JP7737871B2 - Method for manufacturing a deposition mask - Google Patents

Description

The present invention relates to a method for manufacturing a deposition mask. In particular, the present invention relates to a method for manufacturing a deposition mask having a thin-film mask body attached to a mask frame.

Examples of flat panel display devices include liquid crystal display devices and organic EL display devices. These display devices are structures in which thin films made of various materials, such as insulators, semiconductors, and conductors, are stacked on a substrate. These thin films are appropriately patterned and connected to achieve the display device's functionality.

Methods for forming thin films can be broadly classified into gas-phase methods, liquid-phase methods, and solid-phase methods. Gas-phase methods are further divided into physical vapor methods and chemical vapor methods. Vapor deposition is a well-known example of a physical vapor method. The simplest vapor deposition method is vacuum deposition. In vacuum deposition, a material is heated under a high vacuum to sublimate or evaporate the material, producing vapor (hereinafter, these methods are collectively referred to as vaporization). In the area where this material is to be deposited (hereinafter, the deposition area), the vaporized material solidifies and is deposited, resulting in a thin film of the material. Vacuum deposition is performed using a mask (deposition mask) to selectively form a thin film in the deposition area and prevent material from depositing in other areas (hereinafter, the non-deposition area) (see Patent Documents 1 and 2).

A deposition mask has a mask body on which a deposition pattern is formed, and a mask frame for fixing the mask body joined to it. The mask body is formed by forming a plating film using a photoresist layer with a predetermined pattern formed on a support substrate via a metal layer as a mask, joining the frame, and then separating the mask body from the support substrate and underlying metal layer.

JP 2009-87840 A JP 2013-209710 A

During the mask body manufacturing process, when the plating layer, which consists of a fine pattern formed on a support substrate by electroplating, is separated from the support substrate, stress in the plating layer causes the plating layer to shrink. This causes the opening area to shift from the desired position, making it important to manage the plating layer's shrinkage rate. However, because the plating layer's shrinkage rate cannot be measured unless the plating layer is separated from the support substrate, it takes several days to feed back the measured plating layer shrinkage rate results to the fine pattern formation process and the plating layer formation process.

On the other hand, one method for measuring the shrinkage rate of a plating layer is to form a plating layer on a dummy support substrate, then immediately peel it off and measure the shrinkage rate of the plating layer. In this case, the plating layer needs to be formed thick enough so that it will not be damaged or deformed even if it is peeled off alone. However, because the plating layer peeled off from the dummy support substrate is in a different state from the plating layer that makes up the actual mask body, it was not possible to accurately evaluate the shrinkage rate.

In view of the above problems, one object of one embodiment of the present invention is to provide a method for manufacturing a deposition mask with improved positional accuracy of the opening area.

A method for manufacturing a vapor deposition mask according to one embodiment of the present invention includes forming a photoresist layer on a support substrate via a metal base layer, positioning the support substrate so that a first surface of the support substrate is perpendicular to the horizontal plane, measuring a first amount of warpage of the support substrate, forming a mask body by electroforming metal in areas of the metal base layer where the photoresist layer is not formed, positioning the support substrate so that the first surface of the support substrate is perpendicular to the horizontal plane, measuring a second amount of warpage of the support substrate, and calculating a shrinkage rate of the mask body based on the amount of change in warpage calculated based on the first and second amounts of warpage and the internal stress of the support substrate calculated based on the amount of change in warpage. If the shrinkage rate of the mask body is less than the lower limit of a predetermined range and equal to or greater than a first threshold, or if the shrinkage rate of the mask body is greater than the upper limit of the predetermined range and equal to or less than a second threshold, changing the drawing coordinates of each of the predetermined patterns on a mask body to be manufactured next according to the shrinkage rate of the mask body.

FIG. 1 is a plan view of a deposition mask according to an embodiment of the present invention. FIG. 1 is a plan view of a deposition mask according to an embodiment of the present invention. 1 is a cross-sectional view of a deposition mask according to one embodiment of the present invention. 1 is a flowchart illustrating an outline of a manufacturing process of a deposition mask according to an embodiment of the present invention. 10 is a flowchart illustrating a process for adjusting the shrinkage rate of the mask body. 5A to 5C are cross-sectional views showing a method for manufacturing the mask body. 5A to 5C are cross-sectional views showing a method for manufacturing the mask body. 5A to 5C are cross-sectional views showing a method for manufacturing the mask body. 10 shows the results of a simulation of the amount of warpage when a plating layer is formed on a SUS substrate. 10 shows the results of a simulation of the amount of warpage when a plating layer is formed on a glass substrate. 6 is a diagram showing regions 301 to 305 shown in FIG. 5 schematically represented on a support substrate. 6 is an example of a photoresist layer after the magnification of a predetermined pattern is adjusted based on the shrinkage rate of the mask body obtained from FIG. 5. 5A to 5C are cross-sectional views showing a method of forming a mask frame on a mask body. 5A to 5C are cross-sectional views showing a method of forming a mask frame on a mask body. 5A to 5C are cross-sectional views showing a method of forming a mask frame on a mask body. 5A to 5C are cross-sectional views showing a method of forming a mask frame on a mask body. 5A to 5C are cross-sectional views showing a method of forming a mask frame on a mask body.

Each embodiment of the present invention will be described below with reference to the drawings, etc. However, the present invention can be embodied in various forms without departing from the spirit of the invention, and should not be construed as being limited to the description of the embodiments exemplified below.

In order to clarify the explanation, the drawings may show the width, thickness, shape, etc. of each part more schematically than in the actual embodiment. However, the examples shown in the drawings are merely examples and do not limit the interpretation of the present invention unless otherwise specified for the illustrated embodiment. In this specification and each drawing, components similar to those previously described with respect to the previous drawings are designated by the same reference numerals, and detailed descriptions may be omitted as appropriate.

