JP2008184670A - Method for producing organic el element, and mask for film deposition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To control the region where a glass substrate and a mask are made in contact with each other at first, and to suppress misalignment in a stage where the glass substrate and the mask are made in close contact with each other. <P>SOLUTION: The mask 1 is provided with: a mask part 3 having a pattern composed of a plurality of vapor through-holes for mask film-deposition on a glass substrate 10; and a frame 2 for fixing and supporting the mask part 3. On the face side confronted with the glass substrate 10 in the mask 1, a pair of recesses 4 are formed so as to be located in the central part of an external frame part 2b along the outer circumference of the mask part 3. A pair of the recesses 4, in a stage where the mask 1 and the glass substrate 10 are tightly stuck, prevents the phenomenon that both the end parts of the glass substrate 10 bent by gravity 9 interfere the external frame part 2b, and misalignment is generated. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an organic EL element manufacturing method and a film formation mask for manufacturing an organic EL element of an organic EL (electroluminescence) device.

  Conventionally, in a method for manufacturing an organic EL element, a mask film forming method in which a film forming mask is adhered to a glass substrate to form a film is often employed. A mask vapor deposition method which is an example of such a mask film forming method can form an organic EL layer pattern with high accuracy. In recent years, patterning miniaturization has progressed with the increase in resolution of organic EL panels. For this reason, the quality deteriorates due to a slight geometric misalignment between the pixel pattern and the mask pattern on the glass substrate.

Patent Document 1 proposes a method of performing alignment by supporting each side of three or more sides of a substrate for the purpose of accurately aligning a glass substrate (substrate) and a mask. By this method, the bending of the glass substrate can be suppressed, and the alignment can be suitably performed.
JP 2003-17258 A

  In the alignment method disclosed in Patent Document 1, the glass substrate and the mask are brought into close contact after alignment is performed in a state where both the glass substrate and the mask are bent. Since it is difficult to control the bending shape of the glass substrate and the mask, it is difficult to control the region where the glass substrate and the mask first contact in the step of closely contacting the glass substrate and the mask. Therefore, after the glass substrate and the mask are aligned, geometric displacement may occur in the step of bringing the glass substrate and the mask alignment mark into close contact with each other.

  When placing the mask on a flat table to make it flat, and supporting the two sides of the glass substrate and aligning them at a position symmetrical to the center of gravity of the glass substrate, the area of the glass substrate that is most bent in the adhesion process Comes into contact with the mask first. The glass substrate has a shape in which a straight region passing through the center of gravity parallel to the two sides to be supported is greatly bent, and both ends of the straight region are most bent. Therefore, only a small area at both ends on a straight line passing through the center of gravity of the glass substrate first comes into contact with the mask. A slight difference in frictional force between the mask and the glass substrate in this region may cause a geometric misalignment between the mask and the glass substrate.

  An object of the present invention is to provide an organic EL element manufacturing method and a film formation mask capable of forming a high-quality organic EL element with high pattern accuracy using a film formation mask that is in close contact with a substrate. It is what.

  The film formation mask of the present invention is a film formation mask comprising: a mask portion having a pattern for forming a mask film in close contact with a substrate; and a frame that supports the mask portion. A pair of dents that have two sides facing each other at both ends of the mask portion and that are respectively positioned at the center portions of the two opposite sides of the frame are formed on the surface side where the film formation mask is in close contact with the substrate. It is characterized by that.

  The organic EL device manufacturing method of the present invention includes an alignment step of aligning a film forming mask having a mask part having a pattern and a frame that supports the mask part and a substrate, and the aligned film forming element. A step of bringing the mask and the substrate into close contact with each other, and a step of forming an organic EL layer through the film formation mask attached to the substrate, wherein the frame is mutually attached at both ends of the mask portion. And a pair of dents that are respectively located at the center of the two opposite sides of the frame are formed on the surface of the film forming mask that is in close contact with the substrate. .

