JP2006185747A - Manufacturing method of display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a display device capable of improving display performance and excellent in manufacturing yield. <P>SOLUTION: The manufacturing method of the display device comprises a process in which a first electrode 60 of independent island shape is formed at each picture element in the display area on a substrate, a process in which a barrier rib 70 for separating each picture element is formed, a process in which the surface of the first electrode 60 exposed from the barrier rib 70 is megasonic-cleaned, a process in which an organic active layer 64 is formed on the first electrode 60 of each picture element, and a process in which a second electrode 66 common for all picture elements is formed on the organic active layer 64. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a display device.

  In recent years, organic electroluminescence (EL) display devices have attracted attention as flat display devices. Since this organic EL display device is a self-luminous element, it has a wide viewing angle, can be thinned without requiring a backlight, has low power consumption, and has a high response speed. ing.

  Because of these characteristics, organic EL display devices are attracting attention as potential candidates for next-generation flat display devices that can replace liquid crystal display devices. Such an organic EL display device is configured by arranging organic EL elements holding an organic active layer containing an organic compound having a light emitting function between an anode and a cathode as an array substrate in a matrix.

In the process of manufacturing a substrate constituting such a flat display device, a step of cleaning the substrate for the purpose of removing particles on the substrate and removing impurities that affect the chemical or electrical characteristics of the substrate surface Is essential. For example, scrub cleaning, ultrasonic cleaning, megasonic cleaning, and the like can be cited as a method for cleaning a substrate constituting a liquid crystal display device as a flat display device (see, for example, Patent Document 1).
JP 11-142827 A

  In the process of manufacturing a substrate provided with an organic EL element, for example, after forming an anode for each pixel, an organic active layer and a cathode are formed. In such a manufacturing process, a process that easily contaminates the anode surface, for example, a process of forming a partition for separating each pixel, is required after the anode is formed until the organic active layer is formed on the surface. There is a case.

  In this partition wall forming step, after the resin material is disposed on the entire surface of the substrate including the surface of the anode, the partition wall is formed by patterning the resin material by a photolithography process, and the resin material is removed from the anode surface. However, after such a resin material patterning step, particles may remain on the surface of the anode or the surface characteristics may be adversely affected. These may cause a short circuit between the anode and the cathode and increase in resistance between the anode and the organic active layer, and may cause a decrease in display performance and a decrease in manufacturing yield. For this reason, it is required to clean the surface of the anode by an appropriate technique.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a method for manufacturing a display device that can improve display performance and has a good manufacturing yield.

A method of manufacturing a display device according to an aspect of the present invention is as follows.
Forming an independent island-shaped first electrode in each pixel in a display area on the substrate;
Forming a partition for separating each pixel;
Megasonic cleaning the surface of the first electrode exposed from the partition;
Forming a photoactive layer on the first electrode of each pixel;
Forming a second electrode common to all pixels on the photoactive layer.

  According to the present invention, it is possible to improve the display performance and provide a method for manufacturing a display device with a good manufacturing yield.

  A display device manufacturing method according to an embodiment of the present invention will be described below with reference to the drawings. In this embodiment, a self-luminous display device such as an organic EL (electroluminescence) display device will be described as an example of the display device.

  As shown in FIGS. 1 and 2, the organic EL display device 1 includes an array substrate 100 having a display area 102 for displaying an image. The display area 102 of the array substrate 100 is composed of a plurality of pixels PX (R, G, B) arranged in a matrix.

  Further, the array substrate 100 has a plurality of scanning lines Ym (m = 1, 2,...) Arranged along the row direction of the pixels PX (that is, the Y direction in FIG. 1) and a direction substantially orthogonal to the scanning lines Ym. In other words, a plurality of signal lines Xn (n = 1, 2,...) Arranged along (the X direction in FIG. 1) and a power supply line for supplying power to the first electrode 60 side of the organic EL element 40. P.

  Furthermore, the array substrate 100 has a scanning line driving circuit 107 that supplies a scanning signal to each of the scanning lines Ym and a signal that supplies a video signal to each of the signal lines Xn in the peripheral area 104 along the outer periphery of the display area 102. A line driving circuit 108. All the scanning lines Ym are connected to the scanning line driving circuit 107. All signal lines Xn are connected to the signal line driving circuit 108.

