U.S. patent application number 10/484628 was filed with the patent office on 2004-10-21 for apparatus for plating treatment.
Invention is credited to Kawakami, Katsuji, Oda, Hajime, Sawai, Keiichi.
Application Number | 20040206622 10/484628 |
Document ID | / |
Family ID | 19058174 |
Filed Date | 2004-10-21 |
United States Patent
Application |
20040206622 |
Kind Code |
A1 |
Kawakami, Katsuji ; et
al. |
October 21, 2004 |
Apparatus for plating treatment
Abstract
A plating processing device is so arranged that at least a part
of a portion touching plating liquid is made of a material whose
change rate of surface roughness in response to a removing agent is
lower than resin when the material and the resin are measured in
the same conditions. For example, a storage tank (1), a plating
processing tank (2), a buffer tank (3), and a pipe (9) are made of
hard glass and quartz glass. With this, it is possible to prevent a
plating material from being deposited as foreign body on wall
surfaces of the plating processing tank, etc.
Inventors: |
Kawakami, Katsuji;
(Fukuyama-shi, Hiroshima, JP) ; Sawai, Keiichi;
(Fukuyama-shi, Hiroshima, JP) ; Oda, Hajime;
(Okayama-shi, Okayama, JP) |
Correspondence
Address: |
NIXON & VANDERHYE, PC
1100 N GLEBE ROAD
8TH FLOOR
ARLINGTON
VA
22201-4714
US
|
Family ID: |
19058174 |
Appl. No.: |
10/484628 |
Filed: |
January 23, 2004 |
PCT Filed: |
July 24, 2002 |
PCT NO: |
PCT/JP02/07476 |
Current U.S.
Class: |
204/232 ;
257/E21.175; 257/E21.508 |
Current CPC
Class: |
H01L 2924/01088
20130101; H01L 2924/01079 20130101; H01L 2924/19043 20130101; H01L
2924/01013 20130101; H01L 2924/01005 20130101; H01L 2924/14
20130101; H01L 2924/01078 20130101; H01L 2924/01082 20130101; H01L
2924/01004 20130101; H01L 21/2885 20130101; H01L 2924/00014
20130101; H01L 2924/01006 20130101; H01L 2924/01029 20130101; H01L
24/11 20130101; H01L 2224/13099 20130101; H01L 2924/01033 20130101;
C25D 17/02 20130101; H01L 2924/00014 20130101; H01L 2224/0401
20130101 |
Class at
Publication: |
204/232 |
International
Class: |
C25B 015/08 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 25, 2001 |
JP |
2001-225130 |
Claims
1. A plating processing device which plates a plating target object
by supplying plating liquid containing a plating material and
causing said plating target object to touch said plating liquid,
and, if the plating material is deposited on an undesired position,
removes the plating material from the undesired position using a
removing agent, wherein: at least a part of a portion touching said
plating liquid is made of a material whose change rate of surface
roughness in response to the removing agent is lower than resin
when said material and the resin are measured in same
conditions.
2. The plating processing device as set forth in claim 1,
comprising: a plating processing tank for causing said plating
target object to touch said plating liquid, wall surfaces of said
plating processing tank being made of a material whose change rate
of surface roughness in response to the removing agent is lower
than resin when said material and the resin are measured in same
conditions.
3. The plating processing device as set forth in claim 1,
comprising: a plating processing tank for causing said plating
target object to touch said plating liquid; and a plating
processing tank pipe for conveying said plating liquid to said
plating processing tank, wall surfaces of said plating processing
tank pipe being made of a material whose change rate of surface
roughness in response to the removing agent is lower than resin
when said material and the resin are measured in same
conditions.
4. The plating processing device as set forth in claim 1,
comprising: a plating processing tank for causing said plating
target object to touch said plating liquid; and a storage tank for
storing said plating liquid which is to be supplied to said plating
processing tank, wall surfaces of said storage tank being made of a
material whose change rate of surface roughness in response to the
removing agent is lower than resin when said material and the resin
are measured in same conditions.
5. The plating processing device as set forth in claim 4, further
comprising: a heating tank for containing said storage tank so as
to heat said plating liquid in said storage tank using heat
conduction.
6. The plating processing device as set forth in claim 1, further
comprising: a plating processing tank for causing said plating
target object to touch said plating liquid; a plating processing
tank pipe for conveying said plating liquid to said plating
processing tank; and an ultrasonic flowmeter provided at a portion
of said plating processing tank pipe, wall surfaces of said portion
of said plating processing tank pipe being made of a material whose
change rate of surface roughness in response to the removing agent
is lower than resin when said material and the resin are measured
in same conditions.
