US20060207875A1

US20060207875A1 - Electroplating apparatus and electroplating method using the same

Info

Publication number: US20060207875A1
Application number: US11/369,061
Authority: US
Inventors: Hyo-Jong Lee; Sun-jung Kim
Original assignee: Samsung Electronics Co Ltd
Current assignee: Samsung Electronics Co Ltd
Priority date: 2005-03-07
Filing date: 2006-03-06
Publication date: 2006-09-21
Also published as: KR20060097901A; KR100755661B1

Abstract

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.

Description

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 INVENTION

1. 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.
FIG. 1 is a schematic cross-sectional view of a conventional electroplating apparatus.
Referring to FIG. 1, an electroplating apparatus 10 includes an electroplating bath 11, an electroplating solution entrance 12 through which an electroplating solution is supplied into the electroplating bath 11, an anode 13 installed inside the electroplating bath 11, a cathode 15 that is spaced by a predetermined gap from and opposite to the anode 13 and in which a layer that is to be electroplated 14 is installed, and an electroplating solution exit 16 through which an overflowing electroplating solution is exhausted outside the electroplating bath 11.
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 FIG. 2, electroplating ions of an electroplating solution cannot form an electroplating layer 30 having a uniform thickness on the surface of the layer 14. Thus, the electroplating ions are deposited thicker in a predetermined portion of the layer 14, in particular, at the peripheral portions of the layer 14, than in the central portion of the layer 14. In addition, in order to form a copper interconnect using a damascene process, a chemical mechanical polishing (CMP) process is usually performed after electroplating. A polishing speed in the CMP process is faster in the central portion of a semiconductor substrate than in the peripheral portions of the semiconductor substrate. Thus, when the CMP process is performed on a semiconductor substrate that is electroplated thicker in the peripheral portions than its central portion, the non-uniformity of the thickness of the electroplating layer 30 becomes serious.

