JP2005211770A - Substrate manufacturing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a substrate manufacturing apparatus capable of forming a thin film excellent in in-plane film thickness uniformity and capable of suitably adapted to an electronic display device such as an organic EL display device or the like. <P>SOLUTION: In the substrate manufacturing apparatus used in a process for forming the thin film such as an organic layer or the like in an organic EL element by bonding liquid droplets to a substrate from a liquid droplet coating part comprising an ink jet device or the like and irradiating the liquid droplet applied substrate with electromagnetic waves such as infrared rays or the like, the substrate to which the liquid droplet are bonded is successively irradiated with electromagnetic waves. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to a substrate manufacturing apparatus, a substrate manufacturing method, and an electronic display device. More specifically, the present invention relates to a substrate manufacturing apparatus used in a process of forming a film by drying droplets, a substrate manufacturing method using the same, and an electronic display device manufactured by these.

The substrate manufacturing apparatus is an apparatus for manufacturing a substrate subjected to processing such as patterning processing, and the substrate manufactured by such a substrate manufacturing apparatus includes, for example, an organic EL (electroluminescence) display device, a color filter, It is used in electronic display devices such as X-ray sensors and microlens arrays. Among these, in an organic EL display device, a patterning substrate in which an organic layer as a light emitting layer is formed on a substrate according to a dot pattern is used. Such organic EL elements have high-speed response to electrical signals, high light visibility because they emit light themselves, and because organic materials are the main raw materials, they can be used in a wide range of molecular designs and easily multicolored. It has the advantage of being. Further, since it is a completely solid element, it has excellent characteristics such as excellent impact resistance and easy handling. Therefore, in recent years, application to surface light sources, displays, and light sources of printers has been promoted and attracted attention.

Such organic EL elements can be broadly classified into a low molecular type and a high molecular type. Low molecular weight organic EL elements are produced mainly using vapor deposition, while polymer organic EL elements are produced using methods such as spin coating, droplet coating (inkjet), and transfer. Is done. When the droplet coating method (inkjet method) is used, the polymer type organic EL element is produced mainly by dropping a droplet on a substrate and drying it to form a film. This droplet drying step is a very important step in controlling the film thickness.

Regarding the conventional substrate manufacturing apparatus, with respect to the drying process of the solvent containing the solute and the film thickness distribution after drying, depending on the drying conditions, the film thickness of the film formed by drying the droplets may be thicker at the periphery. It is disclosed that there is a case where the film thickness of the central part is increased by drying the central part of the droplet (for example, Non-Patent Document 1).
On the other hand, regarding the method for producing a functional element, in order to obtain the flatness of the functional layer, the functional layer forming coating liquid is used depending on whether the central portion of the functional layer is convex or concave. A method for controlling the volatilization rate of the solvent in the drying step is disclosed (for example, see Patent Document 1). Further, Patent Document 1 describes a method of increasing the volatilization rate in the case of a convex shape by diffusing a volatile solvent by blowing air to prevent saturation of the solvent, and a method of applying heat by a hot plate or a far infrared heater. In addition, as a method of slowing down the volatilization rate in the case of a concave shape, a method of excessively filling a volatile solvent in the atmosphere to suppress the volatilization of the solvent, and a method such as pressurization and cooling are described. However, in these methods, it is not easy to make the drying process of each film distributed in the plane the same. For example, the same drying process is used for the first formed film and the last formed film. It was not easy to realize. Because of this, it has been difficult to obtain film thickness uniformity in the plane, and there is room for improvement in this respect.
JP 2003-266003 A (page 1-6) “Physical Review E” (USA), American Physical Society (APS), Vol. 62, p. 756

The present invention has been made in view of the above-described situation, and provides a substrate manufacturing apparatus capable of forming a thin film with excellent film thickness uniformity in a plane, a substrate manufacturing method using the same, and an electronic display device. It is intended to do.