7. The plating processing device as set forth in claim 1, wherein:
said material whose change rate of surface roughness in response to
the removing agent is lower than resin when said material and the
resin are measured in same conditions is glass.
8. The plating processing device as set forth in claim 7, wherein:
said glass is hard glass.
9. The plating processing device as set forth in claim 7, wherein:
said glass is quartz glass.
Description
TECHNICAL FIELD
[0001] The present invention relates to a plating processing device
used in, for example, a device for manufacturing semiconductor
integrated circuits, etc.
BACKGROUND ART
[0002] Electronic devices such as portable digital assistants have
become smaller in size and lighter in weight. In response to this,
compactness, lightness in weight, and high packaging density have
been required for semiconductor integrated circuits mounted on
these electronic devices.
[0003] A commonly used method to achieve the compactness and high
packaging density of semiconductor integrated circuits, etc.
(hereinafter referred to as semiconductor devices) is to use a
so-called bump electrode. With this method, plating technique is
applied to form a bump electrode of gold (Au) on a predetermined
position on a surface of the semiconductor device, and the bump
electrode is used to directly package the semiconductor device on a
packaging substrate.
[0004] FIG. 3 shows an outline of a conventional plating processing
device.
[0005] FIG. 3 shows a storage tank 51, a plating processing tank
52, a buffer tank 53, a circulating pump 54, a float-type flowmeter
55, filters 56, a heat exchanging unit 57, and pipes 58. The
storage tank 51, the plating processing tank 52, the buffer tank
53, the heat exchanging unit 57, and the pipes 58 are made of resin
material.
[0006] Plating liquid pressurized at the circulating pump 54 flows
into the storage tank 51. The flow rate of the plating liquid
flowed into the storage tank 51 is adjusted at the storage tank 51,
and the plating liquid flows into the plating processing tank 52 at
a predetermined flow rate (by the weight of the liquid itself).
Then, the plating liquid flows out of an outlet of the plating
processing tank 52, and flows into the buffer tank 53. The flow
rate of the plating liquid is raised again at the circulating pump
54, and the plating liquid flows into the storage tank 51.
[0007] During the circulation of the plating liquid, air bubbles
may be generated in the plating liquid due to cavitation in the
circulating pump. If the air bubbles adhere to a surface of a
substrate, the air bubbles inhibit the growth of plating, and in
the worst case, cause abnormal plating (abnormal thickness and
defective shape of plating). In order to remove the air bubbles,
the plating processing device is arranged so that the plating
liquid pressurized at the circulating pump flows into the storage
tank so as to release into the air the air bubbles in the liquid,
and then the plating liquid flows into the plating processing tank
52 by the weight of the plating liquid itself without being
pressurized, for example.
[0008] In the plating processing, the control of the flow volume of
plating liquid and the control of the temperature of the plating
liquid are also important for controlling the speed of metal
deposition and the uniformity of the speed of metal deposition over
the substrate, namely for controlling the plating thickness.
[0009] The flow volume of plating liquid is controlled by the
float-type flowmeter 55 provided at the pipe from the storage tank
51 to the plating processing tank 52. The temperature of the
plating liquid is controlled by the heat exchanging unit 57 (warm
water is circulated inside bundled resin tubes so as to indirectly
adjust the temperature) immersed in the buffer tank 53.
[0010] Due to the nature of the plating liquid, the plating
processing may deposit plating metal on the plating liquid
circulating pipes, the circulating pump, or the plating tank
itself, for example, other than the predetermined position on the
substrate. A part of the metal deposited on the position other than
the predetermined position exfoliates from the deposited position
and floats as foreign body in the plating liquid. The foreign body
moves inside the plating processing device in accordance with the
flow of the plating liquid. If the foreign body adheres to the
surface of the substrate, the foreign body causes abnormal plating
(abnormal thickness and defective shape of plating) in the worst
case. To remove the foreign body, the filter 56 is provided after
the circulating pump, for example. Further, the filter 56 is also
provided directly before the plating processing tank 52, as shown
in FIG. 3.
[0011] The foreign body floating in the plating liquid is removed
by the filter, but the deposited matter adhering to the inner walls
of the plating processing tank, etc. cannot be removed by the
filter. Such deposited matter can cause defects such as the
clogging of the pipes and the increase of the foreign body. Thus,
the pipes and the plating processing tank, etc. are regularly
washed using a halogenated chemical (such as aqua regia and
iodine).
[0012] As described earlier, due to the nature of the plating
liquid, metal is deposited on a portion where the plating liquid
touches, such as the inner walls of the plating processing tank and
pipes, in addition to the desired position. Since most of the metal
deposited on the undesired portion adheres to the inner wall
surfaces as in the plating processing tank, the inner walls are
regularly washed using a halogenated chemical so as to remove the
deposited metal.