In this specification and claims, when describing an aspect in which a structure is placed on top of another structure, the term "on top" is used, unless otherwise specified, to include both a case in which another structure is placed directly on top of the structure so as to be in contact with the structure, and a case in which another structure is placed above the structure via yet another structure.

(First embodiment)
The configuration of a deposition mask according to one embodiment of the present invention will be described with reference to FIGS. 1A to 1C.

1A and 1B are plan views of a deposition mask 10 according to one embodiment of the present invention. Specifically, FIG. 1A is a plan view of the deposition mask 10 as viewed from the first surface 110a of the mask body 110, and FIG. 1B is a plan view of the deposition mask 10 as viewed from the second surface 110b opposite to the first surface 110a of the mask body 110. Also, FIG. 1C is a cross-sectional view of the deposition mask 10 according to one embodiment of the present invention. Specifically, FIG. 1C is a cross-sectional view of the deposition mask 10 taken along line A1-A2 shown in FIG. 1A or 1B.

The deposition mask 10 includes a mask body 110, a mask frame 120, and a connecting portion 130. The mask body 110 has a first surface 110a and a second surface 110b. As shown in FIGS. 1A and 1B, the mask frame 120 and the connecting portion 130 are provided on the first surface 110a of the mask body 110. In addition, in a plan view, the mask frame 120 and the connecting portion 130 overlap the mask body 110. As shown in FIG. 1A, in a plan view viewed from the first surface 110a of the mask body 110, the mask frame 120 and the connecting portion 130 are exposed from the mask body 110. On the other hand, as shown in FIG. 1B, in a plan view viewed from the second surface 110b of the mask body 110, the mask frame 120 and the connecting portion 130 are not exposed from the mask body 110. In other words, in a plan view seen from the second surface 110b of the mask body 110, the mask frame 120 and the connection portion 130 are covered by the mask body 110.

The mask body 110 includes an opening region 111 and a non-opening region 112. The opening region 111 has openings 113 that penetrate the mask body 110 and correspond to the deposition pattern. On the other hand, the non-opening region 112 does not have any openings 113. The boundary between the opening region 111 and the non-opening region 112 is not always clear. However, in many cases, the openings 113 are formed according to the deposition pattern, and therefore the distance between two adjacent openings 113 has a predetermined pitch. Therefore, it is possible to distinguish between the opening region 111 and the non-opening region 112 based on the predetermined pitch of the deposition pattern.

The thickness of the mask body 110 is, for example, 1 μm or more and 10 μm or less. Furthermore, the mask body 110 is preferably formed from a material used in electroforming (or electrolytic plating). The mask body 110 is formed by electroforming from a material such as nickel or a nickel alloy.

When performing a deposition process using the deposition mask 10, a substrate to be deposited is provided on the second surface 110b of the mask body 110. For example, a circuit board with transistors and other elements formed thereon is used as the substrate to be deposited. The deposition mask 10 is fixed in the chamber of the deposition device, sandwiching the substrate to be deposited between them and the deposition mask 10, while being attracted by magnets provided in the deposition device. In the deposition device, a deposition source is provided on the first surface 110a side of the mask body 110. By heating the deposition source, the organic material is heated and sublimated or evaporated. During this deposition process, the organic material is deposited only through the openings 113 in the mask body 110. Therefore, a pattern (deposition pattern) corresponding to the openings 113 is formed on the substrate to be deposited. The openings 113 can be provided, for example, to correspond to the pixel arrangement of a display device and can be arranged in a matrix. The openings 113 are arranged in the x-axis direction (also referred to as the first direction) and the y-axis direction (also referred to as the second direction). In FIG. 1A, if the center of the mask body 110 is the reference point and the coordinates of the reference point are O (0, 0), the four corners of the substrate are coordinates A (-x, y), B (-x, -y), C (x, -y), and D (x, -y).

The mask frame 120 includes a frame portion 121 located on the outer periphery of the deposition mask 10 and crosspieces 122 located inside the frame portion 121. The mask frame 120 has an opening on the inside of the frame portion 121, and this opening is partitioned by crosspieces 122 arranged in a grid pattern. If the size of the mask frame 120 increases, it may be difficult to maintain the parallelism of the mask frame 120 at a predetermined standard due to warping or twisting of the frame portion 121. In the deposition mask 10, the crosspieces 122 increase the rigidity of the frame portion 121, making it possible to maintain the parallelism of the mask frame 120 at a predetermined standard. Note that if the size of the deposition mask 10 is small and the rigidity of the frame portion 121 is sufficiently high, the crosspieces 122 may not be provided.

The mask frame 120 may be formed by integrating the frame portion 121 and the crosspiece portion 122, or by manufacturing the frame portion 121 and the crosspiece portion 122 separately and welding them together.

In FIG. 1A, the mask frame 120 is divided into 12 openings by the crosspieces 122, but the number of divided openings is not limited to this. The number of divided openings can be determined appropriately according to the size of the substrate to be vapor-deposited and the vapor deposition pattern. Furthermore, the arrangement of the crosspieces 122 is not limited to a grid pattern. When the mask frame 120 is a rectangle with short and long sides, warping or twisting is more likely to occur on the long sides than on the short sides. For this reason, it is preferable that the crosspieces 122 are provided so as to connect the opposing long sides. Furthermore, the arrangement of the crosspieces 122 may be shaped according to the vapor deposition pattern.

The width of the frame portion 121 and the width of the crosspiece 122 can be determined appropriately according to the size of the deposition mask 10. Note that, in order to maximize the area of the deposition pattern, it is preferable that the width of the crosspiece 122 be smaller than the width of the frame portion 121.

