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.

Vertical channel field effect transistors and methods of forming the same include forming one or more vertical channels on a bottom source/drain layer. A seed layer is deposited on horizontal surfaces around the one or more vertical channels. A metal gate is deposited on the seed layer. A top source/drain layer is deposited above the one or more vertical channels and the metal gate.

Vertical channel field effect transistors and methods of forming the same include forming one or more vertical channels on a bottom source/drain layer. A seed layer is deposited on horizontal surfaces around the one or more vertical channels. A metal gate is deposited on the seed layer. A top source/drain layer is deposited above the one or more vertical channels and the metal gate.

Vertical channel field effect transistors include a bottom source/drain layer. One or more vertical channels are formed on the bottom source/drain layer. A horizontal seed layer is formed around the one or more vertical channels. A metal gate is formed directly on the seed layer. A top source/drain is formed layer above the one or more vertical channels and the metal gate.

Embodiments of the invention are directed to a vertical FET device having gate and source or drain features. The device includes a fin formed in a substrate and a source or a drain region formed in the substrate. The device further includes a trench formed in the source or the drain region and a dielectric region formed in the trench. The device further includes a gate formed along vertical sidewalls of the fin and positioned such that a space between the gate and the source or the drain region includes at least a portion of the dielectric region. In some embodiments, the device further includes a bottom spacer formed over an upper surface of the dielectric region and positioned such that the space between the gate and the source or the drain region further includes at least a portion of the bottom spacer.

Techniques for producing stacked SiGe nanowires using a condensation process without parasitic Ge nanowires as an undesired by-product. In one aspect, a method of forming SiGe nanowires includes the steps of: forming a stack of alternating Si and SiGe layers on a wafer; patterning fins in the stack; selectively thinning the SiGe layers in the fins such that the Si and SiGe layers give the fins an hourglass shape; burying the fins in an oxide material; and annealing the fins under conditions sufficient to diffuse Ge from the SiGe layers in the fins to the Si layers in the fins to form the SiGe nanowires. A FET device and method for formation thereof are also provided.

A semiconductor device structure, along with methods of forming such, are described. The structure includes a source/drain epitaxial feature disposed over a substrate, and the source/drain epitaxial feature includes about 0.002 atomic percent to about 0.02 atomic percent of aluminum. The structure further includes a first semiconductor layer in contact with the source/drain epitaxial feature and a gate electrode layer disposed over the first semiconductor layer.

An integrated circuit includes a substrate having a semiconductor layer. The integrated circuit includes a transistor. The transistor includes stacked channels above the semiconductor layer, a first source/drain region in contact with the channels, and a second source/drain region in contact with the channels. A backside source/drain contact is positioned in the substrate directly below and electrically coupled to the first source/drain region. A frontside source/drain contact is directly above and electrically coupled to the first source/drain region. A bottom semiconductor structure is positioned below the second source/drain region and in contact with the semiconductor layer.

A method of processing a substrate that includes: forming a bottom passivation layer including an oxide over a first portion of a dielectric layer at a bottom of a recess of the substrate, the recess having sidewalls including a second portion of the dielectric layer; and performing a lateral etch to etch the second portion of the dielectric layer, the bottom passivation layer covering the first portion of the dielectric layer during the lateral etch, and where the forming of the bottom passivation layer includes exposing the substrate to a first plasma including a halogen, and exposing the substrate to a second plasma including oxygen to form the bottom passivation layer.

An insulating film and another insulating film are formed over a semiconductor substrate in that order to cover first, second, and third gate electrodes. The another insulating film is etched back to form sidewall spacers over side surfaces of the insulating film. Then, the sidewall spacers over the side surfaces of the insulating films corresponding to the sidewalls of the first and second gate electrodes are removed to leave the sidewall spacers over the side surfaces of the insulating film corresponding to the sidewalls of the third gate electrode. Then, the sidewall spacers and the insulating films are etched back, so that the sidewall spacers are formed of the insulating film over the sidewalls of the first, second, and third gate electrodes.