Mask frame assembly

Abstract

A mask frame assembly is provided, the mask frame assembly comprising: a frame; a mask, coupled to the frame and comprising a pattern area for deposition on a substrate; and long side rods, coupled to the frame and dividing the pattern area of ​​the mask into unit cell patterns. The long side rods may include a cladding structure in which a relatively ferromagnetic layer and a relatively weak magnetic layer are stacked.

Description

[0001] The Korean Patent Application No. 10-2019-0007582, entitled “Mask Frame Assembly and Manufacturing Method Thereof,” filed on January 21, 2019 in the Korean Intellectual Property Office is hereby incorporated by reference in its entirety. Technical Field

[0002] Embodiments relate to a mask frame assembly for a deposition process, and a method of manufacturing the mask frame assembly. Background Art

[0003] Generally, an organic light emitting display device can realize color according to the principle that holes and electrons injected from an anode and a cathode recombine in an emission layer and emit light. Each pixel has a stacked structure in which an emission layer is located between a pixel electrode as an anode and a counter electrode as a cathode.

[0004] Each pixel can be one of a red sub-pixel, a green sub-pixel, and a blue sub-pixel, and a target color can be expressed by a combination of sub-pixels of the three colors. Therefore, in each sub-pixel, an emission layer that emits one of red light, green light, and blue light is located between two electrodes, and the color of the pixel unit is expressed by an appropriate combination of the three colors of light. Summary of the invention

[0005] The embodiment is directed to a mask frame assembly, the mask frame assembly comprising: a frame; a mask, coupled to the frame and comprising a pattern area for deposition on a substrate; and long side rods, coupled to the frame and dividing the pattern area of ​​the mask into unit cell patterns. The long side rods may include a cladding structure in which a relatively ferromagnetic layer and a relatively weak magnetic layer are stacked.

[0006] In the stacking direction, the thickness of the relatively ferromagnetic layer may be greater than the thickness of the relatively weak magnetic layer.

[0007] The protrusion protruding in the width direction may be located at the relatively weak magnetic layer.

[0008] The protrusion may correspond to a non-emission pattern at one side of the unit cell pattern.

[0009] The protrusion may include a semicircular shape.

[0010] A plurality of protrusions may be periodically arranged in the length direction at ends of the relatively weak magnetic layer in the width direction.

[0011] The cladding structure may include a structure in which a relatively weak magnetic layer is located between a pair of relatively ferromagnetic layers.

[0012] The relatively ferromagnetic layer may be an iron-nickel alloy layer, and the relatively weak magnetic layer may be a stainless steel layer.

[0013] When a magnetic force is applied to the long side rods from a position opposite to the long side rods, the long side rods can bring the mask and the substrate into close contact, with the mask and the substrate being located between the position and the long side rods.

[0014] The contact force applied to the mask by the long side rods may be a combination of a relatively strong attractive force with respect to the ferromagnetic layer and a relatively weak attractive force with respect to the weak magnetic layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Features will become apparent to those skilled in the art by describing in detail example embodiments with reference to the accompanying drawings, in which:

[0016] Figure 1 shows a deposition process in which a mask frame assembly according to example embodiments is used;

[0017] Figure 2 Shows Figure 1 An exploded perspective view of the mask frame assembly shown in;

[0018] Figure 3 Shows Figure 1 A top view of the mask frame assembly shown in ;

[0019] Figure 4 Shows Figure 2 An enlarged perspective view of area A shown in FIG.

[0020] FIG. 5A to FIG. 5C is shown sequentially in Figure 1 A cross-sectional view of the process of the long side rods in the mask frame assembly shown in FIG.

[0021] Figure 6 Shows Figure 1 A cross-sectional view of the detailed structure of the target substrate shown in FIG. DETAILED DESCRIPTION

[0022] Example embodiments will now be described more fully below with reference to the accompanying drawings; however, these example embodiments may be implemented in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey example implementations to those skilled in the art. In the drawn figures, the dimensions of layers and regions may be exaggerated for clarity of illustration. The same reference numerals indicate the same elements throughout.

