JP7104902B2 - Method for manufacturing vapor deposition mask, and method for manufacturing metal plate used for manufacturing vapor deposition mask - Google Patents

Description

The present invention relates to a method for manufacturing a vapor deposition mask. The present invention also relates to a method for manufacturing a metal plate used for manufacturing a vapor deposition mask.

In recent years, display devices used in portable devices such as smartphones and tablet PCs are required to have high definition, for example, a pixel density of 400 ppi or more. Also, there is an increasing demand for portable devices to support ultra-full high-definition, and in this case, display devices are required to have a pixel density of, for example, 800 ppi or more.

Among display devices, an organic EL display device has attracted attention because of its good responsiveness, low power consumption, and high contrast. As a method of forming pixels of an organic EL display device, a method of forming pixels in a desired pattern using a vapor deposition mask having through holes arranged in a desired pattern is known. Specifically, first, a vapor deposition mask is brought into close contact with a substrate for an organic EL display device, and then the closely adhered vapor deposition mask and substrate are put into a vapor deposition apparatus, and an organic material is vapor-deposited onto the substrate. I do. Accordingly, pixels containing an organic material can be formed on the substrate in a pattern corresponding to the pattern of the through holes of the vapor deposition mask.

As a method for manufacturing a vapor deposition mask, for example, a method of forming through-holes in a metal plate by etching using a photolithographic technique is known, as disclosed in Patent Document 1. For example, first, a first resist pattern is formed on the first surface of the metal plate by exposure and development, and a second resist pattern is formed on the second surface of the metal plate by exposure and development. Next, a region of the first surface of the metal plate that is not covered with the first resist pattern is etched to form a first opening in the first surface of the metal plate. After that, the area of the second surface of the metal plate that is not covered with the second resist pattern is etched to form a second opening in the second surface of the metal plate. At this time, by performing etching so that the first opening and the second opening communicate with each other, a through hole penetrating the metal plate can be formed. A metal plate for producing a vapor deposition mask is produced, for example, by rolling a base material made of an iron alloy containing nickel.

Japanese Patent No. 5382259

As a result of extensive research, the inventors of the present invention have found that many inclusions are present in the surface layer of the rolled metal plate. In addition, the inventors of the present invention conducted extensive research and found that when through holes are formed in a metal plate by etching a metal plate having many inclusions in the surface layer, the shape of the through holes tends to vary. I found If the shape of the through-holes varies, the dimensional accuracy and positional accuracy of the vapor deposition material that adheres to the substrate through the through-holes will be degraded.

An object of the present invention is to provide a vapor deposition mask manufacturing method that can effectively solve such problems.

The present invention is a method for manufacturing a metal plate used for manufacturing a vapor deposition mask by forming a plurality of through holes, wherein a base material made of an iron alloy containing nickel is rolled to form a first surface and a second surface. A method for manufacturing a metal plate, comprising: a rolling step of producing a metal plate including a surface; and a surface layer removing step of removing a surface layer of at least the first surface side of the metal plate.

In the method for manufacturing a metal plate according to the present invention, the surface layer removing step may remove the surface layer within a range of 0.5 μm or more and 20 μm or less in the thickness direction of the metal plate.

In the method for manufacturing a metal plate according to the present invention, the surface layer removing step may include a wet etching step of bringing an etchant into contact with at least the first surface of the metal plate.

In the method for manufacturing a metal plate according to the present invention, the wet etching step may include a spraying step of spraying the etchant toward the first surface of the metal plate with the first surface facing downward. good.

In the method for manufacturing a metal plate according to the present invention, the surface layer removing step may include removing the surface layer on the first surface side and removing the surface layer on the second surface side. .

In the method for manufacturing a metal plate according to the present invention, the thickness of the metal plate after the surface layer is removed in the surface layer removing step may be 5 μm or more and 50 μm or less.

The present invention is a method for manufacturing a vapor deposition mask having a plurality of through holes, the first surface being made of an iron alloy containing nickel and positioned on the side of the substrate to which the vapor deposition material passing through the through holes adheres; and a second surface located opposite to the first surface; a surface layer removing step of removing at least a surface layer of the metal plate on the side of the first surface; and a processing step of etching a metal plate to form the through holes in the metal plate.

In the method for manufacturing a vapor deposition mask according to the present invention, in the preparation step, the metal plate may be produced by rolling a base material made of an iron alloy containing nickel.

In the method for manufacturing a vapor deposition mask according to the present invention, the surface layer removing step may remove the surface layer within a range of 0.5 μm or more and 20 μm or less in the thickness direction of the metal plate.

In the method of manufacturing a vapor deposition mask according to the present invention, the surface layer removing step may include a wet etching step of bringing an etchant into contact with at least the first surface of the metal plate.

In the method for manufacturing a vapor deposition mask according to the present invention, the wet etching step may include a spraying step of spraying the etchant toward the first surface of the metal plate with the first surface facing downward. good.

In the method for manufacturing a vapor deposition mask according to the present invention, the surface layer removing step may include removing the surface layer on the first surface side and removing the surface layer on the second surface side. .

In the vapor deposition mask manufacturing method according to the present invention, the thickness of the metal plate after the surface layer is removed in the surface layer removing step may be 5 μm or more and 50 μm or less.

According to the present invention, it is possible to manufacture a vapor deposition mask with small variations in the shape of through holes.

