JPH11339958A - Method for manufacturing electroluminescent device - Google Patents

Abstract

(57) [Summary] (Problem corrected) [PROBLEMS] To provide a method for manufacturing an electroluminescent element which can form a fine electrode, increase the size of a substrate, and prevent a short circuit between electrodes. SOLUTION: An ITO film 12 and a metal layer 13 having a laminated structure are patterned into an anode electrode pattern, and an interlayer insulating film 15 is formed in a region other than a region to become a light emitting portion on the anode electrode. A resist mask 16 is patterned on the interlayer insulating film 15 so as to sandwich the region where the cathode electrode is to be formed.
The layer 18 and the cathode metal layer 19 are formed by vapor deposition.
As a result, the organic E
The L layer 18 and the cathode electrode 19A are formed. Next, the cathode metal layer 19 on the resist mask 16 and the cathode electrode 1 are removed by performing a light etch to remove the cathode metal layer 19 attached to the side wall of the resist mask 16.
9A can be electrically separated. For this reason, the occurrence of a short circuit between the electrodes can be prevented. Also,
Since the cathode electrode can be patterned without using a hard mask, the electrodes can be fine-pitched and the substrate can be enlarged.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an electroluminescent device, and more particularly, to a method for manufacturing an electroluminescent device capable of preventing a defect of a cathode electrode.

[0002]

2. Description of the Related Art In recent years, an electroluminescent device using an organic EL (electroluminescence) material for a light emitting layer has been receiving attention as its lifespan has been improved. Such an electroluminescent device has a structure in which a light emitting layer is sandwiched between a cathode electrode and an anode electrode. In a conventional manufacturing process of an electroluminescent device, a vapor deposition method using a hard mask has been performed when forming a cathode electrode. The reason is that the light emitting layer containing the organic EL material and the cathode electrode material are vulnerable to moisture and solvents, so that the resist is patterned in the photolithography process (including the developing process and the cleaning process) and the etchant used in the etching process. This causes adverse effects such as the edge portion of the cathode electrode being easily separated from the light emitting layer and the light emitting layer being deteriorated. With such a method of forming a cathode electrode using a hard mask, it has been difficult to miniaturize the electrode and increase the size of the display screen in accordance with higher definition of display. However, in the miniaturization of the electrode, a line and space of about 0.1 mm has been a limit. Further, in the case of a large-sized hard mask in which an opening of a fine pattern is formed, there is a problem that an error is easily generated in the formed electrode pattern because the mask itself is deformed by bending.

Therefore, as a patterning technique of a fine pitch cathode electrode, a method as shown in FIGS. 10 and 11 has been proposed. The method shown in FIG. 10 uses an ITO (indium tin oxi) as an anode electrode on a transparent substrate 1.
de) After patterning the film 2, a resist 3 having an inversely tapered side wall is formed as a partition between the cathode electrodes, and an organic EL layer 4 and a cathode metal layer 5 are sequentially deposited. In this manner, a light emitting portion in which the organic EL layer 4 is sandwiched between the ITO film 2 and the cathode metal layer 5 can be formed, and the cathode metal layers 5 of the adjacent light emitting portions are separated via the resist 3. I have. In the method shown in FIG. 11, a resist 3 having a rectangular cross section is formed, and the cathode metal layer 5 is formed by performing evaporation from an oblique direction indicated by an arrow in the figure.
It is to separate each other.

[0004]

However, FIG.
In the method using the inversely tapered resist 3 shown in FIG. 1, the thickness of the organic EL layer 4 is reduced below the side wall of the resist 3 as shown in FIG. There is a problem that it is likely to occur. Also, the oblique vapor deposition method shown in FIG. 11 has the same problem because the thickness of the organic EL layer 4 is reduced below one side wall of the resist 3. Such a problem is that when the size of the substrate is increased, there is a high possibility that the vapor deposition component of the cathode metal material goes under the side wall, and a short circuit between the cathode and the anode and a short circuit between the cathodes are likely to occur. Problem. The organic EL constituting the light emitting section is supposed to prevent the cathode metal layer 5 formed on the portion where the film thickness of the organic EL layer 4 becomes thin from causing a short circuit with the ITO film 2.
When the width of the cathode metal layer 5 on the layer 4 is formed to be short, invasion of a substance causing a dark spot such as oxygen or moisture from the organic EL layer 4 in a portion not covered by the cathode metal layer 5. And problems such as penetration of the solvent of the sealing material. In particular, in the method using the resist 3 having a reverse taper shape, the resist 3 is formed when a protective film or a sealing material is formed.
This causes a problem that the film formation on the lower portion of the side wall becomes defective and the protection function is lowered.

Therefore, the present invention provides an electroluminescent device that can form a fine-pitch electrode, increase the size of a substrate, and prevent a short circuit between a cathode electrode and an anode electrode or between cathode electrodes. An object is to provide a method for manufacturing a device.

