JP2009211896A - Manufacturing method of display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a display device capable of preventing formation of a leakage path caused by a conductive foreign matter generated in the manufacturing process of a transistor element, between the transistor element and a light-emitting element formed on a substrate. <P>SOLUTION: The manufacturing method of the display device comprises: a process of forming a transistor element 501 on a substrate 502, a process to form a flattening film 510 on the substrate 502, in a state of covering the transistor element 501; a process of applying an oxidation treatment with the upper face of the flattening film 510 as a treating surface; and a process of forming a light-emitting element on the planarizing film 510. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a display device having a transistor element and a light emitting element.

  In recent years, as one of flat panel displays, a display device that displays an image using an organic EL (Electro Luminescence) element as a light emitting element (hereinafter referred to as an “organic EL display device”) has attracted attention. The organic EL display device has excellent features such as a wide viewing angle and low power consumption because it utilizes the light emission phenomenon of the organic EL element itself. Furthermore, since it exhibits high responsiveness to high-definition high-speed video signals, development for practical use is being promoted particularly in the video field.

  Among the driving methods for organic EL display devices, the active matrix method using a thin film transistor (TFT) driving element is superior to the conventional passive matrix method in terms of responsiveness and resolving power. It is considered to be a driving method particularly suitable for organic EL display devices having features.

  An active matrix type organic EL display device includes a drive panel provided with at least an organic EL element having an organic light emitting material and a drive element (TFT) for driving the organic EL element. The panel has a configuration in which an organic EL element is sandwiched through an adhesive layer. As a TFT constituting an active matrix organic EL display device, at least two transistors are required for each pixel (for example, a switching transistor for controlling the brightness of a pixel and a driving transistor for controlling light emission of the organic EL element). .

  FIG. 9 is a sectional view showing the structure of a TFT element and an organic EL element applied to an active matrix type organic EL display device. The TFT element 501 includes a gate electrode 503, a gate insulating film 504, a channel layer 505, a channel protective layer 506, a contact layer 507, a source electrode 508s, a drain electrode 508d, and the like formed over the substrate 502.

  The board | substrate 502 is a board | substrate which has electrical insulation, such as resin or glass, for example. The gate electrode 503 is formed, for example, by forming a molybdenum metal film into a strip shape. The gate insulating film 504 is a silicon inorganic material, for example, a single layer film of SiNx or SiOx, or a laminated film of SiNx and SiOx. The channel layer 505 is a semiconductor layer made of amorphous silicon or microcrystalline silicon. The channel protective layer 506 serves as an etching stop layer that prevents the channel portion from being corroded during etching of the source / drain electrodes and the semiconductor layer 505 in the TFT element manufacturing process.

  The contact layer 507 is an ohmic contact layer containing phosphorus or the like. The source electrode 508s and the drain electrode 508d are, for example, titanium or aluminum, or a metal layer obtained by stacking them. A passivation film 509 made of, for example, SiNx is formed on the TFT element 501 having the above configuration.

  A planarizing film 510 is formed on the TFT element 501 so as to cover it. On the planarizing film 510, an organic EL element 511 serving as a light emitting element is formed. The organic EL element 511 mainly includes a lower electrode 512, an organic layer 513, and an upper electrode 514. The organic layer 513 includes at least a light-emitting layer. For example, the organic layer 513 has a four-layer structure of a hole injection layer, a hole transport layer, a light-emitting layer, and an electron transport layer, or a five-layer structure in which an electron injection layer is added thereto. It has become. The organic EL element 511 is separated (divided) for each pixel by an insulating film pattern 515. In addition, a contact portion 516 for electrically connecting the TFT element 501 and the organic EL element 511 is formed on the planarizing film 510. The upper electrode 14 of the organic EL element 511 is covered with a protective film 517.

  By the way, among many pixels constituting the display screen of the organic EL display device, there may be a bright spot that becomes a pixel that always emits light in a power-on driving state or a dark spot that becomes a pixel that does not emit light. Since these bright pixels and dark spots, which are abnormal pixels, greatly reduce the display quality, it is necessary to suppress their occurrence. The cause of the occurrence of an abnormal pixel is one that occurs in a process of creating a TFT element (hereinafter referred to as “TFT element creation process”) or one that occurs after the TFT element creation process. Among these, one of the causes that occur after the TFT device fabrication process is that conductive dust (fine dust) or the like adheres to the lower electrode, which causes a leak path between the lower electrode and the upper electrode. , May be a dark spot.

