Mask for forming OLED pixels, mask support template, and frame-integrated mask

Abstract

The present invention relates to a mask for forming OLED pixels, a mask support template, and a frame-integrated mask. The mask according to the present invention is a mask for forming a plurality of mask patterns and for forming OLED pixels. The mask patterns include a first mask pattern in the upper part and a second mask pattern in the lower part. The thickness of the first mask pattern is greater than the thickness of the second mask pattern. Both side surfaces of the first mask pattern have a concave curvature. The upper width of the first mask pattern is greater than the lower width of the second mask pattern, and the lower width of the first mask pattern is less than the lower width of the second mask pattern.

Description

Technical Field

[0001] The present invention relates to a mask for forming OLED pixels, a mask support template, and a frame-integrated mask. More specifically, it relates to a mask for forming OLED pixels, a mask support template, and a frame-integrated mask that can accurately control the size and position of the mask pattern. Background Art

[0002] As a technique for forming pixels in the OLED (organic light-emitting diode) manufacturing process, the FMM (Fine Metal Mask) method is mainly used. In this method, a thin-film metal mask (Shadow Mask) is closely attached to a substrate and an organic substance is deposited at a desired position.

[0003] In the existing mask manufacturing method, a thin metal sheet to be used as a mask is prepared. After PR coating on the thin metal sheet, patterning is performed or PR coating is performed to have a pattern, and then an etched mask with a pattern is manufactured. However, in order to prevent the Shadow Effect, it is difficult to form a tapered mask pattern obliquely, and additional processes need to be performed, resulting in an increase in process time and cost and a decrease in productivity.

[0004] In ultra-high-definition OLEDs, the existing QHD image quality is 500 - 600 PPI (pixels per inch), and the size of the pixels reaches about 30 - 50 μm, while 4K UHD and 8K UHD high-definition images have higher resolutions such as -860 PPI and -1600 PPI. Therefore, there is an urgent need to develop a technology that can accurately adjust the size of the mask pattern.

[0005] In addition, in the existing OLED manufacturing process, after the mask is manufactured into a strip shape, a plate shape, etc., the mask is welded and fixed to the OLED pixel deposition frame and used. To manufacture a large-area OLED, multiple masks can be fixed to the OLED pixel deposition frame. During the process of fixing to the frame, each mask is stretched to make it flat. When multiple masks are fixed to one frame, there are still problems with poor alignment between the masks and between the mask units. In addition, during the process of welding and fixing the mask to the frame, the thickness of the mask film is too thin and the area is large, so there are problems such as the mask sagging or twisting due to the load.

[0006] Thus, considering the pixel size of ultra-high-definition OLEDs, the alignment error between units needs to be reduced to about several micrometers. Exceeding this error will result in product defects, so the yield may be extremely low. Therefore, it is necessary to develop technologies that can prevent deformation such as sagging or twisting of the mask and enable precise alignment, as well as technologies for fixing the mask to the frame. Summary of the Invention

[0007] Technical problem

[0008] Therefore, the present invention is proposed to solve the above-mentioned various problems existing in the prior art, and aims to provide a mask for forming an OLED pixel, a mask support template, and a frame-integrated mask that can accurately control the size of the mask pattern.

[0009] Technical solution

[0010] The object of the present invention is achieved by a mask for forming an OLED pixel having a plurality of mask patterns. The mask patterns include a first mask pattern in the upper part and a second mask pattern in the lower part. The thickness of the first mask pattern is greater than that of the second mask pattern. Both side surfaces of the first mask pattern have a concave curvature. The upper width of the first mask pattern is greater than the lower width of the second mask pattern. The lower width of the first mask pattern is less than the lower width of the second mask pattern.

[0011] Convex curvatures may be formed on both side surfaces of the second mask pattern.

[0012] The sum of the shapes of the first mask pattern and the second mask pattern may generally present a conical or inverted conical shape.

[0013] The angle formed by the virtual straight line connecting the upper corner of the first mask pattern to the lower corner of the first mask pattern and the lower surface of the mask may be less than 60° and greater than 0.

[0014] The lower width of the first mask pattern may be greater than 15.4 μm and less than 35 μm.

[0015] The thickness of the mask may be 5 μm to 20 μm.

[0016] In addition, the above object of the present invention can be achieved by a template for supporting a mask for forming an OLED pixel, which includes: a template; a temporary bonding part formed on the template; and a mask bonded to the template by sandwiching the temporary bonding part and having a plurality of mask patterns. The mask patterns include a first mask pattern in the upper part and a second mask pattern in the lower part. The thickness of the first mask pattern is greater than that of the second mask pattern. Both side surfaces of the first mask pattern have a concave curvature. The upper width of the first mask pattern is greater than the lower width of the second mask pattern. The lower width of the first mask pattern is less than the lower width of the second mask pattern.

[0017] A partition insulation part is also formed on the temporary bonding part, and the mask can be bonded to the upper surface of the template by sandwiching the temporary bonding part and the partition insulation part.

[0018] Convex curvatures may be formed on both side surfaces of the second mask pattern.

[0019] The first mask pattern and the second mask pattern are formed by wet etching. When wet etching the second mask pattern, the etching solution etches along the side direction at the exposed portion of the partition insulating portion, so that the lower width of the second mask pattern is greater than the upper width.

[0020] In addition, the above object of the present invention can be achieved by a frame-integrated mask formed by integrating a plurality of masks and a frame for supporting the masks. The frame includes an edge frame portion having a hollow region; a mask unit sheet portion having a plurality of mask unit regions and connected to the edge frame portion. Each mask on which a plurality of mask patterns are formed is connected to the upper portion of the mask unit sheet portion. The mask patterns include a first mask pattern at the upper portion and a second mask pattern at the lower portion. The thickness of the first mask pattern is greater than the thickness of the second mask pattern. Both side surfaces of the first mask pattern have a concave curvature. The upper width of the first mask pattern is greater than the lower width of the second mask pattern, and the lower width of the first mask pattern is less than the lower width of the second mask pattern.

[0021] Advantageous Effects

[0022] According to the present invention having the above structure, the size and position of the mask pattern can be accurately controlled. Description of the Drawings

[0023] Figure 1 is a schematic diagram of an existing process of attaching a mask to a frame.

[0024] Figure 2 is a front view and a side sectional view of a frame-integrated mask according to an embodiment of the present invention.

[0025] Figure 3 is a schematic diagram of a mask according to an embodiment of the present invention.

[0026] Figure 4 is a schematic diagram of a process of forming a mask by bonding a mask metal film to a template to manufacture a mask support template according to an embodiment of the present invention.

[0027] Figure 5 is a schematic diagram of the etching degree of a mask according to an existing mask manufacturing process and a comparative example.

[0028] Figures 6 to 7 is a schematic diagram of a manufacturing process of a mask according to an embodiment of the present invention.

[0029] Figure 8 is a schematic diagram of the etching degree of a mask metal film according to an embodiment of the present invention.

[0030] Figure 9 is a schematic diagram of a manufacturing process of a mask support template according to an embodiment of the present invention.

[0031] Figure 10 Schematic diagram of the etching pattern of the mask metal film according to the comparative example and an embodiment of the present invention.

[0032] Figure 11 Schematic diagram of the mask metal film according to an embodiment of the present invention.

[0033] Figure 12 Graph showing the relationship between the holes and the opening ratio according to the experimental example of the present invention.

[0034] Figure 13 Immediately following Figure 11 Schematic diagram of the mask manufacturing process.

[0035] Figure 14 Schematic diagram of the formation principle of the mask pattern according to an embodiment of the present invention.

[0036] Figure 15 Schematic diagram of the mask according to an embodiment of the present invention.

[0037] Figures 16 to 18 SEM photograph of the mask according to an experimental example of the present invention.

[0038] Figure 19 Schematic diagram of the state where the template is loaded onto the frame so that the mask corresponds to the unit area of the frame according to an embodiment of the present invention.

