JP2018195388A - Manufacturing method of display device - Google Patents

Abstract

To provide a manufacturing method of a substrate for providing a display device with high reliability.SOLUTION: A manufacturing method disclosed herein includes steps of: forming a transistor on a substrate; forming, on the transistor, a pixel electrode which is electrically connected to the transistor and contains a conductive oxide; fabricating an array substrate by partially exposing a surface of the pixel electrode and forming a barrier for covering an end of the pixel electrode; and performing plasma treatment on the exposed surface of the pixel electrode. The plasma treatment is performed so that, when the array substrate is heated at 200°C for 30 minutes after the plasma treatment, the organic compound desorbed from the array substrate may have a total amount per array substrate unit area of 5.0 ng/cmor less.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a method for manufacturing a display device, for example, a method for manufacturing an organic electroluminescence display device.

  As typical thin displays, liquid crystal display devices and organic electroluminescence display devices (hereinafter referred to as organic EL display devices) are known. These display devices have a plurality of pixels formed on a substrate, and each pixel is provided with a display element such as a liquid crystal element or an organic EL element (hereinafter referred to as a light emitting element). A liquid crystal element or an organic EL element has a basic structure including a pair of electrodes and a layer containing a liquid crystal sandwiched between them or a light-emitting organic compound, and is driven by applying a voltage or passing a current between the pair of electrodes. Is done.

  In any display element, at least one of the pair of electrodes is configured to transmit visible light. A conductive oxide mainly composed of indium is used as a transparent conductive film for an electrode that transmits visible light. As a typical conductive oxide, a mixed oxide of indium and tin (ITO) or indium and zinc is used. A mixed oxide (IZO) may be mentioned. As disclosed in Patent Document 1, in many display devices, an array substrate is manufactured by forming an electrode including a conductive oxide as a pixel electrode in each pixel. A display device is manufactured by forming a display element on the array substrate. When the array substrate is manufactured, the surface of the pixel electrode can be cleaned by performing plasma treatment on the pixel electrode in the presence of a gas containing oxygen (see Patent Document 2). As a result, the influence of foreign matter remaining on the pixel electrode can be reduced, display quality and reliability of the display device can be improved, and a display device can be manufactured with high yield.

JP 2007-95759 A JP2015-122449A

  An object of one embodiment of the present invention is to provide a highly reliable display device and a method for manufacturing a substrate for manufacturing the display device.

One embodiment of the present invention is a method for manufacturing a display device. In this manufacturing method, a transistor is formed on a substrate, a pixel electrode which is electrically connected to the transistor and includes a conductive oxide is formed on the transistor, and a part of the surface of the pixel electrode is exposed. And forming an array substrate by forming a partition wall covering an end portion of the pixel electrode, and subjecting the exposed surface of the pixel electrode to plasma treatment. The plasma treatment is performed such that when the array substrate is heated at 200 ° C. for 30 minutes after the plasma treatment, the total amount of organic compounds desorbed from the array substrate per unit area of the array substrate is 5.0 ng / cm ² or less.

  One embodiment of the present invention is a method for manufacturing a display device. In this manufacturing method, a transistor is formed on a substrate, a pixel electrode which is electrically connected to the transistor and includes a conductive oxide is formed on the transistor, and a part of the surface of the pixel electrode is exposed. And forming an array substrate by forming a partition wall covering an end portion of the pixel electrode, and subjecting the exposed surface of the pixel electrode to plasma treatment. The plasma treatment is performed in the presence of an oxygen-containing gas having a pressure of 80 Pa or more and an output of 170 W or less and 20 seconds or less.

1 is a schematic top view of a display device of the present invention. An example of the equivalent circuit of the pixel circuit of the display apparatus of this invention. FIG. 4 is a schematic cross-sectional view of a pixel of a display device of the present invention. FIG. 6 is a schematic cross-sectional view illustrating a method for manufacturing a display device of the present invention. FIG. 6 is a schematic cross-sectional view illustrating a method for manufacturing a display device of the present invention. The current-voltage characteristic of the light emitting element of an Example. The time-dependent change of the luminance of the light emitting element of the example. The relationship between the relative intensity | strength of the plasma processing of the array substrate of an Example, and the detection amount of the discharge | released organic compound. The relationship between the drive voltage with respect to the detection amount of an organic compound and reliability in the light emitting element of an Example. The relationship between the drive voltage with respect to the detection amount of an organic compound and reliability in the light emitting element of an Example. The relationship between the drive voltage with respect to the detection amount of an organic compound and reliability in the light emitting element of an Example. The relationship between the drive voltage with respect to the detection amount of an organic compound and reliability in the light emitting element of an Example.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention can be implemented in various modes without departing from the gist thereof, and is not construed as being limited to the description of the embodiments exemplified below.

