Pellicle for extreme ultraviolet lithography based on metal carbide nanotubes and method for manufacturing the same

Abstract

To provide a pellicle for extreme ultraviolet lithography based on metal carbide nanotubes having excellent optical properties and chemical durability, such as extreme ultraviolet transmittance required in extreme ultraviolet lithography environments, and a method for manufacturing the same.SOLUTION: The present invention provides a pellicle for extreme ultraviolet lithography that includes a frame having an opening formed in a central portion thereof, and a porous pellicle membrane supported by the frame, covering the opening, and formed in a mesh structure based on metal carbide nanotubes. A method for manufacturing the pellicle is also provided.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to extreme ultraviolet (EUV) lithography technology, and more particularly, to a porous pellicle for EUV lithography based on metal carbide nanotubes, which is installed on a photomask used in a lithography process using extreme ultraviolet rays, and a method for manufacturing the same.

Background Art

[0002] Extreme ultraviolet lithography technology using a wavelength of 13.5 nm or less is used in exposure and patterning processes for improving the integration degree of semiconductor elements and circuits. Continuous research and development have been conducted on core materials and process technologies for improving the performance and efficiency of the extreme ultraviolet lithography process.

[0003] A pellicle for extreme ultraviolet lithography is a component composed of a thin pellicle film for physically preventing contamination sources generated during the extreme ultraviolet lithography process from adhering to the photomask, a frame, and the like. The pellicle is considered an essential material for improving wafer yield and the productivity of the lithography process.

[0004] However, the conditions required for the pellicle film of the pellicle are a free-standing thin film with an extreme ultraviolet transmittance of 90% or more, a thickness of several tens of nm to achieve this, and a size of 110×144 mm. The pellicle film is an aggregation of advanced thin film technologies that require mechanical stability not to be damaged by a horizontal acceleration of 20 G inside an extreme ultraviolet exposure apparatus, a thermal load due to an extreme ultraviolet output of 250 W or more, and chemical stability to ensure a life level capable of exposing 10,000 wafers in a hydrogen radical environment. Due to such required conditions, extreme material technology and process technology are required for the production of the pellicle.

[0005] Currently, candidate substances proposed as materials for the core layer forming the pellicle film include graphene, graphite, BCN, Si-BN, MoSi2, SiC, ZrSi2, Mo2C, carbon nanotubes, etc., which are thermally and chemically stable. Substances proposed for the protective layer, buffer layer, heat dissipation layer, etc. formed on the core layer include SiN, Ru, etc.

[0006] In order for each of such substances to be commercialized for the pellicle film, it is known that technologies such as nanometer-level thickness realization technology, crystallization technology, thickness uniformity control technology, large-area synthesis technology, defect control technology, etc. must be further improved. The more a technology can realize a pellicle film with good characteristics through as simple a process as possible, the easier it is for mass production application, so the technical value is high.

[0007] Currently, in order to improve the transmittance of the pellicle for extreme ultraviolet lithography, a method of forming a large number of pinholes in the pellicle film is being studied. The pinhole formation process is an additional process that proceeds after synthesizing the core layer of the pellicle in a thin film form, and is a process of irregularly forming a large number of pinholes in the core layer. Since such a pinhole formation process proceeds in a high-cost process such as a lithography process using an electron beam, the cost-efficiency at the time of mass production introduction can be reduced. Therefore, there is a situation where a manufacturing method for creating a porous pellicle by an easier method and a material technology therefor are required.

[0008] In addition, a pellicle using a network structure of carbon nanotubes (CNT) for a porous pellicle film has been proposed and studied. In the case of such a CNT pellicle, although it does not have an extreme ultraviolet transmittance exceeding 90%, it has high mechanical strength, so it has been designated and studied as a promising material and structure leading the future market of pellicles for extreme ultraviolet lithography.

[0009] However, the CNT pellicle has the disadvantage that CNTs are easily etched in an extreme ultraviolet scanner environment. Therefore, it is necessary to further form a capping layer to protect the network structure of CNTs. Regarding CNT pellicles with a capping layer, various materials and processes have been studied, but no mass-producible materials and processes have been proposed yet.

Prior Art Documents

Patent Documents

[0010]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0011] Accordingly, an object of the present invention is to provide a pellicle for extreme ultraviolet lithography based on metal carbide nanotubes having good optical properties such as extreme ultraviolet transmittance and chemical durability required in an extreme ultraviolet lithography environment, and a method for manufacturing the same.

[0012] Another object of the present invention is to provide a pellicle for extreme ultraviolet lithography based on metal carbide nanotubes that can be manufactured by a simple manufacturing process, and a method for manufacturing the same.

Means for Solving the Problems

[0013] To achieve the above object, the present invention provides a method for manufacturing a porous pellicle film for extreme ultraviolet lithography, comprising: manufacturing a sacrificial template in a network structure based on nanowires; depositing a metal carbide precursor on the surface of the nanowires forming the sacrificial template; heat-treating the metal carbide precursor to form metal carbide; and selectively removing the nanowires forming the sacrificial template to manufacture a porous pellicle film with the remaining metal carbide.

