Metal mask, method for forming internal electrode pattern of multilayer ceramic capacitor, method for forming internal electrode of multilayer ceramic capacitor, method for manufacturing multilayer ceramic capacitor, and method for managing metal mask for forming internal electrode of multilayer ceramic capacitor

Abstract

This metal mask is for manufacturing an internal electrode of a multilayer ceramic capacitor and has a through hole having a rectangular shape in a plan view formed in a metal base material. With respect to the through hole, the dimension of the through portion in the short-side direction of the rectangular shape in a plan view is 300 µm or less. With respect to the cross-sectional shape of a peripheral edge facing the through portion, a height difference is formed on a first side in the thickness direction of the base material, and a tapered part extending in the direction away from the through portion is formed on a second side in the thickness direction. The dimension in the thickness direction of the height difference positioned in the short-side direction is 12.2 µm or less. The tapered part positioned in the short-side direction has a taper angle of 47.0° or less with respect to the short-side direction.

Description

Metal mask, method for forming internal electrode pattern of multilayer ceramic capacitor, method for forming internal electrodes of multilayer ceramic capacitor, method for manufacturing multilayer ceramic capacitor, and method for managing metal mask for forming internal electrodes of multilayer ceramic capacitor

[0001] The present invention relates to a metal mask, a method for forming an internal electrode pattern of a multilayer ceramic capacitor, a method for forming an internal electrode of a multilayer ceramic capacitor, a method for manufacturing a multilayer ceramic capacitor, and a method for managing a metal mask for forming an internal electrode of a multilayer ceramic capacitor.This application claims priority based on Japanese Patent Application No. 2024-145739 filed in Japan on August 27, 2024, and Japanese Patent Application No. 2024-145117 filed in Japan on August 27, 2024, the contents of which are incorporated herein by reference.

[0002] An MLCC (Multilayer Ceramic Capacitor) is a chip-type capacitor in which internal electrodes and dielectric sheets (often called green sheets) are laminated in multiple layers. While MLCCs are becoming increasingly miniaturized, they are still required to have sufficient capacitance as a capacitor. In order to increase capacitance without increasing size, it is necessary to reduce the film thickness of the internal electrodes and increase the number of layers. While screen printing has traditionally been used to form the internal electrodes, the use of a sputtering method is expected to allow for thinner internal electrode films and a greater number of layers than before.

[0003] One method for producing metal masks used in sputtering, vapor deposition, etc. is to wet-etch a thin metal substrate (see, for example, Patent Document 1). Material flying from a target passes through through holes formed by etching, and is deposited at a predetermined position with predetermined dimensions and shape.

[0004] Japanese Patent No. 5382259

[0005] In the above-described sputtering deposition, the deposition material is also deposited on the metal mask. If the deposition material is deposited near the through-holes in the metal mask, the deposition of the internal electrodes may be hindered, which may result in a deterioration in the shape of the internal electrodes, such as a narrower line width. Furthermore, if the deposition material is deposited near the through-holes in the metal mask, the deposition of the internal electrodes may be hindered, which may result in a decrease in the film thickness and a decrease in the deposition efficiency (deposition rate).

[0006] If the shape of the internal electrodes deteriorates, the effective area of ​​the electrodes decreases, resulting in a problem of a decrease in electrical capacity. Furthermore, if the number of times that the film deposits on the metal mask are washed is increased in order to solve the above problem, the time until the metal mask can be discarded will be shortened.

[0007] The shape of the internal electrode is strongly influenced by the cross-sectional shape of the periphery of the through hole in the metal mask. The film thickness of the internal electrode is also strongly influenced by the cross-sectional shape of the periphery of the through hole in the metal mask. Indicators that characterize the cross-sectional shape of the metal mask include the step height and taper angle.

[0008] The present inventors have conducted extensive research into the cross-sectional shape of metal masks from the above-mentioned perspectives, and have completed the present invention.

[0009] In view of the above circumstances, the present invention aims to provide a metal mask capable of forming internal electrodes having a good internal electrode shape and good electrical properties, a method for forming an internal electrode pattern of a multilayer ceramic capacitor, a method for forming an internal electrode of a multilayer ceramic capacitor, and a method for manufacturing a multilayer ceramic capacitor.In view of the above circumstances, the present invention also aims to provide a metal mask capable of forming internal electrodes having a good film formation rate and good electrical properties, a method for forming an internal electrode pattern of a multilayer ceramic capacitor, a method for forming an internal electrode of a multilayer ceramic capacitor, and a method for manufacturing a multilayer ceramic capacitor.

[0010] Another object of the present invention is to provide a method for managing metal masks for forming internal electrodes of multilayer ceramic capacitors, which can extend the period before the metal masks are discarded.

[0011] A first aspect of the present invention is a metal mask for manufacturing an internal electrode of a multilayer ceramic capacitor, the metal mask having a metallic substrate with a through hole formed therein that is rectangular in plan view, wherein the dimension of the through portion of the through hole in the direction of a short side of the rectangle in plan view is 300 μm or less, and the cross-sectional shape of a peripheral edge facing the through portion has a step height formed on a first side in the thickness direction of the substrate and a tapered portion extending in a direction away from the through portion formed on a second side in the thickness direction, the dimension of the step height located in the direction of the short side in the thickness direction being 12.2 μm or less, and the tapered portion located in the direction of the short side has a taper angle with respect to the short side direction of 47.0° or less.

[0012] A second aspect of the present invention is a method for forming an internal electrode pattern of a multilayer ceramic capacitor, which comprises forming the internal electrodes by physical vapor deposition using the metal mask of the first aspect.

[0013] A third aspect of the present invention is a method for forming an internal electrode of a multilayer ceramic capacitor, comprising forming the internal electrode by using the method for forming an internal electrode pattern of a multilayer ceramic capacitor according to the second aspect.

[0014] A fourth aspect of the present invention is a method for manufacturing a multilayer ceramic capacitor, comprising forming an internal electrode by using the method for forming an internal electrode of a multilayer ceramic capacitor according to the third aspect.

[0015] A fifth aspect of the present invention is a method for managing a metal mask for forming internal electrodes of a multilayer ceramic capacitor, the method comprising: managing an upper limit of a dimension in the thickness direction of a film deposited on the metal mask of the first aspect at 15 μm; and cleaning the metal mask when the dimension in the thickness direction of the film reaches the upper limit.

[0016] A sixth aspect of the present invention is a metal mask for manufacturing an internal electrode of a multilayer ceramic capacitor, the metal mask having a metallic substrate with a through hole formed therein that is rectangular in plan view, wherein the dimension of the through portion of the through hole in the direction of a short side of the rectangle in plan view is 300 μm or less, and in the cross-sectional shape of the peripheral edge facing the through portion, a step height is formed on a first side in the thickness direction of the substrate, and a tapered portion extending in a direction away from the through portion is formed on a second side in the thickness direction, the dimension of the step height located in the direction of the short side in the thickness direction is 8.3 μm or less, and the tapered portion located in the direction of the short side has a taper angle with respect to the short side direction of 50.2° or less.

