Frame assembly for mounting pellicle on photomask

Abstract

The invention discloses a frame assembly for mounting a pellicle on a photomask. The frame assembly includes a frame to which the pellicle is attached, a post attached to the photomask, and a fixture inserted into an underside of the frame. The posts and the fixture are magnetically engaged with each other, and a gap of a specific height is created between the photomask and the frame by the posts below the fixture. This eliminates the need to accurately align the frame during a mounting process on the photomask, and facilitates separation of the frame from the photomask for reuse. The formation of the gap eliminates the need for a separate process to create vent holes in the frame.

Description

Technical Field

[0001] The present invention relates to a frame assembly, and more particularly, to a frame assembly for mounting a pellicle on a photomask used in a lithography process. Background Art

[0002] Extreme Ultra-Violet (EUV) lithography technology is under development, which uses EUV exposure light with a wavelength of 13.5 nm to obtain micro patterns. In the lithography process, a photomask is used as a patterning template. However, impurities such as particles or foreign substances attached to the photomask can absorb or reflect the exposure light, thereby damaging the transferred pattern. Therefore, in order to prevent impurities from attaching to the surface of the photomask, a method of mounting a pellicle on the surface of the photomask is adopted. In the case of miniaturization of the circuit line width, the role of the pellicle in protecting the photomask becomes increasingly important due to the reduction in the size of impurities that may affect pattern damage.

[0003] FIG. 1 shows a conventional structure with a mounted pellicle. The pellicle 30 includes a square thin film 20 that transmits exposure light and a frame 50 that supports the thin film 20 in its outer region. Generally, a pellicle 30 having such a structure is manufactured by forming a thin film 20 on a silicon substrate and then etching the bottom of the substrate to form a frame 10.

[0004] In order to mount the pellicle 30 on the photomask 60, the frame 50 is mounted on top of the photomask 60. Then, the structure having the pellicle 30 mounted on the frame 50 is mounted on the photomask 60, thereby mounting the pellicle 30 on top of the photomask 60. An adhesive is applied to the bottom of the frame 50 for bonding between the frame 50 and the photomask 60.

[0005] Due to the repeated use of the exposure process of the photomask 60, the pellicle 30 needs to be replaced after reaching its service life. Since it is uneconomical to replace the more durable and reusable frame 50 together with the pellicle 30, a method of replacing only the pellicle 30 and reusing the frame 50 is implemented. In order to replace the pellicle 30, the frame 50 must first be disassembled from the photomask 60. This requires using a separate tool or manually separating the frame 30 from the photomask 60 at the bonding interface between the bottom of the frame 30 and the top surface of the photomask 60. Therefore, the separation process is complex, and there is a risk of damaging the photomask 60 or the frame 50 during the separation operation.

[0006] In addition, in a conventional configuration, extremely precise positioning alignment is required to mount the frame 50 at an accurate position on the photomask 60 during the coupling process.

[0007] In addition, considering that the EUV exposure process is carried out in a high-vacuum and high-reciprocating force environment, the film 20 should not be damaged by the pressure change from atmospheric pressure to vacuum. To accommodate these pressure changes, the frame 50 generally has a number of vent holes (not shown) penetrating laterally. These vent holes are used to buffer the pressure change by connecting the internal space (S) formed between the film 20 and the photomask 60 inside the frame 50 to the external space. Therefore, it is necessary to form vent holes in the frame 50, and due to the high-precision vent hole machining process, the manufacturing cost of the frame increases.

[0008] In addition, in such a conventional configuration, there is a problem that the adhesive applied between the frame 50 and the photomask 60 can act as particles during the EUV exposure process, thereby reducing the exposure accuracy. Summary of the Invention

[0009] The present invention has been designed to solve the above problems, and the object of the present invention is to provide a frame assembly that does not require high-precision frame positioning alignment during the process of coupling a photomask and a frame, and allows the frame and the photomask to be easily separated.

[0010] Another object of the present invention is to provide a frame assembly that eliminates the need for a process of forming separate vent holes in the frame.

