HK1159762A - Pellicle for lithography and manufacturing method thereof - Google Patents

Description

Pellicle for lithography and method for manufacturing the same

Technical Field

The present invention relates to a pellicle (pellicle) for lithography used as a photomask or a pellicle for protecting a reticle (reticle) in the production of semiconductor devices such as LSIs and super LSIs and liquid crystal display panels, and a method for producing the pellicle.

Background

In the manufacture of semiconductor devices such as LSIs and super LSIs and liquid crystal displays, exposure light is irradiated onto a semiconductor wafer or a liquid crystal master through an exposure master such as a photomask or a reticle (collectively referred to as "photomask" in this specification), and a photomask pattern is transferred to form a pattern of a semiconductor device or a liquid crystal display.

Therefore, if foreign matter such as dirt adheres to the photomask, the exposure light is reflected or absorbed by the foreign matter such as dirt adhering to the surface of the photomask, so that the pattern transferred to the semiconductor wafer or the liquid crystal mother panel is deformed, the edge portion of the pattern becomes unclear, and the substrate becomes black, and the size, quality, appearance, and the like are impaired. This causes a problem that the pattern of the photomask cannot be transferred to a semiconductor wafer or a liquid crystal master as desired, and the performance of the semiconductor device or the liquid crystal display is degraded, resulting in a poor yield.

To prevent such a problem, exposure of the semiconductor wafer or the liquid crystal master is performed in a clean room. However, even in this case, it is difficult to completely prevent the adhesion of foreign matter on the surface of the photomask, and therefore, a dust cover is usually attached to the surface of the photomask to expose the semiconductor wafer or the liquid crystal mother plate. The dust cover is called a dust-proof film member and has a high transmittance to exposure light.

Pellicle assemblies are typically manufactured by: the pellicle is produced by coating one surface of a pellicle frame made of aluminum, stainless steel, polyethylene or the like with a good solvent for a pellicle material, air-drying the pellicle, and bonding the pellicle to the surface, or by bonding the pellicle to the surface with an adhesive such as an acrylic resin, an epoxy resin, or a fluororesin, forming an adhesive layer made of a polybutene resin, a polyacetic resin, an acrylic resin, or a silicone resin for bonding a photomask to the other surface of the pellicle frame, and providing a release layer or a spacer for protecting the adhesive layer on the adhesive layer. The pellicle film is made of a cellulose resin such as nitrocellulose and cellulose acetate, or a fluorinated resin, which has a high transmittance to exposure light (see, for example, Japanese patent laid-open publication No. Sho 58-219023, U.S. Pat. No. 4861402, Japanese patent laid-open publication No. Sho 63-27707, and Japanese patent laid-open publication No. Hei 7-168345).

When the pellicle is mounted on the surface of a photomask and a semiconductor wafer or a liquid crystal panel is exposed through the photomask, foreign matter such as dirt adheres to the surface of the pellicle and does not adhere directly to the surface of the photomask, so that the influence of foreign matter such as dirt can be eliminated by irradiating exposure light onto a pattern formed on the photomask and focusing the exposure light.

In addition, in order to eliminate the difference in air pressure between the space enclosed inside the pellicle and the outside in the state where the pellicle is attached to the photomask, a part of the pellicle frame may be provided with small holes for air pressure adjustment. And a screen provided to prevent intrusion of foreign matter from the air flowing through the small holes.

Since the dust-proof pellicle is generally formed of a thin resin film, the dust-proof pellicle is bonded to the dust-proof pellicle assembly frame in a state where a predetermined tension is applied to the dust-proof pellicle in order to be supported tightly by the dust-proof pellicle assembly frame to prevent sagging.

Therefore, in the case of a generally used dust-proof pellicle with a rectangular cross section, after the dust-proof pellicle is attached to the frame of the dust-proof pellicle, the frame of the dust-proof pellicle inevitably undergoes inward warp deformation due to the tension of the dust-proof pellicle.

Such inward warping of the pellicle frame is particularly significant when the pellicle frame has a large side length, such as a printed circuit board or a large-sized pellicle for liquid crystal display manufacturing.

On the other hand, in the photomask, it is required to secure the exposure area to the maximum extent for cost reduction. If the pellicle frame is warped inward, the exposure area is reduced, and it is therefore desirable to reduce the inward warping of the pellicle frame as much as possible.

Although the above problems can be solved by increasing the rigidity of the pellicle frame by enlarging the cross-sectional area of the pellicle frame and the like in technical terms, in practice, the area of the inner side of the pellicle frame is limited in order to secure a large exposure area, and the space required for the operation of fixing or transporting the photomask is secured on the outer side of the pellicle frame. Thus, typically the edges of the pellicle frame are in a straight line shape determined by these constraints.

In addition, there is also a method of reducing the inward warping of the pellicle frame by forming the pellicle frame from a more rigid material, such as carbon fiber Composite (CFRP) or titanium instead of aluminum alloy. Although this makes it possible to reduce the inward warping of the pellicle frame as compared with the case where the pellicle frame is formed of an aluminum alloy, these materials are expensive and have poor workability, and thus it is not practical to significantly increase the cost.