[0017] A seventh aspect of the present invention is a method for forming an internal electrode pattern of a multilayer ceramic capacitor, which comprises forming the internal electrodes by physical vapor deposition using the metal mask of the sixth aspect.

[0018] An eighth aspect of the present invention is a method for forming an internal electrode of a multilayer ceramic capacitor, comprising forming the internal electrode by using the method for forming an internal electrode pattern of a multilayer ceramic capacitor according to the seventh aspect.

[0019] A ninth aspect of the present invention is a method for manufacturing a multilayer ceramic capacitor, comprising forming an internal electrode by using the method for forming an internal electrode of a multilayer ceramic capacitor according to the eighth aspect.

[0020] A tenth aspect of the present invention is a method for managing a metal mask for forming internal electrodes of a multilayer ceramic capacitor, the method comprising: managing an upper limit of a dimension in the thickness direction of a film deposited on the metal mask of the sixth aspect to be 15 μm; and cleaning the metal mask when the dimension in the thickness direction of the film reaches the upper limit.

[0021] According to the present invention, it is possible to provide a metal mask capable of forming internal electrodes with good internal electrode shapes and good electrical properties, a method for forming an internal electrode pattern of a multilayer ceramic capacitor, a method for forming internal electrodes of a multilayer ceramic capacitor, and a method for manufacturing a multilayer ceramic capacitor.

[0022] According to the present invention, it is possible to provide a method for managing metal masks for forming internal electrodes of multilayer ceramic capacitors, which can extend the period until the metal masks are discarded.

[0023] 5 is a schematic diagram showing the positional relationship of a metal mask and the like during film formation; FIG. 6 is a diagram showing the relationship between the cross-sectional shape of a metal mask through-hole and the formed film; FIG. 7 is an example of a thickness profile of a nickel film; FIG. 8 is an example of a thickness profile of a nickel film; FIG. 9 is a schematic plan view showing an example of a member formed using the metal mask according to the present embodiment; FIG. 10 is a schematic plan view showing another example of a member formed using the metal mask according to the present embodiment; FIG. 11 is a schematic plan view showing the positional relationship when the member of FIG. 4 is alternately stacked after being divided into two equal parts, or after cutting either the left or right end shown in FIG. 5.

[0024] Hereinafter, embodiments of the metal mask, the method for forming an internal electrode pattern of a multilayer ceramic capacitor, the method for forming internal electrodes of a multilayer ceramic capacitor, the method for manufacturing a multilayer ceramic capacitor, and the method for managing a metal mask for forming internal electrodes of a multilayer ceramic capacitor will be described with reference to FIGS. 1 to 6 .

[0025] The following embodiment shows one aspect of the present invention, does not limit the present invention, and can be arbitrarily modified within the scope of the technical concept of the present invention.

[0026] As shown schematically in FIG. 1 , the metal mask 1 according to this embodiment is placed on top of a dielectric sheet (often called a green sheet) 100 as a substrate. In physical vapor deposition processes such as sputtering and deposition, only material that flies from a target T toward the metal mask 1 and passes through the through holes 1 a is deposited on the dielectric sheet 100 to form a thin conductive film 101 (see FIG. 2 ). The material constituting the conductive film can be selected from metals. Examples of metals that can be used include nickel and nickel alloys containing nickel as a main component, including aluminum, silver, copper, platinum, etc.

[0027] 2 is an enlarged cross-sectional view of one through hole 1a in the metal mask 1. The through hole 1a is formed by etching a sheet-like metal substrate (hereinafter simply referred to as "substrate 110") that constitutes the metal mask from both sides in the thickness direction.

[0028] When the through-hole 1a is formed by wet etching, the etching is often performed in two stages. Specifically, first, the surface 110a of the substrate 110 that is in close contact with the dielectric sheet is etched, and then the surface 110b of the substrate 110 that is on the target T side is etched, thereby forming the through-hole 1a. The surface 110a corresponds to a first side in the thickness direction of the substrate 110. The surface 110b corresponds to a second side in the thickness direction of the substrate 110.

[0029] Because the etching is isotropic, the planar dimensions of the through hole 1a become larger the closer to the surfaces 110a, 110b of the substrate 110 and become smaller the farther from the surfaces 110a, 110b of the substrate 110. Therefore, when two-stage etching is performed from the surfaces 110a, 110b of the substrate 110 to fabricate the metal mask 1, the planar dimensions of the formed through hole become smallest at the penetration portion 1b in the middle of the substrate 110 in the thickness direction, and the planar shape and dimensions at this portion define the planar shape of the film-formed structure.

[0030] The penetrating portion 1b, which has the smallest planar dimension, is formed at the location where etching from surfaces 110a and 110b meets, and therefore the position of the penetrating portion 1b in the thickness direction of the substrate 110 (hereinafter simply referred to as the "thickness direction") changes depending on the extent of etching performed from each surface.

[0031] Because the film-forming material flies radially from the target T, if it enters the through-hole 1a at an angle, it may pass through the through-hole 1b and then fly outside the area of ​​the through-hole in a plan view, potentially reaching the dielectric sheet 100, as shown by the dashed arrow Ta in FIG. 2 . This phenomenon, sometimes referred to as the "shadow effect," occurs more frequently the farther the through-hole 1b is from the dielectric sheet 100, i.e., the larger the step height h1 (described in detail below), which is the dimension in the thickness direction from the surface 110a of the substrate 110 to the through-hole 1b. Furthermore, the stronger the shadow effect, the smaller the area of ​​the top surface of the formed thin film 101 becomes relative to the area of ​​the bottom surface of the formed thin film 101. In other words, the edge of the formed thin film 101 becomes thinner than the center.

[0032] On the other hand, as shown by the dashed arrow Tb in Figure 2, there is a possibility that the particles may fly from outside the range of the penetration portion 1b in plan view and reach the dielectric sheet 100. This phenomenon occurs due to a tapered portion h2 formed in the substrate 110 closer to the surface 110b than the penetration portion 1b. The tapered portion h2 extends in a direction away from the penetration portion 1b and in a direction in which the gap becomes larger as it moves from the penetration portion 1b toward the surface 110b. The probability of the phenomenon of the particles flying from outside the range of the penetration portion 1b in plan view and reaching the dielectric sheet 100 increases as the position where the tapered portion h2 opens on the surface 110b is farther away from the penetration portion 1b and the taper angle θ becomes smaller, and the formed thin film 101 becomes thicker.

[0033] The taper angle θ of the tapered portion h2 is the smaller of the intersection angles at which the line segment connecting the position where the tapered portion h2 opens onto the surface 110b and the through-hole portion 1b intersects with the surface 110b in the cross-sectional shape of the peripheral edge facing the through-hole 1a.