  The position shift due to the interference between the frame of the film formation mask and the substrate can be reduced in the step of bringing the substrate and the film formation mask into close contact with each other without substantially changing the size and weight of the film formation mask. By using such a film-formation mask, an organic EL element having an organic EL layer which is a thin film pattern with a small dimensional accuracy and a small geometrical deviation from a pixel pattern arranged on a glass substrate is manufactured. It becomes possible to do.

  When positioning the film deposition mask in a flat state and supporting the two sides of the substrate at positions symmetrical to the deflection center of gravity of the substrate, the recesses provided in the film deposition mask are the bent portions at both ends of the substrate. First, it plays a role not to contact the frame of the mask. If the depth of the dent is at least the difference in deflection of the substrate in that area, most of the area on the straight line passing through the center of gravity of the substrate will be in contact first, so the position shift in the contact process between the substrate and the deposition mask Can be suppressed.

  Further, by providing a recess on the extended line of the straight line connecting the alignment marks, the first contact position becomes closer to the alignment marks. Therefore, since the area in the vicinity of the alignment mark between the substrate and the film formation mask comes into contact first, the positional deviation between the substrate and the film formation mask from the alignment until the alignment marks come into contact with each other is reduced. can do.

  In a square frame, it is preferable to form a dent in the center of the shorter two sides of the two sets of two sides having different lengths. In the case of supporting the long side of the substrate, it is possible to avoid the bending of both end portions of the substrate, that is, the central portion of the short side, from first contacting the deposition mask by the recess of the frame. In this case, since the long side of the substrate is supported, the deflection of the entire substrate when supported becomes small, and the positional deviation between the substrate and the film formation mask is less likely to occur in the adhesion process.

  The best mode for carrying out the present invention will be described with reference to the drawings.

  1 to 4 show a film formation mask (evaporation mask) according to an embodiment. (A) of each figure is sectional drawing which shows the mask 1 which is a film-forming mask, (b) is a top view which shows the mask 1 seen from the surface side closely_contact | adhered with the glass substrate 10 which is a board | substrate.

  The mask 1 has a frame 2 and a mask portion 3, and the frame 2 is fixedly supported with tension applied to the mask portion 3. The mask unit 3 has a pattern (mask pattern) composed of a plurality of vapor passage holes for mask vapor deposition. For the purpose of bringing the glass substrate 10 and the mask portion 3 of the mask 1 into close contact with each other during vapor deposition, the mask portion 3 is fixedly supported by the frame 2 in a state where tension is applied, and the bending of the mask portion 3 is suppressed.

For the mask portion 3, a member such as copper, nickel, and stainless steel can be used. Alternatively, the mask portion 3 may be formed by electroforming using a nickel alloy such as nickel, a nickel-cobalt alloy, an invar material that is a nickel-iron alloy, or a super invar material that is a nickel-iron-cobalt alloy. In particular, since the coefficient of thermal expansion of Invar material and Super Invar material is 1-2 × 10 ⁻⁶ / ° C., which is smaller than that of other metals, it is possible to suppress deformation of the mask due to thermal expansion during vapor deposition.

  The frame 2 has a large rigidity for fixing and supporting the mask portion 3 in a state where a tension is applied, and has a sufficient thickness and width to impart the rigidity. As shown in FIGS. 1, 3, and 4, the mask portion 3 is divided by the inner frame portion 2 a and is surrounded by the outer frame portion 2 b that is two sides facing each other at both ends of the mask portion 3. Alternatively, as shown in FIG. 2 (b), a plurality of patterns are provided in one mask portion 3, and two sets of rectangular frames 2 having two opposite sides with different lengths are used. Also good.

  In the configuration in which the inner frame portion 2a that divides the mask portion 3 as shown in FIG. 1 is provided, the rigidity of the mask 1 is improved, so that the effect of improving the accuracy of the pixel arrangement of the pattern is obtained. In this case, it is particularly preferable to increase the rigidity of the outermost outer frame portion 2b, but this is not limited as long as the pattern accuracy of the mask portion 3 can be maintained.

