Alignment mark, method for forming alignment mark, and metal mask with alignment mark

Abstract

To provide an alignment mark formed in a mask substrate in which the alignment mark is prevented from disappearing due to a mark body inadvertently dropping out from a mark through hole.SOLUTION: An alignment mark 5 formed in a mask substrate 1 comprises a mark through hole 6 formed through the mask substrate 1 toward the vertical direction, which is the thickness direction, and a mark body 7 filling the mark through hole 6. The mark through hole 6 comprises a through hole main body 10 passing through the mask substrate 1, and ring-shaped recessed parts 11 and 12. A roughened surface-treated surface 21 having fine irregularities are formed on vertically oriented receiving surfaces 13 and 14 of the recessed parts 11 and 12 and a fine convexoconcave surface 22 is formed on flange parts 16 and 17 of the mark body 7 that correspond to the receiving surfaces 13 and 14, and both surfaces 21 and 22 are brought into convexoconcave engagement.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an alignment mark for detecting the position and / or posture of a detection object, a method for forming an alignment mark, and a metal mask provided with an alignment mark. [Background technology]

[0002] For example, Patent Document 1 (title of invention: Metal mask and manufacturing method thereof) discloses a metal mask equipped with an alignment mark (target mark). The alignment mark in Patent Document 1 is composed of a through-hole formed in a mask substrate made of a thin metal plate in the plate thickness direction, and a dye filled in this through-hole. The through-hole is a stepped hole having a large diameter hole and a small diameter hole, each of which is a straight hole. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-71637 Summary of the Invention [Problem to be solved by the invention]

[0004] In the alignment mark of Patent Document 1, dye is filled into stepped through-holes. The step catches the dye as it moves from the larger-diameter hole to the smaller-diameter hole, preventing it from falling out of the smaller-diameter side of the through-hole. Furthermore, the dye filled in the smaller-diameter holes exerts an anchoring effect, preventing it from falling out of the larger-diameter side of the through-hole. However, the mask substrate is thin, making it difficult to reliably retain the dye solely through the anchoring effect of the small-diameter holes. Furthermore, deformation, such as bending, of the mask substrate can cause separation between the inner surface of the through-hole and the dye, potentially resulting in the dye falling out. Foreign matter can also enter the separated area, potentially causing the dye to fall out. In particular, when cleaning the mask substrate, friction on the surface of the mask substrate or deformation of the mask substrate can cause cleaning water to enter the separated area, potentially causing the dye to fall out of the through-hole, resulting in the inadvertent loss of the alignment mark.

[0005] An object of the present invention is to prevent the mark body from accidentally falling out of the mark through-hole, causing the alignment mark to be lost, in an alignment mark consisting of a mark through-hole formed in a mask substrate and a mark body filling the mark through-hole. Another object of the present invention is to provide a method for forming the above alignment mark, and a metal mask equipped with the alignment mark. [Means for solving the problem]

[0006] The present invention relates to an alignment mark 5 formed on a mask substrate 1 having a mask opening 2. This alignment mark 5 comprises a mark through-hole 6 formed to penetrate the mask substrate 1 in the vertical direction, which is the thickness direction, and a mark body 7 filling this mark through-hole 6. The mark through-hole 6 comprises a through-hole body 10 penetrating the mask substrate 1 and having openings 8 and 9 on the top and bottom surfaces of the mask substrate 1, and ring-shaped recessed portions 11 and 12 having receiving surfaces 13 and 14 facing the vertical direction and recessed into at least one of the top and bottom surfaces of the mask substrate 1 to surround the openings 8 and 9. The mark body 7 comprises a columnar portion 15 corresponding to the through-hole body 10 and flange portions 16 and 17 formed to protrude outward from at least one of the top and bottom ends of the columnar portion 15 to correspond to the recessed portions 11 and 12. The receiving surfaces 13 and 14 of the recessed portions 11 and 12 are formed of a roughened surface 21 having minute irregularities, and the surfaces of the flange portions 16 and 17 of the mark body 7 corresponding to these receiving surfaces 13 and 14 are formed of a minutely irregular surface 22.

[0007] A roughened surface 21 is formed on the inner wall surface of the through-hole body 10, and a minutely uneven surface 22 is formed on the outer circumferential surface of the columnar portion 15 of the mark body 7 corresponding to this inner wall surface.

[0008] The upper and lower ends of the through-hole body 10 of the mark through-hole 6 are formed in an expanding shape with the diameter increasing upward or downward.

