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

Abstract

To obtain an alignment mark that is difficult to disappear and excellent in reliability.SOLUTION: The present invention targets alignment marks formed on a mask substrate 1 equipped with a mask opening 2. The alignment mark 8 is composed of: an opening 9 composed of an upward widening or straight hole that is formed to penetrate in a vertical direction as a thickness direction of the mask substrate 1, or of an upward widening or straight recess that is formed dented on an upper surface 5 of the mask substrate 1; and a rough surface region 12 composed of a rough surface having the surface roughness different from the surface roughness of the upper surface 5 of the mask substrate 1, and formed circumferentially on at least a part of an inner surface 10 of the opening 9.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an alignment mark for detecting the position and orientation 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 an opening (through hole) formed in a mask substrate made of a thin metal plate in the plate thickness direction, and a dye filled in this opening. The opening is a stepped hole having a large diameter hole and a small diameter hole, which are straight holes. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2000-71637 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the metal mask of Patent Document 1, the optical contrast generated on the surface of the mask substrate due to the presence or absence of dye is captured as an alignment mark by a CCD camera, making it possible to detect the position and posture of the metal mask to be detected. However, since the alignment mark in Patent Document 1 is formed by filling an opening with a filler (dye), there is a risk that the filler will fall out of the opening when the mask substrate is deformed, such as flexed or bent, or when the mask substrate is cleaned, and the alignment mark will disappear, leaving room for improvement in terms of its lack of reliability.

[0005] An object of the present invention is to obtain an alignment mark that is unlikely to disappear and has excellent reliability. Another object of the present invention is to provide a method for forming the above-mentioned alignment mark and a metal mask provided with the alignment mark. [Means for solving the problem]

[0006] The present invention is directed to an alignment mark formed on a mask substrate 1 having a mask opening 2. The alignment mark 8 is characterized by comprising an opening 9 consisting of an upwardly expanding or straight hole formed penetrating the mask substrate 1 in the vertical direction, which is the thickness direction, and a rough surface region 12 consisting of a rough surface having a different surface roughness from the surface roughness of the upper surface 5 of the mask substrate 1 and formed in a circumferential shape on at least a part of the inner surface 10 of the opening 9.

[0007] The present invention is directed to an alignment mark formed on a mask substrate 1 having a mask opening 2. The alignment mark 8 is characterized by comprising an opening 9 formed as an upwardly expanding or straight recess recessed into the upper surface 5 of the mask substrate 1, and a roughened surface region 12 formed in a circumferential shape on at least a part of an inner surface 10 of the opening 9 and consisting of a rough surface having a different surface roughness from that of the upper surface 5 of the mask substrate 1.

[0008] The rough surface region 12 is composed of a first rough surface portion 20 formed in a circular shape on the inner surface 10 of the opening 9, and a second rough surface portion 21 formed in a circular shape so as to surround the upper opening 16 of the opening 9.

[0009] The first rough surface portion 20 and the second rough surface portion 21 are formed continuously across the upper opening 16 of the opening portion 9 .

[0010] A throttle wall 43 is formed in a vertical midway portion of the opening 9 so as to protrude circumferentially from the inner surface 10 toward the axis of the opening 9. A rough surface region 12 is formed on an upper surface 43a of the throttle wall 43.

[0011] The present invention is directed to a method for forming an alignment mark on a mask substrate 1 having a mask opening 2. The method is characterized by comprising an opening forming step of penetrating an opening 9 consisting of an upwardly expanding or straight hole in the vertical direction, which is the thickness direction of the mask substrate 1, or forming an opening 9 consisting of an upwardly expanding or straight recess in the upper surface 5 of the mask substrate 1, and a surface roughening step of irradiating at least a part of the inner surface 10 of the opening 9 with laser light to form a circumferential roughened surface region 12 consisting of a rough surface having a surface roughness different from the surface roughness of the upper surface 5 of the mask substrate 1.

[0012] The metal mask according to the present invention is characterized in that the above-mentioned alignment marks 8 are formed on a mask substrate 1 made of a thin metal plate. Effect of the Invention

[0013] In the present invention, the alignment mark 8 is constituted by an opening 9 formed of an upwardly spreading or straight hole penetrating the mask substrate 1 in the vertical direction, which is the thickness direction, and a rough surface area 12 formed in a circular shape on at least a part of the inner surface 10 of the opening 9, which is made of a rough surface having a surface roughness different from that of the upper surface 5 of the mask substrate 1. When the opening 9 formed of an upwardly spreading or straight hole is formed penetrating the mask substrate 1 in the vertical direction, which is the thickness direction, in this way, a circular or polygonal annular shape originating from the inner surface 10 of the opening 9 can be made to appear on the upper surface 5 of the mask substrate 1 in a plan view. In addition, as in the present invention, when the rough surface area 12 made of a rough surface having a surface roughness different from that of the upper surface 5 of the mask substrate 1 is formed in a circular shape on at least a part of the inner surface 10 of the opening 9, a contrast is generated between the rough surface area 12 and the upper surface 5 of the mask substrate 1 due to the difference in reflectance caused by the difference in surface roughness between the rough surface area 12 and the upper surface 5 of the mask substrate 1, and a ring pattern can be clearly made to appear on the inner surface 10 of the opening 9. Furthermore, the inner pattern surrounded by the annular pattern derived from the rough surface region 12 (the through region of the opening 9 inside the rough surface region 12) can be clearly made to appear. Therefore, according to the present invention, the position and posture of the mask substrate 1 can be detected by capturing the annular pattern derived from the rough surface region 12 or the inner shape surrounded by this annular pattern with a CCD camera or the like, in other words, the alignment mark 8 can be formed on the mask substrate 1. As described above, in the present invention, the alignment mark 8 is formed by the opening 9 made of a through hole and the rough surface region 12 formed in a circumferential shape on at least a part of the inner surface 10 of the opening 9, so that there is no risk of the mark disappearing due to the dropout of the dye as the filler, as in the conventional alignment mark in which the opening is filled with a dye, and therefore an alignment mark 8 that is less likely to disappear and has excellent reliability can be obtained. [Brief description of the drawings]