[0014] In the step of manufacturing the porous pellicle film, the porous pellicle film is formed of metal carbide nanotubes such that the remaining metal carbide corresponds to the outer shape of the nanowires, and the metal carbide nanotubes can form a network structure.

[0015] The porous pellicle film may include metal carbide nanotubes having a collapsed form by heat treatment.

[0016] The nanowires are formed of a material that can be selectively removed with respect to the metal carbide precursor or the metal carbide.

[0017] The nanowires may include at least one of carbon nanotubes, semiconductor nanowires, conductor nanowires, and non-conductor nanowires.

[0018] In the step of deposition, the metal carbide precursor may include at least one of a metal, a metal oxide, a compound and a mixture of the metal or the metal oxide.

[0019] The metal may include at least one of molybdenum (Mo), niobium (Nb), zirconium (Zr), ruthenium (Ru), yttrium (Y), and aluminum (Al).

[0020] The metal oxide is molybdenum oxide (MoO x , 1 ≦ x ≦ 5), niobium oxide (NbO x, (1 ≤ x ≤ 3), zirconium oxide (ZrO x , (0.25 ≤ x ≤ 2), ruthenium oxide (RuO x , (2 ≤ x ≤ 4), yttrium oxide (YO x , (1 ≤ x ≤ 3) and aluminum oxide (Al x O y ) may include at least one of them.

[0021] In the step of depositing, the metal carbide precursor can be formed by atomic layer deposition (ALD) or chemical vapor deposition (CVD).

[0022] The step of depositing may include: forming a first metal carbide precursor on the surface of the nanowire by physical vapor deposition (PVD); and forming a second metal carbide precursor on the surface of the first metal carbide precursor by atomic layer deposition (ALD) or chemical vapor deposition (CVD).

[0023] In the step of forming the metal carbide, the metal carbide may include at least one of molybdenum carbide, niobium carbide, zirconium carbide, ruthenium carbide, yttrium carbide and aluminum carbide.

[0024] When the material of the metal carbide nanotube is molybdenum carbide, the thickness of the porous pellicle film is 20 nm or less and the extreme ultraviolet transmittance is 96% or more.

[0025] In the step of forming the metal carbide, it can be heat-treated at 500 - 1300 °C with a reaction gas containing carbon atoms.

[0026] The reaction gas can be a gas containing a hydrocarbon including at least one of methane, ethane and propane.

[0027] In the step of manufacturing the porous pellicle film, the nanowire can be selectively removed by plasma etching.

[0028] In the step of manufacturing the porous pellicle film, by-products generated in the process of forming the metal carbide precursor into metal carbide can be removed by the plasma etching.

[0029] The present invention also provides a method for manufacturing a porous pellicle film for extreme ultraviolet lithography, including: the step of manufacturing a sacrificial template with a network structure based on nanowires; the step of depositing a metal carbide precursor on the surface of the nanowires forming the sacrificial template; the step of selectively removing the nanowires forming the sacrificial template while leaving the metal carbide precursor; and the step of heat-treating the metal carbide precursor to form metal carbide and manufacturing a porous pellicle film with the metal carbide.

[0030] In the step of removal, the nanowires are removed, and the remaining metal carbide precursor is formed of metal carbide precursor nanotubes corresponding to the outer shape of the nanowires, and the metal carbide precursor nanotubes form a network structure.

[0031] In the step of manufacturing the porous pellicle film, the porous pellicle film is formed such that the metal carbide precursor nanotubes are formed into metal carbide nanotubes by heat treatment, and the metal carbide nanotubes form a network structure.

[0032] In the step of removal, the nanowires can be removed using at least one of plasma, ozone (O3), chlorine (Cl2), chloride, and fluoride.

[0033] The present invention also provides a pellicle for extreme ultraviolet lithography, including: a frame having an opening formed in a central portion; and a porous pellicle film supported by the frame to cover the opening and formed with a network structure based on metal carbide nanotubes.

Advantages of the Invention

[0034] According to the present invention, the porous pellicle film is formed with a porous structure based on metal carbide nanotubes, providing good optical properties such as extreme ultraviolet transmittance required in an extreme ultraviolet lithography environment and chemical durability.

[0035] The porous pellicle film according to the present invention can be easily manufactured into a porous pellicle film with a porous structure based on metal carbide nanotubes by utilizing a sacrificial template formed with a nanowire-based network structure. That is, although it is difficult to implement a technique for directly forming metal carbide on the surface of nanowires, first, a metal oxide that is easy to deposit is deposited on the surface of the nanowires, and then reacted with a carbon-containing gas at a high temperature to simultaneously implement the reduction and carbonization of the metal oxide, and the metal carbide can be formed more easily. Thereafter, by removing the sacrificial template by plasma etching or the like, the remaining metal carbide can be manufactured into a porous pellicle film having a network structure based on metal carbide nanotubes so as to correspond to the outer shape of the sacrificial template.

