JP2018178222A - Copper electroplating bath for forming low stress film and copper electroplating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a copper plating solution capable of preventing warpage of a plating film over time in electrolytic copper plating.SOLUTION: There is provided a copper plating solution capable of obtaining a copper film that has a compressive stress exerted onto a plating film obtained from the copper bath so as to resist a tensile stress exerted onto the film over time, and therefore, keeping the film virtually free from warpage over time, by including in the copper plating solution containing a soluble copper salt and an acid: a leveler (B) comprising (a) a heterocyclic nitrogen compound having a mercapto group and (b) an organohalogen compound, or further comprising (c) a product obtained by reacting a predetermined polyalkylene glycol; or further 50-10000 mg/L of a predetermined sulfur-containing compound selected from a sulfide, a mercaptan or the like.SELECTED DRAWING: None

Description

  The present invention provides an electrolytic copper plating bath for forming a low stress film and an electrolytic copper plating method, which can prevent warpage of a copper film after plating.

In ordinary copper electroplating, tensile stress is applied to the inside of the film after plating, and as time passes (eg, after 1 to 2 days), the copper film warps concavely on the surface side of the plating with respect to the surface of the substrate There is a phenomenon called. That is, while tensile stress works mutually inside the plated film on the base material such as bumps and leads, the surface side facing the outside of the film shrinks in the length direction, while the base material of the film Since the length of the contact surface side does not change, a phenomenon that the plating film warps concavely with its surface side up (in other words, warps toward the lower substrate) is observed (See Figure 1A).
Warpage proceeds with time between these 1 and 2 days, then shifts to a steady state, and does not warp further, but, for example, a wafer of 200 μm or less or a film of polyimide resin, epoxy resin, polycarbonate resin, etc. When copper is plated on a thin base like this, the entire base on which the film is formed warps over time, and when various chip components such as ICs are mounted on the base via the plated film, bumps and the like There is a problem of causing a joint failure such as breakage of the joint portion and impairing the reliability of the electronic component.
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 peels off the object to be plated, and also when mounting various chip components, the electronic components It will impair the reliability.

Generally, in copper electroplating, levelers, brighteners, polymers, chlorides and the like are added in order to promote the uniformity, smoothness and gloss of the electrodeposition film.
Therefore, it is conceivable that these components act in combination to affect the warpage of the copper film, but the prior art related to electrolytic copper plating is as follows.
(1) Patent Document 1
Heterocyclic nitrogen compounds having an imidazole ring, tetrazole ring, pyridine ring, benzothiazole ring, etc., and polyhalogen compounds (2,4-bis (chloromethyl) -1,3,5-trimethylbenzene, 1,2-dichloroethane And the like, and a product obtained by reacting a polyepoxide compound (such as 1,4-butanediol diglycidyl ether) with an electrolytic copper plating solution (claims 1-2, 6, [0029] to [0033] And, by containing the above reaction product, it is possible to improve the throwing power and smoothness of the copper film obtained from the plating solution ([0007]).
In this case, among the above-mentioned heterocyclic nitrogen compounds, there is no mercapto group in the substituent R ₁ of the 5-membered ring compound (claim 3), and a 6-membered ring compound (claim 5), a fused heterocyclic nitrogen compound There is no substituent in (claim 4).
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 (see [0056], Table 1).

(2) Patent Document 2
Polyalkene oxide compound having a number average molecular weight of not less than 100 to 2,000,000 and having a functional group such as a sulfonic acid group, an amino group, a mercapto group, a phenyl group, a phenyl oxide group, a phenyl azophenoxy group or a halogen at the end The copper electroplating solution contains Cu as an additive (claims 1 to 3, [0032], [0037] to [0039]), and the above additive has a molecular weight of 100 or more, and therefore, the additive is contained. Even if the amount of chlorine in the plating solution is small, stable and good copper plating can be performed, and it is not necessary to use an additive such as bis (3-sulfopropyl) disulfide (SPS) or Janus green in combination ([0033]) .
As the polyalkene oxide compound, for example, dichloropolyethylene glycol belonging to an organic halide is disclosed ([0037] to [0038]).

(3) Patent Document 3
A copper filling method that can suppress the occurrence of voids and improve plating defects by applying to a substrate a copper plating bath containing a leveler compound consisting of a quaternary dipyridyl salt compound that is a reaction product of a dipyridyl compound and an alkylating agent (Claims 1 to 42, paragraphs 22 to 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, 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, chlorine ion, an electrodeposition accelerator, an electrodeposition inhibitor, and a pyridine derivative in which pyridine rings are linked via an ethylene group are alkylated with 2-chloroethyl ether. A copper plating bath is disclosed which contains a stabilized leveler compound (paragraph 124). In this case, the leveler compound is a product obtained by reacting a heterocyclic nitrogen compound (pyridine derivative) and an organic chlorine compound (2-chloroethyl ether).

(4) Patent Document 4
Inhibitors such as polyoxyalkylene glycol, carboxymethylcellulose, polyethylene glycol, polypropylene glycol, polyvinyl alcohol SPS, mercaptopropane sulfonic acid (MPS), N, N-dimethyl-dithiocarbamyl propane sulfonic acid (DPS), 3- [3 The method is a method of forming a copper film with low internal stress by electroplating with a copper plating solution containing an electrodeposition promoter such as (aminoiminomethyl) thio] -1-propanesulfonic acid (UPS). ~ 6, Table 1).
In Example 1, a copper plating bath (baths 2 to 4) containing MPS (salt), SPS (salt), polyoxyalkylene glycol and polyethylene glycol is described, and the total concentration of MPS (salt) and SPS (salt) Is 5-9 ppm.

JP, 2015-227327, A JP 2008-223082 A Japanese Patent Application Publication No. 2012-510179 JP, 2013-060660, A

In the electrolytic copper plating solution shown in Patent Documents 1 to 4 or the electrolytic copper plating method including the pretreatment, as described above, the obtained copper electrodeposition film acts as a tensile stress with the passage of time. In this case, it is not easy to ensure the reliability of loading of various chip components on the substrate because the semiconductor chip is warped upward toward the plating surface (see FIG. 1A).
For example, in the example ([0056] of Patent Document 1), imidazole (heterocyclic compound), 2,4-bis (chloromethyl) -1,3,5-trimethylbenzene (polyhalogen compound) and And compounds obtained by reacting 1,4-butanediol diglycidyl ether (polyepoxide compound), but even if the compound is added as a leveler to an electrolytic copper plating solution, the obtained copper film warps with time. Is not sufficient at the point which suppresses (refer to the below-mentioned comparative example).
An object of the present invention is to effectively prevent the plating film from warping over time during copper plating.

