JP2019175854A - Organic el display device and method for manufacturing organic el display device - Google Patents

Abstract

Provided is an organic EL display device having less luminance unevenness, color unevenness, and display unevenness. An organic EL display device includes a substrate having a surface on which a driving circuit including a thin film transistor is formed, a planarizing film for covering the driving circuit and planarizing the surface of the substrate, and a flattening film. An organic light-emitting element 40 formed on the surface of the passivation film 30 and electrically connected to the drive circuit 2. , An organic insulating film 32 laminated on the first inorganic insulating film 31, and a second inorganic insulating film 33 laminated on the organic insulating film 32. The surface facing away from the film 32 has an arithmetic average roughness of 50 nm or less. [Selection] Figure 2

Description

  The present invention relates to an organic EL display device and a method for manufacturing the organic EL display device.

  2. Description of the Related Art In recent years, organic EL display devices that have been applied to television receivers and the like include an organic light emitting element formed for each pixel and a drive circuit that causes the organic light emitting element to emit light with a desired current. In an active matrix organic EL display device, a thin film transistor constituting a driving circuit is formed on the surface of a glass substrate or the like for each pixel provided in a matrix, and an organic light emitting element is formed on an insulating film covering the thin film transistor. It is formed. Patent Document 1 discloses forming a thin film transistor having a multilayer structure in order to reduce an area occupied by a thin film transistor for a pixel in such an active matrix display.

JP 2017-11173 A

  In an organic EL display device, for example, luminance unevenness or color unevenness (hereinafter, “brightness unevenness and / or color unevenness” is collectively referred to as “display unevenness”) or the like occurs for each pixel or for any region on the display screen. The display quality is lowered and the product value is lowered. Therefore, in the organic EL display device, a compensation circuit for display unevenness is added to the drive circuit, or a correction unit that corrects the drive current of the organic light emitting element for each pixel or for every certain region after observing the initial display state. It may be provided. However, for example, the circuit elements constituting the compensation circuit provided for each pixel may vary, or a measure for display unevenness may be taken, resulting in an increase in size or cost.

  Therefore, an object of the present invention is to provide an organic EL display device with little display unevenness even without a compensation circuit, and a method for manufacturing such an organic EL display device with little display unevenness.

  The organic EL display device according to the first embodiment of the present invention includes a substrate having a surface on which a driving circuit including a thin film transistor is formed, a planarization film that planarizes the surface of the substrate by covering the driving circuit, An organic light emitting element formed on a surface of the planarization film and electrically connected to the drive circuit, the planarization film is a first inorganic insulating film stacked on the drive circuit, An organic insulating film stacked on the first inorganic insulating film; and a second inorganic insulating film stacked on the organic insulating film; and the organic insulating film in the second inorganic insulating film; The surface facing in the opposite direction has an arithmetic average roughness of 50 nm or less.

  The method for manufacturing an organic EL display device according to the second embodiment of the present invention includes a step of forming a driving circuit including a thin film transistor on a substrate, a first inorganic insulating film, an organic insulating film, and a first layer on the surface of the driving circuit. (2) a step of forming an inorganic insulating film; a step of polishing a surface of the second inorganic insulating film; and a contact reaching the drive circuit to the second inorganic insulating film, the organic insulating film, and the first inorganic insulating film. Forming a hole; embedding a metal in the contact hole; forming a first electrode in a predetermined region; forming an organic light emitting layer on the first electrode; and Forming a second electrode on the layer.

  According to the first and second embodiments of the present invention, it is possible to reduce luminance unevenness or color unevenness in an organic EL display device, and appropriately manufacture an organic EL display device with such display unevenness. Can do.

It is a figure which shows roughly an example of the drive circuit of the organic electroluminescent display apparatus of one Embodiment of this invention. It is sectional drawing which shows roughly an example of the organic light emitting element and thin-film transistor in the organic electroluminescent display apparatus of one Embodiment of this invention. It is a flowchart of the manufacturing method of the organic electroluminescence display of one Embodiment of this invention. It is sectional drawing which shows typically the organic EL display device in the middle of manufacture by the manufacturing method of the organic EL display device of one Embodiment of this invention. It is sectional drawing which shows typically the organic EL display device in the middle of manufacture by the manufacturing method of the organic EL display device of one Embodiment of this invention. It is sectional drawing which shows typically the organic EL display device in the middle of manufacture by the manufacturing method of the organic EL display device of one Embodiment of this invention. It is sectional drawing which shows typically the organic EL display device in the middle of manufacture by the manufacturing method of the organic EL display device of one Embodiment of this invention. It is sectional drawing which shows typically the organic EL display device in the middle of manufacture by the manufacturing method of the organic EL display device of one Embodiment of this invention. It is sectional drawing which shows typically the organic EL display device in the middle of manufacture by the manufacturing method of the organic EL display device of one Embodiment of this invention. It is sectional drawing which shows typically the organic EL display device in the middle of manufacture by the manufacturing method of the organic EL display device of one Embodiment of this invention.

  The inventor has intensively studied to investigate the cause of display unevenness in an organic EL display device. Then, the present inventor has found that unevenness on the surface of the drive circuit including a thin film transistor formed on the surface of the substrate causes variations in film thickness in the organic film in the organic light emitting element, resulting in luminance unevenness and color. It has been found that unevenness can occur. More specifically, an insulating film is provided between the drive circuit and the organic light emitting element as described above. By this insulating film, electrical insulation between the two and blocking of moisture and the like, a flat surface of the organic light emitting element is flattened. It is planned. However, the present inventors have found that this flattening is not always sufficient from the viewpoint of obtaining an excellent display quality.

  On the surface of the substrate on which the thin film transistor is formed, a step is generated by forming the thin film transistor and various wirings. Further, whether or not the surface of each thin film transistor is a region where a gate electrode or the like is formed, etc. Causes a step. For example, a step having a height difference exceeding 300 nm may occur. The present inventor has found that flatness that does not cause display unevenness in an organic EL display device cannot be obtained by simply forming a flattening film on the surface of such a substrate as in the past. In this regard, in the field of flat display, a pixel electrode is formed on a thin film transistor even in a liquid crystal display device, but slight unevenness on the surface of the pixel electrode hardly affects the orientation of liquid crystal molecules. Strict flatness was not required for the base. However, in the organic light emitting device, when the surface of the planarization film is not sufficiently flat, luminance unevenness occurs due to variations in the thickness of the organic film formed on the electrode, and a slight inclination of the electrode surface. As a result, the direction indicating the peak intensity of the emitted light varies or deviates from the normal direction of the display surface. As a result, the present inventors have found that display unevenness occurs.

  A thin film transistor is a top emission type (TE type) organic EL display device in which light from an organic light emitting element is emitted in a direction opposite to the substrate. It can be formed in a region, for example even in the entire light emitting region. On the other hand, in a bottom emission type (BE type) organic EL display device, a thin film transistor is usually formed in the vicinity of the edge of a pixel so that light from the organic light emitting element is not blocked as much as possible. However, in the TE type as well as the BE type, unevenness on the surface of the substrate due to thin film transistors or the like appears as undulations on the surface of the planarization film in the region overlapping the light emitting region of the pixel, and the minute undulations cause display unevenness. It turns out that it is causing. The present inventor has found that the occurrence of uneven brightness and uneven color can be suppressed by further flattening the surface of the flattening film serving as the base of the organic light emitting device.

