JP2011118117A - Pellicle and method for mounting the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for mounting a pellicle having air permeability capable of coping with a pressure change in the ambient atmosphere without inducing the deposition of a foreign substance on a photomask, in which the bulge of the pellicle film caused by involved air upon sticking the pellicle to the photomask can be quickly eliminated to restore the flatness of the film to an original state. <P>SOLUTION: The pellicle 1 includes a frame 2, an adhesive layer 3 layered on a lower edge face of the frame 2, and a pellicle film 4 stretched and adhered to an upper edge face of the frame 2, and has a first through hole 5 to which a filter 8 is attached, and a second through hole 6 to which a filter or a sealing material is detachably attached on a side face of the frame 2. The method for mounting the pellicle 1 on a photomask 7 comprises steps for: sticking the pellicle 1 to the photomask 7 with the adhesive layer 3; detaching the filter or a sealing material from the second through hole 6; and attaching a filter or the sealing material to the second through hole 6 after the recovery of the amount of bulging in the center of the pellicle film 4 to a predetermined value or lower. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a pellicle used for preventing foreign matter from adhering to a photomask (or reticle) used in a lithography process when manufacturing a thin film transistor, a color filter, and the like, and a method for attaching the pellicle to the photomask. .

  Conventionally, in a photolithography process for forming a circuit pattern of a semiconductor element, a dust mask means generally called a pellicle is used to form a photomask or a reticle (in this specification, these are referred to as “photomask” without distinction). ) Has been proposed and put into practical use.

  The pellicle has a shape corresponding to the shape of the photomask (generally, a quadrilateral shape) on the upper edge surface of a frame having a thickness of about several millimeters, a nitrocellulose having a thickness of 10 μm or less, a cellulose derivative, a fluoropolymer, etc. A transparent polymer film (hereinafter referred to as “pellicle film”) is stretched and bonded, and an adhesive material layer is laminated on the lower edge surface of the frame by coating or the like. Usually, the adhesive layer is protected by laminating a protective film until the pellicle is actually used.

  Such a pellicle is generally supplied from a manufacturer that manufactures the pellicle to a manufacturer that manufactures a photomask, and is attached to the photomask through an adhesive layer. Normally, the pellicle is stuck and attached to the photomask so that foreign matter does not enter from the sticking part, so that the closed space surrounded by the pellicle and the photomask is not permeable to the external space. Pellicles, on the other hand, are normally used in a clean room with controlled temperature and humidity in an atmospheric pressure atmosphere, but the atmospheric pressure due to changes in altitude due to movement of the place of use or changes in weather such as the approach of low pressure. May be affected by change.

  In other words, if there is no air permeability between the closed space surrounded by the pellicle and photomask and the outside, the atmospheric pressure of such atmosphere changes the central part of the pellicle film relative to the peripheral part in contact with the frame. The flatness of the pellicle film fluctuates as it swells outward or conversely inwards. As a result, for example, when the pellicle film bulges outward and the pellicle film comes into contact with a part of the exposure apparatus or when a foreign matter inspection on the pellicle film is performed on the photomask with the pellicle attached, Problems such as erroneous detection due to out of focus may occur.

  To solve this problem, adjust the air pressure on the side of the frame of the pellicle to eliminate the pressure difference between the closed space surrounded by the pellicle and the photomask and the external space when the pellicle is attached to the photomask. A technique for opening a ventilation hole has been proposed (see Patent Document 1). In such a technique, in order to prevent foreign matter from entering from the air entering and exiting from the external space into the closed space through the vent hole, a device such as a filter is installed in the vent hole.

  In addition, in the pellicle for a semiconductor element, a vent hole is provided on the side surface of the frame of the pellicle in order to eliminate the pressure difference between the closed space formed by the pellicle and the photomask and the external space, and the vent hole is formed with tape. A pellicle having a structure in which an opening is sealed so as to be opened and closed has been proposed (see Patent Document 2). In such a technique, it is normally intended to eliminate the pressure difference between the closed space and the external space by using the pellicle with the opening of the pellicle sealed and peeling off the tape when the pressure changes.

  Furthermore, in recent years, a technique for providing a vent hole in an oblique direction toward the side surface of the frame body so that foreign matter does not easily enter from the opening portion of the vent hole (see Patent Document 3). (See Patent Document 4), technology for performing ventilation into the closed space formed by the pellicle and photomask and ventilation outside the closed space separately by two vent holes provided with valves (patent) Document 5) has been proposed. In addition, as a filter that achieves both foreign matter capture performance and ventilation performance, a filter that takes 5 to 180 minutes to restore the swollen pellicle membrane to its original state when the atmospheric pressure is reduced and held. There has been proposed a pellicle that is selected and this filter is attached to a vent (see Patent Document 6).

Japanese Utility Model Publication No. 63-39703 Japanese Patent Laid-Open No. 02-244046 Japanese Patent Laid-Open No. 05-11658 Japanese Patent Laid-Open No. 02-250055 Japanese Patent Laid-Open No. 06-27643 JP 2000-305253 A

  By the way, especially in a large-sized pellicle, a new problem has arisen with further increase in size in recent years. That is, when a large pellicle is attached to the photomask, regardless of the atmospheric pressure change, as a result of surrounding air being attached and attached, the center of the pellicle film is applied to the peripheral part in contact with the frame. On the other hand, there is a problem that it may be swollen.

