JP7615698B2 - DEPOSITION MASK, METHOD FOR MANUFACTURING DEPOSITION MASK, AND METHOD FOR MANUFACTURING DISPLAY DEVICE - Google Patents

Description

The present invention relates to a deposition mask, a method for manufacturing a deposition mask, and a method for manufacturing a display device.

The organic EL display device includes a plurality of display pixels. Each display pixel includes a plurality of subpixels. For example, one display pixel includes a red subpixel, a green subpixel, and a blue subpixel. In one example of a display pixel, the red subpixel and the green subpixel are substantially square-shaped. In contrast, the blue subpixel is rectangular-shaped. In the blue subpixel, the length of the long side of the blue pixel is substantially equal to the length of one side of the red subpixel, the length of one side of the green subpixel, and the length of the gap between the red pixel and the green pixel. In the display pixel, one red subpixel and one green subpixel are aligned along a first direction, and in a second direction perpendicular to the first direction, the blue subpixel is adjacent to the red subpixel and the green subpixel that are adjacent to each other in the first direction (see, for example, Patent Document 1).

JP 2011-249334 A

Each subpixel is formed by vacuum deposition using a metal deposition mask. The deposition mask has through-holes for forming each subpixel. As described above, when the blue subpixel has a rectangular shape, the through-hole for forming the blue subpixel also has a rectangular shape corresponding to the shape of the blue subpixel in a plan view.

When forming a deposition mask, a metal plate for forming the deposition mask is prepared. Next, a resist mask for forming through holes in the deposition mask is formed. Then, wet etching is performed on the metal plate using the resist mask, thereby forming a deposition mask with through holes.

In this case, since the through hole to be formed in the metal plate has a rectangular shape in a plan view, a mask hole having a rectangular shape in a plan view is also formed in the resist mask. In wet etching using such a resist mask, the flow of the etching solution differs between the vicinity of the long side and the vicinity of the short side of the mask hole in a plan view. As a result, in the through hole formed in the metal plate, the ratio of the length of the long side to the short side in a plan view is significantly different from that of the mask hole.

The present invention aims to provide a deposition mask that can suppress the difference between the amount of etching that widens a through hole extending in one direction in the long axis direction and the amount of etching that widens it in the short axis direction, a method for manufacturing a deposition mask, and a method for manufacturing a display device.

The deposition mask for solving the above problem is a deposition mask having a first surface, the first surface having a through hole in which a first opening is located, the first opening has a shape extending in a first direction when viewed from a viewpoint facing the first surface, and is constricted so that the width in a direction intersecting the first direction narrows midway in the first direction.

A method for manufacturing a deposition mask for solving the above problem includes forming a resist layer on a metal plate, exposing the resist layer and developing the exposed resist layer to form a resist mask, and wet-etching the metal plate using the resist mask to form a through hole in which a first opening is located on a first surface of the metal plate. By forming the through hole, the first opening is formed so that, when viewed from a viewpoint facing the first surface, the first opening has a shape that extends in a first direction, and the width of the first opening in a direction intersecting the first direction is narrowed midway in the first direction to form a constricted shape.

A manufacturing method for a display device to solve the above problem includes preparing a deposition mask using the above deposition mask manufacturing method, and forming a deposition pattern on a deposition target using the deposition mask.

According to the deposition mask, the method for manufacturing the deposition mask, and the method for manufacturing the display device, the first opening has a constricted shape, so that the flow of the etching solution is interrupted at the constricted portion during etching to form the through hole. As a result, it is possible to reduce the difference between the amount of etching that widens the through hole in the long axis direction, which is the first direction, and the amount of etching that widens the through hole in the short axis direction, compared to when the first opening does not have a constriction.

In the deposition mask, the first opening has a shape surrounded by a pair of opposing long sides and a pair of opposing short sides when viewed from a viewpoint opposite the first surface, and each short side has a straight or arc shape when viewed from a viewpoint opposite the first surface, and at least one long side may have a wavy shape that increases or decreases the distance between the pair of long sides along the extension direction of the long sides.

In the above method for manufacturing a deposition mask, the first opening has a shape surrounded by a pair of opposing long sides and a pair of opposing short sides when viewed from a viewpoint opposite the first surface, and each short side may have a straight or arc shape, and at least one long side may have a wavy shape that increases or decreases the distance between the pair of long sides along the extension direction of the long sides.

According to the deposition mask, each long side has a wavy shape, so when forming a through hole using a resist mask in a metal plate for forming a deposition mask, it is possible to use a resist mask configured to divide the long side of the mask hole of the resist mask into the same number of waves as the long side of the through hole. As a result, when etching the metal plate, the area where the etching solution flows on the long side of the mask hole is divided into the same number of waves as the long side of the through hole. Therefore, when viewed from the etching solution supplied to the mask hole, the difference in length between the divided long side portion and the short side of the mask hole becomes small, so it is possible to suppress the difference between the behavior of the etching solution in the long side direction and the behavior of the etching solution in the short side direction. As a result, it is possible to suppress the difference between the amount of etching that expands the through hole in the long side direction and the amount of etching that expands the through hole in the short side direction.

In the deposition mask, when viewed from a viewpoint facing the first surface, each long side may include a plurality of waves, and each short side may have a length approximately equal to the period of the waves on the long side. With this deposition mask, in etching a metal plate to form a deposition mask, it is possible to use a resist mask configured to divide the long side of the mask hole into lengths approximately equal to the short side of the mask hole. As a result, when viewed from the etching solution supplied to the mask hole, the length between the divided long side portion and the short side in the mask hole is approximately equal, so that the behavior of the etching solution in the long side direction and the behavior of the etching solution in the short side direction are approximately equal. As a result, it is possible to further reduce the difference between the amount of etching that widens the through hole in the long side direction and the amount of etching that widens the through hole in the short side direction.

In the deposition mask, each short side may have a length that is 0.6 to 1.4 times the wave period of the long side. With this deposition mask, it is preferable that each short side has a length that is 0.6 to 1.4 times the wave period of the long side.

The deposition mask may have a second surface facing the first surface, the second opening of the through hole being located on the second surface, the second opening being located within the area surrounded by the first opening when viewed from a viewpoint facing the first surface, the third opening of the through hole being located between the first opening and the second opening in the thickness direction of the deposition mask, the third opening being located within the area surrounded by the second opening when viewed from a viewpoint facing the first surface, the third opening being surrounded by a pair of long sides facing each other and a pair of short sides facing each other when viewed from a viewpoint facing the first surface, each short side of the third opening having the same shape as the short sides of the first opening, and at least one long side of the third opening may have a wavy shape that increases or decreases the distance between the pair of long sides of the third opening along the direction in which the long sides of the third opening extend.