[0009] The present invention relates to a method for forming an alignment mark 5 in a mask substrate 1 having a mask opening 2. The alignment mark 5 comprises a mark through-hole 6 formed to penetrate the mask substrate 1 in the vertical direction, which is the thickness direction, and a mark body 7 filling the mark through-hole 6. The method includes the following steps: a through-hole forming step of forming a through-hole body 10 having openings 8 and 9 on each of the upper and lower surfaces of the mask substrate 1; a recess forming step of recessing ring-shaped recesses 11 and 12 having receiving surfaces 13 and 14 facing the vertical direction in at least one of the upper and lower surfaces of the mask substrate 1 so as to surround the openings 8 and 9; a roughening step of forming a roughened surface 21 having minute asperities on the receiving surfaces 13 and 14 of the recesses 11 and 12; a base material filling step of filling the through-hole body 10 and the recesses 11 and 12 with a mark base material 34; and a curing step of curing the filled mark base material 34 to form the mark body 7.

[0010] The mask substrate 1 is formed by electroforming, and the step of forming the mask substrate 1 by electroforming and the step of forming the through-holes are carried out simultaneously.

[0011] The metal mask according to the present invention has an alignment mark 5 according to any one of claims 1 to 3 formed on a mask substrate 1 made of a thin metal plate. [Effects of the Invention]

[0012] In the alignment mark of the present invention, the mark through-hole 6 penetrates the mask substrate 1 and comprises a through-hole body 10 having openings 8 and 9 on each of the upper and lower surfaces of the mask substrate 1, and ring-shaped recessed portions 11 and 12 having receiving surfaces 13 and 14 oriented in the vertical direction and recessed into at least one of the upper and lower surfaces of the mask substrate 1 so as to surround the openings 8 and 9. If the receiving surfaces 13 and 14 of the recessed portions 11 and 12 are formed as roughened surfaces 21 having minute irregularities and the surfaces of the flange portions 16 and 17 of the mark body 7 facing these receiving surfaces 13 and 14 are formed as minutely irregular surfaces 22, the roughened surface 21 on the mark through-hole 6 side and the minutely irregular surface 22 on the mark body 7 side can be firmly engaged with each other, thereby firmly engaging and fixing the mark body 7 to the mark through-hole 6. In other words, if the receiving surfaces 13 and 14 of the recesses 11 and 12 are formed as roughened surfaces 21 with minute asperities, the surfaces of the flange portions 16 and 17 of the mark body 7 facing these receiving surfaces 13 and 14 are formed as minutely asperities 22, thereby firmly asperity-engaging the roughened surface 21 on the mark through-hole 6 side with the minutely asperity surface 22 on the mark body 7 side, thereby firmly engaging and fixing the mark body 7 to the mark through-hole 6. This prevents the mark body 7 from accidentally falling out of the mark through-hole 6 and the alignment mark 5 from being lost, thereby enabling a more reliable alignment mark 5 to be formed on the mask substrate 1. If flange portions 16 and 17 are provided on the top and bottom surfaces of the mask substrate 1, the mask substrate 1 can be sandwiched between these upper and lower flange portions 16 and 17, which also prevents the mark body 7 from accidentally falling out of the mark through-hole 6 and the alignment mark 5 from being lost.

[0013] When a roughened surface 21 is formed on the inner wall surface of the through-hole body 10 and the outer peripheral surface of the columnar portion 15 of the mark body 7 corresponding to this inner wall surface is formed with a minutely uneven surface 22, the area subjected to the roughening treatment can be made larger than when only the receiving surfaces 13 and 14 of the recessed portions 11 and 12 are roughened. As a result, the area where the uneven engagement between the mark body 7 and the mark through-hole 6 is made larger, and the mark body 7 can be more firmly engaged and fixed to the mark through-hole 6.

[0014] If the upper and lower ends of the through-hole body 10 of the mark through-hole 6 are formed in a flared shape with the diameter increasing upward or downward, the thickness of the connecting portion between the columnar portion 15 of the mark body 7 and the flange portions 16 and 17 can be made larger than when the through-hole body 10 is straight, thereby increasing the rigidity of the connecting portion. This makes it possible to prevent damage to the mark body 7, and therefore allows for a more reliable alignment mark 5 to be formed on the mask substrate 1.

[0015] The alignment mark according to the present invention can be produced through a through-hole forming process, a recess forming process, a surface roughening process, a base material filling process, and a curing process. If the mask substrate 1 is then formed by electroforming and the mask substrate 1 forming process and the through-hole forming process are carried out simultaneously, the mask substrate 1 and the mark through-hole 6 of the alignment mark 5 can be produced simultaneously. This makes it possible to suppress increases in the production costs of the alignment mask 5 and the mask substrate 1 compared to when both processes (the mask substrate 1 and the mark through-hole 6) are produced in separate processes.

