U.S. patent application number 11/369061 was filed with the patent office on 2006-09-21 for electroplating apparatus and electroplating method using the same.
Invention is credited to Sun-jung Kim, Hyo-jong Lee.
Application Number | 20060207875 11/369061 |
Document ID | / |
Family ID | 37009170 |
Filed Date | 2006-09-21 |
United States Patent
Application |
20060207875 |
Kind Code |
A1 |
Lee; Hyo-jong ; et
al. |
September 21, 2006 |
Electroplating apparatus and electroplating method using the
same
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.
Inventors: |
Lee; Hyo-jong; (Seoul,
KR) ; Kim; Sun-jung; (Yongin-si, KR) |
Correspondence
Address: |
MILLS & ONELLO LLP
ELEVEN BEACON STREET
SUITE 605
BOSTON
MA
02108
US
|
Family ID: |
37009170 |
Appl. No.: |
11/369061 |
Filed: |
March 6, 2006 |
Current U.S.
Class: |
204/275.1 ;
204/280; 257/E21.175 |
Current CPC
Class: |
C25D 17/10 20130101;
H01L 21/2885 20130101; C25D 17/001 20130101; C25D 7/123
20130101 |
Class at
Publication: |
204/275.1 ;
204/280 |
International
Class: |
C25B 9/00 20060101
C25B009/00; C25C 7/02 20060101 C25C007/02 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 7, 2005 |
KR |
10-2005-0018795 |
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.
Description
[0001] 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
[0002] 1. Field of the Invention
[0003] 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.
[0004] 2. Description of the Related Art
[0005] 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.
[0006] 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.
[0007] 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.
[0008] FIG. 1 is a schematic cross-sectional view of a conventional
electroplating apparatus.
[0009] 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.
[0010] 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.
[0011] 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
[0012] 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.
[0013] 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.
[0014] 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.
[0015] 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.
[0016] 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.
[0017] 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.
[0018] 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.
[0019] 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.
[0020] In one embodiment, the anode is a soluble anode.
[0021] 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.
[0022] 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.
[0023] 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.
[0024] In one embodiment, the conductor is substantially parallel
to the layer that is to be electroplated.
[0025] In one embodiment, a reduction potential of the conductor is
smaller than a reduction potential of electroplating ions in the
electroplating solution.
[0026] 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.
[0027] 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
[0028] 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.
[0029] FIG. 1 is a schematic cross-sectional view of a conventional
electroplating apparatus.
[0030] FIG. 2 is a cross-sectional view of a layer after being
electroplated using the conventional electroplating apparatus of
FIG. 1.
[0031] FIG. 3 is a schematic cross-sectional view of an
electroplating apparatus according to an embodiment of the present
invention.
[0032] FIG. 4 illustrates a change in a magnetic field due to a
magnetic material.
[0033] 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.
[0034] FIG. 6A is a plan view of a conductor included in an
electroplating apparatus according to an embodiment of the present
invention.
[0035] FIG. 6B is a cross-sectional view of the conductor of FIG.
6A, taken along line B-B'.
[0036] FIG. 7 is a schematic cross-sectional view of a modified
example of an electroplating apparatus according to an embodiment
of the present invention.
[0037] 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.
[0038] FIG. 8B is a cross-sectional view of the conductor of FIG.
8A, taken along line B-B'.
[0039] 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.
[0040] 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.
[0041] 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.
[0042] 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.
[0043] 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
[0044] Hereinafter, an electroplating apparatus according to an
embodiment of the present invention will be described with
reference to FIG. 3.
[0045] FIG. 3 is a schematic cross-sectional view of an
electroplating apparatus according to an embodiment of the present
invention.
[0046] 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.
[0047] 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.
[0048] 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.
[0049] 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.
[0050] 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.
[0051] 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.
[0052] 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.
[0053] 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.
[0054] 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.
[0055] 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.
[0056] 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.
[0057] 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.
[0058] FIGS. 5A and 5B show changes in a magnetic field when the
conductor 170 is inserted into the electroplating bath 110.
[0059] 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.
[0060] 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.
[0061] 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.
[0062] 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.
[0063] 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.
[0064] 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.
[0065] 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.
[0066] 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.
[0067] 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.
[0068] 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.
[0069] 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.
[0070] 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.
[0071] 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.
[0072] 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.
[0073] 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.
[0074] 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.
[0075] 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.
[0076] 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.
[0077] 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.
[0078] 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.
[0079] 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.
[0080] 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.
[0081] 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.
[0082] 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.
[0083] 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.
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