The present inventors focused attention on the products described in Patent Documents 1 to 4 above, in particular, heterocyclic nitrogen compounds, organic halogen compounds, etc., which are reactants for obtaining the products, and modified these. With respect to the product obtained by reacting the compound, when the product was added to the copper electroplating solution, the relationship between various products and the warpage of the obtained copper film was earnestly studied.
As a result, a compound (1) in which mercapto is introduced into a heterocyclic nitrogen compound is reacted with an organic halogen compound (2) or a polyalkylene glycol (3) having a reactive group is further reacted. When the product is added as a leveler to the copper electroplating solution, the unexpected effect is confirmed that the warpage of the obtained copper film can be effectively prevented as compared with the compound disclosed in Patent Document 1 above. did.
In addition, sulfur-containing compounds such as mercaptopropane sulfonic acid (MPS) or a salt thereof, bis (3-sulfopropyl) disulfide (SPS) and the like are used as a compound that performs an electrodeposition promoting function in electrolytic copper plating, It has been found that the warpage preventing effect of a copper film can be further enhanced by using this sulfur-containing compound in combination with the above-mentioned leveler in an electrodeposited copper plating bath at a predetermined concentration or more to complete the present invention.

That is, the present invention 1 relates to an electrolytic copper plating bath containing a soluble copper salt and an acid or a salt thereof,
A 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 or both ends. It is an electrolytic copper plating bath for low stress film formation characterized by the above.

Invention 2 relates to an electrolytic copper plating bath containing an available copper salt and an acid or a salt thereof,
(A) 50 to 10000 mg / L of a sulfur-containing compound selected from sulfides, mercaptans, thiopropyl sulfonic acids and dithiocarbamic acids,
(B) 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 An electricity for forming a low stress film, comprising at least one of a leveler (L2) which is a reaction product of a compound (b) and a polyalkylene glycol (c) having a reactive group at one end or both ends. It is a copper plating bath.

In the invention 3 according to the invention 1 or 2 above, the heterocycle forming the heterocycle nitrogen compound (a) is a dioxane ring, 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 thiadiazole ring, a pyrimidine ring, a pyrazine ring, a quinoline ring, a benzoxazole ring, a morpholine ring, and a pyrrole ring;
The organic halogen compound (b) is a compound having at least one or more halogens in the alkylene chain, or further having a functional group selected from the group consisting of an amino group, an ether group, a hydroxyl group and a sulfonic acid group. Yes,
The reactive group possessed by the polyalkylene glycol (c) is selected from the group consisting of a halogen group, a haloformyl group, a mesylate group and a tosylate group, and the copper electroplating bath for forming a low stress film is characterized in that It is.

Invention 4 of the Invention 2 or 3 includes sulfides of the sulfur-containing compound (A) as bis (3-sulfopropyl) disulfide (SPS), bis (2-sulfopropyl) disulfide, bis (3) -Sul-2-hydroxypropyl) disulfide, bis (4-sulfopropyl) disulfide, bis (p-sulfophenyl) disulfide and salts thereof,
Similarly, mercaptans are selected from mercaptomethanesulfonic acid, mercaptoethanesulfonic acid, mercaptopropanesulfonic acid (MPS) and salts thereof,
Thiopropylsulfonic acids are 3- (benzothiazolyl-2-thio) propanesulfonic acid (ZPS), 3-[(aminoiminomethyl) thio] -1-propanesulfonic acid (UPS), O-ethyl-diethyl carbonate-S -(3-sulfopropyl) -ester and salts thereof;
The dithiocarbamic acids are selected from N, N-dimethyl-dithiocarbamylpropane sulfonic acid (DPS), N, N-dimethyl-dithiocarbamic acid- (3-sulfopropyl) -ester and salts thereof It is an electrolytic copper plating bath for forming a low stress film, which is characterized.

  Invention 5 uses the copper electroplating bath according to any of Inventions 1 to 4 above to form a low stress plating film having a warp suppressing function on a thin plating object of 500 μm or less, It is an electrolytic copper plating method characterized by preventing the curvature of the integrated plating film.

  Invention 6 uses the copper electroplating bath of any of Inventions 1 to 4 above to form a low stress copper plating film having a warp suppressing function of 0.1 μm to 5000 μm on a material to be plated, and produces a warping effect. And preventing the plating film from peeling off the object to be plated.

In the electrolytic copper plating bath of the present invention, a heterocyclic nitrogen compound having a mercapto group is selected as a reactant, and a leveler L1 consisting of a product obtained by reacting an organic halogen compound with this is further reacted with a polyepoxide compound. Since the leveler L2 is contained, the low stress property can be imparted to the obtained copper film, and the warpage of the film with time can be effectively prevented.
In addition to the above leveler L1 and / or leveler L2 in the copper electroplating bath, when a specific sulfur-containing compound (A) coexists at a predetermined concentration or more, the temporal warping of the copper film is more effectively prevented. it can. When an electrodeposition accelerator is contained in an electrolytic copper plating bath, usually, a very small amount of a sulfur-containing compound such as SPS (bis (3-sulfopropyl) disulfide) is compounded in a proportion of about 3 to 10 mg / L. It is also characterized by blending more in the range of 50 to 10000 mg / L than usual.
Furthermore, in the plating bath of the present invention, a copper film having a warp preventing function can be obtained even if a polymer component generally used in a general copper electroplating bath is omitted.
That is, since the internal stress of the plating film formed by 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 stress (see FIG. 1A) is used for warpage, this compressive stress resists tensile stress and approaches 0 MPa, so it is possible to form a film substantially free of warping over time.
Therefore, even if electroplating is performed on a thin object to be plated using the copper plating bath of the present invention, or on an object to be plated having low adhesion, both of the copper films after electroplating can be used. Warpage can be prevented smoothly, thereby improving the reliability of the electronic component.
For this reason, as a use of the copper plating bath of this invention, it is suitable for formation of a fine wiring circuit which requires low stress, via filling, etc.

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, or a benzothiazole ring, a polyhalogen compound, and a polyepoxide compound. However, the above-mentioned heterocyclic nitrogen compound does not have a mercapto group (claims 1 to 2, 6, [0029] to [0033]).
In this case, as apparent from the results of evaluation tests described later, an electrolytic copper plating bath containing the leveler of the present invention, which is a product obtained by reacting a heterocyclic nitrogen compound having a mercapto group and an organic halogen compound, According to Patent Document 1, the plating bath according to the present invention has a function of suppressing the warping of the electrodeposition film obtained from the plating bath, when compared with the copper electroplating bath using a heterocyclic nitrogen compound having no mercapto group according to Patent Document 1. Show a remarkable advantage over the bath according to Patent Document 1.
Even when the sulfur-containing compound of the present invention is allowed to coexist 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 significant advantage.

