U.S. patent application number 13/921006 was filed with the patent office on 2014-01-02 for electroplating apparatuses and methods employing liquid particle counter modules.
The applicant listed for this patent is Novellus Systems, Inc.. Invention is credited to Haiying Fu, Shantinath Ghongadi, Ludan Huang, Charles L. Merrill, Khuong Nguyen.
Application Number | 20140001050 13/921006 |
Document ID | / |
Family ID | 49768190 |
Filed Date | 2014-01-02 |
United States Patent
Application |
20140001050 |
Kind Code |
A1 |
Huang; Ludan ; et
al. |
January 2, 2014 |
ELECTROPLATING APPARATUSES AND METHODS EMPLOYING LIQUID PARTICLE
COUNTER MODULES
Abstract
Disclosed herein are electroplating apparatuses for
electroplating metal onto a semiconductor wafer which may include
an electroplating cell, an electrolyte circulation system connected
to the cell for circulating electrolyte to and from the cell, first
and second sampling ports for taking first and second sample of
electrolyte at first and second locations in the apparatus, and one
or more liquid particle counter modules, connected to the first and
second sampling ports, for measuring particle concentration in the
electrolyte. Also disclosed herein are methods for reducing
particle concentration in an electrolyte present in an
electroplating apparatus which may include determining an
approximate particle concentration using a liquid particle counter
module and modifying the operation of the electroplating apparatus
to reduce particle concentration in the electrolyte.
Inventors: |
Huang; Ludan; (Tigard,
OR) ; Nguyen; Khuong; (Portland, OR) ; Fu;
Haiying; (Camas, WA) ; Merrill; Charles L.;
(Portland, OR) ; Ghongadi; Shantinath; (Tigard,
OR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Novellus Systems, Inc. |
Fremont |
CA |
US |
|
|
Family ID: |
49768190 |
Appl. No.: |
13/921006 |
Filed: |
June 18, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61662853 |
Jun 21, 2012 |
|
|
|
Current U.S.
Class: |
205/109 ;
204/229.4; 204/237; 204/238 |
Current CPC
Class: |
C25D 21/14 20130101;
F24C 14/005 20130101; C25D 17/001 20130101; C25D 21/06
20130101 |
Class at
Publication: |
205/109 ;
204/237; 204/229.4; 204/238 |
International
Class: |
C25D 21/06 20060101
C25D021/06 |
Claims
1. An electroplating apparatus for electroplating metal onto a
semiconductor wafer, the apparatus comprising: an electroplating
cell for containing an anode and an electrolyte during
electroplating; an electrolyte circulation system connected to the
cell for circulating electrolyte to and from the cell; a first
sampling port for taking a first sample of electrolyte at a first
location in the apparatus; a second sampling port for taking a
second sample of electrolyte at a second location in the apparatus;
one or more liquid particle counter modules for measuring particle
concentration in the electrolyte, the liquid particle counter
modules connected to the first sampling port and the second
sampling port.
2. The apparatus of claim 1, further comprising a manifold, the
manifold connected to at least two sampling ports and to at least
one liquid particle counter module.
3. The apparatus of claim 2, further comprising two or more valves
for controlling the flow of electrolyte from the at least two
sampling ports to the manifold.
4. The apparatus of claim 3, further comprising a controller, the
controller comprising machine readable instructions for controlling
the opening and closing of the two or more valves to control the
flow of electrolyte from the at least two sampling ports to the
manifold.
5. The apparatus of claim 1, wherein at least one liquid particle
counter module is configured to measure particle concentration in
the electrolyte at a rate between about 9 and 11 mL/min.
6. The apparatus of claim 1, further comprising a pump, and wherein
a sampling port is located directly downstream of the pump, and
wherein a sampling port is located directly upstream of the
pump.
7. The apparatus of claim 6, further comprising a controller
configured to (i) monitor the particle concentrations upstream and
downstream from the pump, (ii) determine when the pump is producing
more than a threshold amount of particles; and (iii) generate an
alert and/or modify operation of the apparatus when the pump is
producing more than the threshold amount of particles.
8. The apparatus of claim 1, further comprising a reservoir for
holding electrolyte, and wherein a sampling port is located within
the reservoir.
9. The apparatus of claim 1, further comprising a contactor, and
wherein a sampling port is located directly downstream of the
contactor.
10. The apparatus of claim 1, further comprising a particle filter,
and wherein a sampling port is located directly downstream of the
particle filter.
11. The apparatus of claim 1, wherein a sampling port is located
directly upstream of the electroplating cell.
12. The apparatus of claim 1, wherein a sampling port is located
directly upstream of the electroplating cell and a sampling port is
located directly downstream of the electroplating cell.
13. The apparatus of claim 1, wherein a sampling port is located
within the interior of the electroplating cell.
14. The apparatus of claim 13, further comprising a separated anode
chamber within the electroplating cell, and wherein a sampling port
is located proximate to, and downstream from, a membrane separating
the separated anode chamber from the cathode chamber within the
electroplating cell.
15. The apparatus of claim 13, further comprising a controller
configured to (i) monitor the particle concentration within the
interior of the electroplating cell, (ii) determine when the
particle concentration in the electroplating cell is greater than a
threshold level; and (iii) generate an alert and/or modify
operation of the apparatus when the particle concentration in the
electroplating cell is greater than the threshold level.
16. The electroplating apparatus of claim 1, further comprising a
controller configured to: determine the approximate particle
concentration in the first sample using the one or more liquid
particle counter modules; determine the approximate particle
concentration in the second sample using the one or more liquid
particle counter modules; and modify the operation of the
electroplating apparatus to reduce particle concentration in the
electrolyte circulating to and from the electroplating cell.
17. The electroplating apparatus of claim 16, wherein the
controller is further configured to identify a source of particle
contamination in the apparatus based on the approximate particle
concentrations in the first and second samples, and wherein
modifying the operation of the electroplating apparatus comprises
diverting electrolyte away from the source of particle
contamination.
18. The electroplating apparatus of claim 17, wherein the source of
particle contamination is another electroplating cell of the
electroplating apparatus, and wherein diverting electrolyte away
from this cell comprises closing one or more valves to isolate this
cell from the electrolyte circulation system.
19. The electroplating apparatus of claim 16, wherein the
controller is further configured to: direct the first sample of
electrolyte from the first sampling port to the one or more liquid
particle counter modules; and direct the second sample of
electrolyte from the second sampling port to the one or more liquid
particle counter modules.
20. The electroplating apparatus of claim 1, further comprising a
controller configured to: determine the approximate particle
concentration in the first sample using the one or more liquid
particle counter modules; determine the approximate particle
concentration in the second sample using the one or more liquid
particle counter modules; and send an alert to the operator of the
electroplating apparatus if the approximate particle concentration
in the first and/or second samples exceeds a threshold.
21. The electroplating apparatus of claim 1, further comprising a
controller configured to: determine the approximate particle
concentration in the first sample using the one or more liquid
particle counter modules; determine the approximate particle
concentration in the second sample using the one or more liquid
particle counter modules; and send an alert to the operator of the
electroplating apparatus if the magnitude of the difference between
the approximate particle concentrations in the first and second
samples exceeds a threshold.
22. The electroplating apparatus of claim 21, wherein the first
sampling port is located directly upstream of the electroplating
cell, and the second sampling port is located directly downstream
of the electroplating cell.
23. The electroplating apparatus of claim 21, further comprising a
pump, and wherein the first sampling port is located directly
upstream of the pump, and the second sampling port is located
directly downstream of the pump.
24. A method for reducing particle concentration in an electrolyte
present in an electroplating apparatus having an electroplating
cell and an electrolyte circulation system for circulating
electrolyte to and from the electroplating cell, the method
comprising: directing a first sample of electrolyte from a first
sampling port in the apparatus to one or more liquid particle
counter modules; determining the approximate particle concentration
in the first sample using the one or more liquid particle counter
modules; directing a second sample of electrolyte from a second
sampling port in the apparatus to the one or more liquid particle
counter modules; determining the approximate particle concentration
in the second sample using the one or more liquid particle counter
modules; and modifying the operation of the electroplating
apparatus to reduce particle concentration in the electrolyte
present in the electroplating apparatus.
25. The method of claim 24, wherein modifying the operation of the
electroplating apparatus comprises: identifying a source of
particle contamination based on the approximate particle
concentration in the first sample and the approximate particle
concentration in the second sample; and replacing the source of
particle contamination.
26. The method of claim 25, wherein the source of particle
contamination is a chemical or a component within the
electroplating apparatus.
27. The method of claim 24, wherein modifying the operation of the
electroplating apparatus comprises: identifying a source of
particle contamination based on the approximate particle
concentration in the first sample and the approximate particle
concentration in the second sample; and diverting electrolyte away
from the source of particle contamination.
28. The method of claim 27, wherein the source of particle
contamination is an electroplating cell, and wherein diverting
electrolyte away from the cell comprises closing one or more valves
to isolate the cell from the electrolyte circulation system.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional Pat.
App. No. 61/662,853, filed Jun. 21, 2012, and titled "LIQUID
PARTICLE COUNTER FOR ELECTROPLATING APPARATUS," which is hereby
incorporated by reference in its entirety for all purposes.
BACKGROUND
[0002] Electroplating has many applications. One important
application is in plating copper onto semiconductor wafers to form
conductive copper lines for "wiring" individual devices of the
integrated circuit. Often, this electroplating process serves as a
step in, for example, a Damascene fabrication procedure. Other
important applications include through silicon via plating (TSV)
and wafer level packaging (WLP). A continuing issue in modern wafer
electroplating processing is the quality of the deposited metal
film. Defects on the deposited metal film are of particular
concern. Examples of such defects include defects resulting from
pits, protrusions, and particles/agglomerates formed on the film.
