A semiconductor device may include a semiconductor fin, a source/drain region extending from the semiconductor fin, and a gate electrode over the semiconductor fin. The semiconductor fin may include a first well and a channel region over the first well. The first well may have a first dopant at a first dopant concentration and the channel region may have the first dopant at a second dopant concentration smaller than the first dopant concentration. The first dopant concentration may be in range from 10.sup.17 atoms/cm.sup.3 to 10.sup.19 atoms/cm.sup.3.

Example embodiments relate to a field-effect transistors having improved layouts. One example field-effect transistor includes a semiconductor substrate on which at least one transistor cell array is arranged. Each transistor cell includes a first transistor cell unit. Each first transistor cell unit includes a plurality of gate fingers, a main gate finger segment, a plurality of drain fingers, and a main drain finger segment. Each first transistor cell unit also includes a main gate finger base connected to the main gate finger segment of the first transistor cell unit and extending from that main gate finger segment towards the main drain finger segment of that first transistor cell unit. Further, each first transistor cell unit includes a main drain finger base connected to the main drain finger segment of that first transistor cell and extending from that main drain finger segment towards that main gate finger segment.

In a method of manufacturing a semiconductor device, first and second gate structures are formed. The first (second) gate structure includes a first (second) gate electrode layer and first (second) sidewall spacers disposed on both side faces of the first (second) gate electrode layer. The first and second gate electrode layers are recessed and the first and second sidewall spacers are recessed, thereby forming a first space and a second space over the recessed first and second gate electrode layers and first and second sidewall spacers, respectively. First and second protective layers are formed in the first and second spaces, respectively. First and second etch-stop layers are formed on the first and second protective layers, respectively. A first depth of the first space above the first sidewall spacers is different from a second depth of the first space above the first gate electrode layer.

Bipolar junction transistor (BJT) structures are provided. A BJT structure includes a semiconductor substrate, a collector region formed in the semiconductor substrate, a base region formed over the collector region, an emitter region formed over the collector region, a ring-shaped shallow trench isolation (STI) region formed in the collector region, and a base dielectric layer formed over the collector region and on opposite sides of the base region. The base dielectric layer is surrounded by an inner side wall of the ring-shaped STI region.

A FinFET including a gate stack, a semiconductor fin embedded in the gate stack, a source and a drain disposed is provided. The semiconductor fin extends along a widthwise direction of the gate stack and has a first concave and a second concave exposed at sidewalls of the gate stack respectively. The source and drain are disposed at two opposite sides of the gate stack. The source includes a first portion in contact with and embedded in the first concave. The drain includes a second portion in contact with and embedded in the second concave. The first portion and the second portion are covered by the gate stack.

Gates having air gaps therein, and methods of fabrication thereof, are disclosed herein. An exemplary gate includes a gate electrode and a gate dielectric. A first air gap is between and/or separates a first sidewall of the gate electrode from the gate dielectric, and a second air gap is between and/or separates a second sidewall of the gate electrode from the gate dielectric. A dielectric cap may be disposed over the gate electrode, and the dielectric cap may wrap a top of the gate electrode. The dielectric cap may fill a top portion of the first air gap and a top portion of the second air gap. The gate may be disposed between a first epitaxial source/drain and a second epitaxial source/drain, and a width of the gate is about the same as a distance between the first epitaxial source/drain and the second epitaxial source/drain.

An object of the present invention is to provide a semiconductor device capable of eliminating unevenness of current distribution in a plane. A semiconductor device according to the present invention is a semiconductor device including a transistor cell region where a plurality of transistor cells is arranged on a semiconductor substrate, the semiconductor device including an electrode pad which is arranged avoiding the transistor cell region on the semiconductor substrate and is electrically connected to a one-side current electrode of each of the cells, in which the transistor cell region contains a plurality of regions each of which has a different current drive capability from each other depending on a distance from the electrode pad.

The semiconductor device of the present invention includes a first conductivity type semiconductor layer made of a wide bandgap semiconductor and a Schottky electrode formed to come into contact with a surface of the semiconductor layer, and has a threshold voltage V.sub.th of 0.3 V to 0.7 V and a leakage current J.sub.r of 110.sup.9 A/cm.sup.2 to 110.sup.4 A/cm.sup.2 in a rated voltage V.sub.R.

In a method of forming a gate-all-around field effect transistor (GAA FET), a fin structure is formed. The fin structure includes a plurality of stacked structures each comprising a dielectric layer, a CNT over the dielectric layer, a support layer over the CNT. A sacrificial gate structure is formed over the fin structure, an isolation insulating layer is formed, a source/drain opening is formed by patterning the isolation insulating layer, the support layer is removed from each of the plurality of stacked structures in the source/drain opening, and a source/drain contact layer is formed in the source/drain opening. The source/drain contact is formed such that the source/drain contact is in direct contact with only a part of the CNT and a part of the dielectric layer is disposed between the source/drain contact and the CNT.

A semiconductor device and methods of fabricating the same are disclosed. The semiconductor device includes a substrate, a fin structure with a fin top surface disposed on the substrate, a source/drain (S/D) region disposed on the fin structure, a gate structure disposed on the fin top surface, and a gate spacer with first and second spacer portions disposed between the gate structure and the S/D region. The first spacer portion extends above the fin top surface and is disposed along a sidewall of the gate structure. The second spacer portion extends below the fin top surface and is disposed along a sidewall of the S/D region.