Patent ID: 12226854

EMBODIMENT FOR CARRYING OUT THE INVENTION

Hereinafter, a deposition mask, a method of manufacturing the deposition mask, and a mask member for the deposition mask according to one embodiment of the present invention will be described with reference to the accompanying drawings.FIG.1is an explanatory view of a cross section of a deposition mask10formed in a state where opening portions are formed in a mask member according to one embodiment of the present invention, andFIGS.2A to2Gare explanatory views of cross sections in respective steps of a method of manufacturing the deposition mask. Although only three opening portions are shown in the figures, in practice, the deposition mask may have a larger number of opening portions, for example, corresponding to the number of pixels (including R, G, and B sub-pixels) of a plurality of organic EL display apparatuses.

The present inventors have found that burrs81band foreign particles81cmay be generated, for example, as illustrated inFIG.9B or9C, even when the opening portions81aare formed in a resin film81on a protective layer84made of a resin layer or a liquid layer as illustrated inFIG.10mentioned above.FIG.9Bis a picture when using a resin layer as the protective layer84, andFIG.9Cis a picture when using an ethanol as the protective layer84. In these pictures, the foreign particles81cattach to the resin film81as dust particles, and the burrs81bextend to within the opening portions81a. Some of the burrs81bdroop as described above, whereas some of the burrs81battach again to the resin film81after scattered in the air. Note thatFIGS.9B and9Cshow the pictures of the resin film81after removing the process stage85and the protective layer84, and before washing. Specifically,FIG.9Bshows the picture of the surface of the resin film81observed from a side opposite to a laser light irradiation side, andFIG.9Cshows the picture of the surface of the resin film81observed from the laser light irradiation side in the same manner.

The present inventors have intensively studied the cause of the close contact of the burr81band the foreign particle81cto the resin film81, and found that, for example, as shown inFIG.9A, a part of the resin film81droops, thus generating the burrs81b. As a result of further studies about this cause, it is considered that the close contact of the burrs and foreign particles is due to the fact that the resin film81is thermally deformed to form a gap84abetween the protective layer84and the resin film81as shown inFIG.9A. That is, if a part of the surface of the resin film81is irradiated weakly with the laser light, resin material in this part are less likely to sublime from the front surface side of the resin film and may fail to sublime completely. Eventually, a thin part of the resin film81tends to be left there. This thin remaining part of the resin film81is more likely to droop due to shock of the laser light. As a result, it is thought that such drooping of a part of the resin film81generates burrs81bas shown in the right diagram ofFIG.9A. In other words, even when the resin film81is irradiated with the laser light, all resin parts of the resin film81located in the opening portions are not completely sublimed to be scattered in the air. Some of these resin parts may be partially broken and scattered in the air to attach to the deposition mask made of the resin film. Some resin parts may be bent downward without being sublimed completely and left as burrs81bto partially cover the opening portions81a. InFIG.9A, reference number82adenotes a seed layer for forming a metal support layer82by a plating method. However, the seed layer is not required in a case where the metal support layer is not formed by the plating method. Such burrs or foreign particles could be transferred to the substrate for vapor deposition to become obstacles to the vapor deposition, causing black spots on a resultant image displayed on a display screen. In this way, the burrs and foreign particles cause troubles.

Furthermore, the present inventors have intensively studied in order to prevent a part of the resin of the resin film from being incompletely sublimed and remaining as burrs in the opening portion of the deposition mask including the resin film, or to prevent a scattered part of the resin from attaching as burrs inside the opening portion. As a result of this study, the inventors have found that the reason why a part of the resin film remains without being sublimed is that since the output of the irradiated laser light is not uniform as a whole, there occurs a weak part of the laser light, and hence this weak part of the laser light cannot completely sublimate the resin. Further, another reason is that as described above, when the resin film is deformed by heat during irradiation with the laser light, a space is formed between the resin film and the protective layer, and if a part of the resin droops into the space, the resin film becomes more difficult to irradiate with the laser light and are eventually more likely to remain as burrs. Moreover, the inventors have conceived of not only irradiation with the laser light from the front surface side of the resin film, but also irradiation with the laser light from the back surface side of the resin film using the reflected light of the laser light transmitted through the resin film. Consequently, the present inventors have found that all parts of the resin film located in the opening portions substantially across the entire surface of the resin film can be removed without leaving any resin in the opening portions by adding the laser light reflected from the back surface of the resin film even if the laser light rays are partially weak in intensity.

The following two phenomena are considered as main reasons why burrs can be effectively removed by using the reflected light of the laser light. First, it is considered that the reflected laser light is generated mainly when the resin on the front surface (the surface of the resin film on the light irradiation source side for the laser light) of the resin film in each of the opening portions is removed by sublimation, and at this time, the resin is easily sublimed even by irradiation with the laser light from the back surface (the surface opposite to the front surface) side of the resin film. Supposing that opening portions are formed by laser light in a resin film made of polyimide or the like which has a thickness of approximately several μm to 10 μm, pulsed laser light sequentially strikes the resin film at approximately 50 shots or less to 100 shots or more. The wavelength of this laser light is selected, at which the resin easily adsorbs the laser light. In the initial irradiation with the laser light, most of the laser light is absorbed in the resin film from the front surface side, so that the resin in the front surface side of the resin film is sublimed. Here, the laser light hardly reaches to reach a reflective film, and thus a reflected light is hardly generated. Then, when an opening portion-formation region of the resin film becomes considerably thin, the emitted laser light is not completely absorbed in the resin film, and thus the laser light partly passes through the resin film and exits from the back surface side thereof to reach the reflective film. Thus, in the presence of the reflective film on the back surface side, the laser light is reflected and returned back to the resin film. This reflected light from the back surface side is absorbed in the resin film. At that time, since the resin in the opening portion-formation region of the front surface side is mostly removed, the resin on the back surface side also tends to sublime. In other words, when the situation is reached in which resin material in the back surface of the resin film is easily sublimed, the reflected light is automatically intensified, thereby enabling the resin to sublime.

