JP2011071013A - Apparatus and method for manufacturing functional layer of organic el device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress variations of a coating shape arranged on the whole substrate, and homogenize the coating shape when forming a coated film by a wet method including a functional layer of an organic EL element on a substrate. <P>SOLUTION: In a drying device 20, the substrate 1 into which ink is filled is placed on a support base 22 installed inside a reduced pressure vessel 21. A rectifying member 50 is arranged upward the substrate 1. A plurality of slits 53 to circulate solvent vapor are juxtaposed in the rectifying member 50. A plate like mesh member 40 is deployed at the lower face of the rectifying member 50 so as to cover inlets of respective slits 53. A plurality of through-holes 41 are opened and installed to the respective slits 53 in the mesh member 40, respectively. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention mainly relates to a method of forming a thin film for an element, including a functional layer of an organic electroluminescence element (hereinafter referred to as “organic EL element”).

2. Description of the Related Art In recent years, an organic EL element that has been researched and developed is a light-emitting element that utilizes an electroluminescence phenomenon of an organic material, and has a structure in which a light-emitting layer is interposed between an anode and a cathode.
In an organic EL display, the light emitting layer is generally partitioned by a bank made of an insulating material for each element, and the arrangement position and shape of the light emitting layer are defined by this bank. In addition, for example, a hole injection layer, a hole transport layer, or a hole injection / transport layer is interposed between the anode and the light emitting layer, and between the cathode and the light emitting layer, if necessary. An electron injection layer, an electron transport layer, or an electron injection / transport layer is interposed (hereinafter collectively referred to as a hole injection layer, a hole transport layer, a hole injection / transport layer, an electron injection layer, an electron transport layer, and an electron injection / transport layer) In addition, the light emitting layer and the charge injecting and transporting layer perform specific functions such as light emission and charge injecting and transporting, and these layers are collectively referred to as “functional layer”. That said.)

In an organic EL display for full color display, such organic EL elements correspond to RGB sub-pixels, and one pixel is formed by combining adjacent RGB sub-pixels, and the pixels are arranged in a matrix. An image display area is formed.
When manufacturing an organic EL display, there is a step of forming a functional layer of an EL element on a substrate. In this functional layer forming process, a method of forming a low molecular material by a vacuum process is also used. However, an ink (coating liquid) in which a material for forming a functional layer is dissolved in a solvent is applied by an inkjet method or the like. A wet system is often used that fills between banks and dries the filled ink. According to this wet method, a functional layer can be formed relatively easily even in a large panel.

By the way, in the organic EL display, it is required to obtain uniform light emission characteristics for each element. However, since the light emission characteristics of the organic EL element are sensitive to the film thickness of the functional layer, the functional layer is formed by a wet method. Therefore, it is required to fill each element formation scheduled region with a certain amount of ink, and to eliminate the variation in the thickness of the functional layer in each element region, and to form the functional layer flatly.
Therefore, when the functional layers of the plurality of EL elements are formed on the substrate, a solvent having a relatively high boiling point is used so that each element formation scheduled region is filled with an equal amount of ink. When the filled ink is dried, the substrate filled with the ink is dried under reduced pressure in a dryer in order to evaporate the solvent having a high boiling point.

JP 2008-218253 A

  However, when the functional layer is formed by filling the ink on the substrate and drying under reduced pressure as described above, a problem arises because the atmosphere at the time of drying the ink is different between the central portion of the substrate and the end portion of the substrate. That is, in general, in the ink liquid reservoir filled in the substrate edge, the solvent is more likely to evaporate near the substrate edge than near the substrate center. It flows to the end side and drying proceeds in a biased state. Thereby, the film thickness of the coating film tends to be larger on the substrate end side of the functional layer to be formed. As a result, the functional layer of the element formed at the center of the substrate and the functional layer of the element formed at the edge of the substrate tend to have different shapes.

Thus, if the shape of the functional layer is different between the element at the center of the substrate and the element at the edge of the substrate, the characteristics of the functional layers are also different from each other, leading to deterioration in image quality in the organic EL display.
In order to solve such a problem, Patent Document 1 discloses a technique of providing a rectifying member having a plurality of slits on the substrate in order to rectify the solvent vapor flowing upward in the drying chamber. If it is dried using this apparatus, it can be expected that the film shape of the functional layer in which vapor is formed at the central portion and the end portion of the substrate can be made uniform to some extent as a whole.

However, in reality, when steam flows into each slit, the steam flow is likely to be turbulent, and the turbulent steam flow at the slit inlet causes the solvent to evaporate from each ink reservoir in the area corresponding to each slit. As a result, variations occur in the shape of the functional layer formed for each element.
In view of the above problems, the present invention suppresses variations in the shape of the coating film disposed on the entire substrate when a coating film is formed on the substrate by using a wet method including the functional layer of the organic EL element. The purpose is to make the coating film shape uniform.

    In order to solve the above-described problem, a coating liquid that is one embodiment of the present invention, includes a decompression container capable of decompressing the interior, and a decompression pump that exhausts the interior of the decompression container, and is filled in the upper surface of the substrate in the decompression container In the manufacturing apparatus for forming the functional layer of the organic EL element by evaporating the solvent contained in the rectifier, a rectifying member in which a plurality of slits for circulating the solvent vapor are arranged in parallel in the decompression vessel is provided at the entrance of each slit. A mesh member having a plurality of through-holes narrower than the slits is disposed so as to cover the inlets of the slits of the rectifying member. It was.