[0036] By removing the sacrificial template in the manufacturing process of the porous pellicle film according to the present invention, the extreme ultraviolet transmittance of the finally manufactured porous pellicle film can be further improved compared to maintaining the sacrificial template.

[0037] In addition, the finally manufactured porous pellicle film according to the present invention does not include a sacrificial template that is vulnerable to hydrogen plasma, so it can provide good chemical durability required in an extreme ultraviolet lithography environment.

Brief Description of the Drawings

[0038]

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BEST MODE FOR CARRYING OUT THE INVENTION

[0039] In the following description, only the parts necessary for understanding the embodiments of the present invention will be described, and it should be noted that the description of the other parts will be omitted as long as they do not deviate from the gist of the present invention.

[0040] The terms and words used in this specification and claims described below should not be construed as being limited to their ordinary or dictionary meanings. The inventor should define the concept of the terms appropriately based on the principle that he can explain his invention in the best way, and should be construed as meanings and concepts that conform to the technical idea of the present invention. Therefore, the embodiments described in this specification and the configurations shown in the drawings are only preferred embodiments of the present invention and do not represent all of the technical ideas of the present invention. It should be understood that there can be various equivalents and modifications that can replace them at the time of this application.

[0041] Hereinafter, embodiments of the present invention will be described in more detail with reference to the accompanying drawings.

[0042] FIG. 1 is a plan view showing a pellicle for extreme ultraviolet lithography based on metal carbide nanotubes according to the present invention. FIG. 2 is an enlarged view of part A in FIG. 1. FIG. 3 is a cross-sectional view showing the metal carbide nanotubes in FIG. 2. FIG. 4 is a cross-sectional view taken along line 4-4 in FIG. 1. Further, FIG. 5 is an enlarged view of part B in FIG. 4.

[0043] Referring to FIGS. 1 to 5, the pellicle 100 for extreme ultraviolet lithography according to the present invention (hereinafter referred to as "pellicle") includes a porous pellicle film 20 having a free-standing structure (support is not required except for support at the peripheral portion by the frame 10) supported by a frame 10. The frame 10 has an opening 13 formed at the center. The porous pellicle film 20 is supported by the frame 10 to cover the opening 13 and is formed in a network structure based on metal carbide nanotubes 50.

[0044] Here, the pellicle 100 is a consumable material that protects the photomask from foreign substances in the lithography process among the semiconductor and display manufacturing processes. That is, the pellicle 100 is a thin film that is placed on the photomask and serves as a cover. Since the light transferred to the wafer is focused on the photomask for exposure, even if there is a foreign substance on the pellicle 100 that is at a certain distance away, since the focus is not achieved, it does not affect the size of the pattern that the user intends to create, and the formation of defective patterns can be reduced.

[0045] Thereby, the pellicle 100 can protect the photomask from foreign substances during the lithography process, minimize defective patterns, and increase the yield of the semiconductor and display manufacturing processes. In addition, the life of the photomask can be extended by using the pellicle 100.

[0046] Thus, the porous pellicle film 20 according to the present invention provides good optical properties and chemical durability such as an extreme ultraviolet transmittance of 90% or more required in the extreme ultraviolet lithography environment by forming a porous structure based on the metal carbide nanotubes 50.

[0047] Hereinafter, the pellicle 100 according to the present invention will be specifically described. As described above, the pellicle 100 includes a frame 10 and a porous pellicle film 20.

[0048] Frame 10 supports the porous pellicle film 20 and can facilitate the handling and transfer of the porous pellicle film 20 during the process of manufacturing the pellicle 100 for extreme ultraviolet lithography and after the manufacturing is completed. Frame 10 can be formed of a material capable of undergoing an etching process such as silicon. For example, the material of Frame 10 includes silicon, silicon oxide, silicon nitride, metal oxide, metal nitride, graphite, amorphous carbon, etc., and a structure in which such materials are laminated is also possible, and the present invention is not limited thereto. Here, the metal can be Cr, Al, Zr, Ti, Ta, Nb, Ni, etc., and the present invention is not limited thereto.

[0049] The open portion 13 formed in the central portion of Frame 10 can be formed using a microfabrication technique such as MEMS (Micro-Electro Mechanical Systems). That is, the central portion of Frame 10 is removed by a microfabrication technique to form the open portion 13. The porous pellicle film 20 is exposed through the open portion 13.

[0050] Also, the porous pellicle film 20 is supported by Frame 10. The porous pellicle film 20 is formed in a network structure based on the metal carbide nanotubes 50. For example, the material of the metal carbide nanotubes 50 includes at least one of molybdenum carbide, niobium carbide, zirconium carbide, ruthenium carbide, yttrium carbide, and aluminum carbide. The portion of the porous pellicle film 20 exposed in the open portion 13 can occupy 70% or more of the total area.

