JP4750486B2 - Electrolytic copper plating additive, electrolytic copper plating bath containing the additive, and electrolytic copper plating method using the plating bath - Google Patents

Description

  The present invention relates to an electrolytic copper plating additive containing this additive as an essential active ingredient, and an electrolytic copper plating method using this copper plating bath.

  Conventionally, copper or copper is buried in the grooves and holes by electrolytic copper plating, such as the damascene method in the manufacture of highly integrated electronic circuits. When the growth of plating was accelerated, voids were generated inside the grooves and holes, and satisfactory copper plating could not be performed.

In order to solve this problem, for example, Patent Document 1 discloses: a) a metal ion source; b) an electrolyte containing two or more acids; and c) an electrolytic plating bath optionally containing one or more additives (claim 1). The electroplating bath according to claim 1, wherein the two or more acids are selected from organic acids, inorganic acids or mixtures thereof (claim 2); the organic acids are alkylsulfonic acid, arylsulfonic acid, carboxylic acid or halogenated The electroplating bath according to claim 2 selected from hydroacids (claim 3); the inorganic acid selected from sulfuric acid, phosphoric acid, nitric acid, hydrohalic acid, sulfamic acid or fluoroboric acid. The electroplating bath (Claim 4); the electroplating bath according to Claim 1 (Claim 5) wherein two or more acids are present in an amount of about 1 to about 350 g / L; the metal ion source is a copper ion source. The electroplating bath according to claim 1. 6. The electrolytic plating bath of claim 6 wherein the copper ion source is selected from copper sulfate, copper acetate, copper fluoroborate or copper nitrate (Claim 7); from about 1 to about 300 g / L of copper ions. 7. The electroplating bath of claim 6 present in an amount of (Claim 8); one or more additives selected from accelerators, inhibitors, levelers, grain refiners, and wetting agents. An electrolytic plating bath (claim 8) is disclosed. Further, in paragraphs [0034] to [0036] of Patent Document 1, as an accelerator (brightening agent), XO ₃ S—S—R—SH, XO ₃ S—R—S—S—R—SO ₃ X XO ₃ —Ar—S—S—Ar—SO ₃ X (wherein R is an optionally substituted alkyl group and preferably an alkyl group having 1 to 6 carbon atoms, more preferably 1 to 4). Ar is an optionally substituted aryl group such as an optionally substituted phenyl group or naphthyl group; and X is a counter ion such as sodium or potassium.). Has been.

（式中、Ｒ^１及びＲ^２は水素、直鎖又は分岐鎖の炭素原子数１〜６アルキル基、若しくは炭素原子数１〜３の置換基を有していてもよい炭素原子数５〜９のシクロアルキル基であり、それぞれ同一でも異なっていてもよいが、Ｒ^１及びＲ^２の全てが同時に水素であることは無い。Ｍはアルカリ金属、アンモニウム、若しくは１価の有機アンモニウムを表し、ｎは１〜７の数を表す）が開示されている。 Patent Document 2 discloses an additive for copper plating comprising a compound represented by the following general formula (1):

(In the formula, R ¹ and R ² are hydrogen, linear or branched alkyl group having 1 to 6 carbon atoms, or optionally having 1 to 3 carbon atoms substituents having 5 to 9 carbon atoms. Each of R ¹ and R ² may not be hydrogen at the same time, M represents an alkali metal, ammonium, or monovalent organic ammonium; Represents a number from 1 to 7).

JP, 2002-302789, A Claims [0034], [0035], [0036] paragraphs JP, 2005-48256, A Claims

  However, although the accelerator disclosed in Patent Document 1 exhibits a certain degree of effect, there is a problem that the plating bath after building bath is deteriorated with time and the practical promoting effect is still insufficient. is there. Moreover, the additive for copper plating disclosed in Patent Document 2 has been insufficient in improving the accelerating effect, although deterioration over time is suppressed to some extent. While it is desired to efficiently manufacture a highly integrated electronic circuit with a finer structure, a more stable and effective additive for electrolytic copper plating is desired at present.

  Accordingly, an object of the present invention is to provide an electrolytic copper plating that is hardly deteriorated with time after the bathing, and that even in a finer structure, it is possible to satisfactorily embed copper in the grooves and holes by electrolytic copper plating. And an electrolytic copper plating bath using the additive as an essential active ingredient, and an electrolytic copper plating method using the copper plating bath.

（式中、Ｒ^１〜Ｒ^４は、水素原子またはメチル基であり、Ｒ^１〜Ｒ^４の全てが同時に水素原子であることは無く、Ｍは、アルカリ金属、アンモニウムまたは１価の有機アンモニウムを表す） As a result of intensive studies in view of the above problems, the present inventors have completed the present invention. That is, the present invention is an additive for electrolytic copper plating comprising a compound represented by the following general formula (1):

(Wherein R ^{1 to} R ⁴ are a hydrogen atom or a methyl group , and all of R ^{1 to} R ⁴ are not simultaneously a hydrogen atom, and M represents an alkali metal, ammonium or monovalent organic ammonium. To express)

  The present invention also provides an electrolytic copper plating bath which is an aqueous solution containing the above-mentioned additive for electrolytic copper plating.

