JP2006152339A - Vapor deposition mask structural body manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vapor deposition mask structural body having high durability capable of preventing a metal mask from being sagged by the thermal expansion in the vapor deposition using the mask for forming a pattern, and maintaining the high pattern accuracy. <P>SOLUTION: In a vapor deposition mask structural body manufacturing method, a mask under the tension is fixed to a first frame, a rear side of the mask and a second frame are fixed on the inner side of the first frame, and the mask is cut from the first frame. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a mask structure for vapor deposition. More specifically, the present invention relates to a method for manufacturing a mask structure for vapor deposition used in an organic EL device manufacturing apparatus or the like such as an organic EL display, particularly a high-definition color display using a low molecular light emitting material.

  When manufacturing a display using an organic EL element, a step of forming a metal electrode and a transparent electrode, a step of forming a TFT in the case of an active matrix method, and further, an electron transport layer, a light emitting layer, a hole transport layer, etc. A step of forming an organic thin film layer is required. In the organic layer deposition process, the film deposition method differs depending on whether the material is a low-molecular or high-molecular material. A wet process typified by coating or inkjet is used.

  In a color display, since the light emitting materials are different for the three primary colors of light, it is required to form films independently for the three primary colors. In order to form the three primary colors independently, the low molecular weight system is manufactured by using a metal mask from which a deposited portion has been lost during vapor deposition, and using mask vapor deposition in which only the missing portion is deposited. For polymer systems, a method of printing the three primary colors by inkjet printing is used.

When vapor-depositing a low molecular weight EL material using a mask, high accuracy is required for the mask because each of the three primary colors is pattern-deposited correctly. For example, in the case of a pixel pitch of 127 pixels per inch, the size of one pixel is 200 × 200 micrometers, and it is necessary to accurately deposit pixels of 200 × 67 micrometers for each of the three primary colors. If the mask temperature rises and the position of the mask shifts due to thermal expansion, pixels cannot be deposited correctly. For example, assuming that the size of the mask is 400 × 400 millimeters, the linear expansion coefficient of the mask is 1.3 × 10 ⁻⁵ / degree, and the temperature rise is 10 degrees, the thermal expansion causes a positional shift of 52 micrometers. .

In particular, when the mask is used while being fixed to a frame, a problem has been pointed out that the mask sag during the vapor deposition process due to the difference in thermal expansion coefficient between the mask and the frame. In order to solve this, a configuration using a frame having a thermal expansion coefficient larger than that of the mask (Patent Document 1), a method of removing the slack by attracting the mask with a magnetic force (Patent Document 2), a metal mask attached to the screen mesh and tension There is also proposed a method (Patent Document 3) in which the frame is fixed to the frame.
JP 2002-066961 A Japanese Patent Laid-Open No. 10-041069 JP 2003-64468 A

  According to the above technique, there is an unsolved problem as follows.

  The first problem is that the thickness of a metal mask or the like is generally as thin as several tens of micrometers. Therefore, after the metal mask is formed by a technique such as etching or plating, the metal mask is peeled off from the base material of the metal mask. However, there is a concern that the pattern accuracy is lowered due to plastic deformation.

  The second problem is that it is very difficult to fix the single metal mask peeled off from the base material to the frame by applying tension while maintaining accuracy, and this causes new problems such as an increase in manufacturing cost. .

  The third problem is that when a metal mask is fixed using an adhesive, it is difficult to maintain a high vacuum because of a large amount of gas released from the adhesive in the vacuum chamber, and the organic vapor deposition material adhering to the mask is removed. Since the solvent used in the step peels off the adhesive, the solvent cannot be used.

  The present invention has been made in view of the above-mentioned unsolved problems of the prior art, and the metal mask can be easily peeled off from the base material without sacrificing the pattern accuracy of the metal mask. A method of manufacturing a deposition mask structure and a deposition mask structure that are extremely easy to fix a metal mask to a frame by applying a film, are suitable for use in a vacuum, and have high durability against a cleaning solvent. It is for the purpose.