  In general, since the amount of air entrained at the time of application is much larger than the amount of expansion and contraction of air in the closed space due to the atmospheric pressure change described above, the amount of swelling of the pellicle film often increases. On the other hand, considering the production tact, it is preferable to quickly restore the original state after pasting even if the amount of swelling is large. In the case of a pellicle for a semiconductor element having a small area of the pellicle film, even if the central part of the pellicle film swells due to air entrainment when affixed to the photomask, a vent hole having a conventionally known filter By providing a plurality of frames on the frame, the flatness of the pellicle film can be restored to the original state as quickly as possible, and the production tact has not been a problem.

However, the area of the pellicle film is 6000 cm ² or more, more comes to 15000 cm ² or more large pellicle, since the volume of air engulfed during pasting increases in proportion to the area of the pellicle membrane, at the central portion pasted to the photomask It takes a considerable amount of time to restore the flatness of the pellicle film in which the swells to the original state, and there is a new problem that the production tact becomes long.

In other words, by providing a ventilation hole with a filter in the frame, the pellicle does not flow foreign matter into the closed space against the expansion and contraction of the air in the closed space surrounded by the pellicle and the photomask due to atmospheric pressure changes. The flatness of the film can be maintained. However, since the air outflow speed from the vent hole is reduced due to the ventilation resistance of the filter, in the case of a large pellicle having a pellicle film area of 6000 cm ² or more, the center of the pellicle film by the air entrained when the pellicle is attached to the photomask It takes a lot of time to eliminate the swelling of the part and restore the flatness to the original state.

  On the other hand, if the frame is provided with ventilation holes that do not have a filter, the air outflow speed is high, eliminating the swelling of the central part of the pellicle film due to the air entrained when the pellicle is attached to the photomask, thereby restoring flatness. Although it takes less time to recover to this state, foreign matter may flow from the vents due to changes in atmospheric pressure. As measures against foreign matters other than the filter, there are means such as making the shape of the vent hole non-linear or applying an adhesive material for trapping foreign matter on the inner surface of the vent hole, but it is not perfect.

  The present invention has been made in view of such circumstances, and has a breathability that can cope with a change in the pressure of the surrounding atmosphere without causing foreign matter adhesion to the photomask, and also a pellicle made of air entrained when affixed to the photomask It is an object of the present invention to provide a method for attaching a pellicle that can quickly eliminate swelling at the center of the film and restore flatness to its original state.

  As a result of diligent studies to achieve the above object, the present inventor has a first through hole with a filter for coping with a change in atmospheric pressure on the side surface of the frame, and a pellicle to the photomask. The present invention has been completed by finding that this can be achieved by a large pellicle having a second through-hole for quickly releasing the air entrained at the time of pasting from the closed space between the pellicle and the photomask to the external space.

  A first pellicle according to the present invention is a pellicle comprising a frame, an adhesive layer laminated on the lower edge surface of the frame, and a pellicle film stretched and bonded to the upper edge surface of the frame. And having a first through hole to which the first filter is attached and a second through hole to which the second filter is attached on a side surface of the frame body, and the pressure loss of the second filter is It is set smaller than the pressure loss of the first filter.

  The first attachment method according to the present invention is a method of attaching the first pellicle to the photomask, the step of attaching the first pellicle to the photomask with an adhesive layer, and the center of the pellicle film And a step of attaching a sealing material to the second through hole after the swelling amount of the portion has recovered to a predetermined value or less.

  By adopting such a configuration and method, the first through hole to which the first filter having a relatively large pressure loss is attached allows air permeability to cope with the atmospheric pressure change of the surrounding atmosphere when the pellicle is attached to the photomask. Can be secured. In addition, the second through-hole with a second filter with relatively low pressure loss allows the air entrained when the pellicle is affixed to the photomask to be quickly released from the closed space between the pellicle and the photomask to the external space. Thus, the swelling of the central portion of the pellicle film can be quickly eliminated to restore the flatness to the original state.

  A second pellicle according to the present invention is a pellicle comprising a frame, an adhesive layer laminated on the lower edge surface of the frame, and a pellicle film stretched and bonded to the upper edge surface of the frame. The first through hole when the filter is attached and the second through hole with the openable / closable ventilation means are provided on the side surface of the frame body.

  A second attachment method according to the present invention is a method of attaching the second pellicle to the photomask, wherein the openable / closable ventilation means is closed and the second pellicle is made into a photomask with an adhesive layer. A step of attaching, a step of opening the openable / closable venting means, and a step of closing the openable / closable venting means after the swelling amount of the central portion of the pellicle membrane is restored to a predetermined value or less.

  When such a configuration and method are employed, the first through hole to which the filter is attached can ensure air permeability to cope with the atmospheric pressure change in the surrounding atmosphere when the pellicle is attached to the photomask. In addition, by opening the openable / closable means for the second through-hole after attaching the pellicle to the photomask, the air trapped when the pellicle is affixed to the photomask is removed from the closed space between the pellicle and the photomask. It can be quickly released into the space, and the swelling of the central part of the pellicle film can be quickly eliminated to restore the flatness to the original state. The flatness of the pellicle film can be maintained by closing the openable / closable ventilation means after the flatness of the pellicle film is restored.

