JP2003213478A - Electrolytic copper plating method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new electrolytic copper plating method which causes no deterioration in the appearance of plating, and is suitable for the formation of filled via holes. <P>SOLUTION: A plating solution contains a compound having -X-S-Y structure (wherein, X and Y are an atom respectively independently selected from the group consisting of a hydrogen atom, a carbon atom, a sulfur atom, a nitrogen atom and an oxygen atom; and X and Y can be made the same only in the case they are a carbon atom), and copper plating is performed in the presence of titanium oxide while applying ultraviolet rays or visible rays. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a novel electrolytic copper plating method using titanium oxide.

[0002]

2. Description of the Related Art In recent years, there has been a strong demand for higher density and thinner printed wiring boards in order to cope with higher performance and smaller size of electronic devices such as personal computers. As one of the methods for responding to such a demand, a multilayer printed wiring board (buildup printed wiring board) manufactured by using a buildup method in which a pattern is formed for each layer and sequentially laminated is used. Has become.
In such a build-up printed wiring board, in recent years, the effective area of the printed wiring board can be increased, and compared with the conventional plating of only the MVH inner wall surface,
Even if the MVH has a smaller diameter, sufficient electrical connection can be obtained, which is effective for downsizing and high density of the printed wiring board. This is called via-filling, and the entire MVH is filled with a conductor. , A method for making electrical connection between adjacent layers of a build-up printed wiring board has been developed.

Via filling methods include a method of filling a conductive paste into the MVH by a printing method, a method of activating only a conductor layer on the bottom surface of the MVH to selectively stack electroless copper plating, and an electrolytic copper plating. Methods have been announced. However, since the conductive paste is a mixture of copper and an organic substance, it has a lower conductivity than metallic copper, and it is difficult to make sufficient electrical connection with a MVH having a small diameter, which leads to downsizing and high density of printed wiring boards. On the other hand, it is not an effective method. Further, the filling by the printing method requires filling a viscous paste into a hole having a small diameter and not penetrating, but it is difficult to completely fill it without leaving a space because of the viscosity of the paste. Is. Further, the method using electroless copper plating is superior to the conductive paste method in that the MVH filler is a highly conductive metal copper deposit, but the plating film deposition rate is slow and there is a problem in productivity. . When a general high-speed type electroless copper plating bath is used, the deposition rate of the plating film is about 3 μm / hr, and using this, the inside of a typical BVH with a diameter of 100 μm and a depth of 100 μm is plated with copper. When filling, it takes 30 hours or more, and the productivity is extremely poor.

On the other hand, the electrolytic copper plating has a high deposition rate of 10 to 50 μm / hr, which makes it possible to significantly reduce the time required for electroless copper plating.
The application of electrolytic copper plating to H was expected. But,
When copper is deposited on the entire inner surface of the MVH, in order to fill the interior of the MVH with copper without leaving voids, it is necessary that the deposition rate near the bottom surface of the MVH be faster than the deposition rate at the openings. is there. If the deposition rate near the bottom surface is the same as or slower than the deposition rate in the opening, the MVH may not be filled, or the opening may be blocked before the copper plating filling inside the MVH is completed, leaving a void inside. In any case, it cannot be put to practical use.

Conventionally, an electrolytic copper plating bath containing a specific compound containing a sulfur atom has been used in order to accelerate the deposition rate near the bottom surface in the MVH, and the electrolysis condition is a soluble anode such as a phosphorus-containing copper anode. Direct current electrolysis using was used. However, with this method, good MVH immediately after bathing
Although it shows filling performance, the electrolytic copper plating bath becomes unstable over time, and after a certain period of time has passed from the building bath, agglomerates are generated in the formation of the electrolytic copper plating layer, which deteriorates the plating appearance and fills the via. There were problems such as destabilizing the sex. The present inventor has continued research on such problems, found out that the decomposition product of a sulfur-containing compound described later is the cause, and decided to utilize the oxidation reaction by titanium oxide as a method for reducing this decomposition product. It was made based on.

[0006]

The present invention has been made in view of the above circumstances, and by utilizing the photocatalytic activity of titanium oxide, the formation of filled vias is prevented without deteriorating the plating appearance. It aims at providing the electrolytic copper plating method suitable also for.

[0007]

The present invention provides an electrolytic copper plating method for plating in the presence of titanium oxide. The present invention further provides a —X—S—Y— structure, where X and Y
Are each independently a hydrogen atom, a carbon atom, a sulfur atom,
An atom selected from the group consisting of a nitrogen atom and an oxygen atom, and X and Y can be the same only in the case of a carbon atom. The present invention provides an electrolytic copper plating method for performing plating in the presence of titanium oxide using a plating solution containing a compound having a). Further in the present invention, the substrate to be electrolytically copper-plated is typically a printed wiring board or a wafer,
In particular, the substrate has through holes or via holes. The present invention further provides a composite material obtained by the plating method of the present invention.

