US20080083624A1

US20080083624A1 - Electrolysis Plating System

Info

Publication number: US20080083624A1
Application number: US11/863,496
Authority: US
Inventors: Sang Chul Kim
Original assignee: Dongbu HitekCo Ltd
Current assignee: DB HiTek Co Ltd
Priority date: 2006-10-09
Filing date: 2007-09-28
Publication date: 2008-04-10
Also published as: KR100806032B1

Abstract

An electroplating apparatus and method are provided. The electrolysis plating apparatus includes an electrolytic cell, and copper electrode, a wafer electrode, and a magnetic field generator.

Description

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims the benefit under 35 U.S.C. §119 of Korean Patent Application No. 10-2006-0097749, filed Oct. 9, 2006, which is hereby incorporated by reference in its entirety.

BACKGROUND

As technology nodes of semiconductor devices become more developed, new processes for forming finer patterns are being introduced and methods of optimizing traditional processes are increasingly needed.
A process of filling a material, such as an insulating material, into a fine pattern is often called a gapfill process and is generally very sensitive to pattern shapes. Electrochemical plating (ECP) is widely used as a method of filling copper and involves forming a copper wire by an electroplating process. In a related art ECP method, a wafer is dipped into an electrolytic cell containing electrolyte, and a voltage is applied to a copper electrode and a wafer in the electrolytic cell to plate the wafer with copper. When the voltage is applied, an electric field is generated in the electrolytic cell. This electric field provides a driving force to cause the copper ions to migrate from the copper electrode to the wafer via the electrolyte. Therefore, it is possible to adjust the rate of depositing the copper ions on the surface of the wafer by regulating the characteristics of the electric field.
In very small devices, it can often be difficult to completely fill a wafer surface with copper ions by using an electric field. Since a copper wire has highest current density at its edges, copper ions are densely concentrated on the edges. The dense concentration of copper ions at the edges causes the copper ions to be accumulated more in the upper portion of a wafer than in the lower portion, as illustrated in FIG. 1. As a result, an overhang (not shown) is often formed on the upper portion of a wafer pattern. Thus, a via void is often formed inside the copper wire since the upper portion is filled with copper ions while the lower portion is not completely filled.
To account for this problem, an additive is sometimes used. However, this is disadvantageous because the additives used are very expensive, and the gapfill capability is mostly dependent upon the concentration of the additive. Thus, more additive is required to give better gapfill results, which raises the cost even more.
Moreover, the wafer itself rotates in an electrolytic cell of the related art ECP apparatus to attempt to deposit copper ions on the entire surface of a wafer. This rotation of the wafer, however, produces turbulence in the electrolytic solution, leading to the formation of bubbles. These bubbles inhibit the deposition of the copper ions, causing a void to be formed in the copper wire and leading to a reduced device yield.
Thus, there exists a need in the art for an improved ECP apparatus and deposition process.

BRIEF SUMMARY

Embodiments of the present invention provide a deposition process for a semiconductor device and an ECP apparatus. Magnetic force is used to provide a driving force enabling copper ions to uniformly reach a bottom of a wire.
In addition, by rotating a magnet instead of a wafer, formation of bubbles due to turbulence in electrolytic solution can be inhibited.
A semiconductor manufacturing apparatus according to an embodiment employs a magnet in an electrochemical plating (ECP) process without the use of an additive. Thus, the formation of a void typically caused by an overhang of a pattern can be inhibited, thereby reducing the process cost.
In an embodiment, an electrolysis plating apparatus can include: an electrolytic cell; a copper electrode provided in the electrolytic cell; a wafer electrode facing the copper electrode; and a magnetic field generator spaced apart from a rear side of the copper electrode, the wafer electrode, or both.
The details of one or more embodiments are set forth in the accompanying drawings and the detailed description below. Other features will be apparent to those skilled in the art from the detailed description, the drawings, and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a conceptual view illustrating the movement of copper ions in a related art electrolysis plating apparatus.

FIG. 2 is a cross-sectional view of an electrolysis plating apparatus according to an embodiment of the present invention.

FIG. 3 is a view of a magnetic field generator of an electrolysis plating apparatus according to an embodiment of the present invention.

FIG. 4 is a conceptual view illustrating the movement of copper ions in an electrolysis plating apparatus according to an embodiment of the present invention.

FIG. 5 is a conceptual view illustrating the movement of copper ions when a magnetic field generator rotates in an electrolysis plating apparatus according to an embodiment of the present invention.

