Pellicle frame and pellicle

Abstract

The present invention provides; a pellicle frame which can effectively inhibit distortion of the photo mask (8) caused by mounting the pellicle (1), and which does not have a complex shape, and a pellicle which uses said pellicle frame are provided, and a manufacturing method of a blackened pellicle frame is also provided which can reduce the defect of the surface flickering under concentrated light and which facilitates inspection of the foreign matter adhesion prior to use. The present invention relates to a pellicle frame with an anodized film on a surface of an aluminum alloy frame, characterized in that: the aluminum alloy frame comprises an aluminum alloy which contains Ca: 5.0 to 10.0% by mass with the remainder aluminum and unavoidable impurities are contained, and has an area (volume) ratio of an Al.sub.4Ca phase, which is a dispersed phase, is greater than or equal to 25%, and a crystal structure of a part of the Al.sub.4Ca phase is monoclinic; wherein the Al.sub.4Ca phase dispersed in the anodized film is anodized, and the anodized film is stained with a black dye.

Claims

1. A pellicle frame with an anodized film on a surface of an aluminum alloy frame, characterized in that: the aluminum alloy frame comprises an aluminum alloy which contains Ca: 5.0 to 10.0% by mass with the remainder aluminum and unavoidable impurities are contained, and has an area (volume) ratio of an Al.sub.4Ca phase, which is a dispersed phase, is greater than or equal to 25%, and a crystal structure of a part of the Al.sub.4Ca phase is monoclinic; wherein the Al.sub.4Ca phase dispersed in the anodized film is anodized, and the anodized film is stained with a black dye.

2. The pellicle frame according to claim 1, wherein a V content and a Fe content of the aluminum alloy are 0.0001 to 0.005% by mass and 0.05 to 1.0% by mass, respectively.

3. The pellicle frame according to claim 1, wherein an average crystal grain size of the Al.sub.4Ca phase is 1. 5 m or less.

4. The pellicle frame according to claim 1, further comprising a resin film on the anodized film.

5. A method for manufacturing a pellicle frame, comprising: a first step for obtaining an aluminum alloy plastic worked by subjecting an aluminum alloy ingot which contains 5.0 to 10.0% by mass of Ca with the remainder aluminum and inevitable impurities, and has a volume ratio of an Al.sub.4Ca phase which is a dispersed phase of 25% or more to a plastic working, a second step for subjecting the aluminum alloy plastic worked to a heat treatment in a temperature range of 100 to 300 C., and a third step for subjecting the heat-treated aluminum alloy plastic worked to an anodizing treatment with an alkaline electrolytic solution containing tartaric acid as an electrolyte.

6. The method for manufacturing a pellicle frame according to claim 5, wherein, before the first step, the aluminum alloy ingot is subjected to a heat treatment where the ingot is maintained at a temperature of 400 C. or more.

7. A pellicle comprising the pellicle frame according to claim 1 and a pellicle film supported by the pellicle frame.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic cross-sectional view showing one example of the pellicle of the present invention configured using the pellicle frame of the present invention.

(2) FIG. 2 is a schematic plan view showing one example of the pellicle frame of the present invention.

(3) FIG. 3 is an X-ray diffraction pattern of the aluminum alloy plastic worked obtained in Example.

(4) FIG. 4 is an optical microscopic photograph of the cross section of the pellicle frame of Example.

EMBODIMENTS FOR ACHIEVING THE INVENTION

(5) Hereinafter, representative embodiments of the pellicle frame and the pellicle of the present invention will be described in detail with reference to the drawings, but the present invention is not limited to only these examples. In the following description, the same or equivalent parts are denoted by the same numerals, and there is a case that redundant explanation may be omitted. In addition, since the drawings are for conceptually explaining the present invention, dimensions of the respective constituent elements expressed and ratios thereof may be different from actual ones.

