Electroplating apparatus and electroplating method using the same
Provided are an electroplating apparatus and an electroplating method using the electroplating apparatus. The electroplating apparatus includes an electroplating bath, an anode, a cathode, and a conductor. An electroplating solution is supplied into the electroplating bath. An electroplating solution entrance and an electroplating solution exit are formed in the electroplating bath. The anode is installed inside the electroplating bath. The cathode is spaced a predetermined gap apart from and opposite to the anode. A layer that is to electroplated is installed on the cathode. The conductor is installed between the anode and the cathode.
This application claims priority from Korean Patent Application No. 10-2005-0018795 filed on Mar. 7, 2005 in the Korean Intellectual Property Office, the contents of which are incorporated herein by reference in their entirety.
BACKGROUND OF THE INVENTION1. Field of the Invention
The present invention relates to an electroplating apparatus and an electroplating method using the same, and more particularly, to an electroplating apparatus and an electroplating method using the same, in which a metal layer is formed on the surface of a layer that is to be electroplated.
2. Description of the Related Art
Recently, metal interconnections using copper (Cu) having low electric resistance and acceptable electromigration characteristics in place of conventional aluminum (Al) have been introduced in semiconductor fabrication technology.
Copper has increasingly become a metal of choice in metal interconnection due to its several advantages such as secured electric conductivity, acceptable signal characteristic, low manufacturing cost and good electromigration characteristics, compared to conventionally used aluminum. Unlike aluminum, however, copper is hard to dry-etch. Accordingly, a new type of pattern forming method, called a damascene process, is used with copper. In the damascene process, interconnect line trenches and vias are first etched in an insulating layer, and an interconnect material, i.e., copper, is then filled into the trenches and vias. A copper layer is formed through several sequential processes, including a pre-cleaning process, a diffusion barrier forming process, a copper seed layer forming process, and a copper electroplating process.
In the copper electroplating process where copper in an electroplating solution is electroplated onto a structure that is to be electroplated, e.g., a semiconductor substrate, an electroplating apparatus is usually used.
Referring to
Once an electroplating solution is supplied to the electroplating bath 11 through the electroplating solution entrance 12 using, for example, a fountain device, it flows toward the cathode 15 under the influence of a magnetic field formed between the anode 13 and the cathode 15. The layer that is to be electroplated 14 is mounted on a surface of the cathode 15 opposite to the anode 13, such that electroplating ions of the electroplating solution flowing from the anode 13 are deposited on the layer 14 that is to be electroplated. At this time, the remaining electroplating solution that is not deposited on the layer 14 is exhausted outside the electroplating bath 11 through the electroplating solution exit 16 and is supplied back to the electroplating bath 11 after undergoing a predetermined cleaning process.
However, when using the electroplating apparatus 10, as shown in
The present invention provides an electroplating apparatus which can form an electroplating layer having a uniform thickness on a layer that is to be electroplated.
The present invention provides an electroplating method by which an electroplating layer having a uniform thickness can be formed on a layer that is to be electroplated.
The above stated objects as well as other objects, features and advantages, of the present invention will become clear to those skilled in the art upon review of the following description.
According to an aspect of the present invention, there is provided an electroplating apparatus. The electroplating apparatus includes an electroplating bath, an anode, a cathode, and a conductor. An electroplating solution is supplied into the electroplating bath. An electroplating solution entrance and an electroplating solution exit are formed in the electroplating bath. The anode is installed inside the electroplating bath. The cathode is spaced a predetermined gap apart from and opposite to the anode. A layer that is to be electroplated is installed on the cathode. The conductor is installed between the anode and the cathode.
In one embodiment, at least one hole is formed in the conductor. The outer circumference of the conductor can be tangent to the inner surface of the electroplating bath.
In one embodiment, an insulating layer is formed on a surface of the conductor opposite to and facing the layer that is to be electoplated. The insulating layer can be selectively formed in the peripheral portion of the conductor. The insulating layer can be formed of polymer or metal oxide.
In one embodiment, the conductor is shaped such that it is closer to the layer that is to be electroplated at its central portion than at its peripheral portions.
In one embodiment, a distance from the conductor to the layer that is to be electroplated is smaller than or equal to a distance from the conductor to the cathode.
In one embodiment, the anode is a soluble anode.
In one embodiment, a filter is installed between the anode and the conductor. The filter can be a selective ion exchange filter. The anode can be an insoluble anode.
In one embodiment, an external power source is connected to the conductor to apply a voltage to the conductor. The voltage applied to the conductor can be smaller than a voltage applied to the anode and larger than a voltage applied to the cathode.
In one embodiment, the conductor includes at least two sections that are electrically separated from each other. Different voltages can be applied to the at least two sections.