[0023] In the following embodiments, unless an expression used in the singular has an apparently different meaning in the context, it includes an expression in the plural.

[0024] In the following embodiments, terms such as “including,” “having,” and “comprising” are intended to indicate the presence of features or components disclosed in the specification, and are not intended to exclude the possibility that one or more other features or components may be added.

[0025] When a specific embodiment can be implemented differently, the specific process order can be performed in a different order than described. For example, two processes described in succession can be performed substantially simultaneously or in a reverse order to the described order.

[0026] Figure 1 is a schematic diagram of a structure of a thin film deposition apparatus employing the mask frame assembly 100 according to example embodiments.

[0027] like Figure 1 As shown in , the thin film deposition apparatus is provided with a mask frame assembly 100 for forming a desired pattern on a target substrate 300 , and a deposition source 200 for spraying deposition vapor toward the target substrate 300 in a chamber 400 .

[0028] When the deposition source 200 sprays deposition vapor in the chamber 400, the deposition vapor passes through the pattern holes 121a (see FIG. 1 ) formed in the mask 120 of the mask frame assembly 100. Figure 2 ) and attached to the target substrate 300, thereby forming a thin film having a pattern. Reference numeral 500 denotes a magnet that applies a magnetic force to the mask 120 so that the mask 120 is in close contact with the target substrate 300.

[0029] According to the present exemplary embodiment, the mask frame assembly 100 includes Figure 2 1 , a mask 120 forming pattern holes 121 a, a frame 130 supporting both ends of the mask 120 , and long side rods 110 supported by the frame 130 and perpendicularly crossing the mask 120 in a plan view.

[0030] According to the present exemplary embodiment, the frame 130 forming the outer frame of the mask frame assembly 100 has a square shape with an opening 132 formed in the middle. Two opposite ends of the long side rods 110 in the length direction (x direction) are respectively fixed to a pair of sides of the frame 130 facing each other, for example, by welding, and two opposite ends of the mask 120 in the length direction (y direction) are respectively fixed to a pair of sides of the frame 130 perpendicular to the sides to which the long side rods 110 are welded, for example, by welding.

[0031] According to the present exemplary embodiment, the mask 120 includes a plurality of long rod-shaped members, a plurality of pattern holes 121a are formed in the pattern area 121 located in the opening 132, and the two opposite ends of the mask 120 are welded to the frame 130 as described above. Reference numeral 122 denotes a support portion. When the mask 120 is welded to the frame 130, the welding can be performed by fixing the support portion 122 and stretching the support portion 122 in the length direction, and after the welding is completed, the portion protruding outside the frame 130 can be removed by cutting. Figure 2 As shown in , the mask 120 may be formed of a plurality of separate rod shapes because, if the mask 120 is formed as one large member, severe deflection may occur due to its own load. The mask 120 may include Invar, which is an iron-nickel alloy.

[0032] The pattern holes 121a are holes through which deposition vapor passes in a deposition process, and the deposition vapor passing through the pattern holes 121a is attached to the target substrate 300 (see FIG. Figure 1 ) and form a thin film layer.

[0033] According to the present exemplary embodiment, the pattern area 121 is formed with a large length rather than being formed by connecting a plurality of unit cells with a constant pitch, and the long side rods 110 divide the pattern area 121 into unit cells. Therefore, as shown, the mask 120 and the long side rods 110 are installed to be in close contact with each other by vertically crossing the frame 130. Therefore, the long side rods 110 pass through the pattern area 121 of each portion in the mask 120 and divide the pattern area 121 into unit cells. Therefore, the long side rods 110 constitute the boundary lines between the unit cells. Figure 3 1 is a top view of the pattern area 121 divided into unit cell patterns 121b by the long side rods 110. As described above, the pattern area 121 is divided into a plurality of unit cell patterns 121b by the long side rods 110. In addition, a notch portion 121c as a non-linear non-emission pattern may be included in each unit cell pattern 121b. Therefore, a protrusion 111 covering the notch portion 121c to prevent a thin film for emission from being deposited on the notch portion 121c may be provided on the long side rods 110.

