A method is presented for forming a diffusion barrier in a field effect transistor with a source. A raised source is formed at least partially on the source with the raised source comprising III-V material. An interfacial layer is formed at least partially on the raised source with the interfacial layer comprising silicon or germanium. A metal layer is formed at least partially on the interfacial layer with the metal layer comprising transition metal. The diffusion barrier is formed at least partially on the raised source with the diffusion barrier layer comprising transition metal from the metal layer bonded to silicon or germanium from the interfacial layer. Similar processing forms a corresponding diffusion barrier on a raised drain.

A semiconductor device includes a semiconductor substrate, a gate structure formed over the semiconductor substrate, and an epitaxial structure formed partially within the semiconductor substrate. A vertically extending portion of the epitaxial structure extends vertically above a top surface of the semiconductor substrate in an area adjacent the gate structure. A laterally extending portion of the epitaxial structure extends laterally at an area below the top surface of the semiconductor substrate in a direction toward an area below the gate structure and beyond an area where the epitaxial structure extends vertically. The device further includes an interlayer dielectric layer between a side surface of the vertically extending portion of the epitaxial structure and a side surface of the gate structure. A top surface of the laterally extending portion of the epitaxial structure directly contacts the interlayer dielectric layer.

A method to form a semiconductor structure with an active region and a compatible dielectric layer is described. In one embodiment, a semiconductor structure has a dielectric layer comprised of an oxide of a first semiconductor material, wherein a second (and compositionally different) semiconductor material is formed between the dielectric layer and the first semiconductor material. In another embodiment, a portion of the second semiconductor material is replaced with a third semiconductor material in order to impart uniaxial strain to the lattice structure of the second semiconductor material.

A method for manufacturing a semiconductor device includes forming one or more fins extending in a first direction over a substrate. The one or more fins include a first region along the first direction and second regions on both sides of the first region along the first direction. A dopant is implanted in the first region of the fins but not in the second regions. A gate structure overlies the first region of the fins and source/drains are formed on the second regions of the fins.

Techniques related to III-N transistors having self aligned gates, systems incorporating such transistors, and methods for forming them are discussed. Such transistors include a polarization layer between a raised source and a raised drain, a gate between the source and drain and over the polarization layer, and lateral epitaxial overgrowths over the source and drain and having and opening therebetween such that at least a portion of the gate adjacent to the polarization layer is aligned with the opening.

After forming an epitaxial semiconductor layer on portions of a semiconductor located on opposite sides of a sacrificial gate structure, dopants from the epitaxial semiconductor layer are diffused into the semiconductor fin to form a dopant-containing semiconductor fin. A sacrificial gate stack is removed to provide a gate cavity that exposes a portion of the dopant-containing semiconductor fin. The exposed portion of the dopant-containing semiconductor fin is removed to provide an opening underneath the gate cavity. A channel which is undoped or less doped than remaining portions of the dopant-containing semiconductor fin is epitaxially grown at least from the sidewalls of the remaining portions of the dopant-containing semiconductor fin. Abrupt junctions are thus formed between the channel region and the remaining portions of the dopant-containing semiconductor fin.

A method includes forming a first material stack above a first transistor region, a second transistor region, and a dummy gate region of a semiconductor structure, the first material stack including a high-k material layer and a workfunction adjustment metal layer. The first material stack is patterned to remove a first portion of the first material stack from above the dummy gate region while leaving second portions of the first material stack above the first and second transistor regions. A gate electrode stack is formed above the first and second transistor regions and above the dummy gate region, and the gate electrode stack and the remaining second portions of the first material stack are patterned to form a first gate structure above the first transistor region, a second gate structure above the second transistor region, and a dummy gate structure above the dummy gate region.

A semiconductor device includes a substrate including a plurality of transistor devices formed thereon, at least an epitaxial structure formed in between the transistor devices, and a tri-layered structure formed on the epitaxial structure. The epitaxial structure includes a first semiconductor material and a second semiconductor material, and a lattice constant of the second semiconductor material is larger than a lattice constant of the first semiconductor material. The tri-layered structure includes an undoped epitaxial layer, a metal-semiconductor compound layer, and a doped epitaxial layer sandwiched in between the undoped epitaxial layer and the metal-semiconductor compound layer. The undoped epitaxial layer and the doped epitaxial layer include at least the second semiconductor material.

An integrated circuit includes an NMOS transistor, a PMOS transistor and a vertical bipolar transistor. The vertical bipolar transistor has an intrinsic base with a band barrier at least 25 meV high at a surface boundary of the intrinsic base, except at an emitter-base junction with an emitter, and except at a base-collector junction with a collector. The intrinsic base may be laterally surrounded by an extrinsic base with a higher dopant density than the intrinsic base, wherein a higher dopant density provides the band barrier at lateral surfaces of the intrinsic base. A gate may be disposed on a gate dielectric layer over a top surface boundary of the intrinsic base adjacent to the emitter. The gate is configured to accumulate the intrinsic base immediately under the gate dielectric layer, providing the band barrier at the top surface boundary of the intrinsic base.

A transistor having a narrow bandgap semiconductor source/drain region is described. The transistor includes a gate electrode formed on a gate dielectric layer formed on a silicon layer. A pair of source/drain regions are formed on opposite sides of the gate electrode wherein said pair of source/drain regions comprise a narrow bandgap semiconductor film formed in the silicon layer on opposite sides of the gate electrode.