Metal mask and method for producing same

Abstract

A metal mask comprises an effective region and a peripheral region. The effective region is provided with a plurality of through-holes. The plurality of through-holes allow first recessed portions on the first-surface side and second recessed portions on the second-surface side to communicate. The opening area of the first recessed portions is less than the opening area of the second recessed portions. The opening shape of the second recessed portions is quadrangular. Connection portions that connect the first recessed portions and the second recessed portions are circular or substantially circular. The plurality of through-holes are disposed in a staggered manner in the effective region. Adjacent second recessed portions are separated from each other by a top portion.

Description

Metal mask and its manufacturing method

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

[0002] The pixels of each color in an organic EL display device are formed by depositing a pixel-forming material on a substrate by vapor deposition using a metal mask. When using a metal mask to form a film of a vapor deposition material on a substrate, it is necessary to vapor deposit the vapor deposition material on the substrate with high precision. This requires that through-holes in the metal mask be formed with high precision. For example, Patent Document 1 discloses a method for manufacturing a metal mask in which recesses are formed by etching from both sides of a metal plate and through-holes are formed by connecting the recesses.

[0003] Japanese Patent Application Laid-Open No. 2015-163734

[0004] During the deposition process, the deposition material travels from the deposition source toward the metal mask, passes through the through-holes in the metal mask, and adheres to the deposition target, such as an organic EL substrate. In this process, some of the deposition material may adhere to the wall surfaces of the through-holes rather than the substrate, resulting in a thinner deposition layer on the substrate near the wall surfaces of the through-holes. This phenomenon, in which the deposition material is hindered by the wall surfaces of the metal mask or the like, resulting in a thinner deposition layer, is called a "shadow."

[0005] To suppress such shadows, a mask has been devised that is etched to make the thickness of the effective area thinner. However, etching the effective area thinner tends to reduce the mechanical strength of the effective area. Furthermore, the thinner the etching, the more excessively etched the hole shape becomes when viewed from above, causing distortion of the hole shape. In addition, the hole shape may also be deformed by tension when stretched.

[0006] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a metal mask that can suppress deformation of the hole shape in plan view while suppressing shadows, and a method for manufacturing the same.

[0007] A metal mask according to one embodiment of the present disclosure has an effective area and a surrounding area, the effective area having a plurality of through holes, the plurality of through holes connecting a first recess on a first surface side to a second recess on a second surface side, the opening area of ​​the first recess being smaller than the opening area of ​​the second recess, the opening shape of the second recess being rectangular, the shape of the connection between the first recess and the second recess being circular or approximately circular, the plurality of through holes being arranged in a staggered pattern in the effective area, and adjacent second recesses being separated by top portions.

[0008] A method for manufacturing a metal mask according to one embodiment of the present disclosure includes: a step of preparing a metal plate; and an etching step of forming the metal mask by etching the metal plate, wherein the metal mask has an effective area and a surrounding area, the effective area includes a plurality of through holes, the plurality of through holes are connected to a first recess on a first surface side and a second recess on a second surface side, the opening area of ​​the first recess is smaller than the opening area of ​​the second recess, the opening shape of the second recess is rectangular, the shape of the connection between the first recess and the second recess is circular or approximately circular, the plurality of through holes are arranged in a staggered pattern in the effective area, and adjacent second recesses are separated by top portions.

[0009] According to the present disclosure, it is possible to provide a metal mask and a manufacturing method thereof that can suppress deformation of the hole shape in a plan view while suppressing shadows.

[0010] 2A. FIG. 2B is a plan view showing a metal mask according to an embodiment of the present disclosure. FIG. 2C is a top view showing one aspect of the effective area when viewed from the second surface side. FIG. 2D is a perspective view showing one aspect of the effective area when viewed from the second surface side. FIG. 2E is a bottom view showing one aspect of the effective area when viewed from the first surface side. FIG. 2F is a cross-sectional view taken along line II' in FIG. 2A. FIG. 2G is a cross-sectional view taken along line II-II' in FIG. 2A. FIG. 2H is a cross-sectional view taken along line III-III' in FIG. 2A. FIG. 2H is a schematic view for explaining an example of a method for manufacturing a metal mask. FIG. 2G is a view showing an example of a process for forming a resist film on a metal plate. FIG. 2H is a view showing an example of a process for patterning the resist film. FIG. 2H is a view showing an example of a first surface etching process in the effective area. FIG. 2H is a view showing an example of a second surface etching process in the effective area. FIG. 2I is a view showing a metal mask apparatus according to an embodiment of the present disclosure. FIG. 2I is a cross-sectional view showing a vapor deposition apparatus according to an embodiment of the present disclosure. FIG. 2I is a table showing data for examples and comparative examples of the present disclosure.

[0011] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. Note that in the drawings attached to this specification, the scale and aspect ratios may be appropriately changed and exaggerated from those of the actual objects for the sake of convenience in illustration and understanding.

[0012] In this specification and / or drawings, unless otherwise specified, the following interpretations shall be made.

[0013] Terms that refer to a material that is the basis of a certain structure do not necessarily need to be distinguished by differences in name alone. For example, terms such as "substrate," "base material," "plate," "sheet," or "film" fall under the above description.

[0014] Terms and / or numerical values ​​that represent shapes and / or geometric conditions need not be bound by strict meanings and may be interpreted as including a range within which similar functions may be expected. For example, "parallel" and / or "orthogonal" fall under the above terms. Also, "length value" and / or "angle value" fall under the above numerical values.

[0015] When a certain configuration is expressed as being "above," "below," "upper," "lower," "above," or "below" another configuration, this may include a configuration in which the certain configuration is in direct contact with the other configuration, and a configuration in which another configuration is included between the certain configuration and the other configuration. In other words, a configuration in which another configuration is included between the certain configuration and the other configuration may be expressed as a configuration indirectly in contact with the other configuration. Furthermore, the expressions "above," "upper side," or "above" are interchangeable with the expressions "below," "lower side," or "below." In other words, the up-down direction may be reversed.

[0016] When the same or similar symbols are used to denote identical parts and / or parts having similar functions, repeated descriptions may be omitted. Also, the dimensional ratios in the drawings may differ from the actual ratios. Also, some of the configurations of the embodiments may be omitted from the drawings.

[0017] One or more embodiments may be combined with one or more modified embodiments as long as no contradictions arise. Also, one or more embodiments may be combined with each other as long as no contradictions arise. Also, one or more modified embodiments may be combined with each other as long as no contradictions arise.