In order to reduce the inward warpage of the pellicle frame, japanese patent No. 4286194 proposes a method of forming the pellicle frame such that the central portion of at least one pair of sides thereof is an outwardly convex arc-shaped portion, both sides thereof are outwardly concave arc-shaped portions, and the outer side thereof is provided with a linear portion, and the pellicle frame is formed into a desired shape after the pellicle is attached.

Although this method makes it possible to control the shape of the pellicle frame to a desired shape after the pellicle is attached, this method has a problem that it is difficult to mass-produce pellicle assemblies.

That is, in order to control the shape of the frame of the pellicle after the pellicle is attached to the desired shape, the shape of the frame of the pellicle is designed in accordance with the tension distribution of the pellicle, but the tension distribution of the mass-produced pellicle is not constant and a certain degree of variation is inevitable. As a result, when the tension of the dustproof film is greater than the design value, the dustproof film assembly frame is warped inwards excessively after the dustproof film is pasted; on the other hand, when the thickness is smaller than the design value, as shown in japanese patent No. 4286194, the side of the pellicle frame where the center portion is a convex arc portion, the both sides are concave arc portions, and the outer side is a straight portion is maintained in an outward protruding state after the pellicle is attached. In general, the inner dimensional tolerance of the pellicle is set in consideration of the warpage of the pellicle frame due to the tension of the pellicle, the error in attaching the pellicle to the photomask, and the like, so that some margin is left in the photomask pattern portion. However, the outward warping of the pellicle frame is merely a mechanical deformation and is not considered in designing the pellicle frame. Therefore, when the tension of the pellicle is smaller than the designed value and the frame side of the pellicle projects outward, there is a possibility that the pellicle attaching apparatus for attaching the pellicle to the photomask interferes with the conveying apparatus in the photomask exposing machine during the handling of the pellicle.

In the general attachment device for a dustproof sheet assembly as disclosed in japanese patent application No. 4354789, since the dustproof sheet assembly is installed with the long side of the dustproof sheet assembly frame facing downward and in the vertical direction, when the dustproof sheet assembly is installed with the long side of the dustproof sheet assembly frame facing outward, the long side of the dustproof sheet assembly frame facing outward is displaced inward, and thus the dustproof sheet is likely to wrinkle.

Disclosure of Invention

The invention aims to provide a dustproof film assembly for photoetching, which can prevent reduction of an exposure area even when tension of the dustproof film is not uniformly distributed, and can effectively prevent the dustproof film adhered to a dustproof film assembly frame from generating wrinkles and other problems.

It is another object of the present invention to provide a method for manufacturing a pellicle for lithography, which can prevent a reduction in an exposure area even when tension distribution of a pellicle is uneven, and can effectively prevent a problem such as a wrinkle from occurring in a pellicle attached to a frame of the pellicle.

The object of the present invention is achieved as follows.

A pellicle, comprising: comprises a dustproof film component frame; the pellicle frame has at least a pair of long sides each having a substantially linear shape and a pair of short sides each having a shape in which a central portion protrudes outward; a dust-proof film is attached to one surface of the dust-proof film unit frame, and the tension of the dust-proof film is adjusted so that the tension in the direction of the pair of long sides of the dust-proof film unit frame is greater than the tension in the direction of the pair of short sides of the dust-proof film unit frame; the pair of short sides of the pellicle frame are substantially linear in shape.

A method of manufacturing a pellicle, comprising: a dustproof thin film is adhered on one surface of the dustproof thin film component frame; the pellicle frame has at least a pair of long sides each having a substantially linear shape and a pair of short sides each having a shape in which a central portion protrudes outward; the tension of the dustproof pellicle is adjusted, so that the tension along the direction of the long sides of the dustproof pellicle assembly frame is larger than the tension along the direction of the short sides of the dustproof pellicle assembly frame; deforming the pair of short sides of the pellicle assembly frame into a substantially linear shape.

According to the present invention, since the tension of the pellicle is adjusted so that the tension in the direction of the pair of long sides of the pellicle frame is greater than the tension in the direction of the pair of short sides of the pellicle frame, when the pellicle is attached, the inside warpage of the short sides of the pellicle frame is greater than that of the long sides, and as a result, the two corners of the short sides of the pellicle frame generate a bending moment that forces the long sides to displace to the outside. On the other hand, the pair of short sides of the pellicle frame is also deformed into a linear shape by the tension of the pellicle. Therefore, without enlarging the sectional shape of the pellicle frame or forming the pellicle frame from a highly rigid material, the exposure area can be effectively prevented from being reduced without increasing the cost.

Further, according to the present invention, since the long side of the dustproof film is originally linear, even when the tension of the dustproof film is not uniform and the inward force applied to the long side of the dustproof film assembly frame by the dustproof film is smaller than the designed value, the long side of the dustproof film assembly frame does not protrude outward after the dustproof film is attached. Therefore, even when the pellicle frame is placed vertically with the long side of the pellicle frame facing downward on the pellicle pasting apparatus, the long side of the pellicle frame does not displace inward. Therefore, the dust-proof film can be effectively prevented from wrinkling.