[0006]

According to the first aspect of the present invention,
What is claimed is: 1. A method for manufacturing an electroluminescent device comprising a plurality of light-emitting portions each having an organic light-emitting layer sandwiched between a cathode electrode and an anode electrode, comprising: forming an anode electrode on a transparent substrate; A relatively thick photoresist is disposed avoiding the light-emitting portion, and an organic light-emitting layer and a cathode metal layer are sequentially deposited on the entire light-emitting display area. Then, the cathode metal layer attached to the side wall of the photoresist is removed. It is characterized by being insulated.

Therefore, according to the first aspect of the present invention, the organic light emitting layer and the cathode metal layer are deposited over the photoresist, so that the organic light emitting layer and the cathode metal layer are deposited in the light emitting portion region by the step of the thick photoresist. What is deposited on the photoresist becomes a very thin film even if it is stepped or not stepped. By insulating the cathode metal layer formed on the side wall of the photoresist, it becomes possible to electrically separate the cathode electrodes covering the light emitting portion. After the photoresist is formed, there is no photolithography step, so that adverse effects on the cathode can be avoided.

According to a second aspect of the present invention, there is provided the method of manufacturing an electroluminescent device according to the first aspect, wherein the cathode metal layer attached to the side wall of the photoresist is removed by light etching. .

Therefore, according to the second aspect of the present invention, in the operation of the first aspect, the thin cathode metal layer adhered to the side wall of the photoresist can be removed without removing the cathode electrode by light etching.

According to a third aspect of the present invention, there is provided the method of manufacturing an electroluminescent device according to the first aspect, wherein the thickness of the cathode metal layer adhered to the side wall of the photoresist is oxidized to have electrical insulation. It is characterized by being changed into an object.

According to the third aspect of the present invention, in the operation of the first aspect of the present invention, the oxide is formed by the thickness of the cathode metal layer attached to the side wall of the photoresist. The film thickness of which the surface itself is oxidized is small, and the adverse effect on the cathode electrode is substantially small.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of a method for manufacturing an electroluminescent device according to the present invention will be described below based on an embodiment shown in the drawings. (Embodiment 1) FIGS. 1 to 8 show Embodiment 1 in which the present invention is applied to an electroluminescent device for displaying dots in which an anode electrode and a cathode electrode are formed in an XY matrix. First, as shown in FIG. 1A, ITO or In ₂ O is placed on a transparent substrate 11 made of, for example, glass.
_{3 A} transparent electrode material film 12 of (ZnO) x (where x> 0) is formed. Next, on the transparent electrode material film 12,
A metal film 13 made of a simple substance or an alloy of aluminum, chromium, or the like having higher conductivity than the transparent electrode material film is formed. The transparent electrode material film 12 and the metal film 13
Can be formed continuously using a multi-chamber film forming apparatus. After washing the surface of the metal film 13 with water, a photoresist is applied on the metal film 13, exposed, developed, and baked to pattern the resist mask 14. As shown in the plan view of FIG. 1B, a plurality of the resist masks 14 are formed so as to be parallel in a predetermined direction (horizontal direction in the figure).

Next, the underlying metal film 13 and the transparent electrode material film 12 are wet-etched using the above-described resist mask 14, and then the resist mask 14 is peeled off and processed into a pattern as shown in FIG. Then, FIG.
As shown in (a) and (b), a negative-type photosensitive resin is formed on substantially the entire surface of the substrate so as to cover the patterned transparent electrode 12A and the metal electrode film 13A. Then, an interlayer insulating film 15 having an opening 15A in a portion to be a light emitting region is formed. Carbon black may be mixed in the interlayer insulating film 15. As shown in FIG. 3B, the planar shape of the interlayer insulating film 15 is such that an opening 15A is formed in a region inside a contour of each region where an anode electrode and a cathode electrode to be described later intersect. And the plane is formed in a substantially lattice shape.

Subsequently, as shown in FIGS. 4A and 4B, a negative photosensitive resin is applied, exposed, developed and baked to form an insulating resist mask 1 of about 20 μm.
6 is formed. The resist mask 16 passes through the anode electrode (the ITO film 1) so as to pass through the center of the interlayer insulating film 15 between the light emitting units adjacent to each other in the lateral direction in FIG.
2 and a metal film 13).
The width is set narrower than the interlayer insulating film 15. Note that the resist mask 16 on the interlayer insulating film 15 formed at both ends in the longitudinal direction of the anode electrode has a side wall of the interlayer insulating film 15.
Is set at a position retracted from the opening edge of the opening. Thereafter, the metal film 13 is subjected to wet etching (or dry etching) using the resist mask 16 to form a pattern as shown in FIG. In this etching, an etchant that has a sufficient etching selectivity between the material of the metal film 13 and the material of the ITO film 12 is used. Metal film 13 and ITO film 1 after being etched
The planar shape of the ITO film 1 is obtained by opening the metal film 13 and opening the ITO film 1.
2 is exposed. In this way, IT
An anode electrode composed of the O film 12 and the metal film 13 can be formed.