[0051] The porous pellicle film 20 can be manufactured using a sacrificial template in a network structure based on nanowires. The porous pellicle film 20 is formed in a network structure by many metal carbide nanotubes 50. The porous pellicle film 20 may partially include metal carbide nanotubes 50 having a form collapsed by heat treatment. A method for manufacturing the porous pellicle film 20 using a sacrificial template will be described later.

[0052] The shape of the porous pellicle film 20 can be determined by the shape of the frame 10. For example, when the frame 10 has a ring shape in the form of a circle or a square, the porous pellicle film 20 can also have a disc or square plate shape corresponding to the shape of the frame 10.

[0053] Since the porous pellicle film 20 is formed as a network structure based on the metal carbide nanotubes 50, it exhibits a good extreme ultraviolet transmittance of 90% or more. That is, since the metal carbide nanotubes 50 have a nanotube form with a hollow 51 inside, the extreme ultraviolet transmittance is relatively high compared to the nanowires filled inside. Also, since the porous pellicle film 20 is formed of a film in which the metal carbide nanotubes 50 are connected in a network structure, due to the pores formed between the metal carbide nanotubes 50, the extreme ultraviolet transmittance is relatively high compared to a metal carbide layer having the same thickness as the porous pellicle film 20. For example, when the material of the metal carbide nanotubes 50 is molybdenum carbide, the thickness of the porous pellicle film 20 is 20 nm or less and the extreme ultraviolet transmittance is 96% or more.

[0054] Also, the metal carbide nanotubes 50 forming the porous pellicle film 20 have corrosion resistance to hydrogen radicals, so they can provide good chemical durability required in an extreme ultraviolet lithography environment.

[0055] As will be described later, since the porous pellicle film 20 according to the present invention can be manufactured based on a sacrificial template, the porous pellicle film 20 can be easily manufactured compared to the existing pinhole formation process.

[0056] Hereinafter, a method for manufacturing such a porous pellicle film 20 according to the present invention will be described with reference to FIGS. 6 to 13.

[0057] [Method for manufacturing a porous pellicle film according to the first example] FIG. 6 is a flowchart showing a first example of a method for manufacturing a porous pellicle film for extreme ultraviolet lithography based on metal carbide nanotubes according to the present invention.

[0058] Referring to FIG. 6, in step S10, a sacrificial template is manufactured in a network structure based on nanowires. Next, in step S20, a metal carbide precursor is deposited on the surface of the nanowires forming the sacrificial template. Next, in step S31, the metal carbide precursor is heat-treated to form a metal carbide. Next, in step S41, by selectively removing the nanowires that form the sacrificial template, a porous pellicle film is manufactured with the remaining metal carbide.

[0059] Hereinafter, the manufacturing method according to such a first example will be described with reference to FIGS. 7 to 12. Here, FIGS. 7 to 12 are diagrams showing each step of the manufacturing method according to the first example of FIG. 6.

[0060] As shown in FIGS. 7 to 9, in step S10, a sacrificial template 30 is manufactured in a network structure based on nanowires 40. The sacrificial template 30 can have a size corresponding to the size of the porous pellicle film to be manufactured.

[0061] The nanowires 40 are formed of a material that can be selectively removed with respect to the metal carbide precursor 53 or the metal carbide. Such nanowires 40 include at least one of carbon nanotubes, semiconductor nanowires, conductor nanowires, and non-conductor nanowires.

[0062] The nanowires 40 can have the form of a rod filled inside or the form of a nanotube with a hollow formed inside. In FIG. 9, the form of a rod filled inside is exemplified as the nanowires 40.

[0063] The semiconductor nanowires include nanowires based on semiconductors such as silicon.

[0064] The conductor nanowires include nanowires based on at least one conductor of Mo, Zr, Ru, Nb, Mo2C, MoC, ZrC, and NbC.

[0065] The non-conductive nanowires include nanowires based on at least one non-conductive material among SiO2, TiO2, BN, SiC, ZrO2, MoO3, Y2O3, and MgO.

[0066] Such nanowires 40 can be formed of the above-described materials alone, as a compound, or as a mixture. Also, the sacrificial template 30 may be formed of a single type of nanowire 40 in a network structure, or may be formed of two or more types of nanowires 40 in a network structure.

[0067] The sacrificial template 30 can be manufactured by weaving the nanowires 40 or by electrospinning the nanowires 40 into a sheet form. Such a sacrificial template 30 is a sheet having a large number of pores and can be embodied, for example, in the form of a mesh net or a non-woven fabric.

[0068] Next, as shown in FIG. 10, in step S20, a metal carbide precursor 53 is deposited on the surface of the nanowires 40 forming the sacrificial template 30.