In one embodiment, the conductor is substantially parallel to the layer that is to be electroplated.
In one embodiment, a reduction potential of the conductor is smaller than a reduction potential of electroplating ions in the electroplating solution.
In one embodiment, the surface of the conductor is plated with at least one selected form the group consisting of copper (Cu), silver (Ag), platinum (Pt), gold(Au), titanium (Ti), tantalum (Ta), aluminum (Al), and an alloy thereof.
According to another aspect of the present invention, there is provided an electroplating method for electroplating a layer using the above referenced electroplating apparatus.
BRIEF DESCRIPTION OF THE DRAWINGSThe foregoing and other objects, features and advantages of the invention will be apparent from the more particular description of preferred aspects of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention.
Hereinafter, an electroplating apparatus according to an embodiment of the present invention will be described with reference to
Referring to
The electroplating bath 110 is filled with an electroplating solution, and electroplating is carried out in the electroplating bath 110. The electroplating bath 110 includes the anode 130, the cathode 150, and the conductor 170 therein. In the electroplating bath 110, the electroplating solution entrance 120 and the electroplating solution exit 160 are formed to allow the electroplating solution to be supplied into the electroplating bath 110 and to be exhausted outside the electroplating bath 110.
The anode 130, along with the cathode 150, serves to form a magnetic field within the electroplating bath 110. The anode 130 is installed inside the electroplating bath 110, and for example, may be installed in an area adjacent to the electroplating solution entrance 120. For example, when the electroplating apparatus 100 is of a fountain type in which the electroplating entrance 120 is located on the bottom area of the electroplating bath 110, the anode 130 may be installed in a lower portion of the electroplating bath 110. The anode 130 may be formed of any material that does not contaminate the electroplating solution during electroplating. For example, such a material may be either an insoluble material or a soluble material. When the anode 130 is made of an insoluble material, the reactive voltage of the anode 130 increases, causing an increase in the decomposition reaction of an organic additive, and the electroplating solution may be contaminated by a by-product resulting from the decomposition reaction. Thus, a device for controlling the reactive voltage of the anode 130 or preventing the decomposition reaction from affecting the electroplating solution should be additionally used. When the anode 130 is made of a soluble material, the soluble material of the anode 130 is dissolved in the electroplating solution, causing contamination to the electroplating solution. Thus, the same material as an electroplating material contained in the electroplating solution, which does not cause such a problem, may be used as the soluble material of the anode 130. In addition, when the soluble material of the anode 130 is dissolved in the electroplating solution, the surface of the anode 130 becomes uneven and a distance between the anode 130 and the layer 140 may vary from point to point of the anode 130. Due to a variation of the distance, a charge density may also vary from point to point of a neighboring area of the layer 140. Thus, when using the anode 130 made of a soluble material, the anode 130 is spaced a predetermined gap apart from the cathode 150 to minimize a variation in the charge density, caused by a variation of the distance.
The cathode 150 is spaced a predetermined gap apart from and opposite to the anode 130 inside the electroplating bath 110. For example, when the anode 130 is installed in a lower portion of the electroplating bath 110, the cathode 150 may be installed in an upper portion of the electroplating bath 110.
The layer 140 may be installed on a surface of the cathode 150 opposite to the anode 130. The layer 140 may be electrically connected to the cathode 150. For example, when the cathode 150 is installed in the form of a jig connected to an external power source, the layer 140 and the cathode 150 may be electrically connected by placing the peripheral portions of the layer 140 across the jig.
The conductor 170 is inserted between the anode 130 and the cathode 150 inside the electroplating bath 110 to change a magnetic field formed by the anode 130 and the cathode 150, thereby allowing the electroplating ions to be uniformly deposited on the layer 140.
To facilitate understanding of a function of the conductor 170 that changes the magnetic field inside the electroplating bath 110, a change in the magnetic field, caused by the conductor 170, inside the electroplating bath 110 will be described with reference to
First, a change in a magnetic field, caused by a magnetic material, will be described. As shown in (a) of
However, as shown in (b) of
As shown in (c) of
Referring to (d) of
A change in a magnetic field due to insertion of the conductor 170 can be understood as being similar to the foregoing changes in the magnetic field due to the magnetized material 20.
Hereinafter, a distribution of a magnetic field between the anode 130 and the cathode 150 in the conventional electroplating apparatus 10 will be described with reference to
With respect to a voltage drop, an electroplating pattern of the layer 14 will be described. A voltage drop in the direction from the anode 13 to the cathode 15 can be divided into five stages. A first stage is an activation overpotential stage required for dissolving a material included in the anode 13, e.g., copper, in the electroplating solution. A second stage is a concentration overpotential stage in which a concentration overpotential is generated due to dissolved ions, i.e., copper ions. A third stage is a voltage (iR) drop stage in which an iR drop occurs due to movement of positive ions and negative ions in the electroplating solution to maintain the anode 13 and the cathode 15 electrically neutral. Here, i indicates a current density and R indicates a resistance caused by movement of ions. A fourth stage is a concentration overpotential stage in the cathode 15. A fifth stage is an activation overpotential stage required for attaching electroplating ions to the surface of the layer 14 on the cathode 15.
