JP7799511B2 - Alignment mark, method for forming alignment mark, and metal mask with alignment mark - Google Patents

Description

The present invention relates to alignment marks for detecting the position and/or orientation of a detection object, a method for forming alignment marks, and a metal mask equipped with alignment marks.

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 consists of a through-hole formed in a mask substrate made of a thin metal plate, penetrating the 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.

Japanese Patent Application Laid-Open No. 2000-71637

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, an anchor effect is exerted on the dye filled into the smaller-diameter holes, 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 using only the anchor effect of the small-diameter holes. Furthermore, deformation such as bending of the mask substrate can cause separation of the contact area between the inner surface of the through-hole and the dye, resulting in the dye falling out. Foreign matter can also enter the separated area, 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, easily causing the dye to fall out of the through-hole and the alignment mark to be inadvertently lost.

The object of the present invention is to prevent the mark body from accidentally falling out of the mark through-hole and 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.

The present invention is directed to an alignment mark 5 formed on 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. A retaining portion 9 that restricts movement of the mark body 7 in the vertical direction is formed on the inner wall of the mark through-hole 6. The mark through-hole 6 is composed of an upper half 6a that tapers downward and widens, the diameter of which gradually increases downward, and a lower half 6b that tapers downward and narrows, the diameter of which gradually decreases downward. Recesses 22 that bulge outward to the left and right are formed inside the mark through-hole 6 at the boundary between the upper and lower halves 6a and 6b and serve as the retaining portions 9. The mark body 7 is composed of an upper part 7a in the shape of a truncated cone expanding downward and filling the upper half part 6a, and a lower part 7b in the shape of a truncated cone narrowing downward and filling the lower half part 6b, and is provided at the center in the vertical direction with an expanded diameter part 23 whose outer diameter dimension is larger than the opening dimensions of the upper and lower openings of the mark through hole 6.

The depth of the upper half portion 6 a is set to half the thickness of the mask substrate 1 .

The metal mask according to the present invention has the above-described alignment marks 5 formed on a mask substrate 1 made of a thin metal plate.

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 is composed of 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 that fills the mark through-hole 6. The method for forming the alignment mark 5 includes a through-hole forming step of forming the mark through-hole 6 in the mask substrate 1, a base material filling step of filling the mark through-hole 6 with a mark base material 16, and a curing step of curing the filled mark base material 16 to form the mark body 7 so as to fill the mark through-hole 6. In the through-hole forming process, an irradiation device 24 is positioned above the mask substrate 1, and laser light is irradiated onto the location on the mask substrate 1 where the alignment mark 5 is to be formed, causing a portion of the mask substrate 1 to disappear and forming a depression 26 which becomes the upper half 6a of the mark through-hole 6.Next, an irradiation device 24 is positioned below the mask substrate 1 and laser light is irradiated onto the mask substrate 1 to partially disappear the lower portion of the mask substrate 1, thereby forming the lower half 6b of the mark through-hole 6 and forming a through-hole 27 which communicates with the depression 26 above. The beam diameter of the laser light irradiated from the irradiation device 24 gradually increases with increasing distance from the irradiation device 24, and the mark through hole 6 formed in the through hole forming process is composed of an upper half 6a that tapers downward and widens downward, the diameter of which gradually increases as it goes downward, and a lower half 6b that tapers downward and narrows downward, the diameter of which gradually decreases as it goes downward, and is characterized in that a recess 22 that serves as a removal prevention portion 9 is formed by bulging outward to the left and right inside the mark through hole 6 at the boundary between the upper and lower halves 6a and 6b.

When a retaining portion 9 that restricts vertical movement of the mark body 7 is formed on the inner wall of the mark through-hole 6, as in the alignment mark 5 of the present invention, the retaining portion 9 can prevent the mark body 7 from accidentally falling out of the mark through-hole 6 and causing the alignment mark 5 to be lost. Therefore, a more reliable alignment mark 5 can be formed on the mask substrate 1.

When the retaining portion 9 is formed by a recess 22 that protrudes outward in the left and right directions from the inner wall of the mark through hole 6 and forms an expanded diameter portion 23 in the mark body 7, the outer shape of the mark body 7 at the expanded diameter portion 23 can be made larger than the inner shape of the opening of the mark through hole 6 on the top and bottom surfaces of the mask substrate 1, thereby restricting the mark body 7 from moving up and down within the mark through hole 6. This prevents the mark body 7 from falling out of the mark through hole 6.

A configuration can be adopted in which mark through-holes 6 are formed in the mask substrate 1 by laser irradiation. For example, when mark through-holes 6 are formed by irradiating the top and bottom surfaces of the mask substrate 1 with laser light 25, the beam diameter of which increases with increasing distance from the irradiation device 24 responsible for laser irradiation, recesses 22 that serve as retention portions 9 and protrude outward to the left and right can be formed in the inner walls of the mark through-holes 6.

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 makes it possible to obtain a metal mask with a more reliable alignment mark, in which the mark body 7 does not accidentally fall out of the mark through-hole 6 and the alignment mark 5 does not disappear.

