DEPOSITION MASK, METHOD FOR MANUFACTURING DEPOSITION MASK, AND METHOD FOR MANUFACTURING DISPLAY DEVICE

Abstract

To suppress extension of a distance between a mask plate and a vapor deposition object.SOLUTION: A vapor deposition mask includes a mask frame and a mask plate 21. The mask plate 21 includes: a mask region in which a plurality of mask holes is positioned; and a peripheral region surrounding the mask region. The peripheral region includes a welding mark. A plane including a flat part of a second surface of the mask plate 21 is a reference plane RP at a cross section orthogonal to the second surface. The welding mark includes: a first recess 21 WR1 recessing relative to the reference plane RP; a second recess 21 WR2 recessing more than a bottom part of the first recess 21 WR1; and a first protrusion 21 WP1 protruding from the reference plane RP in an edge of the first recess 21 WR1. A maximum value MX1 in a distance between the reference plane RP and the first protrusion 21 WP1 is 1.0 μm or less.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a deposition mask, a method for manufacturing a deposition mask, and a method for manufacturing a display device. [Background technology]

[0002] In the manufacture of an organic EL display device, vacuum deposition is used to form an organic light-emitting layer included in an organic EL display element. When forming an organic light-emitting layer by vacuum deposition, a deposition mask is used to form an organic light-emitting layer having a predetermined shape at a predetermined position on a deposition target. The deposition mask includes a plurality of mask plates and a mask frame. Each mask plate is a metal foil having a plurality of mask holes formed therein. The plurality of mask holes have a shape and arrangement corresponding to the shape and arrangement of the organic light-emitting layer. The mask frame has a frame hole for allowing a deposition material to reach a mask portion attached to the mask frame. Each mask plate is welded to the mask frame so as to close a different frame hole from the others (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2019 / 054462 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, when welding the mask plate to the mask frame, a laser beam is irradiated toward one of a pair of surfaces of the mask plate opposite to the surface that contacts the mask frame. When the laser beam is irradiated onto the mask plate, a portion to which the energy of the laser beam is applied is depressed, and a protuberance is formed by raising the area around the depression. Since the surface of the mask plate opposite to the surface that contacts the mask frame faces the deposition target, the location of the protuberance on that surface may cause the mask plate and the deposition target to be spaced apart to such an extent that the accuracy of the pattern formed on the deposition target is reduced. [Means for solving the problem]

[0005] The deposition mask for solving the above problem includes a mask frame having a frame shape that defines a frame hole, and a mask plate having a first surface, a second surface, and a plurality of mask holes penetrating between the first surface and the second surface, the mask plate including a mask region in which the plurality of mask holes are located and a peripheral region surrounding the mask region, the mask plate being welded to the mask frame in the peripheral region so as to cover the frame hole with the first surface in contact with the mask frame. The peripheral region includes a welding mark. In a cross section perpendicular to the second surface, a plane including a flat portion of the second surface is a reference surface. The welding mark includes a first recess that is recessed with respect to the reference surface, a second recess that is further recessed from a bottom of the first recess, and a protuberance that protrudes from the reference surface at an edge of the first recess. The maximum value of the distance between the reference surface and the protuberance is 1.0 μm or less.

[0006] A method for manufacturing a deposition mask for solving the above problem includes forming a mask plate having a mask region where the mask holes are located and a peripheral region including the mask region by forming a plurality of mask holes penetrating between a first surface and a second surface in a metal plate having the first surface and the second surface, forming a mask frame having a frame shape that defines a frame hole, and welding the peripheral region to the mask frame by laser welding so as to cover the frame hole while the mask plate is in close contact with the mask frame. The welding includes forming a welding mark on the mask plate. In a cross section perpendicular to the second surface, a plane including a flat portion of the second surface is a reference surface. The welding mark includes a first recess that is recessed with respect to the reference surface, a second recess that is further recessed from a bottom of the first recess, and a protuberance that protrudes from the reference surface at an edge of the first recess. The maximum value of the distance between the reference surface and the protuberance is 1.0 μm or less.

[0007] A manufacturing method of a display device for solving the above problem includes forming a pattern on a deposition target by using a deposition mask manufactured by the above deposition mask manufacturing method. According to the deposition mask, the method for manufacturing the deposition mask, and the method for manufacturing the display device, the height of the first raised portion protruding from the flat portion of the deposition mask is 1.0 μm or less. Therefore, when the deposition target has a bank, the distance between the mask plate and the deposition target surface is not expanded by the first raised portion both when the deposition mask is in contact with the deposition target and when it is close to the deposition target. Therefore, the accuracy of the deposition pattern is prevented from decreasing. Alternatively, even when the deposition target does not have a bank, if the height of the first raised portion is 1.0 μm or less, the distance between the mask plate and the deposition target surface is sufficiently small, so that the accuracy of the deposition pattern is prevented from decreasing.

[0008] In the deposition mask, the raised portion may be a first raised portion, the welding mark may further include a second raised portion raised from the bottom of the first recess at an edge of the second recess, and a maximum distance between the bottom of the first recess and the first raised portion may be greater than or equal to a maximum distance between the bottom of the first recess and the second raised portion.

[0009] According to the deposition mask, since the second raised portion does not protrude beyond the first raised portion, the second raised portion is prevented from increasing the distance between the mask plate and the deposition surface of the deposition target, and therefore, the accuracy of the deposition pattern formed using the deposition mask is prevented from decreasing.

[0010] In the deposition mask, the mask plate may have a thickness of 10 μm or less. With this deposition mask, it is not possible to form a recess for forming a welding mark, and therefore it is possible to more significantly obtain the effect of the welding mark having a structure including a first recess, a second recess, and a first protrusion.

[0011] In the above-mentioned deposition mask manufacturing method, the mask frame may include a first magnetic portion having ferromagnetic properties, and the mask plate may include a second magnetic portion having ferromagnetic properties, and the welding may include welding the mask plate to the mask frame in a state in which the second magnetic portion is closely attached to the first magnetic portion by magnetic force.

