HK1149089A - Pellicle - Google Patents

Description

Dustproof film assembly

Technical Field

The present invention relates to a pellicle used as a dust-proof device in the production of products such as semiconductor devices, printed circuit boards, and liquid crystal displays.

Background

In the manufacturing process of semiconductor devices such as LSI and super LSI, or products such as liquid crystal displays, a semiconductor wafer or a liquid crystal master is irradiated with light to form a pattern, and if dust adheres to a photomask or reticle (hereinafter, referred to as a photomask), the dust absorbs the light and reflects the light, thereby deforming the transferred pattern, roughening the edge, and also blacking the substrate to deteriorate the size, quality, appearance, and the like.

Therefore, these operations are usually performed in a clean room, but even then, it is difficult to keep the mask clean all the time. Then, the pellicle is attached to the surface of the photomask and then exposure is performed. At this time, the foreign matter is not directly attached to the mask surface but attached to the pellicle, so that the foreign matter on the pellicle does not affect the transfer as long as the pattern of the mask is brought into focus during photolithography.

In general, a pellicle is formed by attaching or bonding a transparent pellicle film made of a substance having good light transmittance, such as nitrocellulose, cellulose acetate, or fluororesin, to the upper end face of a pellicle frame made of a substance such as aluminum, stainless steel, or polyethylene. An adhesive layer made of polybutylene resin, polyvinyl acetate resin, acrylic resin, or the like for attaching to the mask and a release layer (spacer) for protecting the adhesive layer are provided at the lower end of the pellicle frame.

Then, in a state where the pellicle is attached to the mask, in order to eliminate a difference in air pressure between the space surrounded by the interior of the pellicle and the outside, a small hole for air pressure adjustment is formed in a part of the pellicle frame, and a filter element is provided to prevent foreign matter from entering the interior of the pellicle frame from air flowing through the small hole (see patent document 1).

The collection aperture and area of the filter element are usually considered to obtain desired foreign matter collection performance and air permeability, and when only 1 filter element is provided, the desired air permeability cannot be obtained, a plurality of filter elements may be provided. For example, in many cases, only 1 pellicle is provided in a pellicle for use in semiconductor manufacturing, whereas in a pellicle for large-sized liquid crystal manufacturing in which 1 side exceeds 500mm, 8 to several tens of pellicle are generally provided in order to ensure air permeability.

The filter element used here is generally a sheet-like member obtained by stretching a material such as PTFE into a porous membrane to be used as a gas permeable membrane, and is a commonly used member that is suitable for use in a dustproof membrane module from the viewpoints of cost, shape, and the like. As shown in FIG. 4, an adhesive layer 43 for bonding to a frame is annularly arranged on one surface of a filter element air-permeable membrane 41, and a protective net 42 in a coarse mesh form made of PP or the like for protecting the filter element air-permeable membrane 41 is bonded to the surface on the opposite side, thereby forming a 3-layer structure, and the thickness of the whole is about 0.15 to 0.3 mm. In order to prevent the generation of dust, the filter element may be coated or impregnated with an adhesive material (see patent document 2).

The pellicle frame is generally cleaned with a surfactant or ultrasonically in pure water. At this time, although the inside of the vent hole is also cleaned by the ultrasonic waves in the liquid, the cleaning effect is generally inferior to that of the surface of the pellicle assembly frame (other than the hole portion) because the ultrasonic waves are less likely to penetrate into the inside of the vent hole. In particular, in a large pellicle assembly having a side exceeding 500mm, since the frame width is wide and the vent hole is long, the cleaning efficiency is significantly deteriorated. Further, when the inside of the vent hole is inspected for foreign matter after cleaning, there is a problem that the inside of the vent hole is hardly visually observed.

Further, the filter element is usually mounted in such a manner as to cover the ventilation hole on the outer surface of the dustproof thin film assembly frame. Therefore, for example, when the filter element is vibrated by blowing air to the membrane surface, the membrane surface may be scratched by contacting the peripheral edge portion of the ventilation hole, and dust may be generated. The dust generated at this portion may cause a serious problem in that foreign matter adheres to the mask pattern because it is in the inner region of the pellicle.

[ patent document ]

[ patent document 1] Japanese Kokoku publication Sho 63-39703

[ patent document 2] Japanese patent application laid-open No. H09-068792

Disclosure of Invention

Problems to be solved by the invention

The present invention provides a pellicle, wherein a frame of the pellicle is provided with a vent hole for adjusting the air pressure inside and outside the pellicle to be the same air pressure, and a filter element for preventing particles from entering the interior of the pellicle through the vent hole, wherein the pellicle comprises: the device has no doubt of generating dust from the vent hole or the filter element in use, and has very high reliability.