Electroplating is frequently performed at a late stage in the
device fabrication procedure when the processed wafer is worth many
thousands of dollars. Defects introduced at this stage can result
in substantial losses for integrated circuit manufacturers.
[0003] End users of sophisticated electroplating tools typically
collect defect information on a daily basis. They may accomplish
this by electroplating on a monitor wafer and counting the plated
defects. Defects that create pits in the electroplated layer are
particularly problematic, but any defect can be detrimental.
Assessing defectivity of an electroplating apparatus through use of
a monitor wafer introduces various problems. First, monitor wafers
are quite expensive. Additionally, the time spent plating onto a
monitor wafer is down time for the apparatus. No production wafers
can be plated while the monitor wafer is installed. Further the use
of a monitor wafer cannot pinpoint where or when an apparatus is
failing through particle generation.
SUMMARY OF THE DISCLOSURE
[0004] This disclosure presents various implementations of liquid
particle counter (LPC) modules as components of electroplating
tools. LPC modules may help to detect particles in electrolyte,
allowing designers and operators of electroplating apparatuses to
address problematic conditions before they introduce significant
defects in wafers. Implementations of LPC modules during the design
stage, research and development stage, and wafer production stage
have proven beneficial. For example, in some embodiments,
continuous particle monitoring of various locations within an
electroplating apparatus may provide a constant process signature
so that the conditions of chosen on-tool/apparatus components are
known during production. Additionally, monitoring of incoming
chemicals and/or previously combined chemicals in the electrolyte
can be provided at various locations. Moreover, LPC monitoring at
locations chosen to address particular defect types can accurately
predict on-wafer defect performance, a metric which is
conventionally typically obtained only after a wafer is processed
with stand-alone metrology tools. In some embodiments, the
disclosed implementation of LPC modules on electroplating
tools/apparatuses allows for a comprehensive monitoring and
diagnostic scheme that reveals real-time tool conditions and aids
timely system troubleshooting and maintenance. Additionally, LPC
modules may be used to isolate particle generating hardware in the
apparatus during research and design. In some cases, such hardware
components can be replaced before production, thereby potentially
reducing production wafer defects.
[0005] In some embodiments, LPC modules may use light scattering as
a method of particle detection. Different particle types such as
solid particles and bubbles may produce similar LPC scattering
signatures. In some embodiments, LPC modules are connected to
multiple sampling ports distributed throughout the apparatus. A
single LPC module may detect particle concentrations from multiple
different locations throughout the electroplating apparatus. The
sample ports may be designed and located to capture or exclude
certain types of particles. For example, a sampling port may be
designed to exclude bubbles from reaching the LPC module.
[0006] Certain embodiments disclosed herein concern an apparatus
for electroplating metal onto a substrate. The apparatus may be
characterized by the following features: (a) an electroplating cell
for electroplating metal onto a substrate; (b) an electrolyte
circulation system connected to the electroplating cell; (c) one or
more liquid particle counter modules for measuring particle
concentration in an electrolyte solution; and (d) sampling ports
for taking samples at two or more locations in the apparatus. In
various embodiments, the apparatus is configured for electroplating
copper.
[0007] A single liquid particle counter module may be configured to
analyze samples from multiple sampling ports. To this end, the
liquid particle counter module may be coupled to a manifold to
enable selective monitoring of sampling ports. The manifold and
associated apparatus may include a tap for each sampling port, one
or more pumps to draw sample electrolyte to the LPC module, and one
or more valves and associated controller for selectively delivering
the sample from particular ports at particular times.
[0008] In some embodiments, a liquid particle counter module is
designed to analyze electrolytes at a flow rate between about 2 and
250 mL/min, or at a flow rate between about 5 and 100 mL/min, or at
a flow rate between about 5 and 50 mL/min, or at a flow rate
between about 5 and 20 mL/min, or at a flow rate between about 9
and 11 mL/min. In some implementations, the liquid particle counter
module may be coupled to a drain. Thus, in some embodiments, the
measured sample may not necessarily be recycled to the plating
apparatus.
[0009] In some implementations, the liquid particle counter module
is configured to collect particles in size-based particle bins.
Example of particle size ranges for separate bins include the
following: between about 0.1 and about 0.15 .mu.m in diameter,
between about 0.15 and about 0.2 .mu.m in diameter, between about
0.2 and about 0.3 .mu.m in diameter, between about 0.3 and about
0.5 .mu.m in diameter, and greater than about 0.5 .mu.m in
diameter.
[0010] In some implementations, the sampling ports may be
strategically located on various points in the electrolyte
circulation system and/or the electroplating cell. The electrolyte
circulation system may include various types of fluidic elements
such as pumps. Sampling ports may be provided directly upstream
and/or directly downstream from a fluidic element under
consideration. The term "directly" used herein indicates that no
other processing fluidic element is located between the sampling
port and the fluidic element under consideration.
[0011] In certain embodiments, at least one of the sampling ports
is positioned directly downstream from a pump. Another sampling
port may be located upstream of the same pump. In some apparatus
designs, the electrolyte circulation system includes a second pump
and optionally a third pump, where additional sampling ports are
positioned directly downstream from the second pump and the
optional third pump.
[0012] The electrolyte circulation system may include a bath
reservoir, which may contain at least one of the sampling ports.
The electrolyte circulation system may include one or more
contactors (designed to degas electrolyte), and there may be a
sampling port positioned directly downstream from the contactor. In
certain embodiments, the electrolyte circulation system may include
one or more particle filters, each with its own (or with an
associated) sampling port positioned directly downstream from the
corresponding filter.
[0013] In certain embodiments, at least one of the sampling ports
may be positioned directly upstream from an electroplating cell. In
certain embodiments, at least one of the sampling ports is located
on the interior of at least one of the electroplating cells. In
certain embodiments, at least one of the sampling ports is located
proximate to a membrane in the interior of an electroplating cell.
Such membrane may be part of a Separated Anode Chamber or SAC as
further described below.
[0014] Certain aspects of the disclosure concern methods for
determining particle concentrations in an electrolyte present in an
electroplating apparatus including an electroplating cell, and an
electrolyte circulation system. The method may be characterized by
the following operations: (a) directing a sample of electrolyte
from a sampling port in the apparatus to a liquid particle counter
module; (b) determining the particle concentration at the sampling
port using the liquid particle counter module; and (c) modifying
operation of the electroplating apparatus to reduce the particle
concentration. In certain embodiments, modifying the operation of
the electroplating apparatus involves identifying a source of
particle contamination and replacing the source with a tool,
chemical, or component, as appropriate, to reduce the particle
concentration.
[0015] Accordingly, disclosed herein are electroplating apparatuses
for electroplating metal onto a semiconductor wafer. In some
embodiments, the apparatuses may include an electroplating cell for
containing an anode and an electrolyte during electroplating, an
electrolyte circulation system connected to the cell for
circulating electrolyte to and from the cell, one or more sampling
ports, and one or more liquid particle counter modules connected to
the one or more sampling ports for measuring particle concentration
in the electrolyte. In some embodiments, the one or more sampling
ports may include a first sampling port for taking a first sample
of electrolyte at a first location in the apparatus, and a second
sampling port for taking a second sample of electrolyte at a second
location in the apparatus. In some embodiments, an apparatus may
include a manifold connected to at least two sampling ports and to
at least one liquid particle counter module, and in certain such
embodiments, the apparatus may further include two or more valves
for controlling the flow of electrolyte from the at least two
sampling ports to the manifold, and in certain further embodiments,
a controller including machine readable instructions for
controlling the opening and closing of the two or more valves to
control the flow of electrolyte from the at least two sampling
ports to the manifold. In some embodiments, the apparatus may
further include a drain and at least one liquid particle counter
module may be connected to the drain.
[0016] In some embodiments, at least one of the LPC modules of the
electroplating apparatus may include a size-selective particle
collector having size-based bins for collecting particles. In
certain such embodiments, the size-based bins may include a first
bin for collecting particles between about 0.1 and 0.15 .mu.m in
diameter, a second bin for collecting particles between about 0.15
and 0.2 .mu.m in diameter, a third bin for collecting particles
between about 0.2 and 0.3 .mu.m in diameter, a fourth bin for
collecting particles between about 0.3 and 0.5 .mu.m in diameter,
and a fifth bin for collecting particles greater than about 0.5
.mu.m in diameter.
[0017] In some embodiments, an electroplating apparatus may further
include a pump, sampling ports located directly downstream and
upstream of the pump, and the apparatus may also include a
controller configured to (i) monitor the particle concentrations
upstream and downstream from the pump, (ii) determine when the pump
is producing more than a threshold amount of particles; and (iii)
generate an alert and/or modify operation of the apparatus when the
pump is producing more than the threshold amount of particles.
[0018] In some embodiments, there may be a sampling port located
within the interior of the electroplating cell, and the
electroplating apparatus may further include a controller
configured to (i) monitor the particle concentration within the
interior of the electroplating cell, (ii) determine when the
particle concentration in the electroplating cell is greater than a
threshold level; and (iii) generate an alert and/or modify
operation of the apparatus when the particle concentration in the
electroplating cell is greater than the threshold level.
