WO2005124836A1

WO2005124836A1 - Pellicle frame assembly

Info

Publication number: WO2005124836A1
Application number: PCT/KR2005/001388
Authority: WO
Inventors: Han-Yong Cho
Original assignee: Han-Yong Cho
Priority date: 2004-06-19
Filing date: 2005-05-12
Publication date: 2005-12-29
Also published as: KR100733872B1; KR20060047803A

Abstract

The present invention generally relates to a pellicle frame for supporting a pellicle film capable of preventing foreign substances from adhering to a photomask or a reticle used in a lithography process upon fabrication of a semiconductor device. More particularly, the present invention relates to a pellicle frame assembly with a means for preventing a pellicle frame being deformed due to tension on a pellicle film. A pellicle frame assembly of the present invention comprises a pellicle frame with a plurality of sides for supporting a pellicle film, which has an edge attached to an upper surface of the pellicle frame, in a substantially flat state; and at least one restoring-force applying member that is installed at the pellicle frame to apply a restoring force for restoring deformation of the pellicle frame due to tension on the pellicle film attached to the upper surface to at least one of the sides of the pellicle frame. The pellicle frame assembly preferably further comprises a restoring-force controlling means connected to the at least one restoring-force applying member to control the restoring force applied to the at least one side of the pellicle frame. A wire or resilient member can be used as the restoring-force applying member.

Description

PELLICLE FRAME ASSEMBLY

Technical field The present invention generally relates to a pellicle frame for supporting a pellicle film capable of preventing foreign substances from adhering to a photomask or a reticle used in a lithography process upon fabrication of a semiconductor device. More particularly, the present invention relates to a pellicle frame assembly having a means for preventing the pellicle frame from being deformed due to a tension of the pellicle film.

Background art A lithography process in fabricating a semiconductor device is a process of forming a fine pattern on an integrated circuit (IC), a large scale integrated circuit (LSI), or a thin film transistor liquid crystal display (TFT LCD). In such a lithography process, a dustproof means that is referred to as "pellicle" is used for preventing foreign substances from adhering to a photomask or reticle. If foreign substances adhere to the surface of the photomask, the foreign substances form an image on a photoresist of a semiconductor wafer, leading to a defect in a circuit pattern. In case of installation of a pellicle, even though foreign substances adhere to the surface of a pellicle film, the foreign substances are offset from a focus position to generate aberration. Thus, the image of foreign substances is not formed on the photoresist of the wafer, so that a defect can be avoided in the circuit pattern. A pellicle comprises a hollow pellicle frame, and a pellicle film of which an edge is attached to one side of the frame by means of an adhesive. Although the pellicle frame has a shape corresponding to the shape of a photomask or reticle, the pellicle frame generally takes the shape of a rectangle with a pair of long sides and a pair of short sides, has a thickness of several millimeters at each side, and is made of aluminum. The pellicle film is a transparent polymeric film having a thickness of lOμm or less and made of nitrocellulose or a cellulose derivative. Further, an adhesive to be used for attachment to the photomask or reticle is applied to the other side of the frame to which the pellicle film is not attached. With the recent development of multimedia technology, demand for a high-quality large-sized color thin film transistor liquid crystal display (TFT LCD) rapidly increases. Since the shape of the large-sized TFT LCD is a rectangle, a pellicle frame used for the manufacture of the TFT LCD also takes the shape of a rectangle with a pair of opposite long sides and a pair of opposite short sides. As the size of an LCD increases, a rectangular pellicle frame is subjected to inward deformation of its sides due to the tension of a pellicle film attached to the pellicle frame, which causes a problem that a light exposure area in a photomask or reticle decreases. As an example of a pellicle frame for solving such a problem, Japanese Patent

Laid-Open Publication No. 2001-42507 (published on February 16, 2001) discloses a pellicle frame having a pair of opposite long sides la that protrude outward (is convexed gently outward), as shown in Fig. 17. When a pellicle film is attached to bonding surfaces lal and lbl of the frame, the outward protruding long sides of the pellicle frame are deformed inward due to tension of the film, so that the frame takes the shape of a rectangle to prevent a light exposure area from being decreased. In the large-sized pellicle frame with the outward protruding long sides, the protruding amount (profile) of a long or short side of the pellicle frame should be calculated and processed in consideration of the amount of deformation due to the tension of the pellicle film. However, the pellicle frame with the outward protruding long sides has problems in that it is difficult to accurately calculate the protruding amount of the long or short side of the frame according to a change in the material of the pellicle film or the frame itself or in the size of the frame, and it is more difficult to actually process a correct protruding shape even though accurate calculation is performed. Further, as the size of the pellicle frame increases, the amount of deformation also increases. Thus, the amount of protrusion should be increased. With the increase of the protruding amount, there is a risk that wrinkles may be produced in the attached pellicle film.

