Substrate for metal mask, metal mask, and method for manufacturing metal mask

Abstract

A base material for a metal mask is mainly composed of an iron-nickel alloy. The substrate for a metal mask contains 0.25 mass% to 0.40 mass% (inclusive) of elemental manganese, and has a thickness of 50 [mu] m or less.

Description

Technical Field

[0001] The present disclosure relates to a substrate for a metal mask, a metal mask, and a method for manufacturing a metal mask. Background Art

[0002] An example of a method for forming pixels included in an organic EL display device is a vacuum evaporation method. In the vacuum evaporation method, a metal evaporation mask having a plurality of through holes is used. Each through hole has a shape corresponding to the shape of a pixel, and the plurality of through holes are arranged according to the arrangement of pixels. Each through hole is a passage through which an evaporation material for forming a pixel passes. As a material for forming the evaporation mask, a metal thin plate made of an iron-nickel alloy (for example, refer to Patent Document 1) is used.

[0003] When manufacturing an evaporation mask from a metal thin plate, first, a resist layer is formed on the surface of the metal thin plate, and then a resist pattern is formed from the resist layer. Then, a plurality of through holes are formed in the metal thin plate by wet etching using the resist pattern.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: WO 2018 / 235862 Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] However, in various electronic devices equipped with an organic EL display device, high-definition images are required to be displayed. Therefore, high definition is required for the pixels included in the organic EL display device, and further high definition is required for the evaporation mask used for forming the pixels. For example, in an evaporation mask for forming high-definition pixels of about 500 ppi, the maximum size of the opening located on the surface of the metal thin plate is miniaturized to several tens of μm. In the formation of through holes having miniaturized openings, wet etching is excessively performed in some of the plurality of through holes, thereby causing new problems such as the through holes becoming larger. It should be noted that such problems are common not only to metal masks used in the evaporation method but also to metal masks used in film-forming methods other than the evaporation method.

[0009] Means for Solving the Problems

[0010] A substrate for a metal mask for solving the above problems is a substrate for a metal mask mainly composed of an iron-nickel alloy, contains 0.25 mass% or more and 0.40 mass% or less of manganese element, and has a thickness of 50 μm or less.

[0011] According to the above-described substrate for a metal mask, the substrate for a metal mask contains 0.25 mass% or more of manganese, the standard electrode potential of which is lower than that of iron and nickel elements. Therefore, the substrate for a metal mask is in a state of being easily corroded. Thus, the corrosion potential generated when the etching solution comes into contact with the substrate for a metal mask becomes lower. As a result, it is difficult to generate pitting corrosion when the substrate for a metal mask comes into contact with the etching solution. Consequently, it is possible to suppress the excessive wet etching locally on the substrate for a metal mask, and thus suppress the enlargement of a part of the through holes among the plurality of through holes.

[0012] The above-described substrate for a metal mask may contain 0.03 mass% or more and 0.05 mass% or less of silicon element. According to this substrate for a metal mask, since the substrate for a metal mask contains 0.03 mass% or more and 0.05 mass% or less of silicon element, it is possible to suppress galvanic corrosion between the metal elements located near the silicon element, and thus further suppress the enlargement of a part of the through holes.

[0013] The above-described substrate for a metal mask may contain 63.5 mass% or more and 64.5 mass% or less of iron element, 35.0 mass% or more and 36.5 mass% or less of nickel element, and 0.29 mass% or more and 0.7 mass% or less of additive element, and the additive element may include the manganese element.

[0014] According to the above-described substrate for a metal mask, since the content ratios of the iron element, nickel, and the additive element respectively satisfy the above ranges, the effectiveness of the manganese element content ratio being 0.25 mass% or more and 0.40 mass% or less is improved.

[0015] A metal mask for solving the above problems is a metal mask formed from a substrate for a metal mask mainly composed of an iron-nickel alloy, contains 0.25 mass% or more and 0.40 mass% or less of manganese element, the maximum value of the thickness is 50 μm or less, and has a first surface and a plurality of through holes having openings in the first surface. The area of the opening is 1600 μm 2 below.

[0016] According to the above metal mask, the substrate for a metal mask contains 0.25 mass% or more of manganese, the standard electrode potential of which is lower than that of iron and nickel elements. Therefore, the substrate for a metal mask is in a state of being easily corroded. Thus, the corrosion potential generated when the etching solution comes into contact with the substrate for a metal mask becomes lower. As a result, it is difficult to generate pitting corrosion when the substrate for a metal mask comes into contact with the etching solution. Consequently, even when forming through holes with micro-fine openings of 1600 μm 2 below, it is possible to suppress the excessive wet etching locally on the substrate for a metal mask, and thus suppress the enlargement of a part of the through holes among the plurality of through holes.

[0017] The above metal mask may include an oxide layer containing an oxide of the iron-nickel alloy, and the oxide layer includes the first surface. According to this metal mask, since the metal mask includes an oxide layer, when forming through holes provided in the metal mask, pitting is likely to occur in the metal mask substrate used for forming the metal mask. Therefore, in the metal mask substrate, the effectiveness of the content rate of manganese element whose standard electrode potential is lower than that of iron and nickel being 0.25 mass% or more and 0.40 mass% or less is improved.

[0018] A method for manufacturing a metal mask for solving the above problems includes: forming a plurality of through holes in a metal mask substrate by wet etching, the metal mask substrate containing 0.25 mass% or more and 0.40 mass% or less of manganese element, mainly composed of an iron-nickel alloy, having a thickness of 50 μm or less, and having a first surface. Forming the plurality of through holes is to form the following through holes: having an opening on the first surface and the area of the opening being 1600 μm 2 or less.

[0019] According to the above method for manufacturing a metal mask, the metal mask substrate contains 0.25 mass% or more of manganese element whose standard electrode potential is lower than that of iron element and nickel element. Therefore, the metal mask substrate is in a state where it is easily corroded, and thus the corrosion potential generated when the etching solution contacts the metal mask substrate becomes lower. As a result, it is difficult to generate pitting when the metal mask substrate contacts the etching solution. As a result, even when forming through holes having a micro-refined opening of 1600 μm 2 or less, it is possible to suppress the local excessive wet etching in the metal mask substrate, and thus suppress a part of the through holes among the plurality of through holes from becoming larger.

[0020] In the above method for manufacturing a metal mask, forming the plurality of through holes may include: forming the plurality of through holes by wet etching the metal mask substrate with a ferric chloride solution having a Baumé degree of 47° or more and 52° or less.

[0021] According to the above method for manufacturing a metal mask, even when using a ferric chloride solution containing chloride ions that generates pitting as the etching solution, it is possible to suppress pitting from occurring when forming through holes in the metal mask substrate.

[0022] In the above method for manufacturing a metal mask, forming the plurality of through holes may include forming a resist pattern on the first surface, and the contact angle of the resist pattern with respect to the etching solution is 40° or less. According to this method for manufacturing a metal mask, the degree of freedom of the thickness of the resist pattern can be improved.

[0023] Effects of the Invention

[0024] According to the above-described substrate for a metal mask, the metal mask, and the method for manufacturing the metal mask, enlargement of a part of the plurality of through holes included in the metal mask is suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Figure 1 is a perspective view showing a substrate for a metal mask.

[0026] Figure 2 Figure 2 is Figure 1 a cross-sectional view of the substrate for a metal mask shown in

[0027] Figure 3 Figure 3 is a process chart showing a process of performing excessive wet etching on a part of the substrate for a metal mask.

