JP2872940B2 - Substrate metallization method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method of forming a metal film pattern on a substrate, and more particularly to a method of forming a metal film pattern by an electroless (plating) method.

[0002]

BACKGROUND OF THE INVENTION Electroless or chemical metallization is a simple and inexpensive method of metallizing a substrate.
In such metallization, electroless metallization baths containing complex metal ions and a reducing agent, such as copper and nickel baths, are used to reduce the metal ions to metal on the catalyst surface.
Generally, a metal Pd nucleus is provided on the surface to be metallized to catalyze the surface. In the standard operation, nucleation (hereinafter, referred to as activation) is performed in advance by sequentially contacting the surface to be metallized with an aqueous solution of SnCl _{2 and} an aqueous solution of PdCl ₂ . The activated surface is then immersed in an electroless metallization bath to metallize the surface. This activation method is not selective, ie the entire surface of the substrate is nucleated and then metallized. For electroless copper, strong reducing formaldehyde is generally used as a reducing agent in the bath, and for electroless nickel, the following reducing agent is generally used as a reducing agent in the bath. Phosphite is used. In the metallization of these substrates, selective or patterned metallization is often desirable.

An example of such a metallization method is as follows. First, a uniform metal layer having a desired thickness is deposited on a substrate. Next, a photoresist layer is provided, and this layer is exposed and developed according to a pattern, thereby patterning the resist layer. Then, the metal layer is selectively etched using the resist pattern as a mask, and then the resist layer is removed. In another method, the substrate is activated with a Pd nucleus of the catalyst. Next, a photoresist layer is provided on the substrate, and the layer is exposed and developed according to a pattern, thereby patterning the resist layer. Next, the surface is immersed in an electroless metallizing bath, and the metal is deposited in the holes of the resist pattern to a desired heat by this treatment. Finally, the resist layer is removed, and the Pd nucleus is removed by a short etching process.

[0004]

Both of the two methods have the disadvantages that they require a relatively large number of processing steps and that it is not easy to provide a resist layer on a large substrate surface. doing. In addition, these methods are described in detail in “Thin Film Handbook” edited by the 131st Committee of Thin Films of the Japan Society for the Promotion of Science, published by Ohmsha.

[0005] In addition to the above two methods, a palladium acetate thin film is deposited on a substrate by spin coating, the film is locally decomposed by a laser, and then the palladium acetate on the exposed portion is removed to form metal palladium. A method is known in which a pattern of a Pd nucleus formed through such a process is metallized in an electroless nickel or copper bath. The disadvantages of this method are that a relatively large number of processing steps are required and that high laser power is required to decompose palladium acetate, so that significant time is required to process large substrate surfaces. It is.

The present invention has been made in view of the above problems, and provides a substrate metallization method capable of forming a metal film pattern on a substrate in a relatively small number of processing steps without using photolithography technology. Is what you do.

Another object of the present invention is to provide a method for metallizing a substrate, which can form a desired metal film pattern even on a large-area substrate.

[0008]

The substrate metallization method according to the present invention is a substrate metallization method for forming a metal film pattern on a substrate, wherein a titanate-based coupler layer is formed over the entire main surface of the substrate. Then, a predetermined portion of the titanate-based coupler layer is subjected to ultraviolet ozone treatment to completely remove the predetermined portion from the substrate, and thereafter, the substrate main surface on which the pattern of the titanate-based coupler layer is formed is removed. Contacting with an aqueous solution of stannous chloride (SnCl ₂ ), then washing with water, then contacting with an aqueous solution of palladium chloride (PdCl ₂ ), and then immersing the main surface of the substrate in an electroless metallization bath It is characterized by the following.

The method according to claim 1, wherein the aqueous solution of palladium chloride (PdCl ₂ ) contains a water-soluble polymer for stabilizing the dispersion of palladium ions (Pd ²⁺ ). .

[0010] In the above structure, the ultraviolet ozone treatment may include installing the substrate in an ultraviolet ozone generator,
It is preferable to irradiate ultraviolet rays to the titanate-based coupler layer through a mask member having a predetermined pattern.

In the above structure, the step of immersing the main surface of the substrate in an electroless metallizing bath includes the first step of immersing the main surface of the substrate in an electroless nickel bath, and the step of immersing the main surface of the substrate in an electroless gold bath. It is preferable that the method comprises the second step.

