Metal mask and method for producing same

Abstract

This metal mask comprises an effective region and a peripheral region. The effective region is provided with a plurality of through-holes and a plurality of ridges. The ridges are boundaries formed by merging wall surfaces of mutually adjacent through-holes. The plurality of through-holes have a through-hole row lined up on a straight line L. In the ridges positioned so as to partition mutually adjacent through-holes in the through-hole row, three or more adjacent valley parts are positioned so as to not line up on the straight line L, where the valley parts are portions where the height of the ridges is lowest.

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 thinnest parts of the ridges that define adjacent through holes tend to be regularly aligned in a specific direction, resulting in a structure prone to stress concentration in those areas. The presence of such areas prone to stress concentration can easily result in wavy shapes during stretching, resulting in problems such as reduced deposition accuracy.

[0006] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a metal mask that is less likely to develop wavy shapes when stretched, 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 comprising a plurality of through holes and a plurality of ridge lines, the ridge lines being boundaries formed where the wall surfaces of adjacent through holes meet, the plurality of through holes comprising a row of through holes aligned on a straight line L, and when the portion of the ridge line positioned to separate adjacent through holes in the row of through holes where the height of the ridge line is the smallest is defined as a valley, three or more adjacent valleys are positioned so as not to be aligned on the straight line L.

[0008] A method for manufacturing a metal mask according to one embodiment of the present disclosure comprises: 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, wherein the effective area comprises a plurality of through holes and a plurality of ridge lines, wherein the ridge lines are boundaries formed by the joining of wall surfaces of adjacent through holes, and wherein the plurality of through holes comprise a row of through holes aligned on a straight line L, and when the portion of the ridge line positioned to separate adjacent through holes in the row of through holes where the height of the ridge line is the smallest is defined as a valley, three or more adjacent valleys are positioned so as not to be aligned on the straight line L.

[0009] At least one embodiment of the present disclosure aims to provide a metal mask that is less likely to develop wavy shapes when stretched, and a method for manufacturing the same.

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

[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 surrounding area, wherein the effective area comprises a plurality of through holes and a plurality of ridge lines, wherein the ridge lines are boundaries formed where wall surfaces of adjacent through holes meet, and wherein the plurality of through holes comprise a row of through holes aligned on a straight line L, and when the portion of the ridge line positioned to separate adjacent through holes in the row of through holes where the height of the ridge line is the smallest is defined as a valley, three or more adjacent valleys are positioned so as not to be aligned on the straight line L.

[0025] A second aspect of the present disclosure is the metal mask according to the first aspect, wherein a straight line M connecting the adjacent valley portions may intersect with the straight line L.

[0026] A third aspect of the present disclosure is the metal mask of the first or second aspect, wherein three adjacent valley portions do not have to be aligned in a straight line.

[0027] A fourth aspect of the present disclosure is a metal mask according to any one of the first to third aspects described above, wherein the ridge line has top portions at both ends where the height is a maximum value, and the valley portions do not have to be located at the centers of the top portions at both ends.

[0028] A fifth 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 comprises a plurality of through holes and a plurality of ridge lines, the ridge lines are boundaries formed where wall surfaces of adjacent through holes meet, the plurality of through holes comprise a row of through holes aligned on a straight line L, and when the portion of the ridge line positioned so as to separate adjacent through holes in the row of through holes where the height of the ridge line is the smallest is defined as a valley, three or more adjacent valleys are positioned so as not to be aligned on the straight line L.

[0029] The metal mask 20 of the present disclosure will be described in detail below.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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. 6 ). 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.

[0035] 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.

[0036] Next, we will explain 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 its front and back surfaces.

[0037] 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 2C to 2E, 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. Note that, as shown in Figure 2B, etc., if the second wall surfaces 36 of the second recesses 35 of adjacent through holes 25 meet on the second surface 20b, the area enclosed by the ridge line 32 surrounding one through hole 25 may be considered the opening of the through hole 25. In this case, the area enclosed by the ridge line 32 is the opening area.

[0038] 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. 6 ). 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. 6 ).

[0039] 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.

[0040] 2A and 2B are a top view and a perspective view showing one embodiment of the effective area when viewed from the second surface 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.

[0041] 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 rectangular 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.

[0042] 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.