In a preferred embodiment of the present invention, the pair of short sides of the pellicle frame each include: a central region including a central portion of the short side and having a convex arc shape with respect to an outer side; an end-part-near region which is linear near both ends of the short side; and the middle areas are positioned on two sides of the central area, and the relative outer sides between the central area and the end part adjacent areas are in a concave arc shape, so that the central area and the end part adjacent areas are smoothly connected.

According to a preferred embodiment of the present invention, the center region of the short side of the pellicle frame is displaced inward largely by the tension of the pellicle, so that the center region and the end-portion-adjacent region are smoothly joined together, and the middle region having a concave arc shape with respect to the outer side is also displaced inward. Therefore, the short side of the pellicle frame can be displaced to a shape closer to a straight line.

Further, according to the preferred embodiment of the present invention, since the end-part vicinity regions near both end parts of the short side of the pellicle frame are formed in a straight line shape, not only can the frame size be accurately measured, but also the pellicle frame can be positioned at an accurate position during the production operation. Therefore, the pellicle frame can be processed with high accuracy.

In a more preferred embodiment of the invention, the pellicle assembly frame is designed such that: the radius of the intermediate region having a concave arc shape to the outside is not less than 1/3 of the radius of the central region having a convex arc shape to the outside.

According to the preferred embodiment of the present invention, the arc shape of the central region which is convex with respect to the outer side and the arc shape of the intermediate region which is concave with respect to the outer side can be smoothly connected.

In a more preferred embodiment of the present invention, the dustproof thin film is stretched over a temporary frame before the dustproof thin film is attached to the dustproof thin film assembly frame, and the tension of the dustproof thin film is adjusted by mechanically displacing a central portion of at least one pair of opposing sides of the temporary frame.

In a more preferred embodiment of the present invention, when mechanically displacing the central portion of at least one pair of opposing sides of the time frame, the amount of displacement of the central portion of the at least one pair of opposing sides is controlled by detecting the amount of displacement of the central portion of the at least one pair of opposing sides by load detection means or displacement amount detection means that detects a load applied to the central portion of the at least one pair of opposing sides.

In a more preferred embodiment of the present invention, the load detection unit is constituted by a load cell.

Drawings

Fig. 1 is a schematic plan view of a dustproof pellicle frame used in a manufacturing method of a dustproof pellicle assembly according to a preferred embodiment of the present invention in a state where a dustproof pellicle is not bonded.

Fig. 2 is a schematic plan view of the dustproof thin film module frame of fig. 1 in a state where a dustproof thin film is adhered thereto.

Fig. 3 is a plan view of a dustproof thin film assembly manufacturing apparatus in which a dustproof thin film is adhered to a dustproof thin film assembly frame used in the dustproof thin film assembly manufacturing method according to the preferred embodiment of the present invention.

Fig. 4 is a sectional view taken along line a-a in fig. 3.

FIG. 5 is a schematic plan view of a pellicle assembly frame with a pellicle membrane exerting a force on the pellicle assembly frame.

FIG. 6 is a schematic plan view showing the shape of a frame of a pellicle for use in comparative example 1.

Fig. 7 is a schematic plan view of the shape of the pellicle frame of the pellicle manufactured in comparative example 1.

Fig. 8 is a schematic plan view of the shape of the pellicle frame of the pellicle manufactured in comparative example 2.

Description of the reference numerals

In the drawing, 10 is a dustproof pellicle frame, 11 is a long side of the dustproof pellicle frame, 12 is a short side of the dustproof pellicle frame, 12a is a central region of the dustproof pellicle frame, 12b is a middle region of the dustproof pellicle frame, 12c is a region near an end of the dustproof pellicle frame, 20 is a dustproof pellicle, 21 is a temporary frame, 22 is a dustproof pellicle support portion, 23 is a grip portion, 25 is a load applying unit, 26 is a connecting portion, 27 is a stage, 28 is a load detecting unit, 30 is a carrying stage, 31 is a dustproof pellicle adhesive layer, 32 is a photomask adhesive layer, and 35 is a lifting stage mechanism.

Detailed Description

Fig. 1 is a plan view of a pellicle frame for use in a pellicle manufacturing method according to a preferred embodiment of the present invention, showing the pellicle frame before the pellicle is bonded.

As shown in fig. 1, the pellicle frame 10 has a substantially rectangular cross-sectional shape, with a pair of opposing long sides 11, 11 each having a substantially linear shape, and a pair of opposing short sides 12, 12 each having a shape in which a central region 12a, 12a including a central portion thereof protrudes outward.

More specifically, as shown in fig. 1, the pellicle frame 10 according to the present embodiment has a pair of short sides 12, 12 each having a circular arc shape in which a central region 12a including a central portion of the short side is convex with respect to the outside, and end-near regions 12c, 12c near the ends of the short sides 12 each having a straight line shape; the intermediate regions 12b, 12b located on both sides of the central region 12a are formed in a concave arc shape with respect to the outer sides, and the central region 12a formed in a convex arc shape with respect to the outer sides and the end-portion adjacent regions 12c, 12c formed substantially in a linear shape are smoothly joined.

