KR100623714B1 - Fabrication Method of Organic Electroluminescence Display Device - Google Patents

Abstract

The present invention relates to a method of manufacturing an organic light emitting device, and more particularly, combining three frequency bands of a first frequency band, a second frequency band, and a third frequency band in a cleaning process before deposition of an organic layer of the organic light emitting device. The combination frequency can be used to generate various sizes of cavitation on the surface of the substrate to remove particles of different sizes at the same time, thereby improving the commutation ratio and lifetime of the device.

Organic EL, Particle, Combination Frequency, Cavitation

Description

Fabrication Method of Organic Electroluminescence Device {Fabrication Method of Organic Electroluminescence Display Device}

1 is a cross-sectional view of an organic light emitting display device according to the present invention.

2 is a graph showing cavitation strength and penetration according to frequency bands.

3 is a schematic diagram of an ultrasonic cleaning device according to the present invention;

4 is a flowchart showing an ultrasonic cleaning method according to the present invention.

5A-5F are schematic diagrams of the mechanism of the cleaning principle according to the present invention.

6 is a graph showing the rectification ratio according to an embodiment of the present invention.

7 is a graph showing a lifetime according to an embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

1 substrate 2 organic contaminants

3: particle 4: washing liquid

5: ultrasonic

30: oscillation part 32: vibration part (vibrator)

34: washing tank 36: nozzle

38: cleaning liquid 40: substrate

300 substrate 310 first electrode

330 organic layer 340 second electrode

The present invention relates to a method of manufacturing an organic light emitting display device, and more particularly, a combination frequency combining three frequency bandwidths of a first frequency band, a second frequency band, and a third frequency band before deposition of an organic layer of an organic light emitting device. Cavitation of various sizes is generated on the surface of the substrate to remove particles of different sizes at the same time, thereby providing a method of manufacturing an organic light emitting diode having improved rectification ratio and lifespan.

In general, among flat panel display devices, an organic electroluminescence display device is self-luminous, and has a wide viewing angle, fast response speed, thin thickness, low manufacturing cost, high contrast, and the like. It is attracting attention as a next-generation flat panel display device in the future.

In general, an organic light emitting display device includes an organic light emitting layer between an anode electrode and a cathode electrode so that holes supplied from the anode electrode and electrons received from the cathode electrode combine in the organic light emitting layer to form an exciton, which is a hole-electron pair, again. The excitons emit light by energy generated when the excitons return to the ground state.

The manufacturing process of the organic light emitting device generally includes a cleaning process of the organic film layer deposition substrate.

Contaminants in the organic electroluminescent device manufacturing process include organic contamination, ionic contamination, residues of metals or semiconductor films generated during the process, transport of substrates between facilities, and particulate contamination resulting from handling of workers and process equipment. There is this.

If the contaminant adheres to the substrate, the electrode, or the like, the contact between the electrodes becomes bad, resulting in an increase in resistance, poor wiring, and the like. Therefore, contaminants on the surface of the substrate must be removed to prevent defects in subsequent processes.

In general, cleaning methods are largely divided into chemical cleaning and physical cleaning. More specifically, there are physical cleaning such as brush scrubbing, water jet spray or ultrasonic cleaning, and chemical cleaning such as organic solvents, diluted hydrofluoric acid (HF) or ultra pure water rinse (DI Water Rinse). .

The chemical cleaning is effective for removing particulates, and the physical cleaning is effective for removing relatively large particles that are firmly attached.

       Current cleaning methods for liquid crystal display devices include physical cleaning methods such as spin cleaning, megasonic cleaning, or ultrasonic cleaning.

In the spin cleaning method, the chemical liquid is supplied from the nozzle to the surface of the object to be cleaned while being rotated by supporting the object to be washed with a spin chuck, and then the surface is rinsed by supplying DI water from the nozzle and ultrapure water by centrifugal force. To dry.

In the megasonic cleaning method, the cavitation phenomenon does not appear by cleaning by particle acceleration using a megasonic of high frequency of 1 MHz or more generated in the vibrator, and the acceleration of the particles is increased to remove the contaminants of the object to be cleaned.