1 illustrates a vapor deposition apparatus having a vapor deposition mask device according to an embodiment of the present invention; FIG. 2 is a cross-sectional view showing an organic EL display device manufactured using the vapor deposition mask device shown in FIG. 1; FIG. 1 is a plan view showing a vapor deposition mask device according to an embodiment of the present invention; FIG. FIG. 4 is a partial plan view showing the effective area of the vapor deposition mask shown in FIG. 3; FIG. 5 is a cross-sectional view taken along line VV of FIG. 4; FIG. 5 is a cross-sectional view taken along line VI-VI of FIG. 4; FIG. 5 is a cross-sectional view taken along line VII-VII of FIG. 4; 6 is an enlarged cross-sectional view showing the through hole shown in FIG. 5 and a region in the vicinity thereof; FIG. It is a figure which shows the process of rolling a base material and obtaining a metal plate which has desired thickness. It is a figure which shows the process of annealing the metal plate obtained by rolling. FIG. 4 is a cross-sectional view showing inclusions in the surface layer of the metal plate obtained by rolling. 12 is a cross-sectional view showing a step of etching the metal plate shown in FIG. 11 from the first surface side to form a first concave portion; FIG. 13 is a cross-sectional view showing a step of further advancing etching from the state shown in FIG. 12 to enlarge the first concave portion; FIG. FIG. 4 is a cross-sectional view showing an example of a vapor deposition mask manufactured using a metal plate having many inclusions in the surface layer; It is a schematic diagram for demonstrating an example of the manufacturing method of a vapor deposition mask as a whole. It is a figure which shows the process of removing the surface layer of a metal plate. It is a figure which shows the metal plate from which the surface layer was removed. It is a figure which shows the process of forming a resist film on a metal plate. It is a figure which shows the process of making an exposure mask contact|adhere to a resist film. It is a figure which shows the process of developing a resist film. It is a figure which shows a 1st surface etching process. It is a figure which shows the process of coat|covering a 1st recessed part with resin. It is a figure which shows a 2nd surface etching process. FIG. 24 is a diagram showing a second surface etching step following FIG. 23; It is a figure which shows the process of removing resin and a resist pattern from a metal plate. It is a figure which shows the example of a changed completely type of the process of removing the surface layer of a metal plate.

An embodiment of the present invention will be described below with reference to the drawings. In the drawings attached to this specification, for the convenience of illustration and ease of understanding, the scale and the ratio of vertical and horizontal dimensions are changed and exaggerated from those of the real thing.

1 to 23 are diagrams for explaining an embodiment of the present invention. In the following embodiments and modifications thereof, a method of manufacturing a vapor deposition mask used for patterning an organic material on a substrate in a desired pattern when manufacturing an organic EL display device will be described as an example.
However, the present invention can be applied to vapor deposition masks used for various purposes without being limited to such applications.

In this specification, the terms "plate", "sheet" and "film" are not to be distinguished from each other based only on the difference of names. For example, "plate" is a concept that includes members that can be called sheets and films.

In addition, "plate surface (sheet surface, film surface)" refers to the target plate-shaped member (sheet-shaped member) when viewed from the whole and perspective. member, film-like member). Further, the normal direction used for a plate-like (sheet-like, film-like) member refers to the normal direction to the plate surface (sheet surface, film surface) of the member.

In addition, terms such as "parallel", "perpendicular", "identical", "equivalent", etc., and lengths and angles are used herein to specify shapes and geometric conditions and physical properties and degrees thereof. In addition, the values of physical properties are not bound by strict meanings, and should be interpreted to include the range in which similar functions can be expected.

(Vapor deposition equipment)
First, a vapor deposition apparatus 90 that performs a vapor deposition process for vapor-depositing a vapor deposition material on an object will be described with reference to FIG. As shown in FIG. 1, the vapor deposition device 90 includes a vapor deposition source (for example, a crucible 94), a heater 96, and a vapor deposition mask device 10 therein. In addition, the vapor deposition device 90 further includes exhaust means for creating a vacuum atmosphere inside the vapor deposition device 90 . Crucible 94 contains deposition material 98, such as an organic light emitting material. A heater 96 heats the crucible 94 to evaporate the deposition material 98 under a vacuum atmosphere. The vapor deposition mask device 10 is arranged to face the crucible 94 .

(Evaporation mask device)
The vapor deposition mask device 10 will be described below. As shown in FIG. 1 , the vapor deposition mask device 10 includes a vapor deposition mask 20 and a frame 15 that supports the vapor deposition mask 20 . The frame 15 supports the vapor deposition mask 20 while pulling it in its surface direction so that the vapor deposition mask 20 does not bend. As shown in FIG. 1, the vapor deposition mask device 10 is arranged in the vapor deposition device 90 so that the vapor deposition mask 20 faces a substrate, for example, an organic EL substrate 92, which is an object on which the vapor deposition material 98 is deposited. In the following description, of the surfaces of the vapor deposition mask 20, the surface on the side of the organic EL substrate 92 is referred to as a first surface 20a, and the surface located on the opposite side of the first surface 20a is referred to as a second surface 20b.

The vapor deposition mask device 10 may include a magnet 93 arranged on the surface of the organic EL substrate 92 opposite to the vapor deposition mask 20, as shown in FIG. By providing the magnet 93 , the vapor deposition mask 20 can be attracted to the magnet 93 side by magnetic force, and the vapor deposition mask 20 can be brought into close contact with the organic EL substrate 92 .

FIG. 3 is a plan view showing the vapor deposition mask device 10 viewed from the side of the first surface 20a of the vapor deposition mask 20. As shown in FIG. As shown in FIG. 3 , the vapor deposition mask device 10 has a plurality of vapor deposition masks 20 . Each vapor deposition mask 20 includes a pair of long sides 26 and a pair of short sides 27 and has, for example, a rectangular shape. Each vapor deposition mask 20 is fixed to the frame 15 by spot welding, for example, at a pair of short sides 27 or a portion in the vicinity thereof.

The vapor deposition mask 20 includes a metal plate-like base material in which a plurality of through holes 25 are formed to penetrate the vapor deposition mask 20 . A vapor deposition material 98 that has evaporated from the crucible 94 and reached the vapor deposition mask device 10 passes through the through holes 25 of the vapor deposition mask 20 and adheres to the organic EL substrate 92 . As a result, the vapor deposition material 98 can be deposited on the surface of the organic EL substrate 92 in a desired pattern corresponding to the positions of the through holes 25 of the vapor deposition mask 20 .

FIG. 2 is a cross-sectional view showing an organic EL display device 100 manufactured using the vapor deposition apparatus 90 of FIG. The organic EL display device 100 includes an organic EL substrate 92 and pixels including a vapor deposition material 98 provided in a pattern.

