U.S. patent application number 16/407421 was filed with the patent office on 2019-11-14 for systems and methods for removing contaminants in electroplating systems.
This patent application is currently assigned to Applied Materials, Inc.. The applicant listed for this patent is Applied Materials, Inc.. Invention is credited to Marvin L. Bernt, Kyle M. Hanson, Bioh Kim, Sam Lee, Paul McHugh, Kwan Wook Roh.
Application Number | 20190345624 16/407421 |
Document ID | / |
Family ID | 68465125 |
Filed Date | 2019-11-14 |
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United States Patent
Application |
20190345624 |
Kind Code |
A1 |
Roh; Kwan Wook ; et
al. |
November 14, 2019 |
SYSTEMS AND METHODS FOR REMOVING CONTAMINANTS IN ELECTROPLATING
SYSTEMS
Abstract
Electroplating systems according to the present technology may
include a two-bath electroplating chamber including a separator
configured to provide fluid separation between a first bath
configured to maintain a catholyte during operation and a second
bath configured to maintain an anolyte during operation. The system
may include a catholyte tank fluidly coupled with the first bath of
the two-bath electroplating chamber. The system may also include a
contaminant retrieval system configured to remove contaminant ions
from the catholyte.
Inventors: |
Roh; Kwan Wook; (Kalispell,
MT) ; McHugh; Paul; (Kalispell, MT) ; Lee;
Sam; (Kalispell, MT) ; Hanson; Kyle M.;
(Kalispell, MT) ; Bernt; Marvin L.; (Whitefish,
MT) ; Kim; Bioh; (Andover, MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Applied Materials, Inc. |
Santa Clara |
CA |
US |
|
|
Assignee: |
Applied Materials, Inc.
Santa Clara
CA
|
Family ID: |
68465125 |
Appl. No.: |
16/407421 |
Filed: |
May 9, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62669180 |
May 9, 2018 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C25D 5/22 20130101; C25D
21/18 20130101; C25D 7/12 20130101; C25D 5/08 20130101; C25D 3/38
20130101; C25D 3/30 20130101 |
International
Class: |
C25D 5/22 20060101
C25D005/22; C25D 5/08 20060101 C25D005/08; C25D 3/30 20060101
C25D003/30; C25D 3/38 20060101 C25D003/38 |
Claims
1. An electroplating system comprising: a two-bath electroplating
chamber including a separator configured to provide fluid
separation between a first bath configured to maintain a catholyte
during operation and a second bath configured to maintain an
anolyte during operation; a catholyte tank fluidly coupled with the
first bath of the two-bath electroplating chamber; and a
contaminant retrieval system configured to remove contaminant ions
from the catholyte.
2. The electroplating system of claim 1, wherein the contaminant
retrieval system comprises a vessel positioned fluidly inline
between the first bath and the catholyte tank.
3. The electroplating system of claim 2, wherein the vessel
comprises an anode and a cathode electrically coupled with a power
supply.
4. The electroplating system of claim 3, wherein the anode
comprises a first material that is consumable or inert to the
catholyte.
5. The electroplating system of claim 4, wherein the catholyte
comprises a solution including tin, wherein the contaminant ions
comprise copper, and wherein the first material comprises tin.
6. The electroplating system of claim 4, wherein the first material
comprises a material inert to the catholyte and more noble than
copper.
7. The electroplating system of claim 3, wherein the power supply
is configured to operate at a voltage below a plating potential for
tin within the electroplating system.
8. The electroplating system of claim 7, wherein the power supply
is configured to operate at a voltage above a plating potential for
copper within the electroplating system.
9. The electroplating system of claim 2, wherein the vessel
comprises a packed bed of tin-containing particles.
10. The electroplating system of claim 1, wherein the contaminant
retrieval system comprises a packed bed of tin-containing particles
positioned in the catholyte tank.
11. A method of removing copper contaminants from a tin-containing
catholyte within an electroplating system, the method comprising:
flowing the catholyte from an electroplating chamber to a catholyte
tank, passing the catholyte across a tin-containing material, and
reducing the copper contaminants from the catholyte.
12. The method of removing copper contaminants from a
tin-containing catholyte within an electroplating system of claim
11, wherein the tin-containing material comprises an anode of an
anode-cathode pair of electrically coupled electrodes.
13. The method of removing copper contaminants from a
tin-containing catholyte within an electroplating system of claim
12, wherein the anode and cathode are driven at a voltage below a
tin plating potential and above a copper plating potential.
14. The method of removing copper contaminants from a
tin-containing catholyte within an electroplating system of claim
12, wherein the cathode comprises tin or a material more noble than
copper.
15. The method of removing copper contaminants from a
tin-containing catholyte within an electroplating system of claim
12, wherein the tin-containing material is maintained in a vessel
positioned between and fluidly coupled with the electroplating
chamber and the catholyte tank.
16. The method of removing copper contaminants from a
tin-containing catholyte within an electroplating system of claim
11, wherein the tin-containing material comprises a packed column
of the tin-containing material.
17. The method of removing copper contaminants from a
tin-containing catholyte within an electroplating system of claim
11, wherein the tin-containing material is disposed within the
catholyte tank.