  Hereinafter, an organic EL display device and an organic EL display device manufacturing method according to embodiments of the present invention will be described with reference to the drawings. In addition, the material of each component in embodiment described below, a shape, those relative positional relationship, etc. are only an illustration to the last. The organic EL display device and the manufacturing method of the organic EL display device of the present invention are not limitedly interpreted by these.

[Organic EL display device]
FIG. 1 shows an example of the configuration of the drive circuit 2 in the organic EL display device 1 of the first embodiment, together with an organic EL display panel 3, a data line driver 1d, and a scanning line driver 1g schematically shown. Has been. The organic EL display panel 3 has a plurality of pixels 3a arranged in a matrix, and an organic light emitting element 40 and a drive circuit 2 are provided in each pixel 3a. In the example of FIG. 1, each driving circuit 2 includes a driving TFT 20 that switches an energization state of the organic light emitting element 40, a switching TFT 2 a that switches ON / OFF of the driving TFT 20, and a storage capacitor 2 b that holds a gate-source voltage of the driving TFT 20. Is included. The drain of the driving TFT 20 is connected to the power supply line 2p, the source is connected to the anode of the organic light emitting element 40, and the gate is connected to the source of the switching TFT 2a. The cathode of the organic light emitting element 40 is connected to the ground via the cathode wiring 27. It is connected.

  A gate signal is sent from the scanning line driver 1g to each switching TFT 2a, and a data signal of a display image is applied from the data line driver 1d to each driving TFT 20 via each switching TFT 2a. A current based on the voltage of the data signal flows to the organic light emitting element 40, and the organic light emitting element 40 emits light with a predetermined luminance during one frame period by the action of the storage capacitor 2b. Hereinafter, the structure of the organic EL display device 1 of the present embodiment will be described with reference to FIG. 2 showing a cross section of the organic EL display panel 3 including one pixel 3a. In the following description, the driving TFT 20 is simply referred to as “thin film transistor 20 (TFT 20)”. In addition, the “pixel” referred to in the above description and the following description and each drawing is the minimum component (unit element) of the display screen and is precisely a “sub-pixel”. ". In the following description, “surface” refers to a surface facing in the opposite direction to the substrate 10 (see FIG. 2) in each component other than the substrate 10 constituting the organic EL display device 1 unless the distinction is described. Means. Further, the “surface” with respect to the substrate 10 means a surface facing the organic light emitting element 40 unless the distinction is described.

  FIG. 2 shows an enlarged cross section of the organic EL display panel 3. In particular, an example of a cross section of the TFT 20 and the organic light emitting element 40 is a cathode contact (the first contact 28 and the second contact) of the organic light emitting element 40. Shown with contacts 45). As shown in FIG. 2, the organic EL display device 1 of the present embodiment has a substrate 10 having a surface on which a driving circuit 2 including a thin film transistor 20 is formed, and the surface of the substrate 10 is flattened by covering the driving circuit 2. And the organic light emitting element 40 formed on the surface of the flattening film 30 and electrically connected to the drive circuit 2. The TFT 20 is an Nch field effect transistor in the example of FIG. 2, and includes a semiconductor layer 21 including the channel 21 c, a gate electrode 23 formed on the channel 21 c via the gate insulating film 22, and a source of the semiconductor layer 21. A source electrode 25 and a drain electrode 26 connected to 21s and the drain 21d, respectively. The source electrode 25 and the drain electrode 26 are insulated from the gate electrode 23 by the interlayer insulating film 24. In the example of FIG. 2, the organic light emitting element 40 is a top emission type (TE type) organic light emitting diode (OLED), and includes a first electrode (for example, an anode) 41 and a first electrode 41 formed on the planarizing film 30. An organic light emitting layer 43 formed in the insulating bank 42, and a second electrode (for example, a cathode) 44 formed on the entire substrate 10 including the organic light emitting layer 43. The planarizing film 30 is stacked on the first inorganic insulating film 31 stacked on the drive circuit 2, the organic insulating film 32 stacked on the first inorganic insulating film 31, and the organic insulating film 32. The second inorganic insulating film 33 is included. The surface of the second inorganic insulating film 33 facing in the direction opposite to the organic insulating film 32 has an arithmetic average roughness of 50 nm or less. In the example of FIG. 2, the organic light emitting layer 43 defined by the insulating bank 42 is formed in a region that does not overlap with the contact hole 30 a for electrically connecting the source electrode 25 and the first electrode 41 in plan view. ing.

  That is, in the organic EL display device 1 of the present embodiment, the surface of the substrate 10 having irregularities due to the formation of the drive circuit 2 has a laminated structure of the first inorganic insulating film 31, the organic insulating film 32, and the second inorganic insulating film 33. The surface is covered with a planarizing film 30 having an arithmetic average roughness (Ra) of 50 nm or less. For example, the planarizing film 30 may be polished after laminating each insulating film so that the surface thereof has an arithmetic average roughness of 50 nm or less. In the example of FIG. 2, the organic light emitting layer 43 is formed in a region that does not overlap with the contact hole 30a in plan view.

  As described above, the present inventor conducted extensive studies on the cause of display unevenness in the organic EL display device, and as a result, the surface of the organic light emitting layer in the organic light emitting element is not a perfect flat surface but has fine irregularities. It has been found that there is a part that is tilted microscopically. When the surface of the organic light emitting layer is inclined, the normal direction is inclined with respect to the normal direction of the display surface in the organic EL display device, and light emitted from such an organic light emitting layer in an oblique direction is It becomes difficult to recognize from the front of the display surface. Therefore, a decrease in luminance or a change in chromaticity determined by the intensity of light of each color of R, G, and B has occurred.

  Conventionally, variations in characteristics of TFTs and organic light emitting devices (OLEDs) constituting a driving circuit have been regarded as problems as causes of display unevenness, and measures against these variations have been taken. For example, a circuit that compensates for characteristic variations of TFTs and / or OLEDs is added to each drive circuit provided for each pixel. However, such measures may increase cost and size due to an increase in the number of components of the drive circuit, and may require an additional circuit to suppress variations in the compensation circuit itself. In the first place, such a measure does not function effectively as a measure against display unevenness found by the present inventor, but rather, there is a possibility that unevenness on the surface of the substrate is increased due to an increase in the number of components of the drive circuit. In addition, the luminance distribution of the screen is grasped in the inspection process of the organic EL display device, and the current flowing to each organic light emitting element is sometimes controlled based on the correction data for uniformization. However, such countermeasures also require complicated manufacturing processes and complicated control of the organic EL display device.

  On the other hand, in the present embodiment, as described above, in order to eliminate the cause of newly found display unevenness, that is, to improve the flatness of the surface of the organic light emitting layer 43, flattening as a base thereof is performed. The surface of the film 30 has an arithmetic average roughness of 50 nm or less. By doing so, a display image with extremely little luminance unevenness and color unevenness can be obtained. In addition, since the thickness of the organic light emitting layer 43 is stabilized, it is possible to stably obtain the effect of adopting a microcavity structure effective for improving the intensity of emitted light and the purity of each color of R, G, and B. Therefore, it is preferable to employ a microcavity structure for each pixel (sub-pixel) of the organic EL display device 1 of the present embodiment. Further, in the example of FIG. 2, the organic light emitting layer 43 is formed in a region that does not overlap with the contact hole 30 a in plan view, avoiding directly above the contact hole 30 a. Therefore, as will be described later, display unevenness due to the contact hole 30a is hardly generated.

