KR20180016971A - How to measure surface area of harmonized copper surface - Google Patents

Abstract

The present invention provides a method for measuring the surface area of an etched copper surface easily and with high accuracy. The above object is achieved by a method for measuring the surface area of a copper surface, comprising the steps of: removing natural copper oxide formed on the surface of a metal copper on a surface of a metal surface; A second step of forming a monomolecular layer of a dissimilar metal and a third step of dissolving the monomolecular layer of the dissimilar metal on the electrostatic charge to calculate an anode electric charge used for dissolving the monomolecular layer of the dissimilar metal, The surface area of the surface can be determined.

Description

How to measure surface area of harmonized copper surface

The present invention relates to a method for measuring the surface area of a copper surface, for example, chemically etched by a chemical etching solution, by electrochemical measurement.

As a method of maintaining a desired adhesion between copper and resin in a printed wiring board, a copper surface is roughened by a chemical etching solution, and FIGS. 4 to 6 (SEM observation of the copper surface after etching) and FIG. 7 There is a method of forming micro concavity and convexity of a complicated shape such as a cross-sectional SEM observation and obtaining an adhesion by an anchor effect. Generally, after the surface of the electroless copper is harmonized, a dry film resist is laminated. Further, after forming the pattern of the electrolytic copper, the buildup film is laminated after the upper and side portions of the wiring are matched.

The formation of the harmonic shape is performed while etching the copper surface with a small amount of about 100 nm to 250 nm in the depth direction using an etching solution. Conventionally, the presence or absence of a coarse shape and the determination of a preferable shape have been performed by visual observation or scanning electron microscope SEM observation. However, judgments based on visual observation or SEM observation can not help but depend on individual experience. In the measurement method using the surface roughness meter, Ra (calculated average roughness), Ry (maximum height), and Rz (weighted average roughness), which are parameters indicating the surface roughness, It is difficult to grasp the surface shape quantitatively.

Patent Document 1 has a comparative example in which the value of the peel strength is low and the adhesion is poor even if the Ra values are the same. The Ra value in Examples 1 to 3 in Table 1 in Patent Document 1 is 0.25 占 퐉, the peel strength is 1.10 to 1.20 kgf / cm, and the short circuit has good adhesion to the interlayer insulator. However, the Ra values of the comparative examples 1 to 4 in Table 2 are also 0.25 占 퐉, which is the same as in the Examples, but the fill strength is 0.70 kgf / cm, which is not the range of preferable fill strength described in paragraph 0027, Can not be directly related to each other.

In Patent Document 2, there is a comparative example in which the laser processing energy value is not minimized even if the Ra values are the same. In paragraph [0019] of Patent Document 2, the laser machining energy can be reduced by raising the Ra value to 0.20 탆 or more. The Ra values in Examples 1, 4 to 7, 9 and 10 in Table 3 are 0.52 탆, The laser machining energy value for the hole formation is 3 mJ. However, the Ra value in Comparative Example 3 of Table 3 in Patent Document 2 is also 0.52 占 퐉, but the laser processing energy value is not minimized to 5 mJ, and the relationship between the Ra value and the laser processing energy is not in direct proportion Able to know.

The Ra values in Patent Documents 1 and 2 are the results of measuring the harmonized surface, but as shown in Figs. 4 to 6 and Fig. 7, since the harmonic shape is complex, the Ra value is measured optically from the vertical direction of the measurement surface or mechanically measured with the probe It is difficult to obtain the surface roughness accurately, and there is a possibility that the state of the surface can not be quantitatively evaluated. In such a case, it is necessary to actually laminate a dry film resist or a build-up film to measure the peel strength, and it is troublesome to operate and it takes a long time to evaluate it, and thus it has a problem that it can not be used for process control.

As a method of evaluating the unevenness of the copper surface, there is a method of electrochemically measuring the surface area of copper using the under-potential deposition method.