[0028] Figure 4 Figure 4 is a process chart showing a process of performing excessive wet etching on a part of the substrate for a metal mask.

[0029] Figure 5 Figure 5 is a process chart showing a process of performing excessive wet etching on a part of the substrate for a metal mask.

[0030] Figure 6 Figure 6 is a schematic diagram for explaining pitting corrosion generated in the substrate for a metal mask.

[0031] Figure 7 Figure 7 is a process chart showing a process of performing excessive wet etching on a part of the substrate for a metal mask.

[0032] Figure 8 Figure 8 is a plan view showing a metal mask.

[0033] Figure 9 Figure 9 is Figure 8 a magnified plan view of a part of the metal mask shown in

[0034] Figure 10 Figure 10 is showing Figure 8 a cross-sectional view of the first example of the structure of the metal mask shown in

[0035] Figure 11 Figure 11 is showing Figure 8 a cross-sectional view of the second example of the structure of the metal mask shown in ​​​​​​​​​​​​​​​​​​​​​​

[0036] Figure 12 Figure 12 is a process chart showing one process included in the method for manufacturing a metal mask.

[0037] Figure 13 Figure 13 is a process chart showing one process included in the method for manufacturing a metal mask.

[0038] Figure 14 Figure 14 is a process chart showing one process included in the method for manufacturing a metal mask.

[0039] Figure 15 Figure 15 is a process chart showing one process included in the method for manufacturing a metal mask.

[0040] Figure 16 Figure 16 is a process chart showing one process included in the method for manufacturing a metal mask.

[0041] Figure 17 Figure 17 is a process chart showing one process included in the method for manufacturing a metal mask.

[0042] Figure 18 Figure 18 is a table showing the results of the compositional analysis of the metal mask substrate for the examples and comparative examples and the incidence of recess expansion.

[0043] Figure 19 Figure 19 is a graph showing the relationship between the incidence of recess expansion and the manganese element content rate when wet-etching the metal mask substrate with 47° Baume ferric chloride solution.

[0044] Figure 20 Figure 20 is a graph showing the relationship between the incidence of recess expansion and the manganese element content rate when wet-etching the metal mask substrate with 50° Baume ferric chloride solution.

[0045] Figure 21 Figure 21 is a graph showing the relationship between the predicted value of the incidence of recess expansion calculated based on the prediction formula for the manganese element and the measured value of the incidence of recess expansion.

[0046] Figure 22 Figure 22 is a graph showing the relationship between the predicted value of the incidence of recess expansion calculated based on the prediction formulas for the manganese element and the silicon element and the measured value of the incidence of recess expansion.

[0047] ​​​​​​​​​​​​​​​​​​​​​​Figure 23 Figure 23 is a graph showing the relationship between the etching depth and the incidence of recess expansion.

[0048] Figure 24 Figure 24 is an SEM image obtained by photographing a portion of the substrate for a metal mask where local excessive wet etching has not been performed.

[0049] Figure 25 Figure 25 is an SEM image obtained by photographing a portion of the substrate for a metal mask where local excessive wet etching has been performed.

[0050] Figure 26 Figure 26 is an SEM image obtained by photographing a portion of the substrate for a metal mask where local excessive wet etching has not been performed and a portion where local excessive etching has been performed.

[0051] Figure 27 Figure 27 is a graph showing the relationship between the contact angle of the resist pattern and the incidence of recess expansion when the thickness of the resist pattern is 10 μm.

[0052] Figure 28 Figure 28 is a graph showing the relationship between the contact angle of the resist pattern and the incidence of recess expansion when the thickness of the resist pattern is 5 μm. DETAILED DESCRIPTION

[0053] Refer to Figures 1 to 28 , and an embodiment of a substrate for a metal mask, a metal mask, and a method for manufacturing a metal mask will be described.

[0054] [Substrate for Metal Mask]

[0055] Refer to Figure 1 and Figure 2 , and the substrate for a metal mask will be described.

[0056] Figure 1 The substrate 10 for a metal mask shown in

[0057] ​​​​​​​​​​​​The substrate 10 for a metal mask may contain 0.03% by mass or more and 0.05% by mass or less of silicon (Si) element. The substrate 10 for a metal mask may contain 63.5% by mass or more and 64.5% by mass or less of iron (Fe) element, 35.0% by mass or more and 36.5% by mass or less of nickel (Ni) element, and 0.29% by mass or more and 0.7% by mass or less of additive elements. The additive elements are elements other than the main components of the substrate 10 for a metal mask, namely, iron element and nickel element. The additive elements include the above-mentioned manganese element.

[0058] In order to deoxidize the iron-nickel alloy, during the manufacturing process of the substrate 10 for a metal mask, manganese element is added as a deoxidizer to the iron-nickel alloy. By using manganese element instead of aluminum element and magnesium element as a deoxidizer, it is possible to suppress the inclusion of spinel (MgAl2O4) in the substrate 10 for a metal mask. However, since the content rate of manganese element in the substrate 10 for a metal mask increases, the manganese element is prone to segregation.

[0059] Similarly to the manganese element, in order to deoxidize the iron-nickel alloy, during the manufacturing process of the substrate 10 for a metal mask, silicon element is added as a deoxidizer to the iron-nickel alloy. By using silicon element instead of aluminum element and magnesium element as a deoxidizer, it is possible to suppress the inclusion of spinel in the substrate 10 for a metal mask. However, since the content rate of silicon element in the substrate 10 for a metal mask increases, the silicon element is prone to segregation.

[0060] It should be noted that the additive elements may include metal elements and non-metal elements other than the manganese element. The metal elements may be, for example, magnesium (Mg) element, aluminum (Al) element, chromium (Cr) element, molybdenum (Mo) element, cobalt (Co) element. The non-metal elements may be the above-mentioned silicon element, phosphorus (P) element, sulfur (S) element, chlorine (Cl) element.

[0061] The content rate of magnesium element may be, for example, 0.000% by mass or more and 0.007% by mass or less. The content rate of aluminum element may be, for example, 0.003% by mass or more and 0.029% by mass or less. The content rate of chromium element may be, for example, 0.004% by mass or more and 0.046% by mass or less. The content rate of molybdenum element may be, for example, 0.000% by mass or more and 0.010% by mass or less. The content rate of cobalt element may be, for example, 0.000% by mass or more and 0.265% by mass or less.

[0062] It should be noted that, generally, the larger the amount of each additive element added to the ingot for manufacturing the substrate 10 for a metal mask, the higher the content rate of the additive element in the substrate 10 for a metal mask tends to be. On the contrary, the smaller the amount of each additive added to the ingot for manufacturing the substrate 10 for a metal mask, the lower the content rate of the additive element in the substrate 10 for a metal mask tends to be. The substrate 10 for a metal mask is obtained by subjecting the ingot to rolling treatment or the like. The rolling treatment can be at least one of hot rolling and cold rolling. That is, the ingot can be subjected to only either hot rolling or cold rolling, or both hot rolling and cold rolling.

