JP2011071038A - Mask cleaning method for organic el, mask cleaning device for organic el, manufacturing device of organic el display, and organic el display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain, when removing an organic material adhered to a mask for an organic EL by using laser beam, a high degree of cleaning without damaging the mask for the organic EL beyond restoration. <P>SOLUTION: In a mask cleaning method for the organic EL, an organic material 51 is removed by scanning the laser beam on a surface of the mask 2 for the organic EL to which the organic material 51 is adhered. When irradiating the laser beam L on the mask 2 for the organic EL by transmission through a layer of the organic material 51, the organic material 51 is maintained in a solid state and the laser beam L by which the mask 2 for the organic EL is not deformed after irradiation is irradiated. Moreover, by irradiating the laser beam L, since thermal expansion difference is formed between the organic material 51 and the mask 2 for the organic EL, removal of the organic material 51 is carried out by acting a peeling-off force between the layers. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an organic EL mask cleaning method for cleaning by scanning laser light on an organic EL mask, an organic EL mask cleaning apparatus, an organic EL display manufacturing apparatus, and an organic EL display.

  2. Description of the Related Art Organic EL (Electro Luminescence) displays are widely used as low power consumption, lightweight, and thin image display devices that do not require a backlight. As its structure, an organic EL thin film layer is laminated on a transparent glass substrate, and the organic EL thin film layer has a light emitting layer as a hole injection layer, a hole transport layer, an electron injection layer, an electron transport layer, and an anode layer. And a cathode layer are employed. The light emitting layer is often formed as a thin film by vapor-depositing an organic material on a glass substrate, and each pixel region constituting the display is divided into three to deposit organic materials of three colors of RGB. . Therefore, vapor deposition is performed using an organic EL mask (shadow mask) in which a large number of openings are formed in order to deposit different color organic materials (organic dye materials) in the three regions of each pixel. The deposition process of the light emitting layer is completed by depositing the organic materials of the respective colors while shifting the organic EL mask by the pixel pitch.

  When performing the vapor deposition process, the organic material adheres not only to the glass substrate but also to the organic EL mask. Since the organic EL mask is not used only for one vapor deposition process but is used repeatedly, if an organic material adheres to the organic EL mask during the next vapor deposition process, a new glass The organic material adhering to the substrate is transferred and contaminated. In addition, an organic material is deposited on edge portions of the openings formed in the organic EL mask so that the area of the openings is partially or entirely blocked. Obviously, if all of the openings are blocked, partial blocking may cause an obstacle (shadow or shadow) during deposition, and the deposition accuracy when using the organic EL mask is significantly reduced and can be used. It is no longer a thing. Therefore, the organic EL mask is periodically removed (preferably after completion of one vapor deposition process) to remove the organic material.

  As cleaning of the organic EL mask, a cleaning liquid that dissolves an organic substance or a wet cleaning using a surfactant or the like is mainly performed. Wet cleaning is cleaning performed by supplying a liquid to the organic EL mask. However, the organic EL mask to be cleaned is an ultra-thin metal plate on the order of microns (about 10 to 50 μm), and distortion is caused by the action of ultrasonic pressure and heating for promoting liquid pressure and cleaning during wet cleaning. Large damage such as deformation is given to the organic EL mask. In addition, when wet cleaning is performed using chemicals such as surfactants, a chemical solution supply mechanism and a drainage treatment mechanism for processing used chemicals (drainage) are required, which complicates the mechanism and causes environmental pollution due to drainage. There is also a problem. Furthermore, in recent years, organic EL masks have become larger. In this case, a large amount of cleaning liquid is used, and running costs also increase.

  On the other hand, Patent Document 1 discloses a technique relating to cleaning (laser cleaning) performed by irradiating an organic EL mask with laser light as cleaning without using wet cleaning. By irradiating the metal organic EL mask with laser light, a peeling force is applied between the organic EL mask and the organic material. The technique of Patent Document 1 is to perform cleaning by removing the organic material from the organic EL mask by this peeling force. And the adhesive film is affixed on the mask for organic EL, and the cleaning process is performed by transferring the peeled organic material to an adhesive film.

JP 2006-169573 A

  In the technique disclosed in Patent Document 1, laser light is irradiated toward an organic EL mask (evaporation mask) to induce movement of the surface to which the organic material (deposit) is attached, thereby peeling the organic material. It is carried out. The laser light first enters the layer of organic material, passes through this layer, and enters the organic EL mask.

