JP2011064938A - Organic el element and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase yield in a manufacturing process of a laminated organic EL element by reducing disconnection failure in the laminated organic EL element. <P>SOLUTION: The organic EL element has organic EL layers 101 and 102 held between at least two electrodes (an anode and a cathode), and a contact hole is formed in each of the organic EL layers 101 and 102 by removing a part of the organic EL layers. The contact hole has a multistage (e.g. two stages) wall surface inclined from one side toward the other side. The wall surface of the contact hole has a wall part 103 having a sharp inclination from the one side to the middle in a depth direction, and a wall part 104 having a gentle inclination from the middle in the depth direction to the other side. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an organic EL element and a method for manufacturing the same, and is particularly suitably applied to an organic EL element in which a plurality of organic EL layers including a light emitting layer are stacked on a substrate.

  An organic EL element in which one pixel is composed of one pixel is disclosed (see Patent Document 1). In this organic EL element, three organic EL elements that can be driven independently are stacked on an insulating substrate, and a transparent inorganic layer is formed between the elements in order to prevent a short circuit. In addition, at least one electrode of each element is electrically connected to an active element on the substrate through a contact hole. By adopting such a configuration, in the past, one pixel is composed of three subpixels, and each pixel assigned with RGB can be composed of one subpixel. Is possible.

  As described above, in an organic EL element having a configuration in which a plurality of organic EL elements are stacked, electrodes of each element are electrically connected through contact holes, and a voltage is applied between the elements to obtain a desired light emitting state. This is known.

  Also, laser processing is generally used for forming the contact hole. As a processing method of the contact hole, the contact hole is processed with the first laser beam, and the second laser beam having a weaker energy than the first laser beam is irradiated with a wider diameter, and the contact hole is processed around the contact hole. A technique for removing a residue and preventing disconnection failure is disclosed. Specifically, a technique disclosed in Patent Document 2 is disclosed.

  Furthermore, as another contact hole processing method, a technique of providing a taper by defocusing the irradiated laser beam is disclosed (see Patent Document 3).

JP 2007-12359 A JP 2003-347144 A JP 2002-313914 A

  However, in the organic EL element described in Patent Document 1, since the angle of the wall surface of the contact hole is steep, there is a high possibility that a disconnection failure occurs when the upper electrode is deposited. Moreover, in the technique described in Patent Document 2, when a thin electrode is deposited while the angle of the wall surface of the contact hole is steep, the possibility of disconnection is high. Furthermore, in the technique disclosed in Patent Document 3, when the contact hole is processed through at once, the edge of the organic EL layer may be steeply inclined.

  The present invention has been proposed in view of the above-described circumstances, and an object of the present invention is to reduce the occurrence of disconnection failure and improve the yield in the manufacturing process in a stacked organic EL element.

  The organic EL device of the present invention has the following features in order to achieve the above-described object. That is, the organic EL element of the present invention has an organic EL layer sandwiched between at least two electrodes, and a contact hole from which a part thereof is removed is formed in the organic EL layer. The contact hole includes a multi-stage wall surface that is inclined from one side to the other side, and the inclination angle is moderate in the middle of the wall surface.

  The organic EL device of the present invention has a structure in which a contact hole having a multistage wall inclined from one side to the other side is formed, and the inclination angle becomes gentle in the middle of the wall surface of the formed contact hole. Have. With such a structure, it is possible to obtain a stacked organic EL element having no disconnection failure and to improve the yield in the manufacturing process.

The schematic diagram which shows the cross-sectional shape of the contact hole in the organic EL element which concerns on embodiment of this invention. The schematic diagram which shows the cross-sectional shape of the contact hole in the middle of the manufacturing process of the organic EL element which concerns on embodiment of this invention. The schematic diagram which shows the cross-sectional shape at the time of depositing a thin upper electrode with respect to the contact hole in the organic EL element which concerns on embodiment of this invention. The schematic diagram which shows the cross-section of the organic EL element which concerns on embodiment of this invention. The schematic diagram which shows the planar structure of the organic EL element which concerns on embodiment of this invention. The schematic diagram which shows the cross-sectional structure of the contact hole vicinity in the organic EL element which concerns on embodiment of this invention. The schematic diagram which shows the manufacturing process of the organic EL element which concerns on embodiment of this invention. The schematic diagram which shows the cross-section of the organic EL element which concerns on other embodiment of this invention. The schematic diagram which shows the planar structure of the organic EL element which concerns on other embodiment of this invention.

