U.S. patent application number 16/697582 was filed with the patent office on 2020-03-26 for copper sulfate, copper sulfate solution, plating solution, method for producing copper sulfate, method for producing semiconduct.
This patent application is currently assigned to JX Nippon Mining & Metals Corporation. The applicant listed for this patent is JX Nippon Mining & Metals Corporation. Invention is credited to Masafumi ISHII, Tomota NAGAURA.
Application Number | 20200095699 16/697582 |
Document ID | / |
Family ID | 63915556 |
Filed Date | 2020-03-26 |
United States Patent
Application |
20200095699 |
Kind Code |
A1 |
NAGAURA; Tomota ; et
al. |
March 26, 2020 |
COPPER SULFATE, COPPER SULFATE SOLUTION, PLATING SOLUTION, METHOD
FOR PRODUCING COPPER SULFATE, METHOD FOR PRODUCING SEMICONDUCTOR
CIRCUIT BOARD, AND METHOD FOR PRODUCING ELECTRONIC APPARATUS
Abstract
Copper sulfate which includes a Fe with a concentration of 0.08
ppm by mass or less.
Inventors: |
NAGAURA; Tomota; (Ibaraki,
JP) ; ISHII; Masafumi; (Ibaraki, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
JX Nippon Mining & Metals Corporation |
Tokyo |
|
JP |
|
|
Assignee: |
JX Nippon Mining & Metals
Corporation
Tokyo
JP
|
Family ID: |
63915556 |
Appl. No.: |
16/697582 |
Filed: |
November 27, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
15954289 |
Apr 16, 2018 |
10519558 |
|
|
16697582 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C25D 3/38 20130101; H01L
21/76898 20130101; H01L 21/4846 20130101; H01L 21/2885 20130101;
C25D 5/18 20130101; H01L 21/76879 20130101; C01G 3/10 20130101;
C25D 7/12 20130101; C25D 7/123 20130101; C01P 2006/80 20130101 |
International
Class: |
C25D 3/38 20060101
C25D003/38; C25D 7/12 20060101 C25D007/12; H01L 21/48 20060101
H01L021/48; H01L 21/288 20060101 H01L021/288; C01G 3/10 20060101
C01G003/10 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 28, 2017 |
JP |
2017-090247 |
Feb 6, 2018 |
JP |
2018-019614 |
Claims
1. A plating solution comprising a Fe with a concentration of 0.018
ppm by mass or less.
2. The plating solution according to claim 1, wherein the plating
solution further comprises any one, any two, any three, any four,
or five of the following items (8-1) to (8-5): (8-1) an In with a
concentration of 0.2 ppm by mass or less, (8-2) a Tl with a
concentration of 0.01 ppm by mass or less, (8-3) a Sn with a
concentration of 0.3 ppm by mass or less, (8-4) an Ag with a
concentration of 0.4 ppm by mass or less, and (8-5) an Al with
concentration of 0.04 ppm by mass or less.
3. The plating solution according to claim 1, wherein the plating
solution further comprises any one, any two, any three, any four,
or five of the following items (10-1) to (10-5): (10-1) an In with
a concentration of 0.08 ppm by mass or less, (10-2) a Tl with a
concentration of 0.01 ppm by mass or less, (10-3) a Sn with a
concentration of 0.1 ppm by mass or less, (10-4) an Ag with a
concentration of 0.2 ppm by mass or less, and (10-5) an Al with a
concentration of 0.013 ppm by mass or less.
4. The plating solution according to claim 1, wherein the plating
solution has a copper concentration of from 50 to 100 g/L.
5. The plating solution according to claim 1, wherein the plating
solution has a copper concentration of from 50 to 90 g/L.
6. A method for producing a semiconductor circuit board comprising
performing copper plating by using the plating solution according
to claim 1.
7. A method for producing an electronic apparatus comprising
producing an electronic apparatus by using a semiconductor circuit
board produced by the method for producing a semiconductor circuit
board according to claim 6.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0001] One or more embodiments of the present application relate to
copper sulfate, a copper sulfate solution, a plating solution, a
method for producing copper sulfate, method for producing a
semiconductor circuit board, and a method for producing an
electronic apparatus.
2. Description of the Related Art
[0002] Copper sulfate has been widely used as raw materials for an
electrolytic solution, a pigment, an insecticide, an antiseptic, a
mordant, a material for battery cells, a medical drug, an
electroplating solution for electronic components, such as a
semiconductor device, and the like.
[0003] For example, as copper sulfate capable of being applied to
raw materials for an electrolytic solution, a pigment, an
insecticide, an antiseptic, a mordant, a material for battery
cells, a medical drug, an electroplating solution for electronic
components, such as a semiconductor device, and the like, Japanese
Patent No. 3,987,069 describes high purity copper sulfate having a
purity of 99.99% by weight or more and a content of transition
metals, such as Fe, Cr, and Ni, of 3 ppm by weight or less.
Japanese Patent No. 3,943,583 describes high purity copper sulfate
having a purity of 99.999% by weight or more.
[0004] However, according to the various demands in recent years,
there is an increasing demand of copper sulfate having a further
reduced impurity content, as compared to the high purity copper
sulfate described in Japanese Patent Nos. 3,987,069 and
3,943,583.
[0005] For example, in the case where copper sulfate is used as a
raw material of a copper plating bath, there is a problem that
associated to the miniaturization of wiring, iron contained copper
sulfate as a raw material for a copper plating bath decreases the
conductivity of the copper film.
[0006] One or more embodiments of the present application provide
copper sulfate having a reduced iron concentration, a copper
sulfate solution, a plating solution, a method for producing copper
sulfate, a method for producing a semiconductor circuit board, and
a method for producing an electronic apparatus.
SUMMARY OF THE INVENTION
[0007] Copper sulfate according to one or more embodiments of the
present application in one aspect has a Fe concentration of 0.08
ppm by mass or less.
[0008] A copper sulfate solution according to one or more
embodiments of the present application in one aspect has a Fe
concentration of 0.019 ppm by mass or less.
[0009] A copper sulfate solution according to one or more
embodiments of the present application in another aspect has a Fe
concentration of 0.016 ppm by mass or less.
[0010] A copper sulfate solution according to one or more
embodiments of the present application in still another aspect has
a Fe concentration of 0.012 ppm by mass or less.
