U.S. patent application number 13/616050 was filed with the patent office on 2013-01-17 for plating apparatus and plating method.
The applicant listed for this patent is Yasuhiko Endo, Kuniaki Horie, Kenji Kamoda, Fumio Kuriyama, Yoshio Minami, Nobutoshi Saito, Masahiko SEKIMOTO, Stephen Strausser, Takashi Takemura, Junichiro Yoshioka. Invention is credited to Yasuhiko Endo, Kuniaki Horie, Kenji Kamoda, Fumio Kuriyama, Yoshio Minami, Nobutoshi Saito, Masahiko SEKIMOTO, Stephen Strausser, Takashi Takemura, Junichiro Yoshioka.
Application Number | 20130015075 13/616050 |
Document ID | / |
Family ID | 33492418 |
Filed Date | 2013-01-17 |
United States Patent
Application |
20130015075 |
Kind Code |
A1 |
SEKIMOTO; Masahiko ; et
al. |
January 17, 2013 |
PLATING APPARATUS AND PLATING METHOD
Abstract
A plating apparatus has an ashing unit (300) configured to
perform an ashing process on a resist (502) applied on a surface of
a seed layer (500) formed on a substrate (W), and a pre-wetting
section (26) configured to provide hydrophilicity to a surface of
the substrate after the ashing process. The plating apparatus
includes a pre-soaking section (28) configured to bring the surface
of the substrate into contact with a treatment solution to clean or
activate a surface of the seed layer formed on the substrate. The
plating apparatus also includes a plating unit (34) configured to
bring the surface of the substrate into a plating solution in a
plating tank while the resist is used as a mask so as to form a
plated film (504) on the surface of the seed layer formed on the
substrate.
Inventors: |
SEKIMOTO; Masahiko; (Tokyo,
JP) ; Endo; Yasuhiko; (Tokyo, JP) ; Strausser;
Stephen; (US) ; Takemura; Takashi; (Tokyo,
JP) ; Saito; Nobutoshi; (Tokyo, JP) ;
Kuriyama; Fumio; (Tokyo, JP) ; Yoshioka;
Junichiro; (Tokyo, JP) ; Horie; Kuniaki;
(Tokyo, JP) ; Minami; Yoshio; (Tokyo, JP) ;
Kamoda; Kenji; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SEKIMOTO; Masahiko
Endo; Yasuhiko
Strausser; Stephen
Takemura; Takashi
Saito; Nobutoshi
Kuriyama; Fumio
Yoshioka; Junichiro
Horie; Kuniaki
Minami; Yoshio
Kamoda; Kenji |
Tokyo
Tokyo
Tokyo
Tokyo
Tokyo
Tokyo
Tokyo
Tokyo
Tokyo |
|
JP
JP
US
JP
JP
JP
JP
JP
JP
JP |
|
|
Family ID: |
33492418 |
Appl. No.: |
13/616050 |
Filed: |
September 14, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12543832 |
Aug 19, 2009 |
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13616050 |
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10544623 |
Aug 5, 2005 |
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PCT/JP2004/007437 |
May 25, 2004 |
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12543832 |
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Current U.S.
Class: |
205/118 ;
204/198 |
Current CPC
Class: |
H01L 2224/1147 20130101;
H01L 2924/01074 20130101; H01L 2924/01082 20130101; H01L 2924/01322
20130101; H01L 2224/05573 20130101; H01L 21/6723 20130101; H01L
2924/01029 20130101; H01L 24/11 20130101; H01L 2924/01006 20130101;
H01L 2924/01033 20130101; H01L 21/2885 20130101; H01L 2924/01078
20130101; H01L 2924/01079 20130101; H01L 2924/014 20130101; H01L
2924/01047 20130101; H01L 2924/01046 20130101; H01L 2224/05568
20130101; C25D 5/022 20130101; C25D 17/001 20130101; C25D 7/123
20130101; H01L 21/67173 20130101; H01L 2224/13099 20130101; H01L
2224/05647 20130101; H01L 2924/00014 20130101 |
Class at
Publication: |
205/118 ;
204/198 |
International
Class: |
C25D 5/02 20060101
C25D005/02; C25D 17/00 20060101 C25D017/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 27, 2003 |
JP |
2003-148811 |
Feb 26, 2004 |
JP |
2004-051849 |
Claims
1-60. (canceled)
61. A plating method comprising: ashing a resist on a surface of a
seed layer on a substrate by applying at least one of plasma,
light, and an electromagnetic wave to the resist to reform a
hydrophobic surface of the resist into a hydrophilic surface; and
bringing the substrate into contact with a plating solution in
which an anode is disposed using the resist as a mask so as to form
a plated film on the surface of the seed layer in a predetermined
position where interconnect is formed.
62. The plating method as recited in claim 61, further comprising:
after said ashing, holding the substrate by a substrate holder
while sealing a peripheral portion of the substrate with its
surface exposed.
63. The plating method as recited in claim 62, further comprising:
performing a hydrophilic process on the surface of the substrate
held by said substrate holder after said ashing.
64. The plating method as recited in claim 63, wherein said
hydrophilic process is performed by immersing the substrate in pure
water or ejecting pure water onto the surface of the substrate.
65. The plating method as recited in claim 64, wherein the pure
water is deaerated by a deaeration device.
66. The plating method as recited in claim 63, wherein said
hydrophilic process is performed substantially under vacuum or
performed under a pressure lower than an atmospheric pressure.
67. The plating method as recited in claim 63, wherein said
hydrophilic process comprises continuously performing two or more
types of hydrophilic processes.
68. The plating method as recited in claim 3, further comprising:
after said hydrophilic process, bringing the surface of the
substrate, held by said substrate holder, into contact with a
treatment solution to clean or activate the surface of the seed
layer.
69. The plating method as recited in claim 68, wherein the
treatment solution comprises at least one of ozone water, an acid
solution, an alkali solution, an acid degreasing agent, a solution
containing a developer, a solution containing a resist stripping
solution, and reduced water of an electrolytic solution.
70. The plating method as recited in claim 68, wherein the
treatment solution comprises an acid solution or an acid degreasing
agent so as to perform an electrolytic process on the substrate in
the treatment solution with the substrate serving as a cathode.
71. A plating apparatus comprising: an ashing unit configured to
perform an ashing process on a resist on a surface of a seed layer
on a substrate by applying at least one of plasma, light, and an
electromagnetic wave to the resist to reform a hydrophobic surface
of the resist into a hydrophilic surface; and a plating unit
configured to bring the substrate into contact with a plating
solution in which an anode is disposed using the resist as a mask
so as to form a plated film on the surface of the seed layer in a
predetermined position where interconnect is formed.
72. The plating apparatus as recited in claim 71, further
comprising: a substrate holder configured to detachably hold the
substrate in a substrate loading/unloading unit after the ashing
process while sealing a peripheral portion of the substrate with
its surface exposed.
73. The plating apparatus as recited in claim 72, further
comprising: a substrate transfer device configured to transfer the
substrate between said ashing unit and said substrate
loading/unloading unit.
74. The plating apparatus as recited in claim 72, further
comprising: a pre-wetting section configured to perform a
hydrophilic process on the surface of the substrate held by said
substrate holder after the ashing process.
75. The plating apparatus as recited in claim 74, wherein said
pre-wetting section is configured to perform the hydrophilic
process by immersing the substrate in pure water or ejecting pure
water onto the surface of the substrate.
76. The plating apparatus as recited in claim 75, further
comprising: a deaeration device configured to deaerate the pure
water.
77. The plating apparatus as recited in claim 74, wherein said
pre-wetting section is substantially under vacuum or under a
pressure lower than an atmospheric pressure.
78. The plating apparatus as recited in claim 74, wherein said
pre-wetting section is comprises a plurality of pre-wetting
portions having different functions.
79. The plating apparatus as recited in claim 74, further
comprising: a pre-soaking section configured to bring the surface
of the substrate, held by said substrate holder, into contact with
a treatment solution after said hydrophilic process to clean or
activate the surface of the seed layer.
80. The plating apparatus as recited in claim 79, further
comprising: a substrate holder transfer device configured to
transfer said substrate holder with the substrate held thereon
between said substrate loading/unloading unit, said pre-wetting
section, said pre-soaking section, and said plating unit.
Description
TECHNICAL FIELD
[0001] The present invention relates to a plating apparatus and a
plating method for plating a surface of a substrate, and more
particularly to a plating apparatus and a plating method for
forming a bump (protruding electrode), which provides electrical
connection with an electrode of a package or a semiconductor chip,
on a surface of a semiconductor wafer while a resist is used as a
mask.
BACKGROUND ART
[0002] In tape automated bonding (TAB) or flip chip, for example,
it has widely been practiced to form protruding connecting
electrodes (bumps) of gold, copper, solder, or nickel, or a
multi-layer laminate of these metals at predetermined portions
(electrodes) on a surface of a semiconductor chip having
interconnects formed therein, and to electrically connect the
interconnects via bumps with electrodes of a package or with TAB
electrodes. In order to form bumps, there have been used various
methods including electroplating, vapor deposition, printing, and
ball bumping. In view of a recent increase in the number of I/O
terminals in a semiconductor chip and a trend toward finer pitches,
an electroplating process has more frequently been employed because
the electroplating process can achieve fine processing and has
relatively stable performance.
[0003] In an electroplating process, bumps are formed at
predetermined positions of a surface of a substrate having
interconnections in the following manner. In such a process, a
resist has been widely used as a mask. First, as shown in FIG. 1A,
a seed layer 500 is deposited as a feeding layer on a surface of a
substrate W by sputtering or vapor deposition. Then, a resist 502
is applied onto an overall surface of the seed layer 500 so as to
have a height H of, for example, 20 to 120 .mu.m. Thereafter,
exposure and development are performed on a surface of the resist
502 to form openings 502a having a diameter D of about 20 to about
200 .mu.m at predetermined positions in the resist 502. Then, as
shown in FIG. 1B, a metal such as Au or Cu, which is a material for
bumps, is deposited in the openings 502a by an electroplating
process so as to form and grow plated films 504 in the openings
502a. As shown in FIG. 1C, the resist 502 is stripped and removed
from the surface of the substrate W. Then, as shown in FIG. 1D,
unnecessary portions of the seed layer 500 are etched and removed
from the surface of the substrate W. Then, a reflowing process is
performed, as needed, to form spherical bumps 506 as shown in FIG.
1E.
[0004] Electroplating processes can be grouped into a jet-type or
cup-type electroplating process, in which a plating solution is
ejected upward to a substrate such as a semiconductor wafer
positioned horizontally in a state such that a surface of the
substrate to be plated faces downward, and a dipping-type
electroplating process, in which a substrate is immersed vertically
in a plating solution within a plating tank while the plating
solution is supplied from the bottom of the plating tank so as to
overflow the plating tank. According to the dipping-type
electroplating process, bubbles which would adversely affect
qualities of plated substrates are readily removed, and the
footprint of a plating apparatus can be reduced. Further, the
dipping-type electroplating process can be readily adapted to
variations in wafer size. Thus, the dipping-type electroplating
process is considered to be suitable for a bump formation process,
which fills relatively large holes and requires a considerably long
period of time to complete a plating process.
[0005] When plated films are formed in openings in a resist to form
bumps on a surface of a substrate such as a semiconductor wafer,
because a resist is generally made of a hydrophobic material having
low wettability, a plating solution is unlikely to enter the
openings in the resist. Accordingly, as shown by an imaginary line
in FIG. 1A, air bubbles 508 may be produced in a plating solution.
Such air bubbles 508 tend to remain within the openings 502a to
cause plating defects such as insufficient plating.
[0006] In order to prevent such plating defects, a surface-active
agent may be added to a plating solution to lower surface tension
of the plating solution so as to readily introduce the plating
solution into the openings in the resist. However, when the surface
tension of the plating solution is lowered, air bubbles are likely
to be produced in the plating solution when the plating solution is
circulated. Further, when a new surface-active agent is added to a
plating solution, anomaly of deposition may occur so as to increase
the amount of organic substances trapped in the plated films. Thus,
a surface-active agent may adversely affect properties of the
plated films.