Means for solving the problems

The present invention provides a pellicle for adjusting the air pressure inside a pellicle to be the same as the air pressure outside, the pellicle frame being provided with a vent hole, and a filter element for preventing particles from entering the pellicle being provided in the vent hole, the pellicle comprising: a chamfer of C0.5 to C1.0 or R0.5 to R1.0 is provided on the peripheral edge of the vent hole in the pellicle frame. Generally, the peripheral edge of the vent hole is naturally chamfered by a treatment such as sandblasting or the like to reduce dust generated from the peripheral edge by chamfering, and also to prevent dust from being generated when the filter element membrane comes into contact with the peripheral edge of the vent hole.

In the pellicle of the above, the vent hole provided in the pellicle frame is enlarged (tapered) from the inner surface side to the outer surface side of the frame. If the vent hole diameter is gradually increased, it becomes easier to visually observe the inside of the vent hole after cleaning, and it contributes to ultrasonic waves penetrating into the inside of the vent hole during cleaning, thereby improving the cleaning effect.

In the pellicle of the same manner as above, the surface roughness Ra of the wall surface of the vent hole is set to 1 μm or less. For example, the cleaning effect can be improved and foreign matters are less likely to adhere to the surface of the substrate.

In addition to the above-described aspect of the invention, the dust-proof membrane module can further eliminate the possibility of dust generation during use by coating or impregnating the air-permeable membrane of the filter element to which the dust-proof membrane module is attached with an adhesive substance.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, since the peripheral edge of the vent hole is chamfered and the diameter of the vent hole is gradually increased from the inner surface side to the outer surface side, dust generated from the peripheral edge can be greatly reduced, and whether or not foreign matter remains in the vent hole can be accurately checked. Further, since the inner wall of the vent hole has a small surface roughness, the cleaning efficiency is high and the possibility of adhesion of foreign matters is small. Thus, a dustproof membrane module is provided which is free from the concern of generation of foreign matter from the vent hole or the periphery of the filter element in use and has high reliability.

Drawings

FIG. 1 is a sectional view of a pellicle frame according to an embodiment of the present invention, in the vicinity of a vent hole provided with R-chamfered peripheral edges at both ends.

Fig. 2 is a sectional view of the vicinity of a vent hole of another embodiment of the present invention, the vent hole being provided in a gradually enlarged shape.

Fig. 3 is a sectional view of the vicinity of a vent hole showing an embodiment in which a portion is formed to be gradually enlarged in combination with a peripheral portion provided to be chamfered.

Fig. 4 is a schematic view of the construction of the filter element.

Fig. 5 is a schematic view of the appearance of the dustproof thin film assembly.

Fig. 6 is a schematic view of a related art vent hole in the vicinity thereof.

Fig. 7 is a schematic diagram for explaining a method of evaluating whether dust is generated in the filter element.

Description of the reference numerals

11 dustproof pellicle assembly frame

12 venthole

13 thin film bonding layer

14 dustproof film

15 photo mask adhesive layer

16 Filter element

17 (of the vent hole) peripheral edge portion

21 dustproof pellicle assembly frame

22 air vent

23 thin film bonding layer

24 dustproof film

25 photo mask adhesive layer

26 Filter element

31 dustproof pellicle assembly frame

32 air vent

33 thin film bonding layer

34 dustproof film

35 photo-mask adhesive layer

36 Filter element

37 (of vent hole) peripheral edge portion

3a vent hole diameter part

3b increasing major diameter of vent hole

3c peripheral edge R chamfer radius

41 filter element vent membrane

42 protective net

43 adhesive layer

61 dustproof pellicle assembly frame

62 venthole

63 thin film bonding layer

64 dustproof film

65 photo mask adhesive layer

66 filter element

71 glass substrate

72 dustproof pellicle

Detailed Description

Hereinafter, embodiments for carrying out the present invention will be described, but the present invention is not limited thereto. The present invention is particularly effective in a large dustproof pellicle assembly having a wide frame width (long vent hole), used for liquid crystal manufacturing, and having a length exceeding 500mm, but is not particularly limited in its application since the present invention can obtain desired effects even when applied to a small dustproof pellicle assembly having a narrow frame width (short vent hole) and having a length of about 150mm, used for semiconductor.