[0011] Another object of the present invention is to provide a frame assembly that minimizes the phenomenon of the adhesive acting as particles between the frame and the photomask.

[0012] To achieve the above objects, the present invention provides a frame assembly for mounting a surface film on a photomask used in a lithography process. The frame assembly of the present invention includes: a frame mounted on the photomask, with the surface film attached to the frame; columns attached to the upper side of the photomask, the columns being disposed between the photomask and the frame; and a fixing device mounted by inserting into the lower side of the frame at a position corresponding to the columns between the photomask and the frame. The columns and the fixing device are magnetically engaged with each other, and when engaged, the columns positioned below the fixing device create a gap of a specific height between the photomask and the frame.

[0013] One of the columns and the fixing device can be made of a magnetic material, and the other can be made of a material that is magnetically engaged with the magnetic material.

[0014] The magnetic material may include a rare earth material that loses magnetism at a temperature exceeding its magnetic loss temperature.

[0015] Insertion notches are formed on the lower side of the frame for the fixing device to insert.

[0016] Preferably, the specific height of the gap is 0.05 - 0.5 mm.

[0017] Preferably, the surface of at least one of the upright column and the fixing device is coated with a metal or non-metal material.

[0018] The fixing device includes a fixing device main body extending in the length direction of the frame, and support portions protruding downward at both ends of the fixing device main body to form placing notches for the upright column. The upright column includes an upright column main body, and the upright column main body is prevented from moving in the length direction by being placed in the placing notches in a shape-matching manner.

[0019] The fixing device has coupling notches formed on the bottom surface of the placing notches, and the upright column has protrusions that are coupled to shape-match with the coupling notches.

[0020] The fixing device main body has a length of 5 to 150 mm, a width of 1 to 6 mm, and a thickness of 0.5 to 2 mm in the length direction.

[0021] The support portions have a length of 0.5 to 10 mm in the length direction and a height of 0.1 to 1 mm from the bottom surface of the placing notches.

[0022] The upright column main body has a length of 4 to 130 mm, a width of 1 to 10 mm, and a thickness of 0.15 to 1.5 mm in the length direction.

[0023] The width of the upright column main body is equal to or greater than the width of the fixing device main body.

[0024] The protrusions have a height of 0.1 to 1.5 mm.

[0025] The protrusions have a shape whose cross-section is one or more of a circular shape, a triangular shape, a square shape, and a polygonal shape.

[0026] Preferably, at least one of the upright column and the fixing device is formed with a magnetic enhancement portion having a shape protruding from or recessed into its surface, and the magnetic enhancement portion is used to enhance the magnetic force.

[0027] As a modified embodiment of the present invention, the fixing device has coupling notches formed on the bottom surface of the placing notches, the upright column has protrusions coupled to the coupling notches, the coupling notches are larger than the protrusions, and the protrusions have elastic portions on their outsides, and the elastic portions are inserted into the coupling notches together with the protrusions.

[0028] The elastic portions can be formed of at least one of metal, plastic, resin, and silicon.

[0029] According to the present invention, the frame and the photomask are defined by a shape match between the protrusions of the posts and the coupling notches of the fixing device and by the magnetic force between the fixing device and the posts. This eliminates the need to precisely align the position of the frame during the process of mounting the frame on the photomask and facilitates the separation of the frame from the photomask for reuse.

[0030] In addition, ventilation is generated through the gap formed between the frame and the photomask by the posts, thus eliminating the need for a process of forming separate ventilation holes in the frame.

[0031] Furthermore, the use of the adhesive is reduced and the adhesive is not exposed to the outside, thereby minimizing the appearance and outgassing of particles caused by the adhesive. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] FIG. 1 is a diagram showing a conventional structure with a surface film mounted.

[0033] Figure 2 is a perspective view of a frame assembly according to a first embodiment of the present invention.

[0034] Figure 3 is Figure 2 an exploded perspective view of.

[0035] Figure 4 is a partially enlarged exploded perspective view along line A-A of Figure 2 .

[0036] Figure 5 shows Figure 4 a view after flipping.

