A gate insulating film and a gate electrode of non-single crystalline silicon for forming an nMOS transistor are provided on a silicon substrate. Using the gate electrode as a mask, n-type dopants having a relatively large mass number (70 or more) such as As ions or Sb ions are implanted, to form a source/drain region of the nMOS transistor, whereby the gate electrode is amorphized. Subsequently, a silicon oxide film is provided to cover the gate electrode, at a temperature which is less than the one at which recrystallization of the gate electrode occurs. Thereafter, thermal processing is performed at a temperature of about 1000 C., whereby high compressive residual stress is exerted on the gate electrode, and high tensile stress is applied to a channel region under the gate electrode. As a result, carrier mobility of the nMOS transistor is enhanced.

A device includes a substrate and insulation regions over a portion of the substrate. A first semiconductor region is between the insulation regions and having a first conduction band. A second semiconductor region is over and adjoining the first semiconductor region, wherein the second semiconductor region includes an upper portion higher than top surfaces of the insulation regions to form a semiconductor fin. The semiconductor fin has a tensile strain and has a second conduction band lower than the first conduction band. A third semiconductor region is over and adjoining a top surface and sidewalls of the semiconductor fin, wherein the third semiconductor region has a third conduction band higher than the second conduction band.

A semiconductor device includes at least one semiconductor fin on an upper surface of a base substrate. The at least one semiconductor fin includes a strained active semiconductor portion interposed between a protective cap layer and the base substrate. A gate stack wraps around the at least one semiconductor fin. The gate stack includes a metal gate element interposed between a pair of first cap segments of the protective cap layer. The strained active semiconductor portion is preserved following formation of the fin via the protective cap layer.

Methods and structures for forming strained-channel FETs are described. A strain-inducing layer may be formed under stress in a silicon-on-insulator substrate below the insulator. Stress-relief cuts may be formed in the strain-inducing layer to relieve stress in the strain-inducing layer. The relief of stress can impart strain to an adjacent semiconductor layer. Strained-channel, fully-depleted SOI FETs and strained-channel finFETs may be formed from the adjacent semiconductor layer. The amount and type of strain may be controlled by etch depths and geometries of the stress-relief cuts and choice of materials for the strain-inducing layer.

A semiconductor device may include a strain relaxed buffer layer provided on a substrate to contain silicon germanium, a semiconductor pattern provided on the strain relaxed buffer layer to include a source region, a drain region, and a channel region connecting the source region with the drain region, and a gate electrode enclosing the channel region and extending between the substrate and the channel region. The source and drain regions may contain germanium at a concentration of 30 at % or higher.

A semiconductor structure includes an isolation feature formed in the semiconductor substrate and a first fin-type active region. The first fin-type active region extends in a first direction. A dummy gate stack is disposed on an end region of the first fin-type active region. The dummy, gate stack may overlie an isolation structure. In an embodiment, any recess such as formed for a source/drain region in the first fin-type active region will be displaced from the isolation region by the distance the dummy gate stack overlaps the first fin-type active region.

Transistors include multiple stress liners. One or more channel structures are suspended at opposite ends from the plurality of stress liners. The stress liners provide a stress on the one or more channel structures. A gate is formed over and around the one or more channel structures, defining a channel region of the one or more channel structures that is covered by the gate. A source and drain region are formed on opposite sides of the gate.

Transistors and methods of forming the same include forming a fin of alternating layers of a channel material and a sacrificial material. Stress liners are formed in contact with both ends of the fin. The stress liners exert a stress on the fin. The sacrificial material is etched away from the fin, such that the layers of the channel material are suspended between the stress liners. A gate stack is formed over and around the suspended layers of channel material.

Techniques are disclosed for enabling multi-sided condensation of semiconductor fins. The techniques can be employed, for instance, in fabricating fin-based transistors. In one example case, a strain layer is provided on a bulk substrate. The strain layer is associated with a critical thickness that is dependent on a component of the strain layer, and the strain layer has a thickness lower than or equal to the critical thickness. A fin is formed in the substrate and strain layer, such that the fin includes a substrate portion and a strain layer portion. The fin is oxidized to condense the strain layer portion of the fin, so that a concentration of the component in the strain layer changes from a pre-condensation concentration to a higher post-condensation concentration, thereby causing the critical thickness to be exceeded.

A semiconductor device includes a substrate, a first active fin and a second active fin on the substrate, respectively, a plurality of first epitaxial layers on the first active fin and on the second active fin, respectively, a plurality of second epitaxial layers on the plurality of first epitaxial layers, a bridge layer connecting the plurality of second epitaxial layers to each other, and a third epitaxial layer on the bridge layer.