JPH1197171A - Organic el element and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain variations between a plurality of elements formed on one substrate as well as to reduce uneveness of light emission by forming a groove on a part to separate thin films at a process before forming the thin films to be subjected to separation patterning, forming the thin films thereon, and separating them to each other by means of the groove. SOLUTION: In an Al film deposition device, an Al material and a crucible 119 are deviated outside at a specified distance from the center of rotation of a substrate support 121. A glass substrate 101 on which a groove 102 or the like is formed is set to the support 121 so that its center nay be positioned apart from the rotation center of the substrate 101 at a specified distance and an opening of the groove may be positioned at a lower part. Through controlling the internal pressure of a vacuum container 122 and the deposition speed, the deposition is carried out while rotating the support 121. By the use of this device, in a substrate having a groove with its depth of about 1100 μm no film is formed to a bottom part of the groove when the substrate has the aspect ratio (groove depth/groove width) of 1.1 or more, and as a result, no electric conduction is made and accordingly an electric pattern separation is made possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic EL device and a method of manufacturing the same, and more particularly to an organic EL device capable of emitting light at a fine pitch and a method of manufacturing the same.

[0002]

2. Description of the Related Art The structure of a general organic EL device will be briefly described. FIG. 8A shows an organic EL device manufactured on a glass substrate 801. An anode 802 is formed on a glass substrate, and an organic layer 809 and a cathode 810 are formed on the anode 802 in this order. The organic layer 809 includes a hole injection layer 803, a hole transport layer 804, a light emitting layer 805, an electron transport layer 808, an electron injection layer 807, and the like. As the anode 802, a transparent conductive thin film or a metal thin film of gold or aluminum is used, and as the cathode 810, an alloy in which silver or indium is mixed with magnesium, or an alloy in which lithium is mixed with aluminum is used. As shown in FIG. 8A, when a positive voltage is applied to the anode 802 and a negative voltage is applied to the cathode 810 and a current flows through the element, light is emitted from the lower surface of the glass substrate.

Next, the concept of a simple matrix type organic EL display device will be described. This type of organic EL display device has an anode 8 having a stripe pattern as shown in FIG.
02, a striped cathode 810 patterned so as to be orthogonal to the anode 802, and an organic layer 809 sandwiched between both electrodes. The organic layer 809 is a hole injection layer,
It is composed of a hole transport layer, a light emitting layer, an electron transport layer, an electron injection layer, and the like. Anode 802 and cathode 810 are each 1
If a positive voltage is applied to the anode and a negative voltage is applied to the cathode, a current flows at the intersection of the selected anode and cathode, and light is emitted from the glass substrate side. An image can be displayed by driving each light emitting element in a matrix.

In order to display a high-definition image, it is necessary to reduce the width of the stripes of the anode and the cathode to several hundred μm or less and the gap between adjacent stripes to several tens μm or less. There are several methods for forming a striped electrode. The simplest method is a mask evaporation method using a metal mask. However, since fine processing of a metal mask is very difficult, it is extremely difficult to form a fine pattern of several tens to several hundreds μm by a mask evaporation method. Further, in the case of an organic EL device, when a cathode film is vapor-deposited by a mask, the metal mask may come into contact with the organic layer, and the organic layer or the cathode film may be damaged or damaged.

On the other hand, in the manufacture of a semiconductor device such as a semiconductor memory, if a general method combining photolithography technology and etching technology is used, microfabrication in units of microns can be performed. This method is a process of manufacturing wiring electrodes and transistors in the production of image display devices such as liquid crystal display devices and plasma display devices, and includes the steps of:
It is used when processing an O film, a silicon oxide film, a silicon film, or the like. This is an effective means for processing the ITO electrode of the organic EL element. However, when patterning the cathode of an organic EL element by photolithography and etching techniques, in the steps of applying and developing a photoresist, performing wet etching of a cathode film, and removing the photoresist, a resist solvent, a developing solution, and an etching method are used. There is a problem that the organic layer is affected by the solution and the resist stripping solution, and the display performance and the life of the device are deteriorated.

[0006] In order to solve the above-mentioned problems relating to the fine processing of the cathode accompanying the high definition of the organic EL element, a method described in Japanese Patent Application Laid-Open No. 5-275172 has been proposed. This method is based on the principle that a wall is formed at a portion separating a cathode, and a cathode material is deposited obliquely to the wall.

[0007] This will be described in the following daily cases.
Consider a scene in which the wall is exposed to sunlight from diagonally above, and the side that is exposed to sunlight is the front side. The sun shines on the ground in front of the wall and the front side of the wall, but the shadow behind the fence extends behind the fence. Here, if it is replaced with an element of a material that forms a film of sunlight and an object corresponding to a wall is formed on the substrate by some method, particles adhere to the front and the front side of the wall to form a thin film, The particles do not reach the back side of the wall or the shadowed portion, and no film is formed. In the invention of Japanese Patent Application Laid-Open No. 5-275172, such a wall is separated from the cathode by oblique deposition. FIGS. 8 (c) to 8 (e) are used to describe Japanese Patent Application Laid-Open No. 5-2751.
A configuration example of the organic EL device described in 72 will be described.