In Non-Patent Document 1, the active surface area of cuprous oxide and cupric oxide having a photosensitive nanostructure formed by chemical or electrochemical oxidation used in solar power generation is measured using a thallium monolayer underpotential deposition method. First, the natural oxide copper is removed with -0.80 V vs Ag / AgCl, and subsequently, a thallium monolayer is formed with -0.69 V vs Ag / AgCl, and the potential is swept to the anode side at 50 mV / sec to dissolve the thallium.

In this method, the surface area is measured by combining the electrostatic potential method and the cyclic voltammetry method of sweeping the potential.

Non-Patent Document 1 discloses that although the surface area is measured by the electrostatic potential method and the cyclic voltammetry method, the order is complicated, and the method for quantitatively determining a more precise amount is not studied, (See Comparative Example 1).

Japanese Patent Application Laid-Open No. 2011-80131 Japanese Patent Publication No. 2013-89675

&Quot; Evaluation of electrochemically active surface area of photosensitive copper oxide nanostructures with extremely high surface roughness ", Electrochimica Acta, 98, 109-115 (2013)

An object of the present invention is to provide an electrochemical method for easily and reproducibly measuring the surface area of a copper surface harmonized by, for example, chemical etching.

The present invention has been completed on the basis of such findings. That is, the present invention is as follows.

≪ 1 > A method for measuring a surface area of a copper surface,

A first step of removing natural copper oxide generated on the surface of the metal copper on the electrostatic charge;

A second step of forming a monomolecular layer of dissimilar metals on the electrostatic charge on the surface of the copper oxide from which the natural copper oxide has been removed,

And a third step of dissolving the monomolecular layer of the dissimilar metal on the electrostatic charge,

And calculating the anode electricity amount used for dissolving the monomolecular layer of the dissimilar metal to obtain the surface area of the roughened copper surface.

<2> The method according to <1>, wherein the electrostatic potential in the first step of removing the natural copper oxide is in the range of -1.0 V to -0.75 V vs Ag / AgCl.

<3> The method according to <1> or <2>, wherein the dissimilar metal is thallium.

<4> The method according to any one of <1> to <3>, wherein the electrostatic potential in the second step of forming the monomolecular layer of the dissimilar metal is in the range of -0.74 V to -0.61 V vs Ag / to be.

<5> The measuring method according to any one of <1> to <4>, wherein the treating time in the second step is 50 to 300 seconds.

<6> The method according to any one of <1> to <5>, wherein the electrostatic potential in the third step of dissolving the monolayer is in the range of -0.50 V to 0.0 V vs Ag / AgCl.

<7> The measuring method according to any one of <1> to <6>, wherein the anode electricity amount consumed for dissolving the monolayer on the electrostatic charge is measured five times and the coefficient of variation thereof is 20% or less.

<8> The measuring method according to any one of <1> to <7>, wherein the anode electricity amount is calculated by the following formula (1).

[Equation 1]

Q _a (mC / cm ² ): anode electric quantity

i (mA / cm ² ): Corrosion current density

t (s): time

<9> The method according to <8>, wherein the obtained anode electricity quantity is converted to f _SR , which is a surface area factor according to the following equation (2).

&Quot; (2) &quot;

Q _a : the obtained anode electricity quantity

Q _TI : 112 μC cm ^-2

According to the method for measuring the surface area of the copper surface of the present invention, measurement can be performed easily and with high reproducibility.

1 is a graph showing the results of five measurements of the anode current used for thallium dissolution by the method of Comparative Example 1 (cyclic voltammetry method disclosed in Non-Patent Document 1).
Fig. 2 is a graph showing the results of five measurements of the anode current used for the dissolution of natural oxide copper, the formation of monomolecular thallium, and the dissolution of thallium in a static electric field by the method of Example 1. Fig.
3 is an SEM photograph of the copper surface before the etching treatment in Example 1. Fig.
4 is an SEM photograph of the copper surface when the etching amount in Example 1 is 150 nm.
5 is an SEM photograph of the copper surface when the etching amount in Example 1 is 200 nm.
6 is an SEM photograph of the copper surface when the etching amount in Example 1 is 250 nm.
7 is an SEM photograph of a section of the sample in Example 1. Fig.
8 is a schematic view for explaining a method of measuring the surface area of the present invention.

