JP6948587B2 - Electro-copper plating bath and electro-copper plating method for low stress film formation - Google Patents

Description

The present invention provides an electrolytic copper plating bath for forming a low stress film and an electrolytic copper plating method capable of preventing warpage of the copper film after plating.

In ordinary electrolytic copper plating, tensile stress acts inside the coating after plating, and the copper film warps concavely toward the surface of the plating with the passage of time (for example, after 1 to 2 days). There is a phenomenon called. In other words, tensile stress acts on each other inside the plating film on the base material such as bumps and leads, and the surface side facing the outside of the film shrinks in the length direction, whereas the base material in the film shrinks. Since the length of the contact surface side facing the surface does not change, a phenomenon is observed in which the plating film warps in a concave shape with the surface side facing up (in other words, warps in a convex shape toward the lower base material). (See FIG. 1A).
The warp progresses over time during these 1 to 2 days, then shifts to a steady state, and does not warp any more, but for example, a wafer of 200 μm or less, or a film such as a polyimide resin, an epoxy resin, or a polycarbonate resin. When copper is plated on a thin base material like this, the entire base material on which the film is formed warps over time, and when various chip components such as ICs are mounted on the base material via the plating film, bumps, etc. There is a problem that the reliability of electronic components is impaired due to poor joining such as cracking of the joint.
In addition, when the adhesion between the copper plating film and the object to be plated is low, if the plating film warps, the film itself will peel off from the object to be plated. It will impair reliability.

Generally, in electrolytic copper plating, a leveler, a brightener, a polymer, a chloride, or the like is added in order to promote the uniformity, smoothness, and glossiness of the electrodeposited film.
Therefore, it is considered that these components act in a complex manner to affect the warp of the copper film. Conventional techniques related to electrolytic copper plating are as follows.
(1) Patent Document 1
Heterocyclic nitrogen compounds having an imidazole ring, a tetrazole ring, a pyridine ring, a benzothiazole ring, etc., and a polyhalogen compound (2,4-bis (chloromethyl) -1,3,5-trimethylbenzene, 1,2-dichloroethane) Etc.) and a product obtained by reacting a polyepoxide compound (1,4-butanediol diglycidyl ether, etc.) with an electrolytic copper plating solution (claims 1 to 2, 6, [0029] to [0033]. ), By containing the above reaction product, the uniform electrodeposition property and smoothness of the copper film obtained from the plating solution can be improved ([0007]).
In this case, among the heterocyclic nitrogen compounds are not mercapto groups in the substituents R ₁ of the 5-membered ring compound (claim 3), also 6-membered ring compound (claim 5), condensed heterocyclic nitrogen compound (Claim 4) has no substituent.
For example, in Example 1, imidazole (heterocyclic compound), 2,4-bis (chloromethyl) -1,3,5-trimethylbenzene (polyhalogen compound), and 1,4-butanediol diglycidyl ether. The reaction product with (polyepoxide compound) is disclosed ([0056], see Table 1).

(2) Patent Document 2
A polyalkene oxide compound having a number average molecular weight of 1 to 2 million or more and having a functional group such as a sulfonic acid group, an amino group, a mercapto group, a phenyl group, a phenyloxide group, a phenylazophenoxy group, or a halogen bonded to the terminal. (Claims 1 to 3, [0032], [0037] to [0039]), and the above additive has a molecular weight of 100 or more. , Stable and good copper plating can be performed even if the amount of chlorine in the plating solution is small, and it is not necessary to use additives such as bis (3-sulfopropyl) disulfide (SPS) and yanus green together ([0033]). ..
In the polyalkene oxide compound, for example, dichloropolyethylene glycol belonging to an organic halide and the like are disclosed ([0037] to [0038]).

(3) Patent Document 3
This is a copper filling method in which a copper plating bath containing a leveler compound composed of a quaternary dipyridyl salt compound which is a reaction product of a dipyridyl compound and an alkylating agent can be applied to a substrate to suppress the generation of voids and improve plating defects. (Claims 1-42, paragraphs 22-23).
The dipyridyl compound is, for example, a pyridine derivative in which pyridine rings are directly bonded to each other by carbon-carbon or bonded via an ethylene group (claim 6, paragraph 26).
The alkylating agent is 2-chloroethyl ether, benzyl chloride, 2- (2-chlorotoxy) ethanol, chloroethanol, dichlorohexane, a compound having a glycol bond, and the like (claim 20, paragraphs 39, 46, 55).
In Example 1, a soluble copper salt, sulfuric acid, chloride ion, an electrodeposition accelerator, an electrodeposition inhibitor, and a pyridine derivative in which pyridine rings are bonded to each other via an ethylene group are alkylated with 2-chloroethyl ether. A copper-plated bath containing a modified leveler compound is disclosed (paragraph 124). In this case, the leveler compound is a product obtained by reacting a heterocyclic nitrogen compound (pyridine derivative) with an organic chlorine compound (2-chloroethyl ether).

(4) Patent Document 4
Inhibitors such as polyoxyalkylene glycol, carboxymethyl cellulose, polyethylene glycol, polypropylene glycol, polyvinyl alcohol, SPS, mercaptopropanesulfonic acid (MPS), N, N-dimethyl-dithiocarbamylpropanesulfonic acid (DPS), 3-[ (Aminoiminomethyl) Thio] A method of forming a copper film with low internal stress by electroplating with a copper plating solution containing an electrodeposition accelerator such as -1-propanesulfonic acid (UPS) (claim 1). ~ 6, Table 1).
In Example 1, a copper-plated bath (baths 2-4) containing MPS (salt), SPS (salt), polyoxyalkylene glycol, and polyethylene glycol is described, and the total concentration of MPS (salt) and SPS (salt) is described. Is 5-9 ppm.

Japanese Unexamined Patent Publication No. 2015-227327 Japanese Unexamined Patent Publication No. 2008-223082 Japanese Patent Application Laid-Open No. 2012-510179 Japanese Unexamined Patent Publication No. 2013-060660

In the electrolytic copper plating solution shown in Patent Documents 1 to 4 or the electrolytic copper plating method including pretreatment, as described above, tensile stress acts on the obtained electrodeposition film of copper with the passage of time. As a result, it warps upward toward the plated surface (see FIG. 1A), and it is not easy to ensure the reliability of loading various chip components on the substrate.
For example, in the example ([0056]) of Patent Document 1, imidazole (heterocyclic compound) and 2,4-bis (chloromethyl) -1,3,5-trimethylbenzene (polyhalogen compound) are used. A compound obtained by reacting 1,4-butanediol diglycidyl ether (polyepoxide compound) is exemplified, but even if the compound is added to the electrolytic copper plating solution as a leveler, the obtained copper film is warped over time. It is not enough to suppress the above (see the comparative example described later).
An object of the present invention is to effectively prevent the plating film from warping over time during copper plating.

The present inventors have focused on the products described in Patent Documents 1 to 4, particularly heterocyclic nitrogen compounds and organic halogen compounds which are reactants for obtaining the products, and modified them. Regarding the products obtained by reacting the compounds, when the products were added to the electrolytic copper plating solution, the relationship between various products and the warpage of the obtained copper film was intensively studied.
As a result, a product obtained by reacting a compound (1) obtained by introducing mercapto into a nitrogen compound having a predetermined heterocycle with a predetermined organic halogen compound (2), or a polyalkylene glycol having a reactive group. When the product obtained by reacting (3) is added to the electrolytic copper plating solution as a leveler, it is possible to effectively prevent the obtained copper film from warping over time as compared with the compound disclosed in Patent Document 1. An unexpected effect was confirmed.
Further, sulfur-containing compounds such as mercaptopropanesulfonic acid (MPS) or a salt thereof, bis (3-sulfopropyl) disulfide (SPS), etc. are used as compounds that perform an electrodeposition promoting function in electrolytic copper plating. We have found that the effect of preventing warpage of the copper film can be further enhanced by using this sulfur-containing compound in addition to the above leveler in an electrodeposited copper plating bath at a concentration equal to or higher than a predetermined value, and completed the present invention.

