JP4195550B2 - Pellicle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pellicle, and more particularly, to a pellicle that has an adhesive layer that is light-resistant to short-wavelength light such as excimer light and is excellent in dust resistance and dust-free property.
[0002]
[Prior art]
Applying an adhesive substance to the inner wall of the pellicle frame is effective for preventing dust generation from the pellicle frame and fixing dust that floats or floats inside the pellicle and prevents it from adhering to the mask. It is. However, with the recent miniaturization of the mask circuit pattern, the wavelength of the light source used for exposure has been shortened. Because short-wavelength light is high energy, deterioration of the materials used in the past, such as scorching, evaporation, solidification, and fluidization, occurs to prevent dust generation or immobilize suspended matter. There is a problem with ability.
[0003]
[Problems to be solved by the invention]
Therefore, the main object of the present invention is to provide an adhesive layer that exhibits excellent holding performance for fixing floating substances such as dust and has excellent light resistance against short wavelength light such as excimer light. The object is to provide a pellicle having an inside of a frame.
[0004]
[Means for Solving the Problems]
According to the present invention,
A pellicle having a pellicle frame, a pellicle film stretched on the pellicle frame, and an adhesive layer provided inside the pellicle frame, wherein the adhesive layer contains fluororubber Provided.
[0005]
Preferably,
The fluororubber has the following formulas (1), (2) and (3)
[Chemical 8]
_{-C 2 F 4 - ... (1} )
[Chemical 9]
-C ₃ H _6- (2)
Embedded image
_{-C 2 H 2 F 2 - ...} (3)
A copolymer having a number average molecular weight in the range of 10,000 to 40,000. When the number average molecular weight is lower than the above range, the adhesive layer on the inner side of the pellicle flows during long-term storage and use. Further, the thickness decreases due to the flow and the foreign matter holding power decreases. On the other hand, if it is high, the foreign-matter holding power of the fluororubber itself decreases, which is not preferable.
[0006]
More preferably,
The fluororubber is represented by the following formula (4):
Embedded image
_{- (C 2 F 4) a} - (C 3 H 6) b - (C 2 H 2 F 2) c - ... (4)
(Where a, b, and c are each a positive integer)
And more preferably a 1,1-difluoroethylene / tetrafluoroethylene / propylene copolymer.
[0007]
Also preferably,
The fluororubber has the following formulas (1) and (2)
Embedded image
_{-C 2 F 4 - ... (1} )
Embedded image
-C ₃ H _6- (2)
A copolymer having a number average molecular weight in the range of 5,000 to 50,000. When the number average molecular weight is lower than the above range, the adhesive layer on the inner side of the pellicle flows during long-term storage and use. Further, the thickness decreases due to the flow and the foreign matter holding power decreases. On the other hand, if it is high, the foreign-matter holding power of the fluororubber itself decreases, which is not preferable.
[0008]
More preferably,
The fluororubber has the following formula (5)
Embedded image
_{- (C 2 F 4) a} - (C 3 H 6) b - ... (5)
(Where a and b are each a positive integer)
And more preferably a tetrafluoroethylene / propylene copolymer.
[0009]
In order to form an adhesive layer on the inner side of the pellicle frame, any one of the above fluororubbers, for example, the fluororesin described in formula (4) is dissolved in a solvent to prepare a coating solution. Then, this coating solution is applied to the inside of the pellicle frame and then dried to form an adhesive layer.
[0010]
The solvent is not particularly limited, and any solvent can be used as long as it dissolves any of the above fluororubber and can be applied to the inner wall of the pellicle. As the solvent, ketones and esters are preferably used. Since the ratio between the fluororubber and the solvent cannot be neatly applied when the viscosity is too high, it is preferable to adjust the concentration to about 5 to 40 wt% so that the viscosity is about 10 cp to 100 cp.
[0011]
【Example】
(Example 1)
Product name purchased from Asahi Glass Co., Ltd. as a fluororubber: Afras (1,1-difluoroethylene / tetrafluoroethylene / propylene copolymer [— (C ₂ F ₄ ) _a — (C ₃ H ₆ ) _b — (C _{2 H 2 F 2) c -]} ) was used. The number average molecular weight was 20,400. The solvent used was methyl ethyl ketone (Wako Pure Chemicals, reagent special grade). The coating solution was prepared by adding aphras to methyl ethyl ketone so as to be 20% by weight, and stirring to dissolve. Thereafter, insoluble matters and dust were filtered with a PTFE filter (pore diameter: 3 microns). The coating solution prepared in this way was applied by extending uniformly inside the pellicle frame using a needle having an outer diameter of 1.5 mm with a 0.5 mm lateral hole, thereby producing an inner wall coating layer.