Secondly, some of the laser light is incident on the front surface of the resin film at an incident angle of at most approximately 30° or less. Some of the laser light is incident substantially vertical, namely, at an incident angle of approximately 0°. As a result, an area on the back surface of the resin film to which the reflected light is returned is limited to the opening portion-formation region and its surrounding, depending on the thickness and refractive index of a close contact layer. Specifically, the laser light incident vertically on the resin film is also reflected vertically by the reflective film as it is. However, the laser light is not always incident vertically. The laser light that is incident on the resin film at some incident angle are reflected diagonally. Because of this, even when some parts of the resin film potentially remain after the irradiation with the laser light due to the presence of the partially weak laser light, the diagonally coming, reflected light is easily absorbed in these parts, thereby successfully facilitating the sublimation of the parts. However, since the incident angle of the laser light ranges of approximately 0° or more and 30° or less, the reflected light does not spread out so widely. The detailed relationship between the incident angle and the reflected light will be described later. Thus, the whole area of the resin film does not receive the reflected light of the laser light, and any laser marks formed by irradiating parts of the back surface of the resin film other than the opening portion-formation region by the reflected light have a depth of approximately 0.3 μm or less, and it is obviously less than 1 μm. Consequently, this does not lead to a problem of reduced mechanical strength of the resin film. Rather, since laser marks are also formed on the area of the surface other than the opening portions, a surface area of the resin film becomes larger due to the unevenness of its surface, resulting in an increase in heat radiation. As a result, the temperature of the deposition mask, which increases due to the radiation heat from the vapor deposition source during vapor deposition, is dissipated from the surface of the deposition mask on the opposite side to the vapor deposition source, which contributes to lowering the temperature of the deposition mask. That is, the surface of the deposition mask on which the laser marks are formed is a surface to be superposed onto a substrate for vapor deposition, in other words, the surface of the deposition mask located on an opposite side to a surface facing the vapor deposition source. The resin film with the larger heat radiation is more convenient from the viewpoint of reducing the temperature of the deposition mask.

As shown inFIG.1, the method of manufacturing a deposition mask according to the present embodiment is characterized by comprising depositing a light irradiation source on one surface of the resin film11, the light irradiation source being adapted to emit laser light for forming the pattern of the opening portions11a; providing a reflective film30on the other surface of the resin film11, the reflective film30being adapted to reflect the light having the wavelength of the laser light emitted from the light irradiation source for the laser light, and using the laser light reflected by the reflective film30to form the pattern of the opening portions11ain the resin film11That is, as shown inFIG.1, the first feature of the present invention is that the reflective film30is formed on the other surface of the resin film11located on an opposite side to the irradiation source side of the laser light.

In the example shown inFIG.1, a close contact layer20is formed between the resin film11and the reflective film30. The reason why the close contact layer20is formed in this manner is to prevent formation of an air layer between the resin film11and the reflective film30as much as possible. That is, if the surface of the resin film11is formed in a wave shape with the air layer interposed between the resin film11and the reflective film30, the laser light is more likely to be diffusely reflected at the interface therebetween because of a small refractive index of the air layer. In addition, there is a higher possibility that the reflected light is reflected by the reflective film30in the direction away from the opening portion11a. For this reason, preferably, a layer having a refractive index as close as possible to the refractive index of the resin film11contacts to the resin film11. If the refractive index of the close contact layer20is higher than that of the resin film11, the refraction angle is smaller than the incident angle in the close contact layer20, as the refracted light is likely to approach the incident light which is incident vertically. Meanwhile, as the close contact layer20needs to be finally removed from the resin film11, the close contact layer20is required to be separable easily from the resin film11. The close contact layer20is preferably made of a material that absorbs the laser light for forming the opening portions11aas little as possible. This is because for the purpose of utilizing the reflected light, the light transmitted through the resin film11is preferably reflected without being wasted as much as possible. More specifically, the close contact layer20may be a resin film that transmits approximately 80% or more of near-ultraviolet light (in a wavelength range of 200 to 380 nm) (which is referred to below simply as the “resin film”). Examples of the resin film include a polyvinyl acetate (PVAC) film, a polyvinyl pyrrolidone (PVP) film, a self-assembled molecular (SAM) film and the like.

The present embodiment aims to use the laser light reflected by the reflective film30to locally heat the back surface of the resin film11. For this purpose, a range of which the laser light reflected by the reflective film30reaches to the back surface of the resin film11needs to fall within a range of a focal depth of convergent laser light. In this case, for example, the focal depth of the laser light is set to approximately ±10 μm. For instance, in the case of the laser light focused on the front surface of the resin film11, if the thickness of the resin film11is 5 μm, for example, the thickness of the close contact layer20would be 2.5 μm, so that the round-trip distance through the close contact layer20is 5 μm. Consequently, the back surface of the resin film11is positioned at the limit of the focal depth of 10 μm. Therefore, the thickness of the close contact layer20needs to be 2.5 μm or less. If the resin film11is thicker, by adjusting the convergence point of the laser light to the interior or back surface of the resin film11, the reflected light reaches the back surface side of the resin film11within the focal depth range and thereby can heat the back surface of the resin film11. In this way, by focusing the convergence point onto the interior or back surface of the resin film11, the close contact layer20could be thickened. However, as described above, since the close contact layer20is provided in order to obtain the close contact between the resin film11and the reflective film30, the close contact layer20is preferably as thin as possible from the viewpoint of the loss of the laser light and the manufacturing cost. Accordingly, the thickness of the close contact layer20is 0.1 μm or more and 3 μm or less, preferably 0.1 μm or more and 2.5 μm or less, and more preferably 0.1 μm or more and 2 μm or less.

To reduce the spreading of the reflected light, as described above, the refractive index of the close contact layer20is preferably set to be equal to or more than that of the resin film11. However, in consideration that the laser light includes a partly weak portion and the possibility of generating a resin part where sublimation is insufficient, it is advantageous for the laser light having passed through the resin film11to be reflected diagonally rather than vertically, in order to completely sublimate non-sublimed resin parts of the resin film11with the strong laser light. From this aspect, the refractive index of the close contact layer20is not necessarily equal to or more than that of the resin film11. Further, even if an air gap is formed between the resin film11and the close contact layer20, the angle of refraction of the incident light into the close contact layer20becomes small although the angle of refraction of the incident light from the air gap is large, because the refractive index of the close contact layer20is greater than that of the air gap. Thus, there is no problem as long as the width of the air gap is narrow. As described above, the close contact layer20preferably does not absorb any laser light (for example, light with a wavelength of 335 nm). Because of this, the close contact layer20is formed using a material that has a transmittance of 70% or more, preferably 80% or more, and more preferably 85% or more at the wavelength of the light.