[0043] 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 2E. Figure 2C is a cross-sectional view taken along line II' in Figure 2A. Figure 2D is a cross-sectional view taken along line II-II' in Figure 2A. Figure 2E is a cross-sectional view taken along line III-III' in Figure 2A.

[0044] In the present disclosure, as shown in FIGS. 2A and 2B, the effective area 22 may include a plurality of through holes 25 and a plurality of ridges 32 at least on the second surface 20b.

[0045] 2A to 2E, 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.

[0046] The 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 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. The first recess 30 may be configured as a recess with a smaller diameter than the second recess 35.

[0047] At the connection portion 41, the direction in which the wall surface of the through-hole 25 expands changes discontinuously. Generally, at the connection portion 41, the opening area of ​​the through-hole 25 in plan view becomes smallest.

[0048] 2A , the through hole 25 has a connection portion 41 that is approximately square in plan view. The connection 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. Note that although the connection portion 41 of the through hole 25 is shown as a rectangle that is approximately close to a square in FIG. 2A , the shape is not limited thereto, and the through hole 25 may be a polygon such as a triangle, pentagon, hexagon, or octagon, or may be a circular shape such as a circle or an ellipse.

[0049] The through holes 25 may be formed in any desired pattern other than the pattern exemplified in FIG. 2A . For example, the through holes 25 may be arranged in a grid pattern at a predetermined pitch along two intersecting directions. The through holes 25 may also be arranged in a staggered pattern at a predetermined pitch along two intersecting directions, or in any other pattern. In any pattern, the through holes 25 are arranged in any regular pattern in accordance with the patterns of the vapor deposition layers of each color, such as red (R), green (G), and blue (B), and therefore can be said to have a row of through holes aligned on any straight line L. Note that the two directions may or may not coincide with the longitudinal direction D2 or width direction D1 of the metal mask 20.

[0050] 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.

[0051] 2B , the ridge line 32 is a boundary formed by the joining of the second wall surfaces 36 of the second recesses 35 of adjacent through holes 25. The height of this ridge line 32 is not constant, and may vary in an undulating manner. The height of the ridge line 32 can also be said to be the position of the ridge line 32 in the thickness direction of the metal mask 20. As a general trend, the height of the ridge line 32 changes depending on the distance from the center of the through hole 25, becoming higher as the distance increases and becoming lower as the distance decreases.

[0052] As shown in FIG. 2B , in the present disclosure, a portion of the ridgeline 32 where the height is a local minimum is referred to as a valley portion 33 , and a portion where the height is a local maximum is referred to as a top portion 34 .

[0053] In conventional metal masks, in ridge lines 32 positioned to separate adjacent through holes 25 in a row of through holes, valleys 33 where the height of ridge lines 32 is minimum are aligned on a straight line L. The valleys are the thinnest parts of the effective area 22 and have low mechanical strength. When such valleys are aligned on a straight line L, stress tends to concentrate on the straight line L, which tends to produce wavy shapes during tensioning and reduces vapor deposition accuracy.

[0054] In contrast, the metal mask of the present disclosure is configured so that three or more adjacent valleys are not aligned on a straight line L, as in valleys 33a to 33e where the height of the ridgeline is smallest, as shown in FIGS. 2A and 2B . In the present disclosure, "valleys aligned on a straight line L" means that three or more adjacent valleys are located on the straight line L. Furthermore, the straight line L indicates the direction in which the through holes 25 are aligned in the through hole row. Therefore, "valleys aligned on a straight line L" also includes, for example, a case in which the valleys are aligned on a straight line parallel to the straight line L, such as valleys 33a and 33b. However, valleys 33a and 33b do not have a relationship in which three or more adjacent valleys are positioned on the straight line L, and therefore do not fall under the category of "valleys aligned on a straight line L."

[0055] In the present disclosure, the "straight line L" refers to the direction in which the through-hole row extends, as shown in Figures 2A and 2B. The straight line L may be a line connecting the centers of gravity of the opening areas of the through-holes constituting the through-hole row. Figure 2B shows an example in which the straight line L is drawn substantially parallel to the longitudinal direction D2, but the straight line L may also be drawn substantially parallel to the width direction D1. In this way, when the straight line L can be drawn in multiple directions, the direction in which the through-hole row extends in which the distance between the through-holes is shortest may be taken as the straight line L.