  In the present invention, first, a product obtained by selecting a heterocyclic nitrogen compound having a mercapto group as a reactant, reacting this with an organic halogen compound, or further reacting a polyalkylene glycol having a reactive group (Electrolytic copper plating bath containing (Leveler L1, L2) (Invention 1)) Second, a specific sulfur-containing compound (A) is added to the leveler (B) selected from the above products L1 and L2. It is an electrolytic copper plating bath (invention 2 of the present invention) coexisting at a predetermined concentration or more, and thirdly, a method of electroplating copper on a predetermined thin object using the copper plating bath (invention 5 of the present invention) Fourth, there is a method (electro-conductive copper according to the sixth aspect of the invention) of electroplating copper on 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 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 can be used as long as it is a soluble salt that generates copper ions in an aqueous solution, and there is no particular limitation, and poorly soluble salts are not excluded. Specific examples thereof include copper sulfate, copper oxide, copper hydroxide, copper chloride, copper nitrate, copper carbonate, copper acetate, copper oxalate and the like, with copper oxide, copper nitrate, copper oxide and copper hydroxide being preferred. The content of the soluble copper salt in the plating bath is 10 to 70 g / L, preferably 30 to 60 g / L, in terms of divalent copper ions.
Further, as a base acid of the copper electroplating bath, an acid generally used in a common copper plating bath such as sulfuric acid, hydrochloric acid, oxalic acid, acetic acid can be used, and organic acids such as organic sulfonic acid and oxycarboxylic acid are used. It can also be used.
Salts of base acids are alkali metal salts, alkaline earth metal salts, ammonium salts, amine salts and the like.
Content with respect to the plating bath of an acid or its salt is 10-300 g / L, Preferably it is 30-150 g / L.

The above compound (B) is selected from a specific leveler (L1) and a leveler (L2), and either of the leveler (L1) and the leveler (L2) may be used alone, or the leveler (L1) and the leveler (L2) You may use in combination.
The leveler (L1) is a product obtained by reacting (a) a heterocyclic nitrogen compound having a mercapto group with (b) an organic halogen compound.
As for the heterocyclic nitrogen compound (a) having a mercapto group which is one of the reaction products of the leveler (L1), the above-mentioned heterocyclic ring is a dioxane ring, an imidazole ring, a pyridine ring, a purine ring, a benzimidazole ring, a benzothiazole ring, an imidazoline ring Selected from the group consisting of triazole ring, tetrazole ring, thiadiazole ring, pyrimidine ring, pyrazine ring, quinoline ring, benzoxazole ring, morpholine ring, and pyrrole ring, preferably imidazole ring, pyridine ring, benzothiazole ring, tetrazole ring, Such as thiadiazole ring.
Examples of the heterocyclic nitrogen compound (a) include 4-mercaptoquinoline-2-carboxylic acid, 2-mercapto-2H-pyrrole, mercaptopurine, 2-mercaptopyridine, 4-mercaptopyridine and 5-mercapto-1-methyl tetrazole. 1- (2-Dimethylaminoethyl) -5-mercaptotetrazole, 2-mercaptobenzimidazole, 2-mercapto-1H-imidazole, 2-mercapto-1-methylimidazole, 3-mercapto-1,2,4-triazole , 2-mercaptobenzothiazole, 4-acetamido-7-mercapto-2,1,3-benzoxadiazole, 2-mercaptoimidazoline (ethylenethiourea), 2,5-dimercapto-1,3,4-thiadiazole (bismuthol) ), 2- (2-mercaptoethyl) -1,3-geo Sun, 4-amino-6-hydroxy-2-mercaptopyrimidine hydrate, 2-quinolinethiol, 3-mercaptoquinoline, 8-quinolinethiol, 2-amino-5-mercapto-1,3,4-thiadiazole, 5 And -methyl-1,3,4-thiadiazole-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 (ethylene thiourea), 2,5- Dimercapto-1,3,4-thiadiazole (bismuthol), 5-methyl-1,3,4-thiadiazole-2-thiol and the like.

The organic halogen compound (b) which is the other reaction product of the leveler (L1) has at least one or more halogens in the alkylene chain, or, together with the halogen, an amino group, an ether group, a hydroxyl group, a sulfonic acid It is a compound having a functional group selected from the group consisting of groups.
Examples of the organic halogen compound (b) include chloroethyl ether, chloroethanol, 1,2-dichloroethane, 1,5-dichloropentane, 1,6-dichlorohexane, 1,8-dichlorooctane, bis (bromoethyl) ether, 1 3,5-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-chloroethane sulfonate, 2,2'-dichloro Ethyl ether, 2-bis (2-chloroethoxy) ethane and the like can be mentioned.
Preferred organic halogen compounds (b) are 2-chloroethylamine, 2- (dimethylamino) ethyl chloride, 3-chloro-1-propanol, bis (2-chloroethyl) amine, 3-chloropropane, 2-chloroethyl methyl sulfide, etc. It is.

The leveler (L2) is a product obtained by reacting (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 or both ends. It is.
The components (a) and (b) which are the reactants of the leveler (L2) are the same as the leveler (L1).
With respect to polyalkylene glycol (c) having a reactive group, which is the third reactant of leveler (L2), polyalkylene glycol is a homopolymer or copolymer of C2 to C4 alkylene glycol, polyethylene glycol (PEG), polypropylene Glycol (PPG), or a copolymer of ethylene glycol and propylene glycol is preferred, and more preferred is PEG.
The reactive group at 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 proper range, the low stress property of the obtained copper film is insufficient and the anti-warpage function is deteriorated, and conversely, the anti-warpage function does not differ much even if it exceeds the proper range, but the copper film There is a risk of lowering the physical properties of
The content of the leveler L2 with respect to the copper plating bath is the same as in the case of the leveler L1, and the content in the case of using the levelers L1 and L2 in combination is also the same as in the case of using each leveler.

Therefore, first, Synthesis Examples 1 to 3 classified into the leveler L1 which is a product of the reaction of the component (a) and the component (b) will be illustrated.
(1) Synthesis example 1 (Leveler L1)
It is an example in which an imidazole compound (a) (= 2-mercapto-1H-methylimidazole) having a mercapto group is reacted with bis (2-chloroethyl) amine (b).
In 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 exchange water and 250 ml of ethanol were added. The system was purged with nitrogen and sodium hydroxide was added under 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, the mixture was transferred to a separatory funnel, and the methylene chloride layer was separated. After washing with ion exchange water, the methylene chloride layer was separated again. The methylene chloride layer was dried over magnesium sulfate, and then the solvent was distilled off using an evaporator to synthesize a mercaptoimidazole compound.

