JP2009259565A - Mask cleaning device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a film of a mask from being damaged or generating position changes in pattern openings due to difference in thermal expansion, in case of cleaning of the mask consisting of the film and a frame. <P>SOLUTION: The mask 4 is conveyed to a first and a second cleaning tubs 8, 9, a first and a second rinsing tubs 10, 11 one after another, by a mask conveying device 5 equipped with a cooling means 6. By providing a heating means 7 for heating the film 1 of the mask 4 in pulling up the mask 4 from each rinsing tub 10, 11, and the cooling means 6 for cooling the frame 2, film damage or the like caused by difference of thermal expansion between the film 1 of the mask 4 and the frame 2 is prevented. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a mask cleaning apparatus that removes material adhering to a mask formed of a film and a frame used for mask formation in a manufacturing process of an organic EL element or the like.

  An organic EL element is an element in which an organic compound between both electrodes emits light by a current flowing between a cathode and an anode. Since the organic EL element is self-luminous and has high visibility, it can be made thin and light, and therefore, its application to an active matrix panel for mobile use is being promoted.

  The manufacturing process of an organic EL element includes a vapor deposition process in which an organic material used for forming a hole transport layer, a light emitting layer, and an electron transport layer and a metal material used for forming an auxiliary electrode are patterned by a vapor deposition method. As a mask used in the vapor deposition process, a tension mask is used in which a film with a pattern opening is fixed to a strong frame by applying a predetermined tension to cancel the pattern position change caused by thermal expansion due to temperature rise during vapor deposition. The

In the manufacture of organic EL elements, various materials adhere to the mask in the vapor deposition process. Furthermore, by repeatedly using the same mask, the material is deposited on the mask, and the accuracy of vapor deposition decreases. There is a method in which a mask with reduced accuracy is discarded and an unused mask is used. However, since the mask is expensive, the cost increases.
In order to avoid this, there is known a method for avoiding an increase in cost by cleaning the mask with a cleaning liquid or the like, removing the material attached to the mask, and regenerating the mask (see Patent Document 1).

JP 2006-1000026 A

  However, organic EL elements are increasingly required to be miniaturized due to high definition of display devices, and as a result, reduction in mask pattern size, reduction in film thickness, and improvement in pattern position accuracy are in progress. When such a mask using a thinner film having a smaller pattern opening than that of a conventional mask is cleaned with a conventional cleaning apparatus, damage to the mask film or a change in the position of the pattern opening occurs. For this reason, the mask cannot be reproduced while maintaining the required pattern position accuracy.

  The reason why such mask damage or the like occurs is estimated as follows.

  When cleaning with a conventional cleaning device, after the mask has been processed with the cleaning processing liquid, the processing liquid volatilizes from the mask surface when the mask is pulled up, and the heat of vaporization reduces the temperature of the mask film. Since the frame has a large heat capacity, the temperature hardly decreases.

  In other words, the film shrinks due to a decrease in temperature, and the frame is maintained at the temperature of the processing solution. Therefore, it is presumed that excessive tension occurs in the film and mask damage occurs.

  This situation is a big challenge when high pattern position accuracy is required in a mask using a thinner film that has a smaller pattern opening than a conventional mask, resulting in large damage and pattern opening position change. It was.

  The present invention is a mask capable of regenerating a mask while maintaining the required pattern position accuracy without mask damage or pattern opening position change even when a mask using a thin film is cleaned. The object is to provide a cleaning device.

  The mask cleaning apparatus of the present invention is a mask cleaning apparatus for cleaning a mask comprising a film having a pattern opening and a frame, a processing tank for storing a processing liquid for cleaning the mask, and the mask for the processing tank. And a heating means for heating the film so as to reduce a temperature difference between the film and the frame when the mask is lifted from the processing tank. It is characterized by having.

  Even when cleaning a mask using a thin film with a small pattern opening, the film is heated when the mask is lifted from the processing tank, and the temperature difference from the frame is reduced, so that excessive tension is applied to the film. Prevent it from occurring.

  As a result, the mask can be reproduced while maintaining the required pattern positional accuracy without any mask damage or deformation.

  The best mode for carrying out the present invention will be described with reference to the drawings.

  FIG. 1A shows an example of a tension mask for mask film formation. A film 1 is held on a metal frame 2. The film 1 is made of a metal thin film in which a predetermined pattern opening 3 is formed, and its outer periphery is fixed in a state where a tension is applied to the frame 2. The mask 4 configured in this way is cleaned by a mask cleaning apparatus shown in FIG.

  This cleaning device includes a mask transport device 5, a cooling means 6 provided in the mask transport device 5, a heating means 7, a first cleaning tank 8, a second cleaning tank 9, a first rinse tank 10, a second rinse tank 11, A drying tank 12 and a pump 13 for depressurizing the drying tank 12 are provided.