Since ion paths curving around to the layer 14 from the anode 13 are additionally formed in the peripheral portion of the layer 14 that is electrically connected to the cathode 15, the resistance R is reduced, which is partly due to migration of ions. Since the iR drop caused by partial movement of positive ions and negative ions is reduced, an activation overpotential in the peripheral portion of the layer 14 increases. Here, since the amount of electroplating ions deposited on the layer 14 is proportional to the activation overpotential, the peripheral portion of the layer 14 is electroplated thicker than the central portion of the layer 14.
To maintain a charge density in a neighboring area of the layer 140 uniform, the conductor 170 may be installed substantially in parallel to the layer 140. For example, when the conductor 170 is flat, it may be installed in parallel to the layer 140. When the conductor 170 is a three-dimensional object having curved surfaces, it may be installed substantially in parallel to the layer 140 to minimize a dispersion of distances from points of the conductor 170 to the layer 140.
The conductor 170 may be installed in any position between the anode 130 and the layer 140 that is electrically connected to the cathode 150, but a distance between the conductor 170 and the layer 140 may be set smaller than or equal to a distance between the conductor 170 and the cathode 150.
The outer circumference of the conductor 171 may be tangent to the inner surface of the electroplating bath 110. For example, as shown in
The insulating layer 190 may be formed of any material capable of suppressing or reducing conductivity of the conductor 172. For example, the insulating layer 190 may be formed by coating the surface of the conductor 172 with polymer such as plastic or may be formed of an artificially formed oxide layer or a natural oxide layer of the conductor 172.
The conductor according to the present invention may be a circular or polygonal plate or may be symmetric with respect to its central portion to form a uniform magnetic field, but not limited thereto. In addition, to offset a charge density in a neighboring area of the peripheral portion of an electroplating material, as shown in
The conductor according to the present invention may also include at least two sections that are electrically separated from each other. By way of example, referring to
To apply different voltages to different sections of the conductor 175, an external power source PS2 may be connected to the at least one sections of the conductor 175, separately from an external power source PS1 connected to the anode 130 and the cathode 150. For example, independent external power sources PS2 may be connected to the sections of the conductor 175. Alternatively, the sections of the conductor 175 may be connected to the same external power source PS2, but voltages applied to the sections of the conductor 175 may be set to different levels by a variety of means, e.g., a resistance unit interposed between the respective sections.
In addition, a section of the conductor 175 may be connected to the external power source PS2, and another section of the conductor 175 may not be connected to the external power source PS2 or may be opened to apply different voltages to the different sections of the conductor 175. For example, as shown in
The conductor according to the present invention includes a material having conductivity. The material forming the conductor, in particular, a material of the surface of the conductor, may be the same as electroplating ions of an electroplating solution or have a reduction potential that is smaller than a reduction potential of the electroplating ions of the electroplating solution to prevent the conductor from being substitution-plated by the electroplating ions. For example, when using a copper electroplating solution, the conductor may be made of copper (Cu), silver (Ag), platinum (Pt), gold(Au), titanium (Ti), tantalum (Ta), aluminum (Al), or an alloy thereof, or only the surface of the conductor may be electroplated. Electroplating may be affected depending on whether the anode 130 is a soluble anode or an insoluble anode, but the voltage applied to the conductor is smaller than the voltage applied to the anode 130. Thus, since the decomposition reaction of an additive hardly ever occurs even when the conductor is made of an insoluble material, additional control is not required.
Hereinafter, operations of the electroplating apparatus 100 according to embodiments of the present invention and an electroplating method of electroplating the layer 140 using the electroplating apparatus 100 will be described with reference to
First, an electroplating solution, e.g., a copper electroplating solution, is supplied into the electroplating bath 110 through the electroplating solution entrance 120 using, for example, a fountain device, to fill the electroplating bath 110 with the electroplating solution. The layer 140, e.g., a semiconductor substrate on which a seed layer is formed, is attached to the cathode 150 and contacts the electroplating solution inside the electroplating bath 110. Once a voltage is applied to the electroplating bath 110 by connecting an external power source (not shown) to the anode 130 and the cathode 150, a magnetic field is formed in a direction from the anode 130 to the cathode 150. Electroplating ions, e.g., copper ions, move to the cathode 150 due to the formed magnetic field. Once the electroplate ions arrive in the conductor 170, they are re-arranged to maintain potentials uniform over the entire surface of the conductor 170. At this time, a magnetic field is formed between the conductor 170 and the cathode 150, and the electroplating ions move to the cathode 150 due to the formed magnetic field. The electroplating ions arriving in the cathode 150 are deposited on the layer 140 that is electrically connected to the cathode 150, thereby forming the electroplating layer 300 on the surface of the layer 140.