  For example, Patent Documents 1 to 3 listed below have been proposed as a method for avoiding a dark spot caused after the TFT element creation process. In Patent Document 1, the generation of the leak path is prevented by forming an insulating film between the lower electrode and the organic layer. In Patent Document 2, the occurrence of the leak path is prevented by forming a high-resistance hole injection layer as a buffer layer between the lower electrode and the organic layer. Further, in Patent Document 3, the occurrence of the leak path is prevented by increasing the resistance of the surface layer of the lower electrode.

Japanese Patent Laid-Open No. 11-224781 JP 2001-35667 A JP 2006-338916 A

  However, the proposals described in the above Patent Documents 1 to 3 are effective in preventing bright spots and dark spots caused by the steps after the TFT element creation, but the bright spots caused during the TFT element creation process are effective. It is not effective in preventing dots and dark spots. That is, among the causes of bright spots and dark spots that occur during the TFT element creation process, patterning defects may occur due to the generation of dust (fine dust) during the resist coating process, film formation process, etching process, The dust itself remains on the substrate and may cause abnormal pixels such as bright spots and dark spots. For this reason, for example, as shown in FIG. 10, during the TFT element creation process, the conductive foreign matter 520 remains in contact (electrically connected) with the wiring 521 connected to the TFT element 501, and a part of the foreign matter 520 is left. When the lower electrode 512 of the organic EL element 511 is formed in a state of protruding from the upper surface of the planarizing film 510, a leak path is formed between the lower electrode 512 of the organic EL element 511 and the TFT element 501. It becomes a bright spot which is one of the normal pixels.

  The present invention can prevent a leak path from being formed between a transistor element formed on a substrate and a light emitting element due to conductive foreign matter generated during the manufacturing process of the transistor element. An object of the present invention is to provide a method for manufacturing a display device.

  The method for manufacturing a display device according to the present invention includes a step of forming a transistor element on a substrate, a step of forming a planarization film on the substrate so as to cover the transistor element, and an upper surface of the planarization film. It has the process of performing an oxidation process as a process surface, and the process of forming a light emitting element on the said planarization film | membrane.

  In the method for manufacturing a display device according to the present invention, at the stage where the planarization film is formed so as to cover the transistor elements formed on the substrate, an oxidation process is performed using the upper surface of the planarization film as a surface to be processed. When the conductive foreign matter adhering during the manufacturing process of the transistor element protrudes from the upper surface of the planarizing film, the protruding portion is made non-conductive by the oxidation treatment. Therefore, a leak path is not formed between the transistor element and the light emitting element due to the foreign matter.

  According to the present invention, it is possible to form a leakage path between a transistor element formed on a substrate and a light emitting element due to a conductive foreign matter generated during the manufacturing process of the transistor element. Can be prevented. Therefore, it is possible to provide a high-quality organic EL display device that suppresses the occurrence of abnormal pixels such as bright spots and dark spots.

  Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings. It should be noted that the technical scope of the present invention is not limited to the embodiments described below, and various modifications and improvements have been made within the scope of deriving specific effects obtained by the constituent requirements of the invention and combinations thereof. Also includes form.

  FIG. 1 is a cross-sectional view illustrating a configuration example of an organic EL display device. The illustrated organic EL display device 1 is configured using a plurality (large number) of organic EL elements 2. The organic EL element 2 is divided for each unit pixel by the difference in emission colors of R (red), G (green), and B (blue). However, FIG. 1 shows only one of them.

  The organic EL element 2 is configured using an element forming substrate 3. On the element forming substrate 3, a lower electrode 4, an insulating layer 5, an organic layer 6, and an upper electrode 7 are sequentially laminated together with a TFT (thin film transistor) element serving as a switching element (not shown). Further, the upper electrode 7 is covered with a protective layer 8, and a counter substrate 10 is disposed on the protective layer 8 via an adhesive layer 9. The organic EL element 2 has a structure in which an organic layer 6 made of an organic material is sandwiched between a lower electrode 4 and an upper electrode 7.

