A parasitic capacitance and a leak current in a nitride semiconductor device are reduced. For example, a 100 nm-thick buffer layer made of AlN, a 2 μm-thick undoped GaN layer, and 20 nm-thick undoped AlGaN having an Al composition ratio of 20% are epitaxially grown in this order on, for example, a substrate made of silicon, and a source electrode and a drain electrode are formed so as to be in ohmic contact with the undoped AlGaN layer. Further, in the undoped GaN layer and the undoped AlGaN layer immediately below a gate wire, a high resistance region, the resistance of which is increased by, for example, ion implantation with Ar or the like, is formed, and a boundary between the high resistance region and an element region is positioned immediately below the gate wire.

The embodiments described herein are directed to a method for reducing fin oxidation during the formation of fin isolation regions. The method includes providing a semiconductor substrate with an n-doped region and a p-doped region formed on a top portion of the semiconductor substrate; epitaxially growing a first layer on the p-doped region; epitaxially growing a second layer different from the first layer on the n-doped region; epitaxially growing a third layer on top surfaces of the first and second layers, where the third layer is thinner than the first and second layers. The method further includes etching the first, second, and third layers to form fin structures on the semiconductor substrate and forming an isolation region between the fin structures.

A semiconductor device includes: a semiconductor layer of a first conductivity-type; a well region of a second conductivity-type provided at an upper part of the semiconductor layer; a base region of the second conductivity-type provided at an upper part of the well region; a carrier supply region of the first conductivity-type provided at an upper part of the base region; a drift region of the first conductivity-type provided separately from the base region; a carrier reception region of the first conductivity-type provided at an upper part of the drift region; a gate electrode provided on a top surface of the well region interposed between the base region and the drift region via a gate insulating film; and a punch-through prevention region of the second conductivity-type provided at the upper part of the well region and having an impurity concentration different from the impurity concentration of the base region.

The Rds*Cgd figure of merit (FOM) of a laterally diffused metal oxide semiconductor (LDMOS) transistor is improved by forming the drain drift region with a number of dopant implants at a number of depths, and forming a step-shaped back gate region with a number of dopant implants at a number of depths to adjoin the drain drift region.

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.

A semiconductor device includes a semiconductor substrate of a first conductivity type, a first semiconductor layer of the first conductivity type formed on the semiconductor substrate and having a first conductivity type impurity concentration higher than that of the semiconductor substrate, a second semiconductor layer of a second conductivity type formed above the first semiconductor layer, a first device region formed in the second semiconductor layer and configured to operate based on a first reference voltage, a second device region formed in the second semiconductor layer and configured to operate based on a second reference voltage, the second device region being spaced apart from the first device region, and a region isolation structure interposed between the first and second device regions and formed in a region extending from a front surface of the second semiconductor layer to the first semiconductor layer so as to electrically isolate the first and second device regions from each other.

According to an embodiment, a semiconductor device includes a first semiconductor region of a first conductivity type, a second semiconductor region of the first conductivity type, a first metal portion, a third semiconductor region of a second conductivity type, a first electrode, a fourth semiconductor region of the second conductivity type, and a second electrode. The first semiconductor region includes a first portion and a second portion. The second semiconductor region is provided on the first semiconductor region. The third semiconductor region is provided on part of the second semiconductor region. The first metal portion is provided in the first semiconductor region. The third semiconductor region is positioned on the first portion. The fourth semiconductor region is provided on another part of the second semiconductor region. The fourth semiconductor region is separated from the third semiconductor region. The fourth semiconductor region is positioned on the second portion.

A semiconductor device includes: a chip having a main surface; a first conductive type first region formed on a surface layer portion of the main surface; a second conductive type second region formed on a surface layer portion of the first region; a drain region formed on a surface layer portion of the second region; a source region formed on the surface layer portion of the first region at a distance from the second region; and a second conductive type floating region formed in the first region at a thickness position between a bottom portion of the first region and a bottom portion of the second region and being spaced apart from the bottom portion of the second region, wherein the floating region faces the second region with a portion of the first region interposed between the floating region and the second region.

A voltage tracking circuit is provided and includes first and second P-type transistors and a voltage reducing circuit. The drain of the first P-type transistor is coupled to a first voltage terminal. The voltage reducing circuit is coupled between the first voltage terminal and the gate of the first P-type transistor. The voltage reducing circuit reduces a first voltage at the first voltage terminal by a modulation voltage to generate a control voltage and provides the control voltage to the gate of the first P-type transistor. The gate of the second P-type transistor is coupled to the first voltage terminal, and the drain thereof is coupled to a second voltage terminal. The source of the first P-type transistor and the source of the second P-type transistor are coupled to the output terminal of the voltage tracking circuit. The output voltage is generated at the output terminal.