FIG. 3 is a longitudinal sectional front view of the alignment mark according to the first reference example , and is a cross-sectional view taken along line AA in FIG. 2. FIG. 1 is a perspective view of a metal mask having an alignment mark according to a first reference example . 10A to 10E are diagrams illustrating a method for manufacturing an alignment mark according to a first reference example . FIG. 10 is a vertical sectional front view of an alignment mark according to a second reference example . 10A to 10D are diagrams illustrating a method for manufacturing a mark through-hole that constitutes an alignment mark according to a second reference example . 1 is a vertical sectional front view of an alignment mark according to a first embodiment of the present invention; 5A to 5D are diagrams illustrating a method for manufacturing a mark through-hole that constitutes an alignment mark according to the first embodiment. FIG. 11 is a vertical sectional front view of an alignment mark according to a third reference example . 10A to 10D are diagrams illustrating a method for manufacturing a mark through-hole that constitutes an alignment mark according to a third reference example . 10A and 10B are a longitudinal sectional front view and a plan view of an alignment mark according to a fourth reference example . 10A to 10E are diagrams illustrating a method for manufacturing an alignment mark and a metal mask according to a fifth reference example . FIG. 13 is a vertical sectional front view of an alignment mark according to a sixth reference example . 13A is a vertical sectional front view of an alignment mark according to a seventh reference example , and FIG. 13B is a vertical sectional front view of an alignment mark according to a modified example of the reference example . FIG. 13 is a vertical sectional front view of an alignment mark according to an eighth reference example . FIG. 13 is a vertical sectional front view of an alignment mark according to a ninth reference example . FIG. 23 is a longitudinal sectional front view of an alignment mark according to a tenth reference example . FIG. 23 is a longitudinal sectional front view of an alignment mark according to an eleventh reference example . FIG. 23 is a longitudinal sectional front view of an alignment mark according to a twelfth reference example . 13A and 13B are a longitudinal sectional front view and a plan view of an alignment mark according to a thirteenth reference example . 23A and 23B are a longitudinal sectional front view and a plan view of an alignment mark according to a fourteenth reference example . 14( a ) to 14 ( d ) are diagrams for explaining a method for manufacturing an alignment mark and a metal mask according to a fourteenth reference example . FIG. 23 is a perspective view of an alignment mark according to a fifteenth reference example .

(First Reference Example ) Figures 1 to 3 show a first reference example in which alignment marks are applied to alignment marks on a metal mask for screen printing. In this reference example , the terms "front, back, left, right, top, bottom" refer to the crossed arrows shown in Figures 1 and 2 and the indications near each arrow. As shown in Figure 2, the metal mask is based on a mask substrate 1 made of a thin metal plate formed into a square planar shape. It includes a printing pattern section (pattern area) 3 formed in the center thereof and having a group of numerous through holes (mask openings) 2 for ink paste, which are patterned to form a desired printing pattern, and a rectangular frame-shaped outer peripheral section 4 formed to surround the printing pattern section 3. The metal mask according to this reference example is formed by integrally molding the printing pattern section 3 and the outer peripheral section 4 by electroforming (plating).

Alignment marks 5 used for alignment with the printing substrate are formed at each of the two diagonally positioned corners of the outer periphery 4. As shown in Figure 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 using a camera or the like to distinguish the difference in color tone between the surface of the alignment mark 5 and the surface of the mask substrate 1 around it. To make the alignment marks 5 easier to identify 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 that of the surface of the mask substrate 1.

A retaining portion 9 is formed on the inner wall of the mark through-hole 6 to restrict vertical movement of the mark body 7. As shown in Figure 1, the retaining portion 9 is formed as a convex portion 10 that protrudes inward from the inner wall of the mark through-hole 6. The presence of this convex portion 10 forms a portion 11 with a small diameter (reduced diameter portion) on the mark body 7.

More specifically, as shown in Fig. 2, the upper and lower openings of the mark through-hole 6 facing the upper and lower surfaces of the mask substrate 1 are circular in plan view. Meanwhile, as shown in the cross-sectional view of Fig. 1, the diameter, defined by the lateral spacing between the inner walls of the mark through-hole 6, varies vertically. The mark through-hole 6 in this reference example is composed of an upper half 6a that is narrowed downward and has a bowl-like shape, the diameter of which decreases downward, and a lower half 6b that is widened downward and has a bowl-like shape, the diameter of which increases downward. A convex portion 10 is formed on the inner wall at the boundary between the upper and lower halves 6a and 6b, projecting inward. The upper and lower halves 6a and 6b have substantially the same thickness in the vertical direction, and the convex portion 10 is formed in the vertical center of the inner wall of the mark through-hole 6. The protrusions 10 are formed around the entire periphery from the inner wall, and the diameter defined by the distance between the opposing protrusions 10 is the smallest across the entire mark through-hole 6 in the vertical direction.