18. An electroplating system comprising: an electroplating chamber;
an electrolyte tank fluidly coupled with the electroplating chamber
and configured to maintain an electrolyte; a tin-containing
electrolyte including copper ions; and a contaminant retrieval
system configured to remove the copper ions from the electrolyte,
wherein the contaminant retrieval system comprises a single
component system of a tin-containing material, or a dual component
system of a tin-containing material or a material more noble than
copper on the electromotive force series.
19. The electroplating system of claim 18, wherein the contaminant
retrieval system comprises a vessel positioned between the
electroplating chamber and the electrolyte tank, and wherein the
vessel houses the single component system or the dual component
system.
20. The electroplating system of claim 18, wherein the contaminant
retrieval system is configured in operation to maintain an increase
in copper ion concentration within the electrolyte below about 1
ppm per five thousand wafers processed.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Patent Application No. 62/669,180, filed on May 9, 2018, and which
is hereby incorporated by reference in its entirety for all
purposes.
TECHNICAL FIELD
[0002] The present technology relates to systems and methods for
semiconductor processing. More specifically, the present technology
relates to systems and methods for reducing or removing
contaminants from electroplating electrolyte solutions.
BACKGROUND
[0003] Integrated circuits are made possible by processes which
produce intricately patterned material layers on substrate
surfaces. During electroplating operations, contamination may occur
in the form of metal ions incorporated within an electrolytic
solution used in the electroplating system. Although the
electrolyte may be replaced within the system, the replacement may
be expensive and require extended time offline for the system.
[0004] Thus, there is a need for improved systems and methods that
can be used to produce high quality devices and structures. These
and other needs are addressed by the present technology.
SUMMARY
[0005] Electroplating systems according to the present technology
may include a two-bath electroplating chamber including a separator
configured to provide fluid separation between a first bath
configured to maintain a catholyte during operation and a second
bath configured to maintain an anolyte during operation. The system
may include a catholyte tank fluidly coupled with the first bath of
the two-bath electroplating chamber. The system may also include a
contaminant retrieval system configured to remove contaminant ions
from the catholyte.
[0006] In some embodiments, the contaminant retrieval system may
include a vessel positioned fluidly inline between the first bath
and the catholyte tank. The vessel may include an anode and a
cathode electrically coupled with a power supply. The anode may
include a first material that is consumable or inert to the
catholyte. The catholyte may include a solution including tin and
the contaminant ions may include copper, and thus the first
material may be or include tin. The first material may be or
include a material inert to the catholyte and more noble than
copper. The power supply may be configured to operate at a voltage
below a plating potential for tin within the electroplating system.
The power supply may be configured to operate at a voltage above a
plating potential for copper within the electroplating system. The
vessel may include a packed bed of tin-containing particles. The
contaminant retrieval system may be or include a packed bed of
tin-containing particles positioned in the catholyte tank.
[0007] Some embodiments of the present technology may also
encompass methods of removing copper contaminants from a
tin-containing catholyte within an electroplating system. The
methods may include flowing the catholyte from an electroplating
chamber to a catholyte tank. The methods may include passing the
catholyte across a tin-containing material. The methods may also
include reducing the copper contaminants from the catholyte.
[0008] In some embodiments, the tin-containing material may be an
anode of an anode-cathode pair of electrically coupled electrodes.
The anode and cathode may be driven at a voltage below a tin
plating potential and above a copper plating potential. The cathode
may be or include tin or a material more noble than copper. The
tin-containing material may be maintained in a vessel positioned
between and fluidly coupled with the electroplating chamber and the
catholyte tank. The tin-containing material may be or include a
packed column of the tin-containing material. The tin-containing
material may be disposed within the catholyte tank.
[0009] Embodiments of the present technology may also encompass
electroplating systems. The systems may include an electroplating
chamber. The systems may include an electrolyte tank fluidly
coupled with the electroplating chamber and configured to maintain
an electrolyte. The systems may include a tin-containing
electrolyte including copper ions. The systems may also include a
contaminant retrieval system configured to remove the copper ions
from the electrolyte. The contaminant retrieval system may include
a single component system of a tin-containing material, or a dual
component system of a tin-containing material or a material more
noble than copper on the electromotive force series. The
contaminant retrieval system may include a vessel positioned
between the electroplating chamber and the electrolyte tank, and
the vessel may house the single component system or the dual
component system. The contaminant retrieval system may be
configured in operation to maintain an increase in copper ion
concentration within the electrolyte below about 1 ppm per five
thousand wafers processed. Such technology may provide numerous
benefits over conventional technology. For example, the present
systems provide a cost-effective solution to reducing contaminant
levels within an electrolyte of the system. Additionally, the
present systems and methods may improve quality while having a
limited effect on bath chemistries and process parameters. These
and other embodiments, along with many of their advantages and
features, are described in more detail in conjunction with the
below description and attached figures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] A further understanding of the nature and advantages of the
disclosed embodiments may be realized by reference to the remaining
portions of the specification and the drawings.
[0011] FIG. 1 shows a schematic view of an electroplating system
according to some embodiments of the present technology.
[0012] FIG. 2A shows a schematic view of a contaminant retrieval
system according to some embodiments of the present technology.
[0013] FIG. 2B shows a schematic view of a contaminant retrieval
system according to some embodiments of the present technology.
[0014] FIG. 3 shows a schematic view of an electroplating system
according to some embodiments of the present technology.
[0015] FIG. 4 shows selected operations of a method of removing
copper contaminants from a tin-containing catholyte within an
electroplating system according to some embodiments of the present
technology.