Fig. 4 shows the construction of a filter element used in the present invention. The filter element air-permeable membrane 41 is a porous membrane made of PTFE or the like, and has an adhesive layer 43 provided on the bottom surface thereof for adhesion and fixation to the dustproof membrane module frame, and a protective net 42 provided on the top surface thereof for protecting the filter element air-permeable membrane. Since the adhesive layer 43 is provided in a ring shape, gas can be flowed through the filter element membrane 41 exposed at the center.

Fig. 1 is a sectional view showing the vicinity of a vent hole in an example in which both end peripheral edges 17 of the vent hole 12 of a pellicle frame 11 according to an embodiment of the present invention are chamfered R. When the machining tool cannot be R-chamfered (circular chamfer), a straight chamfer may be used, but it is preferable to provide the R-chamfer from the viewpoint of preventing generation of dust.

Here, the size of the chamfer (in the case of the R chamfer in the figure, the radius of curvature) of the peripheral edge portion 17 is preferably in the range of 0.5 to 1.0 mm. If the thickness is 0.5mm or less, the degree of chamfering is insufficient, the effect is insufficient, and in addition, the machining becomes difficult with a too small size. On the contrary, if it is set to be larger than 1mm, the influence on the frame rigidity is too large, and it is not significant to improve the cleaning efficiency or inspection efficiency in the vent hole, and moreover, it is disadvantageous in that the size of the filter element 16 to be mounted tends to be large, and the tolerance required for the mounting position becomes strict, and the like, so that it is not preferable.

If the peripheral edge 17 of the end of the ventilation hole is chamfered, even if a strong airflow is blown from the outside to the filter element 16 to recess the filter element 16 and contact the peripheral edge 17 of the ventilation hole, since it is not a sharp portion, dust is hardly generated by friction. Further, the opening of the peripheral edge portion 17 is increased, and there is an advantage that it is relatively easy to visually check whether or not foreign matter is present in the vent hole 12 after the pellicle frame 11 is cleaned.

In this embodiment, the peripheral edge portions 17 on both the outer side and the inner side of the pellicle frame 11 are chamfered by R, but it is not always necessary to perform only on the outer side in view of cost.

FIG. 2 is a sectional view showing the vicinity of a vent hole according to another embodiment of the present invention. The ventilation hole 22 is provided so as to gradually increase from the inner surface side to the outer surface side of the pellicle frame. Therefore, when the inside of the vent hole is visually observed from the outside after the dustproof thin film assembly frame is cleaned, whether foreign matters exist in the vent hole can be easily and deeply inspected, and the inspection accuracy is greatly improved in addition to the improvement of the working efficiency.

In this case, the surface roughness Ra in the vent hole is preferably 1 μm or less, more preferably 0.5 μm or less. The roughness is obtained by drilling, reaming, polishing with a grindstone, chemical polishing with a chemical solution, or electrolytic polishing, if necessary.

Since the inner wall of the vent hole is smoothed, the cleaning efficiency is greatly improved, and the possibility that foreign matter remains inside the vent hole after cleaning is reduced. Further, the surface is smoothed, and it is relatively easy to check whether or not foreign matter remains. Further, the possibility of adhesion of foreign matter is also reduced in the manufacturing process.

In addition, from the viewpoint of improving the inspection efficiency, there is a solution that the diameter of the vent hole is increased. However, even if the aperture diameter is increased, the effect is remarkably deteriorated as compared with the gradually increasing shape because there is no facing surface facing the visual direction. Further, although the inspection efficiency can be improved by increasing the hole diameter, the frame rigidity is lowered as the hole diameter is increased.

Then, the above-described means of the present invention can be combined in various ways to further improve the effect.

For example, it is preferable to provide a chamfer on the peripheral edge of the vent hole shown in FIG. 1, and to further perform a machining process so that Ra of the inner wall of the vent hole is 1 μm or less, or to perform a machining process so that Ra of the surface roughness of the inner wall of the gradually enlarged vent hole shown in FIG. 2 is 1 μm or less. The taper angle is gradually increased, although not limited, and a top angle of around 5 ° is not problematic.

FIG. 3 is a cross-sectional view showing the vicinity of a vent hole in an embodiment in which a portion of the vent hole is formed with a chamfer of a peripheral edge portion that gradually increases.

