JP2005250188A - Pellicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pellicle in which increase in pressure loss of a filter is suppressed and the time required for gas substitution is reduced even when the filter is clogged on gas substitution. <P>SOLUTION: The pellicle 1 is composed of: a pellicle frame 2 consisting of frame pieces 2a forming a square and having a through hole 4 open to the inside and outside of one of the frame pieces 2a; a filter 6 covering the outside opening 5 of the through hole 4; and a pellicle film 3 or a pellicle sheet 3 stuck to the upper face of the pellicle frame 2. The passing area of the gas flowing through the filter 6 is larger than the passing area of the gas flowing the inside opening 9 of the through hole 4. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a pellicle that is mounted on a photomask or reticle (hereinafter referred to as a reticle) used in an integrated circuit manufacturing process such as exposing and forming a circuit pattern on a substrate such as a semiconductor element for the purpose of preventing foreign matter adhesion.

  In an optical lithography process used in an integrated circuit manufacturing process, a pattern is formed by exposing a semiconductor wafer coated with a resist material. If scratches / foreign matter are present on the reticle used at this time, the scratches / foreign matter are transferred onto the wafer together with the pattern, causing a short circuit or disconnection of the circuit. For this reason, a pellicle is mounted on one or both sides of the reticle in order to prevent scratches on the surface of the reticle on which the circuit pattern is formed and foreign matter contamination.

In recent years, with the high integration of LSI, in the photolithography technology used in the manufacturing process, the wavelength of the light source has been shortened, and light of ArF excimer laser (193 nm) or F ₂ laser (157 nm) is used. It is going to be done. Lithography using a conventional light source is performed in the air. However, exposure with an F ₂ laser requires exposure in an inert gas atmosphere because oxygen molecules have absorption.

  Therefore, during exposure, the inside of the exposure apparatus is purged with a predetermined gas. At this time, the same gas is also introduced into the space formed by the pellicle and the reticle, that is, the pellicle from the gas introduction hole that penetrates the pellicle frame, and the air and gas in the pellicle are replaced. In order to prevent foreign matter from entering the pellicle during the introduction of the replacement gas, a filter is attached to the gas introduction hole.

  The conventional pellicle is provided with a through hole similar to that described above in order to prevent breakage of the pellicle membrane due to atmospheric pressure fluctuation during air transportation, and a filter is attached for the purpose of preventing entry of foreign matter when air flows in. Patent Document 1 describes a pellicle in which a filter is provided in the vent hole of such a pellicle frame. However, since the pellicle described in Patent Document 1 is obtained by simply sticking the filter to the pellicle frame, in the same method, the area through which the gas passes through the filter during gas replacement during exposure is equal to the opening of the vent hole. It is the same as the area. Accordingly, when the filter is clogged with the gas flow due to the gas replacement operation, the pressure loss of the filter itself increases, so that the flow rate of the filter gas with respect to the flow rate of the gas at the vent hole outlet is reduced. For this reason, it takes time to replace the gas, which hinders quick work.

  In this case, it may be possible to improve the efficiency of gas replacement by increasing the diameter of the vent hole. However, if the diameter is increased, the strength of the pellicle frame decreases, and there is a limit to simply increasing the diameter. The diameter of the vent hole is suitably 0.1 to 2.0 mm with respect to the height of the pellicle frame of 3.3 mm.

JP 2001-350252 A

  The present invention is based on the above prior art, and even if the filter is clogged during gas replacement, the pellicle is designed to reduce the time required for gas replacement by suppressing an increase in pressure loss of the filter itself. The purpose is to provide.

  In order to achieve the above object, according to the first aspect of the present invention, a pellicle frame comprising a frame piece forming a quadrilateral, and having a through hole that opens to the inside and the outside of any of the frame pieces, and an outer opening of the through hole. In a pellicle comprising a filter that covers the pellicle and a pellicle film or a pellicle plate attached to the upper surface of the pellicle frame, the gas passage area that passes through the filter passes through the inner opening of the through-hole. A pellicle characterized by being larger than an area is provided.

  The invention according to claim 2 is characterized in that a diameter of the outer opening is larger than a diameter of the inner opening.

  According to a third aspect of the present invention, the filter is a membrane filter having a large number of pores, and the filter is attached with a gap between the outer surface of the pellicle frame.

  The invention of claim 4 is characterized in that a plurality of the outer openings are covered with a common filter.