The reflective film30preferably has a reflectance of the laser light that is as high as possible. For example, a reflective sheet made of a metal film of aluminum, silver, or the like, or a reflective film with a high reflectance made of multilayer films is used as the reflective film30of the laser light. The multilayer reflective films are multilayer films formed by alternately stacking two kinds of dielectric films having different refractive indices. For example, multilayer films made of Al2O3and SiO2are preferable because they are inexpensive and can exhibit reflectances of approximately 99% or more. These films can be easily deposited by an electron beam (EB) vapor deposition, an electron cyclotron resonance (ECR) sputtering, or the like. In another example, as shown inFIG.5, the reflective films30can be obtained by depositing a single-crystal film31of aluminum and a multilayer film32. The multilayer films32are formed by depositing one or more sets of layers, each set including, for example, two layers with different refractive indices which are deposited by a chemical vapor deposition (CVD) method, and more specifically, a MgF2layer and a Sc2O3layer, each of which is deposited to have a thickness of λ/(4n) (where n is a refractive index of the layer material, and λ is a wavelength of the laser light). The single-crystal film31made of aluminum may be formed by adjusting the deposition conditions for the CVD method. Note that the above reflective sheet is preferably formed by depositing one or more dielectric films on a metal film. The reflective films30may be formed to have a thickness ranging from approximately 1 μm or more and 2.5 μm or less in total, and to have reflectances of 80% or more and more preferably 90% or more.

Next, referring to specific examples ofFIGS.2A to2G, a method of manufacturing the deposition mask according to the present invention will be described in detail. First, as shown inFIG.2A, the resin film11is formed on a support substrate36. The resin film11may be formed by applying a liquid resin material to the support substrate36. Examples of the liquid resin material include a polyimide (PI) resin, a polyethylene naphthalate (PEN) resin, a polyethylene terephthalate (PET) resin, a cycloolefin polymer (COP) resin, a cyclic olefin copolymer (COC) resin, a polycarbonate (PC) resin, polyamide resin, a polyamide-imide resin, a polyester resin, a polyethylene resin, a polivinyl alcohol resin, a polypropylene resin, a polystyrene resin, a polyacrylonitrile resin, an ethylene vinylacetate copolymer resin, an ethylene-vinyl alcohol copolymer resin, an ethylene-methacrylic acid copolymer resin, a polyvinyl chloride resin, a polyvinylidene chloride resin, and an ionomer resin. For example, the polyimide resin is preferable because, when the resin film is formed by applying a precursor solution and then performing heat treatment, the linear expansion coefficient of the resin film made of the polyimide resin can be adjusted depending on the condition including a temperature rise profile during the heat treatment, or the like. However, the resin film11is not limited to the above-mentioned type. Alternatively, the resin film in the form of a sheet may be attached to the support substrate36. When the resin film11is produced by coating a liquid resin material, a uniform coating film can be formed by, for example, slit coating, spin coating or the like. The thickness of the resin film11is approximately several μm to several tens μm, for example, about 5 μm. When the resin film11is produced by applying a liquid resin material, for example, the applied resin material is heated to, for example, approximately 400° C. or higher and approximately 500° C. or lower. The linear expansion coefficient of the resin film11can be adjusted by regulating the heating condition. The support substrate36may be, for example, a glass substrate having a flat front surface. The resin film11preferably has a linear expansion coefficient close to that of the substrate for vapor deposition to be deposited when used as the deposition mask10.

As illustrated inFIG.2B, a seed layer12ais formed on the resin film11through electroless plating so as to have a thickness of approximately 0.05 μm or more and 0.5 μm or less. Then, a metal film12bis formed on the seed layer12athrough electrolytic plating by passing an electric current through the seed layer12a. The metal film12bwill be patterned at a subsequent step to form a metal support layer12, which serves to suppress warping of the resin film11. The metal film12bmay be made of a metal material, such as Fe, Ni, a Fe—Ni alloy, invar, or the like and may have a thickness of 20 μm or more and 60 μm or less. The metal film12bis preferably made of a magnetic substance, because a magnetic force can be used to closely fix the deposition mask10to the substrate for vapor deposition. It should be noted that the metal support layer12may be optional. Even when the metal support layer12is formed, the electrolytic plating is not necessarily used. Alternatively, the metal film12bmay be formed by a sputtering, vacuum deposition, or the like. Furthermore, alternatively the metal film12bmay be formed using a metal foil. Even when the metal film12bis formed by plating, the seed layer12ais not necessarily formed by electroless plating. Alternatively, the seed layer12amay be formed by the sputtering, vacuum deposition, or the like.

Then, both the metal film12band the seed layer12aare patterned to form opening holes12c, each of which is slightly larger than the opening portion11a. That is, the metal film12band the seed layer12aare formed to avoid at least the formation region of the opening portion11ain the resin film11. For example, a tapered opening hole12cshown in the figure is formed by providing a resist film (not shown) on the metal support layer12and performing isotropic etching via the resist film. The reason why the opening hole12cis formed to have the tapered shape is as follows. That is, as shown inFIG.8A, an organic material54is flying from the vapor deposition source60in a wrapper-like bundle (referred to as vapor deposition beams) with a constant angle θ (a vapor deposition angle) of the vapor deposition source60. This is because particles of the vapor deposition at the side edges of the bundle of the vapor deposition beams also reach to the substrate for vapor deposition without being blocked. Strictly speaking, when θ inFIG.8Ais a vapor deposition angle, an taper angle (an acute angle formed relative to the bottom surface of the taper) of the mask is preferably equal to or less than the vapor deposition angle θ. However, when the opening hole12cis sufficiently larger than the opening portion11aof the resin film11, the opening hole12cmay be formed with an arbitrary taper angle. Alternatively, the opening hole12cmay be formed without such etching, for example, by providing a resist film on the portions where the opening holes12care to be formed, in the step ofFIG.2B, to prevent electrolytic plating, or performing sputtering or the like by a lift-off method. The metal support layer12may be formed on the entire surface around the opening portions11aof the resin film11, or may be formed in a post shape around each opening portion11a. The opening holes12cmay be formed in a slit shape.

Then, the resin film11is peeled off from the support substrate36, and as shown inFIG.2D, the resin film11is stretched and fixed to the frame13, thereby producing a resin film assembly10a. This stretching of the resin film11is performed because, if the resin film11is loosely fixed to the frame13, the opening portions11aare formed with the inaccurate size. Due to this, as long as the resin film11is constantly in a stretched state, this stretching step is not necessarily performed, and the resin film11only may be just attached to the frame13. The frame (frame body)13is, for example, required to have enough stiffness to withstand tension when the tension is applied thereto. A metal plate having a thickness of 25 mm or more and 50 mm or less is used as the frame13. The frame13may not be used unless necessary. However, using the frame13is preferred in terms of handleability of the resin film assembly10a. In the presence of the metal support layer12, the frame13may be fixed to the metal support layer12by laser welding or the like in a stretched state with respect to the resin film11. On the other hand, in the absence of the metal support layer12, the frame13may be bonded directly to the resin film11with an adhesive or the like. In this case, the adhesive is preferably used, which does not generate any gas during vapor deposition. For example, a fully cured adhesive such as an epoxy resin is preferable as the adhesive. Even when the tension is barely applied to the resin film11(which means the resin film11is not stretched), from the viewpoint of a certain degree of mechanical strength and handleability, the frame13is preferably provided which is made of, for example, a metal plate or plastic plate that has a thickness of 10 mm or more and 30 mm or less. If the frame13is a metal plate having a magnetic property, the frame13can be easily fixed to the substrate for vapor deposition using any magnet even when the metal support layer12is not provided.