  Since the organic EL mask is used repeatedly, it is necessary to prevent deformation such as distortion or warpage. If the organic EL mask is damaged and deformed to such an extent that it cannot be restored to its original state, it becomes impossible to perform vapor deposition using the organic EL mask accurately. For this reason, the organic EL mask cannot be reused in the next vapor deposition process. When the organic EL mask is irradiated with laser light, the temperature of the portion irradiated with the laser light and its vicinity rises locally. If the temperature rises extremely at this time, the organic EL mask 2 is damaged so that it cannot be restored to its original state.

  Therefore, the present invention has an object to obtain a high degree of cleaning without irreparably damaging the organic EL mask when removing the organic material adhering to the organic EL mask using laser light. And

  In order to solve the above-described problems, the organic EL mask cleaning method according to claim 1 of the present invention is a method for removing an organic material by scanning the surface of an organic EL mask to which an organic material is adhered by scanning a laser beam. In the mask cleaning method, when the organic EL mask is irradiated with the laser light through the organic material, the organic material is maintained in a solid state, and the organic EL mask is not deformed after irradiation. It is characterized by irradiating with laser light.

  According to this organic EL mask cleaning method, even if the organic material is transmitted and irradiated with laser light, the organic material is maintained in a solid state and the organic EL mask is not deformed. Thereby, when laser cleaning is performed, a high degree of cleaning can be obtained without irreparably damaging the organic EL mask.

  The organic EL mask cleaning method according to claim 2 of the present invention is the organic EL mask cleaning method according to claim 1, wherein the organic material and the organic EL mask are irradiated by irradiating the laser beam. The organic material is removed by applying a peeling force between layers by providing a difference in thermal expansion due to a temperature difference.

  According to this organic EL mask cleaning method, by applying laser light, a difference in thermal expansion can be provided between the organic EL mask and the organic material, whereby the organic material is removed from the organic EL mask. Can be peeled off.

  The organic EL mask cleaning method according to claim 3 of the present invention is the organic EL mask cleaning method according to claim 2, wherein the wavelength of the laser light λ depends on the organic material and the organic EL mask. Is characterized in that a wavelength is selected from “400 nm ≦ λ ≦ 1200 nm” so that the organic material is maintained in a solid state and the organic EL mask can be restored after thermal expansion.

  According to this organic EL mask cleaning method, the wavelength of the laser beam is selected as described above in accordance with the organic material and the organic EL mask. Thereby, a high degree of cleaning can be obtained without irreparably damaging the organic EL mask.

  The organic EL mask cleaning method according to a fourth aspect of the present invention is the organic EL mask cleaning method according to the third aspect, wherein the laser beam is a pulse laser.

  According to this organic EL mask cleaning method, by using a pulse laser, the energy of the laser beam can be concentrated at the time of one irradiation, and a high peeling effect can be obtained. In addition, since the laser beam is irradiated intermittently at different points, problems such as fluidization of the organic material and damage to the organic EL mask can be avoided.

  The organic EL mask cleaning method according to claim 5 of the present invention is the organic EL mask cleaning method according to claim 4, wherein spots of spots formed when the laser light is irradiated onto the organic EL mask. The diameter is controlled.

  According to this organic EL mask cleaning method, the spot diameter of the laser beam formed on the organic EL mask can be adjusted. By reducing the spot diameter, the organic material removal efficiency can be increased, and by increasing the spot diameter, the cleaning efficiency can be increased. Therefore, the optimum removal efficiency and cleaning efficiency can be set by adjusting the spot diameter.

  The organic EL mask cleaning apparatus according to claim 6 of the present invention is an organic EL mask cleaning apparatus that removes the organic material by scanning a laser beam on the surface of the organic EL mask to which the organic material is adhered. When the organic EL mask is irradiated with the laser light through the organic material, a laser light source that maintains the organic material in a solid state and oscillates the laser light that is not deformed after the organic EL mask is irradiated is provided. It is characterized by that.

  The organic EL mask cleaning device according to claim 7 of the present invention is the organic EL mask cleaning device according to claim 6, wherein the laser light source generates heat due to a temperature difference between the organic material and the organic EL mask. A laser beam for removing the organic material by causing a peeling force to act between the layers by giving an expansion difference is characterized.

  An organic EL mask cleaning apparatus according to an eighth aspect of the present invention is the organic EL mask cleaning apparatus according to the seventh aspect, wherein the laser light source depends on the organic material and the organic EL mask. The wavelength λ of the laser light is characterized in that the organic material is maintained in a solid state from “400 nm ≦ λ ≦ 1200 nm” and the organic EL mask oscillates at a wavelength that can be restored after thermal expansion.

  The organic EL mask cleaning device according to claim 9 of the present invention is the organic EL mask cleaning device according to claim 8, wherein the laser light source oscillates a pulse laser.

