JP6694988B2 - Organic EL display device and method for manufacturing organic EL display device - Google Patents

Description

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

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

JP, 2017-11173, A

  In the organic EL display device, for example, luminance unevenness or color unevenness (hereinafter also referred to as “display unevenness” collectively in “brightness unevenness and / or color unevenness”) occurs in each pixel or in any area on the display screen. As a result, the display quality is lowered and the product value is lowered. Therefore, in the organic EL display device, a compensating circuit for the display unevenness is added to the driving circuit, or a correcting means for correcting the driving current of the organic light emitting element for each pixel or for each constant region after observing the initial display state. It may be provided. However, for example, a circuit element forming a compensation circuit provided for each pixel may have variations, or measures for display unevenness may cause an increase in size or cost.

  Therefore, it is an object of the present invention to provide an organic EL display device with less display unevenness even if it does not include a compensation circuit, and a method of manufacturing an organic EL display device with less 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 drive circuit including a thin film transistor is formed, and a flattening film for flattening the surface of the substrate by covering the drive circuit, An organic light emitting device formed on the surface of the planarization film and electrically connected to the drive circuit, wherein the planarization film is a first inorganic insulating film laminated on the drive circuit, An organic insulating film laminated on the first inorganic insulating film, and a second inorganic insulating film laminated 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 mean roughness of 50 nm or less.

  A method of manufacturing an organic EL display device according to a second embodiment of the present invention includes a step of forming a driving circuit including a thin film transistor on a substrate, and a first inorganic insulating film, an organic insulating film and a first insulating film on a surface of the driving circuit. 2. Forming an inorganic insulating film, polishing the surface of the second inorganic insulating film, and contacting the second inorganic insulating film, the organic insulating film, and the first inorganic insulating film to reach the drive circuit. Forming a hole, embedding a metal inside 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 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 to appropriately manufacture an organic EL display device having such a small display unevenness. You can

It is a figure which shows roughly an example of the drive circuit of the organic EL display device of one Embodiment of this invention. It is sectional drawing which shows schematically an example of the organic light emitting element and the thin film transistor in the organic EL display device of one Embodiment of this invention. 3 is a flowchart of a method for manufacturing an organic EL display device according to an embodiment of the present invention. FIG. 3 is a cross-sectional view schematically showing an organic EL display device in the process of being manufactured by the method for manufacturing an organic EL display device according to one embodiment of the present invention. FIG. 3 is a cross-sectional view schematically showing an organic EL display device in the process of being manufactured by the method for manufacturing an organic EL display device according to one embodiment of the present invention. FIG. 3 is a cross-sectional view schematically showing an organic EL display device in the process of being manufactured by the method for manufacturing an organic EL display device according to one embodiment of the present invention. FIG. 3 is a cross-sectional view schematically showing an organic EL display device in the process of being manufactured by the method for manufacturing an organic EL display device according to one embodiment of the present invention. FIG. 3 is a cross-sectional view schematically showing an organic EL display device in the process of being manufactured by the method for manufacturing an organic EL display device according to one embodiment of the present invention. FIG. 3 is a cross-sectional view schematically showing an organic EL display device in the process of being manufactured by the method for manufacturing an organic EL display device according to one embodiment of the present invention. FIG. 3 is a cross-sectional view schematically showing an organic EL display device in the process of being manufactured by the method for manufacturing an organic EL display device according to one embodiment of the present invention.

  The inventors of the present invention have conducted extensive studies to investigate the cause of display unevenness in an organic EL display device. Then, the present inventor has found that the unevenness of the surface of the driving circuit including the thin film transistor formed on the surface of the substrate causes variations in the film thickness of the organic film in the organic light emitting element, resulting in uneven brightness and color. It has been found that unevenness can occur. More specifically, the insulating film is provided between the drive circuit and the organic light emitting device as described above, and the insulating film electrically separates the two and shuts off moisture, etc., and flattens the base of the organic light emitting device. Is being promoted. However, the present inventor has found that this flattening is not always sufficient from the viewpoint of obtaining excellent display quality.

  On the surface of the substrate on which the thin film transistor is formed, a step is generated due to the formation of the thin film transistor and various wirings, and also on the surface of each thin film transistor, whether or not it is a region where a gate electrode is formed, etc. Causes a step. For example, a step having a height difference exceeding 300 nm may occur. The present inventor has found out that flatness, which does not cause display unevenness, cannot be obtained in an organic EL display device by simply forming a flattening film on the surface of such a substrate as is conventionally done. In this regard, in the field of flat panel display, the pixel electrode is formed on the thin film transistor even in the liquid crystal display device, but slight unevenness on the surface of the pixel electrode hardly affects the orientation of liquid crystal molecules, No strict flatness was required for the base. However, in the organic light emitting device, when the surface of the flattening film is not sufficiently flat, the thickness of the organic film formed on the flattening film varies to cause uneven brightness and a slight inclination of the electrode surface. As a result, the direction of the peak intensity of the emitted light varies or deviates from the normal direction of the display surface. As a result, the present inventor has found that display unevenness occurs.

