A semiconductor device includes a substrate, first and second fins protruding from the substrate, and first and second source/drain (S/D) features over the first and second fins respectively. The semiconductor device further includes an isolation feature over the substrate and disposed between the first and second S/D features, and a dielectric layer disposed on sidewalls of the first and second S/D features and on sidewalls of the isolation feature. A top portion of the isolation feature extends above the dielectric layer.

A method and structure directed to providing a source/drain isolation structure includes providing a device having a first source/drain region adjacent to a second source/drain region. A masking layer is deposited between the first and second source/drain regions and over an exposed first part of the second source/drain region. After depositing the masking layer, a first portion of an ILD layer disposed on either side of the masking layer is etched, without substantial etching of the masking layer, to expose a second part of the second source/drain region and to expose the first source/drain region. After etching the first portion of the ILD layer, the masking layer is etched to form an L-shaped masking layer. After forming the L-shaped masking layer, a first metal layer is formed over the exposed first source/drain region and a second metal layer is formed over the exposed second part of the second source/drain region.

A method of forming a semiconductor structure includes forming a plurality of fins over a substrate, at least a portion of one or more of the fins providing one or more channels for one or more fin field-effect transistors. The method also includes forming a plurality of active gate structures over the fins, forming at least one single diffusion break trench between a first one of the active gate structures and a second one of the active gate structures, and forming at least one double diffusion break trench between a third one of the active gate structures and a fourth one of the active gate structures. The double diffusion break trench has a stepped height profile in the substrate, the stepped height profile comprising a first depth with a first width and a second depth less than the first depth with a second width greater than the first width.

Embodiments of the invention are directed to a semiconductor-based structure. A non-limiting example of the semiconductor-based structure includes a fin formed over a substrate. A tunnel is formed through the fin to define an upper fin region and a lower fin region. A gate structure is configured to wrap around a circumference of the upper fin region.

A semiconductor structure and a forming method thereof are provided. In one form, a forming method includes: providing a base, including a device region and a zero mark region; forming a zero mark trench inside the base in the zero mark region; filling the zero mark trench, to form a dielectric layer; forming a fin mask material layer covering the base and the dielectric layer; forming a mandrel layer on the fin mask material layer above the dielectric layer and the base in the device region, where the mandrel layer covers a top portion of the dielectric layer; forming a mask spacer on a side wall of the mandrel layer; removing the mandrel layer; etching the fin mask material layer by using the mask spacer as a mask after the mandrel layer is removed, to form a fin mask layer; and etching a partial thickness of the base using the fin mask layer as a mask, where the remaining base after etching is used as a substrate, and a protrusion located over the substrate in the device region is used as a fin, and etching a partial thickness of the dielectric layer during the etching of the base. In the present disclosure, after a fin is formed by filling a zero mark trench with a dielectric layer, a probability that a residue defect or a peeling defect occurs is relatively low.

A 3D semiconductor device including: a first level including a plurality of first metal layers; a second level, where the second level overlays the first level, where the second level includes at least one single crystal silicon layer, where the second level includes a plurality of transistors, where each transistor of the plurality of transistors includes a single crystal channel, where the second level includes a plurality of second metal layers, where the plurality of second metal layers include interconnections between the transistors of the plurality of transistors, and where the second level is overlaid by a first isolation layer; and a connective path between the plurality of transistors and the plurality of first metal layers, where the connective path includes a via disposed through at least the single crystal silicon layer, and where the via includes contact with at least one of the plurality of transistors.

A 3D semiconductor device including: a first level including a single crystal silicon layer and a plurality of first transistors, the plurality of first transistors each including a single crystal channel; a first metal layer overlaying the plurality of first transistors; a second metal layer overlaying the first metal layer; a third metal layer overlaying the second metal layer; a second level is disposed above the third metal layer, where the second level includes a plurality of second transistors; a fourth metal layer disposed above the second level; and a connective path between the fourth metal layer and either the third metal layer or the second metal layer, where the connective path includes a via disposed through the second level, where the via has a diameter of less than 800 nm and greater than 5 nm, and where at least one of the plurality of second transistors includes a metal gate.

Semiconductor devices is provided. The semiconductor device includes a semiconductor substrate having a first region and an adjacent second region; a plurality of adjacent first fins in the first region of the semiconductor substrate; a plurality of adjacent second fins in the second region of the semiconductor substrate; a first type of fin sidewall spacers; a second type of fin sidewall spacers; first doped layers formed between adjacent first type of fin sidewall spacers in the first region; and second doped layers formed between adjacent first type of fin sidewall spacers in the second region.

A method for forming a semiconductor structure includes providing a substrate, including a first region and a second region; forming a plurality of fin structures on the substrate; forming an isolation structure between adjacent fin structures; forming a mask layer over the substrate and the plurality of fin structures; forming an opening by removing a portion of the mask layer formed in the first region; removing a portion of the isolation structure exposed in the opening by using a remaining portion of the mask layer as a mask; removing the remaining portion of the mask layer; and forming a gate structure across the plurality of fin structures. The gate structure covers the first region.

A method includes depositing a semiconductor stack within a first region and a second region on a substrate, the semiconductor stack having alternating layers of a first type of semiconductor material and a second type of semiconductor material. The method further includes removing a portion of the semiconductor stack from the second region to form a trench and with an epitaxial growth process, filling the trench with the second type of semiconductor material. The method further includes patterning the semiconductor stack within the first region to form a nanostructure stack, patterning the second type of semiconductor material within the second region to form a fin structure, and forming a gate structure over both the nanostructure stack and the fin structure.