[0012]
Next, the foreign substance holding force of the inner wall coat layer formed inside the pellicle frame was determined by an impact method. In the impact method, standard particles (material is glass) with a particle size of 105 to 125 microns are attached, and the pellicle frame is dropped from a height of 1 m. Then, it measured by the method of investigating the presence or absence of omission of the attached standard particle. In the measurement of the foreign matter retention force by this method, no drop of standard particles of 105 to 125 microns was observed.
[0013]
Next, the light resistance of the inner wall coat layer formed inside the pellicle frame was examined. Light resistance is irradiated with ArF excimer laser light (L5837 manufactured by Hamamatsu Photonics, frequency 500 Hz, wavelength 193 nm, energy density 1 (mJ / cm ² ) / pulse) to absorb the presence or absence of changes in the chemical structure of the inner wall coat layer. In addition to the measurement using the spectrum, the foreign matter retention force was measured by the impact method described above. The amount of irradiation energy was changed to 500, 800 and 1200 (J / cm ² ). As a result, in all cases, the foreign matter holding power by the impact method was not different from the experimental result when not irradiated, and no new absorption peak was generated or no absorption peak disappeared.
(Example 2)
The fluororubber of Example 1 was applied to the inside of the pellicle in the same manner as in Example 1 except that the fluororubber was changed to a tetrafluoroethylene / propylene copolymer [-(C ₂ F ₄ ) _a- (C ₃ H ₆ ) _b- ]. The foreign matter holding power and light resistance were examined. As a result, in the impact test, no standard particles of 105 to 125 microns were removed. Also, it was confirmed in the light resistance test that the foreign matter holding power did not change and the chemical structure did not change.
[0014]
(Comparative example)
Daifloyl # 100 (CTFE (chlorotrifluoroethylene) low polymer / manufactured by Daikin Industries, Ltd.) was dissolved in ethyl acetate to a concentration of 40% by weight, and the ratio of THV resin was 30: 1 with respect to the CTFE low polymer. Then, add THV Fluoroplastic THV200 (THV (vinylidene fluoride / tetrafluoroethylene / hexafluoropropylene copolymer) resin / manufactured by Sumitomo 3M) and stir well.
[0015]
The solution prepared in this manner was applied to the inside of the pellicle frame uniformly in the same manner as in Example 1 to produce an inner wall coat layer.
[0016]
Next, the foreign substance holding force of the inner wall coat layer formed inside the pellicle frame was determined by an impact method. In the impact method, standard particles (material is glass) with a particle size of 105 to 125 microns are attached, and the pellicle frame is dropped from a height of 1 m. Thereafter, the measurement was performed by a method for examining whether or not the attached standard particles were dropped. In the measurement of the foreign matter retention force by this method, no drop of standard particles of 105 to 125 microns was observed. Next, the light resistance of the inner wall coat layer formed inside the pellicle frame was examined. Light resistance was irradiated with ArF excimer laser light (L5837 manufactured by Hamamatsu Photonics, frequency 500 Hz, wavelength 193 nm, energy density 1 (mJ / cm ² ) / pulse). Then, it was found that the inner wall coat layer evaporated with an irradiation energy amount of less than 500 J / cm ² and did not have the light resistance required for an ArF pellicle.
[0017]
【The invention's effect】
According to the present invention, an adhesive layer that exhibits excellent holding performance for fixing floating substances such as dust and has excellent light resistance against short wavelength light such as excimer light is provided inside the pellicle frame. A pellicle is provided.

Claims (4)

A pellicle having a pellicle frame, a pellicle film stretched on the pellicle frame, and an adhesive layer provided inside the pellicle frame,
The adhesive layer contains a fluororubber, and the fluororubber is a copolymer containing structural units represented by the following formulas (1) and (2), wherein the number average molecular weight is in the range of 5000 to 50000 A pellicle that is a coalescence .

The fluororubber is a fluorine-containing resin represented by the following formula (5), according to claim 1 pellicle according.

(Where a and b are each a positive integer) The fluororubber is a copolymer composed of structural units represented by the following formulas (1), (2) and (3), and is a copolymer having a number average molecular weight in the range of 10,000 to 40,000 . The pellicle according to claim 1.

The pellicle according to claim 3 , wherein the fluororubber is a fluororesin represented by the following formula (4).

(Where a, b, and c are each a positive integer)