A semiconductor structure and a method for fabricating the same are provided. The semiconductor structure includes a substrate, a source region, a drain region and a gate structure. The source region is located in the substrate. The drain region is located in the substrate. The gate structure is disposed on the substrate and located between the source region and the drain region, and includes a first sub-gate structure and a second sub-gate structure. The first sub-gate structure is adjacent to the source region and includes a first sub-gate insulating layer. The second sub-gate structure is adjacent to the drain region and includes a second sub-gate insulating layer. The second sub-gate insulating layer and the first sub-gate insulating layer are separated from each other. The first sub-gate insulating layer has a first thickness, and the second sub-gate insulating layer has a second thickness greater than the first thickness.

The present disclosure relates to semiconductor devices and their fabrication methods. An example semiconductor device comprises a substrate including an active pattern, a channel pattern including semiconductor patterns, a source/drain pattern connected to the semiconductor patterns, an inner gate electrode between two neighboring semiconductor patterns, an inner gate dielectric layer, and an inner high-k dielectric layer between the inner gate electrode and the inner gate dielectric layer. The inner gate dielectric layer includes an upper dielectric layer, a lower dielectric layer, and an inner spacer. A first thickness of the inner spacer is greater than a second thickness of the upper or lower dielectric layer. The first thickness is greater than a third thickness of the inner high-k dielectric layer.

A transistor whose channel region includes an oxide semiconductor is used as a pull down transistor. The band gap of the oxide semiconductor is 2.0 eV or more, preferably 2.5 eV or more, more preferably 3.0 eV or more. Thus, hot carrier degradation in the transistor can be suppressed. Accordingly, the circuit size of the semiconductor device including the pull down transistor can be made small. Further, a gate of a pull up transistor is made to be in a floating state by switching of on/off of the transistor whose channel region includes an oxide semiconductor. Note that when the oxide semiconductor is highly purified, the off-state current of the transistor can be 1 aA/m (110.sup.18 A/m) or less. Therefore, the drive capability of the semiconductor device can be improved.

A method of generating a layout design of an integrated circuit includes forming an active zone and partitioning the active zone into a center portion between a first side portion and a second side portion. The method also includes forming a plurality of gate-strips and forming a routing line. The plurality of gate-strips includes a first group of gate-strips intersecting the active zone over first channel regions in the center portion, a second group of gate-strips intersecting the active zone over second channel regions in the center portion, a third group of gate-strips intersecting the active zone over third channel regions in the first side portion, and a fourth group of gate-strips intersecting the active zone over fourth channel regions in the second side portion.

A semiconductor device includes a first transistor in a first region of a substrate and a second transistor in a second region of the substrate. The first transistor includes multiple first semiconductor patterns; a first gate electrode; a first gate dielectric layer; a first source/drain region; and an inner-insulating spacer. The second transistor includes multiple second semiconductor patterns; a second gate electrode; a second gate dielectric layer; and a second source/drain region. The second gate dielectric layer extends between the second gate electrode and the second source/drain region and is in contact with the second source/drain region. The first source/drain region is not in contact with the first gate dielectric layer.

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 semiconductor device structure and a formation method are provided. The method includes forming a fin structure over a substrate. The fin structure has multiple sacrificial layers and multiple semiconductor layers laid out in an alternating manner. The method also includes partially removing the fin structure to form a recess exposing side surfaces of the semiconductor layers and the sacrificial layers and forming multiple inner spacers covering the side surfaces of the sacrificial layers. The method further includes recessing the semiconductor layers from the side surfaces of the semiconductor layers after the inner spacers are formed and partially removing the inner spacers so that each of the inner spacers becomes thinner. In addition, the method includes forming an epitaxial structure on the side surfaces of the semiconductor layers.

One aspect of the present disclosure pertains to a method of forming a semiconductor structure. The method includes forming an active region over a substrate, forming a dummy gate layer over the active region, forming a hard mask layer over the dummy gate layer, forming a patterned photoresist over the hard mask layer, and performing an etching process to the hard mask layer and the dummy gate layer using the patterned photoresist, thereby forming patterned hard mask structures and patterned dummy gate structures. The patterned hard mask structures are formed with an uneven profile having a protruding portion. The protruding portion of each of the patterned hard mask structures has a first width, wherein each of the patterned dummy gate structures has a second width, and the first width is greater than the second width.

A method of forming a nanosheet FET is provided. A plurality of first and second semiconductor layers are alternately formed on a substrate. The first and second semiconductor layers are patterned into a plurality of stacks of semiconductor layers separate from each other by a space along a direction. Each stack of semiconductor layers has a cross-sectional view along the direction gradually widening towards the substrate. An epitaxial feature is formed in each of the spaces. The patterned second semiconductor layers are then removed from each of the stacks of semiconductor layers.

A method for forming a semiconductor device structure includes forming fin structures over a substrate. The method also includes depositing an isolation material surrounding the fin structures. The method also includes forming a dummy gate structure across the fin structure. The method also includes growing source/drain epitaxial structures over opposite sides of the dummy gate structure. The method also includes removing the dummy gate structure. The method also includes recessing the isolation material after removing the dummy gate structure. The method also includes forming a gate structure over the isolation material.