  In order to make the explanation clearer, the drawings may be schematically represented with respect to the width, thickness, shape, and the like of each part as compared to the actual embodiment, but are merely examples and limit the interpretation of the present invention. Not what you want. In this specification and each drawing, elements having the same functions as those described with reference to the previous drawings may be denoted by the same reference numerals, and redundant description may be omitted.

  In the present specification and claims, when a plurality of films are formed by processing a certain film, the plurality of films may have different functions and roles. However, the plurality of films are derived from films formed as the same layer in the same process and have the same material. Therefore, these plural films are defined as existing in the same layer.

  In the present specification and claims, when expressing a mode in which another structure is arranged on a certain structure, the expression “above” means that it touches a certain structure unless otherwise specified. In addition, both the case where another structure is arranged directly above and the case where another structure is arranged via another structure above a certain structure are included.

  In the present specification and claims, the expression “a structure is exposed from another structure” means an aspect in which a part of a structure is not covered by another structure. The part which is not covered with the structure includes an aspect covered with another structure.

<First Embodiment>
[1. overall structure]
FIG. 1 shows a schematic top view of a display device 100 according to one embodiment of the present invention. As illustrated in FIG. 1, the display device 100 includes a substrate 102, a plurality of pixels 104 formed on the substrate 102, and a scanning line driver circuit 108. The plurality of pixels 104 are arranged in a matrix and form a display area 106. The display region 106 and the scan line driver circuit 108 are sandwiched and sealed between the substrate 102 and the counter substrate 116 not shown in FIG. A wiring (not shown) extends from the display area 106 and the scanning line driving circuit 108 to one side of the substrate 102 and is exposed at an end portion of the substrate 102 to form a terminal 112. The terminal 112 can be electrically connected to a flexible printed circuit (FPC) substrate 114, and a driver IC 110 for controlling the pixel 104 is mounted on the FPC 114. Note that the driver IC 110 may be mounted on the substrate 102 without being provided on the FPC 114, or a driver circuit may be formed on the substrate 102 instead of the driver IC 110 by using the formation process of the scanning line driver circuit 108. Good.

  Each pixel 104 incorporates a display element and a pixel circuit for controlling the display element. The pixel circuit includes various elements such as a transistor and a capacitor, and is controlled by a signal supplied from an external circuit (not shown) via the scanning line driving circuit 108 and the driver IC 110. The display element is controlled by the pixel circuit, and an image is displayed in the display area 106. Hereinafter, an example in which a light emitting element is used as a display element will be described.

  FIG. 2 shows an example of a pixel circuit as an equivalent circuit. In the example shown here, each pixel circuit includes a first scanning line 120, a second scanning line 122, a reset signal line 123, a third scanning line 124, and a driver IC 112 side extending from the scanning line driving circuit 108. Are electrically connected to wiring such as a video signal line 126 and a power supply line 128 that extend from the line. In addition to the light emitting element 150, the pixel circuit shown here has four capacitors, a switching transistor 130, an output transistor 132, a driving transistor 134, and a reset transistor 136, and a storage capacitor 140 and an additional capacitor 142. Yes. These are directly or indirectly connected to the wiring described above. A current is supplied to the anode of the light emitting element 150 from a high potential power supply line PVDD connected to the power supply line 128. The supplied current contributes to the light emission of the light emitting element 150 and flows to the low potential power line PVSS connected to the cathode side. The pixel circuit is not limited to the configuration illustrated in FIG. 2, and pixel circuits having various configurations can be applied to the pixel 104.

[2. Cross-sectional structure]
The structure of the display device 100 is described with reference to cross-sectional views of the pixels 104. In the schematic cross-sectional view shown in FIG. 3, two pixels 104 are shown. In the pixel circuit shown in FIG. Is shown in FIG.

2-1. Array substrate The substrate 102 has a function of supporting a pixel circuit formed thereon, and can include glass, quartz, or a polymer. The counter substrate 116 can also contain a material similar to that of the substrate 102. By using a polymer such as polyimide, polyamide, or polycarbonate for the substrate 102 or the counter substrate 116, flexibility can be imparted to the display device 100, and a so-called flexible display can be provided.

  The driving transistor 134 and the storage capacitor 140 are disposed on the substrate 102 through the undercoat 160. The undercoat 160 has a function of preventing impurities from entering from the substrate 102. When the substrate 102 is a polymer, it also plays a role of preventing moisture from entering from the outside.