The titanium oxide used in the present invention is
Any titanium oxide having photocatalytic activity can be used. Preferably the titanium oxide is titanium dioxide,
The rutile type and the anatase type as well as the amorphous type can be used. The crystallite size and particle size of the particles can be arbitrarily selected. Further, in addition to those exhibiting a photocatalytic activity by irradiation with ultraviolet rays, those exhibiting a photocatalytic activity by visible light can also be suitably used. In the present invention, the photocatalytic ability refers to the oxidizing ability of titanium oxide, which is exhibited by ultraviolet rays or visible light. This ability oxidizes the material in contact with the surface of titanium oxide.

Titanium oxide may be added to the plating solution as a powder, but it is preferably used as a molded product such as granules, filters or beads, or supported or coated on a suitable substrate. Has been used. The substrate may be any substance, may have various shapes such as a plate, a sphere, a rod, a line, and a molded net, or may be a porous substance. The method for producing the above-mentioned molded product or the method for supporting or coating is known, and any method can be used. Preferably used is a titanium plate or mesh having a titanium dioxide layer on the surface.

When titanium oxide exhibits photocatalytic activity by ultraviolet rays, the titanium oxide is irradiated with ultraviolet rays. As the light source of ultraviolet rays, sunlight and artificial light can be used. As the artificial light, various low-pressure, medium-pressure and high-pressure ultraviolet lamps can be used. The ultraviolet rays can be irradiated as they are or after passing through a filter.
The ultraviolet lamp is arranged so that the titanium oxide is irradiated with a sufficient amount of ultraviolet rays so that the photocatalytic ability is exhibited. In addition,
A person skilled in the art can easily determine the irradiation dose of ultraviolet rays sufficient for expressing the photocatalytic activity. The ultraviolet lamp can be provided outside the plating bath, but is preferably provided inside the plating bath. When titanium oxide exhibits a photocatalytic activity with visible light, it is irradiated with natural light or artificial light so that a sufficient amount of visible light is supplied into the plating bath. Also in this case, preferably a lamp that emits visible light is installed in the plating bath. Further, in the present invention, it is also possible to use a light source that simultaneously emits ultraviolet light and visible light for irradiation of ultraviolet light and / or visible light. One aspect of the electrolytic copper plating method of the present invention is
Irradiation of the plating solution with ultraviolet light and / or visible light in the presence of titanium oxide includes irradiation of the plating solution with ultraviolet light and / or visible light in the presence of titanium oxide by electrolytic copper plating. It may be performed at the same time or after the electrolytic copper plating treatment is completed,
Further, it is possible to adopt a mode in which it is always performed regardless of the electrolytic treatment. That is, the electrolytic copper plating method of the present invention does not include only during the electrolytic treatment, after the electrolytic treatment,
It also includes treatments performed until the next electrolytic treatment.

In the electrolytic copper plating method of the present invention, the plating solution contains a compound having a --X--S--Y-- structure. Preferably, X and Y in the structure of the compound are each independently an atom selected from the group consisting of a hydrogen atom, a carbon atom, a nitrogen atom, a sulfur atom and an oxygen atom, and in the present specification, for convenience. The above compound is called a sulfur-containing compound. More preferably, X and Y are each independently an atom selected from the group consisting of a hydrogen atom, a carbon atom, a nitrogen atom and a sulfur atom, and even more preferably, X and Y are each independently hydrogen. An atom selected from the group consisting of an atom, a carbon atom and a sulfur atom, and X and Y can be the same only in the case of a carbon atom. In the above formula -X-S-Y-, S indicates that the valence is 2, but it does not mean that the valences up to the X and Y atoms are 2, and the X and Y atoms are It represents that it can be bonded to any other atom depending on its valence. For example, when X is hydrogen, it has a structure of H-S-Y-.

More preferably, the sulfur-containing compound is
, Sulfonic acid group or sulfonic acid alkali in the molecule
It is a compound having a group that is a metal salt. Sulfonic acid group
Or at least one alkali metal salt thereof should be present in the molecule.
You can Even more preferably, with a sulfur-containing compound
Then, in the molecule, -S-CH_TwoOR-SO_ThreeM structure
Having a compound, or in the molecule, -SR-SO_ThreeM
  A compound having a structure (in the formula, M is hydrogen or alkali gold)
A genus atom, R is an alkyl group containing 3 to 8 carbon atoms.
). Even more preferably, sulfur-containing
As the compound, a compound having the following structures (1) to (8)
Things can be mentioned. (1) M-SO_Three-(CH_Two)_a-S- (CH_Two)_b
-SO_Three-M; (2) M-SO_Three-(CH_Two)_a-O-CH_Two-S-
CH_Two-O- (CH_Two) _b-SO_Three-M; (3) M-SO_Three-(CH_Two)_a-S-S- (C
H_Two)_b-SO_Three-M; (4) M-SO_Three-(CH_Two)_a-O-CH_Two-S-
S-CH_Two-O- (CH _Two)_b-SO_Three-M; (5) M-SO_Three-(CH_Two)_a-SC (= S)-
S- (CH_Two)_b-SO _Three-M; (6) M-SO_Three-(CH_Two)_a-O-CH_Two-S-
C (= S) -S-CH_Two-O- (CH_Two)_b-SO_Three−
M: In the above formulas (1) to (6), in the formula, a and b
= An integer of 3 to 8; M is hydrogen or an alkali metal element
Is. (7) XS- (CH_Two)_a-SO_Three-M; and (8) X-S-CH_Two-O- (CH_Two)_a-SO_Three-M In the above formulas (7) and (8), in the formula, a = 3
Is an integer of 8; M is hydrogen or an alkali metal element
R; X is a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an ant
Group, 1 to 6 nitrogen atoms and 1 to 20 carbon atoms
A chain or cyclic amine composed of multiple hydrogen atoms
Compounds, or 1-2 sulfur atoms and 1-6 nitrogen
With atoms, 1 to 20 carbon atoms and multiple hydrogen atoms
It is one of the heterocyclic compounds constituted.