<Schematic configuration of organic EL element>
Hereinafter, with reference to the drawings, an outline of embodiments of an organic EL device and a method for manufacturing the same according to the present invention will be described.

  1 to 5 show an organic EL element according to an embodiment of the present invention. 1 is a schematic diagram showing the cross-sectional shape of the contact hole, FIG. 2 is a schematic diagram showing the cross-sectional shape of the contact hole during the manufacturing process, and FIG. 3 shows the cross-sectional shape when a thin upper electrode is deposited on the contact hole. It is a schematic diagram. 4 is a schematic view showing a cross-sectional structure of the organic EL element, and FIG. 5 is a schematic view showing a planar structure of the organic EL element shown in FIG.

  As shown in FIG. 1, the organic EL element according to the embodiment of the present invention has one or more organic EL layers 101 and 102 sandwiched between at least two electrodes. When there are a plurality of organic EL layers, the number of the layers is preferably 2 or more and 3 or less. Here, the organic EL layers 101 and 102 are formed with contact holes from which a part thereof has been removed. The contact hole has a multi-stage wall surface inclined from one side to the other side, and the inclination angle is moderate in the middle of the wall surface. That is, as shown in FIG. 1, the contact hole has a wall portion 103 having a steep slope from one side to the middle in the depth direction, and a wall portion 104 having a gentle slope from the middle in the depth direction to the other side. And.

  In addition, as shown in FIG. 4 or 5, the method for manufacturing an organic EL element according to the embodiment of the present invention is a method for manufacturing an organic EL layer 205 sandwiched between at least two electrodes (anode 201, 202 / cathode 203). The contact hole 211 is formed by irradiating the part with laser light. This laser beam is composed of two laser beams having relatively different spot diameters. At this time, first, a step of forming a through hole with a laser beam having a relatively small spot diameter is performed. Subsequently, a laser beam having a relatively large spot diameter is irradiated to the organic EL layer on the same axis more weakly than a laser beam having a small spot diameter, and the contact hole peripheral portion on the side irradiated with the laser beam is irradiated. A step of forming a recess is performed.

  Alternatively, as shown in FIG. 2, first, a step of forming the recess 105 by irradiating the organic EL layer 101 on the laser irradiation apparatus side with a laser beam having a relatively large spot diameter is performed. Subsequently, as shown in FIG. 3, the coaxial organic EL layers 101 and 102 are irradiated with a laser beam having a relatively small spot diameter stronger than the laser beam having a large spot diameter, so that contact holes are formed. A process of penetrating is performed. In the example shown in FIG. 3, an Ag electrode 106 is formed so as to cover the contact hole.

  As another manufacturing method, first, a step of forming a through hole with a laser beam having a relatively small spot diameter is performed on the organic EL layer while focusing on the irradiation position. Subsequently, the organic EL layer on the same axis is irradiated with a laser beam having a relatively large spot diameter while shifting the focus from the irradiation position, and a recess is formed in the peripheral portion of the contact hole on the side irradiated with the laser beam. A forming step is performed.

  Alternatively, first, a step of forming a recess by irradiating the organic EL layer with laser light having a relatively large spot diameter while shifting the focus from the irradiation position. Subsequently, a process of penetrating the contact hole is performed by irradiating the coaxial organic EL layer with laser light having a relatively small spot diameter while focusing on the irradiation position.

<Cross-sectional structure of organic EL element>
Next, with reference to the drawings, embodiments of the organic EL device and the manufacturing method thereof according to the present invention will be described in detail.

  As shown in FIG. 1, the organic EL device according to the embodiment of the present invention has two organic EL layers 101 and 102, and a contact hole is formed through these organic EL layers 101 and 102. Has been. The contact hole has a two-step wall surface, and the inclination angle on the organic EL layer 101 side is gentler than the inclination angle of the wall surface on the organic EL layer 102 side.

