A semiconductor device and fabrication method are described for integrating a nanosheet transistor with a multimodal transistor (MMT) in a single nanosheet process flow by processing a wafer substrate to form buried metal source/drain structures in an MMT region that are laterally spaced apart from one another and positioned below an MMT semiconductor channel layer before forming a transistor stack of alternating Si and SiGe layers in an FET region which are selectively processed to form gate electrode openings so that a first ALD oxide and metal layer are patterned and etched to form gate electrodes in the transistor stack and to form a channel control gate electrode over the MMT semiconductor channel layer, and so that a second oxide and conductive layer are patterned and etched to form a current control gate electrode over the MMT semiconductor channel layer and adjacent to the channel control gate electrode.

A microelectronic structure that includes a stacked nanosheet FET transistor that includes an upper nanosheet transistor and a lower nanosheet transistor. The upper nanosheet transistor includes an upper source/drain and the upper source/drain includes an upper tip that is pointed in a first direction. The lower nanosheet transistor includes a lower source/drain and the lower source/drain includes a lower tip pointed in a second direction. The first direction is different than the second direction.

A method of forming an electrical contact in a semiconductor structure includes performing a cavity shaping process on a semiconductor structures having an n-type metal oxide semiconductor (n-MOS) region and/or a p-type MOS (p-MOS) region, the cavity shaping process comprising forming an n-MOS cavity in an exposed surface of the n-MOS region and/or a p-MOS cavity in an exposed surface of the p-MOS region, wherein the cavity shaping process is configured to increase the surface area of the exposed surface of the n-MOS region or the p-MOS region. In some embodiments, the method includes performing a first selective deposition process to form a p-MOS cavity contact, selectively in the p-MOS cavity.

A device includes a stack of first nanostructures; a first insulating layer adjacent to the stack of first nanostructures; and a first source/drain region over the first insulating layer, wherein the first source/drain region includes: first semiconductor layers, wherein each first semiconductor layer covers a sidewall of a respective first nanostructure, wherein the first semiconductor layers includes a first semiconductor material; second semiconductor layers, wherein each second semiconductor layer covers a sidewall of a respective first semiconductor layer, wherein the second semiconductor layers includes a second semiconductor material different from the first semiconductor material; and a third semiconductor layer on the second semiconductor layer, wherein the third semiconductor layer is a third semiconductor material different from the first semiconductor material and different from the second semiconductor material.

Gate-all-around integrated circuit structures having depopulated channel structures, and methods of fabricating gate-all-around integrated circuit structures having depopulated channel structures using a bottom-up approach, are described. For example, integrated circuit structure includes a first vertical arrangement of nanowires and a second vertical arrangement of nanowires above a substrate. The first vertical arrangement of nanowires has a greater number of nanowires than the second vertical arrangement of nanowires. The first vertical arrangement of nanowires has an uppermost nanowire co-planar with an uppermost nanowire of the second vertical arrangement of nanowires. The first vertical arrangement of nanowires has a bottommost nanowire below a bottommost nanowire of the second vertical arrangement of nanowires. A first gate stack is over the first vertical arrangement of nanowires. A second gate stack is over the second vertical arrangement of nanowires.

A method includes providing a substrate having an epitaxial stack of layers including a plurality of semiconductor channel layers interposed by a plurality of dummy layers. The substrate includes a first device region and a second device region. An etch process is performed to remove a first portion of the epitaxial stack of layers from the second device region to form a trench in the second device region. The removed first portion of the epitaxial stack of layers includes at least one semiconductor channel layer of the plurality of semiconductor channel layers. An epitaxial layer is formed within the trench in the second device region and over the second portion of the epitaxial stack of layers. A top surface of the epitaxial layer in the second device region is substantially level with a top surface of the epitaxial stack of layers in the first device region.

A semiconductor structure includes a first semiconductor device formed in a first device region of a substrate. The first semiconductor device includes a first gate structure comprising a first spacer layer, wherein the first spacer layer has a first thickness. The first semiconductor device also includes a first conductive feature disposed over a first source/drain feature, and the first conductive feature has a first width. The semiconductor structure further includes a second semiconductor device formed in a second device region of the substrate. The second semiconductor device includes a second gate structure comprising a second spacer layer, wherein the second spacer layer has a second thickness different than the first thickness. The second semiconductor device also includes a second conductive feature disposed over a second source/drain feature, and the second conductive feature has a second width different than the first width.

A monolithic 3D complementary field-effect transistor (FET) (CFET) circuit includes a first CFET structure and a second CFET structure in a logic circuit within a device layer. A first interconnect layer disposed on the device layer provides first and second input contacts and an output contact of a logic circuit. Each CFET structure includes an upper FET having a first type (e.g., P-type or N-type) on a lower FET having a second type (e.g., N-type or P-type). The FETs in the monolithic 3D CFET circuit may be interconnected to form a two-input NOR circuit or a two-input NAND circuit. Vertical access interconnects (vias) may be formed within the device layer to interconnect the FETs externally and to each other. The FETs may be formed as bulk-type transistors or SOI transistors.

A semiconductor device may include a substrate, a lower power line in a lower portion of the substrate, metal layers on the substrate, and a protection structure that is electrically connected to the lower power line and the metal layers. The protection structure may include a doping pattern in the substrate, and a first source/drain pattern that is on the substrate and is electrically connected to an upper portion of the doping pattern. The doping pattern and the first source/drain pattern may include different dopants from each other.

A high voltage field effect transistor includes a thick silicon oxide gate dielectric and polysilicon gate electrode, while a low voltage field effect transistor includes a high dielectric constant metal oxide gate dielectric and a metallic gate electrode.