[0039] Figure 20 Schematic diagram of the process of separating the mask and the template after attaching the mask to the frame according to an embodiment of the present invention.

[0040] Figure 21 Schematic diagram of the state where the mask is attached to the unit area of the frame and the insulating portion is removed according to an embodiment of the present invention.

[0041] Reference numerals:

[0042] 23: Partition insulating portion

[0043] 25: Insulating portion

[0044] 50: Template

[0045] 55: Temporary bonding portion

[0046] 100: Mask

[0047] 110: Mask metal film

[0048] 200: Frame

[0049] C: Unit, mask unit

[0050] CR: Mask unit area

[0051] M1, M2, M3: The first insulating portion, the second insulating portion, and the third insulating portion

[0052] P: Mask pattern

[0053] P1, P1-1, P1-2: The first mask pattern

[0054] P2, P2-1, P2-2: The second mask pattern

[0055] SN: Hole

[0056] WE1, WE2, WE3: Wet etching Detailed implementation mode

[0057] For the following detailed description of the present invention, reference may be made to the accompanying drawings which illustrate specific embodiments in which the present invention can be implemented. In order to enable those skilled in the art to implement the present invention, these embodiments will be specifically described below. These embodiments are described in sufficient detail so that those with ordinary knowledge in the relevant technical field can implement the present invention. The various embodiments of the present invention should be understood as being different from each other but not mutually exclusive. For example, the specific shapes, structures, and characteristics described herein can be implemented as other embodiments without departing from the spirit and scope of the present invention. In addition, the position or arrangement of the individual components in each of the disclosed embodiments should be understood as being changeable without departing from the spirit and scope of the present invention. Therefore, the following detailed description is not intended to limit the present invention, and the scope of the present invention is only defined by the appended claims and all scopes equivalent thereto as long as it can be appropriately described. Similar reference numerals in the drawings refer to the same or similar functions in various aspects, and for convenience, the lengths, areas, thicknesses, etc. and their forms may also be exaggeratedly represented.

[0058] Next, in order to enable those skilled in the art to easily implement the present invention, the preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0059] Figure 1 It is a schematic diagram of the process of attaching the mask 10 to the frame 20 in the prior art.

[0060] The existing mask 10 is of the stick-type or plate-type. Figure 1 The stick-type mask 10 can be welded and fixed to the OLED pixel deposition frame on both sides of the stick and used. The body of the mask 10 (or the mask film 11) has a plurality of display units C. One unit C corresponds to one display of a smartphone or the like. Pixel patterns P are formed in the unit C to correspond to the respective pixels of the display.

[0061] Refer to Figure 1(a), a tensile force F1 - F2 is applied along the long axis direction of the strip mask 10, and the strip mask 10 is loaded on the square-shaped frame 20 in an unfolded state. The size of the frame 20 may be sufficient to accommodate the cells C1 - C6 of one strip mask 10 within the inner blank area of the frame, or may be sufficient to accommodate the cells C1 - C6 of multiple strip masks 10 within the inner blank area of the frame.

[0062] Referring to Figure 1 (b), while finely adjusting the tensile forces F1 - F2 applied to each side of the strip mask 10, alignment is performed. After that, a part of the side surface of the strip mask 10 is welded by W to connect the strip mask 10 and the frame 20 to each other. Figure 1 (c) shows a side cross-section of the connected strip mask 10 and the frame.

[0063] Despite finely adjusting the tensile forces F1 - F2 applied to each side of the strip mask 10, there is still a problem that the alignment between the mask cells C1 - C3 is not good. For example, the distances between the patterns P of the cells C1 - C6 are different from each other or the pattern P is skewed. Since the strip mask 10 has a large area including multiple cells C1 - C6 and has a very thin thickness of several tens of μm, it is prone to sagging or distortion due to the load. In addition, it is a very difficult operation to adjust the tensile forces F1 - F2 to make all the cells C1 - C6 flat and simultaneously confirm the alignment state between the cells C1 - C6 in real time through a microscope. However, in order to avoid the mask pattern P with a size of several μm to several tens of μm having an adverse effect on the pixel process of the ultra-high-definition OLED, the alignment error is preferably not more than 3 μm. The alignment error between such adjacent cells is referred to as the pixel position accuracy (PPA).

[0064] Furthermore, connecting each strip mask 10 to a single frame 20 while precisely aligning the alignment states between multiple strip masks 10 and between the multiple cells C1 - C6 of the strip mask 10 is a very difficult operation, and it only increases the process time based on alignment, thus becoming an important reason for reducing production efficiency.

[0065] In addition, after connecting and fixing the strip mask 10 to the frame 20, the tensile forces F1 - F2 applied to the strip mask 10 act on the frame 20 in the opposite direction as tension. This tension causes the frame 20 to deform slightly, and there is a problem that the alignment state between the multiple cells C1 - C6 is distorted.

[0066] In view of this, the present invention proposes a frame 200 and a frame-integrated mask that can form an integrated structure with the mask 100. The mask 100 integrated with the frame 200 can not only prevent deformations such as sagging or distortion, but also be accurately aligned with the frame 200.

[0067] Figure 2 is a front view of a frame-integrated mask according to an embodiment of the present invention Figure 2 in (a)] and a side sectional view Figure 2 in (b)].

[0068] Hereinafter, although the configuration of the frame-integrated mask is described in this specification, the structure and manufacturing process of the frame-integrated mask can be understood to include all the contents of Korean Patent Application No. 2018-0016186.

[0069] Referring to Figure 2 , the frame-integrated mask may include a plurality of masks 100 and one frame 200. In other words, it is a form in which a plurality of masks 100 are respectively attached to the frame 200. Hereinafter, for the sake of convenience of explanation, a mask 100 having a rectangular shape is taken as an example for explanation. However, before the mask 100 is attached to the frame 200, it may be in the shape of a strip mask having protrusions for clamping on both sides, and the protrusions may be removed after being attached to the frame 200.

[0070] A plurality of mask patterns P are formed on each mask 100, and one mask 100 may form one unit C. One mask unit C may correspond to one display such as a smartphone.

[0071] The mask 100 may also be made of materials such as invar, super invar, nickel (Ni), nickel-cobalt (Ni-Co), etc. The mask 100 may use a metal sheet generated by a rolling process or an electroforming process.

[0072] The frame 200 may be formed in a form of attaching a plurality of masks 100. Considering thermal deformation, the frame 200 is preferably formed of materials such as invar, super invar, nickel, nickel-cobalt, etc. having the same coefficient of thermal expansion as the mask. The frame 200 may include an edge frame portion 210 having a substantially rectangular shape and a box shape. The inside of the edge frame portion 210 may be a hollow shape.

[0073] In addition, the frame 200 has a plurality of mask unit regions CR, and may include a mask unit sheet portion 220 connected to the edge frame portion 210. The mask unit sheet portion 220 may be composed of an edge sheet portion 221, a first grid sheet portion 223, and a second grid sheet portion 225. The edge sheet portion 221, the first grid sheet portion 223, and the second grid sheet portion 225 refer to respective portions divided on the same sheet, and they are integrally formed with each other.

[0074] The thickness of the edge frame portion 210 can be greater than the thickness of the mask unit sheet portion 220 and can be formed with a thickness of several millimeters to several centimeters. Although the thickness of the mask unit sheet portion 220 is thinner than that of the edge frame portion 210, it is thicker than the mask 100, and the thickness can be about 0.1 mm to 1 mm. The widths of the first grid sheet portion 223 and the second grid sheet portion 225 can be about 1 - 5 mm.

[0075] In the planar sheet, except for the regions occupied by the edge sheet portion 221, the first grid sheet portion 223, and the second grid sheet portion 225, a plurality of mask unit regions CR (CR11 - CR56) can be provided.