SUMMARY OF THE INVENTION

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 DRAWINGS

The 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.
FIG. 1 is a schematic cross-sectional view of a conventional electroplating apparatus.
FIG. 2 is a cross-sectional view of a layer after being electroplated using the conventional electroplating apparatus of FIG. 1.
FIG. 3 is a schematic cross-sectional view of an electroplating apparatus according to an embodiment of the present invention.
FIG. 4 illustrates a change in a magnetic field due to a magnetic material.
FIGS. 5A and 5B illustrate changes in a magnetic field due to a conductor in an electroplating apparatus according to an embodiment of the present invention.
FIG. 6A is a plan view of a conductor included in an electroplating apparatus according to an embodiment of the present invention.
FIG. 6B is a cross-sectional view of the conductor of FIG. 6A, taken along line B-B′.
FIG. 7 is a schematic cross-sectional view of a modified example of an electroplating apparatus according to an embodiment of the present invention.
FIG. 8A is a plan view of a modified example of a conductor included in an electroplating apparatus according to an embodiment of the present invention.
FIG. 8B is a cross-sectional view of the conductor of FIG. 8A, taken along line B-B′.
FIG. 9A is a bottom perspective view of another modified example of a conductor included in an electroplating apparatus according to an embodiment of the present invention.
FIG. 9B is a schematic cross-sectional view of an electroplating apparatus including the conductor of FIG. 9A according to an embodiment of the present invention.
FIG. 10 is a schematic cross-sectional view of an electroplating apparatus including still another modified example of a conductor according to an embodiment of the present invention.
FIG. 11 is a plan view of yet another modified example of a conductor included in an electroplating apparatus according to an embodiment of the present invention.
FIG. 12 is a schematic cross-sectional view of an electroplating apparatus according to another embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Hereinafter, an electroplating apparatus according to an embodiment of the present invention will be described with reference to FIG. 3.
FIG. 3 is a schematic cross-sectional view of an electroplating apparatus according to an embodiment of the present invention.
Referring to FIG. 3, an electroplating apparatus 100 includes an electroplating bath 110, an electroplating solution entrance 120, an anode 130, a cathode 150 on which a layer 140 that is to be electroplated is installed, an electroplating solution exit 160, and a conductor 170 that is installed between the anode 130 and the cathode 150.
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 FIG. 4 and FIGS. 5A and 5B.
First, a change in a magnetic field, caused by a magnetic material, will be described. As shown in (a) of FIG. 4, when N and S poles are opposite to and facing each other, a northbound magnetic field, that is, a magnetic field inducing from the S pole to the N pole, is formed. Magnetic force lines starting from the central portion of the S pole go to the N pole perpendicularly to the N pole, but magnetic force lines curving around to the N pole are additionally formed in the peripheral portion of the S pole. As a result, a magnetic flux density in the peripheral portions of the N pole increases due to the magnetic force lines coming perpendicularly to and around to the N pole.
However, as shown in (b) of FIG. 4, if a distance between the N pole and the S pole is reduced, the curvature of a magnetic force line that starts from the peripheral portion of the S pole and curves around to the N pole is reduced. Thus, the number of magnetic force lines curving around to the N pole is reduced and a magnetic flux density in the peripheral portions of the N pole is reduced when compared to (a) of FIG. 4.
As shown in (c) of FIG. 4, if a magnetized material 20 is inserted between the N pole and the S pole, a surface of the magnetized material 20 opposite to the S pole serves as another N pole and accepts magnetic force lines starting from the S pole and a surface of the magnetized material 20 opposite to the N pole serves as another S pole and radiates magnetic force lines. At this time, propagation paths of the magnetic force lines radiated from the magnetized material 20 is determined by a distance between the magnetized material 20 and the N pole, regardless of a propagation path of the magnetic force lines accepted by the magnetized material 20 from the S pole. Thus, a magnetic field formed between the magnetized material 20 and the N pole is similar to that formed between the N pole and the S pole which are closer to each other, like in (b) of FIG. 4. As a result, a magnetic flux density in a neighboring area of the peripheral portion of the N pole is reduced when compared to (a) of FIG. 4.
Referring to (d) of FIG. 4 showing propagation paths of magnetic force lines when the magnetized material 20 is moved closer to the N pole, as the magnetized material 20 is moved closer to the N pole, magnetic force lines radiated from the peripheral portions of the magnetized material 20 go to the N pole nearly perpendicularly to the N pole and the number of magnetic force lines curving around to the N pole is reduced. As a result, a magnetic flux density in the peripheral portion of the N pole becomes the same as or similar to that in the central portion of the N pole.
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.
FIGS. 5A and 5B show changes in a magnetic field when the conductor 170 is inserted into the electroplating bath 110.
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 FIG. 1. In FIG. 1, as the electroplating ions included in the electroplating solution move from the anode 13 to the cathode 15, a voltage drop occurs. At this time, ion paths starting from the peripheral portion of the anode 13 and curving around to the layer 14 mounted on the cathode 15 are additionally formed, resulting in an increase of a charge density in a neighboring area of the peripheral portion of the layer 14. Thus, the electroplating ions moving along the additionally formed ion paths are deposited in the peripheral portion of the layer 14, and the peripheral portion of the layer 14 is electroplated thicker than the central portion of the layer 14.
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.
FIG. 5A shows a change in a magnetic field when the conductor 170. of the invention is inserted between the anode 130 and the cathode 150. Once the conductor 170 is inserted between the anode 130 and the cathode 150, ion paths movement from the anode 130 to the conductor 170 are formed. At this time, since all the potential differences in the conductor 170 should be 0V, potentials of portions of the electroplating solution contacting the conductor 170 will have the same size. That is, potentials in the conductor 170 and potentials in the portion of the electroplating solution contacting the conductor 170 are uniform regardless of a distribution of the ion paths starting from the anode 130, and the conductor 170 can serve as an anode with respect to the cathode 150. At this time, a distribution of ion paths starting from the conductor 170 is determined by a distance between the conductor 170 and the cathode 150 regardless of the distribution of the ion paths starting from the anode 130, like the magnetic force lines in (b) of FIG. 4. Thus, a magnetic field formed between the conductor 170 and the electroplating subject 140 that is electrically connected to the cathode 150 is similar to that formed between the anode 130 and the cathode 150 whose distance apart is reduced. As a result, a charge density in a neighboring area of the peripheral portion of the layer 140 is reduced when compared to FIG. 1. That is, since the number of additionally formed ion paths is reduced when compared to FIG. 1, electroplating ions propagating along the additionally formed ion paths are also reduced. Thus, the non-uniformity of the thickness of an electroplating layer 300, caused by excessive deposition of the electroplating ions in the peripheral portion of the layer 140, is reduced.
