U.S. patent application number 13/769585 was filed with the patent office on 2014-08-21 for adjustable current shield for electroplating processes.
This patent application is currently assigned to GLOBALFOUNDRIES INC.. The applicant listed for this patent is GLOBALFOUNDRIES INC.. Invention is credited to Gunther Wilhelm Sandmann, Christian Schroiff, Kerstin Siury.
Application Number | 20140231245 13/769585 |
Document ID | / |
Family ID | 51264089 |
Filed Date | 2014-08-21 |
United States Patent
Application |
20140231245 |
Kind Code |
A1 |
Sandmann; Gunther Wilhelm ;
et al. |
August 21, 2014 |
ADJUSTABLE CURRENT SHIELD FOR ELECTROPLATING PROCESSES
Abstract
One illustrative plating apparatus disclosed herein includes a
substrate holder that is adapted to receive a substrate, an anode
and an adjustable current shield positioned between the substrate
holder and the anode. In this illustrative embodiment, the
adjustable current shield includes a stationary member, a moveable
member that is adapted to be moved relative to the stationary
member and a plurality of current shield members that are
operatively coupled to either the stationary member or the moveable
member, wherein each of the current shield members is rotatably
pinned to either the stationary member or the moveable member and
wherein each of the current shield members is adapted to rotate
when there is relative movement between the moveable member and the
stationary member.
Inventors: |
Sandmann; Gunther Wilhelm;
(Dresden, DE) ; Siury; Kerstin; (Dresden, DE)
; Schroiff; Christian; (Dresden, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
GLOBALFOUNDRIES INC. |
Grand Cayman |
|
KY |
|
|
Assignee: |
GLOBALFOUNDRIES INC.
Grand Cayman
KY
|
Family ID: |
51264089 |
Appl. No.: |
13/769585 |
Filed: |
February 18, 2013 |
Current U.S.
Class: |
204/230.3 |
Current CPC
Class: |
C25D 17/008 20130101;
C25D 7/12 20130101; C25D 17/001 20130101 |
Class at
Publication: |
204/230.3 |
International
Class: |
C25D 17/00 20060101
C25D017/00; C25D 7/12 20060101 C25D007/12 |
Claims
1. A plating apparatus, comprising: a substrate holder that is
adapted to receive a substrate; an anode; and an adjustable current
shield positioned between said substrate holder and said anode,
wherein said adjustable current shield comprises: a stationary
member; a moveable member that is adapted to be moved relative to
said stationary member; and a plurality of current shield members
operatively coupled to said stationary member and said moveable
member, wherein each of said plurality of current shield members is
rotatably pinned to one of said stationary member or said moveable
member and wherein each of said current shield members is adapted
to rotate when there is relative movement between said moveable
member and said stationary member.
2. The apparatus of claim 1, wherein said substrate holder is
located vertically above said anode and said adjustable current
shield is located vertically above said anode.
3. The apparatus of claim 1, wherein each of said substrate holder,
said anode and said adjustable current shield are oriented
substantially vertically, and wherein said adjustable current
shield is located laterally between said substrate holder and said
anode.
4. The apparatus of claim 1, wherein said stationary and moveable
members each have a ring configuration.
5. The apparatus of claim 1, further comprising means for moving
said moveable member relative to said stationary member.
6. The apparatus of claim 1, further comprising a plurality of gear
teeth that are operatively coupled to said moveable member.
7. The apparatus of claim 1, further comprising a lever that is
operatively coupled to said moveable member.
8. The apparatus of claim 1, wherein, when said adjustable current
shield is in a fully closed position, a portion of each of said
plurality of current shielding members overlaps a portion of an
adjacent current shielding member.
9. The apparatus of claim 1, wherein, when said adjustable current
shield is in a fully closed position, a portion of each of said
plurality of current shielding members overlaps and contacts a
portion of an adjacent current shielding member.
10. A plating apparatus, comprising: a substrate holder that is
adapted to receive a substrate; an anode; and an adjustable current
shield positioned between said substrate holder and said anode,
wherein said adjustable current shield comprises: a stationary
member; a moveable member that is adapted to be moved relative to
said stationary member; and a plurality of current shield members
operatively coupled to said stationary member and said moveable
member, wherein each of said plurality of current shield members is
rotatably pinned to one of said stationary member or said moveable
member and wherein a portion of each of said current shield members
is adapted to be moved inward or outward when there is relative
movement between said moveable member and said stationary member
depending upon the direction of such relative movement.
11. The apparatus of claim 10, wherein, when said adjustable
current shield is in a fully closed position, a portion of each of
said plurality of current shielding members overlaps a portion of
an adjacent current shielding member.
