A transistor module includes a substrate; a transistor on the substrate; a dielectric layer disposed over the transistor and the substrate; a metal layer disposed over the dielectric layer and the transistor, the metal layer contacting a portion of the transistor; a metal pillar disposed over the metal layer; and a dielectric cushion disposed between the metal layer and the metal pillar over the transistor. The dielectric cushion includes dielectric material that is softer than the metal pillar, for reducing strain on semiconductor junctions when at least one of tensile or compressive stress is exerted on the metal pillar with respect to the substrate. The transistor module may further include at least one buttress formed between the metal layer and the substrate, adjacent to the transistor, for further reducing strain on the semiconductor junctions by providing at least one corresponding alterative stress path that substantially bypasses the transistor.

A semiconductor device includes a substrate having a recessed region, a first semiconductor region including a first semiconductor layer on a bottom surface and an inner side surface of the recessed region and a first protrusion on the first semiconductor layer, and having a first conductivity type, a second semiconductor region including a second semiconductor layer on the first semiconductor layer and a second protrusion on the second semiconductor layer, and having a second conductivity type, a third semiconductor region including a third semiconductor layer on the second semiconductor layer and a third protrusion on the third semiconductor layer, and having the first conductivity type, a epitaxial stopper layer covering the bottom surface of the recessed region between the first semiconductor region and the substrate and including a material different from materials of the first semiconductor region, and a dummy gate structure intersecting the first to third protrusions on the substrate.

Disclosed are embodiments of a transistor, which incorporates an airgap for low base-emitter capacitance (C.sub.be). Each embodiment of the transistor has a monocrystalline base and, within the monocrystalline base, an intrinsic base region and an extrinsic base region positioned laterally adjacent to the intrinsic base region, wherein the intrinsic and extrinsic base regions have co-planar top surfaces. An essentially T-shaped emitter in cross-section has a lower emitter region on the intrinsic base region and an upper emitter region above the lower emitter region. Each embodiment of the transistor further has an airgap, which is positioned laterally adjacent to the lower emitter region so as to be between the extrinsic base region and the upper emitter region. Thus, the entire airgap is above the co-planar top surfaces of the intrinsic base region and the extrinsic base region. Also disclosed herein are methods of forming the transistor embodiments.

Various particular embodiments include an integrated circuit (IC) structure having: 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.

A bipolar transistor is supported by a single-crystal silicon substrate including a collector contact region. A cyclical epitaxy process is performed to provide a collector region of a first conductivity type on the collector contact region that is laterally separated from a silicon layer by an air gap. A second epitaxial region forms a base region of a second conductivity type. Deposited semiconductor material forms an emitter region of the first conductivity type. The collector region, base region and emitter region are located within an opening formed in a stack of insulating layers that includes a sacrificial layer. The sacrificial layer is selectively removed to expose a side wall of the base region. Epitaxial growth from the exposed sidewall forms a base contact region.

Methods of forming integrated chips include forming a gate stack around a first semiconductor fin and a second semiconductor fin. The gate stack around the second semiconductor fin is etched away. An extrinsic base is formed around the second semiconductor fin in a region exposed by etching away the gate stack.

A method includes providing a semiconductor structure having an active region and an isolation structure adjacent to the active region, the active region having source and drain regions sandwiching a channel region for a transistor, the semiconductor structure further having a gate structure over the channel region. The method further includes etching a trench in one of the source and drain regions, wherein the trench exposes a portion of a sidewall of the isolation structure, epitaxially growing a first semiconductor layer in the trench, epitaxially growing a second semiconductor layer over the first semiconductor layer, changing a crystalline facet orientation of a portion of a top surface of the second semiconductor layer by an etching process, and epitaxially growing a third semiconductor layer over the second semiconductor layer after the changing of the crystalline facet orientation.

A method includes providing a semiconductor structure having an active region and an isolation structure adjacent to the active region, the active region having source and drain regions sandwiching a channel region for a transistor, the semiconductor structure further having a gate structure over the channel region. The method further includes etching a trench in one of the source and drain regions, wherein the trench exposes a portion of a sidewall of the isolation structure, epitaxially growing a first semiconductor layer in the trench, epitaxially growing a second semiconductor layer over the first semiconductor layer, changing a crystalline facet orientation of a portion of a top surface of the second semiconductor layer by an etching process, and epitaxially growing a third semiconductor layer over the second semiconductor layer after the changing of the crystalline facet orientation.

Methods according to the present disclosure include: providing a substrate including: a first semiconductor region, a second semiconductor region, and a trench isolation (TI) laterally between the first and second semiconductor regions; forming an epitaxial layer on at least the first semiconductor region of the substrate, wherein the epitaxial layer includes a first semiconductor base material positioned above the first semiconductor region of the substrate; forming an insulator region on at least the first semiconductor base material, the trench isolation (TI), and the second semiconductor region; forming a first opening in the insulator over the second semiconductor region; and growing a second semiconductor base material in the first opening, wherein a height of the second semiconductor base material above the substrate is greater than a height of the first semiconductor base material above the substrate.

A bipolar transistor is described. In accordance with one aspect of the present invention the bipolar transistor comprises a semiconductor body including a collector region and a base region arranged on top of the collector region. The base region has a first crystalline structure and is at least partly doped with dopants of a first doping type. The collector region is laterally enclosed by a trench isolation and is doped with dopants of a second doping type. The transistor further comprises a conductive base contact layer laterally enclosing the base region which is doped with dopants of the first doping type. The base contact layer comprises a part with the first crystalline structure and a part with a second crystalline structure, wherein the part with the second crystalline structure laterally encloses the part with the first crystalline structure. The transistor further comprises an emitter region arranged on the base region, wherein the emitter region is doped with dopants of the second doping type and forming a pn-junction with the base region.