  The third attachment method according to the present invention includes a frame, an adhesive layer laminated on the lower edge surface of the frame, and a pellicle film stretched and bonded to the upper edge surface of the frame. A pellicle having a first through-hole to which a filter is attached and a second through-hole to which a filter or a sealing material is detachably attached is attached to a photomask. And attaching the pellicle to the photomask with an adhesive layer, removing the filter or sealing material from the second through-hole, and the swelling amount of the central portion of the pellicle film recovered to a predetermined value or less. And attaching a filter or a sealing material to the second through-hole later.

  When such a method is employed, the first through hole to which the filter is attached can ensure the air permeability for coping with the atmospheric pressure change in the surrounding atmosphere when the pellicle is attached to the photomask. Also, by removing the filter or sealing material of the second through-hole after attaching the pellicle to the photomask, the air trapped when attaching the pellicle to the photomask is quickly transferred from the closed space between the pellicle and the photomask to the external space. And the flatness can be restored to the original state by quickly eliminating the swelling at the center of the pellicle film. Then, after the flatness of the pellicle film is restored, the flatness can be maintained by attaching a filter or a sealing material to the second through hole.

In the first and second pellicles, the total area of the openings of the first through holes on the side surfaces of the frame is preferably set to 0.1 mm ² or more and 10 mm ² or less per 1000 cm ² of the area of the pellicle film. In the first and second pellicles, the total area of the openings of the second through holes on the side surfaces of the frame body may be set to 0.6 mm ² or more and 30 mm ² or less per 1000 cm ^{2 of the} pellicle film area. preferable.

If the total area of the openings of the first through-hole is 0.1 mm ² or more per 1000 cm ^{2 of the} pellicle membrane area, the flatness of the pellicle membrane may be lowered when the filter has a foreign matter capturing ability and the pressure changes. Can be followed. Further, when the total area of the openings of the second through-hole is 0.6 mm ² or more per 1000 cm ^{2 of the} pellicle membrane area, the closed space between the pellicle and the photomask that is stuck with air is attached. The flatness of the pellicle film can be returned to the original state by quickly discharging air to the external space. If the sum of the total area of the openings of the first through holes 5 and the total area of the openings of the second through holes 6 is 40 mm ² or less per 1000 cm ² of the area of the pellicle film 4, The strength is maintained, which is preferable.

  According to the present invention, air permeability that can cope with a change in the pressure of the surrounding atmosphere without causing foreign matter adhesion to the photomask and rapid expansion of the central portion of the pellicle film due to air entrained when pasting to the photomask are achieved. It is possible to provide a method for attaching a pellicle that can be eliminated to restore the flatness to the original state.

It is a perspective view which shows the structure of the pellicle which concerns on this invention. It is sectional drawing of the II-II part of FIG.

Hereinafter, a pellicle and an attachment method thereof according to an embodiment of the present invention will be described with reference to the drawings. The present invention, as the area of the pellicle film increases exerts a remarkable effect, in particular, the area of the pellicle film is 6000 cm ² or more, a marked effect in particular when the 15000 cm ² or more. As described above, the present invention has a remarkable effect as the area of the pellicle film increases. However, since the size required for a photomask used for manufacturing a TFTLCD (thin film transistor liquid crystal display) at the present time, An example of the upper limit of the area is 40000 cm ² . Note that the area of the pellicle film is an area determined by the inner dimensions of the frame body to which the pellicle film is bonded, and does not include the area of the width portion of the frame body.

  First, the configuration of the pellicle 1 according to the present embodiment will be described with reference to FIGS. 1 and 2. The pellicle 1 includes a frame body 2, an adhesive material layer 3 laminated on the lower edge surface of the frame body 2, and a pellicle film 4 stretched and bonded to the upper edge surface of the frame body 2. The pellicle film 4 is usually bonded to the upper edge surface of the frame body 2 via an adhesive layer (not shown). A protective film (not shown) for protecting the adhesive material (hereinafter sometimes referred to as “liner”) is laminated on the surface of the adhesive material layer 3. When the pellicle 1 is attached to the photomask 7, the liner is removed and the pellicle 1 is brought into close contact with the photomask 7.

  First, the first through hole 5 of the pellicle 1 according to this embodiment will be described. The frame 2 is provided with a first through hole 5 on a side surface. When the pellicle 1 is attached to the photomask 7, the first through-hole 5 expands and contracts due to air pressure fluctuations (or temperature and humidity fluctuations) in the surrounding environment caused by the air in the closed space formed between the pellicle 1 and the photomask 7 This is a pressure adjusting through hole for preventing the flatness of the pellicle film 4 from being lowered.

  The dimension of the opening of the first through hole 5 (diameter in the case of a circle, circumscribed circle in the case of a polygon) is the height of the frame 2 (dimension from the lower edge to the upper edge) and the frame. 2 can be set as appropriate in consideration of the material 2 and the like. For example, when the height of the frame body 2 is about 6 mm, the size of the opening of the first through hole 5 is preferably smaller than 2 mm so that the strength of the frame body 2 can be maintained. If the strength of the frame 2 is lowered, when the pellicle 1 is stuck to the photomask 7 for a long period of time, an air path may enter the sticking portion or deformation may occur, which is not preferable.