[0063] The substrate 10 for a metal mask has a strip shape including a surface 10F and a back surface 10R which is the surface on the side opposite to the surface 10F. The thickness T of the substrate 10 for a metal mask is the distance between the surface 10F and the back surface 10R. From the viewpoint of improving the operability of the substrate 10 for a metal mask, the thickness T of the substrate 10 for a metal mask is preferably 5 μm or more, more preferably 10 μm or more. When the substrate 10 for a metal mask is used for manufacturing a metal mask for vapor deposition, from the viewpoint of suppressing the shadow effect of the through holes formed in the substrate 10 for a metal mask on the vapor deposition material entering the through holes, the thickness T of the substrate 10 for a metal mask is preferably 30 μm or less, more preferably 20 μm or less. It should be noted that the situation of forming a shadow on the vapor deposition material is called the shadow effect of the metal mask. From the viewpoint of improving the operability of the substrate 10 for a metal mask and suppressing the shadow effect of the metal mask, the thickness of the substrate 10 for a metal mask is preferably 5 μm or more and 30 μm or less.

[0064] Figure 2 The cross-sectional structure of the substrate 10 for a metal mask is shown.

[0065] As Figure 2 shown, the substrate 10 for a metal mask is composed of a main layer 10A, a first surface layer 10B1, and a second surface layer 10B2. The main layer 10A is located between the first surface layer 10B1 and the second surface layer 10B2. The first surface layer 10B1 includes the surface 10F of the substrate 10 for a metal mask. The second surface layer 10B2 includes the back surface 10R of the substrate 10 for a metal mask. The first surface layer 10B1 and the second surface layer 10B2 are natural oxide films containing oxides of an iron-nickel alloy. The first surface layer 10B1 and the second surface layer 10B2 may contain oxides of at least a part of the additive elements. In contrast, in the main layer 10A, the iron-nickel alloy and the additive elements are not oxidized by the oxidation source existing around the alloy. Therefore, the content rate of oxygen element in each of the surface layers 10B1 and 10B2 is higher than the content rate of oxygen element in the main layer 10A.

[0066] The thickness of each of the surface layers 10B1 and 10B2 is, for example, greater than 0 nm and 10 nm or less, and alternatively, may be greater than 0 nm and 5 nm or less.

[0067] Among the metal elements contained in the base material 10 for a metal mask, iron and nickel form passivation due to oxidation. Since the first surface layer 10B1 and the second surface layer 10B2 contain iron and nickel, they are composed of passivation. It should be noted that among the elements that the base material 10 for a metal mask may contain, aluminum, chromium, and cobalt also form passivation due to oxidation.

[0068] [Function of the base material for a metal mask]

[0069] Refer to Figures 3 to 7 to explain the function of the base material 10 for a metal mask. Figures 3 to 5 and Figure 7 Schematically shows the process of wet-etching the base material 10 for a metal mask using the second resist pattern formed on the back surface 10R of the base material 10 for a metal mask. Figure 6 is a schematic diagram for explaining pitting corrosion generated when wet-etching the base material 10 for a metal mask.

[0070] As Figure 3 shown, when wet-etching the base material 10 for a metal mask, a second resist pattern RP2 is formed on the back surface 10R of the base material 10 for a metal mask. The second resist pattern RP2 has a second through-hole RP2A. From the perspective opposite to the back surface 10R, the second resist pattern RP2 is configured such that, through wet-etching via the second through-hole RP2A, an opening having an area of 1600 μm 2 or less can be formed on the back surface 10R of the base material 10 for a metal mask. It should be noted that from the viewpoint of being able to form higher-resolution pixels, the area of the opening is preferably 900 μm 2 or less.

[0071] As Figure 4 shown, when wet-etching the base material 10 for a metal mask from the back surface 10R of the base material 10 for a metal mask, an etchant ES is supplied to the second resist pattern RP2. The etchant is, for example, an etchant containing chloride ions and may be a ferric chloride solution. The method of wet-etching may be, for example, spray etching. In the case where the method of wet-etching is spray etching, the etchant ES supplied to the second resist pattern RP2 has a flow along a predetermined direction.

[0072] A part of the etchant ES supplied to the second resist pattern RP2 flows into the second through-hole RP2A. At this time, as described above, since the opening area of the second through-hole RP2A is as small as to form an opening having an area of 1600 μm 2The opening degree of the following area is such that it is difficult to uniformly supply the etching solution ES to the entire second through-hole RP2A.

[0073] As Figure 5 shown, the etching solution ES supplied to a part of the second through-hole RP2A etches a part of the part of the back surface 10R exposed in the second through-hole RP2A. As described above, since the back surface 10R of the metal mask substrate 10 is included in the second surface layer 10B2, a part of the second surface layer 10B2 is etched.

[0074] As Figure 6 shown, when the etching solution ES is supplied to the second surface layer 10B2, the concentration of chloride ions becomes high only in a part of the second surface layer 10B2. As a result, the passive second surface layer 10B2 is locally damaged by chloride ions, and thus pitting corrosion occurs in a part of the metal mask substrate 10. In the main layer 10A, the part exposed from the second surface layer 10B2 functions as an anode, and the second surface layer 10B2 functions as a cathode. As a result, the following reactions occur.

[0075] (Anodic reaction) Fe → Fe 2+ + 2e -

[0076] (Hydrolysis reaction) Fe 2+ + 2H2O → Fe(OH)2 + 2H +

[0077] (Cathodic reaction) O2 + 2H2O + 4e - → 4OH -

[0078] That is, the iron ions dissolved in the anode undergo a hydrolysis reaction, and thus the part where pitting corrosion occurs is acidified to inhibit passivation, and thus etching further proceeds in the part where pitting corrosion occurs.

[0079] Therefore, as Figure 7 shown, compared with the case where the entire part exposed from the second through-hole RP2A is etched, the part of the main layer 10A exposed from the second surface layer 10B2 is etched at a higher rate. As a result, the sizes of a part of the plurality of through-holes become larger.

[0080] At this point, with respect to the substrate 10 for a metal mask, the substrate 10 for a metal mask contains 0.25% by mass or more of manganese, the standard electrode potential of which is lower than those of iron and nickel elements. Therefore, the substrate 10 for a metal mask is in a state where it is easily corroded, and thus the corrosion potential generated when the etching solution ES comes into contact with the main layer 10A of the substrate 10 for a metal mask becomes lower. As a result, it is difficult for the corrosion potential of the substrate 10 for a metal mask to exceed the pitting potential, and thus it is difficult to generate pitting when the substrate 10 for a metal mask comes into contact with the etching solution ES. Note that the fact that the corrosion potential of the substrate 10 for a metal mask is difficult to exceed the pitting potential means that the corrosion potential can be below the pitting potential, and even if the corrosion potential exceeds the pitting potential, the potential difference is likely to become small. As a result, it is possible to suppress the local excessive wet etching on the substrate 10 for a metal mask, and thus it is possible to suppress a part of the through holes among the plurality of through holes from becoming large.

[0081] By making the content rate of the manganese element fall within the range of 0.40% by mass or less, segregation of the manganese element within the substrate 10 for a metal mask can be suppressed, and thus it is also possible to suppress deviation in etching within the substrate 10 for a metal mask due to segregation of the manganese element.

[0082] In addition, with respect to the substrate 10 for a metal mask, the substrate 10 for a metal mask contains 0.03% by mass or more and 0.05% by mass or less of silicon element. Therefore, it is possible to suppress galvanic corrosion caused by the difference in electrochemical potential between the silicon element and the metal element located near the silicon element, and thereby further suppress a part of the through holes from becoming large.

[0083] In addition, with respect to the substrate 10 for a metal mask, since the content rates of the iron element, the nickel element, and the additive element respectively satisfy the above ranges, the effectiveness of the content rate of the manganese element being 0.25% by mass or more and 0.40% by mass or less is improved.