  The organic EL mask cleaning device according to claim 10 of the present invention is the organic EL mask cleaning device according to claim 9, wherein the condensing means for condensing the laser beam and the focal position of the laser beam are changed. And a focal position changing means.

  An organic EL display manufacturing apparatus according to an eleventh aspect of the present invention includes the organic EL mask cleaning apparatus according to any one of the sixth to tenth aspects. An organic EL display according to a twelfth aspect of the present invention is manufactured by the organic EL display manufacturing apparatus according to the eleventh aspect.

  In the present invention, when the organic material is removed by irradiating the organic EL mask with laser light, the organic material is maintained in a solid state when the laser light is transmitted, so that the organic material can be reliably peeled off. Thus, a high degree of cleaning can be obtained. Since the laser light is given a condition that allows the organic EL mask to be restored to its original state after being thermally expanded by irradiating the organic EL mask with the laser light, the organic EL mask can be reused.

It is an external view of the mask cleaning apparatus for organic EL. It is the side view and top view of an organic EL mask. It is a figure explaining the peeling process when a laser beam is irradiated. It is a figure which shows whether an organic material can maintain a solid state with a wavelength. It is an external view of the mask cleaning apparatus for organic EL at the time of providing two laser light sources. It is a figure explaining peeling of the organic material adhering to the side wall of the micro opening part of the mask for organic EL.

  Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, an organic EL mask cleaning device (device for laser cleaning the surface of an organic EL mask with laser light) of the present invention includes a base 1, an organic EL mask 2, a mask holding member 3, and laser scanning means 4. It has a schematic configuration. The base 1 is a base for mounting each element of the organic EL mask cleaning device. In FIG. 1, the X direction and the Y direction are two directions orthogonal to each other on a horizontal plane, and the Z direction is a vertical direction. The direction indicated by the arrow in the Z direction is upward, and the opposite side is downward. Therefore, gravity acts in the opposite direction of the arrow.

  The organic EL mask 2 is an object to be cleaned that is cleaned using an organic EL mask cleaning device. As shown in FIG. 2, the organic EL mask 2 is an ultra-thin metal plate used for patterning by depositing an organic material as a light emitting layer on a glass substrate 20 constituting an organic EL display. In order to deposit an organic material on the glass substrate 20 with high accuracy, an extremely thin metal plate having a thickness of about 10 to 50 μm is used for the organic EL mask 2. As the size of the organic EL display is increased, the size of the organic EL mask 2 is also increased. For this reason, the organic EL mask 2 is an extremely thin and large metal plate.

  The organic EL mask 2 has a mask body 21, and is a mask metal plate (shadow mask) in which a large number of minute openings (about 30 μm × 80 μm) 22 regularly arranged in the mask body 21 are formed. . As the material for the organic EL mask 2, various metals can be used. For example, a nickel-based alloy (invar), 42 alloy, or the like can be used. The organic EL mask 2 is made to deposit an organic material from a deposition source in a state of being in close contact with the glass substrate 20 in a vacuum deposition tank (not shown) for depositing the organic material of the light emitting layer.

Various organic materials can be used for the light emitting layer, and any organic material such as Alq ₃ , Ir (ppy) 3, and α-NPD can be used. The organic material evaporated from the vapor deposition source is vapor-deposited on the glass substrate 20 through the minute opening 22 of the organic EL mask 2. Thereby, an organic material as a light emitting layer is deposited on a region corresponding to the pixel of the glass substrate 20 to form a pattern. Since the organic EL mask 2 is a large and extremely thin metal plate, as shown in FIG. 2, a reinforcing frame 23 is attached around the periphery thereof to provide shape retention. The reinforcing frame 23 may be a metal material or a material other than metal.

  When the vapor deposition process is performed once using the organic EL mask 2, the organic material adheres not only to the glass substrate 20 but also to the organic EL mask 2. Since the vapor deposition process is repeatedly performed, cleaning of the organic material attached to the organic EL mask 2 is performed at a predetermined timing (preferably, for each vapor deposition process). Since the cleaning tank in which the organic EL mask cleaning device is disposed and the vacuum deposition tank for vapor deposition on the glass substrate 20 are provided separately and independently, the organic EL mask 2 is used when performing the organic EL mask cleaning device. It is transferred from the vacuum deposition tank to the cleaning tank.

  As shown in FIG. 1, the organic EL mask 2 is held in a vertical state (the normal direction of the surface of the organic EL mask 2 is the horizontal plane direction). Therefore, the mask holding member 3 has the same size as or larger than the size of the organic EL mask 2, and the organic EL mask 2 and the mask holding member 3 are usually aligned with high accuracy. It is integrated by welding. At the time of vapor deposition, the organic EL mask 2 is attracted by a large number of magnets from the back surface of the glass substrate 20, and the organic EL mask 2 is uniformly adhered evenly. The organic EL mask 2 may be held in a laid state (the normal direction of the surface of the organic EL mask 2 is vertical).

