JP2000336486A - Substrate applied with catalytic nucleus, catalyzing treatment to substrate and electroless plating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To apply catalytic nuclei applying an electroless plating film in which an initial precipitating layer is dense, high in density and free from defects by adhering metallic catalytic grains composed of silver and palladium on the surface of the nonconductive part to be applied with electroless plating at the nuclear density equal to or above the specified one. SOLUTION: A substrate having a nonconductive part to be applied with electroless plating is subjected to sensitizing treatment with a bivalent tin ion soln., is thereafter subjected to Ag activating treatment and is finally subjected to Pd activating treatment, by which catalytic grains composed of Ag and Pd nuclei having <=1 nm grain size are adsorbed at the nuclear density of >=2000 nuclei/ μm2. Preferably, the average surface roughness of a metallic catalytic grain layer is controlled to <=0.5 nm, and the ratio between silver grains and palladium is controlled to the range from (1:10) to (10:1) by a weight ratio. As the electroless plating soln., each plating soln. of nickel, copper and zinc oxide is used. The substrate is the one in which a Ta, TaN or TiN film has been formed on the surface of a silicon substrate, and, as the plating soln., an electroless copper plating soln. is suitable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the formation of a Cu circuit on a printed circuit board,
Useful for circuit formation of electronic parts such as wiring process, formation of hard disk base layer by electroless Ni-P plating used for hard disk for computer, or formation of transparent electrode of liquid crystal display and transparent semiconductive electrode for solar cell etc. The present invention relates to a substrate provided with a catalytic nucleus, a method for catalyzing the substrate, and an electroless plating method.

[0002]

2. Description of the Related Art In recent years,
2. Description of the Related Art With the high integration of electronic component circuits due to miniaturization and high performance of mobile phones and notebook computers, electroless plating free of defects at the atomic level has become necessary. As a method of forming a circuit on a non-conductive substrate by using an electroless plating technique, a method of adsorbing metallic palladium to an object to be plated and then performing an electroless plating method is performed.

[0003] However, the conventional Pd catalyst has a large particle size of the catalyst and a low core density of the adsorbed catalyst. The electroless plating film obtained by this catalyst solution has a low initial deposition nucleus density and has many defects in the initial deposition layer. An electroless plating film having no defect in the initial deposition layer instead of this is desired. ing.

[0004] The present invention meets the above-mentioned demands and provides a substrate provided with a catalyst nucleus capable of providing an electroless plating film having a dense initial deposition layer and a high density without defects, and an electroless plating of the substrate. It is an object of the present invention to provide a method for catalyzing a substrate to which a catalyst nucleus can be applied to a non-conductive portion, and an electroless plating method for the substrate to which the catalyst nucleus has been applied.

[0005]

Means for Solving the Problems and Embodiments of the Invention The present inventors have conducted intensive studies in order to achieve the above object, and as a result, have found that a sensitizing solution containing stannous ions (Sn ²⁺ ). After performing a sensitizing treatment using, by using an activator containing silver ions and an activator containing palladium ions in combination, and finally immersed in an activator containing palladium ions, We find that fine catalyst particles are adsorbed at high density on a non-conductive substrate, and by applying electroless plating using this catalyzing treatment method, an electroless plating film with no defects in the initial deposition layer can be obtained. I found that.

[0006] That is, although there is hardly any study on the relationship between the particle size and the core density of the catalyst and the initial nucleus density and the initial deposition layer of the electroless plating film, the particle size and the nuclei density of the electroless plating film are not considered. It has been reported by Honma et al. To have a significant effect on the initial precipitation state of [J. Elect
rochem. Soc. , 144, 4123 (199
7)]. However, in the conventional method, the catalyst core density is at most about 1500 nuclei (particles) / μm ² , the catalyst particle diameter is generally 4 nm or more, and the average roughness of the catalyst layer formed on the smooth glass surface is also low. It was 1 nm or more. However, performing the catalyst imparting treatment using an activator containing silver ions and an activator containing palladium ions as described above, in this case, in particular, the sensitizing treatment and the activity containing silver ions The treatment with the activator is repeated a plurality of times, and then the treatment with the activator containing palladium ions is carried out to reduce the catalyst core density to 2
000 nuclei (particles) / μm ² or more, the catalyst particle diameter can be made 2 nm or less, particularly 1 nm or less, and the average roughness of the catalyst layer can be made 0.5 nm or less. Is found.

