CN1571121A

CN1571121A - Copper electroplating method

Info

Publication number: CN1571121A
Application number: CN 03141565
Authority: CN
Inventors: 姜庆堂; 吴廷斌
Original assignee: Semiconductor Manufacturing International Shanghai Corp
Current assignee: Semiconductor Manufacturing International Shanghai Corp
Priority date: 2003-07-11
Filing date: 2003-07-11
Publication date: 2005-01-26

Abstract

A copper electroplating method for a copper manufacturing process, the cleaning solution formed by diluting low-concentration _H2O2 with deionized water is used to clean the substrate on which the copper seed layer is formed, so that _copper is formed on the surface of the copper seed layer oxide, the substrate was then placed in an electrolyte solution containing copper sulfate (CuSO ₄ ) and sulfuric acid (H ₂ SO ₄ ) to remove the copper oxide on the copper seed layer, and finally copper electroplating was performed to remove the copper oxide on the exposed copper seed layer. Copper is seamlessly grown on the new copper seed layer to obtain substantially defect-free copper wires and/or copper plugs.

Description

Copper electroplating method

Technical Field

The present invention relates to copper electroplating, and more particularly to copper electroplating for forming copper lines in semiconductor copper processing.

Background

In recent years, with the remarkable improvement of miniaturization of integrated circuits, aluminum wires in metallization processes belonging to the back-end of the integrated circuit process have been replaced by copper wires with smaller electrical conductivity, i.e., copper wires formed by the so-called copper process. For example, in a copper process, a so-called damascene structure (damascene structure) is formed, and after forming a barrier layer and/or a seed layer in the damascene structure, a copper wire is formed by electroplating copper. In the integrated circuit manufacturing process, contaminants such as organic substances may remain during the manufacturing and inspection processes. Although these residues are well controlled, as integrated circuits continue to shrink in feature size as they become smaller, the negative impact of these contaminants becomes more pronounced, making it increasingly difficult to achieve defect-free copper fills.

Disclosure of Invention

In view of the above problems, it is an object of the present invention to provide a copper electroplating method capable of removing contaminants on a barrier layer and/or a seed layer to expose a new copper layer so that copper can be deposited from the new copper layer during electroplating to seamlessly grow copper when performing copper electroplating.

The invention relates to a copper electroplating method; the method comprises the following steps: a cleaning step of diluting low-concentration H with deionized water₂O₂Cleaning the substrate with the copper seed layer by the formed cleaning solution so as to form copper oxide on the surface of the copper seed layer; a copper oxide removal step of exposing the substrate to a solution containing copper sulfate (CuSO)₄) And sulfuric acid (H)₂SO₄) Removing the copper oxide on the copper seed layer; and an electroplating step of performing copper electroplating to grow copper on the exposed new copper seed layer.

In the copper plating method according to the present invention, H in the cleaning liquid₂O₂In the range of 10PPM to 9% and for a washing time of about 1-10 seconds, and then dried, for example, by spinning.

Further, according to the copper electroplating method of the present invention, the copper oxide removal step is completed within one second, and then the electroplating step is immediately performed.

Furthermore, according to the copper electroplating method of the present invention, the copper oxide removal step and the electroplating step may be performed substantially simultaneously.

According to the copper electroplating method of the present invention, the wettability of the electrolyte to narrow features can be increased and the surface copper oxide can be removed together with unwanted contaminants to expose a new copper layer before the copper starts electroplating, thereby obtaining electroplated copper with good quality.

According to the present invention, the conventional electroplating machine can be implemented with only a slight modification of hardware to add a cleaning solution, and thus, the equipment investment can be reduced, but a copper wire having excellent performance can be obtained, and thus, a semiconductor device can be manufactured with high productivity, significantly reducing the production cost.

Furthermore, according to the present invention, it is possible to obtain copper grown seamlessly simply and easily, and perform copper electroplating at room temperature without deteriorating any important interface, and to form a copper wiring reliably at low cost.

Drawings

The above and other objects and advantages of the present invention will become more apparent in the description of the embodiments with reference to the accompanying drawings, in which:

FIG. 1 is an embodiment of a damascene structure to be formed with copper lines and/or copper plugs;

FIG. 2 is a cleaning process for explaining an embodiment of a copper electroplating method according to the present invention;

FIG. 3 is a schematic diagram illustrating a copper oxide layer removal process according to an embodiment of the copper electroplating method of the present invention; and

fig. 4 shows the final copper wire and/or copper plug formed according to an embodiment of the copper electroplating method of the present invention.

Detailed Description

An embodiment of copper plating for fabricating copper conductors in an integrated circuit according to the present invention will be described below with reference to the accompanying drawings. It is to be understood that the following description is intended to be illustrative only and is not intended to be limiting. Additionally, the figures are not drawn to scale in order to provide a clearer illustration.

