Patent Publication Number: US-2020299821-A1

Title: Vapor deposition mask, method for producing vapor deposition mask, and method for producing organic semiconductor element

Description:
TECHNICAL FIELD 
     The present invention relates to a vapor deposition mask and a method for producing the vapor deposition mask, and specifically to a vapor deposition mask having a structure in which a resin layer and a metal layer are stacked on each other, a method for producing such a vapor deposition mask, and a method for producing an organic semiconductor device using such a vapor deposition mask. 
     BACKGROUND ART 
     Recently, an organic EL (Electro-Luminescent) display device is a target of attention as a next-generation display device. In organic EL display devices currently mass-produced, an organic EL layer is formed by use of, mainly, a vacuum deposition method. 
     A common vapor deposition mask is a metal mask. However, it is becoming difficult to use a metal mask to form a vapor deposition pattern with high precision as organic EL display devices are becoming of a higher definition. A reason for this is that with the current metal processing technology, it is difficult to form, with high precision, small openings corresponding to a short pixel pitch (e.g., about 10 to about 20 μm) in a metal plate (thickness: e.g., about 100 μm) that is to be the metal mask. 
     In such a situation, a vapor deposition mask having a structure in which a resin layer and a metal layer are stacked on each other (hereinafter, referred to also as a “stack-type mask”) is proposed to be used for forming a high-definition vapor deposition pattern. 
     For example, Patent Document No. 1 discloses a vapor deposition mask having a structure in which a resin film and a holding member (thickness: 30 μm to 50 μm) formed of a metal magnetic material are stacked on each other. The resin film has a plurality of openings formed therein in correspondence with a desired vapor deposition pattern. The holding member has a plurality of openings formed therein larger than the openings of the resin film, so as to expose the openings of the resin film. Therefore, when the vapor deposition mask of Patent Document No. 1 is used, the vapor deposition pattern is formed in correspondence with the plurality of openings in the resin film. In a thin resin film that is thinner than a metal holding member for a common metal mask, even small openings may be formed with high precision. According to Patent Document No. 1, the holding member of the vapor deposition mask is formed of a metal magnetic material having a coefficient of thermal expansion less than 6 ppm/° C., for example, of invar. 
     A mask including a holding member formed of a metal magnetic material such as invar or the like is difficult to be formed to be large. For example, it is difficult to form such a mask having a side of a length exceeding 1 meter. A reason for this is that the cost for rolling performed to form a sheet of a metal magnetic material is raised. 
     In such a situation, Patent Document No. 2 discloses a vapor deposition mask including a magnetic layer containing magnetic powder, instead of a sheet of a metal magnetic material. The magnetic layer is formed as follows: a magnetic material-dispersed coating material containing soft magnetic material powder and additives such as a binder, a solvent, a dispersant and the like is applied to a base film and then is dried. Examples of the soft magnetic material powder may include powder of Fe, Ni, an Fe—Ni alloy, an Fe—Co alloy and an Fe—Ni—Co alloy. It is described that the soft magnetic material powder has a particle diameter of 3 μm or shorter, preferably 1 μm or shorter. As examples of the binder, siloxane polymer and polyimide are listed. The amount ratio between the soft magnetic material powder and the binder is not described. Openings in the vapor deposition mask are formed after the magnetic layer is formed on the base film. 
     CITATION LIST 
     Patent Literature 
     Patent Document No. 1: Japanese Laid-Open Patent Publication No. 2013-124372 
     Patent Document No. 2: Japanese Laid-Open Patent Publication No. 2014-201819 
     SUMMARY OF INVENTION 
     Technical Problem 
     However, it is difficult to stably produce a high-definition vapor deposition mask usable to produce a high-definition organic EL display device of, for example, 250 ppi or greater with the technology described in Patent Document No. 2. 
     The present invention made in light of the above-described situation has an object of providing a large stack-type vapor deposition mask preferably usable to form a high-definition vapor deposition pattern and a method for producing the same. Another object of the present invention is to provide a method for producing an organic semiconductor device by use of such a vapor deposition mask. 
     Solution to Problem 
     A vapor deposition mask in an embodiment according to the present invention includes a base film including a plurality of first openings and containing a polymer; a composite magnetic layer formed on the base film, the composite magnetic layer including a solid portion and a non-solid portion; and a frame joined to a peripheral portion of the base film. The plurality of first openings are formed in a region corresponding to the non-solid portion; and the composite magnetic layer contains soft ferrite powder having an average particle diameter shorter than 500 nm and a resin. 
     In an embodiment, the solid portion includes a plurality of island-like portions discretely located. 
     In an embodiment, the plurality of island-like portions include pairs of island-like portions located in point symmetry with respect to one arbitrary first opening among the plurality of first openings as a center. 