FIG. 6 is a cross-sectional view of an electrolysis plating apparatus according to an embodiment of the present invention.

FIG. 7 is a cross-sectional view of an electrolysis plating apparatus according to an embodiment of the present invention.

DETAILED DESCRIPTION

When the terms “on” or “over” are used herein, when referring to layers, regions, patterns, or structures, it is understood that the layer, region, pattern or structure can be directly on another layer or structure, or intervening layers, regions, patterns, or structures may also be present. When the terms “under” or “below” are used herein, when referring to layers, regions, patterns, or structures, it is understood that the layer, region, pattern or structure can be directly under the other layer or structure, or intervening layers, regions, patterns, or structures may also be present.
Referring to FIG. 2, in an embodiment, an electrolysis plating apparatus can include an electrolytic cell 10, a copper electrode 20, a wafer electrode 30, and a magnetic field generator 40.
Electrolytic solution can be contained in the electrolytic cell 10, and the copper electrode 20 can be connected to a positive terminal of a power supply 50 and provided on a base of the electrolytic cell.
The wafer electrode 30 can be disposed in an upper portion of the electrolytic cell 10 such that it faces the copper electrode 20. This wafer electrode 30 can be connected to a negative terminal of the power supply 50 and can fix a wafer in place.
In an embodiment, the magnetic field generator 40 can be disposed over the rear side of the wafer electrode 30 and spaced apart from the wafer electrode 30. The magnetic field generator 40 can be fixed using fastening units known in the art. In many embodiments, the magnetic field generator 40 can be fixed such that it is free to rotate.
Referring to FIG. 3, the magnetic field generator 40 can include a permanent magnet or an electromagnet. In many embodiments, the magnetic field generator 40 can have a circular shape corresponding to the typical shape of a wafer. In addition, the magnetic field generator 40 can be provided with at least two N-poles or S-poles spaced apart in opposition to each other.
In a portion 40 a of the magnetic field generator 40, N-poles or S-poles can be arranged such that the magnetic force generated would be in the same direction as the electric force generated by the electric field between the copper electrode 20 and the wafer electrode 30. Another portion 40 b can be filled with a material, such as a non-magnetic material, to space apart the N-poles or S-poles from each other.
Referring to FIG. 6, in an embodiment, a magnetic field generator 40 can be disposed under the rear side of a copper electrode 20 and spaced apart from the copper electrode 20. In embodiments where a magnetic field generator 40 is provided under a copper electrode 20, magnetic poles (N-poles or S-poles, see 40 a of FIG. 3) of the magnetic field generator 40 face the opposite direction than those of a magnetic field generator 40 in embodiments where the magnetic field generator 40 is provided above the wafer electrode 30.
Referring to FIG. 7, magnetic field generators 40 can be disposed both over the rear side of a wafer electrode 30 and under the rear side of a copper electrode 20. The magnetic field generators 40 can each be spaced apart from the copper electrode 20 and the wafer electrode 30. Magnetic poles (N-poles or S-poles, see 40 a of FIG. 3) of one of the magnetic field generators 40 can be arranged to face the magnetic poles of the other magnetic field generator 40 such that the magnetic force generated by the magnetic field generators 40 would be in the same direction as the electric force generated by the electric field between the copper electrode 20 and the wafer electrode 30.
When the power supply 50 is connected to the copper electrode 20 and the wafer electrode 30, copper ions (Cu²⁺) released from the copper electrode 20 can be deposited on a wafer fixed to the wafer electrode 30.
Copper ions can be affected by the magnetic force generated by a magnetic Field generator 40 as well as the electric force generated by the copper electrode 20 and the wafer electrode 30. In an embodiment, the intensity of the electric field and the intensity of the magnetic field can be modulated by regulating the applied power, making it possible to adjust the movement of the copper ions.
For example, the electric force and the magnetic force can each be adjusted to provide half the force required to deposit the copper ions on the wafer.
Although lines of magnetic force may leave the N-pole and enter the S-pole in a curved shape generally, the lines of magnetic force between the copper electrode and the wafer electrode can be effectively straight because the space between the copper electrode and the wafer electrode is often much smaller than the lengths of the lines of the magnetic field. Therefore, it is possible to generate effectively straight lines of the magnetic field by adjusting the intensity of the magnetic field and the space between the copper electrode and the wafer electrode.
Referring to FIG. 4, in order to inhibit copper ions from being concentrated on the edges of a wafer pattern, the intensity of the magnetic field can be increased while decreasing the intensity of the electric field.
Referring to FIG. 5, in many embodiments, the magnetic field generator 40 (shown in FIG. 2) can be rotating while generating the magnetic force, allowing copper ions from the copper electrode 20 to be more uniformly deposited on the entire surface of the wafer on the wafer electrode 30. Furthermore, while a wafer is rotated in a related art electrolysis plating apparatus, in embodiments of the present invention, the wafer can be fixed as the magnetic field generator 40 rotates, making it possible to inhibit the formation of bubbles in the electrolyte.
In an electrolysis plating apparatus according to embodiments of the present invention, the formation of a void in a via can be inhibited, thereby improving uniformity of a wafer pattern. In addition, the formation of bubbles in the electrolyte can be inhibited since the wafer can be fixed. Accordingly, the electrolysis plating apparatus of embodiments of the present invention allows for an improved wafer yield and lower fabrication costs with no additives required.
Any reference in this specification to “one embodiment,” “an embodiment,” “example embodiment,” etc., means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with any embodiment, it is submitted that it is within the purview of one skilled in the art to effect such feature, structure, or characteristic in connection with other ones of the embodiments.
Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure. More particularly, various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the disclosure, the drawings and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art.