If color display is desired using a plurality of colors, vapor deposition apparatuses 90 each having a vapor deposition mask 20 corresponding to each color are prepared, and the organic EL substrates 92 are loaded into the respective vapor deposition apparatuses 90 in order. As a result, for example, an organic light-emitting material for red, an organic light-emitting material for green, and an organic light-emitting material for blue can be vapor-deposited on the organic EL substrate 92 in order.

By the way, the vapor deposition process may be performed inside the vapor deposition apparatus 90 in a high-temperature atmosphere. In this case, during the vapor deposition process, the vapor deposition mask 20, the frame 15 and the organic EL substrate 92 held inside the vapor deposition device 90 are also heated. At this time, the vapor deposition mask 20, the frame 15 and the organic EL substrate 92 exhibit dimensional change behavior based on their thermal expansion coefficients.
In this case, if the vapor deposition mask 20 or the frame 15 and the organic EL substrate 92 have significantly different coefficients of thermal expansion, a positional shift occurs due to the difference in dimensional change between them, and as a result, the organic EL substrate 92 adheres to the organic EL substrate 92 . The dimensional accuracy and positional accuracy of the vapor deposition material are degraded.

In order to solve such problems, it is preferable that the thermal expansion coefficients of the vapor deposition mask 20 and the frame 15 are equal to the thermal expansion coefficient of the organic EL substrate 92 . For example, when a glass substrate is used as the organic EL substrate 92, an iron alloy containing nickel can be used as the main material of the vapor deposition mask 20 and the frame 15. FIG. For example, an iron alloy containing 30% by mass or more and 54% by mass or less of nickel can be used as the material of the base material that constitutes the vapor deposition mask 20 . Specific examples of nickel-containing iron alloys include an Invar material containing 34% by mass or more and 38% by mass or less of nickel, a Super Invar material containing cobalt in addition to 30% by mass or more and 34% by mass or less of nickel, 38 A low thermal expansion Fe—Ni plating alloy containing nickel in an amount of 54% by mass or more and 54% by mass or more can be mentioned.

If the temperatures of the vapor deposition mask 20, the frame 15 and the organic EL substrate 92 do not reach a high temperature during the vapor deposition process, the thermal expansion coefficients of the vapor deposition mask 20 and the frame 15 are used as the thermal expansion coefficients of the organic EL substrate 92. It doesn't have to be the same value. In this case, a material other than the iron alloy described above may be used as the material forming the vapor deposition mask 20 . For example, iron alloys other than the above nickel-containing iron alloys, such as chromium-containing iron alloys, may be used. As an iron alloy containing chromium, for example, an iron alloy called so-called stainless steel can be used. Alloys other than iron alloys, such as nickel and nickel-cobalt alloys, may also be used.

(Evaporation mask)
Next, the vapor deposition mask 20 will be described in detail. As shown in FIG. 3, the deposition mask 20 has a pair of ears (first ear 17a and second ear 17b) including a pair of short sides 27 of the deposition mask 20, and a pair of ears 17a and 17b. and an intermediate portion 18 located therebetween.

(Ear)
First, the ear portions 17a and 17b will be described in detail. The ear portions 17 a and 17 b are portions of the vapor deposition mask 20 that are fixed to the frame 15 . In this embodiment, the ear portions 17a and 17b are integrally formed with the intermediate portion 18. As shown in FIG. Note that the ear portions 17 a and 17 b may be configured by a member different from the intermediate portion 18 . In this case, the ears 17a, 17b are joined to the intermediate portion 18, for example by welding.

(middle part)
Next, the intermediate portion 18 will be described. The intermediate portion 18 includes at least one effective area 22 formed with a through hole 25 extending from the first surface 20a to the second surface 20b, and a peripheral area 23 surrounding the effective area 22. As shown in FIG. The effective area 22 is the area of the vapor deposition mask 20 that faces the display area of the organic EL substrate 92 .

In the example shown in FIG. 3, the intermediate portion 18 includes a plurality of effective areas 22 arranged at predetermined intervals along the long sides 26 of the vapor deposition mask 20 . One effective area 22 corresponds to one display area of the organic EL display device 100 . Therefore, according to the vapor deposition mask device 10 shown in FIG. 1, multi-surface vapor deposition of the organic EL display device 100 is possible. Note that one effective area 22 may correspond to a plurality of display areas.

As shown in FIG. 3, the effective area 22 has, for example, a substantially rectangular contour in plan view, or more precisely, a substantially rectangular contour in plan view. Although not shown, each effective area 22 can have contours of various shapes according to the shape of the display area of the organic EL substrate 92 . For example, each active area 22 may have a circular contour.

The effective area 22 will be described in detail below. FIG. 4 is a plan view showing an enlarged effective region 22 from the second surface 20b side of the vapor deposition mask 20. As shown in FIG. As shown in FIG. 4, in the illustrated example, the plurality of through-holes 25 formed in each effective area 22 are arranged at a predetermined pitch along two mutually orthogonal directions in the effective area 22. there is An example of the through hole 25 will be described in further detail mainly with reference to FIGS. 5 to 7. FIG. 5 to 7 are cross-sectional views of the effective area 22 of FIG. 4 along the VV to VII-VII directions, respectively.

As shown in FIGS. 5 to 7, the plurality of through holes 25 are formed along the normal direction N of the vapor deposition mask 20 from the first surface 20a, which is one side along the normal direction N of the vapor deposition mask 20. It penetrates to the second surface 20b on the other side. In the illustrated example, the first recess 30 is formed by etching in the first surface 21a of the substrate 21, which is one side of the vapor deposition mask 20 in the normal direction N, as will be described in detail later. A second concave portion 35 is formed on the second surface 21b of the base material 21, which is the other side in the normal direction N. As shown in FIG. The first recess 30 is connected to the second recess 35 so that the second recess 35 and the first recess 30 communicate with each other. The through hole 25 is composed of a second recess 35 and a first recess 30 connected to the second recess 35 .

As shown in FIGS. 5 to 7, from the second surface 20b side of the vapor deposition mask 20 toward the first surface 20a side, the plate of the vapor deposition mask 20 at each position along the normal direction N of the vapor deposition mask 20 The opening area of each second concave portion 35 in the cross section along the surface gradually decreases. Similarly, the opening area of each first concave portion 30 in the cross section along the plate surface of the vapor deposition mask 20 at each position along the normal direction N of the vapor deposition mask 20 is It gradually becomes smaller toward the second surface 20b side.