[0011] A method for producing copper sulfate according to one or
more embodiments of the present application in one aspect contains:
concentrating by heating a copper sulfate raw material solution
obtained by dissolving a copper raw material in concentrated
sulfuric acid; cooling the copper sulfate raw material solution
after concentrating by heating, at a cooling rate of 15.degree.
C./hr or less; and recovering a deposit deposited by the cooling in
such a manner that a recovery ratio of the deposit becomes from 3
to 50%.
[0012] A plating solution according to one or more embodiments of
the present application in one aspect has a Fe concentration of
0.018 ppm by mass or less.
[0013] A plating solution according to one or more embodiments of
the present application in another aspect has a Fe concentration of
0.012 ppm by mass or less.
[0014] A method for producing a semiconductor circuit board
according to one or more embodiments of the present application in
one aspect contains performing copper plating by using the
aforementioned plating solution.
[0015] A method for producing an electronic apparatus according to
one or more embodiments of the present application in one aspect
contains producing an electronic apparatus by using a semiconductor
circuit board produced by the aforementioned method for producing a
semiconductor circuit board.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0016] The copper sulfate according to one or more embodiments of
the present application will be described in detail below.
[0017] The copper sulfate according to one or more embodiments of
the present application has a Fe concertation of 0.08 ppm by mass
or less, and is preferably copper sulfate having a Fe concentration
of 0.05 ppm by mass or less. With a Fe concentration in the copper
sulfate of 0.08 ppm by mass or less, for example, in the case where
the copper sulfate according to one or more embodiments of the
present application is used as a raw material of a copper plating
solution, the deposition of Fe in the copper film, and the
formation crystal defects generated by the deposition of Fe can be
suppressed. As a result, the electric characteristics of a
semiconductor wafer, a printed board, and a semiconductor
integrated circuit board each having the copper film formed
thereon, or a semiconductor integrated circuit and an electronic
apparatus using them can be enhanced. The copper sulfate according
to one or more embodiments of the present application may also be
used as an electrolytic solution, a pigment, an insecticide, an
antiseptic, a mordant, a material for battery cells, and the like,
and there is a possibility that the copper sulfate can be used as a
medical drug or the like.
[0018] The copper sulfate according to one or more embodiments of
the present application may be copper sulfate that satisfies any
one, any two, any three, any four, or five of the following items
(3-1) to (3-5): [0019] (3-1) an In concentration of 1.0 ppm by mass
or less, [0020] (3-2) a Tl concentration of 0.05 ppm by mass or
less, [0021] (3-3) a Sn concentration of 1.0 ppm by mass or less,
[0022] (3-4) an Ag concentration of 1.0 ppm by mass or less, and
[0023] (3-5) an Al concentration of 0.2 ppm by mass or less.
[0024] The copper sulfate according to one or more embodiments of
the present application may further be copper sulfate that
satisfies any one, any two, any three, any four, or five of the
following items (4-1) to (4-5): [0025] (4-1) an In concentration of
0.5 ppm by mass or less, [0026] (4-2) a Tl concentration of 0.05
ppm by mass or less, [0027] (4-3) a Sn concentration of 0.5 ppm by
mass or less, [0028] (4-4) an Ag concentration of 0.8 ppm by mass
or less, and [0029] (4-5) an Al concentration of 0.15 ppm by
mass.
[0030] The copper sulfate according to one or more embodiments of
the present application may further be copper sulfate that
satisfies any one, any two, any three, any four, or five of the
following items (5-1) to (5-5): [0031] (5-1) an In concentration of
0.2 ppm by mass or less, [0032] (5-2) a Tl concentration of 0.05
ppm by mass or less, [0033] (5-3) a Sn concentration of 0.2 ppm by
mass or less, [0034] (5-4) an Ag concentration of 0.3 ppm by mass
or less, and [0035] (5-5) an Al concentration of 0.1 ppm by mass or
less.
[0036] The copper sulfate according to one or more embodiments of
the present application may further be copper sulfate that
satisfies any one, any two, any three, any four, or five of the
following items (6-1) to (6-5): [0037] (6-1) an In concentration of
0.2 ppm by mass or less, [0038] (6-2) a Tl concentration of 0.05
ppm by mass or less, [0039] (6-3) a Sn concentration of 0.2 ppm by
mass or less, [0040] (6-4) an Ag concentration of 0.05 ppm by mass
or less, and [0041] (6-5) an Al concentration of 0.09 ppm by mass
or less.
[0042] The copper sulfate according to one or more embodiments of
the present application may further be copper sulfate that
satisfies any one, any two, any three, any four, or five of the
following items (7-1) to (7-5): [0043] (7-1) an In concentration of
0.2 ppm by mass or less, [0044] (7-2) a Tl concentration of 0.05
ppm by mass or less, [0045] (7-3) a Sn concentration of 0.2 ppm by
mass or less, [0046] (7-4) an Ag concentration of 0.045 ppm by mass
or less, and [0047] (7-5) an Al concentration of 0.05 ppm by mass
or less.
[0048] The concentrations of the elements in the copper sulfate
according to one or more embodiments of the present application are
measured according to the following manners.
Analysis of Concentrations of Al, Na, K, Co, Cr, Ni, Zn, Ca, Mg,
Cd, Mn, and Pb
[0049] The concentrations of Al, Na, K, Co, Cr, Ni, Zn, Ca, Mg, Cd,
Mn, and Pb in the copper sulfate are analyzed by measuring by an
atomic absorption method after removing copper by an electrolytic
method. The measurement apparatus used is a flameless atomic
absorption device, Varian AA280Z/GTA120, produced by Agilent
Technologies, Inc. (Zeeman atomic absorption
spectrophotometer).
[0050] 1 g of a specimen of copper sulfate and ultrapure water are
placed in a 10 mL measuring flask, and the specimen is dissolved in
ultrapure water. Thereafter, ultrapure water is added to the
measuring flask until the bottom of the meniscus of the liquid in
the measuring flask reaches the marked line of the measuring flask,
so as to produce 10 mL of a copper sulfate aqueous solution.