[0016] Several of the figures are included as schematics. It is to
be understood that the figures are for illustrative purposes, and
are not to be considered of scale unless specifically stated to be
of scale. Additionally, as schematics, the figures are provided to
aid comprehension and may not include all aspects or information
compared to realistic representations, and may include exaggerated
material for illustrative purposes.
[0017] In the figures, similar components and/or features may have
the same numerical reference label. Further, various components of
the same type may be distinguished by following the reference label
by a letter that distinguishes among the similar components and/or
features. If only the first numerical reference label is used in
the specification, the description is applicable to any one of the
similar components and/or features having the same first numerical
reference label irrespective of the letter suffix.
DETAILED DESCRIPTION
[0018] A variety of systems are used in the semiconductor industry
for electrodeposition. For example, electroplating may be performed
in single-bath electrolyte systems having a single electrolyte in
contact with both the anode and cathode. Plating may also be
performed in two-bath electrolyte systems including an anolyte and
catholyte. The two-bath chamber typically includes a separator or
membrane separating the two fluids, while allowing certain ions to
permeate the membrane and cause plating at the cathode.
[0019] In a two-bath system the catholyte may be in contact with
the substrate on which deposition may be performed, while the
anolyte is maintained physically separated from the substrate by
the membrane or separator. During some electroplating operations,
one metal may be plated over a second metal, which may have been
deposited in an upstream or previous operation. Upstream
electroplating systems can act as a source of metal ion
contamination for subsequent electroplating systems. For example,
when forming soldering connections, a solder material, such as tin,
tin-silver, or a lead-free material may be deposited over a
separate metal, such as copper, for example, that may have been
formed in a previous operation. The process for depositing the
solder material may use a catholyte including ions of the solder
metal, such as tin, as well as a number of additives, acid, and
other materials providing a specifically balanced solution
configured to reduce the tin ions in order to produce a layer of
the solder material over exposed regions of the first material in
the electroplating chamber.
[0020] The copper may have been formed in any number of previous
operations, including in a previous electrodeposition operation.
When formed in an upstream or previous electrodeposition operation,
residual electrolyte including copper ions may be transferred with
the substrate into the tin-containing electrolytic bath
incorporating an amount of copper ion contamination within the
tin-containing electrolyte. Additionally, due to properties or
conditions of the tin-containing electrolyte, copper may naturally
erode, etch, or undergo oxidation reactions sending ions into the
subsequent tin-containing electrolyte during or prior to the
subsequent plating operations. This may also incorporate an amount
of copper contamination within the tin-containing electrolyte. If
left unresolved, as plating operations are performed, and hundreds
or thousands of substrates are processed, the copper ion
concentration within the tin-containing electrolyte may continue to
rise. If left unresolved, the buildup of contaminants can cause a
number of issues including chemical reaction between the plating
solution and the contaminant materials. Additionally, increased
levels of copper contamination within tin-containing electrolytes
have been shown to produce surface roughness on plated materials,
and other defects or voids between the plated materials.
[0021] Some conventional technologies have attempted to address
contaminant levels in an electrolyte by performing bath changes in
which the tin-containing electrolyte is exchanged for new
electrolyte in the system when contaminant levels are too high.
This process may be expensive based on the cost of electrolyte
additives and materials, and may require increased amounts of tool
down time during the exchanges. Alternatively operations may be
performed to refresh the electrolyte by routinely withdrawing some
electrolyte and incorporating new electrolyte, which may replenish
a percentage of the amount of electrolyte in the system in a given
cycle, and may continually exchange the electrolyte over a number
of these cycles. Depending on how often the exchange occurs, and
the volume involved in the exchange, these replenishments may also
be expensive over time.
[0022] The present technology improves on these conventional
techniques by performing operations in which contaminants may be
removed from the system by an advanced filtering or removal
technique, in which the contaminant ions may be electrochemically
removed from the tin-containing electrolyte. The present technology
may afford reduced contamination levels by continually or
intermittently removing copper ions from the electrolyte without
requiring physical exchange of the electrolyte. These operations
may reduce electrolyte replacement costs, and may increase system
uptime by allowing the removal to occur in a functioning system
during plating operations. It is to be understood that although the
disclosure will routinely describe removing copper ions from a
tin-containing electrolyte, the present technology is not so
limited. For example, any plating material including contaminant
ions may benefit from the present technology by performing
operations based on plating potential differences between the
metallic components as will be described below. For example,
additional applications for the present technology may include
copper contamination into nickel-containing chemistries, nickel
contamination into tin-silver chemistries, or any other application
where an upstream formation of a first material may provide a
contamination source into a downstream electrolyte. Accordingly,
the present technology should not be considered limited to the
exemplary materials discussed.
[0023] FIG. 1 shows a schematic view of an electroplating system
100 according to some embodiments of the present technology.
Electroplating system 100 illustrates a two-bath system, although
single-bath systems may similarly benefit from the present
technology as will be discussed further below. Electroplating
system 100 is shown including a pair of two-bath electroplating
chambers, including chamber 105 and chamber 110. It is to be
understood, however, that systems according to the present
technology may include one or more chambers utilizing an
electrolyte bath, and may include any number of chambers. As shown,
chamber 105 may include a first bath 106 configured to maintain a
catholyte during operation, as well as a second bath 108 configured
to maintain an anolyte during operation. A separator 107 may
provide fluid separation between the anolyte and catholyte, while
allowing ionic transport across the separator. Similarly, chamber
110 may include a third bath 112 configured to maintain a catholyte
during operation, as well as a fourth bath 114 configured to
maintain an anolyte during operation. A separator 113 may provide
fluid separation between the two baths.