With the deposition mask, the third opening located between the first and second openings in the thickness direction of the deposition mask can be formed together with the first opening by etching the metal plate using a resist mask having a mask hole for forming the first opening. Therefore, in the region from the first opening to the third opening in the thickness direction of the deposition mask, it is possible to suppress the difference between the amount of etching in the long side direction and the amount of etching in the short side direction of the through hole.

The present invention can reduce the difference between the amount of etching that widens the through hole in the long axis direction and the amount of etching that widens the through hole in the short axis direction.

FIG. 2 is a perspective view showing a structure of a deposition mask according to an embodiment. 2 is a plan view showing a structure of a deposition mask as viewed from a viewpoint opposite to the surface of the deposition mask shown in FIG. 1 . 3 is a cross-sectional view showing the structure of the deposition mask taken along line IIIa-IIIa in FIG. 2 together with the structure of the deposition mask taken along line IIIb-IIIb. 4 is a cross-sectional view showing a structure of a deposition mask taken along line IV-IV shown in FIG. 2 . 5A to 5C are process diagrams illustrating a method for manufacturing a deposition mask. FIG. 2 is a plan view showing the structure of an exposure mask used for exposing a resist layer. 5A to 5C are process diagrams illustrating a method for manufacturing a deposition mask. FIG. 4 is a plan view showing the shape of a resist mask opening as viewed from a viewpoint opposite to the surface of the metal layer. 5A to 5C are process diagrams illustrating a method for manufacturing a deposition mask. 5A to 5C are process diagrams illustrating a method for manufacturing a deposition mask. 5A to 5C are process diagrams illustrating a method for manufacturing a deposition mask. 5A to 5C are process diagrams illustrating a method for manufacturing a deposition mask. FIG. 4 is a plan view showing the shape of a first opening as viewed from a viewpoint opposite to the surface of the metal layer. 5A to 5C are process diagrams illustrating a manufacturing method of a display device.

An embodiment embodying 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. 1 to 14. FIG.
[Deposition mask]
The deposition mask will be described with reference to FIGS.

FIG. 1 shows a part of a perspective structure of a deposition mask.
1, the deposition mask 10 has a front surface 10F and a back surface 10R. The back surface 10R is a surface of the deposition mask 10 that faces the front surface 10F. The front surface is an example of a first surface, and the back surface is an example of a second surface.

The deposition mask 10 has through holes 11. In this embodiment, the deposition mask 10 has a plurality of through holes 11. The through holes 11 are holes for forming a predetermined deposition pattern on the deposition target during deposition using the deposition mask 10. The deposition pattern forms, for example, sub-pixels of a display pixel provided in an organic EL display device.

The deposition mask 10 includes a mask region 10R1 and a peripheral region 10R2. The peripheral region 10R2 surrounds the mask region 10R1. No through holes 11 for forming a deposition pattern are formed in the peripheral region 10R2. A plurality of through holes 11 are located in the mask region 10R1. The deposition mask 10 includes, for example, a plurality of mask regions 10R1. In the mask region 10R1, the plurality of through holes 11 are arranged according to a predetermined rule. For example, in the example shown in FIG. 1, the plurality of through holes 11 are arranged in a staggered pattern. The through holes 11 may also be arranged in a lattice pattern.

The thickness T of the deposition mask 10 may be, for example, 1 μm or more and 50 μm or less. In the deposition mask 10, the thickness in the mask region 10R1 and the thickness in the peripheral region 10R2 may be the same. Alternatively, the thickness of the mask region 10R1 may be thinner than the thickness of the peripheral region 10R2. Note that when the thickness of the mask region 10R1 is thinner than the thickness of the peripheral region 10R2, the above-mentioned range of thickness T is a range that includes the thickness of the peripheral region 10R2.

FIG. 2 shows the shape of the through-hole 11 as viewed from a viewpoint opposite to the front surface 10F.
2, the surface opening 11AF of the through hole 11 is located on the surface 10F of the deposition mask 10. The surface opening 11AF is an example of a first opening. When viewed from a viewpoint facing the surface 10F, the surface opening 11AF has a shape extending in a first direction, and is constricted such that the width in a direction intersecting the first direction narrows midway in the first direction. The first direction is the long axis direction of the surface opening 11AF, and the direction intersecting the first direction is the short axis direction.

Since the surface opening 11AF has a constricted shape, the flow of the etching solution is interrupted at the constricted portion during etching to form the through hole 11. As a result, the difference between the amount of etching that widens the through hole 11 in the long axis direction and the amount of etching that widens the through hole 11 in the short axis direction is reduced compared to when the surface opening 11AF does not have a constriction.

In this embodiment, the surface opening 11AF has a shape surrounded by a pair of opposing long sides 11L and a pair of opposing short sides 11S when viewed from a viewpoint opposite the surface 10F. Each short side 11S has a straight or arc shape. At least one long side 11L has a wavy shape that increases or decreases the distance between the pair of long sides 11L along the direction in which the long sides 11L extend. The direction in which the long sides 11L extend is the long side direction, which is an example of the long axis direction. The direction in which the short sides 11S extend is the short side direction, which is an example of the short axis direction.

Because each long side 11L has a wavy shape, when forming the through hole 11 using a resist mask in the metal plate for forming the deposition mask 10, it is possible to use a resist mask configured to divide the long side of the mask hole of the resist mask into the same number of waves as the long side of the through hole 11. As a result, when etching the metal plate, the area where the etching solution flows on the long side of the mask hole is divided into the same number of waves as the long side of the through hole 11. Therefore, as seen from the etching solution supplied to the mask hole, the difference in length between the divided long side portion and the short side of the mask hole becomes small, so it is possible to suppress the difference between the behavior of the etching solution in the long side direction and the behavior of the etching solution in the short side direction. As a result, it is possible to suppress the difference between the amount of etching that expands the through hole 11 in the long side direction and the amount of etching that expands the through hole 11 in the short side direction.

In the example shown in FIG. 2, both long sides 11L have a wavy shape that increases and decreases the distance between the pair of long sides 11L along the direction in which the long sides 11L extend. Each short side 11S has a substantially straight shape. Each short side 11S may have an arc shape that protrudes in a direction away from the center of the area surrounded by the surface opening 11AF. In other words, each short side 11S may have an arc shape whose center of curvature is located within the area surrounded by the surface opening 11AF. Alternatively, each short side 11S may have one valley. That is, each short side 11S may have an arc shape that is recessed in a direction toward the center of the area surrounded by the surface opening 11AF. In other words, each short side 11S may have an arc shape whose center of curvature is located outside the area surrounded by the surface opening 11AF.