FIG. 5B shows a change in a magnetic field when the conductor 170 is moved closer to the cathode 150. As a distance between the conductor 170 and the layer 140 that is electrically connected to the cathode 150 decreases, the number of additionally formed ion paths curving around to the layer 140 from the peripheral portion of the conductor 170 is reduced. As a result, a charge density in a neighboring area of the peripheral portion of the layer 140 becomes the same as or similar to that in a neighboring area of the central portion of the layer 140.
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.
FIG. 6A is a plan view of a conductor included in an electroplating apparatus according to an embodiment of the present invention, and FIG. 6B is a cross-sectional view of the conductor of FIG. 6A, taken along line B-B′. As shown in FIGS. 6A and 6B, a conductor 171 may include at least one hole 180 through which an electroplating solution can flow. The shape of the hole 180 may be circular or polygonal, or other shape. The number and the size of the hole 180 may be determined by possible variables in electroplating, such as the flux of the electroplating solution supplied from the electroplating solution entrance 120, a movement speed of electroplating ions, and the composition of an additive. The hole 180 may be disposed symmetrically with respect to, for example, but not limited thereto, the central portion of the conductor 171. In addition, the holes 180 may be disposed in such a manner that the conductor 171 can serve as a diffuser.
The outer circumference of the conductor 171 may be tangent to the inner surface of the electroplating bath 110. For example, as shown in FIG. 7, when the outer circumference of the conductor 171 is entirely tangent to the inner surface of the electroplating bath 110, additionally formed ion paths curving around to the layer 140 from the anode 130 can be blocked. In this case, since the flow of the electroplating solution and movement of the electroplating ions may be restricted, the conductor 171 can include the at least one hole 180.
FIG. 8A is a plan view of a modified example of a conductor included in an electroplating apparatus according to an embodiment of the present invention, and FIG. 8B is a cross-sectional view of the conductor of FIG. 8A, taken along line B-B′. As shown in FIGS. 8A and 8B, an insulating layer 190 may be formed on the entire surface of a conductor 172 or on a portion thereof. When the insulating layer 190 is formed on a portion of the conductor 172 opposite to the layer 140, a magnetic field and an ion path are not formed. in the portion on which the insulating layer 190 is formed. As a result, ion paths and a charge density in a neighboring area of the portion of the layer 140 opposite to the insulating layer 190 can be reduced. Thus, once the insulating layer 190 is formed in a portion of the peripheral portion of the conductor 172 opposite to a neighboring area of the surface of the layer 140 having a high charge density, e.g., a neighboring area of the peripheral portion of the layer 140 in which a charge density is increased by additionally formed ion paths curving around to the layer 140, a charge density reduced by the insulating layer 190 can be offset by the charge density increased by the additionally formed ion paths. To this end, the thickness, the width, and the area of the insulating layer 190 may be determined properly. In addition, it is experimentally determined which portion of a neighboring area of the layer 140 has a high charge density, and the insulating layer 190 is selectively formed on a portion of the conductor 172 opposite to the determined portion. In this manner, the charge density in a neighboring area of the surface of the layer 140 can be maintained uniform.
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 FIGS. 9A and 9B, a conductor 173 is shaped such that it is closer to the layer 140 at its central portion than at its peripheral portion. That is, since an iR drop increases due to movement of ions as a distance from the conductor 173 to the layer 140 increases, a charge density in a neighboring area of the surface of the layer 140 may be reduced. Thus, by offsetting such a reduction by a charge density increased by additionally formed ion paths, the non-uniformity of charge densities can be reduced. For example, the conductor 173 may be shaped of, but not limited to, a hollow cone, as shown in FIGS. 9A and 9B.
FIG. 10 is a schematic cross-sectional view of an electroplating apparatus including still another modified example of a conductor according to an embodiment of the present invention. Referring to FIG. 10, a voltage of a conductor 174 may be determined by voltages applied to the anode 130 and the cathode 150 and the position of the conductor 174. A voltage may be applied to the conductor 174 from an external power source connected to the conductor 174, as shown in FIG. 10, if necessary. In this case, to facilitate smooth movement of the electroplating ions, the voltage applied to the conductor 174 may be set smaller than the voltage applied to the anode 130 and larger than the voltage applied to the cathode 150.
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 FIG. 11, a predetermined portion of a conductor 175 may be spatially divided into two sections. Alternatively, an insulating material 195 may be provided to electrically separate the conductor 175 into two sections. In particular, the conductor 175 may be separated into an inner section and an outer section.
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 FIG. 11, when the conductor 175 is separated into the inner section and the outer section, a charge density in a neighboring area of the peripheral portion of the layer 140 can be controlled by lowering a voltage applied to the outer section than a voltage applied to the inner section.
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 FIG. 3.
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 FIG. 12. For convenience of description, elements that are the same as or similar to those of FIG. 3 are denoted by the same reference numerals, and description of these elements will not be repeated. An electroplating apparatus 101 according to another embodiment of the present invention has a structure and operations that are substantially the same as the electroplating apparatus 100 of FIG. 3 except for a filter 200 shown in FIG. 12.
In FIG. 12, the filter 200 filters impurities of the electroplating solution flowing from the anode 130 to the conductor 170. As shown in FIG. 12, the filter 200 may be installed between the anode 130 and the conductor 170. For example, the filter 200 may be tangent to the inner surface of the electroplating bath 110 or may be installed near to the surface of the anode 130. Various types of filters may be used as the filter 200 as occasion demands. For example, a selective ion exchange filter through which ions pass while an additive is not allowed to pass therethrough may be used as the filter 200 to prevent the decomposition reaction of the additive in the anode 130. The filter 200 may be installed to surround the surface of the anode 130.
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.