Pellicle for EUV lithography

Abstract

To provide a pellicle for use in EUV lithography, capable of reliably preventing the deformation of a frame and the wrinkling of the pellicle film.SOLUTION: A pellicle for use in EUV lithography has: a frame having an opening; and a pellicle film that is supported at one end side of the frame in a stretched manner so as to cover the opening. The pellicle film contains carbon material. The frame is composed of a material having a melting temperature of 500°C or higher and a 0.2% proof stress at 300°C of 300 MPa or more.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a pellicle for EUV lithography. [Background technology]

[0002] In the manufacturing process of semiconductor devices such as large-scale integrated circuits (LSIs) and ultra-LSIs, as well as liquid crystal display panels, patterning is performed by irradiating light onto a photosensitive layer through a mask (also called an exposure master or reticle). If foreign matter adheres to the mask, the light is absorbed by the foreign matter or is reflected and bent by the surface of the foreign matter. This can result in deformation of the formed pattern or rough edges, compromising the dimensions, quality, and appearance of the patterned product. To address these issues, a method has been adopted in which a pellicle with a light-transmitting pellicle film is attached to the surface of the mask to prevent foreign matter from adhering.

[0003] The wavelength of light used in lithography is becoming shorter, and the use of EUV (Extreme Ultra Violet) light is being considered for next-generation lithography technology. EUV light refers to light with a wavelength in the soft X-ray or vacuum ultraviolet region, specifically, light rays with a wavelength of approximately 13.5 nm ± 0.3 nm.

[0004] EUV light is easily absorbed by all materials. If the pellicle film absorbs EUV light, it not only causes exposure defects but can also be damaged by heat generated by the energy of the EUV light.

[0005] For example, during EUV exposure, the pellicle film absorbs light, causing its temperature to rise to over 500°C. This heat is then transferred to the frame, causing it to deform. Another issue is that the difference in linear expansion coefficient between the frame material and the pellicle film material can cause the pellicle film to wrinkle during exposure.

[0006] For this reason, conventional pellicle films for ArF light, for example, are thought to be unsuitable for EUV light, and pellicles for EUV light have been proposed.

[0007] For example, Patent Document 1 discloses a pellicle that suppresses wrinkling and damage to the pellicle membrane by using a metal or alloy with a low linear expansion coefficient and density as the frame. Patent Document 2 also discloses a pellicle frame made of a material with a low linear expansion coefficient. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 2019-70745 [Patent Document 2] Patent No. 6370255 Summary of the Invention [Problem to be solved by the invention]

[0009] However, the technology disclosed in the above document does not adequately suppress frame deformation or pellicle film wrinkles. Furthermore, because EUV light has a short wavelength, it is easily affected by pellicle film distortion. Therefore, if the mask distortion that can occur when attaching a pellicle to a mask is large, it may affect the pattern. Therefore, there is a demand for small mask distortion.

[0010] The present invention has been proposed in consideration of the above-described conventional situation, and an object of the present invention is to provide a pellicle that can more reliably suppress frame deformation and wrinkles in the pellicle film in EUV lithography, and further, that reduces mask distortion that can occur when the pellicle is attached to a mask. [Means for solving the problem]

[0011] [1] A pellicle for use in EUV lithography, comprising: a frame having an opening; and a pellicle membrane stretched and supported on one end face side of the frame so as to cover the opening, the pellicle membrane comprises a carbon material; A pellicle wherein the frame is made of a material having a melting temperature of 500°C or higher and a 0.2% yield strength at 300°C of 300 MPa or higher. [2] The pellicle according to [1], wherein the Young's modulus of the material constituting the frame is less than 110 GPa. [3] The pellicle according to [1] or [2], wherein the Young's modulus of the material constituting the frame is 100 GPa or less. [4] The pellicle according to any one of [1] to [3], wherein the material constituting the frame includes a β-type titanium alloy. [5] The pellicle according to any one of [1] to [4], wherein the material constituting the frame contains 13 to 40 mass % of vanadium (V). [6] The pellicle according to any one of [1] to [5], wherein the material constituting the frame contains 13 to 40 mass % of molybdenum (Mo). [7] The pellicle according to any one of [1] to [6], wherein the material constituting the frame contains 13 to 40 mass % of niobium (Nb). [8] The pellicle according to any one of [1] to [7], wherein the material constituting the frame contains 14 to 25 mass% vanadium (V), 2.5 to 5 mass% aluminum (Al), 0.5 to 4 mass% tin (Sn), and 4 mass% or less chromium (Cr), with the remainder containing at least one of titanium (Ti) and impurities. [9] The pellicle according to any one of [1] to [8], wherein the material constituting the frame contains oxygen (O): more than 0% by mass and 0.20% by mass or less.