The mark through-hole 6 is filled with a resin that will become the mark base material 16 (see FIG. 3(d)), and the resin is cured to form a mark body 7 in the mark through-hole 6. The mark body 7 according to this reference example is composed of an upper portion 7a that is tapered downward and has a hemispherical trapezoidal shape and is formed to fill the upper half portion 6a, and a lower portion 7b that is broadened downward and has a hemispherical trapezoidal shape and is formed to fill the lower half portion 6b. A reduced diameter portion 11 is formed in the vertical center of the mark body 7 in correspondence with the protrusion 10.

With an alignment mark 5 configured as described above, the vertical movement of the mark body 7 is restricted by the convex portion 10 of the mark through-hole 6 engaging with the outer peripheral surfaces located above and below the reduced diameter portion 11 on the mark body 7 side. This prevents the mark body 7 from accidentally falling out of the mark through-hole 6.

For these reasons, the printing metal mask according to this reference example 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.

3A to 3E show a method for manufacturing an alignment mark 5 and a metal mask according to a first reference example . In this reference example , a mask substrate 1 prepared by an electroforming process is etched to form mask through-holes 6 for the alignment marks 5. Specifically, as shown in FIG. 3A, resist films 15 having openings 15a corresponding to the positions where the alignment marks 5 will be formed are first formed on the top and bottom surfaces of the mask substrate 1 prepared by the electroforming process. More specifically, a photoresist layer is applied or laminated to the top and bottom surfaces of the mask substrate 1, and then a pattern film having a pattern corresponding to the openings is adhered to the resist film. The resist film is then baked with an ultraviolet lamp, developed, and dried to form resist films 15 having openings 15a corresponding to the positions where the alignment marks 5 will be formed, as shown in FIG. 3A, on the top and bottom of the mask substrate 1. Next, as shown in FIG. 3( b), an etching process is performed using an etching solution through the opening 15a in the resist film 15 to form recesses that communicate with the opening 15a from the top and bottom of the mask substrate 1. As shown in FIG. 3( c), a mark through-hole 6 is formed, which is composed of a narrowing, bowl-shaped upper half 6a and a widening, bowl-shaped lower half 6b (through-hole forming process). At this time, a protrusion 10 that serves as a retaining portion 9 remains in the vertical center of the inner wall of the mark through-hole 6. After removing the resist film 15, as shown in FIG. 3( d), a mark base material 16 made of resin is filled into 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 17, and the mark base material 16 is filled into the mark through-hole 6 with the lower opening of the mark through-hole 6 closed. Finally, by hardening the mark base material 16 filled in the mark through hole 6, an alignment mark 5 can be formed, which consists of the mark through hole 6 and a mark body 7 consisting of an upper part 7a and a lower part 7b that fill the mark through hole 6, and which has a protrusion 10 on the inner wall of the mark through hole 6 that serves as a removal prevention part 9.

(Second Reference Example ) Figures 4 and 5 show a second reference example of an alignment mark. As shown in Figure 4, the mark through hole 6 constituting the alignment mark 5 according to this reference example differs from the first reference example in that it is composed of an upper half 6a that tapers downward and has a diameter that gradually decreases downward, and a lower half 6b that tapers downward and has a diameter that gradually increases downward. Furthermore, the upper portion 7a of the mark body 7 filling the upper half 6a of the mark through hole 6 is formed in a truncated cone shape that narrows downward, and the lower portion 7b of the mark body 7 filling the lower half 6b of the mark through hole 6 is formed in a truncated cone shape that widens downward. Other points, such as the fact that the mark body 7 is embedded in the mark through hole 6 and that a protrusion 10 that serves as a retaining portion 9 is formed in an inward-protruding shape on the inner wall at the boundary between the upper and lower halves 6a and 6b, are the same as those of the first reference example .

The mark through-holes 6 constituting the alignment marks 5 of this reference example are formed by machining a mask substrate 1 ( FIG. 5( a) ) created by an electroforming process. Specifically, as shown in FIG. 5( b) , a drill 19 is driven from above into the mask substrate 1 at the location where the alignment marks 5 are to be formed, forming drill holes 20 a in the mask substrate 1. Here, cutting is performed until the head of the drill 19 penetrates through to the underside, and the drill holes 20 a thus formed are tapered, narrowing downward. Next, as shown in FIG. 5( c) , the drill 19 is driven from below the mask substrate 1 to form drill holes 20 b on the lower side of the mask substrate 1, tapering upward. It should be noted that the drill holes 20 b can also be formed by driving the drill 19 from above with the mask substrate 1 upside down. As a result, as shown in FIG. 5( d ), a mark through-hole 6 can be formed, which includes an upper half 6a tapered downward and originating from drilled hole 20a, and a lower half 6b tapered downward and originating from drilled hole 20b, and a lower half 6b tapered downward and originating from drilled hole 20b, and the diameter of which gradually increases downward. A protrusion 10 serving as a retaining portion 9 can be formed on the inner wall of the boundary between the upper and lower halves 6a and 6b. Furthermore, by filling the mask substrate 1 with a mark base material 16 (see FIG. 3( d )) and curing it, an alignment mark 5 can be formed, as shown in FIG. 4 , which includes a mark through-hole 6 formed through the mask substrate 1 and a mark body 7 consisting of an upper portion 7a and a lower portion 7b filling the mark through-hole 6, and which includes a protrusion 10 serving as a retaining portion 9 on the inner wall of the mark through-hole 6.