Thereafter, as shown in FIG. 6, an organic EL layer 18 having a thickness smaller than that of the resist mask 16 is formed by vapor deposition. At this time, the organic EL layer 18 is
6 and the portion formed at the bottom of the portion sandwiched between the resist masks 16
Due to the step 6, the film is formed in a state where the film is separated due to the step. Here, the organic EL layer 18 formed at the bottom of the portion sandwiched between the resist masks 16 is formed so as to completely cover the exposed interlayer insulating film 15. In this embodiment, although not shown, the organic EL layer 18 has a structure in which three layers of an organic hole transport layer, an organic light emitting layer, and an organic electron transport layer are sequentially laminated from a lower layer to an upper layer. ing. Examples of the organic hole transport layer include N, N'-di (α-naphthyl)-
N, N'-diphenyl-1,1'-biphenyl-4,4'-diamine (α
-NPD). Also, as the organic light emitting layer,
4,4'-bis (2,2'-diphenylvinylene) biphenyl (D
PVBi) and 4,4'-bis (2-carbazolevinylene) biphenyl (BCzVBi)
Is formed by co-evaporation with 4 wt%. Further, the organic electron transporting layer is made of tris (8-hydroxyquinoline) aluminum (referred to as Alq3).

Subsequently, as shown in FIG.
Li, Cr-Al, Mg-In, or the like is vapor-deposited on substantially the entire display region to form a cathode metal layer 19 having a thickness of about 3000 °. At this time, as shown in FIG. 3A, even if the cathode metal layer 19 adheres to the side wall of the resist mask 16 without causing a step in the resist mask 16, the cathode metal layer adhered to the side wall by the next light etching. 19 can be reliably removed. As conditions for this light etching, when the cathode metal is formed of Cr-Al, chlorine gas and boron tetrachloride gas are used as Cr etching gas, and chlorine gas and oxygen gas are used as Al etching gas. As a result of such light etching, as shown in FIG. 7B, the cathode metal layer 19 on the side wall is removed, and a cathode electrode 19A extending apart from each other in a direction perpendicular to the anode electrode can be formed. The cathode electrode 19A is separated from the cathode metal layer 19 formed on the resist mask 16 and not contributing to light emission. Thus, the electroluminescent device 10 of the present embodiment
Is completed.

Next, the operation of the electroluminescent device 10 of this embodiment will be described. In the present embodiment, the anode electrode is formed by the ITO film 12 and the metal film 13, so that the highly conductive metal film 13 can increase the propagation speed of the signal current, and the work function can be improved. Small ITO
The film 12 enhances hole injection into the organic EL layer 18. For this reason, each pixel can emit light uniformly and with high luminance regardless of the distance from the signal generation source. Also, organic EL
Since the cathode electrode 19A facing the ITO film 12 bonded to the layer 18 has a high work function, the electron injecting property to the organic EL layer 18 is high. The holes injected from the anode electrode and the electrons injected from the cathode electrode 19A correspond to the organic EL layer 1
Recombination within 8 causes emission. Also, the interlayer insulating film 15
The organic EL layer 7 formed thereon does not emit light because it is not sandwiched between these electrodes.

Particularly, in this embodiment, the cathode electrode 19
Since there is no resist stripping step in the formation of A, since the adhesion between the interlayer insulating film 15 and the cathode electrode 19A is high,
It is difficult for the peeling of the cathode electrode 19A to proceed to the organic EL layer 18 where light emission occurs. For this reason, it is not necessary to use a hard mask as in the related art, and it is possible to achieve miniaturization and enlargement of a display portion, and it is possible to prevent occurrence of a short circuit between a cathode electrode and an anode electrode or between cathode electrodes. . Then, the anode electrode (ITO
Since the organic EL layer 18 and the interlayer insulating film 15 wider than the resist mask 16 are interposed between the film 12 and the metal film 13) and the cathode electrode 19A, the resist mask 1
Even if the region surrounded by 6 is not completely covered by the organic EL layer 18, the interlayer insulating film 15 forms the anode electrode and the cathode electrode 19.
Since it is electrically insulated from A, it can be manufactured with a high yield.