  The element forming substrate 3 and the counter substrate 10 are each composed of a transparent glass substrate. The element forming substrate 3 and the counter substrate 10 face each other in such a manner that the lower electrode 4, the insulating layer 5, the organic layer 6, the upper electrode 7, the protective layer 8, and the adhesive layer 9 are sandwiched between the two substrates. It is arranged in a state to do.

  One of the lower electrode 4 and the upper electrode 7 serves as an anode electrode, and the other serves as a cathode electrode. The lower electrode 4 is made of a highly reflective material when the organic EL display device 1 is a top emission type, and is made of a transparent material when the organic EL display device 1 is a transmissive type.

  Here, as an example, it is assumed that the organic EL display device 1 is a top emission type and the lower electrode 4 is an anode electrode. In this case, the lower electrode 4 is made of, for example, silver (Ag), aluminum (Al), chromium (Cr), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), tantalum (Ta), tungsten (W), platinum (Pt), and gold (Au), such as a highly reflective conductive material or an alloy thereof.

  When the organic EL display device 1 is a top emission type and the lower electrode 4 is a cathode electrode, the lower electrode 4 is made of, for example, an aluminum (Al), indium (In), magnesium (Mg) -silver (Ag) alloy. , Such as a lithium (Li) -fluorine (F) compound and a lithium-oxygen (O) compound, which are made of a conductive material having a small work function and high light reflectance.

  When the organic EL display device 1 is a transmissive type and the lower electrode 4 is an anode electrode, the lower electrode 4 is, for example, ITO (Indium-Tin-Oxide) or IZO (Indium-Zinc-Oxide). It is composed of a conductive material with high transmittance. When the organic EL display device 1 is a transmissive type and the lower electrode 4 is a cathode electrode, the lower electrode 4 is made of a conductive material having a low work function and high light transmittance.

  The insulating layer 5 is formed on the upper surface of the element forming substrate 3 so as to cover the periphery of the lower electrode 4. A window is formed in the insulating layer 5 for each unit pixel, and the lower electrode 4 is exposed at the opening of the window. The insulating layer 5 is formed using an organic insulating material such as polyimide or photoresist, or an inorganic insulating material such as silicon oxide.

  For example, as shown in FIG. 2, the organic layer 6 includes a hole injection layer 61, a hole transport layer 62, a light emitting layer 63 (63 r, 63 g, 63 b) and an electron transport layer 64 in order from the element forming substrate 3 side. It has a laminated structure of four layers.

  The hole injection layer 61 is formed of, for example, m-MTDATA [4,4,4-tris (3-methylphenylphenylamino) triphenylamine]. The hole transport layer 62 is formed of, for example, α-NPD [4,4-bis (N-1-naphthyl-N-phenylamino) biphenyl]. Note that the material is not limited to this, and hole transport materials such as a benzidine derivative, a styrylamine derivative, a triphenylmethane derivative, and a hydrazone derivative can be used. Moreover, the hole injection layer 61 and the hole transport layer 62 may each have a laminated structure including a plurality of layers.

  The light emitting layer 63 is formed of a different organic light emitting material for each RGB color component. Specifically, the red light emitting layer 63r includes, for example, 2,6≡bis [(4′≡methoxydiphenylamino) styryl] ≡1,5≡dicyanonaphthalene (BSN) as a dopant material to ADN as a host material. It is composed of a mixture of 30% by weight. The green light emitting layer 63g is composed of, for example, 5% by weight of coumarin 6 as a dopant material mixed with ADN as a host material. For example, the blue light emitting layer 63b is formed by adding 4,4′≡bis [2≡ {4≡ (N, N≡diphenylamino) phenyl} vinyl] biphenyl (DPAVBi) as a dopant material to ADN as a guest material. Consists of a mixture by weight%. The light emitting layers 63r, 63g, and 63b for each color are arranged in a matrix according to the color arrangement of the pixels.

  The electron transport layer 64 is made of, for example, 8≡hydroxyquinoline aluminum (Alq3). The organic layer 6 is not limited to the four-layer structure illustrated here, and may be any layer including at least a light emitting layer. For example, in addition to the above-described four-layer structure (hole injection layer, hole transport layer, light emitting layer, electron transport layer), a five-layer structure including an electron injection layer (not shown) may be used. It may be a structure having a smaller or larger number of layers.

  The upper electrode 7 is made of a transparent or translucent conductive material when the organic EL display device 1 is a top emission type, and is made of a highly reflective material when the organic EL display device 1 is a transmission type. Is done.