     In an embodiment, the soft ferrite powder has a coercive force of 100 A/m or less. 
     In an embodiment, the soft ferrite powder has a Curie temperature lower than 250° C. 
     In an embodiment, the soft ferrite powder in the composite magnetic layer has a volume fraction of 15% by volume or higher and 80% by volume or lower. 
     In an embodiment, the resin includes a thermosetting resin. 
     In an embodiment, the base film contains polyimide, and the resin contains the same type of polyimide as that contained in the base film. 
     In an embodiment, the frame is formed of a nonmagnetic material. The frame is formed of, for example, a polymer material. 
     A method for producing the vapor deposition mask in an embodiment according to the present invention is a method for producing the vapor deposition mask in any one of the above. The method includes step A of preparing a base film containing a polymer and a frame; step B of securing the base film to the frame; step C of forming a plurality of first openings in the base film; and step D of, after the step C, forming a composite magnetic layer, containing soft ferrite powder having an average particle diameter shorter than 500 nm and a resin, on the base film. The step B includes a step of, for example, bonding the base film to the frame with, for example, an adhesive. 
     In an embodiment, the step B includes a step of tensioning the base film. 
     In an embodiment, the method further includes a step of cleaning the base film between the step C and the step D. 
     In an embodiment, the step D is performed by an ink jet method. 
     A method for producing an organic semiconductor device according to the present invention includes a step of vapor-depositing an organic semiconductor material to a work by use of the vapor deposition mask in any one of the above. The organic semiconductor device is, for example, an organic EL device. 
     Advantageous Effects of Invention 
     An embodiment according to the present invention provides a large stack-type vapor deposition mask preferably usable to form a high-definition vapor deposition pattern and a method for producing the same. An embodiment according to the present invention provides a method for producing an organic semiconductor device by use of such a vapor deposition mask. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1( a )  is a plan view schematically showing a vapor deposition mask  100 A in an embodiment according to the present invention; and  FIG. 1( b )  is a cross-sectional view taken along line  1 B- 1 B′ in  FIG. 1( a ) . 
         FIG. 2  is a flowchart showing a method for producing a vapor deposition mask in an embodiment according to the present invention. 
         FIG. 3( a )  and  FIG. 3( b )  are respectively a plan view and a cross-sectional view showing an example of step of a method for producing the vapor deposition mask  100 A;  FIG. 3( b )  is a cross-sectional view taken along line  3 B- 3 B′ in  FIG. 3( a ) . 
         FIG. 4( a )  and  FIG. 4( b )  are respectively a plan view and a cross-sectional view showing an example of step of the method for producing the vapor deposition mask  100 A; 
         FIG. 4( b )  is a cross-sectional view taken along line  4 B- 4 B′ in  FIG. 4( a ) . 
         FIG. 5( a )  is a plan view schematically showing another vapor deposition mask  100 B in an embodiment according to the present invention; and  FIG. 5( b )  is a cross-sectional view taken along line  5 B- 5 B′ in  FIG. 5( a ) . 
         FIG. 6( a )  is a plan view schematically showing still another vapor deposition mask  100 C in an embodiment according to the present invention; and  FIG. 6( b )  is a cross-sectional view taken along line  6 B- 6 B′ in  FIG. 6( a ) . 
         FIG. 7( a )  is a plan view schematically showing still another vapor deposition mask  100 D in an embodiment according to the present invention; and  FIG. 7( b )  is a cross-sectional view taken along line  7 B- 7 B′ in  FIG. 7( a ) . 
         FIG. 8( a )  is a plan view schematically showing still another vapor deposition mask  100 E in an embodiment according to the present invention; and  FIG. 8( b )  is a cross-sectional view taken along line  8 B- 8 B′ in  FIG. 8( a ) . 
         FIG. 9( a )  and  FIG. 9( b )  are respectively plan views schematically showing still other vapor deposition masks  100 F and  100 G in embodiments according to the present invention. 
         FIG. 10( a )  and  FIG. 10( b )  are respectively plan views schematically showing still other vapor deposition masks  300 A and  300 B in embodiments according to the present invention. 
         FIG. 11( a )  and  FIG. 11( b )  are respectively plan views schematically showing still other vapor deposition masks  300 C and  300 D in embodiments according to the present invention. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     A vapor deposition mask in an embodiment according to the present invention includes a base film including a plurality of first openings defining a vapor deposition region and containing a polymer, a composite magnetic layer formed on the base film, and a frame joined to a peripheral portion of the base film. 