[0034] like Figure 4 As shown in , according to the present exemplary embodiment, the long side rod 110 has a cladding structure in which a plurality of metal layers are stacked.

[0035] Therefore, according to the present exemplary embodiment, the long side rod 110 has a sandwich-type stacking structure in which the relatively weakly magnetic second layer 110b is located between the relatively ferromagnetic first layer 110a and the third layer 110c. The first layer 110a and the third layer 110c may be or include Invar, which is an iron-nickel alloy, and the second layer 110b between the first layer 110a and the third layer 110c may be or include stainless steel.

[0036] According to the present exemplary embodiment, the long side rod 110 has a coating structure in which a first layer 110a and a third layer 110c as relatively ferromagnetic layers and a second layer 110b as a relatively weak magnetic layer are stacked so that the contact force applied to the mask 120 is maintained at an appropriate level that is neither too strong nor too weak.

[0037] When the magnet 500 (see Figure 1 ) is applied to the mask frame assembly 100, if the entire portion of the long side rods 110 will include Invar (as a ferromagnetic layer), the force from the long side rods 110 to press the mask 120 toward the target substrate 300 will be too strong, so that the pattern holes 121a of the mask 120 will be deformed due to the excessive force from the long side rods 110. Therefore, since a large gap is formed between the mask 120 and the target substrate 300 and excessive deposition occurs in the gap, an icicle defect may occur.

[0038] On the other hand, if the entire portion of the long side rods 110 were to include stainless steel (as a weak magnetic layer), the force from the long side rods 110 to press the mask 120 toward the target substrate 300 would be too weak, so that a shadow defect would occur in which the mask 120 and the target substrate 300 are not properly attached to each other and a gap exists therebetween. As a result, deposition would occur beyond the periphery of the desired deposition area.

[0039] Therefore, in this exemplary embodiment, the long side rod 110 is formed into a cladding structure in which the first layer 110a and the third layer 110c as ferromagnetic layers are stacked with the second layer 110b as a weak magnetic layer. Therefore, an appropriate level of contact force can be achieved by a combination of ferromagnetism and weak magnetism.

[0040] Furthermore, in this exemplary embodiment, if Figure 4 As shown in FIG. 1 , the thicknesses t1 and t3 of the first layer 110a and the third layer 110c as the ferromagnetic layer are set to be greater than the thickness t2 of the second layer 110b as the weak magnetic layer. Therefore, by including the second layer 110b as the weak magnetic layer, the contact force can be weakened compared to the case where the long side rod 110 includes only the ferromagnetic layer, but on the other hand, since too weak a contact force may cause a shadow defect, the weak magnetic layer is not used as a main layer.

[0041] In the present exemplary embodiment, the protrusion 111, which is the notch portion 121c for forming the unit cell pattern 121b, is formed at the second layer 110b, which is a weak magnetic layer. The presence of the protrusion 111 increases the area to which the magnet 500 is attracted by an amount corresponding to the area of ​​the protrusion 111. Therefore, when the protrusion 111 is formed at the first layer 110a and the third layer 110c, which are ferromagnetic layers, the contact force that has been reduced due to the second layer 110b, which is a weak magnetic layer, can be immediately offset or even increased. Therefore, the protrusion 111 is formed at the weak magnetic layer where the increase in contact force due to the increase in area is relatively small, that is, at the second layer 110b including stainless steel.

[0042] The long side rods 110 having the coating structure as described above can be manufactured by a pressing process and an etching process. The detailed manufacturing process of the mask frame assembly 100 including the long side rods 110 is described below.

[0043] Now refer to Figure 6 An example of a target substrate 300 on which deposition may be performed by using the mask frame assembly 100 is briefly described.

[0044] The mask frame assembly 100 may be used to deposit various thin films, for example, an emission layer pattern of an organic light emitting display device.

[0045] Figure 6 A structure of an organic light emitting display device is shown as an example of a target substrate 300 on which a thin film may be deposited by using the mask frame assembly 100 of example embodiments.

[0046] Reference Figure 6 , a buffer layer 330 is formed on the base plate 320 , and a thin film transistor TFT is disposed on the buffer layer 330 .