As shown in FIGS. 5 to 7, the wall surface 31 of the first recess 30 and the wall surface 36 of the second recess 35 are connected via a circumferential connecting portion 41. As shown in FIGS. In the connecting portion 41, the wall surface 31 of the first concave portion 30 inclined with respect to the normal direction N of the vapor deposition mask 20 and the wall surface 36 of the second concave portion 35 inclined with respect to the normal direction N of the vapor deposition mask 20 join. defined by the ridges of the overhanging portion.
The connecting portion 41 defines a penetrating portion 42 in which the opening area of the through hole 25 is minimized in plan view of the vapor deposition mask 20 .

As shown in FIGS. 5 to 7, on the other side of the vapor deposition mask 20 along the normal direction N, that is, on the first surface 20a of the vapor deposition mask 20, two adjacent through holes 25 are formed by vapor deposition. They are spaced apart from each other along the plate surface of the mask 20 . That is, as in the manufacturing method to be described later, when the base material 21 is etched from the side of the first surface 21a of the base material 21 corresponding to the first surface 20a of the vapor deposition mask 20 to form the first concave portion 30. , the first surface 21a of the substrate 21 remains between two adjacent first recesses 30. As shown in FIG.

Similarly, as shown in FIGS. 5 and 7, on one side of the vapor deposition mask 20 along the normal direction N, that is, on the side of the second surface 20b of the vapor deposition mask 20, two adjacent second concave portions 35 may be spaced apart from each other along the plate surface of the vapor deposition mask 20 . That is, the second surface 21b of the base material 21 may remain between two adjacent second recesses 35 . In the following description, the portion of the effective region 22 of the second surface 21b of the base material 21 that remains without being etched is also referred to as a top portion 43. As shown in FIG. By fabricating the vapor deposition mask 20 so that such a top portion 43 remains, the vapor deposition mask 20 can be given sufficient strength. As a result, it is possible to prevent the vapor deposition mask 20 from being damaged during transportation, for example. If the width β of the top portion 43 is too large, shadows may occur in the vapor deposition process, which may reduce the utilization efficiency of the vapor deposition material 98 . Therefore, the vapor deposition mask 20 is preferably manufactured so that the width β of the top portion 43 does not become excessively large. For example, it is preferable that the width β of the top portion 43 is 2 μm or less. Note that the width β of the top portion 43 generally changes according to the direction in which the vapor deposition mask 20 is cut. For example, the width β of the top portion 43 shown in FIGS. 5 and 7 may differ from each other. In this case, the vapor deposition mask 20 may be configured such that the width β of the top portion 43 is 2 μm or less when the vapor deposition mask 20 is cut in any direction.

In addition, as shown in FIG. 6, depending on the location, etching may be performed such that two adjacent second recesses 35 are connected. That is, there may be a place where the second surface 21b of the base material 21 does not remain between two adjacent second recesses 35 . Also, although not shown, etching may be performed so that two adjacent second recesses 35 are connected over the entire second surface 21b.

When the vapor deposition mask device 10 is accommodated in the vapor deposition device 90 as shown in FIG. 1, the first surface 20a of the vapor deposition mask 20 faces the organic EL substrate 92 as indicated by the two-dot chain line in FIG. The second surface 20b of the vapor deposition mask 20 is located on the side of the crucible 94 holding the vapor deposition material 98 . Therefore, the vapor deposition material 98 adheres to the organic EL substrate 92 through the second concave portion 35 whose opening area is gradually reduced. As indicated by the arrow pointing from the second surface 20b side to the first surface 20a in FIG. In addition, it may move in a direction greatly inclined with respect to the normal direction N of the organic EL substrate 92 . At this time, if the thickness of the vapor deposition mask 20 is large, the obliquely moving vapor deposition material 98 is likely to get caught on the top portion 43, the wall surface 36 of the second recess 35, and the wall surface 31 of the first recess 30. As a result, the through hole The ratio of vapor deposition material 98 that cannot pass through 25 increases. Therefore, in order to increase the utilization efficiency of the vapor deposition material 98, it is possible to reduce the thickness t of the vapor deposition mask 20, thereby reducing the height of the wall surface 36 of the second recess 35 and the wall surface 31 of the first recess 30. considered preferable. That is, it can be said that it is preferable to use a base material 21 having a thickness t as small as possible within a range in which the strength of the vapor deposition mask 20 can be secured as the base material 21 for forming the vapor deposition mask 20 . Considering this point, in the present embodiment, the thickness t of the vapor deposition mask 20 is preferably set to 50 μm or less, for example, 5 μm or more and 50 μm or less. Note that the thickness t is the thickness of the peripheral region 23, that is, the thickness of the portion of the vapor deposition mask 20 where the first concave portion 30 and the second concave portion 35 are not formed. Therefore, it can also be said that the thickness t is the thickness of the base material 21 .

In FIG. 5, a straight line L1 passing through the connection portion 41, which is the portion having the minimum opening area of the through-hole 25, and another arbitrary position on the wall surface 36 of the second recess 35 is the normal direction of the vapor deposition mask 20. The minimum angle to be made with N is labeled θ1. In order to make the vapor deposition material 98 moving obliquely reach the organic EL substrate 92 as much as possible without reaching the wall surface 36, it is advantageous to increase the angle θ1. In addition to reducing the thickness t of the vapor deposition mask 20, reducing the width β of the top portion 43 is also effective in increasing the angle θ1.

In FIG. 7, symbol α represents the width of a portion (hereinafter also referred to as a rib portion) of the effective region 22 of the first surface 21a of the base material 21 that remains without being etched. The width α of the rib portion and the dimension r2 of the penetrating portion 42 _are appropriately determined according to the dimensions and the number of display pixels of the organic EL display device. For example, the width α of the rib portion is 5 μm or more and 40 μm or less, and the dimension r ₂ of the through portion 42 is 10 μm or more and 60 μm or less.