[0056] Although there are no particular limitations on the mode in which the valleys 33a to 33e are not aligned on the straight line L, for example, a mode in which the straight line M connecting two adjacent valleys 33, such as valleys 33b and 33c, intersects with the straight line L. In such a mode, it can be said that at least three or more adjacent valleys are not positioned on the straight line L.

[0057] The intersection angle θ between the straight lines M and L is preferably 8.0° or more, 10.0° or more, 12.0° or more, 13.0° or more, 14.0° or more, or 15.0° or more. The intersection angle θ between the straight lines M and L is not particularly limited, and may be, for example, 30.0° or less, 27.5° or less, 25.0° or less, 22.5° or less, 20.0° or less, or 17.5° or less. When the intersection angle θ is 8.0° or more, wavy shapes are less likely to occur during tensioning, and deposition accuracy tends to be further improved.

[0058] Furthermore, the range of the intersection angle θ 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 intersection angle θ may be 8.0 to 30.0°, 10.0 to 27.5°, 12.0 to 25.0°, 13.0 to 22.5°, 14.0 to 20.0°, or 15.0 to 17.5°.

[0059] The intersection angle θ can be calculated as the average value of an arbitrarily selected straight line M.

[0060] The average distance d of the valleys 33 from the straight line L is preferably 3.0 μm or more, 4.5 μm or more, 6.0 μm or more, or 7.5 μm or more. The average distance d of the valleys 33 from the straight line L is not particularly limited, and may be, for example, 30 μm or less, 25 μm or less, 20 μm or less, or 15 μm or less. When the average distance d is 3.0 μm or more, wavy shapes are less likely to occur during stretching, and deposition accuracy tends to be further improved.

[0061] Furthermore, the range of the average distance d may be determined by a combination of any one of the plurality of candidate values ​​for the lower limit and any one of the plurality of candidate values ​​for the upper limit. Specifically, the average distance d may be 3.0 to 30 μm, 4.5 to 25 μm, 6.0 to 20 μm, or 7.5 to 15 μm.

[0062] The average distance d can be calculated as the average value of the distances from the straight line L to arbitrarily selected valleys 33 .

[0063] Furthermore, it is preferable that three adjacent valleys 33 are not aligned in a straight line, as in the valleys 33b to 33d. In other words, it is preferable that the valleys 33 are positioned in a zigzag pattern so as to straddle the straight line L. This tends to make it less likely that stress will concentrate on a specific straight line.

[0064] Alternatively, the ridge line 32, which is positioned to separate adjacent through holes 25 in the through hole row, may have top portions 34 at both ends where the height is at a maximum, and the valley portion 33 may not be located at the center of the top portions at both ends. In other words, the valley portion 33b may be located biased toward one of the top portions 34a, 34b. This tends to make local stress concentration less likely to occur. Here, the top portion 34 is the portion of the ridge line 32 formed by the merging of adjacent second recesses 35 where the height is at a maximum.

[0065] The distance t between the top portions 34 located at both ends of the ridge line 32 is preferably 40 μm or more, 45 μm or more, or may be 50 μm or more. The distance t between the top portions 34 located at both ends of the ridge line 32 is preferably 100 μm or less, 390 μm or less, or may be 80 μm or less.

[0066] Furthermore, the range of the distance t 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 distance t may be 40 to 100 μm, 45 to 90 μm, or 50 to 80 μm.

[0067] The ratio (average distance d / distance t) of the average distance d of the valleys 33 from the straight line L to the distance t of the top portions 34 located at both ends of the ridge line 32 is defined as the deviation of the valleys 33 from the centers of the top portions 34 located at both ends of the ridge line 32. In this case, the ratio (average distance d / distance t) is preferably 0.025 or more, 0.050 or more, 0.075 or more, or even 0.100 or more. The ratio (average distance d / distance t) is not particularly limited, and may be, for example, 0.300 or less, 0.250 or less, 0.225 or less, or 0.200 or less. When the ratio (average distance d / distance t) is 0.025 or more, wavy shapes and the like are less likely to occur during stretching, and deposition accuracy tends to be further improved.

[0068] Furthermore, the range of the ratio (average distance d / distance t) 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 ratio (average distance d / distance t) may be 0.025 to 0.300, 0.050 to 0.250, 0.075 to 0.225, or 0.100 to 0.200.