The thickness of the mask frame 120 is, for example, 10 μm or more and 2000 μm or less. Furthermore, the mask frame 120 is preferably formed from a material with a low thermal expansion coefficient. For example, the mask frame 120 can be formed from a material such as Invar, which contains iron and nickel, or Super Invar, which contains iron, nickel, and cobalt.

The connection part 130 can connect the mask body 110 and the mask frame 120. As shown in FIG. 1C, the mask body 110 and the mask frame 120 are in direct contact with each other, but are not glued or joined to each other. By joining the connection part 130 to the mask body 110 and the mask frame 120, the mask body 110 and the mask frame 120 are connected and fixed via the connection part 130.

The connecting portion 130 may be provided on at least a portion of the side surface of the frame portion 121 or crosspiece 122 of the mask frame 120. However, to increase the bonding strength between the mask body 110 and the mask frame 120, the connecting portion 130 is preferably provided on at least half of the side surface of the frame portion 121 or crosspiece 122, and more preferably on the entire side surface of the frame portion 121 or crosspiece 122. The connecting portion 130 is preferably formed from a material used in electroforming. The connecting portion 130 is formed from a material such as nickel or a nickel alloy, for example. The material of the connecting portion 130 may be the same as or different from the material of the mask body 110.

As described above, in the deposition mask 10, the mask body 110 and the mask frame 120 are in direct contact with each other, but the mask body 110 and the mask frame 120 are not directly fixed to each other. Therefore, even if the mask body 110 and the mask frame 120 are made of materials with different thermal expansion coefficients, the stress of the mask body 110 or the mask frame 120 can be dispersed. Note that the mask body 110 and the mask frame 120 may not be in direct contact with each other, and a gap may be provided between the mask body 110 and the mask frame 120. In this case, the stress of the mask body 110 or the mask frame 120 can also be dispersed.

During the mask body manufacturing process, when the plating layer consisting of the fine pattern formed by electroplating is separated from the plating support substrate, the plating layer shrinks due to stress in the plating layer. This causes the opening area to shift from the desired position, so managing the plating layer's shrinkage rate is important. However, since the plating layer's shrinkage rate cannot be measured unless the plating layer is separated from the support substrate, it takes several days to feed back the measured plating layer shrinkage rate results to the fine pattern formation process and the plating layer formation process.

On the other hand, one method for measuring the shrinkage rate of a plating layer is to form a plating layer on a dummy support substrate, then immediately peel it off and measure the shrinkage rate of the plating layer. In this case, the plating layer needs to be formed thick enough so that it will not be damaged or deformed even if it is peeled off alone. However, because the plating layer peeled off from the dummy support substrate is in a different state from the plating layer that makes up the actual mask body, the shrinkage rate cannot be accurately evaluated.

In view of the above problems, one object of one embodiment of the present invention is to provide a method for manufacturing a deposition mask with improved positional accuracy of the opening area.

In one embodiment of the present invention, in-line inspection of the shrinkage rate of the mask body is performed during the deposition mask manufacturing process, and the inspection results are fed back to the previous process. This allows the shrinkage rate of the mask body to be inspected at the stage when the mask body is formed, before the deposition mask is completed, and the inspection results can be fed back earlier. It also makes it possible to reduce the number of deposition masks manufactured that have a large shrinkage rate and low positional accuracy of the opening area. In other words, it is possible to improve the yield of usable deposition masks.

Below, a method for manufacturing a deposition mask according to one embodiment of the present invention will be described with reference to Figures 2 to 9E.

Figure 2 is a flowchart outlining a method for manufacturing a deposition mask. In this embodiment, the deposition mask 10 is manufactured as follows. First, when the manufacturing process for the deposition mask 10 is started, it is determined whether the termination conditions for the manufacturing process are met (step S401). If the termination conditions are met (step S401; Yes), the process proceeds. If the termination conditions are not met (step S401; No), the process proceeds to a process for adjusting the shrinkage rate of the mask body (step S402). Next, it is determined whether the termination conditions for the loop are met (step S403). If the termination conditions for the loop are not met (step S403; No), the process proceeds to a mask body formation process (step S404) and a mask frame formation process (step S405), and then the process returns to step S403, and the loop processing is repeatedly executed. If the termination conditions for the loop are met (step S403; Yes), the process returns to step S401. In the following description, the deposition masks 10 will be referred to as deposition masks 10-1, 10-2, and 10-3 in the order in which they are manufactured, and will be referred to as deposition masks 10 when the order of manufacture is not distinguished. The same applies to the components of the deposition mask 10. Each of the steps S401 to S405 will be described in detail below.

The termination condition in step S401 is, for example, whether a predetermined number of deposition masks 10 have been manufactured, or whether an operation to terminate the manufacturing of deposition masks has been performed. Here, the case of manufacturing the first deposition mask 10-1 is described, so if the termination condition is not met (step S401; No), the process proceeds to step S402.

The process of adjusting the shrinkage rate of the mask body in step S402 will be explained with reference to Figures 3 and 4A to 4C.

Figure 3 is a flowchart illustrating a process for adjusting the shrinkage rate of the mask body 110. First, a photoresist layer 230 having a predetermined pattern is formed on a support substrate 210 on which the Nth mask body will be formed (step S411 shown in Figure 3). Here, the explanation assumes that N = 1. The predetermined pattern is an opening pattern formed in the mask body. Figure 4A illustrates a process for forming a metal layer 220 on the support substrate 210 and then forming a photoresist layer 230 having a predetermined pattern on the metal layer 220. The support substrate 210 has a first surface 210a and a second surface 210b. The metal layer 220 is formed on the first surface 210a side. In a plan view, the shape of the pattern of the photoresist layer 230 is, for example, approximately rectangular. In this case, the pattern arrangement corresponds to the pixel arrangement of the display device and is arranged in a matrix. When manufacturing the first deposition mask 10-1, the pattern arrangement may be a pattern designed to be unaffected by the shrinkage of the mask body, or it may be a pattern designed from the beginning taking the influence of the shrinkage of the mask body into consideration.

