method for manufacturing high-resolution deposition masks with improved PPA

Abstract

According to one embodiment of the present invention, in a method for manufacturing a high-resolution deposition mask, by applying mechanical force to detach a mask body manufactured on a carrier substrate such as a silicon substrate, deformation of the deposition hole pattern is prevented, and the Pixel Pitch Accuracy (PPA) can be improved compared to a conventional method of separating only the mask. To this end, in particular, one embodiment of the present invention comprises a method for manufacturing a high-resolution deposition mask for manufacturing an OLED substrate that forms a plurality of pixel regions divided into sections on a deposition substrate, comprising: a mask body forming step (S10) of forming a mask body having a deposition hole pattern corresponding to a plurality of pixel regions divided into sections on a carrier substrate; a mesh frame attachment step (S20) of attaching a frame having a mesh structure covering a non-pixel region other than the edge of the mask body and a plurality of pixel regions to the upper part of the mask body; and a mask separation step (S30) of separating the mask body and the frame having a mesh structure integrally from the carrier substrate by mechanical force, thereby manufacturing a high-resolution deposition mask with improved PPA.

Description

Technology Field

[0001] The present invention relates to a method for manufacturing a high-resolution deposition mask. Background Technology

[0002] Conventional deposition masks using rolled Invar with a thickness of around 500 ppi are manufactured through photolithography and wet etching processes, but there was a problem in that it was difficult to manufacture high-resolution masks because it was difficult to make the Invar thin during the manufacturing process.

[0003] Meanwhile, small OLED displays for virtual reality (VR) and augmented reality (AR), including extended range (XR), require a high resolution of at least 3,000 ppi. To manufacture these high-resolution displays, the OLED DoS process, which manufactures displays using a silicon wafer-based process rather than the conventional glass-based process, is being used.

[0004] Depending on the process, OLEDs are used in two ways: one where the OLED is used as a white light source and pixels are formed through a color filter (mainly used in large displays such as TVs), and another where R (red), G (green), and B (blue) organic materials directly emit light to form pixels (mainly used in mobile phones). Among these two methods, for the R, G, and B organic materials to directly form pixels with light, a shadow mask with small holes corresponding to each pixel is required. To achieve high resolution, the size of the deposition holes corresponding to each pixel must be small, and high positional precision (PPA: Pixel Pitch Accuracy) is required for alignment with the back electrode.

[0005] In addition, the thickness of the deposition mask for fabricating OLED displays must be reduced as the resolution increases, because the size of the deposition holes formed increases as the thickness increases depending on the etching angle during the mask fabrication process. However, in the case of Fine Metal Masks (FMMs) for mobile phones using rolled Invar, masks with a thickness of about 15 to 20 μm are applied, and making them thinner has reached a technical limit.

[0006] Therefore, to develop a new deposition mask, methods are being proposed to fabricate the mask by forming an Invar thin film with a thickness of 1 to 2 μm after a photolithography process (e.g., electro-forming) rather than by making a thin film of Invar through a rolling process, or by etching the back substrate after depositing a film such as SiN on a silicon substrate.

[0007] US Patent 9,142,779 B2 is disclosed in particular with respect to the latter of the methods presented above. In US Patent 9,142,779 B2, Si on a silicon wafer x N y We are depositing and etching the back substrate after photolithography, and Si on the silicon wafer x N y During the deposition process, it is difficult to deposit a film of uniform thickness depending on the degree of wafer warping, and there is a disadvantage that the etching process on the back side also takes a long time. Since it is normal for commercially available silicon wafers to have a warping of about 20 µm, this is due to the standard specifications of normal good products rather than a wafer defect, so it seems virtually difficult to overcome this disadvantage.

[0008] In addition, regarding the total thickness that must be etched on the back side, a standardized thickness is used depending on the wafer diameter, so a wafer with a thickness of approximately 725 µm for an 8-inch wafer and approximately 775 µm for a 12-inch wafer must be etched, which results in a decrease in yield and high process costs during mask manufacturing.

[0009] Meanwhile, even when Invar is manufactured by plating, it is difficult to ensure a uniform plating process for thin Invar metal films. Invar metal films manufactured in this manner have a coefficient of thermal expansion (CTE) of 4 to 6 ppm, which is much higher than the coefficient of thermal expansion (CTE) of rolled Invar, which is about 1.2 ppm. Therefore, a heat treatment process of 400 degrees or higher must be performed, and there is a problem that this process causes changes in the existing PPA.