  Although the surface roughness of the planarizing film 30 is preferably as small as possible, the arithmetic average roughness of, for example, less than 20 nm, which is targeted in the polishing process of the interlayer insulating film in the semiconductor device manufacturing process, is not always required. Such strict flatness in the polishing process of the semiconductor device is required to cope with the shallow depth of focus of the light source used for exposure in the subsequent photolithography process, and suppresses display unevenness of the organic EL display device. Is required for a completely different purpose. That is, from the viewpoint of suppressing display unevenness of the organic EL display device 1, the surface of the planarizing film 30 only needs to have an arithmetic average roughness of 50 nm or less. The inventor has found that this does not occur. Further, even when considering variations in screen size and resolution, manufacturing variations in the organic light emitting device 40, etc., the surface roughness below 20 nm is not necessary. Rather, in terms of ease of implementation, an arithmetic average roughness of 20 nm or more is required. It has been found preferable. That is, the surface roughness of the planarizing film 30, specifically, the surface of the second inorganic insulating film 33 facing the direction opposite to the organic insulating film 32 has an arithmetic average roughness of 20 nm or more and 50 nm or less. It is preferable in terms of achieving both effective suppression of display unevenness that may affect display quality and simple manufacturing.

  Each component of the organic EL display device 1 will be further described with reference to FIG. As the substrate 10, a glass substrate or a polyimide film is mainly used. When the organic EL display device 1 is a bottom emission type (BE type) unlike the example of FIG. 2, a light-transmitting material, that is, a glass substrate, a transparent polyimide film, or the like is used. By using the resin film, the organic EL display device 1 can be easily made flexible and can be attached to a curved surface or the like.

A base coat layer 11 is formed as a barrier film on the surface of the substrate 10 on which the TFT 20 is formed. For example, by a plasma CVD method, mainly basecoat having a lower layer consisting of SiN _X film of about 500nm thickness of about SiO ₂ film and the 50nm thick and a top layer mainly consisting of SiO ₂ film of about 250nm thick Layer 11 is formed.

  A drive circuit 2 including a TFT 20 is formed on the base coat layer 11. The cathode wiring 27 is also formed on the base coat layer 11. Although omitted in FIG. 2, wirings for scanning lines and data lines are formed in the same manner as the cathode wirings 27. In FIG. 2, only the TFT 20 that drives the light emitting element 40 is shown, but the switching TFT 2a described above is also formed on the base coat layer 11, and another TFT may be formed. When the organic EL display device 1 is a TE type as in the example of FIG. 2, the drive circuit 2 can be formed over the entire surface below the light emitting region of the organic light emitting element 40. On the other hand, in the BE type, since the TFT 20 or the like cannot be formed below the light emitting region of the organic light emitting element 40, the TFT 20 or the like is formed at the peripheral portion of the portion overlapping the light emitting region in a plane. However, even in this case, an inclined surface is formed at a boundary portion between a portion where the TFT 20 or each wiring line in the peripheral portion is formed and a portion where the TFT below the light emitting region is not formed. For this reason, irregularities occur in the peripheral portion of the light emitting region, and the display quality is lowered as described above. Therefore, there is a need for a planarizing film 30 that has such flatness on the surface as to bury the unevenness in the TE type as well as the BE type so as not to cause display unevenness.

The TFT 20 includes a semiconductor layer 21 having a source 21s, a channel 21c, and a drain 21d, a gate insulating film 22, a gate electrode 23, an interlayer insulating film 24, a source electrode 25, and a drain electrode 26. The gate insulating film 22 is mainly made of SiO ₂ or the like having a thickness of about 50 nm, and the gate electrode 23 is formed by patterning after a film of Mo or the like having a thickness of about 250 nm is formed. On the gate electrode 23, an interlayer insulating film 24 composed of a SiO ₂ film of about 300 nm thickness and a SiN _x film of about 300 nm thickness is formed, and a source electrode 25 and a drain electrode 26 connected to the source 21s and the drain 21d are formed. Has been. Before the interlayer insulating film 24 is formed, the impurity concentration of the source 21s, the drain 21d, and the cathode wiring 27 is increased by doping with boron ions, for example, and the resistance is lowered by activation by annealing. A more specific structure will be described in detail in the description of the manufacturing method of the organic EL display device described later. 2 shows an example of a top gate structure in which the semiconductor layer 21 is provided between the gate electrode 23 and the substrate 10, but the TFT 20 included in the organic EL display device 1 of the present embodiment has a bottom gate structure. You may have.

A first inorganic insulating film 31 made of SiN _x or the like having a thickness of about 200 nm as a barrier layer is formed on the surface of the drive circuit 2 including the TFT 20, and an organic insulating film 32 is formed on the first inorganic insulating film 31. Furthermore, a second inorganic insulating film 33 is formed. That is, the planarizing film 30 having a three-layer structure of inorganic film + organic film + inorganic film is formed. The planarizing film 30 is formed with a contact hole 30a penetrating the first inorganic insulating film 31, the organic insulating film 32, and the second inorganic insulating film 33 all together. As will be described later, for example, indium tin oxide (ITO) and metal such as silver (Ag) or APC (silver + palladium + copper) are embedded in the contact hole 30a, and the drive circuit 2 is interposed through this metal. And the organic light emitting element 40 are connected.

  The organic insulating film 32 has a thickness of about 1 μm to 2 μm, for example. The organic insulating film 32 greatly reduces the unevenness of the surface of the substrate 10 due to the formation of the drive circuit 2. The organic insulating film 32 is formed using, for example, polyimide resin or acrylic resin. The organic insulating film 32 preferably contains an additive (leveling improver) that improves the flatness of the surface of the organic insulating film 32. The organic insulating film 32 may be formed using a photosensitive resin so that the contact hole 30a can be formed by mask exposure and development. However, for example, photopolymerization initiators such as Michler's ketone, chlorothioxanthone, and isopropylthioxanthone may weaken the effects of the leveling improver described above, or the leveling improver may inhibit photopolymerization. Therefore, it is preferable to use a material that does not include a photoconductor such as a photopolymerization initiator for the organic insulating film 32. Even in this case, the contact hole 30a can be formed by dry etching or the like as will be described later. Then, by selecting a method that does not use photosensitivity for the formation of the contact hole 30a, an organic material having a high purity such as an acrylic resin can be used as the material of the organic insulating film 32. In addition, a necessary and sufficient amount of leveling improver can be added to the organic insulating film 32 without worrying about the effect on photopolymerization, or the effect of the photopolymerization initiator is eliminated, so that the required amount of leveling improver is reduced. You can do less. Therefore, the selection range of the addition amount of the leveling improver is expanded. For example, the organic insulating film 32 includes an additive that improves the flatness of the surface of the organic insulating film 32 facing the second inorganic insulating film 33 at a content of 0.5% by mass or more and 5% by mass or less. Is preferred. When the leveling improver of this amount is included in the organic insulating film 32, it becomes easy to form the planarizing film 30 having a surface with an arithmetic average roughness of 50 nm or less, and acrylic resin or polyimide resin is used. Little impact on required properties. Examples of such leveling improvers include silicone-based, hydrocarbon-based, or fluorine-based surfactants.

