Neutral atom beam nitridation for copper interconnect

• US 9,905,459 B1
• Filed: 09/01/2016
• Issued: 02/27/2018
• Est. Priority Date: 09/01/2016
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Briggs, Benjamin D., Clevenger, Lawrence A., Rizzolo, Michael, Yang, Chih-Chao
• Primary Examiner(s): Geyer, Scott B
• Application Number:
  US15/254,333
• Publication Number:
  US 20180061704A1
• Time in Patent Office: 544 Days
• 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 21/76826 by contacting the layer with gases, liquids or plasmas
• CPC Class Codes: H01L 21/76843 formed in openings in a dielectric
• CPC Class Codes: H01L 21/76846 Layer combinations
• CPC Class Codes: H01L 21/76847 the layer being positioned within the main fill metal
• CPC Class Codes: H01L 21/76856 by treatment in plasmas or gaseous environments, e.g. nitriding a refractory metal liner
• CPC Class Codes: H01L 21/76862 Bombardment with particles, e.g. treatment in noble gas plasmas; UV irradiation
• CPC Class Codes: H01L 21/76867 characterized by methods of formation other than PVD, CVD or deposition from a liquids PVD H01L21/2855; CVD H01L21/28556; deposition from liquids H01L21/288
• CPC Class Codes: H01L 23/53238 Additional layers associated with copper layers, e.g. adhesion, barrier, cladding layers
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Abstract

A method of forming an interconnect that in one embodiment includes forming an opening in a dielectric layer, and treating a dielectric surface of the opening in the dielectric layer with a nitridation treatment to convert the dielectric surface to a nitrided surface. The method may further include depositing a tantalum containing layer on the nitrided surface. In some embodiments, the method further includes depositing a metal fill material on the tantalum containing layer. The interconnect formed may include a nitrided dielectric surface, a tantalum and nitrogen alloyed interface that is present on the nitrided dielectric surface, a tantalum layer on the tantalum and nitrogen alloy interface, and a copper fill.

Claims

1. A method of forming an interconnect comprising:

forming an opening in a dielectric layer;

treating a dielectric surface of the opening in the dielectric layer with a nitridation treatment to convert the dielectric surface to a nitrided surface, wherein the nitridation treatment comprises a neutral atom beam nitridation;

depositing a tantalum containing layer on the nitrided surface; and

depositing metal fill material on the tantalum containing layer.

2. The method of claim 1, wherein the opening in the dielectric layer is formed by photolithography and etching, the opening having sidewall surfaces and a base surface provided by the dielectric layer.

3. The method of claim 1, wherein the dielectric layer is a silicon and carbon containing dielectric.

4. The method of claim 1, wherein the neutral atom beam nitridation comprises;

pressurizing a nitrogen containing gas;

expanding the nitrogen containing gas through a nozzle into a vacuum to create a beam of nitrogen gas clusters, wherein each cluster is comprised weakly bound atoms;

charging the nitrogen gas clusters to accelerate the nitrogen gas clusters;

dissociating the nitrogen gas clusters; and

deflecting a beam of the nitrogen gas clusters following said dissociating to provide a neutral atom beam.

5. The method of claim 4, wherein the nitrogen containing gas is selected from the group consisting of ammonia (NH₃), nitrogen (N₂), Diazene (N₂H₂) and combinations thereof.

6. The method of claim 4, wherein the pressurized nitrogen containing gas is at a pressure ranging from 5 atmospheres to 15 atmospheres.

7. The method of claim 6, wherein the expanding the nitrogen containing gas into said vacuum comprises a vacuum ranging from 1×

10<sup>−

4</sup> atmospheres to 1×

10<sup>−

6</sup> atmospheres.

8. The method of claim 7, wherein following said deflecting the beam of the nitrogen gas clusters to provide the neutral atom beam, the particles are electrically neutral and at an energy ranging from 10 eV to 100 eV.

9. The method of claim 1, wherein nitrogen from the neutral atom beam penetrates a dielectric surface by a dimension less than 5 nm.

10. The method of claim 1, wherein the neutral atom beam causes a carbon depletion in the dielectric, wherein the nitrogen bonds to the damaged bonding in the dielectric that occurs from the carbon depletion.

11. The method of claim 1, wherein depositing a tantalum containing layer on the nitrided surface a deposition process selected from the group consisting of sputtering, plating, electroplating, electroless plating and combinations thereof.

12. The method of claim 1, wherein metal fill comprises a metal selected from the group consisting of copper (Cu), tungsten (W), silver (Ag), gold (Au), platinum (Pt), aluminum (Al), titanium (Ti), Iridium (Jr), Ruthenium (Ru), Rhodium (Rh), Nickel (Ni), Cobalt (Co) and combinations thereof.

13. The method of claim 1, wherein the interconnect comprises a nitrided dielectric surface, a tantalum and nitrogen alloy layer that is present on the nitrided dielectric surface, a tantalum layer on the tantalum and nitrogen alloy layer surface, and a copper fill.

14. The method of claim 1, wherein the interconnect comprises a nitrided dielectric surface, a tantalum and nitrogen alloy layer that is present on the nitrided dielectric surface and a copper fill.