JP2003231995A - Phosphor-containing copper anode for copper electroplating, copper electroplating method using phosphor-containing copper anode, and semiconductor wafer plated by using them with few adhering particles - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a phosphor-containing copper anode for copper electroplating, which inhibits generation of the particles such as sludge formed in an anode side in a plating solution, and prevents adhesion of particles to a semiconductor wafer, in a copper electroplating process, and to provide a copper electroplating method using the phosphor-containing copper anode, a semiconductor wafer plated by using them with few adhering particles, and a method for manufacturing the phosphor-containing copper anode for copper electroplating. <P>SOLUTION: The phosphor-containing copper anode for electroplating copper comprises using phosphor-containing copper, and having a micro diamond pyramid hardness of 40 or higher. The copper electroplating method is characterized by using the phosphor-containing copper anode. The semiconductor wafer with few adhering particles is plated by using them. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to electrolytic copper plating that suppresses the generation of particles such as sludge generated on the anode side in a plating bath during electrolytic copper plating, and particularly prevents the adhesion of particles to semiconductor wafers. Phosphorus-containing copper anode for use, electrolytic copper plating method using the phosphorus-containing copper anode,
The present invention relates to a semiconductor wafer plated with these materials with little particle adhesion.

[0002]

2. Description of the Related Art Generally, electrolytic copper plating is used for forming copper wiring in a PWB (printed wiring board) or the like, but recently it has come to be used for forming copper wiring of semiconductors. Copper electroplating has a long history and many technical accumulations have made it to the present day. However, when this copper electroplating is used for forming copper wiring of semiconductors,
There was a new inconvenience that was not a problem with PWB.

Usually, phosphorous copper is used as an anode when electrolytic copper plating is performed. This is because when an insoluble anode made of platinum, titanium, iridium oxide, etc. is used, the additives in the plating solution are decomposed under the influence of anodic oxidation, causing plating failure. When copper or oxygen-free copper is used, a large amount of particles such as sludge made of metallic copper or copper oxide resulting from the disproportionation reaction of monovalent copper during melting will contaminate the object to be plated. Is. On the other hand, when a phosphorus-containing copper anode is used, a black film made of copper phosphide, copper chloride, etc. is formed on the anode surface by electrolysis, and metal black or copper oxide of monovalent copper is disproportionated. Generation can be suppressed and generation of particles can be suppressed.

However, even if the phosphorus-containing copper is used as the anode as described above, the generation of particles is completely suppressed because the black film is dropped off and metallic copper or copper oxide is generated in the thin portion of the black film. It's not done. Therefore, the filter cloth usually called an anode bag is wrapped around the anode to prevent particles from reaching the plating solution. However, when this method is applied to the plating of a semiconductor wafer, the above-mentioned PWB
Fine particles, which did not pose a problem in the formation of wiring to the semiconductor, reached the semiconductor wafer and adhered to the semiconductor, causing a problem of plating failure.

[0005]

DISCLOSURE OF THE INVENTION The present invention suppresses the generation of particles such as sludge generated on the anode side in a plating solution during electrolytic copper plating, and particularly prevents the particles from adhering to semiconductor wafers. Accordingly, it is an object of the present invention to provide a phosphorus-containing copper anode for electrolytic copper plating, an electrolytic copper plating method using the phosphorus-containing copper anode, and a semiconductor wafer plated with these with less particle adhesion.

[0006]