6 and 7 show a first embodiment of an alignment mark according to the present invention. As shown in Fig. 6, the mark through-hole 6 constituting the alignment mark 5 according to this embodiment is composed of an upper half 6a that tapers downward and widens, and a lower half 6b that tapers downward and narrows, and the inner wall of the mark through-hole 6 at the boundary between the upper and lower halves 6a and 6b is formed with a recess 22 that protrudes outward and serves as a retaining portion 9. The mark body 7 is composed of an upper portion 7a that is shaped like a downwardly widening truncated cone and fills the upper half 6a, and a lower portion 7b that is shaped like a downwardly narrowing truncated cone and fills the lower half 6b, and is provided with an expanded diameter portion 23 in the vertical center whose outer diameter is larger than the opening dimensions of the upper and lower openings of the mark through-hole 6. In this embodiment, the outer shape (outer diameter dimension) of the mark body 7 in the expanded diameter portion 23 can be made larger than the inner shape (opening dimension) of the opening of the mark through hole 6 on the upper and lower surfaces of the mask substrate 1, thereby preventing the mark body 7 from falling off from the mark through hole 6.

In this embodiment, the mark through-hole 6 constituting the alignment mark 5 is formed by laser irradiation of a mask substrate 1 (FIG. 7(a)) created by an electroforming process. Specifically, as shown in FIG. 7(b), an irradiation device 24 is positioned above the mask substrate 1, and laser light 25 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 depression 26. Here, the beam diameter of the laser light 25 gradually increases with increasing distance from the irradiation device 24, and the depression 26 formed by laser irradiation has a tapered shape that widens downward. The depth of the depression 26 is set to half the thickness of the mask substrate 1. Next, as shown in FIG. 7(c), an irradiation device 24 is positioned below the mask substrate 1, and laser light is irradiated from below onto the location where the alignment mark 5 is to be formed, thereby partially eliminating the lower portion of the mask substrate 1 and forming a through-hole 27 that communicates with the depression 26 above. The beam diameter of the laser light 25 emitted from the irradiation device 24 at this time gradually increases with increasing distance from the irradiation device 24, as before, and the through-hole 27 formed by the laser irradiation has a tapered shape that narrows downward. As a result, as shown in FIG. 7(d), a mark through-hole 6 can be formed, which is composed of an upper half 6a that tapers upward and originates from the upper depression 26 and whose diameter gradually decreases upward, and a lower half 6b that tapers downward and originates from the lower through-hole and whose diameter gradually decreases downward. It is also possible to form a through-hole 27 that communicates with the depression 26 by irradiating the mask substrate 1 with a laser from above while holding it upside down. Laser irradiation of the mask substrate 1 from both above and below may also be performed to simultaneously form the mark through-hole 6, which consists of the depression 26 and the through-hole 27.

By filling this mark through-hole 6 with a mark base material 16 (see Figure 3(d)) and curing it, an alignment mark 5 can be formed, as shown in Figure 6, which consists of a mark through-hole 6 formed through the mask substrate 1 and a mark body 7 filling this mark through-hole 6, with a recess 22 on the inner wall of the mark through-hole 6 that serves as a removal prevention portion 9.

( Third Reference Example ) FIGS. 8 and 9 show a third reference example of an alignment mark. As shown in FIG. 8 , in the alignment mark 5 according to this reference example , the retaining portion 9 is formed on the inner wall of the mark through-hole 6 by a rough surface portion 30 having minute asperities 29. More specifically, the mark through-hole 6 is a straight hole with a uniform outer diameter in the vertical direction, but the entire inner wall is formed with the rough surface portion 30 having minute asperities 29. The outer periphery of the mark body 7 enters the minute asperities 29 of the rough surface portion 30, and the two (the inner wall of the mark through-hole 6 and the outer periphery of the mark body 7) are engaged with each other by an asperity. The alignment mark 5 according to this reference example , which has the above-described configuration, can improve the frictional engagement force between the two (the inner wall of the mark through-hole 6 and the outer periphery of the mark body 7), thereby restricting the mark body 7 from moving vertically within the mark through-hole 6. This prevents the mark body 7 from falling out of the mark through-hole 6.

The mark through-hole 6 constituting the alignment mark 5 of this reference example is formed by laser irradiation of a mask substrate ( FIG. 9( a) ) prepared by an electroforming process. Specifically, as shown in FIG. 9( b), an irradiation device 24 is disposed above the mask substrate 1, and laser light 25 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 light 25 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, the mask substrate 1 is placed on the workbench 17, a diffusion prism 32 is placed inside the mark through-hole 6, and the irradiation device 24 is again driven to irradiate the laser light 25 onto the diffusion prism 32. The laser light 25 diffused by the diffusion prism 32 is irradiated onto the entire inner wall of the mark through-hole 6, eliminating the surface of the inner wall and forming minute irregularities 29. As a result of the above, as shown in FIG. 9D, a mark through-hole 6 can be formed that has a rough surface portion 30 made up of minute irregularities 29 on the entire inner wall of the straight hole.

