A method for manufacturing a bipolar transistor, including the steps of: forming a first surface-doped region of a semiconductor substrate having a semiconductor layer extending thereon with an interposed first insulating layer; forming, at the surface of the device, a stack of a silicon layer and of a second insulating layer; defining a trench crossing the stack and the semiconductor layer opposite to the first doped region, and then an opening in the exposed region of the first insulating layer; forming a single-crystal silicon region in the opening; forming a silicon-germanium region at the surface of single-crystal silicon region, in contact with the remaining regions of the semiconductor layer and of the silicon layer; and forming a second doped region at least in the remaining space of the trench.

A layout method for compound semiconductor integrated circuits, comprising following steps of: forming a first metal layer within a first circuit layout area which intersects with a second circuit layout area at an intersection area on a compound semiconductor substrate; defining an adjacent crossover area including said intersection area and a peripheral adjacent area thereof; a first dielectric area located within said adjacent crossover area and intersected with at least part of said intersection area; forming a first dielectric block within said first dielectric area or forming said first dielectric block within said first dielectric area and a second dielectric block outside said first dielectric area, the thickness of said second dielectric block is no greater than and the thickness of at least part of said second dielectric block is smaller than the thickness of said first dielectric block; forming a second metal layer within said second circuit layout area.

Disconnection of a base line is suppressed even when a short-side direction of a collector layer is parallel to crystal orientation [011]. A bipolar transistor includes: a collector layer that has a long-side direction and a short-side direction in a plan view, in which the short-side direction is parallel to crystal orientation [011], a cross-section perpendicular to the short-side direction has an inverted mesa shape, and a cross-section perpendicular to the long-side direction has a forward mesa shape; a base layer that is formed on the collector layer; a base electrode that is formed on the base layer; and a base line that is connected to the base electrode and that is drawn out from an end in the short-side direction of the collector layer to the outside of the collector layer in a plan view.

Device structure and fabrication methods for a bipolar junction transistor. One or more trench isolation regions are formed in a substrate to define a device region having a first width. A protect layer is formed on a top surface of the one or more trench isolation regions and a top surface of the device region. An opening is formed in the protect layer. The opening is coincides with the top surface of the first device region and has a second width that is less than or equal to the first width of the first device region. A base layer is formed that has a first section on the device region inside the first opening and a second section on the protect layer.

Embodiments of the present disclosure describe apparatuses, methods, and systems of an integrated circuit (IC) device. The IC device includes a diffusion control layer as part of an emitter epitaxial structure. The IC device may utilize a common metallization scheme to simultaneously form an emitter contact and a base contact. Other embodiments may also be described and/or claimed.

Device structure and fabrication methods for a bipolar junction transistor. One or more trench isolation regions are formed in a substrate to define a device region having a first width. A protect layer is formed on a top surface of the one or more trench isolation regions and a top surface of the device region. An opening is formed in the protect layer. The opening is coincides with the top surface of the first device region and has a second width that is less than or equal to the first width of the first device region. A base layer is formed that has a first section on the device region inside the first opening and a second section on the protect layer.

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 HBT on a GaAs substrate is presented, wherein its base comprises a first base layer comprising In.sub.iGa.sub.1-iAs with an Indium content i with a slope s1 and a second base layer on the emitter side comprising In.sub.iGa.sub.1-jAs with an Indium content j with a slope s2, and an average of s1 is half of the average of s2 or smaller; or the base comprises a first base layer comprising In.sub.mGa.sub.1-mAs with an Indium content m and a second base layer on the emitter side comprising In.sub.nGa.sub.1-nAs with an Indium content n, and an average of n is larger than the m at a second base layer side; or the base comprises a first base layer pseudomorphic to GaAs with a bulk lattice constant larger than GaAs, and the emitter comprises a first emitter layer pseudomorphic to GaAs with a bulk lattice constant smaller than GaAs.

A method of making a graphene base transistor with reduced collector area comprising forming a graphene material layer, forming a collector material, depositing a dielectric, planarizing the dielectric, cleaning and removing the native oxide, transferring a base graphene material layer to the top surface of the graphene material layer, bonding the base graphene material layer, and photostepping and defining a second graphene material layer. A method of making a graphene base transistor with reduced collector area comprising forming an electron injection region, forming an electron collection region, and forming a base region. A graphene base transistor with reduced collector area comprising an electron emitter region, an electron collection region, and a base region.

Device structures and fabrication methods for a heterojunction bipolar transistor. A first base layer is formed on a first device region of a substrate. A first emitter is formed that defines a first junction with the first base layer. A second base layer is formed on a second device region of a substrate. A second emitter is formed that defines a second junction with the second base layer. The first base layer and the second base layer differ in thickness, composition, concentration of an electrically-active dopant, or a combination thereof.