[0018] When a plurality of steps are disclosed for a method such as a manufacturing method, other steps that are not disclosed may be performed between the disclosed steps. Furthermore, the order of the steps is not limited to the extent that no contradiction occurs.

[0019] Numerical ranges expressed with the symbols "to" and / or "-" include the numerical values ​​before and after the symbols "to" and / or "-". For example, a numerical range expressed as "34 to 38% by mass" is the same as a numerical range expressed as "34% by mass or more and 38% by mass or less".

[0020] For the numerical values ​​described in this disclosure, a numerical range may be defined by combining any one of a plurality of upper limit candidate values ​​with any one of a plurality of lower limit candidate values. In addition, even if not specifically mentioned, a numerical range may be defined by combining any two of a plurality of upper limit candidate values, or a numerical range may be defined by combining any two of a plurality of lower limit candidate values.

[0021] An embodiment of the present disclosure will be described in the following paragraphs. The embodiment of the present disclosure is an example of an embodiment of the present disclosure. The present disclosure is not construed as being limited to only the embodiment of the present disclosure.

[0022] The metal mask of the present disclosure can be used for various applications. For example, without limitation, the metal mask of the present disclosure can be used as a metal mask used to pattern an organic material into a desired pattern on a substrate in the manufacture of an organic electroluminescent (EL) display device. Such a metal mask is also called a deposition mask. Furthermore, the metal mask of the present disclosure can enable high-pixel-density patterning. Organic EL display devices that can be manufactured include displays for smartphones, televisions, and the like, as well as devices for displaying or projecting images and videos to express virtual reality (VR) and augmented reality (AR).

[0023] Unless otherwise specified in the present specification and drawings, an example of a metal mask used in manufacturing an organic EL display device and a manufacturing method thereof will be described as one embodiment of the present disclosure.

[0024] A first aspect of the present disclosure is a metal mask having an effective area and a peripheral area, wherein the effective area is provided with a plurality of through holes, wherein the plurality of through holes are connected between a first recess on a first surface side and a second recess on a second surface side, wherein the opening area of ​​the first recess is smaller than the opening area of ​​the second recess, wherein the opening shape of the second recess is rectangular, and wherein the shape of the connection between the first recess and the second recess is circular or approximately circular, wherein the plurality of through holes are arranged in a staggered pattern in the effective area, and wherein adjacent second recesses are separated by top portions.

[0025] In a second aspect of the present disclosure, in the metal mask according to the first aspect described above, the opening shape of the first recess may be circular or approximately circular.

[0026] In a third aspect of the present disclosure, in the metal mask of the first or second aspect described above, one of the diagonals of the opening shape of the second recess may be approximately parallel to the longitudinal direction of the metal mask or a width direction perpendicular to the longitudinal direction.

[0027] In a fourth aspect of the present disclosure, in the metal mask of any of the first to third aspects described above, a long diagonal line among the diagonal lines of the opening shape of the second recess may be approximately parallel to the longitudinal direction of the metal mask.

[0028] In a fifth aspect of the present disclosure, in the metal mask of any one of the first to fourth aspects described above, the curvature of a corner of the opening shape of the second recess may be 0.010 to 0.150 / μm.

[0029] In a sixth aspect of the present disclosure, in the metal mask of any of the first to fifth aspects described above, the curvature of the second corner is smaller than the curvature of the first corner, the first corner may be a corner of the opening shape of the second recess that is aligned in a direction approximately perpendicular to the extension direction, and the second corner may be a corner of the opening shape of the second recess that is aligned in the extension direction.

[0030] In a seventh aspect of the present disclosure, in the metal mask of any one of the first to sixth aspects described above, the circularity of the connection portion is 0 to 5 μm.

[0031] In an eighth aspect of the present disclosure, in the metal mask of any one of the first to seventh aspects described above, the minimum width W of the top portion separating adjacent second recesses is 0.1 to 20 μm.

[0032] In a ninth aspect of the present disclosure, in the metal mask of any one of the first to eighth aspects described above, the top portions constituting the sides of the rectangular shape of the four second recesses arranged in a staggered pattern meet at one intersection.

[0033] A tenth aspect of the present disclosure is a method for manufacturing a metal mask, comprising: a step of preparing a metal plate; and an etching step of forming the metal mask by etching the metal plate, wherein the metal mask has an effective area and a peripheral area, the effective area has a plurality of through holes, the plurality of through holes are connected to first recesses on a first surface side and second recesses on a second surface side, the opening area of ​​the first recesses is smaller than the opening area of ​​the second recesses, the opening shape of the second recesses is quadrangular, the shape of the connection between the first recesses and the second recesses is circular or approximately circular, the plurality of through holes are arranged in a staggered pattern in the effective area, and adjacent second recesses are separated by top portions.

[0034] The metal mask 20 of the present disclosure will be described in detail below.

[0035] The metal mask 20 of the present disclosure has an effective area 22 and a peripheral area 23. The effective area 22 is an area in which a plurality of through holes 25 are formed in an arbitrary shape and an arbitrary pattern. The peripheral area 23 is an area located around the effective area 22.

[0036] 1 shows a plan view of the second surface 20b side of a metal mask 20 according to an embodiment of the present disclosure. As shown in FIG. 1, the metal mask 20 may have a substantially rectangular outline in plan view. In this disclosure, the term "plan view" refers to viewing the metal mask 20 from a surface along the plate surface of the metal mask 20.

[0037] In the metal mask 20 of the present disclosure, one effective area 22 may be configured to correspond to one organic EL display device. For example, as shown in FIG. 1 , the metal mask 20 may have multiple effective areas 22 arranged in a row at predetermined intervals along the longitudinal direction D2. In FIG. 1 , a peripheral area 23 is located around each effective area 22. By using such a metal mask 20, it is possible to vapor-deposit multiple organic EL display devices onto a substrate 92, which will be described later. Alternatively, one effective area 22 may be configured to correspond to multiple organic EL display devices.

[0038] The material for forming the metal mask 20 is not particularly limited, but examples thereof include iron alloys containing nickel, iron alloys containing chromium such as stainless steel, nickel, and nickel-cobalt alloys.

[0039] Among these, an iron alloy containing nickel is preferable. By using an iron alloy containing nickel, the thermal expansion coefficient of the metal mask 20 can be made equal to the thermal expansion coefficient of the frame 15 and the thermal expansion coefficient of the substrate 92 (see FIG. 5 ). This makes it possible to suppress misalignment caused by differences in dimensional changes among the metal mask 20, the frame 15, and the substrate 92 during the vapor deposition process. Therefore, it is possible to suppress a decrease in the dimensional accuracy and positional accuracy of the vapor deposition material 98 attached to the substrate 92 caused by misalignment.

