Aspects of the disclosure provide an integrated circuit (IC) structure with a bipolar transistor stack within a substrate. The bipolar transistor stack may include: a collector, a base on the collector, and an emitter on a first portion of the base. A horizontal width of the emitter is less than a horizontal width of the base, and an upper surface of the emitter is substantially coplanar with an upper surface of the substrate. An extrinsic base structure is on a second portion of the base of the bipolar transistor stack, and horizontally adjacent the emitter. The extrinsic base structure includes an upper surface above the upper surface of the substrate.

An ESD protection device is fabricated in a semiconductor substrate that includes a semiconductor layer having a first conductivity type. A first well implantation procedure implants dopant of a second conductivity type in the semiconductor layer to form inner and outer sinker regions. The inner sinker region is configured to establish a common collector region of first and second bipolar transistor devices. A second well implantation procedure implants dopant of the first conductivity type in the semiconductor layer to form respective base regions of the first and second bipolar transistor devices. Conduction of the first bipolar transistor device is triggered by breakdown between the inner sinker region and the base region of the first bipolar transistor device. Conduction of the second bipolar transistor device is triggered by breakdown between the outer sinker region and the base region of the second bipolar transistor device.

Devices and methods of forming a device are disclosed. The method includes providing a substrate with a cell region. Selector units and storage units are formed within the substrate. The selector unit includes first and second bipolar junction transistors (BJTs). The selector unit includes first and second bipolar junction transistors (BJTs). A BJT includes first, second and third BJT terminals. The second BJT terminals of the first and second BJTs are coupled to or serve as a common wordline terminal. The third BJT terminal of the first BJT serves as a first bitline terminal, and the third BJT terminal of the second BJT serves as a second bitline terminal. A storage unit is disposed over the selector unit. The storage unit includes a first pinning layer which is coupled to the first BJT terminal of the first BJT, a second pinning layer which is coupled to the first BJT terminal of the second BJT, a free layer which includes an elongated member with first and second major surfaces and first and second end regions separated by a free region. The first pinning layer is coupled to the second major surface of the free layer in the first end region and the second pinning layer is coupled to the second major surface of the free layer in the second end region. A reference stack is disposed on the first major surface of the free layer in the free region. The reference stack serves as a read bitline terminal.

A high-performance HBT that is unlikely to decrease the process controllability and to increase the manufacturing cost is implemented. A heterojunction bipolar transistor includes an emitter layer, a base layer, and a collector layer on a GaAs substrate. The emitter layer is formed of InGaP. The base layer is formed of GaAsPBi having a composition that substantially lattice-matches GaAs.

Various particular embodiments include an integrated circuit (IC) structure including: a stack region; and a silicon substrate underlying and contacting the stack region, the silicon substrate including: a silicon region including a doped subcollector region; a set of isolation regions overlying the silicon region; a base region between the set of isolation regions and below the stack region, the base region including an intrinsic base contacting the stack region, an extrinsic base contacting the intrinsic base and the stack region, and an amorphized extrinsic base contact region contacting the extrinsic base; a collector region between the set of isolation regions; an undercut collector-base region between the set of isolation regions and below the base region; and a collector contact region contacting the collector region under the intrinsic base and the collector-base region via the doped subcollector region.

Device structures for a bipolar junction transistor and methods of fabricating a device structure for a bipolar junction transistor. A base layer comprised of a first semiconductor material is formed. An emitter layer comprised of a second semiconductor material is formed on the base layer. The emitter layer is patterned to form an emitter finger having a length and a width that changes along the length of the emitter finger.

Methods and devices are provided herein for enhancing robustness of a bipolar electrostatic discharge (ESD) device. The robustness of a bipolar ESD device includes providing an emitter region and a collector region adjacent to the emitter region. An isolation structure is provided between the emitter region and the collector region. A ballasting characteristic at the isolation structure is modified by inserting at least one partition structure therein. Each partition structure extends substantially abreast at least one of the emitter and the collector regions.

Embodiments include a first set of fins having an emitter of a bipolar junction transistor (BJT) disposed over the first set of fins, a second set of fins having a base of the BJT disposed over the second set of fins, and a third set of fins having a collector of the BJT disposed over the third set of fins. A first gate structure is disposed over the first set of fins adjacent to the emitter. A second gate structure is disposed over the second set of fins adjacent to the base. A third gate structure is disposed over the third set of fins adjacent to the collector. The first gate structure, second gate structure, and third gate structure are physically and electrically separated.

An integrated circuit includes a first base that has at least a part formed of a first semiconductor material and that includes an electric circuit (for example, a control circuit or a switching circuit), a second base that has at least a part formed of a second semiconductor material having a thermal conductivity lower than the first semiconductor material and that includes a power amplifier circuit, and a low thermal conductive member that has at least a part formed of a low thermal conductive material having a thermal conductivity lower than the second semiconductor material and that is disposed between the electric circuit and the power amplifier circuit. At least a part of the first base overlaps at least a part of the second base in plan view.

A device including a transistor is fabricated by forming a first part of a first region of the transistor through the implantation of dopants through a first opening. The second region of the transistor is then formed in the first opening by epitaxy.