[0007] With a conventional electroplating apparatus using a
dipping-type electroplating process, air bubbles are likely to be
released from the openings in the resist. Such an electroplating
apparatus employs a substrate holder which holds a substrate such
as a semiconductor wafer in a state such that a (front) surface of
the substrate to be plated is exposed while sealing a peripheral
edge and a rear face of the substrate. The substrate holder is
immersed in a plating solution together with the substrate to plate
the surface of the substrate. Thus, according to a conventional
electroplating apparatus using a dipping-type electroplating
process, it is difficult to automate an entire plating process from
loading of a substrate to unloading of the substrate after a
plating process.
[0008] Further, a conventional plating apparatus for bump formation
generally has a plating section for performing a plating process,
an additional process section for performing additional processes
incidental to the plating process, such as a cleaning process and a
pre-treatment process, and a transfer robot for transferring a
substrate between the plating section and the additional process
section. Openings are formed at predetermined positions in a resist
on a substrate. Substrates are housed in a substrate cassette. One
of the substrates is picked out from the substrate cassette. Then,
a metal such as Au or Cu, which is a material for bumps, is
deposited and grown in the openings of the resist on the substrate.
Thereafter, the substrate is subjected to a post-treatment process
such as a cleaning and drying process and returned to the substrate
cassette.
[0009] Substrates which have been plated by the plating apparatus
and returned to the substrate cassette are transferred to a
subsequent resist stripping unit, etching unit, or the like while
the substrates are housed in the substrate cassette. In the resist
stripping unit, the resist is stripped and removed from the surface
of the substrate. In the etching unit, unnecessary portions of the
seed layer are removed from the surface of the substrate.
[0010] However, the conventional plating apparatus for bump
formation is designed to perform processes until a plating process,
but not to perform processes after the plating process, in
consideration of manufacturing lead-time suitable for mass
production of a limited variety of goods. Accordingly, the
conventional plating apparatus for bump formation cannot
continuously perform a sequence of processes to complete bump
formation. Further, the conventional plating apparatus for bump
formation requires a large space for additional process units such
as a resist stripping unit and an etching unit and has less
flexibility in arrangement.
DISCLOSURE OF INVENTION
[0011] The present invention has been made in view of the above
drawbacks. It is, therefore, a first object of the present
invention to provide a plating apparatus and a plating method which
can introduce a plating solution reliably into an opening in a
resist applied on a surface of a substrate without adding any
surface-active agent in a plating solution and can achieve a
plating process without any plating defects such as insufficient
plating.
[0012] A second object of the present invention is to provide a
plating apparatus and a plating method which can automatically form
a plated film suitable for a protruding electrode such as a bump
with a dipping-type process, which can readily release air
bubbles.
[0013] A third object of the present invention is to provide a
plating apparatus which can continuously perform processes
including a plating process such as a bump formation process, can
reduce a space for the whole apparatus, and is suitable for limited
production of a wide variety of goods.
[0014] According to a first aspect of the present invention, there
is provided a plating apparatus having an ashing unit configured to
perform an ashing process on a resist applied on a surface of a
seed layer formed on a substrate, and a pre-wetting section
configured to provide hydrophilicity to a surface of the substrate
after the ashing process. The plating apparatus includes a
pre-soaking section configured to bring the surface of the
substrate into contact with a treatment solution to clean or
activate a surface of the seed layer formed on the substrate. The
plating apparatus also includes a plating unit configured to bring
the surface of the substrate into a plating solution in a plating
tank while the resist is used as a mask so as to form a plated film
on the surface of the seed layer formed on the substrate.
[0015] When a substrate is plated while a resist is used as a mask,
because the resist makes a surface of the substrate hydrophobic,
the surface of the substrate is unlikely to be brought into contact
with a plating solution to thus cause plating defects such as
insufficient plating. The ashing unit performs an ashing process on
the resist applied on the surface of the substrate prior to the
plating process. The ashing process can reform a hydrophobic
surface of the resist into a hydrophilic surface. Thus, the surface
of the substrate becomes likely to be brought into contact with a
plating solution. Further, a hydrophilic process may be performed
on the surface of the substrate in the pre-wetting section after
the ashing process to replace a gas in the openings formed in the
resist with water and further replace the water with a plating
solution. Thus, it is possible to prevent plating defects such as
insufficient plating.
[0016] The ashing unit may be configured to apply at least one of
plasma, light, and an electromagnetic wave to the resist to perform
the ashing process on the resist. When the ashing unit is
configured to apply high-energy light or electromagnetic waves
including plasma, ultraviolet rays, and far ultraviolet rays, then
high-energy ions, photons, or electrons collide with the resist to
produce an active gas. The ions, photons, or electrons and the
active gas can decompose and remove organic substances such as
resist residues. Hydrogen is abstracted from organic substances in
the resist, or principal chains or side chains of organic
substances in the resist 502 are cut, to thereby remove
contaminants from the surface of the substrate and reform the
surface of the substrate. The ashing unit may be provided inside or
outside of a frame of the plating apparatus.
[0017] The pre-wetting section may comprise a pre-wetting tank
configured to immerse a substrate in pure water or a pre-wetting
device configured to eject pure water through a spray to a surface
of the substrate. The pre-wetting section may be substantially
under vacuum or under a pressure lower than an atmospheric
pressure. The pre-wetting section may comprise a deaeration device
for deaerating the pure water.
[0018] The pre-wetting section may comprise a plurality of
pre-wetting portions having different functions. For example, the
plating apparatus may include a dipping-type pre-wetting portion
using deaerated water, a spray-type pre-wetting section, and the
like. In such a case, a suitable pre-wetting portion can be
selected according to a recipe. With this arrangement, limitation
on processes due to types of pre-wetting sections can be
eliminated, and the plating apparatus can perform various types of
processes.
[0019] The pre-soaking section may comprise a pre-soaking tank to
hold the treatment solution including at least one of ozone water,
an acid solution, an alkali solution, an acid degreasing agent, a
solution containing a developer, a solution containing a resist
stripping solution, and reduced water of an electrolytic solution.
For example, when the surface of the substrate is brought into
contact with a treatment solution (acid solution) such as a
sulfuric acid or hydrochloric acid solution, an oxide film, which
has a high electrical resistance, formed on a surface of a seed
layer can be etched to remove the oxide film and expose a clean
metal surface of the seed layer. Further, a substrate may be
treated with ozone water and then treated with an acid
solution.
[0020] Alternatively, the pre-soaking section may comprise a
pre-soaking tank to hold the treatment solution including an acid
solution or an acid degreasing agent so as to perform an
electrolytic process on the substrate in the treatment solution in
a state such that the substrate serves as a cathode.
[0021] The plating unit may comprise an anode disposed in the
plating solution and an anode weight measuring device operable to
measure weight of the anode. The anode weight measuring device may
comprise a load cell. With this arrangement, consumption of the
anode can be measured more accurately than in a case where the
weight of the anode has heretofore been estimated indirectly based
on the amount of current supplied to the anode. Therefore, it is
possible to accurately determine when the anode should be replaced.
The weight of the anode can be measured even during a plating
process. Thus, even during a continuous plating process, it is
possible to accurately determine when the anode should be replaced.
Accordingly, the plating apparatus can be operated
premeditatedly.
[0022] The plating tank may comprise an anode disposed in the
plating solution, a dummy anode provided in the plating tank, and a
single power supply configured to apply a voltage selectively to
the anode for an actual plating process and to the dummy anode for
a dummy plating process. Generally, a power supply which is used
for dummy plating at the time of replacement of a plating solution
is not used during a plating process. Thus, a power supply for
dummy plating is not used for a long term and is provided
uneconomically. With the above arrangement, a single power supply
can be switched so as to perform a dummy plating process and an
actual plating process. Thus, a separate power supply for dummy
plating can be eliminated, and the number of power supplies can be
reduced. The single power supply may be configured to automatically
switch application of the voltage so as to perform the actual
plating process after completion of the dummy plating process.
[0023] The plating apparatus may include a plating solution
management unit configured to manage components of the plating
solution to be supplied to the plating unit. The plating solution
management unit can automatically perform analysis of components in
the plating solution and addition of components which have been
insufficient to the plating solution, which have heretofore been
performed by hand.
[0024] Thus, the plating solution management unit can maintain each
component in the plating solution within a predetermined range.
Since a plating process is performed with a plating solution thus
managed, it is possible to maintain good properties (components),
good appearance, and good uniformity of the thickness of a plated
film formed on the substrate. The plating solution management unit
may be provided inside or outside of the frame of the plating
apparatus.
[0025] The plating solution management unit may be configured to
analyze and/or estimate components of the plating solution and to
add an insufficient component to the plating solution through a
feedback control and/or a feedforward control. For example, the
plating solution management unit extracts a portion of the plating
solution as a sample from the plating tank and analyzes it.
Components which have been insufficient for a predetermined amount
are added into the plating solution through a feedback control
based on the analysis by the plating solution management unit, a
feedforward control estimating disturbances including the plating
time or the number of plated substrates, or a combination of the
feedback control and the feedforward control. Thus, each component
in the plating solution can be maintained within a predetermined
range.
[0026] The plating apparatus may include a communication device
configured to communicate information through a communication
network using a computer. The communication device can transmits
information on, for example, plating results to proper units or
devices through the communication network using the computer. Thus,
required information is mutually transmitted through the
communication device so as to control the units or devices based on
the information to achieve a fully automatic plating process. The
communication device may be provided inside or outside of the frame
of the plating apparatus.
[0027] The plating apparatus may include a resist stripping unit
configured to strip and remove the resist used as a mask from the
surface of the seed layer formed on the substrate. The resist
stripping unit may be provided inside or outside of the frame of
the plating apparatus. From a viewpoint of continuous processing,
it is desirable that the resist stripping unit should strip a
resist on a substrate while the substrate is held by a substrate
holder. The substrate after stripping the resist may be returned to
a substrate cassette.
[0028] The plating apparatus may include a seed layer removal unit
configured to remove an unnecessary portion of a seed layer formed
on the substrate. The seed layer removal unit may be provided
inside or outside of the frame of the plating apparatus. From a
viewpoint of continuous processing, it is desirable that the seed
layer removal unit should remove an unnecessary portion of a seed
layer on a substrate while the substrate is held by a substrate
holder. The substrate after removing the seed layer may be returned
to a substrate cassette.
[0029] The plating apparatus may include an annealing unit
configured to anneal the plated film formed on the surface of the
substrate. The annealing unit may be provided inside or outside of
the frame of the plating apparatus.
[0030] The plating apparatus may include a reflowing unit
configured to reflow the plated film formed on the surface of the
substrate. The reflowing unit may be provided inside or outside of
the frame of the plating apparatus.
[0031] The plating apparatus may include a neutralization unit
configured to perform a neutralization treatment on the surface of
the substrate. After the substrate has been plated and cleaned,
acid or alkali components contained in the plating solution may
remain on the substrate. With the neutralization unit, since
neutralization treatment is performed on the substrate after the
plating process, it is possible to eliminate adverse influence on
the resist stripping process and the seed layer removal process,
which are performed after the plating process, from acid or alkali.
For example, the neutralization treatment solution may comprise an
alkalescent solution containing trisodium phosphate. The
neutralization unit may be provided inside or outside of the frame
of the plating apparatus.
[0032] The plating apparatus may include a visual inspection unit
configured to inspect an appearance of the plated film formed on
the surface of the substrate. Some substrate may have a defective
appearance of a plated film for various reasons including anomaly
of a plating solution, a substrate, and a plating apparatus. If a
plating process is continued without halting the plating apparatus
when a defective substrate is produced, then the number of
defective substrates is increased. The visual inspection unit
performs visual inspection of the plated film and notifies an
operator when the plated film has a defective appearance. At that
time, the plating apparatus is halted, and the defective substrate
is recorded in substrate processing data. Thus, the number of
defective substrates can be reduced, and the defective substrates
can be removed based on the substrate processing data. The visual
inspection unit may be provided inside or outside of the frame of
the plating apparatus. The visual inspection unit may be configured
to inspect the appearance of the plated film in a contact or
non-contact manner.