Furthermore, by filling this mark through-hole 6 with a mark base material 16 (see Figure 3(d)) and curing it, as shown in Figure 8, an alignment mark 5 can be formed, which consists of a mark through-hole 6 formed through the mask substrate 1 and a mark body 7 filling this mark through-hole 6, and which has a roughened surface portion 30 made of minute irregularities 29 on the inner wall of the mark through-hole 6 that serves as a removal prevention portion 9.

( Fourth Reference Example ) FIG. 10 shows a fourth reference example of an alignment mark. In an alignment mark 5 according to this reference example , the retaining portion 9 is composed of a bridge 34 spanning the inner wall of the mark through-hole 6. More specifically, the mark through-hole 6 is a straight hole with a uniform outer diameter in the vertical direction, but the upper and lower ends of its inner wall are each formed with a bridge 34 shaped like a square in plan view, consisting of two ribs 35 running in the left-right direction and two ribs 35 running in the front-to-back direction. Furthermore, by filling the mark through-hole 6 with a mark base material 16 (see FIG. 3( d)) and curing it, an alignment mark 5 can be formed, as shown in FIG. 10 , which includes the mark through-hole 6 formed through the mask substrate 1 and the mark body 7 filling the mark through-hole 6, and which has bridges 34 serving as the retaining portion 9 on the inner walls of the upper and lower ends of the mark through-hole 6.

When the retaining portion 9 is configured as a bridge 34 that spans the inner wall of the mark through hole 6, the bridge 34 engages with the mark body 7, restricting the mark body 7 from moving up and down within the mark through hole 6. This prevents the mark body 7 from falling out of the mark through hole 6.

11(a) to 11(e) show a manufacturing method of an alignment mark and a metal mask according to the fifth 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. 11(a), a photoresist layer 39 is applied or laminated to the upper surface of a matrix 38. Then, a pattern film 40 having pattern openings 40a corresponding to the mask openings 2 and the mark through-holes 6 is adhered to the matrix 38. After the photoresist layer 39 is baked with an ultraviolet lamp 41, developed, and dried, the unexposed portions are removed. As shown in FIG. 11(b), a resist body 42a corresponding to the mask openings 2 and a resist body 42b corresponding to the mark through-holes 6 are formed on the matrix 38. Next, as shown in FIG. 11(c), these resist bodies 42a and 42b are used to form an electrodeposited layer 43 on the matrix 38 by electroforming. This allows the mask substrate 1 having the mask openings 2 to be formed simultaneously with the formation of the mark through-holes 6. Next, the resist bodies 42a and 42b are dissolved (swelled) and removed, thereby forming the mask substrate 1 having the mask opening 2 and the mark through-hole 6 as shown in FIG. 11(d).

Next, as shown in FIG. 11( e), the mask substrate 1 is placed on the workbench 17, a diffusion prism 32 is placed in the mark through hole 6, and the irradiation device 24 is driven to irradiate the diffusion prism 32 with laser light 25, thereby eliminating the surface of the inner wall of the mark through hole 6 and forming minute irregularities 29. This makes it possible to form a mark through hole 6 having a roughened surface portion 30 consisting of minute irregularities 29 on the entire inner wall of the straight hole, as shown in FIG. 9( d) of the third reference example . Furthermore, by filling this mark through hole 6 with a mark base material 16 (see FIG. 3( d)) and curing it, it is possible to form an alignment mark 5, as shown in FIG. 8, which is composed of the mark through hole 6 formed through the mask substrate 1 and the mark body 7 filling this mark through hole 6, and which has a roughened surface portion 30 consisting of minute irregularities 29 that serves as a removal prevention portion 9 on the inner wall of the mark through hole 6.

( Sixth Reference Example ) FIG. 12 shows a sixth reference example of an alignment mark 5. In this reference example , the inner wall of the mark through hole 6 constituting the alignment mark 5 is bell-mouth shaped, with a curved surface formed by bulging inward in both left and right directions. The most inwardly bulging portion of the inner wall of the mark through hole 6 is a protrusion 10 that serves as the retaining portion 9. The mark body 7 filling the mark through hole 6 is small-drum shaped, with the outer diameter of the vertical center being smaller than the outer diameters of both vertical ends. A reduced-diameter portion 11 is formed in the vertical center of the mark body 7. As described above, the protrusion 10 on the mark through hole 6 engages with the reduced-diameter portion 11 on the mark body 7, restricting vertical movement of the mark body 7 within the mark through hole 6 and preventing the mark body 7 from accidentally falling out of the mark through hole 6.

13A shows a seventh reference example of an alignment mark 5. In this reference example , the upper half 6a of the mark through-hole 6 is formed in a tapered bell-mouth shape 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 that of the lower half 6b, and the lowermost part of the upper half 6a is formed with a protrusion 10 serving as a retaining portion 9 extending inward in the left and right directions, and a downward-facing receiving surface 45 is formed around the boundary between the upper half 6a and the lower half 6b. The mark body 7 filling the mark through-hole 6 is formed in a tapered, bottomed 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. A reduced diameter portion 11 having a small outer diameter is formed at the lower end of the upper portion 7a in correspondence with the protrusion 10 of the mark through-hole 6. A ring-shaped cylindrical end surface 48 is formed at the upper end of the lower portion 7b so as to protrude outward from the lower end of the upper portion 7a.