That is, the present invention 1 is in an electrolytic copper plating bath containing a soluble copper salt and an acid or a salt thereof.
Contains compound (B) selected from at least one of the following levelers (L1) and levelers (L2):
The leveler (L1) is a reaction product of (a) a heterocyclic nitrogen compound having a mercapto group and (b) an organic halogen compound.
The leveler (L2) is a reaction product of (a) a heterocyclic nitrogen compound having a mercapto group, (b) an organic halogen compound, and (c) a polyalkylene glycol having a reactive group at one end or both ends. hand,
The above component (a) includes an imidazole ring, a pyridine ring, a purine ring, a benzoimidazole ring, a benzothiazole ring, an imidazoline ring, a triazole ring, a tetrazole ring, a thiazizol ring, a pyrimidine ring, a pyrazine ring, a quinoline ring, a benzoxazole ring, and a morpholin. It is a nitrogen compound having a heterocycle selected from the group consisting of a ring and a pyrrol ring (however, in the case of leveler (L1), the above heterocycle excluding the pyridine ring).
The component (b) has at least one halogen in the alkylene chain, or has a functional group selected from the group consisting of an amino group, an ether group, a hydroxyl group, and a sulfonic acid group together with the halogen. It is an electrolytic copper plating bath for forming a low stress film, which is characterized by being an organic halogen compound.

The present invention 2 is in an electrolytic copper plating bath containing a soluble copper salt and an acid or a salt thereof.
(A) Contains 50 to 10000 mg / L of a sulfur-containing compound selected from sulfides, mercaptans, thiopropylsulfonic acids, and dithiocarbamic acids, and at the same time.
(B) A leveler (L1) which is a reaction product of a heterocyclic nitrogen compound (a) having a mercapto group and an organic halogen compound (b), a heterocyclic nitrogen compound (a) having a mercapto group, and an organic halogen. It contains at least one of levelers (L2), which is a reaction product of compound (b) and a polyalkylene glycol (c) having a reactive group at one end or both ends.
The above component (a) includes an imidazole ring, a pyridine ring, a purine ring, a benzoimidazole ring, a benzothiazole ring, an imidazoline ring, a triazole ring, a tetrazole ring, a thiazizol ring, a pyrimidine ring, a pyrazine ring, a quinoline ring, a benzoxazole ring, and a morpholin. It is a nitrogen compound having a heterocycle selected from the group consisting of a ring and a pyrrol ring (however, in the case of leveler (L1), the above heterocycle excluding the pyridine ring).
The component (b) has at least one halogen in the alkylene chain, or has a functional group selected from the group consisting of an amino group, an ether group, a hydroxyl group, and a sulfonic acid group together with the halogen. It is an electrolytic copper plating bath for forming a low stress film, which is characterized by being an organic halogen compound.

In the present invention 3, the reactive group contained in the polyalkylene glycol (c) in the present invention 1 or 2 is selected from the group consisting of a halogen group, a haloformyl group, a mesylate group, and a tosylate group. It is an electrolytic copper plating bath for forming a characteristic low stress film.

In the present invention 4, among the sulfur-containing compounds (A), the sulfides are bis (3-sulfopropyl) disulfide (SPS), bis (2-sulfopropyl) disulfide, and bis (3) in the above invention 2 or 3. Selected from −sul-2-hydroxypropyl) disulfides, bis (4-sulfopropyl) disulfides, bis (p-sulfophenyl) disulfides and salts thereof.
Similarly, mercaptans are selected from mercaptomethanesulfonic acid, mercaptoethanesulfonic acid, mercaptopropanesulfonic acid (MPS) and salts thereof.
Thiopropyl sulfonic acids include 3- (benzothiazolyl-2-thio) propane sulfonic acid (ZPS), 3-[(aminoiminomethyl) thio] -1-propane sulfonic acid (UPS), O-ethyl-diethylcarbonate-S. -(3-Sulfonpropyl) -esters and selected from these salts,
Dithiocarbamic acids are selected from N, N-dimethyl-dithiocarbamylpropanesulfonic acid (DPS), N, N-dimethyl-dithiocarbamic acid- (3-sulfopropyl) -esters and salts thereof. It is a characteristic electrolytic copper plating bath for forming a low stress film.

In the present invention 5, a low-stress plating film having a warp suppressing function is formed on a thin object to be plated of 500 μm or less by using any of the above-mentioned electrolytic copper plating baths of the present inventions 1 to 4, and the object to be plated is formed. This is an electrolytic copper plating method characterized by preventing the integrated plating film from warping.

In the present invention 6, a low-stress copper-plated film having a warp suppressing function of 0.1 μm to 5000 μm is formed on the object to be plated by using the electrolytic copper plating bath according to any one of the above inventions 1 to 4, and the warping action is performed. This is an electrolytic copper plating method characterized by preventing the plating film from peeling off from the object to be plated.

In the electrolytic copper plating bath of the present invention, a leveler L1 consisting of a product obtained by selecting a predetermined heterocyclic nitrogen compound having a mercapto group as a reaction product and reacting the reaction product with a predetermined organic halogen compound, or a polyepoxide compound. Since it contains the leveler L2 reacted with the above, it is possible to impart a low stress property to the obtained copper film and effectively prevent the film from warping over time.
Further, when a specific sulfur-containing compound (A) is allowed to coexist in the electrolytic copper plating bath at a predetermined concentration or higher in addition to the leveler L1 and / or the leveler L2, the warpage of the copper film over time is more effectively prevented. can. When an electrodeposition accelerator is contained in an electrolytic copper plating bath, a sulfur-containing compound such as SPS (bis (3-sulfopropyl) disulfide) is usually blended in a very small amount at a ratio of about 3 to 10 mg / L. It is also characterized by blending more than usual in the range of 50 to 10,000 mg / L.
Further, in the plating bath of the present invention, a copper film having a warp prevention function can be obtained even if the polymer component generally used in a general electrolytic copper plating bath is omitted.
That is, since the internal stress of the plating film formed in the copper plating bath of the present invention shows a compressive stress of approximately 0 to -30 MPa in the strip electrodeposition stress test (see FIG. 1B), the tension acting on the copper plating film over time. Even if it tries to warp due to stress (see FIG. 1A), this compressive stress approaches 0 MPa against the tensile stress, so that a film having almost no warp can be formed over time.
Therefore, even if the thin object to be plated is electroplated using the copper plating bath of the present invention, or the object to be plated having low adhesion is electroplated, both of the copper film after electroplating Warpage can be prevented smoothly, and the reliability of electronic parts can be improved.
Therefore, the copper-plated bath of the present invention is suitable for forming a fine wiring circuit requiring low stress, via filling, and the like.

Patent Document 1 discloses an electrolytic copper plating solution containing a product obtained by reacting a heterocyclic nitrogen compound such as an imidazole ring, a tetrazole ring, a pyridine ring, and a benzothiazole ring with a polyhalogen compound and a polyepoxide compound. However (claims 1 to 2, 6, [0029] to [0033]), the heterocyclic nitrogen compound does not have a mercapto group.
In this case, as is clear from the evaluation test results described later, the electrolytic copper plating bath containing the leveler of the present invention composed of a reaction product of a heterocyclic nitrogen compound having a mercapto group and an organic halogen compound is used. Comparing with an electrolytic copper plating bath using a heterocyclic nitrogen compound having no mercapto group in accordance with Patent Document 1, the plating bath of the present invention has a function of suppressing warpage of an electrodeposited film obtained from the plating bath. Shows a remarkable advantage over the bath according to Patent Document 1.
Even when the sulfur-containing compound of the present invention coexists in the plating bath of the present invention and the plating bath according to Patent Document 1, the plating bath of the present invention also has a remarkable advantage.

In the present invention, first, a predetermined heterocyclic nitrogen compound having a mercapto group is selected as a reactant, and a predetermined organic halogen compound is reacted with the reaction product, or a polyalkylene glycol having a reactive group is further reacted. It is an electrolytic copper plating bath (the present invention 1) containing the produced products (levelers L1 and L2), and secondly, a sulfur-containing compound specific to the leveler (B) selected from the above products L1 and L2. This is an electrolytic copper plating bath in which (A) coexists at a predetermined concentration or higher (the present invention 2), and thirdly, a method of electrolytic copper plating a predetermined thin object to be plated using the above copper plating bath (the present invention). The fourth invention is a method of electrolytic copper plating the object to be plated using the copper plating bath when the adhesion between the copper film and the object to be plated is low (the invention 6). ..