[0013] A conventional problem is that it is difficult to easily and
effectively prevent the plating material from being deposited as
the foreign body in the plating processing.
DISCLOSURE OF INVENTION
[0014] In view of the foregoing problems, an object of the present
invention is to provide a plating processing device capable of
easily and effectively preventing a plating material from being
deposited as foreign body in the plating processing.
[0015] In order to achieve the foregoing object, a plating
processing device of the present invention which plates a plating
target object by supplying plating liquid containing a plating
material and causing the plating target object to touch the plating
liquid, and which, if the plating material is deposited on an
undesired position, removes the plating material from the undesired
position using a removing agent is so arranged that at least a part
of a portion touching the plating liquid is made of a material
whose change rate of surface roughness in response to the removing
agent is lower than resin when the material and the resin are
measured in same conditions.
[0016] With this arrangement, at least a part of a portion touching
the plating liquid is made of a material whose change rate of
surface roughness in response to the removing agent is lower than
resin when the material and the resin are measured in the same
conditions.
[0017] Thus, when the removing agent is applied to the plating
material that is deposited on the undesired position during the
plating processing, the surface of the portion touching the plating
liquid is not easily roughened if the portion is made of the above
material instead of resin. As the surface is not easily roughened,
accelerating the deposition of the plating material due to the
irregularities caused by the roughness is prevented.
[0018] Therefore, it is possible to easily and effectively prevent
the plating material from being deposited as foreign body in the
plating processing.
[0019] Alternatively, the plating processing device of the present
invention is arranged so as to include a plating processing tank
for causing the plating target object to touch the plating liquid,
wall surfaces of the plating processing tank being made of a
material whose change rate of surface roughness in response to the
removing agent is lower than resin when the material and the resin
are measured in same conditions.
[0020] With this arrangement, wall surfaces of the plating
processing tank are made of a material whose change rate of surface
roughness in response to the removing agent is lower than resin
when the material and the resin are measured in the same
conditions. Therefore, in addition to the effect of the foregoing
arrangement, it is possible to more easily and effectively prevent
the plating material from being deposited as foreign body in the
plating processing.
[0021] Alternatively, the plating processing device of the present
invention is arranged so as to include a plating processing tank
for causing the plating target object to touch the plating liquid;
and a plating processing tank pipe for conveying the plating liquid
to the plating processing tank, wall surfaces of the plating
processing tank pipe being made of a material whose change rate of
surface roughness in response to the removing agent is lower than
resin when the material and the resin are measured in same
conditions.
[0022] With this arrangement, wall surfaces of the plating
processing tank pipe are made of a material whose change rate of
surface roughness in response to the removing agent is lower than
resin when the material and the resin are measured in the same
conditions. Therefore, in addition to the effect of the foregoing
arrangement, it is possible to more easily and effectively prevent
the plating material from being deposited as foreign body in the
plating processing.
[0023] Alternatively, the plating processing device of the present
invention is arranged so as to include a plating processing tank
for causing the plating target object to touch the plating liquid;
and a storage tank for storing the plating liquid which is to be
supplied to the plating processing tank, wall surfaces of the
storage tank being made of a material whose change rate of surface
roughness in response to the removing agent is lower than resin
when the material and the resin are measured in same
conditions.
[0024] With this arrangement, wall surfaces of the storage tank are
made of a material whose change rate of surface roughness in
response to the removing agent is lower than resin when the
material and the resin are measured in the same conditions.
Therefore, in addition to the effect of the foregoing arrangement,
it is possible to more easily and effectively prevent the plating
material from being deposited as foreign body in the plating
processing.
[0025] Alternatively, the plating processing device of the present
invention is arranged so as to include a heating tank for
containing the storage tank so as to heat the plating liquid in the
storage tank using heat conduction.
[0026] With this arrangement, the plating liquid in the storage
tank is heated using heat conduction. Accordingly, a member
directly touching the plating liquid needs not be used as the heat
exchanging unit for adjusting the temperature. Therefore, in
addition to the effect of the foregoing arrangement, it is possible
to easily and effectively prevent the plating material from being
deposited as foreign body in the plating processing.
[0027] Alternatively, the plating processing device of the present
invention is arranged so as to include a plating processing tank
for causing the plating target object to touch the plating liquid;
a plating processing tank pipe for conveying the plating liquid to
the plating processing tank; and an ultrasonic flowmeter provided
at a portion of the plating processing tank pipe, wall surfaces of
the portion of the plating processing tank pipe, where the
ultrasonic flowmeter is provided, being made of a material whose
change rate of surface roughness in response to the removing agent
is lower than resin when the material and the resin are measured in
same conditions.
