JPH11117061A - Thin film for black matrix, and target for film formation for black matrix - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prepare a thin film for black matrix, combining excellent optical properties and corrosion resistance and capable of using as a substitute for chromium, and also to provide a target for film formation for the above purpose. SOLUTION: This thin film for black matrix has a composition consisting of, by weight, 0. 5-60% Cu, 0.1-25% Ti, and the balance essentially Ni or further containing <=0.5% B. This thin film for black matrix can be obtained by using a target having a composition consisting of, by weight, 0.5-60% Cu, 0.1-25% Ti, and the balance essentially Ni or further containing <=0.5% B.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a black matrix thin film as a light shielding film used for a display device such as a liquid crystal display or a plasma display, and a black matrix deposition target.

[0002]

2. Description of the Related Art In liquid crystal and plasma displays, etc.,
A color filter is used as a member that enables color display by transmitting light from a light source through red, blue, and green color materials. In this color filter, a light-shielding film is formed on a glass substrate or the like for the purpose of improving contrast and preventing color mixture of color materials. This light-shielding film is generally called a black matrix. The most important characteristic of the black matrix is an optical characteristic. The optical characteristics are to sufficiently shield unnecessary light from the light source, and to reduce the reflectance because the reflected light from the outside reduces the contrast of the displayed image if the reflectance is high on the display side. Points are mainly required.

The mainstream of this black matrix is to form a film by a sputtering method and pattern it by a photolithography method.
Further, as described in JP-A-8-220326, metal chromium, chromium oxide, molybdenum, carbon, and the like are used for the black matrix. It is considered suitable.

After the formation of the black matrix, a color filter is manufactured by the following steps, for example. First, a coloring material is formed on a glass substrate having a patterned black matrix. In this step, a colored resin is spin-coated on a glass substrate on which a black matrix is formed, and a positive resist is spin-coated thereon. In this state, exposure is performed through a mask, the positive resist is patterned by development, and etching is performed using an alkaline aqueous solution or the like to pattern the colored resin. Thereafter, the positive resist is peeled off by washing with an acidic aqueous solution and warm water and an organic solution. In the case of a color filter, it is necessary to form three types of color material films of red, green, and blue, so the above process is repeated three times. Furthermore, apply a protective film, and finally,
A color filter is completed by forming an O transparent electrode film.

The above manufacturing method is a photolithography method, and one of various color filter manufacturing methods has been proposed. However, in many manufacturing methods, since a black matrix is formed by etching, the black matrix is required to have an etching property with respect to a specific etching solution. On the other hand, when the color material film is formed, the black matrix is exposed to an alkali, an acidic solution, or the like, so that the black matrix is required to have some corrosion resistance in manufacturing.

[0006]

The chromium film conventionally used has a low reflectance and is hard to transmit light, and has very good optical characteristics as a black matrix. Chromium also has excellent corrosion resistance to corrosive solutions used when forming the above-mentioned color material films. However, it has been pointed out that chromium is not preferable in terms of environmental problems because hexavalent chromium is generated when the black matrix is etched.
In view of such a problem, formation of a black matrix using molybdenum or a resin instead of chromium has been studied. However, it has not yet sufficiently provided optical characteristics, corrosion resistance, and processing accuracy. An object of the present invention is to provide a black matrix thin film having excellent optical properties and corrosion resistance that can replace chromium, and a film-forming target therefor.

[0007]

The present inventor has made various studies in view of the above problems. As a result, Ni-Cu-T
It has been found that a black matrix having the same optical properties as chromium and corrosion resistance to a specific corrosive liquid can be obtained with a thin film of an i-based alloy, which has never existed before. That is, the present invention provides a Cu 0.5 to 60 wt%, Ti 0.1 to
This is a black matrix thin film composed of 25 wt% and the balance substantially composed of Ni. In the present invention, the corrosion resistance can be further improved by adding 0.5 wt% or less of B to the above composition.