The electrolytic copper plating bath of the present invention 1 is characterized by containing a soluble copper salt, an acid or a salt thereof, and a compound (B) selected from specific levelers (L1) and (L2).
As the soluble copper salt added to the electrolytic copper plating bath, any soluble salt that generates copper ions in an aqueous solution can be used, there is no particular limitation, and a poorly soluble salt is not excluded. Specific examples thereof include copper sulfate, copper oxide, copper hydroxide, copper chloride, copper nitrate, copper carbonate, copper acetate and copper oxalate, and copper oxide, copper nitrate, copper oxide and copper hydroxide are preferable. The content of the soluble copper salt in the plating bath is 10 to 70 g / L in terms of divalent copper ions, preferably 30 to 60 g / L.
As the base acid of the electrolytic copper plating bath, acids commonly used in ordinary copper plating baths such as sulfuric acid, hydrochloric acid, oxalic acid, and acetic acid can be used, and organic acids such as organic sulfonic acid and oxycarboxylic acid can be used. It can also be used.
The salt of the base acid is an alkali metal salt, an alkaline earth metal salt, an ammonium salt, an amine salt and the like.
The content of the acid or its salt in the plating bath is 10 to 300 g / L, preferably 30 to 150 g / L.

The compound (B) is selected from a specific leveler (L1) and a leveler (L2), and either the leveler (L1) or the leveler (L2) may be used alone, or the leveler (L1) and the leveler (L2) may be used alone. ) May be used together.
The leveler (L1) is a product obtained by reacting (a) a predetermined heterocyclic nitrogen compound having a mercapto group with (b) a predetermined organic halogen compound.
Regarding a predetermined heterocyclic nitrogen compound (a) having a mercapto group which is one of the leveler (L1) reactants, the predetermined heterocycle is an imidazole ring , a purine ring, a benzoimidazole ring, a benzothiazole ring, an imidazoline ring, or a triazole ring. , Tetrazole ring, thiazazole ring, pyrimidine ring, pyrazine ring, quinoline ring, benzoxazole ring, morpholine ring, pyrrole ring, preferably imidazole ring, pyridine ring, benzothiazole ring, tetrazole ring, thiazazole ring and the like. Is.
Examples of the heterocyclic nitrogen compound (a) include 4-mercaptoquinolin-2-carboxylic acid, 2-mercapto-2H-pyrrole, mercaptopurine, 5-mercapto-1-methyltetrazole, 1- (2-dimethylaminoethyl). -5-Mercaptotetrazole, 2-mercaptobenzimidazole, 2-mercapto-1H-imidazole, 2-mercapto-1-methylimidazole, 3-mercapto-1,2,4-triazole, 2-mercaptobenzothiazole, 4-acetamide -7-Mercapto-2,1,3-Benzodiazole, 2-mercaptoimidazole (ethylenethiourea), 2,5-dimercapto-1,3,4-thiazazole (bismthiol), 2- (2-mercaptoethyl) -1,3-dioxane, 4-amino-6-hydroxy-2-mercaptopyrimidine hydrate, 2-quinoline thiol, 3-mercaptoquinolin, 8-quinoline thiol, 2-amino-5-mercapto-1,3, Examples thereof include 4-thiazole, 5-methyl-1,3,4-thiazisol-2-thiol and the like.
Preferred heterocyclic nitrogen compounds (a) are 5-mercapto-1-methyltetrazole, 2-mercapto-1H-imidazole, 2-mercaptoimidazoline (ethylenethiourea), 2,5-dimercapto-1,3,4-thiadiazole ( Bismuthiol), 5-methyl-1,3,4-thiadiazole-2-thiol and the like.

The predetermined organic halogen compound (b), which is the other reactant of the leveler (L1), has at least one or more halogens in the alkylene chain, or together with the halogens, further amino groups, ether groups, hydroxyl groups, It is selected from compounds having a functional group selected from the group consisting of sulfonic acid groups.
Examples of the organic halogen compound (b) include chloroethyl ether, chloroethanol, 1,2-dichloroethane, 1,5-dichloropentane, 1,6-dichlorohexane, 1,8-dichlorooctane, and bis (bromoethyl) ether, 1 , 5-Dibromopentane, 1,6-dibromohexane, 1,8-dibromooctane, 2-chloroethylamine, bis (2-chloroethyl) amine, 2- (dimethylamino) ethyl chloride, 3-chloro-1-propanol, 3-Dichloro-2-propanol, 3-chloropropane, bis (2-chloroethyl) ether, 2-chloroethyl methyl sulfide, 2- (2-chloroethoxy) ethanol, sodium 2-chloroethanesulfonate, 2,2'-dichloro Examples thereof include ethyl ether and 2-bis (2-chloroethoxy) ethane.
Preferred organic halogen compounds (b) include 2-chloroethylamine, 2- (dimethylamino) ethyl chloride, 3-chloro-1-propanol, bis (2-chloroethyl) amine, 3-chloropropane, 2-chloroethyl methyl sulfide and the like. Is.

The leveler (L2) reacts (a) a predetermined heterocyclic nitrogen compound having a mercapto group, (b) a predetermined organic halogen compound, and (c) a polyalkylene glycol having a reactive group at one end or both ends. It is a product that has been made to grow.
The component (b), which is a reaction product of the leveler (L2), is the same as that of the leveler (L1).
Regarding the component (a) which is a reaction product of the leveler (L2), a pyridine ring is added to a predetermined heterocycle of the heterocyclic nitrogen compound of the leveler (L1).
That is, with respect to the predetermined heterocyclic nitrogen compound (a) having a mercapto group which is a reaction product of the leveler (L2), the predetermined heterocycle is an imidazole ring , a pyridine ring, a purine ring, a benzoimidazole ring, a benzothiazole ring, or an imidazoline ring. , Triazole ring, tetrazole ring, thiazazole ring, pyrimidine ring, pyrazine ring, quinoline ring, benzoxazole ring, morpholin ring, pyrrole ring, preferably imidazole ring, pyridine ring, benzothiazole ring, tetrazole ring, For example, thiazazole ring.
The heterocyclic nitrogen compound (a) includes 4-mercaptoquinoline-2-carboxylic acid, 2-mercapto-2H-pyrrole, mercaptopurine, 2-mercaptopyridine, 4-mercaptopyridine, 5-mercapto-1-methyltetrazole. , 1- (2-Dimethylaminoethyl) -5-mercaptotetrazole, 2-mercaptobenzoimidazole, 2-mercapto-1H-imidazole, 2-mercapto-1-methylimidazole, 3-mercapto-1,2,4-triazole , 2-Mercaptobenzothiazole, 4-acetamide-7-Mercapto-2,1,3-benzoxaziazole, 2-mercaptoimidazoline (ethylenethiourea), 2,5-dimercapto-1,3,4-thiazylazole (bismthiol) ), 2- (2-Mercaptoethyl) -1,3-dioxane, 4-amino-6-hydroxy-2-mercaptopyrimidine hydrate, 2-quinoline thiol, 3-mercaptoquinoline, 8-quinoline thiol, 2- Examples thereof include amino-5-mercapto-1,3,4-thiazylazole, 5-methyl-1,3,4-thiazylazole-2-thiol and the like.
Preferred heterocyclic nitrogen compounds (a) are 2-mercaptopyridine, 4-mercaptopyridine, 5-mercapto-1-methyltetrazole, 2-mercapto-1H-imidazole, 2-mercaptoimidazoline (ethylenethiourea), 2,5-. Dimercapto-1,3,4-thiadiazole (bismthiol), 5-methyl-1,3,4-thiadiazole-2-thiol and the like.
Regarding the polyalkylene glycol (c) having a reactive group, which is the third reactant of the leveler (L2), the polyalkylene glycol is a homopolymer or copolymer of C2-C4 alkylene glycol, and polyethylene glycol (PEG), polypropylene. Glycol (PPG) or a copolymer of ethylene glycol and propylene glycol is preferred, more preferably PEG.
The reactive group having at least one end of the polyalkylene glycol is selected from the group consisting of a halogen group, a haloformyl group, a mesylate group and a tosylate group.

