Deposition mask and method for producing deposition mask

A deposition mask is provided. The deposition mask including: a resin film 1 in which penetrating opening patterns 4 are formed and a frame-shaped metal thin film 5 having an opening is provided on one face 1a of the film 1; a metal mask 2 provided at a position corresponding to the opening of the metal thin film 5 on one face 1a side of the film 1, the metal mask 2 being separated from and independent of the film 1, the metal mask 2 being provided with through holes 6; and a metal frame 3 positioned on one face 1a side of the film 1, the metal frame 3 supporting the film 1 and the metal mask 2 by spot-welding a portion of the metal thin film 5 and an edge region of the metal mask 2 to one end face 3a.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a deposition mask provided with a plurality of opening patterns corresponding to a plurality of thin film patterns to be deposited on a substrate, and more particularly, relates to a deposition mask capable of forming high definition thin film patterns with high positional accuracy, and a method of manufacturing the deposition mask.

2. Description of Related Art

A conventional deposition mask is a metal mask provided with a plurality of penetrating opening patterns corresponding to a plurality of thin film patterns to be deposited on a substrate. The mask is manufactured as follows: a first resist pattern having a plurality of through openings is formed on a metal plate, an etching process is performed through the through openings of the first resist pattern to thereby form a plurality of through holes penetrating through the metal plate, the first resist pattern is removed, a second resist pattern having a plurality of second through openings, each exposing a metal edge portion with a predetermined width around each of the plurality of opening patterns on the metal plate, is formed, an etching process is performed through the second through openings of the second resist pattern, to thereby form: a mask body portion around each of the plurality of through openings; and a peripheral portion, having a thickness greater than that of the mask body portion and positioned around the mask body portion, and then, the second resist pattern is removed (for example, see Japanese Patent Application Laid-open Publication No. 2001-237072).

However, in such a conventional deposition mask, the etching process is performed on the metal plate to form the plurality of penetrating opening patterns in the metal plate, and thus, it is not possible to form a high definition opening pattern with a high level of accuracy. In particular, for example, in a case of a large area deposition mask for an organic EL display panel having a large area in which a length of one side of equal to or greater than several tens of cm, it is not possible to uniformly form a high definition opening pattern over the entire surface of the mask, due to the occurrence of etching unevenness, an increase in an opening area caused by isotropic etching, and the like.

SUMMARY OF THE INVENTION

Thus, the applicant has proposed a composite mask having a structure in which a resin film and a magnetic metal member having a thin plate shape are brought into tight contact with each other. In the resin film, corresponding to the thin film patterns, a plurality of opening patterns each having the same shape and dimensions as those of each of a plurality of thin film patterns to be deposited on a substrate are formed. In the magnetic metal member, through holes, each having a size capable of arranging therein at least one of the plurality of opening patterns, are formed.

The composite mask is obtained by forming opening patterns on a thin resin film having a thickness of approximately 10 μm to 30 μm by laser beam machining, and has advantages that it is possible to form high definition opening patterns with a high level of accuracy and to uniformly form opening patterns over the entire surface of the above-mentioned large area deposition mask.

However, in the composite mask, a magnetic metal member such as Invar or an Invar alloy, which has a smaller thermal expansion coefficient, and a member such as a resin film, which has a relatively large thermal expansion coefficient, are brought into tight contact with each other at room temperature or higher, and thus internal stress is generated in the resin film due to a difference in thermal expansion between both the members. Accordingly, when a plurality of opening patterns are sequentially formed in the resin film by laser beam machining, the internal stress is partially released. As a result, it can be understood that the positions of the opening patterns cumulatively deviate. Therefore, there is a concern that high definition thin film patterns cannot be formed with high positional accuracy.

Therefore, the present invention is contrived in view of such problems, and an object thereof is to provide a deposition mask capable of forming high definition thin film patterns with high positional accuracy, and a method of manufacturing the deposition mask.