Then, as shown inFIG.2E, the resin film11is fixed to a process stage35. At this time, the close contact layer20and the reflective film30are interposed between the resin film11and the process stage35. As described above, the close contact layer20may or may not be present, but is preferably inserted between the resin film11and the process stage35because it is preferable that an air layer is not interposed between the resin film11and the reflective film30. For this reason, preferably, the close contact layer20is in contact with the resin film11and further with the reflective film30. For example, the reflective film30made of multilayer films of Al2O3and SiO2or a metal sheet may be formed on the process stage35shown inFIG.5. Subsequently, the close contact layer20made of, for example, a resin film in the film or liquid layer, may be formed on the reflective film30. Then, the resin film assembly10ashown inFIG.2D(or a resin film assembly (not shown) stretched and fixed to a frame) may be provided on the close contact layer20so that the side of the resin film11is in contact with the close contact layer20. In these ways, the mask member10bmay be formed. However, the resin film11does not need to be in perfect contact with the close contact layer20. Alternatively, the resin film assembly10amay be simply overlaid on the close contact layer20, for example, made of PVAC, PVP or the like or may be adhered to the close contact layer20with a dissoluble adhesive that does not erode the resin film11so that the resin film11is separable from the close contact layer20. Forming the reflective film30on the process stage35in this manner makes it possible to continuously use the reflective film30only by re-forming the close contact layer20even when the resin film11is replaced with another after the process, which does not lead to an increase in cost.

In the resin film assembly10a(the metal support layer12is omissible), as illustrated inFIG.2D, the close contact layer20may be formed directly on the back surface (that is opposite to a surface on which the metal support layer12is formed) of the resin film11by the CVD method, vacuum deposition, or the like. Meanwhile, the reflective film30may be formed on the above process stage35. Then, the resin film assembly10ain which the close contact layer20is formed may be fixed to the reflective film30. In this case, the close contact layer20may be formed of any material that enables separation from the resin film11without damaging the resin film11. In particular, the close contact layer20may be formed by an inorganic dielectric film, which is made of SiO2, Si3N4, or the like, using a CVD method or the like. In this way, a mask member10bfor the deposition mask is obtained. It should be noted that the close contact layer20may be formed on the surface of the reflective film30disposed on the process stage35and may not be concurrently formed on the resin film11. Furthermore, the reflective film30may be formed of the above-mentioned dielectric multilayer films32on the close contact layer20. However, the reflective film30is discarded together with the close contact layer20after every processing of the resin film11, which is disadvantageous in terms of cost. In other words, the mask member10bmay be adhered to the process stage35. The reflective film30side of the mask member10bmay be fixed to an appropriate process stage by an adhesive or the like.

Alternatively, when a liquid layer made of ethanol or the like is used as the close contact layer20, for example, the reflective film30may be formed on the process stage35, the liquid layer made of ethanol may be formed on the reflective film30, and a resin film assembly10amay be placed on the liquid layer.

Then, as shown inFIG.2F, opening portions11aare formed in the resin film11. For example, as shown inFIG.7A, when forming the opening portions11a, the resin film11is irradiated with the laser light from its front surface side (a side opposite to the process stage35) via a laser mask41with a desired pattern of optical opening portions41aand the optical lens42, whereby the pattern of the opening portions41aon the laser mask41is scaled down and transferred to the resin film11. This laser light irradiation apparatus and the resin film11are relatively moved using a stepper, so that the pattern of the opening portions11ais sequentially formed in the large resin film11. The optical lens42is not necessarily required, but is effective in increasing an irradiation energy density of a processed surface. In this case, the optical lens42is disposed on the downstream side in the traveling direction of the laser light (on one side of the resin film11) with respect to the laser mask41. The optical lens42is designed to condense the laser light. For example, the use of a 10× optical lens42results in 100-fold energy density, but one side of the pattern is transferred from the laser mask41onto the resin film11on a scale of 1/10. By such irradiation with the laser light, the laser light transmitted through the opening portions41aon the laser mask41sublimes parts of the resin film11. As a result, in conformity with the pattern of the opening portions41aof the laser mask41irradiated with the laser light, the fine pattern of the opening portions11ais formed on the resin film11. This fine pattern in the resin film11is the same as or reduced in size as the pattern on the laser mask41. At this time, in the present invention, the reflective film30is provided on the opposite side of the resin film11to the side facing the laser light source (although omitted inFIG.7A), the laser light transmitted through the parts of the resin film11which become thinner by sublimation is reflected by the reflective film30and then returns back to the resin film11. Eventually, as described above, sublimation progresses from the back surface side of the resin film11as well, thereby preventing a part of the resin from remaining as a burr on the back surface of the resin film11.

As described above, when using the 10× optical lens42, as shown inFIG.7D, the parallel light rays from the laser light source pass through the laser mask41and then through the optical lens (convex lens)42, and are converged onto the resin film11on a scale of 1/10, thereby allowing the resin film11to be irradiated. The light at the center of the laser light is incident on the resin film11almost vertically (at an incident angle of approximately 0°). Meanwhile, an incident angle α of the outermost light ray becomes larger. Here, the incident angle α of the light ray located at the end of the light bundle, which is the largest incident angle, is considered. Assuming that at this time, a is a distance between the optical lens42and the resin film11, b is a length of one side of an optical image formed by the convergent laser light, c is one side of a bundle of the laser light rays before entering the optical lens42, and the laser light is converged to become 1/10 of the original size, for b=4 mm and a=30 mm, the relationship of c=10b=40 mm is given, and consequently, tan α=(c/2−b/2)/a=18/30=0.6. Therefore, α is determined to be 31° (α=31°). This angle is an incident angle of the outermost light ray, and incident angles of other light rays located on the central side become smaller than this incident angle. In addition, since the material of the resin film11has a refractive index n that is greater than a refractive index (approximately 1) of air, when the laser light enter the resin film11, the laser light is reflected to be oriented in the direction closer to the vertical direction relative to the resin film. That is, according to Snell's law, a refraction angle β (seeFIG.7E) satisfies sin β=sin α/n, and when the refractive index n of the resin film11is 1.5, the formula of sin β=sin 31°/1.5 is obtained. Therefore, β is approximately 20°. If a material that has a refractive index larger than that of the resin film11is used for the close contact layer20, the incident angle to a reflecting surface of the close contact layer20becomes smaller. Conversely, if a material that has a refractive index smaller than that of the resin film11is used for the close contact layer20, the incident angle to the reflecting surface of the close contact layer20, which is the same as the reflection angle therefrom, becomes larger, whereby the reflected light reaches a distant position. As the thickness of the close contact layer20increases, a distance d between a position on the front surface of the resin film11where the incident light enters and another position on the front surface of the resin film11where the reflected light returns to reach.