  The laser scanning unit 4 will be described. The laser scanning unit 4 includes a laser light source 41, a galvano mirror 42, and a galvano driving unit 43, and is schematically configured. The laser light source 41 is a light source that oscillates the laser light L. Here, the laser light source 41 oscillates a pulse laser. A pulse with a very short time width is input to the laser light source 41, and the laser light L is oscillated intermittently in synchronization with the pulse. Therefore, the irradiation time of the laser light L in one pulse can be controlled by adjusting the pulse time width (pulse width).

  The laser light source 41 is disposed so that the laser light L is irradiated downward in the Z direction, and a galvano mirror 42 is disposed at the incident position of the laser light. The galvanometer mirror 42 is a reflection mirror that scans the laser beam L, and the irradiation direction of the laser beam L changes by moving the mirror minutely at high speed. Thereby, the laser beam L is scanned on the organic EL mask 2. The scanning with the laser beam L is performed on a predetermined area (cleaning area) of the organic EL mask 2. This cleaning area may be set on the entire surface of the organic EL mask 2 or may be set on a part of the area. In any case, the cleaning area is a surface, and in order to clean the surface, the laser beam L is scanned in the X direction to form one scan line, and this scan line is slightly shifted in the Z direction. To clean the surface. Further, a galvano drive unit 43 is attached to the galvano mirror 42, and the galvano drive unit 43 moves the galvano mirror 42.

  A condensing lens 44 as a condensing means is disposed between the laser light source 41 and the galvanometer mirror 42. The laser light L oscillated from the laser light source 41 is parallel light, and a condensing lens 44 is provided on the optical path of the laser light L in order to focus the laser light L. A lens position adjusting member 45 as a focal position adjusting unit is attached to the condenser lens 44. The lens position adjusting member 45 is a member for moving the condenser lens 44 along the optical path of the laser light L (moving in the Z direction). Thereby, the position of the condensing lens 44 is changed, and the focal position can be changed (defocusing is possible). The condensing lens 44 and the lens position adjusting member 45 can be disposed at arbitrary positions as long as the condensing lens 44 is on the optical path of the laser light L.

  Next, the carrier air flow forming means 6 will be described. The carrier air flow forming means 6 includes a blower unit 61 and an air suction unit 62 and is schematically configured. The blower 61 is attached to a blower support 63 consisting of two struts extending in the Y direction, and the air suction part 62 is also attached to a wind suction support 64 consisting of two struts extending in the Y direction. Yes. Further, the air blowing support portion 63 and the air suction support portion 64 are each attached to the base 1. The air suction part 62 is provided with a recovery part 65, and the recovery part 65 recovers the sucked free substance.

  The blower 61 is formed with a blow slit 61S having a long slit length and a short slit width. Similarly, a wind absorption slit 62S having a long slit length and a short slit width is also formed in the wind absorption portion 62. The air blowing slit 61S and the air suction slit 62S are formed so as to face the same position in the Y direction, and are formed at positions separated from the surface of the organic EL mask 2. Air is blown downward from the blower slit 61 </ b> S, and the air suction slit 62 </ b> S sucks the upper air, so that an air flow is formed between the blower 61 and the air sucker 62. This air flow is referred to as a carrier air flow. In addition, although the conveyance airflow is formed by the slit provided in the ventilation part 61 and the air suction part 62, you may employ | adopt mechanisms other than a slit.

  The mask moving means 7 will be described. The mask moving means 7 is a moving means for moving the organic EL mask 2, and is schematically constituted by a moving table 71. The moving table 71 is a table for fixing and moving the mask holding member 3 in a vertical state. As the moving table 71, for example, a ball screw means, a linear motor means, a robot means or the like can be applied. As the moving table 71 moves, the organic EL mask 2 moves in a vertical state. Although the movement table 71 shows an example of moving in the X direction, it may be movable in the Y direction and the Z direction.

  Next, the operation will be described. First, after vapor deposition material is vapor-deposited on the glass substrate 20 using the organic EL mask 2 in a vacuum vapor deposition tank, the organic EL mask 2 is carried into an organic EL mask cleaning device disposed in the cleaning tank. At the time of carry-in, the organic EL mask 2 is held in contact with the mask holding member 3 and is held upright. In this state, the moving table 71 moves the organic EL mask 2 to the position of the carrier air flow forming means 6 in the X direction and stops at that position.