  Therefore, the present invention provides a method for manufacturing a deposition mask structure in which a mask is fixed to a frame, the step of fixing the tensioned mask to the first frame, and the inside of the first frame, Fixing the back surface of the mask fixed to the first frame and the second frame, and cutting the mask from the first frame at the outer periphery of the second frame. Thus, a method for manufacturing a vapor deposition mask structure is provided, in which a vapor deposition mask structure in which the mask is fixed to the second frame is obtained.

  In vapor deposition using a mask for pattern formation, a metal mask can be prevented from sagging due to thermal expansion, high pattern accuracy can be maintained, and a highly durable vapor deposition mask structure can be realized.

  In order to achieve the above object, a method for manufacturing a vapor deposition mask structure according to the present invention provides a method for manufacturing a vapor deposition mask structure in which a mask is fixed to a frame. Fixing the inner surface of the first frame, fixing the back surface of the mask fixed to the first frame and the second frame, and the outer periphery of the second frame; A method of manufacturing a vapor deposition mask structure, comprising: a step of cutting a mask from the first frame to obtain a vapor deposition mask structure in which the mask is fixed to the second frame. It is.

  More specifically, a method of manufacturing a vapor deposition mask structure including a metal mask that is a mask and a second frame made of a metal that supports the metal mask, the step of manufacturing the metal mask on a base material; The manufactured metal mask and the base material, and the first frame made of a material having a smaller coefficient of thermal expansion than the base material are heated to a predetermined temperature, and the metal mask and the first frame are bonded and fixed in a heated state. A step of peeling the base material and the metal mask at the outer periphery of the first frame, a step of spot welding a second frame made of metal inside the first frame at room temperature, and an outer periphery of the second frame Cutting the metal mask at the part, and welding the metal mask to the second frame with tension applied to the metal mask due to the difference in thermal expansion between the base material and the first frame in the elevated temperature state .

  When the base metal and the metal mask are peeled off at the outer periphery of the first frame, a cut is made in the metal mask in advance along the outer periphery of the first frame, and the base material is metalized by a deformed external force acting on the outside of the cut. It is good to have the process of peeling with the outer peripheral part of a mask.

  If the vapor deposition mask structure having such a process is used, for example, in the manufacture of an organic EL display configured by arranging a plurality of organic EL element pixels, the metal mask used when dividing the light emitting pixels is used as a metal mother. It is manufactured by electrolytic plating on the material, and is bonded and fixed to the first frame having a smaller coefficient of thermal expansion than the base material. At this time, the base material having the metal mask and the frame are heated, and the metal mask and the frame are bonded at a predetermined temperature. For the first frame, it is generally preferable to use a ceramic having a thermal expansion coefficient smaller than that of metal.

  After the metal mask is bonded and fixed to the first frame in this way, an external force is applied to the outside of the notch previously formed in the metal mask on the base material, and the base material is deformed and peeled off from the metal mask.

  The base material may have a thickness of about 1 millimeter or less so that it can be easily deformed out of plane by an external force.

  When the temperature returns to room temperature after bonding, the metal mask fixed to the first frame is in a state of being tensioned by the difference in thermal expansion between the base material and the frame.

  Next, a second frame made of metal is disposed inside the first frame, and after spot welding the metal mask and the second frame, the metal mask is cut at the outer periphery of the second frame.

  As described above, the metal mask can be fixed to the second frame made of metal with a tension applied.

  In order to maintain the flatness during deposition, the work of fixing the metal mask in the initial state to the frame by applying tension is simple and effective using the difference in the thermal expansion coefficient between the base material and the frame in the heat bonding process. Therefore, as compared with a case where tension is directly applied to the metal mask by an external force, the operation is simple and there is no fear of damaging the metal mask. Therefore, the manufacturing cost of the evaporation mask structure can be greatly reduced.