On the other hand, the ultrasonic cleaning method mainly used before the organic film layer deposition of the organic light emitting device is a cleaning by cavitation is a cleaning that destroys or isolates foreign matters of the substance to be cleaned as bubbles are blown when ultrasonic energy is applied to water.

Here, the ultrasonic wave (Ultrasonic) is defined as the ultrasonic wave, which is usually in the range of 20kHz to 50MHz.

In addition, the cavitation phenomenon is that the ultrasonic waves are applied to the liquid and the contraction and expansion phenomenon is repeated to form a fine bubble, the fine bubbles are repeated vibration and rupture, the high impact force is generated when the bubbles collapse, which is converted into mechanical and thermal energy Say the phenomenon. At this time, the cavitation phenomenon is accompanied by chemical and thermal action due to the very small stirring and bursting of the bubble in accordance with the vibration of the bubble. Due to the complex repetition of these actions, the promotion and dispersal of chemical reactions in the washing water increases, so that even fine impurities, which are contaminants attached to the surface of the object to be cleaned, are cleaned.

In the conventional ultrasonic cleaning method of the liquid crystal display device, Korean Patent Laid-Open Publication No. 2004-0032129 discloses a process of repeatedly writing a first ultrasonic wave and a second ultrasonic wave, and simultaneously repeating the phase and wavelength of the first ultrasonic wave and the second ultrasonic wave. In addition, the contents of irradiating and cleaning the object to be cleaned while changing at regular intervals so that any one of the amplitude is different, the Korean Patent Laid-Open No. 2001-0084596 discloses that the first step and the second step of higher frequency than the first step The second step discloses the cleaning by each frequency having at least one or more frequencies.

However, compared to silicon wafers, glass substrates are insulators, so static electricity can be easily induced so that contaminants such as dust and metallic particles can easily adhere to the glass substrates and they are not easily separated.

Conventional ultrasonic cleaning uses different size of particles that can be removed depending on the frequency bandwidth, but it uses a frequency bandwidth that can not remove particles. It has a problem of lowering the rectification ratio and the lifetime of the device.

The technical problem to be achieved by the present invention is to solve the above problems of the prior art, by generating cavitation of various sizes on the surface of the substrate by ultrasonic cleaning before the organic film layer deposition of the organic light emitting device to generate particles of different sizes at the same time By eliminating this, the rectification ratio and lifetime of the device are improved.

The present invention to achieve the above object,

Providing a substrate,

Forming a first electrode on the substrate,

Particles of the substrate using the combination frequency that combines the three bands of the substrate formed with the first electrode 20kHz to 50kHz of the first frequency band, 50kHz to 100kHz of the second frequency band and 100kHz to 140kHz of the third frequency band Perform an ultrasonic cleaning to remove,

Forming an organic layer including at least an organic light emitting layer on the first electrode, and

It provides a method of manufacturing an organic light emitting display device comprising forming a second electrode on the organic film layer.

Hereinafter, with reference to the accompanying drawings will be described the present invention in more detail.

1 is a cross-sectional view of an organic light emitting display device according to the present invention.

Referring to FIG. 1, the method of manufacturing the organic light emitting display device of the present invention provides a substrate 300. The substrate 300 is a transparent insulating substrate such as glass, plastic and quartz.

Subsequently, the first electrode 310 is patterned and formed on the substrate 300.

The first electrode 310 is deposited by sputtering or ion plating. More preferably, the first electrode 310 is formed by selectively patterning through wet etching using a photoresist (PR; Photo Resist) patterned in a photolithography process after deposition by a sputtering method as a mask.

Subsequently, the entire surface of the substrate is cleaned, including the upper portion of the first electrode 310, before the organic layer is deposited.

In the present invention, the cleaning process before the deposition of the organic layer of the organic light emitting device is performed by ultrasonic cleaning using a frequency having a frequency band of 20kHz to 140kHz oscillation.