Here, the shapes of the central region 12a of the arc shape convex to the outside of the dustproof thin film module frame, the intermediate regions 12b, 12b of the arc shape concave to the outside, and the end near regions 12c, 12c substantially linear, and the lengths of the respective regions are appropriately designed in accordance with the tension of the dustproof thin film parallel to the long axis direction of the long side 11 of the dustproof thin film module frame 10 and the tension parallel to the short axis direction of the short side 12 of the dustproof thin film module frame 10, so that the long side 11 and the short side 12 of the dustproof thin film module frame 10 are substantially linear when the dustproof thin film is bonded to the dustproof thin film module frame 10 and the dustproof thin film outside the dustproof thin film module frame 10 is cut.

According to the studies of the present inventors, it was found that: in the pellicle frame 10, if the radii of the intermediate regions 12b, 12b having the concave arc shape to the outside are set to be equal to or larger than 1/3 of the radius of the central region 12a having the convex arc shape to the outside, the convex arc shape to the outside of the central region 12a and the concave arc shape to the outside of the intermediate region 12b are smoothly connected to each other, which is particularly preferable.

Fig. 2 is a schematic plan view showing the state of the pellicle frame 10 and the pellicle 20 when the pellicle 20 is bonded to the pellicle frame 10 according to the present embodiment.

In fig. 1 and 2, since the dust-proof pellicle 20 is bonded to the dust-proof pellicle assembly frame 10 in a state where a predetermined tension is applied thereto, the central region 12a of the short side 12 of the dust-proof pellicle assembly frame 10, which is convex outward in a circular arc shape, is warped inward by the tension of the dust-proof pellicle 20, and is substantially linear. On the other hand, although the long side 11 of the pellicle frame 10 is warped inward by the tension of the pellicle film 20, the warp amount is within the allowable range, which is very small compared to the warp amount of the long side 11 of the pellicle frame 10 in which the short side 12 is formed substantially linearly.

Fig. 3 is a plan view of a pellicle manufacturing apparatus for attaching a pellicle film 20 to a pellicle frame 10 for use in a pellicle manufacturing method according to a preferred embodiment of the present invention. Fig. 4 is a sectional view taken along line a-a in fig. 3.

As shown in fig. 3 and 4, the dustproof thin film module manufacturing apparatus includes a stage 30 of the dustproof thin film module frame 10, the dustproof thin film module frame 10 is formed with a dustproof thin film adhesive layer 31 and a photomask adhesive layer 32, and the photomask adhesive layer 32 is protected by a spacer (not shown). The stage 30 is vertically movable by a stage mechanism 35.

As shown in fig. 3 and 4, the dustproof thin film assembly manufacturing apparatus is constituted such that: four corners of the temporary frame 21, which is provided with the dust-proof film support portions 22 at the four corners and to which the dust-proof film 20 is stretched, are provided on the corresponding dust-proof film support portions 22. In addition, a grip 23 is provided at the center of each side of the temporary frame 21.

The grip 23 is connected to a load applying unit 25 via a connecting portion 26. The load applying unit 25 is constituted such that: a load is applied to the grip portion 23 to displace the grip portion 23 in a direction orthogonal to each side of the temporary frame 21.

The load applying unit 25 includes: a stage 27 capable of automatically or manually moving in a direction orthogonal to each side of the temporary frame 21; and a load detection unit 28 fixed on the table 27 and capable of detecting a load applied to the grip portion 23 of the temporary frame 21 to which the dust-proof film 20 is stretched. In the present embodiment, the load detection unit 28 employs a load sensor. The manufacturing apparatus according to the present embodiment further includes a display (not shown) capable of displaying the compressive force or tensile force applied to the grip portion 23 of the time frame 21 by the movement of the load application unit 25.

Therefore, by displacing the stage 27 in the direction orthogonal to the sides of the temporary frame 21, displacing the temporary frame 21, and changing the tension in the long axis direction and the tension in the short axis direction applied to the dust-proof film 20 stretched over the temporary frame 21, the displacement amount in the long axis direction and the displacement amount in the short axis direction of the temporary frame 21, and the tension in the long axis direction and the tension in the short axis direction applied to the dust-proof film 20 can be detected by the load detection unit 28.

In the present embodiment, the stage 27 is moved while the load detection unit 28 detects the tension in the long axis direction and the tension in the short axis direction applied to the pellicle 20, and the tension applied to the pellicle 20 is controlled so that the tension in the long axis direction parallel to the long side 11 of the pellicle frame 10 is greater than the tension in the short axis direction parallel to the short side 12 of the pellicle frame 10.

As described above, when the tension of the pellicle film 20 is set so that the tension in the major axis direction is greater than the tension in the minor axis direction, the stage 30 on which the pellicle frame 10 is mounted is gradually raised by the raising/lowering table mechanism 35, the pellicle film adhesive layer 31 comes into contact with the pellicle film 20 held on the temporary frame 21, and the pellicle film 20 is adhered to one surface of the pellicle frame 10. At this time, the stage 30 contacts the pellicle film 20 at a slight angle in order to prevent air from being trapped between the pellicle film adhesive layer 31 and the pellicle film 20.