[0008] First, as shown in FIG.
On the substrate 1, an ITO film is processed to form an ITO electrode 802 including a plurality of parallel lines. Next, the ITO electrode 8
A resist wall 808 is formed so as to be orthogonal to 02. According to the embodiment described in JP-A-5-275172, a negative working resist applied on a glass substrate 801;
Photolithography is used to process the resist wall 80
8 are produced. It is a condition of the wall that the thickness is higher than the thickness of the organic EL medium (organic layer) 809 formed in a later step.

After forming the resist wall 808, FIG.
An organic EL medium (organic layer) 809 is formed by a vacuum evaporation method as shown in FIG. Next, as shown in FIG. 8E, a metal thin film to be the second electrode (cathode) 810 is attached from an oblique direction. According to Japanese Patent Application Laid-Open No. 5-275172, the direction of metal particles flying from a material source is controlled to form a metal thin film, for example, vacuum evaporation, electron beam evaporation, ion beam evaporation, laser ablation evaporation. And sputtering methods are suitable.

An embodiment of Japanese Patent Application Laid-Open No. 5-275172 describes a method of forming a cathode using a vacuum evaporation method.
If the vapor deposition direction 812 of the particles flying from the evaporation source is limited and the vapor deposition particles are made to enter the substrate from an oblique direction, the metal thin film does not adhere to the portion where the path of the particles is blocked by the wall. As a result, a separation region of the metal thin film is formed along the resist wall 808, and a striped cathode 810 orthogonal to the ITO electrode 802 is formed. JP-A-5-2751
According to the embodiment described in 72, the deposition direction of the metal particles 81
The angle 811 (= incident angle of vapor deposition particles) 811 between 2 and a normal line on the surface of the glass substrate 801 is about 10 to 60 degrees, preferably about 15 to 45 degrees.

[0011]

Problems to be Solved by the Invention
In the case where the cathode of the organic EL element is formed using the method described in 2, the incidence of vapor deposition particles flying from the evaporation source is
The angle between the incident direction of the vapor-deposited particles and the normal to the substrate must be kept constant so that the resist wall provided on the substrate forms a shadow. As a result, the following problems occur.

(1) It is impossible to manufacture a large screen display device. In other words, it is very difficult to make the incident angle of the deposition particles constant over the entire surface of the large glass substrate with a realistic film forming apparatus. The reason will be described below. FIG. 9A shows the structure of a general vapor deposition apparatus.

[0013] Japanese Patent Application Laid-Open No. 5-2751
In order to form a cathode by the method described in 72, the position of a crucible or a deposition boat (evaporation source) 919 containing a metal material and the position of the substrate 901 need to be shifted from each other in the horizontal direction and fixed. Further, the substrate must be placed in a region where the incident angle of the vapor deposition particles can be regarded as substantially constant, and the substrate must be large enough not to protrude from this region.

Japanese Patent Application Laid-Open No. 5-275172 discloses an angle between an incident direction of vapor deposition particles and a normal line standing on a substrate.
It is established when it is at about 10-60 degrees, preferably about 15-45 degrees. For example, consider a case in which a substrate having a width of 5 cm is used and vapor deposition is performed at an incident angle of 15 degrees between the incident direction of vapor-deposited particles and a normal to the substrate, and an error range of the incident angle of 10% is allowed. In other words, the incident angle at the portion near the evaporation source is 13.5 degrees, and the incident angle at the farthest portion is 16.5 degrees.
To be accurate, the substrate must be set approximately 89 cm above the evaporation source. If this is replaced with a 10-inch substrate, the required distance between the evaporation source and the substrate is about 260 cm in the vertical direction, which is not a practical size for a vapor deposition apparatus.

(2) The uniformity of the thin film to be deposited in the thickness plane is reduced. That is, uneven light emission occurs on the substrate. In the formation of a thin film by a vapor deposition method, the film deposition rate decreases as the distance from the evaporation source increases. Therefore, the film thickness is thick at a portion near the evaporation source and thin at a portion far from the evaporation source. Since the sheet resistance of the metal film used as the cathode depends on the film thickness,
When there is a distribution in the thickness of the metal film, the magnitude of the current flowing through the cathode changes depending on the substrate surface. As a result, in-plane variations occur in the light emission characteristics. When a general vapor deposition apparatus is used, usually, the substrate support is rotated horizontally, and the distance from the substrate to the evaporation source and the vapor deposition direction are randomized to suppress the non-uniformity of the film thickness. However, JP-A-5-275172
In order to carry out the described method, the position of the substrate and the evaporation source must be shifted in the horizontal direction and fixed, as shown in FIG. 9A, so that the in-plane variation of the thin film to be formed is not eliminated.

The in-plane variation of the film thickness is as follows.
When two or more types of materials are co-deposited, a problem of in-plane variation in the material mixing ratio also arises. For example, as shown in FIG. 9B, in the case of forming a co-evaporation layer of magnesium and silver, in the method described in Japanese Patent Application Laid-Open No. 5-275172, a portion close to the evaporation source of the magnesium material is magnesium-rich and silver is evaporated. The portion near the source becomes a silver-rich co-deposited film. Since the change in the mixing ratio of magnesium and silver greatly affects the efficiency of electron injection from the cathode to the organic layer, uneven light emission occurs in the substrate surface, and the brightness differs depending on the location.