Each long side 11L includes multiple waves. That is, each long side 11L includes multiple peaks 11L1 and multiple valleys 11L2. The portions of the long sides 11L that protrude away from the center of the area surrounded by the surface opening 11AF are the peaks 11L1, and the portions that are recessed toward the center of the area surrounded by the surface opening 11AF are the valleys 11L2. The peaks 11L1 are sandwiched between two valleys 11L2 in the direction in which the long side 11L extends. Alternatively, the peaks 11L1 are sandwiched between the intersection of the long side 11L and the short side 11S and one valley 11L2 in the direction in which the long side 11L extends.

A portion of the long side 11L that includes one peak 11L1 and is defined by two valleys 11L2 that sandwich the peak 11L1 is one wave. Alternatively, a portion of the long side 11L that includes one peak 11L1 and is defined by the valleys 11L2 that sandwich the peak 11L1 and the intersection point described above is one wave. Each long side 11L has two or more waves. In the example shown in FIG. 2, each long side 11L has four waves.

Each short side 11S can have a length approximately equal to the wave period of the long side 11L. This makes it possible to use a resist mask configured to divide the long side of the mask hole into lengths approximately equal to the short side of the mask hole when etching a metal plate to form a deposition mask 10. Therefore, when viewed from the etching solution supplied to the mask hole, the length between the divided long side portion and the short side in the mask hole is approximately equal, so the behavior of the etching solution in the long side direction and the behavior of the etching solution in the short axis direction are approximately equal. As a result, it is possible to further reduce the difference between the amount of etching that widens the through hole 11 in the long side direction and the amount of etching that widens it in the short axis direction.

The wave period is the distance between the valleys 11L2 that sandwich one peak 11L1 in the direction in which each long side 11L extends. Alternatively, the wave period is the distance between the valleys 11L2 that sandwich one peak 11L1 in the direction in which each long side 11L extends and the above-mentioned intersection.

Each short side 11S can have a length that is 0.6 to 1.4 times the wave period of the long side 11L. As described above, if each short side 11S has an arc shape, the distance between the above-mentioned intersection points of each short side 11S is the length of each short side 11S.

The back opening 11AR of the through hole 11 is located on the back surface 10R. When viewed from a viewpoint facing the front surface 10F, the back opening 11AR is located within the area surrounded by the front opening 11AF. In other words, the back opening 11AR is smaller than the front opening 11AF in both the direction in which the long side 11L extends and the direction in which the short side 11S extends. In the example shown in FIG. 2, the back opening 11AR has a substantially rectangular shape. The back opening 11AR is an example of a second opening.

The central opening 11AC of the through hole 11 is located between the front opening 11AF and the back opening 11AR in the thickness direction of the deposition mask 10. When viewed from a viewpoint facing the front surface 10F, the central opening 11AC is located within the area surrounded by the back opening 11AR. That is, the central opening 11AC is smaller than the back opening 11AR in both the direction in which the long side 11L extends and the direction in which the short side 11S extends. When viewed from a viewpoint facing the front surface 10F, the front opening 11AF and the central opening 11AC are visible, while the back opening 11AR is not visible.

When viewed from a viewpoint facing the front surface 10F, the central opening 11AC has a shape surrounded by a pair of opposing long sides ACL and a pair of opposing short sides ACS. When viewed from a viewpoint facing the front surface 10F, each short side ACS of the central opening 11AC has the same shape as the short side 11S of the front surface opening 11AF, and at least one long side ACL of the central opening 11AC has a wavy shape that increases or decreases the distance between the pair of long sides ACL in the central opening 11AC along the extension direction of the long sides ACL.

For example, in the example shown in FIG. 2, each short side ACS has a substantially straight shape. As long as each short side ACS has the same shape as the short side 11S of the front opening 11AF, it can have the following shapes. That is, each short side ACS may have an arc shape that protrudes in a direction away from the center of the area surrounded by the central opening 11AC. In other words, each short side ACS may have an arc shape whose center of curvature is located within the area surrounded by the central opening 11AC. Alternatively, each short side ACS may have one valley portion. That is, each short side ACS may have an arc shape that is recessed in a direction toward the center of the area surrounded by the central opening 11AC. In other words, each short side ACS may have an arc shape whose center of curvature is located outside the area surrounded by the central opening 11AC.

Each long side ACL includes multiple waves. That is, each long side ACL includes multiple peaks ACL1 and multiple valleys ACL2. In the long side ACL, the portion protruding away from the center of the area surrounded by the central opening 11AC is the peak ACL1, and the portion recessed toward the center of the area surrounded by the central opening 11AC is the valley ACL2. The peak ACL1 is sandwiched between two valleys ACL2 in the direction in which the long side ACL extends. Alternatively, the peak ACL1 is sandwiched between the intersection of the long side ACL and the short side ACS and one valley ACL2 in the direction in which the long side ACL extends. The long side ACL of the central opening 11AC includes the same number of peaks ACL1 and valleys ACL2 as the long sides 11L of the front opening 11AF.

A portion of the long side ACL that includes one peak portion ACL1 and is defined by two valley portions ACL2 that sandwich the peak portion ACL1 is one wave. Alternatively, a portion of the long side ACL that includes one peak portion ACL1 and is defined by the valley portions ACL2 that sandwich the peak portion ACL1 and the intersection point described above is one wave. Each long side ACL has two or more waves. The long side ACL of the central opening 11AC includes the same number of waves as the long side ACL of the surface opening 11AF.

Figure 3 shows the shape of the through hole 11 in a cross section along the cross section indication line shown in Figure 2. That is, Figure 3 shows the cross-sectional structure of the deposition mask 10 along a plane parallel to the direction in which the short side 11S of the surface opening 11AF extends. For convenience of illustration, Figure 3 shows the shape of the through hole 11 in a cross section along line IIIa-IIIa in Figure 2 and the shape of the through hole 11 in a cross section along line IIIb-IIIb. In Figure 3, the shape of the through hole 11 in a cross section along line IIIa-IIIa is shown using a solid line, and the shape of the through hole 11 in a cross section along line IIIb-IIIb is shown using a two-dot chain line.