Then, the dust-proof pellicle 20 on the outer side of the dust-proof pellicle assembly frame 10 is cut off by a cutter (not shown) to produce a dust-proof pellicle assembly.

Fig. 5 is a schematic plan view of the pellicle frame 10, where the pellicle frame 10 is applied with a force by the pellicle 20 when the pellicle 20 is attached to one surface of the pellicle frame 10 used in the pellicle manufacturing method according to the present embodiment, and the tension of the pellicle 20 is controlled so that the tension in the long axis direction is greater than the tension in the short axis direction.

As shown in fig. 5, the short side 12 of the dustproof thin film module frame 10 is applied with a force T1 directed toward the inside of the dustproof thin film module frame 10 by the tension of the dustproof thin film 20 stretched by the time frame 21, and the long side 11 of the dustproof thin film module frame 10 is applied with a force T2 directed toward the inside of the dustproof thin film module frame 10 by the tension of the dustproof thin film 20 stretched by the time frame 21.

As described above, since the tension of the dust-proof film 20 is controlled so that the tension in the major axis direction is larger than the tension in the minor axis direction, T1 is larger than T2. Therefore, the warp and displacement of the short side 12 of the pellicle frame 10 in the inward direction are larger than the warp and displacement of the long side 11.

Further, according to the short side 12 of the pellicle frame 10 of the present embodiment, since the central area 12a is formed in a convex arc shape with respect to the outside, the central area 12a of the short side 12 is displaced inward by the T1 force applied by the pellicle 20, and is positioned on a virtual straight line connecting the corner portions at both ends of the short side 12.

The short sides 12 of the pellicle frame 10 are positioned on both sides of the central region 12a, and the central region 12a having a convex arc shape with respect to the outside and the substantially linear end-adjacent regions 12c, 12c are smoothly connected to each other, while the intermediate regions 12b, 12b having a concave arc shape with respect to the outside are also displaced inward, and as a result, the short sides 12 of the pellicle frame 10 to which the pellicle 20 is bonded on one side are substantially linear.

On the other hand, the long side 11 of the pellicle frame 10 formed substantially in a straight line shape is also applied with a force T2 directed inward by the pellicle 20, and although the long side 11 of the pellicle frame 10 is also displaced inward by the force T2, the short side 12 is displaced more inward, so that a bending moment M that forces the long side 11 to be displaced outward acts on the corner of the pellicle frame 10, and the force T2 that forces the long side 11 to be displaced inward and the force that forces the long side 11 to be displaced outward due to the bending moment M cancel each other. Therefore, the inward warping of the long side 11 of the pellicle frame 10 can be restricted within an allowable range.

As described above, according to the present embodiment, the pellicle frame 10 has the center region 12a corresponding to the center of each of the pair of short sides 12, which is convex with respect to the outside, the intermediate regions 12b, 12b located on both sides of the center region 12a, which are concave with respect to the outside, and the end vicinity regions 12c, 12c near the ends of the short sides 12, which are substantially linear. The tension of the pellicle 20 is controlled so that the tension in the direction parallel to the long axis of the long side 11 of the pellicle frame 10 is larger than the tension in the direction parallel to the short axis of the short side 12 of the pellicle frame 10, and the pellicle is attached to one surface of the pellicle frame 10 in a state where the pellicle is stretched over the temporary frame 21. As a result, the short side 12 of the pellicle frame 10 is deformed into a straight line shape by the T1 force applied to the short side 12 of the pellicle frame 10 by the pellicle film 20; the long side 11 of the pellicle frame 10 is deformed inward by the T2 force applied to the long side 11 of the pellicle frame 10 by the pellicle 20. However, since the short side 12 is deformed more inward, the bending moment M that forces the long side 11 to displace outward acts on the corner of the pellicle frame 10, and the force that forces the long side 11 to deform inward due to the force T2 and the force that forces the long side 11 to displace outward due to the bending moment M cancel each other out, and the long side 11 of the pellicle frame 10 also remains substantially linear.

Therefore, after the dustproof pellicle 20 is attached, the sectional shape of the dustproof pellicle assembly frame 10 is substantially rectangular. Therefore, a large exposure area can be secured without increasing the rigidity of the pellicle frame 10 by enlarging the sectional area of the pellicle frame 10 or forming the pellicle frame from a highly rigid material or the like. Therefore, the pellicle can be manufactured at low cost, and the pellicle can be easily handled in a pellicle pasting apparatus or a photomask exposure machine during the manufacturing.

In addition, when the tension of the pellicle 20 is not uniform and is smaller than the design value, the short side 12 of the pellicle frame 10 may not be substantially linear and may still have a convex shape with respect to the outside. However, in the general dustproof thin film assembly sticking device, the dustproof thin film assembly is vertically arranged with the long side of the dustproof thin film assembly frame facing downwards, so that the protruding part of the short side 12 is pressed, and the dustproof thin film 20 cannot be folded.

Examples

The following examples and comparative examples are provided to illustrate the effects of the present invention.