  The driving transistor 134 includes a semiconductor film 162, a gate insulating film 164, a gate electrode 166, a first interlayer film 168, source / drain electrodes 170 and 172, and the like. The semiconductor film 162 can include a channel region 162a that overlaps with the gate electrode 166, a pair of low-concentration impurity regions 162b that sandwich the channel region 162a, and a high-concentration impurity region 162c that sandwiches the low-concentration impurity region 162b. Source / drain electrodes 170, 172 are electrically connected to high concentration impurity region 162c.

  The storage capacitor 140 is part of the semiconductor film 162 (high-concentration impurity region 162c), the gate insulating film 164 thereover, and the gate electrode 166, and is present in the same layer as the capacitor electrode 174 that is electrically connected to the gate electrode 166. , A first interlayer film 168 on the capacitor electrode 174, and a part of the source / drain electrode 172. The gate insulating film 164 and the first interlayer film 168 function as a dielectric of the storage capacitor 140.

  A second interlayer film 176 may be provided on the driving transistor 134 and the storage capacitor 140 as an arbitrary configuration. For the undercoat 160, the gate insulating film 164, the first interlayer film 168, and the second interlayer film 176, for example, an inorganic compound containing silicon can be used. Specifically, it is formed of one or a plurality of inorganic films selected from a silicon nitride film, a silicon oxide film, a silicon nitride oxide film, and a silicon oxynitride film.

  A planarizing film 178 is further provided on the driving transistor 134 and the storage capacitor 140. The planarization film 178 absorbs unevenness caused by the semiconductor elements such as the driving transistor 134 and the storage capacitor 140, and provides a flat surface. The planarization film 178 can include a polymer, and examples of the polymer include acrylic resin, epoxy resin, polysiloxane, polyimide, and polyamide.

  An opening reaching the source / drain electrode 172 is provided in the planarization film 178 and the second interlayer film 176, and the connection electrode 180 covering the opening and a part of the upper surface of the planarization film 178 is connected to the source / drain electrode 172. It is provided to touch. An additional capacitor electrode 182 is further provided on the planarizing film 178, and an insulating film 184 is formed so as to cover the connection electrode 180 and the additional capacitor electrode 182. The insulating film 184 can be formed using the above-described silicon-containing inorganic compound, and typically silicon nitride is used. The insulating film 184 does not cover a part of the connection electrode 180 in the opening provided in the planarization film 178 and exposes the bottom surface of the connection electrode 180. Thus, electrical connection between the pixel electrode 152 and the source / drain electrode 172 provided on the connection electrode 180 is possible. The insulating film 184 may be provided with an opening 186 for allowing contact between the partition wall 190 provided thereon and the planarization film 178. Note that the formation of the connection electrode 180 and the opening 186 is arbitrary. By providing the connection electrode 180, oxidation of the surface of the source / drain electrode 172 can be prevented in the subsequent process, and an increase in contact resistance due to oxidation can be suppressed. The opening 186 can function as an opening for discharging impurities such as water and oxygen from the planarization film 178, so that the reliability of the semiconductor element and the light-emitting element 150 in the pixel circuit can be improved.

  On the insulating film 184, the pixel electrode 152 of the light emitting element 150 is provided so as to cover the connection electrode 180 and the additional capacitor electrode 182. The insulating film 184 is sandwiched between the additional capacitor electrode 182 and the pixel electrode 152, and the additional capacitor 142 is constructed by this structure. The potential of the gate electrode 166 can be stabilized by the capacitance of the additional capacitor 142 and the storage capacitor 140. The pixel electrode 152 is shared by the additional capacitor 142 and the light emitting element 150.

  A conductive oxide such as ITO or IZO can be used for the pixel electrode 152. Accordingly, light emitted from the light emitting element 150 can be extracted through the pixel electrode 152. On the other hand, when light emitted from the light-emitting element 150 is extracted from the side opposite to the pixel electrode 152, a pixel electrode is formed using a stack of an electrode (reflective electrode) that reflects visible light and a conductive oxide provided thereon. 152 can be formed. In this case, the reflective electrode can include a highly reflective metal such as aluminum or silver, or an alloy thereof. When the pixel electrode 152 is used as an anode, holes are injected from the pixel electrode 152 into the EL layer 154 formed thereon. By using a stacked structure in which a conductive oxide is provided over a reflective electrode for the pixel electrode 152, good hole injecting property can be obtained.