The support substrate 210 supports each layer during the manufacturing process of the deposition mask 10. For this reason, the support substrate 210 is preferably a rigid substrate. The manufacturing process of the deposition mask 10 includes a step of heating the support substrate 210. If the support substrate 210 expands or contracts due to the heating process, not only will the position of the photoresist layer 230 formed on the support substrate 210 be misaligned, but stress may also cause peeling. For this reason, in order to stabilize the manufacturing process of the deposition mask 10, it is more preferable that the support substrate 210 be a rigid substrate with a small thermal expansion coefficient. Examples of materials for the support substrate 210 include stainless steel (such as SUS304 or SUS430), 42 alloy, invar, super invar, or stainless invar. A glass substrate may also be used as the support substrate 210.

The metal layer 220 functions as the base metal in the first electroforming process. Examples of materials for the metal layer 220 include nickel or a nickel alloy. The metal layer 220 is formed by sputtering, electroforming, electroless plating, or the like.

The metal layer 220 will eventually be separated and removed. Therefore, a conductive layer may be provided on the metal layer 220 to make it easier to separate the metal layer 220 from the support substrate 210. In this case, the metal layer 220 can be easily separated from the support substrate 201 by peeling off the conductive layer.

The deposition mask 10 may be manufactured using electroless plating instead of electroforming. If electroless plating is used, an insulating layer may be used instead of the metal layer 220.

The photoresist layer 230 functions as a mask in the first electroforming process. The photoresist layer 230 is formed into the desired shape by placing photoresist on the metal layer 220 to a predetermined thickness and developing it. The photoresist may be a dry film resist, which is in film form and can be applied and processed, or a liquid coating resist. The photosensitivity may be either positive or negative. The following description will use a negative photosensitive dry film as an example.

The photoresist layer 230 has a pattern that corresponds to the opening pattern of the mask body 110 of the deposition mask 10. The pattern of the photoresist layer 230 is formed by photolithography. That is, the pattern of the photoresist layer 230 is formed by adhering a photomask to the dry film resist, exposing the dry film to ultraviolet light, and dissolving and removing the unexposed portions.

Next, the amount of warpage of the support substrate 210 on which the metal layer 220 and photoresist layer 230 have been formed is measured (see step S412 in Figure 3). The amount of warpage of the support substrate 210 is measured using, for example, a laser displacement sensor. The laser displacement sensor measures the amount of warpage by irradiating the support substrate 210 with laser light and forming an image of the reflected light using a CMOS sensor. The laser displacement sensor obtains data on the amount of warpage in the XY plane of the support substrate 210. The amount of warpage obtained for each coordinate in the XY plane of the support substrate 210 is called warpage data. The number of warpage points to be obtained is set appropriately depending on the area of the support substrate 210.

When measuring the amount of warpage of the support substrate 210, it is preferable to position the support substrate 210 so that the first surface 210a of the support substrate 210 is perpendicular to the horizontal plane and measure the amount of warpage of the support substrate 210. If the support substrate 210 is positioned so that the first surface 210a of the support substrate 210 is parallel to the horizontal plane and the amount of warpage of the support substrate 210 is measured, the amount of warpage will be reduced due to the weight of the support substrate 210, making it impossible to measure the amount of warpage accurately. By positioning the support substrate 210 so that the first surface 210a of the support substrate 210 is perpendicular to the horizontal plane, the effect of the weight of the support substrate 210 can be reduced, and the amount of warpage of the support substrate 210 can be measured accurately. If the effect of the weight of the support substrate 210 is small, the first surface 210a of the support substrate 210 may be tilted ±20° from perpendicular to the horizontal plane.

Next, a first plating layer 240 is formed on the support substrate 210 (see step S413 in FIG. 3). FIG. 4B shows the process of forming the first plating layer 240 using the photoresist layer 230 as a mask. The first plating layer 240 is formed by electroforming (plating).

The plating solution used in electroforming is typically a solvent in which one or more metal salts, organic electrolytes, acids such as phosphoric acid, alkaline substances, or other electrolytes are dissolved. Examples of solvents include water, alcohols such as methanol and ethanol, cyclic carbonates such as ethylene carbonate and propylene carbonate, linear carbonates such as dimethyl carbonate, ethyl methyl carbonate, and diethyl carbonate, or mixtures of these solvents.

The metal salt can be selected appropriately taking into consideration the metal or alloy to be precipitated. Examples of metals for the metal salt include Cu, Zn, Ga, As, Cr, Se, Mn, Fe, Co, Ni, Ag, Cd, In, Sn, Sb, Te, Ru, Rh, Pd, Au, Hg, Tl, Pb, Bi, W, Po, Re, Os, Ir, and Pt. Among these, Ni, Ag, Au, Cd, Co, Cr, Cu, Fe, Sn, and Zn are preferred, with Ni being particularly preferred. These metals may be used alone or in combination of two or more.

Specific examples of metal salts that are the main components of plating solutions include nickel sulfate, nickel sulfate, nickel chloride, nickel sulfamate, and nickel chloride for nickel plating solutions. These metal salts may be used alone or in combination with two or more. Cobalt sulfamate may also be added to the nickel plating solution.

In the first electroforming process, the metal layer 220 and photoresist layer 230 are placed in an electroforming tank containing the above-mentioned plating solution prepared under specified conditions. Metal plating is then formed from the surface of the metal layer 220 that is not covered by the photoresist layer 230 up to the height of the photoresist layer 230. Examples of materials for the first plating layer 240 include nickel or a nickel alloy.