  Then, cleaning is started with the organic EL mask 2 stopped. This cleaning (laser cleaning) is performed by scanning the laser beam L toward the organic EL mask 2. The laser light L oscillated from the laser light source 41 is converged by the condenser lens 44, then reflected by the galvano mirror 42 and applied to the organic EL mask 2. The organic EL mask 2 is arranged so that the surface (front surface) to which the organic material is attached faces the direction of laser light irradiation, and the laser light reflected by the galvano mirror 42 is irradiated to the organic EL mask 2. .

  As shown in FIG. 3A, a solid organic material 51 is attached to the surface of the organic EL mask 2 as a film, and the laser light L passes through the organic material 51 and the organic EL 51 transmits the organic EL. The mask 2 is irradiated. The laser beam L is converged by a condenser lens 44 and focused on the surface (or the vicinity thereof) of the organic EL mask 2. The laser light L focused on the surface (or the vicinity thereof) of the organic EL mask 2 is absorbed by the organic EL mask 2.

  For this reason, the spot diameter of the laser beam L formed on the organic EL mask 2 is a very small region (circular region), and the laser beam L is absorbed in this region. The organic EL mask 2 is a metal material, and heat energy acts by absorbing the laser light L, and the temperature of the absorbed portion (circular region and its vicinity) instantaneously rises. Moreover, since the laser light L is focused near the surface of the organic EL mask 2, only a very small portion of the surface layer portion (several μm) in the thickness direction rises in temperature.

  The portion of the organic EL mask 2 whose temperature has risen causes thermal expansion. As described above, since the laser light L is absorbed in a very narrow region and the thermal energy concentrates, the temperature rises instantaneously, and the portion where the temperature rises rapidly undergoes thermal expansion. On the other hand, the thermal energy exerted by the laser beam L is concentrated in a very narrow region, and the other portions maintain their shapes without increasing in temperature. Accordingly, as shown in FIG. 3B, thermal expansion occurs toward the organic material 51 attached in a solid state.

  As shown in FIG. 3A, the layer of the organic EL mask 2 and the layer of the organic material 51 have a laminated structure. As will be described later, even when the laser beam L is transmitted, the organic material 51 maintains a solid state. That is, while the organic EL mask 2 undergoes thermal expansion and rises instantaneously, the organic material 51 hardly undergoes thermal expansion, so that a peeling force acts between the layers. At this time, when the organic EL mask 2 suddenly undergoes thermal expansion and a peeling force acts, the organic material 51 in a solid state is crushed by a strong impact, and the organic material 51 has a particle size such as powder. It becomes a small free substance and scatters in a direction away from the organic EL mask 2.

  The scattered free substance tries to fall downward in the Z direction by the action of gravity. Then, a carrier air flow is formed by the carrier air flow forming means 6 in the scattering direction, and the free material is collected in the air suction portion 62 by being supplemented by the carrier air flow. Thereby, the scattered free substance does not reattach to the organic EL mask 2, and the problem of a decrease in cleaning degree due to the reattachment of the free substance does not occur.

  As described above, the laser beam L oscillates as a pulse laser. Since the galvano mirror 42 scans so that the irradiation position of the laser beam L changes in one direction (X direction: scanning direction), scanning is performed so that the circular regions are continuous. This scan is performed in one direction to form one scan line, and the scan line is finely shifted in the Z direction (direction perpendicular to the X direction) to clean the surface. The circular area is not necessarily the same shape as the spot formed when the organic EL mask 2 is irradiated with the laser light L, and may be a wider area.

  Here, the wavelength of the laser light L oscillated from the laser light source 41 satisfies two conditions. The first condition is that the organic material 51 remains in a solid state even when the laser beam L is transmitted, and the second condition can be restored after the organic EL mask 2 is thermally expanded by irradiating the laser beam L. Satisfy that.

  The first condition will be described. As shown in FIG. 3A, the laser light L is transmitted through the layer of the organic material 51 and applied to the organic EL mask 2. At this time, the laser beam L may also be absorbed by the organic material 51. When, for example, Ir (ppy) 3 is applied as the organic material 51, when the laser light L having a short wavelength (for example, 532 nm or less) is incident, the laser light L is absorbed by the organic material 51. This is because the intrinsic absorption spectrum of Ir (ppy) 3 has a property of absorbing laser light of the wavelength.

