Methods and apparatuses for atomic layer cleaning of contacts and vias

1. A cleaning method for removing contaminants from an electrical contact interface of a partially fabricated semiconductor substrate in a processing chamber, the contact interface for making an electrical connection with a metal, the method comprising:

(a) introducing a halogen-containing species into the processing chamber;

(b) forming an adsorption-limited layer atop the electrical contact interface and/or contaminants thereon, the adsorption-limited layer comprising halogen from the halogen-containing species;

(c) after (b), removing un-adsorbed halogen-containing species from the processing chamber; and

(d) activating a reaction between the halogen of the adsorption-limited layer and the contaminants present on the electrical contact interface, the reaction resulting in the removal of at least a portion of the contaminants from the electrical contact interface

wherein the contaminants comprise one or more fluorocarbon polymer species deposited in a prior fabrication operation involving a reactive ion etch of the partially-manufactured semiconductor substrate.

2. The method of claim 1 , wherein activating the reaction in (d) comprises reacting an additional chemical species with the halogen and/or halogen-containing species of the adsorption-limited layer.

3. The method of claim 1 , wherein activating the reaction in (d) comprises providing thermal energy to the adsorption-limited layer.

4. The method of claim 1 , wherein activating the reaction in (d) comprises exposing the adsorption-limited layer to an ion and/or free-radical species of a plasma.

5. The method of claim 4 , wherein activating the reaction in (d) further comprises directing an ion species of the plasma toward the adsorption-limited layer by applying an electromagnetic field to the ion species such that it contacts the adsorption-limited layer.

6. The method of claim 5 , wherein application of the electromagnetic field to the ion species causes it to contact the adsorption-limited layer while having a velocity substantially perpendicular to the plane of the semiconductor substrate.

7. The method of claim 5 , wherein the ion species contacts the adsorption-limited layer by impacting it with a relative kinetic energy of less than 100 eVs.

8. The method of Claim 4 , further comprising:

(f) after (d), reacting metal fluorides and/or metal oxides present on the electrical contact interface with the ion and/or free-radical species present in the plasma, the reaction resulting in the removal of at least a portion of the metal fluorides and/or metal oxides from the electrical contact interface.

9. The method of claim 1 , further comprising:

(e) removing halogen-containing species generated by the reaction in (d) from the processing chamber.

10. The method of claim 1 , wherein the halogen-containing species introduced in (a) is an interhalogen selected from the group consisting of:

XeF 2 , BrF 3 , IF 5 ,and ClF 3 .

11. The method of claim 1 , wherein the electrical contact interface comprises Si, Ge, and/or GaAs.

12. The method of claim 11 , wherein the electrical contact interface comprises SiGe.

13. The method of claim 11 , wherein the electrical contact interface comprises Si and further comprises a metal silicide layer atop at least some portion of the underlying Si.

14. The method of claim 13 , wherein the metal silicide layer comprises Ni silicide, Ti silicide, and/or Co silicide.

15. The method of claim 11 , wherein the electrical contact interface comprises Ge and further comprises a metal germanide layer atop at least some portion of the underlying Ge.

16. The method of claim 15 , wherein the metal germanide layer comprises Ti germanide, Ni gemanide, and/or Co germanide.

17. The method of claim 1 , wherein the halogen is fluorine.