  A partition wall 190 that covers an end portion of the pixel electrode 152 is provided on the pixel electrode 152. The pixel electrode 152 is exposed from the partition 190 except for the portion covered with the partition 190. In other words, the partition 190 is an insulating film having an opening, and the pixel electrode 152 is exposed from the partition 190 in the opening and is in contact with an electroluminescent layer (hereinafter, EL layer) 154 described later. The partition wall 190 can include a polymer such as an acrylic resin or an epoxy resin, and electrically insulates between adjacent pixels 104, and includes openings provided in the planarization film 178, the additional capacitor electrode 182, the pixel electrode 152, and the like. It has a function of absorbing irregularities caused by the above. The substrate 102 on which the partition walls 190 are formed is called an array substrate.

2-2. The EL layer 154 and the counter electrode 156 thereover are provided so as to cover the light-emitting element pixel electrode 152 and the partition wall 190. A light emitting element 150 is formed by the pixel electrode 152, the EL layer 154, and the counter electrode 156. In this specification and the claims, the EL layer 154 refers to the entire layer provided between the pixel electrode 152 and the counter electrode 156. Carriers (electrons, holes) are injected into the EL layer 154 from the pixel electrode 152 and the counter electrode 156, and light emission is obtained by a radiation deactivation process from an excited state caused by carrier recombination.

  In FIG. 3, the EL layer 154 is shown to have a single-layer structure, but the EL layer 154 can be composed of a plurality of layers, for example, a carrier injection layer, a carrier transport layer, a light emitting layer, a carrier block. A layer having various functions such as a layer and an exciton blocking layer can be formed in combination. The structure of the EL layer 154 may be the same between all the pixels 104, or the EL layer 154 may be formed so that the structure is different between adjacent pixels 104. For example, by forming the EL layer 154 so that the structure and material of the light emitting layer are different between the adjacent pixels 104, different light emission can be obtained from the adjacent pixels. In the case where the same EL layer 154 is used for all the pixels 104, a plurality of emission colors can be obtained by providing a color filter on the counter substrate 116.

  The counter electrode 156 can be formed using a material similar to that of the pixel electrode 152. In the case where light emission from the EL layer 154 is extracted through the counter electrode 156, the counter electrode 156 can be formed using a conductive oxide having a property of transmitting visible light, such as ITO or IZO. Alternatively, the counter electrode 156 may be formed by forming silver, aluminum, or an alloy thereof with a thickness capable of transmitting visible light.

2-3. Other Configurations As an optional configuration, a protective film (hereinafter referred to as a passivation film) 200 may be provided on the light emitting element 150. The structure of the passivation film 200 can be arbitrarily selected. For example, as shown in FIG. 3, a first layer 202 containing an inorganic compound, a second layer 204 containing an organic compound, and a third layer containing an inorganic compound. A stacked structure including the layer 206 can be applied. In this case, the inorganic compound containing silicon described above can be used as the inorganic compound. As the organic compound, a polymer such as an epoxy resin or an acrylic resin can be used.

  The counter substrate 116 is fixed to the substrate 102 with a sealant 210 so as to sandwich the light emitting element 150 and the pixel circuit. Accordingly, the light emitting element 150, the pixel circuit, the scanning line driving circuit 108, and the like are sealed. Although not shown, a touch sensor, a polarizing plate, or the like may be provided over the passivation film 200 or the counter substrate 116.

[3. Production method]
Hereinafter, a method for manufacturing the display device 100 will be described mainly focusing on a method for forming the pixel electrode 152.

  FIG. 4A is a schematic cross-sectional view of one of the two pixels illustrated in FIG. 3. Here, the driving transistor 134 and the storage capacitor 140 are formed over the substrate 102, and the planarization film 178 provided on these transistors, The state where the connection electrode 180, the additional capacitance electrode 182 and the insulating film 184 are formed is shown. Since these can be formed by applying known materials and methods, description thereof will be omitted.

3-1. Pixel Electrode The pixel electrode 152 is formed on the insulating film 184 so as to overlap with the additional capacitor electrode 182. At this time, the pixel electrode 152 is formed so as to be in contact with the connection electrode 180, whereby the pixel electrode 152 and the source / drain electrode 172 are electrically connected through the connection electrode 180 (FIG. 4B). The pixel electrode 152 includes the above-described conductive oxide or metal. The pixel electrode 152 can also have a laminated structure of metal and conductive oxide, such as a three-layer structure of conductive oxide / metal / conductive oxide, or a two-layer structure of metal / conductive oxide. can do. The conductive oxide may be formed by applying a sputtering method using a target containing ITO or IZO. The metal-containing film is formed by a chemical vapor deposition (CVD) method including a vapor deposition method, a sputtering method, or a metal organic chemical vapor deposition (MOCVD) method.

