JP2010066619A - Pellicle and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pellicle and a method for manufacturing the pellicle that prevents the deposition of a sulfuric acid on a photomask, resultantly preventing the deposition of the sulfuric acid on a substrate by appropriately eliminating, in a stage of manufacturing, sulfur oxides such as sulfuric acids or sulfur compounds such as organic sulfur components derived from a pellicle frame, which have a possibility of depositing the sulfuric acid on a photomask. <P>SOLUTION: The pellicle comprises a pellicle film 11 and a pellicle frame 12 wherein the pellicle frame 12 is subjected to alumite treatment using a sulfur compound, and subjected to cleaning treatment with hot water at 60°C or higher and 100°C or lower for 30 minutes or longer. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pellicle that is a dust-proof cover for a photomask and a method for manufacturing the pellicle.

  When manufacturing a semiconductor using a wafer or the like, a projection exposure method is used in which a pattern formed on a photomask is exposed by a projection optical system onto a substrate coated with a photosensitive agent such as a photoresist. In recent years, with the miniaturization of the pattern shape, the exposure light used tends to be shortened, and an exposure apparatus using KrF (wavelength 248 nm) or ArF (wavelength 193 nm) has been put into practical use. On the other hand, several tens of photomasks are used.

  These photomasks become foreign matter by adhering floating dust floating around during exposure, storage, or transportation. The foreign matter on the photomask hinders image formation at the time of exposure, so that a defect appears in the product. In order to prevent such poor resolution due to foreign matters adhering to the photomask surface, the photomask is equipped with a pellicle as a dust-proof cover having translucency on the surface (see, for example, Patent Document 1).

  Even in a photomask with a pellicle mounted, defects have recently occurred depending on the usage environment. This is because, in addition to the foreign matter floating around, the exposure and storage are repeated, so that the cause of fogging inside the member constituting the pellicle changes and becomes foreign matter, and the foreign matter gradually accumulates on the photomask. Is.

  If foreign matter accumulates over a certain amount on the photomask, the photomask becomes cloudy and defects appear in the product. For this reason, it is necessary to clean the photomask in order to remove fogging. However, the cleaning increases the cost for manufacturing the product and wears the pattern of the photomask.

In recent years, not only HAZE derived from photomask cleaning residues, but also the occurrence of HAZE derived from sulfuric acid used during anodizing and dyeing of the pellicle frame, which is a pellicle member, has attracted attention. Therefore, there is a need for a technique and member that does not allow sulfuric acid to adhere to the substrate of the photomask.
JP 2000-305254 A

  The present invention has been devised in view of the above problems, and in the production stage, a sulfur compound such as a sulfur oxide or an organic sulfur component derived from a pellicle frame that can cause sulfuric acid to adhere to a photomask. It is an object of the present invention to provide a pellicle that does not cause sulfuric acid to adhere to the photomask and, as a result, does not cause sulfuric acid to adhere to the substrate, and a method for manufacturing the pellicle by removing it as appropriate.

The invention according to claim 1 is a pellicle composed of a pellicle film and a pellicle frame. After the pellicle frame has been subjected to alumite treatment using a sulfur compound, the pellicle frame is washed with warm water of 60 ° C. or higher and 100 ° C. or lower for 30 minutes or longer. A pellicle characterized by being processed.
According to a second aspect of the present invention, in a pellicle comprising a pellicle film and a pellicle frame, the pellicle frame is washed with warm water of 60 ° C. or more and 100 ° C. or less for 30 minutes or more after performing a staining treatment using a sulfur compound. A pellicle characterized by being processed.
The invention according to claim 3 is the pellicle according to claim 1, wherein the amount of residual sulfuric acid present in the pellicle frame after the cleaning treatment is 1.0 μg or less per pellicle frame. .
The invention according to claim 4 is the pellicle according to claim 2, wherein the amount of residual sulfuric acid present in the pellicle frame after the cleaning treatment is 1.0 μg or less per pellicle frame. .
According to a fifth aspect of the present invention, there is provided a method for manufacturing a pellicle comprising a pellicle film and a pellicle frame, a step of performing an alumite treatment using a sulfur compound on the pellicle frame, and a temperature of 60 ° C. or higher and 100 ° C. after the alumite treatment. A method for producing a pellicle, comprising the following step of washing with warm water for 30 minutes or more.
The invention according to claim 6 is a method of manufacturing a pellicle comprising a pellicle film and a pellicle frame, a step of performing a staining process using a sulfur compound on the pellicle frame, and a temperature of 60 ° C. to 100 ° C. after the staining process. A method for producing a pellicle, comprising the following step of washing with warm water for 30 minutes or more.