Sulfur-containing compounds are commonly used as brighteners, but are also within the scope of this invention when used for other purposes. When a sulfur-containing compound is used, only one kind may be used or two or more kinds may be mixed and used.

When the sulfur-containing compound is a brightener,
The brightening agent can be used, for example, in the range of 0.1 to 100 mg / L, preferably 0.5 to 10 mg / L. If the concentration in the plating solution is 0.1 mg / L or less, the effect of promoting the growth of the copper plating film cannot be obtained. Further, even when the amount exceeds 100 mg / L, almost no improvement in the effect commensurate with it can be obtained, which is not preferable from the economical point of view. When the sulfur-containing compound is used for purposes other than the brightening agent, the suitable range of the amount used is a matter which can be appropriately determined by those skilled in the art.

The present inventors have found that the above-mentioned sulfur-containing compound --X--
-X, which is a decomposition product produced by cleavage of the single bond of SY-
-S⁻, Or -Y-S⁻Increasing number of compounds is electrolytic copper plating
May deteriorate the filling ability of vias and the appearance of plating.
And found out. Here, in the sulfur-containing compound
X and Y are interchangeable, such as the brightener
(1) M-SO_Three-(CH_Two)_a-S- (CH_Two)_b−
SO_ThreeIn the case of -M, the decomposition product is M-SO._Three
-(CH_Two)_a-S⁻, Or⁻S- (CH_Two) _b-S
O_Three-M is thought to occur, whichever of-
XS⁻Or -Y-S⁻Also good. Therefore,
In the detailed text, for convenience, the decomposition products of sulfur-containing compounds
"-X-S⁻". Also included in the electrolytic copper plating solution
-X-S⁻The compound is a sulfur-containing compound-X-S-Y.
-Only the single bond of XS or S-Y is cleaved,
The other part of the molecule is the undegraded structure of the compound.
The decomposition product may be "X-S⁻Holding structure
, The compound that binds to X is further decomposed
It may be a mixture of several kinds of these compounds,
Is also good.

[-X-S] which is a decomposition product of a sulfur-containing compound.
⁻The concentration of the compound having the structure can be determined by any known method.
More measurable, for example, high performance liquid chromatograph
However, it is not limited to these.
Not a thing. High performance liquid chromatography is used
When using a high-performance liquid chromatograph,
It may be applied to the fee, and there are contaminants that hinder the measurement.
If you want to remove
The process may be performed after the process. -XS⁻Compound
Is a single type, the concentration of the single compound is “−X
-S ⁻Corresponding to the concentration of the compound having the structure, -X-S
⁻When the compound is a mixture of multiple types, each compound
The total concentration of the substances is "-XS⁻Of the compound having the structure
Corresponds to concentration. Here, the sulfur-containing compound in the plating solution
The amount of -X-S-Y- and its decomposition products is the plating deposition amount.
To measure the amount of additives such as brighteners indirectly
CVS (Cyclic Vo)
ltammetry Stripping) analyzer
It is also possible to use it and to evaluate it as a "CVS value".
In addition, in the electrolytic copper plating solution, "-X-S⁻"Compound
Is usually a positive ion such as a metal ion or hydronium ion.
It exists as a pair with ON. Therefore, in the present invention
Is "-X-S⁻I will consider the mechanism of action of compounds
Except in specific cases, such as "-X-S⁻"-
Also included are compounds of the "X-S-H" structure.

[0017] While not wishing to be bound by theory, the electrolytic copper plating solution "-X-S ^-" as the major mechanism by which compounds having a structure results, for example, using a soluble anode such as phosphorous copper Then, during the electrolysis suspension period, the soluble anode reacts with the sulfur-containing compound, and the sulfur-containing compound S
Single bond -X or S-Y is cleaved "-X-S ^-"
It is conceivable that a compound having a structure will occur. Also,
In the electrolytic copper plating treatment, at the cathode, the sulfur-containing compound receives electrons, is cut single bond S-X or S-Y ^- is considered that a compound having a structure results "-X-S" . In the anode, the soluble anode receives electrons emitted when the Cu is Cu ^2+, the sulfur-containing compounds ^- is considered to be a structure "-X-S".

