Target and blackening film

Abstract

To provide a sputtering target suitable for forming a blackened film with both of reduced reflectance and resistance to discoloration during environmental testing, especially under high temperature and humidity conditions.SOLUTION: A sputtering target has a composition represented by CuaNibCoc, where the a denotes the Cu ratio in at%, the b denotes the Ni ratio in at%, and the c denotes the Co ratio in at%, with a+b+c=100, 0.30≤a / (a+b+c)≤0.70, 10≤b≤65, 0.1≤c.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a target for sputtering and a blackened film that can be suitably formed using this target. [Background technology]

[0002] A touch panel is a device that combines two functions, display and input, by layering a touch sensor (touch panel sensor) on top of a display device (such as an LCD panel) to detect touch operations. With this touch panel, when an operator touches the display on the screen, information about the position of the operation is output as a signal to an external device, and the external device then performs the appropriate action desired by the operator based on the position information of the operation.

[0003] Traditionally, touch panel sensors have used transparent ITO (Indium Tin Oxide) electrodes. However, ITO has high resistivity and poor flexibility, which makes it unsuitable for the increasing size and curved surfaces of touch panels in recent years. Therefore, metal mesh wiring made from Cu or Al, which has superior resistivity and flexibility compared to ITO, is beginning to be used. However, with metal electrodes using this metal wire, the problem is that because the metal wire is opaque and has a metallic luster, external light strikes the metal wire and reflects off it, reducing the visibility of the display. As a means of solving this problem, it has been proposed to form a blackening film on the surface of the metal wire as a reflection-reducing film (see Patent Documents 1 and 2 below). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2016-216795 [Patent Document 2] Japanese Patent Publication No. 2016-216797 [Overview of the project] [Problems that the invention aims to solve]

[0005] Incidentally, blackened films, as reflection-reducing films, are expected to see increased application in automotive applications in the future, and therefore require environmental resistance characteristics that prevent discoloration of the film surface even under high temperature and high humidity conditions. For example, the blackened film described in Patent Document 1 is made of an oxide of CuNiW alloy, and the blackened film described in Patent Document 2 is made of an oxide of CuNiMo alloy, but these known blackened films do not exhibit sufficient environmental resistance characteristics.

[0006] The present invention was made with the aim of providing a blackened film that has low reflectivity and environmental resistance to discoloration even under high temperature and high humidity conditions, and a sputtering target suitable for forming this blackened film, against the background of the above circumstances. [Means for solving the problem]

[0007] The inventors of this invention conducted extensive research to solve the above problems and found that by further incorporating predetermined amounts of Ni and Co into a blackened film containing Cu oxide, environmental resistance characteristics that make it resistant to discoloration even under high temperature and high humidity conditions can be obtained. This invention is based on this finding. Therefore, the blackening film of the present invention has a composition of (Cu a Ni b Co c ) 100-x O x It consists of a metal oxide represented by the following, where a represents the ratio of Cu in at%; b represents the ratio of Ni in at%; c represents the ratio of Co in at%; and x represents the ratio of O in at%. The following conditions are met: a+b+c=100, 0.30≦a / (a+b+c)≦0.70, 10≦b≦65, 0.1≦c, and 30≦x≦50. According to the present invention as defined in this way, a blackened film can be made that has low reflectivity and environmental resistance characteristics that make it resistant to discoloration even under high temperature and high humidity conditions.

[0008] Here, if x is 30 ≤ x < 40, a blackened film can be obtained that has low reflectivity and environmental resistance test characteristics, and can be etched with ferric chloride, which has been widely used in the past.

[0009] Furthermore, if x is 40 ≤ x ≤ 50, a blackened film can be obtained that has low reflectivity, environmental resistance test characteristics, and low electrical resistivity.