[10] The pellicle according to any one of [1] to [9], wherein the material constituting the frame contains more than 0% by mass and 0.10% by mass or less of carbon (C).

[11] The pellicle according to any one of [1] to

[10] , wherein the carbon material of the pellicle film includes at least one selected from the group consisting of carbon, graphene, carbon nanotubes, and graphite.

[12] The pellicle according to any one of [1] to

[11] , wherein the thickness of the pellicle film is greater than 0 and less than 1500 nm.

[13] The pellicle according to any one of [1] to

[12] , wherein the frame has a rectangular shape consisting of a pair of long sides and a pair of short sides when viewed from the front, the long side length being 80 mm to 300 mm, and the short side length being 50 mm to 250 mm. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a pellicle that can more reliably prevent frame deformation and wrinkles in the pellicle film in EUV lithography. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a diagram showing an example of a configuration of a pellicle. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, a description will be given of an embodiment of the present invention (hereinafter abbreviated as "embodiment") with reference to the drawings. The present invention is not limited to the following embodiment, and various modifications can be made within the scope of the gist of the present invention. In this specification, numerical ranges expressed using "to" include the preceding and following numerical values.

[0015] An overview of the pellicle according to this embodiment will be described below. Fig. 1(a) is a top view showing a pellicle 1, and Fig. 1(b) is a longitudinal cross-sectional view. In the following description, the upper side of each figure will be referred to as "top" and the lower side as "bottom."

[0016] In this specification, EUV light refers to light with a wavelength of 5 nm or more and 30 nm or less. The wavelength of EUV light is preferably 5 nm or more and 14 nm or less, and specifically, EUV light refers to light with a wavelength of about 13.5 nm±0.3 nm.

[0017] [Pellicle] The pellicle 1 is a structure that protects a photomask from dust in photolithography, etc. The pellicle 1 includes a frame 2, a pellicle film 3, an adhesive layer 4, and a release film 5.

[0018] <frame> The frame 2 (frame body) can have any shape that allows the pellicle membrane 3 to be stretched over the frame 2. For example, the frame 2 can have an outer shape such as a rectangle, a square, a rectangle, or an ellipse when viewed from the front. The rectangle can be a square, a rectangle, or the like, and can have both right-angled corners and a roughly rectangular shape with rounded corners (FIG. 1). The polygon can be a triangle, a trapezoid, a parallelogram, a pentagon, a hexagon, or the like.

[0019] The size of the frame 2 and its opening can be determined according to the size of the photomask. When the frame 2 has a rectangular shape consisting of a pair of long sides and a pair of short sides in a front view, the long side length can be 80 mm to 300 mm, the short side length can be 50 mm to 250 mm, the widths of the long sides and the short sides can each be 1.0 mm to 10.0 mm, and / or the height of the frame can be 1.0 mm to 8.0 mm.

[0020] As shown in Fig. 1, the frame 2 has edges. The edges can have rod-shaped edge members that extend linearly. A pair of edge members can be arranged parallel to each other with a gap between them, and similarly, another pair of edge members can be arranged parallel to each other with a gap between them. The ends of two contacting edge members can be connected so that they form approximately a right angle with each other.

[0021] In pellicle 1 of the present invention, frame 2 is made of a material having a melting temperature of 500°C or higher and a 0.2% yield strength at 300°C of 300 MPa or higher.

[0022] Here, "0.2% yield strength" refers to the magnitude of the load required to give a plastic (permanent) strain of 0.2%, and means that even after applying and unloading a load of this magnitude, there is still 0.2% deformation.