Although not wishing to be bound by theory,
"-X-S ^-" The mechanism of action of a compound adversely affect the electrolytic copper plating having the structure, by which the compound is a metal ion, for example Cu ^+, Cu ²⁺ and ionically bound, there is the conjugate, It is considered that the deposited metal forms agglomerates to form a metal layer having poor adhesion, heat resistance, etc., and also causes a deterioration in plating appearance such as poor gloss. Further, also in the formation of filled vias, the combined product of the decomposition product and the metal ion is
By setting the metal deposition rate near the bottom of the via to be about the same as or less than the metal deposition rate at the via opening,
It is considered that filling of the via is insufficient, or depending on the shape of the via or the like, the problem of filling the via with leaving a void may occur.

[0019] In the electrolytic copper plating method of the present invention, -X-S of the electrolytic copper plating solution ^- the concentration of the compound having the structure, from the viewpoint of the glossiness of the coating appearance is not matte, 2.0Myumol / It is preferable to maintain L or less, and from the viewpoint of making the plating appearance glossy, 1.0 μmol / L or less, more preferably 0.5
More preferably, it is maintained at μmol / L.

[0020] In addition, in view of improving the filling of the vias, -X-S ^- it is preferable to maintain the concentration of the compound having the structure below 0.15 / L, more preferably, 0.1 [mu] mol / L or less.

As the electrolytic copper plating solution used in the present invention, any bath solution can be used as long as it can electrolytically plate copper, and examples thereof include a copper sulfate plating solution, a copper cyanide plating solution, and copper pyrophosphate. Examples of the plating solution include, but are not limited to: Preferably, the electrolytic copper plating solution is a copper sulfate plating solution. Hereinafter, a copper sulfate plating solution will be described as a typical example of the electrolytic copper plating solution. The composition, components, etc. of the other plating solutions are within the range that can be easily determined by those skilled in the art from the following description of the copper sulfate plating solution in the present specification and known documents.

The basic composition of the electrolytic copper plating solution of the present invention can be used without particular limitation as long as it is known and used in ordinary electrolytic copper plating, as long as the object of the present invention is achieved. In the above, it is possible to appropriately change the composition of the basic composition, change the concentration, and add additives. For example, in the case of copper sulfate plating, the copper sulfate plating solution is an aqueous solution containing sulfuric acid, copper sulfate, and a water-soluble chlorine compound as a basic composition, and the basic composition of the plating solution is used for known copper sulfate plating. Any material can be used without particular limitation.

The concentration of sulfuric acid in the copper sulfate plating solution is usually 3
0 to 400 g / L, preferably 170 to 210 g
/ L. For example, when the sulfuric acid concentration is less than 30 g / L, the electroconductivity of the plating bath decreases, and it becomes difficult to energize the plating bath. On the other hand, if it exceeds 400 g / L, the dissolution of copper sulfate in the plating bath is hindered, which causes the precipitation of copper sulfate. The copper sulfate concentration in the copper sulfate plating solution is usually 20 to 250 g / L, preferably 60 to 180 g / L. For example, when the copper sulfate concentration is less than 20 g / L, the supply of copper ions to the substrate to be plated becomes insufficient, and it becomes impossible to deposit a normal plating film. Further, it is difficult to dissolve copper sulfate in excess of 250 g / L.

The water-soluble chlorine compound contained in the copper sulfate plating solution can be used without particular limitation as long as it is one used in known copper sulfate plating. Examples of the water-soluble chlorine compound include, but are not limited to, hydrochloric acid, sodium chloride, potassium chloride, ammonium chloride and the like. As the water-soluble chlorine compound, only one kind may be used, or two or more kinds may be mixed and used. The concentration of the water-soluble chlorine compound contained in the copper sulfate plating solution used in the present invention is usually 10 to 200 mg / L, and preferably 30 to 80 mg / L as a chloride ion concentration. For example, when the chlorine ion concentration is less than 10 mg / L, it becomes difficult for the brightening agent, the surfactant and the like to function normally. Also, 2
If it exceeds 00 mg / L, chlorine gas is generated from the anode in a large amount, which is not preferable.

The electrolytic copper plating solution used in the present invention includes
A surfactant can optionally be included. As the surfactant, any known surfactant that is usually used as an additive for an electrolytic copper plating solution can be used. Preferably, as the surfactant, the following (9) to
Examples thereof include compounds having the structure of (13), but are not limited thereto. _{(9) HO- (CH 2 -CH} 2 -O) in a -H (wherein,
a = 5 to 500 in an _{integer); (10) HO- (CH} 2 -CH (CH 3) -O) a -H
(Wherein, is an integer of _{a = 5~200); (11)} HO- (CH 2 -CH 2 -O) a - (CH 2 -
_{CH (CH 3) -O) b} - (CH 2 -CH 2 -O) c -
H (where a and c are integers and a + c = 5-2)
Is an integer of 50, and b is an integer of 1 to 100); (12)-(NH ₂ CH ₂ CH ₂ ) n- (wherein, n =
5 to 500. );and

(13)

[Chemical 1] (In the formula, a, b, and c are integers of 5 to 200)

The surfactant used in the present invention may be used alone or in combination of two or more. The surfactant used in the present invention is, for example, 0.05
It can be used in the range of 10 to 10 g / L, preferably 0.1 to 5 g / L. The concentration in the plating solution is 0.05 g /
If it is less than L, the wetting effect will be insufficient and a large number of pinholes will occur in the plating film, making it difficult to deposit a normal plating film. Even if it exceeds 10 g / L, almost no corresponding improvement in effect can be obtained, which is not preferable from an economical point of view.