[0084] [Metal Mask]

[0085] Refer to Figures 8 to 10 , and the metal mask will be described.

[0086] Figure 8 The metal mask 20 shown is formed of a substrate 10 for a metal mask mainly composed of an iron-nickel alloy. The metal mask 20 contains 0.25% by mass or more and 0.40% by mass or less of manganese element. The maximum value of the thickness of the metal mask 20 is 50 μm or less. The metal mask 20 includes a back surface 20R and a plurality of through holes 20H having openings in the back surface 20R. The back surface 20R is an example of the first surface. The area of the opening is 1600 μm 2 or less. As described above, from the viewpoint of being able to form a higher-resolution pixel, the area of the opening is preferably 900 μm 2 or less.

[0087] According to the metal mask 20 of the present disclosure, the substrate 10 for the metal mask contains 0.25% by mass or more of manganese, the standard electrode potential of which is lower than that of iron and nickel elements. Therefore, the substrate 10 for the metal mask is liable to corrosion, and thus pitting is difficult to occur when the substrate 10 for the metal mask comes into contact with the etching solution ES. As a result, even when through holes 20H having openings with a miniaturization of 1600 μm 2 or less are formed, wet etching in a local area of the substrate 10 for the metal mask can be suppressed, and thus an increase in the size of a part of the through holes 20H among the plurality of through holes 20H is suppressed.

[0088] The metal mask 20 has a back surface 20R and a surface 20F on the side opposite to the back surface 20R. When the metal mask 20 is a metal mask for evaporation, when forming an evaporation pattern using the metal mask 20, the back surface 20R faces the evaporation target, and the surface 20F faces the evaporation source. The metal mask 20 is used to form pixels included in an organic EL display device.

[0089] The metal mask 20 has a mask portion 20A and a peripheral portion 20B surrounding the mask portion 20A. In Figure 8 the example shown, the metal mask 20 has a plurality of mask portions 20A. A plurality of through holes 20H are formed in each mask portion 20A. Each through hole 20H penetrates the metal mask 20 in the thickness direction of the metal mask 20. When the metal mask 20 is a metal mask for evaporation, each through hole 20H is a passage for the evaporation material. By allowing the evaporation material to pass through the through holes 20H, an evaporation pattern having a predetermined shape is formed on the evaporation target. The peripheral portion 20B does not have through holes 20H. Among the metal mask 20, the peripheral portion 20B has the maximum value of the thickness. It should be noted that the mask portion 20A may or may not have the maximum value of the thickness.

[0090] The metal mask 20 may include an oxide layer containing an oxide of an iron-nickel alloy. The oxide layer includes the back surface 20R of the metal mask 20. That is, the oxide layer corresponds to the second surface layer 10B2 of the above-described substrate 10 for the metal mask. According to the metal mask 20, since the metal mask 20 includes the oxide layer, pitting is liable to occur in the substrate 10 for the metal mask used to form the metal mask 20 when forming the through holes 20H included in the metal mask 20. Therefore, the effectiveness of the content rate of manganese, the standard electrode potential of which is lower than that of iron and nickel, being 0.25% by mass or more and 0.40% by mass or less in the substrate 10 for the metal mask is improved.

[0091] Figure 9 The shape of the through holes 20H as viewed from a perspective opposite to the back surface 20R of the metal mask 20 is shown.

[0092] AsFigure 9 As shown, the second opening 20H2 of the through hole 20H may have a square shape, for example. In Figure 9 the example shown, the second opening 20H2 has a square shape with rounded corners. The center of curvature of each corner is located within the second opening 20H2. In each second opening 20H2, the length L of one side is, for example, 40 μm or less, so the area of the second opening 20H2 is 1600 μm 2 or less. It should be noted that the shape of the second opening 20H2 is not limited to a square, and may be a quadrilateral other than a square, or may have a circular shape.

[0093] In the back surface 20R, a plurality of second openings 20H2 are arranged according to a predetermined rule. In Figure 9 the example shown, the plurality of second openings 20H2 are arranged in a grid pattern. The plurality of second openings 20H2 may also be arranged in a staggered pattern, for example.

[0094] Figure 10 and Figure 11 show a cross-sectional structure of the metal mask 20 along a plane orthogonal to the surface 20F of the metal mask 20. Figure 10 shows a cross-sectional structure of a first example of the metal mask 20. On the other hand, Figure 11 shows a cross-sectional structure of a second example of the metal mask 20. It should be noted that Figure 10 shows a cross-sectional structure of the metal mask 20 when the metal mask substrate 10 is etched only from the surface 10F. In contrast, Figure 11 shows a cross-sectional structure of the metal mask 20 when the metal mask substrate 10 is etched from both the surface 10F and the back surface 10R.

[0095] As Figure 10 shown, in the first example of the metal mask 20, the first opening 20H1 of the through hole 20H is located on the surface 20F, and the second opening 20H2 is located on the back surface 20R. The through hole 20H has a shape that gradually narrows from the surface 20F toward the back surface 20R. That is, in a plane orthogonal to the thickness direction, the area of the through hole 20H monotonically decreases from the surface 20F toward the back surface 20R. The through hole 20H has a substantially arc shape.

[0096] As Figure 11 shown, in the second example of the metal mask 20, the first opening 20H1 of the through hole 20H is located on the surface 20F, and the second opening 20H2 is located on the back surface 20R. The through hole 20H has a large hole portion 20HL and a small hole portion 20HS. The large hole portion 20HL has a shape that gradually narrows along the direction from the surface 20F toward the back surface 20R, and the small hole portion 20HS has a shape that gradually narrows along the direction from the back surface 20R toward the surface 20F.

[0097] That is, in a plane orthogonal to the thickness direction, the area of the large-hole portion 20HL monotonically decreases in the direction from the front surface 20F to the back surface 20R, and the area of the small-hole portion 20HS monotonically decreases in the direction from the back surface 20R to the front surface 20F. Therefore, in a plane orthogonal to the thickness direction, the area of the through-hole 20H is the smallest at the connection portion between the large-hole portion 20HL and the small-hole portion 20HS.

[0098] According to the metal mask substrate 10 using the present disclosure, in both the first example and the second example, an increase in the size of a part of the plurality of through-holes 20H can be suppressed.

[0099] [Method for manufacturing a metal mask]

[0100] Refer to Figures 12 to 17 , and a method for manufacturing a metal mask will be described.

[0101] The method for manufacturing the metal mask 20 of the present disclosure includes: forming a plurality of through-holes in the metal mask substrate 10. At this time, a plurality of through-holes are formed in the metal mask substrate 10 by wet etching. The metal mask substrate 10 is mainly composed of a Fe-Ni alloy containing 0.25 mass% or more and 0.40 mass% or less of manganese element, has a thickness of 50 μm or less, and has a first surface. In addition, forming a plurality of through-holes is to form the following through-holes: having an opening on the first surface and the area of the opening being 1600 μm 2 or less.

[0102] The metal mask substrate 10 contains 0.25 mass% or more of manganese element whose standard electrode potential is lower than that of iron element and nickel element. Therefore, the metal mask substrate 10 is easily corroded. As a result, when the metal mask substrate 10 is in contact with the etching solution, pitting is difficult to occur. As a result, even when forming through-holes having a refined opening of 1600 μm 2 or less, local excessive wet etching of the metal mask substrate 10 can be suppressed, and thus an increase in a part of the plurality of through-holes can be suppressed.