In order to solve the above-mentioned problems, the inventors of the present invention have conducted earnest research, and as a result, improved the material of the electrode and suppressed the generation of particles at the anode, thereby improving the adhesion of particles. We have obtained the knowledge that semiconductor wafers and the like with few defects can be stably manufactured. The present invention is based on this finding. An anode for performing electrolytic copper plating, wherein phosphorus-containing copper is used as the anode, and the phosphorus-containing copper anode has a micro Vickers hardness of 40 or more, and a phosphorus-containing copper anode for electrolytic copper plating and the phosphorus-containing copper anode. 1. Electrolytic copper plating method using a copper anode, and a semiconductor wafer plated with these with less particle adhesion 2. Micro Vickers hardness of phosphorus-containing copper anode is 70
2. The phosphorus-containing copper anode for electrolytic copper plating according to the above 1, the electrolytic copper-plating method using the phosphorus-containing copper anode, and the semiconductor wafer plated by using the same and having less particle adhesion. An anode for performing electrolytic copper plating, wherein phosphorus-containing copper is used as the anode, and the phosphorus-containing copper anode has a non-recrystallized structure or a partially recrystallized structure. And a copper electroplating method using the phosphorus-containing copper anode, and a semiconductor wafer plated with these with less particle adhesion. The electrolytic copper according to the above 1 or 2, wherein the electrolytic copper plating is performed by using phosphorous-containing copper as the anode, and the phosphorous-containing copper anode has an unrecrystallized structure or a partially recrystallized structure. Provided are a phosphorous-containing copper anode for plating, an electrolytic copper plating method using the phosphorous-containing copper anode, and a semiconductor wafer plated using the same with less particle adhesion.

The present invention also includes: Phosphorus content of phosphorus-containing copper anode is 0.1 wtppm
The phosphorus-containing copper anode for electrolytic copper plating described in each of 1 to 4 above, the electrolytic copper-plating method using the phosphorus-containing copper anode, and less particles deposited by using these Semiconductor wafer 6. Phosphorus-containing copper anode has a phosphorus content of 1 to 1000 wt.
6. The phosphorus-containing copper anode for electrolytic copper plating according to 5 above, the electrolytic copper-plating method using the phosphorus-containing copper anode, and the semiconductor wafer plated with these with little particle adhesion. Purity is 99 to 99.999 excluding phosphorus and gas components
It is 999 wt%, and the phosphorus-containing copper anode for electrolytic copper plating according to each of the above 1 to 6, an electrolytic copper plating method using the phosphorus-containing copper anode, and adhesion of particles plated using these Few semiconductor wafers 8. Purity is 99.9 to 99.9 excluding phosphorus and gas components
The phosphorus-containing copper anode for electrolytic copper plating according to the above 7, the electrolytic copper-plating method using the phosphorus-containing copper anode, and a semiconductor wafer plated with these particles with less particle adhesion are provided. To do.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example of an apparatus used in a method for electro copper plating of semiconductor wafers. This copper plating apparatus includes a plating tank 1 containing a copper sulfate plating solution 2. An anode 4, which is a phosphorous-containing copper anode, is used as the anode, and the cathode is, for example, a semiconductor wafer for plating.

As described above, when copper-containing copper is used as the anode during electroplating, a black film containing copper phosphide and copper chloride as main components is formed on the surface, and the black film is formed when the anode is dissolved. , Has a function of suppressing the generation of particles such as sludge made of metallic copper, copper oxide or the like due to the disproportionation reaction of monovalent copper. However, the black film formation rate is strongly influenced by the current density of the anode, the crystal grain size, the phosphorus content rate, etc., and the higher the current density, the smaller the crystal grain size, and the higher the phosphorus content rate, the faster. As a result, it was found that the black film tends to be thick. Conversely, the lower the current density, the larger the crystal grain size, and the lower the phosphorus content, the slower the production rate, and as a result, the black film becomes thinner. As described above, the black film has a function of suppressing the generation of particles such as metallic copper and copper oxide, but when the black film is too thick, it peels and falls off, which itself causes particles. A big problem arises.
On the other hand, if it is too thin, there is a problem in that the effect of suppressing the production of metallic copper, copper oxide, etc. is reduced.

Therefore, in order to suppress the generation of particles from the anode, it is extremely important to optimize each of the current density, the crystal grain size, and the phosphorus content to form a stable black film having an appropriate thickness. I know there is. Therefore, the present inventors have proposed to adjust the crystal grain size of the phosphorus-containing copper anode, the phosphorus content of the phosphorus-containing copper anode, and the current density during melting (Japanese Patent Application No. 2001-323).
265). This allowed us to achieve the intended purpose. However, since these are achieved under the condition of optimization as described above, strict adjustment is necessary. From this, in the present invention,
The above points are further improved, and the generation of sludge and the like is significantly reduced without requiring such strict conditions.