  Since the pellicle of the present invention does not generate sulfuric acid-based HAZE, the sulfur compound contained in the pellicle member constituting the pellicle, particularly the pellicle frame, is removed at the pellicle manufacturing stage, so that the compound is exposed to the exposed portion of the photomask substrate. Can not be attached. Furthermore, by using the pellicle, the generation of the HAZE derived from the above can be suppressed and a stable photomask can be used.

Hereinafter, embodiments of the present invention will be described in detail.
FIG. 1A is a schematic top view showing an embodiment of a pellicle according to the present invention, and FIG. 1B is a schematic cross-sectional view of FIG. 1A taken along the line AA ′.

  The pellicle shown in FIGS. 1A and 1B includes a pellicle film 11 placed on a photomask 10, a pellicle frame 12, a mask adhesive 13, a pellicle adhesive 14, a pellicle inner wall member 15, and a filter 16. Consists of.

  The pellicle frame 12 is made of an aluminum material.

According to one aspect of the present invention, in a pellicle composed of a pellicle film and a pellicle frame, the pellicle frame is subjected to alumite treatment using a sulfur compound, and then is heated in hot water at 60 ° C. or higher and 100 ° C. or lower for 30 minutes or longer. Provided is a pellicle characterized by being washed. According to this configuration, sulfur compounds such as sulfuric acid or organic sulfur components derived from the pellicle frame that may cause sulfuric acid to adhere to the photomask can be appropriately removed at the manufacturing stage. Thus, it is possible to provide a pellicle that does not cause sulfuric acid to adhere to the substrate and consequently does not cause sulfuric acid to adhere to the substrate.
Appropriate temperature and time can be selected in view of elution of appropriate sulfur compounds such as sulfuric acid and thermal expansion of the pellicle frame, and it is more preferable to immerse warm water at 80 ° C for 120 minutes. It is.

The pellicle frame that has been cleaned is bonded to the pellicle film using a pellicle adhesive to form a pellicle.
An aluminum material can be suitably used as a pellicle frame material because of its strength and the like. However, in the case of a pellicle frame made of aluminum, it is necessary to anodize aluminum for the purpose of preventing reflection of exposure light when the substrate is exposed using a photomask.
For the alumite treatment, sulfuric acid, chromic acid, and oxalic acid are used, and sulfuric acid is preferably used for reasons such as good dyeability.
Usually, after the alumite treatment with sulfuric acid, a washing step using pure water at room temperature is provided, but when the present inventors cleaned a pellicle frame treated with alumite using normal temperature pure water, It was found that sulfuric acid remains on the surface, and sulfuric acid-based HAZE is generated by the sulfuric acid on the pellicle frame when the pellicle is mounted on a photomask for exposure.
In the present invention, by using warm water heated to 60 ° C. or more and 100 ° C. or less, preferably ultrapure water, sulfur compounds such as sulfuric acid adhering to the pellicle frame are sufficiently removed by alumite treatment. Thus, a pellicle that does not generate HAZE during exposure could be obtained.
The cleaning of the pellicle with warm water of the present invention is performed, for example, by immersing the pellicle frame in warm water of ultrapure water, but the cleaning method is not limited thereto as long as it is a method according to this.

The pellicle frame is formed by cutting an aluminum extruded mold with a saw. The height is adjusted by grinding the wheel. In addition, the corners of the frame are chamfered after machining, visual appearance inspection, and laser dimension measurement. Furthermore, alumite treatment is performed through cleaning, finish polishing, and short peening (or shot blasting).
In the alumite treatment of the pellicle frame, degreasing, nitric acid immersion, etching, ultrasonic cleaning and the like are performed before the electrolytic treatment with sulfuric acid as described above, and after the alumite treatment, dyeing treatment and sealing treatment are also performed.

  According to another aspect of the present invention, in a pellicle composed of a pellicle film and a pellicle frame, the pellicle frame is dyed using a sulfur compound and then heated in hot water of 60 ° C. or higher and 100 ° C. or lower for 30 minutes. A pellicle characterized by being washed as described above is provided. According to this configuration, sulfur compounds such as sulfuric acid or organic sulfur components derived from the pellicle frame that may cause sulfuric acid to adhere to the photomask can be appropriately removed at the manufacturing stage. Thus, it is possible to provide a pellicle that does not cause sulfuric acid to adhere to the substrate and consequently does not cause sulfuric acid to adhere to the substrate.