  In a top emission type (TE type) organic EL display device in which the light of the organic light emitting element is emitted in the direction opposite to the substrate, the thin film transistor may overlap with the central portion of the pixel in plan view on the surface of the substrate. It may be formed in a region, for example 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 near the edge of a pixel so that the light of the organic light emitting element is not blocked as much as possible. However, not only in the TE type but also in the BE type, the unevenness of the surface of the substrate due to the thin film transistor or the like appears as the unevenness on the surface of the flattening film in the region overlapping with the light emitting region of the pixel, and the minute unevenness causes uneven display. I found that it was causing. Then, 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 which is the base of the organic light emitting device.

  Hereinafter, an organic EL display device according to an embodiment of the present invention and a method for manufacturing an organic EL display device will be described with reference to the drawings. Note that the materials, shapes, and relative positional relationships between the constituent elements in the embodiments described below are merely examples. The organic EL display device and the method of manufacturing the organic EL display device of the present invention are not limited to 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 the organic EL display panel 3, the data line driver 1d, and the scanning line driver 1g which are schematically shown. Has been done. The organic EL display panel 3 has a plurality of pixels 3a arranged in a matrix, and each pixel 3a is provided with an organic light emitting element 40 and a drive circuit 2. In the example of FIG. 1, each drive circuit 2 includes a drive TFT 20 that switches the energization state of the organic light emitting element 40, a switching TFT 2a that switches the drive TFT 20 on / off, and a storage capacitor 2b that holds the gate-source voltage of the drive TFT 20. Is included. The drain of the drive TFT 20 is connected to the power 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 gate via each switching TFT 2a. A current based on the voltage of the data signal flows through the organic light emitting element 40, and the organic light emitting element 40 emits light with a predetermined brightness 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 drive TFT 20 is simply referred to as “thin film transistor 20 (TFT 20)”. Further, the “pixel” referred to in the above description and the following description and each drawing is a minimum constituent element (unit element) of the display screen and is a “sub pixel” to be precise, but for simplification of description, “pixel” is used. It is called. Further, in the following description, the “surface” is 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 particularly described. Means Further, the “surface” with respect to the substrate 10 means a surface facing the organic light emitting device 40, unless the distinction is particularly described.

  FIG. 2 shows an enlarged cross section of the organic EL display panel 3, and in particular, one example of the cross section of the TFT 20 and the organic light emitting element 40 is a cathode contact (first contact 28 and second organic light emitting element 40) 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 drive circuit 2 including a thin film transistor 20 is formed, and a surface of the substrate 10 is flattened by covering the drive circuit 2. The flattening film 30 to be flattened, 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 a channel 21c, a gate electrode 23 formed on the channel 21c via a gate insulating film 22, and a source of the semiconductor layer 21. 21s and the drain 21d, the source electrode 25 and the drain electrode 26 respectively connected are included. The source electrode 25 and the drain electrode 26 are insulated from the gate electrode 23 by the interlayer insulating film 24. The organic light emitting device 40 is a top emission type (TE type) organic light emitting diode (OLED) in the example of FIG. 2, and includes a first electrode (for example, an anode) 41 and a first electrode 41 formed on the planarization film 30. There is an insulating bank 42 surrounding the above, 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 flattening film 30 is stacked on the drive circuit 2 with the first inorganic insulating film 31, 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 the opposite direction to the organic insulating film 32 has an arithmetic average roughness of 50 nm or less. Further, in the example of FIG. 2, the organic light emitting layer 43 defined by the insulating bank 42 is formed in a region which does not overlap with the contact hole 30a 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. It is covered with the planarizing film 30 and has a surface with an arithmetic average roughness (Ra) of 50 nm or less. For example, the flattening film 30 may have its surface made to have an arithmetic mean roughness of 50 nm or less by polishing after laminating each insulating film. Further, in the example of FIG. 2, the organic light emitting layer 43 is formed in a region that does not overlap the contact hole 30a in plan view.

  As described above, the present inventor has made extensive studies as to the cause of display unevenness in the organic EL display device, and as a result, has found that the surface of the organic light emitting layer in the organic light emitting element is not a perfectly flat surface but has fine irregularities. Including that, it was found that there are microscopically inclined parts. When the surface of the organic light emitting layer is tilted, its normal direction is tilted with respect to the normal direction of the display surface of 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, the brightness is lowered or the chromaticity changes depending on the intensities of the lights of R, G, and B colors.

