Mask unit

Abstract

To configure a mask unit MU that restricts a treatment range for each second substrate and includes a frame part 7 covering each side S2 excluding each side S1 facing the second substrate and a beam part 8 covering each side facing each second substrate so as to suppress a shadow effect attributed to a thermal warpage as much as possible, when multiple pieces of second substrate Sg1, Sg2 smaller than a first substrate are parallelly arranged at an interval on a substrate arrangement surface 31 of a stage body 3 capable of arranging a rectangular first substrate.SOLUTION: A beam part has a base plate 81 that is freely stored in a groove 33 recessed on a substrate arrangement surface and multiple beam plate pieces 82 that are arranged in a line in an upper edge part of the base plate projected upward from the substrate arrangement surface in a longitudinal direction of the beam part. A pair of attachment plates 83 is suspended on a lower surface of each beam plate piece, and the base plate and the beam plate pieces are connected with a gap in a vertical direction through both attachment plates.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a mask unit, and more specifically to a mask unit that is positioned above a substrate mounting surface of a stage body that allows the placement of a first substrate of a predetermined size with a rectangular outline, and that restricts the processing range for each second substrate when multiple second substrates smaller in size than the first substrate with a rectangular outline are arranged side by side at intervals on the substrate mounting surface. [Background technology]

[0002] The manufacturing process of flat panel displays involves depositing various thin films on the surface of a rectangular glass substrate (hereinafter referred to as "substrate"). Sputtering devices have traditionally been used for this deposition process (see, for example, Patent Documents 1 and 2). Meanwhile, the size of the substrates on which films are to be deposited has been increasing with each generation (e.g., 2300 mm × 2700 mm for the G8.7 generation) and becoming thinner (e.g., 0.5 mm). When depositing films on such substrates using the so-called deposit-down method by sputtering a target in a vacuum chamber under a vacuum atmosphere, the substrate is transferred by a transfer robot onto the substrate mounting surface of a substrate stage (stage body) located within the vacuum chamber. Therefore, the area of ​​the substrate mounting surface is typically set according to the substrate size.

[0003] For example, from the viewpoint of efficient use of a sputtering apparatus, a substrate of a predetermined size may be used as a first substrate, and multiple second substrates (e.g., two substrates in the case of so-called half-size G8.7 generation substrates) smaller than the first substrate may be arranged side by side on the substrate mounting surface of the stage body for film formation. In such cases, it is necessary to cover the outer periphery of each second substrate to restrict the processing (film formation) range for each second substrate, and a mask unit disposed above the substrate mounting surface is used for this purpose. The mask unit typically includes a plate-shaped frame portion that covers the three sides of each second substrate excluding the sides facing each other, and plate-shaped beam portions that are disposed to bridge the opposing sides of the frame portion and cover the opposing sides of each second substrate.

[0004] The beams of the mask unit must be relatively thin so as not to block the path of sputtered particles that fly from the target according to a predetermined cosine law. Therefore, if the beams are heated by radiant heat or other factors during sputtering and thermal warping occurs, the sputtered particles may find their way around and adhere to areas that should be shielded by the beams (the so-called shadow effect). This problem becomes even more pronounced when two half-sized large-area substrates are arranged side by side for film formation, because the total length of the beams is longer and the amount of thermal warping increases in proportion to the square of the beam length. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-133065 [Patent Document 2] Japanese Patent Application Publication No. 2023-57218 Summary of the Invention [Problem to be solved by the invention]

[0006] In view of the above, an object of the present invention is to provide a mask unit that can suppress as much as possible the shadow effect caused by thermal warping of the beam portions arranged between the substrates. [Means for solving the problem]

[0007] In order to solve the above problem, when a plurality of second substrates smaller in size than the first substrate having a rectangular outline are arranged side by side at intervals on a substrate mounting surface of a stage body which allows the installation of a first substrate of a predetermined size having a rectangular outline, the mask unit of the present invention which is arranged above the substrate mounting surface and restricts the processing range for each second substrate comprises a frame portion which covers each of the sides of each second substrate except for the sides facing each other, and a beam portion which covers each of the sides facing each other of the second substrates, the beam portion having a base plate which can be freely stored in a storage space recessed in the substrate mounting surface and a plurality of beam plate pieces which are arranged in a row in the longitudinal direction of the beam portion at the upper end portion of the base plate which protrudes upward from the substrate mounting surface, a pair of mounting plates are vertically attached to the underside of each beam plate, and the base plate and the beam plate pieces are connected via both mounting plates with a vertical gap.