As a result, it has a [111] orientation on Ta, TaN or TiN which is a barrier film on the Si underlayer, has excellent adhesion to Ta, TaN, and TiN, and has a dense initial deposition layer. Electroless Cu plating with excellent vertical growth and adhesion and excellent uniform deposition in through holes on ultra LSI chip substrates and printed wiring boards with a seed layer formed by defect-free electroless Cu plating film. Electroless Ni with excellent adhesion on the formed build-up printed wiring board and crystallized glass substrate, and a dense and high-density initial deposition layer
-By forming P plating, there is no nodule or pit defect on the surface of the film, and the electroless zinc oxide film is formed electrolessly on the hard disk substrate for computers and the transparent substrate with improved smoothness, and the transparency is improved. The present inventors have found that a transparent electrode of a colorless and transparent liquid crystal display which is excellent and has no yellowish film can be obtained, and a transparent semiconductive electrode for a solar cell can be obtained.

Accordingly, the present invention provides the following substrate, catalyzing treatment method, and electroless plating method. Claim 1: A substrate comprising metal catalyst particles made of silver and palladium adhered to the surface of a non-conductive portion to be electrolessly plated at a nucleus density of 2000 nuclei / μm ² or more. In another preferred embodiment, the substrate has an average surface roughness of 0.5 nm or less. In a preferred embodiment, the weight ratio of silver particles to palladium is 1:10 to 10: 1. Claim 4: Ag activation in which a substrate having a non-conductive part to be electrolessly plated is subjected to a sensitizing treatment with a sensitizing solution containing divalent tin ions and then immersed in an activator containing silver ions. By performing a Pd activation treatment by immersing the catalyst particles in a palladium ion-containing activator, the catalyst particles composed of Ag and Pd nuclei having a particle diameter of 1 nm or less are 2,000 nuclei / μm ^2. A method for catalytically treating a substrate, characterized in that the substrate can be adsorbed at the above nuclear density. In a preferred embodiment, the sensitizing process and the Ag activation process are repeated a plurality of times. (6) An electroless plating method comprising immersing a substrate having a non-conductive portion having metal catalyst particles adhered to the surface to be electrolessly plated in an electroless plating solution by the processing method according to the above (4) or (5). Method. Claim 7: The electroless plating solution is an electroless nickel plating solution,
The electroless plating method according to claim 6, which is an electroless copper plating solution or an electroless zinc oxide plating solution. In another preferred embodiment, the substrate having a non-conductive portion to be electrolessly plated has a Ta, TaN or TiN film formed on the surface of a silicon substrate, and the electroless plating solution is an electroless copper plating solution. Electroless plating method. In another preferred embodiment, the base having the non-conductive portion to be electrolessly plated has a through hole, and the peripheral wall of the through hole is a non-conductive portion to be electrolessly plated, and the electroless plating solution is electroless copper. The electroless plating method according to claim 6, which is a plating solution. In a preferred embodiment, the substrate having a non-conductive portion to be electrolessly plated is a crystallized glass substrate, and the electroless plating solution is an electroless nickel plating solution. In a preferred embodiment, the substrate having a non-conductive portion to be electrolessly plated is a transparent substrate, and the electroless plating solution is an electroless zinc oxide plating solution.

Hereinafter, the present invention will be described in more detail.
The high-density catalyzing treatment method according to the present invention comprises, after subjecting a substrate having a non-conductive portion to be subjected to electroless plating to a sensitizing solution containing a divalent tin ion,
An Ag activation process of immersing in an activator containing silver ions is performed, and finally a Pd activation process of immersing in an activator containing palladium ions is performed. This is for attaching metal catalyst particles.

In this case, examples of the substrate include non-conductive substrates such as glass, plastic, and ceramics, and a composite thereof, or a composite of these non-conductive substrate and metal. The entire surface or a predetermined portion of the surface is a non-conductive portion to be subjected to electroless plating.