In this embodiment, nickel sulfamate is preferably used as the metal salt. By using nickel sulfamate as the metal salt and adjusting the current density, the internal stress of the deposited nickel film can be adjusted. Furthermore, the internal stress may be reduced by adding a stress reducer such as saccharin to the plating solution.

Adding impurities to the nickel plating solution can also adjust the internal stress of the nickel film. Adding organic species, such as compounds containing sulfur atoms in their molecules, to the nickel plating solution can induce compressive stress in the nickel film. Adding inorganic species, such as iron (II, III) ions, zinc ions and their hydroxides, or chromate ions, or organic species, such as 2-butyne-1,4-diol and 2-propyne-1-ol, which have double bonds in their molecules, to the nickel plating solution can induce tensile stress in the nickel film. To impart compressive stress to the nickel film, it is preferable to add impurities that induce compressive stress to the nickel plating solution. Furthermore, to adjust the stress in the nickel film, impurities that induce tensile stress may be added in addition to impurities that induce compressive stress.

Next, the amount of warpage of the support substrate 210 on which the first plating layer 240 has been formed is measured (see step S414 shown in FIG. 3). The method for measuring the amount of warpage in step S414 is the same as the method for measuring the amount of warpage in step S412. Furthermore, the coordinates of the amount of warpage measured in step S414 correspond to the coordinates of the amount of warpage measured in step S412. This allows data on the amount of warpage in the XY plane to be obtained. In the following description, the amount of warpage measured before the first plating layer 240 is formed will be referred to as the first amount of warpage, and the amount of warpage measured after the first plating layer 240 is formed will be referred to as the second amount of warpage.

Next, the change in warpage δ is calculated based on the first and second warpage amounts before and after the formation of the first plating layer 240. The change in warpage δ can be calculated by subtracting the first warpage amount from the second warpage amount for each coordinate. Next, the internal stress σ of the first plating layer 240 is calculated based on the change in warpage δ (step S415 shown in Figure 3). The internal stress σ of the first plating layer 240 is calculated using the following formula (1):

In equation (1), Es represents the Young's modulus of the support substrate 210, b represents the thickness of the support substrate 210, ν represents the Poisson's ratio of the support substrate 210, L represents the distance from the reference point of the support substrate 210, and d represents the thickness of the first plating layer 240. Based on equation (1), the internal stress σ can be calculated for each coordinate in the XY plane. The internal stress σ calculated for each coordinate in the XY plane of the support substrate 210 is referred to as internal stress data. The internal stress data for each coordinate has a one-to-one relationship with the amount of warpage at that coordinate, but it may be calculated for all coordinates, or, based on the assumption that the amount of change in stress within the surface of the support substrate is constant, the stress values at other coordinates may be approximated based on the relationship between the stress values and the amount of warpage at several points sampled within the surface.

Next, the shrinkage rate ε of the first plating layer 240 is calculated based on the internal stress σ of the first plating layer 240 (step S416 shown in FIG. 3). The shrinkage rate ε of the first plating layer 240 is calculated by the following formula (2).

By performing the above calculations on the internal stress data in the XY plane, data on the shrinkage rate ε of the first plating layer 240 in the XY plane can be obtained.

Next, the shrinkage rate ε of the first plating layer 240 is determined to be within a predetermined range (step S417). The allowable predetermined range for the shrinkage rate ε varies depending on the material of the support substrate, such as the Young's modulus and thickness. For example, if the shrinkage rate ε is within the predetermined range at all four corner coordinates of the support substrate 210, the shrinkage rate ε may be determined to be within the predetermined range. For example, if the shrinkage rate ε is within the predetermined range at predetermined coordinates other than the four corner coordinates of the support substrate 210, the shrinkage rate ε may be determined to be within the predetermined range. If the shrinkage rate ε is determined to be within the predetermined range (step S417; Yes), proceed to step S422, where the photoresist layer 230 is removed. Figure 4C shows the process of stripping the photoresist layer 230 from the surface of the metal layer 220. The photoresist layer 230 is stripped using, for example, an amine-based stripper. This results in the formation of a first plating layer 240 having opening regions 111 and non-opening regions 112.

Before removing the photoresist layer 230, the first plating layer 240 formed by electroforming may be polished. By polishing the first plating layer 240, the surface of the first plating layer 240 can be flattened.

The first plating layer 240 corresponds to the mask body 110 of the vapor deposition mask 10. Therefore, for convenience, the following description will refer to the first plating layer 240 as the mask body 110.

Next, a mask frame formation process is performed (step S423). The mask frame formation process will be described in detail later. When the formation of the mask frame is complete, the manufacture of the deposition mask 10-1 is complete. After the process of adjusting the shrinkage rate of the mask body 110 is completed, the process proceeds to step S403 shown in Figure 2.