[0069] The metal carbide precursor 53 can be formed by at least one process among atomic layer deposition (ALD), chemical vapor deposition (CVD), and physical vapor deposition (PVD). For example, the metal carbide precursor 53 can be directly formed on the surface of the nanowires 40 by atomic layer deposition (ALD) or chemical vapor deposition (CVD). Alternatively, after forming the first metal carbide precursor 53 on the surface of the nanowires 40 by physical vapor deposition (PVD), the second metal carbide precursor can be formed on the surface of the first metal carbide precursor by atomic layer deposition (ALD) or chemical vapor deposition (CVD). Here, the first metal carbide precursor is used as a buffer layer between the nanowires 40 and the second metal carbide precursor. The first metal carbide precursor can be formed to have a thickness of 1 to 5 nm.

[0070] The metal carbide precursor 53 includes at least one of a metal, a metal oxide, a compound and a mixture of the metal or the metal oxide.

[0071] Here, the metal contains at least one of molybdenum (Mo), niobium (Nb), zirconium (Zr), ruthenium (Ru), yttrium (Y), and aluminum (Al).

[0072] The metal oxide is molybdenum oxide (MoO x , 1 ≦ x ≦ 5), niobium oxide (NbO x , 1 ≦ x ≦ 3), zirconium oxide (ZrO x , 0.25 ≦ x ≦ 2), ruthenium oxide (RuO x , 2 ≦ x ≦ 4), yttrium oxide (YO x , 1 ≦ x ≦ 3), and aluminum oxide (Al x O y ) and contains at least one of them.

[0073] Next, as shown in FIG. 11, in step S31, the metal carbide precursor 53 is heat-treated to form a metal carbide. Here, the heat treatment is performed at 500 to 1300° C. together with a reaction gas containing carbon atoms. During the heat treatment, a reaction between the metal contained in the metal carbide precursor 53 and the reaction gas is induced, and the metal carbide precursor 53 formed on the surface of the nanowire 40 is converted into a metal carbide.

[0074] At this time, when a metal oxide is used as the metal carbide precursor 53, oxygen in the metal oxide is removed by the heat treatment. Since the nanowire 40 constituting the sacrificial template 30 is protected by the metal carbide precursor 53, during the heat treatment, the substance constituting the metal carbide precursor 53 and the reaction gas remain almost chemically unreacted. Of course, the substance located on the surface of the nanowire 40 that forms an interface with the metal carbide precursor 53 may react with the metal carbide precursor 53 or the reaction gas during the heat treatment to form a compound.

[0075] The reaction gas may be a gas containing a hydrocarbon containing at least one of methane, ethane, and propane.

[0076] The metal carbide is based on the material of the metal carbide precursor 53. For example, the metal carbide may include at least one of molybdenum carbide, niobium carbide, zirconium carbide, ruthenium carbide, yttrium carbide, and aluminum carbide.

[0077] In the present invention, the reason for forming the metal carbide on the surface of the nanowire 40 using the metal carbide precursor 53 is that it is not easy to directly form the metal carbide on the surface of the nanowire 40. On the other hand, after forming a metal or metal oxide that is easy to deposit on the surface of the nanowire 40 and reacting it with a reaction gas containing carbon at a high temperature to simultaneously perform reduction and carbonization of the oxide, the metal carbide can be easily formed on the surface of the nanowire 40.

[0078] Also, as shown in FIG. 12, in the S41 step, the sacrificial template 30 formed on the nanowire 40 is selectively removed, and a porous pellicle film is manufactured using the remaining metal carbide. That is, in the porous pellicle film, the remaining metal carbide is formed into metal carbide nanotubes 50 so as to correspond to the outer shape of the nanowire 40. As a result, the metal carbide nanotubes 50 form a network structure so as to correspond to the sacrificial template 30. The porous pellicle film may include metal carbide nanotubes 50 having a form collapsed by heat treatment.

[0079] At this time, the nanowire 40 is selectively removed by plasma etching with respect to the metal carbide. By-products generated in the process of forming the metal carbide precursor 53 into the metal carbide are also removed by plasma etching. Here, the by-products can be amorphous carbon, graphene, or graphite.

[0080] As the gas used for plasma etching, a gas having a high etching selectivity ratio with respect to the sacrificial template 30 and the metal carbide can be used. For example, the gas used for plasma etching may include at least one of hydrogen and oxygen.

[0081] [Method for manufacturing a porous pellicle film according to the second example] In addition, in the manufacturing method according to the first example, an example in which the sacrificial template is removed after the heat treatment was disclosed, but the present invention is not limited thereto. For example, as shown in FIG. 13, heat treatment can be performed after removing the sacrificial template. Here, FIG. 13 is a flowchart showing a second example of a method for manufacturing a porous pellicle film for extreme ultraviolet lithography based on metal carbide nanotubes according to the present invention.