In the case where these substrates are catalyzed to form an electroless plating film, it is preferable to carry out the following processing steps. Note that washing is performed between each step. (1) Washing: treatment can be performed under known degreasing treatment conditions. (2) Surface conditioning: Using a known surface conditioning agent, a charge is imparted to the surface of the material. (3) Sensitizing: Sensitizing is performed by immersing in a solution containing a known tin ion. (4) Catalytic treatment: Activation is performed with an activator mainly containing silver ions. The above steps (3) and (4) may be repeated a plurality of times as necessary. (5) Catalytic treatment: Activation is performed with an activator containing palladium ions. The above steps (4) and (5) may be repeated a plurality of times as necessary. (6) Electroless plating

In this case, as the surface conditioning agent, an aqueous solution containing 1 to 50 g / L of a cationic surfactant or a cationic polymer compound as a main component can be used. It can be immersed for minutes.

The sensitizing solution used in the sensitizing treatment includes SnCl ₂ , SnSO ₄
Is dissolved in an acid solution such as hydrochloric acid or sulfuric acid.
It is suitable to use a solution containing 1 to 50 g / L of tin ions having a valence of 1 to 3 and a pH of 1 to 3 and immersing at 10 to 60 ° C. for 10 seconds to 5 minutes, preferably 30 seconds to 2 minutes. is there.

In the present invention, the activator containing a silver ion used in the above step (4) may be silver ion 0.0
It is preferably from 001 to 0.5 mol / L, particularly preferably from 0.001 to 0.1 mol / L.

In this case, as a supply source of silver ions, silver sulfate, silver sulfite, silver nitrate, silver thiosulfate, silver methanesulfonate and the like can be used, but it is not limited thereto. Activation performance can be improved by mixing a divalent metal ion with the solution containing silver ions as a main component.

As this example, Ni ion, Co ion, iron ion, zinc ion, copper ion and the like can be preferably used. These concentrations are the same as those of the silver ions. As the anion for the silver ion, a sulfate ion, a nitrate ion, a halogen ion, a methanesulfonate ion and the like are preferably used, but are not particularly limited. The pH is suitably about 5 to 11.

The solution temperature of the silver-based solution of the present invention is:
Although it can be set in a wide range, it is usually preferable to be 15 to 60 ° C. Also, the immersion time in these activators can be appropriately selected, but is preferably 10 seconds to 5 minutes, and more preferably 30 seconds to
It is preferable to perform the immersion treatment for 2 minutes.

As the palladium-containing activator used in the above step (5), a divalent palladium salt such as PdCl ₂ or PdSO ₄ is dissolved in an acid solution such as hydrochloric acid or sulfuric acid to form a divalent Pd ion. 0.01 to 1 g / L, pH 1 to 1
Using a solution that is 3 for 1 second to 5 minutes at 10-60 ° C.
The immersion treatment is preferably performed for 1 second to 1 minute.
If soaked for a long time, Pd may be agglomerated, and densification of the initially deposited layer may not be achieved.

The solution containing the Pd ion as a main component includes:
The performance of the activator can be improved by adding a trace amount, preferably 0.1 to 100 mg / L, of Pb (NO ₃ ) ₂ , Ag ₂ SO ₄ or borofluoric acid, respectively.

In the present invention, the above steps (3) and (4) are washed a plurality of times with water between them, preferably 2 to 6 times.
It is preferably performed three times, especially three or four times, whereby the density and density of the catalyst layer can be more reliably achieved.

The steps (4) and (5) are repeated to avoid Pd agglomeration.
The number is preferably set to 6 times, particularly 2 to 3 times.

As the electroless plating solution used in the above step (6), any known electrocatalytic electroless plating solution can be used. For example, an electroless copper plating solution using formaldehyde as a reducing agent; Electroless nickel-phosphorous plating solution using sodium phosphite as a reducing agent, electroless nickel-boron plating solution using dimethylamine borane as a reducing agent, electroless palladium plating solution, and electroless nickel-phosphorous plating solution using sodium hypophosphite as a reducing agent An electroless plating solution such as an electrolytic palladium-phosphorous plating solution, an electroless gold plating solution, an electroless silver plating solution, and an electroless nickel-cobalt-phosphorous plating solution using sodium hypophosphite as a reducing agent can be used.