[0019] In some embodiments, an electroplating apparatus having an
electroplating cell, an electrolyte circulation system, first and
second sampling ports for taking first and second samples of
electrolyte at first and second locations in the apparatus, and one
or more LPC modules connected to the sampling ports, may further
include a controller configured to (i) determine the approximate
particle concentration in the first sample using the one or more
liquid particle counter modules, (ii) determine the approximate
particle concentration in the second sample using the one or more
liquid particle counter modules, and (iii) modify the operation of
the electroplating apparatus to reduce particle concentration in
the electrolyte circulating to and from the electroplating cell. In
some embodiments, the controller may be further configured to
identify a source of particle contamination in the apparatus based
on the approximate particle concentrations in the first and second
samples, and in certain such embodiments, modifying the operation
of the electroplating apparatus may include diverting electrolyte
away from the source of particle contamination. Furthermore, in
certain such embodiments, the source of particle contamination may
be another electroplating cell of the electroplating apparatus, and
diverting electrolyte away from this cell may include closing one
or more valves to isolate this cell from the electrolyte
circulation system. In some embodiments, the controller may be
configured to direct the first sample of electrolyte from the first
sampling port to the one or more liquid particle counter modules,
and direct the second sample of electrolyte from the second
sampling port to the one or more liquid particle counter
modules.
[0020] In some embodiments, an electroplating apparatus having an
electroplating cell, an electrolyte circulation system, first and
second sampling ports for taking first and second samples of
electrolyte at first and second locations in the apparatus, and one
or more LPC modules connected to the sampling ports, may further
include a controller configured to (i) determine the approximate
particle concentration in the first sample using the one or more
liquid particle counter modules, (ii) determine the approximate
particle concentration in the second sample using the one or more
liquid particle counter modules, and (iii) send an alert to the
operator of the electroplating apparatus if the approximate
particle concentration in the first and/or second samples exceeds a
threshold, and/or if the magnitude of the difference between the
approximate particle concentrations in the first and second samples
exceeds a threshold.
[0021] Also disclosed herein are methods for reducing particle
concentration in an electrolyte present in an electroplating
apparatus having an electroplating cell and an electrolyte
circulation system for circulating electrolyte to and from the
electroplating cell. In some embodiments, the methods may include
(i) directing a first sample of electrolyte from a first sampling
port in the apparatus to one or more liquid particle counter
modules, (ii) determining the approximate particle concentration in
the first sample using the one or more liquid particle counter
modules, (iii) directing a second sample of electrolyte from a
second sampling port in the apparatus to the one or more liquid
particle counter modules, (iv) determining the approximate particle
concentration in the second sample using the one or more liquid
particle counter modules, and (v) modifying the operation of the
electroplating apparatus to reduce particle concentration in the
electrolyte present in the electroplating apparatus. In certain
such embodiments, modifying the operation of the electroplating
apparatus may include identifying a source of particle
contamination based on the approximate particle concentrations in
the first and second samples, and replacing the source of particle
contamination. Depending on the embodiment, the source of particle
contamination may be a chemical or a component within the
electroplating apparatus. In other embodiments, modifying the
operation of the electroplating apparatus may include diverting
electrolyte away from the source of particle contamination, and in
certain such embodiments, the source of particle contamination may
be an electroplating cell, and diverting electrolyte away from the
cell comprises closing one or more valves to isolate the cell from
the electrolyte circulation system.
[0022] These and other features of the disclosure are presented in
further detail below with reference to the associated drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1 illustrates an electroplating apparatus for
electroplating metal onto semiconductor wafers which includes three
electroplating cells, an electrolyte circulation system connected
to the three cells for circulating electrolyte to and from each,
and a liquid particle counter module.
[0024] FIG. 2 illustrates several embodiment sampling ports
configured to exclude air bubbles.
[0025] FIG. 3 shows results from an analysis of particles generated
by different brands of pumps, compared in terms of their particle
performance.
[0026] FIG. 4 shows a graphical representation of particle
concentrations measured while monitoring the electrolyte of an
electroplating apparatus correlated with a tool event log showing
times when additives were introduced into the electrolyte.
[0027] FIG. 5 shows an example of the correlation between particle
concentration and on-wafer defect count.
[0028] FIG. 6 shows an example of an electroplating apparatus
having an electroplating cell and an electrolyte circulation
system.
[0029] FIG. 7 shows an example of an electroplating cell having a
separated anode chamber.
[0030] FIG. 8 shows an example of an electroplating apparatus
having an electroplating cell, an electrolyte circulation system,
and a system for regulating pressure in one or more anode
chambers.
[0031] FIG. 9 schematically illustrates a method of reducing
particle concentration in an electrolyte present in an
electroplating apparatus.
DETAILED DESCRIPTION
[0032] In the following description, numerous specific details are
set forth in order to provide a thorough understanding of the
presented embodiments. The disclosed embodiments may be practiced
without some or all of these specific details. In other instances,
well-known process operations have not been described in detail to
not unnecessarily obscure the disclosed embodiments. While the
disclosed embodiments will be described in conjunction with the
specific embodiments, it will be understood that it is not intended
to limit the disclosed embodiments.
[0033] In this application, the terms "semiconductor wafer,"
"wafer," "substrate," "wafer substrate," and "partially fabricated
integrated circuit" are used interchangeably. One of ordinary skill
in the art will understand that these terms can refer to a silicon
wafer during any of many stages of integrated circuit fabrication
thereon. The following detailed description assumes the disclosed
implementations are implemented on a wafer substrate. However, the
disclosed implementations are not so limited. The work piece may be
of various shapes, sizes, and materials. In addition to
semiconductor wafers, other work pieces that may take advantage of
the disclosed implementations include various articles such as
printed circuit boards and the like.
[0034] Further, in this application, the terms "plating solution,"
"plating bath," "bath," "electrolyte solution," and "electrolyte"
are used interchangeably. One of ordinary skill in the art will
understand that these terms can refer to a solution containing
metal ions and possibly other additives for plating or
electroplating a metal onto a work piece.
[0035] Implementations disclosed herein are related to
configurations and methods of using plating tool hardware for
reducing defects on a wafer substrate during electroplating.
Implementations disclosed herein are applicable to electroplating
apparatus and methods designed for, e.g., 300 millimeter or 450
millimeter wafers seeded with a thin conductive seed layer. In some
embodiments, the methods and apparatuses described herein may be
used as an upgrade for deployed electroplating apparatuses such as
the Sabre.TM. tool available from Lam Research Corporation. In some
embodiments, the apparatus may be installed on existing field tools
and also on complete and/or newly manufactured electroplating
systems. The disclosed liquid particle counter systems permit end
users to monitor and maintain their electroplating apparatus's
health by, e.g., preventing costly scrapping of electroplated
wafers. In some embodiments, the disclosed system may also be used
by apparatus designers to identify problematic components which
introduce particles at levels that could introduce problematic
defects in electroplated wafers.
[0036] Embodiments disclosed herein are able to detect various
extraneous items in a liquid electrolyte. These items include
bubbles as well as solid particles. Collectively, bubbles, solid
particles, and other small defect producing items in an electrolyte
are referred to herein as "particles."
[0037] Particle detection may be performed in reference to various
components or fluidic features fluidically connected via an
electrolyte circulation system. The electrolyte circulation systems
described herein may include various fluidic features. Such fluidic
features may include, but are not limited to, fluid conduits
(including lines and weirs), filters, pumps, fluid inlets, fluid
outlets, valves, level sensors and flow meters. As can be
appreciated, any of the valves may include manual valves, air
controlled valves, needle valves, electronically controlled valves,
bleed valves and/or any other suitable type of valve. Any one or
more of these features can be a source of detrimental particles. To
this end, electrolyte may be analyzed for particles before and/or
after any one or more of these features.
[0038] FIG. 1 illustrates an apparatus 100 for electroplating metal
onto semiconductor wafers which includes three electroplating cells
14, an electrolyte circulation system connected to the three cells
for circulating electrolyte to and from each, and an LPC module
171. The electrolyte circulation system is schematically
illustrated in FIG. 1 by lines connecting the various components of
apparatus 100, such as bath reservoir 12, pumps 120, contactors
182, filters 186, to the electroplating cells 14, with the
electrolyte flow direction indicated by the arrows superimposed on
the lines. FIG. 1 also illustrates that in some embodiments, an
apparatus 100 may include an optional LPC module 172. The dashed
flow line shown in the figure indicates how the additional/optional
LPC module 172 may be fluidically connected to the rest of the
electrolyte circulation system.
[0039] FIG. 1 shows various sampling ports 180 as small circular
elements located at various locations in the apparatus 100 with
respect to the electrolyte circulation system. They are
individually labeled with alphabetical designations to distinguish
their different locations within the apparatus. The sampling ports
180 are for taking samples of electrolyte so that it may be
delivered to LPC module 171 and optionally LPC module 172 for
particle analysis. This particle analysis may involve real-time
measurement of particle concentrations in the electrolyte flowing
through the sampling ports to which the LPC module(s) are connected
so that particle concentration flowing through the various
components of apparatus 100 may be monitored (sometimes in
real-time). An electroplating apparatus, depending on the
embodiment, may employ any one, or two, or three, or more, or all
of the depicted sampling ports 180 shown in FIG. 1. Furthermore,
depending on the particular embodiment, more or fewer sampling
ports 180 than shown in FIG. 1 may be employed.
[0040] Among the elements or components of electroplating apparatus
100 which may be monitored are plating cells 14 (individually
labeled "Plating Cell" 1, 2, and 3 in the figure), pumps 120
(individually labeled "Pump" 1, 2, and 3 in the figure), and
contactors 182 (individually labeled "Contactor" in the figure).