  The mask 4 is held by a mask transfer device 5 and includes a first cleaning tank 8 and a second cleaning tank 9 which are processing tanks, a first rinsing tank 10 and a second rinsing which are processing tanks in which heating means 7 are arranged in the respective openings. It is processed in the tank 11 and dried under reduced pressure in the drying tank 12.

  Examples of the cleaning liquid (processing liquid) stored in the first cleaning tank 8 and the second cleaning tank 9 include organic solvents, but are not limited thereto. In particular, petroleum solvents, hydrocarbon solvents, glycol solvents, glycol ether solvents, glycol ester solvents, N-methyl-2-pyrrolidone, cyclohexanone, N, N-dimethylformamide, and 1,4-dioxane are used. Is preferred.

  The boiling point of the organic solvent is preferably 100 ° C to 250 ° C. In the case of using an organic solvent having a boiling point exceeding 100 ° C., when the mask is lifted from the cleaning tank, the temperature drop of the film due to evaporation of the cleaning liquid is not significant, so the first cleaning tank 8 and the second cleaning tank 9 Then, it is not necessary to heat the film. However, a solvent having a boiling point exceeding 250 ° C. is not preferable because the cost of the distillation regeneration increases. The liquid temperature of the cleaning liquid is preferably in the range of 30 ° C to 60 ° C. The higher the liquid temperature, the higher the cleaning ability, but it becomes difficult to cool the frame. When the liquid temperature is low, the cleaning ability decreases, and the time required for cleaning becomes longer.

  Examples of the rinse liquid (treatment liquid) accommodated in the first rinse tank 10 and the second rinse tank 11 include alcohol solvents, hydrofluorocarbon solvents, and hydrofluoroether solvents. However, the solvent is not limited to these, and any solvent that can be quickly dried may be used. The rinsing liquid has a high evaporation rate, and when the mask 4 is lifted from the rinsing tanks 10 and 11, the temperature of the film 1 of the mask 4 rapidly decreases due to the heat of vaporization. The temperature difference between the frame 2 and the film 1 is reduced. The liquid temperature of the rinse liquid is preferably in the range of 20 ° C to 40 ° C. When the liquid temperature is high, it becomes difficult to cool the frame. When the liquid temperature is low, the material dissolved in the rinse liquid may be deposited and recontaminated.

  The number of washing tanks and rinsing tanks is not limited to two each, and may be one or three or more. The greater the number of tanks, the better the cleanliness, but the larger the device and the higher the cost.

  Moreover, you may provide a heating means in the opening part of a washing tank. In the case of using a cleaning liquid that has a low boiling point and is easily dried in the cleaning tank, the cleaning tank can also serve as a rinse, and the rinse tank can be eliminated. Eliminating the rinsing tank reduces the cost of the apparatus, but the degree of cleaning may decrease due to poor rinsing.

  Examples of the drying method in the drying tank 12 include, but are not limited to, vacuum drying or vacuum drying. The drying temperature is preferably 20 ° C to 60 ° C. The higher the drying temperature, the faster the drying speed, but it becomes difficult to cool the frame. When the drying temperature is low, the drying speed is slow, and the time required for drying becomes long.

  Instead of the drying tank 12, a steam cleaning tank 14 may be used as shown in FIG. Steam is generated by a heater 16 in a steam cleaning tank 14 provided with a cooling pipe 15, and the steam is condensed and liquefied on the mask 4, thereby cleaning the mask 4. When the mask receives heat from the steam and reaches a temperature near the boiling point, the condensation becomes small, and when it is removed, it becomes dry. The steam cleaning tank 14 is provided with a cooling pipe 15 for condensing and recovering the steam in order to prevent excessive loss of steam. Since the steam cleaning is based on the above-described drying method, the steam cooling means 6 must be performed during the steam cleaning. If the cooling means 6 is used, it cannot be completely dried because vapor condensation continues to occur in the cooled frame.

  Examples of the heating means 7 include a means for heating with a hot wire. More specifically, examples include, but are not limited to, infrared lamps, halogen lamps, carbon lamps, infrared light emitting diodes, ceramic heaters, and infrared irradiation electric heaters. Irradiation with wavelengths of heat rays (infrared rays, far infrared rays, etc.) Heating means can be used.

  Alternatively, a means for heating by induction heating may be used. Induction heating is a method of heating an object to be heated by an eddy current generated when an alternating current is passed through a coil, and the heating accuracy is good.

  The heating means may be arranged so that the film is heated uniformly, and a plurality of heating means may be arranged side by side.

