An ion implantation method includes irradiating a wafer having a first temperature with a first ion beam such that a predetermined channeling condition is satisfied and irradiating the wafer having a second temperature different from the first temperature with a second ion beam such that the predetermined channeling condition is satisfied, after the irradiation of the first ion beam.

Junction field effect transistors (JFETs) and related manufacturing methods are disclosed herein. A disclosed JFET includes a vertical channel region located in a mesa and a first channel control region located on a first side of the mesa. The first channel control region is at least one of a gate region and a first base region. The JEFT also includes a second base region located on a second side of the mesa and extending through the mesa to contact the vertical channel region. The vertical channel can be an implanted vertical channel. The vertical channel can be asymmetrically located in the mesa towards the first side of the mesa.

A drift layer has a first conductivity type and is provided on a silicon carbide substrate. A well region has a second conductivity type and is provided on the drift layer. A source region has the first conductivity type and is provided on the well region. A gate trench has an inner surface with a bottom located at a deeper position than the well region and a lateral part continuous with the bottom. An electric field relaxation region has the second conductivity type and has at least a part located below the bottom of the gate trench. A surge relaxation region has the first conductivity type, contacts at least a part of the bottom of the gate trench, and is separated from the drift layer by the electric field relaxation region.

A silicon carbide semiconductor device has a silicon carbide substrate, a first insulator, a first electrode, and a second electrode. The silicon carbide substrate includes a first impurity region, a second impurity region, a third impurity region, a first superjunction portion, a fourth impurity region, a fifth impurity region, a sixth impurity region, and a second superjunction portion. The first superjunction portion has a first region and a second region. The second superjunction portion has a third region and a fourth region. In a direction perpendicular to a second main surface, a bottom surface of a first trench is located between a second end surface and the second main surface and is located between a fourth end surface and the second main surface.

Disclosed herein are methods for reducing MOSFET trench sidewall surface roughness. In some embodiments, a method includes providing a device structure including a well formed in an epitaxial layer, forming a plurality of trenches through the well and the epitaxial layer, and implanting the device structure to form a treated layer along a sidewall of just an upper portion of the device structure within each of the plurality of trenches. The method may further include etching the device structure to remove the treated layer.

A semiconductor device of embodiments includes: a silicon carbide layer having a first face and a second face opposite to the first face, and including a p-type silicon carbide region in contact with the first face, a percentage of a first silicon atom among a plurality of silicon atoms present in a first layer as an uppermost layer being equal to or more than 90% and a site position of the first silicon atom being different from a site position of a silicon atom in a third layer from the first face and the same as a site position of a silicon atom in a fifth layer from the first face; a gate electrode; a silicon oxide layer between the silicon carbide layer and the gate electrode; and a region between the silicon carbide layer and the silicon oxide layer including nitrogen.

Disclosed herein are methods for reducing MOSFET trench sidewall surface roughness. In some embodiments, a method includes providing a device structure including a well formed in an epitaxial layer, forming a plurality of trenches through the well and the epitaxial layer, and implanting the device structure to form a treated layer along a sidewall of just an upper portion of the device structure within each of the plurality of trenches. The method may further include etching the device structure to remove the treated layer.

A Schottky barrier diode is provided. The Schottky barrier diode includes: an n+ type of substrate, an n− type of epitaxy layer disposed on a first surface of the n+ type of substrate and having a trench opened to an opposite side of a surface facing the substrate, a p type of region disposed on a side surface of the trench, a Schottky electrode disposed on the n− type of epitaxy layer and within the trench, and an ohmic electrode disposed on a second surface of the n+ type of substrate.

A SiC SJ trench MOSFET having first and second type gate trenches for formation of gate electrodes and super junction regions is disclosed. The gate electrodes are disposed into the first type gate trenches having a thick oxide layer on trench bottom. The super junction regions are formed surrounding the second type gate trenches filled up with the thick oxide layer. The device further comprises gate oxide electric field reducing regions adjoining lower surfaces of body regions and space apart from the gate trenches.

The present invention relates to a silicon carbide semiconductor device that includes a Schottky barrier diode in a field-effect transistor and includes a first trench provided through first and second semiconductor regions in a thickness direction and reaches inside a semiconductor layer, a second trench provided through the second semiconductor region in the thickness direction and reaches inside the semiconductor layer, a gate electrode embedded in the first trench via a gate insulating film, a Schottky barrier diode electrode embedded in the second trench, a first low-resistance layer having contact with a trench side wall of the first trench, and a second low-resistance layer having contact with a trench side wall of the second trench. The second low-resistance layer has an impurity concentration that is higher than the impurity concentration in the semiconductor layer and lower than the impurity concentration in the first low-resistance layer.