Contactors are used to remove dissolved gases and/or bubbles from
the electrolyte. Other elements that may be monitored in apparatus
100 include the plating solution bath reservoir 12 (labeled "Bath"
in the figure), and filters 186 (individually labeled as "Filter"
in the figure). Sampling ports 180 for each of these elements are
connected to the LPC module by appropriate fluidic conduits as
schematically illustrated in FIG. 1.
[0041] The information on particle concentration and size
distribution from individual sampling locations by itself or in
conjunction with information from other sampling locations is used
to assess apparatus conditions. The scope of electroplating
apparatus condition assessment includes (but is not limited to) (1)
on-tool component performance, (2) on-tool chemistry condition, and
(3) on-wafer defect performance.
[0042] Categories of sampling port locations for LPC analysis
include at least the following:
[0043] 1. Electroplating cells
[0044] 2. Bath reservoir--e.g., a reservoir for holding the
electrolyte for one or more electroplating cells.
[0045] 3. Pumps
[0046] 4. Filters
[0047] 5. Contactors
[0048] In certain embodiments, the sampling ports are positioned
both upstream and downstream from a fluidic element under
consideration. In this manner, the elements can be isolated to
determine whether it is acting as a source of particles which are
contaminating the electrolyte.
[0049] Thus, in some embodiments, an electroplating apparatus may
have one or more pumps and may have one or more sampling ports
located directly downstream of the pumps. For example,
electroplating apparatus 100 shown in FIG. 1 has sampling ports 180
located directly downstream of pumps 120. In some embodiments, a
sampling port may be located directly upstream of a pump, or there
may be sampling ports located both directly upstream and directly
downstream of a pump. The latter configuration, for instance, may
allow a direct and unambiguous determination of the pump's
contribution to particle concentration in the electrolyte
solution.
[0050] Likewise, in some embodiments, an electroplating apparatus
may have one or more particle filters and may have one or more
sampling ports located directly downstream of the particle filters.
For example, electroplating apparatus 100 shown in FIG. 1 has
sampling ports 180 located directly downstream of filters 186. In
some embodiments, a sampling port may be located directly upstream
of a particle filter, or there may be sampling ports located both
directly upstream and directly downstream of a filter. The latter
configuration, for instance, may allow a direct and unambiguous
determination of the particle filter's effect on the particle
concentration in the electrolyte solution.
[0051] Likewise, in some embodiments, an electroplating apparatus
may have one or more contactors and may have one or more sampling
ports located directly downstream of the contactors. In some
embodiments, a sampling port may be located directly upstream of a
contactor, or there may be sampling ports located both directly
upstream and directly downstream of a contactor. The latter
configuration, for instance, may allow a direct and unambiguous
determination of the contactor's contribution to particle
concentration in the electrolyte solution. For example,
electroplating apparatus 100 shown in FIG. 1 has sampling ports 180
located directly upstream and downstream of contactors 182.
[0052] Likewise, in some embodiments, an electroplating apparatus
may include sampling ports located directly upstream and/or
directly downstream of one or more of the electroplating
apparatus's electroplating cells. However, sampling ports may be
located at any convenient position within the interior of an
electroplating cell as well. In certain such embodiments, a
sampling port may be located as close to the wafer as possible.
However, there are some specific locations in a SAC cell design
that have been found to be particularly useful:
[0053] (a) Above the SAC (separated anode chamber) membrane in the
wafer catholyte chamber. Such ports are useful for identifying
filter-generated particles. They may additionally identify
particles generated in situ in the cell by, e.g., precipitation.
Thus, an electroplating apparatus configured with a separated anode
chamber within an electroplating cell may have a sampling port
located proximate to, and downstream from, the membrane which
separates the separated anode chamber from the cathode chamber
within this electroplating cell.
[0054] (b) Near an ionically resistive channeled element (sometimes
called a HRVA and described below). In some embodiments, the
sampling port is located near an outer perimeter of and slightly
above the HRVA. Sampling ports in such locations are useful for
detecting bubble-related particles.
[0055] Sampling ports may also be located within, and/or upstream,
and/or downstream of the bath reservoir of an electroplating
apparatus, such as, for instance, bath reservoir 12 schematically
illustrated as part of electroplating apparatus 100 in FIG. 1. Bath
reservoirs can hold extra electrolyte which, as shown in FIG. 1,
may be circulated to and from one or more electroplating cells 14
within an electroplating apparatus 100. Sampling ports 180 in bath
reservoirs--such as the sampling port labeled `P` in FIG. 1--are
useful for identifying particle sources that are incoming chemicals
or degrading chemicals. Monitoring electrolyte in the bath
reservoir over time can suggest that certain chemical components of
the electrolyte are degrading to produce particles, etc.
[0056] The individual sampling ports 180 can be configured to
capture or exclude bubbles depending upon the location of the port.
A pump which operates by cavitation is a potential source of bubble
contamination. Therefore a sampling port located next to a pump
might be configured to capture bubbles as well as solid particles.
See for example, the A, B, and C sampling ports 180 directly
downstream from the #1, #2, and #3 pumps 120 in FIG. 1. However, a
sampling port located downstream from a filter--such as the G, H,
and I sampling ports 180 each located directly downstream from a
filter 186 in FIG. 1--may be configured to capture only solid
particles, as problematic filters are likely to produce particles
but not bubbles.
[0057] In certain embodiments, sampling ports designed to capture
bubbles are positioned at locations where bubbles are likely to
accumulate. For example, a sampling port may face downward and be
located near the top of a conduit or other fluidic element where
bubbles, through their natural buoyancy, tend to accumulate.
[0058] In other embodiments, where bubbles are to be excluded from
the sampling port, the port may be located at the bottom of the
fluidic element--or other location where bubbles are unlikely to
accumulate. Some examples are as shown in FIG. 2. Note that in
these examples, the inlet to the sampling port opens generally
upwards into the main fluid conduit so that bubbles flowing in the
main conduit would have to flow with a downward velocity component
to enter the sampling port--something which, due to the buoyancy of
the bubbles as stated above, tends not to occur.
[0059] LPC modules for the embodiments described herein may be
obtained from various sources. They may be specially constructed
for the applications described herein or they may be general
purpose tools. LPC modules are commercially available. In various
embodiments, suitable LPC modules are those that are marketed to
the chemical and medical industries. Particle Measuring Systems,
Lighthouse, and RION are some examples of vendors that manufacture
LPC modules. Of course, the disclosed embodiments are limited LPC
modules provided by these vendors.
[0060] In some embodiments, LPC modules use an optical detection
technique, which utilizes scattering effects to detect particles.
In various embodiments, the LPC module employs a laser beam passing
through a flowing or stagnant electrolyte sample. In some
embodiments, the wavelength is near-infrared or red (e.g., 633 nm).
The chosen wavelength is a function of the particle sizes to be
detected. Particles in the nanometer size range are detectable
using laser beams having relatively short wavelengths.
Photodetectors are located around the volume element near the
incident beam. Other particle detection mechanisms (i.e., those not
relying on light scatting) may be used as well.
[0061] In some embodiments, the LPC module ranges between about 10
to 20 inches on each side. The LPC module can be placed at any
convenient location on the electroplating apparatus, configured
such that the LPC is attached to a damper or other vibration
isolation mechanism.
[0062] An LPC module is fluidically connected to one or more
sampling ports via appropriate connections. In various embodiments,
the LPC module may be configured with a multiplex design where
multiple sampling ports are interrogated by a single LPC module. In
some implementations, one LPC module can only measure from one
sampling port at a time. Therefore, LPC measurements of particle
concentration at each of these ports are made serially. In some
implementations, certain sampling ports may be fluidically
connected to their own dedicated LPC modules which are devoted to
measuring particle concentration in the electrolyte sampled from
this sampling port.
[0063] FIG. 1, for example, illustrates bath reservoir 12 having
its internal electrolyte sampling port "P" fluidically connected to
a dedicated LPC module 172. Again, the dashed flow line
illustrating the fluidic connection between sampling port 180 and
LPC unit 172 expressly indicates the optional nature of additional
LPC module 172--though, it should of course be understood that many
of the specific details of the embodiment schematically illustrated
in FIG. 1 are also option (though not so explicitly indicated).
[0064] Oftentimes however, LPC modules are basically shared between
sampling ports. One way of accomplishing this is by way of a
manifold. Thus, as shown in FIG. 1, a manifold 188 may be used to
deliver the sample from various sampling ports 180 to LPC module
171. Of course, it will be understood by one of skill in the art
that there are other ways of accomplishing the sharing of LPC
modules such as through the use of suitable combinations of
circulation conduits and elements which may provide fluidic routes
for delivery of sample electrolyte from the various sampling ports
to a shared LPC module or modules.
[0065] If a manifold is used, the manifold may be connected to at
least two sampling ports and to at least one LPC module. The
manifold 188 shown in FIG. 1 includes multiple inlets from multiple
sampling ports 180 and a single outlet connected to LPC module 171.
The manifold 188 may be configured to conveniently switch which
sampling port or ports 180 LPC module 171 is monitoring, by
blocking or allowing flow of electrolyte through one or more of the
multiple inlets. For example, two or more valves may be used for
controlling the flow of electrolyte through the inlets (i.e., from
the at least two sampling ports to the manifold). Furthermore, as
discussed more fully below, in some embodiments, an apparatus 100
may include a controller which controls the opening and closing of
the two or more valves. In some embodiments, an LPC module may be
configured to sample electrolyte and measure the particle
concentration in the electrolyte at a rate between about 2 and 250
mL/min, or at a rate between about 5 and 100 mL/min, or at a rate
between about 5 and 50 mL/min, or at a rate between about 5 and 20
mL/min, or at a rate between about 9 and 11 mL/min, or more
particularly, at a rate of about 10 mL/min.