  The organic material 51 has a lower melting point than the organic EL mask 2. For this reason, when the laser light L is absorbed in the solid organic material 51 and thermal energy acts, it melts from the solid state and becomes a fluid. The organic EL mask 2 can be thermally expanded to peel the organic material 51 because the organic material 51 maintains a solid state. In this case, a peeling force can be applied between the layers. On the other hand, when it becomes a fluid, even if the organic EL mask 2 is thermally expanded, a peeling force cannot be applied between the layers, and the organic material 51 cannot be removed. Note that even when the laser light L is absorbed by the organic material 51 and softened from the solid state, a peeling force cannot be applied to the organic material 51.

  For this reason, even if the laser beam L permeate | transmits, the organic material 51 must maintain a solid state. Therefore, the wavelength of the laser beam L that satisfies the condition is selected. Since the absorption spectrum of the organic material 51 differs depending on the material, the wavelength of the laser beam L that can maintain the organic material in a solid state is selected according to the type of the organic material 51. The absorption spectrum of the organic material 51 has a property of absorbing short-wavelength laser light and not absorbing long-wavelength laser light. For this reason, the organic material 51 can be peeled off by selecting a laser beam having a wavelength of 1064 nm, for example, without selecting an extremely short wavelength for the laser beam L. In any case, when the wavelength is less than 400 nm, it is absorbed by the organic material 51 and loses its solidity, so the lower limit value of the laser light L is set to 400 nm.

  By oscillating the laser light L satisfying the above conditions from the laser light source 41, the absorption rate of the laser light L into the organic material 51 can be reduced. However, no matter what material is used, the absorptance is not completely 0%. For this reason, if the laser beam L is continuously applied to the same portion, slight absorption may accumulate, and the organic material 51 may lose its solidity. For this reason, the laser light L oscillated from the laser light source 41 is used as a pulse laser, and the laser light L is irradiated intermittently. In addition, since the scanning is performed by the galvanometer mirror 42, the irradiation position is changed for each irradiation. Thereby, the laser beam L is not continuously irradiated to the same portion.

  At this time, as described above, one irradiation time is controlled by adjusting the pulse width. If the pulse width is excessively increased, the irradiation time for the same part is also increased, and the organic material 51 may lose its solidity. On the other hand, if the pulse width is excessively shortened, the organic EL mask 2 may not be thermally expanded to the extent that the organic material 51 can be peeled off. For this reason, the organic material 51 is appropriately set to a pulse width necessary for maintaining the solid state and peeling the organic material 51.

  As described above, the laser light L is hardly absorbed by the organic material 51 and is incident on the organic EL mask while the organic material 51 is maintained in a solid state. Thereby, a temperature difference can be given between the organic EL mask 2 and the organic material 51, and a peeling force can be applied between the layers. Therefore, the organic material 51 is peeled off from the organic EL mask 2 and removed.

  Next, the second condition will be described. As described above, when a laser beam having a short wavelength region enters the organic material 51, the organic material 51 is dissolved by absorption and changes from a solid state to a fluid (or soft body). From this point of view, it is desirable that the wavelength of the laser beam L is longer. However, when the wavelength of the laser beam L is increased, the organic EL mask 2 is significantly damaged. This is because the longer the wavelength of the laser beam L, the closer to the infrared wavelength region, and the greater the amount of heat that acts when entering the organic EL mask 2.

  The narrow region of the organic EL mask 2 is instantaneously heated by the irradiation of the laser beam L and thermally expands. However, after the thermal expansion, it must be restored to the original shape again. At this time, when the temperature of the organic EL mask 2 is excessively increased by the laser light L, the original state is not restored while being deformed, and when the temperature is extremely increased, the organic EL mask 2 may be dissolved.

  The organic EL mask 2 cannot be reused even when the organic EL mask 2 is melted or deformed so as not to be restored. When an organic material is deposited on the glass substrate 20 using the organic EL mask 2, extremely high deposition accuracy is required. Therefore, when the organic EL mask 2 is slightly deformed during vapor deposition, the next vapor deposition process cannot be performed using the organic EL mask 2. In other words, it cannot be reused.

  For this reason, even if the organic EL mask 2 is thermally expanded by irradiating the laser light L, the laser light L that can be restored to the original state after the heat is released is irradiated. For this purpose, the wavelength of the laser light L is selected so that the organic EL mask 2 can be restored after thermal expansion. Thereby, even if the laser beam L is irradiated, the organic EL mask 2 is restored to its original shape, and can be reused in the next vapor deposition process. Various metal materials can be used for the organic EL mask 2, and resilience varies depending on the selected material. Accordingly, the laser light L having a long wavelength can be used to some extent if the material has a high resilience, and the wavelength of the laser light is not excessively long if the material has a low resilience. That is, according to the organic EL mask 2, a wavelength at which the organic EL mask 2 can be restored after thermal expansion is selected. However, even if any material is used, if the laser light L exceeding the wavelength of 1200 nm is irradiated, the organic EL mask 2 is damaged irreparably. For this reason, the upper limit of the laser beam L is set to 1200 nm.