[0023] The 0.2% yield strength of each material was determined by preparing No. 13 test pieces as specified in JIS Z2201, conducting tensile tests in accordance with JIS Z2241, and measuring the 0.2% yield strength in the rolling direction of the test pieces. The test pieces were taken so that their longitudinal direction (L direction) coincided with the rolling direction. The test speed (strain rate in the tensile test) was 0.3 mm / min, and the test temperature was 300°C.

[0024] If the material constituting frame 2 has a 0.2% yield strength of 300 MPa or more at 300°C, frame 2 is less susceptible to plastic deformation, ensuring the structural stability of frame 2 and ultimately pellicle 1. The 0.2% yield strength is preferably 500 MPa or more, and more preferably 600 MPa or more.

[0025] Furthermore, by making the material constituting the frame 2 have a melting temperature of 500°C or higher, it is possible to prevent thermal deformation of the frame 2 even if the pellicle film 3 absorbs light during EUV exposure, causing the temperature of the pellicle film 3 to rise to 500°C or higher and transmitting that heat to the frame 2. The melting temperature is preferably 1000°C or higher, and more preferably 1400°C or higher.

[0026] In this specification, the "melting temperature" is a value estimated from the melting point of the material, or in the case of an alloy, the melting point of each constituent metal.

[0027] In the pellicle 1 of this embodiment, the Young's modulus of the material constituting the frame 2 is preferably less than 110 GPa, more preferably 100 GPa or less, and even more preferably 85 GPa or less. When the Young's modulus of the material constituting the frame 2 is less than 110 GPa, mask distortion when attached to the mask can be suppressed.

[0028] In this specification, the "Young's modulus" may be a conventionally known value (for example, a value listed in a catalog).

[0029] In the pellicle 1 of this embodiment, the coefficient of linear thermal expansion of the material constituting the frame 2 is 10.0 (×10 -6 / K) or less, and 9.0 (×10 -6 / K) or less. -6 / K) or less, deformation due to temperature rise is small, and occurrence of wrinkles and peeling of the pellicle film 3 due to expansion and contraction of the frame 2 can be suppressed.

[0030] In this specification, the "coefficient of linear thermal expansion" may be a conventionally known value (for example, a value listed in a catalog).

[0031] The material constituting the frame 2 is not particularly limited as long as it satisfies the physical properties described above, but a material containing at least one of titanium and a titanium alloy is preferable. Among these, a material containing a β-type titanium alloy is preferable. β-type titanium alloys have excellent corrosion resistance and are easy to process. Furthermore, they can be strengthened by heat treatment or thermomechanical treatment. Furthermore, depending on the composition, they can be strengthened while suppressing an increase in Young's modulus. Therefore, distortion of the mask when attached to the mask can be suppressed, which is preferable. Since distortion of the frame can affect distortion of the mask, a low Young's modulus is preferable. Among β-type titanium alloys, Ti-15V-3Cr-3Sn-3Al, Ti-Nb-based compounds, Ti-Mo-based compounds, or Ti-22V-4Al are preferable.

[0032] The β-type titanium alloy preferably contains at least one element selected from the group consisting of vanadium (V), molybdenum (Mo), niobium (Nb), etc., which have a high solid solubility in the β-phase, which makes it easier to suppress decomposition due to eutectoid transformation and embrittlement due to ω-phase precipitation.

[0033] When the material constituting the frame 2 contains vanadium (V), for example, when the material constituting the frame 2 contains a Ti-V-based β-type titanium alloy, it is preferable that the material contain 13 to 40 mass % V for the same reasons as above. Furthermore, when the material constituting the frame 2 contains molybdenum (Mo), for example, when the material constituting the frame 2 contains a Ti-Mo-based β-type titanium alloy, it is preferable for the material to contain 13 to 40 mass % Mo for the same reasons as above. Furthermore, when the material constituting the frame 2 contains niobium (Nb), for example, when the material constituting the frame 2 contains a Ti-Nb-based β-type titanium alloy, it is preferable for the material to contain 13 to 40 mass % Nb for the same reasons as above.

[0034] A particularly preferred material for forming the frame 2 is a β-type titanium alloy (Ti-V-Cr-Sn-Al) containing 14 to 25 mass% V, 2.5 to 5 mass% Al, 0.5 to 4 mass% Sn, and 4 mass% or less Cr, with the remainder containing at least one of Ti and impurities.