Although not limited, the vapor deposition mask 20 according to this embodiment is particularly effective when manufacturing an organic EL display device with a pixel density of 450 ppi or more. Hereinafter, with reference to FIG. 8, an example of the dimensions of the vapor deposition mask 20 required for manufacturing such an organic EL display device with high pixel density will be described. FIG. 8 is a cross-sectional view showing an enlarged through-hole 25 of the vapor deposition mask 20 shown in FIG. 5 and a region in the vicinity thereof.

In FIG. 8, as a parameter related to the shape of the through hole 25, the distance in the direction along the normal direction N of the vapor deposition mask 20 from the first surface 20a of the vapor deposition mask 20 to the connecting portion 41, that is, the first concave portion _The height of the wall 31 of 30 is denoted r1. Furthermore, the dimension of the first recessed portion 30 at the portion where the first recessed portion 30 connects to the _second recessed portion 35, that is, the dimension of the through portion 42 is represented by symbol r2. Further, in FIG. 8, the angle formed by the straight line L2 connecting the connecting portion 41 and the tip edge of the first concave portion 30 on the first surface 21a of the base material 21 with respect to the normal direction N of the base material 21 is It is represented by the symbol θ2.

When manufacturing an organic EL display device with a pixel density of 450 ppi or _more , the dimension r2 of the penetrating portion 42 is preferably set to 10 μm or more and 60 μm or less. As a result, it is possible to provide the vapor deposition mask 20 with which an organic EL display device with a high pixel density can be manufactured. Preferably, the height r1 of the wall surface 31 of the _first recess 30 is set to 6 μm or less.

Next, the aforementioned angle θ2 shown in FIG. 8 will be described. The angle .theta.2 is inclined with respect to the normal direction N of the substrate 21, and the vapor deposition material 98 that flies so as to pass through the through portion 42 in the vicinity of the connection portion 41 can reach the organic EL substrate 92. It corresponds to the maximum value of the inclination angle of the material 98 . This is because the vapor deposition material 98 that has flown through the connecting portion 41 at an angle of inclination greater than the angle θ2 adheres to the wall surface 31 of the first concave portion 30 before reaching the organic EL substrate 92 . Therefore, by reducing the angle θ2, it is possible to prevent the deposition material 98 that has flown at a large angle of inclination and passed through the through portion 42 from adhering to the organic EL substrate 92. It is possible to prevent the deposition material 98 from adhering to the portion outside the portion overlapping the through portion 42 . That is, reducing the angle θ2 leads to suppression of variations in the area and thickness of the deposition material 98 adhering to the organic EL substrate 92 . From this point of view, for example, the through hole 25 is formed so that the angle θ2 is 45 degrees or less. 8, the dimension of the first recess 30 on the first surface 21a, that is, the opening dimension of the through hole 25 on the first surface 21a, is larger than the dimension r2 of the first recess 30 on the connecting portion 41. I gave an example. That is, an example is shown in which the value of the angle θ2 is a positive value. However, although not shown, the dimension r2 of the first recess 30 in the connection portion 41 may be larger than the dimension of the first recess 30 in the first surface 21a. That is, the value of the angle θ2 may be a negative value.

Next, a method for manufacturing the vapor deposition mask 20 will be described.

Method for Manufacturing Metal Plate First , a method for manufacturing a metal plate used for manufacturing a vapor deposition mask will be described.

(rolling process)
First, as shown in FIG. 9, a base material 60 made of an iron alloy containing nickel is prepared, and this base material 60 is directed toward a rolling device 66 including a pair of rolling rolls 66a and 66b as indicated by an arrow D1. Convey along the direction. The base material 60 that has reached between the pair of rolling rolls 66a and 66b is rolled by the pair of rolling rolls 66a and 66b. As a result, the base material 60 is reduced in thickness and elongated along the conveying direction. be Thereby, a metal plate 64 having a thickness T0 can be obtained. As shown in FIG. 9, the wound body 62 may be formed by winding the metal plate 64 around the core 61 . The thickness T0 is, for example, 10 μm or more and 50 μm or less.

Note that FIG. 9 merely shows the outline of the rolling process, and the specific configuration and procedure for carrying out the rolling process are not particularly limited. For example, the rolling process includes a hot rolling process in which the base material is processed at a temperature higher than the temperature at which the crystal arrangement of the invar material constituting the base material 60 is changed, and a hot rolling process in which the base material is processed at a temperature lower than the temperature at which the crystal arrangement of the invar material is changed. It may include a cold rolling step for processing. Moreover, the direction in which the base material 60 and the metal plate 64 are passed between the pair of rolling rolls 66a and 66b is not limited to one direction. For example, in FIGS. 9 and 10, by repeatedly passing the base material 60 and the metal plate 64 between the pair of rolling rolls 66a and 66b from the left side to the right side of the paper surface and from the right side to the left side of the paper surface, The base material 60 and the metal plate 64 may be gradually rolled.

(Slit process)
After that, a slitting step may be performed in which both ends in the width direction of the metal plate 64 obtained by the rolling step are cut off over a predetermined range so that the width of the metal plate 64 is within a predetermined range. This slitting process is performed to remove cracks that may occur at both ends of the metal plate 64 due to rolling. By performing such a slitting process, it is possible to prevent a phenomenon in which the metal plate 64 is broken, that is, plate breakage, from occurring with a crack as a starting point.

(annealing process)
Thereafter, the metal plate 64 may be annealed using an annealing device 67 as shown in FIG. 10 to remove the residual stress accumulated in the metal plate 64 due to rolling. The annealing step may be performed while pulling the metal plate 64 in the conveying direction (longitudinal direction), as shown in FIG. That is, the annealing step may be performed as continuous annealing while being conveyed, instead of so-called batch annealing.

Preferably, the annealing step described above is performed in a non-reducing or inert gas atmosphere. Here, the non-reducing atmosphere is an atmosphere that does not contain a reducing gas such as hydrogen. By "free of reducing gas" is meant that the concentration of reducing gas such as hydrogen is 0.5% or less. The inert gas atmosphere is an atmosphere in which the concentration of reducing gas is 0.5% or less and the concentration of inert gas such as argon gas, helium gas, or nitrogen gas is 90% or more. By performing the annealing process in a non-reducing atmosphere or an inert gas atmosphere, it is possible to suppress the formation of nickel compounds such as nickel hydroxide on the surface layer of the metal plate 64 .

