Selective surface modification of interconnect structures
Semiconductor structures including copper interconnect structures and methods include selective surface modification of copper by providing a Cu x Ti y N z alloy in the surface. The methods generally include forming a titanium nitride layer on an exposed copper surface followed by annealing to form the Cu x Ti y N z , alloy in the exposed copper surface. Subsequently, the titanium layer is removed by a selective wet etching.
1. A semiconductor structure comprising:
at least one copper interconnect structure filled with copper in an interlayer dielectric, the at least one copper interconnect structure comprising a Cu x Ti y N z alloy in a top surface of the copper, wherein 0<x<1, 0<y<1, and 0≤z<1, wherein the Cu x Ti y N z alloy in the top surface is free of TiN thereon.
2. The semiconductor structure of claim 1 , wherein the at least one copper interconnect structure further comprises a liner layer on surfaces between the at least one copper interconnect structure and the interlayer dielectric.
3. The semiconductor structure of claim 1 further comprising a liner layer intermediate the copper and the interlayer dielectric formed of a material comprising tantalum, titanium, tantalum nitride or titanium nitride.
4. The semiconductor structure of claim 1 , wherein the top surface of the copper is coplanar to a top surface of the interlay dielectric.
5. The semiconductor structure of claim 1 , wherein the copper includes an alloying element comprising C, N, O, or Cl.
6. The semiconductor structure of claim 1 , wherein the copper further comprises an amount of an alloying element is in the range of about 0.001 weight percent (wt. %) to about 10 wt % of the copper.
7. The semiconductor structure of claim 1 , wherein the interlayer dielectric comprises silicon dioxide, silicon nitride, or a doped glass layer, such as phosphorus silicate glass, or boron silicate glass.
8. The semiconductor structure of claim 3 , wherein the liner layer comprises tantalum, tantalum, nitride, cobalt, ruthenium, titanium nitride, or combinations thereof.
9. The semiconductor structure of claim 2 , further comprising a seed layer on the liner layer, the seed layer comprising one or more metals.
10. The semiconductor structure of claim 9 , wherein the seed layer comprising the one or more metals is from 1 atomic percent to 10 atomic percent.
11. The semiconductor structure of claim 9 , wherein the seed layer comprises copper or copper manganese.
12. The semiconductor structure of claim 9 , wherein the seed layer comprising the one or more metals is from 1 atomic percent to 7 atomic percent.
13. The semiconductor structure of claim 5 , wherein the alloying element is from 0.001 weight percent to 10 weight percent.