Metal mask, and method for manufacturing a metal mask

Abstract

The present invention provides a metal mask that has through holes with a desired shape and high repeatability of measurements. [Solution] The metal mask used when forming the internal electrodes of a multilayer ceramic capacitor has multiple through holes provided in a metal substrate manufactured by rolling, and one side is etched. When the mask is placed on a measurement stage and the heights of multiple measurement points on the other side opposite the first side are measured five times, the difference in the difference obtained by subtracting the lowest height among the multiple measurement points from the height of each of the multiple measurement points in each of the five measurements is defined as the difference height, and the average value of the difference heights of the multiple measurement points is defined as the average difference height. The in-plane range, which is the difference between the maximum and minimum values ​​of the average difference height, is 640 μm or less.

Description

Technical Field

[0001] The present invention relates to a metal mask and a method for manufacturing the same.

Background Art

[0002] A multilayer ceramic capacitor (hereinafter sometimes referred to as MLCC) is a chip component type capacitor in which internal electrodes and dielectric layers are laminated in multiple layers. While MLCCs are required to be miniaturized, they are also required to have increased capacitance. In order to increase the capacitance while miniaturizing the MLCC, it is necessary to reduce the film thickness of the internal electrodes and increase the number of lamination layers. Conventionally, the internal electrodes have been formed by screen printing, but by forming them by a physical vapor deposition method such as sputtering, it is expected that a thin internal electrode can be formed, and thus the capacitance can be increased while miniaturizing the MLCC.

[0003] As one method for manufacturing a metal mask used in a physical vapor deposition method such as sputtering or vapor deposition, there is a method of subjecting a thin film metal substrate to a wet etching treatment to form a plurality of fine through holes (for example, Patent Document 1). In the physical vapor deposition method, the material flying from the target passes through the through holes of the metal mask and is formed into a film with a predetermined dimension at a predetermined position.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] To form through-holes of a desired shape in a metal substrate by wet etching, it is necessary to roughen the surface of the metal substrate to improve adhesion between the substrate and the resist. However, roughening the surface of the metal substrate causes fluctuations in its flatness. Therefore, roughening the surface of the metal substrate may worsen the flatness of the metal mask in which the through-holes are formed.

[0006] On the other hand, in order to improve the positional accuracy of internal electrodes formed by physical vapor deposition, it is necessary to form through-holes of the desired shape in the metal mask, while simultaneously improving the positional accuracy of the formed through-holes. Therefore, in the manufacturing process of metal masks, it goes without saying that the shape of the through-holes is inspected and measured, but in some cases, the positional accuracy of the through-holes formed in the metal mask is confirmed by measuring the position of the through-holes. In this case, if the flatness of the metal mask is high, the posture of the metal mask placed on a measurement stage, such as a three-dimensional measuring device, is difficult to stabilize. Therefore, if the flatness of the metal mask is high, the reproducibility of the measurement of the position of the through-holes decreases, making it difficult to control the positional accuracy of the through-holes.

[0007] Furthermore, metal substrates are generally manufactured by rolling. Manufacturers of metal substrates primarily control the thickness of the rolled metal substrate, resulting in small variations in thickness, but large variations in flatness. In particular, variations in flatness tend to be large in the rolling direction (hereinafter sometimes simply referred to as the rolling direction), which is the direction in which the metal substrate is stretched. As a result, in the manufacturing process of metal masks, it was difficult to improve the reproducibility of measuring the position of through holes in the rolling direction when verifying the positional accuracy of through holes formed in the metal mask. Therefore, it was difficult to stably control the positional accuracy of through holes.

[0008] Based on the above circumstances, the present invention aims to provide a metal mask having through holes that can obtain a desired shape and have high repeatability of measurements, and a method for manufacturing a metal mask. [Means for solving the problem]

[0009] To solve the above problems, this invention proposes the following means. A first aspect of the present invention is a metal mask used for manufacturing internal electrodes of multilayer ceramic capacitors by sputtering. This metal mask has multiple through holes provided in a metal substrate manufactured by rolling, and one side is etched. When the mask is placed on a measuring stage and the heights of multiple measurement points on the other side opposite the first side are measured five times, the difference height is calculated by subtracting the lowest height among the multiple measurement points from the height of each measurement point in each of the five measurements. The average difference height is the average difference height, and the in-plane range, which is the difference between the maximum and minimum values ​​of the average difference height, is 640 μm or less. The above-mentioned multiple measurement points consist of 13,800 points set with a measurement pitch of 6 mm in the longitudinal direction and a measurement pitch of 3 mm in the transverse direction of the metal mask.

[0010] A second aspect of the present invention is, Regarding the first aspect This is a method for manufacturing metal masks. The method for manufacturing this metal mask comprises a thin-film etching step in which etching is performed on one side of a metal substrate, and a through-hole forming step in which multiple through-holes are formed in the metal substrate. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a metal mask having through holes that can obtain a desired shape and have high repeatability of measurements, and a method for manufacturing a metal mask. [Brief explanation of the drawing]

[0012] [Figure 1] This is a plan view of a metal mask according to one embodiment of the present invention. [Figure 2] This is a side view of a metal mask relating to one embodiment of the present invention. [Figure 3A] This is a schematic cross-sectional view of a sputtering apparatus using a metal mask according to one embodiment of the present invention. [Figure 3B] It is a schematic enlarged cross-sectional view in the short side direction of the through hole of the metal mask according to an embodiment of the present invention. [Figure 4] It is a flowchart showing a method for manufacturing a metal mask according to an embodiment of the present invention. [Figure 5] It is a side view showing a thinning etching process according to an embodiment of the present invention. [Figure 6] It is an enlarged plan view showing the surface of a metal substrate according to an embodiment of the present invention. [Figure 7] It is an enlarged plan view showing the surface of a metal mask according to an embodiment of the present invention. [Figure 8] It is an enlarged plan view explaining an inspection process according to an embodiment of the present invention. [Figure 9] It is a diagram showing the in-plane range and average range of a metal mask according to an embodiment of the present invention.