Although the number of the first through holes 5 may be singular or plural, the total area of the openings of the first through holes 5 on the side surface of the frame 2 is 0.1 mm ² or more per 1000 cm ² of the area of the pellicle film 4. It is preferable. If the total area is 0.1 mm ² or more per 1000 cm ² of the area of the pellicle film 4, it is possible to follow the decrease in flatness of the pellicle film 4 when the pressure changes, when a filter having a foreign substance capturing ability is attached. Further, if the sum of the total area of the openings of the first through holes 5 and the total area of the openings of the second through holes 6 described later is 40 mm ² or less per 1000 cm ² of the area of the pellicle film 4, The strength of the frame 2 is maintained. At this time, it is more preferable that the sum of the total areas of the openings of the first through-hole 5 is 10 mm ² or less per 1000 cm ² of the area of the pellicle film 4.

  The first through-hole 5 may be single or plural, but for pressure adjustment in the case of a large pellicle with a large area, the first through-hole 5 is plural, and the area per one is small and the total area is large. More preferably. The first through-hole 5 may be provided anywhere on the side of the frame 2 as long as it excludes the portion to be gripped when the frame 2 is attached to the photomask 7. It is preferable in view of the strength of the frame 2 to be provided near the center of the direction. When the frame 2 is a quadrilateral, the first through holes 5 may be provided only on the two long sides or only the two short sides of the frame 2, or only one long side or the short side. It may be provided only on one side or on all four sides.

  In the first through-hole 5, it is necessary to allow air to enter and exit between the closed space formed between the pellicle 1 and the photomask 7 and the external space. For this reason, it is preferable to apply a foreign material capturing adhesive to the inner wall of the first through-hole 5 or attach a filter 8 to the through-hole 5. It is more preferable to attach the filter 8 to the first through hole 5 from the viewpoint of the foreign matter capturing effect.

  As a method for attaching the filter 8, a form in which the filter 8 is packed inside the first through hole 5 may be used, or a form in which the filter 8 is attached to the opening of the through hole 5 on the side surface of the frame body 2 may be used. A method of sticking a film-like filter having a size slightly larger than the opening of the through hole 5 around the opening of the through hole 5 with an adhesive is preferable because the filter can be easily attached.

  As the preferable filter 8, it is necessary to select a filter having an appropriate pore size in terms of a balance between foreign matter capturing ability and air permeability, and an average pore size of 0.1 μm or more and 10 μm or less is preferable. When the average pore diameter is 0.1 μm or more, the following performance against atmospheric pressure fluctuation is excellent, and when the average pore diameter is 10 μm or less, the dustproof performance is high.

  Examples of the material of the filter 8 include resins such as polytetrafluoroethylene (PTFE) and nylon 66, metals such as 316L stainless steel, ceramics such as alumina and aluminum nitride, and anyway, the filter 8 is porous. As long as it has air permeability, it is not particularly limited.

  The adhesive material for attaching the filter 8 to the frame 2 is the frame when the inner surface of the filter 8, that is, the filter 8 is attached to the frame 2 of the pellicle 1 so as to cover the opening of the first through hole 5. It is formed by applying an adhesive material around the surface on the second side so as not to crush the opening. Examples of the material forming the adhesive material include a double-sided adhesive tape, a silicone resin adhesive material, and an acrylic adhesive.

  In addition, the filter 8 may be laminated with a filter protective material for protecting against mechanical shock and physical external pressure on the outer surface of the filter body. As the filter protective material, a porous plastic sheet having appropriate strength, cushioning properties and air permeability is preferably used, and examples of the material include silicone resin, polyethylene, polypropylene, and polyurethane.

  Next, the second through hole 6 of the pellicle 2 according to this embodiment will be described. In addition to the first through hole 5 described above, a second through hole 6 is provided on the side surface of the frame body 2. The second through-hole 6 has a lower flatness of the pellicle film 4 due to air entrainment when the pellicle 1 is attached to the photomask 7, that is, the center part of the pellicle film 4 swells larger than the vicinity of the frame 2. This is a through hole for quickly recovering the state of being adhered to the photomask 7 in a state of being recovered to the original state and flattening it.

  The dimension of the opening of the second through hole 6 (diameter in the case of a circle, circumscribed circle in the case of a polygon) is appropriately set in consideration of the height of the frame 2, the material of the frame 2, and the like. However, it is more preferable to have the same dimension as the first through hole 5 or more. For example, when the height of the frame body 2 is about 6 mm, it is preferable to set the size of the opening of the second through hole 6 to 3 mm or less so that the strength of the frame body 2 can be maintained. If the strength of the frame is lowered, when the pellicle 1 is stuck to the photomask 7 for a long period of time, an air path enters the sticking portion or deformation is likely to occur, which is not preferable. Further, it is not preferable to increase the area of the second through-hole 6 any more because the probability that foreign matter enters during the restoration of the flatness of the pellicle film 4 is increased.