The conditions for electroless plating using these electroless plating solutions can be known ordinary conditions according to the type of the plating solution and the like. The plating film thickness is appropriately selected according to the application and the like. Is done.

As the electroless plating solution, an electroless zinc oxide plating solution capable of depositing zinc oxide (ZnO) can be used. As such a plating solution, a zinc salt such as zinc nitrate 0.01 to 0.5 mol / L, preferably 0.0
5 to 0.2 mol / L, and 0.001 to 0.5 mol / L, preferably 0.01 to 0.2 mol / L, especially 0.001 to 0.5 mol / L of a borane-based reducing agent such as dimethylamine borane and other reducing agents. 0.
PH of about 4 to 9 containing 03 to 0.1 mol / L, especially p
A processing solution of about 6.5 can be suitably used, and 10
A method of immersion treatment at ~ 80 ° C for 5 to 120 minutes can be adopted.

The most suitable electroless plating solution is Zn (N
O ₃ ) ₂ 0.1 mol / L and dimethylamine borane 0.0
It is preferable to use a treatment solution of pH 6.5 containing 3 mol / L. The zinc oxide film obtained from this composition has a small particle size, is C-axis oriented (001), and has a reduced number of voids, so that transparency and conductivity are improved.

According to the present invention, the above catalyzing treatment allows
A metal catalyst particle composed of silver and palladium is 2,000 nuclei / μm ² or more on a non-conductive portion of the substrate to be subjected to electroless plating,
Preferably 2000 to 5000 nuclei / μm ² , especially 250
It can be attached at a nucleus density of 0-3500 nuclei / μm ² . In this case, the attached metal catalyst particle layer has an average surface roughness of 0.5 nm or less, preferably 0.05 to 0.5 n.
m, especially 0.1 to 0.3 nm, and
The catalyst particle diameter is 2 nm or less, preferably 0.1 to 2 nm,
More preferably, the thickness can be set to 0.3 to 1 nm, and a dense and dense catalyst layer can be formed. The above-mentioned nucleus density, average roughness, and average particle diameter can be measured by AFM (atomic force microscope) observation.

The metal catalyst particles formed in the present invention are composed of silver and palladium. In this case, the weight ratio of silver to palladium is from 1:10 to 10: 1, preferably from 1: 4 to 3: 1. : 1, more preferably 1: 3 to 1: 1. The composition ratio of silver and palladium is E
It can be analyzed by SCA (X-ray photoelectron spectroscopy).

In the present invention, an activator containing silver as a main component and an activator containing palladium are used in combination,
By immersing in an activator containing ions, fine catalyst particles can be adsorbed on a non-conductive substrate at a high density.

The mechanism of miniaturization and densification of the adsorbed catalyst is unknown, but sensitizing treatment by immersion in a sensitizing solution containing tin ions and Ag activity immersing in an activator containing silver ions Silver ions are adsorbed at a high density by repeating the
By immersing in an activator containing d ions, it is considered that finer catalyst particles are adsorbed at a high density due to the interaction between silver ions and palladium ions.

According to the catalyzing treatment method of the present invention, a high-density electroless plating film having a dense initial deposition layer can be obtained.
It is effectively used in the field of electronic components such as formation of Cu circuits on SI chips, formation of Ni-P underlayers for computer hard disks, formation of transparent electrodes for liquid crystal displays and transparent semiconductive electrodes for solar cells.

[0031]

According to the present invention, metal catalyst particles composed of fine silver and palladium can be provided on a non-conductive substrate at a high density.

[0032]

EXAMPLES The present invention will be described below in detail with reference to examples and comparative examples, but the present invention is not limited to the following examples.

Example 1 As a non-conductive substrate, a crystallized glass, an epoxy substrate, a Si substrate on which a TiN film was formed, and an alkali-free glass were used in accordance with the type of electroless plating described below. After applying the catalyst, electroless plating was performed.