13(b) shows an alignment mark according to a modified example of the seventh reference example , in which the diameter (d1) of the receiving surface 45, defined by the inner wall of the lowermost portion 6a of the upper half 6a and the inner wall of the uppermost portion 6b of the mark through-hole 6, is set to be the same as the height (d2) of the upper half 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 a 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.

In the alignment mark 5 configured as described above, the reduced diameter portion 11 of the mark body 7 is received by the convex portion 10 of the mark through hole 6, restricting downward movement of the mark body 7. Furthermore, the cylindrical end surface 48 of the mark body 7 is received by the receiving surface 45 of the mark through hole 6, restricting upward movement of the mark body 7. As a result, vertical movement of the mark body 7 within the mark through hole 6 can be restricted, preventing the mark body 7 from accidentally falling out of the mark through hole 6.

( Eighth Reference Example ) Figure 14 shows an eighth reference example of an alignment mark 5. In this reference example , the upper half 6a of the mark through-hole 6 is formed in a bowl shape tapering downward, with the angle of inclination of the inner wall decreasing downward, while the lower half 6b is formed in a tapered shape with a uniform angle of inclination of the inner wall expanding downward. A protrusion 10 that protrudes inward and serves as a retaining portion 9 is formed on the inner wall at the boundary between the upper and lower halves 6a and 6b. The mark body 7 filling the mark through-hole 6 has an upper portion 7a formed in a hemispherical truncated shape tapering downward, with the angle of inclination of the outer periphery decreasing downward, and a lower portion 7b formed in a truncated cone shape expanding downward. Corresponding to the protrusion 10 of the mark through-hole 6, a reduced diameter portion 11 with a small outer diameter is formed at the boundary between the upper and lower portions 7a and 7b.

In the alignment mark 5 configured as described above, the reduced diameter portion 11 of the mark body 7 is received by the convex portion 10 of the mark through-hole 6, restricting the vertical movement of the mark body 7. As a result, the vertical movement of the mark body 7 within the mark through-hole 6 can be restricted, preventing the mark body 7 from accidentally falling out of the mark through-hole 6.

( Ninth Reference Example ) Figure 15 shows a ninth reference example of an alignment mark 5. In this reference example , the upper half 6a of the mark through-hole 6 is formed in a bell-mouth shape that narrows downward, with the angle of inclination of the inner wall increasing downward, while the lower half 6b is formed in a tapered shape with a uniform angle of inclination of the inner wall that widens downward. A protrusion 10 that protrudes inward and serves as a retaining portion 9 is formed on the inner wall at the boundary between the upper and lower halves 6a and 6b. The mark body 7 filling the mark through-hole 6 has an upper portion 7a that is formed in a tapered shape with a concave curved surface whose outer periphery has an angle of inclination that increases downward, while the lower portion 7b is formed in a truncated cone shape that widens downward. Corresponding to the protrusion 10 of the mark through-hole 6, a reduced diameter portion 11 with a small outer diameter is formed at the boundary between the upper and lower portions 7a and 7b.

In the alignment mark 5 configured as described above, the reduced diameter portion 11 of the mark body 7 is received by the convex portion 10 of the mark through-hole 6, restricting the vertical movement of the mark body 7. As a result, the vertical movement of the mark body 7 within the mark through-hole 6 can be restricted, preventing the mark body 7 from accidentally falling out of the mark through-hole 6.

10th Reference Example : Fig. 16 shows a 10th reference example of an alignment mark. This reference example differs from the first reference example in that a cylindrical straight portion 51 with a uniform diameter in the vertical direction is formed between the upper half portion 6a, which is a bowl-shaped portion tapering downward, and the lower half portion 6b, which is a bowl-shaped portion tapering downward, that constitutes the mark through- hole 6. The inner peripheral portion of this straight portion 51 is formed as a convex portion 10 that serves as a retaining portion 9 that protrudes inward. The mark body 7 that fills the mark through-hole 6 is composed of a hemispherical trapezoidal upper portion 7a that narrows downward and fills the upper half portion 6a, a cylindrical portion 52 that serves as a reduced-diameter portion 11 that fills the straight portion 51, and a hemispherical trapezoidal lower portion 7b that widens downward and fills the lower half portion 6b .

17 shows an alignment mark according to the 11th embodiment . This embodiment differs from the 10th embodiment in that both the upper half 6a and the lower half 6b constituting the mark through-hole 6 are straight openings with uniform diameters in the vertical direction, and that both the upper part 7a and the lower part 7b constituting the mark body 7 filling the mark through-hole 6 are cylindrical.

18 shows a twelfth embodiment of an alignment mark. This embodiment differs from the eleventh embodiment in that the straight portion 51 constituting the mark through-hole 6 is formed to protrude outward from the inner wall of the upper and lower halves 6a and 6b to form a recess 22 (retaining portion 9), and the cylindrical portion 52 of the mark body 7 filling the straight portion 51 is formed as an expanded diameter portion 23.