At this time, the combined effect of the above 2 embodiments can be obtained. Since the vent hole 32 is formed to have a portion gradually enlarged and the peripheral edge portion 37 is formed to be R-chamfered, it is relatively easy to inspect whether or not there is a foreign object from the outer surface side, and the inspection accuracy is also relatively high. Further, since the peripheral edge portion 37 is chamfered to R, there is no sharp portion in the vicinity of the air-permeable membrane of the filter element 36, and the risk of generating dust is greatly reduced.

In this embodiment, the whole of the vent holes are not gradually enlarged as shown in fig. 2, but a partial region in the vicinity of the inner side of the frame is set to a normal hole diameter. From the viewpoint of processing means, since the shape is not necessarily provided as described above, there is no difference in effect between the two.

In the structure of FIG. 3, it is preferable that the surface roughness Ra of the inner wall of the vent hole is 1 μm or less. Thus, a dust-proof pellicle assembly excellent in preventing dust from being generated in the peripheral edge portion 37 of the vent hole and the filter element 36, in cleaning efficiency of the vent hole, and in ease of inspection can be obtained.

Here, if the filter element 36 is attached by coating or impregnating with an adhesive substance, the dustproof membrane assembly can be used without any fear of generating dust. In general, the filter element is not manufactured in a clean room environment, and even when it is manufactured in a clean room environment, it is impossible to completely prevent the adhesion of foreign materials until the finished product is obtained through several stages of punching processes. Therefore, although the foreign matter adhered to the filter element may fall off when air is circulated, the adhered foreign matter can be completely fixed to the surface of the filter element by coating or wetting with the adhesive substance.

Here, as the adhesive substance, a silicone adhesive, an acrylic adhesive, or the like can be used. Such adhesives are diluted to several% with a solvent and applied with a proper amount of a tool such as a precision applicator. The concentration of the solution or the amount of the liquid to be impregnated may be determined as appropriate within a range in which the air permeability of the filter element can be ensured.

[ examples ]

The following describes examples of the present invention, but the present invention is not limited thereto.

The pellicle frame of the shape shown in fig. 5 was produced from a rolled sheet of a5052 aluminum alloy by machining, and its outer dimensions were 1526 × 1748mm, inner dimensions were 1493 × 1711mm, and height was 6.2 mm. The frame was provided with 16 vent holes, each of which had a cross-sectional shape as shown in fig. 3. Here, the dimensions in the figure are: 3a 1.5mm, 3b 2.2mm, and 3c (radius of curvature) 0.5 mm. The Ra of the inner wall of the vent hole 32 was polished to 0.5 μm. Then, after the machining is completed, the frame surface is subjected to sand blasting and then black alumina (black alumina) treatment.

The frame was cleaned and dried in a clean room of Class10, and then inspected for foreign matter in a dark room. Of course, the inside of the vent hole was also inspected for foreign matter, and it was confirmed that no foreign matter remained inside from a careful observation from the outside of the frame.

A silicone adhesive diluted with toluene and dried to a film thickness of about 100 μm was applied to the upper end surface of the frame [ manufactured by shin-Etsu chemical industries (Ltd.); KR3700 as the dustproof film bonding agent 33. Then, a silicone adhesive diluted with toluene and having a width of 6mm [ manufactured by shin-Etsu chemical industries (Ltd.); KR3700 as the mask adhesive 35. At this time, the height of the adhesive is about 2 mm.

Then, a PTFE filter element having a structure shown in fig. 4 obtained by punching was attached to each vent hole with tweezers, and a silicone adhesive diluted with toluene [ made by shin-Etsu chemical industry (Strand) ]; KR3700 is applied to the surface of the filter element 36 by a hand coater to allow the adhesive to wet the filter element.

Then, the frame was heated to 130 ℃ to dry the solvent in the adhesive or bonding agent and completely crosslink the silicone adhesive, and then the separately prepared spacer was bonded to the mask adhesive layer as an adhesive protection member. The separator was made by cutting a PET film (125 μm thick, translucent) coated with a release agent on one surface into a frame shape.

Next, the manufacturing process of the dustproof film is described in detail. In the clean room, a quartz substrate having a smooth polished surface and a size of 1620 × 1780mm was cleaned, dried, and then coated with a fluorine resin [ manufactured by asahi glass (strand) ] on one surface thereof by a die coating method; the film was obtained under the trade name Cytop, and had a thickness of 6 μm after drying. The film forming method is herein a die coating method, but various other methods such as a spin coating method, a slit and spin coating method, and the like may also be used. Thereafter, each film-forming substrate was heated to 200 ℃ in an oven, and the solvent was dried. Then, after cooling, a frame-shaped film peeling tool was bonded to the film, and then the film was peeled off and peeled off from the substrate gradually, thereby obtaining a peeled film.