When the solvent contained in the coating liquid filled on the upper surface of the substrate is evaporated in the vacuum container using the manufacturing apparatus according to the above aspect, the solvent vapor evaporated from each region on the upper surface of the substrate is arranged in parallel with the rectifying member. Since each slit is distributed, the evaporation rate of the solvent is made uniform throughout the substrate, and the film shape of the functional layer is made uniform.
Further, a mesh member is disposed so as to cover the entrance of each slit, and a mesh member having a plurality of through-holes narrower than the slit is disposed so as to cover the entrance of each slit of the rectifying member. Therefore, the vapor | steam which evaporates from a coating liquid is introduce | transduced into the entrance of each slit through each through-hole of a mesh member. Therefore, the flow of the solvent vapor is not disturbed at the entrance of each slit, and the vapor flow is adjusted. Therefore, the coating film shape can be formed flat and even in each slit region.

It is sectional drawing which shows typically the partial cross section of the organic electroluminescent display concerning embodiment. It is process drawing explaining the manufacturing method of the said organic EL display. It is a figure which shows schematic structure of the drying apparatus used at a drying process when manufacturing an organic electroluminescent display. It is a perspective view which shows the internal structure of the pressure reduction container in the said drying apparatus. It is an example of the pressure profile in a pressure reduction container. It is a figure which shows a mode when the ink with which it filled in each space between the some bank 5 formed on the board | substrate 1 was dried, without providing a mesh member and a baffle member on a board | substrate. It is a figure which shows the film thickness distribution in the pixel of the light emitting layer formed in each element of a board | substrate center area | region, a board | substrate left end area | region, and a board | substrate right end area | region. It is a figure which shows the flow of the vapor | steam in each slit inlet_port | entrance of a baffle member with the case where a mesh member exists and the case where it does not exist. It is a figure which shows the Example dried using a mask board as a mesh member. It is a figure which shows the Example which uses the metal mask board in which each through-hole was formed in the taper shape as a mesh member.

  An embodiment of the present invention includes a decompression container capable of decompressing the inside and a decompression pump that exhausts the interior of the decompression container, and evaporates a solvent contained in the coating liquid filled on the upper surface of the substrate in the decompression container. In the manufacturing apparatus for forming the functional layer of the organic EL element, a rectifying member in which a plurality of slits for circulating the solvent vapor are arranged in parallel in the decompression container, and the inlet of each slit is spaced from the upper surface of the substrate. And a mesh member in which a plurality of through-holes narrower than the slits are formed is disposed so as to cover the entrance of each slit of the rectifying member.

  According to this aspect, since the solvent vapor evaporating from the coating liquid filled in each region on the upper surface of the substrate flows through each slit arranged in parallel with the rectifying member, the evaporation rate of the solvent is made uniform over the entire substrate. . Further, since the flow of the solvent vapor is not disturbed at the entrance of each slit, the evaporation rate of the solvent is made uniform in each slit region. Therefore, the coating film shape is made uniform without variation in the coating film shape formed in each region on the substrate.

Therefore, by using the manufacturing apparatus of the above aspect, an organic EL element or an organic EL light emitting device having excellent light emission characteristics can be manufactured.
In the above aspect, the following is preferable.
The mesh member is formed so that a plurality of through holes face each of the entrances of the slits of the rectifying member.

In the mesh member, the plurality of through holes are arranged in a matrix within a region facing the entrance of each slit.
The mesh member is set so as to spread outward from the entire region filled with the coating liquid on the substrate.
In the rectifying member, a plurality of slits are penetrated in the vertical direction, and an exhaust port for exhausting the solvent vapor discharged from each slit is provided above the decompression vessel.

A metal mask is used as the mesh member.
Here, in the opening of the metal mask, the opening area on the opposite side facing the substrate holding member is made smaller than the opening area on the side facing the substrate holding member.
In a method for forming a coating film by evaporating a solvent contained in a coating liquid filled on an upper surface of a substrate according to an embodiment of the present invention, the coating liquid is filled on the upper surface in a vacuum container. A rectifying member in which a plurality of slits through which solvent vapor flows is arranged is arranged so that the entrance of each slit faces the upper surface of the substrate with a gap, and is wider than the slit. In the state where the mesh member in which a plurality of narrow through-holes are opened is disposed so as to cover the entrance of each slit, the inside of the decompression vessel is decompressed to evaporate the solvent contained in the coating liquid.

[Embodiment]
In the present embodiment, the present invention is applied in a step of forming a light emitting layer of an organic EL display.
First, a schematic configuration of an organic EL display to be manufactured will be described, and then a manufacturing method thereof will be described.

<Schematic configuration of organic EL display>
FIG. 1 is a cross-sectional view schematically showing a partial cross section of an organic EL display.
As shown in FIG. 1, an organic EL display 100 is an organic EL display in which top emission type organic EL elements 10a, 10b, and 10c each having a light-emitting layer constituting RGB sub-pixels are arranged in a matrix. is there. The organic EL elements 10a, 10b, and 10c correspond to RGB sub-pixels, and one adjacent pixel is formed by three adjacent organic EL elements 10a, 10b, and 10c.