[0010] Furthermore, the target of the present invention is a target for sputtering, and Cu a Ni b Co c It has a composition represented by the following, where a represents the ratio of Cu in at%; b represents the ratio of Ni in at%; and c represents the ratio of Co in at%. The following conditions are met: a+b+c=100, 0.30≦a / (a+b+c)≦0.70, 10≦b≦65, and 0.1≦c. By using the target of the present invention as defined in this way, a blackened film with low reflectivity and environmental resistance test characteristics can be suitably formed by reactive sputtering using a sputtering apparatus. [Brief explanation of the drawing]

[0011] [Figure 1] (A) is a diagram showing a laminate with a blackened film according to one embodiment of the present invention, and (B) is a diagram showing another example of the same laminate. [Figure 2] This figure shows yet another example of the same laminate. [Figure 3] This is an explanatory diagram for environmental resistance testing. [Modes for carrying out the invention]

[0012] Next, embodiments of the present invention will be described in detail. <1. Laminate> In FIG. 1, 10A shows an example of a laminate provided with a blackening film according to an embodiment of the present invention. In the figure, 12 is a transparent substrate, and on one surface (the upper surface in the figure) of this substrate 12, a metal layer 14 for forming an electrode is laminated in a film shape over the entire surface of the substrate 12. And on the surface of this metal layer 14 opposite to the substrate 12, that is, the upper surface in the figure, a blackening film 16 as an anti-reflection film is laminated and formed. This blackening film 16 is also laminated and formed in a film shape over the entire surface of the metal layer 14.

[0013] The transparent substrate 12 may be glass such as soda lime glass, or may be a resin material such as polyethylene terephthalate (PET), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), polycarbonate (PC), polymethyl methacrylate (PMMA), polyimide (PI), etc. As the resin material, polyethylene terephthalate (PET) is preferable.

[0014] The metal layer 14 preferably has a high conductivity with an electrical resistivity of 8.0 μΩ·cm or less, and pure Cu, Cu alloy, pure Al, Al alloy, etc. can be used as such materials.

[0015] The blackening film 16 is laminated and formed on the upper surface in the figure of the metal layer 14. The blackening film 16 is a layer for preventing light from the outside from hitting this metal wire (metal layer) and reflecting, and the visibility of the display part from the reflected light is reduced. The light reflectance is suppressed to less than 20%, preferably less than 15%. This blackening film 16 will be described in detail later.

[0016] In actuality, the laminate 10A is processed and used as an element of a touch panel sensor. 10 shown in FIG. 1(A) shows the processed laminate. In the processed laminate 10, the extra portions of the film-shaped metal layer 14 in the laminate 10A before processing are removed, and only a large number of extremely fine wires S1 remain as the metal layer 14, and these remaining extremely fine wires S1 are parallel to each other to form a striped pattern electrode 14D. The blackening film 16 also has the extra portions removed, leaving only the portion covering the upper surface of the ultra-fine line S1 in the figure as the ultra-fine line S2, and they function to absorb the light incident on the upper surface of the ultra-fine line S1 in the figure and suppress the reflection of light from the ultra-fine line S1. Such ultra-fine lines S1 and S2 can be formed, for example, by a wet etching method using an etching solution such as ferric chloride.

[0017] FIG. 1(B) shows another exemplary form of the laminate. As in the laminates 20A and 20 shown in this figure, it is also possible to laminate and form a blackening film 16 between the metal layer 14 and the transparent substrate 12. Also, as in the laminates 22A and 22 shown in FIG. 2, the transparent substrate 12, the first blackening film 16, the metal layer 14, and the second blackening film 16 are sequentially laminated and formed from the lower side to the upper side in the figure, and the second blackening film 16 serving as a dark layer is laminated and formed on the upper surface of the metal layer 14 on the side opposite to the substrate 12 in the figure. Also, between the lower side of the metal layer 14, that is, between the metal layer 14 and the substrate 12, it is also possible to laminate and form the first blackening film 16 serving as a similar dark layer.

