The disclosure provides a heterojunction bipolar transistor and a preparation method thereof. Since an emitter region has the same physical structure as a base region, and improves frequency characteristics of the device; Simultaneously with biaxial strain, uniaxial strain is introduced. Carrier transmission time in the collector region will be effectively reduced. By this structure, the width of the effective collector region is reduced, the collector junction capacitance is reduced, and the frequency characteristics of the device are further improved; an appropriate choice of the thickness of the Si cap layer can effectively reduce the accumulation of carriers at an interface and increase the gain of the device; at the same time, the preparation method of the bipolar transistor is completely compatible with a 90-nanometer CMOS process, which effectively reduces the development and manufacturing cost of the device.

A semiconductor device is described including a substrate and a plurality of layers. The semiconductor device includes a cascode arrangement of a first bipolar transistor and a second bipolar transistor. A first-bipolar-transistor-collector of the first bipolar transistor and a second-bipolar-transistor-emitter of the second bipolar transistor are at least partially located in a common region in the same layer of the semiconductor device.

Multiple strain states in epitaxial transistor channel material may be achieved through the incorporation of stress-relief defects within a seed material. Selective application of strain may improve channel mobility of one carrier type without hindering channel mobility of the other carrier type. A transistor structure may have a heteroepitaxial fin including a first layer of crystalline material directly on a second layer of crystalline material. Within the second layer, a number of defected regions of a threshold minimum dimension are present, which induces the first layer of crystalline material to relax into a lower-strain state. The defected regions may be introduced selectively, for example a through a masked impurity implantation, so that the defected regions may be absent in some transistor structures where a higher-strain state in the first layer of crystalline material is desired.

The present disclosure relates to semiconductor structures and, more particularly, to a heterojunction bipolar transistor having one or more sealed airgap and methods of manufacture. The structure includes: a subcollector region in a substrate; a collector region above the substrate; a sealed airgap formed at least partly in the collector region; a base region adjacent to the collector region; and an emitter region adjacent to the base region.

A semiconductor device that includes a bipolar transistor, wherein a third opening, through which a pillar bump and a second wiring line, which is electrically connected to an emitter layer, contact each other, is shifted in a longitudinal direction of the emitter layer away from a position at which the third opening would be directly above the emitter layer. The third opening is arranged, with respect to the emitter layer, such that an end portion of the emitter layer in the longitudinal direction of the emitter layer and the edge of the opening of the third opening are substantially aligned with each other.

A normally-off HEMT transistor includes a heterostructure including a channel layer and a barrier layer on the channel layer; a 2DEG layer in the heterostructure; an insulation layer in contact with a first region of the barrier layer; and a gate electrode through the whole thickness of the insulation layer, terminating in contact with a second region of the barrier layer. The barrier layer and the insulation layer have a mismatch of the lattice constant (“lattice mismatch”), which generates a mechanical stress solely in the first region of the barrier layer, giving rise to a first concentration of electrons in a first portion of the two-dimensional conduction channel which is under the first region of the barrier layer which is greater than a second concentration of electrons in a second portion of the two-dimensional conduction channel which is under the second region of the barrier layer.

A bipolar junction transistor includes an extrinsic collector region buried in a semiconductor substrate under an intrinsic collector region. Carbon-containing passivating regions are provided to delimit the intrinsic collector region. An insulating layer on the intrinsic collector region includes an opening within which an extrinsic base region is provided. A semiconductor layer overlies the insulating layer, is in contact with the extrinsic base region, and includes an opening with insulated sidewalls. The collector region of the transistor is provided between the insulated sidewalls.

A method of making a bipolar transistor includes forming a stack of a first, second, third and fourth insulating layers on a substrate. An opening is formed in the stack to reach the substrate. An epitaxial process forms the collector of the transistor on the substrate and selectively etches an annular opening in the third layer. The intrinsic part of the base is then formed by epitaxy on the collector, with the intrinsic part being separated from the third layer by the annular opening. The junction between the collector and the intrinsic part of the base is surrounded by the second layer. The emitter is formed on the intrinsic part and the third layer is removed. A selective deposition of a semiconductor layer on the second layer and in direct contact with the intrinsic part forms the extrinsic part of the base.

A semiconductor device and a manufacturing method thereof are provided. The semiconductor device includes first and second epitaxial layers, and first and second semiconductor layers. The second epitaxial layer is disposed on the first epitaxial layer. The first semiconductor layer extends from above the second epitaxial layer to a top surface of the second epitaxial layer. A vertically extending region of the first semiconductor layer has a body portion and an extending portion extending from a bottom end of the body portion to the second epitaxial layer. A width of the body portion is greater than a width of the extending portion. The second semiconductor layer is disposed on the second epitaxial layer, and laterally surrounds the vertically extending region of the first semiconductor layer. A portion of the second semiconductor layer extends between and overlaps with the body portion of the first semiconductor layer and the second epitaxial layer.

The present disclosure relates to semiconductor structures and, more particularly, to a heterojunction bipolar transistor having one or more sealed airgap and methods of manufacture. The structure includes: a subcollector region in a substrate; a collector region above the substrate; a sealed airgap formed at least partly in the collector region; a base region adjacent to the collector region; and an emitter region adjacent to the base region.