Hereinafter, the present invention will be described in detail.

Fig. 8 is a schematic view for explaining a method of measuring the surface area of the present invention. Fig. The present invention relates to a method of measuring the surface area of a roughened copper surface, the method comprising: a first step of removing the natural copper oxide produced on the surface of the copper metal by electrostatic force; A second step of forming a monomolecular layer of a dissimilar metal and a third step of dissolving the monomolecular layer of the dissimilar metal on the electrostatic charge to calculate an anode electric charge used for dissolving the monomolecular layer of the dissimilar metal, And the surface area of the surface is obtained. In addition, when metal copper is left in an atmospheric environment, copper reacts directly with oxygen in the air to form a coating of copper oxide, which is referred to as a natural oxidation oxide in the present invention.

The surface area of the present invention can be measured in a 1 M sodium sulfate aqueous solution containing 0.5 x 10 &lt; ^-3 &gt; M of thallium sulfate.

The first step of the present invention is a step of performing electrostatic polarization to dissolve natural copper oxide easily generated on the surface of metal copper. The polarization potential is preferably -1.0V to -0.75V vs Ag / AgCl, more preferably -0.90V to -0.77V vs Ag / AgCl, and particularly preferably -0.85V to -0.78V vs Ag / AgCl . If it is polarized at a potential smaller than -1.0 V vs Ag / AgCl, the dissolution of the natural copper oxide may become insufficient, and if it is polarized at a potential larger than -0.75 Vvs Ag / AgCl, the dissolution of the natural copper oxide may become insufficient .

The time for electrostatic polarization may be arbitrary, but if it is performed for 5 seconds or more, natural copper oxide can be sufficiently dissolved. It is preferably 5 seconds to 20 seconds, and more preferably 5 seconds to 10 seconds.

The second step of the present invention is a step of forming a monomolecular layer of dissimilar metals on the surface of the metal copper in which the natural copper oxide is dissolved (removed) in the above step. The polarization potential is preferably -0.74 V to -0.61 V vs Ag / AgCl, more preferably -0.72 V to -0.61 V vs Ag / AgCl, and particularly preferably -0.70 V to -0.61 V vs Ag / AgCl . -0.74 V vs. Ag / AgCl, the dissociated metal ions may unintentionally precipitate in bulk rather than as a single molecule, and when polarized at a potential greater than -0.61 V vs Ag / AgCl, The monolayer may not be precipitated.

The precipitation time of the dissimilar metals is preferably 50 seconds to 300 seconds, more preferably 50 seconds to 200 seconds, and particularly preferably 100 seconds to 200 seconds. If the deposition time of the dissimilar metals is shorter than 50 seconds, there is a possibility that the monomolecular layer of the dissimilar metal is not formed on the entire surface of the surface of the metal copper. In addition, since it is precipitated as a single molecule, the anode electricity quantity remains unchanged even if it takes 300 seconds or more.

The third step of the present invention is a step of forming a monomolecular layer of a dissimilar metal and dissolving the dissimilar metal on the electrostatic charge in the above step. The dissolution potential is higher than the precipitation potential and is preferably -0.5V to 0.0V vs Ag / AgCl, more preferably -0.5V to -0.1V vs Ag / AgCl, -0.4V to -0.2V Is particularly preferable. -0.5 V vs. Ag / AgCl, the monomolecular layer of the dissimilar metal can not be sufficiently dissolved and the anode current may not flow. In addition, when polarized at a potential greater than 0.0V vs Ag / AgCl, there is a possibility that not only the anode current used for dissolving dissimilar metals but also the anode current used for dissolving copper can be measured.

The time for dissolving the monomolecular layer of the dissimilar metal is preferably 30 seconds to 60 seconds, particularly preferably 30 seconds to 45 seconds. If the time for dissolving the monomolecular layer of the dissimilar metal is shorter than 30 seconds, the monomolecular layer of the dissimilar metal may not be completely dissolved. Even if the time for dissolving the monomolecular layer of the dissimilar metal is longer than 60 seconds, the anode electricity quantity does not change.