As shown in FIG. 3, the through hole 11 has a large hole portion 11HL and a small hole portion 11HS. In a cross section perpendicular to the front surface 10F and perpendicular to the direction in which the through hole 11 extends, i.e., perpendicular to the long side direction, the large hole portion 11HL has a shape that tapers in the direction from the front surface 10F to the back surface 10R. In a cross section perpendicular to the front surface 10F and perpendicular to the direction in which the through hole 11 extends, i.e., perpendicular to the long side direction, the small hole portion 11HS has a shape that tapers in the direction from the back surface 10R to the front surface 10F.

The large hole portion 11HL is connected to the small hole portion 11HS midway in the thickness direction of the deposition mask 10. The central opening 11AC described above is located at the portion where the large hole portion 11HL is connected to the small hole portion 11HS. In a cross section perpendicular to the front surface 10F and perpendicular to the direction in which the through hole 11 extends, i.e., perpendicular to the long side direction, the distance between the back surface 10R and the central opening 11AC is the step height. The step height in the cross section along the line IIIa-IIIa is the first step height SH1, and the step height in the cross section along the line IIIb-IIIb is the second step height SH2.

As described above, the shape shown by the solid line in FIG. 3 is a cross-sectional shape along line IIIa-IIIa in FIG. 2. Line IIIa-IIIa is a straight line passing through valley portion 11L2 in the long side 11L of the front opening 11AF. Valley portion 11L2 is the portion of the front opening 11AF where etching of the metal plate to form the deposition mask 10 has progressed the least. In contrast, the shape shown by the two-dot chain line in FIG. 3 is a cross-sectional shape along line IIIb-IIIb in FIG. 2. Line IIIb-IIIb is a straight line passing through peak portion 11L1 in the long side 11L of the front opening 11AF. Peak portion 11L1 is the portion of the front opening 11AF where etching of the metal plate to form the deposition mask 10 has progressed the most.

Therefore, the first step height SH1 in the cross section along line IIIa-IIIa is larger than the second step height SH2 in the cross section along line IIIb-IIIb. Note that in the deposition mask 10, etching is more advanced in the cross section along line IIIb-IIIb than in the cross section along line IIIa-IIIa. Therefore, the second step height SH2 in the cross section along line IIIb-IIIb is smaller than the first step height SH1 in the cross section along line IIIa-IIIa.

Figure 4 shows the cross-sectional shape of the through hole 11 along the line IV-IV shown in Figure 2. That is, Figure 4 shows the cross-sectional shape of the deposition mask 10 along a plane parallel to the direction in which the long side 11L of the front opening 11AF extends.

As shown in FIG. 4, among the side surfaces 11AS that define the through-hole 11, the side surface 11HLS that defines the large hole portion 11HL has a wavy shape that includes waves that repeat along the direction in which the through-hole 11 extends, i.e., the long side direction. In other words, in the side surface 11HLS that defines the large hole portion 11HL, the wavy shape of the long side 11L of the front opening 11AF is maintained along the thickness direction of the deposition mask 10.

[Method of manufacturing deposition mask]
A method for manufacturing a deposition mask will be described with reference to FIGS.
The method for manufacturing the deposition mask 10 includes forming a resist layer on the metal plate, forming a resist mask, and forming a through hole. In forming the resist mask, the resist layer is exposed to light and the exposed resist layer is developed to form a resist mask. In forming the through hole, the metal plate is wet-etched using the resist mask to form a through hole in which a first opening is located on a first surface of the metal plate.

By forming the through holes, the first openings are formed so that they have a shape that extends in the first direction when viewed from a viewpoint facing the first surface, and the width in a direction intersecting the first direction narrows midway in the first direction, resulting in a constricted shape. The manufacturing method of the deposition mask 10 will be described in more detail below with reference to the drawings.

As shown in FIG. 5, when the deposition mask 10 is formed, first, a metal plate 10M for forming the deposition mask 10 is prepared. The metal plate 10M is formed, for example, from an iron-nickel alloy. The iron-nickel alloy can contain, for example, 36 mass% nickel. The iron-nickel alloy may be invar. The thickness of the metal plate 10M may be, for example, 1 μm or more and 50 μm or less, and is preferably 10 μm or more and 30 μm or less. This makes it easier to etch the metal plate to form the deposition mask 10. The metal plate 10M includes a front surface 10MF and a back surface 10MR facing the front surface 10MF.

A first resist layer 21F is formed on the front surface 10MF of the metal plate 10M, and a second resist layer 21R is formed on the rear surface 10MR of the metal plate 10M. Each resist layer 21F, 21R is formed, for example, from a negative resist material. Each resist layer 21F, 21R may be formed from a positive resist material. Each resist layer 21F, 21R is formed by attaching a dry film resist. The thickness of the dry film resist is preferably 5 μm or more and 20 μm or less.

Figure 6 shows the planar structure of the exposure mask used to expose the resist layers 21F and 21R. In addition, in Figure 6, the exposure mask used to expose the first resist layer 21F is shown by a solid line. In contrast, the exposure mask used to expose the second resist layer 21R is shown by a two-dot chain line. Also, Figure 6 shows the shape of the exposure mask when each resist layer 21F and 21R is formed from a negative resist material. Note that the exposure mask is a light-shielding pattern. The portion of the first resist layer 21F where the exposure mask is arranged is not exposed. Therefore, by developing the first resist layer 21F, an opening is formed in the portion of the first resist layer 21F where the exposure mask is arranged.

As shown in FIG. 6, the exposure mask 22F has a substantially rectangular shape. The exposure mask 22F has a pair of long sides 22FL and a pair of short sides 22FS. The exposure mask 22F has a plurality of slits 22FSL extending in a direction parallel to the short sides 22FS. In the example shown in FIG. 6, the exposure mask 22F has three recessed slits 22FSL in each long side 22FL. In each long side 22FL, the three slits 22FSL are arranged at positions that equally divide the long side 22FL. It is preferable that the pitch of the slits 22FSL in the long sides 22FL is substantially equal to the short sides 22FS.

In the exposure mask 22F, the length of the long side 22FL is the length LM of the exposure mask 22F. The length of the short side 22FS is the width WM of the exposure mask 22F. In the example shown in FIG. 6, the length LSL of each slit 22FSL is approximately 1/3 of the width WM of the exposure mask 22F. The width WSL of each slit 22FSL is shorter than the length LSL of the slit 22FSL. The width WSL of the slit 22FSL is shorter than the length of the portion of the long side 22FL of the exposure mask 22F that is located between the slits 22FSL. In the length LM of the exposure mask 22F, each length equally divided by the slits 22FSL is the unit length ULM. In each long side 22FL, the multiple slits 22FSL are arranged so as to equally divide the long side 22FL. The width WSL of the slits 22FSL is shorter than the unit length ULM.