(2) Synthesis example 2 (Leveler L1)
It is the example which made the tetrazole compound (a) (= 1-(2- dimethylamino ethyl) 5-mercapto tetrazole) which has a mercapto group, and bis (2- chloroethyl) ether (b) react.
In 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 exchange water and 250 ml of ethanol were added. After the system was purged with nitrogen, an aqueous sodium hydroxide solution was added at 60 ° C. or less under stirring. Under stirring, 1- (2-dimethylaminoethyl) -5-mercaptotetrazole was dissolved, and then heated to 70 ° C., 0.5 mol of bis (2-chloroethyl) ether was added, and allowed to react for 14 hours. After completion of the reaction, methylene chloride was added at room temperature, the mixture was transferred to a separatory funnel, and the methylene chloride layer was separated. After washing with ion exchange water, the methylene chloride layer was separated again. After drying the methylene chloride layer, the solvent was distilled off using an evaporator to synthesize a mercapto tetrazole compound.

(3) Synthesis example 3 (Leveler L1)
It is an example in which benzothiazole (a) (= 2-mercaptobenzothiazole) having a mercapto group is reacted with 2- (dimethylamino) ethyl chloride (b) and bis (2-chloroethyl) ether (b).
In a 1-L three-necked flask fitted with a thermometer and a stirrer, 0.5 mol of 2-mercaptobenzothiazole, 300 ml of ion exchange water and 250 ml of ethanol were added. After the system was purged with nitrogen, an aqueous sodium hydroxide solution was added at 60 ° C. or less under stirring. Under stirring, 2-mercaptobenzothiazole was dissolved and then heated to 70 ° C., 0.2 mol of 2- (dimethylamino) ethyl chloride hydrochloride was added, and the reaction was allowed to proceed for 15 hours. After completion of the reaction, methylene chloride was added at room temperature, the mixture was transferred to a separatory funnel, and the methylene chloride layer was separated. After washing with ion exchange 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. Thereafter, 0.5 mol of the reaction product, 0.3 mol of bis (2-chloroethyl) ether and 50 g of methylcellulose were added to a 200 ml three-necked flask equipped with a thermometer and a stirrer. The reaction was allowed to proceed at 90 ° C. for 35 hours while stirring. After completion of the reaction, the reaction solution was cooled to 60 ° C. to synthesize a mercaptobenzothiazole compound.

Next, an example of synthesis of leveler L2 classified into products obtained by reacting component (a), component (b) and component (c) will be illustrated.
(4) Synthesis example 4 (Leveler L2)
It is an example in which thiadiazole (a) (= bismuthiol) having a mercapto group, 2- (dimethylamino) ethyl chloride (b), and polyethylene glycol (c) (= PEG) are reacted.
In a 1-L three-necked flask equipped with a thermometer and a stirrer, 0.5 mol of bismuthiol, 300 ml of ion exchange water and 250 ml of ethanol were added. After the system was purged with nitrogen, an aqueous sodium hydroxide solution was added at 60 ° C. or less under stirring. After dissolving bismuthiol under stirring, the temperature was raised to 70 ° C., 0.3 mole of 2- (dimethylamino) ethyl chloride hydrochloride was added, and reaction was carried out for 12 hours. After completion of the reaction, methylene chloride was added at room temperature, the mixture was transferred to a separatory funnel, and the methylene chloride layer was separated. After washing with ion exchange water, the methylene chloride layer was separated again. The methylene chloride layer was dried over magnesium sulfate, and then the solvent was distilled off using an evaporator to obtain a reaction product. Then, to a 200 ml three-necked flask equipped with a thermometer and a stirrer, 0.5 mol of the reaction product, 0.5 mol of both-end mesylate of polyethylene glycol (weight average molecular weight 200) and 50 g of methyl cellulose were added. The reaction was carried out at 90 ° C. for 35 hours under stirring to synthesize a mercaptothiadiazole type 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). 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 first invention.
Also, since the above leveler (B) is the same as the compound (B) used in the copper plating bath of the present invention 1, it can be selected from the specific leveler (L1) and the leveler (L2) of the present invention 1, Either (L1) or the leveler (L2) may be used alone, or the leveler (L1) and the leveler (L2) may be used in combination.
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, bis ( p-sulfophenyl) disulfide and salts thereof.
Examples of the mercaptans include mercaptomethanesulfonic acid, mercaptoethanesulfonic acid, mercaptopropanesulfonic acid (MPS), and salts thereof.
The above thiopropylsulfonic acids are 3- (benzothiazolyl-2-thio) propanesulfonic acid (ZPS), 3-[(aminoiminomethyl) thio] -1-propanesulfonic acid (UPS), O-ethyl-diethyl carbonate- S- (3-sulfopropyl) -esters and salts thereof.
The dithiocarbamic acids include N, N-dimethyl-dithiocarbamylpropane sulfonic acid (DPS), N, N-dimethyl-dithiocarbamic acid- (3-sulfopropyl) -ester, and salts thereof.

In the copper electroplating bath using the sulfur-containing compound (A) of the present invention 2 and the leveler (B) in combination, the sulfur-containing compound (A) can be used singly or in combination, and its content relative to the copper electroplating bath is 50 to 10000 mg / L, preferably 100 to 1500 mg / L, more preferably 50 to 1000 mg / L.
Generally, a copper electroplating bath contains a sulfur-containing compound such as SPS as an electrodeposition promoter, but the content thereof is usually a very small amount of about 3 to 10 mg / L. It is also characterized by blending at a concentration higher than the usual level of ~ 10000 mg / L.
If the content of the above-mentioned sulfur-containing compound (A) is less than the appropriate range, the low stress property can not be imparted to the copper plating 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. Or it becomes brittle and the physical properties of the film decrease.
The content of the above-mentioned leveler (B) to the copper plating bath is generally 0.1 to 500 mg / L, preferably 0.5 to 200 mg / L, as in the copper plating bath of the first invention. Preferably, it is 1 to 50 mg / L.
Moreover, in the said invention 2, the content ratio (weight ratio) of a sulfur-containing compound (A) and a leveler (B) is A / B = 1-500, Preferably 1-300, More preferably, it is 2-100.