[0014] [Figure 1] 3 is a longitudinal sectional front view of the alignment mark according to the first embodiment of the present invention, and a sectional view taken along line AA in FIG. 2. [Diagram 2]FIG. 1 is a perspective view of a metal mask provided with alignment marks according to a first embodiment. [Diagram 3] 1(a) to 1(e) are diagrams illustrating a method for manufacturing a metal mask provided with alignment marks according to a first embodiment. [Figure 4] FIG. 11 is a vertical sectional front view of an alignment mark according to a second embodiment of the present invention. [Diagram 5] 13(a) to 13(c) are diagrams illustrating a method of forming an alignment mark according to a second embodiment. [Figure 6] FIG. 11 is a vertical sectional front view of an alignment mark according to a third embodiment of the present invention. [Figure 7] 13A to 13C are views for explaining a surface roughening treatment step in the alignment mark formation method according to the third embodiment. [Figure 8] FIG. 13 is a vertical sectional front view of an alignment mark according to a fourth embodiment of the present invention. [Figure 9] FIG. 13 is a vertical sectional front view of an alignment mark according to a fifth embodiment of the present invention. [Figure 10] FIG. 13 is a vertical sectional front view of an alignment mark according to a sixth embodiment of the present invention. [Figure 11] FIG. 13 is a vertical sectional front view of an alignment mark according to a seventh embodiment of the present invention. [Figure 12] 13A and 13B are a vertical sectional front view and a plan view of an alignment mark according to an eighth embodiment of the present invention. [Figure 13] FIG. 13 is a perspective view of an alignment mark according to a ninth embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] (First embodiment) FIGS. 1 to 3 show a first embodiment in which the alignment mark according to the present invention is applied to an alignment mark of a metal mask for screen printing. In this embodiment, the front, rear, left, right, and up and down refer to the crossed arrows shown in FIGS. 1 and 2 and the indications of front, rear, left, right, and up and down written near each arrow. As shown in FIG. 2, the metal mask is based on a mask substrate 1 made of a metal thin plate formed in a square shape in a plane shape, and includes a printing pattern part (pattern area) 3 having a group of a large number of mask openings 2 for ink paste formed in the center, and a rectangular frame-shaped outer peripheral part 4 formed to surround the printing pattern part 3. In the printing pattern part 3, the mask openings 2 are patterned to a desired printing pattern. The metal mask according to this embodiment is formed by integrally forming the printing pattern part 3 and the outer peripheral part 4 by electroforming (plating).

[0016] As shown in Fig. 2, alignment marks 8 used for alignment with a print target (workpiece) are formed at two diagonally opposite corners of the outer peripheral portion 4 of the mask substrate 1. As shown in Fig. 1, each alignment mark 8 is composed of an opening 9 formed as an upwardly expanding or straight hole penetrating the mask substrate 1 in the vertical direction, which is the thickness direction of the mask substrate 1, and a rough surface region 12 formed in a circumferential shape on at least a part of an inner surface 10 of the opening 9, which is made of a rough surface having a different surface roughness from that of the upper surface 5 of the mask substrate 1. The alignment marks 8 are recognized by capturing an image of the upper surface 5 of the mask substrate 1 including the alignment marks 8 with a CCD camera.

[0017] 1, the opening 9 in this embodiment is composed of a mark through hole 15 formed to penetrate in the up-down direction, which is the thickness direction of the mask substrate 1. Specifically, the mark through hole 15 has an upper opening 16 and a lower opening 17 on each of the upper and lower surfaces of the mask substrate 1, and is composed of an expanded diameter portion 18 formed in an upwardly expanding bell-mouth shape whose diameter dimension increases from a vertical midpoint toward the upper opening 16, and a constant diameter portion 19 formed in a straight shape with a uniform diameter dimension from the lower end of the expanded diameter portion 18 toward the lower opening 17. The planar shape of the upper and lower openings 16 and 17 is formed to be circular.

[0018] On the inner surface 10 of the mark through hole 15, the expanded diameter portion 18 is roughened by forming minute irregularities 20a over its entire surface, and the minute irregularities 20a form a first rough surface portion 20 in the expanded diameter portion 18. Also, on the upper surface 5 of the mask substrate 1, the periphery of the mark through hole 15 is roughened by forming minute irregularities 21a so as to surround the upper opening 16, and the minute irregularities 21a form a second rough surface portion 21 in a circular ring shape on the upper surface 5 of the mask substrate 1. These two rough surface portions 20 and 21 are formed continuously across the upper opening 16 of the mark through hole 15, and the rough surface region 12 is formed by the two rough surface portions 20 and 21. The rough surface portions 20 and 21 are formed to have the same surface roughness by the minute irregularities 20a and 21a, and the surface roughness of the rough surface region 12 (first rough surface portion 20 and second rough surface portion 21) is formed to be rougher (a different surface roughness from) the surface roughness of the upper surface 5 of the mask substrate 1 formed by electroforming (plating). It is preferable that the rough surface portions 20 and 21 (minute irregularities 20a and 21a) have the same surface roughness, but it is sufficient that the surface roughness of the rough surface region 12 (rough surface portions 20 and 21) is different from the surface roughness of the upper surface 5 of the mask substrate 1, and the surface roughness of the first rough surface portion 20 (minute irregularities 20a) and the second rough surface portion 21 (minute irregularities 21a) may be different.