[0082] First, in step S10, a sacrificial template is manufactured in a network structure based on nanowires. Next, in step S20, a metal carbide precursor is deposited on the surface of the nanowires forming the sacrificial template. Next, in step S33, the nanowires forming the sacrificial template are selectively removed while leaving the metal carbide precursor. Next, in step S43, the metal carbide precursor is heat-treated to form metal carbide, and a porous pellicle film is manufactured using the metal carbide.

[0083] In the manufacturing method according to the second example, steps S10 and S20 proceed in the same manner as in the manufacturing method according to the first example, and thus the description of steps S10 and S20 will be omitted. Hereinafter, steps S33 and S43 will be described in order.

[0084] In step S33, the nanowires forming the sacrificial template are selectively removed while leaving the metal carbide precursor. When selectively removing the nanowires, in step S41, they can be removed by a plasma process. Alternatively, since the nanowire removal process proceeds before the heat treatment process, the nanowires can be removed by dry etching using at least one of ozone (O3), chlorine (Cl2), chloride, and fluoride in addition to plasma.

[0085] Next, in step S43, the metal carbide precursor is heat-treated to form metal carbide, and a porous pellicle film is manufactured using the metal carbide.

[0086] At this time, the nanowires are removed, and the remaining metal carbide precursor is formed into metal carbide precursor nanotubes so as to correspond to the outer shape of the nanowires. The metal carbide precursor nanotubes are formed into metal carbide nanotubes by heat treatment. The metal carbide nanotubes form a network structure and are manufactured as a porous pellicle film. That is, the porous pellicle film is formed such that the remaining metal carbide precursor nanotubes are formed into metal carbide nanotubes so as to correspond to the outer shape of the nanowires. As a result, the metal carbide nanotubes form a network structure so as to correspond to the sacrificial template. The porous pellicle film may include metal carbide nanotubes having a collapsed form by heat treatment.

[0087] In the manufacturing method according to such a second example, a porous pellicle film can be manufactured as follows.

[0088] First, when aluminum oxide is deposited on a CNT (carbon nanotube) membrane which is one of the sacrificial templates, as shown in FIG. 14, a porous membrane in which the peripheral portion of the intermediate CNT (carbon nanotube) is coated with aluminum oxide can be obtained. Here, FIG. 14 is a TEM (transmission electron microscope) photograph showing a state in which a metal carbide precursor is deposited on the surface of the sacrificial template manufactured by the manufacturing method of FIG. 13.

[0089] Referring to FIG. 14, the aluminum oxide formed on the surface of the CNTs forming the CNT membrane can be manufactured in a form in which all are densely connected.

[0090] Next, when etching a CNT membrane coated with aluminum oxide in an etching environment such as hydrogen plasma and oxygen plasma, the CNTs are etched while the aluminum oxide is not etched. That is, the CNTs can be selectively etched with plasma to produce a porous membrane composed of aluminum oxide nanotubes. Thereafter, by heat-treating the aluminum oxide nanotube-based porous membrane at a high temperature of 500 to 1300 °C, a porous membrane based on aluminum carbide nanotubes, in which the aluminum carbide nanotubes are connected in a network structure, i.e., a pellicle membrane, can be produced.

[0091] Thus, according to the manufacturing methods of the first and second examples, a porous pellicle membrane in which metal carbide nanotubes are connected in a network structure can be more easily manufactured using a sacrificial template.

[0092] [Comparative Examples and Examples] In order to confirm the extreme ultraviolet transmittance of the pellicle membrane manufactured by such a manufacturing method of the present invention in an extreme ultraviolet output environment of 350 W or more, simulations were performed on the pellicle membranes of Comparative Examples 1 to 3 according to FIGS. 15 to 18 and Example 1.

[0093] As the pellicle membrane of Comparative Example 1, a Mo2C thin film was used.

[0094] As the porous pellicle membrane of Comparative Example 2, a CNT membrane without a capping layer was used. In the CNT membrane, the CNTs are connected in a network structure.

[0095] The porous pellicle membrane of Comparative Example 3 is based on the CNT membrane of Comparative Example 2 and has a capping layer of Mo2C thereon. The thickness of the capping layer is 3 nm.

[0096] In addition, the porous pellicle film according to Example 1 was manufactured based on the CNT membrane according to Comparative Example 3, where the CNTs were removed and the Mo2C nanotubes were connected in a network structure. That is, the porous pellicle film according to Example 1 is a membrane in which Mo2C nanotubes are connected in a network structure.

[0097] FIG. 15 is a graph showing the extreme ultraviolet transmittance of the pellicle film according to Comparative Example 1.

[0098] Referring to FIG. 15, it was confirmed that the pellicle film according to Comparative Example 1 had an extreme ultraviolet transmittance of about 90% at a thickness of 17.5 nm.

[0099] FIG. 16 is a graph showing the extreme ultraviolet transmittance of the porous pellicle film according to Comparative Example 2.