In the present invention, the phosphorus-containing copper anode has a micro Vickers hardness of 40 or more,
As a result, when electrolytic copper plating is performed, it is possible to suppress the generation of particles such as sludge generated on the anode side in the plating solution, and particularly to effectively prevent the particles from adhering to the semiconductor wafer. In particular, the phosphorus-containing copper anode preferably has a micro Vickers hardness of 70 or more. This hardness can be obtained by melting and casting phosphorus-containing copper, and then performing processing such as rolling or forging. The phosphorus-containing copper anode thus obtained usually has a non-recrystallized structure. After the processing, strain relief annealing can be performed to remove the strain inside the anode. Further, it is also possible to perform annealing at a relatively low temperature after processing. When annealing is performed, it may partially have a recrystallized structure. Even if the material has a recrystallized structure in a part as described above, as long as the hardness is not extremely lowered, only a few particles are recognized and it is not a substantial problem. Therefore, the present invention includes an anode having such a partially recrystallized structure.

The phosphorus content of the phosphorus-containing copper anode does not need to be specially adjusted, but is preferably 0.1 wtppm or more, and preferably 1 to 1000 wtppm. Further, the purity of the phosphorus-containing copper anode is 99 to 100 except for the main components (that is, Cu and P) and the gas components.
It is desirable that it is 99.999999 wt%. Preferably, the purity is 99.9-excluding the main component and the gas component.
It is set to 99.9999 wt%. By performing electrolytic copper plating using the phosphorus-containing copper anode of the present invention described above, the generation of sludge and the like can be significantly reduced, particles reach the semiconductor wafer, and they adhere to the semiconductor wafer. As a result, there is no possibility of causing plating failure. And, the crystal grain size of the phosphorus-containing copper anode,
It is characterized in that it is not necessary to strictly adjust the phosphorus content of the phosphorus-containing copper anode, the current density during melting, and the like. Electrolytic copper plating using the phosphorus-containing copper anode of the present invention is particularly useful for plating on semiconductor wafers, but also in copper plating in other fields where thinning is progressing, it reduces the plating defect rate due to particles. It is effective as a method.

As described above, the phosphorus-containing copper anode of the present invention has an effect of suppressing generation of a large amount of particles such as sludge made of metallic copper or copper oxide and remarkably reducing the contamination of the object to be plated. The decomposition of the additive in the plating solution and the defective plating caused by the use of the insoluble anode do not occur. As a plating solution, copper sulfate: 10 to 70 g / L (Cu), sulfuric acid: 10 to 300 g / L, chloride ion 20 to 100 mg
/ L, additive: (Nichiko Metal Plating CC-1
220: 1 mL / L, etc.) can be used in an appropriate amount.
Further, the purity of copper sulfate is preferably 99.9% or more. In addition, plating bath temperature 15 to 35 ° C, cathode current density 0.5 to 5.5 A / dm ² , anode current density 0.5 to
It is desirable that the plating time be 5.5 A / dm ² and the plating time be 0.5 to 100 hr. The preferred examples of the plating conditions are shown above, but the plating conditions are not necessarily limited to the above conditions.

[0014]

Examples and Comparative Examples Next, examples of the present invention will be described. It should be noted that the present embodiment is merely an example, and the present invention is not limited to this example. That is, it includes all aspects or modifications other than the examples within the scope of the technical idea of the present invention.

(Examples 1 to 4) As shown in Table 1, phosphorus-containing copper having a phosphorus content of 100 to 500 wtppm was used as the anode, and a semiconductor wafer was used as the cathode. In Example 1, a phosphorus-containing copper ingot containing 500 wtppm of melt-cast phosphorus was rolled by 80%, and is a phosphorus-containing copper anode having a micro-Vickers hardness of 110 and an unrecrystallized structure. Example 2 is a phosphorus-containing copper ingot containing 100 wtppm of melt-cast phosphorus.
% Rolled, a phosphorus-containing copper anode having a micro-Vickers hardness of 105 and an unrecrystallized structure. In Example 3, a phosphorus-containing copper ingot containing 500 wtppm of melt-cast phosphorus was rolled by 80% and further subjected to 150 °.
A phosphorus-containing copper anode having a non-recrystallized structure having a micro Vickers hardness of 80, which was annealed for C2 hours for strain relief.