Thereafter, the resulting copper sulfate aqueous solution is
subjected to controlled potential electrolysis for four hours with
Pt electrodes (having a Pt concentration of 99.95% by mass or more)
for an anode and a cathode (dual electrode system), so as to remove
copper from the copper sulfate aqueous solution. Thereafter, the
concentrations of Al, Na, K, Co, Cr, Ni, Zn, Ca, Mg, Cd, Mn, and Pb
are measured with the aforementioned flameless atomic absorption
device. The ultrapure water herein is water having an
electroconductivity of 0.05882 .mu.S/cm or less (with an electric
resistivity (specific resistance) of 17.0 M.OMEGA.cm or more). The
precision balance used for the measurement of the mass of the
specimen of copper sulfate is capable of measuring up to four
places of decimal. The measured value includes up to four places of
decimal. The concentration of the standard specimen of each of the
elements for the flameless atomic absorption device is 1 ppb by
mass. The aforementioned four-hour controlled potential
electrolysis is performed in such a manner that electrolysis is
performed at a current of 0.1 A for 30 minutes, then performed at a
current of 0.15 A for 60 hours, and then performed at a current of
0.25 A for 150 minutes.
[0051] The concentrations of the elements are calculated by the
following expression.
(concertation of designated element (ppm by mass))=(concentration
of designated element in copper sulfate aqueous solution (ppb by
mass)).times.(mass of aqueous solution containing collected copper
sulfate specimen dissolved therein (g))/(mass of collected copper
sulfate specimen (g)).times.10.sup.-3(ppm by mass/ppb by
mass)=(concentration of element in copper sulfate aqueous solution
(ppb by mass)).times.10(g) /1(g).times.10.sup.-3(ppm by mass/ppb by
mass)
[0052] The mass of specimen of copper sulfate in the calculation
expression is a value measured with the precision balance. The mass
of the aqueous solution containing the collected specimen of copper
sulfate dissolved therein is 10 g.
Analysis of Concentrations of Sn and As
[0053] The concentrations of Sn and As in the copper sulfate are
analyzed by measuring by an atomic absorption method after
separating Sn and As from copper by the following coprecipitation
method. The measurement apparatus used is a flameless atomic
absorption device, Varian AA280Z/GTA120, produced by Agilent
Technologies, Inc. (Zeeman atomic absorption
spectrophotometer).
[0054] 2 g of a specimen of copper sulfate, ultrapure water, and 1
mL of a 5% by mass lanthanum nitrate hexahydrate
(La(NO.sub.3).sub.36H.sub.2O) aqueous solution are mixed, and the
copper sulfate is dissolved to produce a copper sulfate aqueous
solution. Aqueous ammonia is added to the copper sulfate aqueous
solution to make pH of the copper sulfate aqueous solution of from
10 to 11. The hydroxide of copper formed by adding aqueous ammonia
is dissolved as a complex of copper and ammonium ion by adding an
excess amount of aqueous ammonia. Lanthanum becomes a hydroxide by
the addition of aqueous ammonia, and is precipitated along with Sn
and As. Thereafter, the precipitate thus formed is separated from
the liquid with filter paper. A 50% by volume nitric acid aqueous
solution (volume of concentrated nitric acid/volume of ultrapure
water: 1/1, temperature: 50 to 80.degree. C.) is added to the
resulting precipitate to dissolve the precipitate, which is then
dried. Thereafter, the product obtained by drying is dissolved in
diluted hydrochloric acid prepared from ultrapure water and
hydrochloric acid (volume of concentrated hydrochloric acid/volume
of ultrapure water: 1/9), and the resulting solution is placed in a
20 mL measuring flask. The concentrated hydrochloric acid used is
concentrated hydrochloric acid having a hydrogen chloride
concentration of 36% by mass. Ultrapure water is added to the
measuring flask until the bottom of the meniscus of the liquid in
the measuring flask reaches the marked line of the measuring flask,
so as to produce 20 mL of a solution for measurement. Thereafter,
the resulting solution for measurement is measured for the
concentrations of Sn and As with the aforementioned flameless
atomic absorption device. The ultrapure water herein is water
having an electroconductivity of 0.05882 .mu.S/cm or less (with an
electric resistivity (specific resistance) of 17.0 M.OMEGA.cm or
more). The precision balance used for the measurement of the mass
of the specimen of copper sulfate is capable of measuring up to
four places of decimal. The measured value includes up to four
places of decimal. The concentration of the standard specimen of
each of the elements for the flameless atomic absorption device is
50 ppb by mass.
[0055] The concentrations of the elements are calculated by the
following expression.
(concertation of designated element (ppm by mass))=(concentration
of designated element in solution for measurement (ppb by
mass)).times.(mass of solution for measurement (g))/(mass of copper
sulfate specimen (g)).times.10.sup.-3(ppm by mass/ppb by
mass)=(concentration of designated element in solution for
measurement (ppb by mass)).times.20 (g)/2(g).times.10.sup.-3(ppm by
mass/ppb by mass)
[0056] The mass of specimen of copper sulfate in the calculation
expression is a value measured with the precision balance. The mass
of the solution for measurement is 20 g.
Analysis of Concentrations of Fe, In, Tl, Ag, and Ti
[0057] The concentrations of Fe, In, Tl, Ag, and Ti in the copper
sulfate can be measured by an ICP-MS method. Specifically, results
obtained by measuring a specimen of copper sulfate diluted with 500
times of ultrapure water with an ICP mass spectroscope (SPW 9700),
produced by SII NanoTechnology Inc.
[0058] The analysis of the concentrations of Fe, In, Tl, Ag, and Ti
in the copper sulfate by an ICP-MS method can be performed in the
following manner.
[0059] (1) 1 (g) of a specimen of copper sulfate is collected. The
precision balance used for the measurement of the mass of copper
sulfate is capable of measuring up to four places of decimal. The
measured value includes up to four places of decimal.
[0060] (2) The specimen of copper sulfate in the item (1) and
ultrapure water are placed in a 500 mL measuring flask, and
thereafter ultrapure water (containing diluted nitric acid
depending on necessity) is added to the measuring flask until the
bottom of the meniscus of the liquid in the measuring flask reaches
the marked line of the measuring flask, so as to produce a copper
sulfate aqueous solution. The ultrapure water is water having an
electroconductivity of 0.05882 .mu.S/cm or less (with an electric
resistivity (specific resistance) of 17.0 M.OMEGA.cm or more). The
electroconductivity of water can be measured according to JIS K0552
(1994). The ultrapure water can be produced, for example, by a
commercially available ultrapure water producing equipment, such as
an ultrapure water producing equipment, RFU 400 Series, produced by
Advantec Toyo Kaisha, Ltd.