Since the low frequency of 20 kHz or less has a large cavitation strength, the substrate may be damaged due to a large impact force. In addition, the high frequency of 140kHz or more is not good cavitation rate, it requires a lot of energy to maintain the cavitation. In this case, the molecular acceleration is high, but the wave amplitude is small, so that the wave energy is converted into thermal energy, so that the temperature of the medium easily rises, and the cleaning ability is significantly reduced.

Ultrasonic cleaning is generally associated with negative pressure effects in addition to cavitation. At this time, the higher the frequency, the higher the power (sound pressure) is required, because the higher the frequency, the less time margin for the bubble to be sufficiently large. For this reason, to use cavitation effectively in practical use, it is better to use several tens of kHz.

In the present invention, the frequency band is classified into three frequency bands according to particle size removal as shown in Table 1 below.

Table 1 shows oscillation frequency bands according to particle size removal.

Oscillation frequency band according to particle size removal Item First frequency band Second frequency band Third frequency band Bandwidth 20 kHz to 50 kHz 50 kHz to 100 kHz 100 kHz to 140 kHz Removable particles More than 5㎛ More than 3㎛ 1 ㎛ or more Use frequency 40 kHz 58 kHz 132 kHz

Referring to Table 1, the present invention removes 20 kHz to 50 kHz to remove 5 μm or more from a first frequency band, 50 kHz to 100 kHz to remove 3 μm or more from a second frequency band and 100 kHz to 140 kHz to remove 1 μm or more. Classify into three frequency bands.

The particle size controlled by the organic light emitting device is 5 μm or less, and the particles of 5 μm or less are divided into 1 μm, 3 μm, and 5 μm particle sizes for the convenience of particle counters.

Since the total thickness of the organic film deposited by the organic light emitting device is 1 μm or less, removing the 1 μm, 3 μm, and 5 μm particles in the organic film emitting device before cleaning the organic film is performed. This is very important in terms of reliability.

In general, an organic light emitting display device is divided into a passive matrix method and an active matrix method according to a method of driving N × M pixels arranged in a matrix form. The anode electrode and the cathode electrode are composed of simple matrix elements, whereas the active matrix method has a thin film transistor mounted on each pixel. As a result, 5 μm or less in the active matrix organic light emitting display device having a thin film transistor Particle Control is Manual More device reliability characteristics than matrix organic electroluminescent devices It is important.

In addition, the present invention uses a 40 kHz frequency in the first frequency band, a 58 kHz frequency in the second frequency band and 132 kHz frequency in the third frequency band, and combines the combination frequency of the three frequencies 40 kHz, 58 kHz and 132 kHz. Repeat this procedure twice in succession and successively to clean particles of various sizes attached to the surface of the substrate. In the ultrasonic cleaning, all three frequencies use a cavitation phenomenon.

Particle removal possible size according to the oscillation frequency band can be confirmed through FIG. 2 is a graph showing cavitation and penetration according to oscillation frequency.

Referring to FIG. 2, when the oscillation frequency is small, the cavitation is strong but the penetration force to the impurities attached to the substrate is small, so that particles of large size are removed, and when the oscillation frequency is large, the cavitation occurs but the impurities are attached to the substrate. Its high penetrating power can remove fine particles.

Next, an ultrasonic cleaning apparatus using the ultrasonic cleaning method described above will be described.

3 is a schematic view of a cleaning unit of the ultrasonic cleaning apparatus. The ultrasonic cleaning apparatus includes an oscillator 30 for generating an ultrasonic signal and a transducer 32 for transmitting ultrasonic waves to a substrate. In the present invention, the oscillator 30 converts general commercial power into high frequency electric signals of 40 kHz, 58 kHz, and 132 kHz and supplies them to the vibrator 32, and transmits high frequency electric signals from the oscillator 30 to the vibrator of the diaphragm. When applied to (32), this vibrator is converted into a mechanical signal, and the converted mechanical signal vibrates through a medium in the water to generate ultrasonic waves having a cavitation phenomenon due to a change in sound pressure. In the present invention, a washing process is performed in three washing tanks different in frequency.

Embodiments of the present invention will now be described with reference to FIGS. 4 and 5.