(3) When two or more kinds of materials are co-evaporated, uneven light emission occurs due to a variation in the mixing ratio of the co-evaporated materials in one dot. This principle will be described with reference to FIG. When a vapor deposition apparatus as shown in FIG. 9B is used, magnesium particles enter the substrate from the lower left direction, and silver particles enter the substrate from the lower right direction. As shown in FIG. 9C, the magnesium particles are blocked by the wall and do not reach the right side of the wall. Conversely, the silver particles do not reach the left side of the wall due to the resist wall. The co-deposited layer of magnesium and silver is a region to which both magnesium particles and silver particles adhere, that is, a magnesium layer 9.
14 and the silver layer 915 are limited to the area where they overlap,
Only this part emits light brightly. However, in portions where silver is not deposited, the efficiency of electron injection is reduced, so that the emission intensity is reduced. Intensity of light emission occurs in the dot.

(4) Only stripe lines extending in a direction perpendicular to the particle incident direction can be patterned.
This is because the angle between the incident direction of the vapor-deposited particles and the normal line formed on the substrate must be limited, and the wall must be formed so that a shadow is formed on the incident of the vapor-deposited particles.

[0019]

According to the present invention, in order to solve the above-mentioned problems, an organic EL device and a method of manufacturing the same are configured as follows.

That is, (1) In a process before forming a thin film to be separated and patterned, a groove is formed in a portion where the thin film is separated, and a thin film is formed thereon, and the thin films are separated from each other by the groove.

(2) The groove is formed by a double wall.

(3) The double wall is formed by processing a photoresist using a photolithography technique.

(4) For the double wall, an inorganic insulating film or an organic insulating film is formed by photolithography and etching.

(5) The double wall is formed by irradiating the inorganic insulating film or the organic insulating film with laser light.

(6) The groove is directly processed on the substrate on which the element is manufactured.

(7) As a method of processing a groove into a substrate,
A casting method using a mold, a sand blast method, a diamond processing method, a melting method using a laser beam or a laser ablation method, or a method combining photolithography and wet etching are used.

(8) The groove is formed by forming a transparent thin film on the surface of the transparent substrate on which the organic EL element is to be formed, and processing the transparent thin film.

In the method described in JP-A-5-275172,
A wall is provided in a region where the cathode is to be separated, and the metal thin film is separated by using the effect that the vapor deposition particles are obliquely incident and are not vapor deposited on a portion where the entrance path of the particles is blocked by the wall. In this method, it is necessary to fix the positions of the substrate and the evaporation source in order to limit the flying direction of the deposition particles.

In a film forming method such as a vapor deposition method or a sputtering method, in which particles protruding from an evaporation source or a sputtering target travel straight, the coverage of a formed thin film is poor. For example, in many cases, a film is not formed on the bottom or the inner side wall of a thin and deep groove or a small diameter hole. The reason can be explained as follows. In the vapor deposition method and the sputtering method, particles that fly to the substrate enter straight ahead.
A groove or hole 1008 having a narrow opening as shown in FIG.
In the case of, the particles that can enter the interior are very limited. Further, as shown in FIG. 10 (b), since the vapor deposition particles and sputter particles excessively adhere to the opening, the opening is further narrowed by the adhered substance 1016, and the particles enter the groove or the hole. There is almost no.

In the manufacture of a semiconductor device, the coverage of a thin film formed on a step or a hole sometimes becomes a problem. Most of them occur in a step of embedding a metal film in a contact hole for connecting a diffusion layer or a gate electrode to an upper wiring electrode. In a 1 gigabit dynamic random access memory (1 Gbit DRAM), the diameter of a contact hole is about 0.3 μm, the depth is about 1.2 μm, and the aspect ratio is up to about 4. At present, the problem of embedding in contact holes has been solved by the progress of reflow technology after buried metal film formation, sputtering film formation technology using a collimator, and chemical vapor deposition (CVD) technology with excellent coverage. Trying to. Here, sputtering film formation using a collimator means that sputtered particles flying in an arbitrary direction from a sputtering target 1018 are collimated by a collimator 10 as shown in FIG.
In this method, particles are allowed to fall within a certain solid angle by passing through the substrate 17 and are made to be substantially perpendicularly incident on the substrate 1001 to improve bottom coverage to the contact hole.

The present invention utilizes the difficulty of forming a thin film in a narrow groove or hole. The method is characterized in that a narrow groove is formed at a portion where a pattern is separated, and a film is formed by using a vapor deposition method or a sputtering method with poor coverage of the groove.

In the method described in JP-A-5-275172,
The angle between the incident direction of the vapor-deposited particles and the normal set on the substrate must be kept constant, which causes some disadvantages.

In the method according to the present invention, it is not necessary to fix the positions of the evaporation source and the substrate, and ordinary film formation may be performed using a general vapor deposition apparatus or sputtering apparatus, and the above four problems are solved. You.