[0100] Referring to FIG. 16, it was confirmed that the porous pellicle film according to Comparative Example 2 had an extreme ultraviolet transmittance of about 96.2% at a thickness of 20 nm.

[0101] FIG. 17 is a graph showing the extreme ultraviolet transmittance of the porous pellicle film according to Comparative Example 3.

[0102] Referring to FIG. 17, it was confirmed that when the CNT membrane was coated with Mo2C to a thickness of 3 nm, the porous pellicle film according to Comparative Example 3 had an extreme ultraviolet transmittance of 92.3% at a thickness of 20 nm of the CNT membrane.

[0103] FIG. 18 is a graph showing the extreme ultraviolet transmittance of the porous pellicle film according to Example 1.

[0104] Referring to FIG. 18, it was confirmed that the porous pellicle film according to Example 1 had an extreme ultraviolet transmittance of about 96.2% at a thickness of 20 nm. When the target of the extreme ultraviolet transmittance is 90% or more, the porous pellicle film according to Example 1 can be formed thicker than 20 nm, for example, at a thickness of 40 nm or more.

[0105] The porous pellicle film composed of a network structure of metal carbide nanotubes with the sacrificial template removed as in Example 1 can be confirmed to exhibit a high extreme ultraviolet transmittance equivalent to that of the porous pellicle film composed of a CNT membrane without a capping layer as in Comparative Example 2.

[0106] Note that the porous pellicle film according to Comparative Example 2 lacks a capping layer and is composed of a CNT membrane, so it has the disadvantage of being vulnerable to hydrogen radicals. On the other hand, the porous pellicle film according to Example 1 is composed of Mo2C nanotubes, so it has corrosion resistance to hydrogen radicals and provides good chemical durability required in the extreme ultraviolet lithography environment.

[0107] When comparing Example 1 and Comparative Example 3, the porous pellicle according to Comparative Example 3 contains a CNT membrane and Mo2C nanotubes. The porous pellicle according to Example 1 has a structure in which the CNT membrane is removed from the porous pellicle according to Comparative Example 3. By removing the CNT membrane as in Example 1, it can be confirmed that Example 1 exhibits a relatively higher extreme ultraviolet transmittance than Comparative Example 3.

[0108] Thus, the porous pellicle film according to the present invention can produce a chemically more stable porous pellicle film by removing a sacrificial template and impurities that are vulnerable in a hydrogen plasma environment, which is an extreme ultraviolet lithography environment, through plasma etching. Also, the porous pellicle film according to the present invention can improve the extreme ultraviolet transmittance rather than maintaining the sacrificial template by forming a metal carbide nanotube or a metal carbide precursor using the sacrificial template and then removing the sacrificial template.

[0109] Thereby, the porous pellicle film according to Example 1 can provide a high extreme ultraviolet transmittance of 90% or more and chemical durability required in the extreme ultraviolet lithography environment.

[0110] Note that the embodiments disclosed in this specification and the drawings are merely specific examples presented for the purpose of assisting understanding and are not intended to limit the scope of the present invention. It is obvious to those having ordinary knowledge in the technical field to which the present invention pertains that other variations based on the technical idea of the present invention are feasible in addition to the embodiments disclosed herein.

Explanation of Reference Numerals

[0111] 10 Frame 13 Release Port 20 Porous Periclase Membrane 30 Sacrificial Template 40 Nanowire 50 Metal Carbide Nanotube 51 Hollow 53 Metal Carbide Precursor 100 Periclase for Extreme Ultraviolet Lithography

Claims

1. Manufacturing a sacrificial template with a network structure based on nanowires; Depositing a metal carbide precursor on the surface of the nanowires forming the sacrificial template; Heat-treating the metal carbide precursor to form metal carbide; and Selectively removing the nanowires forming the sacrificial template and manufacturing a porous pellicle film with the remaining metal carbide; A method for manufacturing a porous pellicle film for extreme ultraviolet lithography, comprising the above steps.

2. In the step of manufacturing the porous pellicle film, The porous pellicle film is characterized in that the remaining metal carbide is formed of metal carbide nanotubes so as to correspond to the outer shape of the nanowires, and the metal carbide nanotubes form a network structure. The method for manufacturing a porous pellicle film for extreme ultraviolet lithography according to Claim 1.

3. The method for manufacturing a porous pellicle film for extreme ultraviolet lithography according to Claim 2, wherein the porous pellicle film contains metal carbide nanotubes having a form collapsed by heat treatment.

4. The method for manufacturing a porous pellicle film for extreme ultraviolet lithography according to Claim 2, wherein the nanowires are formed of a material that can be selectively removed with respect to the metal carbide precursor or the metal carbide.

5. The method for manufacturing a porous pellicle film for extreme ultraviolet lithography according to Claim 3, wherein the nanowires contain at least one of carbon nanotubes, semiconductor nanowires, conductor nanowires, and non-conductor nanowires.