  In addition, the work to remove the base material from the metal mask is also performed by using the notches provided in the metal mask, so that troubles such as deformation of the metal mask during the base material peeling process can be avoided, and the mask pattern can be avoided. Accuracy can be improved.

  Since the second frame made of metal and the metal mask are joined by welding without using an adhesive, it is possible to provide a vapor deposition mask structure that is suitable for use in a vacuum apparatus and highly durable against a cleaning solvent.

  In addition, an example of a method for manufacturing a vapor deposition mask structure according to the present embodiment forms a metal mask using electroplating on a metal base material, and a difference in thermal expansion coefficient between the base material and the first frame. After the metal mask is fixed to the first frame with tension applied, the metal mask and the base material are peeled off. Next, under normal temperature, after spot welding the second frame made of metal and the metal mask inside the first frame, the metal mask is cut at the outer periphery of the second frame to form a deposition mask structure. It is also to create.

  Embodiments of the present invention will be described with reference to the drawings.

  1 is a flowchart showing the steps from the creation of the metal mask to the fixing of the metal mask to the frame according to the first embodiment of the present invention.

  Prior to the description of this step, an apparatus configuration and steps for manufacturing an organic EL device will be briefly described, and then a method for manufacturing an evaporation mask structure which is a feature of the present invention will be described.

  FIG. 7 shows an outline of a vapor deposition apparatus for manufacturing an organic EL device using a vapor deposition mask structure according to an embodiment. A vapor deposition source 11, a heater 12, and a substrate W are held in a chamber 10. It has a substrate holder (not shown), a mask holder (not shown) that supports a vapor deposition mask structure comprising a metal mask 13 and a frame 17, a shutter 15, an exhaust system 16, and the like. The metal mask 13 and the frame 17 are joined by a method described later.

  Next, the organic layer vapor deposition process of an organic EL element is demonstrated using FIG. A metal mask 13 bonded to the substrate W and the frame 17 is disposed in the chamber 10, and the inside of the chamber 10 is evacuated using an exhaust system 16 to maintain a high vacuum. The shutter 15 is closed so that the vapor deposition source 11 and the substrate W are blocked. In a state where a high vacuum is maintained, the heater 12 is energized to heat the vapor deposition source 11 that is previously filled with a vapor deposition material. In this state, since the shutter 15 is closed, impurities that are volatilized at a low temperature and contained in the deposition material are not deposited on the substrate W. After the temperature of the vapor deposition source 11 reaches a steady state, the shutter 15 is opened. When the shutter 15 is opened, the evaporated substance is deposited on the substrate W. At this time, the evaporated substance is blocked at the blocking portion of the metal mask 13 and only the opening portion of the metal mask 13 is deposited on the substrate W. After an appropriate film thickness is formed by vapor deposition, the shutter 15 is closed, and then the heater 12 is turned off.

  FIG. 8 is a graph showing temperature changes of the metal mask, the substrate, and the frame during the vapor deposition process. When the shutter is closed, the temperatures of the metal mask, the substrate, and the frame are equal and constant. When the shutter is opened, the temperature of the metal mask begins to rise. The temperature of the substrate also rises but is smaller than that of the metal mask. The flame temperature hardly rises. When the shutter is closed again, the temperature returns to the initial state.

  As can be seen from the graph of FIG. 8, the temperature of the metal mask rises while the shutter is open, so that the metal mask thermally expands. In order to prevent the metal mask from sagging due to this thermal expansion, a tension that does not sag at the highest temperature that can be assumed during vapor deposition is applied to the metal mask in the initial state. That is, the metal mask is fixed to the frame in a tensioned state.