[0008] According to the above, when multiple second substrates are placed on a substrate mounting surface and a film is formed on them, for example, the mask unit is positioned above the substrate mounting surface and placed in advance in the vacuum chamber of the sputtering apparatus. Then, after each second substrate is placed on the substrate mounting surface, for example, by moving the stage body up to a predetermined height, the lower end portion of the base plate is stored in the storage space of the substrate mounting surface. In this state, the outer periphery of each second substrate is covered by the frame and beams of the mask plate, with gaps in the vertical direction. In this state, a target is sputtered on each second substrate in the vacuum chamber under a vacuum atmosphere to form a film using a deposition-down method, and the beams are heated by radiant heat or the like during sputtering.

[0009] In the present invention, for example, the total length of the opposing sides of the second substrate is divided into multiple equal parts, the length of each division is defined as the division length, and beam plate pieces of the same length are arranged longitudinally along the upper end of the base plate. This configuration reduces the amount of thermal warping that occurs in each beam plate piece. As a result, the shadow effect caused by thermal warping can be minimized. Furthermore, when the lower end of the base plate is stored in the storage space of the substrate installation surface, there is a risk of particles being generated due to friction, etc., but because this location is located below the film formation surface (top surface) of the substrate, problems such as particles adhering to the substrate are unlikely to occur.

[0010] In the present invention, a configuration can be adopted in which two insertion holes are formed in each of the pair of mounting plates at a distance from each other in the longitudinal direction, and through holes having hole axes coinciding with the insertion holes are formed in the base plate, one of the insertion holes being elongated in the longitudinal direction, and a pin member is inserted into the insertion hole and the through hole along the hole axis to connect the base plate and each front beam plate piece. This is advantageous in that it does not restrict free deformation (thermal deformation) of each beam plate piece connected to the base plate part.

[0011] In the present invention, the beam plate pieces preferably have an outline shaped like a convex angle. This is advantageous because it increases the mechanical strength of the beam plate pieces that receive radiant heat compared to flat beam plate pieces and further suppresses the shadow effect. Furthermore, if an adhesion-preventing member is disposed on the portion of the stage body that defines the storage space in a manner that allows the base plate to be stored, it is possible to prevent sputtered particles from getting around and adhering to the portion of the stage body, which is advantageous when the portion of the stage body that defines the storage space is a chuck plate of an electrostatic chuck. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic cross-sectional view of a sputtering apparatus equipped with a mask unit according to an embodiment of the present invention. [Figure 2] Cross-sectional view along line II-II in Figure 1. [Figure 3] 3A and 3B are cross-sectional views taken along line III-III in FIG. 2, in which (a) shows the position of the mask unit at the substrate processing position and (b) shows the position of the mask unit at the substrate transfer position. [Figure 4] 4 is a cross-sectional view taken along line IV-IV in FIG. 2. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, with reference to the drawings, an embodiment of the mask unit MU of the present invention will be described, taking as an example an application to a sputtering apparatus for depositing films on one side of two glass substrates (hereinafter referred to as "small substrates Sg1, Sg2") of a predetermined size and rectangular outline by a sputtering method using a deposition-down method. Hereinafter, the direction in which the targets are arranged parallel to the small substrates Sg1, Sg2 is referred to as the X-axis direction, and the longitudinal direction of the targets perpendicular to the X-axis direction is referred to as the Y-axis direction. Furthermore, the stage main body moves in the Z-axis direction perpendicular to the X-axis and Y-axis directions, and terms indicating directions are based on FIG. 1, which shows the installation orientation of the sputtering apparatus.

[0014] Referring to FIG. 1, a magnetron sputtering apparatus Sa equipped with a mask unit MU according to this embodiment includes a vacuum chamber 1. An exhaust port 11 is provided in the sidewall of the vacuum chamber 1. The exhaust port 11 is connected to a vacuum pump 13, such as a rotary pump or a turbomolecular pump, via an exhaust pipe 12, allowing the interior of the vacuum chamber 1 to be evacuated to a predetermined pressure. The sidewall of the vacuum chamber 1 is also provided with a gas inlet 14 for introducing a sputtering gas consisting of a rare gas such as argon (which may also contain a reactive gas such as oxygen). The gas inlet 14 is connected to a gas source (not shown) via a gas inlet pipe 16 equipped with a mass flow controller 15, allowing the introduction of a sputtering gas with a controlled flow rate. A cathode unit 2 serving as a film formation source is detachably attached to the upper wall of the vacuum chamber 1.