  The element forming substrate 3, the lower electrode 4, the insulating layer 5, the organic layer 6, and the upper electrode 7 constitute the organic EL element 2 (red organic EL element 2r, green organic EL element 2g, blue organic EL element 2b). Has been.

  The protective layer 8 is formed for the purpose of preventing moisture from reaching the upper electrode 7 and the organic layer 6. For this reason, the protective layer 8 is formed with sufficient film thickness using a material with low water permeability and water absorption. Further, since the protective layer 8 needs to transmit light emitted from the organic layer 6 when the organic EL display device 1 is a top emission type, it is made of a material having a light transmittance of about 80%, for example. Composed.

  If the upper electrode 7 is formed of a metal thin film and the insulating protective layer 8 is formed directly on the metal thin film, an inorganic amorphous insulating material, for example, as a material for forming the protective layer 8 is used. Amorphous silicon (α-Si), amorphous silicon carbide (α-SiC), amorphous silicon nitride (α-Si1-xNx), and amorphous carbon (α-C) can be preferably used. Such an inorganic amorphous insulating material does not constitute grains, and therefore has a low water permeability and becomes a good protective layer 8.

  The adhesive layer 9 is formed of, for example, a UV (ultraviolet) curable resin. The adhesive layer 9 is for fixing the counter substrate 10.

  Although illustration is omitted here, when the organic EL display device 1 having such a configuration is provided with a combination of color filters, light emission emitted from the organic EL elements 2r, 2g, and 2b corresponding to each color of RGB. A color filter that transmits only light in the vicinity of the peak wavelength of the spectrum is provided on the light extraction surface side of each color organic EL element 2r, 2g, 2b.

<Configuration of drive circuit>
FIG. 3 is a diagram illustrating a configuration example of a drive circuit of the organic EL display device. The drive circuit of the organic EL display device 1 is formed on the element forming substrate 3. More specifically, the display area 11 and its peripheral area 12 are set on the element forming substrate 3. In the display area 11, a plurality of scanning lines 13 and a plurality of signal lines 14 are wired in a matrix form vertically and horizontally. One pixel 15 is provided at each intersection of the scanning line 13 and the signal line 14. Each pixel 15 is provided with a pixel circuit including the organic EL element 2 described above. In the peripheral region 11, a scanning line driving circuit 16 that scans and drives the scanning lines 13 and a signal line driving circuit 17 that supplies a video signal (that is, an input signal) corresponding to luminance information to the signal line 14 are arranged. Yes.

<Configuration of pixel circuit>
FIG. 4 is a diagram illustrating a configuration example of a pixel circuit. The pixel circuit includes, for example, an organic EL element 2, a driving transistor Tr1, a writing transistor (sampling transistor) Tr2, and a storage capacitor Cs. The transistors Tr1 and TR2 are both composed of TFT elements. In this pixel circuit, the video signal written from the signal line 14 via the write transistor Tr2 is held in the holding capacitor Cs by driving the scanning line driving circuit 16, and a current corresponding to the held signal amount is supplied to the drive transistor Tr1. Is supplied to the organic EL element 2, and the organic EL element 2 emits light with a luminance corresponding to the current value.

  Note that the configuration of the pixel circuit as described above is merely an example, and the pixel circuit may be configured by providing a capacitive element in the pixel circuit or further providing a plurality of transistors as necessary. Further, a necessary drive circuit may be added to the peripheral region 12 according to the change of the pixel circuit.

  5 to 8 are process diagrams for explaining a method of manufacturing an organic EL display device according to an embodiment of the present invention. In the following description of the manufacturing method, the same reference numerals are assigned to the same components as those described in the “background art”. First, as shown in FIG. 5A, a molybdenum film having a thickness of 100 nm, for example, is formed by sputtering, for example, on a substrate 502 made of an insulating substrate, and then known photolithography and etching are performed. Thus, the gate electrode 503 is patterned in a strip shape. Thereafter, a gate insulating film 504 made of, for example, a silicon oxide film, a silicon nitride film, or a laminated film thereof is formed on the substrate 502 by, for example, a plasma CVD method so as to cover the gate electrode 503, and has a thickness of 200 nm to 400 nm, for example, 300 nm. Form with.