12. The apparatus of claim 11, wherein, when said adjustable
current shield is in a fully closed position, a portion of each of
said plurality of current shielding members overlaps and contacts a
portion of an adjacent current shielding member.
13. The apparatus of claim 10, wherein said substrate holder is
located vertically above said anode and said adjustable current
shield is located vertically above said anode.
14. The apparatus of claim 10, wherein each of said substrate
holder, said anode and said adjustable current shield are oriented
substantially vertically, and wherein said adjustable current
shield is located laterally between said substrate holder and said
anode.
15. A plating apparatus, comprising: a substrate holder that is
adapted to receive a substrate; an anode; and an adjustable current
shield positioned between said substrate holder and said anode,
wherein said adjustable current shield comprises: a stationary
ring; a moveable ring that is adapted to be moved relative to said
stationary ring; and a plurality of current shield members
operatively coupled to said stationary ring and said moveable ring,
wherein each of said plurality of current shield members is
rotatably pinned to one of said stationary ring or said moveable
ring and wherein each of said current shield members is adapted to
rotate when there is relative movement between said moveable ring
and said stationary ring, thereby moving a portion of each of said
current shield members radially inward or outward depending upon
the direction of such relative movement.
16. The apparatus of claim 15, wherein said substrate holder is
positioned above said anode and said adjustable current shield is
positioned above said anode.
17. The apparatus of claim 15, further comprising means for moving
said moveable member relative to said stationary member.
18. The apparatus of claim 15, wherein, when said adjustable
current shield is in a fully closed position, a portion of each of
said plurality of current shielding members overlaps a portion of
an adjacent current shielding member.
19. The apparatus of claim 15, wherein, when said adjustable
current shield is in a fully closed position, a portion of each of
said plurality of current shielding members overlaps and contacts a
portion of an adjacent current shielding member.
20. The apparatus of claim 15, wherein said substrate holder is
located vertically above said anode and said adjustable current
shield is located vertically above said anode.
21. The apparatus of claim 15, wherein each of said substrate
holder, said anode and said adjustable current shield are oriented
substantially vertically, and wherein said adjustable current
shield is located laterally between said substrate holder and said
anode.
22. A plating apparatus, comprising: a substrate holder that is
adapted to receive a substrate; an anode; and an adjustable current
shield positioned between said substrate holder and said anode,
wherein said adjustable current shield comprises: a stationary
ring; a moveable ring that is adapted to be moved relative to said
stationary ring; and a plurality of current shield members
operatively coupled to said stationary ring and said moveable ring,
wherein each of said plurality of current shield members is
rotatably pinned to said stationary ring and wherein each of said
current shield members is adapted to rotate when said moveable ring
is moved relative to said stationary ring, thereby moving a portion
of each of said current shield members radially inward or outward
depending upon the direction of movement of said moveable ring
relative to said stationary ring.
23. The apparatus of claim 22, wherein, when said adjustable
current shield is in a fully closed position, a portion of each of
said plurality of current shielding members overlaps a portion of
an adjacent current shielding member.
24. The apparatus of claim 23, wherein, when said adjustable
current shield is in a fully closed position, a portion of each of
said plurality of current shielding members overlaps and contacts a
portion of an adjacent current shielding member.
25. The apparatus of claim 22, wherein said substrate holder is
located vertically above said anode and said adjustable current
shield is located vertically above said anode.
26. The apparatus of claim 22, wherein each of said substrate
holder, said anode and said adjustable current shield are oriented
substantially vertically, and wherein said adjustable current
shield is located laterally between said substrate holder and said
anode.
27. A plating apparatus, comprising: a substrate holder that is
adapted to receive a substrate; an anode; and an adjustable current
shield positioned between said substrate holder and said anode,
wherein said adjustable current shield comprises a plurality of
segmented shielding members that may be moved so as to effectively
change a size of an opening of said adjustable current shield.
28. The apparatus of claim 27, wherein, when said adjustable
current shield is in a fully closed position, a portion of each of
said plurality of segmented shielding members overlaps and contacts
a portion of an adjacent segmented shielding member.
29. The apparatus of claim 27, wherein a portion of each of said
plurality of segmented shielding members is adapted to move
radially inward or outward when moved.
30. The apparatus of claim 27, wherein said size is an effective
diameter of said opening.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] Generally, the present disclosure relates to the manufacture
of sophisticated semiconductor devices, and, more specifically, to
an adjustable current shield that may be employed in electroplating
processes that are performed to form a conductive metal
material.