  Next, a partition wall 190 is formed so as to cover an end portion of the pixel electrode 152 (FIG. 4B). First, a photosensitive resin is used so as to cover the pixel electrode 152 and the insulating film 184 by a wet film formation method such as a spin coating method, an ink jet method, or a spray method using a polymer such as an acrylic resin, an epoxy resin, polyimide, or polysiloxane. Form. Thereafter, exposure and development using a photomask are performed to process the photosensitive resin. Specifically, the photosensitive resin is processed so that the surface of the pixel electrode 152 is exposed, the end of the pixel electrode 152 is covered, and the opening overlaps the surface of the pixel electrode 152. At this time, it is preferable that the end of the opening has a gentle taper shape. Accordingly, disconnection of the EL layer 154 and the counter electrode 156 formed over the partition wall 190 can be prevented. The array substrate is formed through the steps so far.

  Next, oxygen plasma treatment is performed on the array substrate (FIG. 4B). Specifically, plasma is generated in the presence of an oxygen-containing gas such as oxygen or nitrogen monoxide, and the surface of the pixel electrode 152 is processed using the obtained oxygen radicals or ions. The residue of the photosensitive resin remaining on the pixel electrode 152 due to the development process at the time of forming the partition wall 190 is removed by this plasma treatment, and the surface of the pixel electrode 152 can be cleaned. If the residue remains, it acts as a foreign substance for the light emitting element 150 and easily causes a short circuit between the pixel electrode 152 and the counter electrode 156. In the shorted pixel 104, a sufficient voltage cannot be applied to the EL layer 154, and carriers necessary for recombination cannot be injected. For this reason, the shorted pixel 104 does not emit light, and this pixel 104 is recognized as a dark spot (dark spot) during the display operation, and the display quality is greatly deteriorated. Therefore, by performing plasma treatment, display quality can be improved and a reduction in yield of the display device can be prevented.

However, as experimentally shown in the examples described later, an increase in the driving voltage of the light emitting element 150 is observed depending on the conditions of the plasma processing, and further, a decrease in reliability, that is, a decrease in lifetime occurs. For this reason, in the present embodiment, the plasma treatment is performed such that when the array substrate is heated at 200 ° C. for 30 minutes after the plasma treatment, the total amount per unit area of the organic compound desorbed from the array substrate is 0.1 ng / cm ^2. above 5.0 ng / cm ² or less, 1.0 ng / cm ² or more 5.0 ng / cm ² or less, or carried out such that 1.0 ng / cm ² or more 2.0 ng / cm ² or less.

  Here, the organic compound is mainly generated as a result of partial decomposition of the partition wall 190 by heating and / or exposure to plasma, and has a molecular weight of 100 or more and 200 or less. The organic compound may have a bridging bond between two bridgehead atoms. Further, it may have a bicyclo structure or a tricyclo structure. That is, you may have two or more fused aliphatic rings. Alternatively, it may have a double bond conjugated with an aromatic ring or may have a carbonyl group. For example, the organic compounds include methyl isobutyl ketone, alpha methyl styrene, 2,3,3a, 4,7,7a-hexahydro-4,7-methano-1H-indene, and 3-ethenyltricyclo [4,2,1, 0 (2,5)] nonane.

When methyl isobutyl ketone or α-methyl styrene is used as an index, the plasma treatment is carried out with a desorption amount of these compounds from the array substrate of 0.1 ng / cm ² or more and 1.0 ng / cm ² or less, 0.1 ng / cm, respectively. cm ² or more 0.5 ng / cm ² or less, or carried out such that 0.1 ng / cm ² or more 0.4 ng / cm ² or less. When 2,3,3a, 4,7,7a-hexahydro-4,7-methano-1H-indene is used as an index, the plasma treatment has a desorption amount of 0.1 ng / cm ² or more from the array substrate. 0 ng / cm ² or less, 0.3 ng / cm ² or more 1.0 ng / cm ² or less, or carried out such that 0.5 ng / cm ² or more 1.0 ng / cm ² or less. When 3-ethenyltricyclo [4,2,1,0 (2,5)] nonane is used as an index, the plasma treatment has a desorption amount from the array substrate of 0.1 ng / cm ² or more to 0.5 ng / cm. ² or less, 0.1 ng / cm ² or more 0.3 ng / cm ² or less, or carried out such that 0.1 ng / cm ² or more 0.2 ng / cm ² or less.

