A method includes forming a protruding semiconductor stack including a plurality of sacrificial layers and a plurality of nanostructures, with the plurality of sacrificial layers and the plurality of nanostructures being laid out alternatingly. The method further includes forming a dummy gate structure on the protruding semiconductor stack, etching the protruding semiconductor stack to form a source/drain recess, and forming a source/drain region in the source/drain recess. The formation of the source/drain region includes growing first epitaxial layers. The first epitaxial layers are grown on sidewalls of the plurality of nanostructures, and a cross-section of each of the first epitaxial layers has a quadrilateral shape. The first epitaxial layers have a first dopant concentration. The formation of the source/drain region further includes growing a second epitaxial layer on the first epitaxial layers. The second epitaxial layer has a second dopant concentration higher than the first dopant concentration.

A SiC epitaxial wafer includes a SiC substrate and an epitaxial layer laminated on the SiC substrate, wherein the epitaxial layer comprises a first layer, a second layer and a third layer in order from the SiC substrate side, the nitrogen concentration of the SiC substrate is 6.0×10.sup.18 cm.sup.−3 or more and 1.5×10.sup.19 cm.sup.−3 or less, the nitrogen concentration of the first layer is 1.0×10.sup.17 cm.sup.−3 or more and 1.5×10.sup.18 cm.sup.−3 or less, the nitrogen concentration of the second layer is 1.0×10.sup.18 cm.sup.−3 or more and 5.0×10.sup.18 cm.sup.−3 or less, and the nitrogen concentration of the third layer is 5.0×10.sup.13 cm.sup.−3 or more and 1.0×10.sup.17 cm.sup.−3 or less.

In a method of manufacturing a semiconductor device, a first fin structure, a second fin structure, a first wall fin structure and a second wall fin structure are formed over a substrate. The first and second fin structures are disposed between the first and second wall fin structures, and lower portions of the first and second fin structures and the first and second wall fin structures are embedded in the isolation insulating layer and upper portions thereof are exposed from the isolation insulating layer. A sidewall spacer layer is formed on sidewalls of the first and second fin structures. Source/drain regions of the first and second fin structures are recessed. An epitaxial source/drain structure is formed over the recessed first and second fin structures. A width W1 of the first and second fin structures is smaller than a thickness W2 of the sidewall spacer layer.

[summary]

An epitaxial wafer is disclosed. The epitaxial wafer includes a substrate; and a stack disposed on the substrate, wherein the stack includes silicon (Si) layers and silicon germanium (SiGe) layers alternately stacked on top of each other, wherein the silicon germanium layer is doped with boron (B) or phosphorus (P).

A semiconductor device includes a semiconductor substrate, a semiconductor fin extending from the semiconductor substrate, a gate structure extending across the semiconductor fin, and source/drain semiconductor layers on opposite sides of the gate structure. The source/drain semiconductor layers each have a first thickness over a top side of the semiconductor fin and a second thickness over a lateral side of the semiconductor fin. The first thickness and the second thickness have a difference smaller than about 20 percent of the first thickness.

A semiconductor device includes a plurality of tunnel diodes, each of which includes a first semiconductor region of a first conductive type and a second semiconductor region of a second conductive type that is provided above the first semiconductor region, the second semiconductor region being a nanowire shape; an insulating film provided around a side surface of the second semiconductor region; a plurality of first electrodes, each coupled to the first semiconductor region; and a plurality of second electrodes, each coupled to the second semiconductor region, wherein the second electrode has a first surface that faces the side surface of the second semiconductor region across the insulating film, and a diameter of a second semiconductor region of a first tunnel diode of the plurality of tunnel diodes is different from a diameter of a second semiconductor region of a second tunnel diode.

Exemplary semiconductor processing methods may include forming a p-type silicon-containing material on a substrate including a first n-type silicon-containing material defining one or more features. The p-type silicon-containing material may extend along at least a portion of the one or more features defined in the first n-type silicon-containing material. The methods may include removing a portion of the p-type silicon-containing material. The portion of the p-type silicon-containing material may be removed from a bottom of the one or more features. The methods may include providing a silicon-containing material. The methods may include depositing a second n-type silicon-containing material on the substrate. The second n-type silicon-containing material may fill the one or more features formed in the first n-type silicon-containing material and may separate regions of remaining p-type silicon-containing material.

The present disclosure describes a semiconductor device and methods for forming the same. The semiconductor device includes nanostructures on a substrate and a source/drain region in contact with the nanostructures. The source/drain region includes epitaxial end caps, where each epitaxial end cap is formed at an end portion of a nanostructure of the nanostructures. The source/drain region also includes an epitaxial body in contact with the epitaxial end caps and an epitaxial top cap formed on the epitaxial body. The semiconductor device further includes gate structure formed on the nanostructures.

A compound semiconductor has a high electron concentration of 5×10.sup.19 cm.sup.−3 or higher, exhibits an electron mobility of 46 cm.sup.2/V.Math.s or higher, and exhibits a low electric resistance, and thus is usable to produce a high performance semiconductor device. The present invention provides a group 13 nitride semiconductor of n-type conductivity that may be formed as a film on a substrate having a large area size at a temperature of room temperature to 700° C.

In a method for manufacturing a semiconductor device, an isolation insulating layer is formed over a fin structure. A first portion of the fin structure is exposed from and a second portion of the fin structure is embedded in the isolation insulating layer. A dielectric layer is formed over sidewalls of the first portion of the fin structure. The first portion of the fin structure and a part of the second portion of the fin structure in a source/drain region are removed, thereby forming a trench. A source/drain epitaxial structure is formed in the trench using one of a first process or a second process. The first process comprises an enhanced epitaxial growth process having an enhanced growth rate for a preferred crystallographic facet, and the second process comprises using a modified etch process to reduce a width of the source/drain epitaxial structure.