The content of the leveler L1 with respect to the copper plating bath is 0.1 to 500 mg / L, preferably 0.5 to 200 mg / L, and more preferably 1 to 50 mg / L. If the content is less than the appropriate range, the obtained copper film does not have sufficient low stress properties and the warp prevention function deteriorates. On the contrary, even if it is increased from the appropriate range, there is not much difference in the warp prevention function, but the copper film. There is a risk of degrading the physical properties of.
The content of the leveler L2 in the copper plating bath is the same as that of the leveler L1, and the content of the leveler L1 and L2 in combination is also the same as that of the case where each leveler is used alone.

Therefore, first, Synthesis Examples 1 to 3 classified into leveler L1, which is a product obtained by reacting the component (a) and the component (b), will be illustrated.
(1) Synthesis Example 1 (Leveler L1)
This is an example of reacting an imidazole compound (a) having a mercapto group (= 2-mercapto-1H-methylimidazole) with bis (2-chloroethyl) amine (b).
To a 1 L three-necked flask equipped with a thermometer and a stirrer, 0.5 mol of 2-mercapto-1-methylimidazole, 300 ml of ion-exchanged water and 250 ml of ethanol were added. After replacing the inside of the system with nitrogen, sodium hydroxide was added with stirring. After dissolving 2-mercapto-1-methylimidazole under stirring, the mixture was heated to 40 ° C., 0.5 mol of bis (2-chloroethyl) amine hydrochloride was added, and the mixture was reacted for 2 hours. After completion of the reaction, methylene chloride was added at room temperature and transferred to a separating funnel to separate the methylene chloride layer. After washing by adding ion-exchanged water, the methylene chloride layer was separated again. After the methylene chloride layer was dried over magnesium sulfate, the solvent was distilled off using an evaporator to synthesize a mercaptoimidazole compound.

(2) Synthesis Example 2 (Leveler L1)
This is an example of reacting a tetrazole compound (a) having a mercapto group (= 1- (2-dimethylaminoethyl) -5-mercaptotetrazole) with a bis (2-chloroethyl) ether (b).
To a 1 L three-necked flask equipped with a thermometer and a stirrer, 0.5 mol of 1- (2-dimethylaminoethyl) -5-mercaptotetrazole, 300 ml of ion-exchanged water and 250 ml of ethanol were added. After replacing the inside of the system with nitrogen, an aqueous sodium hydroxide solution was added at 60 ° C. or lower with stirring. After dissolving 1- (2-dimethylaminoethyl) -5-mercaptotetrazole under stirring, the mixture was heated to 70 ° C., 0.5 mol of bis (2-chloroethyl) ether was added, and the mixture was reacted for 14 hours. After completion of the reaction, methylene chloride was added at room temperature and transferred to a separating funnel to separate the methylene chloride layer. After washing by adding ion-exchanged water, the methylene chloride layer was separated again. After the methylene chloride layer was dried, the solvent was distilled off using an evaporator to synthesize a mercaptotetrazole compound.

(3) Synthesis example 3 (leveler L1)
This is an example of reacting benzothiazole (a) having a mercapto group (= 2-mercaptobenzothiazole) with 2- (dimethylamino) ethyl chloride (b) and bis (2-chloroethyl) ether (b).
To a 1 L three-necked flask equipped with a thermometer and a stirrer, 0.5 mol of 2-mercaptobenzothiazole, 300 ml of ion-exchanged water and 250 ml of ethanol were added. After replacing the inside of the system with nitrogen, an aqueous sodium hydroxide solution was added at 60 ° C. or lower with stirring. After dissolving 2-mercaptobenzothiazole under stirring, the mixture was heated to 70 ° C., 0.2 mol of 2- (dimethylamino) ethyl chloride hydrochloride was added, and the mixture was reacted for 15 hours. After completion of the reaction, methylene chloride was added at room temperature and transferred to a separating funnel to separate the methylene chloride layer. After washing by adding ion-exchanged water, the methylene chloride layer was separated again. After the methylene chloride layer was dried, the solvent was distilled off using an evaporator to obtain a reaction product. Then, 0.5 mol of the reaction product, 0.3 mol of bis (2-chloroethyl) ether and 50 g of methyl cellulose were added to a 200 ml three-necked flask equipped with a thermometer and a stirrer. The reaction was carried out at 90 ° C. for 35 hours under stirring. After completion of the reaction, the mixture was cooled to 60 ° C. to synthesize a mercaptobenzothiazole compound.

Next, a synthetic example of leveler L2 classified as a product obtained by reacting the component (a), the component (b), and the component (c) will be illustrated.
(4) Synthesis Example 4 (Leveler L2)
This is an example of reacting thiadiazole (a) (= bismuthiol) having a mercapto group with 2- (dimethylamino) ethyl chloride (b) and polyethylene glycol (c) (= PEG).
To a 1 L three-necked flask equipped with a thermometer and a stirrer, 0.5 mol of bismuthiol, 300 ml of ion-exchanged water and 250 ml of ethanol were added. After replacing the inside of the system with nitrogen, an aqueous sodium hydroxide solution was added at 60 ° C. or lower with stirring. After dissolving bismuthiol under stirring, the mixture was heated to 70 ° C., 0.3 mol of 2- (dimethylamino) ethyl chloride hydrochloride was added, and the mixture was reacted for 12 hours. After completion of the reaction, methylene chloride was added at room temperature and transferred to a separating funnel to separate the methylene chloride layer. After washing by adding ion-exchanged water, the methylene chloride layer was separated again. After drying the methylene chloride layer with magnesium sulfate, the solvent was distilled off using an evaporator to obtain a reaction product. Then, 0.5 mol of the reaction product, 0.5 mol of both-terminal mesylated products of polyethylene glycol (weight average molecular weight 200) and 50 g of methyl cellulose were added to a 200 ml three-necked flask equipped with a thermometer and a stirrer. The reaction was carried out at 90 ° C. for 35 hours under stirring to synthesize a mercaptothiadiazole-based compound.

On the other hand, the electrolytic copper plating bath of the present invention 2 contains a soluble copper salt, an acid or a salt thereof, a specific sulfur-containing compound (A) having a predetermined concentration or more, and a leveler (B), and contains sulfur. It is characterized in that the compound (A) and the leveler (B) are used in combination.
The soluble copper salt, acid or salt thereof is as described in the copper plating bath of the present invention 1.
Further, the leveler (B) is the same as the compound (B) used in the copper plating bath of the present invention 1, and can be selected from the specific leveler (L1) and the leveler (L2) of the present invention 1. (L1) or the leveler (L2) may be used alone, or the leveler (L1) and the leveler (L2) may be used in combination.
However, when the leveler (L1) is selected as the leveler (B) of the present invention 2, the pyridine ring is not included in the specific heterocycle of the heterocyclic nitrogen compound (a) as in the present invention 1. On the other hand, when the leveler (L2) is selected as the leveler (B) of the present invention 2, there is no such limitation.
The specific sulfur-containing compound (A) of the present invention 2 is selected from sulfides, mercaptans, thiopropylsulfonic acids, and dithiocarbamic acids.
The above sulfides are bis (3-sulfopropyl) disulfide (SPS), bis (2-sulfopropyl) disulfide, bis (3-sul-2-hydroxypropyl) disulfide, bis (4-sulfopropyl) disulfide, and bis ( p-sulfophenyl) disulfides and salts thereof.
The mercaptans include mercaptomethanesulfonic acid, mercaptoethanesulfonic acid, mercaptopropanesulfonic acid (MPS) and salts thereof.
The thiopropyl sulfonic acids are 3- (benzothiazolyl-2-thio) propane sulfonic acid (ZPS), 3-[(aminoiminomethyl) thio] -1-propane sulfonic acid (UPS), and O-ethyl-diethyl carbonate-. S- (3-sulfopropyl) -esters and salts thereof.
The dithiocarbamic acids include N, N-dimethyl-dithiocarbamylpropanesulfonic acid (DPS), N, N-dimethyl-dithiocarbamic acid- (3-sulfopropyl) -ester, and salts thereof.