[0037] Figure 6 and 7 are Figure 4 a plan view and a side view of the fixing device in

[0038] Figure 8 and 9 are Figure 4 a plan view and a side view of the post in

[0039] Figure 10 is Figure 4 a partially enlarged side cross-sectional view in the assembled state of

[0040] Figure 11 is a diagram showing Figure 10 the disassembled state of.

[0041] Figure 12 is Figure 11 a partially enlarged view of.

[0042] Figures 13 to 18 FIG. is a diagram showing a second embodiment of the present invention.

[0043] Figures 19 to 21 A diagram showing the third embodiment of the present invention.

[0044] Figure 22 A diagram showing a modified example of the column according to the first embodiment. Detailed Description of the Invention

[0045] The present invention will be described in detail below with reference to the accompanying drawings. In the description of the present invention, a detailed explanation of the overall structure of the film 30 and the frame 50 is omitted, and the content described with reference to FIG. 1 in the prior art description is adopted. The same reference numerals are used for the components in FIG. 1 that are the same as those in the present invention.

[0046] Figure 2 A perspective view of a frame assembly according to the first embodiment of the present invention, and Figure 3 is Figure 2 an exploded perspective view of

[0047] The frame assembly according to the present invention can be applied to a photomask 60 used in a lithography process for manufacturing semiconductors and flat panel displays (FPDs), and is particularly suitable for the photomask 60 in an extreme ultraviolet (EUV) lithography process.

[0048] The frame assembly is mounted on the photomask 60, where the film 30 is attached to the top of the frame assembly, thereby providing a member for mounting the film 30 on the photomask 60. The frame assembly of the present invention includes the frame 50 and also includes a fixing device 70 and a column 80.

[0049] The photomask 60 has a microcircuit pattern (not shown) formed on its upper surface for use in a transfer process using EUV exposure light. The microcircuit pattern is generally formed on a quartz substrate used in the EUV exposure process and can be applied regardless of the size and shape of the glass substrate.

[0050] The frame 50 can be formed into various shapes, such as circular, triangular, square, and polygonal, and is generally in the form of a square frame, especially a rectangular frame. The frame 50 has a general shape and size applied in the EUV exposure process and can be changed in size and shape corresponding to the photomask 60. The frame 50 is made of materials such as Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Rb, Sr, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Hf, Ta, W, Pt, Au, SUS, Si, carbon steel, tool steel, ceramics, metal-ceramic composites, resins, or their alloys. Although the film 30 is attached to the upper side of the frame 50, it is omitted in Figure 2 here.

[0051] The column 80 is attached to the upper side of the photomask 60 between the photomask 60 and the frame 50. The fixing device 70 is attached to the lower side of the frame 30 at a position corresponding to the column 80 between the photomask 60 and the frame 50. The column 80 and the fixing device 70 are joined together by magnetic force to form a pair and bond together.

[0052] Both the column 80 and the fixing device 70 can be made of a magnetic material (magnet), or only one of them can be made of a magnetic material. The term magnetic material refers to a material magnetized by a magnetic field, including ferromagnetic, paramagnetic, and diamagnetic materials, covering all common magnets such as Alnico, ferrite, SmCo, neodymium, rubber magnets, plastic magnets, and magnets made of rare earth metals. If only one of the column 80 or the fixing device 70 is made of a magnetic material, then the other can be made of a metallic material or any material that can be magnetically attached to the magnetic material.

[0053] Preferably, a magnet made of a rare earth metal is used. Generally, rare earth materials become magnets through a magnetization process after being mechanically processed into a specific shape by mixing raw materials and then applying a magnetic force. The magnetization process involves applying a strong magnetic field to align the material in a specific direction, thereby inducing magnetism. Rare earth magnets such as neodymium magnets can set their magnetic field strength and demagnetization temperature according to their material mixture. If a rare earth magnet is heated beyond its operating temperature to a temperature at which it loses its magnetic force, it will lose its magnetism, but the lost magnetism can be restored by remagnetization. Using this principle, if the column 80 or the fixing device 70 (especially the fixing device 70) is made of a rare earth magnet with a specific magnetic force loss temperature, it can be strongly held together magnetically during the exposure process. By externally applying heat exceeding the magnetic force loss temperature, the magnetic body loses its magnetism, thereby facilitating the separation of the column 80 and the fixing device 70.