(Third Reference Example ) Figure 19 shows a thirteenth reference example of an alignment mark. In this reference example , the inner periphery of the mark through hole 6 is formed in a polygonal shape with numerous continuous irregularities 54 in a plan view, and the outer periphery of the mark body 7 filling the mark through hole 6 is formed in a plan view with numerous irregularities 55. The inner diameter dimension of the mark through hole 6 does not change in the vertical direction, and the mark body 7 filling the mark through hole 6 is a polygonal cylinder with irregularities on the outer periphery. With the alignment mark 5 configured as described above, the contact area between the mark through hole 6 and the mark body 7 can be increased by the amount of the irregularities 54, 55 formed on the inner and outer peripheries, thereby increasing the frictional engagement force, compared to when the mark through hole 6 is a straight hole with a perfect circular inner periphery in a plan view and the mark body 7 is a cylindrical body with a uniform diameter. As a result, the projections and recesses 54 and 55 function as a retaining portion 9 to restrict the vertical movement of the mark body 7 within the mark through hole 6, thereby preventing the mark body 7 from accidentally falling out of the mark through hole 6.

( Fourteenth Reference Example ) Figures 20 and 21 show a fourteenth reference example of an alignment mark. As shown in Figure 20, the inner periphery of the mark through-hole 6 of this reference example has countless minute irregularities 54 formed in a continuous circle in a plan view. That is, this reference example differs from the thirteenth reference example in that the number of irregularities 54 formed in the inner periphery of the mark through-hole 6 is significantly greater than that of the thirteenth reference example, the amplitude (irregularity width) of each irregularity 54 is significantly smaller than that of the thirteenth reference example , and the inner periphery of the mark through-hole 6 is formed in a circular shape in a plan view . The outer periphery of the mark body 7 filling the mark through-hole 6 has countless irregularities 55 formed in a plan view. The inner diameter dimension of the mark through-hole 6 does not change in the vertical direction, and the mark body 7 filling the mark through-hole 6 is cylindrical with irregularities on the outer periphery.

The alignment mark 5 described above can be obtained by forming minute irregularities on the outer periphery of the resist body 42b used to create the mask substrate 1 by electroforming. Specifically, as shown in FIG. 21(a), a photoresist layer 39 is applied or laminated to the upper surface of the matrix 38, and then a pattern film 40 having pattern openings 40a corresponding to the mask openings 2 and the mark through-holes 6 is adhered to the upper surface. The resist film 40 is then baked (exposed) with an ultraviolet lamp 41, developed, and dried. The unexposed portions are then removed, forming a resist body 42a corresponding to the mask openings 2 and a resist body 42b corresponding to the mark through-holes 6 on the matrix 38, as shown in FIG. 21(b). By forming minute irregularities on the inner periphery of the pattern openings 40a corresponding to the mark through-holes 6, a minute irregularity 58 can be formed on the outer periphery of the resist body 42b corresponding to the mark through-holes 6, as shown in FIG. 21(b). Next, as shown in FIG. 21(c), these resist bodies 42a and 42b are used to form an electrodeposited layer 43 on a matrix 38 by electroforming. Then, only the resist body 42a is dissolved (swelled) and removed, leaving the resist body 42b. This forms an alignment mark 5, as shown in FIG. 20, which includes a mark through-hole 6 that penetrates the mask substrate 1 and has countless minute irregularities 54 on its inner wall that serve as retention portions 9, and a mark body 7 derived from the resist body 42b that fills the mark through-hole 6 and has countless irregularities 55 on its outer periphery (outer peripheral surface). Alternatively, the alignment mark 5 can be formed by dissolving (swelling) and removing both resist bodies 42a and 42b, and filling the mark through-hole 6 with a mark matrix material.

( 15th Reference Example ) Figure 22 shows a 15th reference example of an alignment mark. In this reference example , a heat-shielding structure is formed around the alignment mark 5. The heat-shielding structure is composed of a ring-shaped (annular) groove 61 recessed into the upper surface of the mask substrate 1 so as to surround the alignment mark 5, and a flat surface 62 formed between the outer edge of the alignment mark 5 and the groove 61. In this way, by providing a heat-shielding structure around the alignment mark 5, heat generated when forming the mark through-hole 6 and the rough surface portion 30 by irradiating with laser light can be prevented from spreading around the mask substrate 1, thereby preventing deformation of the mask substrate 1 when irradiated with laser light. Note that the shape of the groove 61 is not limited to annular, and it may also be a square (polygonal) frame shape.