[0019] As described above, the mark through hole 15 (opening 9) consisting of an upwardly expanding hole is formed penetrating the mask substrate 1 in the vertical direction, which is the thickness direction, so that in a plan view, a circular annular shape resulting from the inner surface 10 (expanded diameter portion 18 and constant diameter portion 19) of the mark through hole 15 can be made to appear on the upper surface 5 of the mask substrate 1. In addition, the rough surface region 12 consisting of a rough surface having a surface roughness different from that of the upper surface 5 of the mask substrate 1 is formed in a circumferential shape by the first rough surface portion 20 and the second rough surface portion 21. Due to the difference in reflectance caused by the difference in surface roughness between the rough surface region 12 and the upper surface 5 of the mask substrate 1, a contrast is generated between the rough surface region 12 and the upper surface 5 of the mask substrate 1, so that an annular pattern can be clearly made to appear around the inner surface 10 of the mark through hole 15 and the upper opening 16. Furthermore, an inner pattern surrounded by the annular pattern resulting from the rough surface region 12 (the through region of the opening 9 inside the rough surface region 12) can be clearly made to appear.

[0020] In this embodiment, the rough surface area 12 (first rough surface area 20) is formed on the entire surface of the enlarged diameter portion 18 of the mark through hole 15, and the rough surface area 12 (second rough surface area 21) in the shape of a circular ring is formed around the upper opening 16, so that a circular ring-shaped annular pattern originating from the rough surface area 12 can be produced. In addition, the inner pattern surrounded by the annular pattern is a circular pattern with the diameter dimension of the lower end of the enlarged diameter portion 18, i.e., the lower opening 17. Therefore, according to this embodiment, by capturing the annular pattern originating from the rough surface area 12 or the inner shape surrounded by this annular pattern with a CCD camera or the like, it is possible to detect the position and attitude of the mask substrate 1, in other words, it is possible to form an alignment mark 8 on the mask substrate 1.

[0021] Since the rough surface area 12 is composed of a first rough surface portion 20 formed in a circumferential shape on the inner surface 10 of the opening 9 and a second rough surface portion 21 formed in a circumferential shape so as to surround the upper opening 16 of the opening 9, the width dimension of the rough surface area 12 in the radial direction of the opening 9 can be increased, and the width dimension of the annular pattern derived from the rough surface area 12 can be increased, compared to a form in which the rough surface area 12 is formed only on the inner surface 10 of the opening 9. This increases the contrast between the rough surface area 12 and the upper surface 5 of the mask substrate 1, making the annular pattern appear more clearly inside and outside the opening 9, and therefore makes the annular pattern and the inner shape surrounded by the annular pattern more prominent. Therefore, an alignment mark 8 with better discrimination can be obtained.

[0022] Since the first rough surface portion 20 and the second rough surface portion 21 are formed continuously across the upper opening 16 of the opening 9, the two rough surface portions 20 and 21 can be integrated to make the annular pattern appear more clearly inside and outside the opening 9. This makes it possible to make the annular pattern originating from the rough surface region 12 and the inner shape surrounded by this annular pattern more prominent, thereby making it possible to obtain an alignment mark 8 with better discrimination.

[0023] According to a metal mask having an alignment mark 8 as described above formed on a mask substrate 1 made of a thin metal plate, there is no risk of the mark disappearing due to the fall-off of the dye filler, as occurs with conventional alignment marks formed by filling an opening with a dye or the like, and it is possible to obtain a metal mask having an alignment mark 8 which is less likely to disappear and has excellent reliability.

[0024] 3(a) to (e) show a manufacturing method of the alignment mark 8 and the 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 15 (openings 9) (openings forming process) are performed simultaneously. In detail, as shown in FIG. 3(a), a photoresist layer 27 is applied or laminated on the upper surface of a mother mold 26, and then a pattern film 28 having pattern openings 28a corresponding to the mask openings 2 and the mark through-holes 15 is adhered thereto, and each process of baking (exposure) with an ultraviolet lamp 29, developing, and drying is performed, and then the unexposed portion is removed, so that a pattern resist 30 consisting of a resist body 30a corresponding to the mask openings 2 and a resist body 30b corresponding to the mark through-holes 15 is formed on the mother mold 26 as shown in FIG. 3(b).

[0025] Next, as shown in FIG. 3(c), the resist bodies 30a and 30b are used to form an electrodeposited layer 31 on the matrix 26 by electroforming (plating). As a result, the mask substrate 1 having the mask opening 2 can be formed and the mark through-hole 15 (opening 9) can be formed at the same time (opening forming step). That is, the mask substrate 1, the mark through-hole 15, and the mask opening 2 can be formed simultaneously. The electrodeposited layer 31 is formed within the height range of the pattern resist 30, so that the mark through-hole 15 is formed as a through-hole. At this time, the current density in the vicinity of the periphery of the resist bodies 30a and 30b is reduced, so that the upper portions of the mask opening 2 and the mark through-hole 15 have an upwardly expanding bell-mouth shape with a diameter dimension increasing toward the top. Next, the resist bodies 30a and 30b are dissolved (swelled) and removed, and the electrodeposited layer 31 is peeled off from the matrix 26, so that the mask substrate 1 having the mask opening 2 and the mark through-hole 15 can be formed as shown in FIG. 3(d).

[0026] Next, as shown in FIG. 3(e), an irradiation device 32 is disposed above the mask substrate 1, and a laser beam 33 consisting of parallel light with no change in beam diameter is irradiated onto the inner surface 10 of the mark through-hole 15 and the upper surface 5 of the mask substrate 1 surrounding the mark through-hole 15, with the mark through-hole 15 at the center. By irradiation with this laser beam 33, the surface of the enlarged diameter portion 18 of the mark through-hole 15 disappears or melts and solidifies, forming minute irregularities 20a in the portion irradiated with the laser beam 33. At the same time, in the mask substrate 1, a part of the upper surface 5 around the upper opening 16 disappears or melts and solidifies, forming minute irregularities 21a in the portion irradiated with the laser beam 33. By these minute irregularities 20a and 21a formed by irradiation with the laser beam 33, a first rough surface portion 20 is formed in the enlarged diameter portion 18 of the mark through-hole 15, and a second rough surface portion 21 is formed on the upper surface 5 of the mask substrate 1 (roughening process). Since the upper surface 5 of the mask substrate 1 consisting of the electroformed surface is formed to have a smooth surface texture, the surface roughness of the roughened region 12 is formed to be rougher (greater) than the surface roughness of the upper surface 5 of the mask substrate 1. Note that with the straight laser beam 33, the constant diameter portion 19 of the mark through-hole 15 is not irradiated with the laser beam 33, and therefore minute irregularities are not formed in the constant diameter portion 19.