[0033] The plating apparatus may include a film thickness
measurement unit configured to measure film thickness of the plated
film formed on the surface of the substrate. The film thickness of
a plated film formed on a substrate may vary according to influence
from patterns formed on a substrate and conditions of the
apparatus, the plating solution, and the substrate. In some cases,
the within wafer uniformity of the film thickness of the plated
film may excessively be lowered so as not to meet the specification
limits. If the plating apparatus is operated to plate substrates
continuously, then the number of defective substrate may be
increased. Even if the within wafer uniformity of the film
thickness is within the specification limits, a subsequent
polishing process may be required according to the plating process.
In such a case, it is necessary to set the amount of polishing to
be required. The film thickness measurement unit may be configured
to measure a distribution of the film thickness of the plated film
formed on the substrate over an overall surface of the substrate.
Based on the measurement results, the film thickness measurement
unit determines whether or not the substrate has good quality. If
the substrate does not have good quality, the substrate is recorded
in substrate processing data. Based on a rate of defective
substrates recorded in the substrate processing data, the plating
apparatus is halted, and an operator is notified of the anomaly.
Thus, defective substrates, which have a low within wafer
uniformity of the film thickness of the plated film, can be
removed, and the required amount of the plated film to be polished
can be set in a case where there is a polishing process as a
subsequent process. The film thickness measurement unit may be
provided inside or outside of the frame of the plating apparatus.
The film thickness measurement unit may be configured to measure
the film thickness of the plated film in a contact or non-contact
manner.
[0034] The plating apparatus may include a plating area measurement
unit configured to measure an actual area in which the plated film
is to be formed on the surface of the substrate. A plating area is
required to determine plating conditions. However, a plating area
cannot be known or otherwise cannot accurately be known in some
cases. The plating area measurement unit can measure an actual area
(plating area) in which a plated film is to be formed. Thus, a
current value which determines plating conditions can be accurately
determined. Accordingly, it is possible to accurately obtain a
plated film having a predetermined film thickness in a
predetermined plating time. In particular, in a case where a single
substrate is plated at a time, substrates having different plating
areas can be plated so as to have a predetermined film thickness
merely by setting a current density and a plating period of time.
Accordingly, setting of recipes is greatly facilitated.
[0035] The plating area measurement unit may be provided inside or
outside of the frame of the plating apparatus. The plating area
measurement unit may be configured to supply a current to the
substrate to measure the actual area. The plating area measurement
unit may be configured to optically scan the surface of the
substrate to measure the actual area. For example, when a substrate
is sealed at a peripheral portion and detachably held by a
substrate holder in a state such that a surface of a substrate to
be plated is exposed externally, the surface of the substrate is
optically scanned to measure a plating area.
[0036] The plating apparatus may include a polishing unit
configured to polish a surface of the plated film to adjust film
thickness of the plated film. The polishing unit may be provided
inside or outside of the frame of the plating apparatus. The
polishing unit may be configured to perform chemical mechanical
polishing or mechanical polishing to polish the surface of the
plated film.
[0037] The plating apparatus may include a chemical liquid
adjustment unit configured to remove metal impurities or organic
impurities mixed in the plating solution or generated decomposition
products. In order to maintain evaluation properties of a deposited
film, a plating solution used in a plating process should be
renewed periodically according to levels of impurities mixed in the
plating solution or accumulated decomposition products. An old
plating solution is discarded except for particular plating
solutions such as a gold plating solution, thereby causing loads on
cost and environment. The chemical liquid adjustment unit can
remove impurities and decomposition products contained in an old
plating solution so as to lengthen a frequency of renewal of a
plating solution. Thus, it is possible to reduce loads on cost and
environment. The chemical liquid adjustment unit may be provided
inside or outside of the frame of the plating apparatus. The
chemical liquid adjustment unit may include at least one of an
electrolytic process section, an ion exchange section, an activated
carbon process section, and a coagulation and settlement
section.
[0038] The plating apparatus may include a chemical liquid supply
and recovery unit configured to supply a chemical liquid to the
plating tank and recover the chemical liquid from the plating tank.
With the chemical liquid supply and recovery unit, a highly
corrosive or harmful chemical liquid which would exert an adverse
influence not only on the apparatus or units but also on human
bodies can readily be handled with safe because operators are not
required to handle the chemical liquid so often. The chemical
liquid supply and recovery unit may be provided inside or outside
of the frame of the plating apparatus.
[0039] The chemical liquid supply and recovery unit may include a
chemical liquid container attached in a replaceable manner. The
chemical liquid supply and recovery unit is configured to supply
the chemical liquid from the chemical liquid container to the
plating tank and to recover the chemical liquid from the plating
tank to the chemical liquid container. A commercially available
chemical liquid tank or bottle may be used as a chemical liquid
container and attached in a replaceable manner. Thus, a chemical
liquid is supplied directly from the available chemical liquid tank
or bottle to the plating tank and recovered from the plating tank
directly to the available chemical liquid tank or bottle. When the
chemical liquid tank or bottle becomes empty at the time of supply
of the chemical liquid, an operator is notified of a signal
indicating that the chemical liquid tank or bottle should be
replenished or replaced with a filled chemical liquid tank or
bottle. At that time, the supply of the chemical liquid is
interrupted. After the chemical liquid tank or bottle has been
replenished or replaced with a filled chemical liquid tank or
bottle, the supply of the chemical liquid is restarted. When the
chemical liquid tank or bottle becomes full at the time of recovery
of the chemical liquid, an operator is notified of a signal
indicating that the chemical liquid tank or bottle should be
replaced with an empty chemical liquid tank or bottle or the
chemical liquid should be discharged from the chemical liquid tank
or bottle. At that time, the recovery of the chemical liquid is
interrupted. After the chemical liquid tank or bottle has been
replaced with an empty chemical liquid tank or bottle or become
empty, the recovery of the chemical liquid is restarted.
[0040] The plating apparatus may include a plating solution
regeneration unit configured to remove an organic substance
contained in the plating solution to regenerate the plating
solution. During the plating process, for example, a plating
solution in which a component ratio of an additive such as an
organic component or a surface-active agent is excessively
increased beyond a predetermined range, or a plating solution in
which an additive or a surface-active agent is decomposed but
remains as a waste product can be regenerated by the plating
solution regeneration unit without replacement of the plating
solution, so that cost and work for replacement with a new plating
solution can remarkably be reduced. Particularly, together with use
of the plating solution management unit, a plating solution can be
regenerated to substantially the same degree as a new plating
solution. The plating solution regeneration unit may be provided
inside or outside of the frame of the plating apparatus.
[0041] The plating solution regeneration unit may be configured to
remove the organic substance through an activated carbon filter.
The plating apparatus may have a plating solution circulation
system for flowing the plating solution through the plating
solution regeneration unit, which includes a replaceable activated
carbon filter, and the plating tank. With such a plating solution
circulation system, the plating solution flows through the
activated carbon filter in the plating solution regeneration unit
to remove an organic substance as an additive in the plating
solution and a waste product into which the organic substance is
decomposed. Thus, a plating solution from which an additive
component (organic substance) is removed can be returned to the
plating tank.
[0042] The plating apparatus may include an exhaust gas treatment
unit configured to remove a harmful component from gas or mist
produced in the plating apparatus and to discharge harmless gas to
an exterior of the plating apparatus through a duct. Generally, gas
or mist produced in a plating apparatus is harmful to other
apparatuses or facilities. An exhaust duct from a plating apparatus
is generally connected and joined to a collective exhaust duct.
Accordingly, an exhaust gas which has not been treated in the
plating apparatus may react with an exhaust gas from other
apparatuses so as to exert an adverse influence on other
apparatuses or facilities. The exhaust gas treatment unit can
remove harmful gas and mist from an exhaust gas and introduce the
exhaust gas into a collective exhaust duct to prevent an adverse
influence on other apparatuses or facilities. Thus, it is possible
to reduce loads on removing harmful components in other apparatuses
or facilities. The exhaust gas treatment unit may be provided
inside or outside of the frame of the plating apparatus.
[0043] The exhaust gas treatment unit may be configured to remove
the harmful component through a wet process with an absorption
liquid, a dry process with an absorbent, or a condensation
liquefaction process by cooling. The plating tank may have a first
chamber holding an acid plating solution, a second chamber holding
a cyanic plating solution, and a partition to separate the first
chamber and the second chamber. The first chamber may include an
exhaust duct to discharge an acid gas produced from the acid
plating solution in the first chamber. The second chamber may
include an exhaust duct to discharge a cyanic gas produced from the
cyanic plating solution in the second chamber. For example, if a
plating process with an acid plating solution and a plating process
with a cyanic plating solution are performed in the same plating
apparatus, then the plating solutions or gas may be mixed to
produce a cyanic gas. In order to prevent such a drawback, these
processes have heretofore been performed in separate plating
apparatuses. With the above arrangement, an acid gas produced from
an acid plating solution and a cyanic gas produced from a cyanic
plating solution can separately be discharged so as to prevent the
plating solutions or gas from being mixed to produce a cyanic gas.
Thus, a plating process with an acid plating solution and a plating
process with a cyanic plating solution can be performed
continuously in the same plating apparatus. The cyanic plating
solution may comprise a gold plating solution or a silver plating
solution.
[0044] The plating apparatus may include a waste water regeneration
unit configured to regenerate waste water, which has been used in
and discharged from the plating unit, to reuse at least a portion
of regenerated waste water for the plating process while
discharging the rest of the waste water to an exterior of the
plating apparatus. A cleaning process in the plating process
requires a large amount of cleaning water. A large amount of
cleaning water having high cleanliness and treatment of waste water
which has been used in the plating process impose large loads on
existing facilities. With the waste water regeneration unit, the
plating apparatus has a completely or partially closed system for
regenerating waste water used therein. Thus, it is possible to
reduce the amount of cleaning water having high cleanliness and
loads on waste water treatment required for the facilities. The
waste water regeneration unit may be provided inside or outside of
the frame of the plating apparatus.
[0045] The waste water regeneration unit may be configured to
regenerate the waste water by at least one of microfiltration,
ultraviolet irradiation, ion exchange, ultrafiltration, and reverse
osmosis. A portion or all of cleaning water used in the plating
unit can be stored in a tank of the waste water regeneration unit
and recovered therein. Then, a portion or all of the regenerated
water can be used as cleaning water, and the rest of the
regenerated water can be discharged to the facilities or water
tank.
[0046] According to a second aspect of the present invention, there
is provided a plating apparatus having a loading/unloading section
configured to load and unload a cassette housing substrates, a
sensor provided in the loading/unloading section for detecting
sizes of the substrates received in the cassette, and a plurality
of tools corresponding to sizes of substrates to be plated. The
plating apparatus includes a tool stocker to store the plurality of
tools and a plating section configured to perform at least a
plating process. The plating apparatus also includes a controller
configured to select a tool corresponding to a size detected by the
sensor from the plurality of tools, and a transfer device
configured to hold and transfer the tool selected by the controller
to the plating section.
[0047] If a plating apparatus is designed so as to correspond to
the size of a substrate to be plated, then a plurality of plating
apparatuses are required to correspond various sizes of substrates.
Accordingly, a large space for installation and utilities such as a
power supply are required in a clean room. With the above
arrangement, a single plating apparatus can perform a plating
process on substrates having different sizes, so that a required
space in a clean room, which is expensive, required energy, and
required cost can be reduced while substrates having different
sizes are plated.
[0048] According to a third aspect of the present invention, there
is provided a plating apparatus having a plurality of plating tanks
each having a plating solution and an anode therein. The plating
apparatus includes a single power supply configured to selectively
apply a voltage between a substrate and anodes in the plurality of
plating tanks so as to perform sequential plating processes.