[0040] The iron alloy containing nickel is not particularly limited, but examples thereof include iron alloys containing 0% by mass or more and 54% by mass or less of nickel, such as a super invar material containing 30% by mass or more and 34% by mass or less of nickel and further containing cobalt, an invar material containing 34% by mass or more and 38% by mass or less of nickel, and a low-thermal expansion Fe—Ni-based plated alloy containing 48% by mass or more and 54% by mass or less of nickel.

[0041] Next, a description will be given of the surfaces of the metal mask 20 of the present disclosure. The metal mask 20 of the present disclosure has a first surface 20a and a second surface 20b as front and back surfaces.

[0042] In the present disclosure, the first surface 20a and the second surface 20b of the metal mask 20 are distinguished by the diameter of the through holes 25 on the front and back surfaces of the effective area 22. Specifically, as shown in Figures 2A to 2F, etc., the first surface 20a refers to the surface in the effective area 22 where the opening area of ​​the through holes 25 is small, and the second surface 20b refers to the surface where the opening area of ​​the through holes 25 is large.

[0043] From the viewpoint of the vapor deposition process, the first surface 20a may be the surface of the metal mask 20 that faces the substrate 92 when the metal mask device 10 is housed in the vapor deposition device 90 (see FIG. 5). The second surface 20b may be the surface of the metal mask 20 that faces the crucible 94 that holds the vapor deposition material 98 when the metal mask device 10 is housed in the vapor deposition device 90 (see FIG. 5).

[0044] Next, the pattern of the deposition layer to be attached to the substrate 92 and the pattern of the through holes 25 in the effective area 22 of the metal mask 20 for forming the deposition layer will be described.

[0045] 2A and 2B are a top view and a perspective view showing one aspect of the effective area 22 when viewed from the second surface 20b side. The through-holes 25 penetrate the metal mask 20 in the thickness direction N from the first surface 20a to the second surface 20b. In the vapor deposition process, the vapor deposition material 98 passes through the through-holes 25 and is deposited on the substrate 92.

[0046] The arrangement pattern of the through holes 25 in the effective area 22 corresponds to the pattern in which the vapor deposition material 98 is applied, and the arrangement of the through holes 25 is formed in accordance with the pattern of the vapor deposition layer of each color, such as red R, green G, or blue B. Therefore, when the application pattern differs depending on the type of vapor deposition material 98, a metal mask 20 having a different arrangement pattern of the through holes 25 may be used depending on the type of vapor deposition material 98. For example, different metal masks 20 may be used to sequentially vapor-deposit the red vapor deposition material 98, the green vapor deposition material 98, and the blue vapor deposition material 98 onto the substrate 92.

[0047] Furthermore, when the pattern for depositing the vapor deposition material 98 is the same regardless of color, for example, when the pattern for depositing red R and blue B is the same, the same metal mask 20 may be used. In this case, the metal mask 20 and the substrate 92 may be moved relative to each other, so that the red vapor deposition material 98, the green vapor deposition material 98, and the blue vapor deposition material 98 are deposited in the same pattern in that order using one metal mask 20.

[0048] Next, the aspects of the through-holes 25 in the effective area 22 will be described in more detail with reference to Figures 2A to 2F. Figure 2C is a bottom view showing one aspect of the effective area 22 when viewed from the first surface 20a side. Figure 2D is a cross-sectional view taken along line II' in Figure 2A. Figure 2E is a cross-sectional view taken along line II-II' in Figure 2A. Figure 2F is a cross-sectional view taken along line III-III' in Figure 2A.

[0049] 2A and 2B , the effective area 22 includes a plurality of through holes 25, and adjacent second recesses 35 are separated by a top portion 32. As shown in FIGS. 2A and 2B , the metal mask of the present disclosure has a surface of the metal plate that remains unetched, which is referred to as the top portion 32. Here, being separated means that a continuous metal portion (top portion 32) remains between adjacent second recesses 35, and the second wall surfaces 36 of adjacent second recesses 35 are not in direct contact.

[0050] 2A to 2F, the through hole 25 has a first recess 30 formed in the first surface 20a, a second recess 35 formed in the second surface 20b, and a circumferential connecting portion 41 connecting the first recess 30 and the second recess 35. The through hole 25 is formed by connecting the first recess 30 on the first surface 20a side with the second recess 35 on the second surface 20b side. The portion where the first recess 30 and the second recess 35 are connected is referred to as the connecting portion 41. The first wall surface 31 of the first recess 30 and the second wall surface 36 of the second recess 35 are connected via the circumferential connecting portion 41.

[0051] The opening area of ​​the first recess 30 in a plan view may gradually decrease from the first surface 20 a to the second surface 20 b. The opening area of ​​the second recess 35 in a plan view may gradually decrease from the second surface 20 b to the first surface 20 a. As shown in Figures 2A and 2C , the opening area of ​​the first recess 30 is smaller than the opening area of ​​the second recess 35.

[0052] At the connection portion 41, the direction in which the wall surface of the through hole 25 expands changes discontinuously. Generally, the opening area of ​​the through hole 25 in a plan view is smallest at the connection portion 41. In the present disclosure, the hole shape of the through hole 25 refers to the shape defined by the connection portion 41 in a plan view.

[0053] 2A and 2B , in the present disclosure, the opening shape of the second recess 35 is rectangular, and the through hole 25 has a connecting portion 41 that is circular or approximately circular in plan view. For example, as shown in FIG. 2C , such a through hole 25 may be formed by making the opening shape of the first recess 30 circular or approximately circular. The connecting portion 41 of the through hole 25 is the narrowest part of the through hole 25 and defines the location where the deposition material 98 adheres to the substrate 92.

[0054] In the present disclosure, the size of the rectangular opening shape of the second recess 35 is not particularly limited, but the average side length 1 may be 40 μm or more, 45 μm or more, 50 μm or more, 55 μm or more, 60 μm or more, 65 μm or more, 70 μm or more, or 75 μm or more. The average side length 1 of the rectangular opening shape may be 125 μm or less, 120 μm or less, 115 μm or less, 110 μm or less, 105 μm or less, 100 μm or less, 95 μm or less, or 90 μm or less. Furthermore, the average side length 1 of the rectangular opening shape may be determined by combining any one of the plurality of lower limit candidate values ​​described above with any one of the plurality of upper limit candidate values ​​described above. Specifically, the average side length of the rectangular opening shape is preferably 40 to 125 μm, 55 to 110 μm, or even 70 to 95 μm. By having the average side length 1 within the above range, it is possible to suppress deformation of the hole shape in a plan view while suppressing shadows. The average side length refers to the average of the four sides of the rectangle of the second recess 35.