Disclosure of Invention Accordingly, the present invention is conceived to solve the aforementioned problem that a pellicle frame is deformed due to tension of a pellicle film and thus a light exposure area decreases. An object of the present invention is to provide a pellicle frame assembly with a means for preventing a pellicle frame from being deformed or for restoring a deformed pellicle frame. Particularly, the object of the present invention is to provide a pellicle frame assembly capable of maintaining the original shape of a pellicle frame by controlling deformation of the pellicle frame before or after a pellicle film is attached thereto, without beforehand calculating the amount of deformation and calculating and processing the protruding amount of each side of the pellicle frame. A pellicle frame assembly of the present invention comprises a pellicle frame with a plurality of sides for supporting a pellicle film, which has an edge attached to an upper surface of the pellicle frame, in a substantially flat state; and at least one restoring-force applying member that is installed at the pellicle frame to apply a restoring force for restoring deformation of the pellicle frame due to tension of the pellicle film attached to the upper surface to at least one of the sides of the pellicle frame. The pellicle frame assembly preferably further comprises a restoring-force controlling means connected to the at least one restoring-force applying member to control the restoring force applied to the at least one side of the pellicle frame. The restoring-force applying member employs a resilient member that applies a restoring force resulting from elastic deformation to the pellicle frame, or a member such as a wire of which tension is applied to the pellicle frame, thereby preventing deformation of the pellicle frame or restoring the deformed pellicle frame. If the restoring force is applied to the pellicle frame by means of the wire, one end of the wire is fixed to the at least one side while the wire is installed along the length of the side, and the other end of the wire is connected to the restoring-force controlling means to control tension on the wire acting as the restoring force. Preferably, the restoring-force control means comprises a winding shaft rotatably installed at the pellicle frame to adjust the length of the wire by winding the other end of the wire connected thereto, and a winding-shaft fixing means for preventing the winding shaft from being rotated. After tension is applied to the pellicle frame by adjusting the length of the wire through rotation of the winding shaft for winding the wire around the winding shaft, the winding shaft can be fixed by the fixing means for preventing the rotation of the winding shaft, which may be implemented by formation of threads on the winding shaft or by a frictional force obtained when the winding shaft is pressed to come into close contact with the pellicle frame. In the case where the winding shaft is fixed by being pressed against the pellicle frame, if the winding shaft is inserted into and rotatably installed in a hole formed from an outer surface to an inner surface of the pellicle frame, the winding-shaft fixing means preferably comprises a pressing member for fixing the winding shaft by radially pressing the winding shaft. If the winding shaft is inserted into and rotatably installed in a hole formed from a lower surface to the upper surface of the pellicle frame, the winding-shaft fixing means preferably comprises a pressing member for fixing the winding shaft by axially pressing the winding shaft. Further, the winding shaft may be installed at a side adjacent to the side with the one end of the wire fixed thereto, or at a corner where the side joins with an adjacent side. If a plurality of wires and winding shafts are installed at opposite corners, it is preferred that they be installed to be symmetrical with each other. More preferably, an outer surface of the side of the pellicle frame in which the wire is installed is formed with a groove along the length of the side, and the wire is inserted into and installed in the groove such that the wire does not protrude outwardly. According to the present invention, the wire installed at the pellicle frame is tightly strained by the restoring-force controlling means so that the pellicle frame can be prevented from being deformed due to tension on a pellicle film or the deformed pellicle frame can be restored. In the pellicle frame assembly of the present invention, a wire as the restoring-force applying member may be installed along the length of the at least one side, and the connection of the wire to the side of the pellicle frame may be made such that relative movement can be performed in a slidable manner when tension on the wire is controlled by the restoring-force controlling means. If the wire and the pellicle frame are installed such that they move relative to each other, an outer surface of the side of the pellicle frame in which the wire is installed is formed with a groove along the length of the side, and at least one wire-supporting member is fixedly installed within the groove while being spaced apart by a predetermined from a bottom surface of the groove. Further, one end of the wire is fixed to a corner where one end of the at least one side joins with an adjacent side, and the other end thereof passes through a space between the bottom surface of the groove and the wire-supporting member and is then fixed to a corner where the other end of the adjacent side joins with an adjacent side. Moreover, a height from an inner surface of the side with the wire-supporting member fixed thereto to positions where the respective ends of the wire are fixed is larger than a height from the inner surface of the side with the wire-supporting member fixed thereto to a surface of the wire-supporting member facing the bottom surface of the groove. Thus, when tension is exerted on the wire, a force directed to the outside of the pellicle frame is applied to the wire-supporting member. More preferably, one wire is installed to surround the outer surface of the frame so that a force directed to the outside of the pellicle frame due to the tension on the wire is applied to all the sides of the inwardly deformed pellicle frame. That is, an outer surface of each of the sides of the pellicle frame is formed with a groove along the length of the side, and at least one wire-supporting member is installed in the groove formed in each of the sides while being spaced apart by a predetermined from a bottom surface of the groove. Further, one end of the wire passes through a space between the bottom surface of the groove and the wire-supporting member and is then connected to the other end of the wire while the wire surrounds the frame along the grooves. Moreover, a height from an inner surface of the side with the wire-supporting member fixed thereto to a corner of a side with which the wire is in contact is larger than a height from the inner surface of the side with the wire-supporting member fixed thereto to a surface of the wire-supporting member facing the bottom surface of the groove. Thus, when the wire is tightly strained due to tension exerted thereon, the wire urges the wire-supporting members outward of the pellicle frame. In the case where the resilient member is used as the restoring-force applying member in the pellicle frame assembly of the present invention, a narrow elongated resilient member with strength larger than that of the pellicle frame can be used as the restoring-force applying member. A step portion is formed at a portion of an outer surface of at least one of the sides to which the restoring force applied, extending to a corner where the side joins with an adjacent side, and the narrow elongated resilient member has one end fixed to an outer surface of at least one of the sides and the other end as a free end extending to the comer formed with the step portion. An adjustment bolt is used as the restoring-force controlling means, so that the other end of the narrow elongated resilient member is pressed toward a lower portion of the comer formed with the step portion, thereby applying a restoring force resulting from elastic deformation to the pellicle frame. In the pellicle frame assembly of the present invention, the restoring-force applying member may comprise an angle-type resilient member bent to have an angle larger than an angle defined by an inner surface of a comer where the at least one side joins with an adjacent side. Both ends of the angle-type resilient member are installed to be in close contact with the inner surface of the comer. The restoring-force controlling means may comprise an adjustment bolt installed at the pellicle frame while having one end connected to the angle-type resilient member, so that the angle-type resilient member is pulled toward the inner surface of the comer, whereby the deformed angle-type resilient member can apply a restoring force to the at least one side and the adjacent side. In the pellicle frame assembly of the present invention, the restoring-force applying member may comprise an angle-type resilient member that has an angle larger than an angle defined by an outer surface of a comer where the at least one side joins with an adjacent side and is installed such that a central portion thereof is in close contact with the outer surface of the comer. In this case, the restoring-force controlling means may be any means capable of pulling both ends of the angle-type resilient member toward an outer surface of the pellicle frame so that the deformed angle-type resilient member can apply a restoring force to the at least one side and the adjacent side.

