JP2005105328A - Method for manufacturing mask structure, mask structure and vapor deposition apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mask structure which prevents a metal mask from being sagged due to thermal expansion during vapor deposition by effectively applying tension on a metal mask in an initial state, and maintains a high accuracy of a pattern. <P>SOLUTION: This method for manufacturing the mask structure comprises forming a metal mask material layer 3 to become a metal mask 13 on a base metal 1; arranging a cut part 2 in a perimeter of the metal mask material layer 3; abutting a frame 14 with a lower coefficient of thermal expansion than the base metal 1 to the perimeter of the metal mask 13; and bonding the metal mask material layer 3 to the frame 14 with an adhesive 14a and fixing them, in the state of keeping the base metal 1, the metal mask material layer 3 and the frame 14, heated to a predetermined temperature. When they are cooled to ordinary temperature, a tension is generated in the metal mask 13 caused by a difference of thermal expansion between the base metal 1 and the frame 14. By deforming the base metal 1 by exerting such an external force on its perimeter located outside the cut part 2, the metal mask 13 is peeled off from the base metal 1. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a mask structure, a mask structure, and a vapor deposition apparatus for use in an organic EL device, particularly an organic EL device manufacturing apparatus such as 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. In general, a dry process represented by vacuum deposition is used for a low-molecular material, and a spin process is used for a high-molecular material. A wet process typified by a coat 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 the deposited portion has been lost during deposition and using mask 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 problem, a configuration using a frame having a higher thermal expansion coefficient than the mask (Japanese Patent Laid-Open No. 2002-069619) and a method of fixing a pre-tensioned mask to the frame (Japanese Patent Laid-Open No. 10-041069) are also available. Proposed.
JP 2002-066961 A Japanese Patent Laid-Open No. 10-041069

  According to the prior art, there are the following unsolved problems.

  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 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. It is an object of the present invention to provide a method for manufacturing a mask structure, a mask structure, and a vapor deposition apparatus, in which it is extremely easy to fix the metal mask to the frame.

  In order to achieve the above object, a method for manufacturing a mask structure according to the present invention is a method for manufacturing a mask structure including a metal mask and a frame that supports the metal mask, and a base material having a larger coefficient of thermal expansion than the frame. And a step of heating the manufactured metal mask and the base material and the frame to a predetermined temperature, and bonding and fixing the metal mask and the frame in a heated state. A tension is generated in the metal mask fixed to the frame by a difference in thermal expansion between the base material and the frame in the state.

  It is preferable to have a step of cutting the metal mask along the outer periphery of the frame and peeling the base material together with the outer peripheral portion of the metal mask by a deforming external force acting on the outside of the cut.

  The mask structure of the present invention has a metal mask formed on a base material and a frame that supports the metal mask, and heats the metal mask together with the base material and the frame, A mask structure in which the base material is peeled and removed after bonding to the frame, wherein the base material is made of a material having a larger coefficient of thermal expansion than the frame, and the base material and the frame in the temperature rising state The metal mask is fixed to the frame in a state in which a tension based on a difference in thermal expansion is applied.

  The vapor deposition apparatus of the present invention includes the above mask structure, substrate holding means for holding a substrate so as to face the mask structure, and a vapor deposition source that generates an evaporation substance toward the mask structure and the substrate. It is provided with.

  For example, in a vapor deposition apparatus used for manufacturing an organic EL display configured by arranging a plurality of organic EL element pixels, a metal mask used for dividing a light emitting pixel is manufactured on a metal base material by electrolytic plating, Bond and fix to a frame with a smaller coefficient of thermal expansion than the 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 to each other in a heated state.

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

  After bonding and fixing the metal mask to the frame in this way, an external force is applied to the outside of the notch formed in the metal mask on the base material in advance to deform the base material and peel it 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.

  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, and therefore the manufacturing cost of the mask structure can be greatly reduced.

  In addition, the work of peeling the base material from the metal mask is also performed using the notch 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 Mask pattern accuracy can be improved.