[0016] The present invention can provide a metal mask in which the above-described alignment marks 5 are formed on a mask substrate 1 made of a thin metal plate. This prevents the mark body 7 from accidentally falling out of the mark through-hole 6 and the alignment mark 5 from being lost, thereby providing a metal mask with a more reliable alignment mark. [Brief explanation of the drawings]

[0017] [Figure 1] 3 is a longitudinal sectional front view of the alignment mark according to the first embodiment of the present invention, and is a sectional view taken along line AA in FIG. 2. FIG. [Figure 2] FIG. 1 is a perspective view of a metal mask having alignment marks according to a first embodiment. [Figure 3] 5(a) to 5(d) are diagrams illustrating a method for manufacturing an alignment mark according to the first embodiment. [Figure 4]5(a) to 5(d) are diagrams illustrating a method for manufacturing an alignment mark according to the first embodiment. [Figure 5] FIG. 10 is a vertical sectional front view of an alignment mark according to a second embodiment of the present invention. [Figure 6] 10(a) to 10(d) are diagrams illustrating a method for manufacturing an alignment mark according to a second embodiment. [Figure 7] FIG. 10 is a vertical sectional front view of an alignment mark according to a third embodiment of the present invention. [Figure 8] 10(a) and 10(b) are longitudinal sectional front views of an alignment mark according to a fourth embodiment of the present invention. [Figure 9] FIG. 10 is a vertical sectional front view of an alignment mark according to a fifth embodiment of the present invention. [Figure 10] FIG. 10 is a perspective view of an alignment mark according to a sixth embodiment of the present invention. [Figure 11] 13(a) and 13(b) are longitudinal sectional front views of a main part of an alignment mark according to a seventh embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] First Embodiment FIGS. 1 to 4 show a first embodiment in which the alignment mark according to the present invention is applied to an alignment mark on a metal mask for screen printing. In this embodiment, the terms "front, back, left, right, top, bottom" refer to the crossed arrows shown in FIGS. 1 and 2 and the indications near each arrow. As shown in FIG. 2, the metal mask is based on a mask substrate 1 made of a thin metal plate formed into a square planar shape. The mask substrate 1 has a printing pattern section (pattern area) 3 formed in the center thereof and has a group of numerous through holes (mask openings) 2 for ink paste, which are patterned to form a desired printing pattern. The metal mask according to this embodiment is formed by integrally molding the printing pattern section 3 and the outer periphery 4 using an electroforming (plating) method.

[0019] Alignment marks 5 used for alignment with the printing substrate are formed at each of two corners arranged diagonally on the outer periphery 4. As shown in FIG. 1, each alignment mark 5 consists of a mark through-hole 6 formed through the mask substrate 1 in the vertical direction, which is the thickness direction, and a mark body 7 filling this mark through-hole 6. The alignment marks 5 are recognized by a camera or the like by distinguishing the difference in color tone between the surface of the alignment mark 5 and the surface of the mask substrate 1 around its periphery. To make it easier to identify the alignment marks 5 using a CCD camera or the like, the mark body 7 filling the mark through-hole 6 is made of a resin (mark base material) with a reflectance different from the reflectance of the surface of the mask substrate 1.

[0020] As shown in FIG. 1 , the mark through-hole 6 is composed of a through-hole body 10 that penetrates the mask substrate 1 and has openings 8 and 9 on the upper and lower surfaces of the mask substrate 1, and recessed portions 11 and 12 that are recessed into the upper and lower surfaces of the mask substrate 1 and surround the openings 8 and 9. The planar shape of the mark through-hole 6 (the shape that appears on the upper and lower surfaces of the mask substrate 1), defined by the outer peripheries of the recessed portions 11 and 12, is circular. In this embodiment, the through-hole body 10 is composed of an upper half portion 6a that is formed in a bell-mouth shape that widens upward and whose diameter increases toward the top, and a lower half portion 6b that is formed in a straight shape with a uniform diameter along the vertical direction. The recessed portion 11 surrounding the opening 8 in the upper half portion 6a is a circular ring-shaped recessed hole with a receiving surface 13 that faces upward. Similarly, the recessed portion 12 surrounding the opening 9 in the lower half portion 6b is a circular ring-shaped recessed hole with a receiving surface 14 that faces downward.