  In addition, more precise heating control can be performed by linking the device for measuring the temperature of the film and the heating means. As a method for measuring the temperature of the film, non-contact measurement with a radiation thermometer is preferable. In the case of a contact thermometer such as a thermocouple, accurate measurement cannot be performed because the heat capacity of the film is small, and damage is caused because the film itself is thin.

  The heating temperature of the film by the heating means is preferably within ± 10 ° C. in the cleaning device.

  The cleaning apparatus of FIGS. 1 and 2 includes a cooling unit, and the frame of the mask is cooled to a predetermined temperature by the cooling unit.

  An example of the cooling means is a means for cooling by heat conduction by cooling a portion of the mask transfer device that is in contact with the frame.

  As a method for cooling the portion in contact with the frame, a method of circulating a cooling medium and a method of cooling with a Peltier element can be mentioned.

  Further, a frame having a structure capable of circulating the cooling water in the frame of the mask may be used, and the cooling medium may be circulated in the frame.

  The cooling temperature of the frame by the cooling means is preferably within ± 10 ° C of the air temperature in the cleaning device.

  As shown in FIG. 1B, the mask 4 is held by a mask transfer device 5 having a cooling means 6, and includes a first cleaning tank 8, a second cleaning tank 9, a first rinse tank 10, and a second rinse tank 11. And dried in the drying tank 12.

  In the first cleaning tank 8 and the second cleaning tank 9, a petroleum solvent having a boiling point of 180 ° C. to 207 ° C. was used as a cleaning liquid at a liquid temperature of 40 ° C.

  In the first rinse tank 10 and the second rinse tank 11, isopropyl alcohol was used as a rinse liquid at a liquid temperature of 30 ° C.

  In the drying tank 12, vacuum drying was performed at 30 ° C.

  The temperature inside the cleaning device was 25 ° C. ± 2 ° C.

  An infrared lamp was used as the heating means 7 and when the mask 4 was pulled up, it was heated so that the film temperature did not become 20 ° C. or less, and the temperature difference between the frame 2 and the film 1 was reduced.

  A cooling water circulator was used as the cooling means 6, and cooling water at 20 ° C. was circulated through the mask transfer device to cool the frame 2.

  Although the appearance inspection and pattern opening position measurement of the cleaned mask were performed under the above conditions, there was no damage on the appearance, and the position change amount of the pattern opening was below the lower limit of measurement.

  As shown in FIG. 2, the mask 4 is held by a mask transfer device 5 having a cooling means 6 and processed in a first cleaning tank 8, a second cleaning tank 9, a first rinse tank 10, and a second rinse tank 11. Then, it is dried in the steam drying tank 14.

  In the first cleaning tank 8 and the second cleaning tank 9, N-methyl-2-pyrrolidone was used as a cleaning liquid at a liquid temperature of 40 ° C.

  In the first rinsing tank 10 and the second rinsing tank 11, hydrofluoroether was used as a rinsing liquid at a liquid temperature of 30 ° C.

  The steam drying tank 14 was dried by steam drying with hydrofluorocarbon. The operation of the cooling means 6 was stopped during the steam drying.

  The temperature inside the cleaning device was 25 ° C. ± 2 ° C.

  Induction heating was used as the heating means 7 and when the mask 4 was pulled up, it was heated so that the film temperature did not fall below 20 ° C.

  Peltier cooling was used as the cooling means 6, and the frame was cooled by cooling the portion of the mask transfer device in contact with the frame to 20 ° C., except during steam drying.

  Although the appearance inspection and pattern opening position measurement of the cleaned mask were performed under the above conditions, there was no damage on the appearance, and the position change amount of the pattern opening was below the lower limit of measurement.

  As shown in FIG. 3, the mask 4 is held by a mask transfer device 5 having no cooling means, and a first cleaning tank 8, a second cleaning tank 9, and a third cleaning tank 17 each having a heating means 7 at the opening. And dried in the drying tank 12.

  In the first cleaning tank 8, the second cleaning tank 9, and the third cleaning tank 17, a petroleum solvent having a boiling point of 50 ° C to 80 ° C was used as a cleaning liquid at a liquid temperature of 40 ° C.

  In the drying tank 12, vacuum drying was performed at 30 ° C.

  The temperature inside the cleaning device was 25 ° C. ± 2 ° C.

  An infrared lamp was used as the heating means 7 and heated so that the film temperature did not become 20 ° C. or lower when the mask 4 was pulled up.

  Although the appearance inspection and pattern opening position measurement of the cleaned mask were performed under the above conditions, there was no damage on the appearance, and the position change amount of the pattern opening was below the lower limit of measurement.