Referring to FIG. 4, the ultrasonic cleaning method according to the present invention uses a first process of cleaning a substrate using a first frequency band, a second process of cleaning a substrate using a second frequency band, and a third frequency band. And repeating the third step of cleaning the substrate and the first step, the second step, and the third step once more.

In the said ultrasonic cleaning method, preferable embodiment is as follows.

(1) Performing the first step, the second step and the third step two times sequentially and successively.

(2) The range of the oscillation frequency of the ultrasonic wave is 20kHz to 140kHz.

(3) The frequency used for the ultrasonic cleaning is 40kHz, 58kHz, 132kHz.

(4) The said 1st process, a 2nd process, and a 3rd process differ in amplitude and frequency of a carrier wave.

5A to 5F, a physical cleaning method using ultrasonic waves according to the present invention will be described in detail.

Particles 3 are attached to the substrate 1 via organic contaminants 2. First, ultrapure water (DI Water), which is the cleaning liquid 4, is flowed into the substrate 1 through the nozzle 36 (FIG. 5A).

The high frequency electric signal is applied from the oscillator 30 to the vibrator 32 of the diaphragm to generate an ultrasonic wave 5 having a frequency of 40 kHz. The ultrasonic wave 5 is irradiated onto the surface of the substrate 1 through the cleaning liquid 4 and acted on the particles 3 and organic contaminants 2 adhering to the surface (Fig. 5B).

The cleaning liquid 4 is irradiated with ultrasonic waves 5 to generate OH radicals in the cleaning liquid 4 (FIG. 5C).

The generated OH radicals oxidize and decompose the organic contaminants 2 attached to the surface of the substrate 1 (FIG. 5D).

The particles 3 are separated from the substrate 1 by the vibration and the shock wave of the cavitation caused by the ultrasonic irradiation (FIG. 5E).

The particle 3 is lifted off from the object to be cleaned 1 (FIG. 5F).

The process is then repeated twice with frequency bands 58 kHz and 132 kHz.

The cleaning is performed for 5 minutes for each frequency sequentially and continuously at a frequency of 40 kHz, 58 kHz, and 132 kHz, and the cleaning cycle is repeated twice.

The cleaning cycle has the best particle removal power when performed twice, and since the cleaning cycle does not show a significant difference in the particle removal force when performed more than three times, it is performed twice in consideration of the process time.

Finally, when the surface of the cleaning body is dried, the cleaning is finished.

At this time, the ultrasonic wave becomes a small wave and repeatedly shows compression force and expansion force. Bubbles are produced around impurities that are contaminants of the substrate in ultrapure water during the negative pressure cycle and burst during the next compression cycle. Such bubbles are repeatedly produced and burst about 25,000 to 300,000 times per second in the washing water. As the bubble contracts, the pressure inside the bubble rises. These small bubble explosions are very small, but in terms of their total energy, they can represent a pressure of about 10,000 pounds per square inch and about 20,000 degrees Fahrenheit.

Cavitation in general depends on several factors such as frequency, wave strength, treatment temperature, and vapor pressure of the liquid.

It can be seen that when the cleaning liquid is water, the higher the temperature, the weaker the cavitation strength and the higher the number of cavitation bubbles. Preferably the ultrasonic cleaning temperature is carried out at 50 ℃ to 60 ℃. In addition, dissolved gases dissolved in the solution weaken the cavitation strength. For example, about 8 ppm of oxygen is dissolved in ordinary water, and if it is removed to 0.5 ppm, the intensity of ultrasonic waves is about 5 times stronger. In addition, in a liquid having a high surface tension, cavitation strength becomes strong but hardly generated, and a liquid having a strong viscosity is more difficult to cause cavitation. Finally, the cavitation strength is very weak near the boiling point of the solution. Here, the sound wave is simply a mechanical element for causing a cavitation phenomenon.

Subsequently, an organic layer 330 including at least an organic emission layer is formed on the entire surface of the substrate including the exposed first electrode 310. The organic layer 330 may include a hole injection layer, a hole transport layer, an electron transport layer, an electron injection layer in addition to the organic light emitting layer.