[0015] The cathode unit 2 includes multiple targets 21 (four in this embodiment) arranged side by side at equal intervals in the X-axis direction. Each target 21 is made of a metal material or metal compound selected according to the composition of the thin film to be formed on the small substrates Sg1 and Sg2, and is shaped like a rectangle in a plan view. In this case, the dimensions (width in the X-axis direction and length in the Y-axis direction) of each target 21 are set so that when the target 21 is placed directly opposite the two small substrates Sg1 and Sg2 arranged side by side with a gap in the Y-axis direction, the area where the targets 21 are arranged side by side is slightly larger than the area where the small substrates Sg1 and Sg2 are arranged side by side. Each target 21 is bonded to a copper backing plate 22 and detachably attached to the upper wall of the vacuum chamber 1 via an insulator 23, with its sputtering surface 21a facing downward. Each target 21 is connected to a sputtering power supply 24 installed outside the vacuum chamber 1. In this embodiment, two adjacent targets 21, 21 are paired, and AC power can be applied between each pair of targets 21, 21. The cathode unit 2 further includes magnet units 25 disposed above each target 21.

[0016] The magnet unit 25 includes a support plate (yoke) 25a made of a magnetic material and having a rectangular outline, which is arranged parallel to the sputtering surface 21a of the target 21. A central magnet 25b extending in the Y direction at the center of the support plate 25a's underside and peripheral magnets 25c arranged along the outer periphery of the support plate 25a and surrounding the central magnet 25b are provided with their polarities reversed. This allows a balanced, closed-loop, tunnel-shaped magnetic field (not shown) to be formed in the space below each target 21. Although not specifically shown or described, each magnet unit 25 may be connected to a drive source such as a motor or air cylinder so that each magnet unit 25 (integrally) reciprocates in parallel with a predetermined stroke value in the X-axis direction at a uniform speed during film formation by sputtering. A substrate stage device Sm is provided in the lower space of the vacuum chamber 1, facing the area where each target 21 is arranged side by side.

[0017] The substrate stage device Sm includes a metal stage body 3. The substrate mounting surface 31, which is the upper surface of the stage body 3, is set to an area that generally corresponds to the area where the small substrates Sg1 and Sg2 are arranged side by side, and is large enough to accommodate a rectangular glass substrate (first substrate) in a plan view. A drive shaft 41 is connected to the underside of the stage body 3, penetrating the lower wall of the vacuum chamber 1 while maintaining airtightness and protruding into the vacuum chamber 1. The stage body 3 is vertically movable via the drive shaft 41 by a drive source 42, such as an air cylinder or linear motor, installed outside the vacuum chamber 1. The drive shaft 41 and drive source 42 move the stage body 3 vertically between a substrate transfer position, where the substrate Sg is transferred away from the target 21, and a substrate processing position (position shown in FIG. 1), where the substrate Sg is deposited adjacent to the target 21. Although not specifically shown or described, a chuck plate of an electrostatic chuck having a contour that matches the substrate mounting surface 31 may be attached to the substrate mounting surface 31 to electrostatically attract the substrate Sg during deposition. On the other hand, a passage for circulating a coolant or a heater may be installed inside the stage body 3 so that the substrate Sg can be controlled to a predetermined temperature during film formation by sputtering. Known components can be used for these components, so further detailed explanation will be omitted. The stage body 3 is formed with a plurality of through-holes 32 that penetrate in the vertical direction. The diameter of each through-hole 32 and the distance between each through-hole 32 are set appropriately taking into account the substrate size, the temperature distribution of the substrate Sg during film formation, and the like.