  In the organic EL device according to the embodiment of the present invention, as shown in FIG. 4, organic EL layers 205 and 206 are formed on two separated anodes 201 and 202, respectively. In the example shown in FIG. 4, a blue organic EL layer 205 is formed on the anode 201, and a green organic EL layer 206 is formed on the anode 202. Further, a common cathode 203 is laminated on the organic EL layers 205 and 206, and a red organic EL layer 207 is laminated thereon with the opposite polarity to the other two colors, thereby forming the uppermost anode 204. ing. In FIG. 4, 208, 209, and 210 are circuits for driving the respective colors separately.

<Planar structure of organic EL element>
As shown in FIG. 5, the organic EL device according to the embodiment of the present invention opens a contact hole 211 with respect to a blue organic EL layer (not shown) and a red organic EL layer 207. Note that the uppermost anode 204 is electrically connected to a driving circuit disposed at the lower portion.

<Organic EL device having an inorganic film>
Next, an organic EL element according to another embodiment in which an inorganic film is added to the above-described configuration and a red anode is deposited thereon will be described. FIG. 8 is a schematic diagram showing a cross-sectional structure of an organic EL element according to another embodiment. FIG. 9 is a schematic diagram showing a planar structure of the organic EL element shown in FIG.

  The organic EL element shown in FIG. 8 is obtained by adding an inorganic film 607 to the structure of the organic EL element shown in FIGS. 4 and 5 and depositing a red anode 603 thereon. In this organic EL element, a red organic EL layer 610 is stacked with the same polarity as other colors, and finally a cathode 605 is deposited. Further, as shown in FIG. 9, a contact hole 614 is opened in the blue organic EL layer (not shown), the inorganic film 607, and the red organic EL layer 610, and the uppermost cathode 605 is disposed below. It is electrically connected to the circuit ground (earth 604).

  8 and 9, reference numerals 601, 602, and 603 are anodes, 604 is ground, 605 and 606 are cathodes, 607 is an inorganic film, 608, 609, and 610 are organic EL layers, and 611, 612, and 613 are drive circuits. , 614 respectively indicate contact holes.

  In the conventional technique, when a contact hole is opened by a normal laser processing on a layer in which an organic EL layer and an inorganic layer are laminated, the side wall becomes a steep angle, and when a thin anode is deposited on this, The possibility of disconnection was high.

  Therefore, in the present invention, the laser processing surface is made into two stages, so that the upper surface portion of the contact hole is smoothed, thereby preventing disconnection. Here, the processed surface has two stages, but it goes without saying that the same effect can be obtained even if three or more stages are used.

  FIG. 6 is a schematic view showing a cross-sectional structure in the vicinity of a contact hole in the organic EL element according to the embodiment of the present invention, and shows a cross section taken along the line AA in FIG.

  In the organic EL element according to the embodiment of the present invention, as shown in FIG. 6, drive circuits 209 and 210, extraction wirings 212 and 213, a planarization film 215, and a bank layer 216 are stacked on a substrate 217. Further, on these laminated structures, a first electrode (anode 201), a first organic EL layer (blue organic EL layer 205), a second electrode (cathode 203), a second organic EL layer (red organic EL layer). 207), the third electrode (anode 204) is laminated.

  Although not shown, the first electrode (anode 201) is connected to the extraction wiring through a contact hole opened in the bank layer 216, and the third electrode (anode 204) is opened in the stacked organic EL layer. The contact hole 214 is connected to the extraction wiring.

  Here, the organic EL layer is a layer including at least a light emitting layer, and may have any stacked structure. Examples of the organic EL layer include a single layer type (light emitting layer), a two layer type (light emitting layer / hole injection layer), a three layer type (electron transport layer / light emitting layer / hole transport layer), and a four layer type (electron layer). Injection layer / light emitting layer / hole transport layer / hole injection layer), 5-layer type (electron injection layer / electron transport layer / light emitting layer / hole transport layer / hole injection layer), and the like. In the present embodiment, the case of two-color lamination is described, but the present invention can also be applied to a one-color single-layer, three-color organic EL layer.

  In the present embodiment, a top emission type organic EL element is formed by using the second electrode (cathode 203) and the third electrode (anode 204) as transparent electrodes. The transparent electrode is more preferable as the light transmittance in the visible region is higher because the light extraction efficiency can be improved. For example, a conductive oxide such as ITO or IZO, or a thin translucent metal film such as Ag or Mo. Material can be applied.