  Each pixel PX (R, G, B) is supplied via a pixel switch 10 and a pixel switch 10 having a function of electrically separating an on-pixel and an off-pixel and holding a video signal to the on-pixel. The driving transistor 20 supplies a desired driving current to the display element based on the video signal, and the storage capacitor element 30 holds the gate-source potential of the driving transistor 20 for a predetermined period. The pixel switch 10 and the drive transistor 20 are constituted by, for example, thin film transistors, and here, polysilicon is used for their semiconductor layers.

  Each pixel PX (R, G, B) includes an organic EL element 40 (R, G, B) as a display element. That is, the red pixel PXR includes an organic EL element 40R that mainly emits light corresponding to the red wavelength. The green pixel PXG includes an organic EL element 40G that mainly emits light corresponding to the green wavelength. The blue pixel PXB includes an organic EL element 40B that mainly emits light corresponding to the blue wavelength.

  The configurations of the various organic EL elements 40 (R, G, B) are basically the same. That is, as shown in FIG. 2, the array substrate 100 includes a plurality of organic EL elements 40 disposed on the wiring substrate 120. Note that the wiring substrate 120 is formed on an insulating support substrate such as a glass substrate or a plastic sheet, the pixel switch 10, the driving transistor 20, the storage capacitor element 30, the scanning line driving circuit 107, the signal line driving circuit 108, and various wirings (scanning). Line, signal line, power supply line, etc.).

  The organic EL element 40 includes a first electrode 60 that is arranged in a matrix and is formed in an independent island shape for each pixel PX, and a second electrode that is opposed to the first electrode 60 and is formed in common for all the pixels PX. 66, and a photoactive layer (here, organic active layer) 64 held between the first electrode 60 and the second electrode 66.

  The first electrode 60 constituting the organic EL element 40 is disposed on the insulating film on the surface of the wiring substrate 120 and functions as an anode.

  The organic active layer 62 includes a light emitting layer. The organic active layer 62 may include layers other than the light emitting layer, and may be configured by, for example, a two-layer structure of a hole transport layer formed in common for each color and a light emitting layer formed in each color pixel. In addition, a hole injection layer, a blocking layer, an electron transport layer, an electron injection layer, a buffer layer, and the like may be included, or a layer in which these are functionally combined may be included. In the organic active layer 62, the light emitting layer may be an organic material, and layers other than the light emitting layer may be an inorganic material or an organic material. The light-emitting layer is formed of an organic compound having a light-emitting function that emits red, green, or blue light.

  The second electrode 66 is disposed on the organic active layer 64 in common with each organic EL element 40. The second electrode 66 is formed of a metal material having an electron injection function, for example, a metal material such as ITO (Indium Tin Oxide) or IZO (Indium Zinc Oxide), and functions as a cathode.

  In addition, the array substrate 100 includes a partition wall 70 that separates the pixels RX (R, G, B) for each adjacent color in the display area 102. The partition wall 70 is preferably formed so as to separate each pixel. Here, the partition wall 70 is arranged in a lattice shape along the periphery of each first electrode 60, and the opening shape of the partition wall exposing the first electrode 60 is used. Is formed in a rectangular shape. The partition wall 70 is made of a resin material.

  The array substrate 100 having such a configuration is hermetically sealed with a sealing body 200 on the main surface side including the organic EL elements 40.

  Next, a method for manufacturing the display device having the above-described configuration will be described.

  First, as shown in FIG. 3A, in the display area 102 on the wiring substrate 120, an independent island-shaped first electrode 60 is formed for each pixel. That is, the first electrode 60 is formed by patterning a metal film functioning as an anode on one main surface side of the wiring board 120. The first electrode 60 may be generally formed by a photolithography process or may be formed by a mask sputtering method.

  Subsequently, as shown in FIG. 3B, a partition wall 70 for separating each pixel is formed. That is, a photosensitive resin material such as an acrylic type positive tone resist is formed on the entire main surface of the wiring substrate 120 including the first electrode 60, and then patterned by a photolithography process, and then at 220 ° C. for 60 minutes. Is fired. Thereby, a grid-like partition wall 70 surrounding each pixel is formed.

  The wiring substrate 120 with the partition wall 70 formed in this way is cleaned in a cleaning apparatus 400 as shown in FIG. 4, for example. The cleaning apparatus 400 shown here includes a first cleaning unit 401 that uses an organic solvent as a cleaning liquid, and a second cleaning unit 401 that uses an inorganic solvent as a cleaning liquid. If it is not necessary to use separate systems for exhaust and drainage, the cleaning device 400 may be composed of a single cleaning unit.