  Conventionally, as a cause of display unevenness, variations in characteristics of TFTs and organic light emitting elements (OLEDs) forming a drive circuit have been regarded as problems, and measures against these variations have been taken. For example, a circuit for compensating for characteristic variations of TFTs and / or OLEDs has been added to each drive circuit provided for each pixel. However, such a measure may increase the cost and size because the number of constituent elements of the drive circuit increases, and may require an additional circuit for suppressing the variation of the compensation circuit itself. In the first place, such a measure does not effectively function as a measure against the display unevenness found by the present inventor, but rather, there is a fear that the unevenness of the surface of the substrate may be increased by increasing the number of constituent elements of the drive circuit. Further, the brightness 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 may be controlled based on the correction data for making it uniform. However, such measures also require complicated manufacturing processes of the organic EL display device and complicated control.

  On the other hand, in the present embodiment, as described above, in order to eliminate the newly found cause of the display unevenness, that is, in order to improve the flatness of the surface of the organic light emitting layer 43, the flattening of the underlying layer is performed. The surface of the film 30 has an arithmetic average roughness of 50 nm or less. By doing so, it is possible to obtain a display image with extremely little unevenness in brightness and color. In addition, since the thickness of the organic light emitting layer 43 is stable, it is possible to stably obtain the effect of adopting the microcavity structure that is effective for improving the intensity of emitted light and the purity of each color of R, G, and B. Therefore, it is preferable to adopt a microcavity structure for each pixel (subpixel) 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 which does not overlap the contact hole 30a and which does not overlap the contact hole 30a in a plan view. Therefore, as will be described later, display unevenness due to the contact hole 30a hardly occurs.

  The smaller the surface roughness of the flattening film 30, the more preferable, but the arithmetic average roughness of, for example, less than 20 nm, which is a target in the polishing step of the interlayer insulating film in the manufacturing process of the semiconductor device, is not necessarily required. Strict flatness in the polishing process of such a 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 flattening film 30 may have an arithmetic average roughness of 50 nm or less, and in that case, display unevenness that is perceived by humans is almost eliminated. The present inventor has found that it does not occur. Further, even considering variations in screen size and resolution, manufacturing variations in the organic light emitting device 40, and the like, a surface roughness of less than 20 nm is not necessary, but rather, in terms of ease of realization, an arithmetic average roughness of 20 nm or more is required. It has been found to be preferable. That is, the surface roughness of the flattening 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. This is preferable in terms of 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. For 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 translucent material, that is, a glass substrate, and a transparent polyimide film are 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.

  The drive circuit 2 including the 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 and the like are formed similarly to the cathode wiring 27. Although only the TFT 20 that drives the light emitting element 40 is shown in FIG. 2, the switching TFT 2a described above is also formed on the base coat layer 11, and other TFTs 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 and the like cannot be formed below the light emitting region of the organic light emitting element 40, the TFT 20 and the like are formed in the peripheral portion of the portion that planarly overlaps the light emitting region. However, even in this case, an inclined surface is formed at the boundary between the peripheral portion where the TFT 20 or each wiring is formed and the portion below the light emitting region where the TFT is not formed. Therefore, unevenness is generated in the peripheral portion of the light emitting region, which deteriorates the display quality as described above. Therefore, not only in the TE type, but also in the BE type, a flattening film 30 having a flatness on the surface thereof to the extent that such unevenness is buried and display unevenness is not required.

The TFT 20 is formed of 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 having a} thickness of about 50 nm, and the gate electrode 23 is formed by patterning after forming a film of Mo having a thickness of about 250 nm. An interlayer insulating film 24 made of a SiO ₂ film having a thickness of about 300 nm and a SiN _x film having a thickness of about 300 nm is formed on the gate electrode 23, and a source electrode 25 and a drain electrode 26 respectively connected to the source 21s and the drain 21d are formed. Has been done. Before the interlayer insulating film 24 is formed, the source 21s and the drain 21d, and the cathode wiring 27 have an impurity concentration increased by, for example, doping with boron ions, and have a low resistance by activation by annealing. A more specific structure will be described in detail later in the description of the method for manufacturing the organic EL display device. Although FIG. 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, 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. Further, the second inorganic insulating film 33 is formed. That is, the flattening film 30 having a laminated structure of three layers of inorganic film + organic film + inorganic film is formed. The flattening film 30 is provided with a contact hole 30a that collectively penetrates the first inorganic insulating film 31, the organic insulating film 32, and the second inorganic insulating film 33. As will be described later, for example, a metal such as indium tin oxide (ITO) and silver (Ag) or APC (silver + palladium + copper) is embedded in the contact hole 30a, and the drive circuit 2 is provided via this metal. And the organic light emitting element 40 are connected to each other.