In the manufacturing process of the deposition mask 10-1, if it is determined in step S417 that the shrinkage rate is not within the predetermined range (step S417; No), the process proceeds to step S418. For example, if the shrinkage rate ε is not within the predetermined range at any of the coordinates of the four corners of the support substrate 210, it may be determined that the shrinkage rate ε is not within the predetermined range. For example, even if the coordinates of the four corners of the support substrate 210 are within the predetermined range, if the shrinkage rate ε is not within the predetermined range at predetermined coordinates other than the four corner coordinates, it may be determined in step S417 that the shrinkage rate ε is not within the predetermined range. In step S418, it is determined whether the shrinkage rate is greater than or equal to a first threshold value or less than or equal to a second threshold value. Here, the first threshold value is a value smaller than the lower limit of the predetermined range, and the second threshold value is a value larger than the upper limit of the predetermined range. Like the predetermined range, the first and second threshold values of the allowable shrinkage rate vary depending on the material of the support substrate, such as Young's modulus and thickness. Therefore, in a display device pattern where multiple patterns are arranged on a surface, the values at which the opening pattern with the greatest positional misalignment deviates from the original opening pattern by approximately ±1/2 the pixel pitch at a certain point where the misalignment is zero are referred to as the first and second thresholds. Here, the deposition mask has the relationship: shrinkage rate ∝ stress ∝ tension. If the tension is too large, the deposition mask will deform significantly, making pattern adjustment difficult. Furthermore, if the tension is too small, the mask itself will expand when the mask temperature rises during the deposition process, causing the tension to drop to zero and the mask to sag.

If it is determined that the shrinkage rate is equal to or greater than the first threshold or equal to or less than the second threshold (step S418; No ), the drawing coordinates of the predetermined pattern of the (N+1)th photoresist layer are adjusted so that the calculated shrinkage rate falls within a predetermined range (step S419). Here, since N = 1, the drawing coordinates of the predetermined pattern of the photoresist layer in the manufacturing process of the next deposition mask 10-2 are adjusted. If the center of the support substrate 210 is used as the reference point, the shrinkage rate tends to increase toward the peripheral region of the support substrate 210. In this case, the magnification of the drawing of the predetermined pattern may be increased from the reference point (coordinate O) of the support substrate 210 toward the peripheral region. In other words, the magnification of the drawing of the predetermined pattern may be linearly increased from the reference point on the support substrate 210 toward the peripheral region. The drawing coordinates are changed by increasing the magnification of the drawing of the predetermined pattern. Furthermore, the uniformity of the film thickness of the first plating layer 240 in the XY plane affects the shrinkage rate in the XY plane. Therefore, in the XY plane, the magnification of the predetermined pattern may be increased in areas with a relatively high shrinkage rate, and decreased in areas with a relatively low shrinkage rate. Alternatively, the support substrate 210 may be divided into multiple regions, and the magnification of the predetermined pattern may be set for each region. The reference point of the support substrate 210 does not have to be the center of the support substrate 210; instead, the reference point may be the point or region with the smallest shrinkage rate among the shrinkage rate data of the first plating layer 240 in the XY plane. Adjusting the drawing coordinates of the predetermined pattern of the (N+1)th photoresist layer completes the process in step S402. Thereafter, to manufacture the (N+1)th mask body, the process in step S402 may be started from step S411.

In step S418, if the two-dimensional data of the shrinkage rate ε is determined to be less than the first threshold or greater than the second threshold (step S418; Yes ), the conditions of the first electroforming process are adjusted so that the calculated shrinkage rate ε falls within a predetermined range (step S420). Here, since N = 1, the drawing of a predetermined pattern on the photoresist layer in the manufacturing process of the next deposition mask 10-2 is adjusted. Because the mask body 110 has a large shrinkage rate, a stress reducer may be added to the plating solution in the first electroforming process. Furthermore, nickel sulfamate may be used as a metal salt in the plating solution to adjust the current density. Furthermore, when a nickel plating solution is used as the plating solution, impurities may be added. Another method of stress adjustment is to adjust the temperature of the plating solution. Alternatively, multiple stress adjustment methods may be used in combination. Furthermore, the processing time of the first electroforming process may be adjusted. After adjusting the conditions of the (N+1)th first electroforming process, the process in step S402 is completed. Thereafter, in order to manufacture the (N+1)th (here, the second) mask body, the process of step S402 can be started from step S411.

By performing steps S411 to S420, the shrinkage rate of the Nth manufactured mask body can be used as feedback to the predetermined pattern formation process of the photoresist layer for the N+1th mask body to be manufactured next, and to the first electroforming process. This improves the accuracy of the opening position in the mask body 110, stabilizing the manufacturing process.

In step S403, it is determined whether the loop termination condition is met. The loop termination condition is whether a predetermined number of deposition masks 10 have been manufactured. Here, the predetermined number in step S403 is smaller than the predetermined number in step S401. The predetermined number in step S403 is, for example, the number for returning to the process of adjusting the shrinkage rate of the mask body (step S402) after repeatedly performing the cycle of manufacturing the deposition mask 10 (steps S404 and S405). After manufacturing the predetermined number of deposition masks 10, the shrinkage rate of the mask body 110 is inspected for abnormalities, and if there is an abnormality in the shrinkage rate of the mask body 110, the shrinkage rate can be adjusted early. Therefore, if the predetermined number of deposition masks 10 has been reached (Step S403; Yes), the process returns to Step S402 to check whether there are any abnormalities in the shrinkage rate of the mask body 110. If the predetermined number of deposition masks 10 has not been reached (Step S403; No), the processes of Steps S404 and S405 are repeated.

The deposition mask 10 can be manufactured through the above steps.

In a method for manufacturing a deposition mask according to one embodiment of the present invention, rather than forming a plating layer on a dummy support substrate for measurement and then peeling it off from the support substrate to measure the shrinkage rate, the first plating layer 240 (mask body 110) to be used as a product is formed, and the shrinkage rate of the first plating layer 240 can be calculated without peeling the first plating layer 240 from the support substrate. This allows measurement at the same thickness as the plating layer that constitutes the mask body 110. Therefore, the shrinkage rate can be evaluated more accurately than when measuring the shrinkage rate using a dummy substrate. Furthermore, the calculated shrinkage rate can be used to correct the conditions for the specified pattern or the conditions for the first electroforming process, allowing for early feedback.