  Here, the contact hole portion 214 of the third electrode (anode 204) will be described. As shown in FIG. 1, the sidewalls of the contact holes opened in the organic EL layers 101 and 102 have a gentler slope of the upper wall portion 104 than the lower wall portion 103. For this reason, the disconnection defect does not occur in the ridge portion on the upper surface of the contact hole.

  Although the top emission type organic EL element has been described in the present embodiment, it is needless to say that the present invention can be applied to a bottom emission type organic EL element in which the configuration of the organic EL layer and the electrode is changed.

<Manufacturing process of organic EL element>
FIG. 7 is a schematic diagram showing a manufacturing process of the organic EL element according to the embodiment of the present invention. Here, a description will be given of a portion where blue and red organic EL layers are laminated (corresponding to the right portion of FIG. 4).

  In the manufacturing process of the organic EL element according to the embodiment of the present invention, first, drive circuits 303 and 305 were formed on an insulating substrate 301. Subsequently, a photolithography process was performed, and a conductive film was deposited to form wirings 302 and 304. Subsequently, a planarization film 306 was formed with a photosensitive resin, and contact holes were formed by photolithography processing at the time of formation. Further, a bank layer 307 was formed from a photosensitive resin, and contact holes 308 and 309 were formed by photolithography processing at the time of formation (FIG. 7A).

  Subsequently, a metal thin film and a transparent conductive thin film were laminated by a photolithography process to form an anode 310 for blue. Further, a blue organic EL layer 311 was laminated by mask vapor deposition, and a semitransparent metal thin film or a transparent conductive thin film was deposited as an intermediate common cathode (cathode 312) by 20 nm as an intermediate common cathode (cathode 312). At this time, Ag or Mo can be applied as the translucent electrode. As the transparent conductive thin film, an oxide conductive material such as ITO, IZO, or IWZO can be applied (FIG. 7B).

  Subsequently, a red organic EL layer 313 was laminated by mask vapor deposition (FIG. 7C). Then, a contact hole 314 was formed in the red organic EL layer by laser processing (FIG. 7D). At this time, Ag or Mo can be applied as the translucent electrode. As the transparent conductive thin film, an oxide conductive material such as ITO, IZO, or IWZO can be applied.

At this time, first, a through hole having a small diameter was opened with a laser beam having a high output. The energy at this time is preferably ²⁰ to 200 mJ / cm ² . Next, a laser beam having a weaker output was irradiated to a wider area than the through-hole, and the wall surface above the contact hole (wall portion 104 in FIG. 1) was gently inclined. The energy at this time is preferably ² to 30 mJ / cm ² .

  Also, by performing two-stage laser processing, penetrating the organic EL layer with focused laser light, and further weakly irradiating laser light that is defocused on the same axis to process the periphery of the contact hole shallowly A similar shape can be obtained.

  The laser used at this time may be any laser that can oscillate infrared or X-rays, and examples thereof include a carbon dioxide laser, HF laser, YAG laser, YLF laser, semiconductor laser, and excimer laser.

  Further, a red transparent anode 315 was formed by laminating a semitransparent metal thin film or a transparent conductive thin film by mask sputtering, mask vapor deposition, or cutting after film formation (FIG. 7E). Thereafter, a sealing process (not shown) was performed to connect with an external circuit to complete an organic EL element.

  Next, specific examples to which the present invention is applied will be described.

  Example 1 will be described with reference to FIG.

  As the organic EL element of Example 1, ITO having a thickness of 100 nm was laminated, and the green organic EL layer 206 was formed to 80 nm on the separated anodes 201 and 202, and the blue organic EL layer 205 was formed to 75 nm. Further, a cathode 203 was formed by laminating an Ag film of 30 nm, a red organic EL layer 207 was laminated thereon by 100 nm, and an anode 204 was formed by laminating Ag by 30 nm on the top. In FIG. 4, reference numerals 208, 209, and 210 denote circuits that drive the pixels of each color separately.