[0055] In the present disclosure, the term "approximately circular" includes an elliptical shape. The ratio of the major axis to the minor axis of the elliptical shape is preferably 1.0 or more and 1.2 or less, more preferably 1.0 or more and 1.1 or less, and may be 1.0 or more and 1.05 or less.

[0056] Furthermore, the circularity of the approximately circular shape is preferably 5.0 μm or less, 4.5 μm or less, 4.0 μm or less, 3.5 μm or less, 3.0 μm or less, 2.5 μm or less, 2.0 μm or less, 1.5 μm or less, or 1.0 μm or less. The lower limit of the circularity of the approximately circular shape is not particularly limited, but may be 0 μm or more, 0.5 μm or more, or 1.0 μm or more. Furthermore, the circularity may be determined by combining any one of the above-mentioned multiple lower limit candidate values ​​with any one of the above-mentioned multiple upper limit candidate values. Specifically, the circularity is preferably 0 to 5.0 μm, 0.5 to 4.0 μm, or 1.0 to 3.0 μm. Here, circularity refers to the difference in radius between the maximum circumscribing circle and the minimum inscribing circle. When the circularity of the substantially circular shape is within the above range, it tends to be possible to suppress deformation of the hole shape in a plan view while suppressing shadows.

[0057] The opening radius r of the circular or approximately circular through-hole 25 in a plan view is preferably 10 μm or more, 15 μm or more, 20 μm or more, 22 μm or more, or may be 24 μm or more. The opening radius r of the circular or approximately circular through-hole 25 is preferably 40 μm or less, 35 μm or less, 30 μm or less, or may be 28 μm or less. Furthermore, the range of the opening radius r may be determined by combining any one of the above-mentioned multiple lower limit candidate values ​​with any one of the above-mentioned multiple upper limit candidate values. Specifically, the opening radius r is preferably 10 to 40 μm, 15 to 35 μm, or may be 20 to 30 μm.

[0058] As shown in FIGS. 2A and 2B , the through holes 25 are arranged in a staggered pattern at a predetermined pitch along two mutually intersecting directions. In other words, the through holes 25 may be arranged alternately along the two mutually intersecting directions. Note that the two directions may or may not coincide with the longitudinal direction D2 or width direction D1 of the metal mask 20. In this case, as shown in FIGS. 2A and 2B , the top portions constituting the sides of the quadrangular shapes of the four second recesses arranged in a staggered pattern may meet at a single intersection. In other words, the four second recesses arranged in a staggered pattern may share a top portion constituting the quadrangular shape. This prevents distortion of the hole shape, resulting in a metal mask that suppresses deformation of the hole shape in a planar view.

[0059] In the present disclosure, the strength of the metal mask 20 is further improved by having the top portions 32 remaining unetched between adjacent second recesses 35. As a result, wrinkles and the like are less likely to occur when the metal mask 20 is stretched, which tends to further improve deposition accuracy. Furthermore, by having such top portions 32, it is possible to avoid distortion of the hole shape due to excessive etching, and a metal mask can be obtained that can suppress deformation of the hole shape in plan view.

[0060] Furthermore, in the present disclosure, by making the opening shape of the second recess 35 rectangular while having the top portion 32, it is possible to reduce the gradient from the edge of the second recess 35 toward the connecting portion 41, particularly the gradient in four directions from the four corners of the rectangular shape toward the connecting portion 41. This makes it possible to further suppress shadows. The rectangular shape may be a square, a rectangle, a parallelogram, etc., with a parallelogram being preferred and a rhombus being particularly preferred.

[0061] The minimum width W of the top portion 32 between adjacent second recesses 35 is preferably 0.1 μm or more, 0.5 μm or more, 1.0 μm or more, 1.5 μm or more, 2.0 μm or more, 2.5 μm or more, 3.0 μm or more, or even 3.5 μm or more. Furthermore, the minimum width W may be preferably 20 μm or less, 15 μm or less, 12.5 μm or less, 10 μm or less, 9.0 μm or less, 8.0 μm or less, 7.0 μm or less, or 6.0 μm or less. Furthermore, the minimum width W may be determined by combining any one of the above-mentioned multiple lower limit candidate values ​​with any one of the above-mentioned multiple upper limit candidate values. Specifically, the minimum width W is preferably 0.1 to 20 μm, 1.0 to 15 μm, or 1.5 to 10 μm. Here, the minimum width W refers to the smallest width in plan view of the top portion 32 separating adjacent second recesses 35. When the minimum width W is within the above range, it tends to be possible to suppress deformation of the hole shape in plan view while suppressing shadows.

[0062] Furthermore, in the present disclosure, it is preferable to arrange the through holes 25 in a staggered pattern, and in particular, to arrange one of the diagonals L1, L2 of the opening shape of the second recess 35 so that it is substantially parallel to the longitudinal direction D2 of the metal mask 20 or the width direction D1 perpendicular to the longitudinal direction D2. As a result, for example, when the metal mask 20 is stretched in the longitudinal direction D2, the top portion 32 extending in a direction oblique to the longitudinal direction D2 or the width direction D1 can distribute the force in the stretching direction. Therefore, it is possible to prevent the hole shape of the through holes 25 from being distorted by the force in the stretching direction, which tends to further improve deposition accuracy.

[0063] The average value of the diagonals L1 and L2 is preferably 60 μm or more, 70 μm or more, 80 μm or more, 90 μm or more, or even 95 μm or more. The minimum width W is preferably 150 μm or less, 140 μm or less, 130 μm or less, 120 μm or less, 110 μm or less, or 100 μm or less. Furthermore, the average value of the diagonals L1 and L2 may be determined by combining any one of the above-mentioned multiple lower limit candidate values ​​with any one of the above-mentioned multiple upper limit candidate values. Specifically, the average value of the diagonals L1 and L2 is preferably 60 to 150 μm, 70 to 130 μm, or even 80 to 110 μm. By keeping the average value of the diagonals L1 and L2 within the above range, deformation of the hole shape in a plan view tends to be suppressed while suppressing shadows.