  Acrylic resin is preferable as a material of the organic insulating film 32 because it is well adapted to a surfactant and the like and has high flatness from the viewpoint of not only the purity but also the flatness of the surface of the organic insulating film 32. On the other hand, when the manufacturing process of the organic EL display device 1 includes a high-temperature process of 200 ° C. or higher, a polyimide resin having high heat resistance is preferable. Therefore, the organic insulating film 32 is preferably an acrylic resin that does not include a photoconductor such as a photopolymerization initiator or a polyimide resin that does not include a photoconductor. The surface of the organic insulating film 32 facing the second inorganic insulating film 33 preferably has an arithmetic average roughness of 100 nm or more and 300 nm or less. In that case, as described above, it may be easy to form the planarizing film 30 having an arithmetic average roughness of 50 nm or less on the surface, and the leveling improver content in the organic insulating film 32 is not excessive. Can be stopped.

As described above, the second inorganic insulating film 33 has an arithmetic average roughness of 50 nm or less on the surface facing in the opposite direction to the organic insulating film 32, and therefore, display unevenness of the organic EL display device 1 is suppressed. . The second inorganic insulating film 33 is made of, for example, SiN _x or SiO ₂ , and SiN _x is preferable in terms of moisture barrier properties. That is, the barrier performance against moisture in the planarizing film 30 is enhanced by the second inorganic insulating layer 33.

  The second inorganic insulating film 33 can have a function of blocking moisture at the time of manufacture as well as when the organic EL display device 1 is used. That is, as will be described later, the surface of the planarizing film 30 may be polished in the manufacturing process so as to have a surface roughness of 50 nm or less, and after polishing, cleaning may be performed to remove the abrasive or the like. . When the second inorganic insulating film 33 is not formed, the surface of the organic insulating film 32 is polished and further exposed to a cleaning agent. In that case, the cleaning agent may permeate into the organic insulating film 32 and remain as it is to cause deterioration of the TFT 20. However, the formation of the second inorganic insulating film 33 prevents the penetration of the cleaning agent into the organic insulating film 32 and the deterioration of the TFT 20.

  The second inorganic insulating film 33 is formed to a thickness of, for example, about 100 nm to 600 nm. However, the thickness of the second inorganic insulating film 33 is related to the size of the unevenness appearing on the surface of the organic insulating film 32. That is, the second inorganic insulating film 33 is formed on the uneven surface of the organic insulating film 32, and the surface of the second inorganic insulating film 33 has a flatness of 50 nm or less in arithmetic mean roughness. The thickness of the inorganic insulating film 33 varies based on the unevenness of the surface of the organic insulating film 32 facing the second inorganic insulating film 33.

  For example, the second inorganic insulating layer 33 has a maximum height difference DT of 3 on the surface unevenness of the organic insulating film 32 so that the surface unevenness of the organic insulating film 32 can be sufficiently embedded in the second inorganic insulating layer 33. It is preferable to be formed in a thickness more than double. If necessary, the surface of the second inorganic insulating film 33 is preferably polished by a length (thickness) that is not less than the maximum height difference DT and less than twice the maximum height difference DT. By doing so, the convex portions on the surface of the second inorganic insulating film 33 based on the convex portions on the surface of the organic insulating film 32 can be scraped without exposing the organic insulating film 32, and the surface of the planarizing film 30 is substantially reduced. An arithmetic average roughness of 50 nm or less can be ensured. In that case, the second inorganic insulating film 33 may have a thickness of 1 to 3 times the maximum height difference DT of unevenness on the surface of the organic insulating film 32. For example, in FIG. 2, the maximum thickness TL of the second inorganic insulating film 33 is not less than 2 times and not more than 3 times the maximum height difference DT of the unevenness of the organic insulating film 32, and the minimum thickness of the second inorganic insulating film 33 is The thickness TM is 1 to 2 times the maximum height difference DT of the unevenness of the organic insulating film 32. In particular, in the example of FIG. 2, the maximum thickness TL of the second inorganic insulating film 33 is approximately twice the maximum height difference DT of the unevenness of the organic insulating film 32, and the minimum thickness TM is the organic insulating film. This is substantially the same as the maximum height difference DT of 32 irregularities.

  As described above, the contact hole 30a penetrates through the insulating films constituting the planarizing film 30 all together. For this reason, there is no significant step on the inner wall of the contact hole 30a, and therefore it is easy to embed metal in the contact hole 30a. In addition, cracks and the like hardly occur in the metal. The planarizing film 30 is also formed with a contact hole 30b for forming the second contact 45 of the cathode contacts, and the contact hole 30b also penetrates each insulating film constituting the planarizing film 30 at once. ing.

  The first electrode 41 of the organic light emitting element 40 is formed integrally with a metal embedded in the contact hole 30a. That is, for example, ITO and a metal such as Ag or APC and ITO are embedded in the contact hole 30a by sputtering or the like, and the same ITO film, metal film such as Ag or APC, and ITO film are also formed on the surface of the planarizing film 30. Are formed respectively. By patterning them into a predetermined shape, an upper layer and a lower layer are ITO films, and a first electrode 41 with a metal film such as Ag or APC interposed therebetween is formed. The first electrode 41 preferably has a work function of about 5 eV in relation to the organic light emitting layer 43. In the case of a top emission type, ITO and Ag or APC as described above are used. The ITO film is formed with a thickness of about 10 nm, and the Ag or APC film is formed with a thickness of about 100 nm. In the case of the bottom emission type, for example, only an ITO film having a thickness of about 300 nm to 1 μm is formed.

  A recess as shown in FIG. 2 may occur in the portion of the surface of the first electrode 41 directly above the contact hole 30a when the contact hole 30a is not completely filled with ITO or the like. However, in the example of FIG. 2, the first electrode 41 has a region that does not overlap with the contact hole 30 a in a plan view and is large enough to form the organic light emitting layer 43, and on the region that does not overlap with the contact hole 30 a. An organic light emitting layer 43 is formed on the substrate. Therefore, the thickness unevenness in the organic light emitting layer 43 and the depression on the surface thereof hardly occur, and the display unevenness due to the contact hole 30a hardly occurs.

  An insulating bank 42 that partitions each pixel and insulates between the first electrode 41 and the second electrode 44 is formed at the peripheral edge of the first electrode 41. In the example of FIG. 2, a depression on the surface of the first electrode 41 is covered by the insulating bank 42. An organic light emitting layer 43 is stacked on the first electrode 41 surrounded by the insulating bank 42. The organic light emitting layer 43 serving as the light emitting region of the organic light emitting element 40 is preferably formed in a region that does not overlap the contact hole 30a in plan view, as in the example of FIG. In that case, as described above, display unevenness due to the contact hole 30a is unlikely to occur. The organic light emitting layer 43 is shown as a single layer in FIG. 1 and the like, but is formed of a plurality of organic layers by laminating various materials. The organic light emitting layer 43 is formed by vapor deposition, printing, or the like in which an evaporated or sublimated organic material is selectively attached to only necessary portions using a mask.