[0027] In the method of forming alignment mark 8 of the present embodiment, since rough surface region 12 is formed by irradiation with laser light 33, it is possible to form rough surface region 12 more easily than in a method of forming rough surface region 12 by cutting or the like. In addition, the unevenness of rough surface region 12 can be adjusted simply by controlling the output of the laser light, and this method is also excellent in that the surface roughness of rough surface region 12 can be easily controlled.

[0028] (Second embodiment) FIGS. 4 and 5 show a second embodiment of the alignment mark according to the present invention. As shown in FIG. 4, the shape of the mark through-hole 15 (opening 9) of the alignment mark 8 according to this embodiment is different from that of the first embodiment. Specifically, the mark through-hole 15 is formed in a straight penetrating shape, and is composed of a straight constant diameter portion 19 whose diameter dimension is uniform in the vertical direction as a whole. A first rough surface portion 20 is formed on the entire surface of the constant diameter portion 19, and the first rough surface portion 20 forms the rough surface area 12 together with a second rough surface portion 21 formed on the upper surface 5 of the mask substrate 1. Since the other points are the same as those of the first embodiment, the same members are given the same reference numerals and their description is omitted. The same applies to the following third and subsequent embodiments.

[0029] In the alignment mark 8 of this embodiment, the rough surface area 12 (first rough surface area 20) is formed on the entire surface of the constant diameter portion 19 of the mark through-hole 15, and the circular ring-shaped rough surface area 12 (second rough surface area 21) is formed around the upper opening 16, so that it is possible to produce a circular ring-shaped annular pattern originating from the rough surface area 12. In addition, the inner pattern surrounded by the annular pattern is a circular pattern with the diameter dimension of the constant diameter portion 19.

[0030] The mark through-hole 15 constituting the alignment mark 8 of this embodiment is formed by irradiating a laser on the mask substrate 1 (FIG. 5(a)) created by an electroforming process. Specifically, as shown in FIG. 5(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 8 is to be formed, causing a part of the mask substrate 1 to disappear, thereby forming the mark through-hole 15 penetrating the mask substrate 1 in the vertical direction (opening formation process). The laser beam 33 at this time is set to a parallel beam whose beam diameter is the diameter dimension of the mark through-hole 15 and whose beam diameter does not change, and a straight through-hole whose diameter dimension is uniform in the vertical direction is formed in the mask substrate 1.

[0031] Next, as shown in FIG. 5(c), the mask substrate 1 is placed on a work table 34, a diffusion prism 35 is placed in the mark through hole 15, and the irradiation device 32, which has been reset to a larger beam diameter than before, is driven again to irradiate the laser light 33. By irradiating the laser light 33, the laser light 33 diffused by the diffusion prism 35 is irradiated onto the entire surface of the inner surface 10 of the mark through hole 15, and the surface of the constant diameter portion 19 disappears or melts and solidifies, forming a first rough surface portion 20 in the constant diameter portion 19. At the same time, in the mask substrate 1, a part of the upper surface 5 around the upper opening 16 disappears or melts and solidifies, forming a second rough surface portion 21 (roughening process). As a result, the rough surface area 12 is formed, and an alignment mark 8 having the mark through hole 15 and the rough surface area 12 can be formed.

[0032] (Third embodiment) FIGS. 6 and 7 show a third embodiment of the alignment mark according to the present invention. As shown in FIG. 6, the shape of the mark through hole 15 (opening 9) of the alignment mark 8 according to this embodiment is different from that of the first embodiment. In addition, the second rough surface portion 21 constituting the rough surface area 12 is eliminated. Specifically, as shown in FIG. 6, the mark through hole 15 (opening 9) constituting the alignment mark 8 according to this embodiment is formed to penetrate in an upwardly expanding shape, and is entirely composed of an upwardly expanding tapered expanding diameter portion 18 whose diameter dimension increases toward the upper opening 16. The first rough surface portion 20 is provided on the entire surface of the expanding diameter portion 18 of the mark through hole 15, and the rough surface area 12 is composed only of the first rough surface portion 20.

[0033] In the method of forming the alignment mark 8 according to this embodiment, first, an irradiation device 32 is disposed above the mask substrate 1, and a laser beam 33 is irradiated onto the mask substrate 1 at a position where the alignment mark 8 is to be formed, thereby eliminating a part of the mask substrate 1 and forming a mark through-hole 15 that penetrates the mask substrate 1 in the vertical direction (opening forming step). The laser beam 33 at this time is set to a convergent beam whose beam diameter gradually decreases, and a through-hole that widens upward and has a tapered shape is formed in the mask substrate 1.

[0034] 7, the mask substrate 1 is placed on a work table 34, a diffusion prism 35 is placed in the mark through-hole 15, and the irradiation device 32 is driven again with the beam diameter set smaller than before and re-set to a parallel beam with no change in beam diameter, to irradiate the laser light 33 toward the diffusion prism 35. By irradiating the laser light 33, the laser light 33 diffused by the diffusion prism 35 is irradiated to the entire surface of the inner surface 10 of the mark through-hole 15, and the surface of the enlarged diameter portion 18 disappears or melts and solidifies, forming the first rough surface portion 20 in the enlarged diameter portion 18 (roughening process). As a result, the rough surface region 12 is formed, and the alignment mark 8 having the mark through-hole 15 and the rough surface region 12 can be formed.

[0035] In the alignment mark 8 of this embodiment, the rough surface area 12 (first rough surface portion 20) is formed on the entire surface of the constant diameter portion 19 of the mark through-hole 15, so that it is possible to produce a circular ring-shaped annular pattern resulting from the rough surface area 12. In addition, the inner pattern surrounded by the annular pattern is a circular pattern with the diameter dimension of the lower end of the enlarged diameter portion 18.