[0064] The ratio (Ave(L1, L2) / 2r) of the average value of the diagonals L1 and L2 to the hole diameter is preferably 1.5 or more, 1.7 or more, 1.8 or more, or may be 1.9 or more. The ratio (Ave(L1, L2) / 2r) is preferably 5 or less, 4 or less, 3 or less, or 2.5 or less. Furthermore, the ratio (Ave(L1, L2) / 2r) may be determined by combining any one of the above-mentioned multiple lower limit candidate values ​​with any one of the above-mentioned multiple upper limit candidate values. Specifically, the ratio (Ave(L1, L2) / 2r) is preferably 1.5 to 5, 1.7 to 4, or 1.9 to 3. When the ratio (Ave(L1, L2) / 2r) is within the above range, deformation of the hole shape in plan view tends to be suppressed while suppressing shadows.

[0065] In the present disclosure, the stretching direction is preferably approximately parallel to the longitudinal direction D2 or the width direction D1, and more preferably approximately parallel to the longitudinal direction D2 as shown in FIG.

[0066] Furthermore, when the diagonals of the opening shape of the second recess have different lengths, it is preferable that the longer diagonal L2 be substantially parallel to the longitudinal direction D2 of the metal mask, which makes it possible to more effectively distribute the force in the stretching direction, further suppress deformation of the hole shape of the through hole 25, and tends to further improve deposition accuracy.

[0067] The corners of the opening shape of the second recess 35 do not need to be strictly right angles as shown in Figures 2A and 2B and may be rounded. For example, the curvatures of the corners of the opening shape of the second recess may each independently be preferably 0.010 / μm or more, 0.015 / μm or more, 0.020 / μm or more, 0.025 / μm or more, or 0.030 / μm or more. Furthermore, the curvatures of the corners of the opening shape of the second recess may each independently be preferably 0.150 / μm or less, 0.125 / μm or less, 0.100 / μm or less, 0.095 / μm or less, 0.090 / μm or less, or 0.085 / μm or less. By keeping the curvature of the corners of the opening shape of the second recess within the above range, the force in the stretching direction can be more effectively dispersed, deformation of the hole shape of the through hole 25 is more suppressed, and deposition accuracy tends to be further improved.

[0068] 2A and 2B, the first corner is a corner of the opening shape of the second recess aligned in a direction substantially perpendicular to the extension direction, and the second corner is a corner of the opening shape of the second recess aligned in the extension direction. In this case, it is preferable that the curvature R2 of the second corner is greater than the curvature R1 of the first corner. This makes it possible to more effectively distribute the force in the extension direction, further suppressing deformation of the hole shape of the through hole 25 and tending to further improve deposition accuracy.

[0069] The curvature R1 of the first corner may be preferably 0.010 / μm or more, 0.020 / μm or more, 0.030 / μm or more, 0.040 / μm or more, or 0.050 / μm or more. The curvature R1 of the first corner may be preferably 0.150 / μm or less, 0.125 / μm or less, 0.100 / μm or less, 0.090 / μm or less, 0.080 / μm or less, or 0.070 / μm or less. Furthermore, the range of the curvature R1 of the first corner may be determined by a combination of any one of the plurality of lower limit candidate values ​​described above and any one of the plurality of upper limit candidate values ​​described above. Specifically, the curvature R1 of the first corner is preferably 0.010 to 0.150 / μm, 0.020 to 0.125 / μm, 0.030 to 0.100 / μm, 0.040 to 0.090 / μm, or may be 0.050 to 0.080 / μm.

[0070] The curvature R2 of the second corner may be preferably 0.030 μm or more, 0.040 μm or more, 0.050 μm or more, 0.060 μm or more, 0.070 μm or more, or 0.080 μm or more. The curvature R2 of the second corner may be preferably 0.200 / μm or less, 0.180 / μm or less, 0.160 / μm or less, 0.140 / μm or less, 0.120 / μm or less, or 0.110 / μm or less. Furthermore, the range of the curvature R2 of the second corner may be determined by a combination of any one of the plurality of lower limit candidate values ​​described above and any one of the plurality of upper limit candidate values ​​described above. Specifically, the curvature R2 of the second corner is preferably 0.030 to 0.200 / μm, 0.040 to 0.180 / μm, 0.050 to 0.160 / μm, 0.060 to 0.140 / μm, 0.070 to 0.120 / μm, or may be 0.080 to 0.110 / μm.

[0071] Furthermore, the difference |R2-R1| between the curvature R1 of the first corner and the curvature R2 of the second corner may preferably be 0.005 or greater, 0.010 or greater, 0.015 or greater, 0.020 or greater, or 0.025 or greater. The difference between the curvature R1 of the first corner and the curvature R2 of the second corner may preferably be 0.100 or less, 0.080 or less, 0.060 or less, 0.050 or less, or 0.040 or less. Furthermore, the range of the difference |R2-R1| may be determined by combining any one of the multiple lower limit candidate values ​​described above with any one of the multiple upper limit candidate values ​​described above. Specifically, the difference |R2-R1| may preferably be 0.005 to 0.100, 0.010 to 0.080, or 0.015 to 0.060.

[0072] Furthermore, the ratio (R2 / R1) of the curvature R2 of the second corner to the curvature R1 of the first corner may be preferably 1.05 or greater, 1.10 or greater, 1.20 or greater, 1.25 or greater, 1.30 or greater, 1.35 or greater, or 1.40 or greater. Furthermore, the ratio (R2 / R1) of the curvature R2 of the second corner to the curvature R1 of the first corner may be preferably 2.50 or less, 2.25 or less, 2.00 or less, 1.90 or less, 1.80 or less, 1.70 or less, or 1.60 or less. Furthermore, the range of the ratio (R2 / R1) may be determined by combining any one of the plurality of lower limit candidate values ​​described above with any one of the plurality of upper limit candidate values ​​described above. Specifically, the ratio (R2 / R1) is preferably 1.05 to 2.50, 1.10 to 2.25, or may be 1.20 to 1.90.

[0073] As a result, by having the curvature R1 of the first corner, the curvature R2 of the second corner, the difference |R2-R1|, or the ratio (R2 / R1) within the above ranges, the force in the stretching direction can be more effectively dispersed, deformation of the hole shape of the through hole 25 is more suppressed, and the deposition accuracy tends to be further improved.

[0074] Furthermore, there are no particular limitations on the pitch of the through holes 25 in the effective area 22. For example, when the metal mask 20 is used to fabricate a display (approximately 0.5 inches to 32 inches) for a mobile phone, digital camera, or the like, the pitch of the through holes 25 may be approximately 20 μm to 254 μm in both the width direction D1 and the longitudinal direction D2.