In order to accomplish the object, a deposition mask according to a first aspect of the invention is a deposition mask provided with a plurality of opening patterns corresponding to a plurality of thin film patterns to be deposited on a substrate. The deposition mask includes: a resin film in which the plurality of penetrating opening patterns are formed and a frame-shaped metal thin film having an opening having a size capable of arranging therein the plurality of opening patterns is provided on one face of the resin film; a metal mask provided at a position corresponding to the opening of the metal thin film on one face side of the resin film, the metal mask being separated from and independent of the resin film, the metal mask being provided with a plurality of through holes, each having a size capable of arranging therein at least one of the plurality of opening patterns; and a metal frame positioned on the one face side of the resin film, the metal frame being formed to have a frame shape provided with an opening portion having a size capable of arranging therein the plurality of through holes of the metal mask, the metal frame being configured to support the resin film and the metal mask by spot-welding a portion of the metal thin film and an edge region of the metal mask to one end face in a state in which the resin film and the metal mask are provided under tension on the metal frame.

In addition, a method of manufacturing a deposition mask according to a second aspect of the invention is a method of manufacturing a deposition mask provided with a plurality of opening patterns corresponding to a plurality of thin film patterns to be deposited on a substrate. The method includes: a first step of depositing a frame-shaped metal thin film having an opening having a size capable of arranging therein the plurality of opening patterns, on one face of a resin film; a second step of forming a metal mask by providing a plurality of through holes, each having a size capable of arranging therein at least one of the plurality of opening patterns, in a metal sheet having an external dimension having a size capable of being placed within the opening of the metal thin film; a third step of spot-welding a peripheral region of the metal mask to one end face of the metal frame in a state in which the metal mask is provided under tension across a frame-shaped metal frame having an opening portion having a size capable of arranging therein the plurality of through holes; a fourth step of spot-welding a portion of the metal thin film of the resin film to one end face of the metal frame in a state in which the resin film covers the metal mask with a metal thin film side of the resin film facing the metal mask and the resin film is provided under tension across the metal frame; and a fifth step of irradiating a portion of the resin film through the through hole of the metal mask with a laser beam, to thereby form the opening pattern.

According to the present invention, the resin film and the metal mask are separated from and independent of each other rather than being brought into tight contact with and fixed to each other unlike the above-mentioned composite mask, and thus the resin film does not have internal stress based on a difference in thermal expansion between the resin film and the metal mask. Accordingly, even when a plurality of opening patterns is formed by laser beam machining, positional deviation of the opening patterns can be reduced, and thus, the opening patterns can be formed with high positional accuracy. Therefore, it is possible to form high definition thin film patterns with high positional accuracy.

DESCRIPTION OF PREFERRED EMBODIMENTS

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.FIGS. 1A and 1Bare diagrams illustrating a deposition mask according to a first embodiment of the present invention.FIG. 1Ais a plan view, andFIG. 1Bis a diagram taken along with a line S-S ofFIG. 1Awhen seen from an arrow. The deposition mask is provided with a plurality of opening patterns corresponding to a plurality of thin film patterns to be deposited on a substrate, and is configured to include a resin film1, a metal mask2, and a metal frame3.

The film1is a resin film provided with a plurality of penetrating opening patterns4formed therein so as to correspond to the plurality of thin film patterns to be deposited on the substrate, each opening pattern4having the same shape and dimensions as those of the corresponding thin film pattern, and the film1is, for example, a resin film made of a resin that transmits visible light, such as polyimide or polyethylene-terephthalate (PET), and having a thickness of approximately 10 μm to 30 μm.

Furthermore, a metal thin film (hereinafter, referred to as a “frame-shaped metal thin film”)5is deposited on one face1aof the film1by plating or the like with a thickness of approximately 30 μm to 50 μm. The frame-shaped metal thin film5has an opening having a size capable of arranging therein the plurality of opening patterns4, and thus, has a frame shape with an appropriate width, and the frame-shaped metal thin film5is made of, for example, Invar or an Invar alloy.