[0076] The mask 200 has a plurality of mask unit regions CR, and each mask 100 can be attached in such a manner that each mask unit C corresponds to each mask unit region CR respectively. The mask unit C corresponds to the mask unit region CR of the frame 200, and a part or all of the dummy portion can be attached to the frame 200 (mask unit sheet portion 220). Thus, the mask 100 and the frame 200 can form an integral structure.

[0077] Figure 3 It is a schematic diagram of the mask 100 according to an embodiment of the present invention.

[0078] The mask 100 can include a mask unit C formed with a plurality of mask patterns P and a dummy portion DM around the mask unit C. The mask 100 can be manufactured using a metal sheet generated by a rolling process, electroforming, etc., and one unit C can be formed in the mask 100. The dummy portion DM corresponds to the portion of the mask film 110 [mask metal film 110] other than the unit C and can include only the mask film 110 or can include the mask film 110 formed with a predetermined dummy portion pattern having a similar shape to the mask pattern P. The dummy portion DM corresponds to the edge of the mask 100 and a part or all of the dummy portion DM can be attached to the frame 200 (mask unit sheet portion 220).

[0079] The width of the mask pattern P can be less than 40 μm, and the thickness of the mask 100 can be about 5 - 20 μm. Since the frame 200 has a plurality of mask unit regions CR (CR11 - CR56), it can also have a plurality of masks 100 each including a mask unit C (C11 - 56) corresponding to each mask unit region CR (CR11 - CR56) respectively. In addition, a plurality of templates 50 can be provided for supporting the plurality of masks 100 described later.

[0080] Figure 4 It is a schematic diagram of a process for manufacturing a mask support template by forming the mask 100 by bonding a mask metal film 110 on a template 50 according to an embodiment of the present invention.

[0081] Refer toFigure 4 As shown in (a), a template 50 can be provided. The template 50 is a medium on which a mask 100 is attached on one side and the mask 100 is moved in a state of supporting the mask 100. The central portion 50a can correspond to the mask unit C of the mask metal film 110, and the edge portion 50b can correspond to the dummy portion DM of the mask metal film 110. In order to be able to support the mask metal film 110 as a whole, the template 50 is a flat plate shape with an area greater than or equal to that of the mask metal film 110.

[0082] The template 50 can be made of materials such as wafers, glass, silica, heat-resistant glass, quartz, alumina (Al2O3), borosilicate glass, zirconia, etc. As an example, the template 50 can use a material in borosilicate glass that has excellent heat resistance, chemical resistance, mechanical strength, transparency, etc. In addition, The coefficient of thermal expansion of which is about 3.3, and the difference in the coefficient of thermal expansion from the invar alloy mask metal film 110 is not large, having the advantage of being convenient for controlling the mask metal film 110.

[0083] In order for the laser L irradiated from the upper part of the template 50 to reach the welding part WP (the area where welding is performed) of the mask 100, laser through holes 51 can be formed on the template 50. The laser through holes 51 can be formed on the template 50 in a manner corresponding to the position and number of the welding part WP. Since a plurality of welding parts WP are arranged at a predetermined interval on the edge or the dummy portion DM of the mask 100, correspondingly, a plurality of laser through holes 51 can also be formed at a predetermined interval. As an example, since a plurality of welding parts WP are arranged at a predetermined interval on the dummy portion DM on both sides (left / right) of the mask 100, the laser through holes 51 can also be formed at a predetermined interval on both sides (left / right) of the template 50.

[0084] The position and number of the laser through holes 51 do not necessarily have to correspond to the position and number of the welding part WP. For example, laser L can also be irradiated only on some of the laser through holes 51 for welding. In addition, some of the laser through holes 51 that do not correspond to the welding part WP can also be used as alignment marks when aligning the mask 100 and the template 50. If the material of the template 50 is transparent to the laser L, the laser through holes 51 may not be formed.

[0085] A temporary bonding portion 55 can be formed on one side of the template 50. Before the mask 100 is attached to the frame 200, the temporary bonding portion 55 can temporarily attach the mask 100 (or the mask metal film 110') to one side of the template 50 and support it on the template 50.

[0086] The temporary bonding portion 55 can use an adhesive or adhesive sheet separable based on heating, and an adhesive or adhesive sheet separable based on UV irradiation.

[0087] As an example, the temporary bonding portion 55 can use liquid wax. The liquid wax can use the same wax as that used in the polishing step of the semiconductor wafer, etc., and its type is not particularly limited. As a resin component mainly used to control and maintain the adhesive force, impact resistance, etc., the liquid wax can include substances and solvents such as acrylic acid, vinyl acetate, nylon, and various polymers. As an example, the temporary bonding portion 55 can use acrylonitrile-butadiene rubber (ABR) as the resin component and SKYLIQUID ABR-4016 containing n-propanol as the solvent component. The liquid wax can be formed on the temporary bonding portion 55 by a spin coating method.

[0088] The temporary bonding portion 55 of the liquid wax has a decreased viscosity at a temperature higher than 85°C - 100°C, and an increased viscosity at a temperature lower than 85°C, and a part is cured into a solid, so that the mask metal film 110' and the template 50 can be fixedly bonded.

[0089] Next, referring to Figure 4 (b), the mask metal film 110 can be bonded to the template 50. The liquid wax can be heated to above 85°C, and the mask metal film 110 is brought into contact with the template 50, and then the mask metal film 110 and the template 50 are passed between rollers for bonding.

[0090] According to an embodiment, baking of the template 50 is performed at about 120°C for 60 seconds, so that after the solvent of the temporary bonding portion 55 is vaporized, the mask metal film lamination process can be immediately performed. Lamination is performed by loading the mask metal film 110 on the template 50 having the temporary bonding portion 55 formed on one side and passing it between an upper roller at about 100°C and a lower roller at about 0°C. As a result, the mask metal film 110 can be in contact with the template 50 by sandwiching the temporary bonding portion 55.

[0091] As another example, the temporary bonding portion 55 can use a thermal release tape. The thermal release tape can be in a form in which a core film such as a PET film is arranged in the middle, thermal release adhesives are arranged on both sides of the core film, and a release film is arranged on the outer contour of the adhesive layer. Here, the adhesive layers arranged on both sides of the core film can have different peelable temperatures.

[0092] According to one embodiment, in a state where the peeling film / release film is removed, the lower surface of the thermal peeling tape (the lower second adhesive layer of the core film) is adhered to the film 50, and the upper surface of the thermal peeling tape (the upper second adhesive layer of the core film) can be adhered to the mask metal film 110'. Since the peeling temperatures of the first adhesive layer and the second adhesive layer are different from each other, in the following Figure 20 when separating the template 50 from the mask 100, as the peelable heat is applied to the first adhesive layer, the mask 100 can be separated from the template 50 and the temporary adhesion part 55.

[0093] In addition, the mask metal film 110 can be a mask metal film that has been processed by a surface defect removal process and a thickness reduction process on one or both sides. The thickness of the mask metal film 110 can be about 5 μm to 20 μm. Also, the surface defect removal process and the thickness reduction process can be performed after adhering the mask metal film 110 to the template 50. In addition, the thickness reduction process can be performed only on the mask unit C part. After a surface defect removal process such as CMP, an insulating part (not shown) such as a photoresist is formed only in the region corresponding to the welding part WP of the mask metal film, or in a state where the mask metal film 110 is adhered and supported on the template 50, after an insulating part (not shown) such as a photoresist is formed only in the region corresponding to the welding part WP of the mask metal film 110, an etching process for reducing the thickness is performed on the mask unit C part, so that the welding part WP is formed thicker and has a step difference from the mask unit C, and at the same time, the surface of the mask unit C part for forming the mask pattern P can be formed in a defect-free state.

[0094] Then, referring to Figure 4 (c) of, a patterned insulating part 25 can be formed on the mask metal film 110. The insulating part 25 can be formed of a photoresist material by a printing method or the like.

[0095] Next, the mask metal film 110 can be etched. Methods such as dry etching and wet etching can be used, and there is no particular limitation thereto. As a result of the etching, the part of the mask metal film 110 exposed at the empty position 26 between the insulating parts 25 is etched. The etched part of the mask metal film 110 constitutes the mask pattern P, and thus a mask 100 having a plurality of mask patterns P formed thereon can be manufactured.