[0049] Thus, the use of the single plating power supply can reduce
the number of plating power supplies. Accordingly, the plating
apparatus can be made compact in size. Further, when troubles occur
in the plating power supply, the plating process can be interrupted
before a substrate has been plated or while a substrate is plated.
Accordingly, it is not necessary to discard the substrate, and the
substrate can be plated by the plating power supply that has been
repaired.
[0050] The plurality of plating tanks may contain different kinds
of metals. The plating apparatus may include a sensor for detecting
when a substrate is immersed in the plating solutions of the
plurality of plating tanks, and a switch operable to switch the
single power supply based on a signal from the sensor.
[0051] According to a fourth aspect of the present invention, there
is provided a plating method to form a plated film on a surface of
a substrate. A resist is applied on a surface of a seed layer
formed on the substrate. After an ashing process of the resist, a
hydrophilic process is performed on the surface of the substrate to
provide hydrophilicity to the surface of the substrate. After the
hydrophilic process, the surface of the substrate is cleaned or
activated. The surface of the substrate is brought into a plating
solution while the resist is used as a mask so as to perform a
plating process to form a plated film on the surface of the
substrate.
[0052] The hydrophilic process may comprise continuously performing
two or more types of hydrophilic processes. The resist may be
stripped and removed from the surface of the substrate after the
plating process. An unnecessary portion of a seed layer formed on
the surface of the substrate may be removed. The plated film formed
on the surface of the substrate may be annealed. The plated film
formed on the surface of the substrate may be reflowed. A
neutralization treatment may be performed on the surface of the
substrate after the plating process. An appearance of the plated
film formed on the surface of the substrate may be inspected. Film
thickness of the plated film formed on the surface of the substrate
may be measured. An actual area in which the plated film is to be
formed on the surface of the substrate may be measured. The plated
film formed on the surface of the substrate may be polished to
adjust film thickness of the plated film.
[0053] With the above arrangement, a plating solution can be
introduced reliably into an opening of the resist on the surface of
the substrate without adding any surface-active agent, so that a
plating process without any plating defects such as insufficient
plating can be achieved. Further, a plated film suitable for a
protruding electrode such as a bump can be automatically formed
with a dipping-type process, which can readily release air
bubbles.
[0054] According to a fifth aspect of the present invention, there
is provided a plating apparatus having a plating unit configured to
form a plated film on a surface of a substrate while a resist is
applied as a mask on a surface of a seed layer formed on a
substrate. The plating apparatus includes a resist stripping unit
configured to strip and remove the resist from the surface of the
seed layer, and an etching unit configured to remove an unnecessary
portion of the seed layer formed on the surface of the substrate.
The plating unit, the resist stripping unit, and the etching unit
are incorporated integrally with each other.
[0055] Since the plating unit, the resist stripping unit, and the
etching unit are incorporated integrally with each other, a plating
process, a resist removal process, and a seed layer removal process
can be performed continuously. Further, the plating apparatus can
flexibly perform a desired plating process.
[0056] The plating apparatus may include a cleaning unit configured
to clean the substrate and a pre-treatment unit configured to
perform a pre-treatment process before plating. The plating
apparatus may include a reflowing unit configured to reflow the
plated film formed on the surface of the substrate. The plated film
may form a bump.
[0057] With the above arrangement, a bump formation process
including a plating process can be performed continuously so as to
reduce a space for the apparatus. Further, the plating apparatus
can achieve a desired plating process suitable for limited
production of a wide variety of goods.
[0058] The above and other objects, features, and advantages of the
present invention will be apparent from the following description
when taken in conjunction with the accompanying drawings which
illustrate preferred embodiments of the present invention by way of
example.
BRIEF DESCRIPTION OF DRAWINGS
[0059] FIGS. 1A through 1E are cross-sectional views showing a
process of forming a bump (protruding electrode) on a
substrate;
[0060] FIG. 2 is a schematic plan view showing a plating section in
a plating apparatus according to a first embodiment of the present
invention;
[0061] FIG. 3 is a plan view showing a substrate holder in the
plating section shown in FIG. 2;
[0062] FIG. 4 is an enlarged cross-sectional view of a plating unit
in the plating section shown in FIG. 2;
[0063] FIG. 5 is a plan view showing the plating apparatus
including the plating section shown in FIG. 2 and other various
units;
[0064] FIG. 6 is a flow chart showing a process before a substrate
is removed from the substrate holder in the plating apparatus shown
in FIG. 5;
[0065] FIG. 7 is a flow chart showing a process after the substrate
is removed from the substrate holder in the plating apparatus shown
in FIG. 5;
[0066] FIG. 8 is a schematic plan view showing a plating apparatus
according to a second embodiment of the present invention; and
[0067] FIG. 9 is a schematic plan view showing a plating apparatus
according to a third embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0068] A plating apparatus according to embodiments of the present
invention will be described below with reference to FIGS. 1A
through 9. Like or corresponding parts are denoted by like or
corresponding reference numerals throughout drawings, and will not
be described below repetitively.
[0069] FIG. 2 is a schematic plan view showing a plating section 1
in a plating apparatus according to a first embodiment of the
present invention. As shown in FIG. 2, the plating section 1 has a
rectangular frame 2, two cassette tables 12 each for placing
thereon a cassette 10 which houses substrates such as semiconductor
wafers, an aligner 14 for aligning an orientation flat or a notch
of a substrate in a predetermined direction, and a cleaning and
drying device 16 for cleaning a plated substrate and rotating the
substrate at a high speed to dry the substrate. The cassette tables
12, the aligner 14, and the cleaning and drying device 16 are
disposed along the same circle in the frame 2. The plating section
1 includes a substrate loading/unloading unit 20 disposed along a
tangent line to the circle for loading a substrate onto and
unloading a substrate from a substrate holder 18. The plating
section 1 also has a substrate transfer device (transfer robot) 22
disposed at the center of the circle for transferring a substrate
between the cassette tables 12, the aligner 14, the cleaning and
drying device 16, and the substrate loading/unloading unit 20.
[0070] The plating section 1 has a stocker 24 for storing or
temporarily receiving substrate holders 18, a pre-wetting tank
(pre-wetting section) 26, a pre-soaking tank (pre-soaking section)
28, a first cleaning tank 30a for cleaning a surface of the
substrate with pure water, a blowing tank 32 for removing water
from a cleaned substrate, a second cleaning tank 30b for cleaning a
surface of the substrate, and a plating tank 34. The stocker 24,
the pre-wetting tank 26, the pre-soaking tank 28, the first
cleaning tank 30a, the blowing tank 32, the second cleaning tank
30b, and the plating tank 34 are arranged in order from the
substrate loading/unloading unit 20 in the frame 2. The pre-wetting
tank 26 is configured to immerse a substrate in pure water to
provide hydrophilicity to a surface of the substrate. For example,
the pre-soaking tank 28 is configured to etch an oxide film, which
has a high electrical resistance, formed on a surface of a seed
layer with a treatment solution such as a sulfuric acid or
hydrochloric acid solution to remove the oxide film and clean or
activate a surface of an exposed seed layer. The plating tank 34
has an overflow tank 36 and a plurality of plating units 38
disposed within the overflow tank 36. Each of the plating units 38
is configured to hold one substrate therein to plate the substrate
with copper. In the present embodiment, a copper plating process is
performed on substrates in the plating tanks 34. However, the
present invention is also applicable to nickel, solder, or gold
plating.
[0071] In the present embodiment, the pre-wetting section comprises
a pre-wetting tank 26 for immersing a substrate in pure water.
However, the pre-wetting section may comprise a pre-wetting device
for ejecting pure water through a spray to a surface of a
substrate. The pre-wetting section is preferably substantially
under vacuum or under a pressure lower than an atmospheric
pressure. Alternatively, pure water to be supplied to the
pre-wetting section may be deaerated by a deaeration device.
[0072] Further, the plating section 1 has one pre-wetting tank
(pre-wetting section) 26 in the illustrated example. However, the
plating section 1 may have a plurality of pre-wetting portions
having different arrangements. Specifically, the plating section 1
may have a plurality of pre-wetting portions including a
dipping-type pre-wetting portion using deaerated water as described
above, a spray-type pre-wetting portion, and the like. In such a
case, a suitable pre-wetting portion can be selected according to a
recipe. With this arrangement, limitations on processes due to
types of pre-wetting sections can be eliminated, and the plating
apparatus can perform various types of processes.
[0073] The pre-soaking tank 28 is supplied with an acid solution
such as a sulfuric acid or hydrochloric acid solution, ozone water,
an alkali solution, an acid degreasing agent, a solution containing
a developer, a solution containing a resist stripping solution,
reduced water of an electrolytic solution, or the like. Type of
solution to be used is selected according to purposes of plating.
Further, a substrate may be treated with ozone water and then
treated with an acid solution. Alternatively, an electrolytic
process may be performed on a substrate in an acid solution or an
acid degreasing agent in a state such that the substrate serves as
a cathode.
[0074] The plating section 1 also has a substrate holder transfer
device (substrate transfer device) 40 disposed along the units 20,
24, 26, 28, 30a, 32, 30b, and 34. The substrate holder transfer
device 40 transfers substrate holders 18 together with substrates
between the units 20, 24, 26, 28, 30a, 32, 30b, and 34. The
substrate holder transfer device 40 includes a first transporter 42
for transferring substrate holders 18 between the substrate
loading/unloading unit 20 and the stocker 24, and a second
transporter 44 for transferring substrate holders 18 between the
stocker 24, the pre-wetting tank 26, the pre-soaking tank 28, the
cleaning tanks 30a and 30b, the blowing tank 32, and the plating
tank 34.
[0075] The plating section 1 includes a plurality of paddle driving
units 46 on the opposite side of the overflow tank 36 to the
substrate holder transfer device 40. Each of the paddle driving
units 46 drives a paddle 202 (see FIG. 4) provided in each plating
unit 38. The paddle 202 serves as a stirring rod for agitating a
plating solution.
[0076] The substrate loading/unloading unit 20 has rails 50 and a
flat loading plate 52 slidable horizontally along the rails 50. The
loading plate 52 supports two substrate holders 18 placed parallel
to each other in a horizontal state. A substrate is transferred
between one of the substrate holders 18 and the substrate transfer
device 22, and then another substrate is transferred between the
other of the substrate holders 18 and the substrate transfer device
22.
[0077] FIG. 3 is a plan view showing the substrate holder 18 shown
in FIG. 2. As shown in FIG. 3, each substrate holder 18 has a
stationary support member 54 in the form of a flat rectangular
plate and a movable support member 58 in the form of a ring. The
movable support member 58 is attached to the stationary support
member 54 in a state such that it can be opened and closed via a
hinge 56. A clamp ring 62 is attached to the movable support member
58 on the opposite side of the movable support member 58 to the
stationary support member 54. The clamp ring 62 is supported by
bolts 64 extending from the movable support member 58 through
elongated holes 62a formed along a circumferential direction in the
clamp ring 62. Thus, the clamp ring 62 is configured to be
rotatable and not to be detached from the movable support member
58.
[0078] The stationary support member 54 has L-shaped pawls 66
positioned near a peripheral portion of the movable support member
58. The pawls 66 are arranged along the circumferential direction
at equal intervals. The clamp ring 62 has a plurality of
protrusions 68 projecting radially outward. The protrusions 68 are
formed integrally with the clamp ring 62 and arranged at equal
intervals. The clamp ring 62 also has slightly elongated holes 62b
(three holes in FIG. 3) for rotating the protrusions 68. Each
protrusion 68 has an upper surface tapered so as to be inclined
along a rotating direction. Each pawl 66 has a lower surface
tapered so as to be inclined along the rotating direction and
opposed to the upper surface of the corresponding protrusion
68.