Brief Description of Drawings Fig. 1 is an exploded perspective view of a pellicle frame assembly according to an embodiment of the present invention. Fig. 2 is a front view showing an assembled state of the pellicle frame assembly of the embodiment of Fig. 1. Fig. 3 is a sectional view taken along line A- A in the embodiment of Fig. 1, showing fixed states of wires that are restoring-force applying members of the pellicle frame assembly of the present invention. Fig. 4 is a view illustrating other fixed states of wires in a pellicle frame assembly according to an embodiment of the present invention. Fig. 5 is a view illustrating still other fixed states of wires in a pellicle frame assembly according to an embodiment of the present invention. Fig. 6 is a view illustrating fixed states of a restoring-force controlling means and a wire in a pellicle frame assembly according to another embodiment of the present invention. Fig. 7 (a) shows an example of the wires as the restoring-force controlling means in the embodiment shown in Fig. 3, and Fig. 7 (b) is a view illustrating an example of the restoring-force controlling means in the embodiment shown in Fig. 4. Fig. 8 is an exploded perspective view of a pellicle frame assembly according to a further embodiment of the present invention. Fig. 9 is a sectional view taken along line B-B in the embodiment of Fig. 8. Fig. 10 is a sectional view taken along line C-C in the embodiment of Fig. 8. Fig. 11 is a view illustrating fixed states of wires in a pellicle frame assembly according to a still further embodiment of the present invention. Fig. 12 is a perspective view of a pellicle frame assembly according to a still further embodiment of the present invention. Fig. 13 is a sectional view taken along line D-D in Fig. 12. Fig. 14 is a view showing a state where narrow elongated resilient members as the restoring-force applying members are installed in a pellicle frame assembly according to a still further embodiment of the present invention. Fig. 15 is a view showing a state where angle-type resilient members as the restoring-force applying members are installed in a pellicle frame assembly according to a still further embodiment of the present invention. Fig. 16 is a view showing a state where angle-type resilient members as the restoring-force applying members are installed in a pellicle frame assembly according to a still further embodiment of the present invention. Fig. 17 is a perspective view of a conventional pellicle frame.

Best Mode for Carrying out the Invention Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Fig. 1 is an exploded perspective view of a pellicle frame assembly according to an embodiment of the present invention, Fig. 2 is a front view showing an assembled state of the pellicle frame assembly of the embodiment of Fig. 1, and Fig. 3 is a sectional view taken along line A-A in the embodiment of Fig. 1, showing fixed states of wires that are restoring-force applying members of the pellicle frame assembly of the present invention. The pellicle frame assembly 100 of this embodiment comprises a pellicle frame 10, and a pair of wires 20 and 20' for preventing the pellicle frame 10 from being deformed due to tension on a pellicle film (not shown) attached to upper surfaces l ie, 12c, 13c and