[0103] Hereinafter, a method for manufacturing the metal mask 20 will be described in detail with reference to the drawings. It should be noted that in Figures 12 to 17 , for the convenience of illustration, the process of forming one through-hole is illustrated.

[0104] As Figure 12As shown, the substrate 10 for a metal mask has a surface 10F and a back surface 10R on the side opposite to the surface 10F. The first resist layer R1 is located on the surface 10F. The first resist layer R1 is formed of a negative resist. The second resist layer R2 is located on the back surface 10R. The second resist layer R2 is formed of a negative resist. It should be noted that each of the resist layers R1 and R2 may also be formed of a positive resist.

[0105] As Figure 13 shown, after the first resist layer R1 and the second resist layer R2 are exposed, the first resist layer R1 and the second resist layer R2 are developed. Thereby, a first resist pattern RP1 is formed from the first resist layer R1, and a second resist pattern RP2 is formed from the second resist layer R2. In the development of each of the resist layers R1 and R2, a developer such as an aqueous sodium carbonate solution is used, for example. The first resist pattern RP1 has a first through hole RP1A. The first through hole RP1A penetrates the first resist pattern RP1 along the thickness direction of the first resist pattern RP1. The second resist pattern RP2 has a second through hole RP2A. The second through hole RP2A penetrates the second resist pattern RP2 along the thickness direction of the second resist pattern RP2. From the perspective of the plane opposite to the plane in which the first resist pattern RP1 extends, the second through hole RP2A is located within the first through hole RP1A.

[0106] As Figure 14 shown, a first protective layer PL1 is formed on the surface of the first resist pattern RP1. By forming the first protective layer PL1, the first through hole RP1A is blocked, thereby preventing the etching solution from reaching the substrate 10 for a metal mask via the first through hole RP1A. Next, the substrate 10 for a metal mask is etched from the back surface 10R using the second resist pattern RP2. The etching of the substrate 10 for a metal mask uses an etching solution containing chloride ions, for example. Thereby, a small hole portion 10HS that opens on the back surface 10R is formed.

[0107] At this time, for example, the substrate 10 for a metal mask can be wet-etched using a ferric chloride solution having a Baumé degree of 47° or more and 52° or less. In the method for manufacturing the substrate 10 for a metal mask of the present disclosure, even when a ferric chloride solution containing chloride ions that causes pitting is used as the etching solution, pitting can be suppressed when through holes are formed in the substrate 10 for a metal mask.

[0108] From the viewpoint of improving the thickness freedom of the resist patterns RP1 and RP2, the contact angles of the resist patterns RP1 and RP2 are preferably 40° or less, more preferably 30° or less. By making the contact angle 40° or less, the etching solution easily penetrates into the through holes RP1A and RP2A of the resist patterns RP1 and RP2. It should be noted that the contact angle in the present disclosure is the angle measured by the θ / 2 method. The θ / 2 method is a method for measuring the contact angle according to "6. Static Drop Method" in JIS R 3257:1999 "Test Method for Wettability of Substrate Glass Surfaces".

[0109] The thickness of the resist patterns RP1 and RP2 can be 10 μm or less, preferably 7 μm or less, and more preferably 5 μm or less. The thinner the thickness of the resist patterns RP1 and RP2, the easier it is for the etching solution to penetrate into the through holes RP1A and RP2A of the resist patterns RP1 and RP2.

[0110] As Figure 15 shown, the first protective layer PL1 is removed from the first resist pattern RP1. In addition, the second resist pattern RP2 is removed from the back surface 10R of the metal mask substrate 10. Then, the back surface 10R of the metal mask substrate 10 is covered with the second protective layer PL2. At this time, the second protective layer PL2 is formed on the back surface 10R in such a manner that a part of the second protective layer PL2 is buried in the small hole portion 10HS.

[0111] As Figure 16 shown, the metal mask substrate 10 is etched from the surface 10F using the first resist pattern RP1. In the etching of the metal mask substrate 10, similar to the formation of the small hole portion 10HS, for example, an etching solution containing chloride ions is used. The etching solution containing chloride ions can be, for example, a ferric chloride solution with a Baume degree of 47° or more and 52° or less. When forming the large hole portion 10HL, the same effect as when forming the small hole portion 10HS can also be obtained.

[0112] Thereby, a large hole portion 10HL that opens on the surface 10F is formed. The large hole portion 10HL is formed so as to reach a part of the second protective layer PL2 filled in the small hole portion 10HS, whereby the large hole portion 10HL is connected to the small hole portion 10HS.

[0113] As Figure 17As shown, the first resist pattern RP1 is removed from the surface 10F of the substrate 10 for a metal mask, and the second protective layer PL2 is removed from the back surface 10R. Thus, a metal mask 20 having a through-hole 20H can be obtained. In the through-hole 20H, the large-hole portion 20HL corresponds to the large-hole portion 10HL formed in the substrate 10 for a metal mask, and the small-hole portion 20HS corresponds to the small-hole portion 10HS formed in the substrate 10 for a metal mask. In addition, the surface 20F of the metal mask 20 corresponds to the surface 10F of the substrate 10 for a metal mask, and the back surface 20R of the metal mask 20 corresponds to the back surface 10R of the substrate 10 for a metal mask.

[0114] It should be noted that when forming the second protective layer PL2 on the back surface 10R of the substrate 10 for a metal mask, the second resist pattern RP2 may not be removed from the back surface 10R of the substrate 10 for a metal mask. In this case, the second protective layer PL2 is formed on the second resist pattern RP2. It should be noted that the second protective layer PL2 is formed in the following manner: a part of the second protective layer PL2 is filled in the small-hole portion 10HS and in the second through-hole RP2A of the second resist pattern RP2. After the large-hole portion 10HL is formed in the substrate 10 for a metal mask, the second resist pattern RP2 and the second protective layer PL2 are removed from the substrate 10 for a metal mask.

[0115] [Example]

[0116] Refer to Figures 18 to 28 , the examples and comparative examples will be described.

[0117] [Example 1]

[0118] By rolling an ingot of an iron-nickel alloy added with additive elements, a metal plate was formed, wherein the additive elements include magnesium element, aluminum element, silicon element, chromium element, manganese element, molybdenum element and cobalt element. Then, after annealing the metal plate, the metal plate was cut in such a way as to obtain a metal plate having a desired length in the width direction of the metal plate. Thus, a substrate 10 for a metal mask of Example 1 with a thickness of 25 μm was obtained.

[0119] [Examples 2 to 6, and Comparative Examples 1 to 7]

[0120] Among the additive elements, the addition amount of manganese element was reduced, and the addition amount of one or more elements other than manganese element in the additive elements was reduced or increased. Except for this, substrates 10 for metal masks of Examples 2 to 6 and Comparative Examples 1 to 7 were obtained by the same method as in Example 1.

[0121] [Evaluation Method]

[0122] [Composition Analysis]

[0123] The composition analysis of the substrates for metal masks of each example and each comparative example was performed by X-ray fluorescence analysis (XRF) using a fluorescent X-ray composition analyzer (ZSX Primus IV, Rigaku Corporation).