A protrusion 22P is located at each corner of the exposure mask 22F. When an imaginary rectangle is set that passes through the long side 22FL and the short side 22FS of the exposure mask 22F, the protrusion 22P is a portion that protrudes outward from the corner of the rectangle. Each protrusion 22P has a substantially square shape.

The exposure mask 22R has a rectangular shape. The exposure mask 22R is smaller than the exposure mask 22F used to form openings in the first resist layer 21F.

As shown in FIG. 7, the resist layers 21F, 21R after exposure are developed to form resist masks 23F, 23R. A first resist mask 23F is formed on the front surface 10MF of the metal plate 10M by exposing and developing the first resist layer 21F. A second resist mask 23R is formed on the rear surface 10MR of the metal plate 10M by exposing and developing the second resist layer 21R.

The first resist mask 23F has a first mask hole 23FA. The first mask hole 23FA is a hole for forming the large hole portion 11HL in the through hole 11 of the deposition mask 10. The second resist mask 23R has a second mask hole 23RA. The second mask hole 23RA is a hole for forming the small hole portion 11HS in the through hole 11 of the deposition mask 10.

Figure 8 shows the planar structure of the first resist mask 23F as viewed from a viewpoint facing the front surface 10MF of the metal plate 10M. The planar structure of the second resist mask 23R as viewed from a viewpoint facing the rear surface 10MR of the metal plate 10M is not shown. As described above, the exposure mask 22R has a rectangular shape, and therefore the second resist mask 23R has a rectangular opening.

As shown in FIG. 8, in the step of forming the first resist mask 23F, as described above, a first resist mask 23F having a first mask hole 23FA for forming the through hole 11 in the metal plate 10M is formed. When viewed from a viewpoint facing the surface 10MF of the metal plate 10M, the first mask hole 23FA has a shape surrounded by a pair of opposing long sides 23FAL and a pair of opposing short sides 23FAS. The first mask hole 23FA has a shape substantially equal to the exposure mask 22F described above. The first mask hole 23FA has a substantially rectangular shape.

The first resist mask 23F has multiple protrusions 23FP. Each protrusion 23FP protrudes into the first mask hole 23FA along the direction from each long side 23FAL toward the other long side 23FAL.

The long side 23FAL of the first mask hole 23FA is divided by multiple protrusions 23FP. Therefore, compared to when the first resist mask 23F does not have the protrusions 23FP, the behavior of the etching solution is less likely to differ between the part of the metal plate 10M exposed at the short side 23FAS of the first mask hole 23FA and the part exposed at the long side 23FAL of the first mask hole 23FA. This prevents the part exposed from the long side 23FAL of the first mask hole 23FA from being excessively etched compared to the part exposed from the short side 23FAS of the first mask hole 23FA. As a result, it is possible to reduce the difference between the amount of etching in the long side direction and the amount of etching in the short side direction in the through hole of the metal plate 10M.

When the exposure mask 22F does not have slits 22FSL, the long side 23FAL of the first mask hole 23FA is not divided by multiple protrusions 23FP. In this case, the contact time of the etching solution near the long side 23FAL of the first mask hole 23FA is longer than the contact time of the etching solution near the short side 23FAS of the first mask hole 23FA. Therefore, the rate at which the metal plate 10M is etched near the long side 23FAL is higher than the rate at which the metal plate 10M is etched near the short side 23FAS. As a result, a difference occurs between the amount of etching in the long side direction and the amount of etching in the short side direction in the through hole of the metal plate 10M.

For each first mask hole 23FA, the first resist mask 23F has the same number of convex portions 23FP as the slits 22FSL of the exposure mask 22F. The first resist mask 23F has three convex portions 23FP originating from each long side 23FAL.

When viewed from a viewpoint facing the surface 10MF of the metal plate 10M, a protrusion 23FAP is located at each corner of the first mask hole 23FA. The protrusion 23FAP has substantially the same shape as the protrusion 22P of the exposure mask 22F. By having the first mask hole 23FAP, the corner of the surface opening 11AF is less likely to have an arc shape compared to when the first mask hole 23FA does not have the protrusion 23FAP. This makes it possible to reduce the amount of deviation in the shape of the corner of the surface opening 11AF from the shape of a rectangular corner.

As shown in FIG. 9, in the process of forming through holes 11 in metal plate 10M, first, metal plate 10M is etched from rear surface 10MR of metal plate 10M using second resist mask 23R. Before etching metal plate 10M, a first protective layer 24F is formed to cover front surface 10MF of metal plate 10M. This prevents front surface 10MF of metal plate 10M from being etched together with rear surface 10MR. By etching metal plate 10M from rear surface 10MR, small hole portion 10MS having a shape corresponding to second mask hole 23RA of second resist mask 23R is formed.

When the metal plate 10M is made of Invar, an etching solution capable of etching Invar, i.e., an acidic etching solution, can be used. The acidic etching solution may be, for example, a solution in which any of ferric chloride solution, ferric perchlorate solution, and a mixture of ferric perchlorate solution and ferric chloride solution is mixed with any of perchloric acid, hydrochloric acid, sulfuric acid, formic acid, and acetic acid. The method for etching the metal plate 10M may be any of a dip type, a spray type, and a spin type. The first protective layer 24F may be made of a material that is not etched by the etching solution.

As shown in FIG. 10, the metal plate 10M is etched from the front surface 10MF of the metal plate 10M using the first resist mask 23F. Before etching the metal plate 10M, the first protective layer 24F is removed from the first resist mask 23F. Also, before etching the metal plate 10M, the second resist mask 23R is removed. Next, a second protective layer 24R that covers the rear surface 10MR of the metal plate 10M is formed on the rear surface 10MR. This prevents the rear surface 10MR of the metal plate 10M from being etched together with the front surface 10MF.

The second resist mask 23R formed on the rear surface 10MR of the metal plate 10M does not need to be removed. In this case, the second protective layer 24R may be formed on the second resist mask 23R.

As shown in FIG. 11, the metal plate 10M is etched from the front surface 10MF to form a large hole portion 10ML having a shape corresponding to the first mask hole 23FA of the first resist mask 23F. The large hole portion 10ML is formed in a direction from the front surface 10MF of the metal plate 10M toward the back surface 10MR, and is connected to the small hole portion 10MS formed in the metal plate 10M.