The present inventors have various substrate manufacturing apparatuses that can be suitably applied to the manufacture of an electronic display device such as an organic EL display device, preferably used in a process of forming a film by drying droplets. During the study, attention was paid to the fact that the film applied and dried by the droplet coating method (inkjet method) produced a film thickness distribution between the respective films due to the drying process of the droplets. For example, when a film having such a film thickness distribution is used as an organic layer in an organic EL display device, the light emission characteristics differ due to the difference in film thickness between dots, that is, the film thickness can be controlled. If not, the display luminance varies between dots, and the display quality is impaired. On the other hand, by suppressing such a film thickness distribution, particularly when applied to an organic EL display device, it is possible to suppress the film thickness distribution of an organic layer that has a particularly large effect on light emission characteristics and life characteristics. An organic EL display device that is efficient and has a long lifetime can be provided. In the color filter, the transmission intensity distribution can be suppressed by suppressing the film thickness distribution, so that the display quality can be improved. Therefore, in the method of drying droplets using electromagnetic waves, the droplets were ejected by sequentially irradiating the electromagnetic waves after the droplets were deposited on the substrate in order to make the film thickness between the films uniform. If drying is started sequentially, the time from droplet discharge to drying can be controlled so that the drying process of each film is the same, and variations in film thickness between films are suppressed. The present inventors have found that it is possible to solve this problem and have conceived that the above-mentioned problems can be solved brilliantly.

That is, the present invention is a substrate manufacturing apparatus used in a process of forming a thin film by depositing droplets from a droplet applying unit on a substrate and irradiating an electromagnetic wave from the electromagnetic wave irradiation unit. This is a substrate manufacturing apparatus that sequentially irradiates electromagnetic waves after depositing droplets on a substrate.
The present invention is described in detail below.

The substrate manufacturing apparatus of the present invention is used as a film forming apparatus.
As said board | substrate, a highly transparent thing is preferable, For example, what consists of inorganic materials, such as glass, transparent resin, etc. can be used. Although it does not specifically limit as a droplet, It is preferable to comprise from what has the characteristic suitable for apply | coating by a droplet discharge method (inkjet method).

As said droplet application part, what consists of an inkjet apparatus, a dispenser apparatus, etc. is mentioned, for example. Moreover, as an electromagnetic wave irradiation part, what can irradiate infrared rays, for example is preferable. That is, the irradiation of electromagnetic waves is preferably performed by infrared rays. By irradiating the droplets with infrared rays, the droplets can be effectively heated and dried. In addition, the said infrared rays point out the electromagnetic waves in which the main component is contained in the wavelength from about 770 nm to about 1 mm. Preferably, it is a near infrared ray of about 0.8 to 20 μm, which is particularly effective for effective heating. Furthermore, as a preferable form of the electromagnetic wave irradiation part, there is a form in which a plurality of electromagnetic wave irradiation parts are installed and electromagnetic waves can be simultaneously irradiated to a plurality of regions, and a plurality of droplets are efficiently dried to form a thin film Can be formed. As a more preferable form, the form which can control individually the irradiation intensity | strength etc. of electromagnetic waves in several electromagnetic wave irradiation part is mentioned.
In the board | substrate manufacturing apparatus of this invention, as long as it has a droplet application part and an electromagnetic wave irradiation part as an essential structural member, the other structural member may be included or it is not necessary to include.

The substrate manufacturing apparatus sequentially irradiates electromagnetic waves after depositing droplets on a substrate. As a result, it is possible to irradiate and dry the electromagnetic wave by the electromagnetic wave irradiation unit without leaving the liquid droplets adhered on the substrate by the liquid droplet application unit. It becomes possible to suppress the film thickness variation in between. According to the present invention as described above, for example, when an organic layer is formed on a substrate used in an organic EL display device, it is possible to greatly suppress the variation in drying between dots, and the film thickness between dots can be reduced. An organic layer having excellent uniformity can be formed, and when an electrode or the like is further formed to form an organic EL element, a uniform light emitting state can be obtained.

It is preferable that the substrate manufacturing apparatus irradiates the droplets with electromagnetic waves with a time interval or more at which the droplets start to adhere and spread on the substrate. That is, the droplet application unit and the electromagnetic wave irradiation unit are arranged side by side so that the drying by the electromagnetic wave irradiation unit starts immediately after the droplets are attached to the substrate and at least after the droplet diameter as viewed from the upper side of the substrate widens. Preferably there is. As a result, the droplet spreads after being applied on the substrate, and then drying by the electromagnetic wave irradiation unit starts, so that the droplet is dried in a flatter state than when drying is started before spreading. Therefore, the flatness of the film thickness can be improved.