[0010] Since both of the aforementioned methods are fabricated by forming deposition holes on a silicon substrate through a photolithography process and then removing the back surface by etching, they have problems such as high process time and low yield, resulting in high mask fabrication costs. The problem to be solved

[0011] The present invention was developed to solve the above-mentioned problems, and the first objective of the present invention is to provide a method for manufacturing a high-resolution deposition mask with improved PPA that prevents deformation of the deposition hole pattern and improves PPA by applying mechanical force to detach a mask body manufactured on a carrier substrate such as a silicon substrate.

[0012] The second objective of the present invention is to provide a method for manufacturing a high-resolution deposition mask with improved PPA that can separate the mask body from a carrier substrate without a change in PPA by using a mesh structure frame attached between deposition hole patterns (non-pixel areas) formed corresponding to a plurality of partitioned pixel areas and an adhesive after curing. means of solving the problem

[0013] The objective of the present invention as described above can be achieved by providing a method for manufacturing a high-resolution deposition mask with improved PPA, comprising: a step of forming a mask body (S10) having a deposition hole pattern corresponding to a plurality of pixel regions divided on a deposition substrate; a step of attaching a mesh frame (S20) to the upper part of the mask body to cover a non-pixel region other than the edge of the mask body and a plurality of pixel regions; and a step of separating the mask body and the mesh frame from the carrier substrate as a whole using mechanical force (S30).

[0014] A method for manufacturing a high-resolution deposition mask with improved PPA may further include a step (S15) of interposing a curable adhesive layer that has completed curing between the mask body formation step and the frame attachment step. Here, the term "curable adhesive layer that has completed curing" is used to mean a curable adhesive layer in which the degree of curing has progressed to 90% or more.

[0015] The mesh structure frame may be made of a metallic or non-metallic material. The mesh structure frame may be selected such that its coefficient of thermal expansion (CTE) matches the coefficient of thermal expansion of the mask body.

[0016] In the frame attachment step (S20), the mesh structure frame may be formed of a multilayer metal material having mutually different coefficients of thermal expansion.

[0017] A method for manufacturing a high-resolution deposition mask with improved PPA may further include a border frame attachment step of attaching a border frame along the border of a mesh structure frame between the frame attachment step (S20) and the mask separation step (S30) or after the mask separation step (S30).

[0018] In the edge frame attachment step, the edge frame may be a handling member for transporting the mask body or mounting it on the deposition equipment. Effects of the invention

[0019] According to one embodiment of the present invention as described above, in a method for manufacturing a high-resolution deposition mask, by applying a mechanical force to detach a mask body manufactured on a carrier substrate such as a silicon substrate, deformation of the deposition hole pattern is prevented, and the Pixel Pitch Accuracy (PPA) can be improved compared to a method of separating only the existing mask.

[0020] In addition, the invention provides a method for manufacturing a high-resolution deposition mask with improved PPA, which allows the mask body to be separated from a carrier substrate with improved PPA compared to a conventional method of separating only the mask, by using a mesh structure frame attached between deposition hole patterns (non-pixel areas) formed corresponding to multiple partitioned pixel areas and an adhesive after curing. Brief explanation of the drawing

[0021] FIG. 1 is a flowchart of an embodiment of a method for manufacturing a high-resolution deposition mask with improved PPA according to the present invention, and FIGS. 2 (a) to (d) sequentially illustrate an embodiment of a method for manufacturing a high-resolution deposition mask with improved PPA according to the present invention, and FIGS. 3 (a) to (e) sequentially illustrate another embodiment of the method for manufacturing a high-resolution deposition mask with improved PPA according to the present invention. FIG. 4 is a planar view of a deposition mask with a mesh structure frame attached, manufactured according to one embodiment of the method for manufacturing a high-resolution deposition mask with improved PPA according to the present invention. FIG. 5 is a planar view of a deposition mask with a mesh structure frame and a border frame attached, manufactured according to one embodiment of the method for manufacturing a high-resolution deposition mask with improved PPA according to the present invention. Specific details for implementing the invention

[0022] Embodiments of the present invention will be described in detail below with reference to the accompanying drawings and the contents described therein, but the present invention is not limited or restricted by the embodiments. Various modifications may be made to the embodiments described below. The embodiments described below are not intended to limit the forms of implementation and should be understood to include all modifications, equivalents, and substitutions thereof.

[0023] Meanwhile, in describing the present invention, if it is determined that a detailed description of related known functions or configurations could unnecessarily obscure the essence of the invention, such detailed description will be omitted. Furthermore, the terminology used in this specification is used to appropriately express embodiments of the present invention, and such terminology may vary depending on the intent of the user or operator, or the conventions of the field to which the invention belongs. Accordingly, the definitions of these terms should be based on the content throughout this specification.