      The organic light emitting layer may be a low molecular material or a high molecular material. The low molecular weight material is formed of one selected from the group consisting of aluminy chironium complex (Alq3), anthracene (Anthracene), cyclo pentadiene (Cyclo pentadiene), BeBq2, Almq, ZnPBO, Balq, DPVBi, BSA-2 and 2PSP. .

The polymer material is poly (p-phenylenevinylene) (PPV; poly (p-phenylenevinylene)) and its derivatives, polythiophene (PT) and its derivatives and polyphenylene (PPP; Polyphenylene) and its derivatives It is preferable to form one selected from the group consisting of.

The organic layer 330 is deposited by vacuum deposition, spin coating, inkjet printing, a doctor blade, a laser thermal transfer method (LITI), or the like.

Meanwhile, the organic layer 330 may be patterned for each unit pixel. The patterning of the organic layer 330 may be implemented using laser thermal transfer, vacuum deposition using a shadow mask, or the like.

Subsequently, a second electrode 340 is formed over the entire organic layer 330. The second electrode 340 is formed by performing a vacuum deposition method.

The invention is not limited to the specific representative apparatus and examples described and illustrated herein. Accordingly, the present invention may be variously modified without departing from the spirit and scope of the invention as defined in the appended claims.

Hereinafter, examples are provided to help understanding of the present invention. However, the following examples are only to aid the understanding of the present invention, the present invention is not limited by the following examples.

Example 1

200 x 190 0.7t Bare Glass was provided. Reference particles of the organic substrate were measured with a Hitachi particle measuring instrument (manufactured by Hitachi, Japan). After measuring the substrate, the ultrasonic cleaning device equipped with three baths (manufactured by CREST Co., Ltd.) was used for 5 minutes at 40 kHz frequency, 5 minutes at 58 kHz frequency, and 5 minutes at 132 kHz frequency at 24 ° C. The washing was carried out by repeating two times sequentially and successively. At this time, a different bath (Bath) was used during the cleaning process for each ultrasonic wave.

Subsequently, the substrate was dried for 5 minutes through isopropyl alcohol vapor after 5 minutes of isopropyl alcohol (IPA; Isopropylalcohol) and 5 minutes of rinse (Rinse) to complete cleaning.

Example 2

Cleaning was carried out in the same manner as in Example 1 except that the reaction was performed at 40 kHz for 5 minutes.

Example 3

Washing was carried out in the same manner as in Example 1 except that the reaction was performed at 58 kHz for 5 minutes.

Example 4

Cleaning was performed in the same manner as in Example 1 except that the 132 kHz frequency was performed for 5 minutes.

Example 5

Cleaning was carried out in the same manner as in Example 1 except that the reaction was performed for 20 to 30 minutes at a variable frequency of 20 kHz to 100 kHz.

Comparative Example 1

The frequency was washed in the same manner as in Example 1 except that the frequency was performed at 26 kHz for 5 minutes as follows.

<Evaluation of Particle Removal>

Before ultrasonic cleaning After measuring the number of reference particles of a 200 x 190 0.7t glass substrate by Hitachi particle measuring machine (manufactured by Hitachi, Japan), after ultrasonic cleaning according to Examples 1 and Comparative Examples 1 to 4 above Again, the number of particles was measured and the number removed was converted into percentages.

<Commutation cost evaluation>

The rectification ratios of Example 1 and Example 5 were compared and evaluated.

The rectification ratio is a leakage current in a reverse voltage band and may be expressed as a ratio of forward bias current to reverse bias current. Here, the smaller the value, the better the rectification ratio is.

Rectification Ratio = Forward Bias Current / Reverse Bias Current

<Life Evaluation>

The lifespan of Example 1 and Example 5 was compared and evaluated.

Table 2 below shows the particle size removal rate according to the frequency according to the embodiment of the present invention.