[0035] The Sn content is 0.5 to 4 mass %. By setting the Sn content within this range, the passive film made of titanium oxide becomes more difficult to dissolve, which has the effect of improving corrosion resistance.

[0036] The Cr content is 4 mass % or less. By setting the Cr content within this range, the grain size is made finer, which contributes to improving toughness.

[0037] A specific example of such a titanium alloy is Ti-15V-3Cr-3Sn-3Al (melting temperature: 1668°C, 0.2% yield strength at 300°C: 900 MPa, Young's modulus: 78 GPa). Note that "Ti-15V-3Cr-3Sn-3Al" indicates that the alloy contains 15% by mass of V, 3% by mass of Cr, 3% by mass of Sn, and 3% by mass of Al, with the remainder being Ti and impurities.

[0038] In the titanium alloy according to this embodiment, the remainder (the remainder) includes titanium (Ti) and impurities. In this embodiment, "impurities" refer to components that are introduced during industrial production of titanium alloys due to various factors in the manufacturing process, including raw materials such as titanium sponge and scrap, and also includes unavoidable components. Examples of such unavoidable impurities include oxygen, hydrogen, carbon, and nitrogen. The content of these elements may be limited to the extent that the objectives of the present invention are achieved. The allowable oxygen (O) content is 0.20% by mass or less, the allowable hydrogen (H) content is 0.100% by mass or less, the allowable carbon (C) content is 0.10% by mass or less, and the allowable nitrogen (N) content is 0.1% by mass or less. The lower the content of these elements, the better. While there is no lower limit specified for their content, it is difficult to achieve a content of zero for these elements.

[0039] The frame 2 may be provided with ventilation holes. By providing the ventilation holes, the difference in air pressure between the inside and outside of the closed space formed by the pellicle 1 and the photomask can be eliminated, and swelling or denting of the pellicle film 3 can be prevented. It is also preferable to attach a dust filter to the ventilation holes. In this way, it is possible to prevent foreign matter from entering the closed space formed by the pellicle 1 and the photomask from the outside through the ventilation holes.

[0040] If necessary, an adhesive (e.g., acrylic, vinyl acetate, silicone, rubber-based adhesive, etc.) or grease (e.g., silicone-based, fluorine-based grease, etc.) may be applied to the inner surface or entire surface of the frame 2 to capture foreign matter. Additionally, the frame 2 may be provided with a jig hole or the like for attaching the pellicle 1 to a photomask, if necessary.

[0041] <Pellicle membrane> The pellicle film 3 is a thin film containing a carbon material. The pellicle film 3 has a thickness of 2 μm or less and is formed so as to sufficiently transmit light emitted from a light source in photolithography.

[0042] The pellicle film 3 is preferably a carbon film containing a carbon structure obtained by heating carbon or a compound containing carbon atoms. The carbon film is preferably at least one selected from the group consisting of carbon, graphene, carbon nanotubes (CNT), and graphite. In particular, a carbon nanotube film is preferable from the viewpoints of heat resistance and transmittance. Furthermore, a reinforcing material may be present from the viewpoints of handling and light resistance. Examples of the reinforcing material include SiC and SiN-based compounds, and metals such as Mo, Ru, and Rh.

[0043] The carbon film is produced by, for example, including a step (step I) of depositing a film containing carbon atoms on a substrate, a step (step II) of heating the film deposited on the substrate at 800 to 1400°C in a nitrogen atmosphere to form a carbon film, and a step (step III) of peeling the carbon film from the substrate.

[0044] In (Step I), the compound containing carbon atoms is not particularly limited as long as it is carbonized by heating, and is preferably an organic material.

[0045] The compound containing carbon atoms is more preferably at least one selected from the group consisting of polyimide compounds, polybenzoxazine compounds, polyacrylonitrile compounds, polyisocyanate compounds, polyamide compounds, heteroaromatic ring compounds, polyphenylene resins, polyether resins, liquid crystal polymer resins, polyparaxylylene resins, phenolic resins, epoxy resins, and furan resins. The compound containing carbon atoms is more preferably at least one selected from the group consisting of polyimide compounds and polybenzoxazine compounds.