Although the number of the second through holes 6 may be singular or plural, the total area of the openings of the second through holes 6 on the side surface of the frame 2 is 0.6 mm ² or more and 30 mm per 1000 cm ² of the area of the pellicle film 4. It is preferably ² or less. More preferably 0.96 mm ² or more 12.6 mm ² or less per unit area 1000 cm ² of the pellicle film 4, further preferably 1.62 mm ² or more 10.3 mm ² or less. If the total area is 0.6 mm ² or more, the air is quickly discharged from the closed space between the pellicle 1 and the photomask 7 attached with the air into the external space, and the pellicle film 4 is flat. Can be restored to its original state. As described above, if the sum of the total area of the openings of the first through holes 5 and the total area of the openings of the second through holes 6 is 40 mm ² or less per 1000 cm ² of the area of the pellicle film 4, The strength of the frame 2 is maintained. At this time, it is more preferable that the total area of the openings of the second through-hole 6 is 30 mm ² or less per 1000 cm ² of the area of the pellicle film 4.

  The position where the second opening 6 is provided may be provided anywhere on the side of the frame 2 as long as it excludes the portion to be gripped when the frame 2 is attached to the photomask 7. It is preferable in terms of strength of the frame body 2 to be provided near the center in the vertical direction. When the frame 2 is a quadrilateral, the second through-hole 6 may be provided only on two long sides or only two short sides of the frame 2, or only one long side or short side. It may be provided only on one side or on all four sides.

  The purpose of the second through hole 6 is to release the air entrained from the closed space formed between the pellicle 1 and the photomask 7 to the external space. The outflow speed is preferably larger than the first through-hole 5, the speed ratio is more preferably 10 times or more, and further preferably 100 times or more.

  In the second through-hole 6, no filter is attached to improve the air outflow speed from when the pellicle 1 is attached to the photomask 7 until the flatness of the pellicle film 4 is restored to the original state. Alternatively, it is preferable to attach a filter having a pressure loss smaller than that of the filter attached to the first through hole 5. It is also preferable to provide an adhesive layer for capturing foreign matter on the inner surface of the second through-hole 6. Examples of the material for forming the adhesive layer include a silicone resin adhesive and an acrylic adhesive. The pressure loss of the filter can be measured by the method specified in JISK3803.

  The second through-hole 6 exhibits the above function from the time when the pellicle 1 is attached to the photomask 7 until the flatness of the pellicle film 4 is restored to the original state. Therefore, a removable filter or sealing material is attached to the opening of the second through-hole 6 until the pellicle 1 is attached to the photomask 7, and immediately before or after the pellicle 1 is attached to the photomask 7. The filter or sealing material may be removed. After the flatness of the pellicle film 4 is restored to its original state, it is preferable to attach a filter or a sealing material to the second through-hole 6 again in order to prevent foreign matter from entering.

  Here, as a sealing material to be attached to the second through hole 6 and an attaching method thereof, a method of attaching a non-breathable film made of resin or metal foil to the opening of the second through hole 6 with an adhesive. And a method of filling the second through-hole 6 with an adhesive, a curable adhesive, putty, solder, or the like.

  Further, an openable / closable ventilation means (for example, a cock or a check valve) is attached to the second through-hole 6 and the openable / closable ventilation attached to the second through-hole 6 until the pellicle 1 is attached to the photomask 7. The opening / closing venting means is opened immediately before or after the pellicle 1 is attached to the photomask 7 with the means closed, and the opening / closing ventilation is possible after the flatness of the pellicle film 4 is restored to the original state. The means may be closed.

  Subsequently, materials other than the through holes 5 and 6 and materials and manufacturing methods that constitute the pellicle 1 according to the present embodiment will be described.

  The material for forming the pellicle film 4 is not particularly limited as long as it is a material that allows light to pass well. For example, cellulose derivatives (nitrocellulose, cellulose acetate, cellulose acetate propionate, cellulose acetate butyrate, etc. Or a mixture of two or more of these), a fluorine-based polymer (tetrafluoroethylene-vinylidene fluoride-hexafluoropropylene terpolymer, Teflon (registered trademark) AF manufactured by DuPont, which is a polymer having a cyclic structure in the main chain), Polymers such as CYTOP (registered trademark) manufactured by Asahi Glass Co., Ltd. and Algoflon (registered trademark) manufactured by Augmont can be used. Cellulose acetate propionate and cellulose acetate butyrate are preferably used for the ultra-high pressure mercury lamp, which is the light source of the currently used batch exposure liquid crystal exposure machine, from the viewpoint of light resistance and cost.

  The thickness of the pellicle film 4 is preferably about 0.5 μm to 10 μm. In the pellicle 1 according to this embodiment, the thickness of the pellicle film 4 and the ease of forming a uniform film are preferably 2 μm to 8 μm. The above-described polymer is formed into a film as a polymer solution using a solvent (ketone system, ester system, alcohol system, fluorine system, etc.) suitable for each. There are spin coating methods, roll coating methods, knife coating methods, die coating methods, casting methods, etc. as film formation methods for polymer solutions. From the standpoint of uniformity and ease of management of foreign substances in polymer solutions, spin coating methods are available. A coating method is preferred. After a polymer is deposited on the deposition substrate by spin coating, a uniform film is formed by drying the solvent by hot plate, clean oven, (far) infrared heating or the like, if necessary. As the film formation substrate at this time, synthetic quartz, fused quartz, alkali-free glass, low alkali glass, soda lime glass, or the like can be used.