     The composite magnetic layer includes a solid portion and a non-solid portion. The solid portion is a portion where a composite magnetic body is actually present, and the non-solid portion is a portion where the composite magnetic body is not present and is a portion other than the solid portion. The plurality of first openings included in the base film are formed in a region corresponding to the non-solid portion of the composite magnetic layer. 
     The non-solid portion includes, for example, a plurality of second openings. The plurality of first openings included in the base film are each formed in a region corresponding to any one of the plurality of second openings. The plurality of first openings and the plurality of second openings may correspond to each other on a one-to-one basis. 
     The solid portion includes, for example, a plurality of island-like portions discretely located. It is preferred that the plurality of island-like portions include pairs of island-like portions located in point symmetry with respect to one arbitrary first opening among the plurality of first openings as a center. It is preferred that an attraction force provided by a magnet acting on the island-like portions of the composite magnetic layer acts symmetrically on each of the first openings. A reason for this is that if the attraction force is asymmetrical, the first openings may possibly be deformed. In order to make the attraction force acting on each first opening symmetrical, a pair of (two) island-like portions located in point symmetry horizontally with respect to the center of the first opening and a pair of (two) island-like portions located in point symmetry vertically with respect to the center of the first opening are located, for example. In the case where, for example, the first opening is of a rectangle longer in a vertical direction, the distance between the pair of island-like portions located in the vertical direction is longer than the distance between the pair of island-like portions located in a horizontal direction. Instead of, or in addition to, these island-like portions, two pairs of island-like portions may be located in diagonal directions of the first opening. 
     The composite magnetic layer included in the vapor deposition mask in an embodiment according to the present invention contains soft ferrite powder having an average particle diameter shorter than 500 nm and a resin. 
     In order to, for example, form pixels of a high-definition organic EL display device of 250 ppi or greater, a vapor deposition mask having openings of, for example, about 40 μm is needed. In order to form such openings with high size precision, the restriction that the particle diameter is 1 μm or shorter as described in Patent Document No. 2 is not sufficient. It is preferred to use soft ferrite powder having an average particle diameter shorter than 500 nm, preferably 300 nm or shorter. It is preferred that the maximum diameter of the particles included in the powder is shorter than 500 nm. It is preferred that the average particle diameter of the soft ferrite powder is 10 nm or longer. There is no specific limitation on the minimum diameter of the particles included in the soft ferrite powder. It is preferred that the minimum diameter of the particles included in the soft ferrite powder is 1 nm or longer. If the particle diameter of the soft ferrite powder is too short, a problem may occur that the dispersibility of the particles is decreased or that the fluidity of the dispersion liquid used to form the composite magnetic layer is decreased. Powder having an average particle diameter shorter than 500 nm has a relatively narrow particle size distribution, although this depends on the method for production. 
     “Soft ferrite” refers to ferrite exhibiting soft magnetism, and contains iron oxide (Fe 2 O 3  and/or Fe 3 O 4 ) as a main component. Currently, soft ferrite is in a wide use for various applications. Main types of soft ferrite are, for example, Mn—Zn-based, Cu—Zn-based, Ni—Zn-based, and Cu—Zn—Mg-based soft ferrite. For example, Mn—Zn ferrite having a particle diameter of about 0.5 μm (500 nm) is used for a chip inductor. 
     The vapor deposition mask in an embodiment according to the present invention uses soft ferrite powder, whereas the vapor deposition mask described in Patent Document No. 2 uses metal powder. Soft ferrite is an oxide. Therefore, soft ferrite powder is chemically more stable than metal powder even if having an average diameter shorter than 500 nm, and thus may be handled safely. An oxide has high affinity with a resin (e.g., polyimide, epoxy resin, etc.) and is dispersed stably. Even after the resin is cured or solidified, the adhesiveness at the interface between the soft ferrite and the resin is high. The soft ferrite powder and the resin are dispersed in a solvent. The resultant dispersion liquid is applied to the base film. The solvent is removed and the resin is cured (or solidified), and as a result, the composite magnetic layer is formed. In order to improve the dispersibility of the soft ferrite powder in the dispersion liquid, a surfactant or a dispersant may be incorporated. In order to improve the adhesiveness at the interface between the soft ferrite powder and the resin in the composite magnetic layer, a silane coupling agent or the like may be incorporated. Alternatively, surfaces of the soft ferrite particles may be pre-treated (covered) with a surfactant or a silane coupling agent. 