Mode for Carrying Out the Invention

[0013] An embodiment of the present invention will be described with reference to FIGS. 1 and 2. The dimensions and the like of the figures illustrated in the following description are merely examples, and the present invention is not necessarily limited thereto, and it can be implemented by appropriately changing within the range not changing the gist thereof. Further, in the following drawings, in order to make each configuration easier to understand, the scale, number, etc. in the actual structure and each structure may be made different.

[0014] In each drawing, the Z-axis is shown as appropriate. In the present embodiment, the direction in which the Z-axis extends is the direction in which the plate surface of the metal mask faces. In the following description, the direction in which the plate surface of the metal mask faces is simply referred to as the "plate thickness direction". In the following description, the side (+Z side) in the plate thickness direction toward which the arrow of the Z-axis points is referred to as the "back surface side", and the side opposite to the side (+Z side) in the plate thickness direction toward which the arrow of the Z-axis points (-Z side) is referred to as the "front surface side".

[0015] In each drawing, the X-axis is shown as appropriate. In the present embodiment, the direction in which the X-axis extends is the longitudinal direction of the metal mask. In the following description, the longitudinal direction of the metal mask is simply referred to as the "longitudinal direction". The longitudinal direction is perpendicular to the plate thickness direction. In the present embodiment, the longitudinal direction is parallel to the rolling direction of the metal substrate. The longitudinal direction may not be parallel to the rolling direction of the metal substrate. In the following description, the side (+X side) in the longitudinal direction toward which the arrow of the X-axis points is referred to as the "right side", and the side (-X side) opposite to the side toward which the arrow of the X-axis points in the longitudinal direction is referred to as the "left side". Also, in the following description, the rolling direction of the metal substrate is simply referred to as the "rolling direction".

[0016] In each drawing, the Y-axis is shown as appropriate. In the present embodiment, the direction in which the Y-axis extends is the short side direction of the metal mask. In the following description, the short side direction of the metal mask is simply referred to as the "short side direction". The short side direction is perpendicular to both the plate thickness direction and the longitudinal direction. In the following description, the side opposite to the side (-Y side) toward which the arrow of the Y-axis points in the short side direction is referred to as the "back side". Note that the front side, the back side, the right side, the left side, and the back side are merely names for explaining the relative positional relationship of each part of the metal mask, and the actual arrangement relationship, etc. may be an arrangement relationship other than the arrangement relationship indicated by these names.

[0017] The metal mask 10 of this embodiment shown in Figure 1 is a mask used when forming the internal electrodes 28 of the multilayer ceramic capacitor (MLCC) shown in Figure 3A. The internal electrodes 28 are formed by physical vapor deposition. In this embodiment, the internal electrodes 28 are formed by sputtering. The internal electrodes 28 may also be formed by other methods such as vapor deposition. The metal mask 10 is made of a magnetic alloy. In this embodiment, the metal mask 10 is made of SUS403. As shown in Figure 1, the metal mask 10 consists of a metal substrate 15 manufactured by rolling. The metal substrate 15 is a thin-film metal substrate manufactured by rolling. As shown in Figures 1 and 2, the metal mask 10 is plate-shaped, extending in a direction perpendicular to the plate thickness direction (+Z axis direction). As shown in Figure 1, in this embodiment, the metal mask 10 is substantially rectangular in shape, with its long side extending in the longitudinal direction (X axis direction). The longitudinal direction is the rolling direction of the metal substrate 15.

[0018] The thickness Tm of the metal mask 10 shown in Figure 2 is preferably 38 μm or more and 52.5 μm or less. The thickness Tm of the metal mask 10 may be thinner than 38 μm or thicker than 52.5 μm. In this embodiment, the in-plane range F of the metal mask 10 is 640 μm or less. The procedure for calculating the in-plane range F in this embodiment will be described in detail later. In this embodiment, the length Xm in the longitudinal direction (X-axis direction) of the metal mask 10 shown in Figure 1 is 600 mm, and the length Ym in the short direction (Y-axis direction) of the metal mask 10 is 500 mm. The dimensions of the metal mask 10 are not limited to these. As shown in Figure 2, the metal mask 10 has a first surface 10a and a second surface 10c. As shown in Figure 1, the metal mask 10 has a peripheral region R1, a patterning region R2, and a plurality of through holes 11.

[0019] As shown in Figure 2, the first surface 10a is one of the surfaces of the metal mask 10 facing the surface side (-Z side). The first surface 10a, that is, one of the surfaces, is subjected to etching in the second thin-film process P012, which will be described later. As a result, the first surface 10a is roughened.

[0020] As shown in Figure 2, the second surface 10c is the other surface of the metal mask 10 facing the back side (+Z side). The first surface 10a faces the second surface 10c in the thickness direction (Z axis direction). The second surface 10c, i.e., the other surface, is subjected to etching in the first thin-filming step P011, which will be described later. As a result, the second surface 10c is roughened. Note that if the first thin-filming step P011 is not performed in the thin-filming etching step P01, which will be described later, the second surface 10c will not be roughened.

[0021] As shown in Figure 1, region R1 is the peripheral region of the metal mask 10. In this embodiment, the longitudinal dimension Xf (X-axis direction) and the short-axis dimension Yf of region R1 are both 26 mm.

[0022] As described above, region R2 is a patterning region enclosed by region R1. Viewed from the plate thickness direction (Z-axis direction), region R2 is approximately rectangular in shape with its longer side extending in the longitudinal direction (X-axis direction). In this embodiment, the longitudinal dimension Xa of region R2 is 548 mm, and the short-side dimension Ya of region R2 is 448 mm.

[0023] Multiple through-holes 11 are formed in region R2. Each through-hole 11 penetrates the metal substrate 15 in the thickness direction (Z-axis direction). Viewed from the thickness direction, each through-hole 11 is approximately rectangular in shape, with its longer side extending in the longitudinal direction (X-axis direction). In this embodiment, the longitudinal dimension Xh of each through-hole 11 is 1000 μm. In this embodiment, the short-side dimension Yh of each through-hole 11 is 280 μm. The dimensions of each through-hole 11 are not limited to these. Note that the dimensions of each through-hole 11 are those when viewed from the surface side (-Z side) of the through-hole 11 shown in Figure 3B. Note that the dimensions of each through-hole 11 are the same when viewed from the back side (+Z side).