[0061] (3) The concentrations of Fe, In, Tl, Ag, and Ti in the
copper sulfate aqueous solution produced in the item (2) are
measured with an ICP mass spectroscope, such as an ICP mass
spectroscope (SPW 9700), produced by SII NanoTechnology Inc. The
resulting concentrations of Fe, In, Tl, Ag, and Ti in the copper
sulfate aqueous solution are shown by CFe (ppb by mass), CIn (ppb
by mass), CTl (ppb by mass), CAg (ppb by mass), and CTi (ppb by
mass), respectively.
[0062] The concentrations of Fe, In, Tl, Ag, and Ti are calculated
by the following expressions.
(Fe concentration (ppm by mass)=(Fe concentration in aqueous
solution of collected copper sulfate specimen (ppb by
mass)).times.(mass of aqueous solution of collected copper sulfate
specimen (g))/(mass of collected copper sulfate specimen
(g)).times.10.sup.-3(ppm by mass/ppb by mass)=CFe(ppb by
mass).times.(500(g)).times.10.sup.-3(ppm by mass/ppb by
mass)/1(g)=0.500.times.CFe(ppm by mass)
(In concentration (ppm by mass)=(In concentration in aqueous
solution of collected copper sulfate specimen (ppb by
mass)).times.(mass of aqueous solution of collected copper sulfate
specimen (g))/(mass of collected copper sulfate specimen
(g)).times.10.sup.-3(ppm by mass/ppb by mass)=CIn(ppb by
mass).times.(500 (g)).times.10.sup.-3(ppm by mass/ppb by
mass)/1(g)=0.500.times.CIn(ppm by mass)
(Tl concentration (ppm by mass)=(Tl concentration in aqueous
solution of collected copper sulfate specimen (ppb by
mass)).times.(mass of aqueous solution of collected copper sulfate
specimen (g))/(mass of collected copper sulfate specimen
(g)).times.10.sup.-3(ppm by mass/ppb by mass)=CTl(ppb by
mass).times.(500(g)).times.10.sup.-3(ppm by mass/ppb by
mass)/1(g)=0.500.times.CTl(ppm by mass)
(Ag concentration (ppm by mass)=(Ag concentration in aqueous
solution of collected copper sulfate specimen (ppb by
mass)).times.(mass of aqueous solution of collected copper sulfate
specimen (g))/(mass of collected copper sulfate specimen
(g)).times.10.sup.-3(ppm by mass/ppb by mass)=CAg(ppb by
mass).times.(500 (g)).times.10.sup.-3(ppm by mass/ppb by
mass)/1(g)=0.500.times.CAg(ppm by mass)
(Ti concentration (ppm by mass)=(Ti concentration in aqueous
solution of collected copper sulfate specimen (ppb by
mass)).times.(mass of aqueous solution of collected copper sulfate
specimen (g))/(mass of collected copper sulfate specimen
(g)).times.10.sup.-3(ppm by mass/ppb by mass)=CTi(ppb by
mass).times.(500 (g)).times.10.sup.-3(ppm by mass/ppb by mass)/1
(g)=0.500.times.CTi(ppm by mass)
[0063] The mass of specimen of copper sulfate in the calculation
expressions is a value measured with the precision balance. The
mass of the solution for measurement is 500 g.
Analysis of Concentration of Cl
[0064] The Cl concentration (chloride ion concentration) is
measured with an ion chromatograph. Specifically, the measurement
is performed with an ion chromatograph (Model ICS-1500), produced
by Dionex Corporation.
[0065] The analysis of the concentration of Cl in the copper
sulfate by an ion chromatograph can be performed in the following
manner. [0066] (1) 1 (g) of a specimen of copper sulfate is
collected. The precision balance used for the measurement of the
mass of copper sulfate is capable of measuring up to four places of
decimal. The measured value includes up to four places of decimal.
[0067] (2) The specimen of copper sulfate in the item (1) and
ultrapure water are placed in a 100 mL measuring flask, and
thereafter ultrapure water is added to the measuring flask until
the bottom of the meniscus of the liquid in the measuring flask
reaches the marked line of the measuring flask, so as to produce a
copper sulfate aqueous solution. The ultrapure water is water
having an electroconductivity of 0.05882 .mu.S/cm or less (with an
electric resistivity (specific resistance) of 17.0 M.OMEGA.cm or
more). The electroconductivity of water can be measured according
to JIS K0552 (1994). The ultrapure water can be produced, for
example, by a commercially available ultrapure water producing
equipment, such as an ultrapure water producing equipment, RFU 400
Series, produced by Advantec Toyo Kaisha, Ltd. [0068] (.sup.3) The
concentration of Cl in the copper sulfate aqueous solution produced
in the item (2) is measured with an ion chromatograph (Model
ICS-1500), produced by Dionex Corporation. The resulting
concentration of Cl in the copper sulfate aqueous solution is shown
by CCl (ppb by mass).
[0069] The concentration of Cl in the copper sulfate is calculated
by the following expression.
(Cl concentration (ppm by mass)=(Cl concentration in aqueous
solution of collected copper sulfate specimen (ppb by
mass)).times.(mass of aqueous solution of collected copper sulfate
specimen (g))/(mass of collected copper sulfate specimen
(g)).times.10.sup.-3(ppm by mass/ppb by mass)=CCl(ppb by
mass).times.(100(g)).times.10.sup.-3(ppm by mass/ppb by
mass)/1(g)=0.100.times.CCl(ppm by mass)
[0070] The mass of specimen of copper sulfate in the calculation
expressions is a value measured with the precision balance. The
mass of the solution for measurement is 100 g.
[0071] The copper sulfate according to one or more embodiments of
the present application may have a concentration of metal
impurities other than Cu of 30 ppm by mass or less in total, 25 ppm
by mass or less in total in another embodiment, 20 ppm by mass or
less in total in still another embodiment, and 15 ppm by mass or
less in total in still further another embodiment.
[0072] In one or more embodiments of the present application, the
"concentrations of metal impurities other than Cu in total" is
obtained in such a manner that Na, K, Co, Cr, Ni, Zn, Al, Ca, Mg,
Cd, Mn, Pb, Sn, As, Cl, Fe, Ag, Tl, Ti, and In are analyzed, and
the total of the concentrations of the elements obtained through
the analysis is designated as the total of concentrations of metal
impurities other than Cu.