Example 1

The pellicle frame 10 made of aluminum alloy having the shape shown in fig. 1 was fabricated by machining. The dimensions of the pellicle assembly frame 10 are: the outer dimensions are 2000mm by 2500mm, the inner dimensions 1960mm by 2460mm, substantially rectangular. The pellicle frame 10 has a substantially linear long side 11.

In contrast, the center region 12a of the short side 12 of the pellicle frame 10 has a convex circular arc shape of R72000mm with respect to the outside, the intermediate regions 12b, 12b on both sides of the center region 12a have a concave circular arc shape of R50000mm with respect to the outside, and the end-vicinity region 12c has a linear shape.

Here, the center of the short side 12 of the pellicle frame 10 protrudes 2.5mm outward from the imaginary line connecting the two corners at the two ends of the short side 12. The inner side of the short side 12 was 20mm wide, and formed in the same shape as the outer side of the short side 12, and the height was 6.5mm, and the inner radius of each corner was 2mm and the outer radius was 6 mm.

After the pellicle frame 10 was washed and dried, a silicon adhesive was applied as a pellicle adhesive to one surface, and a silicon adhesive (product name "KR 3700" available from shin-Etsu chemical industries) was applied as an adhesive for attaching a photomask to the other surface, and the respective materials were cured by heating.

Further, a fluorine-based polymer (product name "CYTOP" of Asahi glass Co., Ltd.) was formed on a quartz substrate of a square shape of 2200mm × 2580mm × 22mm by an open-hole spray method, and bonded to an aluminum alloy-made time frame 21 having the same shape as the quartz substrate, and then peeled off to prepare a pellicle film 20 having a thickness of about 4 μm.

The dust-proof film 20 stretched over the time frame 21 thus produced is set on a dust-proof film support 22 provided in the dust-proof film pack manufacturing apparatus, as shown in fig. 3 and 4.

Here, the load applying means 25 is adjusted so that the tensile force applied to the dust-proof film 20 by the load applying means 25 provided at the center of the short side of the temporary frame 21 becomes 2.5 times the tensile force applied to the dust-proof film 20 by the load applying means 25 provided at the center of the long side of the temporary frame 21.

On the other hand, the pellicle frame 10 having the pellicle adhesive layer 31 and the photomask adhesive layer 32 formed thereon and the photomask adhesive layer 32 protected by the spacer (not shown) is placed on the upper surface of the stage 30, and the stage 30 on which the pellicle frame 10 is placed is gradually raised by the raising/lowering mechanism 35 to bring the pellicle adhesive layer 31 into contact with the pellicle 20, thereby adhering the pellicle 20 to one surface of the pellicle frame 10. At this time, the stage 30 contacts the pellicle film 20 at a slight angle in order to prevent air from being trapped between the pellicle film adhesive layer 31 and the pellicle film 20.

After the dustproof pellicle 20 and the dustproof pellicle adhesive layer 31 formed on one surface of the dustproof pellicle frame are completely adhered, the unnecessary dustproof pellicle 20 on the outer side of the dustproof pellicle frame 10 is cut off on the carrier table 30 by a cutter, and the dustproof pellicle is manufactured.

As shown in fig. 2, the long side 11 of the dustproof pellicle assembly manufactured in this way is slightly warped inward, and the short side 12 thereof is substantially linear.

The pellicle was placed on a stage, and the shape of the pellicle frame was measured at 50mm intervals by moving a holder on which a dial gauge (dial gauge) made by mitsui corporation was mounted along a carbon steel rod. The contact surface of the reference bar of the dial gauge is polished in advance to have a flatness of 0.05mm or less.

As a result, the central portion of the one-side long side 11 of the pellicle frame 10 was warped inward by 1.5 mm. The deviation between the outer surface of the short side 12 of the pellicle frame 10 and the straight line connecting the corners of the short side ends is ± 0.3mm or less.

Comparative example 1

As shown in fig. 6, a pellicle frame made of aluminum alloy having a rectangular cross-sectional shape with each side formed substantially in a straight line shape was fabricated by machining. The dimensions of the pellicle assembly frame 10 are: the outer dimension is 2000mm × 2500mm, the inner dimension is 1960mm × 2460mm, and the rectangular shape is obtained. The pellicle frame 10 is 6.5mm high, with an inside radius of 2mm and an outside radius of 6mm at each corner. Using the pellicle frame, a pellicle was bonded by the same apparatus and process as in example 1 to produce a pellicle.

The pellicle frame 10 of the pellicle thus manufactured had a shape shown in fig. 7, and it was found that the central portion of the long side of the pellicle frame 10 was warped by about 1.5mm in the inward direction, and the central portion of the short side of the pellicle frame 10 was warped by about 2.5mm in the inward direction, and thus a significant warp occurred.

As a result, the exposure area was reduced by about 5mm in the major axis direction and by about 3mm in the minor axis direction.

Comparative example 2

The pellicle frame 10, the pellicle 20 and the apparatus having the same size and shape as those of comparative example 1 were attached to the pellicle frame 10 without adjusting the tension of the pellicle 20, and a pellicle was manufactured as in example 1.