The metal mask2is provided at a position corresponding to the inside of the frame (inside of the opening) of the frame-shaped metal thin film5on one face1aside of the film1, in a manner such that the metal mask2is separated from and independent of the film1. The metal mask2supports the film1at the time of forming the plurality of opening patterns4by laser beam machining, and is attracted by a magnet provided on a back face of the substrate during deposition to bring the film1into tight contact with a face of the substrate. The metal mask2is constituted by a metal sheet, which has an external dimension of a size capable of being placed within the frame of the frame-shaped metal thin film5, the metal sheet being formed of a magnetic metal material such as Invar or an Invar alloy, the metal sheet having a thickness of approximately 30 μm to 50 μm, which is substantially the same as that of the frame-shaped metal thin film5. In addition, the metal mask2is provided with a plurality of through holes6having a size capable of arranging therein at least one of the plurality of opening patterns4.

The metal mask2may be provided with a plurality of through holes having an elongated slit shape and arranged in parallel, or, for example, as illustrated inFIG. 1A, the metal mask2may be provided with rows of a plurality of through holes, arranged in parallel at a predetermined constant arrangement pitch P, each row having a plurality of through holes6, each having a size capable of arranging therein one opening pattern4.

The frame-shaped metal frame3is positioned on one face1aside of the film1, and the metal frame3has an opening portion7having a size capable of arranging therein the plurality of through holes6of the metal mask2, and has an external shape having a size that is substantially the same as that of the external shape of the frame-shaped metal thin film5of the film1. The metal frame3is configured to support the film1and the metal mask2by spot-welding a portion of the frame-shaped metal thin film5of the film1and an edge region of the metal mask2to one end face3a(seeFIGS. 2A to 2C and 3A to 3d) in a state in which the film1and the metal mask2are provided under tension on the metal frame3, and the metal frame3is formed of a magnetic metal material such as Invar or an Invar alloy, having a thickness of approximately 30 mm to 50 mm.

Next, a method of manufacturing the deposition mask configured in this manner will be described.

First, the film1in which the frame-shaped metal thin film5having an opening having a size capable of arranging therein the plurality of opening patterns4is formed on one face1athereof, is prepared. In more detail, the film1is a resin film made of a resin that transmits visible light, such as polyimide, having a thickness of 10 μm to 30 μm, cut out into a square shape, and the film1is provided with the frame-shaped metal thin film5having an appropriate width formed on one face1aalong the peripheral portion thereof. At this time, the size of the opening of the frame-shaped metal thin film5is set to be capable of arranging therein the plurality of opening patterns4to be formed in the film1later and capable of accommodating the metal mask2in the opening.

Here, the formation of the frame-shaped metal thin film5will be described in detail.

First, a seed layer constituted by a metal film having good conductivity is formed on one face1aof the resin film1, so as to have a thickness of approximately 50 nm by a known deposition technique such as vapor deposition, sputtering, or electroless plating. In this case, when the film1is polyimide, it is preferable to use nickel or the like as the seed layer. Since copper diffuses into polyimide, copper is not preferable as a seed layer for polyimide. On the other hand, when the film1is PET, it is preferable to use copper or the like as a seed layer in terms of adhesiveness.

Subsequently, a photoresist is applied onto the seed layer, so as to have a thickness of, for example, 30 μm, and is exposed and developed using a photomask, thereby forming an island pattern in a portion corresponding to the inside of the frame (inside of the opening) of the frame-shaped metal thin film5and a portion corresponding to the outside of the frame.

Then, a metal thin film formed of a magnetic metal material such as Invar or an Invar alloy is deposited on the seed layer at a portion not covered by the island pattern by a known plating technique, so as to have a thickness of, for example, 30 μm. Thereafter, the island pattern is removed, and the seed layer positioned below the island pattern is removed by etching. Thereby, the frame-shaped metal thin film5is formed on one face1aof the film1.

In addition, the metal mask2provided with the plurality of through holes6is prepared. The metal mask2is obtained by forming, in a metal sheet, the plurality of through holes6, each having a size capable of arranging therein at least one of the plurality of opening patterns4to be formed in the film1. The metal sheet has an external dimension having a size capable of being placed within the frame of the frame-shaped metal thin film5, and is formed of a magnetic metal material such as Invar or an Invar alloy, and has a thickness of, for example, approximately 30 μm.