  Next, as shown in FIG. 5B, a channel layer 505 made of, for example, amorphous silicon is formed with a film thickness of 10 nm to 30 nm, for example, 15 nm on the gate insulating film 504. Note that in the case where a microcrystalline silicon layer is used as the channel layer 505, the amorphous silicon layer may be formed and then microcrystallized by a method such as laser annealing.

  Next, as shown in FIG. 5C, a silicon nitride film having a thickness of 200 nm is formed over the gate insulating film 504 so as to cover the channel layer 505, and then performing known photolithography and etching. The channel protective layer 506 is patterned on the channel layer 505 so as to cover it. As the etching, for example, wet etching using a solution made of hydrofluoric acid can be applied. Next, a silicon layer containing n-type impurities including phosphorus is formed as a contact layer 507 over the channel layer 505 so as to cover the channel protective layer 506. In this case, for example, the film can be formed by a plasma CVD method using monosilane and hydrogen as a film forming gas and phosphine as an n-type impurity. It should be noted that deposition parameters such as pressure and discharge power other than the gas flow rate are appropriately set. Here, the thickness of the n-type silicon layer may be 100 nm.

  After that, as shown in FIG. 5D, the contact layer 507 and the channel layer 505 thereunder are patterned in an island shape through photolithography and etching processes. At this time, a contact hole (not shown) to the gate electrode 503 is formed.

  Next, as shown in FIG. 6 (A), a three-layer metal layer 508 made of, for example, titanium / aluminum / titanium is covered with, for example, 50 nm / 100 nm / with the channel layer 505 covered with the patterned contact layer 507 and channel layer 505. The film is formed with a thickness of 50 nm.

  Next, as shown in FIG. 6B, through the photolithography and etching process, the three metal layers 508 are separated on the channel layer 505 above the central portion of the gate electrode 503 together with the contact layer 507 therebelow. Thus, the source electrode 508s and the drain electrode 508d are formed on the channel layer 505. In the etching between the source electrode 508s and the drain electrode 508d, the channel protective layer 506 functions as an etching stop layer.

  Thereafter, as shown in FIG. 6C, a passivation film 509 made of, for example, a silicon nitride film is formed to a thickness of 200 nm so as to cover the entire area on the substrate 502. Subsequently, a contact hole (not shown) to the drain electrode 508d is formed. Thus, the TFT element 501 is formed on the substrate 502.

  Next, as shown in FIG. 7A, a planarizing film 510 is formed over the substrate 502 so as to cover the TFT element 501. The planarizing film 510 may be formed by applying a material such as polyimide or an acrylic agent, for example. At this time, if conductive foreign matter adheres on the substrate 502 (on the TFT element 501) during the manufacturing process of the TFT element 501, the foreign matter is removed from the upper surface of the planarizing film 510 at the stage where the planarizing film 501 is formed. Some may protrude. As the conductive foreign matter generated during the manufacturing process of the TFT element 501, for example, metal generated when a three-layer (titanium / aluminum / titanium) metal film constituting the source electrode 508S and the drain electrode 508D is formed by sputtering. It is conceivable that the particles are generated due to defective patterning of wiring, or dust generated during dry etching processing of wiring. When the organic EL element 511 is formed in a state where such conductive foreign matter protrudes from the planarizing film 510, elements of the element that should originally be insulated by the planarizing film 510, for example, the wiring of the TFT element 501 (particularly, , A source electrode 508s, a drain electrode 508d, etc.) and the lower electrode 512 of the organic EL element 511, and this causes a bright spot defect that is an abnormal pixel.

  Therefore, in this embodiment mode, after the planarization film 510 is formed and before the organic EL element 511 is formed, the upper surface of the planarization film 510 is treated as shown in FIG. As shown in FIG. As the oxidation treatment, for example, ozone oxidation treatment (ozone water cleaning treatment), oxygen plasma treatment, or the like can be applied. At this time, for example, as shown in FIG. 8A, conductive foreign matter (metal particles or the like) 520 protrudes from the upper surface of the planarizing film 510 and the end of the foreign matter 520 contacts the wiring 521 connected to the TFT element 501. If (electrically connected), the surface of the foreign material 520 is oxidized by the oxidation treatment. Therefore, as shown in FIG. 8B, an oxide film 522 is generated by an oxidation process on the surface of the foreign matter 520 protruding from the upper surface of the planarization film 510, and the surface of the foreign matter 520 is covered by the oxide film 522. It will be in the state.

