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:
Channel-to-substrate leakage in a FinFET device is prevented by inserting an insulating layer between the semiconducting channel and the substrate during fabrication of the device. Similarly, source/drain-to-substrate leakage in a FinFET device is prevented by isolating the source/drain regions from the substrate by inserting an insulating layer between the source/drain regions and the substrate. Forming such an insulating layer isolates the conduction path from the substrate both physically and electrically, thus preventing current leakage. In an array of semiconducting fins made up of a multi-layer stack, the bottom material is removed thus yielding a fin array that is suspended above the silicon surface. A resulting gap underneath the remaining top fin material is then filled with oxide to better support the fins and to isolate the array of fins from the substrate.
Abstract:
A method for channel formation in a fin transistor includes removing a dummy gate and dielectric from a dummy gate structure to expose a region of an underlying fin and depositing an amorphous layer including Ge over the region of the underlying fin. The amorphous layer is oxidized to condense out Ge and diffuse the Ge into the region of the underlying fin to form a channel region with Ge in the fin.
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:
Elongated fins of a first semiconductor material are insulated from and formed over an underlying substrate layer. Elongated gates of a second semiconductor material are then formed to cross over the elongated fins at channel regions, and the gate side walls are covered by sidewall spacers. A protective material is provided to cover the underlying substrate layer and define sidewall spacers on side walls of the elongated fins between the elongated gates. The first semiconductor material and insulating material of the elongated fins located between the protective material sidewall spacers (but not under the elongated gates) is removed to form trenches aligned with the channel regions. Additional semiconductor material is then epitaxially grown inside each trench between the elongated gates to form source-drain regions adjacent the channel regions formed by the elongated fins of the first semiconductor material located under the elongated gates.
Abstract:
A method for channel formation in a fin transistor includes removing a dummy gate and dielectric from a dummy gate structure to expose a region of an underlying fin and depositing an amorphous layer including Ge over the region of the underlying fin. The amorphous layer is oxidized to condense out Ge and diffuse the Ge into the region of the underlying fin to form a channel region with Ge in the fin.
Abstract:
A method for forming fins includes growing a SiGe layer and a silicon layer over a surface of a bulk Si substrate, patterning fin structures from the silicon layer and the SiGe layer and filling between the fin structures with a dielectric fill. Trenches are formed to expose end portions of the fin structures. A first region of the fin structures is blocked off. The SiGe layer of the fin structures of a second region is removed by selectively etching the fin structures from the end portions to form voids, which are filled with dielectric material. The silicon layer of the fin structures is exposed. The SiGe layer in the first region is thermally oxidized to drive Ge into the silicon layer to form SiGe fins on an oxide layer in the first region and silicon fins on the dielectric material in the second region.
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:
A shallow trench is formed to extend into a handle substrate of a semiconductor-on-insulator (SOI) layer. A dielectric liner stack of a dielectric metal oxide layer and a silicon nitride layer is formed in the shallow trench, followed by deposition of a shallow trench isolation fill portion. The dielectric liner stack is removed from above a top surface of a top semiconductor portion, followed by removal of a silicon nitride pad layer and an upper vertical portion of the dielectric metal oxide layer. A divot laterally surrounding a stack of a top semiconductor portion and a buried insulator portion is filled with a silicon nitride portion. Gate structures and source/drain structures are subsequently formed. The silicon nitride portion or the dielectric metal oxide layer functions as a stopping layer during formation of source/drain contact via holes, thereby preventing electrical shorts between source/drain contact via structures and the handle substrate.
Abstract:
Methods and structures for forming localized, differently-strained regions in a semiconductor layer on a substrate are described. An initial, unstrained, semiconductor-on-insulator substrate may be processed to form the differently-strained regions in the original semiconductor layer. The differently-strained regions may have opposite types of strain. The strains in the different regions may be formed independently.