  Next, a method for fixing the metal mask to the frame by applying tension, which is a feature of the present invention, will be described. FIG. 1 is a flowchart showing the steps from creation of a metal mask to fixing it to a frame. In step 1, the surface of the metal plate that is the base material of the metal mask is polished. As the base material, a stainless steel plate having a thickness of 1 mm or less, for example, a thickness of about 0.5 mm is used. In step 2, a resist is applied to the base material using a technique such as spin coating, and dried. In step 3, a mask pattern and a glass original plate with cuts to be described later are brought into close contact with a base material coated with a resist by photolithography, and the mask pattern and the like are exposed and transferred to the resist. In step 4, development is performed to remove the resist at the masking portion. In step 5, electrolytic plating is performed to form a metal mask material layer on the portion where the resist has been removed. The metal mask material layer uses nickel or the like. In step 6, the remaining resist is removed. When it is necessary to taper the mask opening or the like, etching is performed in step 7. In step 8, the metal mask material layer and the first frame are heated to maintain a predetermined constant temperature. Since the thickness of the base material is much larger than the thickness of the metal mask material layer, the thermal expansion is dominated by the base material rather than the metal mask material layer, and the metal mask material layer is stretched in the same way as the base material. It becomes a state. The first frame is made of a material having a smaller coefficient of thermal expansion than the base material, such as ceramic.

  In step 9, the metal mask material layer and the first frame are bonded while maintaining the temperature. After the adhesive is cured, the base material is peeled off from the metal mask in step 10. When cooled to room temperature, the metal mask is in tension due to the difference in coefficient of thermal expansion between the base material of the metal mask and the first frame. At this time, it is necessary to set the temperature to be heated in step 8 so that the metal mask can be tensioned even at the highest temperature assumed during the vapor deposition as described above.

  In step 11, the second frame made of a metal such as stainless steel and a metal mask are spot welded inside the first frame. The metal mask is fixed to the second frame in a tensioned state. If there is a concern about an increase in the temperature of the frame, a metal having a low coefficient of thermal expansion, such as Super Invar, may be used.

  In step 12, the metal mask is cut at the outer periphery of the second frame to complete the vapor deposition mask structure.

  FIG. 2A shows a cross section of the vapor deposition mask structure after removing the resist. A metal mask material layer 3 having a notch 2 formed by plating is provided on the base material 1. The cut 2 is provided at a position corresponding to the outer periphery of the first frame 14. The pattern of the notches 2 and the mask pattern of the metal mask 13 are drawn on the glass original plate described above and are simultaneously formed by electrolytic plating.

  If necessary, as shown in FIG. 2B, a metal mask 23 in which a taper is formed in the pattern opening or notch 22 may be formed by etching.

  Next, as shown in FIG. 3A, the first frame 14 is bonded to the metal mask material layer 3 using an adhesive 14a. The cut 2 is formed in the metal mask material layer 3 along the outer peripheral portion of the frame 14.

  FIG. 3B is a plan view of the metal mask 13 and the frame 14 viewed in parallel to the mask surface. The notches 2 are arranged along the outer peripheral edge of the frame 14 and apply an external force to the outer edge A on the outer side. Then, stress concentration occurs at the interface between the metal mask material layer 3 and the base material 1 at the point B which is the corner of the notch 2, and the metal mask 13 and the base material 1 begin to peel from the point B.

  FIG. 4 illustrates a process of peeling the base material 1 after the metal mask 13 and the frame 14 are bonded and fixed. When an external force is applied to the base material 1 as shown in FIG. Since it is bonded to the frame 14, the metal mask 13 and the base material 1 start to peel from the notch 2. Furthermore, when an external force is applied and the base material 1 is completely peeled off, a vapor deposition mask structure shown in FIG. 4B is obtained. As described above, it is desirable that the base material 1 has a thickness of 1 millimeter or less so that it can be easily deformed by an external force.

  FIG. 5 is a diagram illustrating a process of welding the second frame 17 made of metal and the metal mask 13. A second frame 17 made of metal is disposed inside the first frame 14 and brought into contact with the metal mask 13. The frame 17 and the metal mask 13 are spot welded by applying pressure to the second frame 17 and the metal mask 13 with the welding electrode tip 18 and applying a pulse current from a connected power source. After the four sides of the frame 17 and the metal mask 13 are welded, the metal mask 13 on the outer periphery of the frame 17 is cut.