[0124] [Incidence of recess expansion]

[0125] A dry film resist with a thickness of 10 μm was pasted on the surface of the substrates for metal masks of each example and each comparative example. Then, using photolithography, a plurality of openings each having a square shape with a side length of 25 μm were formed in the dry film resist, thereby obtaining a resist pattern. It should be noted that the area of the opening formed in the substrate for the metal mask was increased by about 10% relative to the area of the opening formed in the dry film resist. In addition, a dry film resist with a contact angle of 77° with respect to the ferric chloride solution was used. In the resist pattern, the distance between the openings in the first direction was set to 25 μm, and the pitch of the openings in the second direction orthogonal to the first direction was set to 25 μm.

[0126] Next, the substrate for the metal mask having the resist pattern formed thereon was wet-etched using a ferric chloride solution so that the depth of the recess formed by the etching was 8 μm. At this time, the substrate for the metal mask was wet-etched under the following two conditions.

[0127] [Condition 1]

[0128] Specific gravity: 47° Baumé

[0129] Temperature: 50 °C

[0130] [Condition 2]

[0131] Specific gravity: 50° Baumé

[0132] Temperature: 50 °C

[0133] The surface of each substrate for a metal mask was photographed using a laser microscope (VK-X3000, manufactured by Keyence Corporation). Based on the images of each substrate for a metal mask, the area of the openings located on the surface was calculated for 1000 recesses through image analysis. The first average value of the total opening area was calculated, and the recesses with an area smaller than the first average value by more than 30% were excluded. The sum of the areas from the opening with the smallest area to the opening with the 10th smallest area was calculated. Then, based on this sum, the second average value, which is the average value of the areas of each opening, was calculated. Subsequently, the calculated second average value was set as the normal value of the opening area. The recesses among the 1000 openings that had an opening with an area more than 1.1 times the normal value were set as the expanded recesses. The percentage of the expanded recesses relative to the total number of recesses was calculated, and this percentage was set as the incidence of recess expansion.

[0134] [Relationship between etching depth and recess expansion]

[0135] Six test pieces were fabricated, which had a resist pattern formed on the substrate for a metal mask in Comparative Example 6 by the same method as the evaluation method for the incidence of recess expansion described above. Then, based on this, the test pieces were wet-etched according to the above Condition 1 so that each test piece had recesses with different depths. That is, the etching time of the first test piece was set to the length for forming recesses with a depth of 0.9 μm, the etching time of the second test piece was set to the length for forming recesses with a depth of 1.8 μm. Additionally, the etching time of the third test piece was set to the length for forming recesses with a depth of 3.4 μm, the etching time of the fourth test piece was set to the length for forming recesses with a depth of 5.4 μm. Additionally, the etching time of the fifth test piece was set to the length for forming recesses with a depth of 8.0 μm. Additionally, the etching time of the sixth test piece was set to the length for forming recesses with a depth of 15.0 μm.

[0136] The incidence of recess expansion of the first to fourth test pieces was calculated by the following method. That is, the average value of the areas of the openings of all the recesses and the average value of the depths of all the recesses were calculated. Then, the recesses with a size of 50% or less relative to the average value of the area or a depth of 2 times or more relative to the average value of the depth were counted as the recesses in which recess expansion occurred. Then, the percentage of the counted recesses relative to 1000 was calculated. Additionally, the incidence of recess expansion of the fifth test piece was calculated by the same method as the evaluation method for the incidence of recess expansion described above.

[0137] [Relationship between contact angle and thickness of resist pattern and recess expansion]

[0138] Six test pieces were fabricated, each having a resist pattern formed on the substrate for a metal mask in Comparative Example 7 by the same method as the evaluation method for the incidence of recess expansion described above. At this time, different dry film resists were used for each test piece, and thus the contact angle of the resist pattern with respect to the ferric chloride solution was changed as follows for each test piece. That is, the contact angle was set to 22° for the first test piece, 30° for the second test piece, 39° for the third test piece. In addition, the contact angle was set to 51° for the fourth test piece, 63° for the fifth test piece, and 77° for the sixth test piece.

[0139] In the resist pattern, while maintaining the pitch of the openings in the same state as when the length of one side of the opening was 25 μm, the length of one side of the opening was changed to 20 μm. Other than that, six test pieces with different contact angles of the resist pattern were fabricated by the same method as the above method. In addition, in the resist pattern, while maintaining the pitch of the openings in the same state as when the length of one side of the opening was 25 μm, the length of one side of the opening was changed to 30 μm. Other than that, six test pieces with different contact angles of the resist pattern were fabricated by the same method as the above method.

[0140] In addition, by changing the thickness of the dry film resist to 5 μm, six test pieces with a length of one side of the opening of 20 μm, six test pieces with a length of one side of the opening of 25 μm, and six test pieces with a length of one side of the opening of 30 μm were fabricated. At this time, among the six test pieces with the same opening size, the contact angle of the first test piece was set to 28°, the contact angle of the second test piece was set to 31°, and the contact angle of the third test piece was set to 39°. In addition, the contact angle of the fourth test piece was set to 50°, the contact angle of the fifth test piece was set to 60°, and the contact angle of the sixth test piece was set to 78°.

[0141] Then, by the same method as the evaluation method for the incidence of recess expansion described above, the incidence of recess expansion of each test piece was calculated. It should be noted that only Condition 1 was used for the wet etching conditions.

[0142] [Evaluation Results]

[0143] The evaluation results of the composition analysis and the evaluation results of the incidence of recess expansion of the substrates for metal masks in each example and each comparative example are as Figure 18 shown.

[0144] As Figure 18As shown, it can be seen that in Examples 1 to 6, the content rate of iron element is included in the range of 63.412% by mass or more and 64.306% by mass or less, and the content rate of nickel element is included in the range of 35.374% by mass or more and 36.188% by mass or less.

[0145] It can be seen that in Examples 1 to 6, the content rate of manganese element is included in the range of 0.247% by mass or more and 0.354% by mass or less, and the content rate of silicon element is included in the range of 0.026% by mass or more and 0.047% by mass or less. In addition, it can be seen that in Examples 1 to 6, the content rate of magnesium element is included in the range of 0.000% by mass or more and 0.007% by mass or less, and the content rate of aluminum element is included in the range of 0.003% by mass or more and 0.029% by mass or less. In addition, it can be seen that in Examples 1 to 6, the content rate of chromium element is included in the range of 0.004% by mass or more and 0.046% by mass or less, and the content rate of molybdenum element is included in the range of 0.000% by mass or more and 0.010% by mass or less. In addition, it can be seen that in Examples 1 to 6, the content rate of cobalt element is included in the range of 0.000% by mass or more and 0.265% by mass or less.

[0146] It can be seen that in Comparative Examples 1 to 7, the content rate of iron element is included in the range of 64.096% by mass or more and 64.437% by mass or less, and the content rate of nickel element is included in the range of 35.210% by mass or more and 35.563% by mass or less.

[0147] It can be seen that in Comparative Examples 1 to 7, the content rate of manganese element is included in the range of 0.216% by mass or more and 0.243% by mass or less, and the content rate of silicon element is included in the range of 0.035% by mass or more and 0.060% by mass or less. In addition, it can be seen that in Comparative Examples 1 to 7, the content rate of magnesium element is included in the range of 0.000% by mass or more and 0.003% by mass or less, and the content rate of aluminum element is included in the range of 0.004% by mass or more and 0.005% by mass or less. In addition, it can be seen that in Comparative Examples 1 to 6, the content rate of chromium element is included in the range of 0.033% by mass or more and 0.040% by mass or less, and the content rate of molybdenum element is included in the range of 0.017% by mass or more and 0.035% by mass or less. It can be seen that in Comparative Examples 1 to 7, the content rate of cobalt element is 0.000% by mass.

