A semiconductor device is provided. The semiconductor device includes a substrate; an epitaxial layer; a first conductive type first well region disposed in the substrate and the epitaxial layer; a second conductive type first buried layer and a second conductive type second buried layer disposed at opposite sides of the first conductive type first well region, respectively; a first conductive type second well region disposed in the epitaxial layer and being in direct contact with the first conductive type first well region; a second conductive type third buried layer disposed in the first conductive type first well region and/or the first conductive type second well region; a second conductive type doped region disposed in the first conductive type second well region; a gate structure; a drain contact plug; and a source contact plug.

A semiconductor device comprises a bulk semiconductor substrate that includes a first conductivity type floating buried doped region bounded above by a second conductivity type doped region and bounded below by another second conductivity semiconductor region. Trench isolation regions extend through the second conductivity doped region and the first conductivity floating buried doped region into the semiconductor region. Functional devices are disposed within the second conductivity type doped region. The first conductivity type floating buried doped region is configured as a self-biased region that laterally extends between adjacent trench isolation regions.

A method of forming the semiconductor device that may include forming a trench in a substrate, and forming a metal nitride in the trench. The method may further include forming a split fin structure from the substrate. The metal nitride is positioned in the split portion of the fin structure. The method may continue with removing the metal nitride from a source region and drain region portion of the split fin structure, in which the metal nitride remains in a channel region portion of the split fin structure. A gate structure may then be formed on a channel region portion of the fin structure. A back bias is applied to the semiconductor device using the metal nitride in the split portion of the fin structure as an electrode.

A method of forming the semiconductor device that may include forming a trench in a substrate, and forming a metal nitride in the trench. The method may further include forming a split fin structure from the substrate. The metal nitride is positioned in the split portion of the fin structure. The method may continue with removing the metal nitride from a source region and drain region portion of the split fin structure, in which the metal nitride remains in a channel region portion of the split fin structure. A gate structure may then be formed on a channel region portion of the fin structure. A back bias is applied to the semiconductor device using the metal nitride in the split portion of the fin structure as an electrode.

Semiconductor devices and methods of fabricating such devices are provided. The devices include source and drain regions on one conductivity type separated by a channel length and a gate structure. The devices also include a channel region of the one conductivity type formed in the device region between the source and drain regions and a screening region of another conductivity type formed below the channel region and between the source and drain regions. In operation, the channel region forms, in response to a bias voltage at the gate structure, a surface depletion region below the gate structure, a buried depletion region at an interface of the channel region and the screening region, and a buried channel region between the surface depletion region and the buried depletion region, where the buried depletion region is substantially located in channel region.

A cascode switch structure includes a group III-V transistor structure having a first current carrying electrode, a second current carrying electrode and a first control electrode. A semiconductor MOSFET device includes a third current carrying electrode electrically connected to the second current carrying electrode, a fourth current carrying electrode electrically connected to the first control electrode, and a second control electrode. A first diode includes a first cathode electrode electrically connected to the first current carrying electrode and a first anode electrode. A second diode includes a second anode electrode electrically connected to the first anode electrode and a second cathode electrode electrically connected to the fourth current carrying electrode. In one embodiment, the group III-V transistor structure, the first diode, and the second diode are integrated within a common substrate.

In one embodiment, a cascode rectifier structure includes a group III-V semiconductor structure includes a heterostructure disposed on a semiconductor substrate. A first current carrying electrode and a second current carrying electrode are disposed adjacent a major surface of the heterostructure and a control electrode is disposed between the first and second current carrying electrode. A rectifier device is integrated with the group III-V semiconductor structure and is electrically connected to the first current carrying electrode and to a third electrode. The control electrode is further electrically connected to the semiconductor substrate and the second current path is generally perpendicular to a primary current path between the first and second current carrying electrodes. The cascode rectifier structure is configured as a two terminal device.

A semiconductor device and manufacturing method achieve miniaturization, prevent rise in threshold voltage and on-state voltage, and prevent decrease in breakdown resistance. N.sup.+-type emitter region and p.sup.++-type contact region are repeatedly alternately disposed in a first direction in which a trench extends in stripe form in a mesa portion sandwiched between trench gates. P.sup.+-type region covers an end portion on lower side of junction interface between n.sup.+-type emitter region and p.sup.++-type contact region. Formation of trench gate structure is such that n.sup.+-type emitter region is selectively formed at predetermined intervals in the first direction in the mesa portion by first ion implantation. P.sup.+-type region is formed less deeply than n.sup.+-type emitter region in the entire mesa portion by second ion implantation. The p.sup.++-type contact region is selectively formed inside the p+-type region by third ion implantation. N.sup.+-type emitter region and p.sup.++-type contact region are diffused and brought into contact.

A well of a first type of conductivity is formed in a semiconductor substrate, and wells of a second type of conductivity are formed in the well of the first type of conductivity at a distance from one another. By an implantation of dopants, a doped region of the second type of conductivity is formed in the well of the first type of conductivity between the wells of the second type of conductivity and at a distance from the wells of the second type of conductivity. Source/drain contacts are applied to the wells of the second type of conductivity, and a gate dielectric and a gate electrode are arranged above regions of the well of the first type of conductivity that are located between the wells of the second type of conductivity and the doped region of the second type of conductivity.

An integrated circuit containing a first plurality of MOS transistors operating in a low voltage range, and a second plurality of MOS transistors operating in a mid voltage range, may also include a high-voltage MOS transistor which operates in a third voltage range significantly higher than the low and mid voltage ranges, for example 20 to 30 volts. The high-voltage MOS transistor has a closed loop configuration, in which a drain region is surrounded by a gate, which is in turn surrounded by a source region, so that the gate does not overlap field oxide. The integrated circuit may include an n-channel version of the high-voltage MOS transistor and/or a p-channel version of the high-voltage MOS transistor. Implanted regions of the n-channel version and the p-channel version are formed concurrently with implanted regions in the first and second pluralities of MOS transistors.