  By using such an organic compound as an index and selecting plasma processing conditions so that the above-described parameters are satisfied, it is possible to suppress a decrease in reliability of the display device 100 and to prevent an increase in driving voltage.

  More specific conditions for satisfying the parameters described above are as follows. When the distance between the electrodes is 20 mm and the frequency is 13.56 MHz in the plasma treatment, the pressure of the oxygen-containing gas is 80 Pa to 160 Pa, 80 Pa to 120 Pa, or 80 Pa to 100 Pa. The power applied between the electrodes is 50 W to 200 W, 100 W to 200 W, or 120 W to 170 W, and the treatment time is 1 second to 20 seconds.

  The amount of the organic compound desorbed from the array substrate is determined by adsorbing the desorbed organic compound to the porous polymer and then quantifying the gas generated by heating the porous polymer using a gas chromatograph mass spectrometer. Can be estimated.

  Subsequently, an EL layer 154 and a counter electrode 156 are sequentially formed so as to overlap with the pixel electrode 152 and the partition wall 190 (FIG. 5A). The EL layer 154 can be formed by an evaporation method or a wet film formation method, and the counter electrode 156 can be formed by an evaporation method or a sputtering method. Thereby, the light emitting element 150 is formed.

3-2. Other Configurations The passivation film 200 can be formed by any method. In the case of forming the above-described passivation film 200 having the three-layer structure, for example, after the first layer 202 is formed using a CVD method, the second layer 204 is formed by a wet film forming method, and then the third layer 202 is formed. The layer 206 may be formed by a CVD method (FIG. 5B). Thereafter, the counter substrate 116 is fixed on the substrate 102 using the sealant 210, whereby the display device 100 shown in FIG. 3 is obtained.

  As described above and as shown in the following embodiments, the array substrate is plasma-treated so as to satisfy the above-described parameters, thereby preventing an increase in driving voltage of the display device 100 and improving reliability. Can be improved. Further, residue of the residue on the pixel electrode 152 can be prevented by the plasma treatment, so that the yield of the display device 100 can be increased.

  In this embodiment, the results of studying the influence of plasma processing conditions on the driving voltage and reliability of the light emitting element 150 included in the display device 100 will be described.

[1. Experiment]
1-1. Plasma treatment An array substrate was produced according to the manufacturing method described above. The uppermost surface of the pixel electrode 152 of each pixel 104 contains IZO, and after the array substrate was fabricated, this surface was subjected to plasma treatment. The plasma treatment was performed by placing the array substrate on a stage that functions as one electrode. The frequency of the power source was 13.56 MHz. Oxygen was introduced into the chamber, the conditions of plasma treatment were adjusted by changing the pressure of oxygen and the output of the power source, and the influence of the strength of the plasma treatment conditions on the driving voltage and reliability of the light-emitting element 150 was examined. The pressure of oxygen and the output of the power source were as shown in Table 1, and the plasma treatment time was 20 seconds. Here, condition 5 is a blank experiment in which plasma treatment is not performed, and the intensity of the plasma treatment condition at this time was set to 0.2, and the relative intensity of conditions 1 to 4 was calculated based on this.

1-2. Analysis of Organic Compound After the plasma treatment, the array substrate was heated at 200 ° C. for 30 minutes to adsorb the generated gas to the porous polymer. Thereafter, the porous polymer was heated at 270 ° C., and the released gas was analyzed using a gas chromatograph mass spectrometer (model number QP-2010) manufactured by Shimadzu Corporation.

1-3. Production of Light-Emitting Element A light-emitting element 150 was produced by forming an EL layer 154 and a counter electrode 156 on a plasma-treated array substrate using an evaporation method. The structure of the EL layer 154 is as follows. For the counter electrode 156, an alloy of magnesium and silver was used. In the following structure, the hole injection layer is in contact with the pixel electrode 152, and the counter electrode 156 is provided on the electron injection layer.
Hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer

  In this example, a light-emitting element 150 that emits red and blue light (hereinafter referred to as a red light-emitting element and a blue light-emitting element, respectively) was manufactured as the light-emitting element 150.

1-4. Evaluation of Light-Emitting Element The current-voltage (IV) characteristics and reliability of the manufactured light-emitting element 150 were evaluated. Reliability was evaluated by measuring a change in luminance when the light emitting element 150 was driven with a constant current at a predetermined initial luminance. Here, the time when the luminance became 95% with respect to the initial luminance was defined as the lifetime of the light emitting element 150. The drive voltage described below is a voltage when the density of current flowing through the element is a predetermined value.