The substrate used in the electrolytic copper plating method of the present invention can withstand the conditions in the electrolytic copper plating method, as long as it can form a metal layer by plating.
Substrates of any material and shape can be used.
Examples of the material include, but are not limited to, resin, ceramic, metal and the like. For example, the substrate made of resin may be a printed wiring board, and the substrate made of ceramic may be, but is not limited to, a semiconductor wafer. Examples of the metal include, but are not limited to, silicon and the like. Examples of the substrate made of metal include, but are not limited to, silicon wafers. Since the electrolytic copper plating method of the present invention is particularly excellent in filling via holes, the substrate used in the present invention is preferably a substrate having a through hole, a via hole, etc., more preferably a through hole and / or Alternatively, it is a printed wiring board or a wafer having a via hole.

The resin used for the substrate is, for example,
High density polyethylene, medium density polyethylene, branched low density polyethylene, linear low density polyethylene, ultra high molecular weight polyethylene and other polyethylene resins, polypropylene resin, polybutadiene, boribten resin, polybutylene resin, polystyrene resin and other polyolefin resins; polyvinyl chloride Resin, polyvinylidene chloride resin, polyvinylidene chloride-vinyl chloride copolymer resin, halogen-containing resin such as chlorinated polyethylene, chlorinated polypropylene, tetrafluoroethylene; AS resin; ABS resin; MBS
Resins; polyvinyl alcohol resins; polyacrylic acid ester resins such as polymethyl acrylate; polymethacrylic acid ester resins such as polymethyl methacrylate; methyl methacrylate-styrene copolymer resins; maleic anhydride-styrene copolymer Combined resin; polyvinyl acetate resin;
Cellulose resins such as cellulose propionate and cellulose acetate resins; epoxy resins; polyimide resins; polyamide resins such as nylon; polyamideimide resins; polyarylate resins; polyetherimide resins; polyetheretherketone resins; polyethylene oxide resins; PET resins Polyester resin such as polycarbonate resin; polysulfone resin; polyvinyl ether resin; polyvinyl butyral resin; polyphenylene ether resin such as polyphenylene oxide; polyphenylene sulfide resin; polybutylene terephthalate resin; polymethylpentene resin; polyacetal resin; vinyl chloride-vinyl acetate copolymer Ethylene-vinyl acetate copolymers; ethylene-vinyl chloride copolymers; etc. and copolymers and blends thereof. Thermoplastic resins, epoxy resins;
Xylene resin; guanamine resin; diallyl phthalate resin; vinyl ester resin; phenol resin; unsaturated polyester resin; furan resin; polyimide resin; polyurethane resin; maleic acid resin; melamine resin; urea resin;
Thermosetting resins such as and the like, as well as mixtures thereof, but are not limited thereto. Preferable resins include epoxy resin, polyimide resin, vinyl resin, phenol resin, nylon resin, polyphenylene ether resin, polypropylene resin, fluorine resin and ABS resin, and more preferably epoxy resin, polyimide resin,
A polyphenylene ether resin, a fluorine-based resin, an ABS resin, and more preferably an epoxy resin and a polyimide resin. Further, the resin substrate may be made of a single resin, or may be made of a plurality of resins. Further, it may be a composite in which a resin is applied or laminated on another substrate. The resin substrate usable in the present invention is not limited to the resin molded product,
It may be a composite in which a reinforcing material such as a glass fiber reinforcing material is interposed between resins, or a resin film formed on a base material made of various materials such as ceramics, glass and metals such as silicon. It may be.

Ceramics usable as the base material include alumina (Al ₂ O ₃ ) steatite (MgO.
SiO ₂ ), forsterite (2MgO ・ Si
O _2), mullite _{(3Al 2 O 3 · 2SiO 2} ), magnesia (MgO), spinel _{(MgO · Al 2 O 3)} ,
Examples include oxide ceramics such as beryllia (BeO), non-oxide ceramics such as aluminum nitride and silicon carbide, and low-temperature fired ceramics such as glass ceramics, but are not limited to these. Absent.

In the substrate used in the electrolytic copper plating method of the present invention, the portion to be plated is made conductive before the electrolytic copper plating. For example, according to the method of the present invention, MVH
When is filled with metallic copper by electrolytic copper plating, first, the inner surface of the MVH is rendered conductive. This electroconductivity treatment can be performed using any known electroconductivity method, and examples of the electroconductivity method include electroless copper plating, direct plating method, conductive fine particle adsorption treatment, vapor phase plating. Various methods such as a method can be used, but the method is not limited to these.