  Further, in forming the cathode 203 and the contact hole, it was formed by a two-step process so that the inclination is gentle on the way to the upper side along the side wall. In the organic EL element of Example 1 in which such a contact hole was formed, the contact hole portion could be covered without disconnecting the common cathode (cathode 203).

When an organic EL panel having a size of 3 inches (640 × 480 dots) was produced using the organic EL element having such a configuration, there was no defective light emission.
[Comparative Example 1]

  In the comparative example, when the contact hole was formed, the side wall had a shape having no inclination change, and the other structure was the same as the organic EL element of Example 1. In the organic EL element of the comparative example, there was a part that was partially disconnected in the common cathode (cathode 203).

  When an organic EL panel having a size of 3 inches (640 × 480 dots) was fabricated using the organic EL element having such a configuration, 36 light emitting defects occurred.

  Example 2 will be described with reference to FIG.

  As an organic EL element of Example 2, drive circuits 303 and 305 were formed of low-temperature polysilicon on a 100 mm square glass substrate 301 with a thickness of 0.5 mm. The pixel pitch was about 92 μm. Subsequently, AlSi was deposited to a thickness of 100 nm by sputtering, and photolithography processing was performed to form extraction wirings 302 and 304. Subsequently, a planarizing film 306 having a thickness of 2 μm was formed using photosensitive polyimide. Furthermore, 100 nm of IZO was deposited by sputtering, and photolithography processing was performed to form an extraction electrode. Further, a bank layer 307 was formed from photosensitive polyimide, and a blue contact hole 308 and a red contact hole 309 were formed by photolithography processing at the time of formation.

  Subsequently, 100 nm of Ag and 70 nm of IZO were laminated by sputtering, and a blue anode 310 was formed by photolithography. Further, 85 nm of a blue organic EL layer 311 was laminated by mask vapor deposition, and 20 nm of Ag was deposited thereon as an intermediate common cathode 312 using a mask.

  Subsequently, a red organic EL layer 313 was stacked by 70 nm by mask vapor deposition. Then, a contact hole 314 was formed in the organic EL layer in which blue and red were laminated by laser processing.

At this time, first, a 10 μmφ through-hole was opened with a laser beam using a fundamental wave of Nd: YAG. The energy at this time was 60 mJ / cm ² . Next, KrF excimer laser light was irradiated at 15 μmφ to give a gentle slope to the upper surface of the contact hole. The energy at this time was 10 mJ / cm ² .

  Further, 15 nm of Ag and 50 nm of IZO were laminated by mask sputtering to form a red anode 315. Thereafter, a glass cap was sealed (not shown) and connected to an external circuit.

  When an organic EL panel having a size of 3 inches (640 × 480 dots) was produced using the organic EL element having such a configuration, there was no defective light emission.

  In Example 3, in the step of forming the contact hole 314 in the red organic EL layer by laser processing, first, KrF excimer laser light was irradiated at 15 μmΦ to form a gently inclined recess in the organic EL layer. The other configuration was the same organic EL element as in Example 2.

The energy of the laser beam was 12 mJ / cm ² . Next, a through hole was opened with a laser beam using a fundamental wave of Nd: YAG to form a contact hole having a two-step inclination. Thereafter, a glass cap was sealed (not shown) and connected to an external circuit.

  When an organic EL panel having a size of 3 inches (640 × 480 dots) was produced using the organic EL element having such a configuration, there was no defective light emission.

  In Example 3, in the step of forming the contact hole 314 in the red organic EL layer by laser processing, first, a laser beam having a fundamental wave of Nd: YAG is irradiated while shifting the focus by 20 μm, and the organic EL layer is inclined. A loose dent was formed. The other configuration was the same organic EL element as in Example 2.

The energy of the laser beam was 18 mJ / cm ² . Subsequently, a through hole was opened with a focused laser beam to form a contact hole having a two-step inclination. Thereafter, a glass cap was sealed (not shown) and connected to an external circuit.

  When an organic EL panel having a size of 3 inches (640 × 480 dots) was produced using the organic EL element having such a configuration, there was no defective light emission.

  Example 5 will be described with reference to FIG.

