Abstract: In an embodiment, a device includes: a first fin extending from a substrate; a gate stack disposed on the first fin; a source/drain region disposed in the first fin; a contact etch stop layer (CESL) disposed over the source/drain region; a gate spacer extending along a side of the gate stack; and a dielectric plug disposed between the CESL and the gate spacer, where the dielectric plug, the CESL, the gate spacer, and the source/drain region collectively define a void physically separating the gate stack from the source/drain region.

Abstract: A method of forming a semiconductor device includes: forming a fin protruding above a substrate, where a top portion of the fin comprises a layer stack that includes alternating layers of a first semiconductor material and a second semiconductor material; forming a dummy gate structure over the fin; forming openings in the fin on opposing sides of the dummy gate structure; forming source/drain regions in the openings; removing the dummy gate structure to expose the first semiconductor material and the second semiconductor material under the dummy gate structure; performing a first etching process to selectively remove the exposed first semiconductor material, where after the first etching process, the exposed second semiconductor material form nanostructures, where each of the nanostructures has a first shape; and after the first etching process, performing a second etching process to reshape each of the nanostructures into a second shape different from the first shape.

Abstract: A method includes forming an opening in a first dielectric layer. A region underlying the first dielectric layer is exposed to the opening. The method further includes depositing a dummy silicon layer extending into the opening, and depositing an isolation layer. The isolation layer and the dummy layer include a dummy silicon ring and an isolation ring, respectively, in the opening. The opening is filled with a metallic region, and the metal region is encircled by the isolation ring. The dummy silicon layer is etched to form an air spacer. A second dielectric layer is formed to seal the air spacer.

Abstract: In an embodiment, a device includes: a first fin extending from a substrate; a gate stack disposed on the first fin; a source/drain region disposed in the first fin; a contact etch stop layer (CESL) disposed over the source/drain region; a gate spacer extending along a side of the gate stack; and a dielectric plug disposed between the CESL and the gate spacer, where the dielectric plug, the CESL, the gate spacer, and the source/drain region collectively define a void physically separating the gate stack from the source/drain region.