[0079] When the movable support member 58 is in an opened state, a
substrate is inserted and positioned properly in a central area of
the stationary support member 54. Then, the movable support member
58 is closed via the hinge 56. Subsequently, the clamp ring 62 is
rotated clockwise so as to slide the protrusions 68 of the clamp
ring 62 into the lower portions of the L-shaped pawls 66. Thus, the
movable support member 58 is fastened to and locked in the
stationary support member 54. When the clamp ring 62 is rotated
counterclockwise, the protrusions 68 of the clamp ring 62 are slid
out from the L-shaped pawls 66 to unlock the movable support member
58 from the stationary support member 54.
[0080] When the movable support member 58 is locked in the
stationary support member 54 as described above, a seal packing
(not shown) provided on a surface of the movable support member 58,
which faces the stationary support member 54, is pressed against a
surface of the substrate so as to provide a reliable seal.
Simultaneously, the substrate is brought into electric contact with
an external electrode (not shown), which is provided on the
stationary support member 54, at a location sealed by the seal
packing.
[0081] The movable support member 58 is opened and closed by a
cylinder (not shown) and the weight of the movable support member
58. Specifically, the stationary support member 54 has a
through-hole 54a formed therein. The loading plate 52 has a
cylinder provided at a position facing the through-hole 54a when
the substrate holder 18 is mounted on the loading plate 52. The
movable support member 58 is opened when the movable support member
58 is pushed upward through the through-hole 54a by a cylinder rod
(not shown). The movable support member 58 is closed by its own
weight when the cylinder rod is retracted.
[0082] In the present embodiment, the movable support member 58 is
locked and unlocked by rotating the clamp ring 62. The loading
plate 52 has a locking/unlocking mechanism provided on a ceiling
side. The locking/unlocking mechanism has pins disposed at
positions corresponding to the holes 62b in the clamp ring 62 of
the substrate holder 18, which is placed on the loading plate 52
and positioned near the center of the loading plate 52. When the
loading plate 52 is lifted so as to insert the pins into the holes
62b, the pins are rotated about the center of the clamp ring 62 to
thereby rotate the clamp ring 62. The loading plate 52 has only one
locking/unlocking mechanism. After one of the two substrate holders
18 placed on the loading plate 52 is locked or unlocked by the
locking/unlocking mechanism, the loading plate 52 is slid
horizontally to lock or unlock the other of the substrate holders
18.
[0083] Each of the substrate holders 18 has a sensor for detecting
whether a substrate is brought into contact with contact points
when the substrate is loaded into the substrate holder 18. The
sensor outputs signals to a controller (not shown). Each of the
substrate holders 18 also has a pair of hands 76 provided at ends
of the stationary support member 54. The hands 76 have
substantially a T-shape and serve as support portions for
supporting the substrate holder 18 when the substrate holder 18 is
transferred or suspended. Protruding ends of the hands 76 are
engaged with peripheral upper walls of the stocker 24 so that the
substrate holder 18 is held in a vertically suspended state. The
transporter 42 of the substrate holder transfer device 40 grips the
hands 76 of the substrate holder 18 held in the vertically
suspended state and transfers the substrate holder 18. The
protruding ends of the hands 76 are also engaged with peripheral
upper walls of the pre-wetting tank 26, the pre-soaking tank 28,
the cleaning tanks 30a and 30b, the blowing tank 32, and the
plating tank 34 so that the substrate holder 18 is held in a
vertically suspended state.
[0084] FIG. 4 shows a cross-section of one of the plating units 38.
As shown in FIG. 4, the plating unit 38 has an anode 200 and a
paddle (stirring rod) 202. The anode 200 is disposed in the plating
unit 38 at a position facing a surface of a substrate W when the
substrate holder 18 is positioned at a predetermined location. The
paddle 202 is disposed substantially vertically in the plating unit
38 between the anode 200 and the substrate W. The paddle 202 is
configured to be movable parallel to the substrate W in a
reciprocating manner by the paddle driving units 46.
[0085] Thus, the paddle 202 is disposed between the substrate W and
the anode 200 and reciprocated parallel to the substrate W.
Accordingly, a flow of a plating solution can be equalized along
the surface of the substrate W to thereby form a uniform plated
film over the entire surface of the substrate W.
[0086] In the present embodiment, the plating unit 38 also has a
regulation plate (mask) 204 having a central hole 204a between the
paddle 202 and the anode 200. The size of the central hole 204a
corresponds to the size of the substrate W. The regulation plate
204 lowers electric potentials of peripheral portions of the
substrate W so as to equalize the thickness of the plated film.
[0087] The anode 200 is held by an anode holder 206. The anode
holder 206 has an upper end which is held on peripheral upper walls
of the plating unit 38 in a suspended state. The plating unit 38
has a suspension portion 212, which is shown by an imaginary line
in FIG. 4, provided at the peripheral upper walls of the plating
unit 38. A load cell 208 is attached as an anode weight measuring
device to the suspension portion 212. The weight of the anode 200
is measured together with the anode holder 206 by the load cell
208.
[0088] Thus, the weight of the anode 200 can be measured directly
by the load cell 208. Accordingly, consumption of the anode 200 can
be measured more accurately than in a case where the weight of the
anode 200 has heretofore been estimated indirectly based on the
amount of current supplied to the anode 200. Therefore, it is
possible to accurately determine when the anode 200 should be
replaced. The weight of the anode 200 can be measured even during a
plating process. Thus, even during a continuous plating process, it
is possible to accurately determine when the anode 200 should be
replaced. Accordingly, the plating apparatus can be operated
premeditatedly.
[0089] The plating unit 38 includes a power supply 210 for applying
a voltage between the anode 200 and the substrate W. The anode 200
is connected to an anode of the power supply 210. The seed layer
500 (see FIG. 1A) of the substrate W held by the substrate holder
18 is connected through the substrate holder 18 to a cathode of the
power supply 210. The power supply 210 also serves to apply a
voltage between a dummy anode (not shown) provided in the plating
tank 34 and a cathode so as to perform a dummy plating process, for
example, during the time of replacement of a plating solution.
Specifically, the power supply 210 applies a voltage between the
anode 200 and the seed layer 500 of the substrate W and changes
application of the voltage so as to apply a voltage between the
dummy anode and the cathode for performing a dummy plating
process.
[0090] Generally, a power supply which is used for dummy plating at
the time of replacement of a plating solution is not used during an
actual plating process. Thus, a power supply for dummy plating is
not used for a long term and is provided uneconomically. In the
present embodiment, a single power supply 210 can be switched so as
to perform a dummy plating process and an actual plating process.
Thus, a power supply for dummy plating can be eliminated, and the
number of power supplies can be reduced.
[0091] In order to facilitate switching of the power supply 210,
the power supply 210 should preferably be automatically switched so
as to perform an actual plating process after completion of the
dummy plating process.
[0092] FIG. 5 is a plan view showing a plating apparatus including
the plating section 1 shown in FIG. 2 and other various units.
Although FIG. 5 shows that the various units are provided outside
of the frame 2 of the plating section 1, the various units may be
provided within the frame 2 of the plating section 1. A portion or
all of the various units may be disposed outside of the frame 2 of
the plating section 1.
[0093] The plating apparatus includes an ashing unit 300 for
performing an ashing process on a resist 502 applied on a surface
of a seed layer 500 of a substrate (see FIG. 1A). The ashing unit
300 is configured to apply high-energy light or electromagnetic
waves including plasma, ultraviolet rays, and far ultraviolet rays.
Accordingly, high-energy ions, photons, or electrons collide with
the resist 502 to produce an active gas, which abstracts hydrogen
from organic substances in the resist 502 or cuts principal chains
or side chains of organic substances in the resist 502. Thus, the
ashing unit 300 performs an ashing process on a surface of the
resist 502.
[0094] When a substrate is plated while a resist is used as a mask,
because the resist makes a surface of the substrate hydrophobic,
the surface of the substrate is unlikely to be brought into contact
with a plating solution to thus cause plating defects such as
insufficient plating. In the present embodiment, the ashing unit
300 performs an ashing process on the resist 502 applied on the
surface of the substrate prior to the plating process. The ashing
process can reform a hydrophobic surface of the resist 502 into a
hydrophilic surface. Thus, the surface of the substrate becomes
likely to be brought into contact with a plating solution. Further,
a hydrophilic process may be performed on the surface of the
substrate in the pre-wetting tank 26 after the ashing process to
replace a gas in the openings 502a formed in the resist 502 (see
FIG. 1A) with water and further replace the water with a plating
solution. Thus, it is pos Bible to prevent plating defects such as
insufficient plating.
[0095] The plating apparatus also includes a plating solution
management unit 302 for managing components of a plating solution
to be supplied to the plating tank 34. The plating solution
management unit 302 extracts a portion of a plating solution as a
sample from the plating tank and analyzes it. Components which have
been insufficient for a predetermined amount are added into the
plating solution through a feedback control based on the analysis
by the plating solution management unit 302, a feedforward control
estimating disturbances including the plating time or the number of
plated substrates, or a combination of the feedback control and the
feedforward control. Thus, each component in the plating solution
can be maintained within a predetermined range.
[0096] The plating solution management unit 302 can automatically
perform analysis of components in the plating solution and addition
of components which have been insufficient to the plating solution,
which have heretofore been performed by hand. Thus, the plating
solution management unit 302 can maintain each component in the
plating solution within a predetermined range. Since a plating
process is performed with a plating solution thus managed, it is
possible to maintain good properties (components), good appearance,
and good uniformity of the thickness of a plated film formed on the
substrate.
[0097] The plating apparatus includes a communication device 304
for communicating information through a communication network using
a computer. The communication device 304 transmits information on
plating results or the like to proper units or devices through a
communication network interconnecting the units or devices in the
plating section 1, the ashing unit 300, the plating solution
management unit 302, and the other units shown in FIG. 5. Thus,
required information is mutually transmitted through the
communication device 304 so as to control the units or devices
based on the information to achieve a fully automatic plating
process.
[0098] The plating apparatus also includes a resist stripping unit
306, a seed layer removal unit 308, an annealing unit 310, and a
reflowing unit 312. The resist stripping unit 306 immerses the
resist 502 formed as a mask on the substrate in a solvent, such as
acetone, having a temperature of, for example, 50 to 60.degree. C.
to strip and remove the resist 502 after the plating process. The
seed layer removal unit 308 removes portions of the seed layer 500
(see FIG. 1C), which have been unnecessary after the plating
process, formed on a surface of the substrate. The annealing unit
310 anneals the plated film 504 (see FIG. 1D) formed on the surface
of the substrate. The reflowing unit 312 reflows the plated film
504 formed on the surface of the substrate.
[0099] In the present embodiment, the plating apparatus has the
annealing unit 310 and the reflowing unit 312. The plated film 504
is reflowed by the reflowing unit 312 to form a bump 506 (see FIG.
1E), which is rounded by surface tension. Alternatively, the plated
film 504 is annealed, for example, at 100.degree. C. or more by the
annealing unit 310 to remove residual stress in the bump 506. The
reflowing and annealing may simultaneously or individually be
performed by a heat treatment unit.
[0100] From a viewpoint of continuous processing, it is desirable
that the resist stripping unit 306 should strip a resist on a
substrate while the substrate is held by a substrate holder, and
that the seed layer removal unit 308 should remove unnecessary
portions of a seed layer on a substrate while the substrate is held
by a substrate holder. The substrate after stripping the resist or
the substrate after removing the seed layer may be returned to a
substrate cassette.
[0101] The plating apparatus includes a neutralization unit 314
having a neutralization tank for performing a neutralization
treatment on a surface of a substrate immediately after the plating
process. The neutralization unit (neutralization tank) 314 is
configured to immerse a substrate, which has been plated and
cleaned with water, in a neutralization treatment solution to
perform neutralization treatment on the substrate. The
neutralization treatment solution is set to be acescent or
alkalescent so as to have characteristics opposite to the plating
solution.