In the substrate manufacturing apparatus, it is preferable that the droplet application unit and the electromagnetic wave irradiation unit are installed with an interval therebetween. In this embodiment, after the droplet is applied by the droplet application unit, the substrate is moved to the electromagnetic wave irradiation unit, so the distance between the droplet application unit and the electromagnetic wave irradiation unit, the moving speed of the substrate, etc. This makes it possible to easily adjust the time from when the droplets adhere to the substrate until the electromagnetic wave irradiation. In addition, the form of the substrate manufacturing apparatus may be, for example, a form in which the droplet application unit and the electromagnetic wave irradiation unit are integrally provided, and the liquid droplet application unit and the electromagnetic wave irradiation unit are switched every time.

Moreover, in the said board | substrate manufacturing apparatus, it is preferable that the time from the time a droplet adheres on a board | substrate until electromagnetic wave irradiation and the time which irradiates electromagnetic waves become substantially the same with each droplet. That is, when viewed for each droplet, it is preferable that the time from the ejection of the droplet to the drying by electromagnetic wave irradiation is equal, and further the drying time for each droplet is equal. As a result, variations in the film thickness profile between the films can be suppressed. For example, when an organic layer is formed on a substrate used in an organic EL display device, the history from application to drying of droplets in each dot can be made the same, greatly reducing variation in drying between dots. Therefore, the display quality of the organic EL display device can be improved. In the present invention, the meaning of the term “substantially the same” is preferably a form that is evaluated to be substantially the same. However, as long as the effects of the present invention are exhibited, a form similar thereto As such, a form having a predetermined difference is included.

In the substrate manufacturing apparatus, the region where the thin film is formed is preferably defined by at least one of a method of defining by the partition and a method of defining by the difference in surface tension. That is, a form in which a partition wall (bank) for defining a droplet dropping position (film formation position) is formed on the substrate, a form in which the wettability of the liquid is controlled by performing a liquid repellent treatment on the substrate, and These combined forms are preferred. As the partition wall, any partition wall can be used as long as it can suppress the spread of the droplets. Examples of the partition wall include those having a cross-sectional shape of a quadrangle, T-shape, reverse taper shape, and the like. Further, the partition wall may be one whose liquid wettability is controlled by a liquid repellent treatment. As a form defined by the difference in surface tension, any form may be used as long as there is a difference in liquid wettability between the droplet dropping position (film forming position) of the substrate and the other region. According to these defining methods, it is possible to define the position where the droplets are attached more accurately. In this case, the shape of the liquid droplet when viewed from the film surface side does not need to be circular, and can be rectangular, oval, polygonal, or the like.

<Relationship between droplet drying and emission characteristics in organic EL elements>
In the droplet application method (inkjet method), it is very important how long the droplet is dried in the course of droplet drying. That is, when a film is formed by ejecting a plurality of droplets, there is always a time difference between the first ejected droplet and the last ejected droplet. If drying is performed at the same time, the time elapsed until drying differs for each droplet. Here, in the case where an organic layer is formed for each dot on a substrate used in an organic EL display device, the difference in the drying process of the organic layer of each dot means that the film thickness is different and used as a display device. At this time, this appears as a difference in the light emission threshold value, resulting in display unevenness. Moreover, the luminous efficiency and element lifetime in the organic EL display device have a very large correlation with the film thickness of the organic layer, and obtaining an appropriate and uniform film thickness is for obtaining an organic EL element with high efficiency and long life. It is a very important element.
If the substrate manufacturing apparatus of this invention is used, it will become possible to produce the organic EL element with the uniform film thickness distribution of the organic layer between each dot, and realization of a highly efficient and long-life organic EL element will be attained.

The present invention is also a substrate manufacturing method using the substrate manufacturing apparatus. According to such a substrate manufacturing method, since the droplets can be effectively dried by using the substrate manufacturing apparatus, it is possible to form a thin film with an in-plane film thickness distribution suppressed on the substrate. Is possible.