[0066] As shown in FIG. 1, in some embodiments, electrolyte sample
fluid may be directed to a drain 126 after it exits LPC module 171.
The same drain 126 may also be used to capture spent electrolyte
sample fluid after it exits optional LPC module 172. Sending the
sampled electrolyte fluid to a drain after particle measurement
rather than reintroducing back into the electrolyte circulation
system avoids the possibility of contamination resulting from
measurement in the LPC module eventually entering one or more of
the apparatus' electroplating cells.
[0067] In many implementations, the sampling system associated with
the LPC module contains different length conduits as necessary to
deliver sample from each of multiple sampling ports to the LPC
module for analysis. In some embodiments, short length conduits are
desirable to monitor a source of time-dependent particle
concentrations.
[0068] In one embodiment, the LPC module is configured to collect
particles at least 0.1 .mu.m in diameter. The LPC module also
collects particles in size-based particle bins such that a
distribution of the sizes of particles detected can be generated.
Examples of particle size ranges collected in such bins include:
between about 0.05 and 0.1 .mu.m in diameter, between about 0.1 and
about 0.15 .mu.m in diameter, between about 0.15 and about 0.2
.mu.m in diameter, between about 0.2 and about 0.3 .mu.m in
diameter, between about 0.3 and about 0.5 .mu.m in diameter, and
greater than about 0.5 .mu.m in diameter. In other embodiments, the
range of particle sizes detectable by the LPC module depend on the
LPC module selected for use in the apparatus.
[0069] In one configuration, the electroplating apparatus can
contain an LPC module connected to each sampling port. In another
configuration, the electroplating apparatus contains two LPC
modules, one arranged to continuously monitor the bath reservoir
and the other arranged to continuously monitor the electroplating
cell. The manifold or other LPC fluidic system is configured to
adjust the fluid delivery as needed such that samples from other
sampling ports in the electrolyte circulation system can be
analyzed to isolate a potential source of particle generation or
contamination or other defect cause. In some embodiments, at least
one of the LPC modules can be shared by two or more electroplating
cells, with the LPC fluidics system configured to deliver samples
to the LPC module from each of the electroplating cells.
[0070] Depending on the embodiment, there will also typically be a
computer program and/or coded logic (hereinafter referred to as
just "logic") associated with the one or more LPC modules which
generally works to control particle measurement operations,
process, store and analyze the measurements, and to generally
operate the LPC module, etc. The logic may be hardcoded into an
electronics unit or it may be implemented in software running on a
processor. Likewise, the logic may be integrated into the LPC
module itself, or it may be executed on a piece of hardware
distinct from, but in electronic communication with, the LPC
module.
[0071] In some embodiments, the logic associated with an LPC module
may control various fluid sampling parameters. For instance, the
logic may adjust sampling rate--e.g., the frequency at which
particle concentrations are measured from electrolyte samples by
the LPC module. Thus, in certain such embodiments, an LPC module
and its associated logic may generate a process signature of
particle concentrations in real time associated with a particular
process module/component--albeit represented by data at discretely
sampled points acquired at certain time intervals determined by the
aforementioned sampling rate. This measured signature--associated
with a particular component--may then be compared to one or more
predetermined signatures characteristic of that component to
determine whether the component is functioning within-spec as
expected. A detected and significant deviation from the
predetermined signature may then be treated as an alarm which may
be used to alert the operator of the apparatus of the anomalous (or
potentially anomalous) condition. Examples in the context of
identification of defective tools (e.g., a defective pump or
filter), detection of out-of-spec chemistries, etc. will be
discussed in greater detail below.
[0072] It should be noted, however, that although in some
embodiments this type of processing and analysis (or a portion
thereof) may take place on logic integrated into an LPC module or
modules, in other embodiments, some or all of this type of
processing and analysis may take place via logic which is
implemented on a system controller of the electroplating apparatus,
which, more generally, operates to control the overall functioning
of the electroplating system. System controllers will now be
discussed in greater detail, and in conjunction therewith, various
electroplating methods and apparatuses which modify their operation
in response to particle concentrations measured by one or more LPC
modules.
[0073] Nevertheless, it is to be understood that the data
processing and analysis logic used to implement these techniques
and methodologies may reside on the LPC module itself, or on the
system controller, or on some other data processing module within
the electroplating apparatus, or on an external data processing
apparatus, or on any combination of the foregoing. Thus, for
example, in a particular embodiment, various logic modules may be
located on the one or more LPC modules themselves as well as on the
system controller--which then operate in a cooperative manner to
modify the operation of the electroplating apparatus or send an
alert in response to out-of-spec particle concentrations measured
by the one or more LPC modules.
[0074] System Controllers and Logic for Modifying Operations in
Response to Particle Concentrations Measured by LPC Module(s)
[0075] Thus, various embodiments include a system controller having
logic for controlling process operations in accordance with the
present invention. For example, a system controller may be coupled
to an electroplating apparatus and configured to control some or
all aspects of electroplating operations including monitoring and
reacting to particle concentration measurements made by one or more
LPC modules, feeding anolyte and catholyte, bleeding the catholyte,
delivering anolyte to catholyte, etc.
[0076] In some embodiments, the system controller is also
configured to adjust parameters of the system in response to
signals received from the various components of the system and, in
particular, the one or more LPC modules. Such parameters may
include, for example, flow rates in the electrolyte circulation
system, timing of dosing, opening and closing of valves to control
electrolyte flow, controlling opening and closing of valves
relating to the manifold (see, e.g., manifold 188 in FIG. 1) in
order to control which sampling ports (see, e.g., 180 in FIG. 1)
have their sampled fluid directed to one or more LPC modules (see,
e.g., LPC module 171 in FIG. 1), etc. For example, concentrations
of particles and/or plating bath components can be monitored in
anolyte and/or catholyte using a variety of sensors and titrations
(e.g., pH sensors, voltammetry, acid or chemical titrations,
spectrophotometric sensors, conductivity sensors, density sensors,
etc.). In some embodiments the concentrations of electrolyte
components are determined externally using a separate monitoring
system, including an LPC module, which reports them to the system
controller. In other embodiments raw information collected from the
system is communicated to the controller which conducts
concentration determinations from the raw data. In either case, the
system controller may be configured to shut down the apparatus,
collect further information (e.g., particle concentrations at
particular locations), and adjust dosing parameters or flow
parameters in response to these signals and/or concentrations such
as to maintain homeostasis in the system. Further, in some
embodiments, volume sensors, fluid level sensors, and pressure
sensors may be employed to provide feedback to the controller. In
certain embodiments, a pump control may be directed by an algorithm
making use of signals from the one or more LPC modules and/or the
level sensor(s) in a pressure regulating device.
[0077] Typically, a system controller will include one or more
memory devices and one or more processors configured to implement
and execute logic so that the apparatus may perform a method in
accordance with the present disclosure. Machine-readable media
containing instructions for controlling process operations in
accordance with the present invention may be coupled to the system
controller.
[0078] Various techniques, algorithms, and/or methodologies for
modifying the operation of an electroplating apparatus in response
to particle concentration measurements will now be disclosed in the
context of a system controller--with the understanding (as
discussed above) that the instant disclosure encompasses these
concepts wherever the logic embodying and implementing these
concepts happens to physically reside.
[0079] For example, in some embodiments, the system controller
first directs one or more LPC modules to determine whether there
are an excessive concentration of particles in the electroplating
cell. This information may directly correlate with process
performance because, as explained above, high particle
concentration in the electroplating cell generally result in wafer
defects and poor electroplating performance. The LPC module (or
modules) used to determine particle concentration in the
electroplating cell may be fluidically connected to a sampling port
located in the electrolyte circulation system directly downstream
from the electroplating cell, or the sampling port may be located
within the interior of the electroplating cell. In some embodiments
wherein the electroplating cell has a separated anode chamber (as
described elsewhere herein), the sampling port may be located
proximate to, and downstream from, a membrane separating the
separated anode chamber from the cathode chamber within the
electroplating cell. In any event, the system controller may be
configured to monitor the particle concentration within the
interior of the electroplating cell via one or more LPC modules
connected to one or more of the aforementioned sampling ports, and
determine when the particle concentration in the electroplating
cell is greater than a threshold level. If a predetermined
threshold is exceeded, the system controller may be configured to
generate an alert and/or modify operation of the apparatus.
Furthermore, in some embodiments, due to the importance of particle
count in the electroplating cell itself, the one or more LPC
modules and system controller may be configured to sample the
particle concentration more frequently at the location of the wafer
in the electroplating cell. (Sampling rates for particle
concentration measurements are discussed above.)
[0080] Moreover, in some embodiments, if a high particle
concentration is detected in an electroplating cell (as just
described), the system controller may additionally be configured to
direct the operation of various LPC modules located in the
electrolyte circulation system to measure particle concentrations
upstream and downstream from various components in an effort to
determine which component in the apparatus is potentially most
responsible for generating the high particle concentration. In this
manner, the logic employed on the system controller may work at
attempting to isolate the source of the problem. Certain aspects of
this process are explained below in greater detail and in specific
contexts.