[0096] Then, referring to Figure 4 (d) of, the manufacturing of the template 50 for supporting the mask 100 can be completed by removing the insulating part 25.

[0097] Next, the process of manufacturing the mask 100 by forming the mask pattern P on the mask metal film 110 will be described.

[0098] Figure 5It is a schematic diagram of the etching degree (d) of the existing mask manufacturing process [(a) to (c)] and the mask of the comparative example.

[0099] Refer to Figure 5 , only wet etching is performed in the existing mask manufacturing process.

[0100] First, as shown in (a) of Figure 5 , a patterned photoresist M can be formed on the planar film 110'. Then, as shown in (b) of Figure 5 , wet etching WE can be performed through the space between the patterned photoresists M. After performing the wet etching WE, a part of the space of the film 110' is penetrated, and thus a mask pattern P' can be formed. Then, if the photoresist M is cleaned, the manufacturing of the film 110' with the mask pattern P' formed thereon, that is, the mask 100', can be completed.

[0101] As shown in (c) of Figure 5 , the existing mask 100' has a problem that the sizes of the mask patterns P' are not necessarily the same. Since the wet etching WE is isotropic, the etched morphology generally presents an arc shape. Moreover, since it is difficult to keep the etching speed of each part consistent during the wet etching WE process, the widths R1', R1", R1"' of the through patterns after penetrating the film 110' can only be different from each other. In particular, in the patterns where undercut UC frequently occurs, not only the lower width R1" of the mask pattern P' is formed wider, but also the upper width R2" is formed wider, while in the patterns where undercut UC occurs less frequently, the lower widths R1', R1"' and the upper widths R2', R2"' are relatively formed narrower.

[0102] As a result, the existing mask 100' has a problem that the sizes of the individual mask patterns P' are not uniform. For ultra-high-definition OLEDs, currently the QHD picture quality is 500 - 600 PPI, and the size of the pixels reaches about 30 - 50 μm, while the 4K UHD and 8K UHD high picture qualities have higher resolutions such as -860 PPI, -1600 PPI, etc., so even a slight size difference may cause product defects.

[0103] Refer to Figure 5In (d), since the wet etching WE is isotropic, the etched morphology is approximately circular. In addition, during the wet etching process, it is difficult for the etching rate of each part to be exactly the same. If the mask metal film 110 is penetrated by only one wet etching to form a mask pattern, the deviation will be greater. For example, although the wet etching rates of the mask pattern 111 and the mask pattern 112 are different, the difference in the upper width (undercut) is not very large. However, the difference between the lower width PD1 of the mask metal film 110 penetrated by forming the mask pattern 111 and the lower width PD2 of the mask metal film 110 penetrated by forming the mask pattern 112 is much larger than the difference in the upper width. This is the result of the isotropic wet etching. In other words, the width that determines the pixel size is the lower width PD1 and PD2 of the mask patterns 111 and 112, rather than the upper width. Therefore, a scheme of controlling the lower widths PD1 and PD2 by using a wet etching method different from the one-time wet etching can be considered.

[0104] Therefore, according to one aspect of the present invention, the accuracy of the mask pattern during the wet etching process can be improved by multiple wet etchings.

[0105] Figures 6 to 7 It is a schematic diagram of the manufacturing process of a mask according to an embodiment of the present invention.

[0106] Referring to Figure 6 In (a), first, a mask metal film 110 as a metal sheet can be provided. The mask metal film 110 can be generated by a rolling process, electroforming, etc. The material of the mask metal film 110 can be invar, super invar, nickel (Ni), nickel-cobalt (Ni-Co), etc.

[0107] Then, a patterned second-1 insulating portion M1 can be formed on one side (upper surface) of the mask metal film 110. The second-1 insulating portion M1 can be formed of a photoresist material by a printing method, etc. It should be noted that Figures 6 to 7 The insulating portions M1, M2, and M3 as the insulating portions for forming the mask pattern P correspond to the insulating portion 25 described later and are different from the partition insulating portion 23.

[0108] The first insulating portion M1 can be a black matrix photoresist or a photoresist material with a metal coating formed on the upper part. In addition, the material of the first insulating portion M1 can be a photoresist material different from the second insulating portion M2 or the third insulating portion M3 described later, and is preferably an epoxy resin-based photoresist material. The black matrix photoresist can be a material containing a resin black matrix, and the resin black matrix is used to form the black matrix of the display panel. The light-shielding effect of the black matrix photoresist is better than that of a general photoresist. In addition, the photoresist with a metal coating formed on the upper part also has a good light-shielding effect of blocking the light irradiated from the upper part through the metal coating. The first insulating portion M1 can be a positive type photoresist material.

[0109] Then, referring to Figure 6 (b) of, a first mask pattern P1' with a predetermined depth can be formed on one side (upper surface) of the mask metal film 110 by wet etching WE1. Although the first mask pattern P1' is formed in an approximately arc shape without penetrating the mask metal film 110, in the present invention described according to Figure 11 , the first mask pattern (corresponding to the main etching pattern P1-2) is characterized by including a hole SN. For the sake of convenience of explanation, the hole part is excluded when explaining Figure 6 . That is, the depth value of the first mask pattern P1' excluding the hole SN can be smaller than the thickness of the mask metal film 110.

[0110] Due to the isotropic etching characteristics of the wet etching WE1, the width R2 of the first mask pattern P1 is different from the pitch R3 between the patterns of the first insulating portion M1, and can have a width wider than the pitch R3 between the patterns of the first insulating portion M1. In other words, since an undercut UC is formed at the lower parts on both sides of the first insulating portion M1, the width R2 of the first mask pattern P1' can be wider than the pitch R3 between the patterns of the first insulating portion M1 by the width of the formed undercut UC.

[0111] Then, referring to Figure 6 (c) of, a second insulating portion M2 can be formed on one side (upper surface) of the mask metal film 110. The second insulating portion M2 can be formed of a photoresist material by a printing method or the like. For the second insulating portion M2, since it needs to be retained in the space for forming the undercut UC described later, it is preferably a positive type photoresist material.

[0112] Since the second insulating portion M2 is formed on one side (upper surface) of the mask metal film 110, a part of it is formed on the first insulating portion M1, and the other part is filled into the first mask pattern P1.

[0113] The second insulating portion M2 can use photoresist diluted in a solvent. If a high-concentration photoresist solution is formed on the mask metal film 110 and the first insulating portion M1, the high-concentration photoresist solution may react with the photoresist of the first insulating portion M1, and thus it is possible to dissolve a part of the first insulating portion M1. Therefore, in order not to affect the first insulating portion M1, the second insulating portion M2 can use photoresist with a reduced concentration by dilution in a solvent.

[0114] Then, referring to Figure 7 (d), a part of the second insulating portion M2 can be removed. As an example, a part of the second insulating portion M2 can be removed in the form of volatilization by baking. After the solvent of the second insulating portion M2 is volatilized by the baking process, only the photoresist component remains. Therefore, a thinner portion, such as a coated film, remains on the exposed portion of the first mask pattern P1 and the surface of the first insulating portion M1 of the second insulating portion M2'. The thickness of the remaining second insulating portion M2' is preferably less than about several μm so as not to affect the pattern width R3 of the first insulating portion M1 or the pattern width R2 of the first mask pattern P1.

[0115] Then, referring to Figure 7 (e), exposure L can be performed on one side (upper surface) of the mask metal film 110. When exposure L is performed on the upper portion of the first insulating portion M1, the first insulating portion M1 can act as an exposure mask. Since the first insulating portion M1 is a black matrix photoresist or a photoresist material with a metal coating film formed on the upper portion, the light-shielding effect is excellent. Therefore, the second insulating portion M2" located vertically below the first insulating portion M1 [refer to Figure 7 (f)] will not be exposed to exposure L, while the other second insulating portion M2' will be exposed to exposure L.

