gate electrode above a section of the channel forming layer in the gate opening; an opening that is separated from the gate electrode and reaches the base layer; an opening formed in a bottom surface of said opening and reaching the drift layer; a source electrode covering the openings; and a drain electrode on the rear surface of the substrate.

A semiconductor device includes a source electrode and a drain electrode located over a surface of a semiconductor layer including an electron transit layer and an electron supply layer. A gate electrode is located between the source electrode and the drain electrode. A first diamond layer is located between the source electrode and the drain electrode over the surface with an insulating film therebetween. A second diamond layer is located directly on the surface between the gate electrode and the drain electrode. Of heat generated by the semiconductor layer of the semiconductor device in operation, heat on the side of the electrode on which a relatively strong electric field is applied is efficiently transferred to the second diamond layer. The semiconductor device achieves an excellent heat dissipation property from the semiconductor layer and effectively suppresses overheating and a failure and degradation of the characteristics due to the overheating.

A nitride semiconductor device includes: a substrate of a first conductivity type having a first surface and a second surface on a side of the substrate opposite the first surface; a first nitride semiconductor layer of the first conductivity type which is disposed on the first surface of the substrate and includes an acceptor impurity; a second nitride semiconductor layer of a second conductivity type disposed on the first nitride semiconductor layer, the second conductivity type being opposite to the first conductivity type; a first electrode disposed on the second surface of the substrate; a second electrode disposed on the first nitride semiconductor layer; and a gate electrode disposed on the second nitride semiconductor layer.

A nitride semiconductor device includes: a substrate of a first conductivity type having a first surface and a second surface on a side of the substrate opposite the first surface; a first nitride semiconductor layer of the first conductivity type which is disposed on the first surface of the substrate and includes an acceptor impurity; a second nitride semiconductor layer of a second conductivity type disposed on the first nitride semiconductor layer, the second conductivity type being opposite to the first conductivity type; a first electrode disposed on the second surface of the substrate; a second electrode disposed on the first nitride semiconductor layer; and a gate electrode disposed on the second nitride semiconductor layer.

A semiconductor film, a sheet like object, and a semiconductor device are provided that have inhibited semiconductor properties, particularly leakage current, and excellent withstand voltage and heat dissipation. A crystalline semiconductor film or a sheet like object includes a corundum structured oxide semiconductor as a major component, wherein the film has a film thickness of 1 μm or more. Particularly, the semiconductor film or the object includes a semiconductor component of oxide of one or more selected from gallium, indium, and aluminum as a major component. A semiconductor device has a semiconductor structure including the semiconductor film or the object.

A semiconductor film, a sheet like object, and a semiconductor device are provided that have inhibited semiconductor properties, particularly leakage current, and excellent withstand voltage and heat dissipation. A crystalline semiconductor film or a sheet like object includes a corundum structured oxide semiconductor as a major component, wherein the film has a film thickness of 1 μm or more. Particularly, the semiconductor film or the object includes a semiconductor component of oxide of one or more selected from gallium, indium, and aluminum as a major component. A semiconductor device has a semiconductor structure including the semiconductor film or the object.

A Field Effect Transistor including: a channel with one end designated the source and the other end designated the drain; a means for connecting to said source end of said channel; a means for connecting to said drain end of said channel; a gate divided into a plurality of segments each insulated from one another; a means for adjusting the bias of each of said segments independently of one another, whereby the depletion region in said channel can be adjusted to avoid pinch-off and to maximize the efficiency of said Field Effect Transistor.