The pellicle frame 10 of the pellicle thus manufactured had a shape shown in fig. 8, and it was found that the central portion of the long side of the pellicle frame 10 was warped by about 3.5mm in the inward direction, and the central portion of the short side of the pellicle frame 10 was warped by about 1.5mm in the inward direction, and thus a significant warp occurred.

As a result, the exposure area was reduced by about 3mm in the major axis direction and by about 7mm in the minor axis direction.

From example 1, comparative example 1 and comparative example 2, it can be seen that: by attaching the pellicle 20 stretched over the temporary frame 21 to one surface of the pellicle frame 10, the reduction of the exposure area of the photomask can be effectively prevented. Wherein, the central area 12a of the pair of short sides 12, 12 of the dustproof thin film assembly frame 10, which is basically equivalent to the central part, is in a convex arc shape relative to the outer side, the middle areas 12b, 12b positioned at both sides of the central area 12a are in a concave arc shape relative to the outer side, and the end near areas 12c, 12c near the short parts of the short sides 12 are in a linear shape; the tension of the pellicle 20 is controlled so that the tension in the direction parallel to the long axis of the long side 11 of the pellicle frame 10 is greater than the tension in the direction parallel to the short axis of the short side 12 of the pellicle frame 10.

The present invention is not limited to the above-described embodiments and examples, and various modifications are possible within the scope of the invention described in the claims.

For example, in the above embodiment and example 1, the pellicle frame 10 is constituted by the straight long side 11 and the short side 12, the central region 12a including the central portion of the short side 12 is formed in a convex arc shape with respect to the outer side, the intermediate regions 12b, 12b located on both sides of the central region 12a are formed in a concave arc shape with respect to the outer side, and the end vicinity regions 12c, 12c near the ends are formed in a straight line shape. However, the shorter side 12 of the pellicle frame 10 need not be formed in this shape. The short side 12 of the pellicle frame 10 may also be shaped: the two corners are joined by an arc having a curvature corresponding to the deformation of the pellicle assembly frame 10 due to the tension of the pellicle 20. Alternatively, the shorter side 12 of the pellicle frame 10 may be formed as a polygon with a plurality of short straight lines connecting the two corners.

In the above embodiment and example 1, the load detection unit 28 employs a load sensor. However, the load detection unit 28 may employ other load detection units instead of the load sensor. It is also possible to directly measure the displacement amount of the time frame 21 by using a distance measuring sensor or the like instead of the load detection unit, or to detect the displacement amount of the time frame 21 by detecting the movement amount of the load application unit 25.

In the above embodiment and example 1, tension is applied to both the long axis direction and the short axis direction of the temporary frame 21 on which the dust-proof film 20 is stretched. However, the tensile force may be applied only in the long axis direction of the time frame 21 on which the dust-proof film 20 is stretched, or may be reduced in the long axis direction of the time frame 21 on which the dust-proof film 20 is stretched, without applying the tensile force in both the long axis direction and the short axis direction of the time frame 21.

In the above embodiment and example 1, the grip 23 is provided in the center of each side of the temporary frame 21, and tension is generated in the major axis direction and the minor axis direction of the temporary frame 21 on which the dust-proof film 20 is stretched by displacing the grip 23 in the direction orthogonal to each side of the temporary frame 21. However, it is not necessary to generate tension in the long axis direction and the short axis direction of the temporary frame 21 in which the dust-proof film 20 is stretched by displacing the grip 23 provided at the center of each side of the temporary frame 21 in the direction orthogonal to each side of the temporary frame 21, but a plurality of grips 23 may be provided at each side of the temporary frame 21, and tension may be generated in the long axis direction and the short axis direction of the temporary frame 21 in which the dust-proof film 20 is stretched by displacing the grip 23 in the direction orthogonal to each side of the temporary frame 21. The grip 23 may be provided at a position other than the center of each side of the temporary frame 21 as long as the center of each side of the temporary frame 21 can be displaced.

In example 1, the load applying means 25 was adjusted so that the tensile force in the long axis direction of the pellicle frame 21 applied to the pellicle film 20 by the load applying means 25 provided at the center of the short side of the pellicle frame 21 was 2.5 times the tensile force in the short axis direction of the pellicle frame 21 applied to the pellicle film 20 by the load applying means 25 provided at the center of the long side of the pellicle frame 21. However, the tension of the dust-proof film 20 does not have to be set, and the tension in the long axis direction of the frame 21 applied to the dust-proof film 20 may be 2.5 times the tension in the short axis direction of the frame 21 applied to the dust-proof film 20. The tensile strength of the dust-proof film 20, the magnitude of the tension applied to the dust-proof film 20 in the initial state, the rigidity of the time frame 21 holding the dust-proof film 20, the allowable amount of short side projection of the time frame 21, and the like can be appropriately designed in consideration of the overall.

According to the present invention, it is possible to provide a pellicle for lithography capable of effectively preventing the occurrence of problems such as wrinkles in a pellicle attached to a pellicle frame by preventing the reduction of an exposure region even when the tension distribution of the pellicle is not uniform.

