Abstract:
A modified silicon substrate having a substantially defect-free strain relaxed buffer layer of SiGe is suitable for use as a foundation on which to construct a high performance CMOS FinFET device. The substantially defect-free SiGe strain-relaxed buffer layer can be formed by making cuts in, or segmenting, a strained epitaxial film, causing edges of the film segments to experience an elastic strain relaxation. When the segments are small enough, the overall film is relaxed so that the film is substantially without dislocation defects. Once the substantially defect-free strain-relaxed buffer layer is formed, strained channel layers can be grown epitaxially from the relaxed SRB layer. The strained channel layers are then patterned to create fins for a FinFET device. In one embodiment, dual strained channel layers are formed—a tensilely strained layer for NFET devices, and a compressively strained layer for PFET devices.
Abstract:
Integrated circuits are disclosed in which the strain properties of adjacent pFETs and nFETs are independently adjustable. The pFETs include compressive-strained SiGe on a silicon substrate, while the nFETs include tensile-strained silicon on a strain-relaxed SiGe substrate. Adjacent n-type and p-type FinFETs are separated by electrically insulating regions formed by a damascene process. During formation of the insulating regions, the SiGe substrate supporting the n-type devices is permitted to relax elastically, thereby limiting defect formation in the crystal lattice of the SiGe substrate.
Abstract:
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.
Abstract:
Manufacture of a transistor device with at least one P type transistor with channel structure strained in uniaxial compression strain starting from a silicon layer strained in biaxial tension, by amorphisation recrystallisation then germanium condensation.
Abstract:
Methods and structures for forming a localized, strained region of a substrate are described. Trenches may be formed at boundaries of a localized region of a substrate. An upper portion of sidewalls at the localized region may be covered with a covering layer, and a lower portion of the sidewalls at the localized region may not be covered. A converting material may be formed in contact with the lower portion of the localized region, and the substrate heated. The heating may introduce a chemical species from the converting material into the lower portion, which creates stress in the localized region. The methods may be used to form strained-channel finFETs.
Abstract:
A tensile strained silicon layer is patterned to form a first group of fins in a first substrate area and a second group of fins in a second substrate area. The second group of fins is covered with a tensile strained material, and an anneal is performed to relax the tensile strained silicon semiconductor material in the second group of fins and produce relaxed silicon semiconductor fins in the second area. The first group of fins is covered with a mask, and silicon-germanium material is provided on the relaxed silicon semiconductor fins. Germanium from the silicon germanium material is then driven into the relaxed silicon semiconductor fins to produce compressive strained silicon-germanium semiconductor fins in the second substrate area (from which p-channel finFET devices are formed). The mask is removed to reveal tensile strained silicon semiconductor fins in the first substrate area (from which n-channel finFET devices are formed).
Abstract:
A self-aligned SiGe FinFET device features a relaxed channel region having a high germanium concentration. Instead of first introducing germanium into the channel and then attempting to relax the resulting strained film, a relaxed channel is formed initially to accept the germanium. In this way, a presence of germanium can be established without straining or damaging the lattice. Gate structures are patterned relative to intrinsic silicon fins, to ensure that the gates are properly aligned, prior to introducing germanium into the fin lattice structure. After aligning the gate structures, the silicon fins are segmented to elastically relax the silicon lattice. Then, germanium is introduced into the relaxed silicon lattice, to produce a SiGe channel that is substantially stress-free and also defect-free. Using the method described, concentration of germanium achieved in a structurally stable film can be increased to a level greater than 85%.
Abstract:
Methods and structures for forming strained-channel finFETs are described. Fin structures for finFETs may be formed using two epitaxial layers of different lattice constants that are grown over a bulk substrate. A first thin, strained, epitaxial layer may be cut to form strain-relieved base structures for fins. The base structures may be constrained in a strained-relieved state. Fin structures may be epitaxially grown in a second layer over the base structures. The constrained base structures can cause higher amounts of strain to form in the epitaxially-grown fins than would occur for non-constrained base structures.
Abstract:
Methods and structures for forming a localized, strained region of a substrate are described. Trenches may be formed at boundaries of a localized region of a substrate. An upper portion of sidewalls at the localized region may be covered with a covering layer, and a lower portion of the sidewalls at the localized region may not be covered. A converting material may be formed in contact with the lower portion of the localized region, and the substrate heated. The heating may introduce a chemical species from the converting material into the lower portion, which creates stress in the localized region. The methods may be used to form strained-channel finFETs.
Abstract:
A static induction transistor is formed on a silicon carbide substrate doped with a first conductivity type. First recessed regions in a top surface of the silicon carbide substrate are filled with epitaxially grown gate regions in situ doped with a second conductivity type. Epitaxially grown channel regions in situ doped with the first conductivity type are positioned between adjacent epitaxial gate regions. Epitaxially grown source regions in situ doped with the first conductivity type are positioned on the epitaxial channel regions. The bottom surface of the silicon carbide substrate includes second recessed regions vertically aligned with the channel regions and silicided to support formation of the drain contact. The top surfaces of the source regions are silicided to support formation of the source contact. A gate lead is epitaxially grown and electrically coupled to the gate regions, with the gate lead silicided to support formation of the gate contact.