  Thereafter, as shown in FIG. 8C, a contact hole 516 for electrically connecting the TFT element 501 and the organic EL element 511 is formed in the planarization film 501, and then the contact hole 516 is filled with an electrode material. A lower electrode 512 is formed in a predetermined pattern on the planarizing film 501 in a form. Next, after surrounding the lower electrode 512 with an insulating film pattern 515 in pixel units, an organic layer 513 including at least a light emitting layer is stacked on the lower electrode 512 exposed from the insulating film pattern 515. Next, the upper electrode 514 is formed so as to cover the organic layer 513 and the insulating film pattern 515, and the protective film 517 is further formed so as to cover this upper electrode 514. As a result, the organic EL element 511 is formed on the substrate 502 above the TFT element 501. The lower electrode 512, the organic layer 513 and the upper electrode 514 constituting the organic EL element 511 correspond to the lower electrode 4, the organic layer 6 and the upper electrode 7 constituting the organic EL element 2 in FIG. .

  In the method of manufacturing the organic EL display device described above, it is assumed that the conductive foreign matter 520 is attached during the manufacturing process of the TFT element 501, and the planarizing film 510 is formed in a state in which a part of the foreign matter 520 protrudes. Even in this case, by covering the surface of the foreign material 520 with the oxide film 522 generated by the oxidation treatment, the protruding portion can be made nonconductive. For this reason, a leak path is not formed between the lower electrode 512 of the organic EL element 511 and the wiring 521 connected to the TFT element 501 therebelow. Therefore, it is possible to prevent the occurrence of bright spots due to the leak path. Therefore, it is possible to manufacture a high-quality organic EL display device that suppresses the occurrence of abnormal pixels such as bright spots and dark spots.

  Note that the oxidation treatment performed after the planarization film 510 is formed over the substrate 502 among the steps described in the above manufacturing method may be performed on all the substrates 502 or some of the substrates 502. You may carry out for object. Specifically, after the planarization film 510 is formed on the substrate 502 and before the lower electrode 512 of the organic EL element 511 is formed, the planarization film 510 is obtained by visual inspection using a microscope, for example. A step of confirming whether or not the conductive foreign matter 520 exists on the upper surface (surface) of the substrate may be provided, and the oxidation treatment may be performed only on the substrate 502 in which the presence of the foreign matter 520 is confirmed in this step. In that case, oxidation treatment can be performed only on the substrate 502 that needs repair.

It is sectional drawing which shows the structural example of an organic electroluminescence display. It is sectional drawing which shows an example of the laminated structure of an organic EL element. It is a figure which shows the structural example of the drive circuit of an organic electroluminescent display apparatus. It is a figure which shows the structural example of a pixel circuit. It is process drawing (the 1) explaining the manufacturing method of the organic electroluminescence display which concerns on embodiment of this invention. It is process drawing (the 2) explaining the manufacturing method of the organic electroluminescence display which concerns on embodiment of this invention. It is process drawing (the 3) explaining the manufacturing method of the organic electroluminescence display which concerns on embodiment of this invention. It is process drawing (the 4) explaining the manufacturing method of the organic electroluminescence display which concerns on embodiment of this invention. It is sectional drawing which shows the structure of the TFT element and organic EL element which are applied to an active matrix type organic EL display device. It is a figure explaining a subject.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Organic EL display device, 2 ... Organic EL element, 4 ... Lower electrode, 6 ... Organic layer, 7 ... Upper electrode, 501 ... TFT element, 502 ... Substrate, 510 ... Planarizing film, 511 ... Organic EL element

Claims (3)

Forming a transistor element on the substrate;
Forming a planarization film on the substrate so as to cover the transistor element;
Performing an oxidation treatment using the upper surface of the planarizing film as a surface to be treated;
And a step of forming a light emitting element on the planarizing film. Including the step of confirming whether or not conductive foreign matter is present on the upper surface of the planarization film,
The method for manufacturing a display device according to claim 1, wherein the oxidation treatment is performed on the substrate in which the presence of the conductive foreign matter is confirmed. The method for manufacturing a display device according to claim 1, wherein the oxidation treatment is performed by ozone oxidation treatment or oxygen plasma treatment.

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