A semiconductor device has a semiconductor substrate, and multiple first bipolar transistors on the first primary surface side of the semiconductor substrate. The first bipolar transistors have a first height between an emitter layer and an emitter electrode in the direction perpendicular to the first primary surface. The semiconductor device further has at least one second bipolar transistor on the first primary surface side of the semiconductor substrate. The second bipolar transistor have a second height, greater than the first height, between an emitter layer and an emitter electrode in the direction perpendicular to the first primary surface. Also, the semiconductor has a first bump stretching over the multiple first bipolar transistors and the at least one second bipolar transistor.

The present disclosure provides an HBT that includes (i) a semiconductor support layer; at least four wall structures side-by-side on the support layer; (iii) a semiconductor collector-material ridge structure disposed on the support layer between two adjacent wall structures of the at least four wall structures; (iv) a semiconductor base-material layer, wherein a first part of the base-material layer is disposed on a first region of the ridge structure and a second part of the base-material layer is disposed across the wall structures, wherein the base-material layer is supported by the wall structures; (v) a semiconductor emitter-material layer disposed on the first part of the base-material layer; (vi) a base contact layer disposed on the second part of the base-material layer; an emitter contact layer disposed on the emitter-material layer; and (viii) a collector contact layer disposed on a second region of the ridge structure.

A first collector layer is composed of n-type InP (n-InP) doped with Si at a low concentration. A second collector layer is composed of non-doped InGaAs. A base layer is composed of p-type GaAsSb (p.sup.+-GaAsSb) doped with C at a high concentration. An emitter layer is composed of a compound semiconductor different from that of the base layer, and has an area smaller than the base layer in a plan view. An emitter layer can be composed of, for example, n-type InP (n-InP) doped with Si at a low concentration.

The present disclosure relates to semiconductor structures and, more particularly, to a bipolar junction transistor and methods of manufacture. The structure includes: a collector region; a base region adjacent to the collector region; an emitter region adjacent to the base region; contacts having a first material connecting to the collector region and the base region; and at least one contact having a second material connecting to the emitter region.

The present disclosure relates to semiconductor structures and, more particularly, to heterojunction bipolar transistors and methods of manufacture. The structure includes: a collector in a semiconductor substrate; a subcollector in the semiconductor substrate; an intrinsic base over the subcollector; an extrinsic base adjacent to the intrinsic base; an emitter over the intrinsic base; and an isolation structure between the extrinsic base and the emitter and which overlaps the subcollector.

A BJT and methods of forming the same are described. The BJT includes a collector region disposed in a substrate, a lower base structure disposed on the collector region, a first dielectric layer surrounding a bottom portion of the lower base structure, and a second dielectric layer surrounding a top portion of the lower base structure. The first dielectric layer includes a first oxide, the second dielectric layer includes a second oxide, and the first and second oxides have different densities. The BJT further includes an upper base structure disposed on the second dielectric layer and the lower base structure, an emitter region disposed on the lower base structure, a sidewall spacer structure disposed between the emitter region and the upper base structure, and the sidewall spacer structure includes a material different from materials of the first and second dielectric layers.

The present disclosure relates to semiconductor structures and, more particularly, to annular bipolar transistors and methods of manufacture. The structure includes: a substate material; a collector region parallel to and above the substrate material; an intrinsic base region surrounding the collector region; an emitter region above the intrinsic base region; and an extrinsic base region contacting the intrinsic base region.

A collector layer is disposed on a substrate. The collector layer is a continuous region when viewed in plan. A base layer is disposed on the collector layer. An emitter layer is disposed on the base layer. An emitter mesa layer is disposed on the emitter layer. Two base electrodes are located outside the emitter mesa layer and within the base layer when viewed in plan. The two base electrodes are electrically connected to the base layer. Two capacitors are disposed on or above the substrate. Each of the two capacitors is connected between a corresponding one of the two base electrodes and a first line above the substrate. Two resistance elements are disposed on or above the substrate. Each of the two resistance elements is connected between a corresponding one of the two base electrodes and a second line on or above the substrate.

Methods of manufacturing heterojunction bipolar transistors are described herein. An exemplary method can include providing an emitter/base stack comprising a substrate, a base over the substrate, and/or an emitter over the base. The exemplary method further can include forming a collector. The exemplary method also can include wafer bonding the base to the collector. Other embodiments are also disclosed herein.

A collector layer of an HBT includes a high-concentration collector layer and a low-concentration collector layer thereon. The low-concentration collector layer includes a graded collector layer in which the energy band gap varies to narrow with increasing distance from the base layer. The electron affinity of the semiconductor material for the base layer is greater than that of the semiconductor material for the graded collector layer at the point of the largest energy band gap by about 0.15 eV or less. The electron velocity in the graded collector layer peaks at a certain electric field strength. In the graded collector layer, the strength of the quasi-electric field, an electric field that acts on electrons as a result of the varying energy band gap, is between about 0.3 times and about 1.8 times the peak electric field strength, the electric field strength at which the electron velocity peaks.