[0102] After the substrate has been plated and cleaned, acid or
alkali components contained in the plating solution may remain on
the substrate. According to the present embodiment, since the
neutralization treatment is performed on the substrate immediate
after the plating process, it is possible to eliminate adverse
influence on the resist stripping process and the seed layer
removal process, which are performed after the plating process,
from acid or alkali. For example, the neutralization treatment
solution may comprise an alkalescent solution containing trisodium
phosphate.
[0103] The plating apparatus also includes a visual inspection unit
316 for inspecting an appearance of a plated film 504 formed on a
surface of a substrate in a contact or non-contact manner. The
visual inspection unit 316 performs visual inspection of the plated
film 504 and notifies an operator through the communication device
304 when the plated film 504 has a defective appearance. At that
time, the plating apparatus is halted, and the defective substrate
is recorded in substrate processing data. Thus, the number of
defective substrates can be reduced, and the defective substrates
can be removed based on the substrate processing data.
[0104] Some substrate may have a defective appearance of a plated
film 504 for various reasons including anomaly of a plating
solution, a substrate, and a plating apparatus. If a plating
process is continued without halting the plating apparatus when a
defective substrate is produced, then the number of defective
substrates is increased. The plating apparatus in the present
embodiment can prevent such drawbacks.
[0105] The plating apparatus includes a film thickness measurement
unit 318 for measuring the film thickness of a plated film 504
formed on a surface of a substrate in a contact or non-contact
manner. The film thickness measurement unit 318 is configured to
measure a distribution of the film thickness of the plated film 504
formed on the substrate over an overall surface of the substrate.
Based on the measurement results, the film thickness measurement
unit 318 determines whether or not the substrate has good quality.
If the substrate does not have good quality, the substrate is
recorded in substrate processing data. Based on a rate of defective
substrates recorded in the substrate processing data, the plating
apparatus is halted, and an operator is notified of the anomaly
through the communication device 304.
[0106] The film thickness of a plated film formed on a substrate
may vary according to influence from patterns formed on a substrate
and conditions of the apparatus, the plating solution, and the
substrate. In some cases, the within wafer uniformity of the film
thickness of the plated film may excessively be lowered so as not
to meet the specification limits. If the plating apparatus is
operated to plate substrates continuously, then the number of
defective substrate may be increased. Even if the within wafer
uniformity of the film thickness is within the specification
limits, a subsequent polishing process may be required according to
the plating process. In such a case, it is necessary to set the
amount of polishing to be required. In the present embodiment, the
film thickness measurement unit 318 measures the film thickness of
the plated film 504 so as to remove defective substrates, which has
a low within wafer uniformity of the film thickness of the plated
film, and to set the required amount of the plated film to be
polished in a polishing unit 322.
[0107] The plating apparatus includes a plating area measurement
unit 320 for measuring an actual area in which a plated film 504 is
to be formed. The measurement is performed before the plating
process by, for example, supplying a current to the substrate. A
plating area is required to determine plating conditions. However,
a plating area cannot be known or otherwise cannot accurately be
known in some cases. In the present embodiment, an actual area
(plating area) in which a plated film 504 is to be formed is
measured before the plating process. Thus, a current value which
determines plating conditions can be accurately determined.
Accordingly, it is possible to accurately obtain a plated film
having a predetermined film thickness in a predetermined plating
time. In particular, in a case where a single substrate is plated
at a time, substrates having different plating areas can be plated
so as to have a predetermined film thickness merely by setting a
current density and a plating period of time. Accordingly, setting
of recipes is greatly facilitated.
[0108] The plating area measurement unit may comprise a measurement
device for optically scan a surface of a substrate before the
plating process to measure a plating area. For example, a substrate
is sealed at a peripheral portion and detachably held by a
substrate holder in a state such that a surface of a substrate to
be plated is exposed externally. In such a case, when the surface
of the substrate is optically scanned, a plating area can be
measured readily and quickly.
[0109] The plating apparatus also includes a polishing unit 322 for
polishing a surface of the plated film 504 (see FIG. 1E) of the
substrate by chemical mechanical polishing (CMP) or mechanical
polishing (MP) to adjust the film thickness of the plated film
504.
[0110] The plating apparatus includes a chemical liquid supply and
recovery unit 324 for supplying a chemical liquid to the plating
tank 34 and recovering the chemical liquid from the plating tank
34. Thus, the chemical liquid supply and recovery unit 324 supplies
a chemical liquid to the plating tank 34 and recovers the chemical
liquid from the plating tank 34. Accordingly, a highly corrosive or
harmful chemical liquid which would exert an adverse influence not
only on the apparatus or units but also on human bodies can readily
be handled with safe because operators are not required to handle
the chemical liquid so often.
[0111] The chemical liquid supply and recovery unit 324 is
configured to supply a chemical liquid from a chemical liquid
container, which is attached in a replaceable manner, to the
plating tank 34 and to recover the chemical liquid from the plating
tank 34 to the chemical liquid container. Specifically, a
commercially available chemical liquid tank or bottle may be used
as a chemical liquid container and attached in a replaceable
manner. Thus, a chemical liquid is supplied directly from the
available chemical liquid tank or bottle to the plating tank 34 and
recovered from the plating tank 34 directly to the available
chemical liquid tank or bottle.
[0112] When the chemical liquid tank or bottle becomes empty at the
time of supply of the chemical liquid, an operator is notified,
through the communication device 304, of a signal indicating that
the chemical liquid tank or bottle should be replenished or
replaced with a filled chemical liquid tank or bottle. At that
time, the supply of the chemical liquid is interrupted. After the
chemical liquid tank or bottle has been replenished or replaced
with a filled chemical liquid tank or bottle, the supply of the
chemical liquid is restarted.
[0113] When the chemical liquid tank or bottle becomes full at the
time of recovery of the chemical liquid, an operator is notified,
through the communication device 304, of a signal indicating that
the chemical liquid tank or bottle should be replaced with an empty
chemical liquid tank or bottle or the chemical liquid should be
discharged from the chemical liquid tank or bottle. At that time,
the recovery of the chemical liquid is interrupted. After the
chemical liquid tank or bottle has been replaced with an empty
chemical liquid tank or bottle or become empty, the recovery of the
chemical liquid is restarted.
[0114] The plating apparatus includes a plating solution
regeneration unit 326 for removing organic substances contained in
a plating solution through an activated carbon filter to regenerate
the plating solution. The plating apparatus has a plating solution
circulation system (not shown) for flowing a plating solution
through the plating solution regeneration unit 326, which includes
a replaceable activated carbon filter, and the plating tank 34.
With such a plating solution circulation system, the plating
solution flows through the activated carbon filter in the plating
solution regeneration unit 326 to remove organic substances as
additives in the plating solution. Thus, a plating solution from
which additive components (organic substances) are removed can be
returned to the plating tank 34.
[0115] During the plating process, for example, a plating solution
in which a component ratio of an additive such as an organic
component or a surface-active agent is excessively increased beyond
a predetermined range, or a plating solution in which an additive
or a surface-active agent is decomposed but remains as a waste
product can be regenerated by the plating solution regeneration
unit 326 without replacement of the plating solution, so that cost
and work for replacement with a new plating solution can remarkably
be reduced. Particularly, together with use of the plating solution
management unit 302, a plating solution can be regenerated to
substantially the same degree as a new plating solution.
[0116] The plating apparatus includes an exhaust gas treatment unit
328 for removing harmful components from gas or mist produced in
the plating apparatus and discharging harmless gas to an exterior
of the apparatus through a duct. For example, the exhaust gas
treatment unit 328 removes harmful components through a wet process
with an absorption liquid, a dry process with an absorbent, or a
condensation liquefaction process by cooling.
[0117] Generally, gas or mist produced in a plating apparatus is
harmful to other apparatuses or facilities. An exhaust duct from a
plating apparatus is generally connected and joined to a collective
exhaust duct. Accordingly, an exhaust gas which has not been
treated in the plating apparatus may react with an exhaust gas from
other apparatuses so as to exert an adverse influence on other
apparatuses or facilities. In the present embodiment, an exhaust
gas from which harmful gas and mist have been removed by the
exhaust gas treatment unit 328 is introduced into a collective
exhaust duct to prevent an adverse influence on other apparatuses
or facilities. Thus, it is possible to reduce loads on removing
harmful components in other apparatuses or facilities.
[0118] In a case of a combination of a plating process with an acid
plating solution and a plating process with a cyanic plating
solution, the plating tank should preferably have a first chamber
holding an acid plating solution and a second chamber holding a
cyanic plating solution which are separated by a partition. It is
desirable that the first chamber includes an exhaust duct to
discharge an acid gas produced from the acid plating solution, and
that the second chamber includes an exhaust duct to discharge a
cyanic gas produced from the cyanic plating solution.
[0119] For example, if a plating process with an acid plating
solution and a plating process with a cyanic plating solution are
performed in the same plating apparatus, then the plating solutions
or gas may be mixed to produce a cyanic gas. In order to prevent
such a drawback, these processes have heretofore been performed in
separate plating apparatuses. In the present embodiment, an acid
gas produced from an acid plating solution and a cyanic gas
produced from a cyanic plating solution can separately be
discharged so as to prevent the plating solutions or gas from being
mixed to produce a cyanic gas. Thus, a plating process with an acid
plating solution and a plating process with a cyanic plating
solution can be performed continuously in the same plating
apparatus. The cyanic plating solution may comprise a gold plating
solution or a silver plating solution.
[0120] The plating apparatus includes a waste water regeneration
unit 330 for regenerating waste water, which has been used in and
discharged from the plating process, to reuse a portion or all of
regenerated waste water for the plating process while discharging
the rest of the waste water to an exterior of the apparatus.
[0121] A cleaning process in the plating process requires a large
amount of cleaning water. A large amount of cleaning water having
high cleanliness and treatment of waste water which has been used
in the plating process impose large loads on existing facilities.
In the present embodiment, the plating apparatus has a completely
or partially closed system for regenerating waste water used
therein. Thus, it is possible to reduce the amount of cleaning
water having high cleanliness and loads on waste water treatment
required for the facilities. The waste water regeneration unit may
be configured to regenerate the waste water by at least one of
microfiltration, ultraviolet irradiation, ion exchange,
ultrafiltration, and reverse osmosis.
[0122] The plating apparatus includes a chemical liquid adjustment
unit 332 for removing metal impurities or organic impurities mixed
in a plating solution or generated decomposition products. The
chemical liquid adjustment unit 332 includes at least one of an
electrolytic process section, an ion exchange section, an activated
carbon process section, and a coagulation and settlement
section.
[0123] In order to maintain evaluation properties of a deposited
film, a plating solution used in a plating process should be
renewed periodically according to levels of impurities mixed in the
plating solution or accumulated decomposition products. An old
plating solution is discarded except for particular plating
solutions such as a gold plating solution, thereby causing loads on
cost and environment. In the present embodiment, impurities and
decomposition products contained in an old plating solution can be
removed by the chemical liquid adjustment unit 332 so as to
lengthen a frequency of renewal of a plating solution. Thus, it is
possible to reduce loads on cost and environment.
[0124] A bump plating process using the plating apparatus will be
described below with reference to FIGS. 6 and 7. First, a seed
layer 500 is deposited as a feeding layer on a surface of a
substrate as shown in FIG. 1A. Then, a resist 502 is applied onto
an overall surface of the seed layer 500 so as to have a height H
of, for example, 20 to 120 .mu.m. Thereafter, openings 502a having
a diameter D of about 20 to about 200 .mu.m are formed at
predetermined positions in the resist 502. Substrates having such
openings 502a are housed in a cassette 10 in a state such that
surfaces of the substrates to be plated face upward. The cassette
10 is loaded on the cassette table 12.
[0125] The substrate transfer device 22 picks out one of substrates
from the cassette 10 on the cassette table 12 and places it on the
aligner 14 to align an orientation flat or a notch of the substrate
in a predetermined direction. The substrate aligned by the aligner
14 is transferred to the ashing unit 300 to provide hydrophilicity
to the resist 502 on a surface of the substrate by an ashing
process. Then, the substrate after the ashing process is
transferred to the substrate loading/unloading unit 20 by the
substrate transfer device 22.