The plurality of through holes6is formed in the following manner. That is, a photoresist is applied onto one face of the metal sheet so as to have an appropriate thickness and is exposed and developed using a photomask, thereby forming a resist mask having openings at positions corresponding to the plurality of through holes6. Subsequently, the metal sheet is etched using the resist mask, and the through holes6are formed in the portions of the metal sheet which correspond to the openings. Thereby, the metal mask2is formed.

Furthermore, the metal frame3having a frame shape is prepared. The metal frame3is configured to have the external dimension thereof substantially coinciding with the external dimension of the frame-shaped metal thin film5of the film1, and to have the opening portion7within the frame set to have a size capable of arranging therein the plurality of through holes6. The opening portion7is formed by, for example, cutting a magnetic metal plate such as Invar or an Invar alloy, having a thickness of 30 mm to 50 mm.

Hereinafter, a method of manufacturing the deposition mask according to the first embodiment of the present invention will be described with reference toFIGS. 2A to 2C, 3A to 3D, and 4.

First, as illustrated inFIG. 2A, the metal mask2is provided under tension across one end face3aof the metal frame3in a state in which a peripheral portion of the metal mask2is held by tension grips8and is laterally pulled in a direction parallel to the face of the metal mask2to have an appropriate tension applied thereto. In this state, as illustrated inFIG. 2B, a peripheral region of the metal mask2is irradiated with a laser beam L using, for example, a YAG laser, and the metal mask2is spot-welded onto one end face3aof the metal frame3. The spot welding may be performed at a plurality of locations. Thereafter, as illustrated inFIG. 2C, the peripheral portion of the metal mask2is cut off by a cutter so that the metal mask2can be placed within the inside of the frame of the frame-shaped metal thin film5formed on the film1.

Next, as illustrated inFIG. 3A, the peripheral portion is held by the plurality of tension grips8and is laterally pulled in a direction parallel to the face of the film1in a state in which one face1aof the film1having the frame-shaped metal thin film5provided thereon faces the metal mask2, and an appropriate tension is applied to the film1to such an extent that the film1is not stretched. In this state, the film1is positioned above the metal frame3so as to cover the metal mask2. Next, as illustrated inFIG. 3B, after the metal mask2supported by the metal frame3is adjusted to be positioned within the frame of the frame-shaped metal thin film5of the film1, the frame-shaped metal thin film5of the film1is brought into tight contact with one end face3aof the metal frame3. Subsequently, as illustrated inFIG. 3C, the portion of the frame-shaped metal thin film5is irradiated with a laser beam, and thus the frame-shaped metal thin film5is spot-welded to one end face3aof the metal frame3. The spot welding may be performed at a plurality of locations similar to the spot welding of the metal mask2. Meanwhile, the film1remains having the appropriate tension applied thereto until the spot welding is terminated. Thereafter, as illustrated inFIG. 3D, the film1is cut along the outer peripheral of the metal frame3. Thereby, the film1is fixed to the metal frame3and thus supported thereby. In this case, the film1and the metal mask2are separated from and independent of each other.

Subsequently, the metal frame3is mounted on an X-Y stage of a laser beam machining device with the film1located above the metal frame3. Then, as illustrated inFIG. 4, the portions of the film1corresponding to the through holes6of the metal mask2are irradiated with a laser beam L having a wavelength of equal to or less than 400 nm, for example, so that an irradiation area is shaped to be equal to the area of the opening pattern4, and the film1is ablated to be removed. Thereby, for example, one opening pattern4penetrating the film1is formed, corresponding to one through hole6. Thereafter, the portions of the film1corresponding to the through holes6of the metal mask2are irradiated with a laser beam L while moving the X-Y stage stepwise in the X and Y directions at a predetermined pitch which is determined in advance, thereby forming the opening patterns4. Therefore, the deposition mask illustrated inFIG. 1is completed.

According to the deposition mask of the present invention, the film1and the metal mask2are separated from and independent of each other rather than being brought into tight contact with and fixed to each other unlike the above-mentioned composite mask, and thus the film1does not have internal stress based on a difference in thermal expansion between the film1and the metal mask2. Accordingly, even when the plurality of opening patterns4is formed by laser beam machining, positional deviation of the opening patterns4can be reduced, and thus, it is possible to form the opening patterns4with high positional accuracy.