In Example 4, 500 w of melt cast phosphorus was used.
80% rolling of phosphorus-containing copper ingot containing tppm,
Further, it was annealed at 300 ° C. for 1 hour, and was a phosphorus-containing copper anode having a micro-Vickers hardness of 70 and a partially recrystallized structure. As a plating solution, copper sulfate: 20 g /
L (Cu), sulfuric acid: 200 g / L, chloride ion 60 mg
/ L, additive [brightener, surfactant] (Nichiko Metal Plating Co .: trade name CC-1220): 1 mL / L
It was used. The purity of copper sulfate in the plating solution is 99.99%
Met. The plating conditions are a plating bath temperature of 30 ° C., a cathode current density of 2.0 to 4.0 A / dm ² , and an anode current density of 2.0.
˜4.0 A / dm ² , plating time 24-48 hr. The above conditions are shown in Table 1.

After plating, the amount of particles generated and the appearance of plating were observed. The results are also shown in Table 1. It should be noted that the amount of particles was set to 0.
After filtering with a 2 μm filter, the weight of the filtered product was measured. Regarding the appearance of plating, after the above electrolysis, the object to be plated was exchanged, plating was performed for 1 minute, and the presence or absence of burns, cloudiness, blisters, abnormal deposition, adhesion of foreign matter, etc. was visually observed. As a result, in Examples 1 to 3, the amount of particles was 1 mg.
Was less than. Only Example 4 having a slightly low hardness and having a partially recrystallized structure showed a particle amount of 26 mg, which was not a particularly problematic amount. Moreover, the plating appearance and embedding property were both good.

[0018]

[Table 1]

Comparative Examples 1 to 3 As shown in Table 2, phosphorus-containing copper having a phosphorus content of 100 to 500 wtppm was used as the anode, and a semiconductor wafer was used as the cathode. Comparative Example 1 is a phosphorus-containing copper anode having an as-cast structure (recrystallization structure) containing 500 wtppm of phosphorus,
It has a micro Vickers hardness of 35. Comparative Example 2 is a phosphorus-containing copper anode having an as-cast structure (recrystallized structure) containing phosphorus in an amount of 500 wtppm and having a micro Vickers hardness of 32. Comparative Example 3 uses 100% phosphorus.
As-cast structure containing wtppm (recrystallized structure)
Having a micro Vickers hardness of 38. As in the example, as a plating solution, copper sulfate: 20 g / L (Cu), sulfuric acid: 200 g / L, chloride ion 60 mg / L, additive [brightening agent, surfactant] (manufactured by Nikko Metal Plating Co., Ltd .: product Name CC-122
0): 1 mL / L was used. The purity of copper sulfate in the plating solution was 99.99%. Similarly, the plating conditions are a plating bath temperature of 30 ° C. and a cathode current density of 2.0 to 4.0 A / dm.
² , the anode current density was 2.0 to 4.0 A / dm ² , and the plating time was 24 to 48 hr. The above conditions are shown in Table 2.

[0020]

[Table 2]

After plating, the amount of particles generated and the appearance of plating were observed. The results are also shown in Table 2. The amount of particles and the appearance of plating were measured and observed under the same conditions as in the above-mentioned examples. As a result of the above, Comparative Example 1
3 to 3, the amount of particles is 1711
It increased significantly to 4395 mg, and the appearance of plating was poor.

[0022]

INDUSTRIAL APPLICABILITY The present invention can suppress the generation of particles due to sludge or the like generated on the anode side in the plating solution during electrolytic copper plating, and can significantly reduce the adhesion of particles to semiconductor wafers. It has an excellent effect that it can be achieved without requiring strict adjustment such as optimizing the crystal grain size, phosphorus content, current density at the time of melting, etc. of the phosphorous copper anode.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of an apparatus used in a method for electroplating copper on a semiconductor wafer according to the present invention.