[0018] A support rod 5 is inserted into each through-hole 32 with a gap therebetween. Each support rod 5 is made of a metal rod with relatively strong mechanical strength. It has a large-diameter portion 51 that is stored in the through-hole 32 with a gap therebetween at the substrate processing position, and a small-diameter portion 52 that extends downward from the large-diameter portion 51. A cap body 53 (a component of the support rod 5) made of a different material is attached to the upper end of each support rod 5. The cap body 53 is made of a resin molded body such as polyimide. Although not specifically shown or described, an attachment hole extending upward is formed in the underside of the cap body 53, and the cap body 53 is attached by inserting it from above into another small-diameter portion formed at the upper end of each support rod 5. A guide member 6 is vertically attached to the stage body 3 so as to surround the lower edge of each through-hole 32. The guide member 6 has a cylindrical member 62 of a predetermined length, made of a metal having a comparatively high mechanical strength, and having an insertion hole 61 formed therein through which the small diameter portion 52 of each support rod 5 is inserted.

[0019] A cylindrical protrusion 63 is provided on the upper surface of the cylindrical member 62, extending upward so as to surround the upper edge of the insertion hole 61, and the protrusion 63 is fitted into the through hole 32 from its underside. As a result, when the stage body 3 moves upward relative to each support rod 5, the lower surface of the large diameter portion 51 of each support rod 5 abuts against the upper surface of the protrusion 63, thereby locking each support rod 5 (restricting downward movement of each support rod 5), preventing each support rod 5 from falling out of each through hole 32. The length of the large diameter portion 51 of each support rod 5 is set appropriately taking into consideration the amount of protrusion of each support rod 5 from the stage body 3 at the substrate transfer position and the thickness of the stage body 3, etc., and the diameters of the large diameter portion 51 and the small diameter portion 52 are set taking into consideration the diameters of the through hole 32 and the insertion hole 61. Furthermore, the cylindrical member 62 is provided with a pair of upper and lower guide rollers 64, 64, which guide the relative movement of each support rod 5 (the small diameter portion 52 thereof) in the vertical direction.

[0020] A support plate 65 is disposed on the inner surface of the lower wall of the vacuum chamber 1, and a regulating base 66 is disposed on the upper surface of the support plate 65, against which the lower end surfaces of the support rods 5 come into contact to regulate the downward movement of each support rod 5. The regulating base 66 also functions as a stopper member. The regulating base 66 may be disposed directly on the inner surface of the lower wall of the vacuum chamber 1, without providing the support plate 65. Also, a spacer member (not shown) may be detachably mounted on the upper or lower surface of the regulating base 66, allowing the amount of protrusion of each support rod 5 from the stage body 3 at the substrate transfer position to be appropriately changed. When two small substrates Sg1, Sg2 are placed on the substrate placement surface 31 for film formation, a mask unit MU of the present invention is disposed in the vacuum chamber 1 to regulate the film formation ranges on the two small substrates Sg1, Sg2, respectively.

[0021] 2 to 4, the mask unit MU includes a frame 7 covering three sides S2 of the small substrates Sg1 and Sg2 except for the sides S1 and S1 facing each other, and beams 8 covering the sides S1 and S1 facing each other of the small substrates Sg1 and Sg2. At the substrate transfer position, the mask unit MU is supported by a support frame 17 provided on the inner surface of the side wall of the vacuum chamber 1 via the frame 7. The beams 8 include a single base plate 81 elongated in the X-axis direction that can be stored in a groove 33 recessed in the center of the substrate mounting surface 31 over substantially the entire length in the X-axis direction, and a plurality of beam pieces 82 aligned in the X-axis direction at the upper end portion of the base plate 81 that protrudes upward from the substrate mounting surface 31 when stored in the groove 33. In this case, the base plate 81 has a length that reaches both ends of the frame 7, and the beam pieces 82 on both sides in the X-axis direction are positioned on the base plate 81. The width in the Y-axis direction of the recessed groove 33 that defines the storage space of the base plate 81 is set to be larger than the distance between the opposing sides S1, S1 of the small substrates Sg1, Sg2. The total length of the sides S1, S1 is then equally divided into a plurality of parts, the length of each divided unit being the division length, and the length in the X-axis direction of each beam plate piece 82 is set to be slightly shorter than the division length, and the beam plate pieces 82 are arranged in a row at the top end of the base plate 81 with gaps in their longitudinal direction that take thermal expansion into consideration. The division length is set appropriately according to the size of the small substrates Sg1, Sg2.