[0028] With this arrangement, wall surfaces of the portion of the
plating processing tank pipe where the ultrasonic flowmeter is
provided are made of a material whose change rate of surface
roughness in response to the removing agent is lower than resin
when the material and the resin are measured in the same
conditions. The ultrasonic flowmeter is provided at a position that
does not touch the plating liquid. From there, the ultrasonic
flowmeter can project an ultrasonic signal onto the plating liquid
that flows inside the plating processing tank pipe, so as to
measure the flow volume of the plating liquid in response to a
signal reflected from the plating liquid. Therefore, in addition to
the effect of the foregoing arrangement, it is possible to easily
and effectively prevent the plating material from being deposited
as foreign body in the plating processing.
[0029] For a fuller understanding of the nature and advantages of
the invention, reference should be made to the ensuing detailed
description taken in conjunction with the accompanying
drawings.
BRIEF DESCRIPTION OF DRAWINGS
[0030] FIG. 1 is an explanatory diagram showing an embodiment of a
plating processing device of the present invention.
[0031] FIG. 2 is an explanatory diagram showing change rates of
surface roughness of materials in response to a halogenated
chemical (iodine).
[0032] FIG. 3 is an explanatory diagram showing an arrangement of a
conventional plating processing device.
BEST MODE FOR CARRYING OUT THE INVENTION
[0033] The following will explain an embodiment of the present
invention with reference to FIGS. 1 and 2.
[0034] A conventional plating processing device is arranged so that
components including a plating processing tank and pipes are made
of resin material.
[0035] It was revealed that the surface roughness of the resin
increases after repeatedly washed using a halogenated chemical
(removing agent). FIG. 2 shows the results.
[0036] PVDF resin (Polyvinylidene fluoride) and PFA resin
(Tetrafluoroethylene PerFluoroAlkylvinylether copolymer) are used
for plating processing tank and a storage tank. After the PVDF
resin and the PFA resin are immersed in iodine solution for a week
at room temperature, the surface roughness (Ra: average roughness
along the center line) of the resins increases by 70% to 158% with
respect to the initial values.
[0037] In accordance with the changes in the surface roughness
(increase of the surface roughness), the degree of activation of
the irregularities that are formed on the surface changes. These
irregularities supposedly serve as the cores to accelerate the
deposition of metal which is the plating material.
[0038] In contrast, the surface roughness of hard glass and quartz
glass (hereinafter referred to as glass) changes quite little,
namely by 0% to 10%, after the glass is immersed in the same iodine
solution, as shown in FIG. 2. As it is not possible to completely
prevent metal from being deposited on a portion other than a
predetermined position on a substrate (plating target position on a
plating target object), regular washing using the halogenated
chemical is indispensable. Therefore, the inner wall surfaces
(surfaces touching the plating liquid) of the plating processing
device need to be made of a material that is not roughened after
repeatedly washed using the halogenated chemical.
[0039] The substrate to be plated should be plated in a uniform
thickness. To achieve this, the control of the flow volume of
plating liquid and the control of the temperature of the plating
liquid are also important as described earlier.
[0040] The flow volume of plating liquid is conventionally measured
by a float-type flowmeter. This type of flowmeter obtains a numeral
value of the flow volume by floating a float in the plating liquid
in such a manner that the float responds to the flow volume. Thus,
the float itself obstructs the liquid flow. Further, incorporating
the flowmeter complicates the arrangement of the pipes. This
increases a liquid contact area (area that touches liquid) of the
pipes with respect to the plating liquid. Accordingly, metal is
easily deposited on portions such as the inside of the flowmeter
and the bending portions of the pipes, as well as on the float
itself. Consequently, the deposited matter accumulated in
accordance with operating time can prevent the stable and correct
measurement of the flow volume.
[0041] As a method to measure the flow volume of a chemical, there
is a method to use ultrasonic waves which can measure the flow
volume without touching the liquid. This method is to project an
ultrasonic signal onto fluid in the pipes so as to read a signal
transmitted from the fluid, thereby correctly measuring the flow
rate and flow volume. This method cannot be used in the plating
processing device whose pipes are made of resin, however, because
the transmission signals cannot be transmitted and received
correctly, as the inner wall surfaces of the resin pipes are
roughened and metal is deposited on the roughened inner wall
surfaces.
[0042] The temperature of the plating liquid is controlled by the
heat exchanging unit in the buffer tank. The heat exchanging unit
is prepared by bundling resin tubes. Since resin has poor heat
conductivity, a large liquid contact area is required for desirable
heat exchange. In combination with this structure of the heat
exchanger, metal as the plating material is easily deposited on the
heat exchanging unit made of resin.