[0024] As shown in Figure 2, in this embodiment, the longitudinal pitch Xp in which each through-hole 11 is formed is 2 mm. In this embodiment, the transverse pitch Yp in which each through-hole 11 is formed is 1 mm. The longitudinal pitch Xp and transverse pitch Yp in which each through-hole 11 is formed are not limited to these values. In the metal mask 10 of this embodiment, 274 through-holes 11 are formed in the longitudinal direction and 448 through-holes 11 are formed in the transverse direction. The metal mask 10 of this embodiment has 122,752 through-holes 11. Each through-hole 11 is formed by a wet etching process in the through-hole formation process P02 described later.

[0025] Figure 3A is a schematic cross-sectional view of a sputtering apparatus 20 using the metal mask 10 of this embodiment. As described above, in this embodiment, the internal electrodes 28 of the MCLL are formed by the sputtering method. The sputtering apparatus 20 includes a tray 21, a magnet 22, and a target 23.

[0026] The tray 21 is a container-shaped structure that opens towards the target 23. Inside the tray 21 are the carrier film 25, the green sheet 26, and the metal mask 10. The magnet 22 is fixed to the side of the tray 21 that faces away from the target 23. The target 23 is positioned below the tray 21. In this embodiment, the target 23 is, for example, nickel. The target 23 may also be a nickel alloy mainly composed of nickel, including aluminum, silver, copper, and platinum.

[0027] The carrier film 25 holds the green sheet 26. The carrier film 25 is a film that extends in the longitudinal direction (X-axis direction) and the transverse direction (Y-axis direction). The upper and lower surfaces of the carrier film 25 are each coated with an adhesive. The carrier film 25 is attached to the bottom surface of the tray 21. The carrier film 25 is peelable from the bottom surface of the tray 21.

[0028] The green sheet 26 is a sheet that extends in the longitudinal direction (X-axis direction) and the transverse direction (Y-axis direction). In the MLCC, the green sheet 26 plays the role of a dielectric layer. In this embodiment, the green sheet 26 is composed of a layer about 1 μm thick, which is formed by, for example, die-coating a slurry mainly composed of barium titanate onto the surface of a PET sheet and drying it. The green sheet 26 may be composed of other materials. The side of the green sheet 26 that faces away from the target 23 is attached to the carrier film 25. The green sheet 26 is peelable from the carrier film 25.

[0029] The metal mask 10 is positioned below the green sheet 26. In this embodiment, the first surface 10a of the metal mask 10, i.e., one surface, is positioned facing the target 23. As described above, the metal mask 10 is made of a magnetic alloy. Therefore, the magnet 22 applies an upward magnetic force to the metal mask 10. Consequently, the second surface 10c of the metal mask 10 is in close contact with the green sheet 26.

[0030] When voltages of opposite polarities are applied to the target 23 and the green sheet 26, nickel atoms are propelled from the target 23 toward the green sheet 26 by the ionic atoms of the inert gas supplied into the sputtering apparatus 20, if the target 23 is made of nickel. Some of the nickel atoms propagated toward the green sheet 26 pass through each through-hole 11 of the metal mask 10 and deposit on the surface of the green sheet 26. This forms internal electrodes 28 on the portion of the green sheet 26 facing each through-hole 11. In this embodiment, the thickness of the internal electrodes 28 formed on the surface of the green sheet 26 is approximately 150 nm. Once the desired thickness of internal electrodes 28 is formed on the surface of the green sheet 26, the voltage application to the target 23 and the green sheet 26 is terminated. After the carrier film 25 is peeled off the green sheet 26, an MLCC is manufactured using the green sheet 26 with the multiple internal electrodes 28 formed on it.

[0031] As described above, some of the nickel atoms that fly toward the green sheet 26 pass through each through-hole 11 of the metal mask 10 and are deposited on the surface of the green sheet 26. In contrast, some of the nickel atoms that fly toward the green sheet 26 adhere to the first surface 10a of the metal mask 10, so that nickel deposits are deposited on the first surface 10a. When one metal mask 10 is used repeatedly to form the internal electrodes 28, the deposits deposited on the first surface 10a of the metal mask 10 become thicker. In this embodiment, as described above, the first surface 10a of the metal mask 10 is roughened by etching, so the anchoring effect between the deposits and the first surface 10a can be enhanced. This can increase the adhesion strength between the deposits and the first surface 10a. Therefore, when forming the internal electrodes 28, it is possible to suppress the deposits from detaching from the first surface 10a, entering the through-holes 11, and adhering to the internal electrodes 28. Therefore, in this embodiment, the shape of the internal electrode 28 can be suitably stabilized, making it possible to obtain an internal electrode with good accuracy in the superposition of MLCCs.

[0032] Next, the manufacturing method of the metal mask 10 of this embodiment will be described. As shown in Figure 4, the manufacturing method of the metal mask 10 of this embodiment includes a thin-film etching step P01 in which etching is performed on the first surface 30a of the metal substrate 30, that is, one surface; a through-hole forming step P02 in which a plurality of through-holes 11 are formed in the metal substrate 15; and an inspection step P03 in which the positions of the plurality of through-holes 11 are measured.

[0033] In this embodiment, the thin-film etching process P01 includes a first thin-film etching process P011 in which etching is performed on the second surface 30c of the metal substrate 30, i.e., the other surface, and a second thin-film etching process P012 in which etching is performed on the first surface 30a of the metal substrate 30, i.e., one surface. The thin-film etching process P01 does not necessarily include the first thin-film etching process P011. In other words, in the thin-film etching process P01, etching is performed on at least the first surface 30a, and etching is not required on the second surface 30c. In this specification, "workers, etc." includes workers and equipment, etc. that perform the work in each process. Each work may be performed by workers alone, by equipment alone, or by both workers and equipment.