[0025] Method for manufacturing a high-resolution deposition mask with improved PPA

[0026] One embodiment of the method for manufacturing a high-resolution deposition mask with improved PPA according to the present invention functions to improve the positional accuracy (PPA: Pixel Pitch Accuracy) of the deposition hole pattern compared to conventional deposition masks by preventing deformation of the deposition hole pattern that may occur during the mask manufacturing and usage process, which includes the completion and transfer of a mask body having a deposition hole pattern formed thereon and mounting it on a deposition facility. In particular, a deposition mask having a deposition hole pattern formed on a carrier substrate is inevitably separated from the carrier substrate and subjected to post-processing; however, shrinkage forces based on the curing of adhesive materials can cause minute positional changes in the deposition holes, and this embodiment functions to prevent such deformation of the deposition hole pattern.

[0027] FIG. 1 is a flowchart of one embodiment of the method for manufacturing a high-resolution deposition mask with improved PPA according to the present invention, FIG. 2 (a) to (d) are drawings sequentially showing one embodiment of the method for manufacturing a high-resolution deposition mask with improved PPA according to the present invention, and FIG. 3 (a) to (e) are drawings sequentially showing another embodiment of the method for manufacturing a high-resolution deposition mask with improved PPA according to the present invention. The present embodiment will be described in detail below with reference to FIG. 1 to 3.

[0028] The present embodiment relates to a method for manufacturing a high-resolution deposition mask for manufacturing an OLED substrate, wherein a plurality of partitioned pixel areas are formed on a deposition substrate. For efficient production, it is common for a deposition mask to form a plurality of partitioned pixel areas (unit deposition masks). In this specification, since the partitioned plurality of pixel areas correspond to a deposition hole pattern in the deposition mask, it is clarified that even if the two are used interchangeably, they refer to the deposition hole pattern of the deposition mask.

[0029] In this embodiment, as illustrated in FIG. 1, a mask body forming step (S10) is performed to first form a mask body having a deposition hole pattern corresponding to a plurality of pixel regions divided on a carrier substrate.

[0030] Next, a step (S15) of interposing a curable adhesive layer that has completed curing on the upper part of the mask body or the lower part of the mesh structure frame is performed. In this embodiment, the adhesive layer is attached to the lower part of the mesh structure frame and the lower part of the adhesive layer is attached to the upper part of the mask body. Here, the term "curable adhesive layer that has completed curing" is used to mean a curable adhesive layer in which the degree of curing has progressed to 90% or more. Here, the degree of curing can be derived, for example, by observing the double bonds of functional groups using FTIR (Fourier transform infrared) spectroscopy. In particular, if the curing has progressed to less than 90%, it is difficult to maintain PPA during adhesion, and monomers may be released from the adhesive resin during a subsequent high-vacuum deposition process, which may cause problems with high-vacuum degradation.

[0031] Next, a mesh frame attachment step (S20) is performed, in which a mesh structure frame covering non-pixel areas other than multiple pixel areas is attached to the upper part of the mask body.

[0032] Finally, a method for manufacturing a high-resolution deposition mask with improved PPA can be completed by performing a mask separation step (S30) in which the mask body and the frame of the mesh structure are integrally separated from the carrier substrate by mechanical force. In the case of the mask separation step (S30), the mask body and the frame of the mesh structure are separated by mechanical force (e.g., tensile force applied by a peeling means using vacuum pressure, pneumatic pressure, or hydraulic pressure), and it is preferable to separate them sequentially from one side of the mask body to the other.

[0033] That is, in this embodiment, as shown in FIG. 2, a carrier substrate is prepared using a material such as a silicon wafer, and a mask body formation step (S10) is performed on it through a deposition hole pattern formation process, etc., thereby completing the deposition mask. Here, the deposition hole pattern formation process may utilize a photolithography process or a nanoimprinting process (NIL).

[0034] A desired 2-layer deposition mask can be manufactured through a photolithography process, for example, by coating a mask material on a carrier substrate, curing it, then coating a PR (Photo Resist), and then exposing and developing it using a photomask to perform etching (RIE).

[0035] In addition, a desired two-layer deposition mask can be manufactured using a nanoimprinting process, for example, by coating a mask material onto a substrate, curing it, then coating it with Imprinting Resin, applying pressure to the coated Imprinting Resin with a NIL Mold, detaching the mold, and subsequently etching it. However, in addition to the two-layer deposition mask, a single-layer or multilayer deposition mask of three or more layers can be manufactured using the same method.

[0036] The above two processes describe a method for forming a resin-type deposition mask, but are not limited thereto. Accordingly, the mask body formation step (S10) includes a deposition mask manufactured by applying a material such as SiN onto a silicon wafer and forming a deposition hole pattern by various methods. That is, it includes all high-resolution deposition masks that need to be separated from the carrier substrate during the mask manufacturing process.