14c of the frame 10 or for providing a restoring force to restore the pellicle frame 10 that has been deformed. Further, the pellicle frame assembly comprises adjustment bolts 21, 21', 22 and 22' connected to both ends of each of the wires to control tension on each of the wires. In this embodiment, the pellicle frame 10 takes, but is not limited to, the shape of a rectangle. The pellicle frame 10 comprises a pair of opposite short sides 11 and 13, and a pair of opposite long sides 12 and 14. Connection portions of ends of the respective sides 11, 12, 13 and 14 are referred to as comers 15, 16, 17 and 18. In this embodiment, the pellicle frame 10 is integrally made of aluminum. However, the respective sides of the pellicle frame may be made separately and then assembled with one another. Moreover, outer surfaces l id, 12d, 13d and 14d of the respective sides 11, 12, 13 and 14 are formed with grooves lie, 12e, 13e and 14e along the lengths thereof. A section shown in a dotted circle of Fig. 1 is composed of the upper surface lie, a lower surface 11a, an inner surface l ib and an outer surface lid of the short side 11 with the groove formed therein, the groove lie, and a bottom surface llf of the groove. The other sides has upper surfaces, lower surfaces, inner surfaces, outer surfaces, grooves, and bottom surfaces of the grooves, which are designated by reference numerals assigned in the same manner as the side 11. The wires 20 and 20' are inserted into and installed in grooves 12e and 14e formed in outer surfaces 12d and 14d of the long sides of the pellicle frame 10 in order to prevent interference, respectively. As shown in Figs. 2 and 3, each of the grooves 12e and 14e of the long sides 12 and 14 has wire-supporting members 30' and 31' or 30 and 31 that are inserted thereinto at two positions and fixed by means of bolts 32' and 33' or 32 and 33. The bolts 32', 33', 32 and 33 penetrate the grooves 12e and 14e through through-holes 12g and 14g formed in the lower surfaces 12a and 14a of the long sides and through-holes 30a formed in the wire- supporting members and are then fastened to the long sides 12 and 14 of the frame. Although each of the wire-supporting members 30', 31', 30 and 31 is illustrated as being in the form of a disk with a central through-hole 30a, they are not limited thereto. If the wire-supporting members 30', 31', 30 and 31 are particularly in the form of a disk, they may be rotatably fixed by means of pins instead of the bolts 32', 33', 32 and 33. Further, the wire-supporting members 30', 31', 30 and 31 are fixed such that outer peripheries thereof are spaced apart by a predetermined distance from the bottom surfaces 12f and 14f of the grooves 12e and 14e, thereby securing spaces through which the wires 20' and 20 can pass between the bottom surfaces 12f and 14f of the grooves 12e and 14e and the wire- supporting members 30', 31', 30 and 31, respectively. Moreover, the outer peripheries of the wire-supporting members 30', 31', 30 and 31 are formed with supporting grooves 30'b, 31 'b, 30b and 3 lb are formed to support the wires while preventing the wires from coming out therefrom. As shown in Fig. 3, each of the wires 20 and 20' in this embodiment has one end connected to a first adjustment bolt 21 or 21' and the other end connected to a second adjustment bolt 22 or 22' while passing through the spaces between the bottom surface 14f or 12f of the groove 14e or 12e and the wire-supporting members 30 and 31 or 30' and 31'. Further, the first and second adjustment bolts 21, 21', 22 and 22' are fixed to comers 17, 16, 18 and 15, respectively. Although the wires 20 and 20' are made of piano wires in this embodiment, they are not limited thereto but may be made of any wires with appropriate tensile strength. The tension of the wires 20 and 20' can be controlled by adjusting the lengths of the wires 20 and 20' by means of methods illustrated in Figs. 7 (a) and (b). The method illustrated in Fig. 7 (a) is a method of controlling the tension of the wire 20 by adjusting the height of the adjustment bolt 21. That is, the rotation of the adjustment bolt 21 threadly engaged with a threaded hole 17c formed at the comer 17 causes vertical movement of the adjustment bolt 21. Further, the end of the wire 20 is wrapped one time around an outer periphery of a step portion 21a formed in the adjustment bolt 21 and is then fixed by means of a clip 20a. Since the wire 20 is tightly pulled and strained, it does not droop downward and is not wound around the bolt even though the adjustment bolt 21 is rotated. Therefore, the rotation of the adjustment bolt 21 causes vertical movement of the end of the wire 20, thereby controlling the tension on the wire 20. The method illustrated in Fig. 7 (b) is a method of controlling the tension on the wire 20 by adjusting the length of the wire 20 in such a manner that the wire 20 is wound by rotating a winding shaft 25. That is, the winding shaft 25 is rotatably fixed within the hole 17c formed in the comer 17 by means of a pressing member 23 such that the winding shaft cannot move vertically even though it is rotated. Moreover, the end of the wire 20 is inserted into a through-hole 25a formed in the winding shaft 25 and is then fixed such that it does not come out therefrom by means of a clip 20b. When the winding shaft 25 is rotated, the wire is wrapped around an outer periphery of the winding shaft 25. Thus, the length of the wire is adjusted so that the tension on the wire 20 can be controlled. After the tension has been controlled, the pressing member 23 is fastened by means of bolts 24 to fix the winding shaft 25 so that the wire 20 cannot be unwound. Although this embodiment employs the method of Fig. 7 (a) as the method of controlling the tension on the wires 20 and 20', it may employ the method illustrated in Fig. 1 (b). It will be apparent that those skilled in the art can easily conceive other methods of controlling the tension on the wires in addition to the methods illustrated in the figures. Although not shown in the figures, the tension may be controlled using a guide means for guiding the movement of the wire- supporting member in the groove in which the wire-supporting member is installed, and a fixing means for fixing the wire-supporting member that has been moved under the guidance of the guide means. That is, the tension on the wire can be controlled by adjusting pressure that the wire-supporting member exerts on the wire due to the positional movement of the wire-supporting member. Next, the operation of the pellicle frame assembly of the present invention for preventing deformation due to tension on a pellicle film will be described. After the wires are completely installed in the pellicle frame 10 as described above, a pellicle film (not shown) is attached to the upper surfaces lie, 12c, 13c and 14c of the respective sides by means of an adhesive and an adhesive for use in attaching the pellicle frame to a photomask or reticle is applied to the lower surfaces 11a, 12a, 13a and 14a of the respective sides. When the pellicle film has been attached, forces Tp generated due to the tension of the pellicle film are exerted on the pellicle frame 10 as shown in Fig. 3 and intend to inwardly deform the pellicle frame. The respective sides of the pellicle frame 10 are inwardly compressed and deformed, resulting in reduction in a light exposure area. However, in the pellicle frame assembly 100 of this embodiment, the wires 20 and 20' tightly strained by tension Tw urge the wire-supporting members 30, 31, 30' and 31' outward of the pellicle frame 10 (with a resultant force of forces F that substantially balances with a resultant force of the forces Tp), thereby maintaining the rectangular shape of the