A deviation of the point of the resin film11where the reflected light reaches due to the diagonal incidence will be considered. It is assumed that the refractive index of the close contact layer20is the same as the refractive index of the resin film11for convenience, and the total thickness of the resin film11and the close contact layer20is 10 μm for convenience (which is actually smaller than this). In this case, as shown inFIG.7E, the reflection angle of the reflected light, which is reflected by the reflective film30, is the same as the refraction angle β, and the above-mentioned distance d between the position of the incident light and the position of the reflected light is determined to be d=20 tan β=7.28. That is, for example, assuming that each opening portion is about 30 μm square (opening portions, each of which is 30 μm square, are formed at intervals of 30 μm within an optical image of 4 mm square formed on the resin film11described above), the resin film11is re-irradiated with the reflected light at a position that deviates by approximately 7.28 μm from the opening portion of approximately 30 μm in length per side. This deviation is caused when the incident angle is at the maximum, but is smaller in practice, so the deviation becomes much smaller. Therefore, it is considered that most of the incident light is incident in a state where the incident angle is almost 0°, and the reflected light returns to an area where it does not spread so much. In addition, a slight deviation of the reflected light from the incident light is more advantageous from the viewpoint of re-irradiation from the back surface side. That is, it is considered that the cause of the residual resin is due to the presence of a weak part of the laser light. Thus, when reflected directly above, the weak laser light is reflected as it is, and then the resin film is re-irradiated with the weak light, whereas the light reflected diagonally may have a possibility of a strong laser light, and then the resin film may be re-irradiated with the strong light.

However, as shown inFIG.7F, a collimating lens45is interposed between the optical lens42and the resin film11, so that the laser light can be collimated into substantially parallel light rays, which are incident parallel on the resin film11and reflected parallel by the reflective film30. By adjusting the incident angle relative to the resin film11to 0° in this manner, the light can constantly be reflected directly above as long as the close contact layer20is parallel to the resin film11regardless of the refractive index of the close contact layer20, even if any air layer is interposed therebetween.FIG.7Fis the same asFIG.7Dexcept for the collimating lens45, and thus a description thereof is omitted.

The conditions for irradiation with the laser light are adjusted depending on the materials and thicknesses of the resin films11to be processed, the size and shapes of the opening portions11ato be processed, or the like. However, in general, the irradiation with the laser light is performed under the following conditions: the pulse frequency of the laser light is 1 Hz or more and 60 Hz or less; the pulse width is 1 nanosecond (nsec) or more and 15 nanoseconds or less; and the energy density of the laser light on an irradiation surface per pulse is 0.01 J/cm2or more and 1 J/cm2or less.

For example, in order to form the deposition mask10to be used when depositing organic layers in an organic EL display apparatus, the resin film11made of polyimide is irradiated with the laser light under the conditions below. For example, the resin film11has opening portions of 30 μm square, which are arranged at intervals of approximately 30 μm in a matrix manner. The wavelength of the laser light is 355 nm (which is a third harmonic of YAG laser). The pulse frequency thereof is 60 Hz. The pulse width thereof ranges from several nanoseconds or more and 20 nsec or less. The energy density of the laser light on the irradiated surface is 0.25 J/cm2or more and 0.45 J/cm2or less per pulse. The number of shots (the number of irradiated pules) is 50 and more and 200 or less.

However, the laser light used for the irradiation is not limited to light from a YAG laser. Thus, any other laser may be used as long as it emits a light with a wavelength that can be absorbed in the resin. Therefore, other laser lights, such as an excimer laser, a He—Cd laser and the like may be used. It is needless to say that when the laser light source is changed or the resin material is changed to another, the irradiation conditions are to be modified according to them. In the above-mentioned example, 100 shots of irradiation with the laser light were performed to form the pattern of the opening portions. However, about 100 shots of irradiation can form through holes in a polyimide film having a thickness of 10 μm.

It should be noted that also inFIG.2Fand the subsequent figures, as the opening portion11ais illustrated exaggeratedly to be formed in a tapered shape, a size of the opening portion11a(a size of the opening portion11aon the side of the close contact layer20) is illustrated to be small. However, in practice, the length of one side of the opening portion11ais substantially the same as the distance between the adjacent opening portions11a. The reason why the opening portion11ais formed in a tapered shape is the same as the reason why the opening hole12cof the metal support layer12mentioned above is formed in a tapered shape. Specifically, the reason is that since vapor deposition material evaporated from the vapor deposition source becomes deposition beams having a sector-shaped in cross section with a certain angle, which shape is determined depending on a shape of a crucible of the vapor deposition source, such a tapered opening portion11aenables even the particles of the vapor deposition located at side edges of the deposition beams to be deposited on a desired site of the substrate for vapor deposition without being blocked. In the example shown inFIG.2F, each opening portion11ais formed to have two steps in order to more reliably eliminate the blocking of the particles of the vapor deposition. These two steps are formed in the opening portion11aby performing irradiation with laser light in two sessions. For example, initially, the resin material in the resin film11is sublimed up to approximately a half of a thickness of the resin film11and at an area larger than a desired opening portion. Then, the remaining resin film11is irradiated with the laser light again using a laser mask41having the same size opening pattern as the desired opening portion to form each opening portion11ain the two steps. The opening portion11aof the tapered shape may be obtained by differentiating the transmittance of the laser mask41for the laser light at the center portion of each opening portion41aand at its peripheral portion.