[0034]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an organic EL device according to the present invention and a method for manufacturing the same will be described.

(Example 1) In general, film formation by a vacuum evaporation method or a sputtering method has poor step coverage, and film formation conditions affecting the step coverage are (1) pressure in a vacuum chamber,
(2) the distance from the evaporation source to the substrate in the case of vapor deposition, the distance from the target to the substrate in the case of sputtering,
(3) substrate temperature. In order to improve the coatability of the thin film in the grooves, steps, and contact holes, (1) reduce the pressure in the vacuum chamber (make high vacuum) in order to extend the mean free path of flying particles, and (2) particles (3) heating the substrate to reduce the migration effect of the adhered particles on the substrate surface to reduce the solid angle at the time of incidence.

A depth of about 1100 μm as shown in FIG.
An aluminum thin film having a thickness of 400 nm was formed on the glass substrate 101 having grooves m, widths of 200, 350, 720, and 1100 μm processed by a vacuum evaporation method, and the insulating properties of the aluminum thin film were examined. The aspect ratio (= groove depth / groove width) of each groove is 5.5, 3.1, 1.5, 1.1.

FIG. 1B is a schematic view of an apparatus used for depositing an aluminum film. The vertical distance from the evaporation source to the substrate is about 22 cm, and the crucible 119 containing the aluminum material is located about 11 cm outward from the center of rotation of the substrate support 121. The size of the glass substrate 101 in which the groove is cut is a square of 50 mm × 50 mm, such that the center of the substrate 101 is located at a position about 33 mm away from the center of rotation of the substrate, and the opening of the groove is down, It was set on the substrate support 121.

The pressure in the vacuum chamber during the deposition of the aluminum film is 4
× 10 −4 to 1 × 10 ⁻³ Pa, deposition rate is about 1.0 nm
/ Sec. The deposition was performed while rotating the substrate support 121. Substrate heating was not performed. The thickness of the deposited aluminum is about 200 nm.

When the substrate 101 after the deposition of the aluminum thin film was observed with an optical microscope, adhesion of the aluminum film to the bottom of the groove having a groove width of 720 μm or more and an aspect ratio of 1.5 or less was observed. No film was formed on the bottom of the narrow groove having a ratio of 3 or more. In addition, when the electrical isolation by the groove was examined, no continuity was confirmed at all levels, indicating an insulation of several tens of megaohms or more. Therefore, it was found that when the vapor deposition apparatus as shown in FIG. 1B was used, if the aspect ratio was 1.1 or more, electrical pattern separation was possible.

Next, grooves having different depths were formed in the resist film formed on the glass, and the coatability of the aluminum thin film was examined. As shown in FIG. 1 (c), the thickness on the glass substrate is 15 μm.
The surface of the negative dry film photoresist 107 having a width of about 3 to 4 μm is irradiated with a KrF excimer laser.
m, and grooves having a depth of about 2, 4, 5, and 9 μm were formed. The aspect ratio (= groove depth / groove width) of each groove is about 0.5,
1.1, 1.3 and 2.3. The negative-type dry film photoresist 107 is obtained by laminating a glass substrate using NIT215 manufactured by Nippon Synthetic Chemical Industry Co., Ltd., and passing through an exposure and development process.

In the vacuum chamber 122 used in the first embodiment, FIG.
As shown in (b), a substrate 106 processed with a substrate photoresist and a crucible 119 containing aluminum were set. The positions of the glass substrate 106 and the crucible 119 are exactly the same as in the first embodiment. The degree of vacuum in the vacuum chamber during evaporation is about 5
The substrate was rotated at 0 × 10 ⁻⁴ Pa, but the substrate was not heated. The thickness of the deposited aluminum is about 200n
m.

When the substrate after aluminum deposition was observed with an optical microscope, no aluminum film was formed on the bottom of the groove except for a groove having a depth of 2 μm and an aspect ratio of 0.5. It has been found that the metal film can be separated by the groove.

Next, a dot matrix type organic EL device in which a cathode was separated by using a groove formed by a double wall was manufactured. The formation method will be described with reference to FIG.

The glass substrate 201 is a non-alkali glass 7059 manufactured by Corning, and the substrate size is 100 mm × 12.
It is a 0 mm rectangle. As shown in FIG. 2A, an ITO film 202 which is a transparent conductive film is formed on the glass substrate 201.
Is formed by a sputtering method. The film thickness of the ITO film 202 is about 120 nm, has a sheet resistance of 12 ohm / slot, and has characteristics of a light transmittance of 80% or more.

Next, the ITO film 202 is patterned by using a general photolithography technique and a wet etching technique. First, as shown in FIG. 2B, a positive resist 203 is spin-coated on the ITO film 202, and is exposed using a photomask in which a pattern for an anode is cut. When resist development is performed, a resist pattern is formed as shown in FIG. Subsequently, a portion of the ITO film 202 that is not protected by the resist 203 is etched using a mixed solution of hydrochloric acid and ferric chloride. After that, when the resist 203 is removed, an ITO electrode 202 serving as an anode shown in FIG. 2D is formed. At this time, the pattern width of the ITO electrode 202 is 200 μm, and the pattern pitch is 340 μm.