[0018] <2. Blackening Film> Next, the blackening film 16 of the present embodiment will be described. The blackening film 16 is composed of a CuNiCo alloy oxide represented by (Cu a Ni b Co c ) 100-x O x . Here, a represents the ratio (at%) of Cu in the CuNiCo alloy, b represents the ratio (at%) of Ni in the CuNiCo alloy, c represents the ratio (at%) of Co in the CuNiCo alloy, and x represents the ratio (at%) of O in the CuNiCo alloy oxide. In this example, these a, b, c, and x are defined as a + b + c = 100, 0.30 ≤ a / (b + c) ≤ 0.70, 10 ≤ b ≤ 65, 0.1 ≤ c, and 30 ≤ x ≤ 50, respectively.

[0019] The reasons for limiting each chemical component in the blackening film 16 will be described below. Cu is an effective element for darkening the film and lowering its reflectivity by forming an oxide. If the ratio of Cu (a) in the CuNiCo alloy is excessively small, the relative ratio of Ni and Co (b+c) increases, which worsens the etching properties using ferric chloride. On the other hand, if the ratio of Cu (a) is excessively large, the relative ratio of Ni and Co (b+c) decreases, which worsens the environmental resistance test characteristics. For this reason, in this example, the ratio of Cu (a) is specified as 0.30 ≤ a / (a+b+c) ≤ 0.70. Preferably, it is 0.40 ≤ a / (a+b+c) ≤ 0.70.

[0020] Ni is an effective element for improving the corrosion resistance and discoloration resistance of the blackened film. To achieve this effect, in this example, the ratio (b) of Ni in the CuNiCo alloy is set to 10 (at%) or more. However, even when Ni is included, localized spot discoloration may occur under high temperature and high humidity conditions, and the discoloration may spread from these spotted areas. Since this spot discoloration is more pronounced as the ratio of Ni increases, in this example, the ratio (b) of Ni is specified as 10 ≤ b ≤ 65. Preferably, it is 30 ≤ b ≤ 50, and more preferably 40 ≤ b ≤ 50.

[0021] Co is an effective element for suppressing the occurrence of the above-mentioned spot discoloration. To obtain this effect, in this example, the ratio of Co (c) in the CuNiCo alloy is set to 0.1 (at%) or more. However, since excessive addition increases the reflectivity, it is preferable to set the upper limit to 20 (at%). A more preferable range is 1 ≤ c ≤ 10.

[0022] In a blackened film made of CuNiCo alloy oxide, increasing the ratio (x) of O can lower the reflectivity and improve environmental resistance to testing. However, if the ratio (x) is increased excessively, the etching properties deteriorate, so in this example, the ratio (x) is specified as 30 ≤ x ≤ 50. Furthermore, it has been confirmed that within these defined ranges, there is a trade-off relationship between electrical resistivity and etching properties. If you want to selectively increase etching properties, it is desirable to set the ratio (x) of O within the range of 30 ≤ x < 40. On the other hand, if you want to selectively obtain excellent electrical resistivity, it is desirable to set the ratio (x) within the range of 40 ≤ x ≤ 50.

[0023] For depositing the blackened film, a reactive sputtering method containing oxygen gas can be suitably used. Specifically, this includes balanced magnetron sputtering, unbalanced magnetron sputtering, and ion plating. The composition of the metal components in the blackened film formed by sputtering is almost the same as the composition of the sputtering target, and film deposition by sputtering offers excellent manufacturability.

[0024] <3. Target> The sputtering target of this embodiment is used for the purpose of forming the blackened film, and contains Cu, Ni, and Co. a Ni b Co c It has the composition represented by [formula]. However, the target may contain unavoidable impurities. Here, a represents the ratio of Cu in the CuNiCo alloy (at%), b represents the ratio of Ni in the CuNiCo alloy (at%), and c represents the ratio of Co in the CuNiCo alloy (at%). These a, b, and c are defined as a+b+c=100, 0.30≦a / (a+b+c)≦0.70, and 10≦b≦65, respectively. The reason why a, b, and c are defined within the same range as the composition of the blackened film described above is based on the fact that the composition of the metallic components of the blackened film formed by the sputtering method is approximately the same as the composition of the sputtering target.