Claims

1. An electrolysis plating apparatus, comprising:

an electrolytic cell;

a copper electrode provided in the electrolytic cell;

a wafer electrode in the electrolytic cell and facing the copper electrode; and

a first magnetic field generator spaced apart from a rear side of the copper electrode or the wafer electrode.

2. The electrolysis plating apparatus according to claim 1, wherein the first magnetic field generator is spaced apart from the rear side of the wafer electrode.

3. The electrolysis plating apparatus according to claim 2, further comprising a second magnetic field generator spaced apart from the rear side of the copper electrode.

4. The electrolysis plating apparatus according to claim 1, wherein the first magnetic field generator has a circular shape.

5. The electrolysis plating apparatus according to claim 1, wherein the first magnetic field generator comprises at least two poles of the same polarity spaced apart in opposition to each other.

6. The electrolysis plating apparatus according to claim 1, wherein the first magnetic field generator comprises an electromagnet.

7. The electrolysis plating apparatus according to claim 1, wherein the first magnetic field generator comprises a permanent magnet.

8. The electrolysis plating apparatus according to claim 1, wherein the first magnetic field generator is capable of rotating.

9. The electrolysis plating apparatus according to claim 1, further comprising a power supply.

10. The electrolysis plating apparatus according to claim 9, wherein the copper electrode is electrically connected to a positive terminal of the power supply, and wherein the wafer electrode is electrically connected to a negative terminal of the power supply.

11. An electrolysis plating method, comprising:

disposing a copper electrode in an electrolytic cell; disposing a wafer on a wafer electrode in the electrolytic cell such that the wafer faces the copper electrode;

providing a first magnetic field generator spaced apart from a rear side of the copper electrode or the wafer electrode; and

depositing copper ions on the wafer by operating the copper electrode and the wafer electrode and operating the first magnetic field generator.

12. The electrolysis plating method according to claim 11, wherein the first magnetic field generator is provided spaced apart from a rear side of the wafer electrode.

13. The electrolysis plating method according to claim 12, further comprising providing a second magnetic field generator spaced apart from a rear side of the copper electrode, and wherein depositing the copper ions on the wafer further comprises operating the second magnetic field generator.

14. The electrolysis plating method according to claim 11, wherein the first magnetic field generator has a circular shape.

15. The electrolysis plating method according to claim 11, wherein the first magnetic field generator comprises at least two poles of the same polarity spaced apart in opposition to each other.

16. The electrolysis plating method according to claim 11, wherein the first magnetic field generator comprises an electromagnet.

17. The electrolysis plating method according to claim 11, wherein the first magnetic field generator comprises a permanent magnet.

18. The electrolysis plating method according to claim 11, wherein operating the first magnetic field generator comprises rotating the first magnetic field generator.

19. The electrolysis plating method according to claim 11, further comprising providing a power supply.

20. The electrolysis plating method according to claim 19, wherein the copper electrode is electrically connected to a positive terminal of the power supply, and wherein the wafer electrode is electrically connected to a negative terminal of the power supply, and wherein operating the copper electrode and the wafer electrode comprises providing power from the power supply.