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

  FIG. 1 schematically shows a vapor deposition apparatus for manufacturing an organic EL device using a mask structure according to an embodiment. The vapor deposition source 11, a heater 12, and a substrate W are held in a chamber 10 (not shown). A substrate holder as a substrate holding means, a mask holder (not shown) that supports a mask structure including a metal mask 13 and a frame 14, a shutter 15, an exhaust system 16, and the like. The metal mask 13 and the frame 14 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 14 is disposed in the chamber 10, and the interior 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. 2 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. 2, 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 this tension will be described. FIG. 3 is a flowchart showing the steps from creation of the metal mask to fixing it to the frame. In step 1, 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. 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 frame are heated to maintain a steady state where the temperature has been increased. 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. A frame having a smaller coefficient of thermal expansion than the base material is used.

  In step 9, the metal mask material layer and the frame are bonded while maintaining the temperature. After the adhesive is cured and cooled, in step 10, the base material is peeled off from the metal mask. 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 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.

  FIG. 4A shows a cross section of the mask structure after the resist is removed. A metal mask material layer 3 having notches 2 formed by plating is provided on the base material 1. The notch 2 is provided at a position corresponding to the outer periphery of the 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. 4B, a metal mask 23 in which a taper is formed in the pattern opening or the notch 22 may be formed by etching.

  Next, as shown in FIG. 5, the 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. 6 is a plan view of the metal mask 13 and the frame 14 as viewed in parallel with the mask surface. The notch 2 is disposed along the outer peripheral edge of the frame 14, and when an external force is applied to the outer edge A on the outer side, the notch 2 Stress concentration occurs at the interface between the metal mask material layer 3 and the base material 1 at point B, which is the corner of 2, and the metal mask 13 and base material 1 begin to peel off from point B.

  FIG. 7 illustrates a process of peeling the base material 1 after the metal mask 13 and the frame 14 are bonded and fixed. As shown in FIG. 7A, an external force is applied to the base material 1 to deform it out of the plane. Since the metal mask 13 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 mask structure shown in FIG. 7B 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.

  According to the present embodiment, a metal mask formed on a metal base material using electrolytic plating is bonded to the frame in a state of being thermally expanded together with the base material, and is peeled off from the base material after curing and cooling. In this state, a mask with high flatness can be easily manufactured by applying tension to the metal mask. By using such a mask structure, 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 having a large screen and higher definition.

  The mask structure according to the present invention 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 a semiconductor device.

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. It is a flowchart explaining the manufacturing process of the metal mask by one Embodiment. FIGS. 3A and 3B show a mask structure after the resist removing step of FIG. 3, in which FIG. 3A is a cross-sectional view showing the mask structure according to the present embodiment, and FIG. It is a figure explaining the adhesion process of a metal mask and a frame. It is a top view which shows the mask structure of FIG. The process of peeling a metal mask and a base material is demonstrated.

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

Claims (4)

A method of manufacturing a mask structure including a metal mask and a frame that supports the metal mask,
Manufacturing a metal mask on a base material having a larger coefficient of thermal expansion than the frame;
Heating the manufactured metal mask and the base material and the frame to a predetermined temperature, and bonding and fixing the metal mask and the frame in a heated state,
A method of manufacturing a mask structure, comprising: generating tension on a metal mask fixed to a frame based on a difference in thermal expansion between a base material and a frame in a temperature rising state.   2. The mask structure according to claim 1, further comprising a step of cutting the metal mask along the outer periphery of the frame and peeling the base material together with the outer peripheral portion of the metal mask by a deforming external force acting on the outside of the cut. Body manufacturing method.   A metal mask formed on a base material; and a frame for supporting the metal mask, the metal mask is heated together with the base material and the frame, and the base material is bonded to the frame in a heated state. A mask structure exfoliated and removed, wherein the base material is made of a material having a thermal expansion coefficient larger than that of the frame, and tension based on a difference in thermal expansion between the base material and the frame in the temperature rising state. A mask structure, wherein the metal mask is fixed to the frame in a state of being applied.   A mask structure according to claim 3, substrate holding means for holding a substrate so as to face the mask structure, and a vapor deposition source for generating an evaporation substance toward the mask structure and the substrate. The vapor deposition apparatus characterized by this.

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