[0021] The mark body 7 is formed in the mark through-hole 6 by filling the mark through-hole 6 with a resin that will become the mark base material 34 (see FIG. 4(c)) and curing it. The mark body 7 is composed of a columnar portion 15 corresponding to the through-hole main body 10 and flange portions 16 and 17 that protrude outward from the upper and lower ends of the columnar portion 15 and correspond to the recessed portions 11 and 12. The columnar portion 15 of the mark body 7 according to this embodiment is formed of an upper portion 7a that fills the upper half portion 6a and a lower portion 7b that fills the lower half portion 6b. The upper portion 7a is formed in an upwardly flared shape with a concave curved surface whose outer periphery has a slope angle that decreases upward, and the lower portion 7b is formed in a straight cylindrical shape with a uniform diameter in the vertical direction.

[0022] The receiving surfaces 13 and 14 of the recesses 11 and 12 are formed with a roughened surface 21 having minute irregularities, and the surfaces of the flanges 16 and 17 corresponding to these receiving surfaces 13 and 14 are formed with a minutely roughened surface 22. The inner wall surface of the upper half 6a is also formed with a roughened surface 21 having minute irregularities, and the outer peripheral surface of the upper portion 7a corresponding to this inner wall surface is formed with a minutely roughened surface 22.

[0023] According to the alignment mark 5 configured as described above, the roughened surface 21 on the mark through-hole 6 side and the minutely asperity surface 22 on the mark body 7 side can be firmly engaged with each other, thereby firmly fixing the mark body 7 to the mark through-hole 6. This prevents the mark body 7 from accidentally falling out of the mark through-hole 6 and causing the alignment mark 5 to be lost. Furthermore, the through-hole body 10 of the mark through-hole 6 has an upwardly flared upper half 6a whose diameter increases upward, and the roughened surface 21 is also formed on the inner wall surface of this upper half 6a. This allows for a larger roughened area than when only the receiving surfaces 13 and 14 of the recesses 11 and 12 are roughened. This increases the area of ​​asperity engagement between the mark body 7 and the mark through-hole 6, thereby more firmly fixing the mark body 7 to the mark through-hole 6. As described above, according to this embodiment, a more reliable alignment mark 5 can be formed on the mask substrate 1.

[0024] In addition, the mark body 7 clamps the mask substrate 1 between the upper and lower flanges 16 and 17, which also prevents the mark body 7 from accidentally falling out of the mark through-hole 6 and the loss of the alignment mark 5. In this case, the upper end of the through-hole body 10 of the mark through-hole 6 is formed in a flared shape with a diameter that increases toward the top, so that the thickness of the connecting portion between the columnar portion 15 and flange portion 16 of the mark body 7 can be made larger than when the upper half is straight, and the rigidity of this connecting portion can be increased. This makes it possible to prevent damage to the mark body 7 and improve the reliability of the alignment mark 5.

[0025] For these reasons, the printing metal mask according to this embodiment can contribute to Goal 9 (Industry, innovation and infrastructure - Build resilient infrastructure, promote inclusive and sustainable industrialization and foster innovation) and Goal 12 (Responsible consumption and production - Ensure sustainable consumption and production patterns) of the Sustainable Development Goals (SDGs) advocated by the United Nations.

[0026] FIGS. 3(a)-(d) and 4(a)-(d) show a manufacturing method for an alignment mark 5 and a metal mask according to the first embodiment. In this embodiment, the mask substrate 1 is formed by electroforming, and the process of forming the mask substrate 1 by electroforming and the process of forming the mark through-holes 6 are performed simultaneously. Specifically, as shown in FIG. 3(a), a photoresist layer 26 is applied or laminated onto the upper surface of a matrix 25. Then, a pattern film 27 having pattern openings 27a corresponding to the mask openings 2 and the mark through-holes 6 is adhered to the upper surface. After the photoresist layer 26 is baked (exposed) with an ultraviolet lamp 28, developed, and dried, the unexposed portions are removed. As shown in FIG. 3(b), a resist body 29a corresponding to the mask openings 2 and a resist body 29b corresponding to the mark through-holes 6 are formed on the matrix 25. Next, as shown in FIG. 3(c), these resist bodies 29a and 29b are used to form an electrodeposited layer 30 on the matrix 25 by electroforming. This allows the formation of the mark through-holes 6 at the same time as the formation of the mask substrate 1 having the mask openings 2 (through-hole formation process). In other words, the mask substrate 1, the mark through-holes 6, and the mask openings 2 can be formed simultaneously. The mark through-holes 6 have openings 8 and 9 at the top and bottom. At this time, the current density near the periphery of the resist bodies 29a and 29b decreases, so that the upper ends (openings 8) of the resulting mask openings 2 and mark through-holes 6 have a bell-mouth shape with a diameter that increases upward. Next, the resist bodies 29a and 29b are dissolved (swelled) and removed, thereby creating the mask substrate 1 having the mask openings 2 and the mark through-holes 6, as shown in FIG. 3(d).