  As shown in FIG. 4, the mask 4 is processed in the first cleaning tank 8, the second cleaning tank 9, and the third cleaning tank 17 that are held by the mask transfer device 5 having the cooling unit 6 and do not have the heating unit. It is dried in a steam drying tank 14 equipped with a cooling pipe 15 and a heater 16.

  In the first cleaning tank 8, the second cleaning tank 9, and the third cleaning tank 17, cyclohexanone was used as a cleaning liquid at a liquid temperature of 50 ° C.

  The steam drying tank 14 was dried by steam drying with hydrofluorocarbon. The operation of the cooling means 6 was stopped during the steam drying.

  The temperature inside the cleaning device was 25 ° C. ± 2 ° C.

  A cooling water circulator was used as the cooling means 6, and cooling water at 20 ° C. was circulated through the mask transfer device except during steam drying to cool the frame.

  Although the appearance inspection and pattern opening position measurement of the cleaned mask were performed under the above conditions, there was no damage on the appearance, and the position change amount of the pattern opening was below the lower limit of measurement.

(Comparative Example 1)
For comparison, mask cleaning was performed by stopping the operation of the heating unit 7 and the cooling unit 6 of Example 1. When the surface temperature of the film pulled up from the rinse tank and the frame was measured using a radiation thermometer, the surface temperature of the film was 7 ° C., and the surface temperature of the frame was 30 ° C. When the appearance of the washed mask was inspected and the pattern opening position was measured, the film was wrinkled, and the amount of change in the pattern opening position exceeded the allowable amount.

(Comparative Example 2)
For comparison, the operation of the heating means 7 of Example 3 was stopped and mask cleaning was performed. When the surface temperature of the film pulled up from the washing tank and the frame was measured using a radiation thermometer, the film surface temperature was 13 ° C. and the frame surface temperature was 40 ° C. When the appearance of the cleaned mask was inspected and the pattern opening position was measured, there was no damage to the appearance, but the amount of change in the pattern opening position exceeded the allowable amount.

(Comparative Example 3)
For comparison, the operation of the cooling means 6 of Example 4 was stopped and mask cleaning was performed. When the surface temperature of the film pulled up from the washing tank and the frame was measured using a radiation thermometer, the film surface temperature was 26 ° C. and the frame surface temperature was 50 ° C. When the appearance of the washed mask was inspected and the pattern opening position was measured, the film was wrinkled, and the amount of change in the pattern opening position exceeded the allowable amount.

It is a schematic diagram which shows an example of a tension mask and the mask cleaning apparatus by Example 1. FIG. 6 is a schematic diagram showing a mask cleaning apparatus according to Embodiment 2. FIG. 6 is a schematic diagram showing a mask cleaning apparatus according to Embodiment 3. FIG. FIG. 10 is a schematic diagram illustrating a mask cleaning apparatus according to a fourth embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Film 2 Frame 3 Pattern opening 4 Mask 5 Mask conveying apparatus 6 Cooling means 7 Heating means 8 1st washing tank 9 2nd washing tank 10 1st rinse tank 11 2nd rinse tank 12 Drying tank 13 Pump 14 Steam drying tank 15 Cooling Tube 16 Heater 17 Third cleaning tank

Claims (6)

A mask cleaning apparatus for cleaning a mask composed of a film having a pattern opening and a frame,
A treatment tank containing a treatment liquid for cleaning the mask;
A mask transporting device for transporting the mask to the processing bath and pulling it up from the processing liquid;
A mask cleaning apparatus, comprising: a heating unit that heats the film so as to reduce a temperature difference between the film and the frame when the mask is lifted from the processing tank.   2. The mask cleaning apparatus according to claim 1, wherein the heating means is means for heating the film with heat rays, which is disposed in an opening of the processing tank.   2. The mask cleaning apparatus according to claim 1, wherein the heating means is a means for heating the film by induction heating, which is disposed in an opening of the processing tank. A mask cleaning apparatus for cleaning a mask composed of a film having a pattern opening and a frame,
A treatment tank containing a treatment liquid for cleaning the mask;
A mask transporting device for transporting the mask to the processing bath and pulling it up from the processing liquid;
A mask cleaning apparatus comprising: cooling means for cooling the frame so as to reduce a temperature difference between the film and the frame when the mask is lifted from the processing tank. A mask cleaning apparatus for cleaning a mask composed of a film having a pattern opening and a frame,
A treatment tank containing a treatment liquid for cleaning the mask;
A mask transfer device for transferring the mask to the treatment tank and lifting it;
Heating means for heating the film so as to reduce a temperature difference between the film and the frame when pulling up the mask from the processing tank;
And a cooling means for cooling the frame of the mask.   The cleaning apparatus according to claim 4, wherein the cooling unit is provided in the mask transfer device and cools the frame by heat conduction from the mask transfer device.

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