The electrolytic copper plating bath of the present invention may contain known levelers, brighteners, chlorides, polymers and the like in order to promote the glossing action, the smoothing action and the like.
With regard to the above-mentioned chloride, chlorine having a predetermined concentration or more promotes warpage of the copper film, so the content in the plating bath is preferably small (see paragraph 7 of JP-A-2014-125679).
Further, as described above, in the copper electroplating bath of the present invention, even if the content of the above-mentioned polymer is omitted, a copper film having a warp preventing function can be obtained.
The leveler is, for example, a nitrogen-based organic compound mainly composed of a surfactant or a dye.
As the surfactant, a nonionic surfactant, an amphoteric surfactant, a cationic surfactant, or an anionic surfactant can be used singly or in combination.
Examples of the nonionic surfactant include polyethylene glycol (hereinafter referred to as PEG) and polypropylene glycol, as well as C1 to C20 alkanols, phenols, naphthols, bisphenols, (poly) C1 to C25 alkylphenols, (poly) arylalkylphenols, C1. ~ C25 alkyl naphthol, C1 to C25 alkoxylated phosphoric acid (salt), sorbitan ester, polyalkylene glycol, C1 to C22 aliphatic amine, C1 to C22 aliphatic amide, etc. ethylene oxide (EO) and / or propylene oxide (PO) And 2 to 300 moles of addition condensation, and C1 to C25 alkoxylated phosphoric acid (salt).
Examples of the cationic surfactant include quaternary ammonium salts or pyridinium salts. Specifically, lauryl trimethyl ammonium salts, stearyl trimethyl ammonium salts, lauryl dimethyl ethyl ammonium salts, octadecyl dimethyl ethyl ammonium salts , Dimethylbenzyl lauryl ammonium salt, cetyl dimethyl benzyl ammonium salt, octadecyl dimethyl benzyl ammonium salt, trimethyl benzyl ammonium salt, triethyl benzyl ammonium salt, dimethyl diphenyl ammonium salt, benzyl dimethyl phenyl ammonium salt, hexadecyl pyridinium salt, lauryl pyridinium salt, dodecyl Pyridinium salt, stearylamine acetate, laurylamine acetate, octadecylamine acetate Such as the Tate, and the like.
Examples of the anionic surfactants include alkyl sulfates, polyoxyethylene alkyl ether sulfates, polyoxyethylene alkyl phenyl ether sulfates, alkyl benzene sulfonates, {(mono, di, tri) alkyl} naphthalene sulfonates, etc. Can be mentioned. Examples of the amphoteric surfactant include carboxybetaine, imidazoline betaine, sulfobetaine and aminocarboxylic acid. Also, sulfated or sulfonated adducts of condensation products of ethylene oxide and / or propylene oxide with alkylamines or diamines can be used.

The nitrogen-based organic compounds mainly comprising the above dyes are, for example, dyes or derivatives thereof, amide compounds, thioamide compounds, compounds having an aniline or pyridine ring, various heteromonocyclic compounds, various condensed heterocyclic compounds, Amino carboxylic acids and the like.
Specific examples thereof include CI (Basic Color 2) Basic Red 2, Toluidine dyes such as Toluidine Blue, azo dyes such as CI Direct Yellow 1 and CI Basic Black 2, 3-amino- 6-dimethylamino-2-methylphenazine phenazine dyes such as hydrochloric acid, succinimides, imidazolines such as 2'-bis (2-imidazoline), imidazoles, benzimidazoles, indoles, 2-vinylpyridine, Pyridines such as 4-acetylpyridine, 4-mercapto-2-carboxylpyridine, 2,2'-bipyridyl, 4,4'-bipyridyl, phenanthroline, quinolines, isoquinolines, thiophene, thiourea, dimethylthiourea and the like Ureas, 3,3 ', 3 "-nitrilotripropionic acid, diaminomethyleneamino Acid, glycine, N- methyl glycine, dimethyl glycine, beta-alanine, cysteine, glutamic acid, aspartic acid, amino acid, such as ornithine. Preferred examples include CI Basic Red 2, Janus Green B, Toluidine Blue, and Succinimide.
The above brightener is thiourea or a derivative thereof, mercaptans such as 2-mercaptobenzimidazole and thioglycolic acid, sulfides such as 2,2'-thiodiglycolic acid and diethyl sulfide, 3-mercaptopropane-1-sulfone And sodium mercaptosulfonic acid such as bis (3-sulfopropyl) disulfide (disodium salt).
Examples of the polymer component include polyvinyl alcohol, carboxymethyl cellulose, polyethylene glycol, polypropylene glycol, stearic acid-polyethylene glycol ester, polyethylene-propylene glycol and the like.
However, in the copper electroplating bath of the present invention, since the above-mentioned various additives are considered to be related to the warpage of the copper film, attention must be paid to the selection and concentration of the components.

Among the copper electroplating methods of the present invention, the first method is to form a low stress plating film having a warp suppressing function on a thin object of 500 μm or less using the above-mentioned copper electroplating bath.
That is, when a copper film is formed by electroplating on a thin object to be plated, the warp stress of the plating film conventionally affects the thin object to be plated, and the plated film and the object to be plated are integrally bent. There has been a problem that the reliability of electronic components such as mounted semiconductor substrates is impaired, but in the first copper electroplating method of the present invention, the object to be plated is formed by forming a low stress plating film having a warp suppressing function. It is possible to improve the reliability of the electronic component by preventing the warp of the plating film integrated with the above.
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 or 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 in the case where the adhesion between the electrodeposition film and the object to be plated is low and the electrodeposition film itself has a risk of peeling off the object to be plated and warping.
That is, the second method is a method of forming a low stress copper plating film having a warpage suppressing function of 0.1 μm to 5000 μm on an object to be plated using the copper electroplating bath of the present invention.
When the plating film is thin, the warping force is weak and it adheres to the object to be plated, and peeling is unlikely to occur even if the adhesion is low. Therefore, in this second method, the thickness of the copper film formed on the object to be plated is to some extent It is premised that it is thick, and it is 0.1 μm to 5000 μm, preferably 0.5 to 200 μm, more preferably 1 to 100 μm.
However, in the above film thickness range, for example, the film thickness of 0.1 μm at the lower limit appears to be thin, but there is a risk of peeling from the plated object when the film is warped in relation to the plated object.
In the second method, by forming a low stress plating film having a warpage suppressing function, peeling of the plating film from the object to be plated due to the warpage can be prevented, and the reliability of the electronic component can be improved.

The pH of the copper electroplating bath is basically acidic, and is preferably 1 to 7, more preferably 1 to 5, and more preferably 2 or less.
There are no particular limitations on the plating conditions using the copper electroplating bath of the present invention, the bath temperature is 10 to 70 ° C., and the cathode current density is 0.1 to 50 A / dm 2, preferably 5 to 40 A / dm 2. The anode may be a soluble anode made of copper (alloy), or an insoluble anode made of platinum or carbon.
The film thickness of the film formed by electroplating is generally about 5 to 50 μm.