When the metal plate 10M is made of Invar, an etching solution capable of etching Invar, i.e., an acidic etching solution, can be used, as in the case of etching the metal plate 10M from the rear surface 10MR. The acidic etching solution may be, for example, a solution in which either ferric chloride solution, ferric perchlorate solution, or a mixture of ferric perchlorate solution and ferric chloride solution is mixed with either perchloric acid, hydrochloric acid, sulfuric acid, formic acid, or acetic acid. The method for etching the metal plate 10M may be a dip type, a spray type, or a spin type. The second protective layer 24R may be made of a material that is not etched by the etching solution.

As shown in FIG. 12, the first resist mask 23F is removed from the front surface 10MF of the metal plate 10M. Also, the second protective layer 24R is removed from the rear surface 10MR of the metal plate 10M. A portion having a predetermined length is cut from the metal plate 10M to form the deposition mask 10.

The surface 10MF of the metal plate 10M corresponds to the surface 10F of the deposition mask 10. The back surface 10MR of the metal plate 10M corresponds to the back surface 10R of the deposition mask 10. The large hole portion 10ML of the metal plate 10M corresponds to the large hole portion 11HL of the through hole 11 of the deposition mask 10. The small hole portion 10MS of the metal plate 10M corresponds to the small hole portion 11HS of the through hole 11 of the deposition mask 10.

FIG. 13 shows the planar structure of the metal plate 10M as viewed from a viewpoint opposite to the front surface 10MF of the metal plate 10M.
13, the surface opening 11AF of the through hole 11 is located on the surface 10MF of the metal plate 10M. Each long side 11L of the surface opening 11AF has waves corresponding to the number of protrusions 23FP of the first resist mask 23F. When viewed from a viewpoint facing the surface 10MF of the metal plate 10M, the central opening 11AC is located within the area defined by the surface opening 11AF of the through hole 11. That is, when viewed from a viewpoint facing the surface 10MF of the metal plate 10M, the central opening 11AC is surrounded by the surface opening 11AF.

[Display Device Manufacturing Method]
A method for manufacturing the display device will be described with reference to FIG.
The manufacturing method of the display device includes preparing a deposition mask 10 by using the manufacturing method of the deposition mask 10 described above, and forming a deposition pattern on a deposition target by using the deposition mask 10. Hereinafter, a process of forming a deposition pattern will be described with reference to the drawings, along with an example of a deposition apparatus.

As shown in FIG. 14, the deposition device 30 includes a storage tank 31 that stores the deposition mask 10 and the deposition target S. The storage tank 31 is configured to hold the deposition target S and the deposition mask 10 at predetermined positions in the storage tank 31. In the storage tank 31, a holding unit 32 that holds the deposition material Mvd and a heating unit 33 that heats the deposition material Mvd are located. The deposition material Mvd held in the holding unit 32 is, for example, an organic light-emitting material. The storage tank 31 positions the deposition target S and the deposition mask 10 in the storage tank 31 such that the deposition mask 10 is located between the deposition target S and the holding unit 32 and the deposition mask 10 and the holding unit 32 face each other. The deposition mask 10 is placed in the storage tank 31 with the back surface 10R of the deposition mask 10 in close contact with the deposition target S.

In the process of forming the deposition pattern, the deposition material Mvd is heated by the heating unit 33, so that the deposition material Mvd is vaporized or sublimated. The vaporized or sublimated deposition material Mvd passes through the through-holes 11 of the deposition mask 10 and adheres to the deposition target S. As a result, for example, when the deposition material Mvd is an organic light-emitting material, an organic layer having a shape corresponding to the shape and position of the through-holes 11 of the deposition mask 10 is formed on the deposition target S. The deposition material Mvd may be a metal material for forming pixel electrodes of the pixel circuits of the display layer.

[Example]
Examples and Comparative Examples will be described with reference to Tables 1 and 2. Table 1 lists the dimensions of each part of the exposure mask used in the Examples and Comparative Examples. Table 2 lists the evaluation results of the deposition masks of the Examples and Comparative Examples. In the Examples and Comparative Examples described below, a single-wafer etching apparatus was used to etch the metal plate.

[Example 1]
A metal plate was prepared that was made of an iron-nickel alloy containing 36 mass% nickel, had a thickness of 25 μm, and had a square shape with a side length of 100 mm. Then, a dry film resist made of a negative resist material was attached to each side of the metal plate to form a resist layer having a thickness of 15 μm on both sides of the metal plate.

Then, the first resist layer was exposed using an exposure mask having the shape described above with reference to FIG. 6. The exposed resist layer was developed to form a first resist mask. In the exposure mask, the length LM was set to 147.9 μm, the width WM was set to 55.4 μm, the length LSL of the slit 22FSL was set to 16.3 μm, the width WSL of the slit 22FSL was set to 8.7 μm, and the unit length ULM was set to 37.0 μm.

The protrusions of the exposure mask were designed in the following way. That is, in the exposure mask, the above-mentioned virtual rectangle was set, and a square was arranged so that its center of gravity was located at a corner of the rectangle. In this case, the length of one side of the square was set to 16 μm, and the square was arranged so that the angle formed between the long side of the virtual rectangle and one side of the square that intersects with the long side was 45°. When exposing the first resist layer, multiple exposure masks were arranged on the first resist layer so that the multiple exposure masks were located at each lattice point of the lattice array.

In addition, an exposure mask having a length of 130.7 μm and a width of 30.3 μm was prepared as an exposure mask for exposing the second resist layer. The second resist layer was exposed using the exposure mask and developed to form a second resist mask.

Then, the metal plate was etched using the second resist mask. During this process, the time that the back surface of the metal plate was in contact with the etching solution of the single-wafer etching device was set to 1 minute 30 seconds. In addition, ferric chloride solution was used as the etching solution, and the temperature of the etching solution was set to 50°C. This resulted in the formation of small holes in the metal plate.

Then, the metal plate was etched using the first resist mask. At this time, the time that the surface of the metal plate was in contact with the etching solution of the single-wafer etching apparatus was set to 3 minutes 40 seconds. Other than that, the same conditions were set as for etching the metal plate using the second resist mask, and the metal plate was etched using the first resist mask. In this way, a large hole portion was formed in the metal plate, and the deposition mask of Example 1 with a through hole was obtained.

[Example 2]
A metal plate of Example 2 was obtained in the same manner as in Example 1, except that the slit length LSL in Example 1 was set to 12.0 μm.