  In the first cleaning unit 401, the organic solvent used as the cleaning liquid is preferably selected in consideration of the composition of the removal target to be removed. For example, tetramethylammonium hydroxide, glycol ether, alkanolamine Can be selected from.

  In the second cleaning unit 402, the inorganic solvent used as the cleaning liquid is preferably selected in consideration of the composition of the removal target to be removed. For example, functional water such as ammonia water or ammonia-added water is used. Is possible. Since such functional water has a zeta potential close to that of the removal object, the removal ability of the removal object is high.

  In the cleaning apparatus 400 having such a configuration, as shown in FIG. 3C, the surface 60A of the first electrode 60 exposed from the partition wall 70 is cleaned.

  That is, the wiring board 120 on which the partition walls 70 accumulated in the accumulation unit 403 are formed is transferred to the first cleaning unit 401 by the substrate transfer robot 405 disposed in the work area 404. In the first cleaning unit 401, the main surface side of the wiring board 120 is cleaned using a predetermined organic solvent.

  Thereafter, the wiring board of the first cleaning unit 401 is transferred to the second cleaning unit 402 by the substrate transfer robot 405. The second cleaning unit 402 performs megasonic cleaning at a high frequency of about 1 to 1.5 MHz using the main surface side of the wiring board 120. Various conditions for the megasonic cleaning are set in consideration of the material of the object to be cleaned (first electrode 60) so as not to damage the first electrode 60. In this embodiment, the cleaning liquid is functional water, and the frequency is 1.3 MHz.

  This makes it possible to remove particles from the surface 60A even if the surface 60A of the first electrode 60 is contaminated in a previous process such as a process of forming the partition wall 70, and the surface characteristics of the first electrode 60 are improved. Can be improved.

  Subsequently, as shown in FIG. 3D, an organic active layer 64 is formed on the first electrode 60 in each pixel. That is, when a polymer material is selected as the organic active layer 64 including a hole buffer layer in addition to the light emitting layer, it can be applied by a method such as an inkjet method. Further, when a low molecular material is selected as the organic active layer 64, it can be formed by a method such as vapor deposition through a mask having a pixel pattern.

  Subsequently, as shown in FIG. 3E, a second electrode 66 common to all the pixels is formed on the organic active layer 64. That is, the second electrode 66 is formed by forming a metal film functioning as a cathode on one main surface side of the wiring substrate 120 on which the organic active layer 64 is disposed by sputtering or the like.

  By such a process, the organic EL element 40 is formed.

  According to the organic EL element 40 manufactured by the manufacturing method as described above, it was possible to suppress the occurrence of display defects due to the contamination of the surface of the first electrode 60.

  It is desirable to perform the cleaning process in the first cleaning unit 401 and the second cleaning unit 402 as described above while rotating the wiring board 120 in a plane parallel to the main surface. Due to such rotation of the wiring substrate 120, centrifugal force is also applied to the vibration of the cleaning liquid, so that the surface 60A of the first electrode 60 can be cleaned in a cleaner state.

  Further, in the cleaning process in the first cleaning unit 401 and the second cleaning unit 402 as described above, in addition to the rotation of the wiring board 120, the wiring board 120 has nozzles N for discharging the cleaning liquid as shown in FIG. It is desirable to perform the movement while moving in the radial direction R from the center O in the rotating plane. According to such a configuration, the cleaning apparatus can be downsized regardless of the substrate size as compared with the shower type unit.

  Further, in the above-described embodiment, the cleaning process using the organic solvent in the first cleaning unit 401 as the cleaning liquid performed before the megasonic cleaning process in the second cleaning unit 402 is not essential and is omitted. Also good. That is, as a process of cleaning the main surface of the wiring board 120, a sufficient cleaning effect can be expected only by megasonic cleaning.

  However, the step of forming the partition 70 before the step of forming the organic active layer 64 includes a step of baking after patterning the photosensitive resin material. By such a baking process, the remaining photosensitive resin material may be burned onto the surface 60 </ b> A of the first electrode 60. In addition, an oil component may adhere to the surface 60 </ b> A of the first electrode 60. For this reason, it becomes possible to remove effectively the residue of these photosensitive resin materials, an oil-fat component, etc. by adding the washing process by an organic solvent.

  Further, it has been confirmed that it is extremely effective to continuously perform the above-described megasonic cleaning after the cleaning with the organic solvent. That is, the foreign matter floating from the surface 60A of the first electrode 60 (or melted at the surface 60A) by the organic solvent can be removed by megasonic cleaning. For this reason, the surface 60A of the first electrode 60 immediately before the formation of the organic active layer 64 is in a very clean state, and the organic EL element 40 having good display performance can be formed.