In the electrolytic copper plating method of the present invention, the plating temperature (liquid temperature) is appropriately set according to the type of plating bath, but is usually 10 to 40 ° C., preferably 20 to 30. ℃. When the plating temperature is lower than 10 ° C., the conductivity of the plating solution decreases, so that the current density during electrolysis cannot be increased, the growth rate of the plating film slows down, and the productivity decreases. If the plating temperature is higher than 40 ° C, the brightener may be decomposed, which is not preferable. In the electrolytic copper plating method of the present invention,
For example, direct current, PPR (Pulse Period)
Any type of current may be used, such as ic reverse) current. The applied anode current density will be appropriately set according to the type of plating bath, but is usually 0.1 to 10.
10 A / dm ² , preferably 1 to 3 A / dm ² .
If it is less than 0.1 A / dm ^{2, the} area of the anode is too large, which is not economical, and if it is more than 10 A / dm ² , the amount of oxidative decomposition of the brightener component due to oxygen generation during electrolysis from the anode. Is increased, which is not preferable.

In the electrolytic copper plating method of the present invention, any type of electrode such as a soluble anode or an insoluble anode can be used. For example, the soluble anode may be a phosphorus-containing copper anode, and the insoluble anode may be iridium oxide, platinum-clad titanium, platinum, graphite, ferrite, lead dioxide, titanium coated with a platinum group oxide, or a material such as stainless steel. However, the anode is not limited to these.

In the plating method of the present invention, it is preferable that air or oxygen is passed through the plating solution to increase the concentration of dissolved oxygen in the plating solution. While not wishing to be bound by theory, the dissolved oxygen in the plating solution functions as an oxidizing agent, -X-S of the plating solution ^- believed to reduce a compound having the structure. As a method for increasing the concentration of dissolved oxygen in the plating solution, bubbling of the plating solution with air or oxygen is preferable, and the bubbling may be a mode of stirring the plating solution, or performed independently of stirring. It may be one. Further, the bubbling for increasing the dissolved oxygen concentration in the plating solution may be performed during the electrolytic plating treatment or may be performed during the suspension of the plating treatment.

In the plating method of the present invention, stirring may be carried out, and stirring is preferably carried out in order to make the supply of copper ions and additives to the surface of the object to be plated uniform. As a stirring method, air stirring or jet flow can be used. From the viewpoint of increasing the dissolved oxygen in the plating solution, stirring with air is preferable. Also, when stirring is performed with a jet flow, stirring with air may be used together. Furthermore,
It is also possible to perform replacement filtration and circulation filtration, and in particular, it is preferable to circulate and filter the plating solution with a filter, whereby the temperature of the plating solution is made uniform, and dust in the plating solution,
Precipitates and the like can be removed.

By the electrolytic copper plating method of the present invention, a composite material having a copper layer on a substrate can be obtained. When electrolytic copper plating is performed using the electrolytic copper plating solution of the present invention, the copper layer of the obtained composite material does not generate agglomerates, and when filling vias, filling of vias without voids is achieved. The Rukoto. Hereinafter, the present invention will be described in detail with reference to examples, but the examples do not limit the scope of the present invention.

[0037]

Example 1 Step 1: A 2 L bath prepared with the following standard composition for via fill was constructed, and MPS was added to this in an amount of 1 mg / L to prepare a simulated simulated bath fill performance. Then, as an index showing the amount of MPS and SPS in the simulated bath, a CVS measuring device QP-4000 (manufactured by ECI, USA) was used.
The value was measured. CVS value is SPS, M contained in the bath
Although it is an index showing the amount of PS and other substances, it is expressed as a value (mg / L) converted into the SPS amount in the examples. Step 2: 0.5 g / L of titanium oxide powder was added to the via fill performance-reducing bath and dispersed in the bath by stirrer stirring, and the bath was left for 5 hours while being irradiated with ultraviolet rays, and if necessary, with time. The CVS value was measured by sampling the bath solution. Step 3: A plating process was performed by PPR electrolysis. Step 4: The filling morphology was observed by the cross section method.

Comparative Example: Comparative Example 1: Immediately after step 1, plating treatment was performed by PPR electrolysis. Comparative Example 2: After step 1, the plate was naturally left in a dark room for 5 hours, and then plated by PPR electrolysis. Also, step 1
The CVS value of the bath solution was also measured after and 5 hours later.

Via-fill performance-reducing bath composition used in Example 1 and Comparative Examples 1 and 2 CuSO ₄ .5H ₂ O 130 g / L H ₂ SO ₄ 190 g / L Cl ^- 60 mg / L SPS 4 mg / L nonionic surfactant Agent 250 mg / L MPS 1 mg / L Note) SPS: Bis (3-sulfopropyl) disulfide disodium MPS: 3-mercapto-1-propanesulfonic acid sodium salt (manufactured by Tokyo Kasei) Titanium oxide used: titanium oxide (IV) Anatase type,
Kanto Kagaku Co., Ltd. Sex, Deer 1st class 0.5g / L Bath temperature: 23-27 ° C UV lamp: Pencil type / 4W output Body: Velight Co. Manufactured by Model No.
PS-2000-20 Primary Voltage 120volts
60 Hz lamp: Double Bore (registered trademark) Lamp
(Wavelength 254 nm type)

PPR electrolysis condition current density 2 A / dm ² forward reverse current density (F: R CD) 1: 1 forward reverse pulse time (F / RPT) 10 / 0.5 (ms) temperature : 20 ℃ Time: 60 minutes Via size: Via diameter 120 microns / depth 60 microns

Results When the above operation was performed on the evaluation substrate having 100 via holes, almost 100 vias were successfully filled in Example 1, whereas in Comparative Examples 1 and 2,
Most vias were unfilled. A schematic view of a cross section of the processed via is shown in FIG. According to the method of the present invention,
Good via filling properties are obtained, while Comparative Example 1
In and 2 the filling was poor. Also, in Example 1 and Comparative Example 2, the appearance of the filled vias was glossy and good, but in Comparative Example 1, a dull appearance was obtained. The CVS value results are shown in Table 1 below.