[0116] Then, referring to Figure 7 (f), if development is performed after exposure L, the portion of the second insulating portion M2" that has not been exposed to exposure L will remain, while the other second insulating portion M2' will be removed. Since the second insulating portion M2' is a positive photoresist, the portion exposed to exposure L will be removed. The space where the second insulating portion M2" remains can correspond to the space where undercuts UC [refer to Figure 6 (b) step] are formed on both lower sides of the first insulating portion M1.

[0117] Then, referring to Figure 7In (g), wet etching WE2 can be performed on the first mask pattern P1 of the mask metal film 110. The wet etching solution can penetrate into the space between the patterns of the first insulating portion M1 and the space of the first mask pattern P1, thereby performing wet etching WE2. The second mask pattern P2 can be formed through the mask metal film 110. That is, it is formed by penetrating the other side of the mask metal film 110 from the lower end of the first mask pattern P1.

[0118] At this time, the second insulating portion M2" remains on the first mask pattern P1. The remaining second insulating portion M2" can act as a mask for wet etching. That is, the second insulating portion M2" masks the etching solution and prevents the etching solution from etching in the lateral direction of the first mask pattern P1, but etches in the direction of the lower surface of the first mask pattern P1.

[0119] Since the second insulating portion M2" is disposed in the undercut UC space vertically below the first insulating portion M1, the pattern width of the second insulating portion M2" substantially corresponds to the pattern width R3 of the first insulating portion M1. Thus, the second mask pattern P2 corresponds to performing wet etching WE2 on the pitch R3 between the patterns of the first insulating portion M1. Therefore, the width R1 of the second mask pattern P2 can be smaller than the width R2 of the first mask pattern P1.

[0120] Since the width of the second mask pattern P2 defines the width of the pixel, the width of the second mask pattern P2 is preferably less than 35 μm. If the thickness of the second mask pattern P2 is too thick, it is difficult to control the width R1 of the second mask pattern P2, and the uniformity of the width R1 decreases, and the overall shape of the mask pattern P may not be conical / inverted conical. Therefore, the thickness of the second mask pattern P2 is preferably less than the thickness of the first mask pattern P1. The thickness of the second mask pattern P2 is preferably close to 0. When considering the size of the pixel, for example, the thickness of the second mask pattern P2 is preferably about 0.5 to 3.0 μm, more preferably 0.5 to 2.0 μm.

[0121] The sum of the shapes of the connected first mask pattern P1 and the second mask pattern P2 can form the mask pattern P.

[0122] Then, referring to Figure 7 In (h), the manufacturing of the mask 100 can be completed by removing the first insulating portion M1 and the second insulating portion M2". The first mask patterns P1, P2 include inclined surfaces, and the height of the second mask pattern P2 is very low. Therefore, if the shapes of the first mask pattern P1 and the second mask pattern P2 are added together, it presents a conical or inverted conical shape as a whole.

[0123] In addition, between steps (b) and (c) in Figure 6 steps (b2) and (b3) can also be performed.

[0124] Referring to Figure 6 of (b2), a third insulating portion M3 may be formed in the first mask pattern P1'. The third insulating portion M3 may be formed on at least a part of the first mask pattern P1' exposed between the first insulating portions M1. For example, within the interval between the patterns of a pair of adjacent first insulating portions M1, that is, on the first mask pattern P1', a third insulating portion M3 having a width R3 may be formed.

[0125] For ease of exposure, the third insulating portion M3 preferably uses a negative type photoresist material. When the negative type photoresist is filled in the first mask pattern P1' and the upper part is exposed, the first insulating portion M1 functions as an exposure mask with respect to the third insulating portion M3, and only the third insulating portion M3 exposed between the patterns of the first insulating portion M1 remains. At this time, as shown in (c) of Figure 6 , a third edge portion M3 having a width R3 may be formed on the first mask pattern P1'.

[0126] Then, referring to (b3) of Figure 6 , the first mask pattern P1' may be further wet-etched by WE2. Since a part of the first mask pattern P1' is in a state where the third insulating portion M3 is formed, the first mask pattern P1' is not further etched downward but is etched laterally. Therefore, the width of the first mask pattern P1' may be greater than R2 (P1' -> P1).

[0127] Execute Figure 6 The specific reasons for steps (b2) and (b3) are as follows.

[0128] If steps (b2) and (b3) of Figure 6 are omitted and the first mask pattern P2 is formed after the first mask pattern P1' is formed, it will be difficult to reduce the taper angle of the mask patterns P' (P1', P2). Based on the characteristics of the isotropic etching process of the first mask pattern P1', it is difficult for the side surface to have a small angle (the angle formed by the horizontal plane and the side of the mask pattern). Since the angle exceeds 60° or is close to vertical, there is still a case where the angle exceeds 70° even after two wet etchings. Overall, when the angle formed by the side surface of the mask pattern P and the horizontal plane is only about 30° to 70°, the shadow effect can be prevented. If the angle exceeds the above range, the shadow effect will still be generated, resulting in difficulty in uniformly forming OLED pixels.

[0129] In addition, in order to form the surface of the mask pattern P without roughness and uniformly, the wet etching process needs to be performed in a short time. However, if the wet etching process is performed in a short time, it is difficult to form a small angle on the side surface angle of the first mask pattern P1'. Eventually, if the time of the wet etching process is extended to form a small angle on the side surface angle of the first mask pattern P1', there will be problems such as roughness on the surface of the mask pattern and non-uniform morphology.

[0130] Therefore, a third insulating part M3 is further formed in the first mask pattern P1' to prevent the lower part of the first mask pattern P1' from being etched. As the wet etching WE3 (P1'->P1) is further performed in the side direction of the first mask pattern P1', it has the effect of reducing the angle (a1->a2) formed by the side surface of the first mask pattern P1 and the horizontal plane. Since the wet etching is performed in two steps to form the first mask pattern P1, each etching process does not need to last for a long time, so that the surface morphology of the mask pattern P can also be formed uniformly.

[0131] After further performing the wet etching WE3 and forming the first mask pattern P1 with a reduced angle a2 formed by the side surface and the horizontal plane, the third insulating part M3 can be removed.

[0132] Figure 8 It is a schematic diagram of the mask metal film 110 according to an embodiment of the present invention.

[0133] Figure 8 The process up to (a) of Figure 6 is the same as the process described in (a) to (b) of Figure 8 However, in (a) of

[0134] a comparison is made between the first mask pattern P1-1 and the first mask pattern P1-2 with different etching degrees in the wet etching WE1 of the first insulating part M1. Figure 8 Referring to (a) of

[0135] even for the same wet etching WE1-1 and WE1-2, different etching degrees will occur depending on the etched part, as shown by the first mask pattern P1-1 and the first mask pattern P1-2. The pattern width R2-1 of the first mask pattern P1-1 is smaller than the pattern width R2-2 of the first mask pattern P1-2, and this difference in the pattern widths R2-1 and R2-2 will have an adverse effect on the resolution of the pixel. Figure 8 Then, referring to (b) of Figure 6 it can be confirmed that after performing Figure 7After the process described in (f), the second insulating portions M2"-1 and M2"-2 can be respectively formed in the vertical lower space of the first insulating portion M1. Depending on the size of the undercut space at the lower part of the first insulating portion M1, the formed sizes of the respective second insulating portions M2"-1 and M2"-2 will be different. Although the size of the second insulating portion M2"-1 is smaller than that of the second insulating portion M2"-2, the pattern widths of the second insulating portions M2"-1 and M2"-2 will be the same. The pattern widths R3 of the respective second insulating portions M2"-1 and M2"-2 can be the same to correspond to the pattern width R3 of the first insulating portion M1.