In addition, when the opening patterns4are formed in the film1, the film1is not bent, since the film1is supported by the metal mask2. Accordingly, it is possible to form the opening patterns4with high positional accuracy by the effect of supporting achieved by the metal mask2.

However, since the film1has an appropriate tension applied thereto to such an extent that the film1is not stretched, the film1may have slight internal stress caused by the tension. Accordingly, there is a concern that slight positional deviation of the opening patterns4may occur when forming the opening patterns4. However, since the tension is equally, laterally applied parallel to the face of the film1, the internal stress of the film1is uniformly distributed into the face of the film1, and thus the direction and amount of positional deviation of the opening pattern4can be easily predicted by being confirmed in advance by an experiment or the like. Accordingly, when the opening patterns4are formed by laser beam machining while adjusting the position of irradiation with a laser beam L by estimating the positional deviation, all of the opening patterns4finally formed can be positioned at correct positions.

FIG. 5is a diagram illustrating a deposition mask according to a second embodiment of the present invention.FIG. 5Ais a plan view, andFIG. 5Bis a diagram taken along with a line T-T ofFIG. 5Awhen seen from an arrow. Here, only parts different from those in the first embodiment will be described.

The second embodiment can apply to a large area substrate having a length of one side of equal to or greater than 1 m, and In the second embodiment, there are provided a film1with a frame-shaped metal thin film and which has the length of one side of equal to or greater than 1 m, and a metal frame3similarly having an external dimension having a length of one side of equal to or greater than 1 m. On the other hand, in the metal mask2, the width of a metal sheet serving as a substrate is restricted from a problem of manufacturing equipment (in the present situation, a maximum of approximately 500 mm), and the degree of freedom in selecting a width is lower than that of the film1or the metal frame3. Accordingly, in the second embodiment, the metal mask2is configured such that a plurality of strip-like unit masks9having a width of a maximum of approximately 500 mm are arranged so that the longitudinal axes of the unit masks are arranged in parallel.

In more detail, in the unit mask9, rows of a plurality of through holes, each row having a plurality of through holes arranged in a line along the longitudinal axis thereof, or a plurality of slit-shaped through holes extending along the longitudinal axis thereof are formed at a constant arrangement pitch P in a direction perpendicular to the longitudinal axis as illustrated inFIG. 5B. In addition, the plurality of unit masks9are arranged parallel to each other with a gap10provided between the adjacent unit masks9, so that at least one row of through holes or at least one slit-shaped through hole can be present in the gap10while maintaining the arrangement pitch. The unit masks9are spot-welded to one end face3aof the metal frame3. Meanwhile,FIG. 5illustrates the plurality of through holes6arranged in a row, and illustrates a case in which one row of through holes6can be present in the gap10.

Such a deposition mask is manufactured in the following manner.

First, the film1is cut out from a film sheet having a width of equal to or greater than 1 m and a thickness of 10 μm to 30 μm which is wound up in the form of a roll, and is formed to have a square shape having a length of one side of equal to or greater than 1 m. Thereafter, similarly to the first embodiment, a frame-shaped metal thin film5is formed on one face1aof the film1.

On the other hand, the unit mask9is cut out from a band-like metal sheet having, for example, a width of equal to or less than 500 mm and a thickness of 30 μm to 50 μm, which is wound up in the form of a roll, to obtain a metal sheet having a strip shape having a predetermined length determined in advance, and the unit mask9is formed by providing the plurality of through holes6in the metal sheet in the same manner as in the first embodiment.

Next, a process of mounting the unit masks9on the metal frame3will be performed.

First, as illustrated inFIG. 6A, the metal frame3is placed on an X-Y stage at a predetermined position which is determined in advance. For example, the positions of at least two sides of the metal frame3, which are perpendicular to each other, are regulated by positioning pins provided on the X-Y stage, and thus the metal frame is positioned.