Removal Rate by Particle Size by Frequency Item Removal Rate by Particle Size 1 μm 3 μm 5 μm Sum Example 1 93.4% 94.2% 97.7% 94.1% Example 2 3.4% 7.6% 40.7% 11.8% Example 3 -11.0% 2.3% 55.7% 11.1% Example 4 -1.7% 14.2% 15.7% 11.3% Example 5 88.5% 92.3% 87.6% 89.5% Comparative Example 1 17.2% 19.5% 35.7% 22.5%

Referring to Table 2, Example 1 according to the present invention was confirmed that the removal rate by particle size is significantly superior to each particle size of more than 90%. In Examples 2, 3 and 4, the overall particle removal rate did not show a significant difference of about 11%, but in the removal rate according to the particle size, Examples 2 and 3 showed removal rates of 40% to 55% in 5 μm particles. Low removal rates of less than 10% were shown for the micrometer to 3 micrometer particles, while Example 4 showed low removal rates of less than 15% for each of the 1 micrometer, 3 micrometer and 5 micrometer particles.

In addition, in Example 5, the particle size removal rate was about 90% for each particle size, but the results were lower than in Example 1 of the present invention. Comparative Example 1 exhibited an overall low particle removal rate.

Referring to FIG. 6, it was confirmed that Example 1, which was performed twice at 40 kHz, 58 kHz, and 132 kHz compared to Example 5, has a better rectification ratio.

Table 3 below is a table showing a comparison of the rectification ratio of Example 1 and Example 5 according to an embodiment of the present invention.

Rectification Ratio Comparison Item Rectification cost x y Example 1 9 x 10 ⁵ 0.6507 0.3434 Example 6 6 x 10 ⁵ 0.6447 0.3471

Referring to Table 3 and FIG. 6, it was confirmed that Example 1, which was performed twice at 40 kHz, 58 kHz, and 132 kHz compared to Example 5, has a better rectification ratio.

Referring to FIG. 7, it was confirmed that Example 1 has better luminance and lifespan than Example 5 above.

As described above, according to the present invention, the surface of the substrate using a combination frequency combining three frequency bands of the first frequency band, the second frequency band, and the third frequency band in the cleaning process before deposition of the organic layer of the organic light emitting diode. By generating various sizes of cavitation at the same time, it is possible to improve the rectification ratio and the lifetime of the device by simultaneously removing particles of different sizes less than 5 μm.

Claims (9)

Providing a substrate, Forming a first electrode on the substrate, Particles of the substrate using the combination frequency that combines the three bands of the substrate having the first electrode 20 kHz to 50 kHz of the first frequency band, 50 kHz to 100 kHz of the second frequency band and 100 kHz to 140 kHz of the third frequency band Perform an ultrasonic cleaning to remove, Forming an organic layer including at least an organic light emitting layer on the first electrode, and The method of manufacturing an organic light emitting display device, comprising forming a second electrode on the organic layer. The method of claim 1, The ultrasonic cleaning generates a cavitation to remove particles, characterized in that the organic light emitting device manufacturing method. The method of claim 1, The first frequency band is 40kHz, the second frequency band 58kHz and the third frequency band 132kHz frequency, characterized in that the organic light emitting device manufacturing method. The method of claim 1, The ultrasonic cleaning may include a first process of cleaning the substrate using the first frequency band, a second process of cleaning the substrate using the second frequency band, and a third process of cleaning the substrate using the third frequency band. A method of manufacturing an organic light emitting display device, characterized in that the process is performed twice in succession. The method of claim 1, The method of claim 1, wherein the first frequency band is 5㎛ or more, the second frequency band is 3㎛ or more, and the third frequency band is 1μm or more to remove particles. The method of claim 5, wherein The particle removal sequence is 5㎛ or more, 3㎛ or more, 1㎛ or more method for manufacturing an organic light emitting device. The method of claim 1, The ultrasonic cleaning liquid used in the ultrasonic cleaning is an organic electroluminescent device manufacturing method, characterized in that the ultrapure water. The method of claim 1, The first electrode is an anode, the second electrode is a method of manufacturing an organic light emitting device. The method of claim 1, The method of manufacturing an organic light emitting display device, wherein the first electrode is a cathode and the second electrode is an anode.

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