Embodiments of the present disclosure include contact structures and methods of forming the same. An embodiment is a method of forming a semiconductor device, the method including forming a contact region over a substrate, forming a dielectric layer over the contact region and the substrate, and forming an opening through the dielectric layer to expose a portion of the contact region. The method further includes forming a metal-silicide layer on the exposed portion of the contact region and along sidewalls of the opening; and filling the opening with a conductive material to form a conductive plug in the dielectric layer, the conductive plug being electrically coupled to the contact region.

A device includes a first channel region and a first gate structure formed over the first channel region. A first source/drain region is adjacent the first channel region and the first source/drain region includes a crystalline structure doped with a first dopant. A first silicide is formed over the first source/drain region. The first source/drain region includes a first concentration of the first dopant between 2.010.sup.21 atoms per centimeter cubed and 4.010.sup.21 atoms per centimeter cubed at a depth of 8 to 10 nanometers. A gradient of decreasing concentration of the first dopant is one decade for every 5.5 to 7.5 nanometers deeper than the first concentration.

A field oxide film lies extending from the underpart of a gate electrode to a drain region. A plurality of projection parts projects from the side face of the gate electrode from a source region side toward a drain region side. The projection parts are arranged side by side along a second direction (direction orthogonal to a first direction along which the source region and the drain region are laid) in plan view. A plurality of openings is formed in the field oxide film. Each of the openings is located between projection parts adjacent to each other when seen from the first direction. The edge of the opening on the drain region side is located closer to the source region than the drain region. The edge of the opening on the source region side is located closer to the drain region than the side face of the gate electrode.

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 semiconductor device with multiple silicide regions is provided. In embodiments a first silicide precursor and a second silicide precursor are deposited on a source/drain region. A first silicide with a first phase is formed, and the second silicide precursor is insoluble within the first phase of the first silicide. The first phase of the first silicide is modified to a second phase of the first silicide, and the second silicide precursor being soluble within the second phase of the first silicide. A second silicide is formed with the second silicide precursor and the second phase of the first silicide.

A semiconductor device includes a semiconductor fin, a gate structure, source/drain structures, and a contact structure. The semiconductor fin extends from a substrate. The gate structure extends across the semiconductor fin. The source/drain structures are on opposite sides of the gate structure. The contact structure is over a first one of the source/drain structures. The contact structure includes a semiconductor contact and a metal contact over the semiconductor contact. The semiconductor contact has a higher dopant concentration than the first one of the source/drain structures. The first one of the source/drain structures includes a first portion and a second portion at opposite sides of the fin and interfacing the semiconductor contact.

A FinFET device and a method of forming the same are disclosed. In accordance with some embodiments, a FinFET device includes a substrate having at least one fin, a gate stack across the at least one fin, a strained layer aside the gate stack and a silicide layer over the strained layer. The strained layer has a boron surface concentration greater than about 2E20 atom/cm.sup.3 within a depth range of about 0-5 nm from a surface of the strained layer.

A semiconductor process is described. A silicon-phosphorus (SiP) epitaxial layer is formed serving as a source/drain (S/D) region. A crystalline metal silicide layer is formed directly on the SiP epitaxial layer and thus prevents oxidation of the SiP epitaxial layer. A contact plug is formed over the crystalline metal silicide layer.

An integrated circuit with an MOS transistor abutting field oxide and a gate structure on the field oxide adjacent to the MOS transistor and a gap between an epitaxial source/drain and the field oxide is formed with a silicon dioxide-based gap filler in the gap. Metal silicide is formed on the exposed epitaxial source/drain region. A CESL is formed over the integrated circuit and a PMD layer is formed over the CESL. A contact is formed through the PMD layer and CESL to make an electrical connection to the metal silicide on the epitaxial source/drain region.