[0043] The temperature of the plating liquid is preferably
controlled directly before the plating processing tank. In the
conventional plating processing device, however, metal is easily
deposited on the heat exchanging unit because the heat exchanging
unit is made of resin. For this reason, the plating liquid whose
temperature is controlled at the buffer tank is pressurized at the
circulating pump so as to pass through the filter before flowing
into the storage tank. This increases the length of the pipes to
such an extent as to cause the temperature drop of the plating
liquid, thereby hindering the correct temperature control. This
also increases the deposition of metal in accordance with the
increase of the liquid contact area.
[0044] Further, in the conventional plating processing device, the
filter 56 is also provided directly before the plating processing
tank 52 as shown in FIG. 3. The filter 56 is provided to remove
metal foreign body deposited on portions such as the storage tank
51, the flowmeter 55, and the inside of the pipes between the
storage tank 51 and the plating processing tank 52. A predetermined
pressure needs to be applied to the chemical in order to remove the
foreign body using the filter. However, a pressurizing pump cannot
be provided between the storage tank 51 and the plating processing
tank 52, so as not to cause the cavitation. Thus, the chemical
needs to be pressurized by being dropped (by its own weight). In
order to obtain a predetermined pressure, it is necessary to place
the storage tank 51 at a preferable height, and replace the filter
in response to the clogging of the filter (decrease of the flow
volume). This can increase the time and cost for maintenance.
[0045] (A) Minimizing the liquid contact area where the plating
processing device touches the plating liquid and (B) arranging the
plating processing device to be made of a material whose roughness
does not change on the inner wall surfaces after regularly washed
using a cleansing agent such as a halogenated chemical were
revealed to be effective in preventing the deposition of metal
(plating material) such as gold on a portion other than the
predetermined position on the substrate (plating target position on
the plating target object). With this, it is possible to remarkably
reduce the foreign body generated in the plating processing device,
reduce the number of filters conventionally required for removing
the foreign body, and reduce the maintenance time and cost required
for exchanging the filters.
[0046] As described earlier, the pipes, the plating processing
tank, etc. need to be regularly washed using a halogenated chemical
(such as aqua regia and iodine). Note that, the steps of forming a
bump electrode of gold (Au) on a semiconductor integrated circuit
will be outlined later.
[0047] As described earlier, FIG. 2 shows the change rates of the
surface roughness of resin materials and glass materials used in
the plating processing device, in the case where the halogenated
chemical is used for washing. The resin materials do not
significantly differ from the glass materials in terms of the
surface roughness inside the pipes before washing (initial value).
After immersed in a chemical (iodine) for a week, the surface
roughness of the resin materials significantly changes such that
the change rates are 70% to 158% with respect to the initial
values. On the other hand, the changes rates of the glass materials
are significantly small, namely 0% to 10%. It is preferable that
the change rate of the surface roughness is as small as
possible.
[0048] If the change rate of the surface roughness is high, namely
if the inner walls have more irregularities, metal is easily
deposited on the inner walls of the tanks and pipes, using the
irregularities as the cores. Therefore, it is necessary to replace
the tanks and pipes after carrying out one or several operations of
the washing using the chemical.
[0049] The present embodiment is so arranged that the components of
the plating processing device are made of glass which is a material
that is not or almost is not roughened on the inner wall surfaces
after repeatedly washed using a halogenated chemical. This prevents
metal from being deposited on the inner wall surfaces.
[0050] As glass has higher heat conductivity than resin, the
temperature of the plating liquid is controlled by immersing in a
heating tank the storage tank made of glass. This eliminates the
need for the heat exchanging unit, thereby remarkably reducing the
liquid contact area with respect to the plating liquid. Further, it
is possible to control the temperature of the plating liquid at a
position closer to the plating processing tank, thereby stabilizing
the processing temperature.
[0051] The deposition of metal is prevented inside the storage
tank, the plating processing tank, and the pipe connecting the
tanks, by making all of them with glass material. With this, the
filter is not required between the storage tank and the plating
processing tank, thereby eliminating the cost and time for
maintenance such as the regular exchanging of the filter, etc.
Further, the required difference in elevation between the storage
tank and the plating processing tank is only such a difference as
to cause the plating liquid to flow, thereby reducing the size of
the plating processing device.
[0052] Further, by making the pipe with glass, the deposition of
metal is prevented on the inner wall surfaces of the pipe. With
this, it is possible to use an ultrasonic flowmeter that can
measure the flow volume without touching the liquid, thereby
simplifying the arrangement of the pipes.
[0053] In accordance with an embodiment of the present invention,
the following will explain in detail a plating processing device
used in the manufacturing process of semiconductor integrated
circuits, with reference to the drawings.