[0073] The concentrations of Fe, In, Tl, Ag, and Sn (ppm by mass)
in the copper sulfate are measured in the same manner as described
above. The other elements described above are also measured in the
same manner as described above.
[0074] The total organic carbon (TOC) concentration in the copper
sulfate is preferably 10 ppm by mass or less, more preferably 5 ppm
by mass or less, more preferably 1 ppm by mass or less, and further
preferably 0.1 ppm by mass or less. The TOC concentration in the
copper sulfate may be measured with a total organic carbon meter
(TOC-V), produced by Shimadzu Corporation. The measurement of the
total organic carbon is performed with a copper sulfate aqueous
solution obtained by dissolving a specimen of copper sulfate with
ultrapure water (water having an electric resistivity (specific
resistance) of 17.0 M.OMEGA.cm or more) to make a copper
concentration in the copper sulfate aqueous solution of from 25 to
50 g/L. The total organic carbon (TOC) concentration in the copper
sulfate is calculated by the following expression.
(total organic carbon concentration (ppm by mass))=(total organic
carbon concentration in aqueous solution of collected copper
sulfate specimen (ppb by mass).times.(mass of aqueous solution of
collected copper sulfate specimen (g))/(mass of collected copper
sulfate specimen (g)).times.10.sup.-3(ppm by mass/ppb by mass)
[0075] The copper sulfate according to one or more embodiments of
the present application may contain anhydrous copper sulfate and/or
a hydrate of copper sulfate. Examples of the hydrate of copper
sulfate include copper sulfate monohydrate, copper sulfate
trihydrate, and copper sulfate pentahydrate. The copper sulfate
according to one or more embodiments of the present application may
contain a known hydrate of copper sulfate. In the description
herein, the scope of claim, and the abstract, the term "copper
sulfate" used is a concept that includes anhydrous copper sulfate
and/or hydrates of copper sulfate.
[0076] The copper sulfate according to one or more embodiments of
the present application may have a concentration of copper sulfate
(which is a concentration of copper sulfate pentahydrate assuming
that the copper sulfate is wholly copper sulfate pentahydrate) of
99.9% by mass or more and 99.999% by mass or less, 99.9% by mass or
more and 99.995% by mass or less in another embodiment, 99.9% by
mass or more and 99.992% by mass or less in still another
embodiment, 99.9% by mass or more and 99.99% by mass or less in
still further another embodiment, and 99.9% by mass or more and
less than 99.99% by mass in still further another embodiment.
[0077] The concentration of copper sulfate is a result of
evaluation by the following expression.
[0078] The copper concentration in a specimen of copper sulfate is
measured by a sodium thiosulfate titration method.
[0079] The measurement method of the copper concentration (sodium
thiosulfate titration method) is performed in the following
manner.
[0080] A designated amount of a specimen of copper sulfate is
collected and dissolved in ultrapure water to produce a copper
sulfate aqueous solution having a concentration of copper sulfate
of 255 g/L. The precision balance used for the measurement of the
mass of the specimen of copper sulfate is capable of measuring up
to four places of decimal. The ultrapure water herein is water
having an electroconductivity of 0.05882 .mu.S/cm or less (with an
electric resistivity (specific resistance) of 17.0 M.OMEGA.cm or
more). The measured value includes up to four places of decimal.
Thereafter, the operations of the following items (1) and (2) are
performed. [0081] (1) 2 mL of the copper sulfate aqueous solution
is collected, to which an excess amount of potassium iodide is
added.
[0082] The following reaction proceeds by adding potassium iodide
to the copper sulfate aqueous solution.
2Cu.sup.2++4KI.fwdarw.2CuI+I.sub.2+4K.sup.+ [0083] (2) The
measurement is performed by titrating the amount of 12 generated in
the reaction in (1) with sodium thiosulfate. Specifically, the
titration is performed until the violet color of iodine disappears
to form a white turbid solution. The amount (molar amount) of
sodium thiosulfate used for the titration is calculated.
[0083]
I.sub.2+2Na.sub.2S.sub.2O.sub.3.fwdarw.Na.sub.2S.sub.4O.sub.6+2Na-
I
[0084] It is assumed that the specimen of copper sulfate contains
the same amount (molar amount) of copper as the amount of sodium
thiosulfate used in the titration.
[0085] The copper concertation is measured by the following
expressions.
(mass of copper contained in copper sulfate specimen (g))=(amount
of copper contained in copper sulfate specimen (mol)).times.(atomic
weight of copper (g/mol))=(amount of sodium thiosulfate required
for titrating iodine (I.sub.2)(mol)).times.(atomic weight of copper
(g/mol))
(mass of copper sulfate pentahydrate contained in copper sulfate
specimen (g))=(mass of copper contained in copper sulfate specimen
(g).times.3.9292009(assuming that the copper sulfate is wholly
copper sulfate pentahydrate)
(concentration of copper sulfate (% by mass))=(mass of copper
sulfate pentahydrate contained in copper sulfate specimen
(g))/(mass of copper sulfate specimen (g)).times.100 (%)=(mass of
copper in copper sulfate specimen (g).times.3.9292009/(mass of
copper sulfate specimen (g)).times.100 (%)
[0086] The method for producing copper sulfate according to one or
more embodiments of the present application will be described.
[0087] A raw material containing copper and a concentrated sulfuric
acid aqueous solution are heated in a reaction vessel under
stirring to dissolve the raw material containing copper in the
concentrated sulfuric acid aqueous solution, thereby providing a
copper sulfate raw material solution. The stirring means is not
particularly limited, and for example, the solution can be stirred
by blowing air therein.
[0088] The raw material containing copper used may be commercially
available copper sulfate crystals (concentration: 95 to 99.9% by
mass). The copper sulfate crystals contain impurities, such as Na,
Mg, Al, Ca, In, Sn, Ag, and Fe. In alternative, a solution obtained
by dissolving electrolytic copper having a purity of 99.99% or more
in an aqueous solution of concentrated sulfuric acid may also be
used as the raw material containing copper. The concentrated
sulfuric acid used may be commercially available concentrated
sulfuric acid (sulfuric acid concentration: 95 to 99.9% by mass).
