A semiconductor device including: a semiconductor substrate having a drift region of the first conductivity type; a cathode region formed on the lower surface of the semiconductor substrate; a diode portion having the cathode region formed on the lower surface of the semiconductor substrate; the first dummy trench portion provided from the upper surface of the semiconductor substrate to the drift region, including one part provided inside the diode portion and the other part provided outside the diode portion, and provided extending in series from inside the diode portion to outside the diode portion in a predetermined extending direction on the upper surface of the semiconductor substrate; and the first lead-out portion that is provided on the upper surface of the semiconductor substrate, and electrically connected to the first dummy trench portion outside the diode portion is provided.

A lateral transistor tile is formed with first and second collector regions that longitudinally span first and second sides of the transistor tile; and a base region and an emitter region that are between the first and second collector regions and are both centered on a longitudinal midline of the transistor tile. A base-collector current, a collector-emitter current, and a base-emitter current flow horizontally; and the direction of the base-emitter current is perpendicular to the direction of the base-collector current and the collector-emitter current. Lateral BJT transistors having a variety of layouts are formed from a plurality of the tiles and share common components thereof.

In certain aspects, a heterojunction bipolar transistor (HBT) comprises a collector mesa, a base mesa on the collector mesa, and an emitter mesa on the base mesa. The base mesa has a tapered sidewall tapering from a wide bottom to a narrow top. The HBT further comprises a collector contact on a portion of the collector mesa and extending to a portion of the tapered sidewall of the base mesa.

A bipolar junction transistor preferably includes: an emitter region; a base region; and a collector region, in which an edge of the emitter region is aligned with an edge of the base region. Preferably, an edge of the base region is aligned with an edge of the collector region, the edge of the emitter region is aligned with the edges of the base region and the collector region, and the widths of the emitter region, the base region, and the collector region are equivalent. According to a top view of the bipolar junction transistor, each of the base region and the collector region includes a rectangle.

A bipolar junction transistor includes: an emitter region; a base region; and a collector region, wherein each of the emitter region, the base region, and the collector region comprises fin-shaped structures. Preferably, the emitter region, the base region, and the collector region are disposed along a first direction and the fin-shaped structures are disposed along a second direction, in which the first direction is orthogonal to the second direction.

A semiconductor device includes a semiconductor element including a bipolar transistor disposed on a compound semiconductor substrate, a collector electrode, a base electrode, and an emitter electrode, the bipolar transistor including a collector layer, a base layer, and an emitter layer, the collector electrode being in contact with the collector layer, the base electrode being in contact with the base layer, the emitter electrode being in contact with the emitter layer; a protective layer disposed on one surface of the semiconductor element; an emitter redistribution layer electrically connected to the emitter electrode via a contact hole in the protective layer; and a stress-relieving layer disposed between the emitter redistribution layer and the emitter layer in a direction perpendicular to a surface of the compound semiconductor substrate.

A heterojunction bipolar transistor includes: a substrate; a base mesa disposed on the substrate, wherein the base mesa includes a collector layer and a base layer disposed on the collector layer, and wherein in a top view, the base layer includes a first edge and a second edge opposite to the first edge; an emitter layer disposed on the base layer; a base electrode disposed on the substrate and connected to the base layer; a dielectric layer disposed on the base electrode, wherein a first via hole is formed in the dielectric layer at the first edge of the base layer, and a second via hole is formed in the dielectric layer at the second edge of the base layer; and a conductive feature disposed on the dielectric layer, wherein the conductive feature is connected to the base electrode through the first via hole and the second via hole.

A bipolar transistor includes a collector layer, a base layer, and an emitter layer that are formed in this order on a compound semiconductor substrate. The emitter layer is disposed inside an edge of the base layer in plan view. A base electrode is disposed on partial regions of the emitter layer and the base layer so as to extend from an inside of the emitter layer to an outside of the base layer in plan view. An insulating film is disposed between the base electrode and a portion of the base layer, with the portion not overlapping the emitter layer. An alloy layer extends from the base electrode through the emitter layer in a thickness direction and reaches the base layer. The alloy layer contains at least one element constituting the base electrode and elements constituting the emitter layer and the base layer.

Bipolar transistors and MOS transistors are formed in a common process. A semiconductor layer is arranged on an insulating layer. On a side of the bipolar transistors: an insulating region including the insulating layer is formed; openings are etched through the insulating region to delimit insulating walls; the openings are filled with first epitaxial portions; and the first epitaxial portions and a first region extending under the first epitaxial portions and under the insulating walls are doped. On the side of the bipolar transistors and on a side of the MOS transistors: gate structures are formed; second epitaxial portions are made; and the second epitaxial portions covering the first epitaxial portions are doped.

A semiconductor device includes a plurality of unit transistors that are arranged on a surface of a substrate in a first direction. Input capacitive elements are arranged so as to correspond to the unit transistors. An emitter common wiring line is connected to emitter layers of the unit transistors. A via-hole extending from the emitter common wiring line to a back surface of the substrate is disposed at a position overlapping the emitter common wiring line. A collector common wiring line is connected to collector layers of the unit transistors. The input capacitive elements, the emitter common wiring line, the unit transistors, and the collector common wiring line are arranged in this order in a second direction. Base wiring lines that connect the input capacitive elements to base layers of the corresponding unit transistors intersect the emitter common wiring line without physical contact.