A method for producing a semiconductor device includes forming a semiconductor-pillar on a substrate and forming a laminated-structure of at least two composite layers, each including a metal layer and a semiconductor layer in contact with the metal layer, the semiconductor layer containing donor or acceptor atoms, and two interlayer insulating layers sandwiching the composite layers, such that a side surface of at least one of the two interlayer insulating layers is separated from a side surface of the semiconductor pillar. The laminated-structure surrounds the semiconductor pillar. A first heat treatment causes a reaction between the metal layer and the semiconductor layer to form an alloy layer, and brings the alloy layer into contact with the side surface of the semiconductor pillar. A second heat treatment to expands the alloy layer into the semiconductor pillar and diffuses dopant atoms into the semiconductor pillar to form an impurity region therein.

In one implementation, a reliable and robust electrical contact includes a contact pad patterned from a first metal layer situated over a surface of an active die, and multiple dielectric islands situated over the contact pad. The dielectric islands are spaced apart from one another by respective segments of a second metal layer formed between and over the dielectric islands. The contact pad, the dielectric islands, and the second metal layer provide the reliable and robust electrical contact.

Various embodiments disclose a method for fabricating a semiconductor structure including a plurality of vertical transistors each having different threshold voltages. In one embodiment the method includes forming a structure having at least a substrate, a source contact layer on the substrate, a first spacer layer on the source contact layer, a replacement gate on the first spacer layer, a second spacer layer on the replacement gate, and an insulating layer on the second spacer layer. A first trench is formed in a first region of the structure. A first channel layer having a first doping concentration is epitaxially grown in the first trench. A second trench is formed in a second region of the structure. A second channel layer having a second doping concentration is epitaxially grown in the second trench. The second doping concentration is different from the first doping concentration.

A method of fabricating a vertical field effect transistor comprising that includes forming openings through a spacer material to provide fin structure openings to a first semiconductor material, and forming an inner spacer liner on sidewalls of the fin structure openings. A channel semiconductor material is epitaxially formed on a surface of the first semiconductor material filling at least a portion of the fin structure openings. The spacer material is recessed with an etch that is selective to the inner spacer liner to form a first spacer. The inner spacer liner is removed selectively to the channel semiconductor material. A gate structure on the channel semiconductor material, and a second semiconductor material is formed in contact with the channel semiconductor material.

A vertical transistor and the fabrication method. The transistor comprises a first surface and a second surface that is opposite to the first surface. A drift region of the first doping type, this drift region is located between the first surface and the second surface; at least one source region of the first doping type and the source region being located between the drift region and the first surface, with a first dielectric layer located between adjacent source regions; at least one drain region with said first doping type and said drain region being located between said drift region and said second surface, a gate being provided between adjacent drain regions. Said gate includes a gate electrode and a gate dielectric layer disposed between said gate electrode and said drift region, and the second dielectric layer being positioned between said gate electrode and said second surface.

Field effect transistors include a stack of nanosheets of vertically arranged channel layers. A source and drain region is positioned at respective ends of the vertically arranged channel layers. A gate stack is formed over, around, and between the vertically arranged channel layers. The transistor includes a plurality of internal spacers, each formed between the gate stack and a respective source or drain region, with at least one pair of spacers being positioned above an uppermost channel layer.

Various embodiments disclose a method for fabricating one or more vertical fin field-effect-transistors. In one embodiment, a structure is formed. The structure comprises a substrate, a source/drain layer, and a plurality of fins formed on the first source/drain layer. The source/drain layer comprises a first semiconductor layer, a sacrificial layer, and a second semiconductor layer. A bottom spacer layer is formed in contact with the second semiconductor layer and the plurality of fins. A gate structure is then formed. A dielectric layer is deposited in contact with at least the gate structure, the bottom spacer layer, and the second semiconductor layer. At least a portion of the dielectric layer and a portion of the second semiconductor are removed. This removal forms a trench exposing a portion of the sacrificial layer. The sacrificial layer is then removed forming a cavity. A contact material is deposited within the trench and the cavity.

Field effect transistors and methods of forming the same include forming a stack of nanosheets of alternating layers of channel material and sacrificial material. A layer of sacrificial material forms a top layer of the stack. A dummy gate is formed over the stack. Stack material outside of a region covered by the dummy gate is removed. The sacrificial material is etched to form recesses in the sacrificial material layers. Spacers are formed in the recesses in the sacrificial material layers. At least one pair of spacers is formed in recesses above an uppermost layer of channel material. The dummy gates are etched away. The top layer of sacrificial material protects an uppermost layer of channel material from damage from the anisotropic etch. The sacrificial material is etched away to expose the layers of channel material. A gate stack is formed over, around, and between the layers of channel material.

An embodiment semiconductor device includes a nanowire extending upwards from a semiconductor substrate, a source/drain region in the nanowire, and a channel region in the nanowire over the source/drain region. The source/drain region further extends into the semiconductor substrate past edges of the nanowire. The semiconductor device further includes a gate structure encircling the channel region and a silicide in an upper portion of the source/drain region. A sidewall of the silicide is aligned with a sidewall of the gate structure.

Various embodiments disclose a method for fabricating a semiconductor structure including a plurality of vertical transistors each having different threshold voltages. In one embodiment the method includes forming a structure having at least a substrate, a source contact layer on the substrate, a first spacer layer on the source contact layer, a replacement gate on the first spacer layer, a second spacer layer on the replacement gate, and an insulating layer on the second spacer layer. A first trench is formed in a first region of the structure. A first channel layer having a first doping concentration is epitaxially grown in the first trench. A second trench is formed in a second region of the structure. A second channel layer having a second doping concentration is epitaxially grown in the second trench. The second doping concentration is different from the first doping concentration.