Regarding the electrolytic copper plating bath in which the sulfur-containing compound (A) and the leveler (B) of the present invention 2 are used in combination, the sulfur-containing compound (A) can be used alone or in combination, and the content in the electrolytic copper plating bath is 50 to 10,000 mg /. It is L, preferably 100 to 1500 mg / L, and more preferably 50 to 1000 mg / L.
Generally, the electrolytic copper plating bath contains a sulfur-containing compound such as SPS as an electrodeposition accelerator. Normally, the content thereof is a very small amount of about 3 to 10 mg / L, but in the present invention 2, 50 It is also characterized by blending at a concentration higher than usual of 10000 mg / L.
If the amount of the sulfur-containing compound (A) is less than the appropriate range, the low stress property cannot be imparted to the copper-plated film, and if it is more than the appropriate range, the low stress can be maintained, but the resistance value of the film increases and the film becomes rough. Alternatively, it becomes brittle and the physical properties of the film deteriorate.
The content of the leveler (B) in the copper-plated bath is generally 0.1 to 500 mg / L, preferably 0.5 to 200 mg / L, as in the case of the copper-plated bath of the present invention 1. It is preferably 1 to 50 mg / L.
Further, in the present invention 2, the content ratio (weight ratio) of the sulfur-containing compound (A) and the leveler (B) is A / B = 1 to 500, preferably 1 to 300, and more preferably 2 to 100.

In the electrolytic copper plating bath of the present invention, known levelers, brighteners, chlorides, polymers and the like can be contained in order to promote the glossing action and the smoothing action.
Regarding the above chloride, since chlorine having a predetermined concentration or more promotes the warp of the copper film, it is preferable that the content in the plating bath is small (see paragraph 7 of JP-A-2014-125679).
Further, as described above, in the electrolytic copper plating bath of the present invention, a copper film having a warp prevention function can be obtained even if the inclusion of the polymer is omitted.
The leveler is a nitrogen-based organic compound mainly composed of a surfactant or a dye.
As this surfactant, a nonionic surfactant, an amphoteric surfactant, a cationic surfactant, or an anionic surfactant can be used alone or in combination.
Examples of the nonionic surfactant include polyethylene glycol (hereinafter referred to as PEG), polypropylene glycol, C1 to C20 alkanol, phenol, naphthol, bisphenols, (poly) C1 to C25 alkylphenol, (poly) arylalkylphenol, and C1. ~ C25 alkyl naphthol, C1 ~ C25 alkoxylated phosphate (salt), sorbitan ester, polyalkylene glycol, C1 ~ C22 aliphatic amine, C1 ~ C22 aliphatic amide, etc. Ethylene oxide (EO) and / or propylene oxide (PO) Examples thereof include those obtained by addition-condensing 2 to 300 mol of the above, C1 to C25 alkoxylated phosphate (salt), and the like.
Examples of the cationic surfactant include a quaternary ammonium salt or a pyridinium salt, and specifically, a lauryltrimethylammonium salt, a stearyltrimethylammonium salt, a lauryldimethylethylammonium salt, an octadecyldimethylethylammonium salt and the like. , Dimethylbenzyllaurylammonium salt, cetyldimethylbenzylammonium salt, octadecyldimethylbenzylammonium salt, trimethylbenzylammonium salt, triethylbenzylammonium salt, dimethyldiphenylammonium salt, benzyldimethylphenylammonium salt, hexadecylpyridinium salt, laurylpyridinium salt, dodecyl Examples thereof include pyridinium salt, stearylamine acetate, laurylamine acetate and octadecylamine acetate.
Examples of the anionic surfactant include alkyl sulfates, polyoxyethylene alkyl ether sulfates, polyoxyethylene alkyl phenyl ether sulfates, alkyl benzene sulfonates, {(mono, di, tri) alkyl} naphthalene sulfonates, and the like. Can be mentioned. Examples of the amphoteric tenside agent include carboxybetaine, imidazoline betaine, sulfobetaine, aminocarboxylic acid and the like. Sulfation of the condensation product of ethylene oxide and / or propylene oxide with alkylamines or diamines, or sulfonated adducts can also be used.

The nitrogen-based organic compounds mainly composed of the above dyes include dyes or derivatives thereof, amide compounds, thioamide compounds, compounds having an aniline or pyridine ring, various heteromonocyclic compounds, and various condensed heterocyclic compounds. Aminocarboxylic acids and the like.
Specific examples include toluidine dyes such as CI (Color Index) Basic Red 2 and toluidine blue, azo dyes such as CI Direct Yellow 1 and CI Basic Black 2, 3-amino-. Phenazine dyes such as 6-dimethylamino-2-methylphenazine monohydrochloride, imide succinate, imidazolines such as 2'-bis (2-imidazoline), imidazoles, benzoimidazoles, indols, 2-vinylpyridine, Pyridines such as 4-acetylpyridine, 4-mercapto-2-carboxypyridine, 2,2'-bipyridyl, 4,4'-bipyridyl, phenanthroline, quinolins, isoquinolins, aniline, thiourea, dimethylthiourea and the like. Ureas, 3,3', 3 "-nitrilotripropionic acid, diaminomethyleneaminoacetic acid, glycine, N-methylglycine, dimethylglycine, β-alanine, cysteine, glutamic acid, aspartic acid, aminovaleric acid, ornithine, etc. Can be mentioned. Preferred examples include CI Basic Red 2, Janus Green B, toluidine blue, and succinimide.
The brightener is thiourea or a derivative thereof, mercaptans such as 2-mercaptobenzoimidazole and thioglycolic acid, sulfides such as 2,2'-thiodiglycolic acid and diethylsulfide, and 3-mercaptopropane-1-sulfon. Mercaptosulfonic acids such as sodium acid, bis (3-sulfopropyl) disulfide (disodium salt) and the like.
The polymer components include polyvinyl alcohol, carboxymethyl cellulose, polyethylene glycol, polypropylene glycol, stearic acid-polyethylene glycol ester, polyethylene-propylene glycol and the like.
However, in the electrolytic copper plating bath of the present invention, since it is possible that the above-mentioned various additives are related to the warp of the copper film, care must be taken in the selection and concentration of the components.

Among the electrolytic copper plating methods of the present invention, the first method uses the electrolytic copper plating bath to form a low-stress plating film having a warp suppressing function on a thin object to be plated of 500 μm or less.
That is, when a copper film is formed on a thin object to be plated by electroplating, conventionally, the warp stress of the plating film also affects the object to be plated, and the plating film and the object to be plated are integrally warped. There was a problem of impairing the reliability of electronic components such as mounted semiconductor substrates, but in the first electrolytic copper plating method of the present invention, a low-stress plating film having a warp suppressing function is formed to form an object to be plated. It is possible to prevent the warp of the plating film integrated with the above and improve the reliability of electronic parts.
The object to be plated is a flexible or rigid circuit board, a flexible circuit antenna, an RFID tag, an electrolytic foil, a solar cell, a photovoltaic element, a semiconductor wafer, an electromagnetic shield and the like.
The thickness of the object to be plated is preferably 300 μm or less, more preferably 1 to 200 μm.

The second electrolytic copper plating method of the present invention is applied when the adhesion between the electrodeposition film and the object to be plated is low and there is a risk that the electrodeposition film itself peels off from the object to be plated and warps.
That is, the second method is a method of forming a low-stress copper-plated film having a warp suppressing function of 0.1 μm to 5000 μm on the object to be plated by using the electrolytic copper-plated bath of the present invention.
If the plating film is thin, the warping force is weakened and it follows the object to be plated, and peeling is unlikely to occur even if the adhesion is low. Therefore, this second method has a certain degree of film thickness of the copper film formed on the object to be plated. Assuming that it is thick, it is 0.1 μm to 5000 μm, preferably 0.5 to 200 μm, and more preferably 1 to 100 μm.
However, in the above film thickness range, for example, the film thickness of 0.1 μm, which is the lower limit, seems to be thin, but there is a risk of peeling from the object to be plated when the film is warped due to the relationship with the object to be plated.
In the second method, by forming a low-stress plating film having a warp suppressing function, it is possible to prevent the plating film from peeling from the object to be plated due to the warp action and improve the reliability of the electronic component.

The pH of the electrolytic copper plating bath is basically acidic, and is pH 1 to 7, preferably pH 1 to 5, more preferably less than 2.
The plating conditions using the electrolytic copper plating bath of the present invention are not particularly limited, and the bath temperature is 10 to 70 ° C., and the cathode current density is 0.1 to 50 A / dm2, preferably 5 to 40 A / dm2. Further, the anode may be a soluble anode made of copper (alloy) or an insoluble anode made of platinum, carbon or the like.
The film thickness of the film formed by electroplating is generally about 5 to 50 μm.