  Furthermore, according to the present invention, there is provided a pellicle in which the residual amount of sulfuric acid present in the pellicle frame after the washing treatment after the alumite treatment or staining treatment is 1.0 μg or less per pellicle frame. With such a pellicle, sulfuric acid can be prevented from adhering to the photomask substrate.

  Furthermore, the present invention includes a step of subjecting the pellicle frame to an alumite treatment using a sulfur compound, and a step of washing with hot water of 60 ° C. or more and 100 ° C. or less for 30 minutes or more after the alumite treatment or dyeing treatment. A pellicle manufacturing method is provided. Through these steps, a pellicle from which a sulfur compound such as sulfuric acid has been removed can be produced.

  According to the present invention, it is also possible to provide a pellicle characterized in that, in a pellicle composed of a pellicle film and a pellicle frame, the residual amount of sulfuric acid present when the product is used is 1.0 μg or less per pellicle. .

  In addition, as for the shape of the pellicle, only one rectangular shape has been described, but any shape may be used as long as it does not interfere with wafer exposure.

  A pellicle to which the pellicle frame of the present invention is attached will be described. The pellicle is a light-transmitting dust-proof cover installed on the photomask 10, a pellicle frame 12 for holding and unfolding the pellicle film 11, and a pellicle having a light-transmitting property and trapping foreign matter. A film 11, a pellicle adhesive 14 for bonding the pellicle frame 12 and the pellicle film 11, a mask adhesive 13 for bonding the pellicle frame 12 and the photomask 10, and a pellicle frame inside the pellicle frame 12 An inner wall member 15 and a pellicle frame 12 and a filter 16 that prevents inflow of contamination from a vent hole that adjusts the pressure inside the pellicle membrane inner space outside the pellicle frame 12 are provided.

  The pellicle film 11 is held by the pellicle frame 12 and is provided so as to cover the exposure area of the photomask 10. For this reason, the pellicle film 11 has translucency so as not to cut off energy by exposure. The pellicle frame 12 is affixed with a uniform force so as not to cause shadows on the photomask surface due to wrinkles or the like.

  As the pellicle film 11, a transparent film such as fluororesin or cellulose acetate, quartz glass, or the like is used. In particular, CYTOP (manufactured by Asahi Glass Co., Ltd.) is mainly used for a pellicle film for ArF laser exposure.

  The pellicle frame 12 is an alumite-treated aluminum frame, and the above-described hot water cleaning process is provided before the pellicle film is provided.

  The pellicle adhesive 14 is used to bond the pellicle frame 12 and the pellicle film 11. As the pellicle adhesive 14, a silicon resin-based, polyvinyl acetate resin-based, or acrylic resin-based adhesive is used. An adhesive that generates less gas is preferred.

  The mask adhesive 13 is used for bonding the pellicle frame 12 and the photomask 10. As the mask adhesive, a silicone resin-based or acrylic resin-based adhesive is used. Furthermore, an adhesive with less gassing is preferable.

  The pellicle film 11 is mounted on the photomask in order to prevent the foreign matter attached to the photomask from being focused and to prevent a resolution failure on the wafer. At this time, the pellicle is mounted so as to cover the exposure area of the photomask.

  The pellicle inner wall adhesive 15 is used to trap foreign matter existing in the pellicle space. Further, it is used to prevent foreign matter generated from the pellicle frame from entering the pellicle space.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further, this invention is not restrict | limited to the following example.

Pellicle frame made of aluminum material is alumite treated with sulfuric acid and then immersed in pure water at 80 ° C for 120 minutes and washed with pure water at room temperature without performing pure water treatment at 80 ° C for 120 minutes Two pellicle frames of the pellicle frame thus prepared were prepared, and a pellicle film was bonded to the two pellicle frames using a pellicle adhesive to obtain two types of pellicles. Each is a pellicle of the present invention and a conventional pellicle.
The two types of pellicle obtained were each mounted on a photomask. The photomask to be mounted was cleaned without using sulfuric acid, and the IC content (manufactured by DX-320 DIONEX) was used for the sulfuric acid content of the photomask created under these conditions at 100 ° C for 30 minutes. The sulfuric acid content was 0.1 μg / plate or less.