The above-mentioned thin film for a black matrix according to the present invention has a Cu content of 0.5 to 60 wt% and a Ti content of 0.1 to 25 wt%.
%, Or 0.5% by weight of B, with the balance being substantially Ni.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, an important feature of the present invention is that the inclusion of Cu in Ni makes it possible to reduce the reflectance and increase the optical density.
It has been found that by including Ti in a Cu alloy, corrosion resistance can be improved without impairing optical characteristics. As a specific composition, nickel (Ni) is added to copper (Cu) 0.5 to 60 wt% and titanium (T
A new alloy system containing 0.1 to 25 wt% of i) or 0.5 wt% or less of boron (B) is proposed. Since the present invention combines Ni, Cu, Ti, and B, there is an advantage that harmful substances such as Cr are not generated.

In the present invention, Ni is a basic element for obtaining basic optical characteristics as a black matrix. Ni secures basic corrosion resistance by forming a passivation film. In the present invention, the aforementioned N
Based on i, Cu is essentially contained. Cu reduces the high reflectivity of pure Ni, improves the optical characteristics as a black matrix,
It is an element that improves the corrosion resistance by being dissolved in Ni. If the content of Cu exceeds 60 wt%, the corrosion resistance is conversely deteriorated. Therefore, in the present invention, the content is specified to be 60 wt% or less. Further, when the content of Cu is less than 0.5 wt%, the effect of improving the optical characteristics is small and the effect of improving the corrosion resistance is also small, so the content is specified as 0.5 wt% or more. A more preferred range is 10 to 40 wt%.

Although the basic optical characteristics and corrosion resistance of the black matrix can be ensured by the composite of Ni—Cu, according to the study of the present inventors, the corrosion resistance has not been sufficient yet. Further selected Ti as the third element. Ti is the above-mentioned Ni and C
It is an element that improves corrosion resistance without impairing the basic optical characteristics due to the combination of u. It is considered that the reason why Ti improves the corrosion resistance is to strengthen the passivation film formed by Ni. When Ti is contained in an amount of 0.1 wt% or more, an effect of improving corrosion resistance is recognized. However, when the content exceeds 25 wt%, an intermetallic compound such as TiNi ₃ is generated, and becomes multi-phase, and the corrosion resistance is reduced. However, when the film is formed by sputtering, more Ti than the equilibrium state can be dissolved in the Ni-Cu matrix so that 25 Ti
When Ti is contained in an amount of t or less, precipitation of intermetallic compounds is small, and there is an effect of improving corrosion resistance. A more preferred Ti amount is
1 to 10 wt%.

[0012] In the present invention, B is a potential additive element. B is concentrated in a defect portion such as a crystal grain boundary in the thin film, and improves the corrosion resistance of the defect portion. That is, in comparison with Ti, which improves corrosion resistance by strengthening the passivation film, it is possible to further improve corrosion resistance by minimizing the influence on basic optical characteristics in that corrosion resistance is improved by a different action. If the added amount of B is too large, it is excessively concentrated at the crystal grain boundaries, and conversely deteriorates the corrosion resistance. In the present invention, in the case of Ni-Cu-based alloys, the effect of improving corrosion resistance was observed if the addition was 0.5 wt% or less.
It was defined as addition of not more than wt%. More preferably, 0.1
wt% or less, more preferably 0.001 to 0.02
wt%.

The optical characteristics required for the black matrix thin film of the present invention can be evaluated by the reflectance and the optical density. The reflectance is evaluated, for example, by making light of a specific wavelength incident on the thin film at a specific angle and measuring the reflected light. The optical density is a value indicating the amount of attenuation of transmitted light,
It can be represented by an optical density D = -log (I / I0). I is the intensity of the transmitted light, and I0 is the intensity of the incident light. That is, the higher the numerical value of the optical density, the more the light is blocked. The higher the reflectance, the higher the optical density, but the higher the reflectance, the lower the image contrast. Therefore, it is an advantageous material for the black matrix that the reflectance is as low as possible and the optical density is high.

The above-mentioned black matrix thin film can be manufactured by, for example, a method such as sputtering, ion plating, and plating. In particular, application of a sputtering method using a target has an advantage that a thin film having a thickness of the order of submicrons can be obtained by a dry method. According to the studies made by the present inventors, it has been confirmed that a thin film substantially matching the target composition can be obtained by using a target having a composition corresponding to the above-described film composition as a sputtering target. That is, when the thin film for a black matrix of the present invention is to be obtained, a sputtering target that matches the film composition can be used. The target may be either an ingot material or a powder metallurgy material, but is preferably a target in which Ni and Cu are dissolved in a solid solution in order to suppress variation in components. In particular, for a black matrix, a molten material that is advantageous in increasing the size because the target size is large and that is easily reduced in cost is preferable.