[0136] Then, referring to Figure 8 (c), the second insulating portions M2"-1 and M2"-2 are respectively used as masks for wet etching and wet etching WE2 is performed, so that the mask metal film 110 can be penetrated. As a result, the deviation of the widths R1-1 and R1-2 of the formed second mask patterns P2-1 and P2-2 will be significantly smaller than the deviation of the widths R2-1 and R2-2 of the first mask patterns P1-1 and P1-2. This is because after the first wet etching of the mask metal film 110 to the depth of the first mask patterns P1-1 and P1-2, the remaining thickness of the mask metal film 110 is subjected to the second wet etching, and at the same time, the pattern widths of the second insulating portions M2"-1 and M2"-2 for the second wet etching are substantially the same as the pattern width of the first insulating portion M1 for the first wet etching.

[0137] As described above, the mask manufacturing method of the present invention has the effect of forming a mask pattern P of a required size by performing multiple wet etchings. Specifically, as part of the second insulating portion M2" is retained, the wet etching WE2 for forming the second mask pattern P2 will be performed at a thinner width and a thinner thickness compared to the wet etchings WE1 and WE2 for forming the first mask pattern P1, so it has the advantage of being easy to control the width R1 of the second mask pattern P2. On the other hand, since an inclined surface can be formed by wet etching, a mask pattern P that can prevent the shadow effect can be formed.

[0138] Figure 9 is a schematic diagram of the manufacturing process of a mask support template according to an embodiment of the present invention.

[0139] The present invention can Figures 6 to 7 The process of forming the mask pattern P is performed after bonding the mask metal film 110 to the template 50. Figure 9 The processes of (a), (b), and (c) correspond to Figure 4 the processes of (b), (c), and (d), so the description of the same parts will be omitted.

[0140] Referring to Figure 9(a), the mask metal film 110 can be bonded to the template by sandwiching a temporary bonding portion 55. However, it should be prevented that the etching solution enters the interface between the mask metal film 110 and the temporary bonding portion 55 to damage the temporary bonding portion 55 / template 50, thereby causing an etching error of the mask pattern P. Thus, in a state where the partition insulating portion 23 is formed on one surface of the mask metal film 110, the mask metal film 110 can be bonded to the upper surface of the template 50. That is, the surface of the mask metal film 110 on which the partition insulating portion 23 is formed can be oriented toward the upper surface of the template 50. The mask metal film 110 and the template 50 can be bonded to each other by sandwiching the partition insulating portion 23 and the temporary bonding portion 55.

[0141] The partition insulating portion 23 can be formed on the mask metal film 110 by a printing method or the like using a photoresist material that is not etched by the etching solution. In addition, in order to remain circular after multiple wet etching processes, the partition insulating portion 23 can include at least one of a cured negative photoresist and a negative photoresist containing an epoxy resin. As an example, it is preferable to use an epoxy-based SU-8 photoresist and a black matrix photoresist, so that they are cured together during the baking of the temporary bonding portion 55, the baking of the second insulating portion M2 (refer to Figure 7 (d)), etc.

[0142] Then, referring to Figure 9 (b), a patterned insulating portion 25 can be formed on the mask metal film 110. The insulating portion 25 corresponds to Figure 5 (d)'s insulating portion 25, or can correspond to Figures 6 to 7 's insulating portions M1, M2, and M3.

[0143] Next, the etching of the mask metal film 110 can be performed. The etching method of Figure 4 (d) or the etching method of Figures 6 to 7 can be used to form the mask pattern P.

[0144] Then, referring to Figure 9 (c), the manufacturing of the template 50 for supporting the mask 100 can be completed by removing the insulating portion 25. A mask support template including the mask 100 / partition insulating portion 23 / temporary bonding portion 55 / template 50 can be manufactured.

[0145] Next, the reason for manufacturing the mask support template further including the partition insulating portion 23 will be described in more detail.

[0146] Figure 10 is a schematic diagram of the etching degree of the mask metal film according to a comparative example and an embodiment of the present invention.

[0147] As Figures 6 to 7As shown, it is more advantageous to perform etching only on one side (e.g., the upper side) of the mask metal film 110. If etching is performed on both sides simultaneously, it may cause non-uniform thickness of the mask metal film 110, and it is difficult to obtain the desired shape of the mask pattern P. It is very important to perform wet etching WE on one side and prevent the etching solution from leaking to the other side (e.g., the lower side) of the mask metal film 110 due to multiple wet etchings.

[0148] Figure 10 Fig. (a) is a comparative example in which the mask metal film 110 is bonded to the template 50 by sandwiching a temporary bonding portion 55 in the case of no partition insulating portion 23. As Figure 7 detailed in Fig. (g), since the thickness of the first mask pattern P1 (P1-1, P1-2) is relatively thick and the width of the second mask pattern P2 defines the width of the pixel, the width of the second mask pattern P2 is preferably close to 0 μm.

[0149] Therefore, although the first mask pattern P1 is preferably formed at the maximum depth, even for the same wet etchings WE1-1 and WE1-2, the etching degree varies depending on the etching site, as shown by the first mask pattern P1-1 and the first mask pattern P1-2. As Figure 10 the first mask pattern P1-2' on the right side of Fig. (a), there may be a case where the wet etching WE1-2 forms a hole SN.

[0150] In this case, there may also be a problem that the temporarily exposed lower bonding portion 55 is damaged (55 -> 55') due to the wet etching WE1-2. In addition to the temporary bonding portion 55', the template 50 is also damaged.

[0151] Furthermore, when the etching solution enters between the interface of the damaged temporary bonding portion 55' and the mask metal film 110 during WE1-2', it further etches the lower part of the first mask pattern P1, thereby causing problems such as over-sized pattern formation or local amorphous defects.

[0152] Therefore, in the present invention, by further sandwiching a partition insulating portion 23 between the mask metal film 110 and the temporary bonding portion 55, even if the first mask pattern P1-2 penetrates the mask metal film 110 during the first wet etching WE1 (WE1-1, WE1-2), it is possible to prevent the etching solution from entering the lower surface of the mask metal film 110.

[0153] Since the partition insulating portion 23 includes at least one of a cured negative photoresist, a negative photoresist containing an epoxy resin, and a black matrix photoresist, it can withstand subsequent etching processes such as the first wet etching process WE1, the second wet etching process WE2, and the third wet etching process WE3 without being melted by the etching solution. Thus, even if the first mask pattern P1-2 penetrates the mask metal film 110, the width of the pattern will not be enlarged, and it has the effect of being able to maintain the width corresponding to the second-1 insulating portion M1.

[0154] Figure 11 It is a schematic diagram of a mask metal film according to an embodiment of the present invention. Figure 11 (a) is a plan view, Figure 11 (b) is a side cross-sectional view of (a). It should be noted that, Figure 11 Although the mask pattern P1 formed in a circular shape based on the plane is illustrated, the mask pattern P can be formed in various shapes such as a quadrilateral or a polygon.

[0155] As Figure 10 described above, the first mask pattern P1 (P1-1, P1-2) is preferably formed at the maximum depth, but it is very difficult to achieve only retaining the minimum thickness by accurately controlling the etching speeds of WE1-1 and WE1-2. Therefore, the present invention can perform an etching process WE1-2 such that the first mask pattern P1-2' on the right side of Figure 11 (a) forms a hole SN. Therefore, after the first wet etching WE1 (WE1-1, WE1-2) Figure 6 (b) step] is completed, in the mask metal film 110, at least a part of the plurality of first mask patterns P1 may include a hole SN for penetrating the lower surface of the mask metal film 110. It has the effect that the depth of the first mask pattern P1 can be formed deepest at the time points before and after the hole SN is formed. Even if the hole SN is formed, since the partition insulating portion 23 is formed on the template 50, it is possible to prevent the etching solution from leaking through the hole SN.