[0034] In the following description, the metal substrate 30 shown in Figure 5 is a thin-film metal substrate manufactured by rolling, with a length in the longitudinal direction (X-axis direction) equal to the longitudinal length Xm of the metal mask 10, and a length in the transverse direction (Y-axis direction) equal to the transverse length Ym of the metal mask 10. The metal substrate 15 described above is a thin-film metal substrate after a thin-film etching process P01 has been performed on the metal substrate 30. As will be described later, the thickness T0 of the metal substrate 30 is reduced by the first thin-film etching process P011 and the second thin-film etching process P012. Therefore, the thickness Tm of the metal substrate 15 is thinner than the thickness T0 of the metal substrate 30.

[0035] The metal substrate 30 has a first surface 30a facing the front side (-Z side) and a second surface 30c facing the back side (+Z side). The first surface 30a is one surface of the metal substrate 30, and the second surface 30c is the other surface of the metal substrate 30.

[0036] In the first thin-filming step P011, the worker performs an etching treatment on the second surface 30c, i.e., the other surface, of the metal substrate 30 manufactured by rolling. In this embodiment, the worker performs a wet etching treatment on the second surface 30c of the metal substrate 30. This reduces the thickness T0 of the metal substrate 30 and roughens the second surface 30c, forming the second surface 10c of the metal mask 10. In other words, the second surface 10c, i.e., the other surface, of the metal substrate 15 is etched. This makes it possible to increase the surface roughness of the second surface 10c of the metal substrate 15. The etching depth of the second surface 30c, i.e., the other surface, in the first thin-filming step P011 is called the first etching depth D1. The first etching depth D1 is the dimension in the thickness direction (Z-axis direction) of the metal substrate 30 that is removed in the first thin-filming step P011. In other words, in the first thin-filming step P011, the back side (+Z side) of the metal substrate 30 is removed. The first thin-filming step P011 is completed when the etching treatment applied to the second surface 30c of the metal substrate 30 is finished.

[0037] Furthermore, if the thin-film etching process P01 does not include the first thin-film etching process P011, that is, if the second surface 30c of the metal substrate 30 is not etched, then the second surface 10c of the metal substrate 15 is the second surface 30c of the metal substrate 30. In this case, the second surface 10c of the metal substrate 15 is not roughened.

[0038] As described above, the metal substrate 30 in this embodiment is manufactured by rolling. When the metal substrate 30 is manufactured by rolling, the first surface 30a and the second surface 30c of the metal substrate 30 are stretched in the rolling direction. In this embodiment, the rolling direction of the metal substrate 30 is the longitudinal direction (X-axis direction). As a result, rolling streaks extending in the longitudinal direction are formed on each of the first surface 30a and the second surface 30c. Therefore, as shown in Figure 6, rolling streaks extending in the longitudinal direction are clearly visible on the second surface 30c of the metal substrate 30 before etching is performed in the first thin-filming step P011. In contrast, when etching is performed on the second surface 30c in the first thin-filming step P011, as described above, the back side (+Z side) of the metal substrate 30 is removed. Therefore, as shown in Figure 7, rolling streaks are not clearly visible on the second surface 10c of the metal substrate 15 after etching. Furthermore, as mentioned above, the rolling marks on the second surface 30c are marks that occur when the base material in the preceding process of the metal substrate 30 is stretched in the rolling direction. Therefore, when the rolling marks are removed by etching, the residual stress that remained in the metal substrate 30 when it was manufactured by rolling is relieved. As a result, the warping of the metal substrate 15 is reduced, and the flatness of the metal mask 10 is improved.

[0039] In the second thin-filming step P012, the worker performs an etching treatment on the first surface 30a of the metal substrate 30, i.e., one of its surfaces. In this embodiment, the worker performs a wet etching treatment on the first surface 30a of the metal substrate 30. As a result, as shown in Figure 5, the thickness T0 of the metal substrate 30 is reduced, and the first surface 30a is roughened, forming the first surface 10a of the metal mask 10. In other words, the first surface 10a of the metal substrate 15, i.e., one of its surfaces, is etched. This makes it possible to increase the surface roughness of the first surface 10a of the metal substrate 15. The etching depth of the first surface 30a, i.e., one of its surfaces, in the second thin-filming step P012 is called the second etching depth D2. The second etching depth D2 is the dimension in the thickness direction (Z-axis direction) of the metal substrate 30 that is removed in the second thin-filming step P012. In other words, in the second thin-filming step P012, the surface side (-Z side) of the metal substrate 30 is removed. In this embodiment, the first etching depth D1 is less than or equal to the second etching depth D2. That is, the etching depth of the other surface in the first thinning step P011 is less than or equal to the etching depth of one surface in the second thinning step P012. When the second thinning step P012 is completed, the thinning etching step P01 is completed.

[0040] Although not shown in the diagram, similar to the first thin-filming step P011 described above, in the second thin-filming step P012, rolling streaks are not significantly observed on the first surface 10a of the metal substrate 15 after etching. Therefore, residual stress remaining in the metal substrate 30 when it was manufactured by rolling is more effectively relieved. As a result, the warping of the metal substrate 15 is more effectively reduced, and the flatness of the metal mask 10 is more effectively improved. Note that if the etching conditions for the first thin-filming step P011 and the second thin-filming step P012 are set in advance and the etching is performed simultaneously, the second surface 30c and the first surface 30a of the metal substrate 30 can be etched simultaneously, and this may be applied as appropriate.

[0041] Figure 3B shows a cross-sectional view of the through-holes 11 in the short-side direction of a metal mask 10 having through-holes 11. In the through-hole formation process P02, an operator forms multiple through-holes 11 in the metal substrate 15. As shown in Figure 4, in this embodiment, the through-hole formation process P02 includes a first etching process P021 in which etching is performed on the second surface 10c of the metal substrate 15, i.e., the other surface, and a second etching process P022 in which etching is performed on the first surface 10a of the metal substrate 15, i.e., one surface. Thus, in this embodiment, multiple through-holes 11 are formed by a so-called two-stage etching process, in which wet etching is performed separately on the second surface 10c and the first surface 10a of the metal substrate 15.

