Transition metal dry etch by atomic layer removal of oxide layers for device fabrication

1. A method of etching a film, the method comprising:

reacting a surface layer of a transition metal species of a transition metal-containing film with a molecular oxidant species, wherein reacting the surface layer of the transition metal species of the transition metal-containing film with the molecular oxidant species comprises transferring oxygen from molecules having a reactive nitrogen based organic skeleton;

removing volatile fragments of the reacted molecular oxidant species to provide an oxidized surface layer of the transition metal species;

reacting the oxidized surface layer of the transition metal species with a molecular etchant; and

removing the reacted oxidized surface layer of the transition metal species and the reacted molecular etchant by volatlilization.

2. The method of claim 1 , further comprising:

reacting a second surface layer of the transition metal species of the transition metal-containing film with the molecular oxidant species;

removing volatile fragments of the reacted molecular oxidant species to provide a second oxidized surface layer of the transition metal species;

reacting the second oxidized surface layer of the transition metal species with the molecular etchant; and

removing the reacted oxidized surface layer of the transition metal species and the reacted molecular etchant by volatlilization.

3. The method of claim 2 , wherein the reacting, removing, reacting and removing is repeated until a target thickness of the transition metal-containing film is etched away.

4. The method of claim 1 , wherein reacting the surface layer of the transition metal species of the transition metal-containing film comprises reacting a surface layer of a transition metal species selected from the group consisting of cobalt, iron, nickel, platinum and ruthenium.

5. The method of claim 1 , wherein reacting the oxidized surface layer of the transition metal species with the molecular etchant comprises reacting with hexafluoroacetylacetone.

6. The method of claim 1 , wherein removing the reacted oxidized surface layer of the transition metal species and the reacted molecular etchant by volatlilization comprises removing a transition metal complex comprising a transition metal center chelated by two bidentate ligands and removing H 2 O.

7. A method of fabricating a semiconductor structure, the method comprising:

forming a trench in an inter-layer dielectric (ILD) layer;

forming a transition metal-containing film in the trench; and

recessing the transition metal-containing film within the trench, the recessing comprising:

reacting a surface layer of a transition metal species of the transition metal-containing film with a molecular oxidant species, wherein reacting the surface layer of the transition metal species of the transition metal-containing film with the molecular oxidant species comprises transferring oxygen from molecules having a reactive nitrogen based organic skeleton;

removing volatile fragments of the reacted molecular oxidant species to provide an oxidized surface layer of the transition metal species;

reacting the oxidized surface layer of the transition metal species with a molecular etchant; and

removing the reacted oxidized surface layer of the transition metal species and the reacted molecular etchant by volatlilization.

8. The method of claim 7 , further comprising:

forming a dielectric capping layer on the recessed transition metal-containing film.

9. The method of claim 7 , wherein the semiconductor structure is a conductive via or metal line of a back end metallization structure.

10. The method of claim 7 , wherein the semiconductor structure is a metal gate electrode.

11. The method of claim 7 , further comprising:

reacting a second surface layer of the transition metal species of the transition metal-containing film with the molecular oxidant species;

removing volatile fragments of the reacted molecular oxidant species to provide a second oxidized surface layer of the transition metal species;

reacting the second oxidized surface layer of the transition metal species with the molecular etchant; and

removing the reacted oxidized surface layer of the transition metal species and the reacted molecular etchant by volatlilization.

12. The method of claim 11 , wherein the reacting, removing, reacting and removing is repeated until a target thickness of the transition metal-containing film is etched away.

13. The method of claim 7 , wherein reacting the surface layer of the transition metal species of the transition metal-containing film comprises reacting a surface layer of a transition metal species selected from the group consisting of cobalt, iron, nickel, platinum and ruthenium.

14. The method of claim 7 , wherein reacting the oxidized surface layer of the transition metal species with the molecular etchant comprises reacting with hexafluoroacetylacetone.

15. The method of claim 7 , wherein removing the reacted oxidized surface layer of the transition metal species and the reacted molecular etchant by volatlilization comprises removing a transition metal complex comprising a transition metal center chelated by two bidentate ligands and removing H 2 O.

16. A method of etching a film stack, the method comprising:

forming a patterned mask on a transition metal-containing film stack to provide masked regions and exposed regions of the transition metal-containing film stack; and

etching the transition metal-containing film stack by removing the exposed regions of the transition metal-containing film stack, the etching comprising:

reacting a surface layer of a transition metal species of the transition metal-containing film stack with a molecular oxidant species, wherein reacting the surface layer of the transition metal species of the transition metal-containing film stack with the molecular oxidant species comprises transferring oxygen from molecules having a reactive nitrogen based organic skeleton;

removing volatile fragments of the reacted molecular oxidant species to provide an oxidized surface layer of the transition metal species;

reacting the oxidized surface layer of the transition metal species with a molecular etchant; and

removing the reacted oxidized surface layer of the transition metal species and the reacted molecular etchant by volatlilization.

17. The method of claim 16 , further comprising:

reacting a second surface layer of the transition metal species of the transition metal-containing film stack with the molecular oxidant species;

removing volatile fragments of the reacted molecular oxidant species to provide a second oxidized surface layer of the transition metal species;

reacting the second oxidized surface layer of the transition metal species with the molecular etchant; and

removing the reacted oxidized surface layer of the transition metal species and the reacted molecular etchant by volatlilization.

18. The method of claim 17 , wherein the reacting, removing, reacting and removing is repeated until a target thickness of the transition metal-containing film stack is etched away.

19. The method of claim 16 , wherein reacting the surface layer of the transition metal species of the transition metal-containing film stack comprises reacting a surface layer of a transition metal species selected from the group consisting of cobalt, iron, nickel, platinum and ruthenium.

20. The method of claim 16 , wherein reacting the oxidized surface layer of the transition metal species with the molecular etchant comprises reacting with hexafluoroacetylacetone.

21. The method of claim 16 , wherein removing the reacted oxidized surface layer of the transition metal species and the reacted molecular etchant by volatlilization comprises removing a transition metal complex comprising a transition metal center chelated by two bidentate ligands and removing H 2 O.