  The invention according to claim 5 is characterized in that the filter is a depth filter formed by weaving fibers and at least a part of which is press-fitted into the through hole.

  According to the first aspect of the present invention, the passage gas inlet is more than the gas passage area (that is, the opening area of the inner opening on the outlet side of the passing gas) of the inner opening of the through hole penetrating the frame piece of the pellicle frame. Since the passage area of the filter on the side is large, even if the filter is clogged, an increase in pressure loss of the filter itself can be suppressed as compared with the case where the passage area of the filter is the same as that of the conventional inner opening. Therefore, the gas replacement in the pellicle at the time of exposure can be performed quickly.

  According to the invention of claim 2, by making the diameter of the outer opening of the through hole larger than the diameter of the inner opening, the gas passing through the filter having a larger gas passage area than the inner opening is efficiently circulated to the through hole. The time for gas replacement in the pellicle during exposure can be shortened.

  According to the invention of claim 3, since the membrane filter (microfiltration membrane) having a large number of pores in the gas flow direction is attached with a gap with the pellicle frame, the gas flows through the gap through the gap portion. Therefore, the passage area of the filter increases.

  According to the invention of claim 4, for example, if a filter having a shape covering both the outer openings of adjacent through holes is used, the area of the filter itself is increased, the gas flow area is further increased, and one common Since the plurality of outer openings are covered with the filter, the attaching operation of the filter becomes simple.

  According to the fifth aspect of the present invention, a depth filter such as a ceramic filter or a sintered metal can be embedded in the through hole as a filter covering the outer opening, thereby increasing the gas passage area. Further, since no adhesive is required when attaching the depth filter, there is no need to consider the influence on the exposure performance due to the outgas generated from the adhesive.

FIG. 1 is a schematic view of a pellicle according to the present invention.
(A) is a top view of the pellicle frame, and (B) is a cross-sectional view when the pellicle according to the present invention is attached to the reticle. A pellicle 1 according to the present invention includes a pellicle frame 2 including a frame piece 2a forming a quadrilateral and a pellicle film 3 attached to the upper surface thereof. The pellicle 1 is attached to the reticle 11 with an adhesive (not shown) or the like, and protects the surface of the reticle 11. The pellicle frame 2 is formed with a plurality of through-holes 4 that are open on the outside and inside of the quadrilateral intermittently along the frame piece 2a (two in each figure on the left and right frame pieces 2a).

  (C) shows the cross section of the frame piece 2a on one side of the quadrilateral. An outer opening 5 that is an opening of the through hole 4 outside the pellicle frame 2 is covered with a membrane filter 6. The membrane filter 6 is attached to the pellicle frame 2 so that the periphery thereof has a gap 8 with an adhesive 7. The membrane filter 6 is a fluororesin microfiltration membrane having a large number of pores in the gas flow direction. The membrane filter 6 is for preventing dust from entering the pellicle 1 (contamination) during gas replacement during exposure.

  By having the gap 8 between the membrane filter 6 and the pellicle frame 2, the gas also flows through the portion of the membrane filter 6 that covers the gap 8, and the gas in the inner opening 9 on the gas outlet side of the through hole 4. Since the flow area of the membrane filter 6 on the gas inlet side is larger than the flow area (that is, the area of the inner opening 9), even if the membrane filter 6 is clogged, the conventional inner opening and the passage area of the filter As compared with the same case, the increase in pressure loss of the membrane filter 6 itself can be suppressed. Therefore, gas replacement in the pellicle 1 at the time of exposure can be performed quickly.

The pellicle 1 may be a pellicle frame 2 made of aluminum or the like and a pellicle film 3 made of an organic resin such as nitrocellulose or fluororesin having a thickness of several nm to several μm attached thereto with an adhesive. short-wavelength light by miniaturization and high densification, especially wavelength 220nm or less of the light, in particular ArF laser (wavelength 193 nm), considering durability against exposure light using a light such as _{F 2} laser (wavelength 157.6 nm) Alternatively, it may be a pellicle (hard pellicle) in which a pellicle plate made of synthetic quartz glass is attached to a pellicle frame.