[0042]

[Table 1]

Regarding the CVS value, in Example 1, it was 5.8 mg / L at 0 hr after the construction bath (after step 1), but it was 3.4 mg / L after 5 hours, which was the same as SPS. A decrease of about 42% was observed. On the contrary,
In Comparative Example 2, 7.4 mg / L at 0 hr after bathing,
After 5 hours, it was 7.0 mg / L, which was only a decrease of about 5% in SPS conversion. Considering the above-described via filling results, it is considered that the decrease in the CVS value in Example 1 is due to the decrease in MPS, which has an adverse effect on the via filling, by the irradiation of ultraviolet rays in the presence of titanium oxide. To be That is, it is presumed that the decrease in CVS value and the decrease in MPS amount in the bath are related.

Example 2 Step 1: A 10 L bath prepared with the following standard composition for via fill was constructed, and 1 mg / L of MPS was added to this bath to prepare a simulated bath with reduced via fill performance. As an index showing the amount of MPS and SPS in the simulated bath, CV was measured using a CVS measuring device QP-4000 (manufactured by ECI, USA).
The S value was measured. The CVS value is the SPS contained in the bath,
Although it is an index showing the amount of MPS and other substances, in the examples, it was expressed as a value (mg / L) converted into the amount of SPS. Step 2: A chamber provided with an ultraviolet lamp in the center and a bath liquid water passing portion (0.89 L) surrounding the ultraviolet lamp, wherein the water passing portion is provided with the following mesh type titanium oxide. The chamber was connected to the plating bath. The operation of passing the bath liquid through the chamber at a flow rate of 9 L / min while irradiating with ultraviolet rays and aeration at 5.5 L / min was carried out for 5 hours. In addition, the CVS value was measured by sampling the bath solution with time as needed.

Via-fill performance-reducing bath composition used in Example 2 CuSO _4.5 H ₂ O 200 g / L H ₂ SO ₄ 100 g / L Cl ⁻ 50 mg / L SPS 1.5 mg / L Amine-based surfactant 1500 mg / L MPS 1 mg / L Titanium oxide used: mesh type titanium dioxide (Nitto Denko KK: Fine Keep) 2000 x 300 m
m, sheet area 120 dm ² bath temperature: 24-25 ° C. ultraviolet lamp: low output low pressure mercury lamp (254 nm type) / output 15 W (UVL15DH-33; Sen Special Light Source Co., Ltd.)

The change in CVS value in Example 2 is shown in Table 2 below.

[0047]

[Table 2]

As is clear from Table 2, even when the mesh type titanium dioxide is used, the CV with time is changed.
A significant decrease in S value (about 89% in 5 hours) was observed.

Example 3 Example 3 was carried out under the conditions described in Example 1, except as otherwise noted below. Step 1: A 2 L bath prepared with the standard composition for via fill used in Example 1 was constructed, and MPS was added thereto in an amount of 1 mg / L.
A bath in which the via-fill performance was lowered by simulation was prepared by adding the CVS measurement device QP-4000 (manufactured by ECI, USA) as an index showing the amount of MPS and SPS in the simulation bath.
Was used to measure the CVS value. The CVS value is an index indicating the amount of SPS, MPS and other substances contained in the bath, but in the examples, the value converted to the SPS amount (mg /
L). Step 2: 1.0 g / L of titanium oxide powder was added to the via fill performance lowering bath and dispersed in the bath by stirrer stirring, and the bath was left for 70 hours while being irradiated with light from a fluorescent lamp, and then in the bath. The CVS value of was measured.

Comparative Examples 3 and 4 In Comparative Examples 3 and 4, the same method as in Example 3 was performed except for the following modifications. Comparative Example 3: The titanium oxide powder was not added, and the bath liquid was placed in a dark room so as not to be irradiated with any light. Comparative Example 4: Titanium oxide powder was added, but the bath liquid was placed in a dark room so as not to be irradiated with any light.

Other experimental conditions different from those of Example 1 are as follows. Bath temperature: 24 ° C (at the start) -29 ° C (after 70 hours) Light source: fluorescent lamp (fluorescent lamp stand, Twin Bird Industry LK-274 type, 25W)

The CVS value at the time of building a bath is 7.4 in terms of SPS.
Although it was mg / L, in Example 3 irradiated with light of a fluorescent lamp in the presence of titanium oxide, 1.04 m was obtained after 70 hours.
A remarkable decrease of 86% was observed with g / L. On the other hand, in Comparative Example 3 containing no titanium oxide and not irradiated with light, 6.2 mg / L, and in Comparative Example 4 containing titanium oxide but not irradiated with light, 5.8 mg / L. L, only a slight decrease was observed.