6. In the step of deposition, The metal carbide precursor contains at least one of a metal, a metal oxide, a compound and a mixture of the metal or the metal oxide, The metal contains at least one of molybdenum (Mo), niobium (Nb), zirconium (Zr), ruthenium (Ru), yttrium (Y), and aluminum (Al), or The metal oxide is molybdenum oxide (MoO ｘ , 1 ≦ x ≦ 5), niobium oxide (NbO ｘ , 1 ≦ x ≦ 3), zirconium oxide (ZrO ｘ , 0.25 ≦ x ≦ 2), ruthenium oxide (RuO ｘ , 2 ≦ x ≦ 4), yttrium oxide (YO ｘ , 1 ≦ x ≦ 3) and aluminum oxide (Al ｘ O ｙ ), and the method for producing a porous pellicle film for extreme ultraviolet lithography according to claim 2, characterized by containing at least one of them.

7. In the step of deposition, The method for manufacturing a porous pellicle film for extreme ultraviolet lithography according to Claim 6, wherein the metal carbide precursor is formed by atomic layer deposition (ALD) or chemical vapor deposition (CVD).

8. The step of deposition is Forming a first metal carbide precursor on the surface of the nanowires by physical vapor deposition (PVD); and forming a second metal carbide precursor on the surface of the first metal carbide precursor by atomic layer deposition (ALD) or chemical vapor deposition (CVD); A method for manufacturing a porous pellicle film for extreme ultraviolet lithography according to claim 6, characterized by comprising the steps of:

9. In the step of forming on the metal carbide, The method for manufacturing a porous pellicle film for extreme ultraviolet lithography according to claim 6, wherein the metal carbide contains at least one of molybdenum carbide, niobium carbide, zirconium carbide, ruthenium carbide, yttrium carbide, and aluminum carbide.

10. When the material of the metal carbide nanotube is molybdenum carbide, The method for manufacturing a porous pellicle film for extreme ultraviolet lithography according to claim 6, wherein the thickness of the porous pellicle film is 20 nm or less and the extreme ultraviolet transmittance is 96% or more.

11. In the step of forming on the metal carbide, The method for manufacturing a porous pellicle film for extreme ultraviolet lithography according to claim 1, characterized by heat-treating at 500 to 1300 ° C together with a reaction gas containing carbon atoms.

12. The method for manufacturing a porous pellicle film for extreme ultraviolet lithography according to claim 11, wherein the reaction gas is a gas containing a hydrocarbon containing at least one of methane, ethane, and propane.

13. In the step of manufacturing the porous pellicle film, The method for manufacturing a porous pellicle film for extreme ultraviolet lithography according to claim 1, characterized in that the nanowire is selectively removed by plasma etching.

14. In the step of manufacturing the porous pellicle film, The method for manufacturing a porous pellicle film for extreme ultraviolet lithography according to claim 13, characterized in that by-products generated in the process of forming the metal carbide precursor into a metal carbide are removed by the plasma etching.

15. manufacturing a sacrificial template in a network structure based on nanowires; depositing a metal carbide precursor on the surface of the nanowires forming the sacrificial template; selectively removing the nanowires that formed the sacrificial template while leaving the metal carbide precursor; and heat-treating the metal carbide precursor to form a metal carbide, and manufacturing a porous pellicle film with the metal carbide; A method for manufacturing a porous pellicle film for extreme ultraviolet lithography, comprising:

16. In the step of removing, The nanowires are removed, and the remaining metal carbide precursor is formed as metal carbide precursor nanotubes so as to correspond to the outer shape of the nanowires, and the metal carbide precursor nanotubes form a network structure. In the step of manufacturing the porous pellicle film, The method for manufacturing a porous pellicle film for extreme ultraviolet lithography according to claim 15, wherein in the porous pellicle film, the metal carbide precursor nanotubes are formed into metal carbide nanotubes by heat treatment, and the metal carbide nanotubes form a network structure.

17. In the removing step, Removing the nanowire using at least one of plasma, ozone (O ３ ), chlorine (Cl ２ ), chloride, and fluoride, the method for manufacturing a porous pellicle film for extreme ultraviolet lithography according to claim 15.

18. A frame having an opening formed in a central portion; and A porous pellicle film supported by the frame to cover the opening and formed of a network structure based on metal carbide nanotubes; A pellicle for extreme ultraviolet lithography including the above.

19. The pellicle for extreme ultraviolet lithography according to claim 18, wherein the material of the metal carbide nanotubes includes at least one of molybdenum carbide, niobium carbide, zirconium carbide, ruthenium carbide, yttrium carbide, and aluminum carbide.

20. When the material of the metal carbide nanotubes is molybdenum carbide, The pellicle for extreme ultraviolet lithography according to claim 18, wherein the thickness of the porous pellicle film is 20 nm or less and the extreme ultraviolet transmittance is 96% or more.

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