Specifically, for example, as a layer in contact with the first electrode 41, a hole injection layer made of a material having good ionization energy consistency that improves the hole injection property is provided. On this hole injection layer, a hole transport layer capable of improving the stable transport of holes and confining electrons (energy barrier) in the light emitting layer is formed of, for example, an amine material. Furthermore, the light emitting layer selected according to the light emission wavelength is formed thereon. For example, for red and green, Alq ₃ is doped with a red or green organic fluorescent material. As the blue material, a DSA organic material is used. Furthermore, on the light emitting layer, an electron transport layer that improves electron injection and stably transports electrons can be formed of Alq ₃ or the like. By laminating each of these layers by several tens of nanometers, a laminated film of the organic light emitting layer 43 is formed. An electron injection layer for improving electron injection properties such as LiF and Liq may be provided between the organic light emitting layer 43 and the second electrode 44.

  The second electrode 44 is formed on the organic light emitting layer 43. In the example of FIG. 2, the second electrode 44 is continuously formed so as to be common to all pixels, and the second contact 45 formed on the planarization film 30, the gate insulating film 22, and the interlayer insulating film 24 is connected to the cathode wiring 27 through a first contact 28 formed on the wiring 24. The second electrode 44 is formed of a translucent material, for example, a thin Mg—Ag film. The second electrode 44 is preferably made of a material having a low work function, and alkali metal or alkaline earth metal can be used. Mg is preferable because it has a work function as small as 3.6 eV, and Ag having a work function as small as about 4.25 eV is co-deposited at a ratio of about 10% by mass for further providing stability. In the BE type, the second electrode 44 serves as a reflecting plate, so that the second electrode 44 is formed with a large thickness of Al.

A coating layer (TFE) 46 that prevents moisture from reaching the second electrode 44 is formed on the second electrode 44. The covering layer 46 is made of, for example, an inorganic insulating film such as SiN _x or SiO _2, and is formed by forming a single layer film or a laminated film of two or more layers. For example, a laminated film of about two layers having a thickness of about 0.1 μm to 0.5 μm is formed as the coating layer 46. The covering layer 46 is preferably formed in multiple layers of different materials so that a sufficient barrier property against moisture and the like can be obtained even if a pinhole or the like is formed in one layer. The covering layer 46 is formed so as to completely cover the organic light emitting layer 43 and the second electrode 44. The covering layer 46 may include an organic insulating film between the two inorganic insulating films.

[Method for Manufacturing Organic EL Display Device]
Next, taking the organic EL display device 1 shown in FIG. 2 as an example, a method for manufacturing the organic EL display device of one embodiment will be described with reference to the flowchart of FIG. 3 and the cross-sectional views shown in FIGS. 4A to 4G. Is done.

As shown in FIG. 4A, the drive circuit 2 including the thin film transistor 20 is formed on the substrate 10 (S1 in FIG. 3). Specifically, for example, the base coat layer 11 is formed on the surface of the substrate 10 using a plasma CVD method. Although the base coat layer 11 is shown in a single layer structure in FIG. 4A, for example, a SiO ₂ layer having a thickness of about 500 nm, a SiN _x layer having a thickness of about 50 nm thereon, and a thickness of about 250 nm thereon. It is formed by laminating a SiO ₂ layer.

Thereafter, a semiconductor film made of an amorphous silicon (a-Si) layer is formed over the entire surface of the base coat layer 11 by using, for example, a plasma CVD method. This semiconductor film is subjected to a dehydrogenation process by an annealing process for about 45 minutes at a temperature of about 350 ° C., for example. Then, this semiconductor film is annealed by irradiation with an excimer laser of about several tens of nsec, and a-Si is converted into polysilicon. The polysiliconized semiconductor film is patterned by, for example, mask formation by photolithography and dry etching. As a result, the semiconductor layer 21 having a predetermined width and length and the cathode wiring 27 having a predetermined shape are formed. At this time, wirings (not shown) such as scanning lines and data lines other than the cathode wiring 27 can be formed as appropriate. Thereafter, a gate insulating film 22 covering the semiconductor layer 21 and the like is formed. The gate insulating film 22 is formed, for example, by forming a SiO ₂ film having a thickness of about 50 nm using a plasma CVD method.

  On the gate insulating film 22, a gate electrode 23 is formed by forming a Mo film with a thickness of about 250 nm by sputtering or the like and patterning it by dry etching. Then, impurity ions (for example, boron) are doped at a high concentration into the semiconductor layer 21 through the gate insulating film 22 using the gate electrode 23 as a mask, and the implanted impurity ions are activated by annealing. As a result, the region doped with impurity ions in the semiconductor layer 21 is reduced in resistance, and the semiconductor layer 21 includes a source 21 s and a drain 21 d that are formed of the reduced resistance region, and a channel 21 c that is formed in the region immediately below the gate 23. Provided. Annealing is performed, for example, at a temperature of about 350 ° C. for about 45 minutes. At this time, the resistance of each wiring formed appropriately other than the cathode wiring 27 and the cathode wiring 27 is lowered by ion doping and annealing.

Thereafter, an interlayer insulating film 24 is formed on the entire surface of the gate insulating film 22 and the gate electrode 23, and a contact hole 24a exposing a part of the source 21s and the drain 21d is formed. As the interlayer insulating film 24, for example, a plasma CVD method is used to form a stacked film of a lower layer mainly made of SiO _{2 with} a thickness of about 300 nm and an upper layer made mainly of SiN _{x with} a thickness of about 300 nm. Formed by. The contact hole 24a is formed by forming a mask by forming a resist film, selective exposure and development, and performing dry etching or the like.

  Thereafter, by depositing a metal, the metal is buried in the contact hole 24 a and the metal film of the source electrode 25 and the drain electrode 26 is formed on the surface of the interlayer insulating film 24. The metal film of the source electrode 25 and the drain electrode 26 is formed by stacking a Ti film of about 300 nm and an Al film of about 300 nm using, for example, sputtering, and further stacking a Ti film of about 100 nm thereon. Is done. By patterning this metal film using photolithography and dry etching, a source electrode 25 and a drain electrode 26 connected to the source 21s and the drain 21d of the semiconductor layer 21 are formed. The first contact 28 connected to the cathode wiring 27 is formed by the same method as the formation of the source electrode 25 and the drain electrode 26. Through the above steps, the drive circuit 2 including the TFT 20, that is, a portion called a back plane is formed. The method for forming the drive circuit 2 is merely an example relating to the top gate type polysilicon TFT illustrated in FIG. 2, and a bottom gate type TFT may be formed. An amorphous silicon TFT is used instead of the polysilicon TFT. It may be formed by any other method.

4B, the first inorganic insulating film 31, the organic insulating film 32, and the second inorganic insulating film 33 are formed on the surface of the drive circuit 2 (see FIG. 4A) (S2 in FIG. 3). The first inorganic insulating film 31 is formed by forming a film such as SiN _x or SiO _{2 having} a thickness of about 200 nm by plasma CVD, for example. The first inorganic insulating film 31 functions as a barrier layer that prevents components of the organic insulating film 32 from coming into contact with the TFT 20. The organic insulating film 32 embeds irregularities due to the formation of the TFT 20 and the like, and is formed by applying a liquid or low-viscosity paste-like resin. When a liquid resin is used, the surface of the organic insulating film 32 tends to be flat. Examples of the coating method include slit coating and spin coating, but a slit & spin coating method in which both methods are combined may be used. The organic insulating film 32 is formed to a thickness of about 1 μm to 2 μm. As a material of the organic insulating film 32, for example, a polyimide resin or an acrylic resin can be used. A photosensitive resin obtained by adding a photopolymerization initiator (photoconductor) such as Michler's ketone, chlorothioxanthone, or isopropylthioxanthone to these resins may be used. However, a non-photosensitive resin that does not include a photoconductor is preferable because of high purity and high surface smoothness of the organic insulating film 32. An acrylic resin is particularly preferable.