[0036] (Fourth embodiment) FIG. 8 shows an alignment mark according to a fourth embodiment of the present invention. As shown in FIG. 8, the shape of the mark through-hole 15 (opening 9) of the alignment mark 8 according to this embodiment is different from that of the third embodiment. Specifically, the mark through-hole 15 is formed in a straight shape and is composed of a straight constant diameter portion 19 whose diameter dimension is uniform in the vertical direction. In the alignment mark 8 according to this embodiment, the rough surface area 12 (first rough surface portion 20) is formed on the entire surface of the constant diameter portion 19 of the mark through-hole 15, so that a circular ring-shaped annular pattern originating from the rough surface area 12 can be made to appear. In addition, the inner pattern surrounded by the annular pattern is a circular pattern with the diameter dimension of the constant diameter portion 19. The method of forming the alignment mark 8 according to this embodiment is the same as the opening formation step and the roughening treatment step of the third embodiment, but differs only in that the opening formation step is performed by setting the beam diameter to parallel light with no change.

[0037] (Fifth embodiment) Fig. 9 shows a fifth embodiment of the alignment mark according to the present invention. The mark through hole 15 (opening 9) constituting the alignment mark 8 according to this embodiment is different from the fourth embodiment in that a throttling wall 43 is formed in the middle in the vertical direction. Specifically, the mark through hole 15 has a throttling wall 43 protruding from the inner surface 10 toward the axis of the mark through hole 15 in a circumferential manner in the middle in the vertical direction, and the diameter of the throttling opening 44 formed at the protruding end of the throttling wall 43 is smaller than the diameter of the opening 17 serving as the upper opening 16. The inner surface 10 above the throttling wall 43 is formed as a straight hole whose diameter is uniform in the vertical direction, and the inner surface 10 below the throttling wall 43 is also formed as a straight hole whose diameter is uniform in the vertical direction. A first rough surface portion 20 is formed on the entire inner surface 10 of the mark hole 15, including the upper surface 43a and lower surface 43b of the aperture wall 43, and the first rough surface portion 20 formed on the upper surface 43a of the aperture wall 43, the inner surface 10 above the aperture wall 43, and the inner surface 10 of the protruding end portion of the aperture wall 43 constitute a rough surface region 12.

[0038] In the alignment mark 8 of this embodiment, the rough surface region 12 (first rough surface portion 20) is formed on the upper surface 43a of the aperture wall 43 of the mark through-hole 15, the inner surface 10 above the aperture wall 43, and the inner surface 10 of the protruding end portion of the aperture wall 43, so that it is possible to produce a circular ring-shaped annular pattern originating from the rough surface region 12. In addition, the inner pattern surrounded by the annular pattern is a circular pattern with the diameter dimension of the aperture opening 44.

[0039] In the alignment mark 8 of this embodiment, a diaphragm wall 43 is formed in the vertical midpoint of the mark through hole 15 (opening 9), protruding circumferentially from the inner surface 10 toward the axis of the mark through hole 15, so that in a plan view the inner surface 10 of the mark through hole 15 appears as a ring with a larger width dimension in the radial direction of the mark through hole 15. In addition, a rough surface region 12 is formed on the upper surface 43a of the diaphragm wall 43, so that the width dimension of the pattern in the radial direction of the mark through hole 15 can be made large, and the ring-shaped pattern created by the rough surface region 12 can make the inner shape surrounded by the pattern stand out more.

[0040] (Sixth embodiment) FIG. 10 shows an alignment mark according to a sixth embodiment of the present invention. The mark through hole 15 (opening 9) constituting the alignment mark 8 according to this embodiment differs from the fifth embodiment in the shape of the upper and lower inner surfaces 10 of the diaphragm wall 43. Specifically, the upper inner surface 10 of the diaphragm wall 43 is formed in an upwardly expanding bowl shape with a diameter dimension increasing toward the top, and the lower inner surface 10 of the diaphragm wall 43 is formed in a downwardly expanding bowl shape with a diameter dimension increasing toward the bottom. A first rough surface portion 20 is formed on the inner surface 10 including the upper and lower surfaces of the diaphragm wall 43, and the first rough surface portion 20 formed on the upper surface 43a of the diaphragm wall 43, the inner surface 10 above the diaphragm wall 43, and the inner surface 10 of the protruding end portion of the diaphragm wall 43 constitute the rough surface region 12. In the alignment mark 8 of this embodiment, the rough surface region 12 (first rough surface portion 20) is formed on the upper surface 43a of the aperture wall 43 of the mark through-hole 15, the inner surface 10 above the aperture wall 43, and the inner surface 10 of the protruding end portion of the aperture wall 43, so that it is possible to produce a circular ring-shaped annular pattern originating from the rough surface region 12. In addition, the inner pattern surrounded by the annular pattern is a circular pattern with the diameter dimension of the aperture opening 44.

[0041] (Seventh embodiment) FIG. 11 shows a seventh embodiment of the alignment mark according to the present invention. In the above first to sixth embodiments, the opening 9 is formed by the mark through hole 15 made of a through hole, but the opening 9 constituting the alignment mark 8 according to this embodiment is composed of a mark recess 45 formed by recessing into the upper surface 5 of the mask substrate 1. Specifically, the mark recess 45 (opening 9) has an upper opening 16 on the upper surface 5 of the mask substrate 1, and is composed of an equal diameter portion 19 formed in a straight shape with a uniform diameter dimension in the vertical direction, and a bottom portion 46 forming the bottom surface of the mark recess 45. A first rough surface portion 20 is formed on the entire surface of the equal diameter portion 19, and a third rough surface portion 47 made of a rough surface is formed on the entire surface of the bottom portion 46 of the mark recess 45. The first rough surface portion 20 formed in the equal diameter portion 19 constitutes the rough surface region 12, and is formed so that the surface roughness of the first rough surface portion 20 constituting the rough surface region 12 is different from the surface roughness of the third rough surface portion 47 at the bottom portion 46 of the mark recess 45. Furthermore, the surface roughness of the upper surface 5 of the mask substrate 1 is formed to be different from the surface roughness of the third rough surface portion 47 of the bottom 46 of the mark recess 45. The bottom 46 of the mark recess 45 may be formed with the third rough surface portion 47 or may be a mirror surface.