[0034] In other words, the metal mask 1 has a cross-sectional shape of the periphery facing the through hole 1a, in which a step height h1 is formed on the surface 110a side in the thickness direction and a tapered portion h2 is formed on the surface 110b side in the thickness direction, so as to affect the shape and thickness of the thin film 101.

[0035] Based on this, the inventors studied the step height (denoted by the symbol h1 in FIG. 2 ) in the short-side direction, which is the distance from the surface 110a, which is in close contact with the dielectric sheet 100 serving as the substrate, to the through-hole 1b in the thickness direction of the metal mask 1, and the tapered portion h2 located in the short-side direction, to investigate the conditions for a metal mask suitable for manufacturing an internal electrode for an MLCC. The inventors also studied the influence of a film formed by deposition of a film-forming material flying from the target T on the surface 110b and the tapered portion h2 of the substrate 110, to investigate the conditions for a metal mask suitable for manufacturing an internal electrode for an MLCC. Here, the short-side direction is the direction extending perpendicular to the plane of the paper in FIG. 2 at both ends of the left-right direction (long-side direction) of the through-hole 1a in FIG. 2 .

[0036] (Preparation of Metal Mask Samples) A ​​50 μm-thick stainless steel SUS430 sheet (350 mm × 715 mm in plan view) was prepared as a substrate. Two-stage etching was performed on both sides of the substrate to create numerous rectangular through-holes at a constant pitch in plan view. The dimension of the through-hole 1b in the short side direction was 300 μm. By varying the amount of etching from both sides, metal mask samples Samples 1 to 8 were prepared, each having the step height and taper angle shown in Table 1. Similarly, by varying the amount of etching from both sides, metal mask samples Samples 1A to 7A were prepared, each having the step height and taper angle shown in Table 1.

[0037] After each sample was completed, the step height was measured by cutting the metal mask longitudinally across the through-holes, and the thickness dimension of the step height located in the short side direction was measured by laser confocal scanning using a measuring device (VK-X200, manufactured by Keyence Corporation) while making it possible to observe the dimension from the side of the through-hole side. The taper angle was also measured by cutting the metal mask longitudinally across the through-holes, and measuring it from the surface 110b side, which is the flight side of the target, by laser confocal scanning using the same measuring device (VK-X200, manufactured by Keyence Corporation). Cross-sectional profile data was obtained and then processed to calculate the taper angle θ.

[0038] (Measurement of line width of thin film after film formation) Assuming repeated use of the metal mask, six film-formed samples were prepared for each of the metal mask samples, Samples 1 to 8, including samples on which film formation material was intentionally deposited to thicknesses of 0.5 μm, 1.0 μm, 5.0 μm, 10.0 μm, and 15.0 μm, as well as samples on which no film formation material was deposited (deposition amount: 0.0 μm). The deposition thickness of the film formation material on the metal mask samples was controlled by using the metal mask samples under conditions equivalent to the thin film formation process and repeating the process of depositing 0.5 μm.

[0039] A 150 nm-thick thin film was formed using each prepared metal mask sample, and the line width of the thin film in the short side direction after film formation was measured. Nickel material was used for the thin film and the film (target). To measure the line width, an image of the thin film was obtained by white light interference scanning using a measuring device (Keyence VK-X3000). A cross-sectional profile was obtained at the center of the short side of the obtained thin film image using the VK-X3000 multi-file analysis application software.

[0040] 3A shows an example of a thickness profile of a thin film (nickel film). As shown in FIG. 3A, a straight line parallel to the bottom surface was set at a position corresponding to the maximum height H-10 nm of the deposited film (a position 10 nm lower than the maximum height H of the deposited film), and the distance W between the intersection of this line and the deposited film profile was defined as the line width. The measured line width was expressed as a ratio based on the line width of a thin film deposited using a metal mask sample with a deposition amount of 0.0 μm.

[0041] (Evaluation Method) Samples showing a change within the general "20% capacity guarantee value of MLCC" were rated as "○" (OK), and samples showing a change exceeding 20% ​​were rated as "×" (NG).

[0042]

[0043] As shown in Table 1, for the metal mask samples 1 to 6, in which the step height dimension in the thickness direction was 12.2 μm or less and the taper angle of the tapered portion located in the short side direction relative to the short side direction was 47.0° or less, it was confirmed that good film formation could be achieved with a variation of less than 20% in the deposition thickness of the film formed (metal mask deposition amount) for all samples ranging from 0.0 μm to 15.0 μm.

[0044] Therefore, by using a metal mask in which the step height dimension in the thickness direction is 12.2 μm or less and the taper angle of the tapered portion located in the short side direction relative to the short side direction is 47.0° or less, good film formation can be achieved with a change amount of within 20% even if the deposition thickness of the film formation material is 15.0 μm.Therefore, the deposition thickness of the film formation material can be used as an indicator when cleaning the metal mask, and a management method for metal masks for forming internal electrodes of MLCCs can be set according to this indicator.

[0045] Specifically, the method for managing a metal mask for forming an internal electrode of an MLCC includes managing the upper limit of the thickness dimension of the film deposited on the metal mask to 15 μm, and cleaning the metal mask when the thickness dimension of the film reaches the upper limit.

[0046] On the other hand, in the metal mask samples of Samples 7 to 8, when the deposition thickness of the film formed was 15.0 μm, the taper angle exceeded 47.0° even though the dimension of the step height in the thickness direction was 12.2 μm or less, so the amount of change exceeded 20%, and a good evaluation was not obtained. In other words, Samples 1 to 6 in this embodiment are examples, and Samples 7 to 8 are comparative examples.

[0047] This is thought to be because the large taper angle reduces the possibility of the film material flying from outside the range of the penetration portion 1b in a planar view and reaching the dielectric sheet 100, and also because a large amount of the film material is deposited from the penetration portion 1b to the tapered portion, which causes the film material flying from the target T to be blocked by the film material, thereby hindering the formation of a thin film.

[0048] By setting the step height to 12.2 μm or less in the thickness direction and the taper angle of the tapered portion located in the short side direction relative to the short side direction to 47.0° or less, it was possible to achieve the relationship (line width in the short side direction of the thin film deposited on a metal mask sample with a deposition thickness of 1.0 μm) / (line width in the short side direction of the thin film deposited on a metal mask sample with a deposition thickness of 0.0 μm) ≧ 0.97. In other words, for Samples 1 to 6 in Table 1, which satisfy the above condition, the value corresponding to a metal mask deposition amount of 1.0 μm is 0.97.