[0075] The height h1 of the top portion 32, i.e., the thickness of the metal plate constituting the metal mask, is preferably 15 μm or more, 17.5 μm or more, or may be 20 μm or more. The height h1 of the top portion 32 is preferably 60 μm or less, 55 μm or less, 50 μm or less, 45 μm or less, 40 μm or less, 35 μm or less, or 20 μm or less. When the height h1 of the top portion 32 is 15 μm or more, the strength is further improved, wrinkles and the like are less likely to occur during tensioning, and deposition accuracy tends to be further improved. When the height h1 of the top portion 32 is 60 μm or less, shadows tend to be further suppressed.

[0076] Furthermore, the range of the height h1 may be determined by a combination of any one of the plurality of lower limit candidate values ​​and any one of the plurality of upper limit candidate values. Specifically, the height h1 may be 15 to 60 μm, 17.5 to 55 μm, or 20 to 50 μm.

[0077] Finally, a method for manufacturing a metal mask according to an embodiment of the present disclosure will be described.

[0078] A method for manufacturing a metal mask according to one embodiment of the present disclosure includes a preparation step of preparing a metal plate 51 having a first surface 51a and a second surface 51b located opposite the first surface 51a, and an etching step of forming the metal mask 20 by etching the metal plate 51.

[0079] In the following, a method for manufacturing the metal mask 20 by etching will be described, but the metal mask 20 may be formed by etching, by laser processing, or by electroforming.

[0080] A method for manufacturing a metal mask 20 according to an embodiment of the present disclosure will be described primarily with reference to FIGS. 3A to 3E . FIG. 3A is a schematic diagram illustrating a manufacturing apparatus 70 for manufacturing a metal mask 20 using a metal plate 51, along with the processing sequence. FIG. 3A illustrates an example in which the metal plate 51 is continuously supplied from a resist film forming apparatus 71 to a separating apparatus 75. However, the method for manufacturing a metal mask 20 according to the present disclosure is not limited to this. For example, the metal plate 51 may be wound into a wound body after each process performed by each apparatus. Furthermore, when supplying the metal plate 51 to each apparatus, the metal plate 51 may be unwound from the wound body 50.

[0081] Each step of the method for manufacturing the metal mask 20 will be described in detail below.

[0082] First, a metal plate 51 having a desired thickness is prepared (preparation step). The metal plate 51 may be in the form of a wound body 50 wound around a core 52. The method for producing the metal plate 51 having the desired thickness is not particularly limited, but examples thereof include a rolling method and a plating film formation method.

[0083] Next, resist films 53a and 53b are formed on the first surface 51a and the second surface 51b of the metal plate 51 using a resist film forming apparatus 71 (FIG. 3B). Specifically, the resist films 53a and 53b may be formed by attaching a dry film resist to the first surface 51a and the second surface 51b. Alternatively, the resist films 53a and 53b may be formed by applying a coating liquid containing a photosensitive resist material to the first surface 51a and the second surface 51b and drying the applied liquid.

[0084] The dry film resist and coating liquid are not particularly limited, and conventionally known ones can be used. The resist films 53a and 53b thus formed may be either negative resist or positive resist. Of these, negative resists are preferably used.

[0085] The thickness of the resist films 53a, 53b is preferably 15 μm or less, 10 μm or less, 6 μm or less, or may be 4 μm or less. The thickness of the resist films 53a, 53b is preferably 1 μm or more, 3 μm or more, 5 μm or more, or 7 μm or more. The thickness range of the resist films 53a, 53b may be determined by a combination of any one of the above-mentioned multiple upper limit candidate values ​​and any one of the above-mentioned multiple lower limit candidate values.

[0086] Next, the resist films 53a and 53b are exposed and developed using an exposure / development device 72. As a result, a first resist pattern 53c is formed on the first surface 51a, and a second resist pattern 53d is formed on the second surface 51b, as shown in FIG. 3C . For example, when a negative resist film is used, a photomask that blocks light from passing through the region of the resist film that is to be removed may be placed on the resist film, the resist film may be exposed through the photomask, and the resist film may then be developed.

[0087] Subsequently, the metal plate 51 is etched using the etching device 73 with the first resist pattern 53c and the second resist pattern 53d as a mask (etching step). The etching step may include a first-side etching step and a second-side etching step.

[0088] 3D is a schematic diagram illustrating an example of the first-side etching step in the effective region 22. In the first-side etching step, the region of the first surface 51a that is not covered by the first resist pattern 53c is etched using an etching solution. At this time, the second surface 51b may be covered with a resin or the like that is resistant to the etching solution.

[0089] The etching solution erodes the first surface 51a that is not covered by the first resist pattern 53c (FIG. 3D). As a result, numerous first recesses 30 are formed on the first surface 51a. Note that etching of the metal plate 51 can proceed isotropically in various directions from the holes in the resist pattern. Therefore, the cross-sectional areas of the first recesses 30 and second recesses 35 at each position along the thickness direction of the metal mask 20 gradually decrease as they progress from the surface in the thickness direction.

[0090] 3E is a schematic diagram illustrating an example of the second-side etching step in the effective region 22. In the second-side etching step, the region of the second surface 51b that is not covered by the second resist pattern 53d is etched using an etching solution. At this time, a film or the like that covered the second surface 51b in the first-side etching step may be peeled off beforehand. In addition, the first surface 51a may be covered with a resin 54 or the like that is resistant to the etching solution.

[0091] The etching solution erodes the second surface 51b that is not covered by the second resist pattern 53d (FIG. 3E). As a result, a second recess 35 is formed on the second surface 51b. The first recess 30 and the second recess 35 then communicate with each other, thereby forming a through hole 25.

[0092] The etching solution is not particularly limited as long as it is a conventionally known solution, and examples thereof include those containing ferric chloride solution and hydrochloric acid.

[0093] Furthermore, a peeling device 74 is used to peel off the resist pattern, the resin 54 that is resistant to the etching solution, and the like from the metal plate 51. Then, a separation device 75 is used to cut the long metal plate 51, thereby performing a separation step in which the metal mask 20 made of a sheet of metal plate is separated from the metal plate 51. In this manner, the metal mask 20 is obtained.

[0094] A metal mask apparatus 10 according to an embodiment of the present disclosure includes a frame 15 and the above-described metal mask 20 placed on the frame 15. The metal mask 20 may be placed on the frame 15 with the second surface 20b in contact with the frame 15. Fig. 4 shows a plan view of the metal mask apparatus 10 as viewed from the first surface 20a side of the metal mask 20. Fig. 5 shows a cross-sectional view of the vapor deposition apparatus.