Subsequently, as illustrated inFIG. 6B, a unit mask9A is provided under tension across one end face3aof the metal frame3in a state in which edge portions thereof in the longitudinal axis direction are held by tension grips8and are pulled in opposite directions along the longitudinal axis to have a fixed tension applied thereto. Furthermore, in this state, an alignment mark, not shown in the drawing, which is formed in the metal frame3in advance and an alignment mark, not shown in the drawing, which is formed in the unit mask9A in advance are photographed by an alignment camera. For example, the position of the unit mask9A is adjusted so that both the marks have an appropriate positional relationship, and the unit mask9A is aligned with respect to the metal frame3. Thereafter, an edge region of the unit mask9A in the longitudinal axis direction (Y direction) is irradiated with a laser beam L, and thus the unit mask9A is spot-welded to one end face3aof the metal frame3and is fixed.

Subsequently, as illustrated inFIG. 7A, a second unit mask9B is positioned on one end face3aof the metal frame3and is mounted in the same manner as the first unit mask9A. In this case, as illustrated inFIG. 7A, the second unit mask9B is attached so that a space between the first unit mask9A and the second unit mask9B serves as a gap10in which at least one row of through holes6can be present while maintaining the arrangement pitch P with respect to the adjacent row of through holes6. Meanwhile,FIG. 7Aillustrates a case in which a gap10in which one row of through holes (virtual through holes6′) can be present is provided.

In this manner, when the plurality of unit masks9A and9B are spot-welded to one end face3aof the metal frame3and are fixed, both ends of the unit masks9A and9B in the longitudinal axis direction (Y direction) are cut off by a cutter so that the lengths of the unit masks in the longitudinal axis direction have a size capable of being placed within the frame of the frame-shaped metal thin film5provided on the film1, as illustrated inFIG. 7B.

Next, a process of mounting the film1on the metal frame3will be performed.

First, as illustrated inFIG. 8A, the film1is mounted on the metal frame3, which has been positioned on the X-Y stage and fixed, so as to cover the metal mask2. Furthermore, as illustrated inFIG. 8B, a peripheral portion of the film1is held by the tension grips8and is laterally pulled in a direction parallel to the face of the film1, and the film1has an appropriate tension applied thereto. In this state, for example, the position of the film1is adjusted so that the metal mask2can be placed within the frame of the frame-shaped metal thin film5of the film1, while observing the metal mask2through the film1from above, for example. Thereafter, the portion of the frame-shaped metal thin film5is irradiated with a laser beam, and thus the frame-shaped metal thin film5is spot-welded to one end face3aof the metal frame3. Thereby, the film1is fixed to the metal frame3.

Subsequently, as illustrated inFIG. 9, the film1is cut off along the outer periphery of the metal frame3, and thus the external shape of the deposition mask is trimmed.

Thereafter, similarly to the first embodiment, the portions of the film1which correspond to the plurality of through holes6of the metal mask2are irradiated with a laser beam L while moving the X-Y stage stepwise in the X and Y directions, thereby forming the plurality of opening patterns4. In this case, as illustrated in an enlarged manner inFIG. 10, correspond to the virtual through holes6′, the opening patterns4are also formed in the portion of the gap10between the unit masks9A and9B adjacent to each other, and thus, for example, rows, each including the opening patterns4arranged in a line in the Y direction, are formed in the film1so as to be lined up at an arrangement pitch P in the X direction.

In this manner, according to the deposition mask of the second embodiment of the present invention, it is possible to obtain the same effects as those in the first embodiment and to easily manufacture a large area deposition mask having a length of one side of equal to or greater than 1 m.

The deposition mask according to the present invention is not limited to a mask for vapor deposition, for example, for an organic EL layer of an organic EL display panel, and can be applied as a mask for sputtering film formation, for example, for a transparent electrode of an electrostatic capacitive touch panel.

It should be noted that the entire contents of Japanese Patent Application No. 2013-138814, filed on Jul. 2, 2013, on which convention priority is claimed, is incorporated herein by reference.

It should also be understood that many modifications and variations of the described embodiments of the invention will be apparent to one skilled in the art without departing from the spirit and scope of the present invention as claimed in the appended claims.