[0027] Next, as shown in FIG. 4(a), an irradiation device 32 is disposed above the mask substrate 1, and a laser beam 33 is irradiated onto the upper surface of the mask substrate 1 at the location where the alignment mark 5 is to be formed, thereby eliminating a portion of the mask substrate 1 around the opening 8 and forming a recess 11 having a receiving surface 13 (recess forming step). At this time, the laser beam 33 eliminates the surface of the receiving surface 13 of the recess 11, thereby forming a roughened surface 21 having minute irregularities (roughening step). At the same time, the surface of the inner wall surface above the mark through-hole 6 is eliminated, thereby forming a roughened surface 21 having minute irregularities on the inner wall surface. Next, as shown in FIG. 4(b), an irradiation device 32 is disposed below the mask substrate 1, and a laser beam 33 is irradiated onto the lower surface of the mask substrate 1 at the location where the alignment mark 5 is to be formed, thereby eliminating a portion of the mask substrate 1 around the opening 9 and forming a recess 12 having a receiving surface 14. At this time, as before, the surface of the receiving surface 14 of the recessed portion 12 is eliminated by the laser light 33, thereby forming a roughened surface 21 with minute irregularities. Next, a mark base material 34 made of resin is filled so as to receive the mark through-hole 6 (base material filling process). In this base material filling process, the mask substrate 1 is placed on a work table 35, and the mark base material 34 is filled into the mark through-hole 6 with the opening 9 on the lower side of the mark through-hole 6 closed. Finally, the mark base material 34 filled into the mark through-hole 6 is hardened (hardening process). This allows the formation of an alignment mark 5 consisting of the mark through-hole 6 and a mark body 7 consisting of an upper portion 7a and a lower portion 7b that fills the mark through-hole 6.

[0028] Second Embodiment FIGS. 5 and 6 show a second embodiment of an alignment mark according to the present invention. As shown in FIG. 5, the mark through hole 6 constituting the alignment mark 5 according to this embodiment is a straight hole with a uniform inner diameter in the vertical direction. A roughened surface 21 having minute asperities is formed on the entire inner wall of the mark through hole 6. The outer periphery of the mark body 7 enters the minute asperities constituting this roughened surface 21, so that the outer periphery of the columnar portion 15 of the mark body 7 becomes a minutely asperity surface 22. The recessed portion 11 having a receiving surface 13 formed above the mark through hole 6 and the recessed portion 12 having a receiving surface 14 formed below the mark through hole 6 each have a substantially uniform vertical recession dimension in the circumferential direction, and the flange portions 16 and 17 of the mark body 7 that fill these recesses have a substantially uniform vertical thickness in the circumferential direction. Other features, such as the formation of a roughened surface 21 on the receiving surfaces 13 and 14 of the recessed portions 11 and 12, and the formation of a minutely uneven surface 22 on the flange portions 16 and 17, are the same as those in the first embodiment.

[0029] As in the alignment mark 5 of this embodiment, when a roughened surface 21 is formed on the entire inner wall of the mark through-hole 6 and a minutely asperity surface 22 is formed on the outer periphery of the columnar portion 15 of the mark body 7 corresponding to this inner wall surface, the roughened area can be made larger than when only the receiving surfaces 13 and 14 of the recesses 11 and 12 are roughened or when only a portion of the inner wall of the mark through-hole 6 is roughened, thereby making it possible to increase the area where the asperity engages between the mark body 7 and the mark through-hole 6. Therefore, the mark body 7 can be more firmly engaged and fixed to the mark through-hole 6.

[0030] The mark through-hole 6 constituting the alignment mark 5 of this embodiment is formed by irradiating a mask substrate (FIG. 6(a)) prepared by an electroforming process with a laser. Specifically, as shown in FIG. 6(b), an irradiation device 32 is disposed above the mask substrate 1, and a laser beam 33 is irradiated onto the mask substrate 1 at the location where the alignment mark 5 is to be formed, thereby eliminating a portion of the mask substrate 1 and forming a mark through-hole 6 that penetrates the mask substrate 1 in the vertical direction. The laser beam 33 is set to be straight with no change in beam diameter, and a straight hole with a uniform diameter is formed in the mask substrate 1 in the vertical direction. Next, as shown in FIG. 6(c), the mask substrate 1 is placed on a workbench 35, a diffusion prism 37 is placed inside the mark through-hole 6, and the irradiation device 32 is again driven to irradiate the diffusion prism 37 with the laser beam 33. The laser beam 33 diffused by the diffusion prism 37 is irradiated onto the entire inner wall of the mark through-hole 6, eliminating the surface of the inner wall and forming a roughened surface 21 with minute irregularities. As a result, as shown in Fig. 6(d), a mark through-hole 6 having a roughened surface portion, in which the entire inner wall of the straight hole is provided with a roughened surface 21 having minute concaves and convexes, can be formed. The subsequent steps are the same as those shown in Figs. 4(a) to 4(d) of the first embodiment. In this embodiment, as shown in Fig. 6(c), the roughened surface 21 having minute concaves and convexes is formed on the inner wall of the mark through-hole 6 by using laser light 33 diffused by a diffusion prism 37. However, the roughened surface 21 may also be formed on the inner wall of the mark through-hole 6 by using a resist having a rough surface on the side surface.

