A method of forming semiconductor memory device includes the following steps. Firstly, a substrate is provided and the substrate includes a cell region. Then, plural bit lines are disposed within the cell region along a first direction, with each of the bit line includes a tri-layered spacer structure disposed at two sides thereof. Next, plural of first plugs are formed within the cell region, with the first plugs being disposed at two sides of each bit lines. Furthermore, plural conductive patterns are formed in alignment with each first plugs. Following theses, a chemical reaction process is performed to modify the material of a middle layer of the tri-layered spacer structure, and a heat treatment process is performed then to remove the modified middle layer, thereto form an air gap layer within the tri-layered spacer structure.

A semiconductor structure includes a substrate, at least one first gate structure, at least one first spacer, at least one source drain structure, and a conductive plug. The first gate structure is present on the substrate. The first spacer is present on at least one sidewall of the first gate structure. The source drain structure is present adjacent to the first spacer. The conductive plug is electrically connected to the source drain structure while leaving a gap between the conductive plug and the spacer.

A semiconductor structure includes a substrate, at least one first gate structure, at least one first spacer, at least one source drain structure, and a conductive plug. The first gate structure is present on the substrate. The first spacer is present on at least one sidewall of the first gate structure. The source drain structure is present adjacent to the first spacer. The conductive plug is electrically connected to the source drain structure while leaving a gap between the conductive plug and the spacer.

A method for forming an SOI substrate includes following operations. A first semiconductor layer, a second semiconductor layer and a third semiconductor layer are formed over a first substrate. A plurality of trenches and a plurality of recesses are formed in the first semiconductor layer, the second semiconductor layer and the third semiconductor layer. The plurality of trenches extend along a first direction, and the plurality of recesses extend along a second direction different from the first direction. The plurality of trenches and the plurality of recesses are sealed to form a plurality of voids. A device layer is formed over the first substrate. The devices layer is bonded to an insulator layer over a second substrate. The third semiconductor layer, the device layer the insulator layer and the second substrate are separated from the first semiconductor layer and the first substrate. The device layer is exposed.

A semiconductor device and a method of fabricating the same are provide. The fabricating method includes providing a silicon-on-insulator (SOI) substrate that includes, from bottom to top, a substrate, a first insulating layer and a semiconductor layer. The semiconductor layer is patterned to form a plurality of dummy patterns. A second insulating layer is formed around the plurality of dummy patterns. The plurality of dummy patterns are removed to form a plurality of openings. A dielectric structure is formed on the substrate and fills into the plurality of openings.

An integrated circuit may be formed by forming a buried isolation layer in an isolation recess in a single-crystal silicon-based substrate. Exposed lateral surfaces of the substrate at the buried isolation layer are covered with a dielectric sidewall. A seed trench is formed through the buried isolation layer to expose the substrate. A single-crystal silicon-based seed layer is formed through the seed trench, extending above the top surface of the buried isolation layer. A silicon-based non-crystalline layer is formed contacting the seed layer. A cap layer is formed over the non-crystalline layer. A radiant-induced recrystallization process converts the non-crystalline layer to a single-crystal layer aligned with the seed layer. The cap layer is removed and the single-crystal layer is planarized, leaving an isolated semiconductor layer over the buried isolation layer.

A method of forming a semiconductor device includes forming a plurality of non-insulator structures on a substrate, the plurality of non-insulator structures being spaced apart by trenches, forming a sacrificial layer overfilling the trenches, reflowing the sacrificial layer at an elevated temperature, wherein a top surface of the sacrificial layer after the reflowing is lower than a top surface of the sacrificial layer before the reflowing, etching back the sacrificial layer to lower the top surface of the sacrificial layer to fall below top surfaces of the plurality of non-insulator structures, forming a dielectric layer on the sacrificial layer, and removing the sacrificial layer to form air gaps below the dielectric layer.

The present disclosure relates to semiconductor structures and, more particularly, to a semiconductor on insulator substrate with cavity structures and methods of manufacture. The structure includes: a bulk substrate with at least one rectilinear cavity structure; an insulator material sealing the at least one rectilinear cavity structure; and a buried insulator layer on the bulk substrate and over the at least one rectilinear cavity structure.

A method includes a patterned hard mask layer formed over a substrate. The substrate is etched using the patterned hard mask layer to form a trench therein but leaving at least one elongated portion of the substrate inside the trench. A first isolation layer is formed over the patterned hard mask layer. The first isolation layer fills the trench and covers the at least one elongated portion of the substrate. A portion of the first isolation layer is removed to expose the at least one elongated portion of the substrate. The at least one elongated portion of the substrate is thereafter removed to form a first opening. A second isolation layer is formed over the first opening, the patterned hard mask layer, and the first isolation layer, the second isolation layer sealing the first opening to form an air gap.

A device includes a semiconductor substrate, a contact plug over the semiconductor substrate, and an Inter-Layer Dielectric (ILD) layer over the semiconductor substrate, with the contact plug being disposed in the ILD. An air gap is sealed by a portion of the ILD and the semiconductor substrate. The air gap forms a full air gap ring encircling a portion of the semiconductor substrate.