Hereinafter, an example of the electrolytic copper plating bath of the present invention and an electrodeposition stress evaluation test example for measuring the warp over time of the copper plating film obtained from the copper bath of the example will be sequentially described.
In the above Examples and Test Examples, "parts" and "%" are basically based on weight.
The present invention is not limited to the following examples and test examples, and it is needless to say that any modification can be made within the scope of the technical idea of the present invention.

<< Example of an electrolytic copper plating bath >>
Among Examples 1 to 19 below, Examples 1 to 8 and Examples 13 to 16 belong to the present invention 2 (examples of combined use of sulfur-containing compound and leveler), and Examples 9 to 12 and 17 to 19 are present. This is an example belonging to invention 1 (basically an example of single use of a leveler). Example 19 contains the sulfur-containing compound (A), but the content is as small as 10 mg / L and does not satisfy the requirement of the present invention 2 (including 50 mg / L or more of the sulfur-containing compound (A)). , Invention 1 is classified.
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 modified, Example 6 is an example in which the leveler (B) of Example 1 is modified to the leveler of Synthesis Example 2, and Example 7 is also a synthesis Example 8 is an example in which the leveler of Synthesis Example 4 is changed to the leveler of Example 3.
Example 9 is an example in which the sulfur-containing compound (A) is not contained based on Example 1 and only the leveler (B) is used alone, and Example 10 is an example in which the sulfur-containing compound is not contained based on Example 6 Example 11 is an example based on Example 7 containing no sulfur-containing compound, and Example 12 is an example based on Example 8 containing no 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 reduced. Example 15 is an example in which the leveler (B) of the present invention is increased based on Example 1 (the type of copper salt is different), and Example 16 is an example in which the leveler (B) is reduced.
Example 17 is an example where the leveler (B) is reduced based on Example 9, Example 18 is an example where the leveler (B) is increased, and Example 19 is an example where the leveler (B) is reduced and the sulfur-containing compound (A) Is an example of making it less than 50 mg / L.

On the other hand, among Comparative Examples 1 to 6, Comparative Example 1 is an example using the dye (Janus green B) in place of the leveler (B) of the present invention based on Example 1 (example of combined use of sulfur-containing compound and leveler). Similarly, Comparative Example 2 is an example using a polymer (PEG) generally used in an electrolytic copper plating bath, Comparative Example 3 (single-use example of leveler) is a leveler of the present invention based on Example 9 (single-use example of leveler) It is an example using a dye (phthalocyanine) instead of B).
Comparative Example 4 is an example using a conventional copper electroplating bath.
Comparative Examples 5 to 6 are examples based on the patent document 1 of lov described above, and Comparative Example 5 is an example using an imidazole compound having no mercapto group in the leveler based on Example 9 (single-use example of the leveler). Comparative Example 6 is an example using an imidazole compound having no mercapto group in the leveler, based on Example 1 (combination example of sulfur-containing compound and leveler).

(1) Example 1
An electrolytic copper plating bath was constructed with the following composition.
Copper oxide (as Cu 2+) 40 g / L
Sulfuric acid (98%) 110 g / L
Chloride ion 40 mg / L
ZPS 100 mg / L
Mercaptoimidazole compound 10 mg / L of Synthesis Example 1
pH <1

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

(3) Example 3
An electrolytic copper plating bath was constructed with the following composition.
Copper sulfate (as Cu 2+) 40 g / L
Sulfuric acid (98%) 110 g / L
Chloride ion 40 mg / L
SPS 100 mg / L
Mercapto imidazole compound 10 mg / L of the above Synthesis Example 1
pH <1

(4) Example 4
An electrolytic copper plating bath was constructed with the following composition.
Copper sulfate (as Cu 2+) 40 g / L
Sulfuric acid (98%) 110 g / L
Chloride ion 40 mg / L
MPS 100 mg / L
Mercapto imidazole compound 10 mg / L of the above Synthesis Example 1
pH <1

(5) Example 5
An electrolytic copper plating bath was constructed with the following composition.
Copper sulfate (as Cu 2+) 40 g / L
Sulfuric acid (98%) 110 g / L
Chloride ion 40 mg / L
DPS 100 mg / L
Mercapto imidazole compound 10 mg / L of the above Synthesis Example 1
pH <1

(6) Example 6
An electrolytic copper plating bath was constructed with the following composition.
Copper sulfate (as Cu 2+) 40 g / L
Sulfuric acid (98%) 110 g / L
Chloride ion 40 mg / L
ZPS 100 mg / L
Mercapto thiadiazole compound 10 mg / L of Synthesis Example 4
pH <1

(7) Example 7
An electrolytic copper plating bath was constructed with the following composition.
Copper sulfate (as Cu 2+) 40 g / L
Sulfuric acid (98%) 110 g / L
Chloride ion 40 mg / L
ZPS 100 mg / L
Mercapto tetrazole compound 10 mg / L of the synthesis example 2
pH <1

(8) Example 8
An electrolytic copper plating bath was constructed with the following composition.
Copper sulfate (as Cu 2+) 40 g / L
Sulfuric acid (98%) 110 g / L
Chloride ion 40 mg / L
ZPS 100 mg / L
Mercaptobenzothiazole compound 10 mg / L of the above-mentioned Synthesis Example 3
pH <1

(9) Example 9
An electrolytic copper plating bath was constructed with the following composition.
Copper sulfate (as Cu 2+) 40 g / L
Sulfuric acid (98%) 110 g / L
Chloride ion 40 mg / L
Mercaptoimidazole compound 50 mg / L of the above-mentioned Synthesis Example 1
pH <1

(10) Example 10
An electrolytic copper plating bath was constructed with the following composition.
Copper sulfate (as Cu 2+) 40 g / L
Sulfuric acid (98%) 110 g / L
Chloride ion 40 mg / L
Mercapto thiadiazole compound 50 mg / L of Synthesis Example 4
pH <1

(11) Example 11
An electrolytic copper plating bath was constructed with the following composition.
Copper sulfate (as Cu 2+) 40 g / L
Sulfuric acid (98%) 110 g / L
Chloride ion 40 mg / L
Mercapto tetrazole compound 50 mg / L of Synthesis Example 2
pH <1

(12) Example 12
An electrolytic copper plating bath was constructed with the following composition.
Copper sulfate (as Cu 2+) 40 g / L
Sulfuric acid (98%) 110 g / L
Chloride ion 40 mg / L
Mercaptobenzothiazole compound 50 mg / L of Synthesis Example 3
pH <1