A double wall made of resist is formed on the patterned glass substrate 201 with an ITO electrode by using a photolithography technique. First, as shown in FIG. 2E, a negative dry film photoresist 204 having a thickness of 15 μm is laminated on the surface of the glass substrate with ITO. The dry film used here is NIT215 of Nippon Synthetic Chemical Industry Co., Ltd.

Dry film photoresist has a thickness of 15
Since it is micron, the depth of the groove is 15 μm. As described at the beginning of this embodiment, in order to separate the cathode metal film by the groove, an aspect ratio of 1 or more is required, so that the groove width must be 15 μm or less. However, the resolution of the dry film used is 15 μm, and it is difficult to form a pattern of 15 μm or less. Therefore, a double wall having a groove width of about 10 μm is formed by the following method.

After laminating the dry film on the substrate 201, exposure is performed using a photomask on which a desired pattern has been processed to expose the dry film. As shown in FIG. 2F, a photomask 205 used for exposure is
A pattern forming a single wall of 15 μm width is carved. First, as shown in FIG. 2 (f), a photomask 205 is aligned and exposed on a portion to be a left wall of the double wall.
For exposure, a parallel ray of ultraviolet light is irradiated using a mercury lamp. The irradiation amount is 340 mJ in total. By the first exposure, as shown in FIG. 2F, a left wall portion having a width of 15 μm is exposed. Subsequently, as shown in FIG.
The photomask is moved to the right by 25 μm in parallel, and exposure is performed again. The exposure condition is 340 mJ in the same integration as the first time.
In the second exposure, the right wall portion is exposed as shown in FIG. After that, when the resist is developed using an aqueous solution of sodium carbonate having a concentration of about 1%, as shown in FIG. 2B and FIG.
A groove 208 having a width of m, a width of 10 μm, and an aspect ratio of 1.5 is formed. If a liquid resist having excellent resolution and a photomask designed for a double wall are used, a double wall having a smaller size can be formed by a single exposure.

Next, an organic layer 209 formed by laminating a hole transport layer, a light emitting layer and an electron transport layer is formed. FIG. 2J is a cross-sectional view after the formation of the organic layer 209. FIG. 2 (j) is FIG.
It is the figure which expanded the part enclosed with the broken line of (i). As shown in FIG. 2 (j), the organic layer 209 is preferably formed not only on the light emitting section ITO electrode 202 but also on the ITO electrode 202 at the bottom of the groove so that the ITO film is not exposed. This is because, after the formation of the organic layer 209, a metal film serving as a cathode is formed.
This is because, if it adheres to the exposed portion of No. 02, there is a risk of short-circuiting the adjacent ITO electrode. Therefore, it is necessary to increase the step coverage method for forming the organic layer. As described above, the conditions affecting the step coverage are (1) the pressure in the vacuum chamber, (2) the distance from the evaporation source to the substrate in the case of vapor deposition,
In the case of sputtering, there are three: the distance from the target to the substrate, and (3) the substrate temperature. In order to improve the step coverage, the pressure in the vacuum chamber may be reduced (high vacuum), the substrate may be kept away from the evaporation source, and the substrate may be heated.

The optimum conditions differ depending on the groove structure of the vapor deposition apparatus or the sputtering apparatus.
Using a vapor deposition apparatus having a structure similar to that of (b), the pressure in the vacuum chamber was reduced to 4 × 10 ⁻⁵ Pa, the distance from the evaporation source to the substrate was about 47 cm, and the distance from the center of rotation of the substrate support was about The substrate was supported at a distance of 26 mm such that the long side of the substrate was perpendicular to the radial direction, and the organic layer was deposited while rotating the substrate. In the case of the organic EL element, the substrate is not heated in the third embodiment because the organic film constituting the organic layer may include a material having a low glass transition temperature in some cases. As the organic layer 209, a hole transport layer, a light emitting layer, and an electron transport layer are laminated in this order. As the first hole transport layer, N, N′-diphenyl-N, N′-bis (α
-Naphthyl) -1,1'-biphenyl-4,4'-diamine (hereinafter referred to as α-NPD) film was formed at a deposition rate of about 0.3 nm / sec to a thickness of about 55 nm. Next, a tris (8-quinolinol) aluminum complex (hereinafter referred to as Alq3) and quinacridone (hereinafter referred to as Qd) are used as light emitting layers.
Was deposited to a thickness of about 25 nm. At this time, the deposition rate of Alq3 is about 0.3 nm / sec, and the deposition rate of Qd is about 0.02 nm / sec. After that, the deposition of Qd was stopped, and a single layer film of Alq3 was formed as an electron transport layer at a deposition rate of about 0.3 nm / sec until the thickness became about 20 nm. The hole transport layer, the light-emitting layer, and the electron transport layer included in the organic layer 209 may be formed in a portion corresponding to a display area of the organic EL device. Therefore, when the organic layer 209 is formed, portions other than the display area are shielded by the metal mask.