In a method for manufacturing a deposition mask according to one embodiment of the present invention, the conditions for the predetermined pattern may be changed or the electroforming conditions may be changed. Changing the electroforming conditions each time the shrinkage rate of the mask body 110 is adjusted may require a long time to achieve the desired accuracy or for the plating solution to stabilize. This reduces the productivity of deposition masks. Therefore, rather than changing the electroforming conditions each time the shrinkage rate of the mask body 110 is adjusted, the shrinkage rate of the mask body 110 is adjusted by changing the conditions for the predetermined pattern of the photoresist layer 230. In areas where the shrinkage rate of the first plating layer 240 is large, the drawing coordinates may be corrected to increase the area of the predetermined pattern. This improves the positional accuracy of the opening areas of the first plating layer 240. Furthermore, when the shrinkage rate of the mask body 110 is large and correction by changing the predetermined pattern is difficult, changing the electroforming conditions can significantly reduce the time required to determine the conditions.

After manufacturing the mask body 110, only those mask bodies 110 that have achieved the desired shrinkage rate can be sent to the mask frame formation process. By manufacturing the deposition mask 10 using this flow, it is possible to determine whether or not a mask should be sent to the mask frame formation process, and the number of masks that become defective due to a high shrinkage rate of the mask body 110 and low positional accuracy of the opening area after mask frame formation can be reduced. In other words, the yield of final shipped products can be improved.

Figure 5 shows the results of a simulation of the amount of warping when the mask body 110 is formed using a SUS substrate as the support substrate. Figure 6 shows the results of a simulation of the amount of warping when the mask body is formed using a glass substrate as the support substrate. The conditions used in the calculations are listed below.

The support substrate was a SUS substrate with a Young's modulus Es = 200 GPa, thickness b = 1 mm, and size = 1000 mm x 800 mm. The first plating layer formed on the support substrate was a Ni alloy with a thickness d = 5 μm and internal stress σ = 40 MPa (tensile). The center of the support substrate was set to coordinate O (0,0), and the internal stress σ was calculated every 10 mm in the X direction and every 10 mm in the Y direction.

The support substrate was a glass substrate with a Young's modulus Es = 77 GPa, thickness b = 0.5 mm, and size = 1000 mm x 800 mm. The first plating layer formed on the support substrate was a Ni alloy with a thickness d = 5 μm and internal stress σ = 40 MPa (tensile). The center of the support substrate was set to coordinate O (0,0), and the internal stress σ was calculated every 10 mm in the X direction and every 10 mm in the Y direction.

Figures 5 and 6 show the XY plane of the support substrate. Coordinate O (0,0) is the reference point of the support substrate. In Figure 5, region 301 is the region where the change in warpage is 0 to 0.2, region 302 is the region where the change in warpage is 0.2 to 0.4, region 303 is the region where the change in warpage is 0.4 to 0.6, region 304 is the region where the change in warpage is 0.6 to 0.8, and region 305 is the region where the change in warpage is 0.8 to 1.0. Also, in Figure 6, region 311 is the region where the change in warpage is 0 to 2, region 312 is the region where the change in warpage is 2 to 4, region 313 is the region where the change in warpage is 4 to 6, region 314 is the region where the change in warpage is 6 to 8, and region 315 is the region where the change in warpage is 8 to 10. Glass substrates have a lower Young's modulus than SUS substrates, resulting in greater changes in the amount of warping.

As shown in Figures 5 and 6, the change in warpage δ increases from the coordinate O (0,0) of the substrate's reference point toward the coordinates A (-400,500), B (-400,-500), C (400,-500), and D (400,500) of the substrate's four corners. In other words, the amount of warpage increases from the coordinate O (0,0) of the substrate's reference point toward the coordinates A (-400,500), B (-400,-500), C (400,-500), and D (400,500) of the substrate's four corners.

Figure 7 is a diagram showing regions 301 to 305 shown in Figure 5, schematically represented on a support substrate. The amount of change in warpage increases toward the four corners of the support substrate. Although not shown, if regions 311 to 315 shown in Figure 6 were also represented on a support substrate, the distribution of change in warpage would be similar to that shown in Figure 7. Therefore, as the shrinkage rate of the mask body 110 increases, the area of the opening region of the mask body 110 decreases, tending to shift the position (coordinates) of the opening region. By measuring the shrinkage rate of the mask body 110, it is possible to predict the trend in the area of the opening region of the mask body 110. To correct the reduction in area and position (coordinates) of the opening region of the mask body 110, the specified pattern of the photoresist layer can be adjusted, or the plating solution conditions can be adjusted.

8 shows an example of photoresist layers 331-335 after adjusting the magnification of the predetermined pattern based on the shrinkage rate of the mask body obtained in FIG. 5. The photoresist layers 331-335 shown in FIG. 8 are partial views; in reality, the photoresist layers are formed over the entire support substrate. To change the magnification of the predetermined pattern, for example, the magnification can be set so that the magnification increases from region 301 to region 305 in a plan view. Therefore, the area increases from region 301 to region 305. Furthermore, the drawing coordinates of each predetermined pattern are changed so that the area of each predetermined pattern in the peripheral region of the support substrate is larger than the area of each predetermined pattern near the reference point on the support substrate in a plan view. This allows for the formation of a photoresist layer whose area of the predetermined pattern changes depending on the amount of warping of the mask body 110 when manufacturing the next deposition mask 10. This improves the shape and positional accuracy of the opening region in the XY plane of the mask body 110.

Next, the mask frame formation process will be described with reference to Figures 9A to 9E.

Figures 9A and 9B are diagrams illustrating the mask frame adhesion process. As shown in Figure 9A, a protective layer 250 is formed on the opening region 111 of the mask body 110. The protective layer 250 prevents particles generated in a process described below from entering the openings 113 in the opening region 111 and blocking the openings 113. The protective layer 250 can also function as a mask in the second electroforming process described below. The protective layer 250 is made of the same material as the photoresist layer 230.