[0012] According to the above-mentioned method for manufacturing a deposition mask, the mask plate can be closely attached to the mask frame by magnetic force, so that the mask plate can be closely attached to the mask frame with a higher degree of adhesion than when a load is applied to the laminate of the mask plate and the mask frame. Effect of the Invention

[0013] According to the present invention, it is possible to suppress an increase in the distance between the mask plate and the deposition target. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a plan view showing a structure of a mask device including a deposition mask according to an embodiment. [Diagram 2] 2 is a cross-sectional view showing a structure of a deposition mask included in the mask device shown in FIG. [Diagram 3] 2 is a cross-sectional view showing the structure of a mask plate included in the mask device shown in FIG. 1. [Figure 4] FIG. 4 is a plan view showing the structure of the welding trace as viewed from a viewpoint opposite to the second surface. [Diagram 5] FIG. 4 is an end view showing the structure of a welding mark along a plane perpendicular to the second surface. [Figure 6] 1A to 1C are process diagrams illustrating a method for manufacturing a deposition mask according to an embodiment. [Figure 7] 1A to 1C are process diagrams illustrating a method for manufacturing a deposition mask according to an embodiment. [Figure 8] 1A to 1C are process diagrams illustrating a method for manufacturing a deposition mask according to an embodiment. [Figure 9] 1A to 1C are process diagrams illustrating a method for manufacturing a deposition mask according to an embodiment. [Figure 10] 1A to 1C are process diagrams illustrating a method for manufacturing a deposition mask according to an embodiment. [Figure 11] 1A to 1C are process diagrams illustrating a method for manufacturing a deposition mask according to an embodiment. [Figure 12] 1A to 1C are process diagrams illustrating a method for manufacturing a deposition mask according to an embodiment. [Figure 13] 1A to 1C are process diagrams illustrating a method for manufacturing a deposition mask according to an embodiment. [Figure 14] 1A to 1C are process diagrams illustrating a method for manufacturing a deposition mask according to an embodiment. [Figure 15] 1A to 1C are process diagrams illustrating a method for manufacturing a deposition mask according to an embodiment. [Figure 16] FIG. 2 is a schematic diagram showing the configuration of a deposition apparatus together with a deposition mask and a deposition target. [Figure 17] 4 is a graph showing the height of each part in a cross section of a welding mark obtained by measuring the welding mark on the deposition mask of Example 1. [Figure 18]13 is a graph showing the height of each part in a cross section of a welding mark obtained by measuring the welding mark on the deposition mask of Example 2. [Figure 19] 13 is a graph showing the height of each part in a cross section of a welding mark obtained by measuring the welding mark on the deposition mask of Example 3. [Figure 20] 13 is a graph showing the height of each part in a cross section of a welding mark obtained by measuring the welding mark on the deposition mask of Comparative Example 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] An embodiment of a deposition mask, a method for manufacturing a deposition mask, and a method for manufacturing a display device will be described with reference to FIGS.

[0016] [Mask device] A mask device including a deposition mask will be described with reference to FIGS. As shown in Fig. 1, the mask device 10 includes a deposition mask 11 and a main frame 12. The deposition mask 11 includes a mask plate 21 and a mask frame 22. The mask frame 22 has a frame shape that defines frame holes 22H (see Fig. 2). The mask plate 21 includes a plurality of mask holes 21H. The mask plate 21 includes a mask region 21A in which the plurality of mask holes 21H are located, and a peripheral region 21B that surrounds the mask region 21A.

[0017] The deposition mask 11 can include one or more mask plates 21. In the example shown in Fig. 1, the deposition mask 11 includes three mask plates 21. The mask frame 22 has frame holes 22H in the same number as the mask plates 21. Each mask plate 21 is welded to the mask frame 22 so as to cover one different frame hole 22H.

[0018] The mask plate 21 is made of metal. The mask plate 21 may be formed of, for example, an iron-nickel based alloy. The iron-nickel based alloy may include 36% by weight nickel and the remainder iron. Alternatively, the iron-nickel based alloy may include 42% by weight nickel and the remainder iron. The iron-nickel based alloy may include impurities that are metals other than nickel and iron.

[0019] The mask frame 22 is made of metal like the mask plate 21. The mask frame 22 may be made of the same material as the mask plate 21, or may be made of a material different from that of the mask plate 21. The mask frame 22 may be made of, for example, stainless steel, or an iron-nickel alloy. The iron-nickel alloy may include 36% nickel by weight and the remainder iron. The iron-nickel alloy may include 42% nickel by weight and the remainder iron. The iron-nickel alloy may include impurities that are metals other than nickel and iron.

[0020] The main frame 12 has a frame shape that defines a main frame hole 12H. In the example shown in FIG. 1, the outer shape of the main frame 12 has a rectangular shape. The main frame 12 defines a rectangular main frame hole 12H. The main frame 12 is made of metal. The main frame 12 may be formed of, for example, stainless steel or an iron-nickel based alloy. The iron-nickel based alloy may include 36% nickel by mass and the remainder iron. The iron-nickel based alloy may include 42% nickel by mass and the remainder iron. The iron-nickel based alloy may include impurities that are metals other than nickel and iron.

[0021] FIG. 2 shows a cross-sectional structure of the deposition mask 11 along a plane perpendicular to the plane in which the mask frame 22 extends. 2, the mask frame 22 has frame holes 22H penetrating the mask frame 22 in the thickness direction of the mask frame 22. The mask plates 21 are welded to the mask frame 22 such that one mask plate 21 covers one frame hole 22H. The mask plate 21 is welded to the mask frame 22 in the peripheral region 21B such that the entire mask region 21A is exposed to the frame hole 22H.

[0022] FIG. 3 shows a cross-sectional structure of the mask plate 21 along a plane perpendicular to the plane in which the mask plate 21 extends. As shown in FIG. 3, the mask plate 21 has a first surface 21F1 and a second surface 21F2. The second surface 21F2 is the surface opposite to the first surface 21F1. The mask hole 21H penetrates between the first surface 21F1 and the second surface 21F2. The mask plate 21 is welded to the mask frame 22 in the peripheral region 21B so as to cover the frame hole 22H with the first surface 21F1 in contact with the mask frame 22. The thickness TM of the mask plate 21 may be 10 μm or less. The thickness of the mask frame 22 may be 20 μm or more and 100 μm or less, and preferably 20 μm or more and 50 μm or less.