In the above structure, it is preferable that the substrate is a transparent substrate of a liquid crystal display device, and the metal film pattern is a black matrix formed on the transparent substrate.

[0013] The structure of the present invention is characterized in that stannous chloride (SnC
l ₂ ) Starting from the fact that Sn ions derived from the aqueous solution were able to obtain sufficient evidence to be convinced that the amount of deposition varies greatly depending on the state of the substrate surface. It was found that the formation of a selective Pd nucleus and the formation of a selective metallized film were induced. The details are described below.

The surface of the glass substrate on which the ITO (tin-added indium oxide) coating is partially formed is brought into contact with an aqueous solution of stannous chloride (SnCl ₂ ), followed by washing with water under certain conditions, and further, palladium chloride (PdCl ₂ ). ₂ ) After contact with an aqueous solution, the surface of the substrate was immersed in an electroless metallization bath to attempt metallization, but no metallization was achieved.
As a result of the analysis, it was found that Pd nuclei to the extent necessary for metallization were not present on the substrate surface, and that the amount of Sn ²⁺ ions required for the formation of Pd nuclei did not adhere to the substrate surface. . That is, by washing with water under certain conditions, S
It is estimated that n ²⁺ has run off.

Next, a titanate coupler layer is provided on the surface of the glass substrate on which the ITO (tin-added indium oxide) film is partially formed, and the surface of the substrate is coated with stannous chloride (S).
nCl ₂ ) aqueous solution, followed by washing with water under a certain condition, further contact with an aqueous solution of palladium chloride (PdCl ₂ ), and then immersing the substrate surface (titanate-based coupler layer surface) in an electroless metallizing bath. I tried metallization,
In this case, sufficient metallization was achieved. As a result of the analysis, it was found that the amount of Pd nuclei or Sn ²⁺ ions was present on the substrate surface enough to cause sufficient metallization.

Next, a titanate-based coupler layer is provided on the surface of the glass substrate on which the ITO (tin-added indium oxide) film is partially formed, and the titanate-based coupler layer is applied to an actinic ray (ultraviolet ray) generated from a UV ozone reactor. And ozone). The low pressure mercury discharge lamp of this UV ozone reactor emits 185 nm and 254 nm ultraviolet rays. Next, the surface of the substrate is brought into contact with an aqueous solution of stannous chloride (SnCl ₂ ), washed with water under a certain condition, and further brought into contact with an aqueous solution of palladium chloride (PdCl ₂ ). The metallization was attempted by immersing the irradiated region in the electroless metallizing bath in (2), but it was found that the metallization did not occur at all. As a result of the analysis, there is no Pd nucleus necessary for metallization on the substrate surface in the region of the substrate surface to be exposed to actinic radiation (ultraviolet rays and ozone), that is, the portion where the titanate-based coupler layer has been removed. In addition, it was found that the amount of Sn ²⁺ ions necessary for the formation of Pd nuclei did not adhere to the substrate surface.

In the present invention, substrates made of various materials can be used. Specific examples include the above-mentioned glass substrate and a glass substrate on which an ITO (tin-added indium oxide) coating is formed. Further, as the titanate-based coupler, various types such as a monoalkoxy type, a monoalkoxypyrophosphate type, a coordination type, and a chelate type can be used.
The following chemical formulas (1) to (4) show typical molecular structures of monoalkoxy type, coordination type and chelate type (two types) among these various titanate-based couplers.

[0018]

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[0019]

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[0020]

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[0021]

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[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The substrate metallization method of the present invention is a substrate metallization method for forming a metal pattern on a substrate, wherein a titanate-based coupler layer is formed on the entire main surface of the substrate. By subjecting a predetermined portion of the titanate-based coupler layer to ultraviolet ozone treatment, the predetermined portion is completely removed from above the substrate, and thereafter, the main surface of the substrate on which the pattern of the titanate-based coupler layer is formed is first chlorided. Contacting with an aqueous solution of tin (SnCl ₂ ), then washing with water, then contacting with an aqueous solution of palladium chloride (PdCl ₂ ), and then immersing the main surface of the substrate in an electroless metallization bath Accordingly, adhered amount of Sn ²⁺ ions required to form the Pd nuclei on the surface of the titanate coupler layer left in the region to be metallized of the substrate main surface, not metallized substrate main surface It becomes the Sn ²⁺ ions are washed away in frequency, so that the metal layer is grown on the titanate coupler layer. Therefore, a metal pattern can be formed with a relatively small number of steps without using photolithography technology. Further, it is not easy to provide a photoresist layer on the surface of a large-area substrate, and it has been difficult to form a desired metal pattern on the surface of a large-area substrate by the conventional method. A desired metal pattern can be easily formed on the substrate surface having a large area.