[0054] Note that, the chemicals, etc. used in the following
explanation are basically the same with the chemicals generally
used for manufacturing semiconductor integrated circuits, and are
used in the same conditions. Thus, their detailed description is
omitted here expect for special cases.
[0055] First, the following will explain a method for manufacturing
a semiconductor integrated circuit using the plating processing
device of the present embodiment, namely, steps of forming a bump
electrode on a semiconductor substrate using gold (Au) plating.
[0056] The semiconductor substrate, which is used as a substrate to
be plated (plating target substrate) in the present embodiment, is
arranged to mount a plurality of semiconductor integrated circuits,
and is manufactured in the steps as described below.
[0057] An insulating film such as SiO.sub.2 is layered to have a
predetermined thickness on an entire surface of a semiconductor
substrate which mounts a semiconductor integrated circuit. The
semiconductor substrate is a silicon wafer having a diameter of
eight inches (approximately 200 mm), for example. Then,
photolithography and insulating film etching are used to remove a
predetermined portion of the insulating film.
[0058] Next, a metal thin film such as Al--Si is layered to have a
thickness of approximately 1 .mu.m on the entire surface of the
wafer. Then, photolithography and metal thin film etching are used
to form a pad electrode which is an output and input terminal.
Here, the pad electrode has a size of approximately 60
.mu.m.times.110 .mu.m. Further, also formed here is wiring for
mutually connecting elements such as transistors that are mounted
on the surface of the wafer.
[0059] Next, an insulating film such as a SiN film, as a surface
protection film, is layered to have a thickness of approximately
0.6 .mu.m on the entire surface of the wafer. Then, a known method
such as photolithography and insulating film etching are used to
remove a predetermined portion of the surface protection film, so
as to reveal the pad electrode. The opening portion of the surface
protection film has a size of approximately 30 .mu.m.times.80
.mu.m, for example.
[0060] After this, as barrier metal, TiW is layered to have a
thickness of approximately 0.2 .mu.m and Au is layered to have a
thickness of 2 .mu.m. Then, photo resist is used to form a mask for
plating. Using the mask, a known plating technique is used to
deposit gold (Au) having a thickness of approximately 18 .mu.m on a
portion above the pad electrode so as to form a bump electrode. The
size of the bump electrode is approximately 30 .mu.m.times.80
.mu.m, for example, as described above. The following will explain
this in detail.
[0061] Namely, a metal thin film is layered to have a predetermined
thickness on the entire surface of the wafer. The metal thin film
prevents the reaction between (A) Au with which the bump electrode
is to be formed and (B) Al or Al alloy with which the pad electrode
is formed, and functions as so-called current film for electrolytic
plating. The metal thin film is also called base metal. Note that,
the base metal may be a single layer of metal thin film, but is
usually a layered film in which a plurality of metals are layered,
for preventing the reaction between Au and Al or Al alloy, or other
reasons. The base metal is prepared by sequentially layering TiW to
have a thickness of approximately 0.2 .mu.m and Au to have a
thickness of 0.2 .mu.m.
[0062] Next, photo resist is applied to the entire surface of the
wafer. Then, photolithography is used to remove a predetermined
portion of the photo resist on the wafer, namely a portion of the
photo resist that is on the opening portion of the surface
protection film.
[0063] With these steps, the semiconductor substrate 4 is formed.
The semiconductor substrate 4 is a substrate to be plated in the
next, plating step. Note that, the photo resist remaining on the
wafer functions as a mask in the plating step, so as to deposit
plating metal on the opening portion of the photo resist.
[0064] Further, the following will explain the plating step of
forming a bump electrode on the semiconductor substrate 4 using Au
plating. The plating processing device of the present embodiment
carries out the plating step.
[0065] First, a cathode electrode of the plating processing device
is connected to a predetermined position on the base metal that is
layered on the wafer of the semiconductor substrate. Then, the
semiconductor substrate and an anode electrode (not shown) are
immersed in plating liquid that fills a plating bath 2, in such a
manner that the semiconductor substrate and the anode electrode
substantially face each other in parallel. The power source applies
a predetermined voltage across the semiconductor substrate and the
anode electrode, so as to deposit plating metal on a predetermined
portion of the semiconductor substrate, namely, on the opening
portion of the photo resist, by an electrolytic plating method.
[0066] The voltage applied across the semiconductor substrate and
the anode electrode should be appropriately set based on the size
of the semiconductor substrate, the speed of plating the
semiconductor substrate, and the like.
[0067] After the bump electrode is formed on the semiconductor
substrate in the plating step, the photo resist is removed, and
then a needless portion of the base metal is removed using the bump
electrode as a mask. Then, predetermined steps are carried out to
complete the semiconductor integrated circuit.
[0068] Next, a plating processing device of the present embodiment
will be explained in detail.