An anode 2 is formed in a matrix on the TFT substrate 1 (hereinafter referred to as “substrate 1”), and an ITO (indium tin oxide) layer 3 and a hole injection layer 4 are formed on the anode 2. They are stacked in order. The ITO layer 3 is laminated only on the anode 2, whereas the hole injection layer 4 is formed not only on the anode 2 but over the entire upper surface of the substrate 1.
A bank 5 is formed on the upper periphery of the anode 2 via a hole injection layer 4, and a light emitting layer 6 is laminated in a region sandwiched between the banks 5. Further, on the light emitting layer 6, the electron injection layer 7, the cathode 8, and the sealing layer 9 extend beyond the region defined by each bank 5 and are adjacent to the organic EL elements 10 a, 10 b, and 10 c. It is formed to be continuous.

The substrate 1 is, for example, alkali-free glass, soda glass, non-fluorescent glass, phosphoric acid glass, boric acid glass, quartz, acrylic resin, styrene resin, polycarbonate resin, epoxy resin, polyethylene, polyester, silicone resin. Alternatively, an insulating material such as alumina is used as a base material.
The anode 2 is Ag (silver), APC (silver, palladium, copper alloy), ARA (silver, rubidium, gold alloy), MoCr (molybdenum and chromium alloy), NiCr (nickel and chromium alloy). Etc. may be formed.

The ITO layer 3 is interposed between the anode 2 and the hole injection layer 4 and has a function of improving the bonding property between the layers.
The hole injection layer 4 is formed of a metal oxide, metal nitride, or material that performs a hole injection function such as metal nitride, for example, WOx (tungsten oxide) or MoxWyOz (molybdenum-tungsten oxide). The hole injection layer 4 extends laterally along the bottom surface of the bank 5.

The bank 5 is formed of an insulating organic material such as a resin, for example, an acrylic resin, a polyimide resin, a novolac type phenol resin, or the like. The bank 5 is preferably resistant to organic solvents, and may be subjected to an etching process, a baking process, or the like. Therefore, it is preferable to form the bank 5 from a material that is not easily deformed or altered by such a process.
The light emitting layer 6 is a layer made of RGB organic light emitting materials (fluorescent substances). Examples of the organic light-emitting material include oxinoid compounds, perylene compounds, coumarin compounds, azacoumarin compounds, oxazole compounds, oxadiazole compounds, perinone compounds, pyrrolopyrrole compounds, naphthalene compounds, anthracenes described in JP-A-5-163488. Compound, fluorene compound, fluoranthene compound, tetracene compound, pyrene compound, coronene compound, quinolone compound and azaquinolone compound, pyrazoline derivative and pyrazolone derivative, rhodamine compound, chrysene compound, phenanthrene compound, cyclopentadiene compound, stilbene compound, diphenylquinone compound, styryl Compound, butadiene compound, dicyanomethylenepyran compound, dicyanomethylenethiopyran compound, fluoresceinization Product, pyrylium compound, thiapyrylium compound, serenapyrylium compound, telluropyrylium compound, aromatic ardadiene compound, oligophenylene compound, thioxanthene compound, anthracene compound, cyanine compound, acridine compound, 8-hydroxyquinoline compound metal chain, 2- Examples include a metal chain of a bipyridine compound, a chain of a Schiff salt and a group III metal, an oxine metal chain, and a rare earth chain.

The electron injection layer 7 has a function of transporting electrons injected from the cathode 8 to the light emitting layer 6, and is preferably formed of, for example, barium, phthalocyanine, lithium fluoride, or a combination thereof.
Since it is a top emission type, the cathode 8 is formed of a light transmissive material, for example, ITO, IZO (indium zinc oxide) or the like.

The sealing layer 9 has a role of preventing the light emitting layer 6 and the like from being exposed to moisture or air, and is made of a material such as SiN (silicon nitride) or SiON (silicon oxynitride). Is formed.
1 shows an XZ cross-sectional shape obtained by cutting the substrate 1 in the horizontal direction. However, the bank 5 is formed along the upper surface of the substrate 1 in the vertical direction (the front and back direction in FIG. 1 and the Y in FIG. 2). Direction). A plurality of banks 5 are arranged over the entire top surface of the substrate 1.

<Method for manufacturing organic EL display>
FIG. 2 is a process diagram illustrating a method for manufacturing the organic EL display.
As shown in FIG. 2A, an anode 2, an ITO layer 3, and a hole injection layer 4 are sequentially formed on a substrate 1, and a bank 5 is formed on the hole injection layer 4. Along with this, a recessed space 5a, which is a region where light emitting layers are to be formed, is formed between the banks 5.

The anode 2 is formed by forming an Ag thin film by sputtering, for example, and patterning the Ag thin film in a matrix by, for example, a photolithography method. The Ag thin film may be formed by vacuum deposition or the like.
The ITO layer 3 is formed by forming an ITO thin film by sputtering, for example, and patterning the ITO thin film by, for example, a photolithography method.

The hole injection layer 4 is formed by a technique such as vacuum deposition or sputtering using a composition containing WOx or MoxWyOz.
The bank 5 is formed by forming a bank material layer on the hole injection layer 4 by applying a bank material or the like and removing a part of the formed bank material layer. The removal of the bank material layer can be performed by forming a resist pattern on the bank material layer and then etching. The surface of the bank material layer may be subjected to a liquid repellent treatment by a plasma treatment using a fluorine-based material, if necessary.

Next, as shown in FIG. 2 (b), the recessed space 5a, which is the light emitting layer forming region between the banks 5, is filled with ink 6a as a coating liquid containing organic light emitting materials of any of the RGB colors. . Then, the filled ink 6a is dried under reduced pressure to form the light emitting layer 6 as shown in FIG.
The step of forming the light emitting layer 6 will be described in detail later.