  The organic insulating film 32 has a thickness of, for example, 1 μm or more and 2 μm or less. The organic insulating film 32 significantly reduces irregularities on 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, a polyimide resin or an acrylic resin. The organic insulating film 32 preferably contains an additive (leveling improving agent) 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, photopolymerization initiators such as Michler's ketone, chlorothioxanthone, and isopropylthioxanthone may weaken the effects of the above-mentioned leveling enhancer or the leveling enhancer may inhibit photopolymerization. Therefore, for the organic insulating film 32, it is preferable to use a material such as a photopolymerization initiator that does not contain a photoconductor. Even in that case, the contact hole 30a can be formed by dry etching or the like as described later. Then, by selecting a method that does not utilize photosensitivity for forming the contact hole 30a, it is possible to use an organic material having high purity such as acrylic resin as the material of the organic insulating film 32. Further, without concern about the influence on photopolymerization, a necessary and sufficient amount of the leveling improver can be added to the organic insulating film 32, or the influence of the photopolymerization initiator is eliminated, so that the required amount of the leveling improver can be reduced. You can do less. Therefore, the selection range of the amount of the leveling improver added is widened. For example, the organic insulating film 32 contains an additive that improves the flatness of the surface of the organic insulating film 32 facing the second inorganic insulating film 33 in a content ratio of 0.5% by mass or more and 5% by mass or less. Is preferred. When the organic insulating film 32 contains such an amount of the leveling improver, it becomes easy to form the flattening film 30 having a surface having an arithmetic average roughness of 50 nm or less, and moreover, the acrylic resin or the polyimide resin is used. There is little effect on the required characteristics. Examples of such leveling improvers include silicone-based, hydrocarbon-based, and fluorine-based surfactants.

  Acrylic resin is preferable as a material of the organic insulating film 32 because it is well compatible with a surfactant and has high flatness not only in terms of purity but also in 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 flattening film 30 having an arithmetic average roughness of 50 nm or less on the surface, and the content of the leveling improver in the organic insulating film 32 may not be excessive. Can be kept at.

As described above, the second inorganic insulating film 33 has an arithmetic mean roughness of 50 nm or less on the surface facing the direction opposite to the organic insulating film 32, so that the display unevenness of the organic EL display device 1 is suppressed. . The second inorganic insulating film 33 is formed of, for example, SiN _x or SiO ₂ , but SiN _x is preferable from the viewpoint of water blocking property. That is, the second inorganic insulating layer 33 improves the barrier performance against moisture in the flattening film 30.

  The second inorganic insulating film 33 may have a water blocking function not only when the organic EL display device 1 is used but also when it is manufactured. That is, as described later, the surface of the flattening 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 an 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 the cleaning agent. In this case, this cleaning agent may penetrate into the organic insulating film 32 and remain as it is, causing deterioration of the TFT 20. However, by forming the second inorganic insulating film 33, such penetration of the cleaning agent into the organic insulating film 32 and deterioration of the TFT 20 can be prevented.

  The second inorganic insulating film 33 is formed to have a thickness of, for example, 100 nm or more and 600 nm or less. 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 terms of arithmetic average roughness. The thickness of the inorganic insulating film 33 changes based on the unevenness of the surface of the organic insulating film 32 facing the second inorganic insulating film 33.

  The second inorganic insulating layer 33 has, for example, a maximum height difference DT of 3 in the unevenness of the surface of the organic insulating film 32 so that the unevenness of the surface of the organic insulating film 32 can be sufficiently buried in the second inorganic insulating layer 33. The thickness is preferably twice or more. Then, if necessary, the surface of the second inorganic insulating film 33 is preferably polished by a length (thickness) equal to or larger than the maximum height difference DT and less than twice the maximum height difference DT. By doing so, the convex portion on the surface of the second inorganic insulating film 33 based on the convex portion on the surface of the organic insulating film 32 can be scraped off without exposing the organic insulating film 32, and the surface of the planarizing film 30 can be substantially removed. The arithmetic mean roughness of 50 nm or less can be surely achieved. In that case, the second inorganic insulating film 33 may have a thickness of 1 time or more and 3 times or less of the maximum height difference DT of the unevenness of the surface on the entire surface of the organic insulating film 32. For example, in FIG. 2, the maximum thickness TL of the second inorganic insulating film 33 is 2 times or more and 3 times or less than 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 less than or equal to 3 times. Thickness TM is 1 times or more and 2 times or less than the maximum height difference DT of the unevenness of the organic insulating film 32. Particularly 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. It is substantially the same as the maximum height difference DT of the unevenness of 32.

  As described above, the contact hole 30a collectively penetrates each insulating film forming the planarizing film 30. Therefore, there is no remarkable step on the inner wall of the contact hole 30a, so that the metal can be easily embedded in the contact hole 30a. Also, cracks and the like are unlikely to occur in the metal. A contact hole 30b for forming the second contact 45 of the cathode contacts is also formed in the flattening film 30, and the contact hole 30b collectively penetrates each insulating film forming the flattening film 30. ing.