[0023] The first opening 21H1 of the mask hole 21H is located on the first surface 21F1. The second opening 21H2 of the mask hole 21H is located on the second surface 21F2. When viewed from a viewpoint facing the first surface 21F1, the second opening 21H2 is located within the first opening 21H1. That is, the first opening 21H1 is larger than the second opening 21H2. The mask hole 21H has a shape that tapers from the first opening 21H1 toward the second opening 21H2.

[0024] When the mask device 10 is mounted on the deposition apparatus, the first surface 21F1 faces the deposition source, and the second surface 21F2 faces the deposition target. Since the mask hole 21H has a shape tapered from the first opening 21H1 toward the second opening 21H2, the side surface defining the mask hole 21H is unlikely to be shaded by the deposition material.

[0025] FIG. 4 shows a planar structure of the welding traces as viewed from a viewpoint opposite to the second surface 21F2 of the mask plate 21. As shown in FIG. As shown in FIG. 4, the peripheral region 21B includes a welding mark 21W. A plurality of welding marks 21W are located in the peripheral region 21B. The welding mark 21W has a first recess 21WR1. In a plan view facing the second surface 21F2, the first recess 21WR1 has a substantially circular shape. A first protrusion 21WP1 is located around the edge of the first recess 21WR1. The first protrusion 21WP1 may be located over the entire edge of the first recess 21WR1 or over a portion of the edge. In other words, the first protrusion 21WP1 may have a closed ring shape or an open ring shape when viewed from a perspective facing the second surface 21F2.

[0026] The welding mark 21W further includes a second recess 21WR2. The second recess 21WR2 is located within the first recess 21WR1 when viewed from a viewpoint facing the second surface 21F2. The second recess 21WR2 has a substantially circular shape when viewed from a viewpoint facing the second surface 21F2. A second raised portion 21WP2 is located around the edge of the second recess 21WR2. The second raised portion 21WP2 may be located on the entire edge of the second recess 21WR2 or on a part of it. In other words, the second raised portion 21WP2 may have a closed ring shape or an open ring shape when viewed from a viewpoint facing the second surface 21F2.

[0027] FIG. 5 shows a cross-sectional structure of the welding mark 21W along a plane perpendicular to the second surface 21F2 of the mask plate 21. As shown in FIG. 5, in a cross section perpendicular to the second surface 21F2, a plane including the flat portion of the second surface 21F2 is the reference plane RP. As described above, the welding mark 21W includes the first recess 21WR1, the second recess 21WR2, the first raised portion 21WP1, and the second raised portion 21WP2.

[0028] The first recess 21WR1 is recessed with respect to the reference plane RP. The second recess 21WR2 is further recessed from the bottom of the first recess 21WR1. The first raised portion 21WP1 is raised from the reference plane RP at the edge of the first recess 21WR1. A maximum value MX1 of the distance between the reference plane RP and the first raised portion 21WP1 (hereinafter, first maximum value MX1) is 1.0 μm or less.

[0029] When forming a deposition pattern using the mask device 10, the mask device 10 and the deposition target are placed in the deposition device so that the deposition target is in contact with the second surface 21F2 of the mask plate 21 or the second surface 21F2 of the mask plate 21 is close to the deposition target. A bank may be formed on the deposition target to distinguish a pattern formed on the deposition target from other patterns. The distance between the surface on which the bank is formed in the deposition target, i.e., the surface to be deposited, and the top of the bank, i.e., the height of the bank, is set to, for example, 2.0 μm.

[0030] In this regard, the height of the first raised portion 21WP1 protruding from the flat portion of the mask plate 21 is 1.0 μm or less. Therefore, in both cases where the mask plate 21 is in contact with the deposition target and where it is close to the deposition target, the distance between the mask plate 21 and the deposition target surface is not expanded by the first raised portion 21WP1. This prevents the accuracy of the deposition pattern from decreasing. The accuracy of the deposition pattern includes at least one of the accuracy of the position of the deposition pattern on the deposition target and the accuracy of the shape of the deposition pattern.

[0031] Even if the deposition target does not have a bank, if the height of the first protrusion 21WP1 is 1.0 μm or less, the distance between the mask plate 21 and the deposition target surface becomes sufficiently small, so that the distance between the mask plate 21 and the deposition target is prevented from expanding. This prevents the accuracy of the deposition pattern from decreasing.

[0032] The distance between the reference plane RP and the first raised portion 21WP1 is the height of the first raised portion 21WP1. The height of the first raised portion 21WP1 may be uniform throughout the entire first raised portion 21WP1. Alternatively, the height of the first raised portion 21WP1 may include a first size and a second size different from the first size. In either case, if the maximum value MX1 of the height of the first raised portion 21WP1 is 1.0 μm or less, the height of the first raised portion 21WP1 is 1.0 μm or less throughout the entire first raised portion 21WP1.

[0033] In the welding mark 21W, the maximum value MX3 of the distance between the bottom of the first recess 21WR1 and the first raised portion 21WP1 is equal to or greater than the maximum value MX2 of the distance between the bottom of the first recess 21WR1 and the second raised portion 21WP2. Hereinafter, the maximum value MX3 is the third maximum value MX3, and the maximum value MX2 is the second maximum value. It is more preferable that the second maximum value MX2 is equal to or less than the minimum value MM of the distance between the bottom of the first recess 21WR1 and the first raised portion 21WP1.

[0034] Since the second raised portion 21WP2 does not protrude beyond the first raised portion 21WP1, the second raised portion 21WP2 is prevented from increasing the distance between the mask plate 21 and the deposition surface. As a result, the accuracy of the deposition pattern formed using the deposition mask 11 is prevented from decreasing.

[0035] The portion of the first recess 21WR1 that includes the portion that is the farthest from the reference plane RP is the bottom of the first recess 21WR1. As described above, the height of the first raised portion 21WP1 may include a first size and a second size. Therefore, the distance between the bottom of the first recess 21WR1 and the first raised portion 21WP1 may also include a first size and a second size different from the first size, similar to the height of the first raised portion 21WP1.