[Example 3]
The metal plate of Example 3 was obtained in the same manner as in Example 1, except that the time during which the surface of the metal plate was in contact with the etching solution of the single-wafer etching apparatus was set to 4 minutes and 10 seconds when etching the metal plate.

[Comparative Example 1]
A metal plate of Comparative Example 1 was obtained in the same manner as in Example 1, except that the length LM of the exposure mask was set to 148.0 μm, the width WM was set to 53.5 μm, and the exposure mask did not have a slit.

[evaluation]
In each of Examples 1 to 3 and Comparative Example 1, the step height in the through hole was measured. The step height was measured in a portion of a plane parallel to the short side and corresponding to a cross section including the first valley portion, the second valley portion, and the third valley portion. The first valley portion, the second valley portion, and the third valley portion were arranged in the order listed along the long side of the surface opening. The step height was measured in a portion of a plane parallel to the short side and corresponding to a cross section including the first peak portion and the second peak portion. The first peak portion was a portion sandwiched between the first valley portion and the second valley portion in the direction in which the long side extends. The second peak portion was a portion sandwiched between the second valley portion and the third valley portion in the direction in which the long side extends. The step height was also measured in a portion corresponding to a cross section along a plane parallel to the long side. A scanning electron microscope (U3500 type, manufactured by Hitachi High-Tech Corporation) was used to measure the step height. The results of measuring the step height are shown in Table 2 below. In the deposition mask of Comparative Example 1, the long side of the front surface opening does not have a valley portion or a peak portion. Therefore, in Comparative Example 1, the step height was measured in a portion equivalent to the portion where each peak portion and each valley portion are located in the deposition mask of each example.

As shown in Table 2, in Example 1, the average step height in a cross section along a plane parallel to the short side was found to be 2.54. In addition, the difference between the step height in a cross section along a plane parallel to the long side and the step height in a cross section along a plane parallel to the short side was found to have a minimum of 0.22 and a maximum of 1.07.

In Example 2, the average step height in a cross section along a plane parallel to the short side was found to be 0.89. In addition, the difference between the step height in a cross section along a plane parallel to the long side and the step height in a cross section along a plane parallel to the short side was found to have a minimum of 1.91 and a maximum of 2.45.

In Example 3, the average step height in a cross section along a plane parallel to the short side was found to be 2.03. In addition, the difference between the step height in a cross section along a plane parallel to the long side and the step height in a cross section along a plane parallel to the short side was found to have a minimum of 0.21 and a maximum of 1.37.

In Comparative Example 1, the average value of the step height in the cross section along the plane parallel to the short side was found to be 0.65. The minimum difference between the step height in the cross section along the plane parallel to the long side and the step height in the cross section along the plane parallel to the short side was found to be 2.52 and the maximum difference was found to be 2.54. Thus, with the metal plates of Examples 1 to 3, the maximum difference between the step height in the cross section along the plane parallel to the long side and the step height in the cross section along the plane parallel to the short side was found to be smaller than the difference in step height in the metal plate of Comparative Example 1. In other words, with the metal plates of Examples 1 to 3, it was found that the difference between the amount of etching in the long side direction and the amount of etching in the short side direction of the through hole was suppressed.

As described above, according to the embodiment of the deposition mask, the method for manufacturing a deposition mask, and the method for manufacturing a display device, the following effects can be obtained.
(1) Since the front opening 11AF has a constricted shape, the flow of the etching solution for forming the through hole 11 is interrupted at the constricted portion. As a result, it is possible to reduce the difference between the amount of etching that widens the through hole 11 in the long axis direction, which is the first direction, and the amount of etching that widens the through hole 11 in the short axis direction, compared to a configuration in which the front opening 11AF does not have a constriction.

(2) Because each long side 11L has a wavy shape, when forming the through-hole 11 using a resist mask in the metal plate 10M for forming the deposition mask 10, it is possible to use a first resist mask 23F that is configured to divide the long side 23FAL of the first mask hole 23FA of the first resist mask 23F into the same number of waves as the long side 11L of the through-hole 11.

As a result, when etching the metal plate 10M, the area through which the etching solution flows is divided on the long side 23FAL of the first mask hole 23FA into the same number of waves as the long side 11L of the through hole 11. As a result, when viewed from the etching solution supplied to the first mask hole 23FA, the difference in length between the divided portion of the long side 23FAL and the short side 23FAS in the first mask hole 23FA is small, so it is possible to reduce the difference between the behavior of the etching solution in the long side direction and the short side direction. As a result, it is possible to reduce the difference between the amount of etching that expands the through hole 11 in the long side direction and the amount of etching that expands the through hole 11 in the short side direction.

(3) In etching the metal plate 10M to form the deposition mask 10, it is possible to use a first resist mask 23F configured to divide the long side 23FAL of the first mask hole 23FA to a length approximately equal to the short side 23FAS of the first mask hole 23FA. As a result, when viewed from the etching solution supplied to the first mask hole 23FA, the length between the divided portion of the long side 23FAL and the short side 23FAS in the first mask hole 23FA is approximately equal, so that the behavior of the etching solution in the long side direction and the behavior of the etching solution in the short side direction are approximately equal. As a result, it is possible to further reduce the difference between the amount of etching that widens the through hole 11 in the long side direction and the amount of etching that widens the through hole 11 in the short side direction.

(4) It is preferable that the length of each short side 11S is 0.6 to 1.4 times the wave period of the long side 11L.

(5) In the thickness direction of the deposition mask 10, in the region from the surface opening 11AF to the central opening 11AC, it is possible to reduce the difference between the amount of etching in the long side direction and the amount of etching in the short side direction of the through hole 11.

(6) The long side 23FAL of the first mask hole 23FA is divided by multiple protrusions 23FP. Therefore, compared to when the first resist mask 23F does not have the protrusions 23FP, the behavior of the etching solution is less likely to differ between the part of the metal plate 10M exposed at the short side 23FAS of the first mask hole 23FA and the part exposed at the long side 23FAL of the first mask hole 23FA. This prevents the part exposed from the long side 23FAL of the first mask hole 23FA from being excessively etched compared to the part exposed from the short side 23FAS of the first mask hole 23FA. As a result, it is possible to reduce the difference between the amount of etching in the long side direction and the amount of etching in the short side direction in the through hole of the metal plate 10M.