The present invention is also an electronic display device manufactured by the substrate manufacturing apparatus. Such an electronic display device includes a substrate on which a film thickness distribution in a plane is suppressed and a thin film with high film flatness is formed. For example, an organic EL display device, a color filter, a microlens array, an X-ray sensor, It is possible to improve the display quality, sensitivity distribution, and the like of the photosensitive sensor.
Of these, the electronic display device is preferably an electronic electroluminescence display device. Since the in-plane film thickness distribution of the organic layer is suppressed and the film flatness is high, an organic EL display device having a uniform light emission profile and having a high efficiency and a long life can be obtained.

Since the substrate manufacturing apparatus of the present invention is configured as described above, after the droplets are deposited on the substrate, the droplets deposited on the substrate by the droplet coating unit are sequentially irradiated by electromagnetic waves. Since it is possible to irradiate an electromagnetic wave from the electromagnetic wave irradiation unit without drying and to dry the film, it is possible to suppress the film thickness variation between the films due to the drying process of the droplets. According to such a substrate manufacturing apparatus of the present invention, for example, in the case where an organic layer is formed on a substrate used in an organic EL display device, it is possible to greatly suppress the variation in drying between dots. It is possible to form an organic layer with excellent uniformity of the film thickness, and when an electrode or the like is further formed to form an organic EL element, a uniform light emitting state can be obtained.

Hereinafter, the present invention will be described in more detail with reference to the drawings with reference to examples. However, the present invention is not limited only to these examples.

A substrate for an organic EL element in which an organic layer was formed on a substrate was produced by the substrate manufacturing apparatus of the present invention, and an organic EL element was produced using this.

<Structure of organic EL element>
First, the structure of the organic EL element produced in the example will be briefly described with reference to FIGS.
FIG. 3A is a schematic cross-sectional view showing the basic structure of the organic EL element produced in the example, and FIG. 3-B is a schematic plan view of the organic EL element shown in FIG.
As shown in FIGS. 3A and 3B, the organic EL element includes a support substrate 1 that supports the entire element, an organic layer 3 that includes a light emitting material, and a first for supplying a current to the organic layer 3. The electrode 2 and the second electrode 4, and the sealing material 5 are provided. The first electrode 2, the organic layer 3, and the second electrode 4 are laminated on the support substrate 1 in this order, and the entire surface thereof is further covered with a sealing material 5.

On the support substrate 1, at least one electrode is disposed, and the first electrode 2 is disposed here. The material of the support substrate 1 is not particularly limited, and examples thereof include those used in conventional organic EL elements. For example, inorganic materials such as quartz, soda glass, ceramic materials, polyimide, polyester, etc. Organic materials such as can be used.

Although it does not specifically limit as a material of the 1st electrode 2 and the 2nd electrode 4, Usually, one of these electrodes consists of a transparent material. The transparent material is not particularly limited, and examples thereof include those used in conventional organic EL elements. Examples thereof include inorganic materials such as indium-tin oxide (ITO), SnO ₂ , and Au thin films. Alternatively, organic materials such as polyaniline and polythiophene thin films can be used. In addition, the material of the other electrode is not particularly limited, and examples include those used in conventional organic EL elements. For example, a single metal, an alloy, or a laminate thereof is used. Can do. As this metal, for example, magnesium, lithium, calcium, silver, aluminum, indium, cesium, copper, nickel, LiF, or the like can be used.

The organic layer 3 may have a single-layer structure including only a light-emitting layer, or may have a stacked structure including a light-emitting layer. Examples of this laminated structure include a structure in which a hole injecting and transporting layer and a light emitting layer are sequentially laminated, a structure in which a light emitting layer and an electron injecting and transporting layer are sequentially laminated, a hole injecting and transporting layer, a light emitting layer, and an electron injecting and transporting layer. A structure in which the layers are stacked in order is mentioned. Note that the light emitting layer may include a charge (electron or hole) transport material, a charge (electron or hole) injection material, and a charge (electron or hole) limiting material, for example, an electron transport light emission including an electron transport material. It may be a layer or the like. The hole injection / transport layer may be divided into a hole injection layer and a hole transport layer, and the electron injection / transport layer may be divided into an electron injection layer and an electron transport layer.