[0148] It can be seen that in Examples 1 to 6, the incidence of recess expansion in the etching based on Condition 1 is within the range of 0.0% or more and 5.9% or less. In contrast, it can be seen that in Comparative Examples 1 to 7, the incidence of recess expansion in the etching based on Condition 1 is within the range of 12.2% or more and 84.4% or less.

[0149] Thus, it can be seen that when the content rate of manganese element is within the range of 0.247 mass% or more and 0.354 mass% or less, the incidence of recess expansion in the etching based on Condition 1 is suppressed to less than 10%. In contrast, it can be seen that when the content rate of manganese element is 0.243 mass% or less, the incidence of recess expansion in the etching based on Condition 1 exceeds 12%.

[0150] That is, from the viewpoint of suppressing the incidence of recess expansion in the etching based on Condition 1, it is considered that the content rate of manganese element preferably falls within the range of 0.247 mass% or more and 0.354 mass% or less. Further, from the viewpoint of suppressing the incidence of recess expansion, it is considered that the content rate of manganese element is more preferably within the range of 0.255 mass% or more and 0.354 mass% or less, and the content rate of manganese element is further preferably within the range of 0.306 mass% or more and 0.354 mass% or less.

[0151] In addition, from the viewpoint of suppressing the incidence of recess expansion in the etching based on Condition 1, it is considered that the content rate of silicon element preferably falls within the range of 0.026 mass% or more and 0.047 mass% or less.

[0152] It can be seen that in Examples 1 to 6, the incidence of recess expansion in the etching based on Condition 2 is within the range of 0.0% or more and 0.9% or less. In contrast, it can be seen that in Comparative Examples 1 to 7, the incidence of recess expansion in the etching based on Condition 2 is within the range of 4.3% or more and 32.2% or less.

[0153] That is, from the viewpoint of suppressing the incidence of recess expansion in the etching based on Condition 2, it is considered that the content rate of manganese element preferably falls within the range of 0.247 mass% or more and 0.354 mass% or less. Further, from the viewpoint of suppressing the incidence of recess expansion, it is considered that the content rate of manganese element is more preferably within the range of 0.259 mass% or more and 0.354 mass% or less.

[0154] In addition, from the viewpoint of suppressing the incidence of recess expansion in the etching based on Condition 2, it is considered that the content rate of silicon element preferably falls within the range of 0.026 mass% or more and 0.047 mass% or less.

[0155] Figure 19It is a graph showing the relationship between the content rate of manganese element in etching based on Condition 1 and the incidence of recess expansion. Figure 20 It is a graph showing the relationship between the content rate of manganese element in etching based on Condition 2 and the incidence of recess expansion.

[0156] As Figure 19 shown, it can be seen that when the content rate of manganese element is less than 0.247 mass%, the incidence of recess expansion increases sharply in the etching of Condition 1. In addition, as Figure 20 shown, it can be seen that when the content rate of manganese element is less than 0.247 mass%, the incidence of recess expansion increases sharply in the etching of Condition 2.

[0157] Figure 21 and Figure 22 are graphs obtained by performing multiple regression analysis on the relationship between the content rate of each additive element based on Condition 1 and the incidence of recess expansion. Figure 21 It is a graph showing the relationship between the content rate of manganese element and the incidence of recess expansion. Figure 22 It is a graph showing the relationship between the content rate of manganese element and the content rate of silicon and the incidence of recess expansion. It should be noted that for Example 1, in order to facilitate regression analysis, the incidence of recess expansion was set to 0.05%.

[0158] Figure 21 The straight line shown represents the following prediction formula 1 obtained by multiple regression analysis.

[0159] Exp(11.18 - 5396.80×Mn)

[0160] In addition, Figure 21 The graph (plot) shown is a graph obtained by substituting the content rate (mass%) of manganese element in Examples 1 to 6 and Comparative Examples 1 to 7 as measured values into Mn in Prediction Formula 1. The coefficient of determination (R 2 ) of Prediction Formula 1 is 0.878. Therefore, it can be considered that the content rate of manganese element in the substrate for metal mask contributes to the incidence of recess expansion.

[0161] Figure 22 The straight line shown represents the following prediction formula 2 obtained by multiple regression analysis.

[0162] Exp(5.98 + 6914.03×Si - 4532.98×Mn)

[0163] In addition, Figure 22The chart shown is obtained by substituting the Mn content (mass %) of Examples 1 to 6 and Comparative Examples 1 to 7, which are measured values, into Mn in Prediction Formula 2, and substituting the Si content (mass %) of Examples 1 to 6 and Comparative Examples 1 to 7, which are measured values, into Si. The coefficient of determination (R 2 ) of Prediction Formula 2 is 0.982. Therefore, it can be considered that the Si content in the substrate for the metal mask, together with the Mn content, contributes to the incidence of recess expansion.

[0164] The depth of the recess and the incidence of recess expansion are as Figure 23 shown.

[0165] As Figure 23 shown, it can be seen that the incidence is 53% when the depth of the recess is 0.9 μm, 56% when the depth is 1.8 μm, and 49% when the depth is 3.4 μm. It can be seen that the incidence is 49% when the depth of the recess is 5.4 μm and 50% when the depth is 8.0 μm. Thus, it can be seen that the expansion of the recess occurs approximately before the depth of the recess reaches 0.9 μm, and the incidence of recess expansion is maintained before the depth of the recess reaches 8.0 μm.

[0166] Figure 24 and Figure 25 are SEM images obtained by photographing the recesses formed on the surface of the first test piece. Figure 24 is an SEM image obtained by photographing the recesses having a substantially uniform depth of 0.9 μm. In contrast, Figure 25 is an SEM image obtained by photographing the recesses formed by over-etching a part of the portion exposed from the through-holes of the resist pattern.

[0167] As Figure 24 shown, it can be seen that among the multiple recesses 30R opened on the surface 30F of the first test piece, some of the recesses 30R have a substantially uniform depth. In addition, it can be seen that the depth of the recesses 30R is approximately 0.9 μm. In contrast, as Figure 25 shown, it can be seen that among the multiple recesses 30R, some of the recesses 30R are formed only in a part of the design pattern 30D of the recesses 30R. Specifically, it can be seen that the recesses 30R are formed in such a way as to include only one corner of the design pattern 30D having a substantially square shape.

[0168] Based on such results, it can be considered that the recess expansion is caused by excessive etching that occurs locally in the initial stage of wet etching. In addition, since the local and excessive etching occurs in the initial stage of wet etching, it is considered that such etching is caused by pitting that occurs when the etching solution breaks through the oxide layer on the surface of the substrate for the metal mask and comes into contact with the main layer.

[0169] Figure 26 This is an SEM image obtained by photographing the recess formed on the surface of the 6th test piece. Figure 26 This shows an example of a recess for calculating the above normal value and an example of a recess having an opening ratio more than 1.1 times the normal value.

[0170] As Figure 26 shown, it can be seen that in the part where local wet etching does not occur, a recess 30R is formed with a uniform depth over substantially the entire recess 30R and a depth of about 15.0 μm. In contrast, in the part where local etching occurs, as a result of excessive etching, a recess 30R is formed in which the area of the opening is expanded relative to the recess 30R having the normal value, and the recess 30R penetrates the substrate for the metal mask.