[0037] A deposition mask with a mesh structure frame attached is attached to the upper non-pixel area of ​​the mask, as shown in FIG. 2. Since the spacing between the pixel areas forming this upper non-pixel area of ​​the mask is several millimeters, it is not difficult to attach a mesh structure frame made of a metal or non-metal material that has already been manufactured. In this case, although not shown, a curable adhesive layer that has been cured as described above can be interposed to prevent deformation when attaching the mesh structure frame.

[0038] In addition, the mesh structure frame may be made of a metallic or non-metallic material. The mesh structure frame may be selected so that its coefficient of thermal expansion (CTE) matches the coefficient of thermal expansion of the mask body. Here, the metal may be made of various materials, such as iron alloys, nickel, or nickel-cobalt alloys. The mesh structure frame may be manufactured with a thickness of tens of micrometers to hundreds of micrometers.

[0039] For non-metallic materials, various materials such as glass, reinforced glass, quartz, ceramic, and CFRP can be selected and used. In addition, the mesh structure frame may be formed of multilayer metal materials having mutually different coefficients of thermal expansion. This is to match the CTE of the deposition mask through the combination of the coefficients of thermal expansion of the multilayer metal materials.

[0040] Meanwhile, a variation of the present embodiment is a method for manufacturing a deposition mask in which a border frame is additionally attached to a mesh structure frame. The border frame may also utilize a metallic or non-metallic material, and the manufacturing method is performed in the same manner as the present embodiment as shown in FIG. 3, except that the step of forming a mesh structure frame thinly as a first frame and attaching the border frame only to the upper border of the first frame is additionally performed. In the case of the variation, since the first frame can be formed thinner than in the present embodiment, attachment is possible more easily even if the spacing between pixel regions is small, and this contributes to PPA improvement. Additionally, the second frame has an additional deformation prevention function but can be used for handling the separated deposition mask thereafter.

[0041] FIG. 4 is a plan view of a deposition mask with a mesh structure frame attached, manufactured according to one embodiment of the method for manufacturing a high-resolution deposition mask with improved PPA according to the present invention, and FIG. 5 is a plan view of a deposition mask with a mesh structure frame and a border frame attached, manufactured according to one embodiment of the method for manufacturing a high-resolution deposition mask with improved PPA according to the present invention.

[0042] A deposition mask with a mesh structure frame attached is attached to cover a frame area (non-pixel area) excluding a pixel area, as shown in FIG. 4, and it is preferable that it be manufactured to correspond to the shape of the deposition mask and attached using an alignment mark (not shown).

[0043] Meanwhile, the deposition mask with the mesh structure frame and the rim frame attached is preferably attached along the upper edge in a band-like circular shape on the mesh structure frame, as shown in FIG. 5. It is preferable that this rim frame be made of the same material as the mesh structure frame, or even if not the same material, made of a material with a similar CTE. This rim frame may be a handling member for transporting the mask body or mounting it on a deposition equipment.

[0045] Although embodiments of the present invention have been described above with reference to the attached drawings, those skilled in the art will understand that the technical configuration of the present invention described above may be implemented in other specific forms without altering the technical concept or essential features of the present invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive. Furthermore, the scope of the present invention is defined by the claims set forth below rather than by the detailed description above. Additionally, all modifications or variations derived from the meaning and scope of the claims and equivalent concepts should be interpreted as being included within the scope of the present invention.

Claims

Claim 1 A method for manufacturing a high-resolution deposition mask for manufacturing an OLED substrate that forms a plurality of pixel regions divided into sections on a deposition substrate, comprising: a mask body forming step (S10) of forming a mask body having a deposition hole pattern formed on a carrier substrate corresponding to a plurality of pixel regions divided into sections; a step (S15) of interposing a curable adhesive layer having a curing degree of 90% or more on the upper part of the mask body or on the lower part of a mesh structure frame; a mesh frame attachment step (S20) of attaching a mesh structure frame selected to cover non-pixel regions other than the plurality of pixel regions and support the mask body, and which is made of a metal or non-metal material and whose coefficient of thermal expansion (CTE) matches the coefficient of thermal expansion of the mask body; and a rim frame attachment step of attaching a rim frame, which is a handling member for transporting the mask body or mounting it on a deposition equipment, along the rim of the mesh structure frame between the frame attachment step (S20) and the mask separation step (S30) or after the mask separation step (S30). A method for manufacturing a high-resolution deposition mask with improved PPA, comprising a mask separation step (S30) of integrally separating the mask body and the frame of the mesh structure from the carrier substrate by mechanical force to prevent pixel pattern deformation of the mask body. Claim 2 delete Claim 3 delete Claim 4 delete Claim 5 delete Claim 6 delete

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