A semiconductor device includes a medium voltage MOSFET having a vertical drain drift region between RESURF trenches containing field plates which are electrically coupled to a source electrode of the MOSFET. A split gate with a central opening is disposed above the drain drift region between the RESURF trenches. A two-level LDD region is disposed below the central opening in the split gate. A contact metal stack makes contact with a source region at lateral sides of the triple contact structure, and with a body contact region and the field plates in the RESURF trenches at a bottom surface of the triple contact structure. A perimeter RESURF trench surrounds the MOSFET. A field plate in the perimeter RESURF trench is electrically coupled to the source electrode of the MOSFET. An integrated snubber may be formed in trenches formed concurrently with the RESURF trenches.

A power transistor assembly and method of mitigating short channel effects in a power transistor assembly are provided. The power transistor assembly includes a first layer of semiconductor material formed of a first conductivity type material and a hard mask layer covering at least a portion of the first layer and having a window therethrough exposing a surface of the first layer. The power transistor assembly also includes a first region formed in the first layer of semiconductor material of a second conductivity type material and aligned with the window, one or more source regions formed of first conductivity type material within the first region and separated by a portion of the first region, and an extension of the first region extending laterally through the surface of the first layer.

Semiconductor device structures comprising a spacer feature having multiple spacer layers are provided. In one example, a semiconductor device includes an active area on a substrate, the active area comprising a source/drain region, a gate structure over the active area, the source/drain region being proximate the gate structure, a spacer feature having a first portion along a sidewall of the gate structure and having a second portion along the source/drain region, wherein the first portion of the spacer feature comprises a bulk spacer layer along the sidewall of the gate structure, wherein the second portion of the spacer feature comprises the bulk spacer layer and a treated seal spacer layer, the treated seal spacer layer being disposed along the source/drain region and between the bulk spacer layer and the source/drain region, and a contact etching stop layer on the spacer feature.

A method for producing a semiconductor power device, includes forming a gate trench from a surface of a semiconductor layer toward an inside thereof. A first insulation film is formed on an inner surface of the gate trench. The method also includes removing a part on a bottom surface of the gate trench in the first insulation film. A second insulation film having a dielectric constant higher than SiO.sub.2 is formed in such a way as to cover the bottom surface of the gate trench exposed by removing the first insulation film.

A MOS transistor, in particular a vertical channel transistor, includes a semiconductor body housing a body region, a source region, a drain electrode and gate electrodes. The gate electrodes extend in corresponding recesses which are symmetrical with respect to an axis of symmetry of the semiconductor body. The transistor also has spacers which are also symmetrical with respect to the axis of symmetry. A source electrode extends in electrical contact with the source region at a surface portion of the semiconductor body surrounded by the spacers and is in particular adjacent to the spacers. During manufacture the spacers are used to form in an auto-aligning way the source electrode which is symmetrical with respect to the axis of symmetry and equidistant from the gate electrodes.

A transistor device includes a channel region including a portion located in a vertical sidewall of semiconductor material and an extended drain region including a portion located in a lower portion of the semiconductor material. In one embodiment, a control terminal of the transistor device is formed by forming a conductive sidewall spacer structure adjacent to the sidewall and a field plate for the transistor device is formed by forming a second conductive sidewall spacer structure.

A trench power transistor includes a semiconductor body having opposite first and second surfaces, and including at least one active region. Such region includes a trench electrode structure, a well, and a source. The trench electrode structure has an electrode trench recessed from the first surface, and includes first, second, and third insulating layers sequentially disposed over bottom and surrounding walls of the electrode trench, a shield electrode enclosed by the third insulating layer, a fourth insulating layer disposed on the first, second, and third insulating layers, and a gate electrode surrounded by the fourth insulating layer. The second insulating layer made of a nitride material and the fourth insulating layer are different in material. A production method of the transistor is also disclosed.

A gate structure of split-gate MOSFET includes a substrate, an epitaxial layer, a first gate, a second gate, a bottom dielectric layer between the first gate and the epitaxial layer, a gate dielectric layer between the second gate and the epitaxial layer, and an inter-gate dielectric layer between the first and second gates. The epitaxial layer is on the substrate having first and second trenches with different extending directions, wherein the first trench and the second trench have an overlapping region. The width of the first trench is greater than that of the second trench. The depth of the first trench is greater than that of the second trench. The first gate is in the first trench. The second gate is in the first trench on the first gate and in the second trenches.

A semiconductor device includes trench structures that extend from a first surface into a semiconductor body. The trench structures include a gate structure and a contact structure that extends through the gate structure, respectively. Transistor mesas are between the trench structures. Each transistor mesa includes a body zone forming a first pn junction with a drift structure and a second pn junction with a source zone. Diode regions directly adjoin one of the contact structures form a third pn junction with the drift structure, respectively.

A method for producing a semiconductor power device, includes forming a gate trench from a surface of a semiconductor layer toward an inside thereof. A first insulation film is formed on an inner surface of the gate trench. The method also includes removing a part on a bottom surface of the gate trench in the first insulation film. A second insulation film having a dielectric constant higher than SiO.sub.2 is formed in such a way as to cover the bottom surface of the gate trench exposed by removing the first insulation film.