As a material of the light emitting layer included in the organic layer 3, for example, a light emitting material containing a light emission assisting agent, a charge transporting material, an additive (such as a donor or an acceptor), a light emitting dopant, or the like can be used. As the light emitting material of the light emitting layer, a known light emitting material used in a conventional organic EL element can be used. Such light-emitting materials can be classified into types such as a low-molecular light-emitting material, a polymer light-emitting material, and a precursor of the polymer light-emitting material. More than one kind of materials may be used in combination. Moreover, as a solvent used when forming each layer such as a light emitting layer constituting the organic layer 3 by applying droplets, a solvent that can dissolve or uniformly disperse the material of each layer is selected. In addition, another solvent may be added regardless of the insolubility of the material. An ink jet device, a dispenser, or the like can be used for applying the droplets.

The sealing material 5 is provided to prevent moisture and oxygen from touching the organic layer 3 as much as possible. The sealing method by this sealing material 5 is not specifically limited, For example, the sealing method by the film-forming of the organic material or the inorganic material excellent in waterproofness and moisture proofness, and the sticking of a glass cap or a metal cap A sealing method or the like can be used. Further, a getter material may be disposed in a sealed space between the glass cap or the metal cap and the substrate, and adsorption of oxygen, moisture, and the like may be performed by the getter material to prevent oxidation and moisture absorption inside the sealed interior.

<Production of organic EL element>
FIG. 1 is a schematic side view showing the main part of the substrate manufacturing apparatus of the present invention used in the examples. FIG. 2 is a schematic side view showing a state in which electromagnetic waves are applied to the droplets from the substrate manufacturing apparatus of FIG.
An ink jet device was used as the droplet applying unit 6. Moreover, as a liquid discharged from the droplet application part 6, a PEDOT (polyethylenedioxythiophene) / PSS (polystyrene sulfonic acid) solution is used as a material for a hole transport layer, and xylene or tetralin is used as a material for a light emitting layer. Although a solvent and a polymer light-emitting material such as MEH-PPV or polyfluorene soluble in these solvents are used, it is not limited to these materials and solvents. The liquid physical properties were those usually used for inkjet discharge, the viscosity was adjusted to 5 to 15 mPa · s, and the surface tension was adjusted to 30 to 35 mN / m.

As shown in FIG. 1, as the electromagnetic wave irradiation unit 7, a device that irradiates infrared rays is used in parallel with the inkjet device 6. By arranging in this way, it is possible to continuously perform droplet application and infrared irradiation. In addition, although the infrared laser which can be used simply was used as the electromagnetic wave irradiation part 7 here, as long as it can accelerate | stimulate drying as electromagnetic waves, it is not limited to infrared rays.
In addition, it is also possible to use a point condensing type heating device that makes a xenon lamp having an emission line having a wavelength of about 0.8 to 1 μm incident on an optical fiber and then condenses it on an object. However, the wavelength is not particularly limited as long as it includes the wavelength range that is absorbed by the irradiation target.

As shown in FIG. 2, in the substrate manufacturing apparatus, the substrate 10 placed on the substrate stage 9 is sequentially sent relative to the ink jet head, and droplets are ejected from the nozzles of the ink jet device 6. It adheres to a predetermined position on 10.
In this embodiment, a pattern substrate provided with partition walls (banks) 1a for containing droplets is used, and specifically, as shown in FIG. The liquid droplets were sequentially discharged into each partition wall (bank) 1a. The dot pitch is 200 μm, but is not particularly limited including the dot shape.