Generally, ions of a metal having a small work function on a metal having a large work function are under-deposited. In the present invention, a metal having a work function smaller than copper is thallium. Therefore, in the present invention, thallium is particularly preferably used as the dissimilar metal.

In the present invention, the anode electricity amount consumed for dissolving the monomolecular layer of the dissimilar metal on the electrostatic charge is measured five times, and the coefficient of variation thereof is preferably 20% or less, more preferably 15% or less.

In the present invention, the anode electricity quantity can be calculated by the following equation (1).

&Quot; (3) &quot;

Q _a (mC / cm ² ): anode electric quantity

i (mA / cm ² ): Corrosion current density

t (s): time

Further, the obtained anode electricity quantity can be converted into a surface area factor f _SR according to the following equation (2).

&Quot; (4) &quot;

Q _a : the obtained anode electricity quantity

Q _TI : 112 μC cm ^-2

Example

The present invention will be described more specifically with reference to Examples. The present invention is not limited to the following examples.

Example  And In the comparative example  Used Etch conditioning agent

Etching Hardener: EMR5100 (registered trademark) or EMR2000 (registered trademark) manufactured by Mitsubishi Gas Chemical Co.,

Electrolyte

As the thallium ion source, thallium sulfate was dissolved in an aqueous solution of 1 M sodium sulfate at 0.5 x 10 &lt; ^-3 &gt; M.

Sulfuric acid thallium: a special grade reagent manufactured by Wako Pure Chemical Industries, Ltd.

Sodium sulphate: a special grade reagent manufactured by Wako Pure Chemical Industries,

How to measure

1. Measurement of static polarization

Electrode method, using an electrochemical measuring device (Hokuto Denko Co., Ltd., HZ-5000). (Etching depth: 150 nm, 200 nm, and 250 nm) was etched by an etching harmonizer at a predetermined etching amount, and platinum was used as a counter electrode. RAg) as a reference electrode was measured in an electrolytic solution in which 1 M sodium thiosulfate was dissolved at a concentration of 0.5 10 ^-3 M. The measurement was performed with a fixed electrode.

2. SEM observation of the surface

And observed under the conditions of an acceleration voltage of 5 kV and a magnification of 20000 times using a scanning electron microscope (SEM: Hitachi High Technologies, Inc., S3400).

3. SEM observation of section

The single-sided exposure of the sample was performed using ion milling and observed under the conditions of an acceleration voltage of 10 kV and a magnification of 3000 times using a scanning electron microscope (SEM: Hitachi High Technologies, Inc., S3400).

Example 1

An electroless copper (metal copper) film was etched by using EMR5100 (registered trademark) manufactured by Mitsubishi Gas Chemical Co., Ltd. as the etching harmony agent so that the depth from the surface was 150 nm, 200 nm, and 250 nm. SEM observation of the surface and the cross section was carried out in order to confirm the harmony state. 3 is an SEM photograph of an electroless copper surface to which no etching treatment is applied. 4 is an SEM photograph of the copper surface when the etching amount is 150 nm, FIG. 5 is an SEM photograph of the copper surface when the etching amount is 200 nm, and FIG. 6 is an SEM photograph of the copper surface when the etching amount is 250 nm. 7 is an SEM photograph of the cross section of the sample.

As the thallium ion source, a solution in which thallium sulfate was dissolved in an aqueous solution of 1 M sodium sulfate at 0.5 × 10 ^-3 M was used.

Electroless copper was immersed in the electrolytic solution containing thallium and the working electrode of the electroless copper (metal copper) was changed to -0.80 to dissolve the natural copper oxide easily generated on the surface of the electroless copper (metal copper) V &lt; / RTI &gt; vs Ag / AgCl for 5 seconds on the static charge (first step). Subsequently, in order to precipitate (form) thallium into a monolayer, polarization was carried out for 200 seconds on the positive potential of -0.69 V vs Ag / AgCl (second step). Subsequently, in order to dissolve the precipitated thallium monolayer, it was polarized for 30 seconds on a static charge of -0.30 V vs. Ag / AgCl (third step).