[0049] Furthermore, by setting the step height to 12.2 μm or less in the thickness direction and the taper angle of the tapered portion located in the short side direction relative to the short side direction to 47.0° or less, it was possible to achieve the relationship (line width in the short side direction of the thin film deposited on a metal mask sample with a deposition thickness of 5.0 μm) / (line width in the short side direction of the thin film deposited on a metal mask sample with a deposition thickness of 0.0 μm) ≧ 0.92. In other words, for Samples 1 to 6 in Table 1, which satisfy the above condition, the value corresponding to a metal mask deposition amount of 5.0 μm is 0.92 or more.

[0050] Furthermore, by setting the step height to 12.2 μm or less in the thickness direction and the taper angle of the tapered portion located in the short side direction relative to the short side direction to 47.0° or less, it was possible to achieve the relationship (line width in the short side direction of the thin film deposited on a metal mask sample with a deposition thickness of 10.0 μm) / (line width in the short side direction of the thin film deposited on a metal mask sample with a deposition thickness of 0.0 μm) ≧ 0.90. In other words, for Samples 1 to 6 in Table 1, which satisfy the above condition, the value corresponding to a metal mask deposition amount of 10.0 μm is 0.90 or more.

[0051] By setting the step height to 12.2 μm or less in the thickness direction and the taper angle of the tapered portion located in the short side direction relative to the short side direction to 47.0° or less, it was possible to achieve the relationship (line width in the short side direction of the thin film deposited on a metal mask sample with a deposition thickness of 15.0 μm) / (line width in the short side direction of the thin film deposited on a metal mask sample with a deposition thickness of 0.0 μm) ≧ 0.80. In other words, for Samples 1 to 6 in Table 1, which satisfy the above condition, the value corresponding to a metal mask deposition amount of 15.0 μm is 0.80 or more.

[0052] On the other hand, it was confirmed that, for metal mask samples 1 to 4, which have a taper angle of 44.6° or less and a step height in the thickness direction of 1.8 μm or more, better film formation was achieved for samples with deposition thicknesses of 5.0 μm and 15.0 μm than for metal mask samples 5 to 6. That is, the values ​​corresponding to metal mask deposition amounts of 5.0 μm and 15.0 μm for Samples 1 to 4 in Table 1 are greater than the values ​​corresponding to metal mask deposition amounts of 5.0 μm and 15.0 μm for Samples 5 to 6 in Table 1. That is, the line widths in the short side direction of the thin films formed using the metal mask samples with metal mask deposition amounts of 5.0 μm and 15.0 μm are closer to the line widths in the short side direction of the thin films formed using the metal mask samples with metal mask deposition amounts of 0.0 μm for Samples 1 to 4 compared to Samples 5 and 6.

[0053] Furthermore, it was confirmed that metal mask samples 1 and 2, which have a taper angle of 40.3° or less and a step height of 10.0 μm or more in the thickness direction, can perform better film formation in samples with deposition thicknesses of 5.0 μm, 10.0 μm, and 15.0 μm than metal mask samples 3 to 6. That is, the values ​​corresponding to metal mask deposition amounts of 5.0 μm, 10.0 μm, and 15.0 μm for Samples 1 and 2 in Table 1 are greater than the values ​​corresponding to metal mask deposition amounts of 5.0 μm, 10.0 μm, and 15.0 μm for Samples 3 to 6 in Table 1. In other words, the line width in the short side direction of the thin film formed using the metal mask samples with metal mask deposition amounts of 5.0 μm, 10.0 μm, and 15.0 μm is closer to the line width in the short side direction of the thin film formed using the metal mask sample with a metal mask deposition amount of 0.0 μm in samples 1 and 2 than in samples 3 to 6.

[0054] (Measurement of film thickness of thin film after film formation) Separately from the line width of the thin film after film formation, the film thickness of the thin film after film formation was measured. Using the above-mentioned metal mask samples, assuming repeated use of the metal masks, six film-formed samples were prepared for each of Samples 1 to 5 and Samples 7 to 8, including samples on which film formation material was intentionally deposited to thicknesses of 0.5 μm, 1.0 μm, 5.0 μm, 10.0 μm, and 15.0 μm, and samples on which no film formation material was deposited (deposition amount: 0.0 μm).

[0055] A thin film with a thickness of 150 nm was formed using each prepared metal mask sample, and the thickness of the thin film after deposition was measured. Nickel materials were used for the thin film and the film-forming object (target). The thickness of the thin film after deposition was defined as the maximum height H of the film, as shown in Figure 3. The measured thickness was expressed as a ratio based on the thickness of the thin film formed using a metal mask sample with a deposition amount of 0.0 μm.

[0056] (Evaluation Method) For samples with a deposition amount of 15.0 μm, samples showing a change in film thickness of 10% or less were evaluated as "○" (OK), and samples showing a change in film thickness of more than 10% were evaluated as "×" (NG).

[0057]

[0058] As shown in Table 2, for the metal mask samples Samples 3 to 5, in which the step height dimension in the thickness direction is 8.3 μm or less and the taper angle of the tapered portion located in the short side direction with respect to the short side direction is 42.1° or more and 47.0° or less, it was confirmed that good film formation could be achieved with a variation of less than 10% in any sample in which the deposition thickness of the film formed ranged from 0.0 μm to 15.0 μm.

[0059] On the other hand, for the metal mask samples of Samples 1 and 2, the change in film thickness exceeded 10% at least when the deposition thickness of the film was 1.0 μm, 5.0 μm, 10.0 μm, or 15.0 μm, and thus a favorable evaluation was not obtained. This is likely due to the large thickness dimension of the step height, which resulted in a strong shadow effect, causing much of the film material to reach the edge, which does not contribute to the maximum film thickness. Furthermore, it is thought that the deposition of a large amount of film material from the penetration portion 1b to the tapered portion blocked the film material flying from the target T, inhibiting the formation of the thin film.

[0060] Thus, if the change in film thickness exceeds 10%, 1.1 times or more of the film formation steps are required to form the same film thickness, and the time required to repeatedly laminate thin films on one dielectric sheet 100 is proportionally 1.1 times or more, which is not preferable because it not only reduces production efficiency but also deteriorates the stability of the total film thickness. Therefore, the above-mentioned inconvenience can be resolved by setting the dimension of the step height in the thickness direction to 8.3 μm or less and setting the taper angle of the tapered portion located in the short side direction to 42.1° or more and 47.0° or less with respect to the short side direction.

[0061] On the other hand, in the metal mask samples of Samples 3 and 4, in which the step height dimension in the thickness direction is 3.1 μm or less and the taper angle of the tapered portion located in the short side direction with respect to the short side direction is 42.1° or more and 47.0° or less, it was confirmed that better film formation could be achieved in samples with deposition thicknesses of 1.0 μm, 5.0 μm, and 10.0 μm than in the metal mask sample of Sample 5. That is, the values ​​corresponding to metal mask deposition amounts of 1.0 μm, 5.0 μm, and 10.0 μm in Samples 3 and 4 in Table 2 are greater than the values ​​corresponding to metal mask deposition amounts of 1.0 μm, 5.0 μm, and 10.0 μm in Sample 5 in Table 2. In other words, the line width in the short side direction of the thin film formed on the metal mask samples with metal mask deposition amounts of 1.0 μm, 5.0 μm, and 10.0 μm is closer to the line width in the short side direction of the thin film formed on the metal mask sample with a metal mask deposition amount of 0.0 μm in samples 3 to 4 compared to sample 5.