  Furthermore, the present invention is an electrolytic copper plating method characterized by using the above electrolytic copper plating bath.

  The effect of the present invention is that there is almost no deterioration over time of the plating bath after the building bath, and even in a more delicate structure, the copper is satisfactorily embedded without causing voids in the grooves and holes by electrolytic copper plating. The present invention provides an additive for electrolytic copper plating, an electrolytic copper plating bath containing the additive as an essential active ingredient, and an electrolytic copper plating method using the plating bath.

The additive for electrolytic copper plating of the present invention comprises a compound represented by the following general formula (1):

In the general formula ^(1), R 1 ~R ⁴ is Ru hydrogen atom or a methyl group der ^the effect of the present invention with all R 1 to R ⁴ are not hydrogen atoms at the same time can not be obtained. A methyl group is preferred because it has the highest water solubility.

  In the general formula (1), M represents an alkali metal, ammonium, or monovalent organic ammonium. Here, lithium, sodium, potassium, etc. are mentioned as an alkali metal. Examples of monovalent organic ammonium include alkanol ammonium such as monoethanolamine and diethanolamine, and alkylammonium such as methylammonium, ethylammonium and dimethylammonium. Note that M is preferably an alkali metal or ammonium.

  The compound represented by the general formula (1) is more preferably a symmetrical compound that is easy to synthesize and advantageous in terms of cost.

Specific examples of the compound represented by the general formula (1) preferable as an additive for electrolytic copper plating of the present invention are shown below:

  Next, the electrolytic copper plating bath of the present invention will be described. The electrolytic copper plating bath of the present invention is an aqueous solution containing, as an essential active ingredient, the additive for electrolytic copper plating of the present invention comprising the compound represented by the general formula (1). From the viewpoint of obtaining the effect of the present invention more remarkably, the preferable concentration is 0.1 to 100 mg / liter, more preferably 0.5 to 50 mg / liter, and further preferably 1 to 30 mg / liter.

  Components other than the additive for electrolytic copper plating of the present invention blended in the electrolytic copper plating bath of the present invention may be used in the same manner as conventionally known electrolytic copper plating baths. For example, copper salts that are copper sources include copper sulfate, copper acetate, copper fluoroborate, copper nitrate, etc., and inorganic acids that are electrolytes include sulfuric acid, phosphoric acid, nitric acid, hydrogen halide, sulfamic acid. , Boric acid, fluoroboric acid and the like.

The electrolytic copper plating bath of the present invention is particularly preferably a plating bath based on copper sulfate and sulfuric acid. In this case, copper sulfate (as CuSO ₄ .5H ₂ O) is preferably 10 to 300 g / liter, more preferably 100 to 300 g / liter, sulfuric acid 20 to 400 g / liter, more preferably 30 to 150 g / liter. Is efficient.

  Furthermore, it is preferable to mix | blend a chloride ion with the electrolytic copper plating bath of this invention so that it may become 20-150 mg / liter in a plating bath. Although it does not specifically limit as a chloride ion source, For example, NaCl, HCl, etc. can be used.

  Furthermore, it is preferable to add a copper plating inhibitor to the electrolytic copper plating bath of the present invention. As the copper plating inhibitor, for example, an oxygen-containing polymer organic compound can be used. Specifically, polyethylene glycol, polypropylene glycol, polyoxyethylene-polyoxypropylene random copolymer, polyoxyethylene-polyoxypropylene block A copolymer etc. are mentioned. From the viewpoint of remarkably obtaining the effects of the present invention, these oxygen-containing polymer organic compounds preferably have a molecular weight of 500 to 100,000, more preferably 1,000 to 10,000. From the same viewpoint, the amount of the oxygen-containing polymer organic compound used is preferably 20 to 5000 mg / liter, more preferably 50 to 3000 mg / liter in the plating bath.

  Furthermore, a leveler may be blended in the electrolytic copper plating bath of the present invention. Examples of the leveler include dyes or derivatives thereof, amide compounds, thioamide compounds, aminocarboxylic acid compounds, nitrogen-containing heterocyclic compounds, and thioureas. These are usually used at a concentration of 0.1 to 100 mg / liter, preferably 0.5 to 50 mg / liter, more preferably 1 to 30 mg / liter.

  Specific examples of the leveler include auramine, Janus green, Janus black, methyl violet, crystal violet, CI (Color Index) basic red 2, toluidine blue, CI direct yellow 1, and CI basic. Black 2,3-amino-6-dimethylamino-2-methylphenazine monohydrochloride and the like, derivatives of these dyes, succinimides, imidazolines such as 2'-bis (2-imidazoline), imidazoles, benzo Imidazoles, indoles, 2-vinylpyridine, 4-acetylpyridine, 4-mercapto-2-carboxylpyridine, pyridines such as 2,2′-bipyridyl, phenanthroline, quinolines, isoquinolines, aniline, 3,3 ′ , 3 ''-nitrilotripropionic acid, diaminomethylene Minoacetic acid, glycine, N-methylglycine, dimethylglycine, β-alanine, cysteine, glutamic acid, aspartic acid, aminovaleric acid, ornithine, thiourea, 1,3-dimethylthiourea, trimethylthiourea, diethylthiourea, N, N Examples include '-diisopropylthiourea, allylthiourea, acetylthiourea, ethylenethiourea, 1,3-diphenylthiourea, and thiourea dioxide.

