Fully aligned via for interconnect
A fully aligned via interconnect structure and techniques for formation thereof using subtractive metal patterning are provided. In one aspect, an interconnect structure includes: metal lines Mx−1; metal lines Mx disposed over the metal lines Mx−1; and at least one via Vx−1 fully aligned between the metal lines Mx−1 and the metal lines Mx, wherein a top surface of at least one of the metal lines Mx−1 has a stepped profile. In another aspect, another interconnect structure includes: metal lines Mx−1; metal lines Mx disposed over the metal lines Mx−1; at least one via Vx−1 fully aligned between the metal lines Mx−1 and the metal lines Mx; and sidewall spacers alongside the metal lines Mx. A method of forming an interconnect structure is also provided.
1. An interconnect structure, comprising:
metal lines Mx−1;
metal lines Mx disposed over the metal lines Mx−1; and
at least one via Vx−1 fully aligned between the metal lines Mx−1 and the metal lines Mx, wherein a top surface of at least one of the metal lines Mx−1 has a stepped profile.
2. The interconnect structure of claim 1 , wherein the metal lines Mx are oriented perpendicular to the metal lines Mx−1.
3. The interconnect structure of claim 1 , wherein the stepped profile comprises a first region of the top surface of the at least one metal line Mx−1 at a base of the at least one via Vx−1 that is above a second region of the top surface of the at least one metal line Mx−1 away from the at least one via Vx−1.
4. The interconnect structure of claim 1 , wherein the stepped profile comprises a first region of the top surface of the at least one metal line Mx−1 at a base of the at least one via Vx−1 that is below a second region of the top surface of the at least one metal line Mx−1 away from the at least one via Vx−1.
5. The interconnect structure of claim 1 , wherein the metal lines Mx−1, the metal lines Mx, and the at least one via Vx−1 each has a tapered, downward sloping sidewall.
6. The interconnect structure of claim 1 , wherein the metal lines Mx−1, the metal lines Mx, and the at least one via Vx−1 each comprises a metal selected from the group consisting of: cobalt (Co), ruthenium (Ru), molybdenum (Mo), tungsten (W) and combinations thereof.
7. An interconnect structure, comprising:
metal lines Mx−1;
metal lines Mx disposed over the metal lines Mx−1;
at least one via Vx−1 fully aligned between the metal lines Mx−1 and the metal lines Mx; and
sidewall spacers alongside the metal lines Mx but absent along the at least one via Vx−1.
8. The interconnect structure of claim 7 , wherein the sidewall spacers comprise a material selected from the group consisting of: silicon oxide (SiOx), silicon nitride (SiN), silicon oxynitride (SiON), silicon carbide nitride (SiCN) and combinations thereof.
9. The interconnect structure of claim 7 , further comprising:
pockets in the at least one via Vx−1 and the metal lines Mx below the sidewall spacers; and
a metal film disposed in the pockets and along a sidewall of the at least one via Vx−1.
10. The interconnect structure of claim 9 , wherein the metal film contains a different metal from at least one of the metal lines Mx−1, the metal lines Mx, and the at least one via Vx−1.
11. The interconnect structure of claim 9 , wherein the metal film is disposed on a top surface of at least one of the metal lines Mx−1.
12. The interconnect structure of claim 7 , wherein the metal lines Mx are oriented perpendicular to the metal lines Mx−1.
13. The interconnect structure of claim 7 , wherein the metal lines Mx−1, the metal lines Mx, and the at least one via Vx−1 each has a tapered, downward sloping sidewall.
14. The interconnect structure of claim 7 , wherein the metal lines Mx−1, the metal lines Mx, and the at least one via Vx−1 each comprises a metal selected from the group consisting of: Co, Ru, Mo, W and combinations thereof.