[0054] For example, for the reuse of the frame 50, the fixing device 70 that has lost its magnetism is detached from the frame 50, remagnetized through the magnetization process, and then reattached to the frame 50.

[0055] Preferably, the surfaces of the column 80 and the fixing device 70 will be coated with a metallic or non-metallic material to prevent outgassing. For the strong adhesive force caused by mutual magnetism, the coating can be made of a metallic material.

[0056] The column 80 and the fixing device 70 are attached at least once, and preferably, they are positioned in various numbers and positions according to the shape of the frame 50, which can keep the frame 50 stable against the force (vibrational force) generated by the moving direction of the platform that performs reciprocating motion during the exposure process.

[0057] Figures 4 to 12Shows the configuration of each part of the column 80 and the fixing device 70 according to the first embodiment of the present invention and their assembled state.

[0058] The frame 50 has an insertion notch 55 formed on its bottom surface, and the fixing device 70 is inserted and installed in the insertion notch 55. Once inserted into the insertion notch 55, it is preferred that the fixing device 70 does not move. To ensure this, the insertion notch 50 has the same shape as the fixing device 70 to allow shape-matching coupling. The fixing device 70 can be adhered by applying an adhesive in the insertion notch 55, and preferably, the fixing device is coupled by press-fitting without a separate adhesive to ensure that it does not separate and is firmly coupled. The depth of the insertion notch 55 is preferably the same as the thickness of the fixing device 70, especially the thickness of the support portions 72 formed at both ends of the fixing device 70. Therefore, the fixing device 70 inserted into the insertion notch 55 is horizontally positioned at the same level as the lower surface of the frame 50, neither protruding downward from the lower surface of the frame 50 nor being embedded within the insertion notch 55.

[0059] The fixing device 70 includes: a fixing device body 71 that extends in the longitudinal direction of the frame 50; and support portions 72 that protrude downward at both ends of the fixing device body 71, thereby forming a placement notch 73 for placing the column 80. A coupling notch 75 is formed on the bottom surface of the placement notch 73, thereby creating a two-stage recessed shape, where the placement notch 73 is recessed and the coupling notch 75 is further recessed inside the placement notch 73.

[0060] The column 80 is provided with a column body 81. The column body 81 is configured to match the length of the placement notch 73, and thus the lateral movement of the column 80 is prevented by shape matching within the placement notch 73. The column 80 is also characterized by a protrusion 85 that is fitted into the coupling notch 75, thereby being doubly secured in place by being held by the support portions 72 of the fixing device 70 and inserted into the coupling notch 75 for shape-matching connection. This structure ensures that the fixing device 70 and the column 80 remain connected even under the strong force generated by the rapid reciprocating movement of the platform during the exposure process.

[0061] The cross-sectional shapes of the fixing device body 71 and the column body 81 can be circular, elliptical, triangular, square, or polygonal.

[0062] The protrusion 85 can be cylindrical or conical, and its cross-section can be one or more shapes that match the shape of the coupling notch 75, such as circular, triangular, square, or polygonal.

[0063] Reference Figures 6 to 9 Describes the sizes of the corresponding parts of the fixing device 70 and the column 80.

[0064] The fixing device body 71 has a length (L1) of 5 to 150 mm, a width (W1) of 1 to 6 mm, and a thickness (T1) of 0.5 to 2 mm. The support portion 72 has a length (d11) of 0.5 to 10 mm and a height (d12) of 0.1 to 1 mm from the bottom surface of the placement notch 73. The coupling notch 75 has a depth (d13) of 0.1 to 1.5 mm.

