# US 8,771,804 B2 · Processes and systems for engineering a copper surface for selective metal deposition

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 8,771,804 B2
- Document ID: US8771804B2
- Status: Granted
- Kind: B2
- Application number: 11/513,634
- Filed: 2006-08-30
- Published: 2007-12-20
- Granted: 2014-07-08
- Earliest claimed: 2005-08-31
- Assignees: Lam Research Corporation
- Applicants: Yezdi Dordi; John Boyd; Tiruchirapalli Arunagiri; Fritz C. Redeker; William Thie; Arthur M. Howald
- Inventors: Yezdi Dordi; John Boyd; Tiruchirapalli Arunagiri; Fritz C. Redeker; William Thie; Arthur M. Howald
- Web page: https://patentgrep.com/patent/US8771804B2

## CPC

- B05C 13/02: for particular articles
- B05D 3/002: {Pretreatement}
- C23C 18/1651: {Two or more layers only obtained by electroless plating}
- C23C 18/1851: {of surfaces of non-metallic or semiconducting in organic material}
- C23C 18/1893: {with use of organic or inorganic compounds other than metals, first}
- H10D 64/0112: {using conductive layers comprising silicides}
- H10P 14/46: using a liquid
- H10P 50/266: {by vapour etching only}
- H10P 50/267: {using plasmas}
- H10P 70/23: {during, before or after processing of insulating materials}
- H10P 70/234: {the processing being the formation of vias or contact holes}
- H10P 70/27: {during, before or after processing of conductive materials, e.g. polysilicon or amorphous silicon layers}
- H10P 70/277: {the processing being a planarisation of conductive layers}
- H10P 72/0452: {characterised by the layout of the process chambers}
- H10P 72/0468: {comprising a chamber adapted to a particular process}
- H10P 95/04: {Planarisation of conductive or resistive materials}
- H10W 20/033: {in openings in dielectrics}
- H10W 20/035: {combinations of barrier, adhesion or liner layers, e.g. multi-layered barrier layers}
- H10W 20/037: {the barrier, adhesion or liner layers being on top of a main fill metal}
- H10W 20/0523: {by irradiating with ultraviolet or particle radiation}
- H10W 20/062: {by smoothing of conductive parts, e.g. by planarisation}
- H10W 20/081: {by forming openings in the dielectric parts}
- B05C: APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL (spraying apparatus, atomising apparatus, nozzles B05B; plant for applying liquids or other fluent materials to objects by electrostatic spraying B05B5/08)
- B05D: PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL (conveying articles or workpieces through baths of liquid B65G, e.g. B65G49/02)
- C23C: COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04)
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10

## Abstract

The embodiments fill the need to enhance electro-migration performance, provide lower metal resistivity, and improve metal-to-metal interfacial adhesion for copper interconnects by providing improved processes and systems that produce an improved metal-to-metal interface, more specifically copper-to-cobalt-alloy interface. An exemplary method of preparing a substrate surface of a substrate to selectively deposit a thin layer of a cobalt-alloy material on a copper surface of a copper interconnect of the substrate in an integrated system to improve electromigration performance of the copper interconnect is provided. The method includes removing contaminants and metal oxides from the substrate surface in the integrated system, and reconditioning the substrate surface using a reducing environment after removing contaminants and metal oxides in the integrated system. The method also includes selectively depositing the thin layer of cobalt-alloy material on the copper surface of the copper interconnect in the integrated system after reconditioning the substrate surface. An exemplary system to practice the exemplary method described above is also provided.