[0042] In this embodiment, the mark recess 45 (opening 9) consisting of a straight recess is formed in the vertical direction, which is the thickness direction of the mask substrate 1, so that an annular shape originating from the inner surface 10 of the mark recess 45 can be made to appear on the upper surface 5 of the mask substrate 1 in a plan view. In addition, the rough surface region 12 consisting of a rough surface having a surface roughness different from that of the mask substrate 1 is formed in a circular shape in the first rough surface portion 20, so that a contrast is generated between the rough surface region 12 and the upper surface 5 of the mask substrate 1 due to the difference in reflectance caused by the difference in surface roughness between the rough surface region 12 and the mask substrate 1, and a ring-shaped pattern can be made to appear clearly on the inner surface 10 of the mark through hole 15. Furthermore, an inner pattern (bottom 46 of the mark recess 45 inside the rough surface region 12) surrounded by the ring-shaped pattern originating from the rough surface region 12 can be made to appear clearly.

[0043] In this embodiment, since the rough surface area 12 (first rough surface portion 20) is formed on the entire surface of the inner surface 10 of the mark recess 45, a circular ring-shaped annular pattern resulting from the rough surface area 12 can be produced. In addition, the inner pattern surrounded by the annular pattern is a circular pattern with the diameter dimension of the bottom 46 of the mark recess 45. Therefore, according to this embodiment, by capturing the annular pattern resulting from the rough surface area 12 or the inner shape surrounded by this annular pattern with a CCD camera or the like, it is possible to detect the position and attitude of the mask substrate 1; in other words, it is possible to form an alignment mark 8 on the mask substrate 1.

[0044] (Eighth embodiment) FIG. 12 shows an eighth embodiment of the alignment mark according to the present invention. In the mark through-hole 15 (opening 9) of this embodiment, the upper and lower openings 16 and 17 in plan view are formed in irregular polygonal shapes with a large number of continuous irregularities, and are straight through-holes with uniform diameters in the vertical direction. A first rough surface portion 20 constituting the rough surface region 12 is formed on the entire surface of the inner surface 10. In this way, the planar shape of the mark through-hole 15 (the opening shape of the upper opening 16) may be a shape other than a circle, and may be, for example, an ellipse or a polygon (regular polygon). The same applies to the planar shape of the opening 9 consisting of the mark recess 45.

[0045] (Ninth embodiment) FIG. 13 shows a ninth embodiment of the alignment mark according to the present invention. In this embodiment, a heat shielding structure is formed around the alignment mark 8. The heat shielding structure is composed of a ring-shaped (annular) groove 51 recessed into the upper surface 5 of the mask substrate 1 so as to surround the alignment mark 8, and a flat surface 52 formed between the outer periphery of the alignment mark 8 (the outer periphery of the rough surface area 12) and the groove 51. In this way, when a heat shielding structure is provided around the alignment mark 8, it is possible to prevent the heat generated when forming the opening 9 (the mark through hole 15 or the mark recess 45) or the rough surface area 12 by irradiation with the laser light 33 from spreading around the mask substrate 1, and therefore it is possible to prevent the mask substrate 1 from being deformed when irradiated with the laser light 33. The shape of the groove 51 is not limited to annular, and may be a square (polygonal) frame shape.

[0046] In the above embodiment, the alignment marks 8 having the openings 9 with various different shapes are shown, but the shapes of the openings 9 are not limited to those shown in the above embodiment. Specifically, in the first embodiment, the expanded diameter portion 18 can be formed into an upwardly expanding bowl shape or an upwardly expanding tapered shape. In the second to fourth embodiments, the first rough surface portion 20 constituting the rough surface area 12 does not need to be provided on the entire surface of the inner surface 10 of the mark through hole 15, but may be provided in a circumferential shape on at least a part of the inner surface. In the seventh embodiment, the inner surface 10 of the mark recess 45 is formed into a straight shape, but the inner surface 10 may be formed into an upwardly expanding bell-mouth shape, an upwardly expanding bowl shape, or an upwardly expanding tapered shape. In the fifth embodiment, the upper surface 43a and the lower surface 43b of the diaphragm wall 43 may be inclined surfaces or curved surfaces. In the fifth and sixth embodiments, the rough surface area 12 (rough surface portion 20) may not be formed on the lower inner surface 10 and the inner surface of the diaphragm wall 43. Moreover, the aperture opening 44 is not limited to an opening consisting of a straight hole. In the seventh embodiment, the first rough surface portion 20 and the third rough surface portion 47 may be formed to have the same surface roughness. In this case, a circular pattern (annular pattern in the shape of a circular ring) originating from the rough surface region 12 can be made to appear.

[0047] The rough surface region 12 may be formed in a circumferential shape on a part of the inner surface 10 of the opening 9, and may not be formed on the entire inner surface 10 of the opening 9 as in the above-mentioned embodiments. The mask substrate 1 can be formed by etching or laser processing. The minute irregularities 20a and 21a of the rough surface portions 20 and 21 can be formed by chemical etching or mechanical blasting. The surface roughness can be varied within the rough surface region 12 to generate contrast in the rough surface region 12. The surface roughness can also be varied within each of the rough surface portions 20 and 21 to generate contrast in each of the rough surface portions 20 and 21. The contrast may be such that the shading is increased from the upper surface 5 of the mask substrate 1 toward the axis of the opening 9, or decreased toward the axis of the opening 9.