Further, according to the present invention, there can be provided a method for manufacturing a pellicle for lithography, which can prevent a reduction in an exposure region even when the tension distribution of the pellicle is uneven, and can effectively prevent the pellicle attached to the pellicle frame from wrinkling or the like.

Claims (14)

1. A pellicle for lithography, comprising

A pellicle frame having at least a pair of long sides each substantially in a linear shape and a pair of short sides each having a shape in which a central portion protrudes outward;

a pellicle is attached to one surface of the pellicle frame, and tension of the pellicle is adjusted so that tension in the direction of the pair of long sides of the pellicle frame is greater than tension in the direction of the pair of short sides of the pellicle frame;

the pair of short sides of the pellicle frame are substantially linear in shape.

2. The pellicle for lithography according to claim 1, wherein each of the pair of short sides of the pellicle frame includes:

a central region including a central portion of the short side and having a convex arc shape with respect to an outer side;

the middle area is positioned on two sides of the central area, and the relative outer side of the middle area is in a concave arc shape;

the end-part-near region is linear near both ends of the short side.

3. The pellicle of claim 2, where the intermediate areas each have a concave arc shape to the outside that smoothly connects the central area and the end-near areas.

4. The pellicle of claim 2, wherein the radius of the middle area having a concave arc shape to the outside is equal to or greater than 1/3 of the radius of the central area having a convex arc shape to the outside.

5. The pellicle of claim 3, wherein the radius of the middle area having a concave arc shape to the outside is greater than or equal to 1/3 of the radius of the central area having a convex arc shape to the outside.

6. A method for manufacturing a pellicle for lithography, comprising the steps of:

a pellicle frame having at least a pair of long sides and a pair of short sides, the long sides each having a substantially linear shape, the short sides each having a shape in which a central portion protrudes outward, the pellicle being attached to one surface of the pellicle frame;

the tension of the pellicle is adjusted so that the tension in the direction of the pair of long sides of the pellicle frame is greater than the tension in the direction of the pair of short sides of the pellicle frame;

deforming the pair of short sides of the pellicle assembly frame into a substantially linear shape.

7. The method of manufacturing a pellicle for lithography according to claim 6, wherein each of the pair of short sides of the pellicle frame includes:

a central region including a central portion of the short side and having a convex arc shape with respect to an outer side;

the middle area is positioned on two sides of the central area, and the relative outer side of the middle area is in a concave arc shape;

the end-part-near region is linear near both ends of the short side.

8. The method of manufacturing a pellicle for lithography according to claim 7, characterized in that the intermediate areas each have a concave arc shape with respect to the outer side, which smoothly connects the central area and the end vicinity area.

9. The method for manufacturing a pellicle for lithography according to claim 6, further comprising the steps of:

the method includes the steps of stretching the dustproof thin film on a temporary frame before attaching the dustproof thin film to the dustproof thin film assembly frame, and adjusting tension of the dustproof thin film by stretching and mechanically displacing a central portion of at least one pair of opposite sides of the temporary frame.

10. The method for manufacturing a pellicle for lithography according to claim 7, further comprising the steps of:

the method includes the steps of stretching the dustproof thin film on a temporary frame before attaching the dustproof thin film to the dustproof thin film assembly frame, and adjusting tension of the dustproof thin film by stretching and mechanically displacing a central portion of at least one pair of opposite sides of the temporary frame.

11. The method for manufacturing a pellicle for lithography according to claim 8, further comprising the steps of:

the method includes the steps of stretching the dustproof thin film on a temporary frame before attaching the dustproof thin film to the dustproof thin film assembly frame, and adjusting tension of the dustproof thin film by stretching and mechanically displacing a central portion of at least one pair of opposite sides of the temporary frame.

12. The method of manufacturing a pellicle for lithography according to claim 9, wherein when mechanically displacing the central portion of at least one pair of opposing sides of the temporary frame, the amount of displacement of the central portion of the at least one pair of opposing sides is detected by load detecting means or displacement amount detecting means for detecting a load applied to the central portion of the at least one pair of opposing sides, and the amount of displacement of the central portion of the at least one pair of opposing sides is controlled based on the amount of displacement detected by the load detecting means or displacement amount detecting means.

13. The method of manufacturing a pellicle for lithography according to claim 10, wherein when mechanically displacing the central portion of at least one pair of opposing sides of the temporary frame, the amount of displacement of the central portion of the at least one pair of opposing sides is detected by load detecting means or displacement amount detecting means for detecting a load applied to the central portion of the at least one pair of opposing sides, and the amount of displacement of the central portion of the at least one pair of opposing sides is controlled based on the amount of displacement detected by the load detecting means or displacement amount detecting means.

14. The method of manufacturing a pellicle for lithography according to claim 11, wherein when mechanically displacing the central portion of at least one pair of opposing sides of the mask, the amount of displacement of the central portion of the at least one pair of opposing sides is detected by load detecting means or displacement amount detecting means for detecting a load applied to the central portion of the at least one pair of opposing sides, and the amount of displacement of the central portion of the at least one pair of opposing sides is controlled based on the amount of displacement detected by the load detecting means or displacement amount detecting means.