Water used in the aqueous solution of concentrated sulfuric acid is
preferably ultrapure water. The ultrapure water preferably has an
electric resistivity of 15 M.OMEGA.cm or more. This is because the
use of ultrapure water having an electric resistivity of 15
M.OMEGA.cm or more may reduce the impurities, such as Na, Mg, Al,
Ca, In, Sn, Ag, and Fe in the aqueous solution of concentrated
sulfuric acid in some cases, and may decrease the concentrations of
elements, such as Fe, in the resulting copper sulfate in some
cases. The electric resistivity of the ultrapure water is more
preferably 15.5 M.OMEGA.cm or more, more preferably 16.0 M.OMEGA.cm
or more, more preferably 16.5 M.OMEGA.cm or more, and more
preferably 17.0 M.OMEGA.cm or more.
[0089] Subsequently, by heating the copper sulfate raw material
solution, for example, to from 40 to 100.degree. C., preferably
approximately 100.degree. C., water in the copper sulfate raw
material solution is evaporated, and the copper sulfate raw
material solution is concentrated until the copper concentration
thereof becomes, for example, from 100 to 250 g/L. The concentrated
copper sulfate raw material solution is then gradually cooled in
the reaction vessel, and thereby crystals of copper sulfate (for
example, copper sulfate pentahydrate) can be deposited.
[0090] In the cooling step, it is necessary to control precisely
the cooling temperature until the temperature of the copper sulfate
raw material solution after concentrating by heating becomes the
cooling completion temperature, so as to make the appropriate
cooling rate. Specifically, a lower cooling rate may provide a
condition closer to the equilibrium, providing a tendency that the
impurities are hardly contained in the deposited copper sulfate,
but the impurities remain in the copper sulfate raw material
solution. Accordingly, with a lower cooling rate, the
concentrations of elements other than the elements (Cu, S, O, and
H) constituting copper sulfate pentahydrate, such as aluminum, in
the deposited copper sulfate can be decreased.
[0091] Specifically, the cooling rate of the copper sulfate raw
material solution (i.e., the rate of decreasing the temperature of
the copper sulfate raw material solution) until the temperature of
the copper sulfate raw material solution under concentrating by
heating (for example, 100.degree. C.) becomes the cooling
completion temperature is 15.degree. C./hr or less, more preferably
10.degree. C./hr or less, further preferably 7.degree. C./hr or
less, and still further preferably 5.degree. C./hr or less. The
cooling means is not particularly limited, and for example, such
cooling methods as water cooling, gradual cooling, air cooling, and
cooling with a heat exchanger may be utilized.
[0092] A deposit of copper sulfate is obtained from the copper
sulfate raw material solution through the cooling step. The
resulting copper sulfate contains copper sulfate pentahydrate as a
major component in many cases. The resulting deposit of copper
sulfate is separated by solid-liquid separation, dried, then
pneumatically conveyed, and packaged individually, and thus the
copper sulfate (crystal product) according to one or more
embodiments of the present application is obtained.
[0093] In the cooling step, the recovery condition of the deposit
of copper sulfate is preferably regulated. Specifically, the
deposit that is deposited in the initial state in the cooling step
is selectively recovered, and thereby the deposit of copper sulfate
having a smaller amount of impurities can be recovered. More
specifically, the deposit of copper sulfate is preferably recovered
in such a manner that the recovery ratio of the deposit deposited
by cooling becomes from 3 to 50%, more preferably from 5 to 35%,
and further preferably from 5 to 25%. The recovery ratio can be
evaluated by the following expression.
(recovery ratio (%))=(copper concentration in original copper
sulfate aqueous solution (g/L))-(copper concentration in copper
sulfate aqueous solution at stoppage of deposition of copper
sulfate (g/L))/(copper concentration in original copper sulfate
aqueous solution (g/L.times.100))
[0094] The method for making the recovery ratio of the deposit of
copper sulfate in a range of from 3 to 50% is preferably, for
example, a method of completing the recovery of the deposit of
copper sulfate at the time when the temperature of the copper
sulfate aqueous solution at the recovery of copper sulfate (i.e.,
the cooling completion temperature) becomes from 50 to 90.degree.
C., more preferably from 50 to 80.degree. C.
[0095] The copper sulfate solution according to one or more
embodiments of the present application can be obtained by adding a
solvent, such as ultrapure water, to the copper sulfate (crystal
product) according to one or more embodiments of the present
application, and dissolving the copper sulfate in the solvent.
Examples of the solvent for dissolving the copper sulfate include
water, one or plural organic solvents, one or plural inorganic
solvents, and a solvent containing one or more selected from the
group consisting of water, one or plural organic solvents, and one
or plural inorganic solvents. The organic solvent used may be an
alcohol, an aromatic hydrocarbon, a fatty acid, a linear
hydrocarbon, a cyclic hydrocarbon, an organic acid, or the like.
The inorganic solvent used may be an inorganic acid, such as
sulfuric acid, hydrochloric acid, nitric acid, and hydrofluoric
acid. In the case where water is used as the solvent, a copper
sulfate aqueous solution can be obtained.
[0096] Ultrapure water that is used for the copper sulfate aqueous
solution preferably has an electric resistivity of 15.0 M.OMEGA.cm
or more, more preferably 15.5 M.OMEGA.cm or more, more preferably
16.0 M.OMEGA.cm or more, more preferably 16.5 M.OMEGA.cm or more,
and more preferably 17.0 M.OMEGA.cm or more. This is because the
use of ultrapure water having an electric resistivity of 15
M.OMEGA.cm or more may decrease the concentrations of impurities,
such as Na, Mg, Al, Ca, In, Sn, Ag, and Fe in the copper sulfate
aqueous solution in some cases.
[0097] The copper sulfate solution may have a copper concentration
of approximately from 50 to 100 g/L. The copper sulfate solution
preferably has a Fe concentration of 0.019 ppm by mass or less,
more preferably 0.016 ppm by mass or less, and further preferably
0.012 ppm by mass or less. The copper sulfate solution preferably
has a TOC concentration of 1.20 ppm by mass or less. The copper
sulfate solution more preferably has a TOC concentration of 1.10
ppm by mass or less, further preferably 1.0 ppm by mass or less,
and still further preferably 0.9 ppm by mass or less.
[0098] A plating solution can be produced by using the copper
sulfate or the copper sulfate solution described above. The plating
solution according to one or more embodiments of the present
application has a Fe concentration of 0.018 ppm by mass or less,
and preferably 0.012 ppm by mass or less.