(6) 1. Pellicle Frame and Pellicle

(7) The pellicle frame of the present invention is a pellicle frame characterized by being made of an AlCa alloy, and by stretching and affixing a pellicle film on one end surface of the pellicle frame via an adhesive for pellicle film, it is possible to use as a pellicle frame for lithography.

(8) A schematic sectional view of one example of the pellicle of the present invention constituted by using the pellicle frame of the present invention and a schematic plan view of the pellicle frame of the present invention are shown in FIG. 1 and FIG. 2, respectively. The pellicle 1 is obtained by stretching and affixing a pellicle film 6 on the upper end surface of a pellicle frame 2 via an adhesive layer 4 for affixing the pellicle film. When using the pellicle 1, a pressure sensitive adhesive layer 10 for adhering the pellicle 1 to the exposure master plate (mask or reticle) 8 is formed on the lower end surface of the pellicle frame 2, and a liner (not shown) is peelably adhered to the lower end surface of the pressure sensitive adhesive layer 10.

(9) It is preferable that the pellicle frame 2 is made of an AlCa alloy, and the AlCa alloy is processed as a hot extruded material or a hot rolled material, or manufactured by a die casting method. By using these methods, it is possible to efficiently obtain an AlCa alloy having both the low Young's modulus and the mechanical strength required for the pellicle frame. The process steps of the hot extrusion, hot rolling, and die casting are not particularly limited as long as the effects of the present invention are not impaired, and various conventionally known methods can be used. Furthermore, by achieving the cold rolling after the hot extrusion, the mechanical strength can also be increased.

(10) A powder sintered material can also be used for the above AlCa alloy. In order to improve the flatness of the exposure master plate (mask or reticle) 8 after adhering the pellicle 1, the pellicle frame 2 having a low Young's modulus is required. Comparing with general aluminum alloys, the AlCa alloy has a low Young's modulus, and in addition thereto, a Young's modulus thereof can be set to a lower value by using the powder sintered material having voids.

(11) The AlCa alloy is not particularly limited as long as the effects of the present invention are not impaired, and various conventionally known AlCa alloys can be used, but, according to the crystal structure, shape control, and the like of the Al.sub.4Ca crystal, it is preferable to use an AlCa alloy that achieves both the low Young's modulus and the excellent rolling processability.

(12) Since the powder sintered material has proper voids in the material, by controlling the ratio, size, dispersion state, and the like of the voids, it is possible to balance both the mechanical strength required for the pellicle frame 2 and the low Young's modulus. Examples of the materials having a low Young's modulus include magnesium, synthetic resins, and the like, but from the viewpoints of material availability and versatility, it is preferable to use an AlCa alloy which is an aluminum alloy.

(13) As described above, the distortion of the exposure master plate (mask or reticle) 8 by affixing the pellicle 1 to the exposure master plate (mask or reticle) 8 is greatly affected by the distortion of the pellicle frame 2. At the time of the affixing, the pellicle frame 2 is deformed, and the exposure master plate (mask or reticle) 8 is deformed by the deformation stress that tries to back to the original shape. Since the deformation stress depends on the Young's modulus of the material constituting the pellicle frame 2 and the deformation amount thereof, by using an AlCa alloy having a low Young's modulus (in particular, the powder sintered material), it is possible to realize the pellicle frame 2 having a small deformation stress when affixes the pellicle 1 to the exposure master plate (mask or reticle) 8.

(14) As the material of the pellicle frame 2, it is preferable to use a material which is obtained by processing the powder sintered body of the AlCa alloy as a hot extruded material. When achieving the hot processing such as hot forging or hot extrusion of the AlCa alloy powder material, though defects such as blister may be generated in some cases, by hot-extruding the AlCa alloy powder sintered body, it is possible to obtain a material in which occurrence of the defect is inhibited.