     It is preferred to use soft ferrite powder having a coercive force of 100 A/m or less, and it is more preferred to use soft ferrite powder having a coercive force of 40 A/m or less. Invar, which is currently used for a composite magnetic layer, has a coercive force of about 32 A/m. The composite magnetic layer is less rigid than invar and thus is easily deformed. Namely, if the composite magnetic layer is magnetized and has residual magnetization, the composite magnetic layer and the base film may possibly be deformed by the magnetic force. In order to prevent the composite magnetic layer from being deformed by the residual magnetization, it is preferred to remove the residual magnetization from the composite magnetic layer (to demagnetize the composite magnetic layer). The demagnetization may be performed in any of various methods. For example, an alternating attenuated magnetic field may be used for the demagnetization. Alternatively, the soft ferrite powder may be heated to the Curie temperature to perform the demagnetization. Such a method of demagnetization by heating is simple. In consideration of the heat resistance of the resin contained in the base film and the composite magnetic layer, it is preferred that the soft ferrite has a Curie temperature lower than 250′C. 
     It is difficult to measure the physical properties such as the coercive force and the Curie temperature of the soft ferrite powder. Therefore, the physical properties of the powder are evaluated based on the physical properties of a bulk of soft ferrite having the same composition. 
     The resin contained in the composite magnetic layer may be a thermoplastic resin, but a thermosetting resin is preferred. The thermosetting resin is highly adhesive with the base film. The thermosetting resin is also superior to a thermoplastic resin in the heat resistance and/or the chemical stability. Examples of the thermosetting resin include an epoxy resin, polyimide, polyparaxylene, bismaleimide, silica hybrid polyimide, phenol resin, polyester resin and silicone resin. From the point of view of adhesiveness, epoxy resin and polyimide are especially preferred. 
     Examples of preferably usable polyimide may include thermosetting polyimide (obtained by applying a solution of polyamic acid, which is a precursor of polyimide, and heating and thus curing the polyamic acid while heating and thus removing the solvent) and soluble polyimide (obtained by applying polyimide dissolved in a solvent and heating and thus removing the solvent). In the case where the base film is formed of polyimide, it is preferred that the resin contained in the composite magnetic layer contains the same type of polyimide as that contained in the base film. In this case, the polyimide may be thermosetting or soluble. The resin contained in the composite magnetic layer and the polyimide contained in the base film may be of the same type, so that the adhesiveness between the composite magnetic layer and the base film is improved. In the case where polyimide having a small coefficient of thermal expansion (e.g., about 6 ppm/° C.) is used, the difference in the coefficient of thermal expansion between the composite magnetic layer and a work (object on which vapor deposition is to be performed; for example, glass) is made small. The difference in the coefficient of thermal expansion between the composite magnetic layer and the work may be made small, so that even if the temperature is raised during the vapor deposition, the thermal stress generated is small and thus the vapor deposition mask is suppressed from being deformed. The composite magnetic layer may include island-like portions discretely located, so that the thermal stress is decreased. Recently, a vapor deposition device utilizing a temperature rise has been developed. In order to perform vapor deposition with a high definition pattern, it is preferred to perform a preliminary experiment to form openings in consideration of the deformation caused by the heat generated at the time of the vapor deposition. 
     The soft ferrite powder contained in the composite magnetic layer has a volume fraction of, for example, 15% by volume or higher and 80% by volume or lower. The composite magnetic layer is provided to express an attraction force provided by the magnet, and thus it is sufficient as long as a sufficient attraction force is expressed. It is difficult to find, by calculation, the attraction force provided by the magnet. Therefore, a preliminary experiment is performed to finally determine the strength of the magnetic field generated by the magnet and the structure of the vapor deposition mask. The attraction force is influenced by the strength of the magnetic field, the magnetic permeability of soft ferrite, and the strength of the demagnetizing field associated with the thickness of the composite magnetic layer. Therefore, the parameters of the vapor deposition mask to be optimized include the thickness, the area ratio and the volume ratio of the composite magnetic layer (solid portion where the composite magnetic body is actually present) in the vapor deposition mask (region inner to the frame), and also the volume fraction of the soft ferrite powder contained in the composite magnetic layer. The magnetic field to be applied to the composite magnetic layer in order to put the vapor deposition mask into close contact with the work is, for example, 10 mT (milli-tesla) or larger and 100 mT or smaller. If the magnetic field is smaller than 10 mT, a sufficient attraction force may not be provided; whereas if the magnetic field is larger than 100 mT, dust may be attracted. Examples of usable magnet include a permanent magnet such as a rare earth magnet or the like, and an electromagnet. In the case where a permanent magnet is used, it is preferred that a plurality of permanent magnets are located in accordance with the positional arrangement of the solid portion in order to cause a uniform attraction force to act on the composite magnetic layer. 
     The vapor deposition mask in an embodiment according to the present invention includes the frame joined to a peripheral portion of the base film. The frame is joined to the base film without the composite magnetic layer being provided between the frame and the base film. The base film and the frame are joined together with, for example, an adhesive. It is preferred that the adhesive contains a thermosetting resin and has a heat resistance of about 250° C. 