[0099] The plating solution according to one or more embodiments of
the present application may satisfy any one, any two, any three,
any four, or five of the following items (8-1) to (8-5): [0100]
(8-1) an In concentration of 0.2 ppm by mass or less, [0101] (8-2)
a Tl concentration of 0.01 ppm by mass or less, [0102] (8-3) a Sn
concentration of 0.3 ppm by mass or less, [0103] (8-4) an Ag
concentration of 0.4 ppm by mass or less, and [0104] (8-5) an Al
concentration of 0.04 ppm by mass or less.
[0105] The plating solution according to one or more embodiments of
the present application may further satisfy any one, any two, any
three, any four, or five of the following items (9-1) to (9-5):
[0106] (9-1) an In concentration of 0.13 ppm by mass or less,
[0107] (9-2) a Tl concentration of 0.01 ppm by mass or less, [0108]
(9-3) a Sn concentration of 0.2 ppm by mass or less, [0109] (9-4)
an Ag concentration of 0.3 ppm by mass or less, and [0110] (9-5) an
Al concentration of 0.020 ppm by mass or less.
[0111] The plating solution according to one or more embodiments of
the present application may further satisfy any one, any two, any
three, any four, or five of the following items (10-1) to
(10-5):
[0112] (10-1) an In concentration of 0.08 ppm by mass or less,
[0113] (10-2) a Tl concentration of 0.01 ppm by mass or less,
[0114] (10-3) a Sn concentration of 0.1 ppm by mass or less, [0115]
(10-4) an Ag concentration of 0.2 ppm by mass or less, and [0116]
(10-5) an Al concentration of 0.013 ppm by mass or less.
[0117] The plating solution according to one or more embodiments of
the present application preferably has a copper concentration of
from 50 to 100 g/L, and more preferably from 50 to 90 g/L.
[0118] The plating solution according to one or more embodiments of
the present application can be prepared by using the aforementioned
copper sulfate having a purity of 99.9% by mass or more and 99.999%
by mass or less, and copper plating can be performed by using the
plating solution. According to one or more embodiments of the
present application, an electronic apparatus can be produced by
using a semiconductor circuit board produced by performing copper
plating by using the plating solution.
EXAMPLES
[0119] While examples of one or more embodiments of the present
application are described below along with comparative examples,
the examples are provided for better understanding of one or more
embodiments of the present application and the advantages thereof,
but do not intend to restrict one or more embodiments of the
present application.
[0120] As a copper raw material, commercially available copper
sulfate (Cu: 99% or more, Na: 10 ppm, Mg: 1.5 ppm, Al: 4.5 ppm, Ca:
3.9 ppm, In: 5.6 ppm, Sn: 10 ppm, Ag: 3.5 ppm, Fe: 8.5 ppm) was
mixed with ultrapure water having an electric resistivity of 15
M.OMEGA.cm or more, and stirred under heating at 100.degree. C. to
produce a copper sulfate raw material solution. Thereafter, the
copper sulfate raw material solution was transferred to a
concentrating vessel and retained at a temperature of 100.degree.
C. for from 2 to 10 hours to evaporate water in the copper sulfate
raw material solution, thereby concentrating the solution until the
copper concentration thereof becomes from 150 to 250 g/L. The
copper sulfate raw material solution having been concentrated by
heating was transferred to a crystallizing vessel, and in the
crystallizing vessel, cooled to a temperature shown in Table 1 at a
cooling rate shown in Table 1. The treated product obtained by
cooling was subjected to solid-liquid separation by suction
filtration, and thus a deposit of copper sulfate (copper sulfate
pentahydrate) was obtained. The deposit of copper sulfate was dried
to provide a crystal product of the copper sulfate of Examples 1 to
6 and Comparative Examples 1 to 3.
[0121] The copper sulfate according to Examples 1 to 6 and
Comparative Examples 1 to 3 was measured for the concentrations of
Na, K, Co, Cr, Ni, Zn, Al, Ca, Mg, Cd, Mn, Pb, Sn, As, Cl, Fe, Ag,
Tl, Ti, and In, in copper sulfate and the concentration of copper
sulfate by the aforementioned measurement methods. The impurity
elements in copper sulfate were assumed to be Na, K, Co, Cr, Ni,
Zn, Al, Ca, Mg, Cd, Mn, Pb, Sn, As, Cl, Fe, Ag, Tl, Ti, and In, and
the total of the analysis results of the concentrations of these
elements was designated as the total concentration of impurities
other than Cu. The measurement results of the concentrations of Fe,
Al, In, Tl, Sn, and Ag in copper sulfate, the total concentration
of impurities, and the concentration of total organic carbon (TOC)
in the copper sulfate according to Examples 1 to 6 and Comparative
Examples 1 to 3 are shown in Table 1.
[0122] Copper sulfate aqueous solutions were produced with the
copper sulfate according to Examples 1 to 6 and Comparative
Examples 1 to 3, to which the prescribed additives shown later were
added to produce electroplating solutions. An SiO.sub.2 film was
accumulated on a silicon wafer by a chemical vapor deposition (CVD)
method. A Ta layer as a barrier layer was provided on the surface
of the SiO.sub.2 film by sputtering. A Cu seed layer having a
thickness of 80 nm was further formed on the Ta layer by
sputtering, and then a copper film having a thickness of 30 .mu.m
was formed by copper electroplating. A specimen of 45 g was
collected from each of the copper sulfate according to Examples 1
to 6 and Comparative Examples 1 to 3, and the specimen was
dissolved with ultrapure water (having an electric resistivity of
17 M.OMEGA.cm or more) to prepare 200 mL of a copper sulfate
aqueous solution (which had the same ratio of copper sulfate and
the other liquids as the electroplating bath shown below). The
copper sulfate aqueous solution was measured for the Fe
concentration and the total organic carbon concentration therein by
the aforementioned measurement methods, in which the specimen of
copper sulfate was replaced with the copper sulfate aqueous
solution. The results are shown in Table 2.
[0123] The electroplating bath and the electroplating conditions
are as follows.
(Electroplating Bath and Electroplating Conditions)
Electroplating Bath
[0124] A plating bath having the following composition was used as
the electroplating bath.