  On the other hand, at the time of laser cleaning, the laser light L is concentrated on a very narrow region of the organic EL mask 2 to raise the temperature to such a degree that the organic material 51 can be exfoliated. Further, since the change is caused only in the narrow region and on the surface layer, the organic EL mask 2 is not deformed.

  As described above, the organic EL 51 is irradiated with the laser light L that maintains the solid state and can be restored to the original state after the thermal expansion, so that the laser cleaning can be performed with a high degree of cleaning. The organic EL mask 2 can be reused. FIG. 4 shows the relationship between the organic material 51 and the wavelength λ of the laser light L. In this figure, the oscillation intensity is an average oscillation intensity (watt) of the laser beam L necessary for peeling off the target organic material 51, and this oscillation intensity is made constant according to each material. In addition, as wavelengths of the laser light L, two wavelengths of 532 nm and 1064 nm that are used as standard are shown. In the figure, “de” indicates a defocus amount (unit: millimeter).

As shown in this figure, in the Alq _3, lambda is be any of the 532nm and 1064 nm, can be peeled off the Alq ₃ in the organic material 51. This is because Alq ₃ does not absorb the laser beam L to the extent that the solid state cannot be maintained in the wavelength region of 532 nm.

  On the other hand, Ir (ppy) 3 and α-NPD can be peeled off when λ = 1064 nm, but cannot be peeled off when λ = 532 nm. This is because the laser beam L of 532 nm has a high absorption rate of Ir (ppy) 3 and α-NPD, and the organic material 51 cannot maintain a solid state. Thereby, the solidity of the organic material 51 is lost and cannot be peeled off.

  Here, referring back to FIG. 1, the condenser lens 44 can be moved in the Z-axis (optical axis) direction by the lens position adjusting member 45. As a result, the focal position of the laser beam L can be changed (defocusing is possible). By adjusting the defocus amount, the spot diameter of the laser light L spot formed on the organic EL mask 2 can be adjusted.

  From the viewpoint of peeling the organic material 51, it is desirable to reduce the spot diameter. This is because by reducing the spot diameter, the region where the energy of the laser beam L acts can be concentrated, and thermal expansion to the extent that the organic material 51 can be peeled off can be achieved. In other words, if the spot diameter is excessively increased, the organic material 51 cannot be peeled off. On the other hand, when the spot diameter is increased, laser cleaning can be completed in a short time. That is, if the spot diameter is increased, a wide range of the organic material 51 can be peeled at a time, so that the time required for laser cleaning can be shortened accordingly.

  From the above points, by controlling the condensing lens 44 and the lens position adjusting member 45, the spot diameter is such that the organic material 51 can be peeled off and the laser cleaning can be completed in a short time. desirable. For example, a defocus amount (20 mm) as shown in FIG. 4 is desirable.

  In addition, by changing (defocusing) the focal position of the laser light L using the condenser lens 44 and the lens position adjusting member 44, the organic material 51 attached to the side wall of the minute opening 22 can be removed. This point will be described with reference to FIG. The minute opening 22 is a region penetrating in the thickness (10 to 50 μm) direction of the organic EL mask 2, and a side wall 22W is formed in the penetrating region. The organic material 51 also adheres to the side wall 22W.

  At this time, when the laser light L is parallel light, the side wall 22W is not irradiated with the laser light L. This is because the side wall 22W is parallel to the normal direction of the surface 2S of the organic EL mask 2, and the laser light L is incident from the normal direction of the organic EL mask 2. Further, when the focal position F of the laser light L and the organic EL mask 2 are in a positional relationship as shown by the phantom line in FIG. When the focal position F is deviated, the side wall 22W is not irradiated with the laser light L.

  For this reason, defocusing is performed so that the focal position F of the laser light L is shifted toward the laser light source 41 with respect to the surface 2S of the organic EL mask 2. By performing such defocusing, the laser beam L is irradiated onto the side wall 22W of the minute opening 22. Thereby, the organic material 51 adhering to the side wall 22W can be peeled off due to the difference in thermal expansion. Therefore, the lens position adjusting member 44 adjusts the position of the condenser lens 44 so as to perform the defocus as described above.

  Further, the laser beam L may not be a pulse laser. That is, the laser light source 41 may oscillate the laser light L that is continuously irradiated. However, as described above, when the laser beam L is continuously applied to the same portion of the organic material 51, the organic material 51 is dissolved despite the use of the laser beam L having a wavelength that is hardly absorbed. There is a case to do. Further, when the irradiation is continuously performed, the same portion of the organic EL mask 2 is constantly heated by the laser light L, and therefore there is a possibility that the organic EL mask 2 is damaged. For this reason, it is desirable to perform intermittent irradiation using a pulse laser and change the irradiation position for each irradiation.