[0024] Electroplating system 100 may also include a catholyte tank
120. Catholyte tank 120 may be fluidly coupled with the
electroplating chambers 105, 110, and may be specifically fluidly
coupled with the first bath 106 of chamber 105 and with the third
bath 112 of chamber 110. Although not shown in this embodiment, the
system may include a similar anolyte tank coupled with the second
bath 108 of chamber 105 and with the fourth bath 114 of chamber
110. The anolyte tank may include a separate piping or plumbing
system and a dedicated pump forming a separate loop for that
chemistry.
[0025] Pump 125 may be included in the electroplating system 100 to
provide fluid communication between the catholyte tank 120 and the
first bath 106 of chamber 105 and with the third bath 112 of
chamber 110. In other embodiments dedicated pumps may be provided
for each two-bath electroplating system, although a single pump may
be utilized as illustrated. The pump 125 may be configured to
provide catholyte to the electroplating chamber to ensure a
consistent chemistry is maintained during deposition processing.
Pump 125 may be a first pump in some embodiments in which a second
pump is included with an associated anolyte tank for providing
anolyte from the anolyte tank to the anolyte baths of the
associated electroplating chambers. Ancillary equipment may also be
included with electroplating system 100, such as a filter, as well
as unidentified sensors, valves, and common piping materials and
associated components. The illustrated piping configuration is
exemplary only, and is included to show potential lines including
returns 127 to the catholyte tank 120, which may intersect to
provide a common return 130. Other fluid configurations are
similarly encompassed by the present technology.
[0026] Electroplating system 100 may also include a contaminant
retrieval system configured to remove contaminant ions from the
catholyte. The contaminant retrieval system may include one or more
components that may operate to remove certain metal ions from the
catholyte. For example, in an exemplary system utilizing a
tin-containing catholyte, the contaminant retrieval system may be
configured to remove copper or other metal ions from the
tin-containing catholyte. The contaminant retrieval system may
include a vessel 135 positioned fluidly inline between the first
and third baths 106, 112 and the catholyte tank 120. In systems
according to the present technology, a single catholyte tank may be
used to provide and circulate catholyte to multiple chambers.
Vessel 135 may be positioned in a common line, including common
return line 130, or common delivery line 129, although individual
vessels 135 may be positioned within returns 127a, and 127b, for
example.
[0027] Vessel 135 may include one or more materials that may be
configured or operated to remove copper ions from the
tin-containing catholyte, or may remove other metal contaminants
from metal-ion-containing electrolytes. The contaminant retrieval
system may additionally or alternatively include device 140, which
may be disposed or positioned within the catholyte tank 120. For
example, device 140 may include similar materials as vessel 135, or
may include a separate material configured to operate on similar or
different mechanisms for removing metal ion contaminants from a
metal-ion-containing electrolyte. Vessel 135 may be positioned with
a bypass line as illustrated, which may allow intermittent
operation of the contaminant retrieval system in some embodiments,
although other bypass or inline incorporation schemes are similarly
encompassed by the present technology. Vessel 135 will be described
in detail with regard to FIG. 2 below along with exemplary
operating mechanisms for removing contaminants from an
electroplating system.
[0028] Turning to FIG. 2A is shown a schematic view of an exemplary
contaminant retrieval system 200 according to some embodiments of
the present technology. System 200 may be similar to, or include a
vessel 205 similar to, vessel 135 described above, and the system
or components may be positioned within a catholyte fluid system
between a catholyte tank and a processing chamber catholyte bath in
any location as noted previously. In some embodiments, by
incorporating the system 200 within a common return line between
the chamber catholyte bath and the catholyte tank, a single system
200 may be utilized for a multi-chamber system. Additionally, when
incorporated in a return line, catholyte may be flowing under
pressure, which may help drive catholyte flow within the system
200.
[0029] System 200 may include an inlet line 210 and an outlet line
215, which may be part of a common return line of an electroplating
system, or may be bypasses from a common or other fluid line of an
electroplating system. Valves 212 and 214 may be utilized to allow
or prevent flow through contaminant retrieval system 200. An
optional drain line 220 may also be incorporated with the
contaminant retrieval system 200, and may also include an optional
drain valve 222. The drain line may be used to remove electrolyte
material contained within the vessel 205 during a maintenance
operation, for example, and drain line 220 may extend as a
retrieval line back into a catholyte tank, such as tank 120, or may
deliver fluid to an alternative retrieval or disposal position. An
optional flow controller or diffuser 213 may be incorporated within
the vessel 205 in some embodiments to direct flow towards the anode
and cathode setup instead of simply bypassing to the outlet line
215. However, in other embodiments the vessel 205 may simply be
sized to produce a pressure drop configured to draw fluid through
the chamber to limit unintended bypass. Any other mechanical or
fluidic mechanisms may also be used to direct or maintain flow
within the vessel 205.