As the organic EL element of Example 5, ITO was laminated to a thickness of 100 nm, and on the separated anodes 601 and 602, a green organic EL layer 609 was formed at 80 nm and a blue organic EL layer 608 was formed at 75 nm. did. Subsequently, an Ag film 30 nm was laminated to form a cathode 606. Subsequently, 30 nm of SiO ₂ was deposited as an inorganic insulating layer (inorganic film 607), and ITO having a thickness of 30 nm was laminated thereon to form an anode 603. Subsequently, a red organic EL layer 610 was stacked to a thickness of 100 nm, and Ag was stacked to a thickness of 30 nm to form a cathode 605. In FIG. 8, reference numerals 611, 612, and 613 denote circuits for separately driving the pixels of the respective colors.

  Further, in forming the cathode 606 and the contact hole, the slope is gentle on the way to the upper side along the side wall by a two-step process. In the organic EL element of Example 5 in which such a contact hole was formed, the contact hole portion could be covered without the cathode 606 being disconnected.

  When an organic EL panel having a size of 3 inches (640 × 480 dots) was produced using the organic EL element having such a configuration, there was no defective light emission.

  101, 102: Organic EL layer, 103: Wall portion of sloping contact hole, 104: Wall portion of sloping contact hole, 105: Recess, 106: Ag electrode, 201, 202, 204, 310, 315, 601 602, 603: anode, 203, 312, 605, 606: cathode, 205, 311, 608: blue organic EL layer, 206, 609: green organic EL layer, 207, 313, 610: red organic EL layer 211, 214, 314, 614: contact holes

Claims (6)

An organic EL element having an organic EL layer sandwiched between at least two electrodes,
In the organic EL layer, a contact hole from which a part thereof is removed is formed,
The contact hole includes a multi-step wall surface inclined from one side to the other side, and an inclination angle is moderated in the middle of the wall surface. An organic EL element having two or more organic EL layers sandwiched between at least two electrodes,
In the organic EL layer, a contact hole from which a part thereof is removed is formed,
The contact hole includes a multi-step wall surface inclined from one side to the other side, and an inclination angle is moderated in the middle of the wall surface. An organic EL element having an organic EL layer sandwiched between at least two electrodes and forming a contact hole by irradiating a part of the organic EL layer with two laser beams having relatively different spot diameters A manufacturing method comprising:
Forming a through hole with a laser beam having a relatively small spot diameter with respect to the organic EL layer;
Further, a laser beam having a relatively large spot diameter is irradiated to the organic EL layer on the same axis more weakly than the laser beam having a small spot diameter, and a recess is formed in the peripheral portion of the contact hole on the side irradiated with the laser beam. Forming a step;
The manufacturing method of the organic EL element characterized by including. An organic EL element having an organic EL layer sandwiched between at least two electrodes and forming a contact hole by irradiating a part of the organic EL layer with two laser beams having relatively different spot diameters A manufacturing method comprising:
Irradiating the organic EL layer with a laser beam having a relatively large spot diameter to form a recess;
Further, the process of penetrating the contact hole by irradiating the coaxial organic EL layer with a laser beam having a relatively small spot diameter stronger than the laser beam having a large spot diameter;
The manufacturing method of the organic EL element characterized by including. An organic EL element having an organic EL layer sandwiched between at least two electrodes and forming a contact hole by irradiating a part of the organic EL layer with two laser beams having relatively different spot diameters A manufacturing method comprising:
Forming a through-hole with a laser beam having a relatively small spot diameter while focusing on the irradiation position with respect to the organic EL layer;
Further, the organic EL layer on the same axis is irradiated with laser light having a relatively large spot diameter while shifting the focus from the irradiation position, and a recess is formed in the peripheral portion of the contact hole where the laser light is irradiated. And a process of
The manufacturing method of the organic EL element characterized by including. An organic EL element having an organic EL layer sandwiched between at least two electrodes and forming a contact hole by irradiating a part of the organic EL layer with two laser beams having relatively different spot diameters A manufacturing method comprising:
Irradiating the organic EL layer with a laser beam having a relatively large spot diameter while shifting the focus from the irradiation position, and forming a recess;
Further, a process of penetrating the contact hole by irradiating a laser beam having a relatively small spot diameter while focusing on the irradiation position with respect to the organic EL layer on the same axis;
The manufacturing method of the organic EL element characterized by including.

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