[2. result]
2-1. IV Characteristics FIG. 6 shows the IV characteristics and driving voltage of the red light emitting element. As shown in FIG. 6, it can be seen that the conditions of the plasma treatment do not significantly affect the shape of the IV curve itself. However, as shown in the following table, it was confirmed that the driving voltage tends to increase as the relative intensity of the plasma processing conditions increases.

2-2. Reliability FIGS. 7A and 7B show changes in luminance of the red light emitting element and the blue light emitting element over time. As shown in these figures, it has been found that the conditions of the plasma treatment affect the reliability of the light emitting element. That is, it was found that both the red light emitting element and the blue light emitting element increase the relative intensity of the plasma treatment and decrease the reliability. This tendency is more conspicuous in the case of the red light emitting element (see FIG. 7A), and the decrease in luminance with time was minimal in the condition 5 where the relative intensity of the plasma treatment conditions was the lowest.

2-3. Correlation between emitted gas and device characteristics In the analysis of the gas released from the array substrate after the plasma treatment, the following organic compounds were mainly detected. The organic compounds (a), (b), (c) and (d) are methyl isobutyl ketone, α-methyl styrene, 2,3,3a, 4,7,7a-hexahydro-4,7-methano-1H-, respectively. Indene, and 3-ethenyltricyclo [4,2,1,0 (2,5)] nonane.

  Plots of detected amounts of the organic compounds (a), (b), (c), and (d) with respect to the plasma treatment conditions are shown in FIGS. 8A to 8D, respectively. As is apparent from any of the figures, it was found that the detection amount of the organic compound increased as the intensity of the plasma treatment increased without depending on the type of the organic compound. The outermost surface of the array substrate is mainly composed of partition walls 190 and pixel electrodes 152. Since the partition walls 190 contain organic compounds, these organic compounds are considered to be derived from the partition walls 190. Since organic compounds were also detected from the array substrate that had not been subjected to plasma treatment, the partition wall 190 was partially decomposed by heating, and this decomposition is considered to be promoted by plasma.

  9 to 12 show the characteristics of the light-emitting element with respect to the detected amounts of the organic compounds (a), (b), (c), and (d), respectively. 9 to 12, the driving voltage of the red light emitting element and the reliability of the red light emitting element and the blue light emitting element are shown. FIGS. 9A, 9B, 10 A, 10 B, 11 A, 11 B, 12 A, and 12 showing reliability. In (B)), the driving time of the element when the luminance becomes 95% with respect to the initial luminance is plotted relative to the detected amount of the organic compound.

  For example, in the case of the organic compound (a), it was confirmed that the drive voltage increases as the detected amount of the organic compound increases (FIG. 9A). As described above, since the detected amount of the organic compound increases as the plasma processing intensity increases, it can be concluded that the driving voltage increases as the plasma processing intensity increases. Moreover, it turned out that reliability falls with the increase in the detection amount of an organic compound. For example, in the case of a red light emitting element (FIG. 9B), the reliability is greatly reduced by performing the plasma treatment, and the reliability is gradually lowered as the intensity of the plasma treatment is increased. In the case of a blue light emitting element (FIG. 9C), a large difference in reliability due to the presence or absence of plasma treatment is not observed. However, although the tendency is smaller than that of the red light emitting element, it has been confirmed that the reliability gradually decreases as the detection amount of the organic compound increases. A similar tendency was confirmed in the case of organic compounds (b) to (d) (FIGS. 10A to 12C).

As described above, by performing plasma treatment on the pixel electrode 152, generation of dark spots is suppressed and yield is improved. However, it has been experimentally confirmed that the driving voltage increases and the luminance decreases with time as the plasma treatment conditions become stronger. Therefore, in order to manufacture a display device having high reliability with high yield, it can be said that it is preferable to reduce the relative intensity of plasma treatment. Specifically, it is preferable to perform the plasma treatment in the presence of an oxygen-containing gas having a pressure of 80 Pa or more and an output of 170 W or less and 20 seconds or less. By adopting this condition, when the array substrate is heated at 200 ° C. for 30 minutes, the total amount of organic compounds that are desorbed from the array substrate per unit area of the array substrate is 5.0 ng / cm ² or less, or 2.0 ng. / Cm ² or less. As a result, it is possible to manufacture a display device that suppresses the generation of dark spots and has low power consumption and high reliability. That is, this plasma treatment can contribute to manufacturing a display device with high reliability and low power consumption at a high yield.