[0069] FIG. 1 is a diagram schematically showing an arrangement of
the plating processing device in accordance with the present
embodiment.
[0070] FIG. 1 shows a storage tank 1, a plating processing tank 2,
a buffer tank 3, a circulating pump 4, a filter 6, pipes (resin
pipes) 8, pipes (glass pipes) 9, a heating tank 10, and an
ultrasonic flowmeter (liquid noncontact type) 11.
[0071] The storage tank 1 has dimensions of approximately 400 mm
(length).times.100 mm (width).times.300 mm (height). The plating
processing tank 2 has dimensions of approximately 300 mm.times.100
mm.times.300 mm. The buffer tank 3 has dimensions of approximately
700 mm.times.500 mm.times.200 mm. Further, the heating tank 10
should have the height and the area of the base enough to contain
the storage tank.
[0072] The plating processing device of the present embodiment
shown in FIG. 1 is so arranged that the storage tank 1, the plating
processing tank 2, and the buffer tank 3 are made of glass, namely
hard glass or quartz glass, and the pipe 9 from the filter 6 to the
storage tank 1, and the pipe (plating processing tank pipe) 9 from
the storage tank 1 to the plating processing tank 2 are also made
of glass.
[0073] Since portions from the filter 6 to the plating processing
tank 2 are made of glass, an amount of metal deposited on the inner
wall surfaces of the tanks and pipes is fairly small in these
portions.
[0074] The pipes from the plating processing tank 2 to the filter 6
are made of resin. Because of this, metal is easily deposited on
the inner walls of these pipes, but the filter 6 can prevent the
deposited metal foreign body from flowing into the storage tank
1.
[0075] The buffer tank 3 may be made of resin, but this increases
the liquid contact area with respect to the plating liquid. This
accordingly increases the amount of the deposited metal, thereby
accelerating the clogging of the filter 6. Therefore, it is
preferable that the buffer tank 3 is also made of glass.
[0076] As the pipe 9 from the storage tank 1 to the plating
processing tank 2 is made of glass, only a fairly small amount of
metal is deposited on the inner wall surfaces of the pipe 9, so
that an ultrasonic flowmeter can be used. Unlike the pipe to which
the conventional float-type flowmeter is provided, the pipe from
the storage tank 1 to the plating processing tank 2 is fairly
simple. In combination with the effect of the use of glass, almost
no metal is deposited in the pipe from the storage tank 1 to the
plating processing tank 2, thereby eliminating the need for the
filter that is provided directly before the plating processing tank
in the conventional plating processing device. With this, the
number of filters used in the plating processing device of the
present embodiment is as about one-fifth as the number of filters
in the conventional device. This reduces cost and time required for
maintaining the plating processing device and reduces the size of
the plating processing device.
[0077] Further, in the conventional plating processing device,
deposited matter on the inner walls increases as the surface
roughness on the inner wall surfaces of the pipes increases,
because the pipes are made of resin material. This prevents a
noncontact flowmeter such as an ultrasonic flowmeter from obtaining
a stable numerical value. In the present embodiment, the deposition
inside the pipes is reduced because the pipes are made of glass
material, so that the noncontact flowmeter (ultrasonic waves) can
stably measure the numerical value. Further, the noncontact
flowmeter (ultrasonic waves) can eliminate obstructions within the
pipes such as a float, thereby stabilizing the flow volume.
[0078] The heat conductivity of resin material such as
polypropylene is 4.2 to 4.5.times.10.sup.-4
(cal/cm.multidot.sec.multidot..degree. C.), whereas the heat
conductivity of glass material such as hard glass is 26.0 to
30.0.times.10.sup.-4 (cal/cm.multidot.sec.multidot..degree. C.).
Namely, the heat conductivity of glass is one place larger than
that of resin.
[0079] For this reason, the size of the heat exchanging unit for
controlling the temperature of the plating liquid can be remarkably
reduced if the heat exchanging unit is made of glass instead of
resin. In combination with the effect of the heat exchanging unit
having a small size, the glass heat exchanging unit can reduce the
deposition of metal. With this, the temperature of the plating
liquid, which can be controlled only at the buffer tank in the
conventional plating processing device, can be controlled at the
storage tank. This enables the correct control of the temperature
of the plating liquid at a position closer to the plating
processing tank.
[0080] The heat exchanging unit may be a common heat exchanging
unit having a honeycomb shape in which thin tubes are bundled, and
may be immersed in the plating liquid of the storage tank 1. In the
present embodiment, by taking advantage of the good heat
conductivity of glass of which the storage tank 1 is made, the
temperature may be desirably controlled by directly inserting the
storage tank 1 in the heating tank 10 that is additionally
provided, as shown in FIG. 1, for example. In this case, no heat
exchanging unit is immersed in the plating liquid, thereby further
reducing the deposition of metal. The heating tank 10 may be filled
with warm water, for example, with which the plating liquid in the
storage tank 1 is warmed using heat conduction.