[0069] The height h1 of the valleys 33 is preferably 5.0 μm or more, 6.0 μm or more, 7.0 μm or more, or may be 8.0 μm or more. The height h1 of the valleys 33 is preferably 20 μm or less, 17.5 μm or less, 15 μm or less, or 12.5 μm or less. When the height h1 of the valleys 33 is 5 μm or more, wavy shapes are less likely to occur during stretching, and deposition accuracy tends to be further improved. When the height h1 of the valleys 33 is 20 μm or less, shadows tend to be further suppressed.

[0070] 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 5.0 to 20 μm, 6.0 to 17.5 μm, 7.0 to 15 μm, or 8.0 to 12.5 μm.

[0071] Furthermore, the height h2 of the top portion 34 is preferably 15 μm or more, 17.5 μm or more, 20 μm or more, or may be 22.5 μm or more. The height h2 of the top portion 34 is preferably 35 μm or less, 32.5 μm or less, 30 μm or less, or 27.5 μm or less. When the height h2 of the top portion 34 is 15 μm or more, wavy shapes and the like are less likely to occur during stretching, and deposition accuracy tends to be further improved. When the height h2 of the top portion 34 is 35 μm or less, shadows tend to be further suppressed.

[0072] Furthermore, the range of the height h2 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 h2 may be 15 to 35 μm, 17.5 to 32.5 μm, 20 to 30 μm, or 22.5 to 27.5 μm.

[0073] Furthermore, the ratio (h1 / h2) of the height h1 of the valley portion 33 to the height h2 of the top portion 34 is preferably 0.20 or more, 0.25 or more, 0.30 or more, or even 0.35 or more. The ratio (h1 / h2) is preferably 0.80 or less, 0.75 or less, 0.70 or less, or 0.65 or less. When the ratio (h1 / h2) is 0.20 or more, wavy shapes and the like are less likely to occur during stretching, and deposition accuracy tends to be further improved. When the ratio (h1 / h2) is 0.80 or less, shadows tend to be further suppressed.

[0074] Furthermore, the range of the ratio (h1 / h2) 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 ratio (h1 / h2) may be 0.20 to 0.80, 0.25 to 0.75, 0.30 to 0.70, or 0.35 to 0.65.

[0075] As described above, in the present disclosure, the valley portion 33, which is the thinnest part of the effective area 22, is not aligned on the straight line L, thereby suppressing stress concentration on the straight line L, making it less likely that wavy shapes will occur during tensioning, and thus improving deposition accuracy.

[0076] The formation of such through holes 25 may be adjusted by the etching conditions when forming the first recess 30 and the second recess 35 and the shape of the photoresist mask used.

[0077] 2A to 2E, the top portion 34 is shown as the portion of the ridge 32 formed by the merging of adjacent second recesses 35 where the height is greatest. Alternatively, the top portion 34 may be a portion that remains unetched and has the second surface 20b at its top. Such a top portion that remains unetched is also referred to as a "rib bar."

[0078] Fig. 3A is a top view showing the effective area 22 as viewed from the second surface 20b when the top portion 34 is a rib bar. Fig. 3B is a perspective view showing the effective area 22 as viewed from the second surface 20b when the top portion 34 is a rib bar.

[0079] 3A and 3B is the same as the embodiment shown in Figures 2A and 2B except that the top portion 34 is a rib rod. Even in this case, the metal mask of the present disclosure is configured so that the valleys 33a to 33e, where the height of the ridge line is smallest, do not line up on the straight line L, as shown in Figures 3A and 3B. As a result, in the present disclosure, the valleys 33, which are the thinnest parts of the effective area 22, do not line up on the straight line L, which suppresses stress concentration on the straight line L and makes it less likely that a wavy shape will occur during tensioning, thereby further improving vapor deposition accuracy.

[0080] Finally, a method for manufacturing a metal mask according to an embodiment of the present disclosure will be described.

[0081] 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.

[0082] 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.

[0083] A method for manufacturing a metal mask 20 according to an embodiment of the present disclosure will be described primarily with reference to FIGS. 4A to 4E . FIG. 4A 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. 4A 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.

[0084] Each step of the method for manufacturing the metal mask 20 will be described in detail below.

[0085] 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.

[0086] 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. 4B). 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.

[0087] 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.

[0088] 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.

[0089] 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. 4C . 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.

[0090] 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.

[0091] 4D 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.

[0092] The etching solution erodes the first surface 51a that is not covered by the first resist pattern 53c (FIG. 4D). 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.

[0093] 4E 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.