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

  When the contact hole 30a is not completely filled with ITO or the like on the surface of the first electrode 41 right above the contact hole 30a, a depression as shown in FIG. 2 may occur. However, in the example of FIG. 2, the first electrode 41 has a region that does not overlap with the contact hole 30a in plan view, which is large enough to form the organic light emitting layer 43, and on the region that does not overlap with the contact hole 30a. An organic light emitting layer 43 is formed on the. Therefore, unevenness in the thickness of the organic light emitting layer 43 and depressions on the surface thereof are less likely to occur, and uneven display due to the contact holes 30a is less likely to occur.

  An insulating bank 42 that partitions each pixel and insulates the first electrode 41 and the second electrode 44 from each other is formed on the peripheral edge of the first electrode 41. In the example of FIG. 2, the insulating bank 42 covers the depressions on the surface of the first electrode 41. Then, the organic light emitting layer 43 is stacked on the first electrode 41 surrounded by the insulating bank 42. The organic light emitting layer 43, which serves as a 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 a 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. Although the organic light emitting layer 43 is shown as a single layer in FIG. 1 and the like, it 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 a necessary portion with a mask.

Specifically, for example, as the layer in contact with the first electrode 41, a hole injection layer made of a material having a good ionization energy matching property that improves hole injection properties is provided. On this hole injection layer, a hole transport layer capable of improving stable transport of holes and confining electrons (energy barrier) to the light emitting layer is formed of, for example, an amine-based material. Further, a light emitting layer selected according to the 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. Further, on the light emitting layer, an electron transport layer that improves electron injection properties and stably transports electrons may be formed of Alq ₃ or the like. A laminated film of the organic light emitting layer 43 is formed by laminating each of these layers by several tens of nm. An electron injection layer that improves the electron injection property of LiF, Liq, or the like 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 planarizing film 30, the gate insulating film 22, and the interlayer insulating film are formed. It is connected to the cathode wiring 27 via 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. A material having a small work function is preferable for the second electrode 44, and an alkali metal, an alkaline earth metal, or the like can be used. Since Mg has a small work function of 3.6 eV, Mg is preferable, and Ag having a small work function of about 4.25 eV is co-evaporated at a ratio of about 10% by mass for imparting stability. In the BE type, since the second electrode 44 serves as a reflector, Al is formed thick as the second electrode 44.

A coating layer (TFE) 46 that prevents moisture from reaching the second electrode 44 is formed on the second electrode 44. The coating layer 46 is made of 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 coating layer 46 is preferably formed in multiple layers of different materials so that even if a pinhole is formed in one layer, a sufficient barrier property against moisture and the like can be obtained. The coating layer 46 is formed so as to completely cover the organic light emitting layer 43 and the second electrode 44. The coating layer 46 may include an organic insulating film between the two layers of 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 according to the embodiment will be described with reference to the flowchart of FIG. 3 and the cross-sectional views shown in FIGS. 4A to 4G. To be 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 by using the plasma CVD method. Although the base coat layer 11 is shown as 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, and a thickness of about 250 nm further thereon. It is formed by stacking the SiO ₂ layers of

After that, 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 dehydrogenation treatment by annealing treatment at a temperature of about 350 ° C. for about 45 minutes, for example. Then, this semiconductor film is annealed by irradiation with an excimer laser for several tens of nanoseconds, 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, each wiring (not shown) other than the cathode wiring 27, such as a scanning line and a data line, can be appropriately formed. After that, the gate insulating film 22 that covers the semiconductor layer 21 and the like is formed. The gate insulating film 22 is formed by forming a SiO ₂ film having a thickness of about 50 nm by using, for example, a plasma CVD method.

  The gate electrode 23 is formed by forming a Mo film with a thickness of about 250 nm on the gate insulating film 22 by, for example, sputtering and patterning by dry etching. Then, impurity ions (for example, boron) are doped into the semiconductor layer 21 at a high concentration 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 of the semiconductor layer 21 doped with the impurity ions is made low in resistance, and the semiconductor layer 21 has the source 21s and the drain 21d made of the low resistance region and the channel 21c made of the region immediately below the gate 23. It is provided. The annealing is performed at a temperature of about 350 ° C. for about 45 minutes, for example. At this time, the cathode wiring 27 and each wiring appropriately formed other than the cathode wiring 27 are also reduced in resistance by ion doping and annealing.

After that, the interlayer insulating film 24 is formed on the entire surfaces of the gate insulating film 22 and the gate electrode 23, and the contact hole 24a exposing a part of the source 21s and the drain 21d is formed. The interlayer insulating film 24 is formed by using, for example, a plasma CVD method to form a laminated film of a lower layer mainly made of SiO ₂ and having a thickness of about 300 nm and an upper layer mainly made of SiN _x and having 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.

  After that, by depositing a metal, the metal is embedded in the contact hole 24a 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 by using, for example, sputtering, and further stacking a Ti film of about 100 nm thereon. To be done. By patterning this metal film using photolithography and dry etching, the source electrode 25 and the drain electrode 26 respectively 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 that for forming 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 of forming the drive circuit 2 is merely an example of the top gate type polysilicon TFT illustrated in FIG. 2, and a bottom gate type TFT may be formed. , May be formed by any other method.