[0042] In the first etching step P021, the operator etches the second surface 10c of the metal substrate 15. First, the operator adheres a resist (not shown) to both the second surface 10c and the first surface 10a of the metal substrate 15. Next, the operator exposes and develops both sides of the metal substrate 15 using an exposure mask to create multiple holes in the resist. The multiple holes formed in the resist are formed in positions and shapes corresponding to the through holes 11 formed in the metal mask 10. After that, the operator laminates the resist with holes on the first surface 10a side of the metal substrate 15 with a protective film, and then etches the second surface 10c of the metal substrate 15. When holes of the desired shape and depth are formed on the second surface 10c of the metal substrate 15, the operator finishes the etching of the second surface 10c. When the operator removes the resist provided on the second surface 10c, the first etching step P021 is completed.

[0043] In the second etching step P022, the worker protects the second surface 10c of the metal substrate 15 with an etching-resistant resin such as a gravure coat. After that, the worker removes the protective film of the resist with holes on the first surface 10a side, and then etches the first surface 10a of the metal substrate 15 through the resist with holes on the first surface 10a side. When holes of the desired shape and depth are formed on the first surface 10a of the metal substrate 15, and these holes connect with the holes formed on the second surface 10c to form through-holes 12, the worker completes the etching process on the first surface 10a. After that, the worker removes the resist with holes on the first surface 10a side of the metal substrate 15, and the etching-resistant resin protecting the second surface 10c of the metal substrate 15, and the second etching step P022 is completed. When the second etching step P022 is completed, the through-hole formation step P02 is completed. At this time, the metal substrate 15 has a plurality of through-holes 11 as shown in Figure 1. When multiple through holes 11 are formed in the metal substrate 15, the metal mask 10 is completed.

[0044] As shown in Figure 3B, the dimensions of the through-hole 11 formed in the metal substrate 15, as viewed from the thickness direction (Z-axis direction), are smallest at the through-hole portion 12 in the middle of the thickness direction of the metal substrate 15. In this embodiment, the shape and dimensions of the through-hole portion 12 as viewed from the thickness direction are the same as the shape and dimensions of the through-hole 11 described in Figures 1 and 8, etc.

[0045] The etching method in the through-hole formation step P02 is not limited to this embodiment. Multiple through-holes 11 may be formed by a so-called one-stage etching process, in which etching is performed simultaneously on both the second surface 10c and the first surface 10a of the metal substrate 15. Alternatively, etching may be performed on the first surface 10a first, followed by etching on the second surface 10c.

[0046] In order to increase capacitance in an MLCC, it is necessary to suppress the misalignment of the opposing internal electrodes 28. Therefore, it is necessary to suppress variations in the position of each internal electrode 28 formed on the green sheet 26. Consequently, in the through-hole formation process P02, it is necessary to suppress variations in the position of each through-hole 11 formed on the metal substrate 15.

[0047] According to this embodiment, the second surface 10c of the metal substrate 15, i.e., the other surface, is subjected to etching. Therefore, the surface roughness of the second surface 10c of the metal substrate 15 can be increased, and when forming multiple through holes 11 by wet etching in the through-hole formation process P02, the adhesion between the second surface 10c of the metal substrate 15 and the resist can be improved. This makes it easier to form the desired through holes in the metal substrate 15. Consequently, the desired shape of the internal electrodes 28 of the MLCC formed using the metal mask 10 can be easily formed, and an internal electrode with good overlapping accuracy of the MLCC can be obtained. Even if the other surface is not subjected to etching, if the adhesion between the second surface 10c of the metal substrate 15 and the resist is sufficient when forming multiple through holes 11, it is easy to form through holes 11 of the desired shape in the metal substrate 15.

[0048] According to this embodiment, the first surface 10a of the metal substrate 15, that is, one surface, is subjected to etching. Therefore, the surface roughness of the first surface 10a of the metal substrate 15 can be increased, and in the through-hole formation process P02, when forming multiple through-holes 11 by wet etching, the adhesion between the first surface 10a of the metal substrate 15 and the resist can be improved. As a result, through-holes 11 of the desired shape can be easily formed in the metal substrate 15. Therefore, an internal electrode 28 of the MLCC with less shape variation can be obtained using the metal mask 10.

[0049] In inspection step P03, the operator measures the positions of multiple through-holes 11. To obtain internal electrodes with good overlapping accuracy of MLCCs, it is necessary to suppress variations in the position of each through-hole 11 formed in the metal mask 10. Therefore, in this embodiment, in inspection step P03, the positions of multiple through-holes 11 formed in the metal mask 10 are measured. As shown in Figure 8, in this embodiment, when measuring the positions of multiple through-holes 11, the leftmost (-X side) and furthest back (-Y side) through-hole 11 is used as reference A, and the center position (X(n), Y(n)) of the through-hole 11 is measured. X(n) is the distance in the longitudinal direction (X-axis direction) between reference A and the center of the through-hole 11. Y(n) is the distance in the short direction (Y-axis direction) between reference A and the center of the through-hole 11.

[0050] In this embodiment, the center positions of multiple through holes 11 are measured from the center of the through hole 11 formed on the leftmost (-X side) and furthest back (-Y side), with a measurement pitch Xmp in the longitudinal direction (X axis direction) of 6 mm and a measurement pitch Ymp in the short direction (Y axis direction) of 3 mm. As described above, the longitudinal pitch Xp in which each through hole 11 is formed is 2 mm, and the short direction pitch Yp is 1 mm. Therefore, in inspection step P03 of this embodiment, the center position of the through hole 11 is measured every three through holes 11 along the longitudinal direction, and every three through holes 11 along the short direction. The position of the through hole 11 formed on the leftmost and furthest back is measured first, and the center position of such through hole 11 is (X(1), Y(1)). The center position of the nth through hole 11 to be measured is (X(n), Y(n)). In inspection step P03 of this embodiment, the positions of 13,800 through holes 11 are measured. The position of each through-hole 11 is measured by a first measuring device (not shown). In this embodiment, the first measuring device is a Mitutoyo QuickVision Active QV-L202Z1L-D. The first measuring device may be any other measuring device. In this embodiment, the positions of the multiple through-holes 11 are measured with the metal mask 10 placed on a measuring stage of the first measuring device. Once the operator has measured the positions of 13,800 through-holes 11, inspection process P03 is completed. When inspection process P03 is completed, the manufacturing process of the metal mask 10 is completed.