Finally, a cathode layer is formed by using a vacuum evaporation method. The gist of the present invention is that the vapor deposition particles or the sputter particles wrap around the inner wall or the bottom of the groove 208 provided between the double walls 207 by utilizing the poor step coverage of the film formation by the vacuum vapor deposition method or the sputtering method. And performing separate patterning of the cathode. In Example 3, a co-evaporated film of magnesium and silver was employed as the cathode. FIG. 3 schematically shows an apparatus used for co-evaporation of magnesium and silver. Vaporization boat 319 containing magnesium
Then, the boat 320 charged with silver and the glass substrate 301 on which an organic layer has been formed are placed in a vacuum chamber 322 for forming a metal film. The substrate 301 is supported at a position approximately 26 mm away from the substrate rotation center such that the long side of the substrate is orthogonal to the radial direction. Vertical distance from evaporation source to substrate is about 22c
m, the boat 319 containing magnesium is located at a position of about 11 cm outward from the center of rotation of the substrate support, and the evaporation material 320 of the silver material is located symmetrically with respect to the center of rotation of the substrate support. is there. The cathode may be formed at a portion corresponding to a display area of the organic EL element and a connection portion with an external electrode. Therefore, a portion other than the display portion is shielded using a metal mask.

After setting the substrate and the deposition material, the pressure in the vacuum chamber 322 is reduced. In Example 2, the pressure was reduced to about 5 × 10 ⁻⁴ Pa, which was lower by about one digit than that in the organic layer deposition. The deposition rates of magnesium and silver are 0.4 nm / sec and 0.04 nm / sec, respectively, and a co-deposition layer is formed to a thickness of about 200 nm.

The co-evaporated film of magnesium and silver thus formed is separated by a groove 208 formed between the double walls, as shown in FIG. as a result,
It is possible to produce a cathode 210 with a pitch of about 340 μm and a width of about 200 μm, which is completely electrically isolated.

(Example 2) A groove was directly cut in a glass substrate.
A method of separating the cathode by the groove will be described below.
As shown in FIG. 4A, a glass substrate 401 has a width of 15 μm.
A groove 408 having a depth of 20 m, a depth of 20 m, and a pitch of 215 m is processed. A method of casting using a mold for processing glass,
Examples include a sand blast method, a diamond processing method, a melting or ablation method using a laser beam, a method using photolithography and a wet etching method, and the like.

Next, on the glass substrate 401 provided with the groove,
An ITO film having a thickness of about 150 nm is formed by an ion plating method or a CVD method having a high step coverage.
The ITO film is formed to a width of 200 μm and a pitch of 215 μm using a usual photolithography technique and a wet etching method.
Then, a stripe-shaped ITO electrode 402 orthogonal to the groove of the glass substrate as shown in FIG. 4B is formed.

Subsequently, in the same manner as in Example 1, an organic layer 408 including a hole transport layer, a light emitting layer, and an electron transport layer, and a co-evaporated layer of magnesium and silver as a cathode are formed by vacuum evaporation.

As shown in FIG. 4D, the co-evaporated layer of magnesium and silver was formed on the surface of the glass substrate with a width of 15 μm.
The cathode 310 is formed by being separated by a groove having a depth of 20 μm and an aspect ratio of 1.3.

In the method of separating the cathode by the grooves formed between the double walls shown in Example 1, the grooves and the double wall portions do not emit light. The light emitting area depends on the miniaturization of the double wall. When a dry film photoresist is used, the wall width is 15 μm.
The following processing is difficult. Furthermore, the step of the double wall influences the way of the deposition particles, and the thickness of the organic layer may change near the boundary between the wall and the light emitting portion.

However, by forming the groove directly on the substrate as in the second embodiment, the non-light emitting portion is only the groove portion, so that the light emitting area can be enlarged and the vapor deposition surface can be flattened. By doing so, an organic layer having a uniform thickness can be formed in each dot.
Further, since the photoresist does not remain after the completion of the device, it is not affected by a temporal change in the resist structure and components.
(Embodiment 3) There is a method in which a transparent thin film is formed on a glass substrate, and the transparent thin film is processed to form a groove having a desired aspect ratio. In the method of forming a groove by processing glass as shown in Embodiment 2, it is difficult to perform fine processing of several tens μm or less. However, it is easy to form a transparent thin film on a substrate and process it, and miniaturization is possible.

As shown in FIG. 5A, the glass substrate 501
A silicon nitride film 507 is formed thereon. The thickness of the silicon nitride film 507 is about 1 μm. The silicon nitride film 5 is formed by ordinary photolithography and wet etching.
A groove 508 is cut in 07. The width of the groove is about 1 μm, which is almost the same as the thickness of the silicon nitride film.

After forming the nitride film pattern, an ITO film is formed. For the film formation, a method such as a CVD method capable of forming a film with high coverage even at the step of the nitride film is used. Next, using a general photolithography method and a wet etching method, an ITO having a width corresponding to the area of the light emitting portion as shown in FIG.
The electrode 502 is processed.