[0046] The substrate is not particularly limited as long as it has a melting point higher than 800 to 1400°C, which is the heating temperature when forming the carbon film, and for example, a silicon substrate (hereinafter also referred to as Si substrate) whose surface layer contains silicon dioxide (SiO2) is preferred. By producing a carbon film on a Si substrate, a carbon film with excellent in-plane film thickness uniformity can be produced without film breakage.

[0047] Known techniques can be applied to form carbon or a compound containing carbon atoms into a film, and arc plasma deposition (APD) is a preferred method for forming carbon into a film on a substrate, while spin coating is a preferred method for forming a compound containing carbon atoms into a film on a substrate. These methods make it possible to produce a carbon film with excellent in-plane film thickness uniformity.

[0048] In (Step II), the heating temperature is 800 to 1400° C., preferably 900 to 1300° C., and more preferably 1000 to 1200° C. Heating can be carried out using a heat treatment furnace or the like.

[0049] The heating time is preferably 1 minute to 10 hours, more preferably 10 minutes to 3 hours, and even more preferably 30 minutes to 2 hours, from the viewpoint of sufficiently converting carbon atoms into a turbostratic carbon structure.

[0050] In (Step III), the specific method for the step of peeling the carbon film from the substrate is not particularly limited, and examples thereof include a method including: a step of spin-coating a composition containing an acrylic resin or the like onto the carbon film obtained by heating to form a support film; a step of peeling the substrate by a hydrofluoric acid treatment or the like; a step of attaching a support frame to the peripheral edge of the carbon film of the structure consisting of the carbon film and the support film; and a step of removing the support film by an etching treatment or the like.

[0051] The thickness of the carbon film constituting the pellicle film 3 is preferably less than 1500 nm. The thickness of the carbon film is the thickness of the film as used in the ordinary sense. The upper limit of the thickness of the carbon film is more preferably 1200 nm or less, even more preferably 1000 nm or less, still more preferably 500 nm or less, and even more preferably 300 nm or less. By making the thickness of the carbon film less than 1500 nm, it is possible to obtain a carbon film that does not develop cracks during production. The lower limit of the thickness of the carbon film is not particularly limited as long as it is greater than 0 nm.

[0052] The thickness of the carbon film can be controlled, for example, by adjusting the thickness of a film containing carbon atoms when the film is laminated on a substrate in a method for producing a pellicle film.

[0053] As shown in FIG. 1( b ), the pellicle film 3 is adhered and fixed to one end of the frame 2 with an adhesive (not shown), and covers the frame 2 .

[0054] <Adhesive layer> As shown in FIG. 1(b), an adhesive layer 4 for attaching the pellicle 1 to the photomask is disposed on the other end side of the frame 2 (the side of the frame 2 opposite to the pellicle film 3).

[0055] The adhesive layer 4 is composed of an adhesive such as an acrylic, rubber, vinyl, epoxy, or silicone adhesive, and more preferably an acrylic or silicone adhesive. The thickness of the adhesive layer 4 is preferably, for example, 0.2 mm to 2.5 mm. Furthermore, when the pellicle is attached to the mask using a jig or the like, an adhesive may not be necessary.

[0056] <Release film> A release film 5 (liner) is disposed so as to cover the adhesive layer 4. This release film 5 protects the adhesive layer 4 when not in use, and is peeled off from the adhesive layer 4 when the pellicle 1 is in use.

[0057] A film of polyester or the like having a thickness of about 30 to 200 μm is generally used for the release film 5. If the peeling force required to peel the release film 5 from the adhesive layer 4 is too great, the adhesive layer 4 may be deformed during peeling. Therefore, the surface of the film that comes into contact with the adhesive may be subjected to a release treatment such as silicone or fluorine to achieve an appropriate peeling force.

[0058] In the pellicle 1 of this embodiment having such a configuration, the frame 2 is made of a material that has a high melting temperature and sufficient rigidity and strength, so it is less likely to deform or break even at high temperatures, has excellent structural stability, and is suitable as a pellicle for EUV lithography. That is, with the pellicle 1 of this embodiment, it is possible to more reliably prevent deformation of the frame 2 and wrinkles in the pellicle film 3 during EUV lithography.