[0003] 2. Description of the Related Art
[0004] The manufacture of semiconductor devices often requires the
formation of electrical conductors on semiconductor wafers. For
example, electrically conductive leads on the wafer are often
formed by electroplating (depositing) an electrically conductive
layer, such as copper, on the wafer and into patterned trenches.
There are two general types of electroplating equipment: fountain
plating equipment and vertical plating equipment. Both have
relative advantages in some applications. Although the orientation
of the surface of the wafer to be plated is different in the two
different processes--horizontal in fountain plating equipment and
vertical in vertical plating equipment--the process operations are
very similar.
[0005] In general, electroplating involves making electrical
contact with a so-called conductive "seed" layer that is formed on
the wafer surface upon which the electrically conductive layer,
e.g., copper, is to be deposited. Current is then passed through a
plating solution (i.e., a solution containing ions of the element
being deposited, for example, a solution containing Cu.sup.++)
between an anode and the conductive seed layer on the wafer plating
surface that acts as a cathode. The seed layer carries the
electrical plating current from the edge of the wafer, where
electrical contact is made, to the center of the wafer, including
through embedded structures, trenches and vias. This causes an
electrochemical reaction on the wafer plating surface which results
in the deposition of the electrically conductive layer. Ideally,
the final layer of material that is electrodeposited on the seed
layer should completely fill the embedded structures, and it should
have a specific thickness profile across the surface of the wafer.
Generally, in electroplating processes, the thickness profile of
the deposited metal should be controlled as much as possible.
[0006] In an attempt to minimize variations in the deposited
material, it is important that the electrically conductive seed
layer have a uniform thickness over the wafer plating surface.
However, even with highly uniform seed layers, conventional
electroplating processes produce a non-uniform deposition due to
the so-called "edge effect" associated with such plating processes.
In general, the edge effect refers to the tendency of the deposited
electrically conductive layer to be thicker near the wafer edge
than at the wafer center, i.e., an "edge-thick" profile. This
edge-thick profile in the final layer is caused by, among other
things, a decrease in current flow through the seed layer in the
middle region of the wafer as compared to the current flowing near
the edge region of the wafer. That is, since the conductive seed
layer is contacted at the periphery of the wafer and the magnitude
of the current flowing through the seed layer drops as one moves
from the edge of the wafer toward the center of the wafer, there is
less conductive material, e.g., copper, plated at the center of the
wafer as compared to the edge region of the wafer.
[0007] The formation of such edge-thick layers of material makes
subsequent processing more difficult. For example, such edge-thick
layers of material make subsequent chemical mechanical polishing
operations more difficult to perform, i.e., it makes it more
difficult to obtain a substantially planar surface after the
polishing process has been performed. As another example, various
processing parameters of the electroplating process may be adjusted
in an attempt to combat this tendency to produce conductive
material layers with an edge-thick profile. However, such
processing changes may result in producing a conductive layer that
is too thin in the middle area of the wafer, thereby leading to the
formation of defective wiring features that are not as thick as
intended by the design process. Such defective wiring features may
reduce the useful life of an integrated circuit product and, in a
worst-case scenario, may lead to complete device failure.
[0008] One technique that has been employed in an effort to avoid
or reduce the magnitude of the production of such edge-thick
conductive layers involves the use of so-called current shields.
Current shields are typically positioned between the anode and the
wafer and they act to reduce the electrical field at the edge
region of the wafer, which reduces the amount of the conductive
material formed on the edge region of the wafer. The current
shields may be made of a variety of materials, such as
non-conductive, inert materials, like plastic. The current shields
may be fixed or adjustable in terms of their area that is
positioned between the anode and the wafer. In one example, a fixed
current shield has a radial width of about 20-30 mm and a thickness
on the order of about 2-3 mm. Such fixed current shields are
typically sized and configured for a particular process flow and/or
device by a trial and error process. Once acceptable results are
achieved, the specifically designed current shield is used in
production operations. Unfortunately, when there is a change in the
design of the wafer or the process conditions, the existing current
shield may not produce acceptable results. In that case, a new
design of a current shield may need to be determined (by trial and
error) and then put into production service. Alternatively,
processing engineers may try to "make-do" with the less than
desirable original current shield, which may lead to the production
of conductive layers that do not have the desired or target
thickness profile and the problems associated with such layers as
discussed above.
[0009] The present disclosure is directed to a novel adjustable
current shield that may solve or reduce one or more of the problems
identified above.