Further, the substrate stage 9 is sequentially sent, and immediately after applying the droplet, the electromagnetic wave irradiation unit (infrared irradiation device) 7 irradiates the infrared ray 11 to change the shape of the droplet 12 immediately after the substrate is attached to the shape of the droplet 13 spreading after the substrate is attached. In this state, the droplet was dried and a film 14 was formed.
Here, when the drying process is performed after the droplets are ejected to the entire surface of the substrate 10 without immediately drying with the infrared rays 11, the droplets are sequentially dried by the infrared irradiation device 7 after being applied by the inkjet device 6. As a result of comparison with the case (in this example), the latter case was able to suppress the film thickness difference between the dots 15a. This is because the solvent evaporates from each droplet after droplet application, but the rate at which each droplet evaporates differs immediately when left without using the infrared irradiation device 7, that is, by drying. In contrast to the film thickness difference, when the infrared irradiation device 7 is used immediately, the drying starts immediately after the droplet application, so that each droplet becomes a uniform drying process, and the film thickness difference is reduced. This is because it is difficult to occur.
In this embodiment, the irradiation intensity of the electromagnetic wave 11 with respect to each droplet after the droplet application is constant, but it may be controlled so that the order is small → large → small. Since extreme heating and cooling can be suppressed, stable drying can be performed. In such a case, a plurality of electromagnetic wave irradiation sections 7 after applying the droplets may be provided. The present invention can also be applied to cases where the irradiation time is insufficient but the irradiation intensity cannot be increased. In order to suppress the film thickness distribution, the irradiation intensity may be changed from the first droplet to the last droplet. For example, the irradiation intensity is gradually increased from the first half to the second half, and vice versa. It may be made smaller.
Furthermore, the form of the nozzles in the ink jet apparatus 6 may be either a plurality of nozzles (a plurality of ejection holes) or a single nozzle (a single ejection hole), and the form of the head may be a plurality of heads or a singular. Any of the heads may be used, but from the viewpoint of productivity, a form of a plurality of heads with a plurality of nozzles is preferable. In this case, it is more preferable that the electromagnetic wave irradiation unit 7 corresponding to each nozzle is juxtaposed.
In preparing the device, the atmosphere for coating and drying is preferably performed in an inert gas atmosphere rather than in the air, and the moisture concentration is on the order of ppm or less, and the oxygen concentration is on the order of ppm or less. It is preferable.

The film 14 produced using the substrate manufacturing apparatus had a high film flatness with suppressed film thickness distribution between the dots 15a. Furthermore, when an organic EL display device having a structure comprising an anode / hole transport layer / polymer light emitting layer / cathode was produced, the uniformity of light emission could be improved.
The planar shape of the dot is not particularly limited, and may be a rectangle, an ellipse, a polygon, or the like. One dot may be used as one film forming area, or a plurality of dots may be combined into one film forming area. As an example of a dot arrangement different from that of the organic EL element produced in the example, FIGS. 4A and 4B show a basic structure of another example of the organic EL element.

It is a side surface schematic diagram which shows the principal part of the board | substrate manufacturing apparatus of this invention used in the Example. It is a side surface schematic diagram which shows a mode that electromagnetic waves are irradiated with respect to a droplet from the board | substrate manufacturing apparatus of FIG. It is a cross-sectional schematic diagram which shows the basic structure of the organic EL element produced in the Example. FIG. 3 is a schematic plan view of the organic EL element shown in FIG. It is a cross-sectional schematic diagram which shows the basic structure of another example of an organic EL element. FIG. 4 is a schematic plan view of the organic EL element shown in FIG.

Explanation of symbols

1: support substrate 1a, 1b: partition wall 2: first electrode 3: organic layer 4: second electrode 5: sealing material 6: droplet application part (inkjet device)
7: Electromagnetic wave irradiation unit 9: Substrate stage 10: Substrate 11: Electromagnetic wave (infrared ray)
12: Droplet immediately after substrate attachment 13: Droplet spread after substrate attachment 14: Film 15a, 15b: Dot

Claims (7)

A substrate manufacturing apparatus used in a process of forming a thin film by attaching a droplet from a droplet application unit on a substrate and irradiating an electromagnetic wave by an electromagnetic wave irradiation unit,
The substrate manufacturing apparatus irradiates electromagnetic waves sequentially after depositing droplets on the substrate. 2. The substrate manufacturing apparatus according to claim 1, wherein the substrate manufacturing apparatus irradiates the droplets with electromagnetic waves for a time interval at which a droplet starts to adhere and spread on the substrate. 3. The substrate manufacturing apparatus according to claim 1, wherein the substrate manufacturing apparatus has a droplet applying unit and an electromagnetic wave irradiation unit installed at an interval. The time from when a droplet is deposited on the substrate to when the electromagnetic wave is irradiated and the time when the electromagnetic wave is irradiated are substantially the same for each droplet. Board manufacturing equipment. A substrate manufacturing method using the substrate manufacturing apparatus according to claim 1. An electronic display device manufactured by the substrate manufacturing apparatus according to claim 1. The electronic display device according to claim 6, wherein the electronic display device is an electronic electroluminescence display device.

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