[Explanation of symbols]

1 plating tank 2 Copper sulfate plating solution 3 Semiconductor wafer 4 Phosphorus-containing copper anode

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[Procedure amendment]

[Submission date] March 27, 2002 (2002.3.2)
7)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Correction content]

As described above, the phosphorus-containing copper anode of the present invention has an effect of suppressing generation of a large amount of particles such as sludge made of metallic copper or copper oxide and remarkably reducing the contamination of the object to be plated. The decomposition of the additive in the plating solution and the defective plating caused by the use of the insoluble anode do not occur. As a plating solution, copper sulfate: 10 to 70 g / L (Cu), sulfuric acid: 10 to 300 g / L, chloride ion 20 to 100 mg
/ L, additive: (Nichiko Metal Plating CC-1
220: 1 mL / L, etc.) can be used in an appropriate amount.
Further, the purity of copper sulfate is preferably 99.9% or more. In addition, plating bath temperature 15 to 35 ° C, cathode current density 0.5 to 5.5 A / dm ² , anode current density 0.5 to
It is desirable to set it to 5.5 A / dm ² . The preferred examples of the plating conditions are shown above, but the plating conditions are not necessarily limited to the above conditions.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yukihiko Tobita             4 shares, 187 Usba, Hwagawa-cho, Kitaibaraki, Ibaraki             Ceremony Company Nikko Materials Isohara Factory (72) Inventor Chie Miyata             4 shares, 187 Usba, Hwagawa-cho, Kitaibaraki, Ibaraki             Ceremony Company Nikko Materials Isohara Factory F-term (reference) 4K024 AA09 AB01 BB12                 4M104 BB04 DD52 HH20

Claims (8)

[Claims] 1. An anode for electrolytic copper plating, comprising:
A phosphorus-containing copper is used as an anode, and the phosphorus-containing copper anode has a micro Vickers hardness of 40 or more, and a phosphorus-containing copper anode for electrolytic copper plating, and an electrolytic copper-plating method using the phosphorus-containing copper anode, and A semiconductor wafer plated with these materials with little particle adhesion. 2. The phosphorus-containing copper anode for electrolytic copper plating according to claim 1, wherein the phosphorus-containing copper anode has a micro Vickers hardness of 70 or more, and an electrolytic copper-plating method using the phosphorus-containing copper anode. A semiconductor wafer plated with these materials with little particle adhesion. 3. An anode for electrolytic copper plating, comprising:
Phosphorus-containing copper is used as an anode, and the phosphorous-containing copper anode has a non-recrystallized structure or a partially recrystallized structure. Copper plating methods and semiconductor wafers plated using these with less particle adhesion. 4. An anode for electrolytic copper plating, comprising:
3. A phosphorus-containing copper anode for electrolytic copper plating according to claim 1 or 2, wherein phosphorus-containing copper anode is used as the anode, and the phosphorus-containing copper anode has a non-recrystallized structure or a partially recrystallized structure. An electrolytic copper plating method using a phosphorous copper anode, and a semiconductor wafer plated with the same with less particle adhesion. 5. The phosphorus content of the phosphorus-containing copper anode is 0.1.
It is more than wtppm, The phosphorus-containing copper anode for electrolytic copper plating in each of Claims 1-4, the electrolytic copper plating method using this phosphorus-containing copper anode, and the particle | grain adhesion plated using these. Low semiconductor wafer. 6. The phosphorus content of the phosphorus-containing copper anode is 1 to 1.
The phosphorus-containing copper anode for electrolytic copper plating according to claim 5, the electrolytic copper-plating method using the phosphorus-containing copper anode, and the semiconductor wafer plated with these particles with less particle adhesion. 7. A purity of 99 to 9 excluding phosphorus and gas components.
9. 999999% by weight, phosphorous copper-containing anode for electrolytic copper plating according to each of claims 1 to 6, electrolytic copper-plating method using the phosphorous-containing copper anode, and plating using these A semiconductor wafer with few particles attached. 8. A purity of 99.9 excluding phosphorus and gas components.
9 to 99.9999% by weight, the phosphorus-containing copper anode for electrolytic copper plating according to claim 7, the electrolytic copper-plating method using the phosphorus-containing copper anode, and less adhesion of particles plated using these Semiconductor wafer.