Then, as shown in FIG. 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 depositing a film of SiN _x or SiO _{2 having} a thickness of about 200 nm by, for example, a plasma CVD method. The first inorganic insulating film 31 functions as a barrier layer that prevents the components of the organic insulating film 32 from contacting the TFT 20. The organic insulating film 32 fills up the irregularities formed by the formation of the TFT 20 and the like, and is formed by applying a liquid or low-viscosity paste 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 a slit coating method and a spin coating method, but a slit & spin coating method combining both methods may be used. The organic insulating film 32 is formed to have a thickness of 1 μm or more and 2 μm or less. As a material of the organic insulating film 32, for example, a polyimide resin or an acrylic resin can be used. A photosensitive resin in which a photopolymerization initiator (photoreceptor) such as Michler's ketone, chlorothioxanthone, or isopropylthioxanthone is added to these resins may be used. However, the non-photosensitive resin containing no photoconductor is preferable because it has high purity and the surface smoothness of the organic insulating film 32 is high. Acrylic resin is particularly preferable.

Like 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 by using, for example, plasma CVD. By forming the second inorganic insulating film 33, it is possible to prevent permeation of various solvents such as a cleaning agent used in a later step into the organic insulating film 32 and the resulting deterioration of the TFT 20.

  The second inorganic insulating film 33 is for preventing unevenness of the surface of the organic insulating film 32, which may be caused by unevenness of the surface of the substrate 10, from appearing on the surface of the flattening film 30 (the surface of the second inorganic insulating film 33). belongs to. Therefore, the second inorganic insulating film 33 is preferably formed to have a thickness selected based on the maximum height difference DT of the unevenness 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 at least twice 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 recess of the surface of the organic insulating film 32 can be surely 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 of 2 times or more and 3 times or less of the maximum height difference DT of the unevenness on the surface of the organic insulating film 32. By doing so, it is possible to surely fill the recess of the organic insulating film 32 as described above. Further, without increasing the thickness of the second inorganic insulating film 33 more than necessary, the unevenness based on the unevenness of the surface of the organic insulating film 32 that may appear on the surface of the second inorganic insulating film 33 after forming the film is surely ensured in the polishing step described later. The exposure of the organic insulating film 32 after polishing can be prevented almost certainly.

  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 inventors have found that when the surface of the flattening film 30 that is the base of the organic light emitting device 40 (see FIG. 2) is not sufficiently flat, display unevenness may occur in the organic EL display device. It was Therefore, the surface of the second inorganic insulating film 33 forming the surface of the flattening 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, it is possible to prevent display unevenness that is perceived by humans from occurring, as described above. Further, in the flattening of the surface of the flattening film 30, it is not always necessary to obtain the arithmetic average roughness of less than 20 nm which is a target in the manufacturing process of the semiconductor device. Rather, in order to avoid a complicated and time-consuming polishing step including a surface roughness inspection, the surface of the second inorganic insulating film 33 may be polished to have 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, for example, at least part of the amount of polishing (the amount of decrease in the thickness of the second inorganic insulating film 33 due to polishing) the surface of the organic insulating film 32. The maximum height difference DT of the irregularities is polished to be 1 time or more and less than 2 times. By doing so, as described above, when the second inorganic insulating layer 33 is formed to have a thickness of at least twice the maximum height difference DT of the unevenness of the organic insulating film 32, the second inorganic insulating layer 33 is formed based on the unevenness of the organic insulating film 32. The unevenness that may appear on the surface of the second inorganic insulating film 33 after the film formation can be surely leveled, and furthermore, the exposure of the organic insulating film 32 due to polishing can be almost certainly prevented. For example, in the example of FIG. 4C, the polishing amount P1 in a region that was a convex portion on the surface of the second inorganic insulating film 33 after film formation (for example, a region where the TFT 20 is formed) is unevenness on the surface of the organic insulating film 32. Is about twice the maximum height difference DT. Further, in the example of FIG. 4C, the polishing amount P2 in a region that is a concave portion on the surface of the second inorganic insulating film 33 after film formation (for example, a region where the TFT 20 is not formed) is the maximum of the unevenness of the organic insulating film 32. Although it is almost the same as the height difference DT, the amount is slightly lower.