[0047] The thin film transistor TFT includes an active layer 331 , a gate insulating layer 332 covering the active layer 331 , and a gate electrode 333 on the gate insulating layer 332 .

[0048] An interlayer insulating layer 334 is formed to cover the gate electrode 333 , and a source electrode 335 a and a drain electrode 335 b are formed on the interlayer insulating layer 334 .

[0049] The source electrode 335 a and the drain electrode 335 b respectively contact the source region and the drain region of the active layer 331 via contact holes formed in the gate insulating layer 332 and the interlayer insulating layer 334 .

[0050] In addition, the pixel electrode 321 of the organic light emitting diode OLED is connected to the drain electrode 335b. The pixel electrode 321 is formed on the planarization layer 337, and the pixel defining layer 338 for dividing the sub-pixel area is formed on the pixel electrode 321. Reference numeral 339 indicates a spacer for preventing the components in the target substrate 300 from being damaged due to contact with the mask 120 by maintaining a gap between the mask 120 and the target substrate 300. The spacer 339 may be formed in a shape in which a portion of the pixel defining layer 338 protrudes. The emission layer 326 of the organic light emitting diode OLED is formed in the opening of the pixel defining layer 338, and the counter electrode 327 is deposited on the emission layer 326 and the pixel defining layer 338. Therefore, the opening surrounded by the pixel defining layer 338 is the area of ​​the sub-pixel such as the red pixel R, the green pixel G and the blue pixel B, and the emission layer 326 of the relevant color is formed in the opening defined by the pixel defining layer 338.

[0051] Therefore, for example, when the mask 120 is prepared so that the pattern holes 121a correspond to the emission layer 326, the emission layer 326 having a desired pattern can be formed by referring to Figure 1 The unit cell pattern 121 b may correspond to a display region of the organic light emitting display device.

[0052] In the following, reference will be made to Figure 2 and FIG. 5A to FIG. 5C The process of forming the mask frame assembly 100 for manufacturing the organic light emitting display device as described above is described. FIG. 5A to FIG. 5C Describing the process of manufacturing the long side rod 110 with the coating structure described above, we will return to the reference Figure 2 A process of manufacturing the mask frame assembly 100 including the long side rods 110 is described.

[0053] First, when manufacturing the long side rod 110, as Figure 5A As shown in , a first layer 110a (as a ferromagnetic layer and including Invar alloy), a second layer 110b (as a weak magnetic layer and including stainless steel) and a third layer 110c (as a ferromagnetic layer and including Invar alloy) are sequentially stacked and pressed to prepare a cladding structure.

[0054] Next, the above protrusions 111 are formed at the second layer 110b. Specifically, the end portions in the width direction (y direction) are removed from each of the first layer 110a and the third layer 110c by etching using photolithography, as shown in FIG. Figure 5B Therefore, an end portion 110b-1 of the second layer 110b in the width direction (y direction) is exposed to the outside.

[0055] Next, an etching process using photolithography is performed on the end portion 110b-1 of the second layer 110b exposed in the width direction (y direction) so that only the protrusion 111 remains. Thus, a structure in which a plurality of protrusions 111 are periodically arranged in the length direction (x direction) is formed at the end portion of the second layer 110b in the width direction. Therefore, the protrusion 111 is included in each unit cell pattern 121b in the above arrangement structure. Here, a case in which the protrusion 111 is semicircular is described, but the protrusion 111 may be formed in various shapes.

[0056] The long side bars 110 formed in the above-mentioned manner are fixed to the frame 130 (such as Figure 2 ), the mask 120 is selectively arranged on the long side rods 110, and the mask 120 is fixed by, for example, welding, thereby manufacturing the mask frame assembly 100.

[0057] By using the mask frame assembly 100 having the above structure, the force from the long side rods 110 that makes the mask 120 in close contact with the target substrate 300 can be maintained at an appropriate level that is neither too strong nor too weak. Therefore, deposition defects such as icicle defects or shadow defects can be fully controlled. Therefore, stable product quality can be guaranteed.