While the above embodiments illustrate alignment marks of various shapes, the present invention is not limited to these. Specifically, for example, in the first embodiment, the upper and lower halves 6a and 6b of the mark through-hole 6 have substantially the same vertical thickness. However, the upper and lower halves 6a and 6b may have a larger vertical thickness than the other, and the retaining portion 9 (protrusion 10) may be biased to one side of the mask substrate 1 in the vertical direction. The retaining portion 9 (protrusion 10) may also be intermittently formed in the circumferential direction on the inner wall of the mark through-hole 6. In the fifth embodiment, the bridges 34 are provided at both the upper and lower ends of the inner wall of the mark through-hole 6. However, the bridges 34 may be formed only at the upper or lower ends, or may be formed midway up or down the mark through-hole 6. In the seventh embodiment, a straight hole may be formed midway through the inner wall (curved surface) of the mark through-hole 6, forming a straight portion midway through the mark body 7. In the eighth embodiment, a straight hole may be formed at the bottom of the upper half 6a of the mark through-hole 6, and a straight cylindrical portion may be formed between the upper portion 7a and lower portion 7b of the mark body 7. This 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 creating a mask substrate 1 by electroforming. In the ninth or tenth embodiment, the lower half 6b of the mark through-hole 6 may be a straight cylindrical portion or may taper downward. Various other embodiments of the present invention are possible, such as combinations of the retaining portions 9 of each embodiment. However, the key is that the retaining portion 9 that restricts vertical movement of the mark body 7 is formed on the inner wall of the mark through-hole 6.

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 completely fill the mark through-hole 6. Furthermore, the number and position of the alignment marks formed on the mask substrate of the present invention are not limited to those described in the above embodiments. 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 described in the above embodiments. They may be polygonal, star-shaped, or other shapes. 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 mark 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 have a frame attached to the outer periphery 4 of the mask substrate 1 or to the outer periphery of the mask substrate 1 via a gauze. The marking body (marking material) may be formed from metal (plating, electrodeposition, welding, etc.). Furthermore, the technology of the present invention is not limited to metal masks for printing; it can also be applied to metal masks for evaporation, solder ball arrays, and solder ball suction.

The diameter of the alignment mark 5 appearing on the top and bottom surfaces of the mask substrate 1 is preferably equal to or greater than the diameter of the opening of the through hole (mask opening) 2 and the diameter of the straight portion extending vertically of the through hole (mask opening) 2; however, it is more desirable for the diameter of the alignment mark 5 to be set larger than the diameter of the opening of the through hole (mask opening) 2 and the diameter of the straight portion extending vertically of the through hole (mask opening) 2.

REFERENCE SIGNS LIST 1 mask substrate 2 mask opening 5 alignment mark 6 mark through-hole 7 mark body 9 retaining portion 10 convex portion 16 mark base material 22 concave portion 29 minute concave and convex portions 30 rough surface portion 34 bridge body

Claims (4)

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).
A retaining portion (9) is formed on the inner wall of the mark through-hole (6) to restrict the mark body (7) from moving in the vertical direction.
The mark through hole (6) is composed of an upper half portion (6a) tapered downwards, the diameter of which gradually increases downwards, and a lower half portion (6b) tapered downwards, the diameter of which gradually decreases downwards, and a recess (22) that bulges outward to the left and right and serves as a retaining portion (9) is formed inside the mark through hole (6) at the boundary between the upper and lower halves (6a, 6b).
The alignment mark is characterized in that the mark body (7) comprises an upper part (7a) in the shape of a downwardly expanding truncated cone filling the upper half part (6a) and a lower part (7b) in the shape of a downwardly narrowing truncated cone filling the lower half part (6b), and is provided with an expanded diameter part (23) in the vertical center part, the outer diameter of which is larger than the opening dimensions of the upper and lower openings of the mark through hole (6) . 2. The alignment mark according to claim 1 , wherein the depth of the upper half (6a) is set to half the thickness of the mask substrate (1) . 3. A metal mask comprising a mask substrate (1) made of a thin metal plate and an alignment mark (5) according to claim 1 or 2 formed on the mask substrate (1). 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 mark through-hole (6) in a mask substrate (1);
a base material filling step of filling the mark through-hole (6) with a mark base material (16);
a hardening step of hardening the filled mark base material (16) to form a mark body (7) so as to fill the mark through-hole (6),
In the through-hole forming step, an irradiation device (24) is disposed above the mask substrate (1), and a laser beam is irradiated onto the mask substrate (1) at a location where the alignment mark (5) is to be formed, thereby eliminating a portion of the mask substrate (1) and forming a depression (26) that will become the upper half (6a) of the mark through-hole (6); next, an irradiation device (24) is disposed below the mask substrate (1), and a laser beam is irradiated onto the mask substrate (1), thereby partially eliminating the lower portion of the mask substrate (1), thereby forming the lower half (6b) of the mark through-hole (6) and forming a through-hole (27) that communicates with the depression (26) above;
The beam diameter of the laser light emitted from the irradiation device (24) gradually increases with increasing distance from the irradiation device (24),
A method for forming an alignment mark, characterized in that the mark through hole (6) formed in the through hole forming process is composed of an upper half (6a) that tapers downward and widens downward, the diameter of which gradually increases downward, and a lower half (6b) that tapers downward and narrows downward, the diameter of which gradually decreases downward, and a recess (22) that bulges outward to the left and right and serves as a removal prevention portion (9) is formed inside the mark through hole (6) at the boundary between the upper and lower halves (6a, 6b).