Similar to the first inorganic insulating film 31, the second inorganic insulating film 33 is formed by forming a film made of SiN _x or SiO ₂ using, for example, plasma CVD. By forming the second inorganic insulating film 33, penetration of various solvents such as a cleaning agent that can be used in a subsequent process into the organic insulating film 32 and degradation of the TFT 20 that may occur as a result are prevented.

  The second inorganic insulating film 33 is formed so that the surface unevenness of the organic insulating film 32 that may be caused by the surface unevenness of the substrate 10 does not appear on the surface of the planarizing film 30 (the surface of the second inorganic insulating film 33). belongs to. Therefore, the second inorganic insulating film 33 is preferably formed to a thickness selected based on the maximum height difference DT of the irregularities on the surface of the organic insulating film 32. For example, the second inorganic insulating film 33 is formed to have a thickness that is twice or more the maximum height difference DT in the unevenness of the surface of the organic insulating film 32 facing the second inorganic insulating film 33. By doing so, the dent on the surface of the organic insulating film 32 can be reliably filled with a part of the second inorganic insulating film 33. Further, it is more preferable that the second inorganic insulating layer 33 is formed to have a thickness not less than 2 times and not more than 3 times the maximum height difference DT of the unevenness on the surface of the organic insulating film 32. By doing so, the dent of the organic insulating film 32 can be filled reliably as described above. Furthermore, without making the second inorganic insulating film 33 unnecessarily thick, the unevenness based on the unevenness of the surface of the organic insulating film 32 that can appear on the surface after the formation of the second inorganic insulating film 33 is ensured in the polishing step described later. In addition, exposure of the organic insulating film 32 after polishing can be prevented with certainty.

  Next, as shown in FIG. 4C, the surface of the second inorganic insulating film 33 is polished (S3 in FIG. 3). As described above, the present inventor has found that display unevenness may occur in the organic EL display device when the surface of the planarizing film 30 serving as the base of the organic light emitting element 40 (see FIG. 2) is not sufficiently flat. It was. Therefore, the surface of the second inorganic insulating film 33 constituting the surface of the planarizing film 30 is polished. For example, the surface of the second inorganic insulating film 33 is polished so as to have an arithmetic average roughness of 50 nm or less. By polishing to such a degree of surface roughness, as described above, display unevenness that is perceived by humans can be hardly caused. Further, in the planarization of the surface of the planarization film 30, an arithmetic average roughness that is less than 20 nm, which is a target in the manufacturing process of the semiconductor device, is not necessarily obtained. Rather, in order to avoid a complicated and time-consuming polishing process including a surface roughness inspection, the surface of the second inorganic insulating film 33 may be polished to an arithmetic average roughness of 20 nm or more and 50 nm or less. preferable.

  In the polishing of the surface of the second inorganic insulating film 33, the second inorganic insulating film 33 has a polishing amount (amount of reduction in the thickness of the second inorganic insulating film 33 due to polishing), for example, at least partly on the surface of the organic insulating film 32. Polishing is performed so as to be at least 1 and less than 2 times the maximum height difference DT. By doing so, as described above, when the second inorganic insulating layer 33 is formed to have a thickness more than twice the maximum height difference DT of the unevenness of the organic insulating film 32, it is based on the unevenness of the organic insulating film 32. Unevenness that may appear on the surface of the second inorganic insulating film 33 after film formation can be leveled reliably, and the exposure of the organic insulating film 32 due to polishing can be prevented almost certainly. For example, in the example of FIG. 4C, the polishing amount P1 in a region (for example, a region where the TFT 20 is formed) that is a convex portion on the surface of the second inorganic insulating film 33 after film formation is unevenness on the surface of the organic insulating film 32. Is approximately twice the maximum height difference DT. In the example of FIG. 4C, the polishing amount P2 in a region (for example, a region where the TFT 20 is not formed) that is a concave portion on the surface of the second inorganic insulating film 33 after film formation is the maximum unevenness of the organic insulating film 32. Although it is substantially the same as the height difference DT, it is slightly less.

The method for polishing the second inorganic insulating film 33 is not particularly limited. However, in order to achieve an arithmetic average roughness of 50 nm or less, it is preferable to polish by CMP polishing using a neutral slurry containing cerium, colloidal silica, or fumed silica as an abrasive. With CMP polishing, for example, the effect of mechanical polishing can be increased by the surface chemical action of the polishing agent, and a smooth polished surface can be obtained quickly. Cerium has a high hardness and ceria (CeO ₂ ), which is an oxide thereof, causes a chemical reaction with glass, and thus can be an effective abrasive for the second inorganic insulating film 33 formed of SiO ₂ or the like. Colloidal silica is a colloid of SiO ₂ or a hydrate thereof usually having a particle size of 10 nm to 300 nm, and fumed silica (also called dry silica or highly dispersed silica) is a spherical shape having a particle size of 10 nm to 30 nm. The SiO ₂ particles are agglomerated (particle size: 100 nm to 400 nm), and all function effectively as an abrasive.

  For polishing the second inorganic insulating film 33, an aqueous solution of neutral water-soluble alcohol or potassium hydroxide is used together with the above-described polishing agent. In particular, when the substrate 10 is formed of a polyimide resin, it is preferable to polish the surface of the second inorganic insulating film 33 using a neutral alcohol solution together with the above-described abrasive from the viewpoint of preventing the substrate 10 from being corroded.

  As shown in FIG. 4D, a contact hole 30a reaching the drive circuit 2 (see FIG. 4A) is formed in the second inorganic insulating film 33, the organic insulating film 32, and the first inorganic insulating film 31 (S4 in FIG. 3). ). Preferably, a contact hole 30a penetrating these three insulating films is formed. The contact hole 30a is preferably formed in a region where the organic light emitting layer 43 is to be formed in a formation of the organic light emitting layer 43 (see FIG. 4F) described later and a region that does not overlap in the thickness direction of the substrate 10. By doing so, the occurrence of display unevenness can be prevented as described above. The contact hole 30a is formed by dry etching after forming a resist mask, for example, as in the case of the contact hole 24a described above. When a hole is formed in a film in which an inorganic film and an organic film are mixed, such as the planarizing film 30, when wet etching is used, the etching rate of the two is different, so that a step may be formed on the inner wall of the hole. In this case, the contact hole 30a is not completely filled with metal in a process to be described later, and a problem that the contact resistance with the source electrode 25 and the like increases easily occurs. However, by using dry etching, the contact hole 30a having an inner wall with few steps can be formed in the planarizing film 30 in which the inorganic film and the organic film are mixed. When the contact hole 30a is formed, a contact hole 30b for the first contact 45 (see FIG. 2) is also formed in the portion above the first contact 28 in the planarization film 30 by the same method as the contact hole 30a. The

  As shown in FIG. 4E, metal is embedded in the contact hole 30a, and the first electrode 41 of the organic light emitting device 40 (see FIG. 2) is formed in a predetermined region (S5 in FIG. 3). Specifically, for example, by sputtering, an ITO film having a thickness of about 10 nm and a lower layer in which an Ag film or an APC film having a thickness of about 100 nm are stacked and an upper layer mainly made of an ITO film having a thickness of about 10 nm are formed. Is done. As a result, a metal is embedded in the contact hole 30 a and a laminated film of an ITO film, an Ag film or an APC film, and an ITO film is formed on the surface of the planarizing film 30. Thereafter, the first electrode 41 is formed by patterning the laminated film. As shown in FIG. 4E, this laminated film is preferably patterned so that the first electrode 41 has a region that does not overlap with the contact hole 30a in a plan view and has a sufficient size for the formation of the organic light emitting layer 43. The When the metal is embedded in the contact hole 30a, the second contact 45 is formed by filling the contact hole 30b with at least an ITO film and an Ag film or an APC film.