  The frame 2 can be made of a material having a low thermal expansion coefficient such as an invar material that is a nickel-iron alloy or a super invar material that is a nickel-iron-cobalt alloy. By using a material having a low expansion coefficient for the frame 2, the effect of suppressing deformation of the mask due to thermal expansion can be obtained in the same manner as when used for the mask portion 3.

  In the present embodiment, the definition of a support region when two opposing sides of the glass substrate 10 are used as a substrate support will be described. Here, to support two sides of the substrate means to support at least one continuous region including the vessel point on one side or both sides sandwiching the vessel point. Further, the support region may be supported symmetrically with respect to the midpoint of the supported side, and the entire region of the side may be supported.

FIG. 5 is a diagram for explaining bending that occurs when the glass substrate 10 to be in close contact with the mask 1 is supported by two opposing sides. The center of gravity of the glass substrate 10 is defined as point A, and points located on the substrate edge on the straight line BB passing through the point A and parallel to the pair of substrate support portions 11 are defined as B ₁ and B ₂ . When supporting the substrate support part 11 which is two opposing sides of the glass substrate 10, the amount of bending in the region on the BB line at the center of the substrate becomes the largest, and the amount of bending becomes smaller toward the substrate supporting part 11.

FIG. 6 is a graph showing a difference in deflection amount from point A to points B ₁ and B ₂ when a glass substrate having a size of 500 mm × 400 mm is supported by two long sides as an example for explaining the deflection. And represents the amount of deflection when the point A is used as a reference. The amount of deflection was calculated using arithmetic processing by a finite element method which is a known technique. As shown in FIG. 6, although it is a slight difference of several tens of μm, the amount of bending becomes the largest in the region along the line B-B, and in the whole glass substrate 10, points B ₁ that are both ends of the substrate center B ₂ is most bent.

  Therefore, as shown in FIGS. 1 to 4, a pair of dents 4 are formed in the center part of the two sides of the frame 2 facing each other on the side close to the glass substrate 10. In the cross-sectional views shown in FIGS. 1 to 4A, in order to make the relationship between the bent shape of both ends of the glass substrate 10 and the recess 4 of the mask 1 easier to understand, the bent shapes of both ends of the glass substrate 10 are The size of the depth H of the dent 4 is highlighted.

  By providing the pair of recesses 4 in the frame 2, it becomes possible to prevent the bending of both end portions of the glass substrate 10 from first contacting the frame 2 of the mask 1, and to suppress displacement in the contact process. It becomes possible. The depth H of the dent 4 may be designed so that both ends of the glass substrate 10 do not first contact the mask 1, and at least if the depth H of the dent 4 is greater than or equal to the deflection difference between the both ends of the glass substrate 10. Good. Moreover, as long as the dimensional accuracy of the mask portion 3 is not adversely affected, a hole may be formed in a part or all of the recess 4 to replace the opening. However, in order to suppress the influence on the dimensional accuracy of the pattern of the mask 1 as much as possible, it is preferable that the depth H of the recess 4 is slightly larger than the deflection difference between both ends of the glass substrate 10.

  What is necessary is just to design the shape and the position of the dent 4 according to the bending amount of both ends of the glass substrate 10, a bending shape, and the size of the glass substrate itself.

  For example, as shown in FIG. 3, when the glass substrate 10 is smaller than the size of the mask 1, the dent 4 may be formed closer to the center of the mask 1 according to the shape of the glass substrate 10. Similarly, the shape of the recess 4 can be changed.

  Further, as shown in FIG. 4, a dent 4 may be provided on an extended line of the straight line LL connecting the alignment marks 5. As a result, the first contact position is closer to the alignment mark 5, and the vicinity of the alignment mark 5 on the glass substrate 10 and the mask 1 is first contacted. As a result, it is possible to reduce the positional deviation between the glass substrate 10 and the mask 1 until the alignment marks are brought into close contact with each other.