pellicle frame 10. As shown in Fig. 3, in the pellicle frame assembly 100 of this embodiment, the distances (levels) from the inner surfaces 12b and 14b of the long sides 12 and 14 to positions where the respective ends of the wires 20' and 20 are connected to the adjustment bolts 21', 22', 21 and 22 are larger (higher) than the distances (levels) from the inner surfaces 12b and 14b of the long sides 12 and 14 to surfaces of the wire-supporting members 30', 31', 30 and 31 facing the bottom surfaces 12f and 14f of the grooves 12e and 14e. Therefore, the rotation of the adjustment bolts 21, 22, 21' and 22' causes the ends of the fixed wires 20 and 20' to move outward of the pellicle frame 10, thereby controlling the tension Tw of the wires. When the adjustment bolts are rotated in an unwinding direction, the tension on the wires 20 and 20' is increased so that the wires 20 and 20', which are in slidable contact with the wire-supporting members 30, 31, 30' and 31', can more strongly urge the wire-supporting members 30, 31, 30' and 31' outward of the pellicle frame 10. At this time, if the tension Tw on the wires is properly controlled such that the sum of the forces F with which the supporting members outwardly push the sides of the frame balances with the sum of the forces Tp with which the pellicle film inwardly pull the frame, it is possible to prevent deformation of the pellicle frame 10 due to the pellicle film. Fig. 4 is a view illustrating other fixed states of wires in a pellicle frame assembly according to an embodiment of the present invention. The embodiment shown in Fig. 4 is different from the embodiment shown in Fig. 3 in that it employs the winding shaft 25 shown in Fig. 7 (b) as a wire tension controlling means to control tension on the wires. Fig. 5 is a view illustrating still other fixed states of wires in a pellicle frame assembly according to an embodiment of the present invention. The embodiment shown in Fig. 5 is different from the embodiments shown in Figs. 3 and 4 in that it employs tumbuckles 40 connected to the wires instead of the adjustment bolts and the winding shafts as a restoring-force controlling means. Since the tumbuckle 40 is a known device for use in controlling tension on a wire, a detailed description thereof will be omitted. Further, wire-fixing bolts 15a, 16a, 17a and 18a are installed at the comers 15, 16, 17 and 18 where ends of the wires are fixed. The ends of the wires fixed by the wire-fixing bolts 15a, 16a, 17a and 18a are installed at levels beyond gaps between the bottom surfaces 12f and 14f of the grooves 12e and 14e and the wire-supporting members 30', 31', 30 and 31. Therefore, when the wires 20' and 20 are subjected to the tension and then tightly strained, the wires 20' and 20 urge the wire-supporting members 30', 31', 30 and 31 outward of the pellicle frame 10. Fig. 6 is a view illustrating fixed states of a restoring-force controlling means and a wire in a pellicle frame assembly 200 according to another embodiment of the present invention. The pellicle frame assembly 200 of the embodiment shown in Fig. 6 is different from the pellicle frame assembly 100 of the embodiment shown in Fig. 5 in that the wire-supporting members are fixed to all the long and short sides and a wire 20 is wrapped one time throughout the grooves formed in the outer surfaces lid, 12d, 13d and 14d of the respective sides 11, 12, 13 and 14 and both ends of the wire are then connected to each other by means of a tumbuckle 40 so as to control tension thereon. Therefore, deformation of the pairs of opposite long sides and short sides can be simply treated by means of a single wire. Wire-guiding members 15a, 15b, 16a, 16b, 17a, 17b, 18a and 18b are formed at the respective comers 15, 16, 17 and 18 to protrude beyond the grooves formed in the respective sides. It will be apparent that without installation of additional wire-guiding members, guiding members may be formed to protrude beyond the grooves when the grooves are machined at the comers. The wire-guiding members 15a, 15b, 16a, 16b, 17a, 17b, 18a and 18b are installed to protrude beyond the gaps between the bottom surfaces llf, 12f, 13f and 14f of the grooves lie, 12e, 13e and 14e and the wire-supporting members 32, 30', 31', 32', 30 and 31. When the wire 20 is tightly strained due to its tension, the tension on the wire urges the wire-supporting members 32, 30', 31', 32', 30 and 31 fixed to the grooves lie, 12e, 13e and 14e outward of the pellicle frame. Fig. 8 is an exploded perspective view of a pellicle frame assembly according to a further embodiment of the present invention, Fig. 9 is a sectional view taken along line B- B in the embodiment of Fig. 8, and Fig. 10 is a sectional view taken along line C-C in the embodiment of Fig. 8. The pellicle frame assembly 300 of the embodiment shown in Fig. 8 is different from the pellicle frame assembly 100 of the embodiment shown in Fig. 1 in that four wires 20 are arranged over the comers 15, 16, 17 and 18 where adjacent long sides 12 and 14 and short sides 11 and 13 join together, and one ends thereof are inserted into the grooves l ie and 13e formed in the short sides 11 and 13 and are fixed therein by means of fixing bolts 50 and the other ends thereof are inserted into the grooves 12e and 14e formed in the long sides 12 and 14 and are fixed to winding shafts 60. The other end of each of the wires 20 is inserted into a hole 61 formed in each of the winding shafts 60, which are rotatably installed at the long sides of the pellicle frame 10, so that the wire 20 can be wrapped around the winding shaft 60 as the winding shaft is rotated, thereby adjusting the length of the wire. Further, the winding shafts 60 are inserted into and rotatably installed in holes 14k formed from the lower surfaces to the upper surfaces of the pellicle frame 10. In addition, the long sides of the pellicle frame 10 are formed with setscrew recesses 14p for use in fixing the winding shafts 60 to prevent the tightly strained wires 20 from being unwound due to the rotation of the winding shafts 60, and setscrews 70 are inserted into the setscrew recesses 14p. To prevent the pellicle frame 10 from being deformed due to the tension on the pellicle film or to restore the deformed pellicle frame, the winding shafts 60 are rotated to shorten the lengths of the wires 20 so that the wires 20 can be tightly strained. When the wires 20 are tightly strained, the wires 20 pull the fixing bolts 50 and the winding shafts 60 connected to the ends of the wires 20 and outwardly stretch the sides of the pellicle 10 adjacent to the comers 15, 16, 17 and 18 with which the wires 20 are in contact. The setscrews 70 then fix the winding shafts 60 such that the winding shafts 60 do not unwind the wires. By straining the wires before the pellicle film is attached to the pellicle frame, deformation of the pellicle frame due to the pellicle film is prevented. Further, by straining the wires after the pellicle film is attached to the pellicle frame, the deformed pellicle frame can be substantially restored to its original state. Fig. 11 is a view illustrating fixed states of wires in a pellicle frame assembly according to a still further embodiment of the present invention. The pellicle frame assembly 400 of the embodiment shown in Fig. 11 is different from the pellicle frame assembly 300 of the embodiment shown in Fig. 8 in that, winding shafts 60 installed at the long sides 12 and 14 are inserted into and rotatably installed in holes 12n and 14n formed from the outer surfaces 12d and 14d to the inner surfaces 12b and 14b of the long sides 12 and 14 of the pellicle frame 10. Further, since the winding shafts 60 and the holes 12n and 14n to which the winding shafts are to be inserted