Catalyst application and plating step i. Degreasing The substrate was immersed in the following degreasing agent solution at 50 ° C for 3 minutes. ii. Rinse with water: 25 ° C, 15 seconds iii. Surface conditioning Dipped in the following surface conditioning solution at 30 ° C for 5 minutes. iv. Washing: 25 ° C, 15 seconds v. Sensitizing It was immersed in the following sensitizing solution at 20 ° C. for 1 minute. vi. Washing with water: 25 ° C, 15 seconds vii. Addition of catalyst The sample was immersed in the following silver salt activating solution at 20 ° C for 1 minute. viii. Water washing: The above steps (v) to (viii) were performed three times in total at 25 ° C. for 15 seconds. ix. Addition of catalyst The sample was immersed in the following palladium activating solution at 20 ° C for 5 seconds. x. Rinsing: 25 ° C., 15 seconds The above steps (ix) and (x) were performed twice in total. xi. Electroless plating

The following four types of electroless plating were performed. (A) Electroless Ni-P plating: Immersion was carried out at pH 4.6 and 90 ° C. for 1 minute using the following electroless Ni-P plating solution. (B) Electroless Ni-B plating: Immersion was carried out at pH 6.6 and 65 ° C. for 1 minute using the following electroless Ni-B plating solution. (C) Electroless Cu plating: Immersion was performed at pH 13, 35 ° C. for 1 minute using the following electroless Cu plating solution. (D) Electroless ZnO plating: It was immersed in the following electroless ZnO plating solutions (1) to (3) at pH 6.5 and 65 ° C. for 30 minutes.

In this case, as the non-conductive substrate, crystallized glass is used for the above (a) electroless Ni-P plating,
(B) Epoxy substrate for electroless Ni-B plating,
(C) For the electroless Cu plating, the barrier layer Ti
Alkali-free glass was used for the Si substrate on which the N film was formed and (d) electroless ZnO plating.

The surface states after the adsorption of the catalyst and the formation of the electroless plating film were observed using an AFM (atomic force microscope). In addition, (a) the adhesion of the electroless Ni-P plating to the crystallized glass and (c) the Ti on Si of the electroless Cu plating
A tape test was performed for adhesion to the N film.

[0038] ASAHI CLEANER manufactured degreaser Uemura & Co., Ltd. C-4000 5 g / L surface modifier Uemura & Co. THRU-CUP CD-202 50 mL / L sensitizing solution _{SnCl 2 · 2H 2 O 15 g} / L HCl 15 mL / L silver activating solution _{AgNO 3 1.5 g / L NiSO 4} · 6H 2 O 0.3 g / L CoSO 4 · 7H 2 O 0.2 g / L pH 7 palladium activating solution PdCl ₂ 1 g / L HCl 1 mL / L Pb (NO ₃ ) ₂ 0.1 g / L Ag ₂ SO ₄ 0.03 g / L borofluoric acid 0.01 mL / L pH 1.5 Electroless Ni-P plating solution Uemura & Co. Nimuden DX (reducing agent: sodium hypophosphite) pH 4.6 electroless Ni-B plating solution Uyemura & Co. BEL 801 (reductant: dimethylamine borane) pH .6 electroless Cu plating solution Uyemura & Co. THRU-CUP PEA (reducing agent: formaldehyde) pH 13 electroless ZnO plating solution _{(1) Zn (NO 3)} 2 0.1 mol / L dimethylamine borane 0.03 mol / L pH 6.5 electroless ZnO plating solution (2) Zn (NO ₃ ) ₂ 0.1 mol / L dimethylamine borane 0.05 mol / L pH 6.5 electroless ZnO plating solution (3) Zn (NO _{3 2} ) 0.1 mol / L dimethylamine borane 0.1 mol / L pH 6.5

[Comparative Example 1] Electroless plating was performed in the same manner as in Example 1 except that the catalyst was treated only with a silver salt activator without using a palladium activator. Was.