The method of 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. In the case of CMP polishing, the effect of mechanical polishing can be increased by the surface chemical action of the polishing agent, and a smooth polished surface can be quickly obtained. Cerium has a high hardness, and its oxide, ceria (CeO ₂ ) causes a chemical reaction with glass, and thus can be an effective polishing agent for the second inorganic insulating film 33 formed of SiO ₂ or the like. Colloidal silica is a colloid of SiO ₂ or its hydrate, which usually has a particle size of 10 nm to 300 nm, and fumed silica (also called dry silica or highly dispersed silica) is a true spherical shape having a particle size of 10 nm to 30 nm. Of SiO ₂ particles are agglomerated (particle diameter 100 nm to 400 nm), and both effectively function 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-mentioned 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 by using the neutral alcohol liquid together with the above-mentioned 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, contact holes 30a are formed so as to collectively penetrate these three insulating films. The contact hole 30a is preferably formed in a region where the organic light emitting layer 43 is not formed in the thickness direction of the substrate 10 in the formation of the organic light emitting layer 43 (see FIG. 4F) described later. By doing so, the occurrence of display unevenness can be prevented as described above. The contact hole 30a is formed by dry etching, for example, after forming a resist mask, like 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 flattening film 30, when wet etching is used, the etching rates of the two are different, so that a step may occur on the inner wall of the hole. In that case, the problem that the inside of the contact hole 30a is not completely filled with metal in the process described later and the contact resistance with the source electrode 25 or the like increases tends to occur. However, by using dry etching, it is possible to form the contact hole 30a having an inner wall with few steps in the flattening film 30 in which an inorganic film and an organic film are mixed. At the time of forming the contact hole 30a, a contact hole 30b for the first contact 45 (see FIG. 2) is formed in the flattening film 30 above the first contact 28 in the same manner as the contact hole 30a. It

  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, using 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. To be done. As a result, a metal is embedded inside the contact hole 30a, 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 flattening film 30. Then, 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 which does not overlap with the contact hole 30a in a plan view and is large enough to form the organic light emitting layer 43. It The second contact 45 is formed by filling the contact hole 30a with at least the ITO film and the Ag film or the APC film when the metal is embedded in the contact hole 30a.

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 on the peripheral portion 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 surfaces of the flattening film 30 and the first electrode 41, and the patterning thereof exposes a predetermined region of the first electrode 41. Preferably, the region of the first electrode 41 that does not overlap the contact hole 30a in the thickness direction of the substrate 10 is exposed. The insulating bank 42 is formed to have a height of about 1 μm. As described above, various organic materials are stacked in forming the organic light emitting layer 43. The stacking of the organic material is performed by, for example, vacuum vapor deposition, and in that case, the organic material is vapor-deposited through a vapor deposition mask having openings corresponding to desired subpixels such as R, G, and B. A layer of LiF or the like may be formed on the surface of the organic light emitting layer 43 to improve the electron injection property. 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 of 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 is 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 mass% and Ag is 10%. It is contained in a proportion of about mass%. The second electrode 44 is formed to have a thickness of, for example, about 10 to 20 nm.

A coating layer 46 (see FIG. 2) that protects the second electrode 44 and the organic light emitting layer 43 from moisture or oxygen is formed on the second electrode 44. Since the coating layer 46 protects the second electrode 44 and the organic light emitting layer 43 which are weak against moisture or oxygen, an inorganic insulating film such as SiO ₂ or SiN _x that hardly absorbs moisture is formed by using a plasma CVD method or the like. Is formed by The coating layer 46 is preferably formed so that its end portion is in close contact with an inorganic film such as the second inorganic insulating film 33. This is because the inorganic films are bonded to each other with good adhesion. By doing so, it is possible to more reliably prevent the infiltration of water 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 drive circuit including a thin film transistor is formed, and a planarization for flattening the surface of the substrate by covering the drive circuit. A first inorganic layer formed on the surface of the flattening film and electrically connected to the driving circuit, the flattening film being laminated on the driving circuit. An organic insulating film stacked on the first inorganic insulating film; and a second inorganic insulating film stacked on the organic 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), it is possible to reduce uneven brightness or uneven color 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 mean 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 having a highly flat surface is easily obtained, and a flattening film having a surface having 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), the 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. May be. In that case, it may be easy to form a flattening film having a surface with an arithmetic mean roughness of 50 nm or less, and the content of the leveling improver in the organic insulating film may be kept to an extent not excessive.

(5) In the organic EL display device according to (4), the organic insulating film contains an additive that improves the flatness of the surface of the organic insulating film in an amount of 0.5% by mass or more and 5% by mass or less. May be included in. In that case, it becomes easy to form a flattening film having a surface having an arithmetic average roughness of 50 nm or less, and the characteristics required for the resin material forming 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. They may be connected via a metal embedded in a contact hole that collectively penetrates the insulating film. In that case, the drive circuit and the organic light emitting element are reliably connected to each other 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 the unevenness of the surface of the organic insulating film facing the second inorganic insulating film. And the maximum height difference of the unevenness over the entire surface of the organic insulating film may be 1 time or more and 3 times or less. In that case, the unevenness on 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 driving circuit including a thin film transistor on a substrate, and a first inorganic insulating film and an organic insulating film on the surface of the driving circuit. A step of forming a film and a second inorganic insulating film, a step of polishing the surface of the second inorganic insulating film, the second inorganic insulating film, the organic insulating film and the first inorganic insulating film, and the drive circuit. To form a contact hole, a step of forming a first electrode in a predetermined region while burying a metal in the contact hole, and 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 less unevenness in brightness or color.