[0126] Two substrate holders 18 stored in the stocker 24 are lifted
and transferred to the substrate loading/unloading unit 20 by the
transporter 42 of the substrate holder transfer device 40. The
substrate holders 18 are turned through 90.degree. above the
substrate holder transfer device 40 so as to be horizontally
positioned. Then, the substrate holders 18 are lowered to place the
two substrate holders 18 simultaneously onto the loading plate 52
in the substrate loading/unloading unit 20. At that time, the
cylinder is actuated to open the movable support member 58 of the
substrate holder 18 positioned near a central portion of the
substrate loading/unloading unit 20.
[0127] The substrate transfer device 22 transfers the substrate and
inserts it into the substrate holder 18. Then, the cylinder is
actuated in an reverse manner to close the movable support member
58. Thereafter, the movable support member 58 is locked by the
locking/unlocking mechanism. After the substrate has been loaded
into one of the substrate holders 18, the loading plate 52 is slid
horizontally so as to position the other of the substrate holders
18 at the central position of the substrate loading/unloading unit
20. Another substrate is loaded into the other of the substrate
holders 18 in the same manner as described above, and then the
loading plate 52 is returned to the original position.
[0128] In the substrate holder 18, a surface of the substrate to be
plated is exposed through an opening of the substrate holder 18.
The substrate is sealed at a peripheral portion thereof by a seal
packing (not shown) so as to prevent a plating solution from
entering the peripheral portion of the substrate. The substrate is
electrically connected to a plurality of electric contacts at
portions which are not brought into contact with the plating
solution. The hands 76 of the substrate holder 18 are electrically
connected to the electric contacts. The hands 76 are connected to a
power supply to supply electric power to the seed layer 500 of the
substrate.
[0129] Then, the two substrate holders 18 each having the substrate
loaded are simultaneously held and lifted by the transporter 42 of
the substrate holder transfer device 40. The substrate holders 18
are transferred to the stocker 24 and turned through 90.degree.
above the stocker 24 so as to be vertically positioned. Then, the
substrate holders 18 are lowered so that the substrate holders 18
are held in a suspended manner in the stocker 24 and thus
temporarily received in the stocker 24. The substrate transfer
device 22, the substrate loading/unloading unit 20, and the
transporter 42 of the substrate holder transfer device 40 repeat
the above process so as to load substrates into substrate holders
18 which have been stored in the stocker 24 and hold (temporarily
receive) the substrate holders 18 in a suspended manner at
predetermined positions in the stocker 24.
[0130] The substrate holder 18 has a sensor for detecting
contacting states between the substrate and the electrical
contacts. When the sensor detects that the substrate is
insufficiently held in contact with the electrical contacts, it
outputs a signal indicating insufficient contact to a controller
(not shown).
[0131] The transporter 44 of the substrate holder transfer device
40 holds two substrate holders 18 temporarily received in the
stocker 24. The two substrate holders 18 are lifted and transferred
to the pre-wetting tank 26 by the transporter 44. Then, the two
substrate holders 18 are lowered and immersed into pure water held
in the pre-wetting tank 26 to wet surfaces of the substrates with
pure water for providing hydrophilicity to the surfaces of the
substrates. Any liquid can be used as a pre-wetting liquid in the
pre-wetting tank 26 as long as it can wet a surface of a substrate
and can replace air bubbles in openings of the seed layer with the
liquid so as to improve hydrophilicity of the surface of the
substrate. As described above, the plating apparatus may have
various kinds of pre-wetting portions so as to continuously perform
two or more types of pre-wetting processes in the pre-wetting
portions. In such a case, the plating apparatus can achieve various
types of processes.
[0132] If a substrate is detected to be insufficiently held in
contact with the electrical contacts by the sensor provided in the
substrate holder 18, the substrate holder 18 having the substrate
loaded therein is left temporarily received in the stocker 24.
Thus, even if a substrate is insufficiently held in contact with
electrical contacts when the substrate is loaded into the substrate
holder 18, a plating process can be continued without interrupting
operation of the plating apparatus. Although the substrate that is
insufficiently held in contact with the electrical contacts is not
plated, a substrate that has not been plated can be removed from
the cassette after the cassette is returned.
[0133] Then, the substrate holders 18 with the substrate are
transferred to the pre-soaking tank 28 in the same manner as
described above. The substrates are immersed in a treatment
solution such as a sulfuric acid or hydrochloric acid solution held
in the pre-soaking tank 28 to etch an oxide film, which has a high
electrical resistance, formed on the surface of the seed layer 500
so as to expose a clean metal surface as a pre-treatment process.
The substrate thus pre-treated is transferred to the plating area
measurement unit 320 to measure an actual area in which a plated
film 504 is to be formed. The measurement is performed by, for
example, supplying a current to the seed layer 500 of the
substrate. Then, the substrate holders 18 with the substrates are
transferred to the cleaning tank 30a, where surfaces of the
substrates are cleaned with pure water held in the cleaning tank
30a.
[0134] The substrate holders 18 with the cleaned substrates are
transferred to the plating tank 34 holding a plating solution and
held in a suspended manner in each of the plating units 38. The
transporter 44 of the substrate holder transfer device 40 repeats
the above process so as to transfer substrate holders 18 with
substrates to the plating units 38 in the plating tank 34 and hold
the substrate holders 18 at predetermined positions in a suspended
manner. After all of the substrate holders 18 have been held in a
suspended manner, a plating voltage is applied between anodes 200
and seed layers 500 of the substrates while the plating solution
overflows into the overflow tank 36. Simultaneously, the paddles
202 in the plating units 38 are reciprocated parallel to the
surfaces of the substrates by the paddle driving units 46. Thus,
the surfaces of the substrates are plated. At that time, the
substrate holders 18 are supported in a suspended manner at the
hands 76 on upper portions of the plating units 38. Electric power
is supplied from a plating power supply through hand support
portions, the hands 76, and electrical contacts to the seed layers
500 of the substrates.
[0135] The application of the plating voltage from the plating
power supply, the supply of the plating solution, and the
reciprocating movement of the paddles are stopped after the plating
process has been completed. The two substrate holders 18 with the
plated substrates are simultaneously held by the transporter 44 of
the substrate holder transfer device 40 and transferred to the
cleaning tank 30b. The substrate holders 18 are immersed in pure
water held in the cleaning tank 30b to clean surfaces of the
substrates with pure water. The substrate holders 18 with the
substrates are transferred to the neutralization unit
(neutralization tank) 314 and immersed into a neutralization
treatment solution to perform a neutralization process. The
substrates and the substrate holders 18 are cleaned with pure water
after the neutralization process. Then, the substrate holders 18
with the substrates are transferred to the blowing tank 32 to
remove water droplets attached to the substrate holders 18 and the
substrates by blowing air so as to dry the substrate holders 18 and
the substrates. The substrate holders 18 with the dried substrates
are returned to the stocker 24 and held at the predetermined
positions in a suspended manner.
[0136] The transporter 44 of the substrate holder transfer device
40 repeats the above process so as to return the substrate holders
18 with the plated substrates to the stocker 24 and to hold the
substrate holders 18 at predetermined positions in a suspended
manner.
[0137] The two substrate holders 18 with the plated substrates
which have been returned to the stocker 24 are simultaneously held
and placed on the loading plate 52 of the substrate
loading/unloading unit 20 by the transporter 42 of the substrate
holder transfer device 40. At that time, a substrate holder 18 that
has been temporarily received in the stocker 24 because a substrate
held in the substrate holder 18 is detected to be insufficiently
held in contact with electrical contacts by the sensor provided in
the substrate holder 18 is also transferred and placed on the
loading plate 52 of the substrate loading/unloading unit 20.
[0138] Then, the movable support member 58 of the substrate holder
18 positioned at the central portion of the substrate
loading/unloading unit 20 is unlocked by the locking/unlocking
mechanism. The cylinder is actuated to open the movable support
member 58. In this state, the plated substrate in the substrate
holder 18 is picked out and transferred to the cleaning and drying
device 16 by the substrate transfer device 22. In the cleaning and
drying device 16, the substrate is cleaned and rotated at a high
speed to spin-dry the substrate. Then, the loading plate 52 is slid
horizontally. The substrate held by the other substrate holder 18
is cleaned and dried in the same manner as described above.
[0139] After the loading plate 52 is returned to the original
position, the two substrate holders 18 from which the substrates
are unloaded are simultaneously held by the transporter 42 of the
substrate holder transfer device 40 and returned to the
predetermined positions in the stocker 24. Then, the two substrate
holders 18 with the plated substrates which have been returned to
the stocker 24 are simultaneously held and placed on the loading
plate 52 of the substrate loading/unloading unit 20 by the
transporter 42 of the substrate holder transfer device 40. Thus,
the processes as described above are repeated. All of the
substrates are unloaded from the substrate holders 18 with the
plated substrates which have been returned to the stocker 24 and
cleaned and dried. Thus, as shown in FIG. 1B, it is possible to
obtain substrates W having plated films 504 grown in the openings
502a formed in the resist 502.
[0140] Next, the cleaned and dried substrate is transferred to the
visual inspection unit 316 to inspect an appearance of the plated
films 504 formed on the surface of the substrate. The inspected
substrate is transferred to the resist stripping unit 306, where
the substrate is immersed in a solvent, such as acetone, having a
temperature of, for example, 50 to 60.degree. C. to strip and
remove the resist 502 on the substrate as shown in FIG. 1C. Then,
the substrate from which the resist 502 has been removed is cleaned
and dried.
[0141] The cleaned substrate is transferred to the film thickness
measurement unit 318 to measure a distribution of the film
thickness of the plated film 504. The measured substrate is
transferred to the seed layer removal unit 308, where unnecessary
portions of the seed layer 500 which are exposed are removed after
the plating process. Then, the substrate from which the unnecessary
portions of the seed layer 500 are removed is cleaned and
dried.
[0142] The substrate is transferred to the reflowing unit 312,
which comprises, for example, a diffusion furnace, to reflow the
plated films 504 so as to form bumps 506 which have been rounded
due to surface tension as shown in FIG. 1E. Alternatively, the
substrate may be transferred to the annealing unit 310 to anneal
the substrate at a temperature of 100.degree. C. or more so as to
remove residual stress in the bumps 506. Then, the reflowed or
annealed substrate is cleaned and dried.
[0143] The cleaned substrate is transferred to the polishing unit
322 to polish surfaces of the bumps 506 (or the plated films 504)
so as to adjust the film thickness of the substrate. The polished
substrate is cleaned and dried. Then, the substrate is returned or
unloaded to the cassette 10. Thus, a sequence of processes is
completed.
[0144] In the present embodiment, the substrate transfer device 22
has a dry hand and a wet hand. The wet hand is used only when a
plated substrate is picked out from the substrate holder 18. The
dry hand is used except when a plated substrate is picked out from
the substrate holder 18. Because the substrate holder 18 seals a
rear face of the substrate so that the rear face of the substrate
is not brought into contact with a plating solution, it is not
necessary to use a wet hand to handle the substrate. However, since
the dry hand and the wet hand are separately used, even if a
plating solution contaminates a substrate because of a flow of
rinse water or insufficient sealing, such contamination does not
cause a rear face of another substrate to be contaminated.
[0145] Bumps formed by multilayer plating include Ni--Cu-solder,
Cu--Au-solder, Cu--Ni-solder, Cu--Ni--Au, Cu--Sn, Cu--Pd,
Cu--Ni--Pd--Au, Cu--Ni--Pd, Ni-solder, Ni--Au, and the like. The
solder may comprise high melting point solder or eutectic solder.
Alternatively, bumps may be formed by Sn--Ag multilayer plating or
Sn--Ag--Cu multilayer plating and reflowed to alloy the multilayer.
Because such a process does not use Pb unlike a conventional Sn--Pb
solder, environmental problems which would otherwise be caused by
lead can be eliminated.