[0051] In this embodiment, metal masks 10 in which the position of each through-hole 11 is within the desired tolerance are shipped sequentially and used in the sputtering apparatus 20 described above to form the internal electrodes 28. On the other hand, metal masks 10 in which the position of the through-hole 11 is outside the desired tolerance are judged to be defective and discarded. In inspection step P03, the position of the through-hole 11 may be measured for all completed metal masks 10, or, for example, the position of the through-hole 11 may be measured only for metal masks 10 sampled from each manufacturing lot of the metal substrate 30 and each manufacturing lot of the resist.

[0052] Next, the relationship between the in-plane range F and the average range Xrave in the metal mask 10 of this embodiment will be explained. First, the average range Xrave of this embodiment will be explained. The average range Xrave of this embodiment is an index that shows the repeatability of the measurement of the position of each through hole 11 in the longitudinal direction (X-axis direction). In this embodiment, the average range Xrave of the metal mask 10 is calculated as follows. First, the metal mask 10 is placed on the measurement stage of a first measuring device (not shown) with the second surface 10c facing upwards, and the measurement of the center position (X(n), Y(n)) of each of the multiple through holes 11 is repeated five times. Next, the hole range Xr(n), which is the difference between the maximum and minimum values ​​in the longitudinal direction (X-axis direction), i.e., the rolling direction, of the center position (X(n), Y(n)) of each of the multiple through holes 11, is calculated, and the average range Xrave, which is the average value of the hole range Xr(n) of the multiple through holes 11, is calculated.

[0053] Next, the in-plane range F of the metal mask 10 in this embodiment will be described. The in-plane range F in this embodiment is an index indicating the flatness of the metal mask 10. In this embodiment, the in-plane range F of the metal mask 10 is calculated as follows. First, the metal mask 10 is placed on the stage of a second measuring device (not shown) with the second surface 10c facing upwards, and the height Z(n) of multiple measurement points on the second surface 10c of the metal mask 10 is measured five times. Next, for each of the five measurements, the difference height ΔZ(n) is calculated by subtracting the minimum height, which is the lowest height among the heights Z(n) of each measurement point, from the height Z(n) of each measurement point. Next, the average difference height ΔZ(n)ave, which is the average value of the five difference heights ΔZ(n) of each measurement point, is calculated, and then the difference between the maximum and minimum values ​​of all average difference heights ΔZ(n)ave is calculated as the in-plane range F of the metal mask 10. As shown in Figure 8, in this embodiment, the measurement location for height Z(n) is the left side (-X side) and back side (-Y side) of the through hole 11 where the center position was measured. There are 13,800 measurement locations for the height Z(n) of the metal mask 10. Height Z(n) is the height of the nth measurement location in each of the five measurements. The measurement pitch in the longitudinal direction (X-axis direction) is 6 mm, and the measurement pitch in the transverse direction (Y-axis direction) is 3 mm. In this embodiment, the second measuring device for measuring the height Z(n) of the metal mask 10 is a Nikon NEXIV VMR-12072. The measuring device for measuring the height Zh(n) of the metal mask 10 may be any other measuring device.

[0054] In this embodiment, when the in-plane range F of the metal mask 10 is large, the contact points between the measuring stage and the metal mask 10 tend to vary each time the metal mask 10 is placed on the measuring stage of the first measuring device. As a result, when the in-plane range F of the metal mask 10 is large, the orientation of the metal mask 10 tends to change each time the metal mask 10 is placed on the measuring stage of the first measuring device. Therefore, in inspection step P03, the repeatability of measuring the center position (X(n), Y(n)) of each through hole 11 tends to vary. In other words, it is difficult to improve the repeatability of measuring the position of each through hole 11 in inspection step P03.

[0055] In this embodiment, when the in-plane range F of the metal mask 10 is small, variations in the contact points between the measuring stage and the metal mask 10 can be suppressed each time the metal mask 10 is placed on the measuring stage of the first measuring device. This improves the repeatability of measuring the position of each through-hole 11 in the inspection process P03. Therefore, the position of each through-hole 11 can be stably controlled in the inspection process P03.

[0056] Figure 9 is a table showing the in-plane range F and average range Xrave of the metal mask 10. The present invention will be described in detail below with reference to Examples 1 to 10 and Comparative Examples 1 to 4 of the metal mask 10 of the present invention. However, the metal mask 10 of the present invention is not limited to the following Examples 1 to 10 and can be modified as appropriate without departing from the spirit of the invention.

[0057] According to the specifications shown in Figure 9, metal masks with at least one difference in the thickness T0 of the metal substrate 30, the first etching depth D1, and the second etching depth D2 were used as samples for Examples 1 to 10 and Comparative Examples 1 to 4. The depth difference ΔD shown in Figure 9 is the absolute value of the difference between the first etching depth D1 and the second etching depth D2.

[0058] As shown in Figure 9, for the metal masks 10 of Examples 1 to 10, the in-plane range F was 640 μm or less, resulting in good results with an average range Xrave of 3.0 μm or less. Therefore, the metal masks 10 of Examples 1 to 10 can improve the repeatability of measuring the position of each through-hole 11 in the rolling direction of the metal substrate 30. Thus, the position of each through-hole 11 can be stably controlled by the inspection process P03.

[0059] In contrast, for the metal masks of Comparative Examples 1 to 4, the in-plane range F was greater than 640 μm, resulting in an average range Xrave greater than 3.0 μm, and unsatisfactory results were not obtained. As described above, if the in-plane range F of the metal mask is too large, the contact points between the measuring stage and the metal mask tend to vary each time the metal mask is placed on the measuring stage of the first measuring device. As a result, the position of each through-hole 11 tends to vary each time the metal mask 10 is placed on the measuring stage of the first measuring device, and the average range Xrave tends to become large. Therefore, for the metal masks of Comparative Examples 1 to 4, whose in-plane range F is greater than 640 μm, it is difficult to improve the repeatability of the measurement of the position of each through-hole 11 in the rolling direction of the metal substrate 30. Consequently, it is difficult to stably control the position of each through-hole 11 in the inspection process P03.