[0036] On the other hand, the distance between the bottom of the first recess 21WR1 and the second raised portion 21WP2 is the height of the first raised portion 21WP1. The height of the second raised portion 21WP2 may be uniform throughout the second raised portion 21WP2. Alternatively, the height of the second raised portion 21WP2 may include a first size and a second size different from the first size.

[0037] Therefore, if the second maximum value MX2 is equal to or less than the third maximum value MX3, the second raised portion 21WP2 does not protrude beyond the first raised portion 21WP1. That is, the welding mark 21W does not have a portion that protrudes more than 1.0 μm from the reference plane RP. Also, if the second maximum value MX2 is equal to or less than the above-mentioned minimum value MM, the second raised portion 21WP2 is prevented from protruding beyond the first raised portion 21WP1 over the entire circumferential direction of the edge of the first recess 21WR1.

[0038] As described above, the thickness of the mask plate 21 is 10 μm or less. If the thickness of the mask plate 21 is 100 μm or more, a recess having a depth of several tens of μm can be formed on the second surface 21F2 of the mask plate 21, and then the mask plate 21 can be laser-welded to the mask frame 22 so that the welding mark 21W is formed in the recess. In contrast, if the thickness of the mask plate 21 is 10 μm or less, a recess for forming the welding mark 21W cannot be formed. Therefore, the effect of the welding mark 21W having a structure including the first recess 21WR1, the second recess 21WR2, the first raised portion 21WP1, and the second raised portion 21WP2 can be more significantly obtained.

[0039] [Method of manufacturing deposition mask] A method for manufacturing the deposition mask 11 will be described with reference to FIGS. The manufacturing method of the deposition mask 11 includes forming a mask plate 21, forming a mask frame 22, and welding the mask plate 21 to the mask frame 22. In forming the mask plate 21, a metal plate having a first surface and a second surface is formed with a plurality of mask holes penetrating between the first surface and the second surface. This forms the mask plate 21 including a mask region 21A in which a plurality of mask holes 21H are located and a peripheral region 21B including the mask region 21A.

[0040] In forming the mask frame 22, the mask frame 22 having a frame shape that defines the frame hole 22H is formed. In welding the mask plate 21 to the mask frame 22, the peripheral region 21B is welded to the mask frame 22 by laser welding so as to cover the frame hole 22H in a state in which the mask plate 21 is in close contact with the mask frame 22. The welding includes forming a welding mark 21W on the mask plate 21. Hereinafter, a manufacturing method of the deposition mask 11 will be described in more detail with reference to the drawings.

[0041] 6 to 11 show processes from preparing a base material for forming the mask plate 21 to forming the mask plate 21. Also, Fig. 12 to 15 show processes from joining the mask plate 21 to the mask frame 22 to removing the support from the mask plate 21. For convenience of illustration, Fig. 12 to 15 show a structure in which the mask frame 22 has only one frame hole 22H and the deposition mask 11 has one mask plate 21.

[0042] 6 to 11, in the method for manufacturing the deposition mask 11, first, a base material 30 for forming the mask plate 21 is prepared (see FIG. 6). The base material 30 of the mask plate 21 includes a metal plate 31 for forming the mask plate 21 and a support 32 for supporting the metal plate 31. The support 32 is formed of a resin layer 32a and a glass substrate 32b. In the base material 30, the resin layer 32a is sandwiched between the metal plate 31 and the glass substrate 32b.

[0043] As described above, the metal plate 31 may be made of an iron-nickel alloy. The glass substrate 32b may be made of any one selected from the group consisting of quartz glass, crystallized glass, borosilicate glass, aluminoborosilicate glass, high silicate glass, porous glass, and soda-lime glass.

[0044] Next, the thickness of the metal plate 31 is reduced by etching the metal plate 31 from the first surface 31F1. For example, the thickness of the metal plate 31 can be reduced to ½ or less of the thickness of the metal plate 31 before etching (see FIG. 7). Then, a resist layer PR is formed on the first surface 31F1 of the metal plate 31 (see FIG. 8). The resist layer PR is exposed and developed, so that a resist mask RM is formed on the first surface 31F1 (see FIG. 9).

[0045] Next, the metal plate 31 is wet-etched from the first surface 31F1 using the resist mask RM. As a result, a plurality of mask holes 21H are formed in the metal plate 31 (see FIG. 10). In the wet etching of the metal plate 31, the first openings 21H1 are formed in the first surface 31F1, and then the second openings 21H2 smaller than the first openings 21H1 are formed in the second surface 31F2. Next, the resist mask RM is removed from the surface 31F to manufacture the mask plate 21 (see FIG. 11). Note that the first surface 31F1 of the metal plate 31 corresponds to the first surface 21F1 of the mask plate 21, and the second surface 31F2 of the metal plate 31 corresponds to the second surface 21F2 of the mask plate 21.

[0046] The process of preparing the base material 30 (see FIG. 6) includes a process of sandwiching a resin layer 32a between a metal plate 31 and a glass substrate 32b, and bonding the metal plate 31 and the glass substrate 32b via the resin layer 32a. When the metal plate 31, the resin layer 32a, and the glass substrate 32b are bonded, a CB (Chemical Bonding) process is first performed on at least the surfaces of the metal plate 31 and the glass substrate 32b that are in contact with the resin layer 32a. The surfaces of the metal plate 31 and the glass substrate 32b on which the CB process is performed are the target surfaces. In the CB process, for example, a chemical solution is applied to the target surface, so that functional groups reactive to the resin layer 32a are applied to the target surface. In the CB process, for example, a Si-based compound is applied to the target surface.

[0047] Then, the metal plate 31, the resin layer 32a, and the glass substrate 32b are stacked in the order described above, and then thermocompression bonded together. At this time, the target surface of the metal plate 31 and the target surface of the glass substrate 32b are brought into contact with the resin layer 32a. As a result, the functional groups provided on the target surface react with the functional groups located on the surface of the resin layer 32a, thereby bonding the metal plate 31 and the resin layer 32a, and bonding the glass substrate 32b and the resin layer 32a.