That is, the above-mentioned laser mask41is formed, for example, as follows. As shown inFIG.7B, a light-shielding thin film41bmade of chromium or the like is formed on a transparent substrate that transmits the laser light, such as a quartz glass plate. Thereafter, the light-shielding thin film41bis patterned to form opening portions41a. Consequently, a transmittance of the laser mask41can be partly changed by forming the light-shielding thin films41bin a spot manner, for example, as conceptually shown inFIG.7C. InFIG.7C, each opening portion41ais illustrated to be partitioned into a first section41a1, a second section41a2, and a third section41a3for convenience, but such partitioning is not necessarily performed. The first section41a1transmits 100% of light because the light-shielding thin film41bis not formed in the first section41a1at all. In the second section41a2, the light-shielding thin films41bare sparsely formed, so that an area of the total light-shielding thin films41bis approximately 20% of the entire area of the second section41a2. Consequently, the second section41a2has a transmittance of 80%. Further, the third section41a3is formed so that the amount of the light-shielding thin films41bis approximately 50% of the entire area of the third section41a3in terms of area. Consequently, the third section41a3has a transmittance of approximately 50%. By forming the laser mask41such that its transmittance drastically changes toward its peripheral edge, the taper angle of the opening portion11abecomes larger, whereas by forming the laser mask41such that its transmittance changes moderately, the taper angle of the opening portion11abecomes smaller and thereby the opening portion11ais tapered gradually.

In this example, for easy understanding of the description, the opening portion41ais described as being divided into the first section41a1, the second section41a2, and the third section41a3, and the light-shielding thin films41bare illustrated to be distributed in a plurality of regions in the figure. However, since a transfer resolution of the laser light is actually approximately 2 μm, for example, the opening portion is, in practice, partitioned into 5 by 5 equal segments in the vertical and horizontal orientations, respectively, each segment having 2 μm square, resulting in 25 segments in total. The light-shielding thin film41bis formed in some of all 25 segments, thereby making it possible to adjust the transmittance of the laser light. As such, by continuously reducing the transmittance of the opening portion41atoward its peripheral edge, the tapered opening portion11acan be formed.

That is, the above-mentioned method illustrated inFIG.7Cor adjustment using a projection lens (optical lens42) or the like allows the transmittance of each opening portion41afor the laser light to gradually decrease from its center to peripheral edge. This makes the laser light incident on the resin film11weaker toward the peripheral edge, thus reducing an ability of sublimating the resin film11. Consequently, the amount of the resin film11removed from its front surface side becomes small at its peripheral edge, whereby the opening portion11ais formed in the tapered shape.

Thereafter, the close contact layer20, the reflective film30, and the process stage35are removed as shown inFIG.2G. In this way, the deposition mask10is obtained. When the close contact layer20and the reflective film30are pressed against and fixed firmly to the process stage35, the deposition mask10is separated from the process state35by simply pulling the frame13fixed to the resin film11. If the close contact layer20is made of a resist material, for example, it may be subjected to an ashing process for dissolution of an organic substance contained in the close contact layer20with an asher or the like, or the close contact layer20may be immersed into a resist removing liquid. In this way, the close contact layer20can be removed from the resin film11without any damage to the resin film11. If the close contact layer20is an inorganic dielectric film made of a silicon oxide film or the like, an etchant, such as dilute hydrofluoric acid, which does not erode a resin film, may be used to dissolve and remove the close contact layer20. Consequently, the deposition mask10and the close contact layer20, and the like can be easily separated from each other, thereby producing the deposition mask10. Thereafter, the deposition mask10is put in an organic film cleaning liquid, for example, “OEL Clean-01”, manufactured by KANTO CHEMICAL CO., INC., within an ultrasonic bath and cleaned at a frequency of 80 kHz with a power of 0.5 W/cm2for 10 minutes.

In the above method, deposition masks10were respectively manufactured using PVAC as the close contact layer20and also using the above-mentioned dielectric multilayered reflective films (Example 1) and the above-mentioned metal sheet (Example 2) as the reflective film30, and 2016 opening portions are formed in each of the deposition masks10. The number of burrs formed at these opening portions was checked by observing each of the resin film11from its backside (surface opposite to the surface with the metal support layer12formed thereon) with a microscopy. This observation was performed by photographing42blocks, each block having 6×8 slots (opening portions). The results are summarized in Table 1 in comparison with deposition masks using polyvinyl alcohol (PVA) (Comparative Example 1) and ethanol (Comparative Example 2) as protective layers, each of Comparative Examples having the conventional structure shown inFIG.10. This comparison was made in terms of the number of burrs counted in the same manner as Examples. Furthermore, another comparison between Examples and Comparative Examples with the same structures as mentioned above was made in terms of the number of burrs observed and counted from the side of the metal support layer12. The results are summarized in Table 2. The number of burrs which was observed from a side of the resin film11is different from that observed from a side of the metal support layer12. The reason for the different numbers is considered that foreign particles that had been scattered and attached to the opening portions11aduring the laser processing were not completely removed even with washing and left as burrs.

TABLE 1Status of generation of burrs (observed from resin film side)NumberGenerationof burrsrate (%)Example 1Multilayer50.25reflective filmExample 2Metal sheet80.4ComparativePVA231.1Example 1ComparativeEthanol1366.7Example 2

TABLE 2Status of generation of burrs (observedfrom metal support layer side)NumberGenerationof burrsrate (%)Example 1Multilayer30.15reflective filmsExample 2Metal sheet100.5ComparativePVA251.2Example 1ComparativeEthanol1406.9Example 2

As can be seen apparently from Tables 1 and 2, the forming of the reflective film30contributes to an approximately single-digit improvement in the generation rate of burrs in comparison with the conventional samples.FIG.6is a picture showing a state of the back surface of the resin film11in Example 1. As can be seen from this picture, the surface state is quite different from those inFIGS.9B and9Cmentioned above, which shows that burrs and foreign particles are hardly left in Example 1. It should be noted that laser marks11bshown inFIG.4Aare difficult to find in the picture (seeFIG.4A) to be described later, because each laser mark11bhas a depth of only about 0.3 μm or less (approximately 0.1 μm) and thus is too shallow to emerge in the picture.

According to the embodiment of the present invention, when the opening portions11aare formed in the resin film11, as the reflective film30is formed on the back surface side of the resin film11, thus it contributes to the sublimation of the resin film11by using the reflected light. As a result, burrs that tend to be left on the back surface of the resin film11can be effectively removed. In addition, since the reflected light of the laser light is used, a laser light from the back surface increases the intensity light together with the sublimation of resin from parts of the resin film11, unlike a case of irradiating a back surface of the resin film with laser light from another separate light source. That is, when the resin film11is sublimated or scattered, the transmission light of the laser light becomes large and the reflection light becomes large. As a result, the laser light is irradiated from the back surface side of the resin film11in a state where the resin in the front surface side is reduced, and the sublimated resin is easily emitted from the front surface side. In other words, when the most of the front surface of the resin film11is left, the laser light that strikes the back surface of the resin film11does not facilitate the sublimation of the resin from the front surface. In the embodiment of the present invention, no reflected light is generated when most of the resin is left on the front surface. In this case, most of the laser light is almost absorbed in the resin film11from the front surface and does not reach the reflective film30. In short, the laser light strikes the back surface of the resin film11only at a necessary timing. This effectively removes unnecessary burrs.