     The frame does not need to be formed of a magnetic material, and may be formed of a nonmagnetic material. The frame may be formed of, for example, a resin such as ABS (acrylonitrilebutadienestyrene), PEEK (polyetheretherketone), polyimide or the like. In order to improve the mechanical properties (e.g., rigidity) of the frame, a fiber reinforced composite material (e.g., CFRP), for example, may be used. It is preferred to use CFRP containing polyimide as a matrix resin. 
     Hereinafter, embodiments according to the present invention will be described with reference to the drawings. The present invention is not limited to any of the following embodiments. 
     With reference to  FIG. 1( a )  and  FIG. 1( b ) , a vapor deposition mask  100 A in an embodiment according to the present invention will be described.  FIG. 1( a )  and  FIG. 1( b )  are respectively a plan view and a cross-sectional view schematically showing the vapor deposition mask  100 A.  FIG. 1( b )  shows a cross-section taken along line  18 - 1   i ′ in  FIG. 1( a ) .  FIG. 1  schematically shows an example of vapor deposition mask  100 A. Needless to say, none of, for example, the sizes of, the numbers of, the relative positions of, and the ratio between lengths of, the components is limited to those shown in the figures. This is applicable to the other figures referred to below. 
     As shown in  FIG. 1( a )  and  FIG. 1( b ) , the vapor deposition mask  100 A includes a base film  10 A and a composite magnetic layer  20 A formed on the base film  10 A. Namely, the vapor deposition mask  100 A has a structure in which the base film  10 A and the composite magnetic layer  20 A are stacked on each other. The assembly of the base film  10 A and the composite magnetic layer  20 A will be referred to as a “stack body  30 A”. 
     The base film  10 A contains a polymer, and is typically formed of a polymer. As the polymer, polyimide is preferred. The base film  10 A may contain a polymer and a filler. The base film  10 A includes a plurality of first openings  13 A. A portion of the base film  10 A other than the first openings  13 A, namely, a portion where the base film  10 A is actually present, is referred to as a “solid portion  12 A”. 
     When the vapor deposition mask  100 A is located such that the base film  10 A is in close contact with a work (object on which vapor deposition is to be performed), an organic semiconductor material, for example, is vapor-deposited in a region defined by the plurality of first openings  13 A. The plurality of first openings  13 A, for example, are arrayed in a matrix including rows and columns. The row direction is defined as the horizontal direction and the column direction is defined as the vertical direction in this example, but these directions are not limited thereto. The plurality of first openings  13 A are formed to have a size and a shape suitable to, and are located at positions suitable to, a vapor deposition pattern that is to be formed on the work. The first openings  13 A are typically quadrangular, for example, rectangular, but is not limited to having such a shape and may have any shape. 
     The composite magnetic layer  20 A is formed on the base film  10 A, in a region inner to a frame  40 A. The composite magnetic layer  20 A includes a solid portion  22 A and a non-solid portion  23 A. In this example, the non-solid portion  23 A includes a plurality of second openings  23 A. The plurality of second openings  23 A of the composite magnetic layer  20 A correspond to the first openings  13 A of the base film  10 A on a one-to-one basis. The second openings  23 A of the composite magnetic layer  20 A are formed in a self-alignment manner with the first openings  13 A of the base film  10 A. 
     There is no specific limitation on the thickness of the base film  10 A. It should be noted that if the base film  10 A is too thick, a part of a vapor deposition film may be thinner than a desired thickness (referred to as “shadowing”). From the point of view of suppressing generation of shadowing, it is preferred that the base film  10 A has a thickness of 25 μm or less. From the point of view of the strength and the resistance against washing of the base film  10 A itself, it is preferred that the base film  10 A has a thickness of 3 μm or greater. 
     As described above, the structure of the composite magnetic layer  20 A is optimized together with the strength of a magnetic field generated by a magnet, such that a sufficient attraction force is provided by the magnetic field. The second openings  23 A of the composite magnetic layer  20 A are formed to be aligned with the first openings  13 A of the base film  10 A. Therefore, from the point of view of suppressing the generation of shadowing, it is preferred that a total thickness of the base film  10 A and the composite magnetic layer  20 A is set so as not to exceed 25 μm. 
     The frame  40 A is joined to a peripheral portion of the base film  10 A without the composite magnetic layer  20 A being located between the frame  40 A and the base film  10 A. The base film  10 A and the frame  40 A are joined to each other with, for example, an adhesive (not shown). The frame  40 A may be formed of a nonmagnetic material, for example, a resin. 
     Now, with reference to  FIG. 2 , a method for producing a vapor deposition mask in an embodiment according to the present invention will be described.  FIG. 2  is a flowchart showing the method for producing the vapor deposition mask in this embodiment according to the present invention. 