  Moreover, it is preferable to provide the dent 4 in the central part of the shorter two sides of two sets of two opposite sides having different lengths of the mask 1. When supporting the long side of the glass substrate 10, it is possible to avoid the bending of the central portion of the short side of the glass substrate 10 from first contacting the mask 1 by the recess 4 of the mask 1. In this case, since the long side of the glass substrate 10 is supported, the deflection of the entire glass substrate when supported is reduced, and the positional displacement between the glass substrate 10 and the mask 1 is less likely to occur in the adhesion process. In addition, when the size of the glass substrate 10 is large, the glass substrate 10 may be bent too much and the glass substrate 10 may be broken or broken. A method of supporting 10 long sides is desirable.

  FIG. 7 is a view showing a mask 101 and a glass substrate 110 in which no recess is formed for comparison. Since no dent is formed in the frame 102 that supports the mask portion 103, the bent regions of both end portions of the glass substrate 110 first come into contact with the mask 101 in the step of closely attaching the glass substrate 110 and the mask 101. Therefore, a slight positional difference between the mask 101 and the glass substrate 110 may cause a geometric displacement between the mask 101 and the glass substrate 110.

  Next, a method for manufacturing the mask 1 will be described.

First, the mask part 3 and the frame 2 are produced. The mask part 3 is produced by using means such as etching, laser processing, or electroforming on a thin plate of metal or alloy. The frame 2 is manufactured by laser processing or machining a metal or alloy.
Next, the mask portion 3 and the frame 2 are fixedly and integrally joined to each other through an electrodeposited metal layer or the like, thereby fixing the mask portion 3 to the frame 2.

  When forming a mask portion 3 having a plurality of patterns as shown in FIG. 2, the periphery of the mask portion 3 is pulled outward by a clamp or the like, and tension is applied to the mask portion 3 so as to satisfy a desired dimensional accuracy. However, the mask portion 3 may be in a state without distortion. In this state, the peripheral part of the mask part 3 and the frame 2 are fixed by spot welding or the like. By such a method, the mask portion 3 can be fixed to the frame 2.

  To form the recess 4 in the frame 2, laser processing, machining, chemical etching, or the like can be used, but it is possible to form a recess with a desired position, shape, and depth. It is not limited to this. The order in which the mask portion 3 and the recess 4 are fixed and formed on the frame 2 is not particularly limited as long as the pattern accuracy of the mask portion 3 is guaranteed.

  Examples will be described below by taking an evaporation mask, which is a film formation mask, as an example.

  A non-alkali glass 0.7 mm thick substrate was used as the glass substrate. Thin film transistors, electrode wirings, and pixel electrodes are formed in a matrix on this substrate by a conventional method.

  First, the mask for vapor deposition was spot-welded to a 10 mm thick frame made of super invar material with a 50 μm thick mask portion made of super invar material to which tension was applied while adjusting the pattern accuracy. In the mask part, a total of 42 patterns of 40 mm × 50 mm, 6 × 7 in a matrix, were arranged symmetrically. Next, a recess having a depth of about 100 μm is formed in a semicircular shape having a radius of 15 mm in the vicinity of the center of the two short sides of the frame by chemical etching. In this way, a vapor deposition mask was produced, and an alignment mark with a glass substrate was formed on the frame in a region 1 mm away from the recess toward the mask center.

  The vapor deposition mask was placed so as to be flat on a smooth base, and the glass substrate was brought close to the vapor deposition mask while supporting a region (substrate support portion) on the opposite long side of the glass substrate from above. Next, alignment is performed so that the vapor passage hole in the mask portion of the evaporation mask matches the pixel pattern on the glass substrate, and the glass substrate is brought closer to the evaporation mask and brought into close contact with each other to form an organic EL layer. Filmed.