[0081] I. LPC Monitoring of on-Tool Component Performance
[0082] Each module/component on an electroplating apparatus may be
monitored in terms of particle performance (generation, filtration,
accumulation, etc.). If a module/component is known or suspected to
be generating an excessive amount of particles, one or more LPC
modules may be assigned to monitor the particle concentrations of
electrolyte samples from sampling ports located directly upstream
and downstream of the suspect component. The particle generation
rate can then be calculated based on the difference between the two
LPC readings--e.g., if the magnitude of the difference between the
approximate particle concentrations in the upstream and downstream
samples exceeds a threshold value, an alert can be triggered or the
operation of the apparatus modified. Similarly, for a
component/module which is designed to (or known to) filter out
particles, LPC modules can be assigned to monitor the particle
concentrations upstream and downstream from the particular
component/module respectively and the particle filtration rate can
be calculated based on the difference between the two LPC readings.
If a module is known or suspected to accumulate particles, LPC
modules can be assigned to monitor the particle concentration
before and after the particular module respectively and the
particle retention rate can be calculated based on the difference
between the two LPC readings. When the LPC monitoring shows a
deviance from the acceptable baseline range the module or component
needs to be repaired or replaced. This method can also be applied
to compare performance of different brands or models of a given
component so that a component of superior performance can be
selected for use in the electroplating apparatus.
[0083] A pump is a useful example for illustrating how an LPC
module is used to evaluate and screen pump performance. FIG. 3
shows results from analysis concerning particles generated by
different brands of pumps. Two types of pumps were compared in
terms of their particle performance. To calculate the particles
generated by the pump, LPC modules were used to sample electrolyte
from the pump outlet (i.e., monitor particle concentration directly
downstream of the pump) and inlet on each pump (i.e., monitor
particle concentration directly upstream of the pump),
simultaneously. The difference between the pump outlet and pump
inlet rate is the pump particle generation rate. As shown, pump B
demonstrated significantly less particle generation than pump
A.
[0084] A similar approach may be implemented in a system controller
and used for monitoring the particle performance of pumps or other
on-tool components (e.g., filter, degasser, contactor, etc.) over
time. Such real-time component monitoring can identify performance
issues before they mature and therefore prevent catastrophic
failure events from occurring. For example, in conventional
electroplating systems, pump performance is largely not monitored.
Conventionally, pumps are replaced when the pumps fails or when it
reaches its recommended life-span. For the former case, before a
pump fails, it can generate elevated particle concentration for
prolonged length of time, which negatively affects defect and yield
performance of the electroplating tool. For the latter case, the
recommended life-span is suggested for an average pump based on
different criteria. For a particular pump, the recommended
life-span can be too early or late. As shown in FIG. 3, the data
collected demonstrates the potential wide variation in pump
performance. Therefore, monitoring of pump operation via system
controller and LPC module(s) can potentially assess pump
performance on an individual basis, potentially achieving an
improved cost/performance balance.
[0085] Accordingly, in order to monitor individual components of an
electroplating apparatus and to identify performance issues before
they mature into severe failure events, in some embodiments, an
electroplating apparatus may employ a sampling port located
directly downstream of a component, a sampling port located
directly upstream of the component, and a system controller
configured to monitor the particle concentrations upstream and
downstream from the component. By this monitoring, the system
controller may be configured to determine if and when the component
is producing more than a threshold amount of particles, and if so,
having identified a source of particle contamination, generate an
alert and/or modify the operation of the electroplating apparatus
in response. Operational modification may be, for example, to
execute logic which diverts electrolyte away from the source of
particle contamination, logic which removes the offending component
from the electrolyte circulation system, logic which sends an alert
to the operator of the electroplating apparatus that the component
requires replacement, or perhaps logic which shuts down the
electroplating apparatus until maintenance can be performed to
avoid potential destruction of valuable wafers. In some cases, the
source of particle contamination may be another electroplating cell
and diverting electrolyte away from this cell may include closing
one or more valves to isolate the offending cell from the rest of
the electrolyte circulation system.
[0086] As indicated above, the component may be a pump, but it may
be another type of component as well, as described above. For
instance, if the component is a filter, the relevant consideration
may be whether or not the filter is sufficiently reducing the
number of particles in the electrolyte passing through the filter.
In such a case, with respect to monitoring the filter, the
controller may be configured to monitor the particle concentrations
upstream and downstream from the filter, and be configured to
determine when the filter is failing to reduce the amount of
particles below a threshold level or to reduce particle number such
that the ratio of particles in the downstream electrolyte versus
the upstream electrolyte is below a threshold ratio. If so
determined, the controller may be configured to generate an alert
and/or modify the operation of the electroplating apparatus in
response. For example, by sending an alert to the operator of the
electroplating apparatus to replace the offending filter.
[0087] II. LPC Monitoring of on-Tool Chemistry Condition
[0088] Various chemicals are delivered to an electroplating cell to
enable the electroplating process. A major concern for
electroplating is the presence of both minute particles in the
incoming chemicals and particles generated from the interaction
between chemicals in various chemical and ambient environments
(air, temperature, etc.), and during the electroplating process.
Chemistry conditions can be monitored in real-time by employing LPC
sampling at proper locations.
[0089] FIG. 4 provides a graphical representation of particle
concentrations while monitoring the bath of an electroplating tool.
Spikes of particle concentration appeared at varied time intervals,
suggesting a source of contamination coming into the solution
reservoir. The source of contamination can be identified by
correlating the LPC data with a tool event log. The labeled boxes
in FIG. 4 correspond to the additives that were introduced into the
bath at the various times when spikes of particle concentration
appeared. In this case, an additive A was diagnosed as the source
of contamination. Further investigation showed that additive A had
degraded and was no longer suitable to be used on the tool. As
shown in the example, chemistry issues can be identified in a
timely fashion by implementing LPC monitoring. As a result,
discovering when a tool's condition is not fit for wafer processing
helps prevent wasting valuable resources.
[0090] III. LPC Monitoring and its Direct Matching to on-Wafer
Defect Performance
[0091] On-wafer defect performance is a metric for electroplating
tools. Minute particles are one of the main causes of on-wafer
defects. A conventional method of obtaining on-wafer defect data is
to measure processed wafers with various stand-alone metrology
tools, typically hours after wafers have been plated in production.
As a result, in the event of a defect excursion, the event would
not be discovered until hours after a problem arose, during which
both numerous wafers and tool time are wasted. However, by
implementing LPC sampling at proper locations, particle data which
qualitatively and quantitatively correlates to on-wafer defects in
real-time as the wafers are plated can be obtained. FIG. 5
illustrates such an example. An increased trend of solid particle
concentration was observed during wafer plating (solid lines),
which was confirmed by subsequent examination of processed wafers
on metrology tools (yellow dots). As demonstrated in the plot, the
LPC data matches remarkably well with on-wafer defect count. Since
the particle concentration data from the LPC module is given in
real-time, detection of a defect excursion event is possible at the
earliest possible time, and therefore prevents wasting valuable
resources, and enables timely troubleshooting defect causes.
[0092] Example Electroplating Cells and Apparatuses with
Recirculation Systems
[0093] Specific examples of electroplating cells and apparatuses
with recirculation systems which may incorporate sampling ports and
LPC modules as described above will now be presented in detail with
reference to FIGS. 6-8.
[0094] One example of a suitable electroplating apparatus with a
recirculation system is described in detail in U.S. application
Ser. No. 13/051,822 titled "ELECTROLYTE LOOP FOR PRESSURE
REGULATION FOR SEPARATED ANODE CHAMBER OF ELECTROPLATING SYSTEM"
filed on Mar. 18, 2011 and naming Rash et al. as inventors, which
is incorporated herein by reference in its entirety. Other suitable
electroplating apparatus is described in U.S. application Ser. No.
13/305,384 titled "ELECTROPLATING APPARATUS AND PROCESS FOR WAFER
LEVEL PACKAGING" filed on Nov. 28, 2011 and naming Mayer et al. as
inventors, which is incorporated herein by reference in its
entirety.
[0095] An example of an electroplating apparatus including an
electroplating cell and an electrolyte circulation system will now
be described. Referring to FIG. 6, an electroplating system 10
includes a dosing system 11 that alters the chemical composition of
a plating bath 12 in the solution reservoir. A sampling port (not
shown) may be located on the interior of the solution reservoir and
connected to an LPC module. Anode and cathode electrolyte delivery
systems 13-1 and 13-2 respectively deliver anode and cathode
electrolyte (sometimes referred to as "anolyte" and "catholyte"
respectively) to an electroplating cell 14. A sampling port (not
shown) may be located on the interior of the electroplating cell
14, separately connected to an LPC module. Plating solution may
also be returned from the electroplating cell 14 to the plating
bath 12 in the solution reservoir by the anode and cathode
electrolyte delivery systems 13-1 and 13-2, respectively.
[0096] For example only, the anode electrolyte delivery system 13-1
may be a closed loop system that circulates anode electrolyte.
Excess anode electrolyte may be returned to the plating bath 12 as
needed. The cathode electrolyte delivery system 13-2 may circulate
and return plating solution from the plating bath 12 in the
solution reservoir. As described further below, the anolyte
delivery system may also be an open loop system.
[0097] Referring now to FIG. 7, an exemplary electroplating cell 14
is shown. While the electroplating cell 14 is shown as a separated
anode chamber (SAC) electroplating cell, skilled artisans will
appreciate that other types of electroplating cells can be used.
The electroplating cell 14 includes a cathode chamber 18 and an
anode chamber 22, which are separated by a membrane 24. While a
membrane 24 is shown, other boundary structures may be employed
including sintered glass, porous polyolefins, etc. A sampling port,
if present, may be configured to take sample catholyte from cathode
chamber 18 and provide such catholyte to an LPC module. The
electroplating cell may need to be modified to accommodate the
sampling port.