[0030] Within vessel 205 of contaminant retrieval system 200 may be
one or more devices or apparatus configured to perform a removal
operation intended to remove copper or other metallic ions from a
tin or other metal-containing electrolyte, while limiting or
preventing removal of the tin or metal ion of the electrolyte. Two
such options as may be included individually or in combination as
illustrated in FIG. 2A as well as 2B described below. As
illustrated in FIG. 2A, vessel 205 may include an electrode system
including an anode 230, a cathode 235, as well as a power source
240, which may be electrically coupled with anode 230 and cathode
235. Power source 240 is illustrated as a multi-cell source,
although it is to be understood that any number of power supplies
or sources may be used to provide a voltage configured to drive an
electrochemical operation between anode 230 and cathode 235. It is
also to be understood that the anode and cathode are being shown
schematically, and are not limited to the configuration
illustrated. For example, in some embodiments the position of the
anode and cathode may be reversed within the vessel, with the
cathode positioned above the anode. Additionally, the anode and
cathode may be disposed in a planar arrangement and positioned
adjacent or in line with one another. In some embodiments the anode
and cathode may be characterized by a curvature, and may be aligned
proximate one another along a common radius from a central axis
through the vessel, or with one of the anode or cathode positioned
concentrically or radially outward of the other of the anode or
cathode. Any other configurations possible within the vessel are
similarly encompassed by the present technology.
[0031] Anode 230 may be made of a first material, and cathode 235
may be made of a second material. In some embodiments the first
material and the second material may be similar or identical to one
another. In some embodiments one or both of the anode 230 or
cathode 235 may be or include tin or a tin-containing material,
although the material may be based on a different element, which
may be selected to coordinate with the ion of the catholyte. As
explained previously, one exemplary application of the present
system is where a tin-containing material may be plated over a
second material, which may be or include copper. In such an
electroplating operation, the catholyte of a two-bath system may
include metal ions of the material to be plated or deposited, which
in this case may be tin. In other embodiments in which a different
metal is to be plated, the anode and/or cathode may include the
different metal in the electrode composition. In some embodiments
the anode and/or cathode may be a more inert material, and may be a
material that is more noble on the electromotive force series than
one or both of the metal ion of the electrolyte, or the metal ion
of the contaminant. Continuing the example throughout this
description, the material of the anode or cathode may be more noble
than one or both of tin or copper. For example, materials including
platinum, silver, palladium, steel, chromium, nickel, titanium,
vanadium, zirconium, niobium, molybdenum, hafnium, tantalum,
tungsten, ruthenium, rhodium, technelium, rhenium, osmium, iridium,
antimony, tellurium, or other transition metals or other elements,
including compounds, such as oxides, or combinations of any of the
materials, may be used.
[0032] Although many of the identified materials may be utilized in
embodiments of the present technology, in some embodiments the
material may be selected to limit interference with the
electroplating system. For example, the material may be selected to
limit side reactions with components or additives of the
electrolyte, maintain conductivity, limit oxidation or passivation
within the electrolyte system, as well as withstand the environment
of the electrolyte. The anode 230 may be either consumable or inert
in the catholyte. One exemplary inert material may be or include
platinum, which may be used as one or both of the anode or cathode
in various embodiments. A consumable material may be or include tin
or a tin-containing material, which may also be incorporated as one
or both of the anode or cathode in various embodiments. In some
embodiments, the anode may be or include tin or a tin-containing
material, which may be consumed to provide tin ions into the
catholyte. Certain inert electrode materials may not oxidize metal
materials into the catholyte, but may generate or evolve gaseous
species within the catholyte if the potential is high enough, and
thus may be managed to limit gas from entering into the catholyte
via bubble separators or other collection mechanisms. Accordingly,
in some embodiments tin or a tin-containing material may be
utilized, which may be relatively or substantially neutral to the
catholyte by providing the metal ions, which may at least partially
replenish plating ions into the catholyte.
[0033] As previously stated, in other embodiments in which a
different metal is the base ion for the catholyte, the anode may be
or include that material, which may at least partially replenish
the electrolytic solution during operation of the contaminant
retrieval system. Either the anode or the cathode may take on a
number of designs, profiles, or configurations, including a plate
material, pellet material, or other configuration to provide
surface area characteristics configurable for a variety of system
designs. For example, in one embodiment, tin pellets may be
contained within a conductive sleeve to which power source 240 may
be coupled. Such a configuration may be positioned substantially
normal to a direction of flow within the vessel, and may provide an
amount or tortuosity of flow to improve contact of resident copper
ions with the tin or other materials to increase retrieval from the
system.
[0034] In some embodiments the power supply may be operated within
a particular voltage range within a cell potential difference
between the contaminant metal species and the electrolyte metal
species. For example, in some embodiments the power source may be
configured to supply a voltage within a window at least partially
defined by the cell potential between the contaminant material, for
example copper, and the electrolyte metal ion, for example tin. In
this example, the cell potential would be the copper potential of
about 0.34 minus the tin potential of negative 0.14, producing a
cell potential of about 0.48 V. Again, when different electrolyte
or contaminant materials are utilized, the potential may be
premised by the specific potential of those materials. By
maintaining the power supply operating voltage within a window
defined by the cell potential, the system may be configured to
reduce or plate out the contaminant material while maintaining the
electrolyte metal ion material. The system may be configured to
limit or prevent plating of the electrolyte metal ion material,
which would otherwise reduce the concentration of the ion intended
to be plated at the chamber cathode, which typically may be the
substrate.