Thereafter, an organic layer 508 including a hole transport layer, a light emitting layer, and an electron transport layer is formed by a vacuum evaporation method. At this time, the pressure in the reaction chamber was set to 5 × 1 so as to enhance the coatability of the organic film so that a sufficient film could be formed on the inner wall and the bottom of the groove 508.
0 kept ^-5. After the completion of the lamination of the organic layers, the substrate is transported to a reaction chamber for forming a metal film. The pressure in the reaction chamber for the metal film is set to be higher (lower vacuum) than when the organic layer is formed, and the mean free path of the metal particles flying to the substrate during the vapor deposition is shortened.

By doing so, the metal particles are prevented from entering the inside of the groove 508 and the cathode can be separated by the groove. As the cathode 410, a co-evaporated layer of magnesium and silver was used. Magnesium and silver deposition rate is 10: 1
It is. With this method, a very high-definition display device can be manufactured.

Example 4 In Example 1, a double wall was formed using a photoresist to separate the cathode. In the fourth embodiment, a method of forming an organic EL element by forming a double wall using an inorganic insulating film instead of a photoresist will be described.

First, as shown in FIG. 6A, an ITO electrode having a pattern width of 200 μm and a pitch of 220 μm is formed on a glass substrate. Next, as an inorganic insulating film, a thickness of about 2 μm
Is formed by a sputtering method. This nitride film is processed by a general photolithography method and a wet etching method, and as shown in FIG.
Two 14.5 μm wide bands with a 1 μm gap
Silicon nitride film patterns 607 arranged at a pitch of 20 μm
And With this silicon nitride film pattern 607,
A groove 60 having a width of 1 μm and a depth of 2 μm as shown in FIG.
8 is made.

After a silicon nitride film pattern was formed, an organic layer 6 having a thickness of about 110 nm, comprising a hole transport layer, a light emitting layer, and an electron transport layer, was formed by a vacuum evaporation method as in Example 3.
09 is formed. Thereafter, the substrate is transferred to a reaction chamber for forming a metal film, and a co-evaporated layer of magnesium and silver is formed as a cathode. The ratio of magnesium and silver is 10 to 1 at a deposition rate, and the co-deposited layer of magnesium and silver is 200 nm.
The co-evaporated layer of magnesium and silver is separated by a groove having a width of 1 μm, a depth of 2 μm and an aspect ratio of 2 sandwiched between silicon nitride films, and the cathode 610 is patterned.

In the method shown in the fourth embodiment, the thickness of the silicon nitride film is smaller than that of the resist of the first embodiment. An organic layer is formed. Further, since no resist remains on the device after completion, there is no deterioration of the device due to aging of the resist.

(Embodiment 5) As a method of forming a double wall or a groove using a photoresist, there is a method of performing patterning by laser beam irradiation. According to this method, a groove can be formed in a resist having no resolution for a fine pattern.

First, as shown in FIG. 7A, using a resist or other inorganic insulating film or organic insulating film,
A line and space pattern is formed. In the fifth embodiment, a dry film type photoresist having a thickness of 15 μm is used, and is formed with a width of 25 μm and a pitch of 330 μm. The pattern made of resist or transparent insulating film
What is necessary is just to form using a normal photolithography technique and an etching technique.

Next, as shown in FIG. 7B, in order to form a groove having a width of 5 μm and a depth of about 10 μm at the center of the resist pattern 707, a laser beam 723 is irradiated so as to vertically cross the center of the resist pattern. I do. A groove 708 as shown in FIG. 7C is formed in the center of the resist pattern 707 by the heat storage / evaporation of the laser beam 723 or the photoablation function.

By appropriately adjusting the beam diameter, wavelength, intensity, and irradiation time of the laser beam 723, a groove having a desired width and depth can be formed. In the fifth embodiment, FIG.
Groove 708 that does not reach the underlying ITO electrode as shown in FIG.
make. Such a groove having a concave cross section that does not reach the ITO film can prevent a short circuit between adjacent electrodes due to exposure of the ITO surface at the groove bottom.

Thereafter, the substrate 701 is transferred to a reaction chamber for forming an organic layer, and a hole injection layer, a light emitting layer, and an electron injection layer are vacuum-deposited in this order as in the first embodiment. Finally, a co-deposited layer of magnesium and silver serving as a cathode is formed, and FIG.
The organic EL device as shown in FIG.

[0073]

As described above, the present invention utilizes the poor coverage of the inside of a groove, which is possessed by the vapor deposition method and the sputtering method, in the step of forming a metal thin film serving as a cathode. It is not necessary to limit the use of the film forming apparatus such as fixing the incident angle of the substrate of the vapor deposition particles to the substrate as described in -275172. The present invention can be used without deteriorating the performance of the film forming apparatus, so that a thin film can be formed under the optimum conditions of the film forming apparatus with respect to the maximum substrate size allowed by the film forming apparatus.

Accordingly, the following effects can be obtained in forming the cathode of the organic EL device.

(1) Since a thin film having a uniform thickness can be formed over the entire surface of a large substrate within a range permitted by the film forming apparatus, the unevenness of light emission of the organic EL element is greatly reduced and Even if a plurality of elements are manufactured on a substrate, there is no variation between the elements.