  Further, it is preferable that an antireflection layer made of a material having a lower refractive index than that of the pellicle film 4 is formed on one side or both sides of the pellicle film 4 so that the transmittance with respect to exposure light can be increased. As the material of the antireflection layer, fluorine-based polymers (tetrafluoroethylene-vinylidene fluoride-hexafluoropropylene terpolymer, Teflon (registered trademark) AF manufactured by DuPont which is a polymer having a cyclic structure in the main chain, Asahi Glass Co., Ltd.) CYTOP (registered trademark) manufactured by the company, Algoflon (registered trademark) manufactured by Augmont, etc., polyfluoroacrylate, etc.), and materials having a low refractive index such as calcium fluoride, magnesium fluoride, and barium fluoride are used. The thickness of the antireflection layer is preferably set within a range of 10 nm to 500 nm, and particularly preferably within a range of 20 nm to 180 nm from the viewpoint of enhancing the antireflection effect.

  An adhesive for adhering the pellicle film 4 to the frame 2 is appropriately selected depending on the material of the pellicle film 4 and the material of the frame 2. For example, an epoxy, acrylic, silicone or fluorine adhesive is used. As the curing method, a curing method (thermal curing, photocuring, anaerobic curing, etc.) suitable for each adhesive is employed. From the viewpoint of dust generation, cost, and workability, an acrylic ultraviolet curable adhesive is preferable.

  Examples of the material of the frame 2 include known materials used for the pellicle 1 such as aluminum or an alloy thereof (for example, duralumin) or iron or an iron-based alloy (for example, stainless steel). Among these, in consideration of an increase in the weight of the frame 2 due to an increase in size, it is preferable to use a lightweight and rigid material, such as aluminum or an alloy thereof.

  The adhesive material for attaching the frame 2 to the photomask 7 includes a hot melt system (rubber system, acrylic system, styrene ethylene butylene styrene system, styrene ethylene propylene styrene system) having an adhesive force, and a base material. Tape system with adhesive material applied on both sides (Acrylic, PVC, etc. sheets as base material or rubber, polyolefin, urethane, etc. can be applied, rubber, acrylic, silicone, etc. as adhesive Are used).

  In the large pellicle 1 according to the present embodiment, a relatively soft hot-melt material or foam is suitable as the adhesive material so that the pellicle 1 is evenly attached to the photomask 7 with a low load. In the case of a foam, dust generation from the foam can be prevented by covering the cross section with an acrylic or vinyl acetate adhesive material or a non-adhesive material. The thickness of the pressure-sensitive adhesive layer is preferably 0.2 mm or more and 2 mm or less, but more preferably 1 mm or more for uniform application to the photomask 7. In order to protect the adhesive surface of the adhesive material layer until it is attached to the photomask 7, a polyester film which has been subjected to a release treatment with silicone or fluorine is preferably used.

  Next, a method for attaching the pellicle 1 according to this embodiment to the photomask 7 will be described.

  First, the pellicle 1 is attached to the photomask 7 with the adhesive material layer 3. At this time, since air is entrained in the closed space between the pellicle 1 and the photomask 7, the pellicle film 4 swells and the flatness decreases. At this time, the swelling amount of the pellicle film 4 at the center with respect to the periphery of the frame 2 may be about 0.3 to 5.0 mm. However, since the pellicle film 4 tends to return to a flat state due to the tension of the pellicle film 4, the air in the closed space is gradually discharged to the external space through the through holes (particularly, the second through holes 6). The flatness gradually recovers. Further, when it is desired to restore the pellicle film 4 to the flatness as soon as possible, physical means such as suction by a vacuum pump may be taken. When the swelling amount of the pellicle film 4 is restored to a predetermined value or less, the opening of the second through hole 6 is closed with a sealing material or an adhesive material, a filter is attached, or the openable / closable ventilation means is closed. The predetermined value may be determined by the working distance margin of the exposure apparatus to be used and the capability of the defect inspection apparatus, but is usually preferably 1 mm or less, and more preferably 0.3 mm or less.

  As a method for closing the opening of the second through hole 6, a method of sealing the through hole with a curable adhesive, putty solder, or the like, and a sealing material or a filter from the outside of the opening of the second through hole 6 are used. A method of sticking and a method of closing the openable / closable ventilation means can be mentioned. The filter preferably has a smaller pressure loss than the filter used for the first through-hole 5 in order to accelerate the membrane return time when the pellicle membrane 4 swells. Specifically, the pressure loss of the filter used for the first through hole 5 is preferably 300 to 500 Pa, and the pressure loss of the filter used for the second through hole 6 is preferably 50 to 250 Pa. As a material, a porous filter using ultra high molecular weight polyethylene, a sintered metal filter, a porous ceramic filter, or the like can be preferably used.

  The material used for the seal is preferably a tape that does not contain foreign matter, but any material may be used as long as it is a sealing material that is excellent in dustproofness and low outgassing properties. However, before sticking, it should be excellent in dust resistance and low outgassing properties, and it should have an adhesive strength that does not peel off due to vibration during transportation and storage. This is because the seal at the opening is peeled off immediately after pasting and the pellicle film 4 is opened until the pellicle film 4 is recovered. For example, anything may be used as long as it is provided with an adhesive layer on a dustproof tape or a filter for a vent hole. Examples of the sealing material include a dustproof tape made of fluororesin or polyolefin resin. Examples of the adhesive material include a hot-adhesive mask adhesive material used in the pellicle 1, a silicone-based adhesive material, and a foamable double-sided tape.