Next, as shown in FIG. 2 (d), an electron injection layer 7, a cathode 8, and a sealing layer 9 are sequentially formed.
The electron injection layer 7 is formed by forming barium into a thin film by, for example, vacuum deposition.
For the cathode 8, for example, ITO is formed into a thin film by sputtering.
<Formation of the light emitting layer 6>
A method for forming the light emitting layer 6 will be described in detail.

Ink preparation process:
For each color of RGB, an ink is produced by dissolving the organic light emitting material constituting the light emitting layer 6 in a solvent including a solvent having a relatively high boiling point (boiling point: 170 to 300 ° C.).
As the solvent, in addition to cyclohexylbenzene (CHB, boiling point 238 ° C.), for example, diethylbenzene (boiling point 183 ° C.), decahydronaphthalene (boiling point 190 ° C.), methyl benzoate (boiling point 199 ° C.), acetophenone (boiling point 202 ° C.), Phenylbenzene (boiling point 202 ° C), benzyl alcohol (boiling point 205 ° C), tetrahydronaphthalene (boiling point 207 ° C), isophorone (boiling point 213 ° C), n-dodecane (boiling point 216 ° C), dicyclohexyl (boiling point 227 ° C), p- And xylene glycol dimethyl ether (boiling point 235 °).

These solvents may be used alone, or may be a mixture of a plurality of solvents, or a mixture of the above high-boiling solvent and a low-boiling solvent having a boiling point of less than 170 ° C.
Ink filling process:
Over the entire surface of the substrate 1, each of the concave spaces 5 a formed between the plurality of banks 5 is filled with ink of each RGB color by a droplet discharge method (inkjet method).

In addition to this, as a method for filling ink, a dispenser method, a nozzle coating method, a spin coating method, intaglio printing, relief printing, or the like may be used.
Drying process:
The substrate 1 filled with ink of each color is accommodated in the drying device 20 and dried by evaporating the solvent in the ink under a reduced pressure atmosphere.

(Configuration of drying apparatus 20 and drying method)
FIG. 3 is a diagram showing a schematic configuration of the drying device 20 used in the drying process when the organic EL display 100 is manufactured.
The drying apparatus 20 includes a decompression container 21, and a support base 22 for horizontally placing the substrate 1 filled with ink is provided inside the decompression container 21, and an ink is disposed above the support base 22. A mesh member 40 and a rectifying member 50 are provided for rectifying the solvent vapor evaporating from the rectifier.

FIG. 4 is a perspective view showing an internal configuration of the decompression container 21 in the drying apparatus 20.
The rectifying member 50 is provided with a plurality of slits 53 for allowing the solvent vapor to flow therethrough, and the inlets (lower end openings) of the slits 53 are arranged to face the upper surface of the substrate 1 with a gap.
The mesh member 40 is a plate-like member having a plurality of through-holes 41 having a narrower width than the slit 53, and is disposed so as to cover the lower surface of the rectifying member 50, that is, to cover the entrance of each slit 53. Has been. Thereby, the mesh member 40 is horizontally disposed so as to cover the substrate 1 at a slight distance from the substrate 1.

A horizontal partition plate 24 and an exhaust port 23 are provided at an upper portion in the decompression vessel 21 with a gap from the upper end surface of the rectifying member 50.
A decompression pump 31 is connected to the exhaust port 23 via an exhaust pipe 30. By driving the decompression pump 31, the decompression pump 21 can be exhausted and decompressed.
When exhausting from the decompression vessel 21, the gas present immediately below the mesh member 40 passes through the through holes 41 of the mesh member 40 and flows into the rectifying member 50 and the slits 53, and flows upward through the slits 53. It is discharged from the exhaust port 23.

The decompression vessel 21 is provided with a door (not shown) for taking in and out the substrate 1 on its side surface and can be hermetically sealed.
The decompression pump 31 has a capability of decompressing the decompression vessel 21 to 10 Pa or less, and uses, for example, a mechanical booster and a rotary pump. Moreover, you may make it switch the vacuum pump to be used according to the pressure in the pressure reduction container 21. For example, when drawing from atmospheric pressure, a rotary pump may be used for exhaustion, and when the degree of vacuum increases, a mechanical booster may be used in combination.

  A pressure gauge 61 for measuring the pressure in the decompression vessel 21 is attached to the decompression vessel 21. In addition, an adjustment valve 32 that adjusts the exhaust conductance is attached to the exhaust pipe 30. The measurement value measured by the pressure gauge 61 is input to the controller 60, and the controller 60 controls the adjustment valve 32 and the drive control of the decompression pump 31 based on this measurement value.

Details about the mesh member 40 and the flow regulating member 50:
As shown in FIGS. 3 and 4, the rectifying member 50 is fixed in the decompression vessel 21, and the mesh member 40 is attached so as to cover the entire lower surface of the rectifying member 50. The lower surfaces of the mesh member 40 and the rectifying member 50 extend outward from the entire ink filling region on the upper surface of the substrate 1 placed on the support base 22.