[0059] Although the embodiment of the present invention has been described above, the present invention is not limited to this and can be modified as appropriate within the scope of the invention. [Example]

[0060] The present invention will now be described in more detail with reference to examples and comparative examples. However, the present invention is not limited to the following examples as long as it does not deviate from the gist of the present invention.

[0061] [Fabrication of pellicle] Example 1 (1) Preparation of adhesive frame A frame made of β-type Ti alloy (Ti-15V-3Cr-3Sn-3Al) with an outer diameter of 149mm x 115mm x 1.5mm height and 3.5mm width was prepared, and an acrylic adhesive was applied to its lower end surface to create an adhesive-coated frame.

[0062] (2) Preparation of carbon film A 15 wt% solution of a polyimide precursor (BPDA-ODA) synthesized from 3,3',4,4'-biphenyltetracarboxylic dianhydride (BDPA) and 4,4'-diaminodiphenyl ether (ODA) in N-methylpyrrolidone was spin-coated onto a Si substrate and imidized at 300°C for 1 hour under a nitrogen atmosphere to form a 400 nm thick polyimide film.

[0063] Subsequently, the substrate was placed in a heat treatment furnace and heated at 1100° C. for 1 hour under an N 2 flow to carbonize it, thereby obtaining a carbon film with a thickness of 200 nm.

[0064] The substrate was then spin-coated at 500 rpm with a 15 wt% solution of polymethyl methacrylate (PMMA) in acetone to form a support film. The substrate was then immersed in a 40 wt% aqueous solution of hydrogen fluoride, and the PMMA-coated carbon film was peeled off from the substrate and washed with water. The PMMA-coated carbon film was then immersed in a 1:1 (weight ratio) acetone:isopropyl alcohol solvent to dissolve the PMMA. The carbon film was then transferred to the isopropyl alcohol solution using a glass substrate. The carbon film was then removed and dried to obtain a carbon film.

[0065] The obtained carbon film was attached to the upper end surface of the adhesive-attached frame via an adhesive to form the pellicle of Example 1.

[0066] <Example 2> A pellicle was fabricated in the same manner as in Example 1, except that a frame made of a Ti alloy (Ti-20Nb-5Cr-4Zr), a β-type titanium alloy, was used instead of a Ti alloy (Ti-15V-3Cr-3Sn-3Al). Example 3 A pellicle was fabricated in the same manner as in Example 1, except that a frame made of a Ti alloy (Ti-22V-4Al), a β-type titanium alloy, was used instead of a Ti alloy (Ti-15V-3Cr-3Sn-3Al). Example 4 A pellicle was fabricated in the same manner as in Example 1, except that a frame made of a Ti alloy (Ti-36Nb-2Ta-3Zr-O), a β-type titanium alloy, was used instead of a Ti alloy (Ti-15V-3Cr-3Sn-3Al).

[0067] <Example 5> A pellicle was fabricated in the same manner as in Example 1, except that a frame made of a Ti alloy (Ti-6Al-4V) was used instead of a Ti alloy (Ti-15V-3Cr-3Sn-3Al). <Comparative Example 1> A pellicle was fabricated in the same manner as in Example 1, except that a frame made of invar (Fe—Ni36) was used instead of a Ti alloy (Ti-15V-3Cr-3Sn-3Al).

[0068] <Comparative Example 2> A pellicle was produced in the same manner as in Example 1, except that a frame made of an Al alloy (7075) was used instead of the Ti alloy (Ti-15V-3Cr-3Sn-3Al).

[0069] [Evaluation of frame properties] The physical properties of the frame of the pellicle fabricated as described above were evaluated as follows.

[0070] <0.2% yield strength at 300℃> The 0.2% yield strength of each material was determined by preparing No. 13 test pieces as specified in JIS Z2201, conducting tensile tests in accordance with JIS Z2241 on these test pieces, and measuring the 0.2% yield strength in the rolling direction of the test piece at a test temperature of 300°C. The test pieces were taken so that their longitudinal direction (L direction) coincided with the rolling direction. The test speed (strain rate in the tensile test) was 0.3 mm / min.

[0071] [Evaluation of heat resistance of pellicle] The heat resistance of the produced pellicles was evaluated as follows.