The anode current used to dissolve the thallium monolayer was integrated over time to obtain the anode charge Q _a .

The anode electricity quantity was calculated by the following equation (1).

&Quot; (5) &quot;

Q _a (mC / cm ² ): anode electric quantity

i (mA / cm ² ): Corrosion current density

t (s): time

The obtained anode electricity quantity was converted into f _{SR, which} is a surface area factor according to the following equation (2).

&Quot; (6) &quot;

Q _a : the obtained anode electricity quantity

Q _TI : 112 μC cm ^-2

112 占 폚 cm ^-2 is the theoretical value of the anode electricity amount required to form the monomolecular layer on the dissimilar metal having 1 cm ² of thallium.

This operation was performed five times, and an average value, a standard deviation and a variation coefficient of the anode electricity amount were obtained. The results are summarized in Table 1.

The anode electricity quantity and f _SR are as follows.

The average Q _a0 before etching harmonization is 0.225 mC / cm &lt; ² &gt;

Standard deviation: 0.024 mC / cm ²

          Coefficient of variation: 11%

Mean f _SR0 = 2.01

          Standard deviation: 0.21

          Coefficient of variation: 11%

The average Q _a150 after the 150 nm etching harmonization = 0.330 mC / cm &lt; ² &gt;

Standard deviation: 0.028 mC / cm ²

          Coefficient of variation: 9%

Mean f _SR150 = 2.95

          Standard deviation: 0.25

          Coefficient of variation: 9%

The average Q _a200 after the 200 nm etching harmonization = 0.532 mC / cm ²

Standard deviation: 0.061 mC / cm ²

          Coefficient of variation: 11%

Mean f _SR200 = 4.75

          Standard deviation: 0.55

          Coefficient of variation: 11%

Average Q _a250 = 0.780mC / cm ² after etching conditioner 250nm

Standard deviation: 0.073 mC / cm ²

          Coefficient of variation: 9%

Mean f _SR250 = 6.97

          Standard deviation: 0.65

          Coefficient of variation: 9%

As a result of measuring the anode electricity quantity by the electrostatic potential method of the present invention, it can be seen that the surface area expressed by f _SR is increased depending on the etching amount. In addition, the coefficient of variation was not different depending on the amount of etching before and after the etching harmony, and was about 10%.

An HSD test of Tukey-Kramer was performed to confirm whether there is a significant difference between the anode electric quantity and f _SR before etching and between respective etching amounts. In this case, the rejection limit for the 5 percent Tukey test on both sides would be 2.861. It can be said that the p value in Table 2 below is 0.05 or less. The results of the assay show that there is a significant difference between all groups after etch conditioning, after 150 nm etching coarsulation, after 200 nm etching coarsening, and after 250 nm etching coarsulation (Table 2). This is evidence that the coefficient of variation is small and reproducible.

Comparative Example 1

An electroless copper (metal copper) film was etched by using EMR5100 (registered trademark) manufactured by Mitsubishi Gas Chemical Co., Ltd. as the etching harmony agent so that the depth from the surface was 150 nm, 200 nm, and 250 nm. SEM observation of the surface and the cross section was carried out in order to confirm the coarsened state as in the first embodiment.

As the thallium ion source, a solution in which thallium sulfate was dissolved in an aqueous solution of 1 M sodium sulfate at 0.5 × 10 ^-3 M was used.

Electroless copper is immersed in an electrolytic solution containing thallium and a working electrode of electroless copper (metal copper) is set to -0.80 V vs &lt; RTI ID = 0.0 &gt; Ag / AgCl for 5 seconds. Subsequently, in order to precipitate thallium as a monolayer, it was polished for 200 seconds on a static charge of -0.69 V vs. Ag / AgCl. Subsequently, in order to dissolve the precipitated thallium monolayer, it was swept to -0.70 V to -0.30 V vs. Ag / AgCl to 50 mV / sec (not a positive potential).