[0048] (Reference Example) In each of the above embodiments, the rough surface region 12 is formed in a continuous circumferential shape on the inner surface 10 of the opening 9, but the rough surface region 12 can be formed in an intermittent circumferential shape in the circumferential direction of the inner surface 10 of the opening 9. In this case, it is desirable to form the rough surface region 12 intermittently at two (plural) positions, one above the other, in different thickness directions, so that the phases are different from each other, and to configure so that a ring-shaped pattern originating from the rough surface region 12 appears on the inner surface 10 of the opening 9. The rough surface region 12 can also be formed intermittently in the circumferential direction of the opening 9 or in the planar direction of the mask substrate 1. Even with such a configuration, a contrast can be generated between the rough surface region 12 and the upper surface 5 of the mask substrate 1 due to the difference in reflectance caused by the difference in surface roughness between the rough surface region 12 and the mask substrate 1, and a pattern can be clearly appeared on the inner surface 10 of the opening 9.

[0049] As described above, in the present invention, the alignment mark 8 is constituted by the opening 9 made of an upwardly spreading or straight hole formed through the mask substrate 1 in the vertical direction, which is the thickness direction, and the rough surface area 12 made of a rough surface having a surface roughness different from the surface roughness of the upper surface 5 of the mask substrate 1 and formed in a circular shape on at least a part of the inner surface 10 of the opening 9. When the opening 9 made of an upwardly spreading or straight hole is formed through the mask substrate 1 in the vertical direction, which is the thickness direction, in this way, a circular or polygonal annular shape derived from the inner surface 10 of the opening 9 can be made to appear on the upper surface 5 of the mask substrate 1 in a plan view. In addition, as in the present invention, when the rough surface area 12 made of a rough surface having a surface roughness different from the surface roughness of the upper surface 5 of the mask substrate 1 is formed in a circular shape on at least a part of the inner surface of the opening 9, a contrast is generated between the rough surface area 12 and the upper surface 5 of the mask substrate 1 due to the difference in reflectance caused by the difference in surface roughness between the rough surface area 12 and the upper surface 5 of the mask substrate 1, and a ring pattern can be clearly made to appear on the inner surface 10 of the opening 9. Furthermore, the inner pattern surrounded by the annular pattern derived from the rough surface region 12 (the through region of the opening 9 inside the rough surface region 12) can be clearly made to appear. Therefore, according to the present invention, the position and posture of the mask substrate 1 can be detected by capturing the annular pattern derived from the rough surface region 12 or the inner shape surrounded by this annular pattern with a CCD camera or the like, in other words, the alignment mark 8 can be formed on the mask substrate 1. As described above, in the present invention, the alignment mark 8 is formed by the opening 9 made of a through hole and the rough surface region 12 formed in a circumferential shape on at least a part of the inner surface 10 of the opening 9, so that there is no risk of the mark disappearing due to the dropout of the dye as the filler, as in the conventional alignment mark in which the opening is filled with a dye, and therefore an alignment mark 8 that is less likely to disappear and has excellent reliability can be obtained.

[0050] In another aspect of the present invention, the alignment mark 8 is constituted by an opening 9 formed as an upwardly expanding or straight recess recessed into the upper surface 5 of the mask substrate 1, and a rough surface region 12 formed in a circular shape on at least a part of the inner surface 10 of the opening 9, the rough surface region 12 being made of a rough surface having a surface roughness different from that of the upper surface 5 of the mask substrate 1. In this way, when the opening 9 formed as an upwardly expanding or straight recess is formed penetrating the mask substrate 1 in the vertical direction, which is the thickness direction, an annular shape originating from the inner surface 10 of the opening 9 can be made to appear on the upper surface 5 of the mask substrate 1 in a plan view. In addition, as in another aspect of the present invention, when the rough surface region 12 made of a rough surface having a surface roughness different from that of the upper surface 5 of the mask substrate 1 is formed in a circular shape on at least a part of the inner surface 10 of the opening 9, a contrast is generated between the rough surface region 12 and the upper surface 5 of the mask substrate 1 due to the difference in reflectance caused by the difference in surface roughness between the rough surface region 12 and the upper surface 5 of the mask substrate 1, and a circular pattern can be clearly made to appear on the inner surface 10 of the opening 9. Furthermore, the inner pattern surrounded by the annular pattern derived from the rough surface region 12 (the bottom 46 region of the opening 9 inside the rough surface region 12) can be clearly made to appear. Therefore, according to the present invention, the position and posture of the mask substrate 1 can be detected by capturing the annular pattern derived from the rough surface region 12 or the inner shape surrounded by this annular pattern with a CCD camera or the like, and in other words, the alignment mark 8 can be formed on the mask substrate 1. As described above, in another aspect of the present invention, the alignment mark 8 is formed by the opening 9 made of a recess and the rough surface region 12 formed in a circumferential shape on at least a part of the inner surface 10 of the opening 9, so that there is no risk of the mark disappearing due to the dropout of the dye as the filler, as in the conventional alignment mark in which the opening is filled with a dye or the like, and an alignment mark 8 that is less likely to disappear and has excellent reliability can be obtained.

[0051] When the rough surface area 12 is composed of a first rough surface portion 20 formed in a circumferential shape on the inner surface 10 of the opening 9 and a second rough surface portion 21 formed in a circumferential shape so as to surround the upper opening 16 of the opening 9, the width dimension of the rough surface area 12 in the radial direction of the opening 9 can be increased, and the width dimension of the annular pattern derived from the rough surface area 12 can be increased, compared to a form in which the rough surface area 12 is formed only on the inner surface 10 of the opening 9. This increases the contrast between the rough surface area 12 and the upper surface 5 of the mask substrate 1, making the annular pattern appear more clearly inside and outside the opening 9, and therefore makes the annular pattern and the inner shape surrounded by the annular pattern more prominent. Therefore, an alignment mark 8 with better discrimination can be obtained.

[0052] If the first rough surface portion 20 and the second rough surface portion 21 are formed continuously across the upper opening 16 of the opening 9, the two rough surface portions 20 and 21 can be integrated together, making the annular pattern appear more clearly inside and outside the opening 9. This makes it possible to make the annular pattern originating from the rough surface region 12 and the inner shape surrounded by this annular pattern more prominent, resulting in an alignment mark 8 with better discrimination.