Next, with reference toFIGS.3A to3D, a description will be given below of a method of manufacturing a deposition mask according to another embodiment of the present invention. In this embodiment, the order of forming films is opposite to that in the foregoing embodiment. More specifically, as illustrated inFIG.3A, a resin film11is formed on a metal foil12d, which will be used as a metal support layer12. The resin film11may be formed by applying a liquid resin to the metal foil12dand heating and solidifying the liquid resin, similar to the foregoing embodiment, or by bonding a solidified film sheet to the metal foil12d. This process can form, in a short time, an assembly in which the resin film11is in contact with the metal foil12dwithout using plating.

As illustrated inFIG.3B, the metal foil12dis patterned, and then the resin film11is expanded and fixed to a frame13. The reasons why the metal foil12dis patterned and the resin film11is expanded are the same as those described in the foregoing embodiment. The material for the frame13may be the same as that used in the foregoing embodiment.

As illustrated inFIG.3C, a close contact layer20is formed on the resin film11. The close contact layer20may be formed of an inorganic dielectric layer or other film that is easily separable from the resin film11by a CVD method or the like, for example, similar to the foregoing embodiment.

As illustrated inFIG.3D, a reflective film30is formed on the close contact layer20by a CVD method or the like. The reflective film30may have the same structure as that described inFIG.5. First, multilayer films32(seeFIG.5) are formed, and then an aluminum single-crystal film31is formed. In this way, a mask member10bfor a deposition mask10is obtained, as illustrated inFIG.3D. In this example, as described above, the assembly illustrated inFIG.3B or3Cmay be stacked on the reflective film30or the close contact layer20that has already been formed on a process stage35, thereby forming the mask member10b.

As illustrated inFIG.2E, the reflective film30of the mask member10bis fixed to the process stage35, thereafter. This fixing is performed using an adhesive agent or with another method by which the reflective film30is fixed to the process stage35to an extent that the reflective film30does not move. Then, as illustrated inFIGS.2F to2G, a pattern of opening portions11ais formed in the resin film11with laser light. After that, the close contact layer20is removed from the resin film11so that the resin film11is separated from the process stage35or the like. In this way, the deposition mask10is obtained.

FIG.4Aillustrates a cross section of the deposition mask10manufactured by the above method. This structure is substantially the same as that illustrated inFIG.2G, butFIG.4Aillustrates the structure in more detail. More specifically, in the deposition mask10according to this embodiment of the present invention, as described above, the reflective film30(seeFIG.2F) is formed on the surface opposite to the surface of the resin film11on the side of a laser light source. When the light source irradiates the laser light, this laser light passes through the resin film11, and then is reflected by the reflective film30. This reflected light is absorbed in the resin left in the opening portions11a, facilitating sublimation of this resin. However, as described above, laser light which has entered the resin film11vertically (at an incident angle of 0°) is reflected substantially vertically. However, some laser light enters the resin film11at given angles other than 0°. This laser light is reflected diagonally by the reflective film30and may travel to the outside of the opening portion-formation region. Such laser light might strike a region on the back surface of the resin film11other than the opening portion-formation region. As a result, laser marks11bare formed on the back surface of the resin film11as laser-light-irradiation signs. The depth of these laser marks11bis approximately 0.1 μm, or 0.5 μm or less at most. In other words, the depth of the laser marks11branges from approximately 0.1 or more to 0.5 μm or less. Thus, the laser marks11bare less likely to affect the mechanical strength of the resin film11whose thickness is 5 μm or more. Moreover, as described above, the laser light from the light source is incident on the resin film11at an incident angle of approximately 30° or less. Then, the angle of refraction of which the laser light enters the resin film11having a greater refractive index has an angle of approximately 20° or less. If the close contact layer20has a greater refractive index than that of the resin film11, the angle of refraction further decreases and the angle of reflection also further decreases. The reflected light is returned to within a limited, small region. As a result, the reflected light generated by the reflective film30does not spread out so widely, thus creating the laser marks11bonly around the opening portions11a.

The laser marks11bcreated in the above manner are less likely to decrease the mechanical strength of the resin film11, as described above. Rather, the laser marks11bare expected to effectively enhance the heat radiation of the resin film11by making its back surface uneven to increase the surface area. When the deposition mask10is used, a lower surface of the deposition mask10illustrated inFIG.4A, namely, the back surface of the resin film11is fixed to the substrate for vapor deposition, whereas the metal support layer12of the deposition mask10faces a crucible of a vapor deposition source. In this case, since the vapor deposition material flies toward the deposition mask10, the deposition mask10is exposed to high temperatures due to heat radiated from the vapor deposition source and greatly heated accordingly. When the temperature of the deposition mask10increases, the resin film11is expanded and the opening portions11aare enlarged. As a result, the vapor deposition material may be deposited within a larger area than an intended area. If an organic EL display apparatus is manufactured with the deposition mask10formed in this manner, its pixel sizes may differ from one another, causing a lowered display quality. For this reason, it is not preferable that the temperature of the deposition mask10does not increase excessively. In view of the above, the surface of the deposition mask10which faces the vapor deposition source, namely, the upper surface illustrated inFIG.4Ais preferably a mirror surface that has a low heat radiation coefficient so as not to absorb heat from the vapor deposition source. However, the opposite surface of the deposition mask10preferably dissipates absorbed heat and has a great heat radiation coefficient. For this reason, the laser marks11bthat make the surface of the deposition mask10uneven contributes to enhancement of the heat radiation.

To further facilitate the heat radiation, the back surface of the resin film11is coated with a high-heat-radiation film14having a great heat radiation coefficient, as illustrated inFIG.4B. The high-heat-radiation film14may be made of Al2O3, AlTiN, or graphite, for example, and formed with a sputtering, vacuum deposition, CVD method, or the like. For example, the high-heat-radiation film14may have a thickness of approximately several hundreds of nanometers. Among these processes, especially the sputtering process is preferred, because the sputtering process allows the high-heat-radiation film14to be formed in good contact with the resin film11, which contributes to the heat radiation. Moreover, because of its considerably small thickness, the high-heat-radiation film14allows the laser mark11bformed on the back surface of the resin film11to emerge on a back surface of the high-heat-radiation film14with its shape unchanged, thereby successfully forming projections and dents14b.