Finally, the peeling film is attached to the film bonding layer of the frame, and the excess film on the outer side is cut off by a cutter, thereby completing the dustproof film assembly.

The completed dustproof membrane assembly was evaluated for the characteristic of whether dust was generated when the air flow was blown to the filter element.

First, a quartz glass substrate having a thickness of 1620 × 1780 × 10mm and a polished surface was prepared, cleaned and dried in the clean room, and then inspected in a dark room for the presence of foreign matter remaining on the substrate with a condenser lamp. The foreign matter adhering to the surface is removed by an air blower, and the position of the foreign matter which cannot be removed is accurately recorded by a map.

Then, as shown in fig. 7, the produced pellicle 72 is bonded to the quartz glass substrate 71, thereby producing a sealed space surrounded by the pellicle 72 and the glass substrate 71. Then, 5 of the filter element sections (not shown) of all the dustproof membrane modules 72 are arbitrarily selected, and an air flow is blown from the outside. The conditions of air flow blowing are that the caliber of a nozzle is: 2mm, distance: 20mm, pressure: about 392kPa (4 kgf/cm)²) And blowing time: for 10 seconds.

Then, after the air flow was blown to the filter element, the foreign matter on the quartz glass substrate 71 was visually inspected with a condenser lamp in a dark room, and compared with an inspection chart before the air flow was blown. As a result, it was found that foreign matters were not increased.

[ comparative example ]

The pellicle frame of the shape shown in fig. 5 was produced from a rolled sheet of a5052 aluminum alloy by machining, and its outer dimensions were 1526 × 1748mm, inner dimensions were 1493 × 1711mm, and height was 6.2 mm. The frame is provided with 16 vent holes 62 having the same cross-sectional diameter as shown in fig. 6 and a diameter of 1.5 mm. After the machining, the surface of the frame was subjected to sand blasting and then to black alumite treatment. Further, the roughness Ra of the inner wall surface of the vent hole 62 was measured to be about 2 to 4 μm.

Then, in the same manner as in the above example, the frame was cleaned and dried in a clean room of Class10, and the presence or absence of the adhesion of foreign matter was confirmed in a dark room. At this time, the inside of the vent hole is also inspected for foreign matter, and the state of the inside of the vent hole cannot be clearly confirmed because the vent hole is narrow and deep.

Then, a film adhesive 63 and a mask adhesive 65 were applied to the frame in the same manner as in the above-described examples, and the filter element having the shape shown in fig. 4 was attached with tweezers. Then, the frame was heated to 130 ℃ to dry the solvent and completely crosslink the silicone adhesive, and a separately prepared spacer was attached to the mask adhesive layer as an adhesive protection member.

Finally, the dustproof film thus produced was attached to the film joining layer of the frame in the same manner as in the above-described embodiment, and the excess film outside the frame was cut off with a cutter, thereby completing a dustproof film assembly.

The evaluation of the pellicle was performed in the same manner as in the above-described example, and as shown in FIG. 7, whether or not dust was generated was evaluated by blowing air from the outside to the filter element of the pellicle 72 attached to the glass substrate 71. As a result, it was found that several foreign substances having a diameter of 10 to 20 μm were attached to the glass substrate in the vicinity of 2 of the 5 vent holes.

Claims (4)

1. A pellicle frame is provided with a vent hole for adjusting the air pressure inside the pellicle to be the same as that outside, and a filter element for preventing foreign matter from entering the inside of the pellicle is attached to the vent hole, wherein the peripheral edge of the vent hole is provided with a chamfer of C0.5-C1.0 or a chamfer of R0.5-R1.0.

2. A pellicle wherein a frame is provided with a vent hole for adjusting the air pressure inside the pellicle to be the same as that outside, and a filter element for preventing foreign matter from entering the inside of the pellicle is attached to the vent hole, characterized in that the vent hole is enlarged from the inner surface side of the frame to the outer surface side thereof so as to be gradually enlarged.

3. A pellicle wherein a frame is provided with a vent hole for adjusting the air pressure inside the pellicle to be the same as that outside, and a filter element for preventing foreign matter from entering the inside of the pellicle is attached to the vent hole, characterized in that the surface roughness Ra of the inner wall of the vent hole is 1 [ mu ] m or less.

4. The dustproof membrane assembly of any one of claims 1 to 3, wherein an adhesive substance is coated or impregnated on the filter element.