An anode current having a potential in the range of -0.59 V to -0.30 V vs Ag / AgCl was integrated with respect to time to obtain an anode electricity quantity.

The obtained anode electricity quantity was divided by the theoretical anode electricity quantity required when thallium was produced as a single molecule on 1 cm ² of copper, and was defined as f _SR . This operation was performed five times, and an average value and standard deviation of the anode electricity quantity were determined. The results are summarized in Table 3.

The anode electricity quantity and f _SR are as follows.

The average Q _a0 before etching harmonization is 0.227 mC / cm &lt; ² &gt;

Standard deviation: 0.097 mC / cm ²

         Coefficient of variation: 43%

Mean f _SR0 = 2.02

         Standard deviation: 0.87

         Coefficient of variation: 43%

Average Q _a150 after 150 nm etching _coarsening = 0.300 mC / cm &lt; ² &gt;

Standard deviation: 0.108 mC / cm ²

         Coefficient of variation: 36%

Mean f _SR150 = 2.68

         Standard deviation: 0.97

         Coefficient of variation: 36%

The average Q _a200 after the 200 nm etching harmonization = 0.658 mC / cm ²

Standard deviation: 0.179 mC / cm ²

         Coefficient of variation: 27%

Mean f _SR200 = 5.87

         Standard deviation: 1.60

         Coefficient of variation: 27%

Average Q _a250 after etching at 250 nm = 0.889 mC / cm &lt; ² &gt;

Standard deviation: 0.227 mC / cm ²

         Coefficient of variation: 25%

Mean f _SR250 = 7.94

         Standard deviation: 2.03

         Coefficient of variation: 25%

When the anode electric quantity is measured by the cyclic voltammetry method according to the method of Non-Patent Document 1, it can be seen that the surface area expressed by f _SR increases with the increase of the etching amount. However, The etching amount was 27% when the etching amount was 200 nm, and the etching amount was 25% when the etching amount was 250 nm, and a large difference was found in the value.

An HSD test of Tukey-Kramer was performed to confirm whether there is a significant difference between the anode electric quantity and f _SR before etching and between respective etching amounts. In this case, the rejection limit for the 5 percent Tukey test on both sides would be 2.861. If the p value in Table 4 is more than 0.05, it is not meaningful. From the results of the test, there is no significant difference between the group before etch conditioning and the group after 150 nm etching harmonization, and there is no significant difference between the group after 200 nm etch-blend and the group after 250 nm etch-blend (Table 4). This is because the value of the coefficient of variation is large and is different in all the groups and the reproducibility is poor.

Example 2

Etching of the electrolytic copper (metal copper) film was carried out using EMR2000 (registered trademark) manufactured by Mitsubishi Gas Chemical Company as the etching harmony agent so that the depth from the surface was 200 nm. As the thallium ion source, a solution in which thallium sulfate was dissolved in an aqueous solution of 1 M sodium sulfate at 0.5 × 10 ^-3 M was used.

Electroless copper was immersed in an electrolytic solution containing thallium and the working electrode of electrolytic copper (metal copper) was immersed in an electrolytic solution of -0.8 V vs Ag / The AgCl was polarized for 5 seconds on the static charge (first step). Subsequently, in order to precipitate (form) thallium into a monolayer, polarization was carried out for 200 seconds on the electrostatic potential of -0.69 V vs Ag / AgCl (second step). Subsequently, in order to dissolve the precipitated thallium monolayer, it was polarized for 30 seconds on a static charge of -0.30 V vs. Ag / AgCl (third step).

As in Example 1, the anode current used for dissolving the thallium monolayer was integrated with respect to time, and the anode electricity quantity Q _a was determined.

This operation was performed five times, and an average value, a standard deviation and a variation coefficient of the anode electricity amount were obtained. The results are summarized in Table 5.

The anode electricity quantity and f _SR are as follows.