     First, a base film and a frame are prepared (step Sa). 
     Next, the base film is secured to the frame (step Sb). The base film is, for example, joined to the frame with an adhesive. In this step, the base film may be tensioned when necessary. The base film is tensioned in, for example, the horizontal direction and the vertical direction. In this embodiment according to the present invention, only the base film is tensioned. Therefore, a large tension machine as conventionally required is not required, and the frame may have a mechanical strength and a rigidity lower than those conventionally required. Thus, the frame does not need to be formed of a magnetic metal material, and may be formed of, for example, a polymer. 
     Next, a plurality of first openings are formed in the base film (step Sc). In this step, the base film is put into close contact with a surface of a glass substrate with a liquid being located between the base film and the glass substrate. In this state, a laser beam is radiated, so that the plurality of first openings are formed at predetermined positions with a predetermined shape and a predetermined size. It is preferred to clean the base film in order to remove debris generated as a result of laser ablation. The base film may be cleaned before a composite magnetic layer is formed, so that the composite magnetic layer and the base film are not delaminated from each other and the debris are removed with more certainty. The composite magnetic layer may possibly be delaminated especially when a surface of the base film is mechanically wiped in order to remove the debris of the film, referred to as burr, bound to perimeters of the first openings. 
     Next, the composite magnetic layer containing soft ferrite powder having an average particle diameter shorter than 500 nm and a resin is formed on the base film (step Sd). As described above, a dispersion liquid containing the soft ferrite powder, the resin (encompassing a precursor) and a solvent is prepared and applied to the base film. The solvent is removed and the resin is cured (solidified) to form the composite magnetic layer. The application of the dispersion liquid may be performed by, for example, a screen printing method, a slot printing method or an ink jet method. For example, the composite magnetic layer  20 A of the vapor deposition mask  100 A shown in  FIG. 1  may be formed as follows. The concentration or the like of the dispersion liquid may be adjusted, so that the dispersion liquid is prevented by the surface tension thereof from entering the first openings  13 A of the base film  10 A. Thus, the composite magnetic layer having the second openings  23 A formed in a self-alignment manner with the first openings  13 A is formed. 
     As described below, in the case where a composite magnetic layer having a plurality of island-like portions located in any of various patterns is to be formed, it is preferred to use an ink jet method. 
     With reference to  FIG. 3  and  FIG. 4 , the method for producing the vapor deposition mask  100 A will be described.  FIG. 3( a )  and  FIG. 3( b )  are respectively a plan view and a cross-sectional view showing an example of step of a method for producing the vapor deposition mask  100 A (step Sb).  FIG. 4( a )  and  FIG. 4( b )  are respectively a plan view and a cross-sectional view showing an example of step of the method for producing the vapor deposition mask  100 A (step Sc). 
     As shown in  FIG. 3( a )  and  FIG. 3( b ) , the base film  10 A is secured to the frame  40 A. The base film  10 A is secured to the frame  40 A with, for example, an adhesive (not shown). In this example, only a part of the frame  40 A overlaps the base film  10 A. Alternatively, the entirety of the frame  40 A may overlap the base film  10 A. In this step, the base film  10 A may be tensioned when necessary. In order to heat and thus cure the adhesive in the state where the base film  10 A is tensioned, it is preferred that the frame  40 A is formed of a heat-resistant polymer material. It is preferred that the step of heating and curing the adhesive is performed at a reduced pressure in order to prevent an organic substance from being volatilized from the adhesive in the case where the vapor deposition mask  100 A is used in vacuum. It is preferred that the frame  40 A is formed of, for example, polyimide in order to allow the base film  10 A to be tensioned while the adhesive is heated, although this depends on the heating temperature. In the case where the frame  40 A needs to be rigid, CFRP of polyimide is preferably usable for the frame  40 A. 
     In this embodiment according to the present invention, only the base film  10 A is formed before the composite magnetic layer  20 A is formed. Therefore, the problem that the composite magnetic layer  20 A is delaminated when the base film  10 A is tensioned is solved. 
     Next, as shown in  FIG. 4( a )  and  FIG. 4( b ) , the plurality of first openings  13 A are formed in the base film  10 A (step Sc). 
     In this step, a glass substrate (not shown), for example, is located below the base film  10 A (on a surface of the base film  10 A opposite to a surface on which the frame  40 A is located), and a liquid (e.g., ethanol) is located between the glass substrate and the base film  10 A. The surface tension of the liquid is utilized to put the base film  10 A into close contact with a surface of the glass substrate. In this state, a laser beam is radiated from above the base film  10 A, so that the plurality of first openings  13 A of a predetermined shape and a predetermined size are formed at predetermined positions. 