The above-described embodiment can be modified as follows.
[Surface opening]
As described above, the surface opening 11AF has a shape extending in the first direction when viewed from a viewpoint facing the surface 10F, and is narrowed so that the width in the direction intersecting the first direction is narrowed halfway in the first direction. Therefore, the surface opening 11AF may have a shape other than the shape defined by a pair of long sides 11L and a pair of short sides 11S as described above with reference to FIG. 2. For example, the surface opening 11AF may have a shape in which two circles are connected at a part of each circle when viewed from a viewpoint facing the surface 10F. Note that, when viewed from a viewpoint facing the surface 10F, the narrowed portion of the surface opening 11AF is a portion in which the width in the direction intersecting the first direction has a minimum value in the first direction. In other words, the width in the direction intersecting the first direction at the narrowed portion is smaller than the width in the direction intersecting the first direction at the portion sandwiching the narrowed portion in the first direction.

[Metal plate]
The material forming the metal plate 10M is not limited to Invar, and may be, for example, the following materials. That is, the material forming the metal plate 10M may be an alloy containing 30 mass% or more of nickel and the remainder of iron. The alloy may contain additives in addition to iron and nickel. The additives may be chromium, manganese, carbon, cobalt, or the like. The metal plate 10M may be formed from an iron-nickel-cobalt based alloy. The iron-nickel-cobalt based alloy may contain, for example, 30 mass% or more of nickel, 3 mass% or more of cobalt, and the remainder of iron. The iron-nickel-cobalt based alloy may contain additives in addition to iron, nickel, and cobalt. The additives may include, for example, additives such as chromium, manganese, and carbon. The iron-nickel-cobalt based alloy may be an alloy containing 32 mass% of nickel, 4 mass% to 5 mass% of cobalt, and the remainder of iron, that is, Super Invar.

[Resist layer]
Each resist layer 21F, 21R may be formed by applying a coating liquid for forming the resist layer 21F, 21R. For example, when the thickness of the metal plate 10M is 10 μm or less, it is preferable to form the resist layer 21F, 21R by coating. Also, for example, when the thickness of the metal plate 10M is 5 μm or less, it is preferable to form the resist layer 21F, 21R having a thickness of 1 μm or less by coating.

[Method of manufacturing deposition mask]
The through-holes 11 of the deposition mask 10 may be formed by only etching the metal plate 10M from the front surface 10MF of the metal plate 10M. In this case, the thickness of the metal plate 10M is preferably 15 μm or less, more preferably 10 μm or less. In this case, the through-holes 11 extend from the front surface opening 11AF to the rear surface opening 11AR, and have a shape that tapers from the front surface opening 11AF toward the rear surface opening 11AR. When the metal plate 10M is etched only from the front surface 10MF, the difference between the amount of etching in the short side direction and the amount of etching in the long side direction can be reduced by etching the metal plate 10M using the first resist mask 23F described with reference to FIG. 8. This makes it possible to increase the straightness of the long side 11L of the front surface opening 11AF when viewed from a viewpoint facing the front surface 10F of the deposition mask 10.

Reference Signs List 10: deposition mask 10F: front surface 10R: rear surface 10M: metal plate 11: through hole 11AC: central opening 11AF: front surface opening 11AR: rear surface opening 11L: long side 11S: short side 23F: first resist mask 23FA: first mask hole 23FAL: long side 23FAS: short side 23FP: protruding portion

Claims (8)

A deposition mask for forming a plurality of sub-pixels of a display pixel, the sub-pixels including a first surface, the deposition mask comprising:
a through hole in which a first opening is located on the first surface, the through hole being for forming one deposition pattern corresponding to one of the sub-pixels on a deposition target ;
the first opening has a shape extending in a first direction when seen from a viewpoint facing the first surface, and is constricted so that a width in a direction intersecting the first direction narrows midway in the first direction. the first opening has a shape surrounded by a pair of opposing long sides and a pair of opposing short sides when viewed from a viewpoint opposite to the first surface,
When viewed from a viewpoint opposite to the first surface,
Each short side has a straight or arc shape;
The deposition mask according to claim 1 , wherein at least one of the long sides has a wavy shape that increases or decreases a distance between the pair of long sides along an extension direction of the long side. When viewed from a viewpoint opposite to the first surface, each long side includes a plurality of waves;
The deposition mask according to claim 2 , wherein the length of each of the short sides is 0.6 to 1.4 times the wave period of the long sides. a second surface opposed to the first surface;
a second opening of the through hole is located on the second surface, and when viewed from a viewpoint facing the first surface, the second opening is located within a region surrounded by the first opening;
a third opening of the through hole is located between the first opening and the second opening in a thickness direction of the deposition mask, and when viewed from a viewpoint facing the first surface, the third opening is located within a region surrounded by the second opening,
the third opening has a shape surrounded by a pair of opposing long sides and a pair of opposing short sides when viewed from a viewpoint opposite to the first surface,
When viewed from a viewpoint opposite to the first surface,
each short side of the third opening has the same shape as a short side of the first opening;
The deposition mask according to claim 2 , wherein at least one long side of the third opening has a wavy shape that increases or decreases a distance between a pair of long sides of the third opening along an extension direction of the long side of the third opening. A method for manufacturing a deposition mask for forming a sub-pixel of a display pixel including a plurality of sub-pixels, the method comprising the steps of:
forming a resist layer on a metal plate;
exposing the resist layer to light and developing the exposed resist layer to form a resist mask; and
wet-etching the metal plate using the resist mask to form a through-hole in which a first opening is located on a first surface of the metal plate, the through-hole being for forming one deposition pattern corresponding to one of the sub-pixels on a deposition target ,
The through hole is formed so that the first opening has a shape that extends in a first direction when viewed from a viewpoint facing the first surface, and the first opening is formed so that a width of the first opening in a direction intersecting the first direction narrows midway in the first direction. When viewed from a viewpoint opposite to the first surface, the first opening has
A pair of long sides facing each other;
The shape is bounded by a pair of short sides opposed to each other,
Each short side has a straight or arcuate shape;
The method for manufacturing a deposition mask according to claim 5 , wherein at least one of the long sides has a wavy shape that increases or decreases a distance between the pair of long sides along an extension direction of the long side. forming the resist mask includes forming the resist mask having a mask hole for forming the through hole of the metal plate;
the mask hole has a shape surrounded by a pair of opposing long sides and a pair of opposing short sides when viewed from a viewpoint facing the first surface,
The method for manufacturing a deposition mask according to claim 6 , wherein the resist mask has a plurality of protrusions protruding into the mask holes along a direction from each long side toward the other long side. Preparing a deposition mask by using the deposition mask manufacturing method according to any one of claims 5 to 7 ; and
forming a deposition pattern on a deposition target using the deposition mask.