[0025] This target can be manufactured by melting a block having a predetermined component composition and then cutting it out from there. In some cases, the product can be manufactured by mixing powders containing the constituent elements and pressurizing the mixed powder from cold to hot. The raw material powder may be a pure metal or alloy containing the constituent elements. Examples of molding methods include cold isohydrodynamic forming (CIP), hot isohydrodynamic forming (HIP), hot extrusion, and ultra-high pressure hot pressing. [Examples]

[0026] Next, embodiments of the present invention will be described in detail below. In these embodiments, laminates equipped with a blackened film made of a metal oxide with the composition shown in Tables 1 and 2 below were fabricated, and their reflectivity, environmental resistance test characteristics, electrical resistivity, and etching properties were evaluated.

[0027] [Table 1]

[0028] [Table 2]

[0029] <Fabrication of laminates> Targets were prepared by melting to achieve the metal component compositions shown in Tables 1 and 2 above. Next, using the fabricated target, a blackened film with a thickness of 30-50 nm was formed on the surface of an evaluation glass substrate (size: φ100 × 0.5t) or on the surface of a Cu metal film formed on the glass substrate by reactive sputtering.

[0030] The conditions for depositing a blackened film by sputtering are as follows: ·Vacuum degree: 1×10 -4 Pa or less • Film-forming gas: A mixture of Ar gas and oxygen gas Sputtering pressure: 0.15 Pa Spattering power: 150W

[0031] <Evaluation of reflectance> A laminate consisting of a blackened film, a Cu metal film, and a substrate was used, and the reflectance was measured in accordance with JIS K 7105. Specifically, a UV-Vis spectrophotometer was used to measure the reflectance at 50 nm intervals for visible light (wavelengths 400-800 nm), and the average value was calculated as the reflectance. The reflectance was measured when the reflected light was viewed from the blackened film side to the substrate side, that is, when light was incident on the substrate side from the blackened film side, and evaluated according to the evaluation criteria below. The results are shown in Tables 1 and 2. ○: Reflectance less than 15% △: Reflectance is 15% or more, but less than 20%. ×: Reflectance is 20% or higher

[0032] <Evaluation of environmental resistance test characteristics> As shown in Figure 3, a laminate consisting of a blackened film / Cu metal film / blackened film / substrate layer was used. This laminate was maintained in an atmospheric environment of 85°C × 85%RH (relative humidity), and the lightness (L*) and chromaticity (a*, b*) of the film surface of the laminate were measured every 100 hours using a spectrophotometer. The color difference ΔE* was calculated based on the start of the test (0h) as defined by the following formula.

number

[0033] <Evaluation of electrical resistivity> A laminate consisting of a blackened film (thickness 50 nm) and a substrate layer was fabricated. Electrical resistivity (Ω·cm) was measured at five locations on the blackened film using the four-probe method, and the average value was calculated. The laminate was then evaluated according to the following evaluation criteria. The results are shown in Tables 1 and 2. ○: Less than 1Ω·cm △: 1Ω·cm or more, less than 10Ω·cm ×: 10Ω cm or more

[0034] <Evaluation of Etching Properties> A laminate consisting of a blackened film (50 nm thick) and a substrate layer was prepared. A 20 mm square sample was cut from this laminate, and this sample was immersed in an etching solution consisting of 1% by mass of ferric chloride and the remainder being water. The time it took for the blackened film formed on the substrate to completely dissolve was measured and evaluated according to the evaluation criteria below. The results are shown in Tables 1 and 2. ○: When the entire amount is dissolved in 5-10 seconds ×: In cases other than those listed above

[0035] The following can be seen from the evaluation results in Tables 1 and 2. Comparative Examples 1-10 are examples in which the blackened film is composed of a single metal oxide. In Comparative Examples 1-10, the blackened film is composed using one of the single metals Cu, Ni, Co, W, or Cr. Good reflectivity results were obtained in Comparative Examples 5-8, which used Co or W, but the environmental resistance test characteristics evaluation results for Comparative Examples 5-8 were "×". In addition, the etching properties evaluation was also "×" in the examples using single metals other than Cu.