As shown in FIG. 4F, the organic light emitting layer 43 is formed on the first electrode 41 (S6 in FIG. 3). Specifically, an insulating bank 42 that partitions each pixel and prevents contact between the first electrode 41 and the second electrode 44 (see FIG. 2) is formed at the peripheral edge of the first electrode 41. The insulating bank 42 may be an inorganic insulating film such as SiO ₂ or an organic insulating film such as polyimide or acrylic resin. For example, these insulating films are formed on the entire surface of the planarizing film 30 and the first electrode 41, and a predetermined region of the first electrode 41 is exposed by the patterning. Preferably, a region of the first electrode 41 that does not overlap with the contact hole 30a in the thickness direction of the substrate 10 is exposed. The insulating bank 42 is formed with a height of about 1 μm. As described above, various organic materials are laminated in the formation of the organic light emitting layer 43. Lamination of the organic material is performed by, for example, vacuum vapor deposition. In that case, the organic material is vapor-deposited through a vapor deposition mask having an opening corresponding to a desired subpixel such as R, G, and B. On the surface of the organic light emitting layer 43, a layer such as LiF that improves the electron injection property may be formed. Note that the organic light emitting layer 43 may be formed by printing using an inkjet method or the like instead of vapor deposition.

  As shown in FIG. 4G, the second electrode 44 is formed on the organic light emitting layer 43 (S7 in FIG. 3). The second electrode 44 is formed by forming a thin Mg—Ag eutectic film by co-evaporation, for example. The second electrode 44 is also formed on the second contact 45 and connected to the cathode wiring 27 via the second contact 45 and the first contact 28. The Mg—Ag eutectic film is a eutectic film of Mg and Ag vaporized or sublimated from different crucibles and eutecticized during film formation because of different melting points. For example, Mg is about 90% by mass and Ag is 10%. It is contained at a rate of about mass%. The second electrode 44 is formed to a thickness of about 10 to 20 nm, for example.

A coating layer 46 (see FIG. 2) is formed on the second electrode 44 to protect the second electrode 44 and the organic light emitting layer 43 from moisture or oxygen. The covering layer 46 is formed by using a plasma CVD method or the like to form an inorganic insulating film such as SiO ₂ or SiN _x that hardly absorbs moisture in order to protect the second electrode 44 and the organic light emitting layer 43 that are sensitive to moisture or oxygen. It is formed by doing. The covering layer 46 is preferably formed so that the end thereof is in close contact with an inorganic film such as the second inorganic insulating film 33. This is because the inorganic films are bonded together with good adhesion. By doing so, it is possible to more reliably prevent intrusion of moisture and the like. Through the above steps, the organic EL display device 1 shown in FIG. 2 can be manufactured.

[Summary]
(1) The organic EL display device according to the first embodiment of the present invention includes a substrate having a surface on which a driving circuit including a thin film transistor is formed, and planarizing the surface of the substrate by covering the driving circuit. An organic light emitting element formed on a surface of the planarization film and electrically connected to the drive circuit, the planarization film being stacked on the drive circuit. An insulating film; an organic insulating film stacked on the first inorganic insulating film; and a second inorganic insulating film stacked on the organic insulating film, wherein the organic in the second inorganic insulating film The surface facing the direction opposite to the insulating film has an arithmetic average roughness of 50 nm or less.

  According to the configuration of (1), luminance unevenness or color unevenness can be reduced in the organic EL display device.

(2) In the organic EL display device according to (1), the surface of the second inorganic insulating film may have an arithmetic average roughness of 20 nm or more and 50 nm or less. In that case, it is easy to achieve both effective suppression of display unevenness that may affect display quality and simple manufacturing.

(3) In the organic EL display device according to (1) or (2), the organic insulating film may be an acrylic resin that does not include a photoconductor, or a polyimide resin that does not include a photoconductor. In that case, an organic insulating film with high surface flatness is easily obtained, and a flattened film having a surface with an arithmetic average roughness of 50 nm or less is easily obtained.

(4) In the organic EL display device according to any one of (1) to (3), a surface of the organic insulating film facing the second inorganic insulating film has an arithmetic average roughness of 100 nm or more and 300 nm or less. It may be. In that case, it may be easy to form a planarizing film having a surface with an arithmetic average roughness of 50 nm or less, and the content of the leveling improver in the organic insulating film can be kept to an excessive level.

(5) In the organic EL display device according to the above (4), the organic insulating film contains 0.5 mass% or more and 5 mass% or less of an additive that improves flatness on the surface of the organic insulating film. May be included. In that case, it becomes easy to form a planarizing film having a surface with an arithmetic mean roughness of 50 nm or less, and the characteristics required for the resin material constituting the organic insulating film are hardly affected.

(6) In the organic EL display device according to any one of (1) to (5), the drive circuit and the organic light emitting element include the first inorganic insulating film, the organic insulating film, and the second inorganic film. You may connect via the metal embedded in the contact hole which penetrates an insulating film collectively. In that case, the drive circuit and the organic light emitting element are reliably connected through a path having good conductivity.

(7) In the organic EL display device according to any one of (1) to (6), the thickness of the second inorganic insulating film is based on unevenness of the surface of the organic insulating film facing the second inorganic insulating film. And may be 1 to 3 times the maximum height difference of the unevenness on the entire surface of the organic insulating film. In that case, the unevenness of the surface of the organic insulating film can be leveled on the surface of the planarizing film without exposing the organic insulating film.

(8) A method of manufacturing an organic EL display device according to a second embodiment of the present invention includes a step of forming a drive circuit including a thin film transistor on a substrate, and a first inorganic insulating film and an organic insulation on the surface of the drive circuit. A step of forming a film and a second inorganic insulating film; a step of polishing a surface of the second inorganic insulating film; and the driving circuit on the second inorganic insulating film, the organic insulating film, and the first inorganic insulating film. A step of forming a contact hole reaching the surface, a step of embedding a metal in the contact hole and forming a first electrode in a predetermined region, a step of forming an organic light emitting layer on the first electrode, Forming a second electrode on the organic light emitting layer.

  According to the configuration of (8), it is possible to appropriately manufacture an organic EL display device with little luminance unevenness or color unevenness.

(9) In the method for manufacturing an organic EL display device according to (8), a neutral slurry containing cerium, colloidal silica, or fumed silica is used as an abrasive in polishing the surface of the second inorganic insulating film. The surface of the second inorganic insulating film may be polished to an arithmetic average roughness of 50 nm or less by CMP polishing. By doing so, the surface of the planarization film can be quickly polished to a surface roughness that does not substantially cause display unevenness.