[0048] The resin layer 32a is preferably made of polyimide. In this case, the linear expansion coefficients of the metal plate 31, the resin layer 32a, and the glass substrate 32b are approximately the same. Therefore, even if the laminate formed of the metal plate 31, the resin layer 32a, and the glass substrate 32b is heated in the process of manufacturing the deposition mask 11, warping of the laminate caused by the difference in linear expansion coefficient between the layers forming the laminate is suppressed.

[0049] Electrolysis or rolling is used as a method for manufacturing the metal plate 31. As post-treatment of the metal plate 31 obtained by these methods, polishing, annealing, etc. are appropriately used. When electrolysis is used for manufacturing the metal plate 31, the metal plate 31 is formed on the surface of an electrode used for electrolysis. Then, the metal plate 31 is released from the surface of the electrode. In this manner, the metal plate 31 is manufactured. In the above-mentioned bonding step, it is preferable to bond the metal plate 31 having a thickness of 10 μm or more to the glass substrate 32b via the resin layer 32a. When the metal plate 31 is manufactured by rolling, the thickness of the metal plate 31 is preferably 15 μm or more. When the metal plate 31 is manufactured by electrolysis, the thickness of the metal plate 31 is preferably 10 μm or more.

[0050] In the thinning process (see FIG. 7) for reducing the thickness of the metal plate 31 before forming the resist mask RM on the metal plate 31, wet etching can be used. As described above, in the thinning process, the thickness of the metal plate 31 after thinning can be reduced to 1 / 2 or less of the thickness of the metal plate 31 before thinning. Therefore, the thickness of the metal plate 31 can be made twice or more the thickness of the mask plate 21. As a result, even if the thickness required for the mask plate 21 is as thin as 10 μm or less as described above, a metal plate 31 having higher rigidity than the mask plate 21 of the deposition mask 11 can be used before the metal plate 31 is bonded to the glass substrate 32b. Therefore, it is easier to bond the metal plate 31 to the glass substrate 32b than to bond a metal plate 31 having the same thickness as the mask plate 21 to the glass substrate 32b. The step of reducing the thickness of the metal plate 31 can be omitted.

[0051] An acidic etching solution can be used as an etching solution for thinning the metal plate 31 by wet etching. When the metal plate 31 is made of Invar, the etching solution may be any etching solution capable of etching Invar. The acidic etching solution may be, for example, a solution in which either a ferric perchlorate solution or a mixed solution of a ferric perchlorate solution and a ferric chloride solution is mixed with either perchloric acid, hydrochloric acid, sulfuric acid, formic acid, or acetic acid. The method for etching the first surface 31F1 can be any of a dip type, a spray type, and a spin type.

[0052] In the etching step (see FIG. 10) for forming the mask holes 21H in the metal plate 31, an acidic etching solution can be used as the etching solution. When the metal plate 31 is made of an iron-nickel alloy, any of the etching solutions that can be used in the thinning process described above can be used as the etching solution. Any of the etching methods that can be used in the thinning process can be used as the etching method for forming the mask holes 21H.

[0053] The step of preparing the base material 30 may include a step of thinning the metal plate 31 from one surface of the metal plate 31 before bonding the metal plate 31, the resin layer 32a, and the glass substrate 32b to one another. In this case, the thinning step included in the step of preparing the base material 30 is a first thinning step, and the thinning step performed after the step of preparing the base material 30 is a second thinning step.

[0054] In the first thinning process, the metal plate 31 is thinned by etching from one surface. In contrast, in the second thinning process, the metal plate 31 is thinned by etching from a surface different from the surface etched in the first thinning process. The surface that is etched first is the second surface 31F2 of the metal plate 31 that is to be joined to the resin layer 32a and is also the surface that is to be subjected to the CB treatment.

[0055] By etching both the first surface 31F1 and the second surface 31F2 of the metal plate 31, it is possible to adjust the residual stress of the metal plate 31 from both the first surface 31F1 and the second surface 31F2. This makes it possible to prevent the occurrence of bias in the residual stress of the metal plate 31 after etching, compared to the case where only one surface is etched. Therefore, when the mask plate 21 obtained from the metal plate 31 is bonded to the mask frame 22, the occurrence of wrinkles in the mask plate 21 is prevented.

[0056] The etching amount when etching the metal plate 31 from the first surface 31F1 is the first etching amount, and the etching amount when etching the metal plate 31 from the second surface 31F2 is the second etching amount. The first etching amount and the second etching amount may be equal or different. When the first etching amount and the second etching amount are different, the first etching amount may be larger than the second etching amount, and the second etching amount may be larger than the first etching amount. However, when the second etching amount is smaller than the first etching amount, the etching amount in a state in which the metal plate 31 is supported by the resin layer 32a and the glass substrate 32b is larger, and therefore the metal plate 31 is easy to handle. Therefore, the metal plate 31 is easily etched.

[0057] As shown in Fig. 12 to Fig. 15, a part of the mask frame 22 and a part of the mask plate 21 are joined (see Fig. 12 and Fig. 13). At this time, the multiple mask plates 21 are joined to the single mask frame 22 so that each mask plate 21 covers a different frame hole 22H one by one. Then, the glass substrate 32b is removed from the resin layer 32a (see Fig. 14). Next, the resin layer 32a is removed from each mask plate 21 (see Fig. 15). In this way, the deposition mask 11 described above is obtained.

[0058] 12, in the step of joining a part of the mask frame 22 and a part of the mask plate 21, the mask frame 22 is formed first. When forming the mask frame 22, a metal plate for forming the mask frame 22 is first prepared. Next, frame holes 22H are formed in the metal plate, thereby obtaining the mask frame 22. The frame holes 22H may be formed in the metal plate by wet etching or by laser cutting.

[0059] In the step of joining the mask plate 21 to the mask frame 22, laser welding is used. At this time, the first laser beam L1 is irradiated to the portion of the mask plate 21 included in the peripheral region 21B through the glass substrate 32b and the resin layer 32a. Therefore, the glass substrate 32b and the resin layer 32a need to be transparent to the first laser beam L1. In other words, the first laser beam L1 needs to have a wavelength that can transmit through the glass substrate 32b and the resin layer 32a. The first laser beam L1 is intermittently irradiated along the edge of the frame hole 22H to form intermittent welding marks. As a result, the mask plate 21 is welded to the mask frame 22. The wavelength of the first laser beam L1 may be, for example, 355 nm, 1064 nm, or 1070 nm.