  Further, as a cleaning process in the second cleaning unit 402, a cleaning process using hydrogen fluoride water as a cleaning liquid may be added before the cleaning process using functional water. According to such a cleaning process using hydrogen fluoride water, the oxide layer on the surface of the first electrode 60 can be lifted off, and the object to be removed is effectively removed by the subsequent cleaning process using functional water. Can be removed. For this reason, the surface 60A of the first electrode 60 is further cleaned. The concentration of hydrogen fluoride water used for this cleaning is about 0.3 to 1.0 wt%. Here, the cleaning is performed for 5 seconds using 0.5 wt% hydrogen fluoride water. After that, when megasonic cleaning was performed, the surface 60A of the first electrode 60 was in a very clean state.

  As described above, according to this embodiment, a process that easily contaminates the surface of the first electrode is required after the first electrode is formed and before the organic active layer is formed on the surface. Even if there is a case, it is possible to effectively remove impurities adhering to the surface of the first electrode by adding an appropriate cleaning process for cleaning the surface of the first electrode before forming the organic active layer. Become. Therefore, it is possible to sequentially form the organic active layer and the second electrode with the surface of the first electrode being clean, the display performance of the organic EL element can be improved, and the manufacturing yield can be improved. .

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the components without departing from the gist of the invention in the stage of implementation. Further, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, you may combine suitably the component covering different embodiment.

FIG. 1 is a diagram schematically showing a configuration of an organic EL display device according to an embodiment of the present invention. FIG. 2 is a cross-sectional view schematically showing the structure of one pixel of the organic EL display device shown in FIG. FIG. 3A is a diagram for explaining a manufacturing process for forming the organic EL display device, and shows a process of forming the first electrode. FIG. 3B is a diagram for explaining a manufacturing process for forming the organic EL display device, and shows a process of forming a partition. FIG. 3C is a diagram for explaining a manufacturing process for forming the organic EL display device, and is a diagram illustrating a process of megasonic cleaning the surface of the first electrode. FIG. 3D is a diagram for explaining a manufacturing process for forming the organic EL display device, and shows a process for forming the organic active layer. FIG. 3E is a diagram for explaining a manufacturing process for forming the organic EL display device, and is a diagram illustrating a process of forming the second electrode. FIG. 4 is a diagram illustrating a configuration example of the cleaning device. FIG. 5 is a diagram for explaining the rotation direction of the substrate and the movement direction of the nozzle in the megasonic cleaning.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Organic EL display apparatus, 10 ... Pixel switch, 20 ... Drive transistor, 30 ... Storage capacitor element, 40 ... Organic EL element, 60 ... 1st electrode, 64 ... Organic active layer, 66 ... 2nd electrode, 70 ... Partition , 100 ... Array substrate, 120 ... Wiring substrate, PX ... Pixel, 400 ... Cleaning device, 401 ... First cleaning unit, 402 ... Second cleaning unit

Claims (7)

Forming an independent island-shaped first electrode in each pixel in a display area on the substrate;
Forming a partition for separating each pixel;
Megasonic cleaning the surface of the first electrode exposed from the partition;
Forming a photoactive layer on the first electrode of each pixel;
Forming a second electrode common to all pixels on the photoactive layer. A method for manufacturing a display device, comprising:   The method of manufacturing a display device according to claim 1, wherein the megasonic cleaning step is performed while rotating the substrate.   3. The method of manufacturing a display device according to claim 2, wherein the megasonic cleaning step is performed while moving a nozzle for discharging a cleaning liquid in a radial direction within a plane in which the substrate rotates.   The method for manufacturing a display device according to claim 1, wherein the megasonic cleaning step uses ammonia water or ammonia-added water as a cleaning liquid.   The display according to claim 1, wherein the megasonic cleaning step includes a cleaning step using hydrogen fluoride water as a cleaning liquid and a cleaning step using ammonia water or ammonia-added water as a cleaning liquid. Device manufacturing method.   2. The method according to claim 1, further comprising a step of cleaning the surface of the first electrode with an organic solvent after the step of forming the partition walls and before the step of performing the megasonic cleaning. The manufacturing method of the display apparatus of description.   The method for manufacturing a display device according to claim 6, wherein the organic solvent includes any of tetramethylammonium hydroxide, glycol ether, and alkanolamine.

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