[0035] In one non-limiting hypothetical scenario, chamber setup and
testing may identify that within one possible contaminant retrieval
system, tin may begin plating out of the electrolyte at a voltage
of greater than or about 2 V, and thus the plating potential for
tin within the system may be at a voltage above 2 V, such as 2.3 V,
as a hypothetical example. Accordingly, the voltage of power supply
240 may be maintained below the hypothetical 2.3 V in such a cell.
Based on the cell potential relative to the contaminant copper, the
cell potential for copper may be about 0.5 V less than the 2.3 V
for plating tin, and thus the plating potential for copper within
the system may be at a voltage above about 1.5 V, such as about 1.8
V, continuing the hypothetical example. Accordingly, the voltage of
power supply 240 may be maintained above the hypothetical 1.8 V in
some embodiments. Depending on many factors including cell
composition, electrolyte composition, or a variety of resistances
within the system, these plating potentials may be system specific,
and may be predetermined via testing for a given system. However,
during operation the power supply voltage may be maintained within
the window as defined below the plating potential for tin within
the given cell design. As copper or other contaminant concentration
continues to reduce within the electrolyte, the potential to plate
additional copper may shift in a more negative potential direction,
which may require increasing the voltage over time beyond the
predetermined or precalculated threshold to plate copper. However,
the voltage may still be maintained below the potential to plate
the electrolyte ion material, such as tin. After an amount of time
has passed where the window may not be suitably maintained without
beginning tin plating, the anode and or cathode material may be
replaced within the contaminant retrieval system.
[0036] FIG. 2B illustrates an additional embodiment of a schematic
view of an exemplary contaminant retrieval system 250 according to
some embodiments of the present technology, which may be combined
with or utilized instead of the anode 230 and cathode 235. System
250 may be similar to or include common components as discussed
above with respect to system 200, and may be incorporated within an
electroplating system in a similar manner. System 200 may also
include a vessel 205 similar to vessel 135 described above, and the
system or components may be positioned within a catholyte fluid
system between or within a catholyte tank and a processing chamber
catholyte bath in any location as noted previously.
[0037] System 200 may include an inlet line 210 and an outlet line
215, which may be part of a common return line of an electroplating
system, or may be bypasses from a common or other fluid line of an
electroplating system. Valves 212 and 214 may be utilized to allow
or prevent flow through contaminant retrieval system 200. An
optional drain line 220 may also be incorporated with the
contaminant retrieval system 200, and may also include an optional
drain valve 222. As previously noted, the drain line may be used to
remove electrolyte material contained within the vessel 205 during
a maintenance operation, for example, and drain line 220 may extend
as a retrieval line back into a catholyte tank, such as tank 120,
or may deliver fluid to an alternative retrieval or disposal
position.
[0038] Within vessel 205 of contaminant retrieval system 200 may be
a pelletized material 260 or otherwise packed particle design.
Packed material 260 may be or include a conductive material, and
may be any of the materials identified above for the anode and
cathode materials of system 200. In some embodiments the packed
materials may be tin or tin-containing particles positioned within
the vessel 205. Additionally or alternatively, the particles may be
included as device 140 within the catholyte tank. System 200 may
also be positioned within catholyte tank 120 described above. The
packed materials may be a single material included within the
vessel, or may be a combination of the components described above.
For example, the material may be more active on the electromotive
force series than the contaminant material. By incorporating the
material 260 within the vessel 205, a galvanic action may be
afforded by the system, which may allow plating and removal of the
contaminant from the electrolyte.
[0039] For example, when maintained in contact with the electrolyte
including the contaminant species, a galvanic reaction may occur on
multiple pellets of the material 260. For example, some pellets
will naturally begin to donate electrons in a reduction reaction to
contaminant ions, such as copper ions, which will begin to plate on
these pellets that may exhibit a cathode effect. Additional pellets
may then naturally exhibit an anode effect, and may donate
electrons to the system, causing the pellet to undergo an oxidation
reaction in which ions of the pellet material may be delivered into
the electrolyte material. The pellets or material 260 may not be
connected electrically, and the reaction may occur directly during
the flow of the electrolyte material across the surface of the
material 260. In some embodiments, when power source 240 of system
200 is not engaged, the same action may occur if the system is
allowed to continue circulating electrolyte across the anode and
cathode materials. Accordingly, one or both actions may be
performed or allowed to occur to reduce contaminant ion
concentration within the electroplating system.
[0040] Additional materials that may be utilized may include resin
or otherwise coated particles including an active exchange material
within the resin or coating. The exchange material may be
configured to perform a proton exchange relative to copper ions
incorporated within the electrolyte. The material may be configured
to preferentially interact with copper or contaminant ionic species
relative to other metallic species, such as ions of the electrolyte
utilized in plating. In operation, such as continuing the example
throughout this disclosure, tin ions and other materials may not
interact with the particles as they flow across or through the bed
of particles. Copper ions, however, may be absorbed through the
resin or coating material, and may be collected by the internal
active exchange material, which may expel a proton in response to
the collected copper. The particles may be capable of operating for
an amount of time, or may remove an amount of material before the
particles are saturated. Once saturated, or when nearing
saturation, the materials may be replaced or refreshed for
additional use. The resin or coating may be any material configured
to operate within the electrolyte and system environment, and allow
transmission of copper or contaminant ionic species, while limiting
or preventing transmission of other metallic or some other ionic
species.