By performing the annealing step, it is possible to obtain the metal plate 64 having a thickness T0 from which residual strain has been removed to some extent.

The elongated metal plate 64 having the thickness T0 may be produced by repeating the above-described rolling process, slitting process, and annealing process multiple times. Although FIG. 10 shows an example in which the annealing process is performed while the metal plate 64 is pulled in the longitudinal direction, it is not limited to this, and the annealing process is performed while the metal plate 64 is wound around the core 61 . It can be carried out in the state of Batch annealing may thus be carried out. When the annealing process is performed while the metal plate 64 is wound around the core 61 , the metal plate 64 may be warped according to the winding diameter of the wound body 62 . Therefore, depending on the winding diameter of the wound body 62 and the material forming the base material 60, it is advantageous to perform the annealing process while pulling the metal plate 64 in the longitudinal direction.

(Cutting process)
After that, a cutting step is performed in which both ends of the metal plate 64 in the width direction are cut off over a predetermined range, thereby adjusting the width of the metal plate 64 to a desired width. Thus, a metal plate 64 having a desired thickness and width can be obtained.

By the way, when the inventors of the present invention conducted extensive research, they found that many inclusions existed in the surface layer of the metal plate 64 after rolling. FIG. 11 is a cross-sectional view showing inclusions 64c present in the surface layer of the metal plate 64 obtained by rolling. Inclusions are granular substances composed of compounds containing metal elements other than iron, such as aluminum and magnesium. The average particle size of the inclusions 64c is, for example, 0.5 μm or more and 20 μm or less. Also, the average particle size of the inclusions 64c may be 0.5 μm or more and 10 μm or less, or may be 0.5 μm or more and 5 μm or less. Compounds are, for example, oxides, sulfides, carbides, nitrides, intermetallic compounds, and the like.

As shown in FIG. 11, many inclusions 64c are present in the first surface layer of the metal plate 64 on the side of the first surface 64a, which is located within the range indicated by symbol T1 in the thickness direction of the metal plate 64. As shown in FIG. Similarly, many inclusions 64c are also present in the second surface layer of the metal plate 64 on the side of the second surface 64b, which is located within the range indicated by symbol T2 in the thickness direction of the metal plate 64. As shown in FIG. The first surface layer T1 is, for example, a portion within 5 μm in the thickness direction from the first surface 64a of the metal plate 64 after rolling. The second surface layer T2 is, for example, a portion within 5 μm in the thickness direction from the second surface 64b of the metal plate 64 after rolling. In addition, as shown in FIG. 11, the inclusions 64c hardly exist in the intermediate layer T3 located between the first surface layer T1 and the second surface layer T2.

FIG. 12 is a cross-sectional view showing a step of etching the metal plate 64 shown in FIG. When the etching progresses to the place where the inclusion 64c exists, the inclusion 64c is exposed on the wall surface 31 of the first recess 30 as shown in FIG. In the state shown in FIG. 12 , most of the surface of the inclusion 64 c exposed on the wall surface 31 is in contact with the iron alloy forming the metal plate 64 . Fixed.

FIG. 13 is a cross-sectional view showing a step of further advancing etching from the state shown in FIG. 12 to enlarge the first concave portion 30. As shown in FIG. As the etching progresses, most of the surface of the inclusion 64c exposed on the wall surface 31 in FIG. As a result, the inclusion 64c is separated from the metal plate 64, and as shown in FIG. Such a depression can also occur on the wall surface 36 of the second recess 35 formed on the second surface 64 b side of the metal plate 64 .

Etching progresses faster in the recessed portion than in other portions. As a result, it is conceivable that the shape of the above-described through hole 25 composed of the first recess 30 and the second recess 35 is affected by the recess. FIG. 14 is a cross-sectional view showing an example of a vapor deposition mask 20 manufactured using a metal plate 64 having many inclusions 64c in the surface layers T1 and T2. As a result of extensive research by the present inventors, as shown in FIG. It was found that many appeared in For example, as shown in FIG. 14 , the wall surface 31 of the first recess 30 may have a recess 31 a reaching the first surface 20 a of the vapor deposition mask 20 . Moreover, the connecting portion 41 may be formed with a notch portion 41a due to the recessed portion.

The aforementioned angle θ2 shown in FIG. 8 is determined by the position of the wall surface 31 of the first concave portion 30 and the position of the connecting portion 41 on the first surface 20a. As described above, the angle θ2 corresponds to the maximum tilt angle of the flying direction of the deposition material 98 that can reach the organic EL substrate 92 . Therefore, the recessed portion 31a and the chipped portion 41a shown in FIG. 14 cause variations in the range of the flying direction of the vapor deposition material 98 that can reach the organic EL substrate 92 . For this reason, if the recessed portion 31a or the chipped portion 41a exists in the through hole 25, it is considered that the dimensional accuracy and positional accuracy of the vapor deposition material adhering to the organic EL substrate 92 through the through hole 25 are degraded. .

In order to solve such a problem, in the present embodiment, before the step of etching the metal plate 64 to form the through-holes 25 in the metal plate 64, a surface layer removal process for removing the surface layer of the metal plate 64 is performed. Propose to implement the process. As a result, the portion of the metal plate 64 where many inclusions 64c are present can be removed. As a result, it is possible to suppress variation in the shape of the through-hole 25 due to the depression formed by the detachment of the inclusion 64c. A method of manufacturing a vapor deposition mask including a surface layer removing step will be described below. In the following description, the metal plate from which the surface layer has been removed by performing the surface layer removing step is denoted by reference numeral 64z.

Manufacturing Method of Deposition Mask A method of manufacturing the deposition mask 20 using the metal plate 64 will be described mainly with reference to FIGS. 15 to 25. FIG. FIG. 15 shows a manufacturing apparatus 70 that manufactures the vapor deposition mask 20 using the metal plate 64. As shown in FIG. First, the wound body 62 is prepared by winding the metal plate 64 around the core 61 . By rotating the core 61 and unwinding the wound body 62, a metal plate 64 extending in a band shape is supplied as shown in FIG.