## Claims

### Claim 1

A method of preparing a substrate surface of a substrate to selectively deposit a thin layer of a cobalt-alloy material on a copper surface of a copper interconnect of the substrate in an integrated system to improve electromigration performance of the copper interconnect, comprising:
removing contaminants and metal oxides from the substrate surface in a wet process module connected to a first transfer module, which is a lab-ambient transfer module of the integrated system;
after removing contaminants and metal oxides, moving the substrate from the wet process module to the lab-ambient transfer module;
moving the substrate from the lab-ambient transfer module to a second transfer module, which is a vacuum transfer module;
moving the substrate from the vacuum transfer module to a plasma module connected to the vacuum transfer module;
reconditioning the copper surface of the copper interconnect using a reducing environment, after removing contaminants and metal oxides, in the plasma module connected to the vacuum transfer module of the integrated system;
after reconditioning the copper surface, moving the substrate from the plasma module to the vacuum transfer module;
moving the substrate from the vacuum transfer module to a third transfer module, which is a controlled-ambient transfer module;
moving the substrate from the controlled-ambient transfer module to a wet electroless deposition process module connected to the controlled-ambient transfer module;
selectively depositing the thin layer of cobalt-alloy material on the copper surface of the copper interconnect, after reconditioning the substrate surface, in the wet-electroless deposition process module;
wherein one or more process modules and the transfer modules of the integrated system being filled with inert gas to reduce oxygen exposure during transfers of the substrate within the integrated system, the transfers of the substrate include transfers between the transfer modules of the integrated system, the wet electroless deposition process module being filled with the inert gas to maintain an oxygen level in the processing environment that is lower than ambient, and transfers in the inert gas filled transfer modules protects the copper surface from oxidation after the contaminants and the metal oxides are removed from the substrate surface and before the thin layer of cobalt-alloy material is selectively deposited on the copper surface;
wherein the wet electroless deposition process module provides for a dry-in/dry-out processing of the substrate, the substrate goes in and comes out of the wet electroless deposition process module in a dry state, the wet electroless deposition process module providing for rinse and dry operations without wet robotic transfer of the substrate to a separate rinse-dry module;
wherein reconditioning the substrate surface converts surface copper oxides to substantially copper, and after reconditioning the substrate surface, the substrate is transferred and processed in a controlled environment to minimize the formation of copper oxide over the copper surface;
wherein after reducing the copper surface, the substrate is transferred and processed with limited exposure to oxygen to enable the thin layer of the cobalt-alloy material to be selectively deposited on the copper surface, and wherein the first transfer module, the second transfer module and the third transfer modules are distinct, and wherein after electroless deposition the substrate is transferred from the electroless chamber to the controlled ambient transfer module, and from the controlled ambient transfer module, the substrate is transferred to the vacuum transfer module, and then from the vacuum transfer module the substrate is transferred to the lab ambient transfer module.

### Claim 2 (depends on 1)

The method of claim 1, wherein the copper interconnect has a metal line over a via, the copper interconnect is lined with a metallic barrier layer and is filled with a copper layer, the substrate with the copper interconnect being removed of a copper overburden and a metallic barrier overburden by a metal chemical-mechanical polishing before the substrate is moved to the integrated system.

### Claim 3 (depends on 1)

The method of claim 1, wherein the contaminants comprises metal-organic complex contaminants and organic contaminants.

### Claim 4 (depends on 3)

The method of claim 3, wherein complexed metal-organic contaminants comprises copper-BTA complex.

### Claim 5 (depends on 3)

The method of claim 3, wherein the metal-organic complex contaminants are removed by a wet clean process using a cleaning solution that includes tetramethylammonium hydroxide (TMAH).

### Claim 6 (depends on 3)

The method of claim 3, wherein the metal-organic complex contaminants are removed by a wet clean process using a cleaning solution that includes complexing amines.

### Claim 7 (depends on 1)

The method of claim 1, wherein the metal oxides are removed by a wet clean process using a cleaning solution that includes one of citric acid, sulfuric acid, or sulfuric acid with hydrogen peroxide.

### Claim 8 (depends on 1)

The method of claim 1, wherein the substrate surface includes the copper surface and a dielectric surface.

### Claim 9 (depends on 1)

The method of claim 1, wherein the substrate surface is reconditioned by a hydrogen-containing plasma, which is generated by hydrogen (H2) gas, ammonia (NH3) gas, or a combination of both gases.

### Claim 10 (depends on 1)

The method of claim 1, wherein the substrate surface is reconditioned at a temperature of between 20° C. and 300° C.

### Claim 11 (depends on 1)

The method of claim 1, wherein the substrate is transferred and processed in the integrated system to limit a duration the substrate is exposed to oxygen.

### Claim 12 (depends on 1)

The method of claim 1, wherein the thin layer of the cobalt-alloy material is selectively deposited by an electroless deposition process on the copper surface to promote adhesion between the copper surface of the copper interconnect and a dielectric capping layer for the copper interconnect.

### Claim 13 (depends on 1)

The method of claim 1, wherein the thickness of the thin layer of the cobalt-alloy material is between about 5 angstroms to about 300 angstroms.

### Claim 14 (depends on 1)

The method of claim 1, wherein the cobalt-alloy material is selected from the group consisting of CoWP, CoWB, and CoWBP.

### Claim 15 (depends on 1)

The method of claim 1, further comprising cleaning the substrate surface after selectively depositing the cobalt-alloy material on the copper surface.

### Claim 16 (depends on 15)

The method of claim 15, wherein cleaning the substrate surface after selectively depositing the cobalt-alloy material on the copper surface of the copper interconnect uses a hydroxylamine-based chemistry.

### Claim 17 (depends on 1)

The method of claim 1, further comprising:
after selectively depositing the thin layer of cobalt-alloy material, moving the substrate from the wet electroless deposition process module to the controlled-ambient transfer module;
moving the substrate from the controlled-ambient transfer module to the vacuum transfer module;
moving the substrate from the vacuum transfer module to the lab-ambient transfer module.