(15) The method for preparing the hot extruded AlCa alloy powder material used as the material of the pellicle frame 2 is not particularly limited, but it is preferably prepared by molding a raw material powder through a CIP method or the like (for example, AlCa alloy powder prepared by a quenched solidification method such as an atomizing method, a mechanical alloying method, or the like), heating and sintering the AlCa alloy powder molded body in vacuum or in an inert gas atmosphere, cooling the sintered body in vacuum or in an inert gas atmosphere, and hot-extruding the obtained sintered body. Here, the porosity of the hot extruded AlCa alloy powder material can be appropriately controlled depending on the compacting condition, the sintering condition, the extrusion condition, the oxidation state of the surface of the raw powder material, and the like.

(16) Further, in the material of the pellicle frame 2, it is preferable that the Ca content of the AlCa alloy is 5 to 10% by mass. When the Ca content is greater than or equal to 5% by mass, an Al.sub.4Ca phase is properly formed, and the Young's modulus can be effectively reduced. In addition, when the Ca content is smaller than or equal to 10% by mass, the amount of Al.sub.4Ca phase does not become too large, and it is possible to inhibit that the material becomes brittle, which results in giving the sufficient strength.

(17) In order to form a uniform anodized film, an etching treatment using an acid or an alkali may be achieved as a pretreatment, and in order to facilitate detection when dust or the like adheres to the obtained frame body, a blast treatment or the like may be applied. On the other hand, in order to increase the degree of cleaning, cleaning treatment such as pure water cleaning, hot water cleaning, ultrasonic cleaning or the like may be achieved after the anodizing treatment, the coloring treatment and the sealing treatment.

(18) The shape of the pellicle frame 2 is not particularly limited as long as the effects of the present invention are not impaired and can be various conventionally known shapes according to the shape of the exposure master plate (mask or reticle) 8, but, in general, the plane shape of the pellicle frame 2 is a ring shape, a rectangular shape or a square shape and has a size and shape to cover the circuit pattern portion provided on the exposure master plate (mask or reticle) 8. In addition, the pellicle frame 2 may be provided with an air pressure adjustment vent (not shown), a dust removal filter (not shown) for the vent, jig holes (not shown), and the like.

(19) The height (thickness) of the pellicle frame 2 is preferably 1 to 10 mm, more preferably 2 to 7 mm, and most preferably 3 to 6 mm. By setting the height (thickness) of the pellicle frame 2 to these values, the deformation of the pellicle frame 2 can be inhibited, and good handling property can be ensured.

(20) The cross-sectional shape of the pellicle frame 2 is not particularly limited as long as the effects of the present invention are not impaired and can be various conventionally known shapes, but it is preferable that the cross-sectional shape is a quadrilateral in which the upper side and the lower side are parallel. There are required a width for affixing the pellicle film 6 is required on the upper side of the pellicle frame 2, and a width for adhering to the exposure master plate 8 by providing the adhesive layer 10 for pressure sensitive adhesion on the lower side. For this reason, the width of the upper side and the lower side of the pellicle frame 2 is preferably about 1 to 3 mm.

(21) The flatness of the pellicle frame 2 is preferably smaller than or equal to 20 m, more preferably smaller than or equal to 10 m. By improving the flatness of the pellicle frame 2, it is possible to reduce the deformation amount of the pellicle frame 2 when the pellicle 1 is attached to the exposure master plate (mask or reticle) 8. The flatness of the pellicle frame 2 is calculated by calculating a virtual plane by measuring the height at a total of 8 points including 4 corners of the pellicle frame 2 and 4 central points of the four sides, and then calculating from the difference obtained by subtracting the lowest point from the highest point among the distances of each point.

(22) 2. Method for Manufacturing Pellicle Frame

(23) The method for manufacturing a pellicle frame of the present invention is a method for manufacturing a pellicle frame, comprising a first step for obtaining an aluminum alloy plastic worked (aluminum alloy to be plastic-worked) by subjecting an aluminum alloy ingot which contains 5.0 to 10.0% by mass of Ca with the remainder aluminum and inevitable impurities, and has a volume ratio of an Al.sub.4Ca phase which is a dispersed phase of 25% or more to a plastic working, a second step for subjecting the aluminum alloy plastic worked to a heat treatment in a temperature range of 100 to 300 C., and a third step for subjecting the heat-treated aluminum alloy plastic worked to an anodizing treatment with an alkaline electrolytic solution containing tartaric acid as an electrolyte.