[0022] A pair of mounting plates 83, 83 are vertically attached to the underside of each beam piece 82 with a gap in the Y-axis direction, and the base plate 81 and the beam piece 82 are connected via the mounting plates 83, 83 with a gap in the vertical direction. Two insertion holes 84a, 84b are formed in each of the pair of mounting plates 83, 83 and spaced apart in the longitudinal direction. A through hole 85 having a hole axis coinciding with each of the insertion holes 84a, 84b is formed in each of the base plate 81, and each beam piece 82 is connected to the base plate 81 by inserting a pin member 86 into the insertion holes 84a, 84b and the through hole 85 along the hole axis. In this case, one of the insertion holes 84b is formed as an elongated hole in the longitudinal direction, allowing free deformation (thermal expansion) of the mounting plates 83, 83 and, ultimately, each beam piece 82. As shown enlarged in Fig. 4, each beam piece 82 and each mounting plate 83 has a gate-shaped protrusion 87a extending in the Y-axis direction on one end surface of each beam piece 82 and each mounting plate 83, extending continuously from both ends to the lower end of each mounting plate 83. The other end surfaces of each beam piece 82 and each mounting plate 83, facing the protrusion 87a, have a receiving recess 87b with a gap therebetween to receive the protrusion 87a. When each beam piece 82 is attached to the base plate 81, a labyrinth structure is formed between each beam piece 82. This minimizes deposition of sputtered particles on the recessed grooves 33 located between each beam piece 82, and also minimizes particle generation by preventing contact between each beam piece 82. As shown in Fig. 3, each beam piece 82 has an upwardly convex, angular profile (triangular in cross section). That is, the beam plate piece 82 is thick at the center and becomes thinner toward both sides. Also, when the base plate 81 is stored in the groove 33, an adhesion-preventing member 9 is provided to prevent sputter particles from adhering to the inner surface of the groove 33, which is part of the stage main body 3, or to the side surfaces of the small substrates Sg1 and Sg2. The film formation on the two small substrates Sg1 and Sg2 will be specifically described below.

[0023] When forming a film on a substrate Sg, first, the stage body 3 of the substrate stage device Sm is moved to the substrate transfer position. Although not specifically illustrated or described, at the substrate transfer position, the lower surface of the small diameter portion 52 of each support rod 5 abuts the upper surface of the regulating base 66, and each support rod 5 protrudes a predetermined amount from the stage body 3. Taking into account deflection due to the weight of each small substrate Sg1, Sg2, the large diameter portion 51 of each support rod 5 may protrude a greater amount from the stage body 3 on the outer periphery side of the small substrates Sg1, Sg2. Furthermore, as shown in FIG. 3(b), the mask unit MU is in a state in which its base plate 81 is partially detached from the recessed groove 33. Then, the small substrates Sg1, Sg2 are sequentially transferred into the vacuum chamber 1 by a transfer robot through the substrate unloading port 18 (see FIG. 1) opened in the side wall of the vacuum chamber 1, and each small substrate Sg1, Sg2 is temporarily received so that it is supported by the upper end surface of each support rod 5 (specifically, the cap body 51).

[0024] After the transport robot is retracted and the substrate unloading port 18 is closed, the stage body 3 is moved upward relative to each support rod 5. As the stage body 3 moves upward, the small diameter portion 52 of each support rod 5 moves downward relative to the stage body 3 while being guided by the pair of upper and lower guide rollers 64, 64. When the lower surface of the large diameter portion 51 of the support rod 5 abuts against the upper surface of the protruding piece portion 63, each support rod 5 is locked, thereby restricting the downward movement of each support rod 5 and preventing each support rod 5 from falling out of each through hole 32. In this state, the lower surface of the small diameter portion 52 of each support rod 5 is spaced from the upper surface of the regulating base 66, and each support rod 5 reaches a substrate processing position where the large diameter portion 51, including the cap body 53, of each support rod 5 is completely immersed in the through hole 32 (see FIG. 1 ). As the stage main body 3 moves upward, the base plate 81 of the mask unit MU sinks into the recessed groove 33, and the lower end surface of the base plate 81 abuts against the recessed groove 33 to be positioned. As a result, the outer periphery of each of the small substrates Sg1, Sg2, including the sides S1, S1 facing each other, is covered by the beam portion 8 with vertical gaps remaining, and the outer periphery of each of the small substrates Sg1, Sg2, including the remaining three sides S2, S2, is covered by the frame portion 7 with vertical gaps remaining. In this state, each target 21 is sputtered by a sputtering method in the vacuum chamber 1 in a vacuum atmosphere to form a film over the mask unit MU, and after the film formation, the stage main body 3 is moved downward from the substrate processing position to the substrate transfer position.