### Claim 18

A method of preparing a substrate surface of a substrate to selectively deposit a layer of a cobalt-alloy material on a copper surface of a copper interconnect of the substrate in an integrated system, comprising:
removing metal-organic complex contaminants and metal oxides from the substrate surface by a wet process in one or more process modules connected to a first transfer module, which is a lab-ambient transfer module of the integrated system;
after removing metal-organic complex contaminants and metal oxides, moving the substrate to the lab-ambient transfer module;
moving the substrate from the lab-ambient transfer module to a second transfer module, which is a vacuum transfer module;
moving the substrate from the vacuum transfer module to a dry plasma process module connected to the vacuum transfer module;
removing organic contaminants from the substrate surface by a dry process in the dry plasma process module connected to the vacuum transfer module of the integrated system;
after removing organic contaminants, moving the substrate from the dry plasma process module to the vacuum transfer module;
moving the substrate from the vacuum transfer module to a plasma etch process module connected to the vacuum transfer module;
removing a metallic barrier overburden of the copper interconnect in the plasma etch process module connected to the vacuum transfer module of the integrated system, after the metal-organic complex contaminants, metal oxides and organic contaminants are removed from the substrate surface;
after removing the metallic barrier overburden, moving the substrate from the plasma etch process module to the vacuum transfer module;
moving the substrate from the vacuum transfer module to a third transfer module, which is a controlled-ambient transfer module;
moving the substrate from the controlled-ambient transfer module to a wet electroless deposition process module connected to the controlled-ambient transfer module;
selectively depositing the thin layer of the cobalt-alloy material on the copper surface of the copper interconnect after removing the metallic barrier overburden, in the wet-electroless deposition process module;
wherein one or more process modules and the transfer modules of the integrated system being filled with inert gas to reduce oxygen exposure during transfers of the substrate within the integrated system, the transfers of the substrate include transfers between the transfer modules of the integrated system, the wet electroless deposition process module being filled with the inert gas to maintain an oxygen level in the processing environment that is lower than ambient, and transfers in the inert gas filled transfer modules protects the copper surface from oxidation after the contaminants and the metal oxides are removed from the substrate surface and before the thin layer of cobalt-alloy material is selectively deposited on the copper surface;
wherein the wet electroless deposition process module provides for a dry-in/dry-out processing of the substrate, the substrate goes in and comes out of the wet electroless deposition process module in a dry state, the wet electroless deposition process module providing for rinse and dry operations without wet robotic transfer of the substrate to a separate rinse-dry module, and wherein the first transfer module, the second transfer module and the third transfer modules are distinct, and wherein after electroless deposition the substrate is transferred from the electroless chamber to the controlled ambient transfer module, and from the controlled ambient transfer module, the substrate is transferred to the vacuum transfer module, and then from the vacuum transfer module the substrate is transferred to the lab ambient transfer module.

### Claim 19 (depends on 18)

The method of claim 18, wherein the metal-organic complex contaminants are removed from the substrate surface using a first wet chemistry prior to removing metal oxides using a second wet chemistry.

### Claim 20 (depends on 18)

The method of claim 18, wherein metal oxides contaminants are removed from the substrate surface using a first wet chemistry prior to removing the metal-organic complex contaminants using a second wet chemistry.

### Claim 21 (depends on 18)

The method of claim 18, further comprising:
reducing the copper surface of the copper interconnect to convert copper oxides to copper after the substrate has been removed of the metallic barrier overburden, wherein after reducing copper surface, the substrate is transferred or processed in controlled environment to minimize the formation of copper oxide, the copper surface being removed of copper oxide to increase the selectivity of the cobalt-alloy material on the copper surface.

### Claim 22 (depends on 18)

The method of claim 18, wherein the thin layer of the cobalt-alloy material is selectively deposited by an electroless deposition process on the copper surface to promote adhesion between the copper surface of the copper interconnect and a dielectric capping layer for the copper interconnect.

### Claim 23 (depends on 18)

The method of claim 18, wherein the substrate is transferred and processed in the integrated system to limit a duration the substrate is exposed to oxygen.

### Claim 24 (depends on 18)

The method of claim 18, wherein the metallic bather overburden is removed using one of a plasma etch process or a wet chemical etch process.

### Claim 25 (depends on 18)

The method of claim 18, wherein the substrate is transferred and processed in controlled environment to enable the thin layer of the cobalt-alloy material to be selectively deposited on the copper surface.

### Claim 26 (depends on 18)

The method of claim 18,
wherein reconditioning the substrate surface converts surface copper oxides to substantially copper, and after reconditioning the substrate surface, the substrate is transferred and processed in a controlled environment to minimize the formation of copper oxide over the copper surface;
wherein after reducing the copper surface, the substrate is transferred and processed with limited exposure to oxygen to enable the thin layer of the cobalt-alloy material to be selectively deposited on the copper surface.

### Claim 27 (depends on 18)

The method of claim 18, further comprising:
after selectively depositing the thin layer of cobalt-alloy material, moving the substrate from the wet electroless deposition process module to the controlled-ambient transfer module;
moving the substrate from the controlled-ambient transfer module to the vacuum transfer module;
moving the substrate from the vacuum transfer module to the lab-ambient transfer module.