[0062] Furthermore, it was confirmed that the metal mask sample of Sample 4, in which the step height in the thickness direction was 1.9 μm or less and the taper angle of the tapered portion located in the short side direction relative to the short side direction was 44.6° or more, exhibited better film formation in the samples with deposition thicknesses of 5.0 μm, 10.0 μm, and 15.0 μm than the metal mask sample of Sample 5. That is, the values ​​corresponding to metal mask deposition amounts of 5.0 μm, 10.0 μm, and 15.0 μm in Sample 4 in Table 2 were greater than the values ​​corresponding to metal mask deposition amounts of 5.0 μm, 10.0 μm, and 15.0 μm in Sample 5 in Table 2. That is, the line width in the short side direction of the thin film formed on the metal mask samples with metal mask deposition amounts of 5.0 μm, 10.0 μm, and 15.0 μm in Sample 4 was closer to the line width in the short side direction of the thin film formed on the metal mask sample with a metal mask deposition amount of 0.0 μm than in Sample 5.

[0063] 4 shows an example of a member 50 serving as an internal electrode for an MLCC, formed using the metal mask according to this embodiment. The member 50 has a structure in which a thin film 20 made of a conductor is formed as an internal electrode on a substrate (dielectric sheet) 10 made of a dielectric by a method for forming an internal electrode that includes a method for forming an internal electrode pattern by sputtering, which is a type of physical vapor deposition method, using the metal mask according to this embodiment.

[0064] Because the thin film 20 is formed using the metal mask according to this embodiment, the line width in the short side direction is 80% or more of the line width when no film is deposited on the metal mask. The member 50 shown in Fig. 4 is divided into two equal parts, member 50A and member 50B, in the longitudinal direction as shown by the dashed line, to form an internal electrode for an MLCC. A plurality of the members are stacked so that the margins 11 without the thin film 20 are alternated, as shown in Fig. 6. The member 50 shown in Fig. 5 is cut at either the left or right end in the longitudinal direction as shown by the dashed line, to form an internal electrode for an MLCC. A plurality of the members are stacked so that the margins 11 without the thin film 20 are alternated, as shown in Fig. 6.

[0065] That is, the manufacturing method of an MLCC (manufacturing method of a multilayer ceramic capacitor) includes forming thin films 20 that become internal electrodes on a substrate 10 shown in FIG. 4 by a method for forming internal electrodes including the method for forming an internal electrode pattern described above, dividing the substrate 10 shown in FIG. 4 on which the internal electrodes have been formed into two equal parts in the longitudinal direction into members 50A and 50B, and stacking a plurality of the two equal parts of the substrate 10 so that the margins 11 without the thin films 20 shown in FIG. 6 are staggered.

[0066] The method also includes cutting either the left or right end in the longitudinal direction of each of two thin film 20 regions of the member 50 shown in Figure 5 by a method for forming an internal electrode including the method for forming an internal electrode pattern described above, and stacking a plurality of the cut substrates 10 so that the margins 11 without thin film 20 shown in Figure 6 are alternately arranged.

[0067] The member 50 shown in Fig. 4 can contribute to the favorable fabrication of an MLCC that guarantees the above-mentioned capacitance because the line width of the thin film is maintained within a predetermined range even after it is divided into two equal parts, member 50A and member 50B. The member 50 shown in Fig. 5 can contribute to the favorable fabrication of an MLCC that guarantees the above-mentioned capacitance because the line width of the thin film is maintained within a predetermined range even after it is cut into two parts, member 50A and member 50B, at the two thin film 20 regions.

[0068] 6 is a diagram showing the positional relationship when the member 50 shown in FIG. 4 is divided into two equal parts, or when the two thin film 20 regions shown in FIG. 5 are alternately stacked after either the left or right end in the longitudinal direction is cut. In practice, this combination is counted as one set, and many sets are stacked.

[0069] As shown in Fig. 6, the member 50 shown in Fig. 4 is divided into two halves, member 50A and member 50B, which are stacked with their longitudinal ends symmetrical. In the case of the member 50 shown in Fig. 5, either the left or right end of each of the two thin film 20 regions is cut off to form member 50A and member 50B, which are stacked with their longitudinal ends symmetrical.

[0070] 6, where the thin film 20A of the member 50A and the thin film 20B of the member 50B overlap, essentially functions as a capacitor. An external terminal is connected to each of the thin film 20A of the member 50A exposed at the longitudinal end (right end) and the thin film 20B of the member 50B exposed at the longitudinal end (left end) in a stacked state.

[0071] As described above, in the metal mask 1 of this embodiment, the dimension of the penetrating portion 1b in the short side direction is 300 μm or less, the dimension in the thickness direction of the step height h1 located in the short side direction is 12.2 μm or less, and the taper angle of the tapered portion h2 located in the short side direction with respect to the short side direction is 47.0° or less, so that the shape of the internal electrode is good, and it is possible to form an internal electrode with good electrical properties.

[0072] Furthermore, since the metal mask 1 of this embodiment experiences little reduction in effective area when used repeatedly, in the method for managing a metal mask for forming internal electrodes of an MLCC, the number of times the metal mask 1 is cleaned can be reduced by setting the upper limit of the thickness direction dimension of the film deposited on the metal mask 1 to 15 μm, thereby making it possible to extend the period until the metal mask 1 is discarded.

[0073] While the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to these examples. The shapes and combinations of the components shown in the above examples are merely examples, and various modifications can be made based on design requirements, etc., without departing from the spirit of the present invention.

[0074] For example, the substrate of the metal mask according to the present invention is not limited to stainless steel such as SUS430 used in the above study. For example, other magnetic metal substrates made of alloys such as Invar or Super Invar may also be used. Forming a thin-film metal substrate from a magnetic metal material such as those described above offers the advantage of being able to be fixed to a film-forming apparatus using magnetic force. Furthermore, the thickness of the substrate is not limited to 50 μm as used in the above study. Even if the thickness is different, similar effects can be achieved by setting the step height or taper angle within the above range.

[0075] In addition, when the metal mask according to the present invention is mounted in a normal film forming apparatus, either surface in the thickness direction can be made to face the substrate, and the step height changes accordingly, but the step height in the present invention is defined as the lower of the above values. Also, in view of the manufacturing process, the step height in the metal mask according to the present invention is different from the cross section in the short side direction of the through hole and the cross section in the long side direction, so for the sake of clarity, the step height in the cross section extending in the long side direction of the part forming the edge of the short side of the through hole, i.e., the step height in the short side direction, is used.