[0031] (Third embodiment) Fig. 7 shows a third embodiment of an alignment mark according to the present invention. The alignment mark 5 according to Fig. 7 differs from the second embodiment in that the roughened surface 21 formed on the entire inner wall surface of the mark through-hole 6 is eliminated. In all other respects, it is the same as the second embodiment.

[0032] (Fourth embodiment) Figure 8(a) shows a fourth embodiment of an alignment mark according to the present invention. In this embodiment, the upper half 6a constituting the through-hole body 10 of the mark through-hole 6 is formed in a bell-mouth shape tapering downward, with the angle of inclination of the inner wall increasing downward, and the lower half 6b is formed in a straight shape with a uniform diameter in the vertical direction. The inner diameter of the lowermost part of the upper half 6a is set smaller than the inner diameter of the lower half 6b. The mark body 7 filling the mark through-hole 6 is formed in a tapered shape with the upper part 7a being a concave curved surface with the angle of inclination of the outer periphery increasing downward, and the lower part 7b is formed in a straight cylindrical shape with a uniform diameter in the vertical direction. Recessed portions 11 and 12 having receiving surfaces 13 and 14 oriented in the vertical direction are formed on the periphery of opening 8 in upper half 6a of mark through-hole 6 and on the periphery of opening 9 in lower half 6b, respectively, and correspondingly, a flange portion 16 is formed at the upper end of upper portion 7a of mark body 7, and a flange portion 17 is formed at the lower end of lower portion 7b. Roughened surfaces 21 are formed on receiving surfaces 13 and 14, and minutely uneven surfaces 22 are formed on flange portions 16 and 17.

[0033] 8(b) shows an alignment mark according to a modification of the fourth embodiment, in which the diameter (d1) of the receiving surface defined by the inner wall of the lowermost portion of the upper half portion 6a of the mark through-hole 6 and the inner wall of the uppermost portion of the lower half portion 6b is set to the same dimension as the height (d2) of the upper half portion 6a. This configuration can be obtained by forming a resist body having substantially the same shape as the lower portion 7b of the mark body 7 on a matrix, and then producing the mask substrate 1 by electroforming. In other words, when electroforming is performed using a resist body having substantially the same shape as the lower portion 7b of the mark body 7, the electroforming speed in the horizontal direction from the upper corner of the resist body and the electroforming speed in the upward direction from the upper end of the resist body are substantially the same. Therefore, the dimension d1 resulting from the amount of electroforming in the horizontal direction and the dimension d2 resulting from the amount of electroforming in the upward direction can be made substantially the same dimension. It is also possible to form a straight hole at the bottom of the upper half 6a of the mark through-hole 6 in this embodiment, and form a straight cylindrical portion between the upper portion 7a and the lower portion 7b of the mark body 7. Such a configuration can be obtained by forming a resist body having approximately the same shape as the lower portion 7b of the mark body 7 on a matrix, then laminating and forming a resist body having approximately the same shape as the straight cylindrical portion, and then producing the mask substrate 1 by electroforming.

[0034] Fifth Embodiment FIG. 9 shows a fifth embodiment of an alignment mark according to the present invention. In this embodiment, the upper half 6a of the mark through-hole 6 is formed in a bowl-like shape tapering downward, with the angle of inclination of the inner wall decreasing downward, and the lower half 6b is formed in a straight shape with a uniform diameter in the vertical direction. The mark body 7 filling the mark through-hole 6 has the upper portion 7a formed in a hemispherical truncated shape tapering downward, with the outer periphery having a convex curved surface whose angle of inclination decreases downward, and the lower portion 7b formed in a straight cylindrical shape with a uniform diameter in the vertical direction. The periphery of the opening 8 of the upper half 6a of the mark through-hole 6 and the periphery of the opening 9 of the lower half 6b are formed with recesses 11 and 12 having receiving surfaces 13 and 14 oriented in the vertical direction, respectively. Correspondingly, a flange 16 is formed at the upper end of the upper portion 7a of the mark body 7, and a flange 17 is formed at the lower end of the lower portion 7b. The receiving surfaces 13 and 14 are formed with a roughened surface 21, and the flange portions 16 and 17 are formed with a minutely uneven surface 22.