[0060] In the step of joining the mask plate 21 to the mask frame 22, the mask plate 21 is brought into close contact with the mask frame 22 by magnetic force. As shown in Fig. 13, the mask frame 22 is placed on the support stand SS, and a laminate of the mask plate 21, the resin layer 32a, and the glass substrate 32b is placed on the mask frame 22. At this time, the mask plate 21 is brought into contact with the mask frame 22. The magnets MG are placed on the glass substrate 32b. This allows the mask plate 21 to be closely attached to the mask frame 22 by the magnetic force of the magnets MG. Since the mask plate 21 and the mask frame 22 are made of a ferromagnetic material, the mask plate 21 can be closely attached to the mask frame 22 by the magnetic force of the magnets MG. Therefore, the mask plate 21 can be closely attached to the mask frame 22 with a higher degree of adhesion than when a load is applied to the laminate of the mask plate 21 and the mask frame 22.

[0061] In a state in which the mask plate 21 is brought into close contact with the mask frame 22 by the magnetic force of the magnets MG, the mask plate 21 is irradiated with the first laser beam L1. This causes the mask plate 21 to be welded to the mask frame 22. As a result, a weld mark 21W is formed on the mask plate 21.

[0062] As described above, the welding marks 21W formed on the mask plate 21 include the first recesses 21WR1, the second recesses 21WR2, the first protrusions 21WP1, and the second protrusions 21WP2. As described above, the first maximum value MX1 is equal to or less than 1.0 μm, and the third maximum value MX3 is equal to or greater than the second maximum value MX2.

[0063] By disposing the magnet MG on the glass substrate 32b, the mask plate 21 is brought into close contact with the mask frame 22, and the energy of the first laser beam L1 is easily transmitted to the mask frame 22 as well. This makes it easier for the mask plate 21 to be recessed toward the mask frame 22 at the boundary between the mask plate 21 and the mask frame 22. As a result, a welding mark having the first recess 21WR1 is easily formed.

[0064] In the weld mark 21W, the depth of the first recess 21WR1 tends to be deeper as the magnetic force of the magnet MG is greater. Also, the depth of the first recess 21WR1 tends to be deeper as the laser output is greater. The depth of the second recess 21WR2 tends to be deeper as the laser output is greater. The height of the first raised portion 21WP1 tends to be higher as the magnetic force of the magnet MG is greater. Also, the height of the first raised portion 21WP1 tends to be higher as the laser output is greater. The height of the second raised portion 21WP2 tends to be higher as the laser output is greater.

[0065] The process of removing the support 32 includes a first process (see FIG. 14) and a second process (see FIG. 15). In the first process, a second laser beam L2 is irradiated onto the interface between the resin layer 32a and the glass substrate 32b. The second laser beam L2 has a wavelength that is transmitted by the glass substrate 32b and absorbed by the resin layer 32a. This removes the glass substrate 32b from the resin layer 32a. The wavelength of the second laser beam L2 is preferably 308 nm or 355 nm.

[0066] In the first step, the interface between the resin layer 32a and the glass substrate 32b is irradiated with the second laser beam L2, so that the thermal energy of the second laser beam L2 is absorbed by the resin layer 32a. This heats the resin layer 32a, thereby lowering the strength of the chemical bond between the resin layer 32a and the glass substrate 32b. Then, the glass substrate 32b is removed from the resin layer 32a. In the first step, it is preferable to irradiate the second laser beam L2 to the entire welded portion, but if it is possible to lower the strength of the bond between the glass substrate 32b and the resin layer 32a over the entire welded portion, the second laser beam L2 may be irradiated to a part of the welded portion.

[0067] It is preferable that the transmittance of the glass substrate 32b is higher than that of the resin layer 32a at the wavelength of the second laser beam L2. This can increase the efficiency of heating the portion of the resin layer 32a that forms the interface between the glass substrate 32b and the resin layer 32a, compared to when the transmittance of the glass substrate 32b is lower than that of the resin layer 32a.

[0068] As described above, the resin layer 32a is preferably made of polyimide. Of the polyimides, the resin layer 32a is preferably made of a colored polyimide. The glass substrate 32b is preferably transparent.

[0069] In the second step, after the first step, the resin layer 32a is dissolved using the chemical liquid LM, thereby removing the resin layer 32a from the mask plate 21. The chemical liquid LM can be a liquid that can dissolve the material forming the resin layer 32a and has no reactivity with the material forming the mask plate 21. The chemical liquid LM can be, for example, an alkaline solution. The alkaline solution can be, for example, a sodium hydroxide aqueous solution. Note that, although the dipping method is exemplified as a method for contacting the resin layer 32a with the chemical liquid LM in FIG. 15, the method for contacting the resin layer 32a with the chemical liquid LM can also be a spray method or a spin method.

[0070] Thus, in the process of removing the support 32 from the mask plate 21, the glass substrate 32b is removed from the resin layer 32a in the first process, and the resin layer 32a is removed from the mask plate 21 in the second process. Therefore, it is possible to reduce the external force acting on the mask plate 21 compared to the case where the support 32 is removed from the mask plate 21 by interfacial destruction caused by an external force applied to the laminate of the glass substrate 32b, the resin layer 32a, and the mask plate 21. This suppresses deformation of the mask plate 21 caused by removal of the support 32, and thus deformation of the mask holes 21H in the mask plate 21.

[0071] [Display device manufacturing method] A method for manufacturing a display device will now be described with reference to FIG. The manufacturing method of the display device includes forming a pattern on the deposition target S using the deposition mask 11 manufactured by the manufacturing method of the deposition mask 11. Hereinafter, a process of forming a pattern will be described along with an example of a deposition apparatus.