  FIG. 6 shows a mask structure for vapor deposition after cutting the metal mask on the outer periphery of the frame, which is welded to the frame 17 in a state where the metal mask 13 is tensioned.

  According to the present embodiment, a metal mask formed on a metal base material using electrolytic plating is bonded to the first frame in a state of being thermally expanded together with the base material, and is peeled off from the base material after curing. A mask with high flatness in which a metal mask is tensioned can be easily manufactured. And the mask structure for vapor deposition with high durability suitable for use in a vacuum can be manufactured by welding the mask to which tension was applied to the second metal frame. By using such a mask structure for vapor deposition, the shape accuracy of the mask pattern can be maintained with high flatness even during film formation, and it becomes possible to manufacture a color organic EL display with a large screen and higher definition.

  The vapor deposition mask structure according to the present invention described above is not limited to a mask for manufacturing an organic EL element, but can also be used as a mask for forming other fine patterns such as semiconductor devices.

It is a flowchart explaining the manufacturing process of the metal mask by one Embodiment. 1 shows a vapor deposition mask structure after the resist removal step of FIG. 1, wherein (a) is a cross-sectional view showing a vapor deposition mask structure supported by a base material according to the present embodiment, and (b) is a modification. FIG. It is a figure explaining the adhesion | attachment process of a metal mask and a 1st flame | frame, (a) is sectional drawing, (b) is a top view. The process of peeling a metal mask and a base material is demonstrated. It is a figure explaining the welding process of a metal mask and a 2nd frame. It is a figure explaining the mask structure for vapor deposition after cutting a mask in the 2nd frame perimeter. It is a figure explaining the vapor deposition apparatus of an organic EL device. It is a graph which shows the temperature rise of the metal mask in a vapor deposition process, a board | substrate, and a flame | frame.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Base material 2, 22 Cut 3, 23 Metal mask material layer 11 Deposition source 12 Heater 13 Metal mask 14 Frame 14a Adhesive 15 Shutter 16 Exhaust system 17 Frame 18 Welding electrode tip

Claims (9)

In the method of manufacturing a vapor deposition mask structure in which the mask is fixed to the frame,
Fixing the tensioned mask to the first frame;
Fixing the back surface of the mask fixed to the first frame and the second frame inside the first frame;
Cutting the mask from the first frame at the outer periphery of the second frame,
A method for producing a vapor deposition mask structure, comprising: obtaining a vapor deposition mask structure in which the mask is fixed to the second frame.   The method for manufacturing a mask structure for vapor deposition according to claim 1, wherein the mask is a metal mask.   The metal mask is formed by electroplating on a base material, and is manufactured by peeling the base material after fixing the first frame and the metal mask on the opposite side of the base material of the metal mask. Item 3. A method for manufacturing a mask structure for vapor deposition according to Item 2.   The first frame and the metal mask are fixed at a specified temperature, the tension is applied to the metal mask by a difference in thermal expansion between the first frame and a base material when the temperature is returned to room temperature, and the metal mask is applied to the metal mask. 3. The method of manufacturing an evaporation mask structure according to claim 2, wherein the metal mask and the second frame are fixed in a state where the tension is applied.   The method for manufacturing a metal mask structure for vapor deposition according to claim 2, wherein the second frame and the metal mask are fixed by welding.   The method for manufacturing a metal mask structure for vapor deposition according to claim 2, wherein the first frame and the metal mask are fixed by bonding.   The metal mask structure for vapor deposition obtained by the manufacturing method of the metal mask structure for vapor deposition of the gas state as described in any one of Claims 1 thru | or 6.   A method for producing an organic EL element array, comprising: a light emitting point forming step of obtaining a plurality of light emitting points by depositing a vapor deposition material on a substrate through the metal mask structure according to claim 7.   The organic electroluminescent display obtained by the manufacturing method of the organic electroluminescent element array of Claim 8.

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