[0035] Sixth Embodiment FIG. 10 shows a sixth embodiment of an alignment mark according to the present invention. In this embodiment, a heat-shielding structure is formed around the alignment mark 5. The heat-shielding structure is composed of a ring-shaped (annular) groove 42 recessed into the upper surface of the mask substrate 1 so as to surround the alignment mark 5, and a flat surface 41 formed between the outer periphery of the alignment mark 5 and the groove 42. The provision of a heat-shielding structure around the alignment mark 5 in this manner prevents heat generated during the formation of the mark through-hole 6 and the roughened surface 21 by irradiation with laser light from spreading around the mask substrate 1, thereby preventing deformation of the mask substrate 1 during irradiation with laser light. The shape of the groove 42 is not limited to annular, and it may be a square (polygonal) frame shape.

[0036] Seventh Embodiment FIGS. 11(a) and 11(b) show an alignment mark according to a seventh embodiment of the present invention. The alignment mark 5 of this embodiment differs from the first to sixth embodiments in that a rough surface portion 45 for camera recognition, consisting of minute irregularities, is formed on the outer periphery of the mark body 7. Specifically, in the alignment mark 5 shown in FIG. 11(a), a circular ring-shaped rough surface portion 45 is formed on the upper surface of the mask substrate 1 outside the outermost periphery of the flange portion 16 of the mark body 7. In the alignment mark 5 shown in FIG. 11(b), a circular ring-shaped rough surface portion 45 is formed inside the outermost periphery of the flange portion 16. With the rough surface portion 45 formed on the outer periphery of the flange portion 16 in this manner, the formation area of ​​the alignment mark 5 can be clearly identified by a recognition camera.

[0037] Such a rough surface portion 45 is particularly useful when the mark body 7 is formed from metal.This is because if the mask substrate 1 and the mark body 7 are both formed from metal, it can be difficult for a camera to identify and recognize the outermost periphery of the mark body 7. However, if a rough surface portion 45 is formed on the outer periphery of the flange portion 16 of the mark body 7, as in this embodiment, capturing the rough surface portion 45 with a camera makes it easier to identify and recognize the outermost periphery of the mark body 7.

[0038] In this embodiment, the rough surface portion 45 is formed on the outer periphery of the upper flange portion 16, but it may be formed on the entire surface of the marking body 7, including the outer periphery of the upper flange portion 16. Also, the rough surface portion 45 may be formed on the outer periphery of the lower flange portion 17. The rough surface portion 45 may be formed on the outer peripheries of both the upper and lower flange portions 16 and 17.

[0039] In the above embodiments, various shapes of alignment marks have been shown, but the present invention is not limited to those shown in the above embodiments. Specifically, for example, in the first embodiment, the upper half 6a of the mark through-hole 6 is formed into an upwardly diverging bell-mouth shape with a diameter increasing upward. However, the upper half 6a may be formed into an upwardly diverging tapered shape. The lower half 6b may be diverging (a downwardly diverging bell-mouth shape or a downwardly diverging tapered shape). A roughened surface 21 may be formed on a portion of the through-hole body 10 of the mark through-hole 6 in the vertical direction. The alignment mark 5 described in each embodiment may be upside down. In the alignment mark of the present invention, the mark body 7 (mark material) does not have to be completely filled in the mark through-hole 6. Furthermore, the number and positions of alignment marks formed on the mask substrate of the present invention are not limited to those shown in the above embodiment. The number of alignment marks may be one or three or more, and the alignment marks may be positioned within the printing pattern section (pattern area) 3. The shape of the alignment marks formed on the mask substrate of the present invention is not limited to those shown in the above embodiment. They may be formed into polygonal or star shapes, etc. It is desirable that the shape of the alignment marks 5 appearing on the top and bottom surfaces of the mask substrate 1 be different from the shape of the openings of the through holes (mask openings) 2. It is also desirable that the shape of the openings of the mark through holes 6 constituting the alignment marks 5 be different from the shape of the openings of the through holes (mask openings) 2. The mask substrate of the present invention is not limited to those formed by electroforming (plating). The metal mask of the present invention may be prepared by preparing a metal plate and subjecting it to chemical processing (etching), optical processing (laser irradiation), or mechanical processing (drilling, punching) to form through-holes (mask openings) 2 and mark through-holes 6. By adjusting the composition of the etching agent, the laser irradiation level, or the drill shape and rotation speed, a roughened surface (unevenness) can be formed within each through-hole 2 / 6. The metal mask of the present invention may also be provided with a frame on the outer periphery 4 of the mask substrate 1 or on the outer periphery of the mask substrate 1 via a gauze. The mark body (mark material) may be formed from a metal (plating, electrodeposition, welding, etc.).Furthermore, the technology of the present invention is not limited to metal masks for printing, but can also be applied to metal masks such as masks for evaporation, masks for arranging solder balls, and masks for attracting solder balls.