     It is preferred to clean the surface of the base film  10 A after this in order to remove debris generated as a result of laser ablation. Especially in the case where burr bound to perimeters of the first openings  13 A is generated on a bottom surface of the base film  10 A, it is preferred to wipe the bottom surface of the base film  10 A in order to remove the burr. 
     After this, a dispersion liquid containing soft ferrite powder, a resin (encompassing a precursor) and a solvent is applied to a top surface of the base film  10 A. The solvent is removed and the resin is cured (or solidified) to form the composite magnetic layer  20 A. The step of removing the solvent and heating and thus curing the resin may be formed by use of an electric furnace. 
     Now, with reference to  FIG. 5  through  FIG. 9 , structures of other vapor deposition masks  100 B through  100 G in embodiments according to the present invention will be described. The vapor deposition masks  100 B through  100 G may also be produced by the method described above. It should be noted that non-solid portions  23 B through  23 G of composite magnetic layers  20 B through  20 G of the vapor deposition masks  100 B through  100 G are larger than first openings  13 B through  13 G of base films  10 B through  10 G. Therefore, ever, if the composite magnetic layers  20 B through  20 G are thicker, shadowing does not easily occur. Therefore, the composite magnetic layers  20 B through  20 G may be made thicker than the composite magnetic layer  20 A of the vapor deposition mask  100 A. 
       FIG. 5( a )  is a plan view schematically showing one of the other vapor deposition masks in the embodiments according to the present invention, specifically, the vapor deposition mask  100 B.  FIG. 5( b )  is a cross-sectional view taken along line  5 B- 5 B′ in  FIG. 5( a ) . 
     The vapor deposition mask  100 B includes the base film  10 B, the composite magnetic layer  20 B (stack body  308 ) formed on the base film  10 B, and a frame  40 B joined to a peripheral portion of the base film  10 B. 
     The base film  10 B includes a solid portion  12 B and the plurality of first openings  13 B. The composite magnetic layer  20 B includes a solid portion  22 B and the non-solid portion  23 B. The solid portion  22 B includes a plurality of island-like portions  22 B discretely located. The plurality of island-like portions  22 B include two pairs of island-like portions  22 B located in diagonal directions of each of the first openings  13 B. Namely, four island-like portions  22 B are located in the diagonal directions of each of the first openings  13 B. Therefore, an attraction force provided by a magnet acting on the island-like portions  228  of the composite magnetic layer  20 B acts symmetrically on each of the first openings  138 . 
     In this example, the island-like portions  22 B are circular, for example. Alternatively, the island-like portions  22 B may be polygonal; or tapered, for example, conical. 
       FIG. 6( a )  is a plan view schematically showing another one of the other vapor deposition masks in the embodiments according to the present invention, specifically, the vapor deposition mask  100 C.  FIG. 6( b )  is a cross-sectional view taken along line  68 - 6 B′ in  FIG. 6( a ) . 
     The vapor deposition mask  100 C includes the base film  10 C, the composite magnetic layer  20 C (stack body  30 C) formed on the base film  10 C, and a frame  40 C joined to a peripheral portion of the base film  10 C. 
     The base film  10 C includes a solid portion  12 C and the plurality of first openings  13 C. The composite magnetic layer  20 C includes a solid portion  22 C and the non-solid portion  23 C. The non-solid portion  23 C includes a plurality of slits  23 C. The plurality of slits  23 C, which extend in the column direction, are arrayed in the row direction. The solid portion  22 C is continuously formed in a region other than the non-solid portion  23 C. As seen in a direction normal to the vapor deposition mask  100 C, each of the slits  23 C is larger than each of the first openings  13 C of the base film  10 C, and two or more first openings  13 C are located in each of the slits  23 C (the number of the first openings  13 C is not limited to the number shown in  FIG. 6 , needless to say). 
       FIG. 7( a )  is a plan view schematically showing still another one of the other vapor deposition masks in the embodiments according to the present invention, specifically, the vapor deposition mask  100 D.  FIG. 7( b )  is a cross-sectional view taken along line  7 B- 78 ′ in  FIG. 7( a ) . 
     The vapor deposition mask  100 D includes the base film  10 D, the composite magnetic layer  20 D (stack body  30 D) formed on the base film  10 D, and a frame  40 D joined to a peripheral portion of the base film  10 D. The base film  10 D includes a solid portion  12 D and the plurality of first openings  13 D. The composite magnetic layer  20 D includes a solid portion  22 D and the non-solid portion  23 D. The non-solid portion  23 D is one second opening  23 D, in which all the first openings  13 D are located. The solid portion  22 D is continuously formed in a region other than the non-solid portion  23 D. 