The average Q _a0 before etching harmonization is 0.199 mC / cm &lt; ² &gt;

Standard deviation: 0.019 mC / cm ²

           Coefficient of variation: 9.6%

Mean f _SR0 = 1.77

           Standard deviation: 0.17

           Coefficient of variation: 10%

The average Q _a200 after the 200 nm etching harmonization = 0.317 mC / cm ²

Standard deviation: 0.034 mC / cm ²

           Coefficient of variation: 11%

Mean f _SR200 = 2.83

           Standard deviation: 0.31

           Coefficient of variation: 11%

As a result of measuring the anode electricity quantity by the electrostatic potential method of the present invention, it can be seen that the surface area expressed by f _SR is increased depending on the etching amount. In addition, the coefficient of variation was not different depending on the amount of etching before and after the etching harmony, and was about 10%.

Example 3

Etching of the electrolytic copper (metal copper) film was carried out using EMR2000 (registered trademark) manufactured by Mitsubishi Gas Chemical Company as the etching harmony agent so that the depth from the surface was 200 nm. As the thallium ion source, a solution in which thallium sulfate was dissolved in an aqueous solution of 1 M sodium sulfate at 0.5 × 10 ^-3 M was used.

The procedure of Example 2 was repeated except that the electrostatic potential polarization for dissolving the natural copper oxide easily generated on the surface of the metal copper in the first step of Example 2 was performed at a potential of -1.5 V vs Ag / And operated under the same conditions. The average of the obtained anode electricity amounts was 0.242 mC / cm &lt; ^{2 &} gt ;. It is considered that the dissolution of natural copper oxide becomes insufficient and the formation of a monolayer of thallium on the entire surface of copper is insufficient.

Example 4

Etching of the electrolytic copper (metal copper) film was carried out using EMR2000 (registered trademark) manufactured by Mitsubishi Gas Chemical Company as the etching harmony agent so that the depth from the surface was 200 nm. As the thallium ion source, a solution in which thallium sulfate was dissolved in an aqueous solution of 1 M sodium sulfate at 0.5 × 10 ^-3 M was used.

Example 2 was repeated except that the electrostatic potential polarization for dissolving the natural copper oxide easily generated on the surface of the metal copper in the first step of Example 2 was performed at a potential of -0.70 V vs Ag / AgCl. And operated under the same conditions. The average of the obtained anode electricity amounts was 0.252 mC / cm &lt; ^{2 &} gt ;. It is considered that the dissolution of natural copper oxide becomes insufficient and the formation of a monolayer of thallium on the entire surface of copper is insufficient.

Example 5

Etching of the electrolytic copper (metal copper) film was carried out using EMR2000 (registered trademark) manufactured by Mitsubishi Gas Chemical Company as the etching harmony agent so that the depth from the surface was 200 nm. As the thallium ion source, a solution in which thallium sulfate was dissolved in an aqueous solution of 1 M sodium sulfate at 0.5 × 10 ^-3 M was used.

Except that the electrostatic potential polarization was performed at a potential of -0.8 V vs Ag / AgCl in order to form a thallium monomolecular layer on the surface of the metal copper from which natural copper oxide had been removed in the second step of Example 2, 2 under the same conditions. The average of the obtained anode electricity amounts was 2.339 mC / cm &lt; ^{2 &} gt ;. It is thought that a part of thallium ions was unintentionally precipitated in a bulk rather than a monolayer.

Example 6

Etching of the electrolytic copper (metal copper) film was carried out using EMR2000 (registered trademark) manufactured by Mitsubishi Gas Chemical Company as the etching harmony agent so that the depth from the surface was 200 nm. As the thallium ion source, a solution in which thallium sulfate was dissolved in an aqueous solution of 1 M sodium sulfate at 0.5 × 10 ^-3 M was used.

Except that the electrostatic potential polarization was performed at a potential of -0.6 V vs. Ag / AgCl in order to form a monolayer of thallium on the surface of the metal copper from which natural copper oxide had been removed in the second step of Example 2, 2 under the same conditions. The average of the obtained anode electricity amounts was 0.167 mC / cm &lt; ^{2 &} gt ;. It is considered that the formation of a monolayer of thallium on the entire surface of copper is insufficient.