[0015]

Embodiments of the present invention will be described below. First, a black matrix film-forming target having the composition shown in Table 1 was manufactured by the following steps. Vacuum melting-Hot working: Heating temperature 1000 ° C, Finish thickness 30 [mm]-Cold rolling: Finish thickness 8 [mm]-Annealing 800 ° C x 1 hour-Processing: Finish thickness 5 [mm] is obtained. A thin film having a thickness of about 100 nm was formed on a Corning # 7059 glass substrate by a DC magnetron sputtering apparatus using the target. Table 2 shows the composition of the obtained film. Table 3 shows the optical characteristics, and Table 4 shows the evaluation results of the corrosion resistance.

[0016]

[Table 1]

[0017]

[Table 2]

[0018]

[Table 3]

[0019]

[Table 4]

Here, the optical characteristics were evaluated at a wavelength of 600 nm. The reflectance was measured at an incident angle of 5 degrees, and the optical density was evaluated by allowing light to enter the film perpendicularly and measuring the transmitted light. As a method for evaluating the corrosion resistance, a 10 wt% aqueous solution of calcium hydroxide was used as an alkaline solution, a 10 wt% aqueous solution of sulfuric acid was used as an acidic solution, and immersed in each aqueous solution for 10 minutes at room temperature. The change was evaluated. This is because the optical density depends on the film thickness and the material, and the change in the optical density before and after the corrosion resistance test changes due to the change in the thickness of the thin film or the chemical deterioration of the very surface layer. is there.

As can be seen by comparing Tables 1 and 2, it can be seen that a thin film having substantially the same composition as the target was obtained. Also, as can be seen from Table 3, No. 1 to N
o. No. 14 Ni-Cu based and No. 14 Mo in No. 16 is No. 16 which is conventionally used in optical characteristics. The result was equivalent to 15 Cr. On the other hand, as can be seen from the evaluation of the corrosion resistance in Table 4, as shown in FIG. It can be seen that the Mo thin film of No. 16 is corroded so strongly as to be peeled off by both the aqueous solution of alkaline calcium hydroxide and the aqueous solution of acidic sulfuric acid, which is not preferable.

In the case of the Ni-Cu-Ti system, the sample No. which falls within the composition range of the product of the present invention. 1-6 show the same level of corrosion resistance as Cr. In particular, No. 1 in which Ti is in a preferable range.
4 has the same value as Cr. The value is almost the same even for 3. However, in the case of No. 3 having a Cu content exceeding the range of the product of the present invention. 7 shows that the acid resistance deteriorates. In addition, No. 3 exceeding the Ti content in the range of the product of the present invention. 8
However, it can be seen that the acid resistance is reduced.

The comparative material No. Compared with Ni-Cu-Ti which is within the range of the present invention even with Ni-Cu of 9,
It can be seen that the acid resistance is poor. Further, No. 3 containing B in the composition range of the present invention was added. In 10-14, Ni-Cu-T
No. i in which the contents of Ti and Cu are similar in the i-type. Compared with No. 3, the acid resistance is improved or has the same value. No. 1 in a particularly preferred composition range. 11 and N
o. 12 has the same value as Cr. From this, B
It can be seen that the corrosion resistance is improved by adding.

[0024]

The Ni-Cu-Ti of the present invention is changed by changing Cr conventionally used as a black matrix.
By performing a thin film etching process or the like using a system black matrix, it becomes possible to produce a liquid crystal color filter without generating hexavalent Cr. This is important for solving the environmental problems that have been concerned in recent years.

Claims (4)

[Claims] Claims 1. A Cu 0.5 to 60 wt%, Ti 0.1 to
25. A thin film for a black matrix, comprising 25 wt% and the balance substantially composed of Ni. 2. The black matrix thin film according to claim 1, wherein B is contained in an amount of 0.5% or less. 3. Cu 0.5-60 wt%, Ti 0.1-
A black matrix film-forming target consisting of 25 wt% and the balance substantially made of Ni. 4. The black matrix film-forming target according to claim 1, wherein B is contained in 0.5% or less.