Hereinafter, examples of the electrolytic copper plating bath of the present invention and examples of electrodeposition stress evaluation tests for measuring the warpage of the copper plating film obtained from the copper bath of the examples over time will be described in sequence.
The "parts" and "%" of the above examples and test examples are basically based on weight.
It should be noted that the present invention is not limited to the following examples and test examples, and it goes without saying that any modification can be made within the scope of the technical idea of the present invention.

<< Example of electrocopper plating bath >>
Of the following Examples 1 to 19, Examples 1 to 8 and Examples 13 to 16 are examples belonging to the present invention 2 (examples of combined use of a sulfur-containing compound and a leveler), and Examples 9 to 12 and 17 to 19 are present. This is an example belonging to Invention 1 (basically a single-use example of a leveler). Although Example 19 contains the sulfur-containing compound (A), the content is as small as 10 mg / L and does not satisfy the requirement of the present invention 2 (containing 50 mg / L or more of the sulfur-containing compound (A)). , Classified as the present invention 1.
In Example 1, the sulfur-containing compound (A) is ZPS, and the leveler (B) of the present invention is an example of the mercaptoimidazole compound of Synthesis Example 1. Examples 2 to 5 are examples in which the sulfur-containing compound (A) of Example 1 is changed, Example 6 is an example in which the leveler (B) of Example 1 is changed to the leveler of Synthesis Example 2, and Example 7 is also synthetic. Example 3 is changed to the leveler of Example 3, and Example 8 is changed to the leveler of Synthesis Example 4, respectively.
Example 9 is based on Example 1 and does not contain the sulfur-containing compound (A), and only the leveler (B) is used alone. Similarly, Example 10 is based on Example 6 and does not contain the sulfur-containing compound. Example 11 is an example based on Example 7 that does not contain a sulfur-containing compound, and Example 12 is an example based on Example 8 that does not contain a sulfur-containing compound. In Examples 9 to 12, the content of the leveler (B) is different from that of each basic example.
Example 13 is an example in which the amount of the sulfur-containing compound (A) is increased based on Example 1 (the type of copper salt is different), and Example 14 is an example in which the amount of the sulfur-containing compound (A) is decreased. Example 15 is an example in which the amount of the leveler (B) of the present invention is increased (the type of copper salt is different) based on Example 1, and Example 16 is an example in which the amount of the leveler (B) is decreased.
Example 17 is an example in which the leveler (B) is reduced based on Example 9, Example 18 is an example in which the leveler (B) is increased, and Example 19 is an example in which the leveler (B) is reduced and the sulfur-containing compound (A). ) Is less than 50 mg / L.

On the other hand, among Comparative Examples 1 to 6, Comparative Example 1 is an example in which a dye (Janus Green B) is used instead of the leveler (B) of the present invention based on Example 1 (example of combined use of a sulfur-containing compound and a leveler). Similarly, Comparative Example 2 is an example using a polymer (PEG) commonly used in an electrolytic copper plating bath, and Comparative Example 3 (a single use example of a leveler) is based on Example 9 (a single use example of a leveler) of the present invention. This is an example in which a dye (phthalocyanine) is used instead of B).
Comparative Example 4 is an example in which a normal electrolytic copper plating bath is used.
Comparative Examples 5 to 6 are examples based on Patent Document 1 described above, and Comparative Example 5 is an example in which an imidazole compound having no mercapto group is used in the leveler based on Example 9 (single use example of the leveler). Comparative Example 6 is an example in which an imidazole-based compound having no mercapto group is used in the leveler based on Example 1 (example of combined use of a sulfur-containing compound and a leveler).

(1) Example 1
An electrolytic copper-plated bath was constructed with the following composition.
Copper oxide (as Cu2 +) 40g / L
Sulfuric acid (98%) 110g / L
Chloride ion 40 mg / L
ZPS 100mg / L
The mercaptoimidazole compound of Synthesis Example 1 10 mg / L
pH <1

(2) Example 2
An electrolytic copper-plated bath was constructed with the following composition.
Copper oxide (as Cu2 +) 40g / L
Sulfuric acid (98%) 110g / L
Chloride ion 40 mg / L
UPS 100mg / L
The mercaptoimidazole compound of Synthesis Example 1 10 mg / L
pH <1

(3) Example 3
An electrolytic copper-plated bath was constructed with the following composition.
Copper sulphate (as Cu2 +) 40g / L
Sulfuric acid (98%) 110g / L
Chloride ion 40 mg / L
SPS 100 mg / L
The mercaptoimidazole compound of Synthesis Example 1 10 mg / L
pH <1

(4) Example 4
An electrolytic copper-plated bath was constructed with the following composition.
Copper sulphate (as Cu2 +) 40g / L
Sulfuric acid (98%) 110g / L
Chloride ion 40 mg / L
MPS 100 mg / L
The mercaptoimidazole compound of Synthesis Example 1 10 mg / L
pH <1

(5) Example 5
An electrolytic copper-plated bath was constructed with the following composition.
Copper sulphate (as Cu2 +) 40g / L
Sulfuric acid (98%) 110g / L
Chloride ion 40 mg / L
DPS 100 mg / L
The mercaptoimidazole compound of Synthesis Example 1 10 mg / L
pH <1

(6) Example 6
An electrolytic copper-plated bath was constructed with the following composition.
Copper sulphate (as Cu2 +) 40g / L
Sulfuric acid (98%) 110g / L
Chloride ion 40 mg / L
ZPS 100mg / L
The mercaptothiadiazole compound of Synthesis Example 4 10 mg / L
pH <1

(7) Example 7
An electrolytic copper-plated bath was constructed with the following composition.
Copper sulphate (as Cu2 +) 40g / L
Sulfuric acid (98%) 110g / L
Chloride ion 40 mg / L
ZPS 100mg / L
The mercaptotetrazole compound of Synthesis Example 2 10 mg / L
pH <1

(8) Example 8
An electrolytic copper-plated bath was constructed with the following composition.
Copper sulphate (as Cu2 +) 40g / L
Sulfuric acid (98%) 110g / L
Chloride ion 40 mg / L
ZPS 100mg / L
The mercaptobenzothiazole compound of Synthesis Example 3 10 mg / L
pH <1

(9) Example 9
An electrolytic copper-plated bath was constructed with the following composition.
Copper sulphate (as Cu2 +) 40g / L
Sulfuric acid (98%) 110g / L
Chloride ion 40 mg / L
The mercaptoimidazole compound of Synthesis Example 1 50 mg / L
pH <1

(10) Example 10
An electrolytic copper-plated bath was constructed with the following composition.
Copper sulphate (as Cu2 +) 40g / L
Sulfuric acid (98%) 110g / L
Chloride ion 40 mg / L
The mercaptothiadiazole compound of Synthesis Example 4 50 mg / L
pH <1

(11) Example 11
An electrolytic copper-plated bath was constructed with the following composition.
Copper sulphate (as Cu2 +) 40g / L
Sulfuric acid (98%) 110g / L
Chloride ion 40 mg / L
The mercaptotetrazole compound of Synthesis Example 2 50 mg / L
pH <1

(12) Example 12
An electrolytic copper-plated bath was constructed with the following composition.
Copper sulphate (as Cu2 +) 40g / L
Sulfuric acid (98%) 110g / L
Chloride ion 40 mg / L
The mercaptobenzothiazole compound of Synthesis Example 3 50 mg / L
pH <1

(13) Example 13
An electrolytic copper-plated bath was constructed with the following composition.
Copper sulphate (as Cu2 +) 40g / L
Sulfuric acid (98%) 110g / L
Chloride ion 40 mg / L
ZPS 1000mg / L
The mercaptoimidazole compound of Synthesis Example 1 10 mg / L
pH <1

(14) Example 14
An electrolytic copper-plated bath was constructed with the following composition.
Copper sulphate (as Cu2 +) 40g / L
Sulfuric acid (98%) 110g / L
Chloride ion 40 mg / L
ZPS 50mg / L
The mercaptoimidazole compound of Synthesis Example 1 10 mg / L
pH <1

(15) Example 15
An electrolytic copper-plated bath was constructed with the following composition.
Copper sulphate (as Cu2 +) 40g / L
Sulfuric acid (98%) 110g / L
Chloride ion 40 mg / L
ZPS 100mg / L
The mercaptoimidazole compound of Synthesis Example 1 50 mg / L
pH <1