Example 7

Etching of the electrolytic copper (metal copper) film was carried out using EMR2000 (registered trademark) manufactured by Mitsubishi Gas Chemical Company as the etching harmony agent so that the depth from the surface was 200 nm. As the thallium ion source, a solution in which thallium sulfate was dissolved in an aqueous solution of 1 M sodium sulfate at 0.5 × 10 ^-3 M was used.

The operation was carried out under the same conditions as in Example 2 except that the precipitation time for forming a thallium monomolecular layer on the surface of the metal copper from which natural copper oxide was removed in the second step of Example 2 was 30 seconds. The average of the obtained anode electricity amounts was 0.176 mC / cm &lt; ^{2 &} gt ;. It is considered that the formation of a monolayer of thallium on the entire surface of copper is insufficient.

Example 8

Etching of the electrolytic copper (metal copper) film was carried out using EMR2000 (registered trademark) manufactured by Mitsubishi Gas Chemical Company as the etching harmony agent so that the depth from the surface was 200 nm. As the thallium ion source, a solution in which thallium sulfate was dissolved in an aqueous solution of 1 M sodium sulfate at 0.5 × 10 ^-3 M was used.

The same operation as in Example 2 was carried out except that the electrostatic potential polarization for dissolving the thallium monomolecular layer in the third step of Example 2 was set at a potential of 0.1 V vs Ag / AgCl. The average of the obtained anode electricity amounts was 57.6 mC / cm &lt; ^{2 &} gt ;. It is considered that not only the monolayer of thallium but also copper dissolves.

When the surface area is measured by the surface area measuring method of the present invention, the surface area can be measured to a high degree in a simple and reproducible manner as described above.

Industrial availability

The surface area measuring method of the present invention can easily and highly accurately measure the surface area of a product made of copper or a copper alloy and has high industrial applicability.

Claims (9)

A method of measuring the surface area of a coherent copper surface,
A first step of removing natural copper oxide generated on the surface of the metal copper on the electrostatic charge;
A second step of forming a monomolecular layer of dissimilar metals on the electrostatic charge on the surface of the copper oxide from which the natural copper oxide has been removed,
And a third step of dissolving the monomolecular layer of the dissimilar metal on the electrostatic charge,
Wherein the surface area of the coarsened copper surface is obtained by calculating an anode electricity amount used for dissolving the monomolecular layer of the dissimilar metal.
The method according to claim 1,
Wherein the electrostatic potential in the first step of removing the natural copper oxide is in the range of -1.0 V to -0.75 V vs Ag / AgCl.
3. The method according to claim 1 or 2,
Wherein the dissimilar metal is thallium.
4. The method according to any one of claims 1 to 3,
Wherein the electrostatic potential in the second step of forming the monomolecular layer of the dissimilar metal is in the range of -0.74 V to -0.61 V vs Ag / AgCl.
5. The method according to any one of claims 1 to 4,
And the treatment time in the second step is 50 to 300 seconds.
6. The method according to any one of claims 1 to 5,
Wherein the electrostatic potential in the third step of dissolving the monolayer is in the range of -0.50 V to 0.0 V vs Ag / AgCl.
7. The method according to any one of claims 1 to 6,
Wherein the anode electricity amount consumed for dissolving the monolayer on the electrostatic charge is measured five times, and the coefficient of variation thereof is 20% or less.
8. The method according to any one of claims 1 to 7,
Wherein the anode electricity quantity is calculated by the following equation (1).
[Equation 1]

Q _a (mC / cm ² ): anode electric quantity
i (mA / cm ² ): Corrosion current density
t (s): time
9. The method of claim 8,
Wherein the obtained anode electricity quantity is converted to f _{SR which} is a surface area factor according to the following equation (2).
&Quot; (2) &quot;

Q _a : the obtained anode electricity quantity
Q _TI : 112 μC cm ^-2

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