The photomask with the pellicle attached is placed in a space where the contamination of sulfuric acid or sulfur-based organic matter from the outside is removed (sulfuric acid 0.1 μg / m ³ or less, organic sulfur component is 0.1 ng / m ³ or less in terms of toluene) After storing in a metal case for 21 days, an ArF laser (manufactured by ximer-300 MPB) was irradiated on a photomask at 10 mJ at a wavelength of 50 mW / cm ² and 200 Hz. At this time, there was no change such as energy degradation. The exposure atmosphere was set to a ratio of N ₂ : O ₂ = 4: 1, and the atmosphere was passed through an acid, alkali, and organic chemical filter and contained no environmental contamination.

The amount of sulfuric acid present in the photomask was evaluated by ToF-SIMS (manufactured by TRIFT-II ULVAC-PHI). As a result of comparing the intensity of sulfate ion (HSO4 m / z97) adsorbed on the photomask surface with the total ion normalized and multiplied by 10,000,
The amount of sulfate ions adsorbed on the photomask surface using the pellicle of the present invention was 0.99. On the other hand, the amount of sulfate ions adsorbed on the photomask surface using a conventional pellicle was 30.06.

Further, the pellicle frame of the present invention before the pellicle membrane was ion-extracted by immersing it in 100 ml of pure water at 100 ° C. for 30 minutes, and the resulting extract was subjected to ion chromatography (IC) analysis (DX-320 DIONEX) The amount of sulfuric acid possessed by the frame was 1.0 μg per frame for the pellicle of the present invention.
On the other hand, when an analysis similar to the IC analysis of the present invention was performed, the amount of sulfuric acid possessed by the frame was 13.1 μg per frame for the conventional pellicle.

FIG. 2 shows a comparison between the pellicle of the present invention and the conventional pellicle. The left axis shows the amount of sulfate ion (HSO ₄ m / z97) obtained by ToF-SIMS, normalized by the total detected ion and multiplied by 10000, and the amount of sulfate ion on the photomask surface with the pellicle attached Is shown. On the other hand, the right axis is the amount of sulfuric acid obtained by extracting the frame with pure water at 100 ° C. for 30 minutes and obtained by IC, and indicates the amount of sulfate ions present on the photomask frame surface.

  Finally, as a result of manufacturing, storing, and inspecting the photomasks with these two types of pellicles under the same conditions, a 1 μg level product was detected from the photomask with the conventional pellicles. Although it occurred, sulfuric acid type HAZE was not detected from the photomask equipped with the pellicle of the present invention.

(A) is a schematic top view which shows one Example of the pellicle of this invention. (B) is a schematic cross-sectional view taken along line A-A ′ of (a). FIG. 3 is a comparative view of the pellicle of the present invention and a conventional pellicle. The left axis shows the result of normalizing sulfate ions (HSO4 m / z97) obtained by ToF-SIMS with all detected ions and multiplying by 10,000. The right axis shows the amount of sulfuric acid obtained by extracting the frame with pure water at 100 ° C. for 30 minutes.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Photomask 11 ... Pellicle film 12 ... Pellicle frame 13 ... Mask adhesive 14 ... Pellicle adhesive 15 ... Inner wall adhesive 16 ... Filter

Claims (6)

  A pellicle composed of a pellicle film and a pellicle frame, wherein the pellicle frame is subjected to alumite treatment using a sulfur compound and then washed with warm water of 60 ° C. or more and 100 ° C. or less for 30 minutes or more. Pellicle to do.   A pellicle comprising a pellicle film and a pellicle frame, wherein the pellicle frame is subjected to a dyeing process using a sulfur compound and then washed with warm water of 60 ° C. or more and 100 ° C. or less for 30 minutes or more. Pellicle to do.   2. The pellicle according to claim 1, wherein the amount of residual sulfuric acid present in the pellicle frame after the cleaning treatment is 1.0 μg or less per pellicle frame.   The pellicle according to claim 2, wherein the amount of residual sulfuric acid present in the pellicle frame after the cleaning treatment is 1.0 µg or less per pellicle frame.   In a method for producing a pellicle comprising a pellicle film and a pellicle frame, a step of performing an alumite treatment using a sulfur compound on the pellicle frame, and a washing treatment for 30 minutes or more with warm water of 60 ° C. or higher and 100 ° C. or lower after the alumite treatment And a method for manufacturing a pellicle, comprising:   In a method for producing a pellicle composed of a pellicle film and a pellicle frame, a step of performing a staining process using a sulfur compound on the pellicle frame, and a washing process for 30 minutes or more with warm water of 60 ° C. or more and 100 ° C. or less after the staining process And a method for manufacturing a pellicle, comprising:

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