As a result, the mesh member 40 is disposed so as to be parallel to the substrate 1 with a gap from the upper surface filled with ink in the substrate 1 placed on the support base 22 and to cover the entire ink filling region. Directly above the mesh member 40, a rectifying member 50 is provided in which a plurality of slits 53 for allowing solvent vapor to flow upward are arranged in parallel.
3 and 4, the mesh member 40 is a thin plate-like member disposed on the inlet side of the rectifying member 50, and a plurality of through holes 41 are provided to the inlets of the slits 53 of the rectifying member 50. It is established one by one.

As the mesh member 40, a wire mesh may be used, or a mask plate having a through-hole formed in a thin plate may be used.
The rectifying member 50 includes a plurality of vertical partition plates 51 extending in the vertical direction (Y direction) and the vertical vertical direction (Z direction), and a plurality of vertical partition plates 52 extending in the horizontal direction (X direction) and the vertical direction (Z direction). Are combined in a matrix.

The plurality of vertical partition plates 51 are arranged at equal intervals in the horizontal direction (X direction), and the plurality of vertical partition plates 52 are arranged at equal intervals in the vertical direction (Y direction). By the vertical partition plate 51 and the vertical partition plate 52, the upper space of the substrate 1 is partitioned in the horizontal direction and the vertical direction.
Alternatively, the vertical partition plate 52 may be omitted, and the plurality of vertical partition plates 51 may be provided in a stripe shape to partition the space on the substrate 1 only in the lateral direction.

Further, in the rectifying member 50, in order to make the flow rate of the steam flowing through each slit 53 uniform, it is preferable to arrange the plurality of vertical partition plates 51 at equal intervals in the lateral direction (X direction) as described above. The intervals between the plurality of vertical partition plates 51 may be appropriately changed depending on the shape of the decompression container 21 and the position of the exhaust port 23.
Using such a drying apparatus 20, the ink is dried under reduced pressure as follows.

The substrate 1 filled with ink is placed on the support base 22 in the vacuum container 21 (initial temperature 25 ° C.), and the vacuum container 21 is sealed.
Thereafter, the decompression container 21 is decompressed by the decompression pump 31.
FIG. 5 is an example of a pressure profile (temporal change in pressure) in the decompression vessel 21.
In this example, the decompression vessel 21 is depressurized over about 5 minutes until the pressure reaches about 10 Pa from the atmospheric pressure state. Thereafter, the adjustment valve 32 is adjusted for about 6 minutes to maintain the pressure in the decompression vessel 21 at 10 Pa.

By reducing the pressure in the decompression container 21 in this way, the solvent contained in the ink 6a is evaporated, and the light emitting layer 6 is formed.
Thereafter, the adjustment valve 32 is closed, the atmosphere is introduced into the decompression vessel 21 to return to the atmospheric pressure state, and the substrate is taken out from the decompression vessel 21.
<Rectifying effect by mesh member 40 and rectifying member 50>
As described above, when the vacuum drying is performed in the vacuum container 21, the vacuum drying is performed in a state where the mesh member 40 and the rectifying member 50 are present above the substrate 1, and therefore, evaporation is performed from each region on the substrate 1. The solvent vapor passes through the through holes 41 of the mesh member 40 and flows into the slits 53 directly above. Therefore, it is uniformly introduced into each slit 53 partitioned by the vertical partition plate 51 and the vertical partition plate 52. Then, the steam introduced into each slit 53 flows smoothly upward along the vertical partition plate 51 and the vertical partition plate 52 and is exhausted from the exhaust port 23.

Accordingly, during drying under reduced pressure, the flow of the solvent evaporating from the ink filled in each region on the substrate is uniformly arranged, so that the formed light emitting layer 6 has good uniformity.

Hereinafter, this effect will be described in detail with reference to FIGS.
As Comparative Example 1, a mechanism in which variation occurs in the shape of the light emitting layer formed on the substrate 1 when drying without providing the mesh member 40 and the rectifying member 50 in the drying chamber will be described. Note that the variation in the shape of the light emitting layer on the substrate 1 can occur in either the horizontal direction (X direction) or the vertical direction (Y direction), but here, the horizontal direction (mainly orthogonal to the bank 5) ( (X direction) will be described.

FIG. 6 is a diagram showing a state in which ink filled in each space between the plurality of banks 5 formed on the substrate 1 is dried without providing a mesh member and a rectifying member on the substrate 1. The substrate 1 is shown in a cross section cut in the lateral direction.
In FIG. 6A, the height of the curve indicated by the broken line indicates the concentration of the solvent vapor that evaporates from the ink at each position in the horizontal direction on the substrate.

FIG. 6B shows the evaporation rate in the subpixel when the solvent evaporates from the ink in the central region of the substrate 1 and the right and left end regions of the substrate 1 when the light emitting layer 6 is formed. Are different from each other by arrows A1 to A3, arrows B1 to B3, and arrows C1 to C3.
FIG. 7 shows the film thickness distribution (film thickness distribution in the lateral direction perpendicular to the bank 5) in the sub-pixels of the light-emitting layer 6 formed in each sub-pixel of the substrate center region, substrate left end region, and substrate right end region. It is a figure and was measured using an atomic force microscope (AFM).