are constructed such that they can be threadly engaged with each other, there is no need for additional setscrews for fixing the winding shafts 60. To prevent the winding shafts 60 from being rotated, additional pressing members may be used in a manner similar to that shown in Fig. 13. Fig. 12 is a perspective view of a pellicle frame assembly according to a still further embodiment of the present invention, and Fig. 13 is a sectional view taken along line D-D in Fig. 12. The pellicle frame assembly 500 of the embodiment shown in Fig. 12 is different from the pellicle frame assembly 300 of the embodiment shown in Fig. 8 in that the winding shafts 60 are fixed by pressing members 75 rather than the setscrews 70. Referring to Fig. 13, each of the pressing members 75 is provided with a though-hole 76 which receives and supports one end of each of the winding shafts 60 and into which a tool for rotating the winding shaft 60 is inserted. The through-hole 76 is tapered and the end of the winding shaft 60 that is to be received within the through-hole 76 is also tapered, so that the end of the winding shaft 60 does not protrude beyond the through-hole 76 and is supported when the corresponding wire 20 is wound through the rotation of the winding shaft 60. Moreover, receiving recesses 14p are formed in the long side 14 of the pellicle frame 10 to accommodate the pressing members 75 such that the pressing members 75 do not protrude outwardly. A spring 78 is installed between the receiving recess 14p and the pressing member 75 received therein, so that the pressing member 75 is spaced apart from the winding shaft 60 and thus the winding shaft 60 can be easily rotated when the winding shaft 60 is not pressed by the pressing member 75. Further, an outer periphery of the winding shaft 60 with a through-hole 61 formed therein is provided with an annular groove 62 to receive the wire wound thereon. Therefore, after the wire 20 is wound and strained through the rotation of the winding shaft 60, fixing bolts 77 are fastened to the long side 14 to press the pressing member 75 so as to fix the winding shaft 60 and maintain the wire 20 in the strained state. Even in the embodiments shown in Figs. 8 and 12, it is preferred that the bottom surface llf of the groove lie formed in the short side 11 of the pellicle frame 10 be provided with an additional groove 13m in a lengthwise direction from a position where one end of the wire 20 is fixed to the comer so that the wire 20 can be inserted thereinto without protruding beyond the bottom surface l lf of the groove lie, in the same manner as the embodiment shown in Fig. 11. Fig. 14 is a view showing a state where narrow elongated resilient members as the restoring-force applying members are installed in a pellicle frame assembly according to a still further embodiment of the present invention. The pellicle frame assembly 600 of this embodiment is different from the aforementioned embodiments in that instead of the wires, narrow elongated resilient members 80 with strength larger than that of the pellicle frame are used as the restoring-force applying members. Each of the outer surfaces 12d and 14d of the long sides 12 and 14 on which restoring forces are to be exerted is formed with two step portions 12-1 and 12-2 or 14-1 and 14-2 to reach the comers where the long sides join with the adjacent short sides 11 and 13 so that the narrow elongated resilient members 80 fixed therein cannot protrude outwardly. One end of each of the narrow elongated resilient members 80 is fixed to the first step portion 12-1 or 14-1 by means of a fixing bolt 81, and the other end thereof is positioned above the second step portion 12-2 or 14-2 extending to the corresponding comer 15, 16, 17 or 18. To apply the restoring forces to the long sides and control the restoring forces, adjustment bolts 82 penetrate through free ends of the narrow elongated resilient members 80 and fix them to the adjacent short sides 11 and 13 such that level adjustment can be performed. When the adjustment bolts 82 are tightened to urge and deform the free ends of the narrow elongated resilient members 80 toward the comers, the restoring forces are exerted on the long sides 12 and 14 to which the other ends of the narrow elongated resilient members are fixed, thereby restoring the deformed pellicle frame 10. Moreover, since the deformation of the narrow elongated resilient members 80 pulls the adjustment bolts 82 from the comers toward the sides, the adjustment bolts 82 apply outward bending moment to the short sides 11 and 13 so that forces for outwardly deforming the short sides are exerted thereon. Fig. 15 is a view showing a state where angle-type resilient members as the restoring-force applying members are installed in a pellicle frame assembly according to a still further embodiment of the present invention. The pellicle frame assembly 700 of this embodiment is different from the pellicle frame assembly 600 of the embodiment shown in Fig. 14 in that instead of the narrow elongated resilient members 80, angle-type resilient members 83 are used as the restoring-force applying members. The angle-type resilient members 83 have angles larger than included angles defined by inner surfaces of the comers 15, 16, 17 and 18 where the long sides 12 and 14 and the short sides 11 and 13 join each other, and are installed such that opposite ends thereof are in close contact with the inner surfaces of the comers 15, 16, 17 and 18. Receiving recesses 19a are formed in the inner surfaces of the comers 15, 16, 17 and 18 to receive the opposite ends of the angle- type resilient members 83 such that the opposite ends do not protrude inwardly. The width of each of the angle-type resilient members 83 is smaller than that of the receiving recess 19a, and the width of the receiving recess is smaller than that of the inner surface of the pellicle frame. The receiving recesses 19a are formed to reside in the inner surfaces of the comers. Each of the comers 15, 16, 17 and 18 is formed with a threaded through- hole 19b to which the adjustment bolt 84 is fastened. The end of the adjustment bolt 84 is rotatably fixed (connected) to a central portion of the angle-type resilient member 83 through the through-hole 19b. Therefore, when the adjustment bolts 84 are unscrewed to move outward of the pellicle frame, the angle-type resilient members 83 are pulled and deformed toward the inner surfaces of the comers 15, 16, 17 and 18. The deformed angle-type resilient members 83 apply the restoring forces to the short and long sides on both sides of the comers 15, 16, 17 and 18. Fig. 16 is a view showing a state where angle-type resilient members as the restoring-force applying members are installed in a pellicle frame assembly according to a still further embodiment of the present invention. The pellicle frame assembly 800 of this embodiment is different from the pellicle frame assembly 700 of the embodiment shown in Fig. 15 in that angle-type resilient members 85 are installed on outer surfaces of the comers 15,16, 17 and 18. Referring to Fig. 16, the angle-type resilient members 85 have angles larger than external angles defined by the outer surfaces of the comers 15, 16, 17 and 18 where the long sides 12 and 14 and the short sides 11 and 13 join each other, and are installed such that bent central portions thereof are in close contact with the outer surfaces of the comers 15, 16, 17 and 18. Receiving recesses 19c are formed in the outer surfaces of the comers to receive the angle-type resilient members 85. A pair of adjustment bolts 86 are installed in a height-adjustable manner at the long side 12 or 14 and the short side 11 or 13 to press both ends of each of the angle-type resilient members