[0098] Further, the membrane may be omitted in some
implementations. In various embodiments, the electrolyte in the SAC
is an aqueous solution of between about 10 and 50 gm/l copper and
between 0 and about 200 gm/l H.sub.2SO.sub.4.
[0099] The membrane 24 may be supported by a membrane frame (not
shown). For example only, the membrane 24 may be electrically
dielectric and may include micro-porous media that is resistant to
direct fluid transport. For example only, the membrane 24 may be a
cationic membrane. For example only, the cationic membrane may
include membranes sold under the trade name Nafion.RTM., which are
available from Dupont Corporation of Wilmington Del. Electroplating
apparatuses having membranes for forming separated anode chambers
are described in U.S. Pat. No. 6,527,920 issued to Mayer et al.,
and U.S. Pat. Nos. 6,126,798 and 6,569,299 issued to Reid et al.,
which are all herein incorporated by reference in their
entireties.
[0100] The cathode and anode chambers 18 and 22 may include cathode
electrolyte and anode electrolyte flow loops, respectively. The
cathode electrolyte and anode electrolyte may have the same or
different chemical compositions and properties. For example only,
the anode electrolyte may be substantially free of organic bath
additives while the cathode electrolyte may include organic bath
additives.
[0101] An anode 28 is arranged in the anode chamber 22 and may
include a metal or metal alloy. For example only, the metal or
metal alloy may include copper, copper/phosphorous, lead,
silver/tin or other suitable metals. In certain embodiments, anode
28 is an inert anode (sometimes referred to as a "dimensionally
stable" anode). The anode 28 is electrically connected to a
positive terminal of a power supply (not shown). A negative
terminal of the power supply may be connected to a seed layer on
the substrate 70.
[0102] Flow of anode electrolyte is fed into the anode chamber 22
as shown by arrow 38 via a central port and passing through anode
28. Optionally, one or more flow distribution tubes (not shown) are
used to deliver anolyte. When used, the flow distribution tubes may
supply anode electrolyte in a direction towards a surface of the
anode 28 to increase convection of dissolved ions from the surface
of the anode 28. Optionally, a second sampling port (not shown) may
be connected to the central port or flow distribution tube (not
shown) directly upstream of the electroplating cell 14 to deliver
sample electrolyte to an LPC module (not shown).
[0103] The flow of anode electrolyte exits the anode chamber 22 at
30 via manifolds 32 and returns to an anode electrolyte bath (not
shown) for recirculation. In some implementations, the membrane 24
may be conically-shaped to reduce collection of air bubbles at a
central portion of the membrane 24. In other words, the anode
chamber ceiling has a reverse conical shape. A return line for
plating solution may be arranged adjacent to radially outer
portions of the membrane.
[0104] While the anode 28 is shown as a solid, the anode 28 may
also include a plurality of metal pieces such as spheres or another
shape (not shown) arranged in a pile (not shown). When using this
approach, an inlet flow manifold may be arranged at a bottom of the
anode chamber 22. Flow of the electrolyte may be directed upward
though a porous anode terminal plate.
[0105] The anode electrolyte may be optionally directed by one or
more of the flow distribution tubes onto a surface of the anode 28
to reduce a voltage increase associated with the build-up or
depletion of dissolved active species. This approach also tends to
reduce anode passivation.
[0106] The anode chamber 22 and the cathode chamber 18 are
separated by the membrane 24. Cations travel from the anode chamber
22 through the membrane 24 and the cathode chamber 18 to the
substrate 70 under the influence of the applied electric field. The
membrane 24 substantially blocks diffusion or convection of
non-positively charged electrolyte components from traversing the
anode chamber 22. For example, the membrane 24 may block anions and
uncharged organic plating additives.
[0107] The cathode electrolyte supplied to the cathode chamber 18
may have different chemistry than the anode electrolyte. For
example, the cathode electrolyte may include additives such as
accelerators, suppressors, levelers, and the like. For example
only, the cathode electrolyte may include chloride ions, plating
bath organic compounds such as thiourea, benzotrazole,
mercaptopropane sulphonic acid (MPS), dimercaptopropane sulphonic
acid (SPS), polyethylene oxide, polyproplyene oxide, and/or other
suitable additives.
[0108] Cathode electrolyte enters the cathode chamber 18 at 50 and
travels through a manifold 54 to one or more flow distribution
tubes 58. While flow distribution tubes 58 are shown, the flow
distribution tubes 58 may be omitted in some implementations. For
example only, the flow distribution tubes 58 may include a
non-conducting tubular material, such as a polymer or ceramic. For
example only, the flow distribution tubes 58 may include hollow
tubes with walls composed of small sintered particles. For example
only, the flow distribution tubes 58 may include a solid walled
tube with holes drilled therein.
[0109] One or more of the flow distribution tubes 58 may be
oriented with openings arranged to direct fluid flow at the
membrane 24. A sampling port (not shown) may be located within
chamber 18 and samples of the fluid flow are delivered to an LPC
module (not shown) for analysis. The flow distribution tubes 58 may
also be oriented to direct fluid flow to regions in the cathode
chamber 18 other at the membrane 24. A discussion of plating
apparatus having fluted flow distribution tubes is contained in
U.S. patent application Ser. No. 12/640,992 filed Dec. 17, 2009 by
Mayer et al. and incorporated herein by reference in its
entirety.
[0110] The electrolyte eventually travels through a flow diffuser
60 and passes near a lower surface of a substrate 70. The
electrolyte exits the cathode chamber 18 over a weir wall 74 as
shown by arrows 72 and is returned to the plating bath.
[0111] For example only, the flow diffuser 60 may include a
micro-porous diffuser, which is usually greater than about 20%
porous. Alternately, the flow diffuser may include an ionically
resistive channeled plate, also sometimes called a high resistance
virtual anode (HRVA) plate, such as one shown in U.S. Pat. No.
7,622,024, issued Nov. 24, 2009, which is hereby incorporated by
reference in its entirety. A sampling port can be located near the
outer perimeter of and slightly above the ionically resistive
channeled plate and connected to an LPC module for detecting
particles. Placing sampling ports in such locations is useful for
detecting bubble-related particles. The channeled plate is
typically less than about 5% porous and imparts higher electrical
resistance. In other implementations, the flow diffuser 60 may be
omitted.
[0112] Various patents describe electroplating apparatus containing
separated anode chambers (SAC) that may be suitable for practice
with the embodiments disclosed herein. These patents include, for
example, U.S. Pat. Nos. 6,126,798, 6,527,920, and 6,569,299, each
previously incorporated by reference, as well as U.S. Pat. Nos.
6,821,407 issued Nov. 23, 2004, and 6,890,416 issued May 10, 2005,
both incorporated herein by reference in their entireties. The
disclosed embodiments may also be practiced with apparatus and
methods designed for simultaneously depositing two or more elements
(e.g., tin and silver) such as those described in U.S. patent
application Ser. No. 13/305,384, filed Nov. 28, 2011, and titled
"ELECTROPLATING APPARATUS AND PROCESS FOR WAFER LEVEL PACKAGING,"
which is hereby incorporated by reference in its entirety for all
purposes.
[0113] In various embodiments, the electroplating apparatus used
with the systems described herein has a "clamshell" design. A
general description of a clamshell-type plating apparatus having
aspects suitable for use with this invention is described in detail
in U.S. Pat. No. 6,156,167 issued on Dec. 5, 2000 to Patton et al.,
and U.S. Pat. No. 6,800,187 issued on Oct. 5, 2004 to Reid et al.,
which are incorporated herein by reference for all purposes.
[0114] Referring now to FIG. 8, an exemplary system 90 for
regulating pressure in one or more anode chambers is shown. First
and second anode chambers 22-1 and 22-2 include membranes 24-1 and
24-2, respectively arranged between the anode chamber and a
corresponding cathode chamber. The system 90 according to the
present disclosure significantly reduces the difficulty of bubble
removal as well as regulates pressure in the anode chambers 22-1
and 22-2 without requiring precision pumps and/or pressure
feedback, which reduces cost and complexity.
[0115] Deionized (DI) water source 100 provides deionized water via
a valve 112 to a conduit 114, which may include a sampling port. A
plating solution source 104 provides plating solution or
electrolyte via a valve 108 to the conduit 114. In some
embodiments, the apparatus includes a sampling port immediately
downstream from plating solution source. The plating solution may
be virgin makeup solution (VMS). For a discussion of one
implementation for dosing with VMS and DI water, see, e.g., U.S.
patent application Ser. No. 11/590,413, filed Oct. 30, 2006, and
naming Buckalew et al. as inventors, which is incorporated herein
by reference in its entirety. A pump 120 has an input in fluid
communication with the conduit 114. An output of the pump 120
communicates with an input of a filter (not shown) via conduit 121.
A sampling port (not shown) may be connected to conduit 121 and
delivers samples of fluid via conduit (not shown) to an LPC module
(not shown) for particle detection. In many embodiments, this
filter may be unnecessary as all the filtering is handled by a
filter 164.
[0116] A conduit 124 connects to conduits 128 and 130, which are
connected to the anode chambers 22-1 and 22-2, respectively. A
drain valve 126 may be used to drain fluid from the conduit 124. As
can be appreciated, the drain valve 126 may be positioned at other
locations in the electroplating circulation system. For example, it
may be incorporated into a variant of valve 108, which variant is a
three-way valve. Conduits 132 and 134 receive electrolyte from the
anode chambers 22-1 and 22-2, respectively. A conduit 136 connects
the conduits 132 and 134 to a pressure regulating device 138. A
sampling port (not shown) may be located on conduit 136 and
connected to the LPC module.