In the following description, the process steps and corresponding structures according to embodiments of the present invention do not cover a complete process for manufacturing a complete IC circuit, but may be adapted to other processes in different IC circuits in the semiconductor technology field for manufacturing a desired complete IC circuit.

Fig. 1 is an embodiment of a damascene structure to be formed with copper lines and/or copper plugs, using an embodiment of a copper electroplating method according to the present invention, prior to copper electroplating. As shown in FIG. 1, 101 is SiO₂Layer as an interlayer metal dielectric in SiO₂A trench is formed in layer 101 and in SiO₂A barrier/seed layer 102 is formed on layer 101 by Physical Vapor Deposition (PVD). For simplicity, only one trench is shown in FIG. 1, butHowever, the number of grooves may be more than one. In addition, the black particles in fig. 1 represent organic substances or unwanted contaminants P attached to the surface of the seed layer during the manufacturing process or the inspection process.

Next, in the following, an embodiment of a copper electroplating method according to the present invention will be described by taking the damascene structure shown in fig. 1 as an example.

According to the present embodiment, the copper electroplating method mainly includes three processes, which are a cleaning process, a copper oxide layer removal process, and an electroplating process.

First, the cleaning procedure is explained. As shown in FIG. 2, in the cleaning procedure, H is diluted with deionized water₂O₂To form a dilution H₂O₂The solution RS cleans the damascene structure as shown in fig. 1. According to this example, diluted H₂O₂Solution RS is diluted with deionized water and contains 3% H₂O₂Low concentration of oxdol (oxydol). The damascene structure, after immersion in the dilute solution RS thus obtained, forms a thin copper oxide layer of about 50A thickness on the copper seed layer and improves the wettability of the narrow features by the electrolyte ES, facilitating the copper electroplating process. The chemical reaction for the formation of the above copper oxide is as follows:

(1)

(2)

this pre-cleaning step can be performed in the cleaning and drying chamber of a Sabre plating machine manufactured by Novellus or an iECP plating machine manufactured by Applied Materials, with only slight hardware modifications to add diluted H₂O₂And (4) dissolving.

Then, refer toFIG. 3 illustrates a new copper layer exposure process according to the present embodiment. After the cleaning process is completed and the desired thin oxide film is formed on the copper seed layer, the damascene structure is placed in the electrolyte solution ES for a very short time, e.g., less than one second, and the copper oxide layer formed in the cleaning process consists essentially of copper sulfate (CuSO)₂) And sulfuric acid (H)₂SO₄) The formed electrolyte solution ES is rapidly dissolved away, organic matters or unnecessary contaminants originally attached to the surface of the seed layer are removed as the copper oxide is dissolved in the electrolyte solution ES, and a new uncontaminated copper seed layer is exposed to serve as an initial layer for copper electroplating in a subsequent electroplating process. The chemical reaction of copper oxide with the electrolyte ES is as follows:

(3)

(4)

finally, immediately after the oxide removal process is completed by placing the damascene structure in the electrolyte ES, an electroplating process is performed to seamlessly deposit and grow the copper wire and/or the copper plug 104 as shown in fig. 4. The electroplating process may be a general electroplating process, i.e., electroplating is performed by placing appropriate electrodes into the electrolyte ES and then applying appropriate currents.

According to the present invention, the conventional electroplating machine can perform the present invention with only slight modification of hardware, and thus, the equipment investment can be reduced, but the copper wire and/or the copper plug having excellent performance can be obtained, and thus the semiconductor device can be manufactured with high yield, and the production cost can be remarkably reduced. In addition, the present invention can simply and easily perform copper electroplating, and can perform copper electroplating at room temperature without deteriorating any important interface, reliably obtain seamless grown copper, significantly improve production efficiency and reduce production cost.

In the above, the present invention is described in terms of preferred embodiments, but the present invention is not limited to the above preferred embodiments, and various modifications and changes can be made by those skilled in the art without departing from the spirit and scope of the present invention, and the scope of the present invention is limited only by the scope defined in the following claims and the equivalents thereof.

Claims

1. A copper electroplating method for a copper manufacturing process; comprising the steps of:

The cleaning step is to dilute the cleaning solution formed by the low-concentration _H2O2 with deionized water, and clean the _substrate on which the copper seed layer is formed, so that copper oxide is formed on the surface of the copper seed layer;

a copper oxide removal step, placing the substrate in an electrolyte comprising copper sulfate and sulfuric acid to remove copper oxide on the copper seed layer; and an electroplating step, performing copper electroplating to coat the exposed new copper seed layer Copper grows on it.

2. The copper electroplating method according to claim 1, _{characterized} in that the concentration of _H2O2 in the cleaning solution is 10PPM to 9%. The copper electroplating method as claimed in claim 1, wherein the electroplating step is performed immediately after performing the copper oxide removing step for less than one second.

3. The copper electroplating method as claimed in claim 1, wherein the copper oxide removing step is performed substantially simultaneously with the electroplating step.