(24) The Young's modulus of the AlCa alloy varies depending on the amount of the Al.sub.4Ca phase and the crystal structure. Therefore, even if the amount of the Al.sub.4Ca phase is the same, the crystal structure is changed by the plastic working in the first step, and the Young's modulus may be increased in some cases. On the other hand, by achieving a heat treatment (annealing treatment) in the temperature range of 100 to 300 C. after the plastic working, it is possible to return the crystal structure of the Al.sub.4Ca phase to the state before the plastic working and to lower the Young's modulus.

(25) Further, by setting the V content of the aluminum alloy ingot to 0.0001 to 0.005% by mass, it is possible to inhibit the formation of a compound of 30 m or more by reaction with V and Ca, Ti, Al, or the like. As a result, formation of the white spot defects after the anodizing treatment (third step) can be inhibited.

(26) Furthermore, by setting the Fe content to 0.05 to 1.0% by mass, it is possible to make the cast structure of the AlCa alloy coarse and uniform. As a result, the fine eutectic structure emphasized after the anodizing treatment (third step) can be blurred, and the formation of the black defects can be inhibited.

(27) Further, before the first step, it is preferable to subject the aluminum alloy ingot to a heat treatment at a temperature of higher than or equal to 400 C. By holding at a temperature of higher than or equal to 400 C. (homogenizing treatment) prior to plastic working, the eutectic structure can be made coarse and uniform. As a result, as described above, the fine eutectic structure can be blurred, and the formation of the black spot defects can be inhibited.

(28) In addition, it is possible to anodize the aluminum phase and the Al.sub.4Ca phase by applying the anodizing treatment (third step) with an alkaline electrolytic solution containing tartaric acid as an electrolyte to the heat-treated aluminum alloy plastic worked.

(29) Furthermore, by subjecting the dyeing treatment with a black dye after the anodizing treatment (third step), the L* value of the pellicle frame can be reduced to smaller than or equal to 30. The preferable L* value is greater than or equal to 10 or more and smaller than or equal to 30.

(30) The representative embodiments of the present invention have been described above, but the present invention is not limited only to these embodiments, and various design changes are possible, and all such design changes are included in the technical scope of the present invention.

EXAMPLES

Example

(31) An aluminum alloy having the composition (% by mass) shown in Sample 1 of Table 1 was cast into an ingot of 8 inches (billet) by a DC casting method and homogenized at 550 C. for 4 hours, and then, plastic-worked at an extrusion temperature of 500 C. to obtain a plate having a width of 180 mma thickness of 8 mm.

(32) Thereafter, after cold rolling to a thickness of 3.5 mm, a heat treatment was carried out to hold at 200 C. for 4 hours to obtain a present aluminum alloy plastic worked. This was machined to produce an aluminum alloy frame in the shape of frame having an external size of 149 mm122 mma thickness 3 mm. After subjecting the obtained aluminum alloy frame material to a shot blasting treatment by using stainless steel grains having an average grain size of about 100 m, the blast-treated aluminum alloy frame material was subjected to the anodizing treatment by using an alkaline aqueous solution (pH=13.0) as an electrolytic solution in which 53 g/L of sodium tartrate dihydrate (Na.sub.2C.sub.4H.sub.4Os.sub.2H.sub.2O) and 4 g/L of sodium hydroxide were dissolved, at a bath temperature of 5 C. under a constant voltage electrolysis of an electrolytic voltage of 40 V for 20 minutes. Then, after washing with pure water, by measuring a thickness if the anodized film formed on the surface of the aluminum alloy frame material with an eddy current type film thickness meter (available from Fischer Instruments Co., Ltd.), the thickness was 6.6 m.