[0040] The diameter dimension of the alignment mark 5 appearing on the upper and lower surfaces of the mask substrate 1 is preferably equal to or greater than the diameter dimension at the opening of the through hole (mask opening) 2 and the diameter dimension at the straight portion extending in the vertical direction of the through hole (mask opening) 2, but it is more preferable to set the diameter dimension of the alignment mark 5 larger than the diameter dimension at the opening of the through hole (mask opening) 2 and the diameter dimension at the straight portion extending in the vertical direction of the through hole (mask opening) 2. [Explanation of symbols]

[0041] 1 Mask substrate 2 Mask opening 5 Alignment marks 6 Mark holes 6a upper half 6b Lower half 7 Mark Body 8 Opening (top) 9 Opening (bottom) 10 Through-hole body 11 Otoribe (upper) 12 Otoribe (lower) 13 Receiving surface (upper) 14 Receiving surface (lower) 15 Columnar part 16 Flange part (upper) 17 Flange part (bottom) 21 Roughened surface 22 Micro-rough surface

Claims

1. An alignment mark (5) formed on a mask substrate (1) having a mask opening (2), The mask substrate (1) comprises a mark through-hole (6) formed through the mask substrate (1) in the thickness direction, ie, the vertical direction, and a mark body (7) filling the mark through-hole (6). The mark through-hole (6) comprises a through-hole body (10) penetrating the mask substrate (1) and having openings (8, 9) on the upper and lower surfaces of the mask substrate (1), and a ring-shaped recessed portion (11, 12) having receiving surfaces (13, 14) oriented in the vertical direction and recessed into at least one of the upper and lower surfaces of the mask substrate (1) so as to surround the openings (8, 9). The marking body (7) comprises a columnar portion (15) corresponding to the through-hole body (10) and flange portions (16, 17) formed to protrude outward from at least one of the upper and lower ends of the columnar portion (15) in correspondence with the recessed portions (11, 12), An alignment mark characterized in that the receiving surfaces (13, 14) of the recessed portions (11, 12) are formed of roughened surfaces (21) having minute irregularities, and the surfaces of the flange portions (16, 17) of the mark body (7) corresponding to the receiving surfaces (13, 14) are formed of minute irregularities (22).

2. 2. An alignment mark according to claim 1, wherein a roughened surface (21) is formed on the inner wall surface of the through-hole body (10), and the outer surface of the columnar portion (15) of the mark body (7) corresponding to this inner wall surface is formed with a finely uneven surface (22).

3. 2. An alignment mark according to claim 1, wherein the upper and lower ends of the through-hole body (10) of the mark through-hole (6) are formed in an expanding shape with a diameter that increases upward or downward.

4. A method for forming an alignment mark (5) on a mask substrate (1) having a mask opening (2), comprising: The alignment mark (5) comprises a mark through-hole (6) formed through the mask substrate (1) in the vertical direction, which is the thickness direction, and a mark body (7) filling the mark through-hole (6); a through-hole forming step of forming a through-hole body (10) having openings (8, 9) on each of the upper and lower surfaces of the mask substrate (1); a recess forming step of recessing ring-shaped recesses (11, 12) having receiving surfaces (13, 14) oriented in the vertical direction on at least one of the upper and lower surfaces of the mask substrate (1) so as to surround the openings (8, 9); a roughening step of forming a roughened surface (21) having minute irregularities on the receiving surfaces (13, 14) of the recessed portions (11, 12); a base material filling step of filling the through-hole body (10) and the recessed portions (11, 12) with a mark base material (34); and a hardening step of hardening the filled mark base material (34) to form a mark body (7).

5. The mask substrate (1) is formed by electroforming, 5. The method for forming an alignment mark according to claim 4, wherein the step of forming the mask substrate (1) by electroforming and the step of forming the through-holes are carried out simultaneously.

6. A metal mask comprising a mask substrate (1) made of a thin metal plate and an alignment mark (5) according to any one of claims 1 to 3 formed on the mask substrate (1).

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