FIG. 2 is a sectional view of another pellicle according to the present invention.
As shown to (A), the cross-sectional shape of the through-hole 4 is formed in a taper shape so that a diameter may spread gradually toward the outer opening part 5 from the middle of the through-hole 4. By increasing the opening area of the outer opening 5 in this way, the gas that has passed through the membrane filter 6 having a large distribution area can be distributed efficiently. It is assumed that the diameter of the outer opening 5 is increased to the extent that the strength of the pellicle frame 2 is not affected. As shown in (B), the diameter of the outer opening 5 may be widened so as to form a step without being tapered.

FIG. 3 is a side view of a pellicle frame of still another pellicle according to the present invention.
As shown in the figure, a plurality of through holes 4 (two in the figure) formed intermittently along the frame piece 2 a of the pellicle frame 2 may be covered with one common membrane filter 6. As described above, when the membrane filter 6 having a shape covering both the outer openings 5 of the adjacent through holes 4 is used, the area of the membrane filter 6 itself is increased, and the gap between the outer openings 5 and 5 of the through holes 4 and 4 is increased. Since gas flows also from the filter of the part to cover (arrow E part of the figure), the distribution area further increases. Therefore, the gas replacement time can be further shortened. Further, since the plurality of outer openings 5 are covered with one membrane filter 6, the attaching operation of the membrane filter 6 becomes simple.

FIG. 4 is a sectional view of still another pellicle according to the present invention.
As shown to (A), the depth filter 10 is embedded and attached to the through-hole 4 in which the outer side opening part 5 has a larger opening area than the inner side opening part 9. The depth filter 10 is formed of a ceramic filter or a sintered metal. Thus, even if the depth filter 10 is embedded in the through hole 4 having the large outer opening 5, the gas flow area can be made larger than that of the inner opening 9, so that pressure loss can be increased even if clogging occurs. Can be suppressed. Further, no adhesive is required when the depth filter 10 is attached, and since there is no outgas generated from the adhesive during exposure, the exposure performance can be improved. In order to prevent deterioration or deterioration of the filter due to exposure light or generation of outgas, it is preferable that the depth filter 10 does not protrude into the pellicle frame 2 from the inner opening 9 on the inner surface side of the frame piece 2a.

  As shown in (B), the depth filter 10 may protrude from the pellicle frame 2 rather than the outer opening 5. Since the depth filter 10 is formed by folding fibers, gas flows into the filter from multiple directions. Therefore, the larger the portion protruding from the pellicle frame 2 is, the larger the gas flow area is. Further, the increase in pressure loss can be suppressed and the time for gas replacement can be shortened. In the figure, the through-hole 4 has a larger outer opening 5 than the inner opening 9, but in this case, the opening area of the outer opening 5 and the inner opening 4 as shown in FIG. The same may be used. Other configurations, operations, and effects are the same as those in FIG.

  INDUSTRIAL APPLICABILITY The present invention is applicable to a pellicle attached to a reticle used in an optical lithography process used in a semiconductor integrated circuit manufacturing process, and particularly to suppress an increase in pressure loss of a filter during gas replacement of the pellicle. However, this filter can also be used effectively when dust is prevented from entering the pellicle during transportation of the pellicle.

1 is a schematic view of a pellicle according to the present invention. Sectional drawing of another pellicle which concerns on this invention. The side view of the pellicle frame of another pellicle concerning the present invention. Sectional drawing of another pellicle which concerns on this invention.

Explanation of symbols

1: pellicle, 2: pellicle frame, 2a: frame piece, 3: pellicle film, 4: through-hole, 5: outer opening, 6: membrane filter, 7: adhesive, 8: gap, 9: inner opening 10: depth filter, 11: reticle.

Claims (5)

A pellicle frame comprising a frame piece forming a quadrilateral, and having a through hole that opens to the inside and the outside of any one of the frame pieces;
A filter covering an outer opening of the through hole;
In a pellicle composed of a pellicle film or a pellicle plate attached to the upper surface of the pellicle frame,
A pellicle characterized in that a passage area of gas flowing through the filter is larger than a passage area of gas flowing through an inner opening of the through hole.   The pellicle according to claim 1, wherein a diameter of the outer opening is larger than a diameter of the inner opening.   The pellicle according to claim 1 or 2, wherein the filter is a membrane filter having a large number of pores, and the filter is attached with a gap between the filter and the outer surface of the pellicle frame.   The pellicle according to any one of claims 1 to 3, wherein the plurality of outer openings are covered with a common filter. The pellicle according to claim 1 or 2, wherein the filter is a depth filter formed by weaving fibers and at least a part of which is press-fitted into the through hole.

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