[0117] The pressure regulating device 138 includes a housing 140
including an inlet 142 arranged on or near a bottom surface 141
thereof. The inlet 142 communicates with a vertical tubular member
144, which includes an inlet 145 and an outlet 146. The housing 140
further includes a first outlet 147 that is spaced from the inlet
142 on or near the bottom surface 141 of the housing 140. The
housing 140 further includes a second outlet 152 near an upper
portion 153 of the housing 140.
[0118] In various embodiments, the pressure regulating device is
exposed to atmospheric pressure. In other words, it is "open" and
thereby creates an open loop for anolyte recirculation. Exposure to
atmospheric pressure may be accomplished by, for example, providing
vent holes or other openings in housing 140. In other cases, an
electrolyte outlet pipe (e.g., conduit 154) may have an opening to
allow atmospheric contact with the electrolyte. In a specific
embodiment, the outlet conduit delivers electrolyte into a trough,
which is of course exposed to atmospheric pressure. Additional
details of a pressure regulating device suitable for some
implementations is described in U.S. patent application Ser. No.
13/051,822, filed on Mar. 18, 2011, which is incorporated herein by
reference in its entirety.
[0119] In the depicted embodiment, the pressure regulating device
138 further includes filter medium 164. The filter medium 164 may
include porous material that filters bubbles from the electrolyte.
The filter medium 164 may be positioned in a horizontal position as
shown or in any other suitable position to filter bubbles and/or
particles from the anode electrolyte before the anode electrolyte
returns to the anode chambers 22-1 and 22-2. More general, other
forms of bubble separation devices may be employed. These include
thin sheets of porous material such as "Porex".TM. brand filtration
products (Porex Technologies, Fairburn, Ga.), meshes, activated
carbon, etc.
[0120] In some implementations, the filter medium 164 may be
arranged outside of the housing 140 in line with the conduit 121 or
another conduit. In other implementations, the filter medium 164
may be arranged at an angle between horizontal and vertical. In
still other implementations, the filter medium 164 may be arranged
in a vertical position and the outlet may be arranged on a side
wall of the housing 140. Still other variations are
contemplated.
[0121] In a specific embodiment, filter 164 has a sleeve shape and
fits over tubular member 144. It may fit from top to bottom over
the sleeve or over at least a substantial fraction of the height.
In some cases, the filter includes a sealing member such as an
o-ring disposed at a location on the inner circumference of the
filter and mating with the tubular member 144. The filter is
configured to remove particles and/or gas bubbles from the
electrolyte before delivering the electrolyte to outlet 147. For
bubble management, it may be sufficient that the filter have pores
sized at approximately 40 micrometers or smaller, or in some cases
sized at approximately 10 micrometers or smaller. In a specific
embodiment, the average pore size is between about 5 and 10
micrometers. Such filters have the additional benefit of removing
very large particles. As an example, suitable filters may be
obtained from Parker Hannifin Corp., filtration division,
Haverhill, Mass. (e.g., a 5 micron pore size pleated polypropylene
filter part number PMG050-9FV-PR). In some designs, the outer
diameter of the filter will be between about 2 and 3 inches.
Further, the filter size may be chosen so that some space remains
between the filter and the outer housing of the pressure regulator.
Such a gap can allow easier and more reliable tuning of level
sensors in the pressure regulator. In some embodiments, the
regulator housing and the filter are sized so that a gap of about
0.2 to 0.5 inches remains between them.
[0122] The first outlet 147 communicates with a conduit 148, which
returns anode electrolyte and completes an anode electrolyte flow
loop. A sampling port (not shown) may be located on conduit 138 and
connected to the LPC module. A conduit 154 connects the second
outlet 152 to the plating bath 12 in a solution reservoir to handle
overflow of anode electrolyte as needed. In some cases, as
indicated above, the conduit 154 empties into a trough (not shown)
prior to reaching a solution reservoir for holding plating bath
12.
[0123] In some implementations, the inlet 145 of the vertical
tubular member 144 is vertically located below at least a portion
of the membranes 24-1 and 24-2. The outlet 146 of the vertical
tubular member 144 is located above the membranes 24-1 and
24-2.
[0124] In certain embodiments, the plating bath 12 in a solution
reservoir provides catholyte to the cathode chambers. Because the
electrolyte provided to the plating bath from pressure regulator
138 is anolyte, which may be without plating additives, the
composition of electrolyte in the plating bath may require
adjustment prior to delivering to the cathode chambers. For
example, some plating additives may be dosed into the plating bath
in while held in a solution reservoir.
[0125] In use, the anode chambers 22-1 and 22-2 may be initially
filled with plating solution and/or deionized water. The pump 120
may be turned on to provide flow. In some implementations, the pump
120 may provide approximately 2-4 liters per minute. The pump 120
causes variations in the pressure of the electrolyte in the anode
chambers 22. Additionally, delivery of fresh plating solution from
source 104 may introduce transient increases in the anolyte
pressure within chambers 22. As the pressure in the anode chamber
22 increases, electrolyte flows out of the vertical tubular member
144 and down an outer surface of the vertical tubular member 144.
The electrolyte flows through the filter medium 164 (if present)
and out the outlet 147.
[0126] Methods of Reducing Particle Concentration in Electroplating
Apparatuses
[0127] Several methods will now be described for reducing particle
concentration in an electrolyte present in an electroplating
apparatus. These methods relate to the various techniques described
above for modifying the operation of an electroplating apparatus in
response to particle concentration measurements, which were
discussed above within the context of logic implemented on an
electroplating apparatus's system controller or other hardware. It
should be appreciated, however, that in many cases, the methods
described here could be implemented via logic (either as software
or hard-coded) residing on an electroplating apparatus's system
controller or another device in electronic communication with the
LPC modules of an electroplating apparatus. Similarly, it should be
appreciated that the techniques, methodologies, and/or algorithms
described above with reference to a system controller could also be
characterized as methods performable independent of the context of
a system controller or other specific hardware.
[0128] Accordingly, some methods for reducing particle
concentration in an electrolyte present in an electroplating
apparatus are performed in the context of an apparatus having an
electroplating cell and an electrolyte circulation system for
circulating electrolyte to and from the cell as these
components/modules are described herein. FIG. 9 schematically
illustrates certain such methods. For example, in reference to FIG.
9, a method 900 may include directing (910) a first sample of
electrolyte from a first sampling port in such an apparatus to one
or more liquid particle counter (LPC) modules, followed by
determining (920) the approximate particle concentration in the
first sample using the one or more LPC modules. In certain such
embodiments, the method 900 may further include directing (930) a
second sample of electrolyte from a second sampling port in the
apparatus to the one or more LPC modules, and determining (940) the
approximate particle concentration in the second sample using the
one or more LPC modules. Finally, in certain such embodiments, the
method may conclude by modifying (950) the operation of the
electroplating apparatus to reduce particle concentration in the
electrolyte present in the electroplating apparatus.
[0129] The operation of the electroplating apparatus may be
modified in various ways in order to reduce particle concentration
depending on the methodology employed. In some embodiments,
modifying the operation of the electroplating apparatus to reduce
particle concentration may include identifying a source of particle
contamination based on the approximate particle concentration in
the first sample and the approximate particle concentration in the
second sample, and replacing the source of particle contamination.
For instance, a pump may be producing an excessive number of
particles, as described above, and modification of the apparatus
may include replacing the pump. In other embodiments, modifying the
operation of the electroplating apparatus to reduce particle
contamination may include identifying the source of the
contamination as just described and diverting electrolyte away from
the source of particle contamination. For instance, if one of
several electroplating cells in an electroplating apparatus is
generating excessive particle contamination, electrolyte may be
diverted away from it by closing one or more valves to isolate the
cell from the electrolyte circulation system (as described
above).
[0130] Lithographic Patterning Tools and Processes
[0131] The apparatus and processes described hereinabove may be
used in conjunction with lithographic patterning tools or
processes, for example, for the fabrication or manufacture of
semiconductor devices. Typically, though not necessarily, such
tools/processes will be used or conducted together in a common
fabrication facility. Lithographic patterning of a film typically
comprises some or all of the following steps, each step enabled
with a number of possible tools: (1) application of photoresist on
a workpiece, i.e., substrate, using a spin-on or spray-on tool; (2)
curing of photoresist using a hot plate or furnace or UV curing
tool; (3) exposing the photoresist to visible or UV or x-ray light
through a mask using a tool such as a wafer stepper; (4) developing
the resist so as to selectively remove resist and thereby pattern
it using a tool such as a wet bench; (5) transferring the resist
pattern into an underlying film or workpiece by using a dry or
plasma-assisted etching tool; and (6) removing the resist using a
tool such as an RF or microwave plasma resist stripper. This
process may provide a pattern of features such as Damascene,
Through Silicon Via, or Wafer Level Packaging features that may be
electrofilled with silver tin using the above-described apparatus.
In some embodiments, electroplating occurs after the resist has
been patterned but before the resist is removed (through resist
plating).
Other Embodiments
[0132] Although the foregoing processes, systems, apparatuses, and
compositions have been described in some detail for the purpose of
promoting clarity of understanding, it will be apparent to one of
ordinary skill in the art that certain changes and modifications
may be practiced within the scope of the appended claims. It should
be noted that there are many alternative ways of implementing the
processes, systems, apparatuses, and compositions disclosed herein.
Accordingly, the disclosed embodiments are to be considered as
illustrative and not restrictive, and the scope of each appended
claims is not to be limited to the specific details of the
embodiments described herein.
* * * * *