(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 have an arithmetic average roughness of 50 nm or less by CMP polishing. By doing so, the surface of the flattening film can be rapidly polished to a surface roughness that does not substantially cause display unevenness.

(10) In the method of manufacturing an organic EL display device according to (9), in polishing 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. You may grind to. By doing so, it is possible to obtain a surface roughness that does not substantially cause display unevenness in the flattening film, and it is possible to avoid a complicated polishing process that requires a long time.

(11) In the method of 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 to form the second inorganic insulating film. The surface of the membrane 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 (8) to (11) above, 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. In the polishing of the surface of 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 above, and the reduction amount of the thickness of the second inorganic insulating film due to the polishing. May be at least partially greater than or equal to 1 time and less than twice the maximum height difference, and the second inorganic insulating film may be polished. By doing so, the unevenness that may appear on the surface of the second inorganic insulating film after the film formation can be surely leveled based on the unevenness of the organic insulating film, and the exposure of the organic insulating film due to polishing can be almost surely performed. Can be prevented.

(13) In the method of manufacturing an organic EL display device according to (12) above, in the formation of the second inorganic insulating film, the second inorganic insulating film is formed to a thickness of 2 times or more and 3 times or less of the maximum height difference. It may be formed. By doing so, the recess of the organic insulating film can be surely filled without making the second inorganic insulating film thicker than necessary.

(14) In the method for 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 possible to prevent an increase in the contact resistance between the organic light emitting element and the drive circuit because a step is unlikely to occur on the inner wall of the contact hole.

(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 that does not overlap with a region where the organic light emitting layer is to be formed in the thickness direction of the substrate. You may. By doing so, it is possible to prevent depressions from being formed on the surface of the organic light emitting layer, and prevent deterioration of display quality.

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 Flattening Film 30a, 30b Contact Hole 31 First Inorganic Insulating Film 32 Organic Insulating Film 33 Second Inorganic Insulating Film 40 Organic Light Emitting Element (OLED)
41 first electrode 43 organic light emitting layer 44 second electrode

Claims (12)

A substrate having a surface on which a drive 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 device formed on the surface of the planarization film and electrically connected to the drive circuit,
The flattening 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 Including an inorganic insulating film,
A surface of the second inorganic insulating film that faces away from the organic insulating film has an arithmetic mean roughness of 50 nm or less;
An organic EL device in which the organic insulating film contains an additive for improving the flatness of the surface of the organic insulating film facing the second inorganic insulating film in an amount of 0.5% by mass or more and 5% by mass or less. Display device. A substrate having a surface on which a drive 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 device formed on the surface of the planarization film and electrically connected to the drive circuit,
The flattening 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 Including an inorganic insulating film,
A surface of the second inorganic insulating film that faces away from the organic insulating film has an arithmetic mean roughness of 50 nm or less;
The thickness of the second inorganic insulating film varies based on the 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 2 times or more and 3 times or less of 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 in which the difference in maximum height of the unevenness of the film is 1 to 2 times.   The organic EL display device according to claim 1, wherein the organic insulating film contains 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 collectively penetrates the first inorganic insulating film, the organic insulating film, and the second inorganic insulating film. The organic EL display device according to any one of claims 1 to 4. A step of forming a driver 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;
Embedding a metal inside 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,
An organic EL device in which the organic insulating film contains an additive for improving the flatness of the surface of the organic insulating film facing the second inorganic insulating film in an amount of 0.5% by mass or more and 5% by mass or less. Manufacturing method of display device.   In the polishing of the surface of the second inorganic insulating film, CMP polishing using a neutral slurry containing cerium, colloidal silica, or fumed silica as an abrasive is performed to reduce the surface of the second inorganic insulating film to 50 nm or less. The method for manufacturing an organic EL display device according to claim 6, wherein polishing is performed to an arithmetic average roughness.   The method of manufacturing an organic EL display device according to claim 7, wherein in the polishing of the surface of the second inorganic insulating film, a neutral alcohol liquid is used together with the polishing agent to polish the surface of the second inorganic insulating film. .. In the formation of the second inorganic insulating film, the second inorganic insulating film is formed with a thickness that is at least twice 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 at least 1 time and less than 2 times the maximum height difference. The method for manufacturing an organic EL display device according to claim 6, wherein the second inorganic insulating film is polished.   The method of manufacturing an organic EL display device according to claim 9, wherein in forming the second inorganic insulating film, the second inorganic insulating film is formed to have a thickness that is 2 times or more and 3 times or less 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 not formed and a region that does not overlap in the thickness direction of the substrate.

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