[0072] As shown in FIG. 16, the vapor deposition apparatus 40 includes a storage tank 41 that stores the mask device 10 and the vapor deposition target S. The storage tank 41 is configured to hold the vapor deposition target S and the mask device 10 at predetermined positions in the storage tank 41. In the storage tank 41, a holding unit 42 that holds the vapor deposition material Mvd and a heating unit 43 that heats the vapor deposition material Mvd are located. The vapor deposition material Mvd held in the holding unit 42 is an organic light-emitting material. The storage tank 41 positions the vapor deposition target S and the mask device 10 in the storage tank 41 such that the mask device 10 is located between the vapor deposition target S and the holding unit 42 and the mask device 10 and the holding unit 42 face each other. The mask device 10 is disposed in the storage tank 41 with the second surface 21F2 of the vapor deposition mask 11 in close contact with or close to the vapor deposition target S.

[0073] In the process of forming a pattern, the deposition material Mvd is heated by the heating unit 43, whereby the deposition material Mvd is vaporized or sublimated. The vaporized or sublimated deposition material Mvd passes through the mask holes 21H of the deposition mask 11 and adheres to the deposition target S. As a result, an organic layer having a shape corresponding to the shape and position of the mask holes 21H of the deposition mask 11 is formed at a predetermined position on the deposition target S. The organic layer is an example of a pattern.

[0074] [Example] An example and a comparative example will be described with reference to FIGS. [Example 1] A metal plate made of an iron-nickel alloy containing 36% by mass of nickel, having a thickness of 10 μm, a length of 300 mm, and a width of 300 mm, was prepared. A metal plate, a polyimide resin layer having a thickness of 20 μm, and a glass substrate made of synthetic quartz having a thickness of 2.3 mm were prepared. Then, the metal plate, the resin layer, and the glass substrate were laminated in this order, and the metal plate, the resin layer, and the glass substrate were thermocompression bonded. A mask region having a length of 250 mm and a width of 220 mm was formed on the metal plate by wet etching. Thus, a mask plate was formed from the metal plate.

[0075] A metal plate made of an iron-nickel alloy containing 36 mass % of nickel and having a thickness of 10 mm was prepared. Frame holes were formed in the metal plate by wet etching to obtain a mask frame.

[0076] A mask frame was placed on the support table, and then a laminate of the deposition mask, the resin layer, and the glass substrate was placed on the mask frame so that the peripheral region of the deposition mask was in contact with the mask frame. Then, a pressure of 10 N / cm was applied to the four corners of the glass substrate. 2 A neodymium magnet having an attractive force of 1.0 MPa was placed on the mask plate to tightly attach it to the mask frame.

[0077] A multimode fiber laser was prepared that oscillated a laser beam having a wavelength of 1070 nm and had a spot diameter of 100 μm. The peripheral area of ​​the mask plate was irradiated with the laser beam at intervals of 1 mm. The laser output was set to 20 W, and the pulse width was set to 1 ms. The mask plate was irradiated with the laser beam through the glass substrate and the resin layer.

[0078] [Example 2] A deposition mask of Example 2 was obtained in the same manner as in Example 1, except that the laser output in Example 1 was changed to 40 W.

[0079] [Example 3] A deposition mask of Example 3 was obtained in the same manner as in Example 1, except that the pulse width was changed to 2 milliseconds.

[0080] [Comparative Example 1] A deposition mask of Comparative Example 1 was obtained in the same manner as in Example 1, except that a neodymium magnet was not placed on the glass substrate when the mask plate was irradiated with a laser beam.

[0081] [Evaluation method] For each deposition mask, the height of each part including the welding marks was measured using a laser microscope (LEXT OLS4000, manufactured by Olympus Corporation) in a cross section along a plane perpendicular to the second surface of the mask plate. For each deposition mask, the height of each part in five welding marks was measured. Then, the average values ​​were calculated for the first maximum value of the distance between the reference surface and the first raised portion, the second maximum value of the distance between the bottom of the first recess and the first raised portion, and the third maximum value of the distance between the bottom of the first recess and the second raised portion.

[0082] [Evaluation Results] In Example 1, it was found that the first maximum value MX1 was 0.6 μm, the second maximum value MX2 was 1.8 μm, and the third maximum value MX3 was 9.7 μm. Note that Fig. 17 shows a representative example of the shape of the welding marks provided on the deposition mask of Example 1. Also, the unit of the horizontal axis in Figs. 17 to 20 is μm.

[0083] In Example 2, it was found that the first maximum value MX1 was 0.8 μm, the second maximum value MX2 was 5.1 μm, and the third maximum value MX3 was 5.9 μm. Note that FIG. 18 shows a representative example of the shape of the welding marks provided on the deposition mask of Example 2.

[0084] In Example 3, it was found that the first maximum value MX1 was 0.7 μm, the second maximum value MX2 was 6.1 μm, and the third maximum value MX3 was 7.3 μm. Note that FIG. 19 shows a representative example of the shape of the welding marks provided on the deposition mask of Example 3.

[0085] In the welding mark of Comparative Example 1, only a first recess and one protrusion located at the edge of the recess were observed. In addition, it was confirmed that the maximum distance between the reference plane and the protrusion was 2.7 μm. Note that FIG. 20 shows a representative example of the shape of the welding mark of the deposition mask of Comparative Example 1.

[0086] In addition, it was confirmed that the diameter of the first recess in the welding marks of each deposition mask was about 450 μm when viewed from the viewpoint facing the second surface. In addition, it was confirmed that the depth of the welding marks shown in Fig. 17 to Fig. 19 exceeded the thickness of the mask plate 21, that is, a part of the welding marks of the mask plate was embedded in the mask plate.

[0087] A deposition target having a first surface and a bank having a height of 2.0 μm on the first surface was prepared. When the deposition target was placed on the deposition masks of Examples 1 to 3, it was found that the bank contacted the flat portion of the deposition mask because the first maximum value MX1 was 1.0 μm or less. In contrast, when the deposition target was placed on the deposition mask of Comparative Example 1, it was found that the deposition mask had a protruding portion exceeding 2.0 μm, and therefore the protruding portion of the deposition mask contacted the deposition target.

