A semiconductor structure includes a stacked device structure having a first field-effect transistor having a first source/drain region, and a second field-effect transistor vertically stacked above the first field-effect transistor, the second field-effect transistor having a second source/drain region and a gate region having first sidewall spacers. The stacked device structure further includes a frontside source/drain contact disposed on a first portion of a sidewall and a top surface of the second source/drain region, a first metal via connected to the frontside source/drain contact and to a first backside power line, and second sidewall spacers disposed on a first portion of the first metal via. The first sidewall spacers comprise a first dielectric material and the second sidewall spacers comprise a second dielectric material different than the first dielectric material.

A method includes forming a lower transistor in a lower wafer, wherein the lower transistor includes a lower source/drain region, forming a contact plug electrically connecting to the lower source/drain region, and forming a metal line over the lower transistor. A first portion of the metal line is vertically aligned to the lower source/drain region. The method further includes bonding an upper wafer to the lower wafer, and forming an upper transistor in the upper wafer. The upper transistor includes an upper source/drain region, and is vertically aligned to a second portion of the metal line. A first interconnect structure is formed on the lower wafer and electrically connecting to the lower transistor. A second interconnect structure is formed on the upper wafer and electrically connecting to the upper transistor.

A method includes forming a fin structure including a first channel layer, a sacrificial layer, and a second channel layer over a substrate; forming a dummy gate structure across the fin structure; recessing the fin structure; epitaxially growing first source/drain epitaxial structures on opposite sides of the first channel layer; forming first dielectric layers to cover the first source/drain epitaxial structures, respectively; epitaxially growing second source/drain epitaxial structures on opposite sides of the second channel layer; removing the dummy gate structure and the sacrificial layer to form a gate trench between the first source/drain epitaxial structures and between the second source/drain epitaxial structures; and forming a metal gate structure in the gate trench. The second source/drain epitaxial structures are over the first dielectric layers, respectively.

An IC device includes a first and second stacked transistor structures including respective first and second and third and fourth transistors in a semiconductor substrate, first and second bit lines and a word line on one of a front or back side of the semiconductor substrate, and a power supply line on the other of the front or back side. The first transistor includes a source/drain (S/D) terminal electrically connected to the first bit line, a S/D terminal electrically connected to a S/D terminal of the second transistor, and a gate electrically connected to the word line, the third transistor includes a S/D terminal electrically connected to the second bit line, a S/D terminal electrically connected to a S/D terminal of the fourth transistor, and a gate electrically connected to the word line, and the second and fourth transistors include S/D terminals electrically connected to the power supply line.

A semiconductor structure is provided that includes a first stacked FET cell including a second FET stacked over a first FET, and a second stacked FET cell located adjacent to the first stacked FET cell and including a fourth FET stacked over a third FET. The structure further includes a first backside source/drain contact structure located beneath the first stacked FET cell and contacting a source/drain region of the first FET, a second backside source/drain contact structure located beneath the second stacked FET cell and contacting a source/drain region of the third FET, and an angled cut region laterally separating the first backside source/drain contact structure from the second backside source/drain contact structure.

Structures and formation methods of a semiconductor device structure are provided. The semiconductor device structure includes a plurality of nanostructures over a substrate, and a gate electrode surrounding the nanostructures. The semiconductor device structure includes a source/drain portion adjacent to the gate electrode, and a semiconductor layer between the gate electrode and the source/drain portion.

A semiconductor device including: a first silicon level including a first single crystal silicon layer and a plurality of first transistors; a first metal layer disposed over the first silicon level; a second metal layer disposed over the first metal layer; a third metal layer disposed over the second metal layer; a second level including a plurality of second transistors, disposed over the third metal layer; a third level including a plurality of third transistors, disposed over the second level; a via disposed through the second and third levels; a fourth metal layer disposed over the third level; a fifth metal layer disposed over the fourth metal layer; and a fourth level including a second single crystal silicon layer and is disposed over the fifth metal layer, where each of the plurality of second transistors includes a metal gate, and the via has a diameter of less than 450 nm.

A transistor includes a gate structure with reduced gate region or eliminated gate region located between a top MDI region and a bottom MDI region. The reduced gate region has a reduction of conductive material therewithin and may be formed due to the presence of prefabricated wide inner spacers between the top MDI region and the bottom MDI region. The no gate region has an absence of conductive material therewithin and may be formed due to the presence of a prefabricated inner spacer that is between, and has a coplanar perimeter with, the top MDI region and the bottom MDI region. By reducing or eliminating the conductive material of the gate structure between the dual MDI structure, parasitic capacitance otherwise associated therewith is reduced.

A method includes forming a first semiconductor channel region and a second semiconductor channel region, with the second semiconductor channel region overlapping the first semiconductor channel region, forming a first gate dielectric on the first semiconductor channel region, and forming a second gate dielectric on the second semiconductor channel region. A dipole dopant is incorporated into a first one of the first gate dielectric and the second gate dielectric to a higher atomic percentage, and a second one of the first gate dielectric and the second gate dielectric has a lower atomic percentage of the dipole dopant. A gate electrode is formed on both of the first gate dielectric and the second gate dielectric. The gate electrode and the first gate dielectric form parts of a first transistor, and the gate electrode and the second gate dielectric form parts of a second transistor.

A method of microfabrication includes epitaxially growing a first vertical channel structure of silicon-containing material on a first sacrificial layer of silicon containing material, the first sacrificial layer having etch selectivity with respect to the vertical channel structure. A core opening is directionally etched through the vertical channel structure to expose the first sacrificial layer, and the first sacrificial layer is isotropically etched through the core opening to form a first isolation opening for isolating the first vertical channel structure.