[0095] In the metal mask device 10 of the present disclosure, multiple metal masks 20 may be attached to one frame ( FIG. 4 ). In this case, the multiple metal masks 20 may be aligned in a width direction D1 that intersects with the longitudinal direction D2 of the metal masks 20. Furthermore, each metal mask 20 may be fixed to the frame 15 at both ends 23 a of the metal mask 20 in the longitudinal direction D2.

[0096] The method of fixing to the frame 15 is not particularly limited, but may be, for example, welding.

[0097] The metal mask device 10 may include a member that is fixed to the frame 15 and that partially overlaps the metal mask 20 in the thickness direction of the metal mask 20. Examples of such a member are not particularly limited, but include, for example, a member that extends in a direction intersecting the longitudinal direction of the metal mask 20 and supports the metal mask 20, and a member that overlaps the gap between two adjacent metal masks.

[0098] Next, a method for manufacturing an organic EL display device using the metal mask 20 according to the present disclosure will be described with reference to Fig. 5. The organic EL display device may include a substrate 92 and a deposition layer including a deposition material 98 provided in a pattern, stacked together.

[0099] The method for manufacturing an organic EL display device according to an embodiment of the present disclosure is not particularly limited, but includes, for example, a vapor deposition step of depositing a vapor deposition material 98 on a substrate such as the substrate 92 using a metal mask 20 .

[0100] In the vapor deposition process, first, the metal mask device 10 is positioned so that the metal mask 20 faces the substrate 92. At this time, as shown in Fig. 5, the first surface 20a of the metal mask 20 may face the substrate 92. Here, the substrate 92 is a vapor deposition target such as a glass substrate.

[0101] 5, when the metal mask device 10 is housed in the vapor deposition device 90, the surface of the metal mask 20 facing the substrate 92 is the first surface 20a, and the surface of the metal mask 20 facing the crucible 94 holding the vapor deposition material 98 is the second surface 20b. In the vapor deposition device 90, the metal mask 20 is placed on the surface of the substrate 92 facing the crucible 94. Here, the metal mask 20 and the substrate 92 may be brought into close contact with each other by magnetic force.

[0102] A crucible 94 containing a deposition material 98 and a heater 96 for heating the crucible 94 may be disposed below the metal mask device 10 within the deposition device 90. Here, the deposition material 98 may be, for example, an organic light-emitting material. The deposition material 98 in the crucible 94 is vaporized or sublimated by the heat from the heater 96. The vaporized or sublimated deposition material 98 adheres to the substrate 92 through the through-holes 25 of the metal mask 20. As a result, the deposition material 98 is formed into a film on the surface of the substrate 92 in a desired pattern corresponding to the positions of the through-holes 25 of the metal mask 20. Note that the interior of the deposition device 90 may be in a vacuum atmosphere during the deposition process.

[0103] When different types of evaporation materials are to be evaporated according to pixels such as RGB, different metal masks 20 may be used depending on the type of evaporation material 98, and the evaporation materials 98 may be deposited on the surface of the substrate 92. For example, the evaporation material 98 for red, the evaporation material 98 for green, and the evaporation material 98 for blue may be evaporated in this order on the substrate 92. Alternatively, the evaporation material 98 for red, the evaporation material 98 for green, and the evaporation material 98 for blue may be evaporated in this order by gradually moving the metal mask 20 (metal mask device 10) and the substrate 92 relative to each other along the arrangement direction of the through holes 25 (the aforementioned one direction).

[0104] The method for manufacturing an organic EL display device may include various processes other than the vapor deposition process of depositing a vapor deposition material 98 on a substrate such as the substrate 92 using the metal mask 20. For example, the method for manufacturing an organic EL display device may include a process of forming a first electrode on the substrate. A vapor deposition layer is formed on the first electrode. The method for manufacturing an organic EL display device may also include a process of forming a second electrode on the vapor deposition layer. The method for manufacturing an organic EL display device may also include a sealing process of sealing the first electrode, the vapor deposition layer, and the second electrode provided on the substrate 92.

[0105] The vapor deposition layer formed on a substrate such as the substrate 92 using the metal mask 20 is not limited to the light-emitting layer formed by vapor deposition of the organic light-emitting material described above, and may include other layers. For example, the vapor deposition layer may include, in order from the first electrode side, a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, an electron injection layer, etc. In this case, a vapor deposition process using a metal mask 20 corresponding to each layer may be performed.

[0106] The present disclosure will be described in more detail below using examples and comparative examples, but the present disclosure is not limited to the following examples.

[0107] Example 1: Using the above-described metal mask manufacturing method, a metal mask was manufactured having through holes formed of first and second recesses in a metal plate. As shown in FIGS. 2A to 2C, the opening shape of the second recesses 35 was rectangular, and the opening shape of the first recesses 30 was circular. The through holes 25 were arranged in a staggered pattern along the longitudinal direction D2 and the width direction D1, with the diagonals L2 and L1 of the rectangular shape of the second recesses 35 extending substantially parallel to the longitudinal direction D2 and the width direction D1, respectively. Furthermore, a top portion 32 remained unetched between adjacent second recesses 35. The metal plate used as the raw material for the metal mask was an Invar material with a thickness of 20 μm.

[0108] Examples 2 to 8 Metal masks of Examples 2 to 8 were obtained in the same manner as in Example 1, except that the curvature of the rectangular shape of the opening was changed by changing the resist pattern used.

[0109] Comparative Example 1 A metal mask of Comparative Example 1 was obtained in the same manner as in Example 1, except that the opening shape of the second recess 35 was formed to be circular.

[0110] Comparative Example 2 A metal mask of Comparative Example 2 was obtained in the same manner as in Comparative Example 1, except that the size of the circular opening was changed.

[0111] Comparative Example 3 The metal mask of Comparative Example 3 was obtained in the same manner as in Example, except that the etching was further advanced so that the second wall surfaces 36 of adjacent second recesses 35 merged together, thereby preventing any top portions 32 remaining unetched between adjacent second recesses 35.

[0112] Comparative Example 4 A metal mask of Comparative Example 4 was obtained in the same manner as in Example, except that the through holes 25 were arranged in a lattice pattern along the longitudinal direction D2 and the width direction D1 instead of in a staggered pattern.