SUMMARY OF THE INVENTION
[0010] The following presents a simplified summary of the invention
in order to provide a basic understanding of some aspects of the
invention. This summary is not an exhaustive overview of the
invention. It is not intended to identify key or critical elements
of the invention or to delineate the scope of the invention. Its
sole purpose is to present some concepts in a simplified form as a
prelude to the more detailed description that is discussed
later.
[0011] Generally, the present disclosure is directed to a plating
tool that includes an adjustable current shield that may be
employed in electroplating process operations. One illustrative
plating apparatus disclosed herein includes a substrate holder that
is adapted to receive a substrate, an anode and an adjustable
current shield positioned between the substrate holder and the
anode. In this illustrative embodiment, the adjustable current
shield includes a stationary member, a moveable member that is
adapted to be moved relative to the stationary member and a
plurality of current shield members that are operatively coupled to
either the stationary member or the moveable member, wherein each
of the current shield members is rotatably pinned to either the
stationary member or the moveable member and wherein each of the
current shield members is adapted to rotate when there is relative
movement between the moveable member and the stationary member.
[0012] Another illustrative plating apparatus disclosed herein
includes a substrate holder that is adapted to receive a substrate,
an anode and an adjustable current shield positioned between the
substrate holder and the anode. In this illustrative embodiment,
the adjustable current shield includes a stationary ring, a
moveable ring that is adapted to be moved relative to the
stationary ring and a plurality of current shield members
operatively coupled to the stationary ring and the moveable ring,
wherein each of the plurality of current shield members is
rotatably pinned to either the stationary ring or the moveable ring
and wherein each of the current shield members is adapted to rotate
when there is relative movement between the moveable ring and the
stationary ring, thereby moving a portion of each of the current
shield members radially inward or outward depending upon the
direction of the relative movement.
[0013] Yet another illustrative plating apparatus disclosed herein
includes a substrate holder that is adapted to receive a substrate,
an anode and an adjustable current shield positioned between the
substrate holder and the anode, wherein the adjustable current
shield includes a plurality of segmented shielding members that may
be moved so as to effectively change a size of an opening of the
adjustable current shield.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The disclosure may be understood by reference to the
following description taken in conjunction with the accompanying
drawings, in which like reference numerals identify like elements,
and in which:
[0015] FIGS. 1 and 1A are simplistic and schematic views of various
illustrative embodiments of an electroplating apparatus having an
adjustable current shield as disclosed herein;
[0016] FIGS. 2A-2E depict various illustrative aspects of one
illustrative embodiment of an adjustable current shield as
disclosed herein; and
[0017] FIGS. 3A-3B depict one illustrative embodiment of a
plurality of current shielding members that may be employed in the
illustrative adjustable current shield disclosed herein.
[0018] While the subject matter disclosed herein is susceptible to
various modifications and alternative forms, specific embodiments
thereof have been shown by way of example in the drawings and are
herein described in detail. It should be understood, however, that
the description herein of specific embodiments is not intended to
limit the invention to the particular forms disclosed, but on the
contrary, the intention is to cover all modifications, equivalents,
and alternatives falling within the spirit and scope of the
invention as defined by the appended claims.
DETAILED DESCRIPTION
[0019] Various illustrative embodiments of the invention are
described below. In the interest of clarity, not all features of an
actual implementation are described in this specification. It will
of course be appreciated that in the development of any such actual
embodiment, numerous implementation-specific decisions must be made
to achieve the developers' specific goals, such as compliance with
system-related and business-related constraints, which will vary
from one implementation to another. Moreover, it will be
appreciated that such a development effort might be complex and
time-consuming, but would nevertheless be a routine undertaking for
those of ordinary skill in the art having the benefit of this
disclosure.
[0020] The present subject matter will now be described with
reference to the attached figures. Various structures, systems and
devices are schematically depicted in the drawings for purposes of
explanation only and so as to not obscure the present disclosure
with details that are well known to those skilled in the art.
Nevertheless, the attached drawings are included to describe and
explain illustrative examples of the present disclosure. The words
and phrases used herein should be understood and interpreted to
have a meaning consistent with the understanding of those words and
phrases by those skilled in the relevant art. No special definition
of a term or phrase, i.e., a definition that is different from the
ordinary and customary meaning as understood by those skilled in
the art, is intended to be implied by consistent usage of the term
or phrase herein. To the extent that a term or phrase is intended
to have a special meaning, i.e., a meaning other than that
understood by skilled artisans, such a special definition will be
expressly set forth in the specification in a definitional manner
that directly and unequivocally provides the special definition for
the term or phrase.