[0076] Next, the measurement results using Samples 1A to 7A are described. (Measurement of Thin Film Thickness After Deposition) Assuming repeated use of the metal masks, six deposition samples were prepared for each of Samples 1A to 7A, including samples with intentionally deposited films of 0.5 μm, 1.0 μm, 5.0 μm, 10.0 μm, and 15.0 μm, as well as samples with no deposition (deposition amount: 0.0 μm). The deposition thickness of the deposition material on the metal mask samples was controlled by using the metal mask samples under conditions equivalent to the thin film deposition process and repeatedly depositing 0.5 μm.

[0077] A thin film with a thickness of 150 nm was formed using each prepared metal mask sample, and the film thickness of the formed thin film was measured. Nickel material was used for the thin film and the film (target). To measure the film thickness, an image of the thin film was obtained by white light interference scanning using a measuring device (Keyence VK-X3000). A cross-sectional profile was obtained at the center of the short side of the obtained thin film image using the VK-X3000 multi-file analysis application software.

[0078] 3B shows an example of the thickness profile of the nickel film. As shown in FIG. 3B, the film thickness of the thin film was defined as the maximum height H of the film formed from a line parallel to the bottom surface. The measured film thickness was expressed as a ratio based on the film thickness of a thin film formed using a metal mask sample with a deposition amount of 0.0 μm.

[0079] (Evaluation Method) For samples with a deposition amount of 15.0 μm, samples showing a change in film thickness of 10% or less were evaluated as "○" (OK), and samples showing a change in film thickness of more than 10% were evaluated as "×" (NG).

[0080]

[0081] As shown in Table 3, for the metal mask samples Samples 1A to 5A, in which the step height dimension in the thickness direction is 8.3 μm or less and the taper angle of the tapered portion located in the short side direction with respect to the short side direction is 50.2° or less, it was confirmed that good film formation could be achieved with a variation of 10% or less in the deposition thickness of the film formed for all samples ranging from 0.0 μm to 15.0 μm.

[0082] Therefore, by using a metal mask in which the step height dimension in the thickness direction is 8.3 μm or less and the taper angle of the tapered portion located in the short side direction relative to the short side direction is 50.2° or less, good film formation can be achieved with a variation of less than 10% even if the deposition thickness of the film formation material is 15.0 μm.Therefore, the deposition thickness of the film formation material can be used as an indicator when cleaning the metal mask, and a management method for metal masks for forming internal electrodes of MLCCs can be set according to this indicator.

[0083] Specifically, the method for managing a metal mask for forming an internal electrode of an MLCC includes managing the upper limit of the thickness dimension of the film deposited on the metal mask to 15 μm, and cleaning the metal mask when the thickness dimension of the film reaches the upper limit.

[0084] On the other hand, in the metal mask samples of Samples 6A to 7A, the change in film thickness exceeded 10% when the deposition thickness of the film formed was 1.0 μm, 5.0 μm, 10.0 μm, or 15.0 μm, and thus a favorable evaluation was not obtained. That is, Samples 1A to 5A in this embodiment are examples, and Samples 6A to 7A are comparative examples.

[0085] This is probably because the large dimension of the step height in the thickness direction strengthened the shadow effect, causing much of the film-forming material to reach the edge, which does not contribute to the maximum film thickness. Also, it is thought that the film-forming material was deposited in large amounts from the penetration portion 1b to the tapered portion, which blocked the film-forming material flying from the target T, inhibiting the formation of the thin film.

[0086] Thus, if the change in film thickness exceeds 10%, 1.1 times or more of the film formation steps are required to form the same film thickness, and the time required to repeatedly laminate thin films on one dielectric sheet 100 is proportionally 1.1 times or more, which is not preferable because it not only reduces production efficiency but also deteriorates the stability of the total film thickness. Therefore, the above-mentioned inconvenience can be resolved by setting the dimension of the step height in the thickness direction to 8.3 μm or less and setting the taper angle of the tapered portion located in the short side direction to 50.2° or less.

[0087] By setting the step height to 8.3 μm or less in the thickness direction and the taper angle of the tapered portion located in the short side direction relative to the short side direction to 50.2° or less, it was possible to achieve the following: (film thickness at the center of the thin film formed on a metal mask sample with a deposition thickness of 1.0 μm) / (film thickness at the center of the thin film formed on a metal mask sample with a deposition thickness of 0.0 μm) ≥ 0.94. In other words, for Samples 1A to 5A in Table 3, which satisfy the above conditions, the value corresponding to a metal mask deposition amount of 1.0 μm is 0.94 or more.

[0088] Furthermore, by setting the step height to 8.3 μm or less in the thickness direction and setting the taper angle of the tapered portion located in the short side direction to 50.2° or less with respect to the short side direction, it was possible to achieve the following: (film thickness at the center of the thin film formed on a metal mask sample with a deposition thickness of 5.0 μm) / (film thickness at the center of the thin film formed on a metal mask sample with a deposition thickness of 0.0 μm) ≥ 0.93. In other words, for Samples 1A to 5A in Table 3, which satisfy the above conditions, the value corresponding to a metal mask deposition amount of 5.0 μm is 0.93 or more.

[0089] Furthermore, by setting the step height to 8.3 μm or less in the thickness direction and setting the taper angle of the tapered portion located in the short side direction to 50.2° or less with respect to the short side direction, it was possible to achieve the following: (film thickness at the center of the thin film formed on a metal mask sample with a deposition thickness of 10.0 μm) / (film thickness at the center of the thin film formed on a metal mask sample with a deposition thickness of 0.0 μm) ≧ 0.91. In other words, for Samples 1A to 5A in Table 3, which satisfy the above conditions, the value corresponding to a metal mask deposition amount of 10.0 μm is 0.91 or more.

[0090] By setting the step height to 8.3 μm or less in the thickness direction and the taper angle of the tapered portion located in the short side direction relative to the short side direction to 50.2° or less, it was possible to achieve the following: (film thickness at the center of the thin film formed on a metal mask sample with a deposition thickness of 15.0 μm) / (film thickness at the center of the thin film formed on a metal mask sample with a deposition thickness of 0.0 μm) ≧ 0.90. In other words, for Samples 1A to 5A in Table 3, which satisfy the above condition, the value corresponding to a metal mask deposition amount of 15.0 μm is 0.90 or more.

[0091] On the other hand, for the metal mask samples 1A to 4A, in which the step height was 5.7 μm or less in the thickness direction and the taper angle of the tapered portion located in the short side direction relative to the short side direction was 50.2° or less, it was confirmed that better film formation could be achieved for samples with a deposition thickness of 1.0 μm than for the metal mask sample 5A. That is, the values ​​corresponding to a metal mask deposition amount of 1.0 μm for Samples 1A to 4A in Table 3 were greater than the values ​​corresponding to a metal mask deposition amount of 1.0 μm for Sample 5A in Table 3. That is, the line width in the short side direction of the thin film formed using the metal mask samples with a metal mask deposition amount of 1.0 μm for Samples 1A to 4A was closer to the line width in the short side direction of the thin film formed using the metal mask sample with a metal mask deposition amount of 0.0 μm than for Sample 5A.