[Comparative Example 2] Electroless plating was performed in the same manner as in Example 1 except that the catalyzing treatment was performed using only the palladium activating agent without using the silver salt activating agent. Was.

Table 1 shows the results of AFM observation of the adsorption state of the catalyst particles on the epoxy substrates obtained in Example 1 and Comparative Examples 1 and 2. Table 2 shows the AFM observation results of the initial deposition state of various electroless platings. Table 3 shows whether or not the electroless Ni-P plating film on the crystallized glass and the electroless Cu plating film on the TiN film on Si were peeled off by a tape test.

[0042]

[Table 1]

[0043]

[Table 2] Note: When the appearance of the electroless ZnO plating film was evaluated,
Example 1 was colorless and transparent, and no yellow color was observed. In contrast, Comparative Example 1 was transparent but yellowish.

[0044]

[Table 3]

From the results shown in Table 1, it is confirmed that the present invention can adsorb fine catalyst particles on a non-conductive substrate at a high density.

From the results shown in Table 2, it is recognized that the present invention can form electroless plating having no defect in the initial deposition layer on the non-conductive substrate according to the present invention.

From the results shown in Table 3, it can be seen that an electroless Ni—P film having excellent adhesion on a crystallized glass according to the present invention, TiN on Si
It is recognized that an electroless Cu film having excellent adhesion can be formed on the barrier film.

Continuing from the front page (72) Inventor Masanobu Izaki 1-4-1, Kumigaoka, Kawai-machi, Kitakatsuragi-gun, Nara Prefecture 1-72 (72) Inventor Hiroshi Hatase 1006 Odakadoma, Kadoma-shi, Osaka Matsushita Electric Industrial Co., Ltd. (72) Inventor Yoshiji Saijo 1-5-1, Hirakata-shi, Osaka Pref.

Claims (11)

[Claims] 1. A metal catalyst particle comprising silver and palladium is 2,000 nuclei / μm on the surface of a non-conductive portion to be electrolessly plated.
^A substrate adhered at a nuclear density of ² or more. 2. The substrate according to claim 1, wherein the attached metal catalyst particle layer has an average surface roughness of 0.5 nm or less. 3. The substrate according to claim 1, wherein the weight ratio of silver particles to palladium is 1:10 to 10: 1. 4. Ag activity in which a substrate having a non-conductive portion to be electrolessly plated is subjected to a sensitizing treatment with a sensitizing solution containing divalent tin ions and then immersed in an activator containing silver ions. The catalyst particles comprising Ag and Pd nuclei having a particle diameter of 1 nm or less are deposited on the non-conductive portion at 2000 nuclei / μm by performing a Pd activation treatment by immersing in a palladium ion-containing activator. ^Two
A method for catalytically treating a substrate, characterized in that the substrate can be adsorbed at the above nuclear density. 5. The processing method according to claim 4, wherein the sensitizing process and the Ag activation process are repeated a plurality of times. 6. An electroless plating method comprising immersing a substrate having a nonconductive portion having metal catalyst particles adhered to a surface to be electrolessly plated by the treatment method according to claim 4 or 5 in an electroless plating solution. Plating method. 7. The electroless plating method according to claim 6, wherein the electroless plating solution is an electroless nickel plating solution, an electroless copper plating solution, or an electroless zinc oxide plating solution. 8. A substrate having a non-conductive portion to be electrolessly plated has a Ta, TaN or TiN film formed on a silicon substrate surface, and the electroless plating solution is an electroless copper plating solution. Electroless plating method as described. 9. A printed wiring board in which a base having a non-conductive portion to be electrolessly plated has a through hole, a peripheral wall portion of the through hole is a non-conductive portion to be electrolessly plated, and the electroless plating solution is an electroless plating solution. The electroless plating method according to claim 6, which is a copper plating solution. 10. The electroless plating method according to claim 6, wherein the substrate having a non-conductive portion to be electrolessly plated is a crystallized glass substrate, and the electroless plating solution is an electroless nickel plating solution. 11. The electroless plating method according to claim 6, wherein the substrate having a non-conductive portion to be electrolessly plated is a transparent substrate, and the electroless plating solution is an electroless zinc oxide plating solution.