[0125] Copper sulfate (added as copper sulfate pentahydrate,
copper: 57.3 g/L) concentration: 225 g/L
[0126] Sulfuric acid concentration: 55 g/L
[0127] Chloride ion: 60 ppm
[0128] Polyethylene glycol (average molecular weight: 10,000)
concentration:500 mg/L
[0129] Bis(3-sulfopropyl) disulfide (SPS) concentration: 20
mg/L
[0130] Janus green concentration: 1 mg/L
[0131] The solvent used as ultrapure water (having an electric
resistivity of 15 M.OMEGA.cm or more).
Electroplating Conditions
[0132] The plating conditions were a plating bath temperature of
40.degree. C., a cathode current density of 2.0 A/dm.sup.2, an
anode current density of 2.0 A/dm.sup.2, and a plating time of from
70 to 90 minutes.
[0133] The copper film was evaluated for platability by measuring
the electric resistance by the four-probe method. In the evaluation
of platability, the case where the electric resistance was less
than 0.020.times.10.sup.-4 .OMEGA./cm was evaluated as "A", the
case where the electric resistance was 0.020.times.10.sup.-4
.OMEGA./cm or more and less than 0.040.times.10.sup.-4 .OMEGA./cm
was evaluated as "B", and the case where the electric resistance
was 0.040.times.10.sup.-4 .OMEGA./cm or more was evaluated as "C".
The results are shown in Table 2.
[0134] The recovery ratio of the copper sulfate was evaluated
according to the following.
(recovery ratio (%))=(copper concentration in original copper
sulfate aqueous solution (g/L))-(copper concentration in copper
sulfate aqueous solution at stoppage of deposition of copper
sulfate (g/L))/(copper concentration in original copper sulfate
aqueous solution (g/L))
[0135] The results are shown in Table 1.
TABLE-US-00001 TABLE 1 Cooling rate of copper sulfate raw material
solution from 100.degree. C. to Cooling cooling completion
completion Recovery Copper sulfate Inpurity concentration in copper
sulfate (ppm by mass) TOC temperature temperature ratio
concentration Total (ppm by (.degree. C./hr) (.degree. C.) (%) (%
by mass) Fe Al In Ti Sn Ag concentration mass) Example 1 5.degree.
C./hr 76 5 99.999 0.02 0.02 <0.05 <0.05 <0.05 0.15 1.52
0.18 Example 2 7.degree. C./hr 73 8 99.999 0.03 0.05 0.35 <0.05
0.30 0.60 2.36 0.89 Example 3 10.degree. C./hr 67 16 99.995 0.044
0.07 0.42 <0.05 0.61 0.83 17.02 3.33 Example 4 10.degree. C./hr
65 18 99.99 0.05 0.09 0.52 <0.05 0.71 1.10 21.35 3.81 Example 5
10.degree. C./hr 60 25 99.99 0.06 0.11 0.59 <0.05 0.79 1.15
25.98 4.32 Example 6 15.degree. C./hr 53 32 99.99 0.08 0.15 0.66
<0.05 0.91 1.55 28.13 5.26 Comparative 15.degree. C./hr 0 75
99.97 3.00 2.30 1.50 <0.05 2.60 2.50 35.56 11.45 Example 1
Comparative 15.degree. C./hr 25 64 99.999 0.09 0.09 0.10 <0.05
0.50 <0.01 1.70 5.72 Example 2 Comparative 15.degree. C./hr 25
55 99.99 0.50 0.10 0.11 <0.05 0.60 0.04 3.41 6.90 Example 3
TABLE-US-00002 TABLE 2 Inpurity concentration in copper TOC
Electric sulfate solution (ppm by mass) (ppm by resistance Fe Al In
Ti Sn Ag mass) Platability (.sup.-4 .OMEGA. cm) Example 1 0.005
0.005 <0.01 <0.01 <0.01 0.034 0.04 A 0.0221 Example 2
0.007 0.011 0.079 <0.01 0.068 0.135 0.20 B 0.0235 Example 3
0.010 0.016 0.095 <0.01 0.137 0.187 0.75 B 0.0321 Example 4
0.011 0.020 0.117 <0.01 0.160 0.248 0.86 B 0.0333 Example 5
0.014 0.025 0.133 <0.01 0.178 0.259 0.97 B 0.0349 Example 6
0.018 0.034 0.149 <0.01 0.205 0.349 1.18 B 0.0362 Comparative
0.675 0.518 0.338 <0.01 0.585 0.563 2.58 C 0.0704 Example 1
Comparative 0.020 0.020 0.023 <0.01 0.113 <0.002 1.29 C
0.0401 Example 2 Comparative 0.113 0.023 0.025 <0.01 0.135 0.009
1.55 C 0.0422 Example 3
[0136] In Examples 1 to 6, in which the cooling rate and the
recovery ratio on depositing copper sulfate pentahydrate from the
copper sulfate raw material solution were controlled to adequate
ranges, the Fe concentration was decreased to 0.08% by mass or
less, and good platability was obtained. Furthermore, the Fe
concentration of the copper sulfate solution was 0.08% by mass or
less, and further 0.02% by mass or less, and thus good platability
was obtained. In Comparative Example 1 with cooling to 0.degree. C.
at a too large cooling rate, on the other hand, the recovery ratio
was as high as approximately 70%, but Fe was not reduced, and good
platability was not obtained. In Comparative Examples 2 and 3,
copper films were formed under the same conditions as in Example 1
by using copper sulfate produced according to the methods for
producing high purity copper sulfate described in Japanese Patent
No. 3,987,069 for Comparative Example 2 and Japanese Patent No.
3,943,583 for Comparative Example 3. In both Comparative Examples 2
and 3, the iron concentration was larger than in Examples 1 to 6
although the copper sulfate concentration was large, and thus the
copper film had a large electric resistance, providing inferior
platability to Examples 1 to 6.
[0137] By using a plating solution having the aforementioned
composition, wiring formation on a semiconductor wafer,
particularly a semiconductor wafer having a through silicon via,
can be performed. Furthermore, by using a plating solution having a
composition other than as described above, for example a known
composition, such as the composition described in Japanese Patent
No. 5,388,191, wiring formation on a semiconductor wafer and wiring
formation on a semiconductor circuit board can be performed.
Accordingly, by using a plating solution having the aforementioned
composition, an integrated circuit and a semiconductor circuit
board, such as a package board having the integrated circuit
mounted, can be formed.
* * * * *