[0065] The column body 81 has a length (L2) of 4 to 130 mm, a width (W2) of 1 to 10 mm, and a thickness (T2) of 0.15 to 1.5 mm. If both the column body 81 and the fixing device body 71 are made of magnetic materials, then the width of the column body 81 will be equal to or greater than the width of the fixing device body 71. If the fixing device body 71 is made of magnetic material and the column body 81 is made of magnetically attachable material, then preferably, the column body 81 has a greater width than the fixing device body 71 because the strongest magnetic field is formed at the edge region of the fixing device body 71.

[0066] The protrusion 85 of the column 80 has a height (d23) of 0.1 to 1.5 mm so as to match the depth (d13) of the coupling notch 75. For process performance and structural stability, the depths (d13) and height (d23) of the coupling notch 75 and the protrusion 81 are preferably 0.3 to 1 mm.

[0067] As Figure 12 shown, a gap of a specific height is formed between the lower side of the frame 50 and the upper side of the photomask 60. In the case where the column 80 and the fixing device 70 are coupled, a part of the thickness direction section of the column body 81 protrudes outward, thereby forming a gap between the lower side of the frame 50 and the upper surface of the photomask 60. This gap is preferably formed to have a height of 0.05 to 0.5 mm and serves as an exhaust hole to connect the internal space (S) formed by the film 30 and the frame 50 to its external space.

[0068] The column body 81 has an adhesive notch 87 formed on its lower side. An adhesive (C) is applied within the adhesive notch 87 so as to join the column body 81 to the photomask 60. Since the adhesive (C) is contained within the recessed adhesive notch 87, in the assembled state as Figure 12 shown, the adhesive does not leak out, thereby minimizing particle generation caused by the adhesive (C).

[0069] Figures 13 to 18Shows a second embodiment of the present invention. In this embodiment, the column 180 is provided with two protrusions 185 corresponding to the two coupling notches 175 in the fixing device 170. The column 180 has a column main body 181 and the fixing device 170 has a fixing device main body 171, a support portion 172 and a placement notch 173, and the configuration is the same as that in the first embodiment. In this embodiment, the lengths of the column 180 and the fixing device 170 are longer than those in the first embodiment, so as to provide a more robust connection between the photomask 60 and the frame 50 during the exposure process in which the photomask 60 moves in the length direction of the frame. Considering the forces generated during the reciprocating movement during the exposure process and the fastening strength between the fixing device 170 and the column 180, the number of the coupling notches 175 and the protrusions 185 on the fixing device 170 and the column 180 can be changed.

[0070] Figures 19 to 21 Describes a third embodiment of the present invention. In this embodiment, the fixing device 270 is substantially the same as the fixing device in the second embodiment, but further includes a magnetic enhancement portion 279. The magnetic enhancement portion 279 is formed as one or more grooves 279 recessed in the outer surface of the fixing device 270, preferably a plurality of grooves. When the fixing device 270 is made of a magnetic material, the strongest magnetic field is formed at the boundary region including the edge portion of the fixing device main body 71. Therefore, forming a plurality of magnetic enhancement portions 279 can strengthen the engagement between the fixing device 70 and the column 80. The dimensions of the magnetic enhancement portion 279, such as length, depth, width, etc., are not limited.

[0071] In addition, the magnetic enhancement portion 279 can not only be formed as the grooves as shown, but also be formed as ribs protruding from the fixing device main body 71, or be formed into various other shapes, such as protrusions protruding from the surface of the fixing device 270 or grooves recessed into the surface.

[0072] Although this embodiment illustrates that the magnetic enhancement portion 279 is formed on the fixing device 270, it can also be formed on the column or both the fixing device 270 and the column, in an independent shape or in an interlocking shape that is complementary to each other for connection.

[0073] Figure 22 Shows a modified example of the column according to the first embodiment.