       FIG. 8( a )  is a plan view schematically showing still another one of the other vapor deposition masks in the embodiments according to the present invention, specifically, the vapor deposition mask  100 E.  FIG. 8( b )  is a cross-sectional view taken along line  8 B- 8 B′ in  FIG. 8( a ) . 
     The vapor deposition mask  100 E includes the base film  10 E, the composite magnetic layer  20 E (stack body  308 ) formed on the base film  10 E, and a frame  40 E joined to a peripheral portion of the base film  10 E. The base film  101  includes a solid portion  12 E and the plurality of first openings  13 E. The composite magnetic layer  20 E includes a solid portion  22 E and the non-solid portion  23 E. The non-solid portion  23 E includes a plurality of second openings  23 E. One first opening  131  is located in each of the second openings  238 . Each of the second openings  23 E is larger than each of the first openings  138 . The solid portion  221  is continuously formed in a region other than the non-solid portion  23 E. 
       FIG. 9( a )  and  FIG. 9( b )  are respectively plan views schematically showing still other ones of the other vapor deposition masks in the embodiments according to the present invention, specifically, the vapor deposition masks  1001  and  100 G. 
     The vapor deposition mask  100 F shown in  FIG. 9( a )  includes the base film  10 F, the composite magnetic layer  20 F (stack body  30 F) formed on the base film  10 F, and a frame  40 F joined to a peripheral portion of the base film  10 F. The base film  10 F includes a solid portion  12 F and the plurality of first openings  13 F. The composite magnetic layer  20 F includes a solid portion  22 F and the non-solid portion  23 F. The non-solid portion  23 F includes two second openings  23 F. The solid portion  221  includes a peripheral portion continuously formed around the second openings  23 F and island-like portions  22 F discretely located in the second openings  23 F. 
     The vapor deposition mask  100 G shown in  FIG. 9( b )  includes the base film  10 G, the composite magnetic layer  20 G (stack body  30 G) formed on the base film  10 G, and a frame  40 G joined to a peripheral portion of the base film  10 G. The base film  10 G includes a solid portion  12 G and the plurality of first openings  13 G. The composite magnetic layer  20 G includes a solid portion  22 G and the non-solid portion  23 G. The non-solid portion  23 G is one second opening  23 G, in which all the first openings  13 G are located. The solid portion  22 G includes a peripheral portion continuously formed around the second opening  23 G and island-like portions  22 G discretely located in the second opening  23 G. 
     The vapor deposition mask in an embodiment according to the present invention may have a structure in which unit regions each corresponding to one device (e.g., organic EL display device) are located two-dimensionally. The vapor deposition mask having such a structure is preferably usable to form a plurality of devices on one substrate as an object on which vapor deposition is to be performed. 
       FIG. 10( a ) ,  FIG. 10( b ) ,  FIG. 11( a )  and  FIG. 11( b )  are respectively plan views showing still other vapor deposition masks  300 A,  300 B,  300 C and  300 D in embodiments according to the present invention. These vapor deposition masks each include a plurality of (six in this example) unit regions UA through UD located at an interval as seen in a direction normal thereto. The unit regions UA of the vapor deposition mask  300 A each have substantially the same pattern as that of the vapor deposition mask  100 A. The unit regions UB of the vapor deposition mask  300 B, the unit regions UC of the vapor deposition mask  300 C, and the unit regions UD of the vapor deposition mask  300 D each have substantially the same pattern as that of the vapor deposition mask  100 B. The solid portion  22 B of the vapor deposition mask  300 B do not include a portion located between the unit regions UB. By contrast, the solid portion  22 C of the composite magnetic layer  20 C of the vapor deposition mask  300 C includes a portion continuously formed between the unit regions UC. The solid portion  22 D of the composite magnetic layer  20 D of the vapor deposition mask  300 D includes island-like portions  22 D located between the unit regions UD. 
     The vapor deposition mask in an embodiment according to the present invention includes a composite magnetic layer as described above, and thus is easily made large and may be formed to have a high-definition pattern. Therefore, the vapor deposition mask is preferably usable to mass-produce, for example, a high-definition organic EL display device. 
     INDUSTRIAL APPLICABILITY 
     A vapor deposition mask in an embodiment according to the present invention is preferably usable to produce an organic semiconductor device such as an organic EL display device, and is especially preferably usable to produce an organic semiconductor device, for which a high-definition vapor deposition pattern needs to be formed. 
     REFERENCE SIGNS LIST 
     
         
           10 A base film 
           12 A solid portion 
           13 A first opening (non-solid portion) 
           20 A composite magnetic layer 
           22 A solid portion 
           23 A non-solid portion (second opening) 
           40 A frame 
           100 A vapor deposition mask 
         UA unit region