The supplied metal plate 64 is conveyed to the surface layer removing device 71 , the processing device 72 and the separating device 73 in order by the conveying rollers 75 . The surface layer removing device 71 performs a surface layer removing step of removing at least the first surface layer T1 on the first surface 64a side of the surface layer of the metal plate 64 obtained by rolling. The processing device 72 processes the metal plate 64z from which the surface layer has been removed to form the through holes 25 in the metal plate 64z. In this embodiment, a large number of through-holes 25 corresponding to a plurality of vapor deposition masks 20 are formed in the metal plate 64z. In other words, a plurality of vapor deposition masks 20 are laid out on the metal plate 64z. The separation device 73 performs a separation step of separating a portion of the metal plate 64z in which a plurality of through holes 25 corresponding to one vapor deposition mask 20 are formed from the metal plate 64z. In this manner, a sheet-shaped vapor deposition mask 20 can be obtained.

(Surface layer removal step)
First, the surface layer removing step will be described with reference to FIGS. 16 and 17. FIG. In the surface layer removing step, for example, as shown in FIG. 16, the injection device 71a injects the etchant toward the first surface 64a of the metal plate 64 to bring the etchant into contact with the first surface 64a of the metal plate 64. (injection process). As the etchant, for example, a ferric chloride solution can be used.
By performing such a wet etching process, the first surface layer T1 can be removed over a predetermined range E1 in the thickness direction of the metal plate 64, as shown in FIG. The range E1 for removing the first surface layer T1 in the thickness direction is, for example, 0.5 μm or more and 20 μm or less, preferably 0.5 μm or more and 10 μm or less, and more preferably 0.5 μm or more and 5 μm or less. . By appropriately setting the range E1, the first surface 64a of the metal plate 64z can be composed of the intermediate layer T3 with almost no inclusions 64c. A thickness T4 of the metal plate 64z after the first surface layer T1 is removed over a predetermined range is, for example, 5 μm or more and 50 μm or less.

Incidentally, when the etchant is sprayed toward the first surface 64a of the metal plate 64 with the first surface 64a facing upward, the etchant temporarily stays on the first surface 64a. As a result, it is conceivable that the etching proceeds excessively or the uniformity of the etching becomes low. In consideration of such problems, preferably, as shown in FIG. 16, in the injection step, the etchant is injected toward the first surface 64a of the metal plate 64 with the first surface 64a facing downward. In this case, the etchant after adhering to the first surface 64a and dissolving the first surface layer T1 naturally drops or flows from the first surface 64a due to gravity. This can prevent the etchant from remaining on the first surface 64a. Therefore, excessive etching of the first surface 64a of the metal plate 64 can be suppressed, and the etching uniformity can be improved. Thereby, the thickness T4 of the metal plate 64z can be precisely controlled.

(Processing process)
Next, processing steps for forming the through holes 25 in the metal plate 64z will be described with reference to FIGS. 18 to 25. FIG. 18 to 25, illustration of the inclusion 64c is omitted.

The process of processing the metal plate 64z includes a process of etching the elongated metal plate 64z using a photolithography technique to form the first recesses 30 in the metal plate 64z from the side of the first surface 64a; and a step of etching the metal plate 64z using a lithographic technique to form the second recesses 35 in the metal plate 64z from the second surface 64b side. The through hole 25 is formed in the metal plate 64z by connecting the first recess 30 and the second recess 35 formed in the metal plate 64z. In the example described below, the step of forming the first recess 30 is performed before the step of forming the second recess 35, and between the step of forming the first recess 30 and the step of forming the second recess 35, A step of sealing the produced first concave portion 30 is performed. Details of each step will be described below.

First, as shown in FIG. 18, resist films 65c and 65d containing a negative photosensitive resist material are formed on the first surface 64a and the second surface 64b of the metal plate 64z. For example, a coating liquid containing a photosensitive resist material such as casein is applied onto the first surface 64a and the second surface 64b of the metal plate 64z, and then the coating liquid is dried to form the resist films 65c and 65d. Form.

Next, exposure masks 68a and 68b are prepared so as not to transmit light to areas to be removed of the resist films 65c and 65d. place on top. At this time, an alignment process may be performed to adjust the relative positional relationship between the exposure mask 68a on the side of the first surface 64a and the exposure mask 68b on the side of the second surface 64b. As the exposure masks 68a and 68b, for example, a glass dry plate that does not allow light to pass through the areas to be removed of the resist films 65c and 65d is used. After that, the exposure masks 68a and 68b are sufficiently adhered to the resist films 65c and 65d by vacuum adhesion.
A positive resist material may be used as the photosensitive resist material. In this case, as the exposure mask, an exposure mask is used that allows light to pass through the area of the resist film that is to be removed.

After that, the resist films 65c and 65d are exposed through the exposure masks 68a and 68b (exposure step). Further, the resist films 65c and 65d are developed to form images on the exposed resist films 65c and 65d (development step). As described above, as shown in FIG. 20, a first resist pattern 65a is formed on the first surface 64a of the metal plate 64z, and a second resist pattern 65b is formed on the second surface 64b of the metal plate 64z. be able to. The development process may include a resist heat treatment process for increasing the hardness of the resist films 65c and 65d or for making the resist films 65c and 65d more firmly adhere to the metal plate 64z.
The resist heat treatment process can be performed, for example, at room temperature or higher and 400° C. or lower.

Next, as shown in FIG. 21, a first surface etching step is performed in which a region of the first surface 64a of the metal plate 64z not covered with the first resist pattern 65a is etched using a first etchant. . For example, the first etchant is sprayed toward the first surface 64a of the metal plate 64z through the first resist pattern 65a from a nozzle arranged on the side facing the first surface 64a of the metal plate 64z being conveyed. . As a result, as shown in FIG. 21, erosion by the first etchant progresses in areas of the metal plate 64z that are not covered with the first resist pattern 65a. As a result, a large number of first recesses 30 are formed in the first surface 64a of the metal plate 64z. As the first etchant, for example, one containing a ferric chloride solution and hydrochloric acid is used.