[0156] Since the first mask pattern P1 is formed based on the first wet etching, it exhibits an isotropic etching characteristic, so that the width will become narrower from the upper surface to the lower surface of the mask metal film 110, and the side surface may have a concave curvature shape. Since undercuts are formed at the lower parts on both sides of the first insulating portion M1, the upper width of the first mask pattern P1 may be greater than the pitch R3 between the patterns of the first insulating portion. Therefore, the hole SN at the lowermost end of the first mask pattern P1 can be located in the vertical region within the pitch between the first insulating portion M1 and the adjacent first insulating portion M1 (or within the pitch between the patterns of the first insulating portion M1). Considering the lower width of the final mask pattern P, the pitch between the patterns of the first insulating portion M1 can be set to about 20 μm to 30 μm.

[0157] However, if the size of the hole SN becomes too large, during the subsequent process of forming the second insulating portion M2 and performing the second etching WE, there will be a situation where the object to be etched does not exist, so it is difficult to form the second mask pattern P2 with the required size and shape. In addition, the etching solution WE1-2' flowing through the large hole SN will also affect the temporary bonding portion 55 of the template 50 and the partition insulating portion 23. Therefore, it is necessary to control the size of the hole SN. Finally, when the upper width of the mask pattern P is set to about 40 μm and the lower width is set to about 25 μm, the width of the hole SN is preferably less than about 15.4 μm (more than 0), and more preferably less than about 15 μm (more than 0).

[0158] Figure 12 It is a relationship curve graph of the hole and the opening ratio according to the experimental example of the present invention. Figure 12 (a) shows the opening ratio with respect to the target size of the hole SN, Figure 12 (b) shows the maximum width of the hole SN with respect to the opening ratio. Here, the opening ratio can be understood as the area of the hole SN with respect to the area of the first mask pattern P1 based on the plane (the surface of the mask metal film). The opening ratio can be numerically valued by transmitting a black-and-white image.

[0159] Referring to Figure 12 in (a), in the interval where the hole SN starts to be formed (the opening ratio exceeds 0), the width change of the hole SN is very obvious. As described in (d) above Figure 5 this is because the wet etching proceeds isotropically, so the etching speed in the width direction (PD1->PD2) is greater than the degree of etching downward. Therefore, it is necessary to stably set the opening ratio before the width change of the hole SN.

[0160] Referring to Figure 12 in (b), in the interval where the opening ratio is 0 to 0.3%, the width of the hole SN changes sharply. Therefore, in order to set the maximum width of the hole SN to about 15 μm, the opening ratio can be 0 to 0.3%, and more preferably about 0 to 0.1%.

[0161] Referring back to Figure 11 , the angle a formed by the first mask pattern P1 and the horizontal plane can be less than 60° (more than 0). From another perspective, the angle a formed by the virtual straight line connecting the hole SN to the upper corner of the first mask pattern P and the lower surface of the mask metal film 110 can be less than 60° (more than 0). In order to prevent the shadow effect, the angle formed by the side surface of the final mask pattern P and the horizontal plane should be about 30° to 70°, but if the second mask pattern P2 is further formed through subsequent processes, the angle a can be further increased. Therefore, the angle a formed by the first mask pattern P1 (the first mask pattern P1) and the horizontal plane is preferably less than the above angle.

[0162] Figure 13 is immediately followed by Figure 11 FIG. is a schematic view showing a process of manufacturing a mask 100.

[0163] Referring to Figure 13 (a) of, after forming a first mask pattern P1 having a hole SN, a second insulating portion M2" can be formed on the side surface of the first mask pattern P1 [refer to Figure 7 (f) of]. Subsequently, wet etching WE2 can be performed on the first mask pattern P1. The wet etching solution penetrates into the space between the patterns of the first insulating portion M1 and the space of the first mask pattern P1 to perform wet etching WE2. The second insulating portion M2" masks the etching solution and prevents the etching solution from etching in the lateral direction of the first mask pattern P1, but etches in the downward surface direction of the first mask pattern P1.

[0164] Referring to Figure 13 (b) of, the second mask pattern P2 can be formed in a form that penetrates the mask metal film. That is, the second mask pattern P2 can be formed in a form that has a width greater than the width of the hole SN and penetrates from the lower end of the first mask pattern P1 to the other end of the mask metal film 110.

[0165] At this time, the second mask pattern P2 can be formed in a form different from that described in Figure 7 (g) and (h) in which concave curvatures are formed on both side surfaces. Since the first mask pattern P has a hole SN and the lower portion of the mask metal film 110 has a partition insulating portion 23, the shape of the second mask pattern P2 can be as shown in the figure.

[0166] Figure 14 is a schematic view of the mask pattern formation principle according to an embodiment of the present invention. The reason why the second mask pattern P2 is as shown in Figure 13 (b) will be described below.

[0167] Referring to Figure 14 (a) of, the etching solution penetrates between the second insulating portions M2", and due to the formation of the hole SN, the local thickness of the mask metal film 110 exposed around the hole SN is very thin. In addition, the exposed portion of the mask metal film 110 has a smaller curvature and a more horizontal shape compared to the unexposed portion. Thus, the portion around the hole SN is etched WE2' with a thinner thickness and is removed first, and as the side surface of the removed portion is exposed, this side surface can be further etched. The wet etching proceeds isotropically, and the characteristic that the etching rate in the width direction (or lateral direction) is greater than the etching degree in the downward direction [similar to Figure 5 (d) of PD1->PD2] can also play a role together.

[0168] On the other hand, referring to Figure 14In (b1), the second insulating portion M2''' does not necessarily correspond to the vertical lower position of the first insulating portion M1 and can be formed along the side surface of the first mask pattern P1 to a lower position. When performing exposure L in (e) of Figure 7 , due to the depth of the first mask pattern P1, at least the corners of the second insulating portion M2''' exposed through the gaps between the first insulating portions M1 cannot be exposed. Therefore, due to the remaining of this part, the second insulating portion M2''' is formed closer to the lower part. In addition, in order to more accurately control the size of the second mask pattern P2, the second insulating portion M2''' can be formed by performing exposure and development specifically.

[0169] Next, local etching WE2 can be performed on the mask metal film 110 exposed through the gaps between the second insulating portions M2''' formed at a lower position along the side surface of the first mask pattern P1.

[0170] Referring to Figure 14 In (b2), the mask metal film 110 of the vertical lower portion of the second insulating portion M2''' can exhibit an undercut shape due to isotropic etching. Since the gap between the second insulating portion M2''' and the partition insulating portion 23 is small, more etching solution flows downward compared to the upper or middle portion of the mask metal film 110 located below the second insulating portion M2'''. Therefore, the undercut of the mask metal film 110 located below the second insulating portion M2''' does not exhibit a concave curvature but exhibits a convex curvature or a shape close to a straight line.

[0171] Of course, Figure 14 the principles of (a) or (b1), (b2) can all be applied.

[0172] Figure 15 is a schematic diagram of a mask according to an embodiment of the present invention.

[0173] Referring to Figure 15 , the mask pattern P includes a first mask pattern P1 in the upper part and a second mask pattern P2 in the lower part, and the thickness of the first mask pattern P1 can be greater than the thickness of the second mask pattern P2.

[0174] As a result of isotropic etching of the first mask pattern P1, concave curvatures are formed on both side surfaces. The side surfaces of the second mask pattern P2 do not have concave curvatures but can exhibit convex curvatures or shapes close to straight lines.

[0175] Of course, the upper width D1 of the first mask pattern P1 is greater than the lower width D2 of the second mask pattern P2. In addition, the lower width D3 of the first mask pattern P1 (or the upper width D3 of the second mask pattern P2) can be smaller than the lower width D2 of the second mask pattern P2. Figure 11The width of the hole SN of the first mask pattern P1 is set to be less than 15.4 μm, and the lower width D2 of the second mask pattern P2 is set to be less than 35 μm. Therefore, the lower width D3 of the first mask pattern P1 (or the upper width D3 of the second mask pattern P2) is preferably greater than 15.4 μm and less than 35 μm. Thus, the side cross-sectional shape of the mask pattern P can resemble a water droplet shape that has dropped onto the ground.