[0094] The etching solution erodes the second surface 51b that is not covered by the second resist pattern 53d (FIG. 4E). 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.

[0095] 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.

[0096] In the second surface etching step, etching may be continued until adjacent second recesses 35 are connected, as shown in FIG. 4E . At the points where adjacent second recesses 35 are connected, the adjacent second recesses 35 join together to form ridge lines 32. Furthermore, ridge lines 32 are separated from second resist pattern 53d, and etching erosion at the tops of ridge lines 32 also progresses in the thickness direction of metal plate 51. This causes second resist pattern 53d to peel off from metal plate 51. Note that portions of second surface 51b may remain between adjacent second recesses 35.

[0097] 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.

[0098] 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. 5 shows a plan view of the metal mask apparatus 10 as viewed from the first surface 20a side of the metal mask 20. Fig. 6 shows a cross-sectional view of the vapor deposition apparatus.

[0099] In the metal mask device 10 of the present disclosure, multiple metal masks 20 may be attached to one frame ( FIG. 5 ). 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.

[0100] The method of fixing to the frame 15 is not particularly limited, but may be, for example, welding.

[0101] 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.

[0102] 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. 6. 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.

[0103] 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 .

[0104] 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. 6, 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.

[0105] 6, 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.

[0106] 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.

[0107] 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).

[0108] 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.

[0109] 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.

[0110] 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.

[0111] (Example) Using the above-described method for manufacturing a metal mask, a metal mask was manufactured having through holes each consisting of a first recess and a second recess in a metal plate. In this case, as shown in the positional relationship of valleys 33b to 33d in FIG. 2B , at the ridge line formed by the merging of the wall surfaces of adjacent through holes, the valleys were not aligned on the straight line L of the through hole row, but were aligned in a zigzag pattern across the straight line L. The metal plate used as the raw material for the metal mask was an invar material. In all of the metal masks in the example, three or more adjacent valleys were positioned so that they were not aligned on the straight line L.

[0112] Comparative Example A metal mask was obtained in the same manner as in the example, except that the valleys were configured to align on the straight line L of the through hole row. Note that in all of the metal masks of the comparative examples, three or more adjacent valleys were positioned to align on the straight line L. Note that in Table 1, there are examples in which the intersection angle θ and the average distance d in the metal masks of the comparative examples are not 0. This is because, although all of the valleys were designed to align on the straight line L, some of the four or more adjacent valleys were not positioned on the straight line L due to manufacturing variations.

[0113] (Evaluation of Shape) As shown in FIGS. 2A and 2B , for each metal mask obtained as described above, the intersection angle θ between the line M and the line L, the average distance d of the valley portion 33 from the line L, the distance t between the top portions 34 located at both ends of the ridge line 32, the ratio indicating the amount of deviation of the valley portion 33 from the center of the top portion 34 (average distance d / distance t), the height h1 of the valley portion 33, the height h2 of the top portion 34, and the ratio thereof (h1 / h2) were evaluated.

[0114] (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

[0115]

[0116] 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.

[0117] 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...ridge line, 33, 33a, 33b, 33c, 33d, 33e, 33f...valley portion, 34, 34a, 34b...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 comprises a plurality of through holes and a plurality of ridge lines, wherein the ridge lines are boundaries formed where wall surfaces of adjacent through holes meet, wherein the plurality of through holes comprise a row of through holes aligned on a straight line L, and wherein when the portion of the ridge line that separates adjacent through holes in the row of through holes where the height of the ridge line is the smallest is defined as a valley, three or more adjacent valleys are positioned so as not to be aligned on the straight line L.

2. The metal mask according to claim 1, wherein a straight line M connecting adjacent valley portions intersects with the straight line L.

3. The metal mask according to claim 1, wherein three adjacent valleys are not aligned in a straight line.

4. The metal mask according to claim 1, wherein the ridge lines have top portions at both ends where the height is a maximum value, and the valley portions are not located at the centers of the top portions at both ends.

5. 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, wherein the effective area has a plurality of through holes and a plurality of ridge lines, wherein the ridge lines are portions where wall surfaces of adjacent through holes intersect, wherein the plurality of through holes form a row of through holes aligned on a straight line L, and wherein, in the ridge lines positioned so as to separate adjacent through holes in the row of through holes, valley portions where the height of the ridge line is minimum do not line up on the straight line L.

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