(33) Subsequently, a dyeing treatment was achieved by placing the aluminum alloy frame material which was subjected to the anodizing treatment in an aqueous solution containing an organic dye (TAC 411 available from Okuno Pharmaceutical Co., Ltd.) at a concentration of 10 g/L for 10 minutes at a temperature of 55 C. After the dyeing treatment, the dye-treated aluminum alloy frame material was placed in a steam sealing apparatus and was subjected to a sealing treatment for 30 minutes while generating steam at a relative humidity of 100% (R.H.), 2.0 kg/cm.sup.2G at a temperature of 130 C. to obtain a test pellicle frame according to the example.

(34) FIG. 3 shows the X-ray diffraction pattern of the present aluminum alloy plastic worked. In the X-ray diffraction measurement, a specimen of 20 mm20 mm was cut out from the plate-like present aluminum alloy plastic worked, the surface layer portion was scraped by about 500 m, and then a -2 measurement was carried out with respect to the region by a Cu-K beam source. From the peak position of the Al.sub.4Ca phase in FIG. 3, it can be seen that the tetragonal Al.sub.4Ca phase and the monoclinic Al.sub.4Ca phase are mixed in the present aluminum alloy plastic worked.

(35) The result of the structure observation (optical microscopic photograph) on the cross section of the present pellicle frame is shown in FIG. 4. The black region was the Al.sub.4Ca phase, and the area (volume) ratio of the Al.sub.4Ca phase was measured by an image analysis and was 36.8%.

(36) The present pellicle frame of the example was cut into a test piece, and a tensile strength was measured by a tensile test, and, a yield strength and a Young's modulus were measured. The obtained results are shown in Table 2. In addition, the present pellicle frame was cut and aligned to form a 3030 mm surface, and the lightness index L* value was measured using a CR-400 available from KONICA MINOLTA CORPORATION using a Hunter's color difference formula of the present pellicle frame. The results are shown in Table 2.

Comparative Example 1

(37) A comparative pellicle frame 1 having an anodized film having a film thickness of 7.1 m was prepared in the same manner as in Example 1 except that the composition (% by mass) shown in Sample 2 in Table 1 was used. A tensile strength, a yield strength, a Young's modulus and an L* value of the comparative pellicle frame 1 were measured in the same manner as in the above example. The obtained results are shown in Table 2.

(38) Further, in the same manner as in the above example, the structure observation on the cross section of the comparative pellicle frame 1 was carried out, and an area (volume) rate of the Al.sub.4Ca phase was measured by an image analysis and found to be 15.9%.

Comparative Example 2

(39) A comparative pellicle frame 2 having an anodized film with a film thickness of 6.6 m was prepared by anodizing in the same manner as in the above example except that 8 g/L of sodium hydroxide was used as an electrolytic solution for anodizing treatment, and steam sealing was conducted after the anodizing without the dyeing treatment. A tensile strength, a yield strength, a Young's modulus and an L* value of the comparative pellicle frame 1 were measured in the same manner as in the above example. The obtained results are shown in Table 2.

(40) TABLE-US-00001 TABLE 1 Ca V Fe Al Sample 1 7.44 0.001 0.05 Bal. Sample 2 2.53 0.001 0.06 Bal.

(41) TABLE-US-00002 TABLE 2 Tensile Yield Young's strength strength modulus (MPa) (MPa) (GPa) L* value Example 224 171 50.2 28.4 Com. Example 1 185 161 62.5 27.6 Com. Example 2 224 171 50.2 40.6

(42) The Young's modulus of the pellicle frame produced from the 7.44% by mass Ca alloy in the example is 50.2 GPa, which is much smaller than that of the Comparative example 1 (62.5 GPa). Here, the Young's modulus of Comparative Example 2 which is not dyed also shows a small value of 50.2 GPa, but the L* value is as large as 40.6.

EXPLANATION OF SYMBOLS

(43) 1: Pellicle 2: Pellicle frame 4: Adhesive layer for affixing the pellicle film 6: Pellicle film 8: Exposure master plate (mask or reticle) 10: Pressure sensitive adhesion layer