As shown in FIG. 6A, the solvent vapor concentration is lower in the regions B and C on the end portion of the substrate 1 than in the region A on the center portion of the substrate 1, and in particular, the substrate right end and substrate left end. In the vicinity, the decrease in solvent vapor concentration is significant.
The reason why the concentration of the solvent vapor is lowered at the end of the substrate 1 in this way is that the solvent vapor evaporated from the ink diffuses upward only in the central region of the substrate 1 because there is a source of the solvent vapor on both sides. On the other hand, in the right end region B of the substrate 1, there is no solvent vapor generation source on the right side, and a space with a low solvent vapor pressure spreads, so that the solvent vapor evaporated from the ink is only in the upward direction. This is because the solvent vapor that diffuses in the right direction and also evaporates from the ink in the left end region C of the substrate 1 is diffused not only in the upward direction but also in the left direction, and the diffusion power is large.

  Here, the lower the vapor concentration on the substrate 1, the larger the vapor concentration gradient near the ink surface and the higher the evaporation rate of the solvent. Therefore, FIG. 6B shows the right end region of the substrate. Thus, in the right end region of the substrate 1, the evaporation rate B2 from the center of the pixel is higher and the evaporation rate B3 from the right end of the pixel is higher than the evaporation rate B1 from the left end of the pixel.

  If there is a difference in the evaporation speed in the liquid pool of the ink liquid filled in this way, the ink liquid flows from the left end of the pixel having a low evaporation speed to the right end of the pixel having a high evaporation speed. Since only the contained solvent evaporates, the amount of light emitting layer material deposited increases at the right end of the pixel, and the film thickness increases accordingly. Therefore, the film thickness of the light emitting layer formed in the sub-pixel in the substrate right end region of the substrate 1 is larger in the pixel right end portion than in the pixel left end portion as shown in the graph of the substrate right end region in FIG.

  Similarly, in the left end region of the substrate, the evaporation rate C2 from the center of the pixel is higher and the evaporation rate C1 from the left end of the pixel is higher than the evaporation rate C3 from the right end of the pixel. Accordingly, in the ink liquid, the liquid flows from the pixel portion to the left end portion of the pixel, and the film thickness of the light emitting layer formed in the left end region of the substrate 1 is larger at the left end portion of the pixel than at the right end portion of the pixel.

  On the other hand, as shown in the figure of the substrate central region in FIG. 6B, in the substrate central region, the difference in vapor pressure between the left and right in the pixel is small, so the evaporation rate A1 from the left end of the pixel and the right end of the pixel. , A3 are almost equivalent. However, since the solvent vapor can diffuse also on the adjacent bank 5 at the pixel end portion, the vapor concentration is slightly smaller at the pixel end portion than the pixel center portion, and the evaporation rate A2 from the pixel center portion is In comparison, the evaporation rates A1 and A3 from the pixel end are slightly increased.

Accordingly, in the central region of the substrate, the ink liquid flows from the central portion of the pixel to the element end portion in the liquid pool of the filled ink liquid, and as shown in the graph of the central region of the substrate in FIG. Compared to the thickness, the film thickness at the pixel edge is slightly larger.
On the other hand, in the present embodiment, the drying is performed under reduced pressure with the mesh member 40 and the rectifying member 50 existing above the substrate 1, so that it is uniformly introduced into each slit 53 as described above. The steam introduced into each slit 53 flows smoothly upward along the vertical partition plate 51 and the vertical partition plate 52 and is exhausted from the exhaust port 23.

Accordingly, during drying under reduced pressure, the solvent vapor concentration in each region on the substrate 1 becomes uniform, and accordingly, the difference in evaporation rate in the pixels of the substrate right end region and the substrate left end region can be suppressed to be small. Flow (convection) is also kept small. Therefore, the film thickness difference between the left and right in the pixel of the light emitting layer 6 to be formed can be suppressed to be small.
Further, since the mesh member 40 is present at the lower end entrance of each slit 53 of the rectifying member 50, the light emitting layer 6 having a more uniform shape can be formed as described below.

FIG. 8 is a diagram illustrating the flow of steam at the lower end inlet of each slit 53 when the mesh member 40 is present and when it is not present.
FIG. 8A is an enlarged view of a portion C surrounded by a circle in FIG. 3 and shows a case where the mesh member 40 does not exist.
FIG. 8B shows a case where the mesh member 40 does not exist at the lower end entrance of each slit 53 of the rectifying member 50. In this case, when the solvent vapor flows into the lower end inlet of each slit 53 as indicated by an arrow a2 in the figure, the flow of the vapor tends to be disturbed. When the flow of vapor is disturbed at the lower end inlet of each slit 53, the shape of each light emitting layer 6 formed on the substrate 1 is disturbed accordingly, and the uniformity can be impaired.

  In contrast, in the present embodiment, as shown in FIG. 8A, the mesh member 40 exists at the lower end inlet of each slit 53, and the solvent vapor on the substrate 1 passes through the plurality of through holes 41. Since it is introduced into each slit 53 while being rectified, there is no disturbance near the entrance of each slit 53. Therefore, the light emitting layers 6 formed on the substrate 1 are uniformly formed without any disturbance in the shape of the light emitting layers 6 formed on the substrate 1.

As described above, in addition to the rectifying effect on the entire area of the substrate 1 by the rectifying member 50, the rectifying effect in the entrance of each slit 53 by the mesh member 40 is also obtained. The solvent is uniformly evaporated from the ink filled in the light-emitting layer, whereby the light-emitting layer 6 having a uniform shape is formed.
Specifications of mesh member 40 and rectifying member 50:
In the rectifying member 50, the pitch W (corresponding to the lateral width of each slit 53) of the vertical partition plates 51 is preferably 50 mm or less because the rectifying effect is obtained as the width becomes narrow. On the other hand, if the pitch W is too narrow, the thickness of the vertical partition plate 51 cannot be secured, and the pressure loss when the solvent vapor flows through the slit 53 becomes large.

