METHODS AND APPARATUSES FOR ATOMIC LAYER CLEANING OF CONTACTS AND VIAS

• US 20150037972A1
• Filed: 07/29/2014
• Published: 02/05/2015
• Est. Priority Date: 07/30/2013
• Status: Active Grant

• Current Assignee: Lam Research Corporation
• Original Assignee: Lam Research Corporation
• Inventors: Danek, Michal, Gao, Juwen, Fellis, Aaron, Lai, Chiukin Steven, Juarez, Francisco
• Granted Patent: US 9,362,163 B2
• Time in Patent Office: Days
• US Class Current: 438/643
• CPC Class Codes: C23G 5/00 Cleaning or de-greasing metallic material by other methods; Apparatus for cleaning or de-greasing metallic material with organic solvents
• CPC Class Codes: H01L 21/02063 the processing being the formation of vias or contact holes
• CPC Class Codes: H01L 21/76814 post-treatment or after-treatment, e.g. cleaning or removal of oxides on underlying conductors
• CPC Class Codes: H01L 21/76841 Barrier, adhesion or liner layers

Abstract

Described are cleaning methods for removing contaminants from an electrical contact interface of a partially fabricated semiconductor substrate. The methods may include introducing a halogen-containing species into a processing chamber, and forming an adsorption-limited layer, which includes halogen from the halogen-containing species, atop the electrical contact interface and/or the contaminants thereon. The methods may further include thereafter removing un-adsorbed halogen-containing species from the processing chamber and activating a reaction between the halogen of the adsorption-limited layer and the contaminants present on the electrical contact interface. The reaction may then result in the removal of at least a portion of the contaminants from the electrical contact interface. In some embodiments, the halogen adsorbed onto the surface and reacted may be fluorine. Also described herein are apparatuses having controllers for implementing such electrical contact interface cleaning techniques.

Claims

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 fluorine-containing species into the processing chamber;

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

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

(d) activating a reaction between the fluorine 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.

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

10. The method of claim 1, further comprising:

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

13. The method of claim 3, 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.

14. The method of claim 1, wherein the fluorine-containing species introduced in (a) is XeF₂, BrF₃, IF₅, or ClF₃.

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

21. The method of claim 20, wherein the electrical contact interface comprises SiGe.

22. The method of claim 20, wherein the electrical contact interface comprises Si and further comprises a metal silicide layer atop at least some portion of the underlying Si.

23. The method of claim 22, wherein the metal silicide layer comprises Ni silicide, Ti silicide, and/or Co silicide.

24. The method of claim 20, wherein the electrical contact interface comprises Ge and further comprises a metal germanide layer atop at least some portion of the underlying Ge.

25. The method of claim 24, wherein the metal germanide layer comprises Ti germanide, Ni gemanide, and/or Co germanide.

8. (canceled)

9. (canceled)

11. (canceled)

12. (canceled)

15. (canceled)

16. (canceled)

17. (canceled)

18. (canceled)

19. (canceled)

26. (canceled)

27. A method of forming a metallization layer in electrical contact with an electrical contact interface of a partially fabricated semiconductor substrate in a processing chamber, the method comprising:

removing contaminants from the electrical contact interface according to a cleaning 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 the 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 comprises one or more fluorocarbon polymer species deposited in a prior fabrication operation involving a reactive ion etch of the partially-manufactured semiconductor substrate; and

depositing the metallization layer, the metallization layer comprising a metal in electrical contact with the electrical contact interface;

wherein the removal of contaminants and deposition of the metallization layer are performed in the same processing chamber without an intervening vacuum break.

29. The method of claim 27, wherein the metal is tungsten, and wherein depositing the metallization layer comprises:

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

(ii) introducing molecular hydrogen into the processing chamber; and

(iii) reacting the tungsten-containing species with the molecular hydrogen to deposit tungsten atop the electrical contact interface.

30. The method of claim 29, further comprising:

depositing a barrier layer after removing contaminants from the electrical contact interface but before depositing the metallization layer;

wherein the barrier layer comprises elemental titanium, titanium nitride, and/or fluorine-free tungsten.

28. (canceled)

31. (canceled)

32. (canceled)

33. An apparatus for forming a metallization layer in electrical contact with an electrical contact interface of a partially fabricated semiconductor substrate, the apparatus comprising:

a processing chamber;

a substrate holder within the processing chamber;

one or more gas inlets for introducing chemical species into the processing chamber;

an exhaust system for evacuating chemical species from the processing chamber; and

a controller having machine-readable instructions which it is configured to execute including instructions for;

(a) operating the one or more gas inlets to introduce a fluorine-containing species into the processing chamber;

(b) maintaining conditions within the processing chamber such that an adsorption-limited layer forms atop the electrical contact interface and/or contaminants thereon, the adsorption-limited layer comprising fluorine from the fluorine-containing species;

(c) operating the exhaust system to remove un-adsorbed fluorine-containing species from the processing chamber;

(d) activating a reaction between the fluorine 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;

(e) operating the one or more gas inlets to introduce a metal-containing species into the processing chamber; and

(f) maintaining conditions within the processing chamber such that metal comprising the metal-containing species is deposited onto the electrical contact interface forming the metallization layer.

35. The apparatus of claim 33, wherein the instructions of the controller further provide that instructions (a)-(f) be executed without an intervening vacuum break.

34. (canceled)