[0021] The present disclosure is directed to an electroplating tool
that includes an adjustable current shield that may be employed in
electroplating process operations. As will be readily apparent to
those skilled in the art upon a complete reading of the present
application, the methods and devices disclosed herein may be
employed in a variety of different manufacturing applications and
techniques, e.g., standard plating operations to form a uniform
conductive layer, patterned plating applications, etc. Moreover,
the methods and devices disclosed herein may also be employed in
manufacturing a variety of different devices, including, but not
limited to, logic devices, memory devices, etc. With reference to
the attached figures, various illustrative embodiments of the
methods and devices disclosed herein will now be described in more
detail.
[0022] FIG. 1 depicts, in schematic and simplistic form, a
fountain-type electroplating apparatus 10 in accordance with one
illustrative embodiment disclosed herein, wherein the adjustable
current shield 100 disclosed herein is oriented substantially
horizontal within the apparatus 10 and located vertically above the
anode. However, as will be recognized by those skilled in the art,
the adjustable current shield disclosed herein may also be employed
in vertical-type plating tools, wherein the adjustable current
shield 100 disclosed herein is oriented substantially vertical in
such a vertical plating tool, as schematically depicted in FIG. 1A.
The disclosed electroplating apparatus 10 contains a main plating
bath container 12 that contains a conventional electroplating bath
14 comprised of an electrolytic plating fluid. A cylindrical
container wall 16 determines the height 18 of the plating bath 14.
The electroplating apparatus 10 further includes a substrate/wafer
holder 20 and a schematically depicted anode 30. The substrate
holder 20 is adapted to hold an integrated circuit substrate 22. A
motor (not shown) drives a spindle 26 that rotates the substrate
holder 20 and substrate 22 around a central axis during plating
operations. The substrate 22 has a substrate backside 22B and a
substrate front plating surface 22F. The front plating surface 22F
typically has a conductive seed layer (not shown) formed thereon to
facilitate plating operations, e.g., a conductive copper seed layer
or a tantalum or titanium nitride barrier layer. The shape and
configuration of the substrate holder 20 may vary depending upon
the type of plating apparatus employed. In some cases, the
substrate holder 20 may include a compliant O-ring seal (not shown)
and a set of electrical contacts (not shown) for electrically
connecting the negative terminal of a power source 24 to the
conductive seed layer (not shown) at the edge of the substrate 20.
The positive terminal of the power source 24 is conductively
coupled to the anode 30. The substrate 22 may be comprised of any
semiconducting material, such as silicon, silicon/germanium, ruby,
quartz, sapphire and gallium arsenide. The anode 30 is illustrative
in nature in that it may be comprised of multiple parts arranged in
a variety of configurations and it may have multiple openings.
[0023] Also shown in FIG. 1, the electroplating apparatus also
includes a schematically depicted adjustable current shield 100 as
disclosed herein. In general, the adjustable current shield 100 is
disposed between the anode 30 and the substrate 22 or substrate
holder 20. The adjustable current shield 100 may be secured to the
container wall 16 by any desired technique, e.g., clips, lugs,
bolted connections, etc. The periphery of the adjustable current
shield 100 need not be sealed against the inner surface of the
container wall 16. The adjustable current shield 100 may be
positioned at any desired distance from the substrate 22, and this
distance may vary depending upon the particular application. For
example, the position of the adjustable current shield 100 may be
determined, at least in part, based upon the desired thickness
profile of the electrically conductive layer to be deposited on the
substrate 22. In general, the closer the adjustable current shield
100 is positioned to the substrate 22, the greater the influence
the adjustable current shield 100 has on the resulting thickness
profile of the electrically conductive layer to be deposited on the
wafer 22. The adjustable current shield 100 as well as the
container wall 16 may be comprised of materials that resist attack
by the electrolytic plating fluid in the bath 14. These structures
may be comprised of a dielectric material or a composite material
that includes a dielectric coating to prevent electroplating of
metal onto these structures during the electroplating process.
These structures may also be made of various plastics, such as
polypropylene, polyethylene and fluoro-polymers, especially
polyvinylidine fluoride, or ceramics such as alumina or zirconia.
The apparatus 10 depicted in FIG. 1 is a simplistic and schematic
depiction of an illustrative fountain-type plating tool, the basic
construction of which is well known to those skilled in the art. As
noted earlier, the adjustable current shield 100 disclosed herein
may be employed in so-called vertical plating tools as well, the
basic construction of which is also well known to those skilled in
the art. FIG. 1A is a simplistic and schematic depiction of some of
the major components of such a vertical plating apparatus. More
specifically, as shown in FIG. 1A, in some embodiments, the
substrate holder 20, substrate 22, adjustable current shield 100
and the anode 30 may all be oriented substantially vertically,
wherein the adjustable current shield 100 is located laterally
between the substrate holder 20 and the anode 30.