After that, as shown in FIG. 22, the first recesses 30 are covered with a resin 69 having resistance to the second etchant used later in the second surface etching step. That is, the first concave portion 30 is sealed with the resin 69 having resistance to the second etchant. In the example shown in FIG. 22, a film of resin 69 is formed so as to cover not only the formed first concave portion 30 but also the first surface 64a (first resist pattern 65a).

Next, as shown in FIG. 23, the second surface 64b of the metal plate 64z that is not covered with the second resist pattern 65b is etched to form the second recess 35 in the second surface 64b. An etching step is performed. The second surface etching step is performed until the first recesses 30 and the second recesses 35 communicate with each other, thereby forming the through holes 25 . As the second etchant, one containing, for example, a ferric chloride solution and hydrochloric acid is used, like the above-described first etchant.

Note that the erosion by the second etchant is performed on the portion of the metal plate 64z that is in contact with the second etchant. Therefore, corrosion progresses not only in the normal direction N (thickness direction) of the metal plate 64z, but also in the direction along the plate surface of the metal plate 64z. Here, preferably, in the second surface etching step, two second recesses 35 respectively formed at positions facing two adjacent holes 66a of the second resist pattern 65b are positioned between the two holes 66a. It ends before joining on the back side of the bridge portion 67a. As a result, as shown in FIG. 24, the above-described top portion 43 can be left on the second surface 64b of the metal plate 64z.

After that, as shown in FIG. 25, the resin 69 is removed from the metal plate 64z. The resin 69 can be removed by using, for example, an alkaline remover. When an alkaline stripping solution is used, as shown in FIG. 25, the resin 69 and the resist patterns 65a and 65b are removed at the same time. After the resin 69 is removed, the resist patterns 65a and 65b may be removed separately from the resin 69 using a stripping solution different from the stripping solution for stripping the resin 69. FIG.

(Separation process)
After that, the vapor deposition mask 20 can be obtained by separating the portion of the metal plate 64z in which the plurality of through holes 25 corresponding to one vapor deposition mask 20 are formed from the metal plate 64z.

(Action of this embodiment)
In the method of manufacturing the vapor deposition mask 20 according to the present embodiment, before the metal plate 64 is processed to form the through holes 25 in the metal plate 64, the first surface layer T1 on the side of the first surface 64a of the metal plate 64 is formed. A surface layer removing step is carried out. Thereby, it is possible to obtain the metal plate 64z in which the density of the inclusions 64c on the side of the first surface 64a is reduced. As a result, it is possible to suppress variation in the shape of the through-hole 25 due to the depression formed by the detachment of the inclusion 64c. Therefore, the dimensional accuracy and positional accuracy of the vapor deposition material adhering to the organic EL substrate 92 through the through holes 25 can be improved.

Various modifications can be made to the above-described embodiment. Modifications will be described below with reference to the drawings as necessary. In the following description and the drawings used in the following description, the same reference numerals as those used for the corresponding portions in the above-described embodiment are used for the portions that can be configured in the same manner as in the above-described embodiment, Duplicate explanations are omitted. Further, when it is clear that the effects obtained in the above-described embodiment can also be obtained in the modified example, the explanation thereof may be omitted.

(Modified example of removed surface layer)
In the above embodiment, only the first surface layer T1 on the side of the first surface 64a of the metal plate 64 is removed over the range E1 in the thickness direction, and the second surface layer T2 on the side of the second surface 64b is not removed. showed that. However, the present invention is not limited to this. As shown in FIG. 26, in addition to the first surface layer T1, the second surface layer T2 on the side of the second surface 64b of the metal plate 64 is further extended over a range E2 in the thickness direction. may be removed. The range E2 in the thickness direction to remove the second surface layer T2 is, for example, 0.5 μm or more and 20 μm or less, preferably 0.5 μm or more and 10 μm or less, and more preferably 0.5 μm or more and 5 μm or less. . A thickness T4 of the metal plate 64z after the first surface layer T1 and the second surface layer T2 are removed over a predetermined range is, for example, 5 μm or more and 50 μm or less.

(Modification of removal method)
In the above-described embodiment, an example of removing the surface layer of the metal plate 64 by spraying the etchant toward the surface of the metal plate 64 was shown, but the method of removing the surface layer is not particularly limited. do not have. For example, the surface layer of the metal plate 64 may be removed by immersing the metal plate 64 in an etching bath in which an etchant is stored. Alternatively, the surface layer of the metal plate 64 may be removed by bringing a member such as cloth impregnated with the etching liquid into contact with the surface of the metal plate 64 .

10 Deposition mask device 15 Frame 20 Deposition mask 21 Base material 22 Effective area 23 Surrounding area 25 Through hole 30 First concave portion 31 Wall surface 31a Recessed portion 35 Second concave portion 36 Wall surface 41 Connection portion 41a Notch portion 43 Top portion 50 Intermediate product 64 Metal Plate 64c Inclusion 64z Metal plate 65a First resist pattern 65b Second resist pattern 65c First resist film 65d Second resist film 71 Surface layer removal device 72 Processing device 73 Separation device 90 Vapor deposition device 92 Organic EL substrate 98 Vapor deposition material

Claims (1)

A method for manufacturing a metal plate used for manufacturing a vapor deposition mask by forming a plurality of through holes,
A rolling step of rolling a base material made of an iron alloy containing nickel to produce a metal plate including a first surface and a second surface;
a surface layer removing step of removing at least the surface layer on the first surface side of the metal plate,
In the surface layer removing step, the surface layer on the first surface side is removed by 0.5 μm or more, but the surface layer on the second surface side is not removed by 0.5 μm or more,
When the vapor deposition mask is manufactured by forming the plurality of through holes in the metal plate, the first recess is formed on the first surface, and the second surface has a larger area than the first recess in plan view. A second recess having a large dimension and being connected to the first recess in the thickness direction of the metal plate is formed. A method of manufacturing a metal plate.

Images