  The embodiments described above as the embodiments of the present invention can be implemented in appropriate combination as long as they do not contradict each other. Also, those in which those skilled in the art have appropriately added, deleted, or changed the design based on the display device of each embodiment, or those in which processes have been added, omitted, or changed in conditions are also included in the present invention. As long as the gist is provided, it is included in the scope of the present invention.

  In this specification, the case of an EL display device is mainly exemplified as a disclosure example. However, as another application example, an electronic paper type display having another self-luminous display device, a liquid crystal display device, an electrophoretic element, or the like. Any flat panel display device such as a device may be used. Further, the present invention can be applied without particular limitation from small to medium size.

  Of course, other operational effects that are different from the operational effects brought about by the above-described embodiments will be apparent from the description of the present specification or can be easily predicted by those skilled in the art. It is understood that this is brought about by the present invention.

  100: Display device, 102: Substrate, 104: Pixel, 106: Display area, 108: Scan line driving circuit, 112: Terminal, 114: Flexible printed circuit board, 116: Counter substrate, 120: First scan line, 122 : Second scanning line, 123: reset signal line, 124: third scanning line, 126: video signal line, 128: power supply line, 130: switching transistor, 132: output transistor, 134: drive transistor, 136: reset Transistor: 140: holding capacitor, 142: additional capacitor, 150: light emitting element, 152: pixel electrode, 154: EL layer, 156: counter electrode, 160: undercoat, 162: semiconductor film, 162a: channel region, 162b: low Concentration impurity region, 162c: high concentration impurity region, 164: gate insulating film, 166: gate electrode, 68: first interlayer film, 170: source / drain electrode, 172: source / drain electrode, 174: capacitance electrode, 176: second interlayer film, 178: planarization film, 180: connection electrode, 182: additional capacitance Electrode, 184: Insulating film, 186: Opening, 190: Partition wall, 200: Passivation film, 202: First layer, 204: Second layer, 206: Third layer, 210: Sealing material

Claims (12)

Forming a transistor on a substrate;
Forming a pixel electrode which is electrically connected to the transistor and contains a conductive oxide over the transistor;
An array substrate is formed by exposing a part of the surface of the pixel electrode and forming a partition wall that covers an end of the pixel electrode, and plasma treatment is performed on the exposed surface of the pixel electrode. Including applying,
In the plasma treatment, when the array substrate is heated at 200 ° C. for 30 minutes after the plasma treatment, the total amount of organic compounds desorbed from the array substrate per unit area of the array substrate is 5.0 ng / cm ² or less. A manufacturing method of a display device performed as follows. The manufacturing method according to claim 1, wherein the plasma treatment is performed so that the total amount of the organic compound is 2.0 ng / cm ² or less.   The manufacturing method of Claim 1 whose molecular weight of the said organic compound is 100-200.   The manufacturing method according to claim 1, wherein the organic compound has a bridging bond between two bridgehead atoms.   The organic compounds include methyl isobutyl ketone, alpha methyl styrene, 2,3,3a, 4,7,7a-hexahydro-4,7-methano-1H-indene, and 3-ethenyltricyclo [4,2,1, The production method according to claim 1, which is selected from 0 (2,5)] nonane.   The manufacturing method according to claim 1, wherein the total amount of the organic compound is estimated by gas chromatography mass spectrometry of the organic compound adsorbed on a porous polymer.   The manufacturing method according to claim 1, further comprising forming a layer containing an organic compound and a counter electrode on the pixel electrode. Forming a transistor on a substrate;
Forming a pixel electrode which is electrically connected to the transistor and contains a conductive oxide over the transistor;
An array substrate is formed by exposing a part of the surface of the pixel electrode and forming a partition wall that covers an end of the pixel electrode, and plasma treatment is performed on the exposed surface of the pixel electrode. Including applying,
The method for manufacturing a display device, wherein the plasma treatment is performed in the presence of an oxygen-containing gas having a pressure of 80 Pa or more and an output of 170 W or less and 20 seconds or less.   The manufacturing method according to claim 8, further comprising forming a layer containing an organic compound and a counter electrode on the pixel electrode.   The manufacturing method according to claim 8, wherein the partition wall provides an organic compound having a molecular weight of 100 to 200 by the plasma treatment.   The manufacturing method according to claim 10, wherein the organic compound has a bridging bond between two bridgehead atoms.   The organic compounds include methyl isobutyl ketone, alpha methyl styrene, 2,3,3a, 4,7,7a-hexahydro-4,7-methano-1H-indene, and 3-ethenyltricyclo [4,2,1, The production method according to claim 10, which is selected from 0 (2,5)] nonane.

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