Methods of forming tight pitch stack nanowire isolation
Methods for forming a tight pitch stack nanowire without shallow trench isolation including a base nanosheet formed on a substrate. At least one fin are formed, and at least one dummy gate is formed over the at least two fins, on the base nanosheet, the at least two fins including at least two alternating layers of a first material and a second material. The base nanoset is replaced with a blanket dielectric to form a shallow trench isolation (STI) around the at least one fin and around the at least one dummy gate. A gate replacement is performed to replace the at least one dummy gate and the second material with a gate conductor material and a gate cap to form gate structure.
1. A method for forming a stacked nanowire transistor, comprising:
forming at least one fin, and at least one dummy gate over the at least one fin, on a base nanosheet, the fin having a first material and a second material;
replacing the base nanosheet with a blanket dielectric to form a shallow trench isolation (STI) around the at least one fin and around the at least one dummy gate and having a substantially uniform thickness over a substrate; and
performing a gate replacement to replace the at least one dummy gate and the second material with a gate conductor material and a gate cap to form gate structures.
2. The method of claim 1 , wherein the base nanosheet is replaced with the blanket dielectric, including:
etching the base nanosheet selective to each of the first material and the second material, such that the base nanosheet is removed and a cavity is formed beneath the at least one fin; and
depositing a dielectric material beneath the cavity.
3. The method of claim 2 , further including:
planarizing the dielectric material; and
recessing the dielectric material down to an STI level, such that the dielectric material forms the blanket dielectric that isolates each of the at least one fin.
4. The method of claim 1 , wherein forming the at least one fin includes at least two alternating layers of the first material and the second material.
5. The method of claim 4 , wherein the base nanosheet includes a material that is different from each of the first material and the second material.
6. The method of claim 4 , wherein the base nanosheet and the second material include different amounts of Ge.
7. The method of claim 1 , wherein the base nanosheet defines an active area within which the at least one fin and the at least one dummy gate are formed.
8. The method of claim 7 , wherein a top surface of the substrate outside of the active area is recessed below a top surface of the substrate within the active area.
9. The method of claim 7 , wherein the blanket dielectric replaces the base nanosheet in the entire active area.
10. The method of claim 7 , wherein a top surface of the substrate outside of the active region is at a height that is less than a height of a bottom surface of the blanket.
11. The method of claim 1 , wherein the gate structures are formed on top of the blanket dielectric such that each gate structure is isolated from the substrate and from each other gate structure by the blanket dielectric.
12. A method for forming a stacked nanowire transistor, comprising:
forming at least two fins, and at least one dummy gate over the at least two fins, on a base nanosheet, each of the at least two fins having a first material and a second material;
etching the base nanosheet from beneath the at least two fins and the at least one dummy gate to form a cavity beneath the at least two fins and the at least one dummy gate;
filling the cavity with a blanket dielectric to form a shallow trench isolation (STI) beneath and between each of the at least two fins and beneath and around the at least one dummy gate and having a substantially uniform thickness over a substrate; and
performing a gate replacement to replace the at least one dummy gate and the second material with a gate conductor material and a gate cap for form gate structures.
13. The method of claim 12 , further including:
planarizing the blanket dielectric; and
recessing the blanket dielectric down to an STI level below the at least two fins, such that the blanket dielectric isolates each of the at least two fins.
14. The method of claim 12 , wherein forming the at least two fins includes at least two alternating layers of the first material and the second material.
15. The method of claim 14 , wherein the base nanosheet includes is formed from a material that is different from each of the first material and the second material.
16. The method of claim 14 , wherein the base nanosheet and the second material include different amounts of Ge.
17. The method of claim 12 , wherein the base nanosheet defines an active area within which the at least two fins and the at least one dummy gate are formed.
18. The method of claim 17 , wherein the blanket dielectric replaces the base nanosheet in the entire active area.
19. The method of claim 18 , wherein the gate structures are formed on top of the blanket dielectric such that each gate structure is isolated from the substrate and from each other gate structure by the blanket dielectric.