(13) Example 13
An electrolytic copper plating bath was constructed with the following composition.
Copper sulfate (as Cu 2+) 40 g / L
Sulfuric acid (98%) 110 g / L
Chloride ion 40 mg / L
ZPS 1000 mg / L
Mercaptoimidazole compound 10 mg / L of Synthesis Example 1
pH <1

(14) Example 14
An electrolytic copper plating bath was constructed with the following composition.
Copper sulfate (as Cu 2+) 40 g / L
Sulfuric acid (98%) 110 g / L
Chloride ion 40 mg / L
ZPS 50 mg / L
Mercaptoimidazole compound 10 mg / L of Synthesis Example 1
pH <1

(15) Example 15
An electrolytic copper plating bath was constructed with the following composition.
Copper sulfate (as Cu 2+) 40 g / L
Sulfuric acid (98%) 110 g / L
Chloride ion 40 mg / L
ZPS 100 mg / L
Mercaptoimidazole compound 50 mg / L of the above-mentioned Synthesis Example 1
pH <1

(16) Example 16
An electrolytic copper plating bath was constructed with the following composition.
Copper sulfate (as Cu 2+) 40 g / L
Sulfuric acid (98%) 110 g / L
Chloride ion 40 mg / L
ZPS 100 mg / L
Mercaptoimidazole compound 1 mg / L of Synthesis Example 1
pH <1

(17) Example 17
An electrolytic copper plating bath was constructed with the following composition.
Copper sulfate (as Cu 2+) 40 g / L
Sulfuric acid (98%) 110 g / L
Chloride ion 40 mg / L
Mercaptoimidazole compound 1 mg / L of Synthesis Example 1
pH <1

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

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

(20) Comparative Example 1
An electrolytic copper plating bath was constructed with the following composition.
Copper sulfate (as Cu 2+) 40 g / L
Sulfuric acid (98%) 110 g / L
Chloride ion 40 mg / L
ZPS 100 mg / L
Janus Green B 10 mg / L
pH <1

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

(22) Comparative Example 3
An electrolytic copper plating bath was constructed with the following composition.
Copper sulfate (as Cu 2+) 40 g / L
Sulfuric acid (98%) 110 g / L
Chloride ion 40 mg / L
Phthalocyanine 10 mg / L
pH <1

(24) Comparative Example 4
An electrolytic copper plating bath was constructed with the following composition.
Copper sulfate (as Cu 2+) 40 g / L
Sulfuric acid (98%) 110 g / L
Chloride ion 40 mg / L
ZPS 100 mg / L
Janus Green B 1 mg / L
Polyethylene glycol (average molecular weight 20000) 500 mg / L
pH <1

(25) Comparative Example 5
An electrolytic copper plating bath was constructed with the following composition.
Copper sulfate (as Cu 2+) 40 g / L
Sulfuric acid (98%) 110 g / L
Chloride ion 40 mg / L
Imidazole compound without mercapto group 10 mg / L
pH <1
In the above Synthesis Example 1, an imidazole compound having a mercapto group classified into leveler L1 of the present invention was synthesized, but the imidazole compound having no mercapto group is a 2-mercapto compound based on this Synthesis Example 1. It was synthesized using 0.5 mole of imidazole instead of 0.5 mole of 1H-methylimidazole.

(26) Comparative Example 6
An electrolytic copper plating bath was constructed with the following composition.
Copper sulfate (as Cu 2+) 40 g / L
Sulfuric acid (98%) 110 g / L
Chloride ion 40 mg / L
ZPS 100 mg / L
Imidazole compound without mercapto group 10 mg / L
pH <1
The imidazole compound having no mercapto group is the same as that used in Comparative Example 5.

<< Example of evaluation test of electrodeposition stress >>
Therefore, using the copper plating baths of Examples 1 to 19 and Comparative Examples 1 to 6, electroplating is performed under the conditions of a cathode current density of 10 A / dm 2, a bath temperature of 30 ° C., and a plating time of 10 minutes. A test strip electrodeposition stress test was performed on the obtained electrodeposition film immediately after plating.
As described above, in normal copper plating, the stress immediately after plating is tensile stress (+ MPa), and tensile stress (+ MPa) works continuously with the passage of time (after 1 to 2 days). Warpage 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 plating surface side with the passage of time, but it takes 1 to 2 days When it passes, it will be in a steady state and it will not go any further.

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
Example 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
Example 16-11
Example 17-13
Example 18-8
Example 19-9

<< Comprehensive evaluation based on the above test results >>
According to the above Table A, it contains the sulfur-containing compound (A) of the present invention and, instead of the leveler (B) of the present invention, it contains a nitrogen-based dye (Janus green) widely used in copper electroplating baths. In Comparative Example 1, each tensile stress was +10 MPa, and in Comparative Example 2 containing a polymer (PEG) commonly used in an electrolytic copper plating bath, +8 MPa was shown.
In addition, in Comparative Example 3 which does not contain the sulfur-containing compound (A) of the present invention and contains a nitrogen-based dye (phthalocyanine) generally used in an electrolytic copper plating bath instead of the leveler (B) of the present invention It showed stress.
Next, the sulfur-containing compound (A) of the present invention (A) does not contain the sulfur-containing compound (A) of the present invention, and in Comparative Example 5 containing an imidazole compound having no mercapto group instead of the leveler (B) of the present invention Comparative Example 6 containing an imidazole compound containing no mercapto group, instead of the leveler (B) of the present invention, showed a tensile stress of +9 MPa.
In addition, in the comparative example 4 which used the common electrolytic copper plating bath, tensile stress was shown again, and the value was the largest with +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 they contain the sulfur-containing compound (A) of the present invention and the compound replacing the leveler of the present invention. This is a comparative example of the present invention 1 in that it does not contain the sulfur-containing compound (A) of the present invention and contains an alternative compound of the leveler of the present invention, but in these comparative examples 1 to 6, tensile stress (+ MPa) was applied to all plated films. It can be seen that the plating film warps in a concave shape (ie, convex on the lower substrate side) with the surface side up (see FIG. 1A).
On the other hand, in Examples 1 to 19 including the levelers (L1, L2) of the present invention, or further containing a predetermined amount of the sulfur-containing compound (A) of the present invention, all plating films were It can be seen that the compressive stress of (see FIG. 1B) acts.
As a result, even if the tensile stress works with time and the copper plating film is warped, this compressive stress (-MPa) works against the tensile stress (+ MPa) to bring the stress close to 0 Mpa, so there is almost no warpage. A copper film can be formed over time.
For this reason, in electrolytic copper plating, in order to prevent the warp of the electrodeposition film which is the subject of the present invention, it is a condition that compressive stress (-MPa) is obtained immediately after plating, and from the copper plating bath of the present invention It was confirmed that the obtained electrodeposition film satisfied the conditions.