If the length L in the vertical direction of each slit 53 is too short, a sufficient rectifying effect cannot be obtained, and turbulence of the airflow generated at the upper end side (exit side) of the slit 53 is easily transmitted to the substrate 1, so that it should be 10 cm or more. Is preferred. Further, if the length L is too long, the pressure loss when the solvent vapor circulates through the slit 53 is increased, and therefore, the length is preferably 500 cm or less.
A particularly preferable range for the length L of the slit 53 is 20 cm to 100 cm.

A plurality of through holes 41 provided in the mesh member 40 face the inlets of the slits 53 and function to rectify the solvent vapor flowing into the inlets.
Therefore, it is preferable that the plurality of through holes 41 are uniformly distributed over the entire entrance of each slit 53 of the rectifying member 50.
For example, as shown in the enlarged view of the mesh member 40 in FIG. 4, a plurality of through holes 41 are arranged in a matrix in the horizontal direction (X direction) and the vertical direction (Y direction) over the entire entrance opening region of the slit 53. It is preferable to do.

The opening shape of each through hole 41 is preferably a circular shape, an elliptical shape, a rectangular shape, or the like, but is not limited thereto.
Further, as shown in the following embodiment, each through hole 41 of the mesh member 40 may be formed so as to correspond to the ink filling region on the substrate 1.
The opening width (hole diameter) of the through hole 41 is set to be equal to or larger than the pixel size (the length of one side of the pixel). Since the pixel size is usually 10 μm or more, the width (hole diameter) of the through hole 41 is also set to 10 μm or more. On the other hand, in order to obtain a rectifying effect, the width (hole diameter) of the through hole 41 is preferably set to 1 mm or less.

If the gap G between the substrate 1 and the mesh member 40 is too narrow, the substrate 1 may be adsorbed by the mesh member 40, so that it is 0.1 mm or more. On the other hand, if the gap G is too wide, the rectifying effect by the mesh member 40 and the rectifying member 50 hardly reaches the surface of the substrate 1, so the gap G is preferably set to 50 mm or less.
(Example in which a mask plate is used as the mesh member 40 and dried)
Coating liquid:
Ink for forming the light emitting layer of organic EL devices, solvent is butyl benzoate, solute is polyfluorene polymer (Product name: Poly (9,9-di-n-dodecylfluorenyl-2,7-diyl), made by Aldrich) Yes, the concentration is 1.0 wt%.

substrate:
A bank is formed on the substrate by spin-coating a photosensitive material on a flat glass and patterning it with a photolithographic technique. Here, as shown in FIG. 9, a bank 5 having a width of 25 μm is formed on the substrate 1 with a gap of 65 μm.
Application process:
Ink is filled between banks (pixel regions) on the substrate using an ink jet device.

Drying process:
The drying device 20 used in the drying process uses a metal mask plate having a through hole 41 in a thin metal plate as the mesh member 40. Then, the inside of the decompression vessel 21 is decompressed based on the pressure profile shown in FIG.
The metal mask plate can be manufactured by opening the through hole 41 by etching a stainless plate having a thickness of 0.05 mm to 0.1 mm.

  In the example shown in FIG. 9, the thickness of the metal mask plate is 100 μm, and the through hole 41 has the same pattern as the filling region (element formation scheduled region) of the ink 6a on the substrate 1 (the through hole 41 and the element region). Is a one-to-one corresponding pattern). Such a metal mask can be manufactured by etching using a mask having the same design specifications as the exposure mask used when forming the bank 5.

Then, the substrate 1 is placed on the support base 22 so that each pixel region (region filled with the ink 6a) is located immediately below each through hole 41 in the mesh member 40.
In order to align each through hole 41 and each pixel region of the mesh member 40, for example, alignment marks for alignment are formed on the upper surface of the support base 22 and the substrate 1, and both alignment marks are formed. Can be easily aligned.

By performing drying under reduced pressure in this state, the solvent vapor evaporating from the ink 6a filled in each element region on the substrate 1 is sucked into each through hole 41 located immediately above, so that each pixel region is filled. The ink 6a thus obtained can be dried under reduced pressure under the same conditions.
(Example of drying using a mask plate having tapered through-holes)
In the embodiment shown in FIG. 10, a metal mask plate is used as the mesh member 40 as in FIG. 9, but each through hole 41 has a larger width (hole diameter) on the side closer to the substrate 1. 41 is formed in a taper shape. Thereby, it can be expected that the effect of forming the thickness of the light emitting layer 6 to be flat is enhanced.

That is, the ink 6a filled between the banks rises thick in the pixel central region and thins in the pixel end region due to the surface tension.
Here, if the through-hole 41 is formed in a tapered shape, it is easy to cover the region filled with the ink 6a by increasing the opening area on the inlet side (lower side) of the through-hole 41. . Thereby, the solvent vapor evaporating from the pixel center and the solvent vapor evaporating from the pixel end can be uniformly taken into the through-hole 41.