As a preferred example of the above structure, palladium ion (PdCl ₂ ) is added to the palladium chloride (PdCl ₂ ) aqueous solution.
When a water-soluble polymer such as polyvinyl alcohol or polyvinylpyrrolidone for stabilizing the dispersion of d ²⁺ ) is contained, palladium ions (Pd ²⁺ ) can be supplied without causing unevenness on the substrate surface. A Pd nucleus can be stably formed in a desired region on the substrate surface.

As a preferred example of the above-mentioned structure, the ultraviolet ozone treatment is such that the substrate is placed in an ultraviolet ozone generator, and ultraviolet light is applied to the titanate coupler layer through a mask member having a predetermined pattern. When,
The ultraviolet ozone treatment can be easily performed.

As a preferred example of the configuration, the step of immersing the main surface of the substrate in an electroless metallizing bath includes a first step of immersing the main surface of the substrate in an electroless nickel bath, and a step of immersing the main surface of the substrate in an electroless nickel bath. When the method includes the second step of dipping, a metal pattern whose surface is covered with a gold film can be formed. Therefore, the metal pattern has excellent rust resistance and low resistance.

As a preferred example of the above configuration, when the substrate is a transparent substrate of a liquid crystal display device and the metal film pattern is a black matrix formed on the transparent substrate, a liquid crystal capable of displaying an excellent contrast is provided. The display device can be manufactured efficiently.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a flowchart showing a flow of a processing operation of a substrate metallization method according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view for each processing step. In FIG. 2, 1 is a glass substrate, 2 is ITO
The layers 3, 3 are titanate-based coupler layers, 4 is a chromium mask, 5 is ultraviolet rays, 6 is a sensitizing layer (stannic chloride layer), 7 is an activation layer (palladium layer), and 8 is formed by electroless plating. A nickel-gold layer.

First, as a sensitizing solution for forming a sensitizing layer (a stannous chloride layer), a hydrochloric acid solution prepared by adjusting stannous chloride to a concentration of about 10 g / l is prepared. As an activation solution for forming the (palladium layer), a hydrochloric acid solution prepared by adjusting palladium chloride to a concentration of about 0.3 g / l was prepared.
Electroless nickel plating solution and electroless gold plating solution were obtained from Okuno Pharmaceutical Co., Ltd. Further, a chromium mask manufactured by an ordinary method was prepared. Also, a reagent containing about 10% by weight of a titanate coupler in a solvent was purchased. More specifically, five types of titanate-based couplers of various types described above (monoalkoxy type, monoalkoxypyrophosphate type, coordination type, and chelate type) (two types of chelate type and one type of other type) Seed) was purchased. In addition, a borosilicate glass substrate having an ITO layer partially formed on its main surface by fine processing was purchased.

First, after cleaning the main surface of the borosilicate glass substrate 1 on which the ITO layer 2 is partially formed by fine processing on the main surface, the five kinds of reagents are applied to the main surface with a special solvent. The solution diluted to 0.3% by weight was applied with a spinner at a rotation speed of the spinner of about 2500 RPM.
Heat treatment was performed at 20 ° C. for 1 hour. Thus, as shown in FIG. 2A, the titanate-based coupler layer 3
Was formed uniformly.

Next, the substrate 1 is placed in a UV ozone reactor (not shown), and the main surface of the substrate 1 is irradiated with ultraviolet rays 5 through a chrome mask 4 (FIG. 2B). By the ozone treatment, the UV-exposed region of the titanate-based coupler layer 3 was completely removed (FIG. 2C).

Next, the substrate 1 is immersed in a sensitizing solution, and the exposed portion of the main surface of the substrate 1 and the titanate-based coupler layer 3 are exposed.
Was washed with water to form a sensitizing layer (stannic chloride layer) 6 on the surface of the titanate-based coupler layer 3 (FIG. 2D). This rinsing is performed under controlled conditions. That is, by immersion in the sensitizing solution, stannous chloride is densely adsorbed on the surface of the titanate-based coupler layer 3, and stannous chloride is slightly adsorbed on the surface of the borosilicate glass (substrate 1). I have. The water washing preserves the stannous chloride adsorbed on the titanate-based coupler layer 3 and almost completely removes the stannous chloride adsorbed on the borosilicate glass surface.