85. When the both ends of the angle-type resilient member 85 are pressed by adjusting the heights of the adjustment bolts 86, the elastic restoring force of the deformed angle- type resilient member 85 is transmitted to the respective sides through the adjustment bolts

86, thereby restoring the deformed pellicle frame. It is intended that the embodiments of the present invention described above and illustrated in the drawings should not be construed as limiting the technical spirit of the present invention. The scope of the present invention is defined only by the appended claims. It is apparent that those skilled in the art can make various changes and modifications thereto. Therefore, such changes and modifications fall within the scope of the present invention so far as they are obvious to those skilled in the art.

Industrial Applicability According to the present invention, there is provided a pellicle frame assembly capable of preventing deformation in a large-sized pellicle frame due to tension on a pellicle film, thereby enabling a larger semiconductor device to be fabricated. With the present invention, the deformation of the pellicle frame due to the tension on the pellicle film is prevented or the deformed pellicle frame is restored by wires or resilient members. Therefore, it is possible to prevent reduction in a light exposure area due to the deformation of the pellicle frame upon manufacture of a large-sized TFT LCD, so that a larger LCD can be manufactured as compared with the use of a conventional pellicle frame.

Claims

1. A pellicle frame assembly, comprising: a pellicle frame with a plurality of sides for supporting a pellicle film in a substantially flat state, the pellicle film having an edge attached to an upper surface of the pellicle frame; and at least one restoring-force applying member installed at the pellicle frame to apply a restoring force for restoring deformation of the pellicle frame due to tension of the pellicle film attached to the upper surface to at least one of the sides of the pellicle frame.