[0024] The illustrative electroplating bath 14 is a conventional
bath that typically contains the metal to be plated, together with
associated anions, in an acidic solution. Copper electroplating is
usually performed using a solution of CuSO.sub.4 dissolved in an
aqueous solution of sulfuric acid. In addition to these major
constituents of the electroplating bath 14, it is common for the
bath 14 to contain several additives, which are any type of
compound added to the plating bath 14 to change the plating
behavior. Three types of electroplating bath additives are in
common use, subject to design choice by those skilled in the art:
suppressors, accelerators and levelers. Suppressor additives retard
the plating reaction and increase the polarization of the cell.
Accelerator additives are normally catalysts that accelerate the
plating reaction under suppression influence or control. Levelers
behave like suppressors, but are highly electrochemically active
(i.e., are more easily electrochemically transformed), losing their
suppressive character upon electrochemical reaction. Levelers also
tend to accelerate plating on depressed regions of the surface
undergoing plating, thus, tending to level the plated surface. Of
course, as will be appreciated by those skilled in the art after a
complete reading of the present application, the inventions
disclosed herein are not limited to use with any type of plating
bath, as the inventions disclosed herein may be employed with a
variety of different bath chemistries.
[0025] General aspects of a typical plating process will now be
described. As will be appreciated by those skilled in the art, the
container wall 16 of the plating apparatus 10 functions as an
overflow weir. During typical operations, the substrate holder 20
is partially submerged in the plating bath 14 such that the
electrolytic plating fluid wets plating surface 22F of the
substrate 22 but does not wet the upper portions of substrate
holder 20. In general, the plating fluid overflows the
container/weir 16, as indicated by the arrows 32, into the space
between the main plating bath container 12 and container wall 16.
Thereafter, as indicated by the arrows 34, the plating fluid flows
to the inlet 36 of a circulating pump 38. During operations, the
circulating pump 38 typically continuously circulates plating fluid
to the plating bath 14, as indicated by the arrow 26. In this
manner, the bath height 18 may be maintained during plating
operations. Generally, the plating solution flows upwards through
openings (not shown) in the anode 30 and around the anode 30 toward
the substrate 22. During use, the power supply 24 biases the wafer
22 to have a negative potential relative to the anode 30, causing
an electrical current to flow from the anode 30 to the substrate
22. This also causes an electric current flux from the anode 30 to
the substrate 22, wherein the electric current flux is defined as
the number of lines of forces (field lines) through an area. This
causes an electrochemical reaction (e.g., Cu.sup.+++2e.sup.-=Cu)
which results in the deposition of the electrically conductive
layer (e.g., copper) on the on the front face 22F of the substrate
22. The ion concentration of the desired metal in the plating
solution may be replenished during the plating cycle by dissolving
a metal of the anode 30, e.g., copper, in the plating solution.
[0026] FIGS. 2A-2E depict various aspects of the illustrative
example of an adjustable current shield 100 as disclosed herein.
FIGS. 3A-3B depict one illustrative example of a plurality of
current shielding members that may be employed in the illustrative
adjustable current shield 100 disclosed herein. In general, in the
disclosed example, the adjustable current shield 100 is comprised
of a stationary ring 102 (see FIGS. 2A-2B), an adjustable or
moveable ring 112 (see FIGS. 2C-2D) and a plurality of current
shielding members 130 (see FIGS. 3A-3B). In operation, as described
more fully below, the moveable ring 112 is adapted to be moved
relative to the stationary ring 102. This relative movement of the
moveable ring 112 causes a portion (136) of each of the current
shielding members 130 to move radially inward, thereby effectively
changing the "size" of the shielding members 130 and their
shielding capability.
[0027] FIGS. 2A-2B, depict various aspects of one illustrative
example of the stationary ring 102. In the depicted example, the
stationary ring 102 has an inner surface 104, an outer surface 106
and a ledge 110 that defines a recess 111 that is adapted to
receive the moveable ring 112. A plurality of pins 108 are attached
to the stationary ring 102. The stationary ring 102 may be secured
to the container wall 16 of the plating apparatus 10 by any desired
technique, e.g., clips, lugs, bolted connections, etc. (not shown).