Next, the substrate 1 was immersed in an activation liquid to selectively deposit palladium nuclei on the sensitizing layer (stannic chloride layer) 6 to form an activation layer (palladium layer) 7. According to transmission electron microscopy (TEM) or XPF analysis, there is no palladium nucleus in the exposed portion of the main surface of the substrate 1, that is, in the region exposed to ultraviolet light, and the sensitizing layer (stannous chloride layer) 6, ie, unexposed It was confirmed that palladium nuclei existed in the region (Fig. 2
(E)).

Next, when the substrate 1 is immersed in an electroless nickel plating solution, no nickel metal is deposited on the exposed portion of the main surface of the substrate 1 and nickel is deposited only on the surface of the sensitizing layer (stannic chloride layer) 6. The metal is deposited to form a nickel metal layer, and after washing with water, when the substrate 1 is immersed in an electroless gold plating solution,
A gold layer was formed on the surface of the nickel metal layer, and a nickel-gold plating layer 8 was formed (FIG. 2 (f)). And finally, it is washed with water.

As described above, according to the method of this embodiment, a metal film pattern can be formed in a desired region on the main surface of a substrate without using photolithography or the like. In addition,
Considering that the borosilicate glass substrate in this embodiment is a transparent substrate of a liquid crystal display device, it is clear that the black matrix of the color filter for the liquid crystal display device can be easily formed by the method of this embodiment.

[0035]

As described above, according to the substrate metallization method according to the present invention, a substrate metallization method for forming a metal film pattern on a substrate is provided. A coupler layer was formed, and a predetermined portion of the titanate-based coupler layer was subjected to ultraviolet ozone treatment, whereby the predetermined portion was completely removed from the substrate, and thereafter, a pattern of the titanate-based coupler layer was formed. The main surface of the substrate is brought into contact with an aqueous solution of stannous chloride (SnCl ₂ ), then washed with water, and then an aqueous solution of palladium chloride (Pd
Cl ₂ ), and thereafter, the main surface of the substrate is immersed in an electroless metallization bath, so that a metal film pattern can be formed in a relatively small number of steps without using photolithography technology. As a result, the substrate can be metallized in a short time. Further, since a desired metal film pattern can be easily formed on the surface of a large-area substrate, the large-area substrate can be stably metallized.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a processing operation flow of a substrate metallization method according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating another processing step of a substrate metallization method according to an embodiment of the present invention.

[Explanation of symbols]

Reference Signs List 1 borosilicate glass substrate 2 ITO layer 3 titanate-based coupler layer 4 chromium mask 5 ultraviolet ray 6 sensitizing layer (stannic chloride layer) 7 activation layer (palladium layer) 8 nickel-gold plating formed by electroless plating layer

Claims (5)

(57) [Claims] 1. A substrate metallization method for forming a metal film pattern on a substrate, comprising: forming a titanate-based coupler layer over the entire main surface of the substrate; and applying ultraviolet ozone treatment to a predetermined portion of the titanate-based coupler layer. Is performed, the predetermined portion is completely removed from the substrate, and thereafter, the main surface of the substrate on which the pattern of the titanate-based coupler layer is formed is brought into contact with an aqueous solution of stannous chloride (SnCl ₂ ), Next, the substrate is washed with water, then brought into contact with an aqueous solution of palladium chloride (PdCl ₂ ), and then the main surface of the substrate is immersed in an electroless metallizing bath. 2. The method according to claim 1, wherein the aqueous solution of palladium chloride (PdCl ₂ ) contains a water-soluble polymer for stabilizing the dispersion of palladium ions (Pd ²⁺ ). 3. The ultraviolet ozone treatment according to claim 1, wherein the substrate is placed in an ultraviolet ozone generator, and the titanate-based coupler layer is irradiated with ultraviolet light via a mask member having a predetermined pattern. Substrate metallization method. 4. A step of immersing the main surface of the substrate in an electroless metallizing bath includes a first step of immersing the main surface of the substrate in an electroless nickel bath, and a second step of immersing the main surface of the substrate in an electroless gold bath. The method according to claim 1, wherein the method comprises: 5. The method according to claim 1, wherein the substrate is a transparent substrate of a liquid crystal display, and the metal film pattern is a black matrix formed on the transparent substrate.