(10) In the method for manufacturing an organic EL display device according to (9), in the polishing of the surface of the second inorganic insulating film, the surface of the second inorganic insulating film has an arithmetic average roughness of 20 nm or more and 50 nm or less. It may be polished. By doing so, it is possible to obtain a surface roughness that does not substantially cause display unevenness in the planarizing film, and it is possible to avoid a complicated polishing process that requires a long time.

(11) In the method for manufacturing an organic EL display device according to (9) or (10), in the polishing of the surface of the second inorganic insulating film, a neutral alcohol liquid is used together with the polishing agent in the second inorganic insulating film. The surface of the film may be polished. By doing so, even when a resin such as polyimide is used for the substrate, the corrosion can be prevented.

(12) In the method for manufacturing an organic EL display device according to any one of the above (8) to (11), in the formation of the second inorganic insulating film, the unevenness of the surface of the organic insulating film facing the second inorganic insulating film The second inorganic insulating film is formed to have a thickness that is twice or more the maximum height difference in the step, and in the polishing of the surface of the second inorganic insulating film, the amount of decrease in the thickness of the second inorganic insulating film due to the polishing However, the second inorganic insulating film may be polished so that at least partly becomes not less than 1 times and less than 2 times the maximum height difference. By doing so, the unevenness that may appear on the surface of the second inorganic insulating film after film formation can be surely leveled based on the unevenness of the organic insulating film, and the exposure of the organic insulating film by polishing can be almost reliably performed. Can be prevented.

(13) In the method of manufacturing an organic EL display device according to (12), in forming the second inorganic insulating film, the second inorganic insulating film is formed to have a thickness that is not less than twice and not more than three times the maximum height difference. It may be formed. By doing so, the recess of the organic insulating film can be reliably filled without making the second inorganic insulating film thicker than necessary.

(14) In the method of manufacturing an organic EL display device according to any one of (8) to (13), the contact hole may be formed by dry etching. By doing so, it is difficult for a step to be formed on the inner wall of the contact hole, so that an increase in contact resistance between the organic light emitting element and the drive circuit can be prevented.

(15) In the method for manufacturing an organic EL display device according to any one of (8) to (14), the contact hole is formed in a region where the organic light emitting layer is to be formed and a region that does not overlap in the thickness direction of the substrate. May be. By doing so, it can prevent that a dent arises on the surface of an organic light emitting layer, and can prevent a display quality fall.

DESCRIPTION OF SYMBOLS 1 Organic EL display device 2 Drive circuit 3 Organic EL display panel 10 Substrate 20 Thin film transistor (drive TFT, TFT)
23 gate electrode 25 source electrode 26 drain electrode 30 planarization film 30a, 30b contact hole 31 first inorganic insulating film 32 organic insulating film 33 second inorganic insulating film 40 organic light emitting device (OLED)
41 1st electrode 43 Organic light emitting layer 44 2nd electrode

Claims (12)

A substrate having a surface on which a driving circuit including a thin film transistor is formed;
A planarization film that planarizes the surface of the substrate by covering the drive circuit;
An organic light emitting element formed on the surface of the planarization film and electrically connected to the drive circuit,
The planarizing film includes a first inorganic insulating film stacked on the driving circuit, an organic insulating film stacked on the first inorganic insulating film, and a first inorganic insulating film stacked on the organic insulating film. 2 It contains an inorganic insulating film,
The surface of the second inorganic insulating film facing the direction opposite to the organic insulating film has an arithmetic average roughness of 50 nm or less,
Organic EL, wherein the organic insulating film contains an additive that improves the flatness of the surface of the organic insulating film facing the second inorganic insulating film at a content of 0.5% by mass or more and 5% by mass or less. Display device. A substrate having a surface on which a driving circuit including a thin film transistor is formed;
A planarization film that planarizes the surface of the substrate by covering the drive circuit;
An organic light emitting element formed on the surface of the planarization film and electrically connected to the drive circuit,
The planarizing film includes a first inorganic insulating film stacked on the driving circuit, an organic insulating film stacked on the first inorganic insulating film, and a first inorganic insulating film stacked on the organic insulating film. 2 It contains an inorganic insulating film,
The surface of the second inorganic insulating film facing the direction opposite to the organic insulating film has an arithmetic average roughness of 50 nm or less,
The thickness of the second inorganic insulating film varies based on unevenness of the surface of the organic insulating film facing the second inorganic insulating film,
The maximum thickness of the second inorganic insulating film is not less than 2 times and not more than 3 times the maximum height difference of the unevenness of the organic insulating film, and the minimum thickness of the second inorganic insulating film is the organic insulating film An organic EL display device having a maximum height difference of 1 to 2 times the unevenness of the film.   The organic EL display device according to claim 1, wherein the organic insulating film includes an acrylic resin that does not include a photoconductor or a polyimide resin that does not include a photoconductor.   The organic EL display device according to claim 1, wherein a surface of the organic insulating film facing the second inorganic insulating film has an arithmetic average roughness of 100 nm or more and 300 nm or less.   The drive circuit and the organic light emitting element are connected via a metal embedded in a contact hole that penetrates the first inorganic insulating film, the organic insulating film, and the second inorganic insulating film all together. The organic EL display device according to any one of claims 1 to 4. Forming a driving circuit including a thin film transistor on a substrate;
Forming a first inorganic insulating film, an organic insulating film and a second inorganic insulating film on the surface of the drive circuit;
Polishing the surface of the second inorganic insulating film;
Forming a contact hole reaching the drive circuit in the second inorganic insulating film, the organic insulating film, and the first inorganic insulating film;
Burying a metal in the contact hole and forming a first electrode in a predetermined region;
Forming an organic light emitting layer on the first electrode;
Forming a second electrode on the organic light emitting layer;
Including
Organic EL, wherein the organic insulating film contains an additive that improves the flatness of the surface of the organic insulating film facing the second inorganic insulating film at a content of 0.5% by mass or more and 5% by mass or less. Manufacturing method of display device.   In polishing the surface of the second inorganic insulating film, the surface of the second inorganic insulating film is 50 nm or less by CMP polishing using a neutral slurry containing cerium, colloidal silica, or fumed silica as an abrasive. The method for producing an organic EL display device according to claim 6, wherein the organic EL display device is polished to an arithmetic average roughness.   The method for manufacturing an organic EL display device according to claim 7, wherein in the polishing of the surface of the second inorganic insulating film, the surface of the second inorganic insulating film is polished using a neutral alcohol liquid together with the abrasive. . In the formation of the second inorganic insulating film, the second inorganic insulating film is formed to a thickness that is twice or more of the maximum height difference in the unevenness of the surface of the organic insulating film facing the second inorganic insulating film,
In the polishing of the surface of the second inorganic insulating film, the reduction amount of the thickness of the second inorganic insulating film due to the polishing is at least partially less than or equal to 1 and less than 2 times the maximum height difference. The method for manufacturing an organic EL display device according to any one of claims 6 to 8, wherein the second inorganic insulating film is polished.   10. The method of manufacturing an organic EL display device according to claim 9, wherein in the formation of the second inorganic insulating film, the second inorganic insulating film is formed to a thickness of not less than twice and not more than three times the maximum height difference.   The method for manufacturing an organic EL display device according to claim 6, wherein the contact hole is formed by dry etching.   The method for manufacturing an organic EL display device according to claim 6, wherein the contact hole is formed in a region where the organic light emitting layer is to be formed and a region that does not overlap in a thickness direction of the substrate.

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