2. The pellicle frame assembly according to Claim 1, further comprising: a restoring-force controlling means connected to the at least one restoring-force applying member to control the restoring force applied to the at least one side of the pellicle frame.

3. The pellicle frame assembly according to Claim 2, wherein the restoring-force applying member is a wire, one end of the wire is fixed to the at least one side while the wire is installed along the length of the side, and the other end of the wire is connected to the restoring-force controlling means to control tension of the wire acting as the restoring force.

4. The pellicle frame assembly according to Claim 3, wherein the restoring-force control means comprises a winding shaft rotatably installed at the pellicle frame to adjust the length of the wire by winding the other end of the wire connected thereto, and a winding-shaft fixing means for preventing the winding shaft from being rotated.

5. The pellicle frame assembly according to Claim 4, wherein the winding shaft is inserted into and rotatably installed in a hole formed from an outer surface to an inner surface of the pellicle frame, and the winding-shaft fixing means comprises a pressing member for fixing the winding shaft by radially pressing the winding shaft.

6. The pellicle frame assembly according to Claim 4, wherein the winding shaft is inserted into and rotatably installed in a hole formed from a lower surface to the upper surface of the pellicle frame, and the winding-shaft fixing means comprises a pressing member for fixing the winding shaft by axially pressing the winding shaft.

7. The pellicle frame assembly according to Claim 5 or 6, wherein the winding shaft is installed at a side adjacent to the side with the one end of the wire fixed thereto.

8. The pellicle frame assembly according to Claim 7, wherein each wire and the winding shaft installed at opposite comers is symmetrical with each other.

9. The pellicle frame assembly according to any one of Claims 3 to 8, wherein an outer surface of the side of the pellicle frame in which the wire is installed is formed with a groove along the length of the side, and the wire is inserted into and installed in the groove such that the wire does not protmde outwardly.

10. The pellicle frame assembly according to Claim 2, wherein the restoring-force applying member is a wire installed along the length of the at least one side, and the connection of the wire to the side of the pellicle frame is made such that relative movement can be performed in a slidable manner when tension of the wire is controlled by the restoring-force controlling means.

11. The pellicle frame assembly according to Claim 10, wherein an outer surface of the side of the pellicle frame in which the wire is installed is formed with a groove along the length of the side, the pellicle frame assembly further comprises at least one wire-supporting member inserted into and fixed in the groove while being spaced apart by a predetermined from a bottom surface of the groove, one end of the wire is fixed to a comer where one end of the at least one side joins with an adjacent side, and the other end thereof passes through a space between the bottom surface of the groove and the wire-supporting member and is then fixed to a comer where the other end of the adjacent side joins with an adjacent side, and a height from an inner surface of the side with the wire-supporting member fixed thereto to positions where the respective ends of the wire are fixed is larger than a height from the inner surface of the side with the wire-supporting member fixed thereto to a surface of the wire-supporting member facing the bottom surface of the groove.

12. The pellicle frame assembly according to Claim 10, wherein an outer surface of each of the sides of the pellicle frame is formed with a groove along the length of the side, the pellicle frame assembly further comprises at least one wire-supporting member inserted into and fixed in at least one of the grooves formed in the sides while being spaced apart by a predetermined from a bottom surface of the groove, one end of the wire passes through a space between the bottom surface of the groove and the wire-supporting member and is then connected to the other end of the wire while the wire surrounds the frame along the grooves, and a distance from an inner surface of the side with the wire-supporting member fixed thereto to a comer of a side with which the wire is in contact is larger than a distance from the inner surface of the side with the wire-supporting member fixed thereto to a surface of the wire-supporting member facing the bottom surface of the groove.

13. The pellicle frame assembly according to Claim 2, wherein a step portion is formed at a portion of an outer surface of at least one of the sides to which the restoring force applied, extending to a comer where the side joins with an adjacent side, the restoring-force applying member is a narrow elongated resilient member with strength larger than that of the pellicle frame, the narrow elongated resilient member having one end fixed to an outer surface of at least one of the sides and the other end as a free end extending to the comer formed with the step portion, and the restoring-force controlling means comprises an adjustment bolt installed at the adjacent side to press the other end of the narrow elongated resilient member toward a lower portion of the comer formed with the step portion.

14. The pellicle frame assembly according to Claim 2, wherein the restoring-force applying member comprises an angle-type resilient member with an angle larger than an angle defined by an inner surface of a comer where the at least one side joins with an adjacent side, the angle-type resilient member being installed such that both ends thereof are in close contact with the inner surface of the comer, and the restoring-force controlling means comprises an adjustment bolt having one end connected to the angle-type resilient member, the adjustment bolt being installed at the pellicle frame to pull the angle-type resilient member toward the inner surface of the comer so that the deformed angle-type resilient member can apply a restoring force to the at least one side and the adjacent side.

15. The pellicle frame assembly according to Claim 2, wherein the restoring-force applying member comprises an angle-type resilient member with an angle larger than an angle defined by an outer surface of a comer where the at least one side joins with an adjacent side, the angle-type resilient member being installed such that a central portion thereof is in close contact with the outer surface of the comer, and the restoring-force controlling means is installed at the pellicle frame to pull both ends of the angle-type resilient member toward an outer surface of the pellicle frame so that the deformed angle-type resilient member can apply a restoring force to the at least one side and the adjacent side.