[0036] Comparative Examples 11-18 are examples in which the blackened film is composed of an oxide of an alloy consisting of Cu and one other metal. In the case of CuNi alloy (Comparative Examples 11, 12) and CuCo alloy (Comparative Examples 13, 14), although the environmental resistance test characteristics improved, spot discoloration still occurred, so the target service life of 1000 hours or more was not achieved.

[0037] Comparative Examples 19-28 are examples in which the blackened film is composed of an oxide of CuNiCo alloy, but the ratio of any element differs from that claimed in the present invention. Comparative Examples 19-22 and 24-27, in which the ratio of O (x) is 20 at%, which is lower than the lower limit of the present invention, received a "×" in the reflectance evaluation, indicating that the target reflectance suppression effect was not achieved.

[0038] Comparative Examples 22 and 23 are examples where the ratio of Ni (b) was 70 at%, exceeding the upper limit of the present invention. In these examples, the high ratio of Ni caused spot discoloration, and the environmental resistance test characteristics were evaluated as "×". Comparative Examples 27 and 28 are examples where the ratio of Ni (b) was 5 at%, which is below the lower limit of the present invention. In these examples as well, discoloration of the film surface occurred, and the evaluation of the environmental resistance test characteristics was "×".

[0039] As described above, in each comparative example, the evaluation of at least one of the reflectance or environmental resistance test characteristics fell short of the target.

[0040] In contrast, Examples 1 to 27, which consist of a CuNiCo alloy oxide and have a blackened film whose constituent element ratios satisfy the provisions of the present invention, have shown good results in both reflectivity and environmental resistance test characteristics.

[0041] Looking at each example in more detail, we can see that there is a trade-off relationship between electrical resistivity and etchability. As shown in Examples 1-3, 10-12, and 19-21, if the ratio of O (x) is 30 ≤ x < 40, a blackened film that can be etched with ferric chloride, which is widely used as an etching solution for metal wiring such as Cu, can be obtained. Also, as shown in Examples 4-9, 13-18, and 22-27, if the ratio of O (x) is 40 ≤ x ≤ 50, a blackened film with electrical resistivity suppressed to less than 1 Ω·cm can be obtained.

[0042] Although embodiments and examples of the present invention have been described in detail above, these are merely illustrative examples. The present invention can be implemented in various modified forms without departing from its spirit.

Claims

1. Cu ａ Ni ｂ Co ｃ The composition is represented by the following, where a represents the ratio of Cu in at%; b represents the ratio of Ni in at%; and c represents the ratio of Co in at%. a+b+c=100, 0.30≦a / (a+b+c)≦0.70, 10 ≤ b < 25, 0.1 ≤ c, A target for sputtering characterized by the following:

2. Composition is (Cu ａ Ni ｂ Co ｃ ) １００－ｘ O ｘ It consists of a metal oxide represented by the following, where a represents the ratio of Cu in at%; b represents the ratio of Ni in at%; c represents the ratio of Co in at%; and x represents the ratio of O in at%. a+b+c=100, 0.30≦a / (a+b+c)≦0.70, 10 ≤ b < 25, 0.1 ≤ c, 30 ≤ x ≤ 50, A blackened film characterized by the following:

3. The blackening film according to claim 2, characterized in that x is 30 ≤ x < 40.

4. The blackening film according to claim 2, characterized in that x is 40 ≤ x ≤ 50.

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