(2) The problem of the change in the mixing ratio of the co-deposited material near the wall, which occurs when two or more types of materials are co-deposited, is solved, and the light emission unevenness in the dot does not occur.

(3) Since it is not necessary to fix the incident angle of the vapor-deposited particles or sputtered particles on the substrate, patterning of not only a parallel stripe pattern but also various shapes is possible.

(4) An organic layer or a metal layer is not damaged by a metal mask as in a metal mask evaporation method.
Further, it is possible to perform a fine pattern processing in a micron unit, which is very difficult with the metal mask method.
(5) Unlike a method combining photolithography technology and wet etching technology, there is no damage to an organic film or a metal film due to a resist solvent, a developing solution, a stripping solution, and an etching solution, so that the device life and characteristics are not deteriorated. .

[Brief description of the drawings]

FIGS. 1A to 1C are diagrams showing Example 1 of an organic EL device according to the present invention.

FIGS. 2A to 2K are views showing a method for manufacturing an organic EL device according to Example 1 of the present invention.

FIG. 3 is a diagram illustrating a method for manufacturing an organic EL device according to Example 1 of the present invention.

FIGS. 4A to 4D are views showing a method for manufacturing an organic EL device according to Example 2 of the present invention.

FIGS. 5A to 5E are views showing a method for manufacturing an organic EL device according to Example 3 of the present invention.

6 (a) to 6 (d) are views showing a method for manufacturing an organic EL device according to Example 4 of the present invention.

FIGS. 7A to 7D are views showing a method for manufacturing an organic EL device according to Example 5 of the present invention.

FIGS. 8A and 8B are diagrams showing a structure of a general organic EL element. (C)-(e) are diagrams showing a conventional method for manufacturing an organic EL device.

FIGS. 9A to 9C are diagrams showing a conventional method for manufacturing an organic EL device.

FIGS. 10A to 10C are diagrams illustrating a film forming method.

[Explanation of symbols]

101, 201, 301, 401, 501, 601, 7
01,801,901,1001 Glass substrate 102,103,104,105,108,109,1
10, 111 Groove 112 Incident direction of aluminum particles 119 Aluminum material and crucible 121, 321, 921 Substrate support 122, 322, 922 Vacuum tank 202, 402, 502, 602, 702, 802 I
TO electrode 203 Positive photoresist 204 Negative dry film photoresist 205 Photomask 206: Photosensitive portion 207, 707 Double wall 208, 408, 508, 608, 708 Groove 209, 309, 409, 509, 609, 709, 8
09 Organic layers 210, 310, 410, 510, 610, 710, 8
Reference Signs List 10 cathode 312 magnesium particle deposition direction 313, 913 silver particle deposition direction 319 magnesium material and deposition boat 320, 920 silver material and deposition boat 507 silicon nitride film 607 silicon nitride film pattern 723 laser beam 803 hole injection layer 804 Hole transport layer 805 light emitting layer 806 electron transport layer 807 electron injection layer 808, 907 resist wall 811, 911 incident angle 812 vapor deposition direction 912 vapor deposition direction of metal material, vapor deposition direction of magnesium material 914 magnesium layer 915 silver layer 919 metal material and Crucible, magnesium material and evaporation boat 1008 Groove or hole 1012 Particle arrival direction 1016 Attached matter 1017 Collimator 1018 Sputter target

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] November 16, 1998

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

Claims (9)

[Claims] 1. An organic EL device comprising a thin film separated from each other on a substrate, wherein the thin film formed on the substrate is formed on a substrate on which the thin film to be separated and patterned is formed by a step of forming the thin film. An organic EL device having a groove formed in a state of being separated from each other at a boundary portion of the thin film, wherein the thin film separated into a predetermined shape by the groove is formed on the substrate. 2. A method of manufacturing an organic EL device, comprising forming thin films separated from each other on a substrate, wherein a groove formed without connecting the thin film on the substrate is formed in the substrate. A method of manufacturing an organic EL device, comprising: forming the thin film on a substrate having a groove formed thereon and forming the thin film separated into a predetermined pattern on the substrate. 3. The organic EL device according to claim 1, wherein the groove is formed by a double wall provided on the substrate. 4. The organic EL device according to claim 3, wherein the double wall is formed by processing a photoresist using a photolithography technique. 5. The organic EL device according to claim 3, wherein the double wall is formed by processing an inorganic insulating film or an organic insulating film using a photolithography technique and an etching method.
An element or a method for manufacturing the element. 6. The organic EL device according to claim 3, wherein the double wall is formed by irradiating a laser beam to an inorganic insulating film or an organic insulating film. 7. The organic EL device according to claim 1, wherein the groove is formed directly on a substrate on which the device is manufactured. 8. A means for processing the groove into a substrate,
A method of casting using a mold, a sand blast method, a diamond processing method, a melting method using laser light or a laser ablation method, a method combining photolithography and wet etching, or a method for producing the same. . 9. The organic EL device or a method of manufacturing the same, wherein the groove is formed by forming a transparent thin film on the surface of the substrate on which the organic EL device is formed and processing the transparent thin film.