  In the vapor deposition mask of this embodiment, it becomes possible to prevent the bending of both ends of the glass substrate from coming into contact with the frame of the mask at the beginning of the adhesion process. It was possible to suppress the displacement of the pixel pattern. By vacuum deposition using a known luminescent material, it becomes possible to form (deposit) an organic EL layer that is a thin film pattern with good dimensional accuracy on a glass substrate, and an organic EL element without display unevenness is obtained. It was.

(Comparative example)
A non-alkali glass 0.7 mm thick substrate was used as the glass substrate. Thin film transistors, electrode wirings, and pixel electrodes are formed in a matrix on this substrate by a conventional method. First, the mask for vapor deposition was spot-welded to a 10 mm thick frame made of super invar material with a 50 μm thick mask portion made of super invar material to which tension was applied while adjusting the pattern portion accuracy. In the mask part, a total of 42 patterns of 40 mm x 50 mm, 6x7 in total, are arranged in a matrix, and the alignment mark with the glass substrate is formed at the same position as in the embodiment on the frame. did.

  This vapor deposition mask was placed flat on a flat table, and the glass substrate was brought close to the vapor deposition mask while supporting the region on the long side of the glass substrate from above. Next, alignment was performed so that the pattern of the evaporation mask coincided with the pixel pattern on the glass substrate, and the glass substrate was brought closer to the evaporation mask and brought into close contact slowly.

  In this vapor deposition mask configuration, the deflection of both ends of the glass substrate comes into contact with the mask frame at the beginning of the adhesion process, so it is difficult to suppress misalignment between the mask pattern and the pixel pattern on the glass substrate. It was. When vacuum deposition was performed using a known light-emitting material, a pattern shift occurred in the organic EL layer formed on the glass substrate, and display unevenness occurred in the obtained organic EL element.

  The film-forming mask of the present invention is not limited to the manufacturing process of the organic EL element, and can be widely applied to other vapor deposition processes and CVD processes that require high-precision alignment with a glass substrate or the like.

An embodiment is shown, (a) is a schematic cross-sectional view showing a mask and a glass substrate, and (b) is a plan view showing only the mask. It shows a modification, (a) is a schematic cross-sectional view showing a mask and a glass substrate, (b) is a plan view showing only the mask. It shows another modification, (a) is a schematic cross-sectional view showing a mask and a glass substrate, (b) is a plan view showing only the mask. Furthermore, another modification is shown, (a) is a schematic cross-sectional view showing a mask and a glass substrate, (b) is a plan view showing only the mask. It is a top view for demonstrating the bending which arises in a glass substrate. It is a graph which shows the result of having measured the amount of bending which arises in a glass substrate. It is a figure explaining a comparative example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mask 2 Frame 3 Mask part 4 Recess 5 Alignment mark 10 Glass substrate 11 Substrate support part

Claims (5)

In a film formation mask comprising a mask portion having a pattern for forming a mask film in close contact with a substrate, and a frame that supports the mask portion,
The frame has two sides facing each other at both ends of the mask portion, and the film formation mask is located on the surface side in close contact with the substrate, at the center of the two opposite sides of the frame. A film-forming mask characterized by forming a pair of recesses.   2. The film formation mask according to claim 1, wherein the recess is formed on a linear extension line connecting alignment marks for aligning the substrate and the film formation mask.   3. The structure according to claim 1, wherein the frame has two sets of two opposite sides having different lengths, and the pair of dents are formed at the central portions of the two shorter sides, respectively. Mask for membrane.   The film-forming mask according to claim 1, wherein the film-forming mask is a vapor deposition mask. An alignment step of aligning a substrate and a film formation mask including a mask portion having a pattern and a frame supporting the mask portion;
Adhering the aligned film-forming mask and the substrate;
Forming an organic EL layer through the film-formation mask adhered to the substrate,
The frame has two sides facing each other at both ends of the mask portion, and the film formation mask is located on the surface side in close contact with the substrate, at the center of the two opposite sides of the frame. A method of manufacturing an organic EL element, wherein a pair of recesses is formed.

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