[0041] By performing operations and using systems according to the
present technology, a concentration of contaminant ions may be
reduced and/or maintained below certain thresholds. For example,
the present technology may afford a contaminant-neutral
configuration allowing contaminant incorporation to be maintained
during substrate processing and routine replacement or refreshing
of the contaminant retrieval system components. Systems may be
capable of tolerating an amount of contaminant incorporation within
the electrolyte, such as less than or about 10 ppm, less than or
about 8 ppm, less than or about 5 ppm, less than or about 3 ppm,
less than or about 2 ppm, less than or about 1 ppm, less than or
about 100 ppb, less than or about 10 ppb, or less. The present
technology may be configured to limit additional contaminant
accumulation during a number of substrate processing operations.
For example, the present technology may limit additional
incorporation of contaminant and/or reduce native contaminant
levels below any of these stated limits at any time during
operation, including after processing more than or about 1,000
substrates, processing more than or about 5,000 substrates,
processing more than or about 10,000 substrates, or more. For
example, if a natural concentration of contaminant may be at 5 ppm
for an electrolyte solution, the present technology may maintain
the contaminant level below 6 ppm, below 5.1 ppm, as well as
further reduce contaminant levels below 5 ppm, below 4 ppm, or less
during processing of any of the noted substrate numbers.
Accordingly, the present technology may maintain or improve
contaminant levels within electrolytic materials.
[0042] The present technology may similarly be utilized in
single-bath systems in some embodiments. FIG. 3 shows a schematic
view of an electroplating system 300 according to some embodiments
of the present technology. Electroplating system 300 may include
some or all of the components discussed previously, although a
single electrolyte may be used within the systems alternatively to
a separate catholyte and anolyte. The components of electroplating
system 300 may operate similarly to the components described above,
and may be configured to limit contaminant accumulation to any of
the previously identified ranges. As illustrated, electroplating
system 300 may include an electroplating chamber 305, as well as an
additional electroplating chamber 310. Similar to previous systems,
electroplating system 300 may include any number of electroplating
chambers within the system. The electroplating chambers 305, 310
may be configured to house an electrolyte 306, 312 that is
distributed through the system. Electroplating system 300 may
include an electrolyte tank 320 fluidly coupled with the
electroplating chambers 305, 310, and configured to maintain the
electrolyte that is distributed.
[0043] Electroplating system 300 may include a pump 325 fluidly
coupled between the electrolyte tank 320 and the electroplating
chamber 310. The pump may be configured to provide electrolyte from
the electrolyte tank to the electroplating chamber 305.
Electroplating system 300 may also include any other ancillary
equipment in some embodiments that may be used in electroplating
chamber designs. Electroplating system 300 may be used in any
number of electroplating operations, and may be configured with
materials to perform operations related to a number of metals and
materials. In one example encompassed by the present technology,
the system may be used in a tin-plating operation, and may utilize
a tin-containing electrolyte. An amount of contaminant, such as a
copper ion contaminant, may be present in the electrolyte.
[0044] Electroplating system 300 may also include one or more
contaminant retrieval system components, which may include vessel
335 or device 340. Vessel 335 and device 340 may be or include any
of the materials or components previously described, and may be
configured to operate to reduce copper ion concentration within the
electrolyte. The contaminant retrieval system may include a single
component system, such as particles in a packed configuration as
previously described. The contaminant retrieval system may also
include a dual component system, such as an anode/cathode electrode
configuration with a power supply to drive an electroplating
operation as described previously. The system may be operated to
maintain or reduce contaminant concentration to any of the levels
previously described during processing of any number of
substrates.
[0045] The systems described previously may be used to perform one
or more methods, such as removing copper contaminants from a
tin-containing catholyte or electrolyte within an electroplating
system. FIG. 4 shows operations of an exemplary method 400 of
removing contaminant species from an electrolyte material according
to some embodiments of the present technology. Method 400 may be
performed with any of the systems previously described, which may
include any of the components or configurations described
elsewhere. Method 400 may include additional operations performed
prior to the stated operations, including a first deposition or
plating in a first chamber. For example, an upstream process may
include forming a copper-containing or other metal-containing
material on a substrate. The substrate may then be transferred to a
second plating chamber for plating a tin-containing or other
metal-containing material. When transitioned into an electrolyte
including the second material, such as the tin-containing material,
contamination may be introduced into the system as previously
described. Method 400 may include flowing a catholyte or
electrolyte through an electroplating system at operation 410. The
electrolyte may include a contaminant within the solution. The
electrolyte may be flowed between a processing chamber and an
electrolyte tank, which may be a catholyte tank in some
embodiments. At operation 420, the electrolyte may be passed over a
material configured to reduce or remove contaminants from the
electrolyte. In one example, a catholyte may be passed over a
tin-containing material. Contaminant species may be reduced or
removed from the electrolyte at operation 430.
[0046] As previously noted, the material may be any of the
materials previously described, and may include one or more
components including a retrieval vessel and/or a particulate
material included inline of a fluid line of the system, such as
fluidly coupled between the electroplating chamber and the
electrolyte tank. In some embodiments the material may also or
alternatively be included within an electrolyte tank, such as a
catholyte tank as previously described. In some embodiments the
material may be tin or a tin-containing material operated as an
anode of an anode-cathode pair of electrically coupled electrodes.