  In the electrolytic copper plating bath of the present invention, other additives known to be added to the copper plating bath can be arbitrarily used within a range that does not impair the object of the present invention.

  Other additives include anthraquinone derivatives, cationic surfactants, nonionic surfactants, anionic surfactants, amphoteric surfactants, alkane sulfonic acids, alkane sulfonates, alkane sulfonate esters, hydroxyalkane sulfones. Examples include acids, hydroxyalkanesulfonic acid salts, hydroxyalkanesulfonic acid esters, and hydroxyalkanesulfonic acid organic acid esters. In particular, when hydroxyalkanesulfonic acid is used, it is preferable to use this because it is possible to prevent void generation by eliminating uneven copper deposition even for trenches and vias having a large aspect ratio. Isethionic acid is preferred. The suitable use amount of hydroxyalkanesulfonic acid is a range in which 0.1 to 10 times by mass ratio of the additive 1 for electrolytic copper plating of the present invention shows a good additive effect.

The electrolytic copper plating method of the present invention may be performed in the same manner as the conventional electrolytic copper plating method except that the electrolytic copper plating bath of the present invention is used as the electrolytic copper plating bath. For example, the plating bath temperature is 15 to 40 ° C., preferably 20 to 30 ° C., and the current density is 1.0 to 30 A / dm ² , preferably 2.0 to 5 A / dm ² . Moreover, the stirring method of a plating bath can use air stirring, rapid liquid flow stirring, mechanical stirring by a stirring blade, etc.

The invention is further illustrated by the following examples, but it should be understood that the invention is not limited thereto.
Example 1 and Comparative Example 1
About the electrolytic copper plating bath of the mixing | blending described below, the current density-potential difference measurement was performed. The results are shown in FIG. From FIG. 1, it was confirmed that the electrolytic copper plating bath using the above compound 2 as an additive for electrolytic copper plating can easily pass current as compared with the comparative example using the additive which is a similar compound. This means that the plating acceleration effect at the time of electrolytic copper plating is great.

(Combination)
Example 1: Copper sulfate pentahydrate 200 g / liter, sulfuric acid 50 g / liter, polyethylene glycol (PEG 3000) having a number average molecular weight of 3,000 100 mg / liter, Compound 2 = 10 mg / liter, hydrochloric acid 50 mg / liter Comparative Example 1: Sulfuric acid Copper pentahydrate 200 g / liter, sulfuric acid 50 g / liter, polyethylene glycol (PEG 3000) with a number average molecular weight of 3000 100 mg / liter, comparative compound 1 of the following formula 1 = 10 mg / liter, hydrochloric acid 50 mg / liter

Comparative compound 1

Examples 2-9, Comparative Examples 2-5
Each electrolytic copper plating bath was constructed (prepared) at the ratio shown in Tables 1 and 2. Next, three types of electrolytic copper plating baths with the composition shown in Table 1 were prepared for the printed circuit board on which vias having a diameter of 30 μm and an aspect ratio of 1.0 were prepared, immediately after the bathing, 60 minutes after the bathing, and 24 hours after the bathing. In this state, electrolytic copper plating was performed under the conditions of a cathode current density of 2 A / dm ² , a bath temperature of 30 ° C., and a plating time of 30 minutes. About the obtained printed circuit board, the cross section of the via part was observed with the scanning electron microscope, and the presence or absence of the void was evaluated. The results are shown in Tables 1 and 2.

Comparative compound 2

  As can be seen from Table 1 and Table 2, when electrolytic copper plating is performed with an electrolytic copper plating bath using the additive for electrolytic copper plating of the present invention, no deterioration with time of the plating bath after the building bath is observed, and good copper Can be embedded.

  Provided with an electrolytic copper plating bath that can be embedded well without causing voids in grooves and holes even with a finer structure with little deterioration over time after building bath. It is applied to applications in which copper is embedded in grooves and holes by electrolytic copper plating, such as a damascene method in the manufacture of integrated electronic circuits.

It is a graph which shows the result of the current density-potential difference measurement of the electrolytic copper plating bath obtained in Example 1 and Comparative Example 1.

Claims (4)

Electrolytic copper plating additive comprising a compound represented by the following general formula (1):

(Wherein R ^{1 to} R ⁴ are a hydrogen atom or a methyl group , and all of R ^{1 to} R ⁴ are not simultaneously a hydrogen atom, and M represents an alkali metal, ammonium or monovalent organic ammonium. To express) Electrolytic copper plating bath, characterized in that the aqueous solution containing the electrolytic copper plating additive according to claim 1 Symbol placement. Furthermore, the electrolytic copper plating bath of Claim 2 containing a copper sulfate, a sulfuric acid, a chloride ion, and an oxygen containing high molecular organic compound. Electrolytic copper plating method characterized by using the claim 2 or 3 electrolytic copper plating bath according.

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