The electroplating solution supplied through the electroplating solution entrance 120 using the fountain device flows to the cathode 150 and is exhausted outside the electroplating bath 110 through the electroplating solution exit 160 installed beside the cathode 150, e.g., an overflow pipe. The electroplating solution exhausted outside the electroplating bath 110 may be supplied back to the electroplating bath 110 after undergoing a cleaning process.
Hereinafter, an electroplating apparatus according to another embodiment of the present invention will be described with reference to
In
In addition, the anode 130 according to another embodiment of the present invention may be made of a soluble or insoluble material like in the electroplating apparatus 100 according to an embodiment of the present invention. In particular, when the anode 130 is made of an insoluble material, the additive does not pass through the filter 200 or penetration of the additive is suppressed, thereby preventing the decomposition reaction of the additive in the anode 130. At this time, the surface potential of the filter 200 is sharply increased, causing a change in a charge density in a neighboring area of the cathode 150. However, since a conductor 171 is installed between the filter 200 and the cathode 150, an influence of the increase in the surface potential of the filter 200 can be reduced.
As described above, using the electroplating apparatus and the electroplating method using the same according to embodiments of the present invention, the thickness of an electroplating layer on a layer can be formed uniform, thereby improving the reliability of the electroplated layer and skipping an additional process for maintaining the thickness of the electroplating layer uniform.
While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims.
Claims
1. An electroplating apparatus comprising:
- an electroplating bath into which an electroplating solution is supplied and in which an electroplating solution entrance and an electroplating solution exit are formed;
- an anode installed inside the electroplating bath;
- a cathode which is spaced a predetermined gap apart from and opposite to the anode and on which a layer that is to be electroplated is installed; and
- a conductor installed between the anode and the cathode.
2. The electroplating apparatus of claim 1, wherein at least one hole is formed in the conductor.
3. The electroplating apparatus of claim 2, wherein the outer circumference of the conductor is tangent to the inner surface of the electroplating bath.
4. The electroplating apparatus of claim 1, wherein an insulating layer is formed on a surface of the conductor opposite to and facing the layer that is to be electroplated.
5. The electroplating apparatus of claim 4, wherein the insulating layer is selectively formed in the peripheral portion of the conductor.
6. The electroplating apparatus of claim 4, wherein the insulating layer is formed of polymer or metal oxide.
7. The electroplating apparatus of claim 1, wherein the conductor is shaped such that it is closer to the layer that is to be electroplated at its central portion than at its peripheral portions.
8. The electroplating apparatus of claim 1, wherein a distance from the conductor to the layer that is to be electroplated is smaller than or equal to a distance from the conductor to the cathode.
9. The electroplating apparatus of claim 1, wherein the anode is a soluble anode.
10. The electroplating apparatus of claim 1, wherein a filter is installed between the anode and the conductor.
11. The electroplating apparatus of claim 10, wherein the filter is a selective ion exchange filter.
12. The electroplating apparatus of claim 11, wherein the anode is an insoluble anode.
13. The electroplating apparatus of claim 1, wherein an external power source is connected to the conductor to apply a voltage to the conductor.
14. The electroplating apparatus of claim 13, wherein the voltage applied to the conductor is smaller than a voltage applied to the anode and is larger than a voltage applied to the cathode.
15. The electroplating apparatus of claim 1, wherein the conductor includes at least two sections that are electrically separated from each other.
16. The electroplating apparatus of claim 15, wherein different voltages are applied to the at least two sections.
17. The electroplating apparatus of claim 1, wherein the conductor is substantially parallel to the layer that is to be electroplated.
18. The electroplating apparatus of claim 1, wherein a reduction potential of the conductor is smaller than a reduction potential of electroplating ions in the electroplating solution.
19. The electroplating apparatus of claim 9, wherein the surface of the conductor is plated with at least one selected form the group consisting of copper (Cu), silver (Ag), platinum (Pt), gold (Au), titanium (Ti), tantalum (Ta), aluminum (Al), and an alloy thereof.
20. An electroplating method of electroplating a layer using the electroplating apparatus of any of claims 1 through 19.
Type: Application
Filed: Mar 6, 2006
Publication Date: Sep 21, 2006
Inventors: Hyo-jong Lee (Seoul), Sun-jung Kim (Yongin-si)
Application Number: 11/369,061
International Classification: C25B 9/00 (20060101); C25C 7/02 (20060101);