[0072] <Frame transformation> The obtained pellicle was attached to a quartz substrate (6025) and left in an oven at 200° C. for 24 hours. After that, the state of the pellicle (deformation of the frame) was visually observed and evaluated as follows. ○: No deformation was observed in the frame. ×: Deformation was observed in the frame.

[0073] <Photomask deformation> The deformation of the photomask was evaluated by measurement using FlatMaster 200 manufactured by Tropel. The flatness of a photomask (6025 quartz) was measured before and after attaching a pellicle, and the flatness before and after attachment was subtracted to calculate the amount of deformation of the mask (6025 quartz) due to attaching the pellicle to the mask (measurement area: 135 mm x 110 mm), and the evaluation was as follows: The pellicle was attached to the quartz using a simple mounter (load: 5 kgf, 60 sec). ◯: The amount of deformation of the photomask due to the attachment of the pellicle was less than 40 nm. △: The amount of deformation of the photomask due to the attachment of the pellicle was 40 nm or more and less than 45 nm. ×: The deformation of the photomask due to the attachment of the pellicle was 45 nm or more.

[0074] The evaluation results for the physical properties of the frame and the heat resistance of the pellicle are summarized in Table 1.

[0075] [Table 1]

[0076] As is clear from Table 1, in the examples using materials with melting temperatures of 500°C or higher and 0.2% yield strength at 300°C of 300 MPa or higher, frame deformation was more reliably suppressed than in the comparative examples using materials that did not satisfy these conditions. In addition, distortion of the mask was also more effectively suppressed.

[0077] Although the embodiment of the present invention has been described above, the present invention is not limited to this and can be modified as appropriate within the scope of the invention. [Industrial Applicability]

[0078] By using the pellicle of the present invention, it is possible to more reliably prevent deformation of the frame and wrinkles in the pellicle film due to heat generated by absorbing EUV light, and the pellicle can be widely used as a pellicle for EUV lithography. [Explanation of symbols]

[0079] 1: Pellicle 2: Frame 3: Pellicle membrane 4: Adhesive layer 5: Release film

Claims

1. A pellicle for use in EUV lithography, comprising: a frame having an opening; and a pellicle membrane stretched and supported on one end face side of the frame so as to cover the opening, the pellicle membrane comprises a carbon material; A pellicle, wherein the frame is made of a material having a melting temperature of 500°C or higher and a 0.2% yield strength at 300°C of 300 MPa or higher.

2. The pellicle of claim 1 , wherein the Young's modulus of the material that makes up the frame is less than 110 GPa.

3. 3. The pellicle according to claim 1, wherein the Young's modulus of the material constituting the frame is 100 GPa or less.

4. The pellicle according to any one of claims 1 to 3, wherein the material constituting the frame includes a β-type titanium alloy.

5. The pellicle according to any one of claims 1 to 4, wherein the material constituting the frame contains 13 to 40 mass % of vanadium (V).

6. The pellicle according to any one of claims 1 to 5, wherein the material constituting the frame contains 13 to 40 mass % of molybdenum (Mo).

7. The pellicle according to any one of claims 1 to 6, wherein the material constituting the frame contains 13 to 40 mass % of niobium (Nb).

8. 8. The pellicle according to claim 1, wherein the material constituting the frame contains 14 to 25 mass% vanadium (V), 2.5 to 5 mass% aluminum (Al), 0.5 to 4 mass% tin (Sn), and 4 mass% or less chromium (Cr), with the remainder including at least one of titanium (Ti) and impurities.

9. The pellicle according to any one of claims 1 to 8, wherein the material constituting the frame contains oxygen (O): more than 0% and 0.20% by mass or less.

10. The pellicle according to any one of claims 1 to 9, wherein the material constituting the frame contains carbon (C): more than 0 and 0.10 mass% or less.

11. The pellicle according to any one of claims 1 to 10, wherein the carbon material of the pellicle film comprises at least one selected from the group consisting of carbon, graphene, carbon nanotubes, and graphite.

12. The pellicle according to any one of claims 1 to 11, wherein the thickness of the pellicle film is greater than 0 and less than 1500 nm.

13. The pellicle according to any one of claims 1 to 12, wherein the frame is rectangular in shape when viewed from the front, consisting of a pair of long sides and a pair of short sides, the long side length being 80 mm to 300 mm, and the short side length being 50 mm to 250 mm.

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