  In the mounting method according to the embodiment described above, the pellicle 1 is attached to the photomask 7 by the first through hole 5 to which the filter 8 (first filter) having a relatively large pressure loss is attached. Air permeability for coping with changes in atmospheric pressure in the surrounding atmosphere can be ensured. Further, the second through-hole 6 having a large air outflow speed functions mainly for air entrainment when the pellicle 1 is attached to the photomask 7, and the air entrained when the pellicle 1 is attached to the photomask 7. Can be quickly released from the closed space between the pellicle 1 and the photomask 7 to the external space, and the swelling of the central portion of the pellicle film 4 can be quickly eliminated to restore the flatness to the original state.

  Further, in the attachment method according to the embodiment described above, when an openable / closable ventilation means (for example, a cock or a check valve) is attached to the second through-hole 6, the pellicle 1 is attached to the photomask 7. By opening the openable / closable ventilation means, the air entrained when the pellicle is affixed to the photomask 7 is quickly released from the closed space between the pellicle 1 and the photomask 7 to the external space, and the central portion of the pellicle film 4 It is possible to quickly eliminate the swelling and restore the flatness to the original state. Then, after the flatness of the pellicle film 4 is restored, the flatness can be maintained by closing the openable / closable ventilation means.

  Moreover, in the attachment method according to the embodiment described above, when the filter or the seal material is detachably attached to the second through hole 6, the second through hole 6 is attached after the pellicle is attached to the photomask. By removing the filter or the sealing material, the air entrained when the pellicle is attached to the photomask 7 is quickly released from the closed space between the pellicle 1 and the photomask 7 to the external space, and the swelling of the central portion of the pellicle film 4 is caused. It can be quickly eliminated and the flatness can be restored to the original state. Then, after the flatness of the pellicle film 4 is recovered, the flatness can be maintained by attaching a filter or a sealing material to the second through hole 6.

  Hereinafter, the present embodiment will be described in detail with reference to examples and comparative examples.

[Example 1]
An aluminum alloy frame (inner dimensions: 1493 mm x 1711 mm, long side width: 16.5 mm, short side width: 18.5 mm, height: 6.0 mm) with anodized surface and two sides Four through-holes with a diameter of 1.5 mm were formed in the vicinity of the center of the side surface, for a total of 8 holes to be the first through-holes. Next, a total of four through-holes having a diameter of 2.2 mm were formed between the corners of the frame and the first through-holes to form second through-holes.

  The pellicle film has a thickness obtained by applying a polymer solution of cellulose ester on a low alkali glass to form a main film by spin coating, and then applying a fluoropolymer solution by spin coating on the film to form an antireflection layer. A 4 μm pellicle membrane was used. The obtained pellicle film was spread and bonded to the upper edge surface of the frame with an adhesive. Also, a styrene ethylene butylene styrene hot melt adhesive material is applied and dried on the lower edge surface of the frame to form a 1 mm thick adhesive material layer, and a 0.1 mm thick liner made of polyethylene film is used as the adhesive material. Protected by sticking to the layer.

  A PTFE filter (pressure loss 380 Pa) having an average hole diameter of 0.6 μm, a thickness of 0.15 mm, and a size of 3.0 mm × 7.5 mm is inserted into the eight first through holes, and the first through hole frame. Was attached to the frame using a double-sided tape having a thickness of 0.1 mm so as to separately cover the openings on the side surfaces. On the other hand, an ultra high molecular weight polyethylene filter (pressure loss 120 Pa) having an average pore diameter of 17 μm, a thickness of 0.5 mm, and a size of 3.5 mm × 8.0 mm is inserted into the four second through holes. It was affixed to the frame using a double-sided tape having a thickness of 0.1 mm so as to separately cover the openings on the side surfaces of the hole frame.

The liner is peeled off and removed from the pellicle produced as described above, and applied to a glass substrate (length 1700 mm × width 1800 mm × thickness 14.8 mm) instead of a photomask with a load of 6.5 N / cm ^2. It was stuck.

  After that, air is pumped from one of the first through holes into a closed space constituted by the pellicle affixed on the glass substrate and the glass substrate, and the height of the central part of the pellicle film is reduced to the frame. It was inflated until it became 2 mm higher than the average height of the body periphery (average value of the center of each of the four sides of the frame). Thereafter, all four filters at the opening of the second through-hole were attached as they were, and the swelling of the pellicle film was observed, and the time required until the swelling amount of the pellicle film became 0 mm was measured. The amount of swelling at the center of the pellicle film was measured with a laser displacement meter (KEYENCE LC-2450). The results are shown in Table 1. Further, after the flatness of the pellicle film returned, it was visually inspected whether foreign matter was mixed in the pellicle. The results are also shown in Table 1.

[Example 2]
A pellicle was prepared in the same manner as in Example 1 except that the dimensions of the frame were 1122 mm × 1342 mm, long side width 12 mm, short side width 12 mm, and height 5.0 mm. Was expanded until it became 2 mm high, and then the time required until the expansion amount became 0 mm was measured. The results are shown in Table 1. A visual inspection was also performed under the same conditions. The results are also shown in Table 1.