Next, a description will be given of a method of manufacturing an organic EL display apparatus by using the deposition mask10having the resin film manufactured in the above manner. Aside from the method of manufacturing the deposition mask10, processes in the manufacturing method may be well-known processes. Thus, a description that will be given below with reference toFIGS.8A to8Bis focused on a method of depositing organic layers by using the deposition mask10.

In the method of manufacturing an organic EL display apparatus of the present invention, unillustrated TFTs, a planarizing layers, and a first electrode (for example, anodes)52are formed on an unillustrated support substrate. A device substrate51is thereby formed. The deposition mask10manufactured by the above method is overlaid and aligned on the device substrate51. By depositing organic materials54on the device substrate51, an organic deposition layer55formed of organic materials54is formed. And a second electrode (cathode)56is formed on the organic deposition layer55.

The device substrate51may be formed in the following process. For example, although not illustrated completely, switching elements such as the TFTs are formed on the support substrate made of a glass plate, for example, in units of RGB sub-pixels in each pixel. The first electrode52connected to the switching element is formed on the planarizing layer by a combination of a metal film made of Ag, APC, or the like, and an ITO film, for example. As illustrated inFIGS.8A and8B, insulating bank53may be made of SiO2, plastic, or the like, is formed between sub-pixels to divide these sub-pixels from each other. The above deposition mask10is aligned and fixed on the insulating banks53of the device substrate51. This fixing may be performed by attracting the deposition mask10to a magnet, for example, disposed on the opposite side of the device substrate51. The opening portion11ain the deposition mask10is formed so as to be smaller than a gap between opposed walls each other, of the insulating bank53. Therefore, the organic material54is suppressed from depositing to side wall of the insulating bank53, thereby preventing lowered light emitting efficiency.

In this state, as illustrated inFIG.8A, a vapor deposition source (crucible)60in a vapor deposition apparatus evaporates the organic material54. Then, the organic material54is deposited only on parts of the device substrate51exposed from the opening portions11aof the deposition mask10. In this way, the organic deposition layer55is formed on the first electrodes52in desired sub-pixels. As described above, the opening portions11ain the deposition mask10is formed so as to be smaller than a gap between opposed walls each other, of the insulating bank53. Therefore, the organic material54is suppressed from depositing to side wall of the insulating bank53. As a result, as illustrated inFIGS.8A and8B, the organic deposition layer55is deposited substantially only on the first electrodes52. This vapor deposition step may be performed on each sub-pixel by sequentially replacing one deposition mask with another. Alternatively, a deposition mask may be used to deposit the same material on a plurality of sub-pixels at one time.

FIGS.8A and8Beach simply illustrate the organic deposition layer55by a single layer, but in fact the organic deposition layer55may be formed of the deposition layers55of a plurality of layers made of different materials. For example, a hole injection layer is provided as a layer in contact with the anode52in some cases. The hole injection layer improves a hole injection property and is made of material having a good ionization energy matching. A hole transport layer is formed of, for example, an amine-based material on the hole injection layer. The hole transport layer improves stable transportability of holes and enables confinement of electrons (energy barrier) into a light emitting layer. Further, the light emitting layer, which is selected depending on a target emission wavelength, is formed on the hole transport layer, for example, by doping red or green organic phosphor material into Alq3, for the red or green wavelength. As a blue-type material, a bis(styryl)amine (DSA)-based organic material is used. An electron transport layer is formed of Alq3, for example, on the light emitting layer. The electron transport layer improves an electron injection property and stably transports electrons. These respective layers, each having a thickness of approximately several tens of nanometers, are deposited to form the organic deposition layer55. It should be noted that an electron injection layer, such as LiF or Liq, which improves the electron injection property, may also be provided between the organic layers and the metal electrode.

In the organic deposition layer55, an organic layer of a material corresponding to each color of RGB is deposited as the light emitting layer. In addition, the hole transport layer, the electron transport layer, and other similar layers are preferably deposited separately by using materials suitable for the light emitting layer, if emphasis is placed on light emission performance. However, in consideration of the material cost, the same material common to two or three colors of RGB may be deposited in some cases. In a case where the material common to sub-pixels of two or more colors is deposited, the deposition mask is formed to have opening portions formed in the sub-pixels sharing the common material. In a case where individual sub-pixels have different deposited layers, for example, one deposition mask10is used for sub-pixels of R, so that the respective organic layers can be sequentially deposited. In a case where an organic layer common to RGB is deposited, other organic layers for the respective sub-pixels are deposited up to the lower side of the common layer, and then at the stage of the common organic layer, the common organic layer is deposited across the entire pixels at one time using the deposition mask1with the opening sections formed at RGB sites.

After finishing the formation of all the organic layers of the organic deposition layer55and the electron injection layer, such as a LiF layer, the deposition mask10is removed, and then a second electrode (e.g., cathode)56is formed over the entire surface. An example illustrated inFIG.8Bis a top emission type, in which light is emitted from a top side in the figure. Thus, the second electrode56may be formed of a light-transmissive material, for example, a thin Mg—Ag eutectic layer. Alternatively, for example, Al may be used. It should be noted that in a bottom emission type which emits light from a side of the device substrate51, ITO or In3O4, for example, may be used for the first electrodes52, and metals having low work functions, for example, Mg, K, Li, or Al may be used for the second electrode56. A protective layer57made of, for example, Si3N4, is formed on a surface of the second electrode56. It should be noted that the whole deposited layers are sealed with a sealing layer made of glass or a moisture-resistant resin film (not illustrated), for example, and is thus configured to prevent the organic deposition layer55from absorbing moisture. Alternatively, a structure can also be provided in which the organic layers may be made common or shared as much as possible, and a color filter may be provided on the surface side of the organic layers.

REFERENCE SIGNS LIST

10Deposition mask10aResin film assembly10bMask member11Resin film11aOpening portion11bLaser mark12Metal support layer12aSeed layer12bMetal film12cOpening hole13Frame14High-heat-radiation film14bprojections and dents20Close contact layer30Reflective film31Aluminum single-crystal film32Multilayer films35Process stage36Support substrate41Laser mask41aOpening portion41bLight-shielding thin film42Optical lens45Collimating lens51Device substrate52First electrode53Insulating bank54Organic material55Organic deposition layer56Second electrode57Protective layer