[0060] Compared to the metal mask of Comparative Example 1, in which the first surface 10a and the second surface 10c of the metal mask are not etched, the metal masks 10 of Examples 4 and 9, in which the first surface 10a is etched, have a smaller in-plane range F. This is because, as described above, by etching the first surface 10a in the thin-film etching process P01, the residual stress that remained in the metal substrate 30 when it was manufactured by rolling is relieved, thereby reducing the warping of the metal substrate 15. Therefore, by etching the first surface 10a of the metal mask 10 in the thin-film etching process P01, the in-plane range F of the metal mask 10 can be reduced, and thus the average range Xrave can be reduced. Note that the surface of the metal mask 10 that is etched may be only the second surface 10c. In this case as well, the residual stress that remained in the metal substrate 30 when it was manufactured by rolling can be relieved, thus reducing the warping of the metal substrate 15. Therefore, the in-plane range F of the metal mask 10 can be reduced, thereby reducing the average range Xrave of the metal mask 10.

[0061] Furthermore, compared to the metal masks of Comparative Examples 2 to 4, which have a depth difference ΔD of 4.5 μm or more, the metal masks 10 of Examples 1 to 10, which have a depth difference ΔD of 3.0 μm or less, have a smaller in-plane range F. This is because, in the metal masks 10 of Examples 1 to 10, it is possible to suppress the difference between the residual stress remaining on the first surface 10a and the residual stress remaining on the second surface 10c from becoming too large, thereby suppressing excessive warping of the metal mask 10. In this embodiment, the depth difference ΔD is preferably 3.0 μm or less, and more preferably 1.5 μm or less.

[0062] According to this embodiment, the metal mask 10 is used when forming the internal electrodes 28 of a multilayer ceramic capacitor (MLCC), and has a plurality of through holes 11 provided in a metal substrate 15 made by rolling, and has an etching treatment on the first surface 10a, i.e., one surface, and when the mask is placed on a measurement stage and the heights Z(n) of multiple measurement points on the second surface 10c, i.e., the other surface facing the first surface 10a is measured five times, the difference obtained by subtracting the minimum height, which is the lowest height among the multiple measurement points, from the height Z(n) of each of the multiple measurement points in each of the five measurements is defined as the difference height ΔZ(n), and the average value of the difference heights ΔZ(n) of each of the multiple measurement points is defined as the average difference height ΔZ(n)ave, the in-plane range F, which is the difference between the maximum and minimum values ​​of the average difference height ΔZ(n)ave, is 640 μm or less. Therefore, in the thin-film etching process P01, etching the first surface 10a of the metal mask 10 can relieve residual stress remaining in the metal substrate 30 when it was manufactured by rolling. This reduces the warping of the metal substrate 15, allowing the in-plane range F of the metal mask 10 to be 640 μm or less. Consequently, the average range Xrave of the metal mask 10 can be reduced to 3.0 μm or less. This improves the repeatability of measuring the position of each through-hole 11 in the inspection process P03, allowing for stable control of the position of each through-hole 11. Consequently, it is possible to obtain internal electrodes with high accuracy in the superposition of MLCCs.

[0063] According to this embodiment, the second surface 10c of the metal mask 10, i.e., the other surface, is subjected to etching. Therefore, it is possible to suppress the depth difference ΔD of the metal mask 10 from becoming too large, and as described above, it is possible to suppress the difference between the residual stress remaining on the first surface 10a of the metal mask 10 and the residual stress remaining on the second surface 10c from becoming too large. As a result, it is possible to more effectively suppress the warping of the metal mask 10 from becoming too large, and thus the in-plane range F of the metal mask 10 can be more preferably set to 640 μm or less. Therefore, the average range Xrave of the metal mask 10 can be more preferably reduced to 3.0 μm or less. As a result, in the inspection process P03, the repeatability of the measurement of the position of each through hole 11 can be more preferably improved, and the position of each through hole 11 can be controlled more stably. Therefore, it is possible to more preferably suppress the variation in the position of the internal electrodes 28 of the MLCC formed using the metal mask 10, and thus obtain internal electrodes with good overlapping accuracy of the MLCC.

[0064] According to this embodiment, when the maximum and minimum values ​​of the center positions of each of the multiple through holes 11 in the rolling direction are taken as the hole range Xr after repeating the process of placing the material on the measurement stage and measuring the center position of each of the multiple through holes 11 five times, the average range Xrave, which is the average value of the hole range Xr of the multiple through holes 11, is 3 μm or less. Therefore, in the inspection process P03, the repeatability of the measurement of the position of each through hole 11 can be improved, and the position of each through hole 11 can be stably controlled. Consequently, variations in the position of the internal electrodes 28 of the MLCC formed using the metal mask 10 can be suppressed, and an internal electrode with good overlapping accuracy of the MLCC can be obtained.

[0065] According to this embodiment, the thickness Tm of the metal mask 10 is 38 μm or more and 52.5 μm or less. Therefore, it is possible to prevent the thickness Tm of the metal mask 10 from becoming too thin, and thus prevent the rigidity of the metal mask 10 in the thickness direction (Z-axis direction) from becoming too small. As a result, when the metal mask 10 is placed on the measurement stage of the first measuring device in inspection step P03, it is possible to prevent the metal mask 10 from bending in the thickness direction due to its own weight. Therefore, in inspection step P03, the repeatability of the measurement of the position of each through hole 11 can be more favorably improved. Furthermore, since it is possible to suppress the thickness Tm of the metal mask 10 from becoming too thick, it is possible to suppress the rigidity of the metal mask 10 in the thickness direction from becoming too large. As a result, in the first thinning process P011 and the second thinning process P012, the residual stress remaining in the metal substrate 30 is relieved, making it easier to reduce the warping of the metal substrate 15. Therefore, since it is easier to reduce the in-plane range F of the metal mask 10, the repeatability of measuring the position of each through hole 11 can be more favorably improved in the inspection process P03.