Next, as shown in FIG. 9B, an adhesive layer 280 is provided on the non-opening region 112 of the mask body 110, and the mask frame 120 is adhered onto the adhesive layer 280. The adhesive layer 280 does not need to be completely hardened, as it will be removed in a process described later. Examples of materials that can be used for the adhesive layer 280 include vinyl acetate resin, ethylene vinyl acetate resin, epoxy resin, cyanoacrylate resin, and acrylic resin.

9C is a diagram illustrating the second electroforming step. As shown in FIG. 9C, a second plating layer 270 is formed to connect the mask body 110 and the mask frame 120. The second plating layer 270 can be formed by electroforming, which passes current through the metal layer 220 or the mask frame 120. The second plating layer 270 can be formed using a method similar to that used for the first plating layer 240. The second plating layer 270 is provided to fill the openings in the non-opening regions 112, so the second plating layer 270 is in contact with the metal layer 220. The second plating layer 270 also connects the upper and side surfaces of the non-opening regions 112 of the mask body 110 to the mask frame 120. In other words, the second plating layer 270 corresponds to the connection portion 130 of the vapor deposition mask 10. Therefore, for convenience, the second plating layer 270 will be described below as the connection portion 130.

Figures 9D and 9E are diagrams illustrating the process of separating the support substrate. As shown in Figure 9D, the protective layer 250 is peeled off. The protective layer 250 can be peeled off in the same manner as the photoresist layer 230.

Next, as shown in FIG. 9E, the support substrate 210 and metal layer 220 are separated from the mask body 110. The support substrate 210 and metal layer 220 may be separated simultaneously, or the metal layer 220 may be separated after the support substrate 210 is separated.

Through the above steps, a deposition mask 10 can be produced in which the mask frame 120 and connecting portion 130 overlap the mask body 110.

The order of steps in the manufacturing method of the vapor deposition mask 10 is not limited to that described above. For example, the formation of the protective layer 250 shown in FIG. 9A may be performed after the mask frame 120 shown in FIG. 9B has been attached to the mask body. Furthermore, the peeling of the protective layer 250 shown in FIG. 9D may be performed after the separation of the support substrate 210 shown in FIG. 9E.

In this embodiment, a method for forming the mask body 110 by electroplating has been described, but one embodiment of the present invention is not limited to this. The mask body 110 can also be formed from a film formed by other metal foil film formation techniques, such as a film formed by electroless plating or a film formed by sputtering. The film used as the mask body 110 may be patterned by etching as appropriate.

The above-described embodiments of the present invention can be implemented in any suitable combination, provided they are not mutually inconsistent. Furthermore, even if a person skilled in the art has appropriately added or deleted components or modified the design based on each embodiment, or has added or omitted steps or modified conditions, these are also included within the scope of the present invention, as long as they incorporate the essence of the present invention.

Even if there are other effects and advantages different from those achieved by the aspects of the above-described embodiments, if they are clear from the description in this specification or can be easily predicted by a person skilled in the art, they are naturally considered to be achieved by the present invention.

10, 10-1 to 10-3: deposition mask, 110: mask body, 110-1: mask body, 110-2: mask body, 110a: first surface, 110b: second surface, 111: opening area, 112: non-opening area, 113: opening, 120: mask frame, 121: frame portion, 122: crosspiece portion, 130: connection portion, 210: support substrate, 210a: first surface, 210b: second surface, 220: metal layer, 230: photoresist layer, 240: first plating layer, 250: protective layer, 270: second plating layer, 280: adhesive layer, 301 to 305: regions, 311 to 315: regions

Claims (5)

forming a photoresist layer having a predetermined pattern on a support substrate via a base metal layer;
placing the support substrate so that a first surface of the support substrate is perpendicular to a horizontal plane, and measuring a first warpage amount of the support substrate;
forming a mask body by depositing metal by electroforming in an area of the base metal layer where the photoresist layer is not formed;
the support substrate is disposed so that a first surface of the support substrate is perpendicular to a horizontal plane, and a second warpage amount of the support substrate is measured;
calculating a shrinkage rate of the mask body based on a change in the amount of warpage calculated based on the first amount of warpage and the second amount of warpage and an internal stress of the support substrate calculated based on the change in the amount of warpage;
a method for manufacturing a deposition mask, wherein when the shrinkage rate of the mask body is smaller than a lower limit value of a predetermined range and is equal to or larger than a first threshold value, or when the shrinkage rate of the mask body is larger than an upper limit value of a predetermined range and is equal to or smaller than a second threshold value, the method changes drawing coordinates of each of the predetermined patterns on a mask body to be manufactured next according to the shrinkage rate of the mask body. The method for manufacturing a deposition mask according to claim 1, wherein the electroforming conditions for the next mask body to be manufactured are changed when the shrinkage rate of the mask body is smaller than the lower limit of the predetermined range and less than the first threshold, or when the shrinkage rate of the mask body is larger than the upper limit of the predetermined range and exceeds the second threshold. The method for manufacturing a vapor deposition mask according to claim 1, wherein, when the shrinkage rate of the mask body is within the predetermined range, the photoresist layer is peeled off and a mask frame is formed on the mask body. The method for manufacturing a deposition mask according to claim 1, wherein the drawing coordinates are changed so that the area of the predetermined pattern increases radially from a reference point on the support substrate toward the peripheral region in a plan view. The method for manufacturing a deposition mask according to claim 1 , further comprising changing the drawing coordinates so that an area of the predetermined pattern in a peripheral region of the support substrate is larger than an area of the predetermined pattern in the vicinity of a reference point on the support substrate in a plan view.