(16) Example 16
An electrolytic copper-plated bath was constructed with the following composition.
Copper sulphate (as Cu2 +) 40g / L
Sulfuric acid (98%) 110g / L
Chloride ion 40 mg / L
ZPS 100mg / L
The mercaptoimidazole compound of Synthesis Example 1 1 mg / L
pH <1

(17) Example 17
An electrolytic copper-plated bath was constructed with the following composition.
Copper sulphate (as Cu2 +) 40g / L
Sulfuric acid (98%) 110g / L
Chloride ion 40 mg / L
The mercaptoimidazole compound of Synthesis Example 1 1 mg / L
pH <1

(18) Example 18
An electrolytic copper-plated bath was constructed with the following composition.
Copper sulphate (as Cu2 +) 30 g / L
Sulfuric acid (98%) 110g / L
Chloride ion 40 mg / L
The mercaptoimidazole compound of Synthesis Example 1 50 mg / L
pH <1

(19) Example 19
An electrolytic copper-plated bath was constructed with the following composition.
Copper sulphate (as Cu2 +) 30 g / L
Sulfuric acid (98%) 90g / L
Chloride ion 40 mg / L
ZPS 10mg / L
The mercaptoimidazole compound of Synthesis Example 1 50 mg / L
pH <1

(20) Comparative Example 1
An electrolytic copper-plated bath was constructed with the following composition.
Copper sulphate (as Cu2 +) 40g / L
Sulfuric acid (98%) 110g / L
Chloride ion 40 mg / L
ZPS 100mg / L
Janus Green B 10mg / L
pH <1

(21) Comparative Example 2
An electrolytic copper-plated bath was constructed with the following composition.
Copper sulphate (as Cu2 +) 40g / L
Sulfuric acid (98%) 110g / L
Chloride ion 40 mg / L
ZPS 100mg / L
Polyethylene glycol (average molecular weight) 500 mg / L
pH <1

(22) Comparative Example 3
An electrolytic copper-plated bath was constructed with the following composition.
Copper sulphate (as Cu2 +) 40g / L
Sulfuric acid (98%) 110g / L
Chloride ion 40 mg / L
Phthalocyanine 10 mg / L
pH <1

(24) Comparative Example 4
An electrolytic copper-plated bath was constructed with the following composition.
Copper sulphate (as Cu2 +) 40g / L
Sulfuric acid (98%) 110g / L
Chloride ion 40 mg / L
ZPS 100mg / L
Janus Green B 1mg / L
Polyethylene glycol (average molecular weight 20000) 500 mg / L
pH <1

(25) Comparative Example 5
An electrolytic copper-plated bath was constructed with the following composition.
Copper sulphate (as Cu2 +) 40g / L
Sulfuric acid (98%) 110g / L
Chloride ion 40 mg / L
Imidazole-based compound having no mercapto group 10 mg / L
pH <1
In Synthesis Example 1, an imidazole-based compound having a mercapto group classified into leveler L1 of the present invention was synthesized, but the imidazole-based compound having no mercapto group is 2-mercapto based on this Synthesis Example 1. Synthesis was performed using 0.5 mol of imidazole instead of 0.5 mol of -1H-methylimidazole.

(26) Comparative Example 6
An electrolytic copper-plated bath was constructed with the following composition.
Copper sulphate (as Cu2 +) 40g / L
Sulfuric acid (98%) 110g / L
Chloride ion 40 mg / L
ZPS 100mg / L
Imidazole-based compound having no mercapto group 10 mg / L
pH <1
The imidazole-based compound having no mercapto group is the same as that used in Comparative Example 5.

<< Example of evaluation test of electrodeposition stress >>
Therefore, using each of the copper plating baths of Examples 1 to 19 and Comparative Examples 1 to 6, electroplating was performed under the conditions of cathode current density: 10 A / dm2, bath temperature: 30 ° C., and plating time: 10 minutes. A test strip electrodeposition stress test was carried out on the obtained electrodeposition film immediately after plating.
As mentioned above, in normal copper plating, the stress immediately after plating is tensile stress (+ MPa), and the tensile stress (+ MPa) continuously works with the passage of time (after 1 to 2 days), so plating. The warp to the surface side becomes stronger (see FIG. 1A), and even if the stress immediately after plating is 0 MPa, it also warps to the plated surface side with the passage of time, but it takes 1 to 2 days. After that, it becomes a steady state and does not warp any more.

Table A below shows the test results.
In this case, when the stress is + MPa, it means tensile stress, and −MPa means compressive stress.
[Table A] Stress (MPa) Stress (MPa)
Example 1-10 Comparative Example 1 +10
Example 2-9 Comparative Example 2 +8
Example 3-10 Comparative Example 3 +15
Example 4-8 Comparative Example 4 +20
Example 5-8 Comparative Example 5 + 11
Example 6-12 Comparative Example 6 +9
Examples 7-11
Example 8-10
Example 9-8
Example 10-10
Example 11-8
Example 12-8
Example 13-5
Example 14-5
Example 15-7
Examples 16-11
Examples 17-13
Example 18-8
Example 19-9

<< Comprehensive evaluation based on the above test results >>
According to Table A above, the sulfur-containing compound (A) of the present invention is contained, and instead of the leveler (B) of the present invention, a nitrogen-based dye (Janus Green) commonly used in an electrolytic copper plating bath is contained. Comparative Example 1 showed a tensile stress of +10 MPa, and Comparative Example 2 containing a polymer (PEG) commonly used in an electrolytic copper plating bath showed a tensile stress of +8 MPa.
Further, in Comparative Example 3 which does not contain the sulfur-containing compound (A) of the present invention and contains a nitrogen-based dye (phthalocyanine) which is widely used in electrolytic copper plating baths instead of the leveler (B) of the present invention, the tension is +15 MPa. Showed stress.
Next, in Comparative Example 5, which does not contain the sulfur-containing compound (A) of the present invention and contains an imidazole-based compound having no mercapto group instead of the leveler (B) of the present invention, +11 MPa, the sulfur-containing compound (A) of the present invention. ), And instead of the leveler (B) of the present invention, Comparative Example 6 containing an imidazole-based compound having no mercapto group showed each tensile stress of +9 MPa.
In Comparative Example 4 using a general electrolytic copper plating bath, the tensile stress was also exhibited, and the value was the largest at +20 MPa.

In short, Comparative Examples 1 to 3 and Comparative Example 6 are examples to be compared with the present invention 2 in that the sulfur-containing compound (A) of the present invention and a compound substituting for the leveler of the present invention are included, and Comparative Example 5 is an example to be compared with the present invention 2. It is inversely proportional to the present invention 1 in that it does not contain the sulfur-containing compound (A) of the present invention and contains a substitute compound for the leveler of the present invention. ) Acts, and it can be seen that the plating film warps in a concave shape (that is, a convex shape toward the lower base material side) with the surface side facing up (see FIG. 1A).
On the other hand, in Examples 1 to 19 containing the levelers (L1, L2) of the present invention or further containing the sulfur-containing compound (A) of the present invention in a predetermined amount, all the plating films were -13 to -5 MPa. It can be seen that the compressive stress of (see FIG. 1B) acts.
As a result, even if the tensile stress acts over time and the copper plating film tries to warp, this compressive stress (-MPa) acts against the tensile stress (+ MPa) to bring the stress closer to 0 MPa, so there is almost no warpage. A copper film can be formed over time.
Therefore, in electrolytic copper plating, in order to prevent the electrodeposition film from warping, which is a subject of the present invention, it is a condition that a compressive stress (−MPa) is obtained immediately after plating, and the copper plating bath of the present invention can be used. It was confirmed that the obtained electrodeposition film satisfies the above conditions.

In particular, when Comparative Examples 5 to 6 (based examples of Patent Document 1 above) are weighed in comparison with Examples 1 to 19, when the product obtained by reacting the heterocyclic nitrogen compound is used as a leveler for electrolytic copper plating, it is complex. An unexpectedly remarkable result was found that the force acting on the obtained copper film is divided into the opposite directions of the tensile stress and the compressive stress depending on the presence or absence of the mercapto group bond to the ring compound.
That is, it is important that the presence or absence of a mercapto group bond to the heterocyclic nitrogen compound is greatly related to the suppression of the successive warpage of the copper film, and the bond of the mercapto group to the heterocyclic compound is essential for the suppression of the warp. The causal relationship was supported.