[0081] The foregoing explained an example where the pipe from the
plating processing tank 2 to the buffer tank 3, and the pipe from
the buffer tank 3 to the filter 6 via the circulating pump 4 are
made of resin. These pipes may be made of glass without causing no
particular problem in terms of preventing the metal deposition. But
special consideration is required to use glass material for the
pipe around the pump, because the glass may break due to the
vibration of the pump, etc.
[0082] By changing the material of the other pipes and tanks to
glass material, approximately 90% of the total liquid contact area
with respect to the plating liquid can be made of glass material.
With this, it is possible to prevent the deposition of metal on a
portion other than a predetermined position on the surface of the
semiconductor device (plating target position on the plating target
object).
[0083] FIG. 1 shows an example where an outlet of the plating
liquid from the storage tank 1 is provided at the bottom surface of
the storage tank 1, but the outlet may be provided at a side
surface of the storage tank 1. In this case, the same heating tank
10 can be also used to adjust the temperature.
[0084] Further, FIG. 1 shows an example where an inlet of the
plating liquid into the plating processing tank 2 is provided at a
side surface of the plating processing tank 2, but the inlet may be
provided at the bottom surface of the plating processing tank 2 so
as to control the thickness of the plating thickness. Of course, a
plurality of inlets may be provided to the plating processing tank
2.
[0085] With this arrangement, it is possible to prevent metal from
being deposited on the inside of the plating processing device.
This prevents metal that is exfoliated from the inside of the
device from attaching to semiconductor substrates, thereby reducing
defects in semiconductor substrates. This can also reduce the
number of filters used for removing the foreign body, thereby
reducing the cost and time for maintenance.
[0086] Further, the temperature of the plating liquid can be
controlled at a position closer to the plating processing tank,
thereby correctly controlling the temperature on a substrate to be
plated.
[0087] Here, a halogenated chemical is used as a cleansing liquid
(removing agent). This is only an example in the case of gold (Au)
plating. Alternatively, concentrated nitric acid and concentrated
sulfuric acid may be used in Cu plating, and concentrated
hydrochloric acid and dilute nitric acid may be used in Ni
plating.
[0088] The foregoing explained the present invention in detail
using the plating processing device for semiconductor integrated
circuits as an example. However, the present invention can be
applied to a plating processing device for manufacturing
semiconductor devices other than semiconductor integrated circuits.
For example, the present invention can be applied to a plating
processing device used in the manufacturing process of compound
semiconductors, and a plating processing device used in the
manufacturing process of liquid crystal panels.
[0089] Note that, a device for manufacturing semiconductor
integrated circuits of the present invention which includes a
storage tank of a plating liquid, a plating processing tank to
which the plating liquid flows from the storage tank, a buffer tank
to which the plating liquid flows from the plating processing tank,
a flowmeter which measures a flow volume of the plating liquid, a
heat exchanging unit which controls the temperature of the plating
liquid, a filter which removes foreign body from the plating
liquid, a pump which circulates the plating liquid, and pipes which
connects the tanks may be so arranged that portions touching the
plating liquid are made of a material whose change rate of surface
roughness in response to washing using a halogenated chemical is
not more than 10% with respect to an initial value of the surface
roughness.
[0090] Alternatively, the device of the present invention may be so
arranged that hard glass or quartz glass is the material whose
change rate of the surface roughness in response to the washing
using the halognated chemical is not more than 10% with respect to
the initial value.
[0091] Alternatively, the device of the present invention may be so
arranged that the flowmeter of the plating liquid measures a liquid
volume of the plating liquid using ultrasonic waves without
touching the plating liquid.
[0092] Alternatively, the device of the present invention may be so
arranged that a part of the pipes which connects the tanks is made
of hard glass or quartz glass.
[0093] Alternatively, the device of the present invention may be so
arranged that the temperature of the plating liquid is controlled
at the storage tank.
[0094] The invention being thus described, it will be obvious that
the same may be varied in many ways. Such variations are not to be
regarded as a departure from the spirit and scope of the invention,
and all such modifications as would be obvious to one skilled in
the art are intended to be included within the scope of the
following claims.
Industrial Applicability
[0095] The present invention relates to a plating processing device
used in a device for manufacturing semiconductor integrated
circuits, etc. In particular, the present invention can be used in
manufacturing semiconductor integrated circuits to be mounted in
electronic devices such as portable digital assistants, for which
compactness, lightness in weight, and high density packaging are
required.
* * * * *