  1 shows an example in which one laser light source 41 is provided, a plurality of laser light sources 41 may be provided. FIG. 5 shows an example provided with two laser light sources 41A and 41B. The laser light sources 41A and 41B are light sources that oscillate laser beams L having different wavelengths, and when used, only one of them is switched and used. For this purpose, for example, the laser light sources 41A and 41B are configured to be movable in the X direction in the figure, and one of the laser light sources oscillates the laser light toward the galvanometer mirror 42. Of course, instead of moving the laser light source itself, an optical element (for example, a reflection mirror or a half mirror) that joins the optical paths of the laser beams emitted from the two laser light sources may be used.

  Thereby, it is possible to remove a plurality of types of organic materials 51. When an organic material 51 made of Alq3 is attached to the organic EL mask 2, a laser light source 41A that oscillates a laser beam L having a wavelength of 532 nm is used, and Ir (ppy) 3 or When the organic material 51 made of α-NPD is attached, a laser light source 41B that oscillates laser light L having a wavelength of 1064 nm can be used.

  In addition, as described above, when the organic EL mask 2 is irradiated with the laser light L, the organic EL mask 2 undergoes thermal expansion due to local temperature rise, and causes the organic material 51 to have a peeling force. It is as follows. In this case, after the organic material 51 is peeled off, heat is still accumulated in the organic EL mask 2, whereby the organic EL mask 2 maintains a high temperature state. For this reason, stress is applied to the organic EL mask 2 and there is a possibility of deformation such as distortion or warping.

  Therefore, the temperature of the accumulated heat can be cooled by applying air (preferably cold air) from the surface opposite to the surface of the organic EL mask 2 (the surface on which the organic material 51 is adhered). Thereby, stress can be reduced in the organic EL mask 2.

2 mask for organic EL 4 laser scanning means 6 carrier air flow forming means 7 mask moving means 41 laser light source 42 galvano mirror 43 galvano driving part 44 condenser lens 45 lens position adjusting member 51 organic material

Claims (12)

An organic EL mask cleaning method for removing the organic material by scanning a laser beam on the surface of the organic EL mask to which the organic material is attached,
When the organic EL mask is irradiated with the laser light through the organic material, the organic material is maintained in a solid state, and the organic EL mask is irradiated with laser light that does not deform after irradiation. A method for cleaning an organic EL mask. By irradiating the laser beam, the organic material and the organic EL mask are given a thermal expansion difference due to a temperature difference, thereby removing the organic material by applying a peeling force between the layers. The organic EL mask cleaning method according to claim 1. Depending on the organic material and the organic EL mask, the wavelength λ of the laser light is maintained in a solid state from “400 nm ≦ λ ≦ 1200 nm”, and the organic EL mask is heated. The organic EL mask cleaning method according to claim 2, wherein a wavelength that can be restored after expansion is selected. The organic EL mask cleaning method according to claim 3, wherein the laser beam is a pulse laser. The organic EL mask cleaning method according to claim 4, wherein a spot diameter of a spot formed when the laser light is irradiated on the organic EL mask is controlled. An organic EL mask cleaning device that removes the organic material by scanning a laser beam on the surface of the organic EL mask to which the organic material is attached,
A laser light source that maintains the organic material in a solid state and transmits laser light that is not deformed after irradiation when the organic EL mask is irradiated with the laser light through the organic material; An organic EL mask cleaning device comprising: The laser light source oscillates a laser beam that removes the organic material by applying a peeling force between layers by providing a difference in thermal expansion due to a temperature difference between the organic material and the organic EL mask. The organic EL mask cleaning device according to claim 6. The laser light source maintains the organic material in a solid state from among “400 nm ≦ λ ≦ 1200 nm” with a wavelength λ of the laser light according to the organic material and the organic EL mask, and the organic light source The organic EL mask cleaning device according to claim 7, wherein the EL mask oscillates a wavelength that can be restored after thermal expansion. The organic EL mask cleaning apparatus according to claim 8, wherein the laser light source oscillates a pulse laser. Condensing means for condensing the laser light;
A focal position changing means for changing a focal position of the laser beam;
The organic EL mask cleaning device according to claim 9, comprising:   11. An organic EL display manufacturing apparatus comprising the organic EL mask cleaning apparatus according to claim 6.   An organic EL display manufactured by the apparatus for manufacturing an organic EL display according to claim 11.

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