Example 3
A pellicle was prepared in the same manner as in Example 1 except that the ultra high molecular weight polyethylene filter attached to the second through hole was changed to a sealing material (“Eco Clear Tape” manufactured by Nitto Denko) 3 mm × 7.5 mm. Under the same conditions, the pellicle membrane was inflated to a height of 2 mm. Thereafter, all the four sealing materials were removed, and the time required for the amount of swelling of the pellicle membrane to become 0 mm was measured. The results are shown in Table 1. After the measurement, a new sealing material having the same dimensions and shape as the sealing material was pasted to seal the second through hole. Thereafter, it was visually inspected whether foreign matter was mixed in the pellicle. The results are also shown in Table 1.

Example 4
A pellicle was prepared in the same manner as in Example 3 except that the dimensions of the frame were 1122 mm × 1342 mm, long side width 12 mm, short side width 12 mm, and height 5.0 mm. Was expanded until it became 2 mm high, and then the time required until the expansion amount became 0 mm was measured. The results are shown in Table 1. A visual inspection was also performed under the same conditions. The results are also shown in Table 1.

[Comparative Example 1]
A pellicle was produced in the same manner as in Example 1 except that the frame did not have the second through-hole, and after the pellicle film was inflated to 2 mm higher under the same conditions, the amount of swelling was 0 mm. The time required was measured. The results are shown in Table 1. A visual inspection was also performed under the same conditions. The results are also shown in Table 1.

[Comparative Example 2]
A pellicle was prepared in the same manner as in Example 2 except that the frame did not have the second through hole, and the pellicle film was inflated to a height of 2 mm under the same conditions. The time required was measured. The results are shown in Table 1. A visual inspection was also performed under the same conditions. The results are also shown in Table 1.

[Comparative Example 3]
The pellicle is the same as in Example 2 except that the frame does not have the second through-hole and that the first through-hole is eight in the center of the two long sides, a total of sixteen. After the pellicle membrane was swollen to 2 mm higher under the same conditions, the time required for the swollen amount to be 0 mm was measured. The results are shown in Table 1. A visual inspection was also performed under the same conditions. The results are also shown in Table 1.

  As is clear from the above results, in Examples 1 to 4 in which the second through hole is provided in the pellicle, the second through hole having a relatively small pressure loss and a large air outflow speed is formed by attaching the pellicle to the glass substrate ( It effectively functions against air entrainment when pasting to a photomask substitute), and can quickly eliminate swelling at the center of the pellicle film as compared with Comparative Examples 1-3.

  The method for attaching a pellicle according to the present invention can be suitably used in the field of manufacturing liquid crystal panels.

DESCRIPTION OF SYMBOLS 1 ... Pellicle 2 ... Frame body 3 ... Adhesive material layer 4 ... Pellicle film 5 ... 1st through-hole 6 ... 2nd through-hole 7 ... Photomask 8 ... Filter

Claims (7)

A pellicle comprising a frame, an adhesive layer laminated on a lower edge surface of the frame, and a pellicle film stretched and bonded to the upper edge surface of the frame,
A first through hole to which the first filter is attached and a second through hole to which the second filter is attached are provided on the side surface of the frame body,
The pressure loss of the second filter is set smaller than the pressure loss of the first filter,
Pellicle. A pellicle comprising a frame, an adhesive layer laminated on a lower edge surface of the frame, and a pellicle film stretched and bonded to the upper edge surface of the frame,
The first through-hole to which the filter is attached and the second through-hole to which the openable / closable ventilation means are attached have a side surface of the frame body.
Pellicle. The total area of the openings of the first through holes on the side surface of the frame body is set to 0.1 mm ² or more and 10 mm ² or less per 1000 cm ² of the area of the pellicle film.
The pellicle according to claim 1 or 2. The total area of the openings of the second through holes on the side surface of the frame is set to 0.6 mm ² or more and 30 mm ² or less per 1000 cm ² of the area of the pellicle film.
The pellicle according to any one of claims 1 to 3. A method of attaching the pellicle according to any one of claims 1, 3, and 4 to a photomask,
Attaching the pellicle to the photomask with the adhesive layer;
Attaching a sealing material to the second through-hole after the swelling amount of the central portion of the pellicle membrane has recovered to a predetermined value or less,
How to install the pellicle. A method of attaching the pellicle according to any one of claims 2 to 4 to a photomask,
Attaching the pellicle to the photomask with the adhesive layer with the openable / closable ventilation means closed; and
Opening the openable / closable vent means; and
Including closing the openable and closable ventilation means after the swelling amount of the central portion of the pellicle membrane is restored to a predetermined value or less.
How to attach the pellicle. A method of attaching a pellicle having a frame, a pressure-sensitive adhesive layer laminated on a lower edge surface of the frame, and a pellicle film stretched and bonded to the upper edge surface of the frame to a photomask,
The pellicle has a first through hole to which a filter is attached and a second through hole to which a filter or a sealing material is detachably attached, on a side surface of the frame body,
Attaching the pellicle to the photomask with the adhesive layer;
Removing the filter or the sealing material from the second through hole;
Attaching the filter or the sealing material to the second through-hole after the swelling amount of the central portion of the pellicle membrane has recovered to a predetermined value or less,
How to attach the pellicle.

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