The outer surface 106 of the stationary ring 102 need not be sealed
against the inner surface of the container wall 16. The physical
size of the stationary ring 102 may vary depending upon a variety
of factors, including the size of the plating apparatus 10 in which
it will be employed and the mechanical loading it is anticipated to
experience in operation. In one illustrative example, the
stationary ring 102 may have a radial thickness (outside diameter
minus inside diameter) of about 5-50 mm, and an overall thickness
of about 5-25 mm. The stationary ring 102 may be made of a
dielectric material or a composite material that includes a
dielectric coating various plastics, such as polypropylene,
polyethylene, and fluoro-polymers, especially polyvinylidine
fluoride, or ceramics such as alumina or zirconia. The number, size
and location of the pivot pins 108 may also vary depending upon the
particular application and the number of current shielding members
130 employed in the adjustable current shield 100.
[0028] FIGS. 2C-2D depict various aspects of one illustrative
example of a moveable ring 112 that may be employed in the
adjustable current shield 100 disclosed herein. In the depicted
example, the moveable ring 112 has an inner surface 114 and an
outer surface 116. A plurality of pins 118 are attached to the
stationary ring 102. As shown in FIG. 2E, the moveable ring 112 is
adapted to be positioned in the recess 111 formed in the stationary
ring 102. Any of a variety of means may be provided for causing
movement of the moveable ring 112 relative to the stationary ring
102. In the depicted example, such means may include a plurality of
schematically depicted gear teeth 113 that are coupled to the
moveable ring 112. The gear teeth 113 are adapted to be engaged by
a driving member or device (not shown in FIG. 2C) to cause relative
movement of the moveable ring 112. Alternatively, such means may
include a schematically depicted lever 115 that is coupled to the
moveable ring 112. The lever 115 is adapted to be engaged by a
driving member or device (not shown in FIG. 2C) or manually to
cause relative movement of the moveable ring 112. The physical size
of the moveable ring 112 may vary depending upon a variety of
factors, including the size of the plating apparatus 10 in which it
will be employed and the mechanical loading it is anticipated to
experience in operation. In one illustrative example, the moveable
ring 112 may have a radial thickness (outside diameter minus inside
diameter) of about 5-30 mm, and an overall thickness of about 5-20
mm. The moveable ring 112 may be made of a dielectric material or a
composite material that includes a dielectric coating various
plastics, such as polypropylene, polyethylene, and fluoro-polymers,
especially polyvinylidine fluoride, or ceramics such as alumina or
zirconia. The number, size and location of the pins 118 may also
vary depending upon the particular application and the number of
current shielding members 130 employed in the adjustable current
shield 100.
[0029] FIGS. 3A-3B depict one illustrative example of a plurality
of current shielding members 130 that may be employed with the
adjustable current shield 100 disclosed herein. FIG. 3B is somewhat
of an assembly drawing of the adjustable current shield 100 with
the stationary ring 102 and the moveable ring 112 depicted in
dashed lines. As will be appreciated by those skilled in the art
after a complete reading of the present application, the size,
number, shape and configuration of the current shielding members
130 employed with the adjustable current shield 100 disclosed
herein may vary depending on the particular application. In the
example depicted in FIG. 3A, each of the current shielding members
130 has a generally elongated, curved configuration. In the
embodiment disclosed herein, each of the current shielding members
130 comprises a pivot hole 132 and a slot 134. In this example, the
pivot hole 132 is adapted to receive and operatively cooperate with
one of the pins 108 on the stationary ring 102, while the slot 134
is adapted to receive and operatively cooperate with one of the
pins 118 on the moveable ring 112. If desired, the positions of the
hole 132 and the slot 134 on the current shielding member 130 may
be interchanged, but the orientation of the slot 134 would need to
be rotated ninety degrees as compared to the orientation of the
slot 134 that is depicted in the drawings. In some embodiments, the
slots 134 may have some degree of curvature, although that is not
depicted in the attached drawings. The number and physical size of
the current shielding members 130 may vary depending upon a variety
of factors, including the size of the plating apparatus 10 in which
they will be employed and the mechanical loading the current
shielding members 130 are anticipated to experience in operation.
In one illustrative example, the current shielding members 130 may
have a width 130W of about 10-30 mm, and an overall thickness of
about 1-3 mm. The current shielding members 130 may be made of a
dielectric material or a composite material that includes a
dielectric coating various plastics, such as polypropylene,
polyethylene, and fluoro-polymers, especially polyvinylidine
fluoride, or ceramics such as alumina or zirconia.