[0074] In this embodiment, the coupling notch 75 of the fixing device 70 is larger than the protrusion 85 of the column 80. Specifically, when both the protrusion 85 and the coupling notch 75 have a circular cross-section, the diameter (R1) of the coupling notch 75 is larger than the diameter (R2) of the protrusion 85. The protrusion 85 is provided with an elastic portion 88 on its outer surface. The elastic portion 88 is made of one or more of the following materials: metal, plastic, resin, and silicone, and is attached to the outer surface of the protrusion 85 by fitting or coating. The thickness (r1) of the elastic portion 88 is set such that the overall size of the protrusion 85 including the elastic portion 88, i.e., R2 + 2r1, is equal to or slightly larger than the size of the coupling notch 75, i.e., R1. Thus, when the protrusion 85 and the elastic portion 88 are inserted into the coupling notch 75, they are inserted in a manner similar to a press fit, thereby strengthening the engagement between the fixing device 70 and the column 80. This modification can also be applied to the second and third embodiments described previously.

[0075] Although the details of the present disclosure have been described above with reference to several embodiments of the present disclosure through the accompanying drawings, the embodiments are for illustrative and descriptive purposes only and are not to be construed as limiting the scope of the present disclosure defined in the appended claims. Those skilled in the art should understand that various changes and other equivalent embodiments can be made in accordance with these embodiments. Therefore, the scope of the present invention should be defined by the technical subject matter of the appended claims.

Claims

1. A frame assembly for mounting a pellicle on a photomask used in a lithography process, the frame assembly comprising: A frame mounted on the photomask, with the pellicle attached to the frame; Posts attached to the upper side of the photomask, the posts being disposed between the photomask and the frame; And A fixing device installed by inserting it into the lower side of the frame at a position corresponding to the posts between the photomask and the frame; Wherein the posts and the fixing device are magnetically engaged with each other, and when engaged, the posts positioned below the fixing device create a gap of a specific height between the photomask and the frame.

2. The frame assembly according to claim 1, wherein one of the posts and the fixing device is made of a magnetic material, and the other is made of a material that is magnetically engaged with the magnetic material.

3. The frame assembly according to claim 1, wherein the magnetic material includes a rare earth material that loses magnetism at a temperature exceeding its magnetic loss temperature.

4. The frame assembly according to claim 1, wherein insertion notches are formed on the lower side of the frame for inserting the fixing device.

5. The frame assembly according to claim 1, wherein the specific height of the gap is 0.05 - 0.5 mm.

6. The frame assembly according to claim 1, wherein the surface of at least one of the posts and the fixing device is coated with a metal or non-metal material.

7. The frame assembly according to claim 1, wherein The fixing device includes a fixing device main body extending in the length direction of the frame, and support portions protruding downward at both ends of the fixing device main body to form placement notches for the posts, and The posts include post main bodies, and the post main bodies are prevented from moving in the length direction by being placed in the placement notches in a shape-matching manner.

8. The frame assembly according to claim 7, wherein The fixing device has coupling notches formed on the bottom surface of the placement notches, and The posts have protrusions that are coupled to shape-match with the coupling notches.

9. The frame assembly according to claim 7, wherein The fixing device main body has a length of 5 - 150 mm, a width of 1 - 6 mm, and a thickness of 0.5 - 2 mm in the length direction; The support portions have a length of 0.5 - 10 mm in the length direction and a height of 0.1 - 1 mm from the bottom surface of the placement notches; The post main bodies have a length of 4 - 130 mm, a width of 1 - 10 mm, and a thickness of 0.15 - 1.5 mm in the length direction; and The protrusions have a height of 0.1 - 1.5 mm.

10. The frame assembly according to claim 7, wherein the width of the post main body is equal to or greater than the width of the fixing device main body.

11. The frame assembly according to claim 1, wherein at least one of the upright and the fixing device is formed with a magnetic enhancement portion having a shape protruding from or recessed into its surface, and the magnetic enhancement portion is for enhancing magnetic force.

12. The frame assembly according to claim 7, wherein the fixing device has a coupling notch formed on the bottom surface of the placement notch, the upright has a protrusion coupled to the coupling notch, the coupling notch is larger than the protrusion, and the protrusion has an elastic portion on its exterior, and the elastic portion together with the protrusion is inserted into the coupling notch.

13. The frame assembly according to claim 12, wherein the elastic portion is formed of at least one of metal, plastic, resin, and silicon.

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