(Embodiment 2) FIG. 8 is a sectional view showing Embodiment 2 of a method for manufacturing an electroluminescent device according to the present invention.
In the second embodiment, the steps up to the deposition of the cathode metal layer 19 in the first embodiment are the same.
After that, an oxidation process is performed instead of the light etching process of the first embodiment. In the present embodiment, as shown in FIG. 8, O ₂ using a cathode metal layer 19 on the side wall O ₂ plasma treatment, an ozone plasma treatment, or a resist stripping step
The cathode metal layer 19 formed on the resist mask 16 and the cathode electrode 19A can be electrically separated by changing the cathode metal layer 19 on the side wall to an oxide film 20 by performing an ashing process or the like. For example, when performing the O ₂ ashing process, the cathode metal layer 19 attached to the side wall of the resist mask 16 can be changed to the oxide film 20 in a processing time of 5 minutes or more. By performing such an oxidation treatment, the oxide film 20 is formed also on the surface of the cathode electrode 19A, but since it is an extremely thin film, it does not affect the cathode electrode 19A. In this embodiment, the cathode metal layer 19 attached to the side wall of the resist mask 16 is
Because it is continuous with the cathode metal layer 19 above
The cathode electrode 19A has a structure that is difficult to peel off,
By changing to the oxide film 20, an effect of suppressing the progress of peeling of the cathode electrode 19A can be added. Furthermore, in the present embodiment, the organic EL layer 18 is not exposed to the atmosphere when the cathode electrode 19A is separated, so that there is an advantage that inconvenience such as a dark spot does not easily occur. Other operations in the second embodiment are the same as those in the first embodiment described above, and a description thereof will be omitted.

(Embodiment 3) FIG. 9 is a sectional view showing Embodiment 3 of a method for manufacturing an electroluminescent device according to the present invention.
In the present embodiment, the metal layer 13 is not provided on the ITO film 12 in the first embodiment, and the resist mask 1
6 is not formed, and the other manufacturing steps are the same as those of the third embodiment.
Is the same as The figure shows a state in which the cathode electrode 19A has been electrically separated from the cathode metal layer 19 on the resist mask 16 after the completion of the light etching step. The other operations of the third embodiment are the same as those of the first embodiment.

Although the first to third embodiments have been described above, the present invention is not limited to these embodiments.
Various changes accompanying the gist of the configuration are possible. For example, in the first and second embodiments described above, the side wall of the interlayer insulating film 15 is formed in a tapered shape, but may be a side wall which rises vertically by anisotropic etching. In the above-described embodiment, the organic EL layer 18 has a three-layer structure, but may have a single-layer structure, a two-layer structure, or a structure having four or more layers.

[0022]

As is apparent from the above description, according to the present invention, fine pitch electrodes can be formed in the electroluminescent device, and the substrate can be made large. Also, there is an effect that occurrence of short circuit between cathode electrodes can be prevented.

[Brief description of the drawings]

FIG. 1A is a process sectional view showing Embodiment 1 of a method for manufacturing an electroluminescent element according to the present invention, and FIG. 1B is a plan view thereof.

FIG. 2 is a process sectional view showing the first embodiment.

FIG. 3A is a process sectional view illustrating the first embodiment, and FIG.
Is a plan view of the same.

FIG. 4A is a process sectional view illustrating the first embodiment, and FIG.
Is a plan view of the same.

FIG. 5 is a process sectional view showing the first embodiment.

FIG. 6 is a process sectional view showing the first embodiment.

FIGS. 7A and 7B are process cross-sectional views showing Embodiment 1. FIGS.

FIG. 8 is a sectional view showing Embodiment 2 of the method for manufacturing an electroluminescent element according to the present invention.

FIG. 9 is a sectional view showing Embodiment 3 of the method for manufacturing the electroluminescent element according to the present invention.

FIG. 10 is a cross-sectional view illustrating a method for manufacturing a conventional electroluminescent device.

FIG. 11 is a sectional view showing a method for manufacturing a conventional electroluminescent device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Electroluminescent element 11 Transparent substrate 12 ITO film 13 Metal layer 15 Interlayer insulating film 16 Resist mask 18 Organic EL layer 19 Cathode metal layer 19A Cathode electrode 20 Oxide film

Claims (3)

[Claims] 1. A method for manufacturing an electroluminescent device comprising a plurality of light emitting portions each having an organic light emitting layer sandwiched between a cathode electrode and an anode electrode, comprising: forming a pattern of an anode electrode on a transparent substrate; And disposing a relatively thick photoresist on the anode electrode, avoiding the light-emitting portion, and sequentially depositing an organic light-emitting layer and a cathode metal layer over the entire light-emitting display area, and then adhering to the side wall of the photoresist. A method for manufacturing an electroluminescent device, comprising insulating a formed cathode metal layer. 2. The method according to claim 1, wherein the cathode metal layer attached to the side wall of the photoresist is removed by light etching. 3. The method of manufacturing an electroluminescent device according to claim 1, wherein the thickness of the cathode metal layer attached to the side wall of the photoresist is changed into an oxide having electrical insulation by an oxidation treatment.