[0113] (Evaluation of Strength) The strength was evaluated using the metal masks produced in the Examples and Comparative Examples as described above. Specifically, when the metal mask was placed on the frame, visual observation was made to see whether defects such as wavy shapes occurred. Based on the observation results, the strength was evaluated according to the following evaluation criteria. (Evaluation criteria) A: No wavy shapes occurred B: Fine wavy shapes occurred, but within the acceptable range C: Wavy shapes occurred D: Large wavy shapes occurred

[0114] (Evaluation of Shadows) Using the metal masks prepared in the Examples and Comparative Examples as described above, a vapor deposition process was carried out in which a vapor deposition material was attached to a substrate to form a vapor deposition layer. Tris(8-quinolinolato)aluminum, an organic light-emitting material, was used as the vapor deposition material. A glass substrate was used as the substrate. The conditions for the vapor deposition process were set so that the thickness of the vapor deposition layer would be 40 nm.

[0115] Next, the deposition layer on the substrate was observed using a LEICA DMRX HX DC300F optical microscope and a Hitachi High-Technologies Birdscan scanning white light interference microscope. Based on the observation results, the area ratio V of the deposition layer was calculated. The area ratio V of the deposition layer is the ratio (V2 / V1) of the effective area V2 of the deposition layer to the area V1 of the through holes.

[0116] The effective area V2 is the area of ​​the region of the deposited layer having a thickness of 95% or more of the target thickness. If the target thickness is 40 nm, the effective area V2 is the area of ​​the region of the deposited layer having a thickness of 38 nm or more.

[0117] The area ratio V was calculated for each of the 30 vapor-deposited layers on the substrate. Based on the results, the evaluation criteria were as follows: (Evaluation criteria) A: The area ratio V for all of the 30 vapor-deposited layers on the substrate was 0.70 or more. D: The area ratio V for even one of the 30 vapor-deposited layers on the substrate was less than 0.70.

[0118] (Evaluation 1 of hole shape before stretching) For each metal mask obtained as described above, the number of through holes whose circular shape had become distorted due to excessive etching or the like was counted for the shape of the connection portion of 100 randomly selected through holes. Based on the results, the deformation of the hole shape before stretching was evaluated according to the following evaluation criteria. (Evaluation criteria) A: 1 or less through hole whose circular shape was distorted B: 2 to 5 through holes whose circular shape was distorted C: 6 to 10 through holes whose circular shape was distorted D: 11 or more through holes whose circular shape was distorted

[0119] (Evaluation 2 of hole shape during stretching) The metal masks produced in the examples and comparative examples as described above were tensioned in the longitudinal direction and placed on a frame. In this state, the number of through holes whose connection parts were distorted from a circular shape was counted for 100 randomly selected through holes. Based on the results, the deformation of the hole shape before stretching was evaluated according to the following evaluation criteria. (Evaluation criteria) A: 1 or less through hole whose circle was distorted B: 2 to 5 through holes whose circle was distorted C: 6 to 10 through holes whose circle was distorted D: 11 or more through holes whose circle was distorted

[0120] The results are shown in Figure 6. Note that because the rectangular shape of the opening of the second recess has rounded corners, the value obtained by simply multiplying the long side or short side by √2 does not equal a value. Examples 1 and 2 and Comparative Example 3 are examples in which the rectangular shape of the opening of the second recess is square, while Examples 3 to 8 and Comparative Example 4 are examples in which the rectangular shape of the opening of the second recess is rectangular.

[0121] The metal mask of the present disclosure has industrial applicability, for example, as a metal mask used in the manufacture of organic EL display devices.

[0122] DESCRIPTION OF SYMBOLS 10...metal mask device, 15...frame, 20...metal mask, 20a...first surface, 20b...second surface, 22...effective area, 23...peripheral area, 23a...end, 25...through hole, 30...first recess, 31...first wall surface, 32...top portion, 35...second recess, 36...second wall surface, 41...connection portion, 50...wound body, 51...metal plate, 51a...first surface, 51b...second surface, 52...core, 53a...resist film, 53b...resist film, 53c...first resist pattern, 53d...second resist pattern, 54...resin, 70...manufacturing apparatus, 71...resist film forming apparatus, 72...exposure / developing apparatus, 73...etching apparatus, 74...peeling apparatus, 75...separating apparatus, 90...evaporation apparatus, 92...substrate, 94...crucible, 96...heater, 98...evaporation material

Claims

1. A metal mask having an effective area and a peripheral area, wherein the effective area is provided with a plurality of through holes, wherein the plurality of through holes are connected to first recesses on a first surface side and second recesses on a second surface side, wherein the opening area of ​​the first recesses is smaller than the opening area of ​​the second recesses, wherein the opening shape of the second recesses is rectangular, wherein the shape of the connection between the first recesses and the second recesses is circular or nearly circular, wherein the plurality of through holes are arranged in a staggered pattern in the effective area, and wherein adjacent second recesses are separated by top portions.

2. The metal mask according to claim 1, wherein the opening shape of the first recess is circular or approximately circular.

3. The metal mask according to claim 1, wherein one of the diagonals of the opening shape of the second recess is approximately parallel to the longitudinal direction of the metal mask or a width direction perpendicular to the longitudinal direction.

4. The metal mask according to claim 1, wherein the longest diagonal of the diagonal of the opening shape of the second recess is approximately parallel to the longitudinal direction of the metal mask.

5. The metal mask according to claim 1, wherein the curvature of the corners of the opening shape of the second recess is 0.010 to 0.150 / μm.

6. The metal mask according to claim 1, wherein the curvature of the second corner is smaller than the curvature of the first corner, the first corner is a corner of the opening shape of the second recess that is aligned in a direction approximately perpendicular to the extension direction, and the second corner is a corner of the opening shape of the second recess that is aligned in the extension direction.

7. The metal mask according to claim 1, wherein the circularity of the connection portion is 0 to 5 μm.

8. The metal mask according to claim 1, wherein the minimum width W of the top portion separating adjacent second recesses is 0.1 to 20 μm.

9. The metal mask according to claim 1, wherein the top portions of the four second recesses arranged in a staggered pattern, which form the sides of the rectangular shape, meet at one intersection.

10. A method for manufacturing a metal mask, comprising: a step of preparing a metal plate; and an etching step of forming the metal mask by etching the metal plate, wherein the metal mask has an effective area and a peripheral area, the effective area has a plurality of through holes, the plurality of through holes are connected to first recesses on a first surface side and second recesses on a second surface side, the opening area of ​​the first recesses is smaller than the opening area of ​​the second recesses, the opening shape of the second recesses is quadrangular, the shape of the connection between the first recesses and the second recesses is circular or approximately circular, the plurality of through holes are arranged in a staggered pattern in the effective area, and adjacent second recesses are separated by top portions.

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