Formation of advanced interconnects

• US 10,177,092 B2
• Filed: 11/15/2017
• Issued: 01/08/2019
• Est. Priority Date: 08/17/2016
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Edelstein, Daniel C, Yang, Chih-Chao
• Primary Examiner(s): Page, Dale E
• Assistant Examiner(s): Haider, Wasiul
• Application Number:
  US15/813,477
• Publication Number:
  US 20180082952A1
• Time in Patent Office: 419 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 21/76831 in via holes or trenches, e.g. non-conductive sidewall liners
• CPC Class Codes: H01L 21/76843 formed in openings in a dielectric
• CPC Class Codes: H01L 21/76858 by diffusing alloying elements
• CPC Class Codes: H01L 21/76879 by selective deposition of conductive material in the vias, e.g. selective C.V.D. on semiconductor material, plating plating on semiconductors in general H01L21/288
• CPC Class Codes: H01L 21/76882 Reflowing or applying of pressure to better fill the contact hole
• CPC Class Codes: H01L 21/76883 Post-treatment or after-treatment of the conductive material
• CPC Class Codes: H01L 23/5226 Via connections in a multilevel interconnection structure
• CPC Class Codes: H01L 23/528 Geometry or layout of the interconnection structure H01L27/0207 takes precedence; algorithms G06F30/00
• CPC Class Codes: H01L 23/5283 Cross-sectional geometry
• CPC Class Codes: H01L 23/53209 based on metals, e.g. alloys, metal silicides H01L23/53285 takes precedence
• CPC Class Codes: H01L 23/53223 Additional layers associated with aluminium layers, e.g. adhesion, barrier, cladding layers
• CPC Class Codes: H01L 23/53261 Refractory-metal alloys
• CPC Class Codes: H01L 23/53266 Additional layers associated with refractory-metal layers, e.g. adhesion, barrier, cladding layers

Abstract

A method for fabricating an advanced metal conductor structure is described. A pattern in a dielectric layer is provided. The pattern includes a set of features in the dielectric for a set of metal conductor structures. An adhesion promoting layer is created over the patterned dielectric. A ruthenium layer is deposited over the adhesion promoting layer. Using a physical vapor deposition process, a cobalt layer is deposited over the ruthenium layer. A thermal anneal is performed which reflows the cobalt layer to fill the set of features to form a set of metal conductor structures.

Claims

1. A method for fabricating an advanced metal conductor structure comprising:

providing a pattern in a dielectric layer, wherein the pattern includes a set of features in the dielectric for a set of interconnect metal conductor structures which interconnect conductive line layers to other elements of an integrated circuit;

creating an adhesion promoting layer disposed on the patterned dielectric layer;

depositing a ruthenium metal layer disposed on the adhesion promoting layer;

using a physical vapor deposition process to deposit a cobalt layer disposed on the ruthenium metal layer; and

performing a thermal anneal which reflows the cobalt layer to completely fill a remainder portion of the set of interconnect metal conductor features to form the set of interconnect metal conductor structures.

2. The method as recited in claim 1, wherein the adhesion promoting layer is a liner layer.

3. The method as recited in claim 2, wherein the thermal anneal is carried out in a temperature range between 300-800 degrees Centigrade in a neutral ambient and a RuCo alloy layer is formed between the ruthenium and cobalt layers.

4. The method as recited in claim 3, wherein the cobalt layer is reflowed over the RuCo alloy layer during the creation of the RuCo alloy layer.

5. The method as recited in claim 1, wherein the adhesion promoting layer is a nitrogen enriched layer formed in the patterned dielectric layer produced by a nitridation process.

6. The method as recited in claim 5, wherein the nitridation process is selected from the group of a plasma nitridation process and a thermal nitridation process.

7. The method as recited in claim 5, wherein the thermal anneal is carried out in a temperature range between 300-800 degrees Centigrade in a neutral ambient and the ruthenium metal layer and a portion of the cobalt layer forms a RuCo alloy liner layer disposed over and bonded to the nitrogen enriched layer formed in the patterned dielectric.

8. The method as recited in claim 5, wherein the thermal anneal is carried out in a temperature below 300 Centigrade and the ruthenium metal layer and the cobalt layer forms a Ru/Co interface and the ruthenium metal layer is disposed over and bonded to the nitrogen enriched layer formed in the patterned dielectric.

9. The method as recited in claim 1, wherein the adhesion promoting layer is comprised of a nitrogen enriched layer formed in the patterned dielectric layer produced by a nitridation process and a liner layer comprised of one or more materials selected from the group consisting of Ta, Ti, W, TaN, TiN and WN.

10. The method as recited in claim 1, wherein the set of metal conductor structures further comprise a set of conductive lines.

11. The method as recited in claim 10, wherein the set of interconnect metal conductor structures reduce resistance-capacitance delays as compared to interconnects made of copper.

12. The method as recited in claim 1, further comprising removing excess material on field areas of the dielectric layer outside the set of interconnect metal conductor features using a planarization process.

13. The method as recited in claim 12, wherein the planarization process is a chemical mechanical polishing process.

14. The method as recited in claim 1, wherein the method is used as part of a Damascene process which forms the set of interconnect metal conductor structures which interconnect conductive line layers to other elements of an integrated circuit.

15. The method as recited in claim 1, wherein the thermal anneal is carried out in a temperature range between 300-800 degrees Centigrade in a neutral ambient and the ruthenium metal layer and a portion of the cobalt layer forms a RuCo alloy liner layer disposed over and bonded to the adhesion promoting layer.