Next, Examples 1 to 19 will be examined in detail.
Examples 1 to 8 belong to the electrolytic copper plating bath of the present invention 2 in which the sulfur-containing compound (A) and the leveler (B) are used in combination. Among them, Examples 1 to 5 are the leveler (= mercaptoimidazole type) of the present invention. Compound) is fixed and the sulfur-containing compound (A) is changed to various compounds of ZPS, UPS, SPS, MPS, and DPS, and Examples 1 and 6 to 8 are the sulfur-containing compounds of the present invention. This is an example in which (= ZPS) is fixed and the leveler (B) is changed to various compounds such as a mercaptoimidazole compound, a mercaptothiadiazole compound, and a mercaptotetrazole compound. Was able to be granted. Comparing the levelers L1 and L2, it is -12 MPa in Example 6 using the leveler L2 (Synthesis Example 4), and -11 to 11 in Examples 1 to 5 and 7 to 8 using the leveler L1 (Synthesis Examples 1 to 3). It showed a compressive stress of -8 MPa.
Examples 9 to 12 belong to the electrolytic copper plating bath of the present invention 1 in which the leveler (B) is used alone, and the leveler is changed to various compounds such as a mercaptoimidazole compound, a mercaptothiadiazole compound, and a mercaptotetrazole compound. However, when comparing the levelers L1 and L2, it is -10 MPa in Example 10 using the leveler L2 (Synthesis Example 4) and -8 MPa in Examples 9 and 11-12 using the leveler L1 (Synthesis Examples 1 to 3). The compressive stress of was shown.

Examples 13 to 16 belong to the (combination type) electrolytic copper plating bath of the present invention 2, and based on Example 1, the amount of the sulfur-containing compound (A) of the present invention is increased or decreased, and the leveler (B) of the present invention is used. In Examples 13 to 14, the amount of the sulfur-containing compound (A) was increased or decreased from Example 1, and the compressive stress did not change. Therefore, it can be determined that the leveler (B) is an appropriate amount even if it is a small amount. Further, since the compressive stress is -7 MPa in Example 15 in which the leveler (B) is increased from Example 1 and the compressive stress is -11 MPa in Example 16 in which the leveler (B) is decreased, the leveler (B) is contained in the combined plating bath. It is presumed that the amount is sufficient in a small range.
Examples 17 to 18 belong to the (single-use type) electrolytic copper plating bath of the present invention 1, and are examples in which the leveler (B) of the present invention is increased or decreased based on Example 1, and the leveler (B) is carried out. In Example 17 in which the amount was reduced from Example 1, the compressive stress was -13 MPa, and in Example 18 in which the amount was increased, the compressive stress was -8 MPa. It is speculated. Further, Example 19 contains a sulfur-containing compound (A) and a leveler (B), but the content (10 mg / L) of the sulfur-containing compound (A) is less than the specified amount of the present invention 2, so that the present invention 1 It belonged to the electrolytic copper plating bath, and the compressive stress was -9 MPa.
In particular, when Examples 16 to 17 are weighed in comparison with Example 1, the leveler content in Examples 16 to 17 is 1 mg / L, which is only 1/10 of that in Example 1, but the absolute value of compressive stress. In light of the fact that it is increased from Example 1 (-10 MPa → -11, -13 MPa), it is judged that the content of the leveler (B) is small or small in terms of suppressing the warp of the plating film. can. Further, in Example 19, the contents of the copper salt and the acid were reduced from those of Example 1, but the absolute value of the compressive stress did not change much.

FIG. 1A is a schematic view of a copper-plated film warped by a tensile stress, and FIG. 1B is a schematic view of a copper-plated film when a compressive stress is applied.

Claims (6)

In an electrocopper plating bath containing a soluble copper salt and an acid or a salt thereof,
Contains compound (B) selected from at least one of the following levelers (L1) and levelers (L2):
The leveler (L1) is a reaction product of (a) a heterocyclic nitrogen compound having a mercapto group and (b) an organic halogen compound.
The leveler (L2) is a reaction product of (a) a heterocyclic nitrogen compound having a mercapto group, (b) an organic halogen compound, and (c) a polyalkylene glycol having a reactive group at one end or both ends. hand,
The above component (a) includes an imidazole ring, a pyridine ring, a purine ring, a benzoimidazole ring, a benzothiazole ring, an imidazoline ring, a triazole ring, a tetrazole ring, a thiazizol ring, a pyrimidine ring, a pyrazine ring, a quinoline ring, a benzoxazole ring, and a morpholin. It is a nitrogen compound having a heterocycle selected from the group consisting of a ring and a pyrrol ring (however, in the case of leveler (L1), the above heterocycle excluding the pyridine ring).
The component (b) has at least one halogen in the alkylene chain, or has a functional group selected from the group consisting of an amino group, an ether group, a hydroxyl group, and a sulfonic acid group together with the halogen. An electrolytic copper-plated bath for forming a low-stress film, which is characterized by being an organic halogen compound. In an electrocopper plating bath containing a soluble copper salt and an acid or a salt thereof,
(A) Contains 50 to 10000 mg / L of a sulfur-containing compound selected from sulfides, mercaptans, thiopropylsulfonic acids, and dithiocarbamic acids, and at the same time.
(B) A leveler (L1) which is a reaction product of a heterocyclic nitrogen compound (a) having a mercapto group and an organic halogen compound (b), a heterocyclic nitrogen compound (a) having a mercapto group, and an organic halogen. It contains at least one of levelers (L2), which is a reaction product of compound (b) and a polyalkylene glycol (c) having a reactive group at one end or both ends.
The above component (a) includes an imidazole ring, a pyridine ring, a purine ring, a benzoimidazole ring, a benzothiazole ring, an imidazoline ring, a triazole ring, a tetrazole ring, a thiazizol ring, a pyrimidine ring, a pyrazine ring, a quinoline ring, a benzoxazole ring, and a morpholin. It is a nitrogen compound having a heterocycle selected from the group consisting of a ring and a pyrrol ring (however, in the case of leveler (L1), the above heterocycle excluding the pyridine ring).
The component (b) has at least one halogen in the alkylene chain, or has a functional group selected from the group consisting of an amino group, an ether group, a hydroxyl group, and a sulfonic acid group together with the halogen. An electrolytic copper-plated bath for forming a low-stress film, which is characterized by being an organic halogen compound. The low stress according to claim 1 or 2, wherein the reactive group contained in the polyalkylene glycol (c) is selected from the group consisting of a halogen group, a haloformyl group, a mesylate group, and a tosylate group. Electrocopper plating bath for film formation. " Among the sulfur-containing compound (A), the sulfides are bis (3-sulfopropyl) disulfide (SPS), bis (2-sulfopropyl) disulfide, bis (3-sul-2-hydroxypropyl) disulfide, and bis (4). -Selected from sulfopropyl) disulfides, bis (p-sulfophenyl) disulfides and salts thereof,
Similarly, mercaptans are selected from mercaptomethanesulfonic acid, mercaptoethanesulfonic acid, mercaptopropanesulfonic acid (MPS) and salts thereof.
Thiopropyl sulfonic acids include 3- (benzothiazolyl-2-thio) propane sulfonic acid (ZPS), 3-[(aminoiminomethyl) thio] -1-propane sulfonic acid (UPS), O-ethyl-diethylcarbonate-S. -(3-Sulfonpropyl) -esters and selected from these salts,
Dithiocarbamic acids are selected from N, N-dimethyl-dithiocarbamylpropanesulfonic acid (DPS), N, N-dimethyl-dithiocarbamic acid- (3-sulfopropyl) -esters and salts thereof. The electrolytic copper plating bath for forming a low stress film according to claim 2 or 3, which is characterized by this. Using the electrolytic copper plating bath according to any one of claims 1 to 4, a low-stress plating film having a warp suppressing function is formed on a thin object to be plated of 500 μm or less, and integrated with the object to be plated. An electrolytic copper plating method characterized by preventing the warp of the plated film. Using the electrolytic copper plating bath according to any one of claims 1 to 4, a low-stress copper plating film having a warp suppressing function of 0.1 μm to 5000 μm is formed on the object to be plated, and the object is plated by the warp action. An electrolytic copper plating method characterized by preventing the film from peeling off from the object to be plated.

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