A method for forming a transistor structure includes steps as follows: A substrate with an original surface is prepared. Next a gate conductive region is formed, wherein at least a portion of the gate conductive region is disposed below the original surface, and a bottom wall and sidewalls of the gate conductive region is surrounded by a gate dielectric layer. Then, a first conductive region is formed, wherein a bottom wall of the first conductive region is aligned or substantially aligned with a top wall of the gate conductive region.

A semiconductor device that achieves both miniaturization and high breakdown voltage is disclosed. The semiconductor device has a gate electrode G1 formed in a trench TR extending in Y direction and a plurality of column regions PC including column regions PC1 to PC3 formed in a drift region ND. The column regions PC1, PC2 and PC3 are provided in a staggered manner to sandwich the trench TR. An angle θ1 formed by a line connecting the centers of the column regions PC1 and PC2 and a line connecting the centers of the column regions PC1 and PC3 is 60 degrees or more and 90 degrees or less.

A semiconductor structure includes a substrate, an isolation layer, a dielectric layer, an insulation layer, a conductor and a capping layer. The substrate has a concave portion. The isolation layer is located on a top surface of the substrate. The dielectric layer is located on the isolation layer. The insulation layer is located on a surface of the concave portion and extends to a sidewall of the isolation layer. The conductor is located on the insulation layer in the concave portion. The conductor has a first top surface and a second top surface, and the first top surface is closer to the dielectric layer than the second top surface. The capping layer is located in the concave portion and covers the conductor.

A Field Effect Transistor (FET) may include a semiconductor substrate having a first conductivity type, a semiconductor layer of the first conductivity type formed over the substrate, and a pair of doped bodies of a second conductivity type opposite the first conductivity type formed in the semiconductor layer. A trench filled with a trench dielectric is formed within a region between the doped bodies. The FET may be a Vertical Metal-Oxide-Semiconductor FET (VMOSFET) including a gate dielectric disposed over the region between the doped bodies and the trench, and a gate electrode disposed over the gate dielectric, wherein the trench operates to prevent breakdown of the gate dielectric, or the FET may be a Junction FET. The FET may be designed to operate at radio frequencies or under heavy-ion bombardment. The semiconductor substrate and the semiconductor layer may comprise a wide band-gap semiconductor such as silicon carbide.

A transistor including a gate region penetrating into a first gallium nitride layer, wherein a second electrically-conductive layer coats at least one of the sides of said gate region.

According to one embodiment, a semiconductor device includes first to third electrodes, first and second semiconductor regions, a nitride region, and a first insulating member. The third electrode includes a first electrode portion. The first electrode portion is between the first electrode and the second electrode. The first semiconductor region includes first to sixth partial regions. The fourth partial region is between the first and third partial regions. The fifth partial region is between the third and second partial regions. The sixth partial region is between the fifth and second partial regions. The second semiconductor region includes first and second semiconductor portions. The second semiconductor portion is in contact with the fifth partial region. The nitride region includes a first nitride portion being in contact with the sixth partial region. The first insulating member includes a first insulating region between the third partial region and the first electrode portion.

A test structure for a buried gate transistor includes a substrate, a first test contact located on one side of a first transistor contact, a second test contact located on one side of a second transistor contact, and a layer buried in the substrate, having a doping greater than or equal to 10.sup.18 cm.sup.−3, and having a face which is tangent to the buried part of the gate. A first insulation structure is disposed between the first test contact and the first transistor contact and a second insulation structure is disposed between the second test contact and the second transistor contact. The first and second test contacts each have an end connected to the buried layer.

Structures, devices and methods are provided for forming an interface protection layer (204) adjacent to a fully or partially recessed gate structure (202) of a group III nitride, a metal-insulator-semiconductor high-electron-mobility transistor (MIS-HEMT) device or a metal-insulator-semiconductor field-effect transistor (MIS-FET) device, and forming agate dielectric (114) disposed the interface protection layer (204).

Provided is a semiconductor device including: an active portion provided thereon; a plurality of trench portions each including a gate conductive portion and arranged in a array direction while extending in a extending direction in the active portion, a conductive portion shape ratio of a trench length to a width of the gate conductive portion array direction being 1,000 or more; a first control pad protruding toward an inner side of the semiconductor substrate from a first outer peripheral side of the semiconductor substrate in a top view; and a first well region provided below the first control pad and to cover the first control pad in the top view, in which a shortest distance between the first well region and a trench center position as a center of a length of the plurality of trench portions in the extending direction in the top view is 1,000 μm or more.

A high electron mobility transistor (HEMT) includes a carrier transit layer, a carrier supply layer, a main gate, a control gate, a source electrode and a drain electrode. The carrier transit layer is on a substrate. The carrier supply layer is on the carrier transit layer. The main gate and the control gate are on the carrier supply layer. A fluoride ion doped region is formed right below the main gate in the carrier supply layer. The source electrode and the drain electrode are at two opposite sides of the main gate and the control gate, wherein the source electrode is electrically connected to the control gate by a metal interconnect. The present invention also provides a method of forming a high electron mobility transistor (HEMT).