The contaminant species, which may be copper, may be plated onto
the cathode, while anode species may be eroded into the electrolyte
solution. In some embodiments one or more of the cathode or anode
may not be consumed during the operation. When operated as a
cathode and anode, the electrodes may be driven by a power source
operating at a voltage configured or tested to be below a tin
plating potential and above a copper plating potential, which may
also be below a potential of an electrolyte species and above a
potential of a contaminant species in other embodiments. In some
embodiments the cathode may be or include tin or may be a material
more noble on an electromotive force series than copper.
[0047] For example, during system setup, sample runs or tests may
be performed to determine a threshold voltage for the system at
which tin plating may occur. For example, a power source as
previously described may be operated at a particular voltage, while
a monitoring operation is performed for the current. Current flow
may be based on material plating out of the electrolyte. Thus, for
example, at low voltage, current flow may be reduced, or may not
occur. At a threshold at which copper plating may occur, an amount
of current may be observed. Based on the concentration of copper
within the solution, this current may be in a microamp or milliamp
range. As voltage is further increased, a threshold may be reached
at which current may rise in a more pronounced manner, which may
indicate plating of tin from the electrolyte. Because of the higher
concentration of tin within the system, current generated by the
plating of tin may be more than an order of magnitude higher than
during copper plating, for example.
[0048] Accordingly, a threshold for tin plating may then be
determined for the individual system, and voltage for operation may
then be maintained below this threshold, but above the threshold
potential for copper plating. As previously stated, the voltage may
be adjusted over time relative to the characteristics of the
electrolyte. For example, as copper ion concentration is further
reduced, voltage may be increased to accommodate further plating,
although the voltage may still be maintained below the tin-plating
threshold. Additionally, because of low copper concentration,
copper deposition may proceed at or near the mass-transfer limited
current density for the copper. Electrolyte flow characteristics
and characteristics of the cathode material may therefore be
important factors in removal of the limited copper or other
contaminant within the system. Flow agitators or other mechanisms
may therefore be included to facilitate movement within the vessel,
such as rifling along an interior of the vessel, as well as
incorporated devices to increase electrolyte movement within the
vessel. The cathode material may also be modified or enhanced in
some embodiments, including by incorporating roughening to increase
surface area and plating opportunity, as well as profiles including
fluted, creased, or corrugated designs that may increase residence
time at the cathode as well as surface area to facilitate plating.
In some embodiments as may be applicable in any of the previously
described figures, the cathode may be characterized by a greater
surface area than the anode, and may be characterized by at least
twice the surface area, at least three times the available surface,
at least five times the available surface area, at least ten times
the available surface area, or more.
[0049] The system may be operated in a continuous mode in some
embodiments to continue to reduce copper concentration and/or
provide additional tin from an anode. The system may also be
operated intermittently after testing of electrolyte indicates a
rise in copper ion concentration, such as above a threshold. By
operating the system intermittently, electrolyte balance may be
better maintained. For example, operating intermittently may limit
effects on other materials or additives in the electrolyte, and may
ensure an overabundance of tin ions are not provided into the
system.
[0050] In some embodiments the material may be included in a packed
configuration, either within a vessel or packed column configured
to provide sufficient surface area for interaction with the
electrolyte and contaminant species included within the
electrolyte. By utilizing the present technology, contaminant
levels within an electrolyte may be maintained or reduced below
predetermined levels. Utilizing electroplating and/or galvanic
interactions, the present technology may allow contaminant species
to be removed, while maintaining other ionic species within the
electrolyte. These techniques may reduce operating costs, while
maintaining system uptime, compared to conventional techniques.
[0051] In the preceding description, for the purposes of
explanation, numerous details have been set forth in order to
provide an understanding of various embodiments of the present
technology. It will be apparent to one skilled in the art, however,
that certain embodiments may be practiced without some of these
details, or with additional details.
[0052] Having disclosed several embodiments, it will be recognized
by those of skill in the art that various modifications,
alternative constructions, and equivalents may be used without
departing from the spirit of the embodiments. Additionally, a
number of well-known processes and elements have not been described
in order to avoid unnecessarily obscuring the present technology.
Accordingly, the above description should not be taken as limiting
the scope of the technology.
[0053] Where a range of values is provided, it is understood that
each intervening value, to the smallest fraction of the unit of the
lower limit, unless the context clearly dictates otherwise, between
the upper and lower limits of that range is also specifically
disclosed. Any narrower range between any stated values or unstated
intervening values in a stated range and any other stated or
intervening value in that stated range is encompassed. The upper
and lower limits of those smaller ranges may independently be
included or excluded in the range, and each range where either,
neither, or both limits are included in the smaller ranges is also
encompassed within the technology, subject to any specifically
excluded limit in the stated range. Where the stated range includes
one or both of the limits, ranges excluding either or both of those
included limits are also included. Where multiple values are
provided in a list, any range encompassing, encompassed by, or
based on any of those values, specifically stated or otherwise
included, is similarly specifically disclosed.
[0054] As used herein and in the appended claims, the singular
forms "a", "an", and "the" include plural references unless the
context clearly dictates otherwise. Thus, for example, reference to
"a material" includes a plurality of such materials, and reference
to "the fluid" includes reference to one or more fluids and
equivalents thereof known to those skilled in the art, and so
forth.
[0055] Also, the words "comprise(s)", "comprising", "contain(s)",
"containing", "include(s)", and "including", when used in this
specification and in the following claims, are intended to specify
the presence of stated features, integers, components, or
operations, but they do not preclude the presence or addition of
one or more other features, integers, components, operations, acts,
or groups.
* * * * *