[0092] Furthermore, it was confirmed that the metal mask samples 1A to 3A, in which the step height in the thickness direction was 3.1 μm or less and the taper angle of the tapered portion located in the short side direction relative to the short side direction was 42.1° or more, exhibited better film formation in the samples with deposition thicknesses of 1.0 μm and 5.0 μm than the metal mask samples 4A to 5A. That is, the values ​​corresponding to metal mask deposition amounts of 1.0 μm and 5.0 μm for Samples 1A to 3A in Table 3 were greater than the values ​​corresponding to metal mask deposition amounts of 1.0 μm and 5.0 μm for Samples 4A to 5A in Table 3. That is, the line widths in the short side direction of the thin films formed using the metal mask samples with metal mask deposition amounts of 1.0 μm and 5.0 μm were closer to the line widths in the short side direction of the thin films formed using the metal mask samples with metal mask deposition amounts of 0.0 μm for Samples 1A to 3A than for Samples 4A to 5A.

[0093] Furthermore, it was confirmed that, for metal mask samples 1A to 2A, in which the step height dimension in the thickness direction was 1.9 μm or less and the taper angle of the tapered portion located in the short side direction relative to the short side direction was 44.6° or more, better film formation was achieved in samples with deposition thicknesses of 5.0 μm, 10.0 μm, and 15.0 μm than for metal mask sample 5 A. That is, the values ​​corresponding to metal mask deposition amounts of 5.0 μm, 10.0 μm, and 15.0 μm for Samples 1A to 2A in Table 3 were greater than the values ​​corresponding to metal mask deposition amounts of 5.0 μm, 10.0 μm, and 15.0 μm for Sample 5A in Table 3. In other words, the line width in the short side direction of the thin film formed using the metal mask samples with metal mask deposition amounts of 5.0 μm, 10.0 μm, and 15.0 μm is closer to the line width in the short side direction of the thin film formed using the metal mask sample with a metal mask deposition amount of 0.0 μm in samples 1A to 2A than in sample 5A.

[0094] Furthermore, it was confirmed that the metal mask sample of Sample 1A, in which the step height in the thickness direction is 0.8 μm or less and the taper angle of the tapered portion located in the short side direction with respect to the short side direction is 48.4° or more, exhibited better film formation in samples with deposition thicknesses of 5.0 μm, 10.0 μm, and 15.0 μm than the metal mask samples of Samples 2A to 5A. That is, the values ​​corresponding to the metal mask deposition amounts of 5.0 μm, 10.0 μm, and 15.0 μm for Sample 1A in Table 3 were greater than the values ​​corresponding to the metal mask deposition amounts of 5.0 μm, 10.0 μm, and 15.0 μm for Samples 2A to 5A in Table 3. In other words, the line width in the short side direction of the thin film formed using metal mask samples with metal mask deposition amounts of 5.0 μm, 10.0 μm, and 15.0 μm is closer to the line width in the short side direction of the thin film formed using metal mask samples with metal mask deposition amounts of 0.0 μm in sample 1A than in samples 2A to 5A.

[0095] 4 shows an example of a member 50 serving as an internal electrode for an MLCC, formed using the metal mask according to this embodiment. The member 50 has a structure in which a thin film 20 made of a conductor is formed as an internal electrode on a substrate (dielectric sheet) 10 made of a dielectric by a method for forming an internal electrode that includes a method for forming an internal electrode pattern by sputtering, which is a type of physical vapor deposition method, using the metal mask according to this embodiment.

[0096] Since the thin film 20 is formed using the metal mask according to this embodiment, the film thickness at the center is 90% or more of the film thickness when no film is deposited on the metal mask. The member 50 shown in Fig. 4 is divided into two equal parts, member 50A and member 50B, in the longitudinal direction as shown by the dashed-dotted line to form an internal electrode for an MLCC. A plurality of the members are stacked so that the margins 11 without the thin film 20 are alternately arranged, as shown in Fig. 6. The member 50 shown in Fig. 5 is cut at either the left or right end in the longitudinal direction as shown by the dashed-dotted line to form an internal electrode for an MLCC. A plurality of the members are stacked so that the margins 11 without the thin film 20 are alternately arranged, as shown in Fig. 6.

[0097] That is, the manufacturing method of an MLCC (manufacturing method of a multilayer ceramic capacitor) includes forming thin films 20 that become internal electrodes on a substrate 10 shown in FIG. 4 by a method for forming internal electrodes including the method for forming an internal electrode pattern described above, dividing the substrate 10 shown in FIG. 4 on which the internal electrodes have been formed into two equal parts in the longitudinal direction into members 50A and 50B, and stacking a plurality of the two equal parts of the substrate 10 so that the margins 11 without the thin films 20 shown in FIG. 6 are staggered.

[0098] Furthermore, a method for manufacturing an MLCC (a method for manufacturing a multilayer ceramic capacitor) includes cutting either the left or right end in the longitudinal direction of each of two thin film 20 regions of the member 50 shown in FIG. 5 by a method for forming internal electrodes including the method for forming an internal electrode pattern described above, and stacking a plurality of the cut substrates 10 so that the margins 11 without thin film 20 shown in FIG. 6 are alternately arranged.

[0099] The member 50 shown in Fig. 4 can contribute to the favorable fabrication of an MLCC that guarantees the above-mentioned capacitance because the film thickness of the thin film is maintained within a predetermined range even after it is divided into two equal parts, member 50A and member 50B. The member 50 shown in Fig. 5 can contribute to the favorable fabrication of an MLCC that guarantees the above-mentioned capacitance because the film thickness is maintained within a predetermined range even after it is cut into two parts, member 50A and member 50B, at the two thin film 20 regions.

[0100] 6 is a diagram showing the positional relationship when the member 50 shown in FIG. 4 is divided into two equal parts, or when the two thin film 20 regions shown in FIG. 5 are alternately stacked after either the left or right end in the longitudinal direction is cut. In practice, this combination is counted as one set, and many sets are stacked.

[0101] As shown in Fig. 6, the member 50 shown in Fig. 4 is divided into two halves, member 50A and member 50B, which are stacked with their longitudinal ends symmetrical. In the case of the member 50 shown in Fig. 5, either the left or right end of each of the two thin film 20 regions is cut off to form member 50A and member 50B, which are stacked with their longitudinal ends symmetrical.

