The present invention provides a bipolar transistor, a method for forming the bipolar transistor, a method for turning on the bipolar transistor, and a band-gap reference circuit, virtual ground reference circuit and double band-gap reference circuit with the bipolar transistor. The bipolar transistor includes: a Silicon-On-Insulator wafer; a base area, an emitter area and a collector area; a base area gate dielectric layer on a top silicon layer and atop the base area; a base area control-gate on the base area gate dielectric layer; an emitter electrode connected to the emitter area via a first contact; a collector electrode connected to the collector area via a second contact; and a base area control-gate electrode connected to the base area control-gate via a third contact. Processes of forming the bipolar transistor are fully compatible with traditional standard CMOS processes; and the base current to turn on the bipolar transistor is based on the GIDL current and formed by applying a voltage to the base area control-gate electrode without any need of contact to the base.

A semiconductor device having a vertical drain extended MOS transistor may be formed by forming deep trench structures to define vertical drift regions of the transistor, so that each vertical drift region is bounded on at least two opposite sides by the deep trench structures. The deep trench structures are spaced so as to form RESURF regions for the drift region. Trench gates are formed in trenches in the substrate over the vertical drift regions. The body regions are located in the substrate over the vertical drift regions.

A silicon-carbide semiconductor substrate having a plurality of first doped regions being laterally spaced apart from one another and beneath a main surface, and a second doped region extending from the main surface to a third doped region that is above the first doped regions is formed. Fourth doped regions extending from the main surface to the first doped regions are formed. A gate trench having a bottom that is arranged over a portion of one of the first doped regions is formed. A high-temperature step is applied to the substrate so as to realign silicon-carbide atoms along sidewalls of the trench and form rounded corners in the gate trench. A surface layer that forms along the sidewalls of the gate trench during the high-temperature step from the substrate is removed.

A semiconductor device includes a semiconductor layer having a first surface and a second surface, a first electrode on the first surface, a second electrode on the second surface, a first semiconductor region of a first conductivity type in the semiconductor layer, a second semiconductor region of a second conductivity type in an element region of the semiconductor layer between the first semiconductor region and the first electrode, a third semiconductor region of the second conductivity type between the second semiconductor region and the first electrode, and a fourth semiconductor region of the second conductivity type in a termination region of the semiconductor layer inwardly of the first surface. A distance between the fourth semiconductor region and the second surface is greater than a distance between the second semiconductor region and the second surface.

In a silicon carbide semiconductor device, a trench penetrates a source region and a first gate region and reaches a drift layer. On an inner wall of the trench, a channel layer of a first conductivity-type is formed by epitaxial growth. On the channel layer, a second gate region of a second conductivity-type is formed. A first depressed portion is formed at an end portion of the trench to a position deeper than a thickness of the source region so as to remove the source region at the end portion of the trench. A corner portion of the first depressed portion is covered by a second conductivity-type layer.

A semiconductor device comprises a silicon carbide based semiconductor layer structure that includes a drift layer having a first conductivity type, a gate trench that extends to a first depth into an upper surface of the semiconductor layer structure, a gate electrode in the gate trench, a support shield trench that extends to a second depth into the upper surface of the semiconductor layer structure, where the second depth is less than the first depth, and a source metallization layer on the upper surface of the semiconductor layer structure and extending into the support shield trench.

In a semiconductor device, a first N-type diffusion layer is provided in a first high-side circuit region, and a second N-type diffusion layer is provided in a second high-side circuit region. Constituent elements for first and second high-side circuits are provided in the first and second N-type diffusion layers. An isolation trench is provided between the first N-type diffusion layer and the second N-type diffusion layer. The deepest portion of the isolation trench reaches a P-type substrate region of a P-type substrate. The first N-type diffusion layer and the second N-type diffusion layer are electrically isolated by the isolation trench having a buried insulating film inside.

A semiconductor device comprising a bipolar transistor and a method of making the same. A power amplifier including a bipolar transistor. The bipolar transistor includes a collector including a laterally extending drift region. The also includes a base located above the collector. The bipolar transistor further includes an emitter located above the base. The bipolar transistor also includes a doped region having a conductivity type that is different to that of the collector. The doped region extends laterally beneath the collector to form a junction at a region of contact between the doped region and the collector. The doped region has a non-uniform lateral doping profile. A doping level of the doped region is highest in a part of the doped region closest to a collector-base junction of the bipolar transistor.

A method of forming a transistor device includes providing a drift layer having a first conductivity type, forming a first region in the drift layer, the first region having a second conductivity type that is opposite the first conductivity type, forming a body layer on the drift layer including the first region, forming a source layer on the body layer, forming a trench in the source layer and the body layer above the first region and extending into the first region, forming a gate insulator on the inner sidewall of the trench, and forming a gate contact on the gate insulator.

The present invention makes it possible to improve the accuracy of wet etching and miniaturize a semiconductor device in the case of specifying an active region of a vertical type power MOSFET formed over an SiC substrate by opening an insulating film over the substrate by the wet etching. After a silicon oxide film having a small film thickness and a polysilicon film having a film thickness larger than the silicon oxide film are formed in sequence over an epitaxial layer, the polysilicon film is opened by a dry etching method, successively the silicon oxide film is opened by a wet etching method, and thereby the upper surface of the epitaxial layer in an active region is exposed.