[0088] As described above, according to the embodiment of the deposition mask, the method for manufacturing the deposition mask, and the method for manufacturing the display device, the following effects can be obtained. (1) The height of the first raised portion 21WP1 protruding from the flat portion of the mask plate 21 is 1.0 μm or less. Therefore, when the deposition target S has a bank, the distance between the mask plate 21 and the deposition target surface is not expanded by the first raised portion 21WP1 both when the mask plate 21 is in contact with the deposition target S and when it is close to the deposition target S. This prevents the accuracy of the deposition pattern from decreasing. Alternatively, even when the deposition target S does not have a bank, if the height of the first raised portion 21WP1 is 1.0 μm or less, the distance between the mask plate 21 and the deposition target surface becomes sufficiently small, so that the accuracy of the deposition pattern is prevented from decreasing.

[0089] (2) Since the second raised portion 21WP2 does not protrude beyond the first raised portion 21WP1, the second raised portion 21WP2 is prevented from increasing the distance between the mask plate 21 and the deposition surface. As a result, the accuracy of the deposition pattern formed using the deposition mask 11 is prevented from decreasing.

[0090] (3) If the thickness of the mask plate 21 is 10 μm or less, it is not possible to form a recess for forming the welding mark 21W. Therefore, it is possible to obtain a more significant effect of the structure of the welding mark 21W including the first recess 21WR1, the second recess 21WR2, the first raised portion 21WP1, and the second raised portion 21WP2.

[0091] (4) The mask plate 21 can be brought into close contact with the mask frame 22 by magnetic force. Therefore, the mask plate 21 can be brought into closer contact with the mask frame 22 with a higher degree of adhesion than when a load is applied to a laminate of the mask plate 21 and the mask frame 22.

[0092] The above-described embodiment can be modified as follows. [Welding marks] The welding mark 21W may not have the second raised portion 21WP2. Even in this case, as long as the first maximum value MX1 is 1.0 μm or less, the effect equivalent to that of (1) above can be obtained. For the welding mark 21W without the second raised portion 21WP2, for example, the laser used to weld the mask plate 21 and the mask frame 22 may be changed from a multimode fiber laser to a single mode laser. This suppresses the formation of the second raised portion 21WP2, so it is also possible to form the welding mark 21W without the second raised portion 21WP2.

[0093] [Mask board] The thickness of the mask plate 21 may be greater than 10 μm. Even in this case, as long as the first maximum value in the welding mark 21W is 1.0 μm or less, the effect equivalent to that of (1) described above can be obtained.

[0094] The mask plate 21 may be made of two or more materials. In this case, the portion of the mask plate 21 that includes the portion on which the magnetic force of the magnet MG acts may be a first magnetic portion made of a ferromagnetic material, while the other portions may be made of a metal other than a ferromagnetic material. Even in this case, the effect equivalent to that of (4) above can be obtained.

[0095] [Mask frame] The mask frame 22 may be made of two or more materials. In this case, the portion of the mask frame 22 that includes the portion on which the magnetic force of the magnet MG acts may be a second magnetic portion made of a ferromagnetic material, while the other portions may be made of a metal other than a ferromagnetic material. Even in this case, the effect equivalent to that of (4) above can be obtained.

[0096] [Method of manufacturing deposition mask] A weight having no magnetic force may be used instead of the magnet MG when the mask plate 21 is brought into close contact with the mask frame 22. Even in this case, the mask plate 21 can be brought into close contact with the mask frame 22, and therefore the welding mark 21W having the first recess 21WR1 is more easily formed than when no weight is used. [Explanation of symbols]

[0097] 10...Mask device 11…Deposition mask 12…Mainframe 21...Mask plate 21A…Mask area 21B…Surrounding area 21H…Mask hole 21W…Welding traces 21WP1…1st raised part 21WP2…Second raised part 21WR1…First recess 21WR2…Second recess 22...Mask frame

Claims

1. a mask frame having a frame shape that defines a frame hole; a mask plate including a first surface, a second surface, and a plurality of mask holes penetrating between the first surface and the second surface, the mask plate comprising a mask region in which the plurality of mask holes are located, and a peripheral region surrounding the mask region, the mask plate being welded to the mask frame in the peripheral region so as to cover the frame holes with the first surface in contact with the mask frame; The peripheral region includes a welding mark, In a cross section perpendicular to the second surface, a plane including a flat portion of the second surface is a reference surface, The welding marks are A first recess recessed relative to the reference surface; a second recess further recessed from a bottom of the first recess; a protruding portion protruding from the reference surface at an edge of the first recess, The maximum value of the distance between the reference surface and the protrusion is 1.0 μm or less. Evaporation mask.

2. the raised portion is a first raised portion, The welding mark further includes a second raised portion that is raised from the bottom portion of the first recess at an edge of the second recess, a maximum value of the distance between the bottom of the first recess and the first raised portion is equal to or greater than a maximum value of the distance between the bottom of the first recess and the second raised portion; The deposition mask according to claim 1 .

3. The thickness of the mask plate is 10 μm or less. The deposition mask according to claim 1 .

4. forming a plurality of mask holes penetrating between a first surface and a second surface in a metal plate having a first surface and a second surface, thereby forming a mask plate having a mask region in which the plurality of mask holes are located and a peripheral region including the mask region; forming a mask frame having a frame shape that defines a frame hole; and welding the peripheral area to the mask frame by laser welding so as to cover the frame hole while the mask plate is in close contact with the mask frame; The welding includes forming a welding mark on the mask plate; In a cross section perpendicular to the second surface, a plane including a flat portion of the second surface is a reference surface, The welding marks are A first recess recessed relative to the reference surface; a second recess further recessed from a bottom of the first recess; a protruding portion protruding from the reference surface at an edge of the first recess, The maximum value of the distance between the reference surface and the protrusion is 1.0 μm or less. A method for manufacturing a deposition mask.

5. the mask frame includes a first magnetic portion having ferromagnetic properties, the mask plate includes a second magnetic portion having ferromagnetic properties, The welding step includes welding the mask plate to the mask frame in a state in which the second magnetic portion is closely attached to the first magnetic portion by a magnetic force. The method for producing the deposition mask according to claim 4 .

6. forming a pattern on a deposition target using a deposition mask manufactured by the method for manufacturing a deposition mask according to claim 4 or 5. A method for manufacturing a display device.

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