Example 4, Comparative Examples 5 and 6 In Example 4, Comparative Examples 5 and 6, Example 3 and Comparative Example 3 were used, except that the standard composition for via fill was changed to that used in Example 2. And 4 were performed.

The CVS value at the time of bathing is 3.7 in SPS conversion.
Although it was mg / L, in Example 4 irradiated with the light of the fluorescent lamp in the presence of titanium oxide, 2.2 mg was obtained after 70 hours.
/ L, a remarkable decrease of 41% was observed. On the other hand, in Comparative Example 5 containing no titanium oxide and not irradiated with light, it was 4.0 mg / L, and in Comparative Example 6 containing titanium oxide but not irradiated with light, 3.9 mg / L. L and CV
An increase in S value was recognized.

[0055]

As described above, in the electrolytic copper plating method of the present invention, the electrolytic copper plating is performed by irradiating the electrolytic copper plating bath with ultraviolet rays and / or visible light. It has the advantageous effect of being able to reduce the decomposition products of the sulfur-containing compounds, which cause the destabilization of the bath over time. Further, the present invention is
By reducing the decomposition products of the sulfur-containing compound, in the formation of the electrolytic copper plating layer, agglomerates are generated to deteriorate the plating appearance, and the filled property of the via becomes unstable. It has an advantageous effect that the instability can be eliminated.

[Brief description of drawings]

FIG. 1 is a schematic view of a cross section of a filled via in Example 1 and Comparative Examples 2 and 3. FIG.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01L 23/12 H05K 3/18 G H05K 3/18 H01L 23/12 N (72) Inventor Shinjiro Hayashi Saitama 2-269 Yoshino-cho, Saitama-shi, Saitama Prefecture, Japan Rironard Co., Ltd. Technical Research Institute (72) Inventor Satoshi Tsukoshi, 2-269 4- Yoshino-cho, Saitama City Saitama Prefecture F-Term (R) 4K023 AA19 CB13 DA11 4K024 AA09 AB08 AB19 BA15 BB11 BB12 BC10 CA02 CA13 CA16 GA01 GA16 4M104 AA01 BB04 CC01 DD51 DD52 DD81 5E343 BB24 CC78 DD43 GG11

Claims (9)

[Claims] 1. A method for electrolytic copper plating, which comprises plating in the presence of titanium oxide. 2. The method according to claim 1, further comprising irradiating with ultraviolet light.
The method described. 3. The method according to claim 1, further comprising irradiating with visible light.
The method described. 4. The plating solution has a --X--S--Y-- structure (wherein X and Y are each independently selected from the group consisting of hydrogen atom, carbon atom, sulfur atom, nitrogen atom and oxygen atom). Atomic group of atoms, and X and Y can be the same only in the case of carbon atoms.)
4. The method according to any one of 3 to 3. 5. An —X—S—Y— structure, wherein X and Y are
Are independently hydrogen atom, carbon atom, sulfur atom and
And an atom selected from the group consisting of a nitrogen atom, X
And Y can be the same only if they are carbon atoms. ) Have
The compound that (1) M-SO_Three-(CH_Two)_a-S- (CH_Two)_b
-SO_Three-M; (2) M-SO_Three-(CH_Two)_a-O-CH_Two-S-
CH_Two-O- (CH_Two) _b-SO_Three-M; (3) M-SO_Three-(CH_Two)_a-S-S- (C
H_Two)_b-SO_Three-M; (4) M-SO_Three-(CH_Two)_a-O-CH_Two-S-
S-CH_Two-O- (CH _Two)_b-SO_Three-M; (5) M-SO_Three-(CH_Two)_a-SC (= S)-
S- (CH_Two)_b-SO _Three-M; (6) M-SO_Three-(CH_Two)_a-O-CH_Two-S-
C (= S) -S-CH_Two-O- (CH_Two)_b-SO_Three−
M; (In the formulas (1) to (6), a and b are integers of 3 to 8;
M is hydrogen or an alkali metal element) (7) A-S- (CH_Two)_a-SO_Three-M; and (8) A-S-CH_Two-O- (CH_Two)_a-SO_Three-M (In the formulas (7) and (8), a = an integer of 3 to 8;
M is hydrogen or an alkali metal element; A is a hydrogen atom,
Alkyl groups having 1 to 10 carbon atoms, aryl groups, 1 to 6 carbon atoms
Nitrogen atom, 1 to 20 carbon atoms and hydrogen atoms
A chain or cyclic amine compound composed of, or 1
~ 2 sulfur atoms and 1-6 nitrogen atoms and 1-20
Heterocyclization composed of carbon atoms and multiple hydrogen atoms
A compound selected from the group consisting of
The electrolytic copper plating method according to claim 4, which is a product. 6. The electrolytic copper plating method according to claim 5, wherein the compound having a —X—S—Y— structure is present in the electrolytic copper plating solution in an amount of 0.1 to 100 mg / L. 7. The electrolytic copper plating method according to claim 1, wherein the substrate to be electrolytic copper plated is a printed wiring board or a wafer. 8. The electrolytic copper plating method according to claim 7, wherein the substrate has a through hole or a via hole. 9. A composite material obtained by the method according to claim 7.