[0176] The angle ta formed by the imaginary straight line connecting the upper end corner of the first mask pattern P1 to the lower end corner of the first mask pattern P1 and the lower surface of the mask can be less than 60° (more than 0), and preferably can be less than 55°. Since both side surfaces of the second mask pattern P2 have a convex curvature, the imaginary straight line should be arranged to contact the lower end corner of the first mask pattern P1 rather than the lower end corner of the second mask pattern P2. Thus, the overall shape of the mask pattern P, which is the sum of the shapes of the first mask pattern P1 and the second mask pattern P2, can present a conical or inverted conical shape.

[0177] Figures 16 to 18 is the SEM photograph of the mask according to an experimental example of the present invention. Figure 16 and Figure 17 respectively show the (1) plane, (2) milling line, (3) side cross-section along the milling line, and (4) enlarged photograph of the side cross-section of various patterns, Figure 18 shows the enlarged photograph of the side cross-section. The mask pattern P forms a circular shape based on the plane.

[0178] Table 1 below shows the test data of the mask thickness, cone angle ta, and the height of the left / right step of various patterns. The height of the left / right step corresponds to t2' and t1' shown in (b) of Figure 15 respectively. Figure 16 and Figure 17 Specimen 1 and Specimen 2 are typically shown in Figure 18 Specimens 3 to 6 are shown in

[0179] Table 1

[0180]

[0181] Referring to Figures 16 to 18 it can be observed that the mask pattern P has the form as shown in Figure 15 Both side surfaces of the first mask pattern P1 have a concave curvature, and both side surfaces of the second mask pattern P2 have a convex curvature or a shape close to a straight line. In addition, referring to Table 1, it can be seen that as the mask thickness becomes thinner, the height of the step shows a tendency to decrease. The cone angle is less than 55°, and compared to the mask thickness, the step heights are 6%, 22.8%, 26.7%, 25.6%, 27.9%, and 18.4% respectively, with a maximum not exceeding 30%.

[0182] Next, a process of bonding the mask 100 to the frame 200 using the fabricated mask support template 50 will be described.

[0183] Figure 19 It is a schematic diagram of a state in which the template 50 is loaded on the frame 200 and the mask 100 is aligned with the unit area CR of the frame 200 according to an embodiment of the present invention. Figure 12 The case where one mask 100 is aligned / attached to the unit area CR is illustrated, but multiple masks 100 can also be simultaneously aligned with all the unit areas CR so that the masks 100 are attached to the frame 200. In this case, multiple templates 50 for separately supporting the multiple masks 100 can be provided.

[0184] The template 50 can be transferred by a vacuum chuck 90. The opposite side of the surface of the template 50 to which the mask 100 is bonded can be adsorbed by the vacuum chuck 90 and transferred. After the vacuum chuck 90 adsorbs the template 50 and turns it over, the bonding state and alignment state of the mask 100 are not affected during the process of transferring the template 50 to the frame 200.

[0185] Then, referring to Figure 19 , the mask 100 can be aligned with one mask unit area CR of the frame 200. The alignment of the mask 100 with the mask unit area CR can be achieved by loading the template 50 on the frame 200 (or the mask unit sheet portion 220). While controlling the position of the template 50 / vacuum chuck 90, it can be observed through a microscope whether the mask 100 is aligned with the mask unit area CR. Since the template 50 presses the mask 100, the mask 100 can be in close contact with the frame 200.

[0186] In addition, a lower support 70 can be further arranged at the lower part of the frame 200. The lower support 70 can press the opposite side of the mask unit area CR in contact with the mask 100. At the same time, since the lower support 70 and the template 50 press the edges of the mask 100 and the frame 200 (or the mask unit sheet portion 220) in opposite directions, the alignment state of the mask 100 can be maintained without being disrupted.

[0187] Next, a laser L can be irradiated onto the mask 100 and the mask 100 can be attached to the frame 200 based on laser welding. Weld beads WB are generated at the welded portions of the mask welded by the laser. The weld beads WB can have the same material as the mask 100 / frame 200 and are connected to the mask 100 / frame 200 integrally.

[0188] Figure 20 It is a schematic diagram of a process of separating the mask 100 from the template 50 after the mask 100 is attached to the frame 200 according to an embodiment of the present invention.

[0189] Referring toFigure 20 After attaching the mask 100 to the frame 200, the mask 100 and the template 50 can be debonded. By performing at least one of heat ET, chemical treatment CM, application of ultrasonic waves US, and application of ultraviolet rays UV on the temporary bonding portion 55, the mask 100 and the template 50 can be separated. Since the mask 100 remains attached to the frame 200, only the template 50 can be lifted. As an example, if heat ET at a temperature higher than 85°C - 100°C is applied, the viscosity of the temporary bonding portion 55 decreases, and the adhesive force between the mask 100 and the template 50 weakens, thereby separating the mask 100 and the template 50. As another example, by immersing the temporary bonding portion 55 in chemicals such as IPA, acetone, and ethanol in CM to dissolve and remove the temporary bonding portion 55, the mask 100 and the template 50 can be separated. As another example, by applying ultrasonic waves US or ultraviolet rays UV, the adhesive force between the mask 100 and the template 50 is weakened, thereby separating the mask 100 and the template 50.

[0190] Figure 21 is a schematic diagram of a state in which the mask 100 is attached to the frame 200 and the insulating portion 23 is removed according to an embodiment of the present invention. Figure 21 Shows the state of the unit area CR where all the masks 100 are attached to the frame 200. Although the mask 100 can be attached one by one and then the template 50 can be separated, all the masks 100 can also be attached and then all the templates 50 can be separated.

[0191] The template 50 is separated from the mask 100 by the vacuum chuck 90, and the partition insulating portion 23 will remain on the mask 100. If the partition insulating portion 23 is a cured photoresist, it is difficult to remove it by a wet etching process. Therefore, in order to remove the partition insulating portion 23 on the mask 100, at least one of plasma PS and ultraviolet rays UV can be applied. A process can be performed in which the frame-integrated masks 100 and 200 are loaded into another chamber (not shown), and only the partition insulating portion 23 is removed by applying atmospheric pressure plasma, vacuum plasma PS, or ultraviolet rays UV.

[0192] As described above, the present invention can form the first mask pattern P1 with the maximum depth while leaving the step with the thinnest thickness, so it has the effect of being able to more precisely control the size and position when finally forming the mask pattern P. In addition, by using the mask support template including the mask metal film 110 / partition insulating portion 23 / temporary bonding portion 55 / template 50, it has the effect of preventing errors caused by the penetration / leakage of the etching solution in the wet etching process.

[0193] As described above, although the preferred embodiments of the present invention have been described with reference to the accompanying drawings, the present invention is not limited to the described embodiments, and those of ordinary skill in the art to which the present invention pertains can make various modifications and changes without departing from the spirit of the present invention. Such modified examples and changed examples should be regarded as all belonging to the scope of the present invention and the appended claims.

Claims

1. A mask support template for supporting a mask used for forming OLED pixels, the mask support template comprising: Template; A temporary bonding portion formed on the template; And A mask bonded to the template by sandwiching the temporary bonding portion and having a plurality of mask patterns formed thereon, wherein a partition insulating portion is further formed on the temporary bonding portion, and the mask is bonded to the upper surface of the template by sandwiching the temporary bonding portion and the partition insulating portion, The mask pattern includes a first mask pattern in the upper part and a second mask pattern in the lower part. The thickness of the first mask pattern is greater than that of the second mask pattern. The upper width of the first mask pattern is greater than the lower width of the second mask pattern. The lower width of the first mask pattern is less than the lower width of the second mask pattern, Both side surfaces of the first mask pattern have a concave curvature, and both side surfaces of the second mask pattern have a convex curvature, The first mask pattern and the second mask pattern are formed by wet etching. When wet etching the second mask pattern, the etching solution etches along the side direction at the exposed portion of the partition insulating portion, making the lower width of the second mask pattern greater than the upper width.

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