A semiconductor structure includes a first device and a second device. The first device includes: a first gate structure formed over an active region and a first air spacer disposed adjacent to the first gate structure. The second device includes: a second gate structure formed over an isolation structure and a second air spacer disposed adjacent to the second gate structure. The first air spacer and the second air spacer have different sizes.

A semiconductor device and a method of forming the same are provided. The method includes forming a sacrificial gate structure over an active region. A first spacer layer is formed along sidewalls and a top surface of the sacrificial gate structure. A first protection layer is formed over the first spacer layer. A second spacer layer is formed over the first protection layer. A third spacer layer is formed over the second spacer layer. The sacrificial gate structure is replaced with a replacement gate structure. The second spacer layer is removed to form an air gap between the first protection layer and the third spacer layer.

A semiconductor device and a method of forming the same are provided. The method includes forming a sacrificial gate structure over an active region. A first spacer layer is formed along sidewalls and a top surface of the sacrificial gate structure. A first protection layer is formed over the first spacer layer. A second spacer layer is formed over the first protection layer. A third spacer layer is formed over the second spacer layer. The sacrificial gate structure is replaced with a replacement gate structure. The second spacer layer is removed to form an air gap between the first protection layer and the third spacer layer.

A semiconductor device includes bit line structures disposed on a substrate, each bit line structure comprising a bit line and an insulating spacer structure, buried contacts which fill lower portions of spaces between bit line structures in the substrate, and landing pads which fill upper portions of the spaces, extend from upper surfaces of the buried contacts to upper surfaces of the bit line structures, and are spaced apart from each other by insulating structures. A first insulating structure is disposed between a first landing pad and a first bit line structure. The first insulating structure includes a sidewall extending along a sidewall of the first landing pad toward the substrate. In a direction extending toward the substrate, the sidewall of the first insulating structure gets closer to a first sidewall of the first bit line structure.

A semiconductor device includes bit line structures disposed on a substrate, each bit line structure comprising a bit line and an insulating spacer structure, buried contacts which fill lower portions of spaces between bit line structures in the substrate, and landing pads which fill upper portions of the spaces, extend from upper surfaces of the buried contacts to upper surfaces of the bit line structures, and are spaced apart from each other by insulating structures. A first insulating structure is disposed between a first landing pad and a first bit line structure. The first insulating structure includes a sidewall extending along a sidewall of the first landing pad toward the substrate. In a direction extending toward the substrate, the sidewall of the first insulating structure gets closer to a first sidewall of the first bit line structure.

An N-type metal oxide semiconductor (NMOS) transistor includes a first gate and a first spacer structure disposed on a first sidewall of the first gate in a first direction. The first spacer structure has a first thickness in the first direction and measured from an outermost point of an outer surface of the first spacer structure to the first sidewall. A P-type metal oxide semiconductor (PMOS) transistor includes a second gate and a second spacer structure disposed on a second sidewall of the second gate in the first direction and measured from an outermost point of an outer surface of the second spacer structure to the second sidewall. The second spacer structure has a second thickness that is greater than the first thickness. The NMOS transistor is a pass-gate of a static random access memory (SRAM) cell, and the PMOS transistor is a pull-up of the SRAM cell.

A semiconductor device is provided. The semiconductor device includes a fin protruding from a semiconductor substrate and a gate structure formed across the fin. The semiconductor device also includes a gate spacer formed over a sidewall of the gate structure. The gate spacer includes a sidewall spacer and a sealing spacer formed above the sidewall spacer. In addition, an air gap is vertically sandwiched between the sidewall spacer and the sealing spacer. The semiconductor device further includes a hard mask formed over the gate structure and covering a sidewall of the sealing spacer.

A semiconductor device is provided. The semiconductor device includes a fin protruding from a semiconductor substrate and a gate structure formed across the fin. The semiconductor device also includes a gate spacer formed over a sidewall of the gate structure. The gate spacer includes a sidewall spacer and a sealing spacer formed above the sidewall spacer. In addition, an air gap is vertically sandwiched between the sidewall spacer and the sealing spacer. The semiconductor device further includes a hard mask formed over the gate structure and covering a sidewall of the sealing spacer.

The embodiments described herein are directed to a method for mitigating the fringing capacitances generated by patterned gate structures. The method includes forming a gate structure on fin structures disposed on a substrate; forming an opening in the gate structure to divide the gate structure into a first section and a second section, where the first and second sections are spaced apart by the opening. The method also includes forming a fill structure in the opening, where forming the fill structure includes depositing a silicon nitride liner in the opening to cover sidewall surfaces of the opening and depositing silicon oxide on the silicon nitride liner.

The embodiments described herein are directed to a method for mitigating the fringing capacitances generated by patterned gate structures. The method includes forming a gate structure on fin structures disposed on a substrate; forming an opening in the gate structure to divide the gate structure into a first section and a second section, where the first and second sections are spaced apart by the opening. The method also includes forming a fill structure in the opening, where forming the fill structure includes depositing a silicon nitride liner in the opening to cover sidewall surfaces of the opening and depositing silicon oxide on the silicon nitride liner.