[0066] According to this embodiment, the method for manufacturing the metal mask 10 is used when forming the internal electrodes 28 of a multilayer ceramic capacitor (MLCC), and is a method for manufacturing a metal mask 10 made of a metal substrate 30 manufactured by rolling, comprising: a thin-film etching step P01 in which etching is performed on the first surface 30a of the metal substrate 30, i.e., one surface; and a through-hole forming step P02 in which a plurality of through-holes 11 are formed in the metal substrate 15. Therefore, as described above, by etching the first surface 10a of the metal mask 10 in the thin-film etching step P01, the in-plane range F of the metal mask 10 can be reduced to 640 μm or less. Consequently, the average range Xrave of the metal mask 10 can be reduced to 3.0 μm or less. As a result, the repeatability of measurement of the position of each through-hole 11 can be improved in the inspection step P03, and the position of each through-hole 11 can be stably controlled. Consequently, variations in the position of the internal electrodes 28 of the MLCC formed using the metal mask 10 can be suppressed, and internal electrodes with good overlapping accuracy of the MLCC can be obtained.

[0067] According to this embodiment, the thin-film etching process P01 includes a first thin-film etching process P011 in which etching is performed on the second surface 10c of the metal substrate 15, i.e., the other surface, that faces the first surface 10a, and a second thin-film etching process P012 in which etching is performed on the first surface 10a of the metal substrate 15, i.e., one surface. Therefore, as described above, it is possible to suppress the metal mask 10 from becoming too large in depth difference ΔD, and thus it is possible to more effectively suppress the metal mask 10 from becoming too large in warping. As a result, the in-plane range F of the metal mask 10 can be more preferably set to 640 μm or less. Consequently, the average range Xrave of the metal mask 10 can be more preferably reduced to 3.0 μm or less. Therefore, in the inspection process P03, the repeatability of measuring the position of each through-hole 11 can be improved, and the position of each through-hole 11 can be controlled more stably.

[0068] According to this embodiment, the etching depth D1 of the second surface 10c, i.e., the other surface, in the first thin-film deposition process P011 is less than or equal to the etching depth D2 of the first surface 10a, i.e., one surface, in the second thin-film deposition process P012. Therefore, the surface roughness of the first surface 10a can be more favorably increased, and when forming the internal electrode 28 in the sputtering apparatus 20, the adhesion strength between the deposit deposited on the first surface 10a of the metal mask 10 and the first surface 10a can be more favorably increased, as described above. Therefore, when forming the internal electrode 28, it is more favorably possible to suppress the deposit from detaching from the first surface 10a, entering the through-hole 11, and adhering to the internal electrode 28. Consequently, the shape of the internal electrode 28 can be more favorably stabilized, and an internal electrode with good accuracy in MLCC superposition can be obtained.

[0069] Although the present invention has been described above, the specific configuration of the metal mask is not limited to this embodiment, and modifications and combinations of the configuration that do not depart from the spirit of the present invention are also included.

[0070] The material constituting the metal mask according to the present invention is not limited to stainless steel such as SUS430 as described above. The material constituting the metal mask may be other magnetic metallic materials such as Invar and SuperInvar.

[0071] The configuration of the metal mask according to the present invention is not limited to this embodiment. For example, the shape of the through holes, the number of through holes, the pitch of the through holes in the longitudinal direction, and the pitch of the through holes in the short direction may differ from those of this embodiment.

[0072] The method for manufacturing a metal mask according to the present invention is not limited to this embodiment. For example, the second thin-film thinning step may be performed before the first thin-film thinning step, or the first and second thin-film thinning steps may be performed simultaneously if the processing conditions are suitable. In addition, during the inspection step, dimensions of the metal mask other than the center position of each through-hole, such as the thickness of the metal mask, may be measured. [Explanation of Symbols]

[0073] 10 Metal Masks 10a First face (one side) 10c Second face (the other face) 11 Through hole 15 Metal substrate 28 Internal electrode 30 Metal base material 30a First surface (one side) 30c Second face (the other face) D1 First etching depth (etching depth of the other surface) D2 Second etching depth (etching depth on one side) P01 Thin-film etching process P011 1st thinning process P012 Second thinning process P02 Through hole formation process Thickness of Tm metal mask Xr Hole Round Xrave Average Range

Claims

1. A metal mask used for fabricating internal electrodes of multilayer ceramic capacitors by sputtering, It has multiple through holes provided in a metal substrate manufactured by rolling, One side has been etched, When the measurement stage is placed and the heights of multiple measurement points on the other surface facing one of the aforementioned surfaces are measured five times, the difference obtained by subtracting the lowest height among the multiple measurement points from the height of each of the multiple measurement points in each of the five measurements is defined as the difference height, and the average value of the difference heights of each of the multiple measurement points is defined as the average difference height, the in-plane range, which is the difference between the maximum and minimum values ​​of the average difference height, is 640 μm or less. The aforementioned multiple measurement points consist of 13,800 points, with a measurement pitch of 6 mm in the longitudinal direction and a measurement pitch of 3 mm in the short direction of the metal mask. Metal mask.

2. The metal mask according to claim 1, wherein the other surface is subjected to etching.

3. When the measurement stage is used to measure the center position of each of the multiple through holes, and this process is repeated five times, the difference between the maximum and minimum values ​​in the rolling direction of the center position of each of the multiple through holes in the metal substrate is defined as the hole range. The metal mask according to claim 1 or 2, wherein the average range, which is the average value of the hole ranges of the multiple through holes, is 3 μm or less.

4. The metal mask according to claim 1 or 2, wherein the etching depth of one surface is 6.0 μm or less, and the difference between the etching depth of one surface and the etching depth of the other surface is 3.0 μm or less.

5. A metal mask according to claim 1 or 2, wherein the thickness is 38 μm or more and 52.5 μm or less.

6. A method for manufacturing a metal mask according to Claim 1, A thin-film etching process in which etching is performed on one side of the aforementioned metal substrate, A through-hole forming step of forming multiple through-holes in the metal substrate, A method for manufacturing a metal mask having the following characteristics.

7. The method for manufacturing a metal mask according to claim 6, wherein the thin-film etching step includes a first thin-film step of performing an etching treatment on the other surface of the metal substrate facing the one surface, and a second thin-film step of performing an etching treatment on the one surface.

8. The method for manufacturing a metal mask according to claim 7, wherein the etching depth of the other surface in the first thin-film deposition step is less than or equal to the etching depth of the one surface in the second thin-film deposition step.

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