As a result, in the ink 6a filled in each element region, the evaporation rate of the solvent from the pixel center region and the evaporation rate of the solvent from the pixel end region are made uniform, and the film thickness of the light emitting layer 6 is flattened. It can be expected to enhance the effect of forming.
The advantages of forming the through holes 41 in a tapered shape will be further described. As shown in FIG. 9, when the through holes 41 are straight (cylindrical), the hole diameter R1 is set to the width of the ink 6a between the banks 5 ( 65m), the thickness t1 between the through holes 41 in the mesh member 40 is also reduced to a bank width (25 μm), but the shape of the through holes 41 is tapered as shown in FIG. Even if the hole diameter R1 of the through hole 41 on the inlet side is increased to the same extent as the width (65 μm) of the ink 6a between the banks 5, the wall thickness t2 on the outlet side between the through holes 41 in the mesh member 40 is the inlet side. Is larger than the thickness t1 (thickness t2> thickness t1), it is easy to ensure the strength of the mesh member 40, and the processing when forming the through hole 41 is also easy.

In order to form the through-hole 41 in a tapered shape in this way, a general taper etching technique may be used, and the conditions for opening the through-hole 41 by wet etching are controlled for a metal thin plate. By doing so, it can be formed with a desired taper angle.
Moreover, when forming the through-hole 41 in a taper shape, it is preferable to set the angle of the inner wall surface of the through-hole 41 with respect to the main surface (horizontal surface) of the mesh member 40 within a range of 65 to 85 °.

(Modification)
(1) In the above embodiment, the case where a light emitting layer is formed between banks when forming a plurality of EL elements on a substrate has been described. However, functional layers other than the light emitting layer, such as a charge injection transport layer, etc. Can also be carried out in the same way, and the same effect can be obtained.

(2) In the above embodiment, the example in which the light emitting layer of the top emission type organic EL display is formed has been described. However, the present invention can also be applied to the case of forming the light emitting layer of the bottom emission type organic EL display. In addition to the light emitting layer of the organic EL element, the present invention can also be applied when forming a functional layer such as a charge transport layer or a color filter of the organic EL element.
(3) Further, in addition to the organic EL elements described in the embodiment, a plasma display panel rib or the like, an overcoat film for a flat panel display, a resist film for photolithography, an alignment film for a liquid crystal panel The present invention can also be applied when forming the above.

The present invention is an effective technique in the technical field of forming a functional film by applying and drying ink, and can be applied to manufacture an organic EL panel such as an organic EL light source and an organic EL light source. An organic EL panel having uniform emission characteristics within the substrate surface can be manufactured.
In the organic EL display, the light emission characteristics in the image display surface are made uniform, which contributes to the improvement of the image quality.

DESCRIPTION OF SYMBOLS 1 Board | substrate 5 Bank 5a Recessed space 6 Light emitting layer 6a Ink 10a, 10b, 10c Organic EL element 20 Drying device 21 Depressurization container 22 Support base 23 Exhaust port 24 Horizontal partition plate 30 Exhaust pipe 31 Depressurization pump 32 Adjustment valve 40 Mesh member 41 Through Hole 50 Rectifying member 51 Vertical partition plate 52 Vertical partition plate 53 Slit 60 Controller 61 Pressure gauge 100 Organic EL display

Claims (10)

A function of the organic EL element by evaporating the solvent contained in the coating liquid filled on the upper surface of the substrate in the decompression container, comprising a decompression container capable of decompressing the inside and a decompression pump exhausting from the decompression container A manufacturing device for forming a layer,
In the vacuum container,
A rectifying member in which a plurality of slits through which solvent vapor flows is arranged in parallel is arranged so that the entrance of each slit faces the upper surface of the substrate with a gap therebetween,
A manufacturing apparatus, wherein a mesh member in which a plurality of through-holes narrower than the slit are formed is disposed so as to cover an inlet of each slit of the rectifying member.   2. The manufacturing apparatus according to claim 1, wherein the mesh member is formed so that a plurality of the through-holes face each inlet of each slit of the rectifying member. In the mesh member,
The manufacturing apparatus according to claim 2, wherein the plurality of through holes are arranged in a matrix within a region facing the entrance of each slit. The mesh member is
The manufacturing apparatus according to claim 1, wherein the manufacturing apparatus extends outward from the entire region filled with the coating liquid on the substrate. In the rectifying member, each of the plurality of slits penetrates in the vertical direction,
The manufacturing apparatus according to any one of claims 1 to 4, wherein an exhaust port for exhausting the solvent vapor discharged from each of the slits is provided in an upper portion of the decompression vessel.   The manufacturing apparatus according to claim 1, wherein the mesh member is a metal mask in which a through hole is formed in a metal plate. Each through-hole opened in the metal mask is
The manufacturing apparatus according to claim 6, wherein the opening area on the opposite side is smaller than the opening area on the side facing the substrate.   The manufacturing method of the organic EL element characterized by including the process of forming the functional layer of an organic EL element using the manufacturing apparatus in any one of Claims 1-7.   A method for producing an organic EL display device comprising a step of forming a functional layer of an organic EL element using the production apparatus according to claim 1. A coating film forming method for forming a coating film by evaporating a solvent contained in a coating liquid filled on an upper surface of a substrate,
In the vacuum container,
Arrange the substrate filled with coating liquid on the upper surface,
The flow straightening member in which a plurality of slits for circulating the solvent vapor are arranged side by side is arranged so that the entrance of each slit faces the upper surface of the substrate with a gap therebetween,
In a state where a mesh member in which a plurality of through-holes narrower than the slit are opened is arranged so as to cover the entrance of each slit,
A method for forming a coating film, comprising: evaporating a solvent contained in the coating solution by decompressing the inside of the decompression vessel.

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