In particular, when Comparative Examples 5 to 6 (comparative examples according to Patent Document 1 above) are compared with Examples 1 to 19, complex copper is plated when a product obtained by reacting a heterocyclic nitrogen compound is used as a leveler. The remarkable result was unexpectedly found that the force acting on the obtained copper film splits in the opposite direction of tensile stress and compressive stress depending on the presence or absence of mercapto group binding to the ring compound.
That is, it is important that the presence or absence of the binding of the mercapto group to the heterocyclic nitrogen compound is largely related to the suppression of the warpage of the copper film over time, and that the bonding of the mercapto group to the heterocyclic compound is essential for the suppression of the warpage. 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, but among these, examples 1 to 5 are the levelers of the present invention (= mercaptoimidazole type Compound (A) is fixed to ZPS, UPS, SPS, MPS, DPS various compounds, and Example 1 and Examples 6 to 8 are 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 mercaptoimidazole compounds, mercaptothiadiazole compounds, mercaptotetrazole compounds, etc., but all are compressive stress (-MPa) on the plated film Could be granted. Comparing the levelers L1 and L2, -12 MPa in Example 6 using the leveler L2 (Synthesis example 4), -11 to 11 in the examples 1 to 5 and 7-8 using the levelers 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 singly, and are examples in which the leveler is changed to various compounds such as mercaptoimidazole compound, mercaptothiadiazole compound and mercaptotetrazole compound. However, when the levelers L1 and L2 are compared, -10 MPa in Example 10 using Leveler L2 (Synthesis Example 4), -8 MPa in Example 9 using Leveler L1 (Synthesis Examples 1 to 3), and 11-12 Showed a compressive stress of

Examples 13 to 16 belong to the (combination type) electrolytic copper plating bath of the present invention 2, and the sulfur-containing compound (A) of the present invention is increased or decreased based on Example 1, and the leveler of the present invention (B) In Examples 13-14 in which the sulfur-containing compound (A) was increased or decreased from Example 1, the compressive stress was not changed. Therefore, the leveler (B) can be judged to be an appropriate amount even if it is a small amount. In Example 15 in which the leveler (B) was increased from Example 1, the compressive stress was -7 MPa in Example 15 and the compressive stress was -11 MPa in Example 16 in which the level was reduced. The amount is assumed to be sufficient in a small amount range.
Examples 17 to 18 belong to the (single use type) electrolytic copper plating bath of the invention 1 and are examples in which the leveler (B) of the invention is increased or decreased based on the example 1 and the leveler (B) is implemented. In Example 17 reduced from Example 1, since the compression stress is -13 MPa and the compression stress is -8 MPa in Example 18 increased, the content of the leveler (B) is sufficient even in a small amount range even with a single-use type plating bath It is guessed. Example 19 contains the sulfur-containing compound (A) and the leveler (B), but the content (10 mg / L) of the sulfur-containing compound (A) is less than the amount specified in the second invention. It belongs to an electrolytic copper plating bath and has a compressive stress of -9 MPa.
In particular, when comparing Examples 16 to 17 with Example 1, the content of the leveler in Examples 16 to 17 is 1 mg / L, which is only 1/10 of Example 1, but the absolute value of the compressive stress In view of the fact that it is more than that of Example 1 (-10MPa → -11, -13MPa), it is judged that the content of the leveler (B) may be small or small in terms of suppressing the warpage of the plating film. it can. Moreover, although Example 19 reduced the content of copper salt and acid from Example 1, the absolute value of the compressive stress did not change much.

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

Claims (6)

In an electrolytic copper plating bath containing a soluble copper salt and an acid or a salt thereof,
A 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 or both ends. An electrolytic copper plating bath for forming a low stress film, characterized in that In an electrolytic copper plating bath containing an available copper salt and an acid or a salt thereof,
(A) 50 to 10000 mg / L of a sulfur-containing compound selected from sulfides, mercaptans, thiopropyl sulfonic acids and dithiocarbamic acids,
(B) 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 An electricity for forming a low stress film, comprising at least one of a leveler (L2) which is a reaction product of a compound (b) and a polyalkylene glycol (c) having a reactive group at one end or both ends. Copper plating bath. The heterocyclic ring constituting the heterocyclic nitrogen compound (a) is a dioxane ring, 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 thiadiazole ring, a pyrimidine ring, And is selected from the group consisting of pyrazine ring, quinoline ring, benzoxazole ring, morpholine ring and pyrrole ring,
The organic halogen compound (b) is a compound having at least one or more halogens in the alkylene chain, or further having a functional group selected from the group consisting of an amino group, an ether group, a hydroxyl group and a sulfonic acid group. Yes,
The low stress according to claim 1 or 2, wherein the reactive group possessed by the polyalkylene glycol (c) is selected from the group consisting of a halogen group, a haloformyl group, a mesylate group, and a tosylate group. Electric copper plating bath for film formation. Among the sulfur-containing compounds (A), sulfides are bis (3-sulfopropyl) disulfide (SPS), bis (2-sulfopropyl) disulfide, bis (3-sul-2-hydroxypropyl) disulfide, bis (4) -Sulfopropyl) disulfide, bis (p-sulfophenyl) disulfide and salts thereof,
Similarly, mercaptans are selected from mercaptomethanesulfonic acid, mercaptoethanesulfonic acid, mercaptopropanesulfonic acid (MPS) and salts thereof,
Thiopropylsulfonic acids are 3- (benzothiazolyl-2-thio) propanesulfonic acid (ZPS), 3-[(aminoiminomethyl) thio] -1-propanesulfonic acid (UPS), O-ethyl-diethyl carbonate-S -(3-sulfopropyl) -ester and salts thereof;
The dithiocarbamic acids are selected from N, N-dimethyl-dithiocarbamylpropane sulfonic acid (DPS), N, N-dimethyl-dithiocarbamic acid- (3-sulfopropyl) -ester and salts thereof The electrolytic copper plating bath for low stress film formation according to claim 2 or 3 characterized by the above-mentioned.   A low stress plating film having a warp suppressing function is formed on a thin object to be plated of 500 μm or less using the copper electroplating bath according to any one of claims 1 to 4 and integrated with the object to be plated The copper electroplating method characterized by preventing the curvature of the plating film which carried out.   A low stress copper plating film having a warpage suppressing function of 0.1 μm to 5000 μm is formed on an object to be plated using the copper electroplating bath according to any one of claims 1 to 4, and plating is performed by the warpage action. A copper electroplating method characterized in that the coating film is prevented from peeling off from the object to be plated.

Images