Cobalt first layer advanced metallization for interconnects

• US 10,170,424 B2
• Filed: 11/07/2017
• Issued: 01/01/2019
• 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:
  US15/806,304
• Publication Number:
  US 20180061768A1
• Time in Patent Office: 420 Days
• CPC Class Codes: H01L 21/2855 by physical means, e.g. sputtering, evaporation H01L21/28518 - H01L21/28537 and H01L21/28568 take precedence
• CPC Class Codes: H01L 21/28568 the conductive layers comprising transition metals H01L21/28518 takes precedence
• CPC Class Codes: H01L 21/3212 by chemical mechanical polishing [CMP]
• CPC Class Codes: H01L 21/76802 by forming openings in dielectrics
• 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 21/7684 Smoothing; Planarisation
• CPC Class Codes: H01L 21/76843 formed in openings in a dielectric
• CPC Class Codes: H01L 21/76846 Layer combinations
• CPC Class Codes: H01L 21/76855 After-treatment introducing at least one additional element into the layer
• CPC Class Codes: H01L 21/76856 by treatment in plasmas or gaseous environments, e.g. nitriding a refractory metal liner
• CPC Class Codes: H01L 21/76858 by diffusing alloying elements
• CPC Class Codes: H01L 21/76864 Thermal treatment
• CPC Class Codes: H01L 21/76877 Filling of holes, grooves or trenches, e.g. vias, with conductive material
• CPC Class Codes: H01L 21/76882 Reflowing or applying of pressure to better fill the contact hole
• 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 23/53209 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 23/53238 : Additional layers associated with copper layers, e.g. adhesion, barrier, cladding layers
• CPC Class Codes: H01L 23/53247 : Noble-metal alloys
• CPC Class Codes: H01L 23/53252 : Additional layers associated with noble-metal 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 metal conductor structures and an adhesion promoting layer in the set of features;

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 layer;

performing a thermal anneal which reflows the cobalt layer to fill a first portion of the set of features leaving a second, remaining portion of the set of features unfilled; and

depositing a second metal layer to fill the second, remaining portion of the set of features, wherein the second metal is a metal other than cobalt, wherein a thickness of the reflowed cobalt layer from the ruthenium layer to a bottom of the second metal layer and a thickness of the second metal layer after planarization are substantially equal.

2. The method as recited in claim 1, wherein the adhesion promoting layer is a liner layer of a single layer comprised of a material selected from the group consisting of Ta, Ti, W, TaN, TiN and WN.

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 is formed.

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

5. The method as recited in claim 4, wherein the nitridation process is selected from the group of a plasma nitridation process and a thermal nitridation process.

6. The method as recited in claim 1, wherein the adhesion promoting layer is comprised of a nitrogen enriched layer formed in the patterned dielectric 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.

7. The method as recited in claim 1, wherein the set of metal conductor structures are a set of conductive lines.

8. The method as recited in claim 1, further comprising removing excess material on field areas of the dielectric layer using a planarization process.

9. The method as recited in claim 8, wherein the planarization process is a chemical mechanical polishing process.

10. The method as recited in claim 1, wherein the second metal layer is selected from the group consisting of Ni, Ir and Rh.

11. The method as recited in claim 1, wherein the respective thicknesses of the reflowed cobalt layer and the second metal layer are formed according to a desired resistivity and reliability needed for the advanced metal connector structure.

12. The method as recited in claim 1, wherein a first dimension of the advanced metal connector structure is less than twenty nanometers.

13. 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 metal conductor structures and an adhesion promoting layer in the set of features;

creating an adhesion promoting layer disposed on the patterned dielectric;

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 layer;

performing a thermal anneal which reflows the cobalt layer to fill a first portion of the set of features leaving a second, remaining portion of the set of features unfilled, wherein the reflowed cobalt layer has a u-shaped cross-section having a thicker bottom layer than side layers; and

depositing a second metal layer to fill the second, remaining portion of the set of features, wherein the second metal is a metal other than cobalt, wherein a thickness of the reflowed cobalt layer from the ruthenium layer to a bottom of the second metal layer and a thickness of the second metal layer after planarization are substantially equal.

14. 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 metal conductor structures and an adhesion promoting layer in the set of features;

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 layer;

performing a thermal anneal which reflows the cobalt layer to form a first metal fill layer filling a first portion of the set of features leaving a second, remaining portion of the set of features unfilled; and

depositing a second metal layer to form a second metal fill layer filling the second, remaining portion of the set of features, wherein the second metal is a metal other than cobalt wherein a thickness of the reflowed cobalt layer from the ruthenium layer to a bottom of the second metal layer and a thickness of the second metal layer after planarization are on the same order of magnitude.

15. The method as recited in claim 14, wherein the cobalt layer and the second metal layer fill a majority of the pattern in the dielectric.