[0171] Figure 27 This is a graph showing the relationship between the contact angle and the incidence of recess expansion when the thickness of the resist pattern is 10 μm. Figure 28 This is a graph showing the relationship between the contact angle and the incidence of recess expansion when the thickness of the resist pattern is 5 μm. It should be noted that Figure 27 and Figure 28 in both cases, the graph when the length of one side of the opening is 20 μm is "○", the graph when the length of one side of the opening is 25 μm is "×", and the graph when the length of one side of the opening is 30 μm is "□".

[0172] As Figure 27 shown, it can be seen that when the contact angle of the resist pattern is the same, the smaller the area of the opening, the higher the incidence of recess expansion. In addition, it can be seen that when the length of one side of the opening is 20 μm, recess expansion does not occur when the contact angle is 30° or less. In addition, it can be seen that when the length of one side of the opening is 25 μm or more, recess expansion does not occur when the contact angle is 39° or less.

[0173] As Figure 28 shown, it can be seen that compared with Figure 27Compared with the results shown, when the area of the opening is the same, regardless of the value of the contact angle, the incidence of recess expansion is low. In addition, it can be seen that when the contact angle of the resist pattern is the same, the smaller the area of the opening, the higher the incidence of recess expansion. It can be seen that when the length of one side of the opening is 20 μm, recess expansion does not occur when the contact angle is 39° or less. In addition, it can be seen that when the length of one side of the opening is 25 μm, recess expansion does not occur when the contact angle is 50° or less. It can be seen that when the length of one side of the opening is 30 μm, recess expansion does not occur when the contact angle is 60° or less.

[0174] In addition, it can be seen that regardless of the thickness of the resist pattern, as long as the contact angle is 39° or less, the incidence of recess expansion is less than 20%. Furthermore, it can be seen that regardless of the area of the opening, as long as the contact angle is 30° or less, recess expansion does not occur. Based on such results, it is considered that the contact angle of the resist pattern is preferably 39° or less, more preferably 30° or less.

[0175] As described above, according to the substrate for a metal mask, the metal mask, and the method for manufacturing the metal mask, the effects described below can be obtained.

[0176] (1) The substrate 10 for a metal mask contains 0.25 mass% or more of manganese element whose standard electrode potential is lower than that of iron element and nickel element. Therefore, the substrate 10 for a metal mask is in a state where it is easily corroded. Thus, the corrosion potential generated when the etching solution ES contacts the substrate 10 for a metal mask becomes lower. As a result, it is difficult to generate pitting when the substrate 10 for a metal mask contacts the etching solution ES. As a result, local over-etching of the substrate 10 for a metal mask is suppressed, and thus an increase in the size of a part of the plurality of through-holes 20H is suppressed.

[0177] (2) Since the substrate 10 for a metal mask contains 0.03 mass% or more and 0.05 mass% or less of silicon element, galvanic corrosion between the metal elements located near the silicon element can be suppressed, thereby further suppressing an increase in the size of a part of the through-holes 20H.

[0178] (3) Since the content rates of iron element, nickel element, and additive element respectively satisfy the above ranges, the effectiveness of the manganese element content rate being 0.25 mass% or more and 0.40 mass% or less is improved.

[0179] (4) The substrate 10 for the metal mask contains 0.25 mass% or more of manganese element whose standard electrode potential is lower than that of iron element and nickel element. Therefore, the substrate 10 for the metal mask is in a state of being easily corroded. As a result, the corrosion potential generated when the etching solution ES contacts the substrate 10 for the metal mask becomes lower. Thus, it is difficult to generate pitting corrosion when the substrate 10 for the metal mask contacts the etching solution ES. As a result, even when forming the through hole 20H having a micro-refined opening of 1600 μm 2 or less, it is possible to suppress the excessive wet etching locally on the substrate 10 for the metal mask. Therefore, it is possible to suppress a part of the through holes 20H among the plurality of through holes 20H from becoming larger.

[0180] (5) Since the metal mask 20 includes an oxide layer, pitting corrosion is likely to occur in the substrate 10 for the metal mask when forming the through hole 20H included in the metal mask 20. Therefore, in the substrate 10 for the metal mask, the effectiveness of the manganese element having a standard electrode potential lower than that of iron and nickel being contained at 0.25 mass% or more and 0.40 mass% or less is improved.

[0181] (6) Even when using a ferric chloride solution containing chloride ions that generates pitting corrosion as the etching solution ES, it is possible to suppress the generation of pitting corrosion when forming the through hole in the substrate 10 for the metal mask.

[0182] (7) When the contact angles of the resist patterns RP1 and RP2 with respect to the etching solution ES are 40° or less, the degree of freedom in the thickness of the resist patterns RP1 and RP2 can be increased.

[0183] It should be noted that the above-described embodiments can be implemented with the following modifications.

[0184] [Metal Mask]

[0185] · The metal mask 20 formed using the substrate 10 for the metal mask is not limited to the metal mask used in the evaporation method, and may also be a metal mask used in the sputtering method, the CVD method, the ion plating method, and the screen printing method.

[0186] Description of Symbols

[0187] 10... Substrate for metal mask

[0188] 10F... Surface

[0189] 10R... Back surface

[0190] 10A... Main layer

[0191] 10B1... First surface layer

[0192] 10B2... Second surface layer

[0193] 20... Metal mask

[0194] 20F… surface

[0195] 20H… through hole

[0196] 20R… back surface

Claims

1. A substrate for a metal mask, which is a substrate for a metal mask mainly composed of an iron-nickel alloy, contains 0.25% by mass or more and 0.40% by mass or less of manganese element, and has a thickness of 50 μm or less.

2. The substrate for a metal mask according to claim 1, wherein it contains 0.03% by mass or more and 0.05% by mass or less of silicon element.

3. The substrate for a metal mask according to claim 1, wherein it contains 63.5% by mass or more and 64.5% by mass or less of iron element, contains 35.0% by mass or more and 36.5% by mass or less of nickel element, contains 0.29% by mass or more and 0.7% by mass or less of additive elements, and the additive elements include the manganese element.

4. A metal mask, which is a metal mask formed from a substrate for a metal mask mainly composed of an iron-nickel alloy, contains 0.25% by mass or more and 0.40% by mass or less of manganese element, the maximum value of the thickness is 50 μm or less, and has: a first surface, and a plurality of through holes having openings on the first surface, The area of the opening is 1600 μm 2 or less.

5. The metal mask according to claim 4, which includes an oxide layer containing an oxide of the iron-nickel alloy, and the oxide layer includes the first surface.

6. A method for manufacturing a metal mask, including forming a plurality of through holes in a substrate for a metal mask by wet etching, the substrate for a metal mask contains 0.25% by mass or more and 0.40% by mass or less of manganese element, is mainly composed of an iron-nickel alloy, has a thickness of 50 μm or less, and has a first surface, Forming the plurality of through-holes means forming the through-holes described below: having an opening on the first surface, and the area of the opening being 1600 μm 2 or less.

7. The method for manufacturing a metal mask according to claim 6, wherein forming the plurality of through holes includes: forming the plurality of through holes by wet etching the substrate for a metal mask with a ferric chloride solution having a Baume degree of 47° or more and 52° or less.

8. The method for manufacturing a metal mask according to claim 6 or 7, wherein forming the plurality of through holes includes: forming a resist pattern on the first surface, and the contact angle of the resist pattern with respect to the etching solution is 40° or less.

Images