[0058] By summarizing and reviewing, the electrodes and emission layers of the organic light-emitting display device can be formed by deposition. Therefore, a mask having a pattern hole identical to the target pattern of the thin film layer to be formed can be aligned on the substrate, and the raw material of the thin film layer can be deposited on the substrate through the pattern hole in the mask to form a thin film of the target pattern.

[0059] The mask can be used in the form of a mask frame assembly together with a frame for supporting the edge of the mask and long side rods for dividing the pattern hole into a plurality of unit cell patterns. In the deposition operation, the mask is in close contact with the substrate due to magnetic force.

[0060] When the mask is in close contact with the substrate due to magnetic force, the long side rods are also attracted by the magnetic force, so that the mask is in closer contact with the substrate. Therefore, in the deposition operation, the magnet, the substrate, the mask and the long side rods are arranged in sequence. The mask and the long side rods are attracted to the substrate due to the magnetic force of the magnet, and the long side rods further press the mask to the target substrate. On the other hand, if the long side rods press the mask to the substrate with too strong a force, the pattern holes formed in the mask will be deformed due to the pressing force of the long side rods, so an icicle defect in which a large gap is formed between the mask and the substrate and over-deposition occurs in the gap will occur. If the long side rods press the mask to the substrate with too weak a force, a gap will be formed between the mask and the substrate, so a shadow defect in which deposition is performed beyond the periphery of the desired target deposition area will occur. Therefore, when the force used to press the mask to the substrate is too strong or too weak, a deposition defect will occur.

[0061] As described above, one or more embodiments include a mask frame assembly and a method of manufacturing the same which are improved to maintain the contact force applied by the long side rods to the mask at an appropriate level that is neither too strong nor too weak.

[0062] Example embodiments have been disclosed herein, and although specific terms are employed, these terms will be used and interpreted in a general and descriptive sense only and not for purposes of limitation. In some cases, it will be apparent to one of ordinary skill in the art that, from the time of filing this application, unless otherwise specifically noted, features, characteristics, and / or elements described in conjunction with a particular embodiment may be used alone or in combination with features, characteristics, and / or elements described in conjunction with other embodiments. Therefore, it will be understood by those skilled in the art that various changes in form and detail may be made without departing from the spirit and scope of the present invention as set forth in the claims.

Claims

1. A mask frame assembly, comprising: frame; a mask coupled to the frame and comprising a patterned area for deposition on a substrate; and long side rods coupled to the frame and dividing the pattern area of ​​the mask into unit cell patterns; The long side rod comprises a coating structure, in which a relatively ferromagnetic layer and a relatively weak magnetic layer are stacked and completely overlapped. Wherein, the coating structure includes a structure in which the relatively weak magnetic layer is located between a pair of relatively ferromagnetic layers, wherein the protrusion protruding in the width direction is located at the relatively weak magnetic layer, and The plurality of protrusions having the same magnetic properties as the relatively weak magnetic layer are periodically arranged along the length direction at ends of the relatively weak magnetic layer in the width direction.

2. The mask frame assembly according to claim 1, wherein: In the stacking direction, the thickness of the relatively ferromagnetic layer is greater than the thickness of the relatively weak magnetic layer.

3. The mask frame assembly according to claim 1, wherein: The protrusion corresponds to a non-emission pattern at one side of the unit cell pattern.

4. The mask frame assembly according to claim 1, wherein: The protrusion includes a semicircular shape.

5. The mask frame assembly according to claim 1, wherein: The relatively ferromagnetic layer is an iron-nickel alloy layer, and the relatively weak magnetic layer is a stainless steel layer.

6. The mask frame assembly according to claim 1, wherein: When a magnetic force is applied to the long side rods from a position opposite to the long side rods, the long side rods bring the mask and the substrate into close contact with each other, with the mask and the substrate being located between the position and the long side rods.

7. The mask frame assembly according to claim 6, wherein: The contact force applied to the mask by the long side rods is a combination of the relatively strong attractive force of the relatively ferromagnetic layer and the relatively weak attractive force of the relatively weak magnetic layer.

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