[0146] As described above, the plating apparatus in the present
embodiment can automatically perform a dipping-type electroplating
process on a substrate and form plated metal films suitable for
bumps on a surface of the substrate when the apparatus is operated
after a cassette housing substrates is loaded on a cassette
table.
[0147] In the present embodiment, while the substrate is held in a
sealed manner at a peripheral portion and a rear face by a
substrate holder, the substrate is transferred together with the
substrate holder for various processes. However, substrates may be
received and transferred in a substrate transfer device having a
rack. In this case, a thermally oxidized layer (Si oxide layer), an
adhesive tape film, or the like may be applied to a rear face of a
substrate to prevent the rear face of the substrate from being
plated.
[0148] In the present embodiment, a dipping-type electroplating
process is automatically performed to form bumps on a substrate.
However, a jet-type or cup-type electroplating process, in which a
plating solution is ejected upward, may automatically be performed
to form bumps on a substrate. This also holds true in the following
embodiments.
[0149] FIG. 8 is a schematic plan view showing a plating apparatus
according to a second embodiment of the present invention. As shown
in FIG. 8, the plating apparatus has a loading/unloading section
402 for loading and unloading cassettes 400 which house substrates
such as semiconductor wafers therein, a tool stocker 404 for
storing a plurality of types of tools (substrate holders) which
correspond to the sizes of substrates to be plated, a transfer
device 406 for transferring a substrate together with a tool
holding the substrate, and a plating section 408.
[0150] The loading/unloading section 402 has sensors 410 provided
at cassette holding portions on which cassettes 400 are mounted.
The sensors 410 detect the sizes of the substrates received in the
cassettes 400 on the cassette holding portions. Further, the
loading/unloading section 402 has a substrate loading/unloading
unit 412 disposed near the tool stocker 404 for loading a substrate
onto and unloading a substrate from a tool. The substrate is
transferred from the cassette 400 to the substrate
loading/unloading unit 412 by a transfer robot (not shown).
[0151] The tool stocker 404 stores a plurality of types of tools
(substrate holders) which correspond to the sizes of substrates to
be plated. The tools include a substrate holder having
substantially the same structure as shown in FIG. 3 which has the
same shape as shown in FIG. 3 but can detachably hold a substrate
having a diameter of, for example, 200 mm or 300 mm.
[0152] The plating section 408 includes a plurality of types of
plating tanks to perform various plating processes. In the present
embodiment, the plating tanks include a copper plating tank 414a to
perform a copper plating process, a nickel plating tank 414b to
perform a nickel plating process, and a gold plating tank 414c to
perform a gold plating process. The substrate is sequentially
transferred to the plating tank 414a, 414b, and 414c by the
transfer device 406. Thus, various plating processes are
sequentially performed to form bumps having a Cu--Ni--Au
multilayer. The plating tanks are not limited to the plating tanks
as described above.
[0153] In the present embodiment, the plating section 408 has a
single plating power supply 416. The power supply 416 selectively
supplies electric power through a switch 418 between a substrate
and anodes of the plating tanks in which the substrate is immersed,
so that the substrate is sequentially plated in the copper plating
tank 414a, the nickel plating tank 414b, and the gold plating tank
414c. The plating apparatus may include a sensor (not shown) for
detecting when a substrate is immersed in the plating solutions of
said plurality of plating tanks In such a case, the switch 418
switches the power supply 416 based on a signal from the
sensor.
[0154] Thus, the use of the single plating power supply 408 can
reduce the number of plating power supplies. Accordingly, the
plating apparatus can be made compact in size. Further, when
troubles occur in the plating power supply, the plating process can
be interrupted before a substrate has been plated or while a
substrate is plated. Accordingly, it is not necessary to discard
the substrate, and the substrate can be plated by the plating power
supply that has been repaired.
[0155] The plating processes in the plating apparatus will be
described below. First, a seed layer 500 is deposited on a surface
of a substrate as shown in FIG. 1A. Then, a resist 502 is applied
onto an overall surface of the seed layer 500. Thereafter, openings
502a are formed at predetermined positions in the resist 502.
Substrates having such openings 502a are housed in a cassette 400.
The cassette 400 is introduced into the loading/unloading section
402 and loaded on the cassette holding portion of the
loading/unloading section 402. At that time, the sensor 410
provided at the cassette holding portion detects the sizes of the
substrates housed in the cassette 400 and sends a signal to a
controller (not shown).
[0156] The controller sends the signal to the transfer device 406,
which selects a tool having a size suitable for a substrate housed
in the cassette 400 introduced into the loading/unloading section
402, picks out the tool from the tool stocker 404, and transfers
the tool to the substrate loading/unloading unit 412. A substrate
is picked out from the cassette 400 by the transfer robot (not
shown) and transferred to the substrate loading/unloading unit 412.
The substrate is held by the tool in the substrate
loading/unloading unit 412.
[0157] The transfer device 406 holds the substrate together with
the tool and performs a necessary process such as pretreatment on a
surface of the substrate. Then, the transfer device 406 transfers
the substrate to the copper plating tank 414a and immerses the
substrate in a plating solution of the copper plating tank 414a to
form plated copper films on a surface of the seed layer 500. The
transfer device 406 transfers the substrate together with the tool
to the nickel plating tank 414b and immerses the substrate in a
plating solution of the nickel plating tank 414b to form plated
nickel films on a surface of the plated copper film. The transfer
device 406 transfers the substrate together with the tool to the
gold plating tank 414c and immerses the substrate in a plating
solution of the gold plating tank 414c to form plated gold films on
a surface of the plated nickel film. Thus, bumps of Cu--Ni--Au
alloy are formed on the surface of the substrate. The substrate on
which the bumps are formed is returned from the substrate
loading/unloading unit 412 to the cassette 400. As with the first
embodiment, necessary processes such as cleaning are performed
between these plating processes or after these plating
processes.
[0158] If the plating apparatus is designed so as to correspond to
the size of a substrate to be plated, then a plurality of plating
apparatuses are required to correspond various sizes of substrates.
Accordingly, a large space for installation and utilities such as a
power supply are required in a clean room. According to the present
embodiment, a single plating apparatus can perform a plating
process on substrates having different sizes, so that a required
space in a clean room, which is expensive, required energy, and
required cost can be reduced while substrates having different
sizes are plated.
[0159] FIG. 9 is a schematic plan view showing a plating apparatus
according to a third embodiment of the present invention. As shown
in FIG. 9, the plating apparatus has one or more cassette tables
610 each for loading and unloading a substrate cassette housing
substrates such as semiconductor wafers, two cleaning units 612,
two pre-treatment units 614, two plating units 616, two resist
stripping units 618, two etching units 620, and two reflowing units
622. In the illustrated example, the plating apparatus has three
cassette tables 610. The cleaning units 612, the pre-treatment
units 614, the plating units 616, the resist stripping units 618,
the etching units 620, and the reflowing units 622 are independent
of each other. As shown in FIG. 9, these units are incorporated
integrally with each other so as to form two lines each including
different types of units.
[0160] The plating apparatus also has a first transfer robot 624
disposed between the cassette tables 610 and the cleaning units 612
for transferring a substrate between the cassette tables 610 and
the cleaning units 612, and a second transfer robot 626 disposed
between the two lines of the units for transferring a substrate
between these units. The second transfer robot 626 is movable along
the lines of the units.
[0161] For example, the cleaning units 612 may immerse a substrate
in pure water so as to bring a surface of the substrate into
contact with pure water to clean (or rinse) the substrate and then
spin-dry the substrate. For example, the pre-treatment units 614
may be configured to immerse a substrate in a treatment solution
such as a sulfuric acid or hydrochloric acid solution to etch an
oxide film, which has a high electrical resistance, formed on a
surface of the substrate so as to expose a clean metal surface.
Alternatively, the pre-treatment units 614 may uniformly apply a
pre-treatment solution (pre-dipping solution), which constitutes a
portion of a plating solution, onto a surface of a substrate so
that a plating solution is more likely to adhere to the surface of
the substrate.
[0162] For example, the plating units 616 may perform an
electroplating process on openings formed in a surface of a
substrate. For example, the resist stripping units 618 may be
configured to strip and remove a resist film remaining on a surface
of a substrate. For example, the etching units 620 may etch and
remove unnecessary portions of a seed layer, which are other than
bumps formed on a surface of a substrate. For example, the
reflowing units 622 may be configured to heat and reflow a
substrate to melt a plated film and form hemisphere bumps on a
surface of a substrate.
[0163] The plating processes in the plating apparatus will be
described below. First, a seed layer 500 is deposited as a feeding
layer on a surface of a substrate by sputtering or vapor
deposition, as shown in FIG. 1A. Then, a resist 502 is applied onto
an overall surface of the seed layer 500 so as to have a height H
of, for example, 20 to 120 .mu.m. Thereafter, openings 502a having
a diameter D of about 20 to about 200 .mu.m are formed at
predetermined positions in the resist 502. Substrates having such
openings 502a are housed in a substrate cassette. The substrate
cassette is loaded on the cassette table 610.
[0164] The first transfer robot 624 picks out one of substrates
from the substrate cassette on the cassette table 610 and transfers
it to one of the cleaning units 612 to clean a surface of the
substrate with pure water. The cleaned substrate is transferred to
one of the pre-treatment units 614 by the second transfer robot 626
to perform a pre-treatment process on a substrate. In the
pre-treatment unit 614, the substrate is immersed in a treatment
solution such as a sulfuric acid or hydrochloric acid solution, or
a pre-treatment solution (pre-dipping solution), which constitutes
a portion of a plating solution, is uniformly applied onto a
surface of a substrate.
[0165] The pre-treated substrate is cleaned by one of the cleaning
units 612 as needed. Then, the substrate is transferred to one of
the plating units 616 by the second transfer robot 626 to perform
an electroplating process on a surface of the substrate. Thus, as
shown in FIG. 1B, it is possible to obtain a substrate W having a
plated film 504 grown in the openings 502a formed in the resist
502.
[0166] The plated substrate W is cleaned by one of the cleaning
units 612 as needed. Then, the substrate is transferred to one of
the resist stripping units 618 by the second transfer robot 626 to
immerse the substrate in a solvent, such as acetone, having a
temperature of, for example, 50 to 60.degree. C. to strip and
remove the resist 502 on the substrate as shown in FIG. 1C.
[0167] The substrate from which the resist 502 has been removed is
cleaned as needed. Then, the substrate is transferred to one of the
etching units 620 by the second transfer robot 626 to etch and
remove unnecessary portions of a seed layer 500, which are exposed
after the plating process, as shown in FIG. 1D.
[0168] The etched substrate is cleaned by one of the cleaning units
612 as needed. Then, the substrate is transferred to one of the
reflowing units 622 by the second transfer robot 626 to heat and
reflow the plated film 504 of the substrate so as to form bumps
rounded due to surface tension as shown in FIG. 1E. Further, the
substrate is annealed at a temperature of 100.degree. C. or more so
as to remove residual stress in the bumps 506.
[0169] The reflowed substrate is transferred to one of the cleaning
units 612 by the second transfer robot 626. In the cleaning unit
612, the substrate is cleaned with pure water and spin-dried. The
spin-dried substrate is returned to the substrate cassette mounted
on the cassette table 610 by the first transfer robot 624.
[0170] As described above, according to the present embodiment, a
bump formation process including a plating process can be performed
continuously so as to reduce a space for the apparatus. Since the
plating apparatus includes independent units for performing various
processes, the plating apparatus can flexibly achieve a desired
plating process.
[0171] Although certain preferred embodiments of the present
invention have been shown and described in detail, it should be
understood that various changes and modifications may be made
therein without departing from the scope of the appended
claims.
INDUSTRIAL APPLICABILITY
[0172] The present invention is suitable for use in a plating
apparatus for forming a bump (protruding electrode), which provides
electrical connection with an electrode of a package or a
semiconductor chip, on a surface of a semiconductor wafer with use
of a resist as a mask.
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