[0030] With reference to FIG. 3B, in one embodiment, the gear teeth
113 on the moveable ring 112 are adapted to be engaged by teeth 142
on an illustrative drive motor 140, such as a stepper motor. In one
embodiment, the drive motor 140 is adapted to cause rotation of the
moveable ring 112 in either of the directions indicated by the
arrows 150 (clockwise) or 152 (counterclockwise). Accordingly, in
this embodiment, the drive motor 140 constitutes part of the means
for causing relative movement of the moveable ring 112. The
illustrative lever 115 may also be moved in the directions 160, 162
to cause relative movement of the moveable ring 112. Movement of
the lever 115 may be accomplished manually or by electromechanical
means, such as by an electric motor (not shown) coupled to the
lever 115 by appropriate mechanical linkage.
[0031] In the example depicted in FIG. 3B, eight of the
illustrative current shielding members 130 are employed as part of
the illustrative adjustable current shield 100 disclosed herein. Of
course, as noted above, the number of such current shielding
members 130 employed in any particular plating apparatus 10 may
vary depending upon the particular application. The adjustable
current shield 100 is depicted in its fully closed position in FIG.
3B, wherein the current shielding members 130 have their smallest
effective width as it relates to acting as a current shield during
plating operations. In the particular example depicted herein, a
distal portion 136 (see FIG. 3A) of each of the current shielding
members 130 is positioned above a portion of an adjacent current
shielding member 130, and in some cases may contact the adjacent
current shielding member 130. The amount or degree to which the
distal portion 136 overlaps an adjacent current shielding member
130 may vary depending upon the particular application. In some
embodiments, there may be no such overlap at all.
[0032] The effective width of the current shielding members 130 may
be adjusted as follows. Rotation of the moveable ring 112 relative
to the stationary ring 102 (by means of the lever 115 or the motor
140/gear teeth 113/142) in the direction indicated by the arrow 150
causes a portion of the current shielding members 130 to be
extended radially inward, in the direction indicated by the arrow
150A, to thereby increase the effective width of the adjustable
current shield 100. During this process, the current shielding
members 130 pivot around the pin 108 on the stationary ring 102.
The slot 134 cooperates with the pin 118 on the moveable ring 112
to allow the movement of the current shielding member 130. The
amount or extent to which the current shielding members 130 may
move radially inward depends upon the desired effective width of
the adjustable current shield 100 and the specific design of the
plating apparatus. Normally, the adjustable current shield 100 will
have a limit on how far the moveable ring 112 may be rotated
relative to the stationary ring 102, which will correspond to a
maximum displacement of the current shielding members 130 (not
shown) in the radially inward direction 150A. In some cases, to the
extent that each of the current shielding members 130 overlapped
with an adjacent current shielding member 130 when the adjustable
current shield 100 was in its fully closed position (as shown in
FIG. 3B), such an overlapping relationship may not exist when the
current shielding members 130 are shifted inward. Rotation of the
moveable ring 112 relative to the stationary ring 102 (by means of
the lever 115 or the motor 140/gear teeth 113/142) in the direction
indicated by the arrow 152 (counterclockwise) causes the current
shielding members 130 to be moved in a radially outward direction,
as indicated by the arrow 152A, to thereby decrease the effective
width of the adjustable current shield 100. Once the adjustable
current shield 100 is adjusted such that the current shielding
members 130 are positioned so as to provide the desired amount of
current shielding during plating operations, the adjustable current
shield 100 may be locked or secured in this desired position by any
suitable means.
[0033] As will be appreciated by those skilled in the art after a
complete reading of the present application, the adjustable current
shield 100 provides several advantages as it relates to performing
plating operations. For example, to the extent that there is a
change in the design of the substrates to be processed through the
plating apparatus 10, or a change in the processing parameters, the
adjustable current shield 100 provides a readily adjustable means
by which a process engineer may attempt to reduce or eliminate the
problems associated with producing plated metal layers with an
edge-thick profile. Moreover, by adjusting the shape, size and/or
number of current shielding members 130, as well as the extent to
which portions of the current shielding members 130 may be
positioned radially inward, a process engineer has greater
processing flexibility to "tune" plating operations as necessary.
In one embodiment, the subject matter disclosed herein is directed
to a plating apparatus that includes a plurality of segmented
shielding members that may be actuated simultaneously or
individually to effectively change the size (effective diameter) of
the opening or aperture of a substantially circular current
shield.
[0034] The particular embodiments disclosed above are illustrative
only, as the invention may be modified and practiced in different
but equivalent manners apparent to those skilled in the art having
the benefit of the teachings herein. For example, the process steps
set forth above may be performed in a different order. Furthermore,
no limitations are intended to the details of construction or
design herein shown, other than as described in the claims below.
It is therefore evident that the particular embodiments disclosed
above may be altered or modified and all such variations are
considered within the scope and spirit of the invention.
Accordingly, the protection sought herein is as set forth in the
claims below.
* * * * *