[0053] When the throttling wall 43 is formed in the middle of the opening 9 in the up-down direction, protruding circumferentially from the inner surface 10 toward the axis of the opening 9, the inner surface 10 of the opening 9 appears in a plan view as a ring with a larger width dimension in the radial direction of the opening 9. In addition, when the rough surface region 12 is formed on the upper surface 43a of the throttling wall 43, the width dimension of the pattern in the radial direction of the opening 9 can be made large, so that the ring-shaped pattern created by the rough surface region 12 can make the inner shape surrounded by the pattern stand out more.

[0054] In the method of forming an alignment mark of the present invention, since the rough surface region 12 is formed by irradiation with laser light 33, it is possible to form the rough surface region 12 more easily than in a method of forming the rough surface region 12 by cutting or the like. In addition, the unevenness of the rough surface region 12 can be adjusted simply by controlling the output of the laser light, and this method is also excellent in that the surface roughness of the rough surface region 12 can be easily controlled.

[0055] The present invention can provide a metal mask having the above-mentioned alignment marks 8 formed on a mask substrate 1 made of a thin metal plate. This eliminates the risk of the mark disappearing due to the fall-off of the dye filler, as occurs with conventional alignment marks formed by filling openings with dye, and makes it possible to obtain a metal mask having alignment marks 8 that are less likely to disappear and have excellent reliability.

[0056] The alignment mark 8 according to the present invention is not limited to metal masks for screen printing, but can also be applied to metal masks for vapor deposition, solder ball arrangement, solder ball adsorption, etc. When applying the alignment mark 8 in which the opening 9 is made of the mark through-hole 15 as the alignment mark for such various metal masks, it is preferable to form the opening diameter of the opening 9 to be approximately the same as or smaller than the mask opening 2 in order to prevent an object (printed matter, ball, organic matter, etc.) from being inadvertently formed on the work through the opening 9. Furthermore, when applying alignment marks 8 in which openings 9 are formed of mark recesses 45 as alignment marks for various metal masks, it is preferable to form the opening diameter of openings 9 to be approximately the same as or smaller than mask openings 2 in order to prevent objects (printed matter, balls, organic matter, etc.) from entering openings 9 and causing the alignment mark 8 to disappear. For example, in metal masks for arranging solder balls or for adsorbing solder balls, it is preferable to form the opening diameter of openings 9 to be smaller than the diameter of the solder balls to be handled.

[0057] In the above-mentioned various metal masks, resin can be filled into the opening 9 (mark through hole 15, mark recess 45) of the alignment mark 8. By using a transparent material for the resin to be filled, through which the inner surface 10 of the opening 9 can be seen, the annular pattern or the like that appears on the inner surface 10 of the opening 9 can be captured by a CCD camera or the like, and the position and posture of the mask substrate 1 can be detected. In this way, filling the mark through hole 15 (opening 9) with resin can prevent an object from being inadvertently formed on the work through the mark through hole 15, and filling the mark recess 45 (opening 9) with resin can prevent an object from entering the mark recess 45 and causing the alignment mark 8 to disappear. In addition, by preventing these problems, the degree of freedom of the opening diameter of the opening 9 (mark through hole 15, mark recess 45) can be improved.

[0058] A metal mask equipped with an alignment mark according to the present invention 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. [Explanation of symbols]

[0059] 1 Mask substrate 2 Mask opening 5 Top surface 8 Alignment Marks 9 Openings 10. Inside 12 Rough surface area 15 Mark hole 16 Top opening 18 Expanded diameter part 20 1st rough surface part 21 2nd rough surface part 43 Squeezing Wall 43a Upper surface of aperture wall 45 Mark recess

Claims

1. An alignment mark formed on a mask substrate (1) having a mask opening (2), An opening (9) formed as an upwardly expanding or straight hole penetrating the mask substrate (1) in the vertical direction, which is the thickness direction of the mask substrate (1); The alignment mark is characterized in that it is made of a rough surface having a surface roughness different from the surface roughness of the upper surface (5) of the mask substrate (1) and is composed of a rough surface area (12) formed in a circular shape on at least a portion of the inner surface (10) of the opening (9).

2. An alignment mark formed on a mask substrate (1) having a mask opening (2), An opening (9) formed as an upwardly expanding or straight recess formed on the upper surface (5) of the mask substrate (1); The alignment mark is characterized in that it is made of a rough surface having a surface roughness different from the surface roughness of the upper surface (5) of the mask substrate (1) and is composed of a rough surface area (12) formed in a circular shape on at least a portion of the inner surface (10) of the opening (9).

3. 3. An alignment mark as described in claim 1 or 2, wherein the rough surface area (12) is composed of a first rough surface portion (20) formed in a circumferential shape on the inner surface (10) of the opening (9) and a second rough surface portion (21) formed in a circumferential shape so as to surround the upper opening (16) of the opening (9).

4. 4. The alignment mark according to claim 3, wherein the first rough surface portion (20) and the second rough surface portion (21) are formed continuously across an upper opening (16) of the opening portion (9).

5. A throttle wall (43) is formed in a vertical midway portion of the opening (9) so as to protrude circumferentially from the inner surface (10) toward the axis of the opening (9), 2. The alignment mark according to claim 1, wherein a roughened area (12) is formed on an upper surface (43a) of the aperture wall (43).

6. A method for forming alignment marks in a mask substrate (1) comprising a mask opening (2), comprising the steps of: an opening forming step of penetrating the mask substrate (1) in the thickness direction, i.e., in the vertical direction, an opening (9) consisting of an upwardly expanding or straight hole, or depression-forming the upper surface (5) of the mask substrate (1) in the thickness direction, i.e., in the vertical direction, an opening (9) consisting of an upwardly expanding or straight recess; a roughening process for irradiating at least a part of the inner surface (10) of the opening (9) with laser light to form a circular roughened area (12) having a surface roughness different from the surface roughness of the upper surface (5) of the mask substrate (1); 13. A method for forming an alignment mark, comprising:

7. 3. A metal mask comprising an alignment mark (8) according to claim 1 or 2 formed on a mask substrate (1) made of a thin metal plate.

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