A power semiconductor device includes a semiconductor layer based on silicon carbide (SiC), a vertical drift region positioned to extend in a vertical direction inside the semiconductor layer and having a first conductive type, a well region positioned in at least one side of the vertical drift region to make contact with the vertical drift region and having a second conductive type, recess gate electrodes extending from a surface of the semiconductor layer into the semiconductor layer and buried in the vertical drift region and the well region to cross the vertical drift region and the well region in a first direction, source regions positioned in the well region between the recess gate electrodes and having the first conductive type, and insulating-layer protective regions surrounding lower portions of the recess gate electrodes, respectively, in the vertical drift region, and having the second conductive type.

Embodiments of processing a substrate are provided herein. In some embodiments, a method of processing a substrate includes: depositing, via a first epitaxial growth process, an n-doped silicon material onto a substrate to form an n-doped layer while adjusting a ratio of dopant precursor to silicon precursor so that a dopant concentration of the n-doped layer increases from a bottom of the n-doped layer to a top of the n-doped layer; etching the n-doped layer to form a plurality of trenches having sidewalls that are tapered and a plurality of n-doped pillars therebetween; and filling the plurality of trenches with a p-doped material via a second epitaxial growth process to form a plurality of p-doped pillars.

The disclosure provides a superjunction IGBT (insulated gate bipolar transistor) device, wherein a carrier storage layer of a first conductivity type is provided between a voltage sustaining layer and a base region, and a MISFET (metal-insulator-semiconductor field effect transistor) of a second conductivity type is also integrated in a cell, with at least one gate of the MISFET is connected to the emitter contact thereof. The MISFET is turned off at a low forward conduction voltage, helping to reduce the conduction voltage drop. The MISFET can provide a path for carriers of a second conductivity type and prevent the carrier storage layer from suffering a high electric field when the forward conduction voltage is slightly higher or it is at the forward blocking state, helping to improve the reliability.

A method to fabricate a transistor includes implanting dopants into a semiconductor to form a drift layer having majority carriers of a first type; etching a trench into the semiconductor; thermally growing an oxide liner into and on the trench and the drift layer; depositing an oxide onto the oxide liner on the trench to form a shallow trench isolation region; implanting dopants into the semiconductor to form a drain region in contact with the drift layer and having majority carriers of the first type; implanting dopants into the semiconductor to form a body region having majority carriers of a second type; forming a gate oxide over a portion of the drift layer and the body region; forming a gate over the gate oxide; and implanting dopants into the body region to form a source region having majority carriers of the first type.

The present invention introduces a new shielded gate trench SBR (Super Barrier Rectifier) wherein an epitaxial layer having special MSE (multiple stepped epitaxial) layers with different doping concentrations decreasing in a direction from a substrate to a top surface of the epitaxial layer, wherein each of the MSE layers has an uniform doping concentration as grown. Forward voltage V.sub.f is significantly reduced with the special MSE layers. An integrated circuit comprising a SGT MOSFET and a SBR formed on a single chip obtains benefits of low on-resistance, low reverse recovery time and high avalanche capability from the special MSE layers.

A semiconductor substrate includes a base substrate, a first epitaxial layer having a first conductivity type on the base substrate, a second epitaxial layer having the first conductivity type on the first epitaxial layer, a first well region having a second conductivity type different from the first conductivity type, in the first epitaxial layer and the second epitaxial layer, and a second well region which is spaced apart from the first well region and has the second conductivity type, in the first epitaxial layer and the second epitaxial layer, wherein a doping concentration of the first epitaxial layer is greater than a doping concentration of the second epitaxial layer, and a depth of each of the first well region and the second well region is greater than a thickness of the second epitaxial layer.

A modified structure of an n-channel lateral double-diffused metal oxide semiconductor (LDMOS) transistor is provided to suppress the rupturing of the gate-oxide which can occur during the operation of the LDMOS transistor. The LDMOS transistor comprises a dielectric isolation structure which physically isolates the region comprising a parasitic NPN transistor from the region generating a hole current due to weak-impact ionization, e.g., the extended drain region of the LDMOS transistor. According to an embodiment of the disclosure, this can be achieved using a vertical trench between the two regions. Further embodiments are also proposed to enable a reduction in the gain of the parasitic NPN transistor and in the backgate resistance in order to further improve the robustness of the LDMOS transistor.

First dopants are implanted through a larger opening of a first process mask into a silicon carbide body, wherein the larger opening exposes a first surface section of the silicon carbide body. A trench is formed in the silicon carbide body in a second surface section exposed by a smaller opening in a second process mask. The second surface section is a sub-section of the first surface section. The larger opening and the smaller opening are formed self-aligned to each other. At least part of the implanted first dopants form at least one compensation layer portion extending parallel to a trench sidewall.

A semiconductor device includes a first nitride-based semiconductor layer, a second nitride-based semiconductor layer, a group of negatively-charged ions, and a field plate. The gate electrode and the drain electrode disposed above the second nitride-based semiconductor layer to define a drift region therebetween. The group of negatively-charged ions are implanted into the drift region and spaced apart from an area directly beneath the gate and drain electrodes to form at least one high resistivity zone in the second nitride-based semiconductor layer. The field plate is disposed over the gate electrode and extends in a region between the gate electrode and the high resistivity zone.

A method for forming a drift region of a superjunction device includes forming a drift region section having a semiconductor layer with first regions of a first doping type and second regions of a second doping type arranged alternatingly in a first lateral direction. Forming the drift region section includes: forming an implantation mask on top of a first surface of the semiconductor layer and including first openings; in a first implantation process, implanting dopant atoms of the first doping type through the first openings into the first surface; increasing a size of the first openings to obtain second openings; in a second implantation process, implanting dopant atoms of the second doping type through the second openings into the first surface; and after removing the mask, in a third implantation process, implanting dopant atoms of the first doping type into the first surface.