[0025] According to the above embodiment, by adopting a configuration in which the beam pieces 82 are arranged in a row in the longitudinal direction at the upper end portion of the base plate 81, the amount of thermal warping occurring in each beam piece 82 is reduced. As a result, the shadow effect caused by thermal warping can be minimized. Furthermore, when the lower end portion of the base plate 81 is stored in the storage space 33 of the substrate mounting surface 31, there is a risk of particles being generated due to friction, etc. However, because this location is located below the film-forming surfaces (top surfaces) of the small substrates Sg1 and Sg2, problems such as particles adhering to the small substrates Sg1 and Sg2 are unlikely to occur. Moreover, because the beam pieces 82 have an upwardly convex, angular contour, their mechanical strength, which receives radiant heat, is increased compared to flat beam pieces 82. Furthermore, the shadow effect can be further suppressed, which is advantageous. Furthermore, the presence of the adhesion-preventing member 9 prevents sputtered particles from getting around and adhering to the inner surfaces of the grooves 33 of the stage body 3.

[0026] Although the above describes an embodiment of the present invention, various modifications are possible without departing from the scope of the technical concept of the present invention. In the above embodiment, two small substrates Sg1 and Sg2 serving as second substrates approximately equal to half the size of the substrate are arranged side by side on a substrate mounting surface 31 capable of mounting a first substrate of a predetermined size, and film formation is performed on the substrate mounting surface 31. However, the present invention is not limited to this. The present invention can also be applied to cases where second substrates of 1 / 3 size are arranged side by side at a predetermined interval in the Y-axis direction, or where second substrates of 1 / 4 size are arranged side by side at predetermined intervals in the X-axis and Y-axis directions. For example, when forming a film on a second substrate of 1 / 3 size, two beams 8 can be provided spaced apart in the Y-axis direction. When forming a film on a second substrate of 1 / 4 size, the beams 8 can be arranged in a cross shape. Furthermore, in the above embodiment, the stage main body 3 is moved up and down by the moving means 4. However, the present invention is not limited to this. The substrate stage device SM can also be configured so that the support rods 5 and the mask unit MU move up and down. [Explanation of symbols]

[0027] MU...mask unit, Sg1, Sg2...small substrate (second substrate), S1, S2...side, 3...stage body, 31...substrate mounting surface, 33...groove (defining storage space), 7...frame portion, 8...beam portion, 81...base plate, 82...beam plate piece, 83...mounting plate, 84a, 84b...insertion hole, 85...through hole, 86...pin member, 9...adhesion prevention member.

Claims

1. a mask unit disposed above the substrate mounting surface of a stage body that allows a first substrate of a predetermined size having a rectangular outline to be mounted, and that restricts a processing range for each second substrate when a plurality of second substrates smaller in size than the first substrate having a rectangular outline are arranged side by side at intervals on the substrate mounting surface, a frame portion covering each of the sides of each second substrate other than the sides facing each other, and a beam portion covering each of the sides of each second substrate facing each other; A mask unit characterized in that the beam portion has a base plate that can be freely stored in a storage space recessed in the substrate mounting surface, and a plurality of beam plate pieces arranged in a row in the longitudinal direction of the beam portion at the upper end portion of the base plate that protrudes upward from the substrate mounting surface, and a pair of mounting plates are vertically attached to the underside of each beam plate piece, and the base plate and beam plate pieces are connected via both mounting plates with a gap in the vertical direction.

2. The mask unit of claim 1, characterized in that two insertion holes are formed in each of the pair of mounting plates at a longitudinal interval, and through holes having hole axes coinciding with each of the insertion holes are formed in the base plate, and one of the insertion holes is made a long hole in the longitudinal direction, and a pin member is inserted into the insertion hole and the through hole along the hole axis to connect the base plate and each front beam plate piece.

3. 3. The mask unit according to claim 1, wherein the beam plate pieces have an outline in the shape of an upwardly convex mountain.

4. 3. The mask unit according to claim 1, wherein an adhesion-preventing member is disposed in a portion of the stage body that defines the storage space, in a state that allows the base plate to be stored.

Images