[0102] 6, where the thin film 20A of the member 50A and the thin film 20B of the member 50B overlap, essentially functions as a capacitor. An external terminal is connected to each of the thin film 20A of the member 50A exposed at the longitudinal end (right end) and the thin film 20B of the member 50B exposed at the longitudinal end (left end) in a stacked state.

[0103] As described above, in the metal mask 1 of this embodiment, the dimension of the penetrating portion 1b in the short side direction is 300 μm or less, the dimension in the thickness direction of the step height h1 located in the short side direction is 8.3 μm or less, and the taper angle of the tapered portion h2 located in the short side direction with respect to the short side direction is 50.2° or less, so that the film formation rate is good and it is possible to form internal electrodes with good electrical properties.

[0104] Furthermore, since the metal mask 1 of this embodiment experiences little reduction in effective area when used repeatedly, in the method for managing a metal mask for forming internal electrodes of an MLCC, the number of times the metal mask 1 is cleaned can be reduced by setting the upper limit of the thickness direction dimension of the film deposited on the metal mask 1 to 15 μm, thereby making it possible to extend the period until the metal mask 1 is discarded.

[0105] While the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to these examples. The shapes and combinations of the components shown in the above examples are merely examples, and various modifications can be made based on design requirements, etc., without departing from the spirit of the present invention.

[0106] For example, the substrate of the metal mask according to the present invention is not limited to stainless steel such as SUS430 used in the above study. For example, other magnetic metal substrates made of alloys such as Invar or Super Invar may also be used. Forming a thin-film metal substrate from a magnetic metal material such as those described above offers the advantage of being able to be fixed to a film-forming apparatus using magnetic force. Furthermore, the thickness of the substrate is not limited to 50 μm as used in the above study. Even if the thickness is different, similar effects can be achieved by setting the step height or taper angle within the above range.

[0107] In addition, when the metal mask according to the present invention is mounted in a normal film forming apparatus, either surface in the thickness direction can be made to face the substrate, and the step height changes accordingly, but the step height in the present invention is defined as the lower of the above values. Also, in view of the manufacturing process, the step height in the metal mask according to the present invention is different from the cross section in the short side direction of the through hole and the cross section in the long side direction, so for the sake of clarity, the step height in the cross section extending in the long side direction of the part forming the edge of the short side of the through hole, i.e., the step height in the short side direction, is used.

[0108] REFERENCE SIGNS LIST 1 metal mask 1a through hole 1b through portion 10 substrate 20 thin film (internal electrode) 21 upper surface 22 bottom surface 100 dielectric sheet (substrate) 110 base material h1 step height h2 tapered portion

Claims

1. A metal mask for manufacturing internal electrodes of a multilayer ceramic capacitor, in which a through hole of a rectangular shape in plan view is formed in a metal substrate, wherein the dimension of the through portion of the through hole in the direction of a short side of the rectangle in plan view is 300 μm or less, and in the cross-sectional shape of the peripheral edge facing the through portion, a step height is formed on a first side in the thickness direction of the substrate, and a tapered portion extending in a direction away from the through portion is formed on a second side in the thickness direction, the dimension of the step height located in the direction of the short side in the thickness direction is 12.2 μm or less, and the tapered portion located in the direction of the short side has a taper angle of 47.0° or less with respect to the direction of the short side.

2. The metal mask according to claim 1, wherein the taper angle is 44.6° or less, and the dimension of the step height in the thickness direction is 1.8 μm or more.

3. The metal mask according to claim 2, wherein the taper angle is 40.3° or less, and the dimension of the step height in the thickness direction is 10.0 μm or more.

4. The metal mask according to claim 1, wherein the dimension of the step height in the thickness direction is 8.3 μm or less, and the taper angle is 42.1° or more and 47.0° or less.

5. The metal mask according to claim 4, wherein the dimension of the step height in the thickness direction is 3.1 μm or less.

6. The metal mask according to claim 5, wherein the dimension of the step height in the thickness direction is 1.9 μm or less, and the taper angle is 44.6° or more.

7. A method for forming an internal electrode pattern of a multilayer ceramic capacitor, comprising forming the internal electrodes by physical vapor deposition using the metal mask according to any one of claims 1 to 6.

8. A method for forming an internal electrode of a multilayer ceramic capacitor, comprising forming the internal electrode by using the method for forming an internal electrode pattern of a multilayer ceramic capacitor as set forth in claim 7.

9. A method for manufacturing a multilayer ceramic capacitor, comprising forming the internal electrodes using the method for forming internal electrodes of a multilayer ceramic capacitor according to claim 8.

10. A method for managing a metal mask for forming internal electrodes of a multilayer ceramic capacitor, comprising: managing the upper limit of the dimension in the thickness direction of a film deposited on the metal mask according to any one of claims 1 to 6 to be 15 μm; and cleaning the metal mask when the dimension in the thickness direction of the film reaches said upper limit.

11. A metal mask for manufacturing internal electrodes of a multilayer ceramic capacitor, in which a through hole of a rectangular shape in plan view is formed in a metal substrate, wherein the dimension of the through portion of the through hole in the direction of the short side of the rectangle in plan view is 300 μm or less, and in the cross-sectional shape of the peripheral edge facing the through portion, a step height is formed on one side in the thickness direction of the substrate, and a tapered portion extending in a direction away from the through portion is formed on the other side in the thickness direction, the dimension in the thickness direction of the step height located in the direction of the short side is 8.3 μm or less, and the tapered portion located in the direction of the short side has a taper angle with respect to the short side direction of 50.2° or less.

12. The metal mask according to claim 11, wherein the dimension of the step height in the thickness direction is 5.7 μm or less.

13. The metal mask according to claim 12, wherein the dimension of the step height in the thickness direction is 3.1 μm or less, and the taper angle is 42.1° or more.

14. The metal mask according to claim 13, wherein the dimension of the step height in the thickness direction is 1.9 μm or less, and the taper angle is 44.6° or more.

15. The metal mask according to claim 14, wherein the dimension of the step height in the thickness direction is 0.8 μm or less, and the taper angle is 48.4° or more.

16. A method for forming an internal electrode pattern of a multilayer ceramic capacitor, comprising forming the internal electrodes by physical vapor deposition using the metal mask according to any one of claims 11 to 15.

17. A method for forming an internal electrode of a multilayer ceramic capacitor, comprising forming the internal electrode using the method for forming an internal electrode pattern of a multilayer ceramic capacitor as defined in claim 16.

18. A method for manufacturing a multilayer ceramic capacitor, comprising forming the internal electrodes using the method for forming internal electrodes of a multilayer ceramic capacitor as defined in claim 17.

19. A method for managing a metal mask for forming internal electrodes of a multilayer ceramic capacitor, comprising: managing the upper limit of the dimension in the thickness direction of a film deposited on the metal mask according to any one of claims 11 to 15 to be 15 μm; and cleaning the metal mask when the dimension in the thickness direction of the film reaches said upper limit.

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