Classifications

• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
  • G03F7/70—Microphotolithographic exposure; Apparatus therefor
  • G03F7/708—Construction of apparatus, e.g. environment aspects, hygiene aspects or materials
  • G03F7/7095—Materials, e.g. materials for housing, stage or other support having particular properties, e.g. weight, strength, conductivity, thermal expansion coefficient
  • G03F7/70958—Optical materials or coatings, e.g. with particular transmittance, reflectance or anti-reflection properties
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F1/00—Originals for photomechanical production of textured or patterned surfaces, e.g., masks, photo-masks, reticles; Mask blanks or pellicles therefor; Containers specially adapted therefor; Preparation thereof
  • G03F1/62—Pellicles, e.g. pellicle assemblies, e.g. having membrane on support frame; Preparation thereof
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
  • G03F7/70—Microphotolithographic exposure; Apparatus therefor
  • G03F7/70008—Production of exposure light, i.e. light sources
  • G03F7/70033—Production of exposure light, i.e. light sources by plasma extreme ultraviolet [EUV] sources
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
  • G03F7/70—Microphotolithographic exposure; Apparatus therefor
  • G03F7/708—Construction of apparatus, e.g. environment aspects, hygiene aspects or materials
  • G03F7/70983—Optical system protection, e.g. pellicles or removable covers for protection of mask

Definitions

• This disclosure relates to an EUV-transmitting film, a method for processing the film, and an exposure method.
• Patent Document 1 Japanese Patent No. 68588157 discloses a pellicle membrane having a core layer containing a material that is substantially transparent to EUV radiation, such as (poly)Si, and a cap layer containing a material that absorbs IR radiation.
• Patent Document 2 JP 2020-98227 A discloses a pellicle film that is stretched over one end surface of a pellicle frame, and that has a main layer of single-crystal Si and graphene on one or both sides of the main layer. It is said that the presence of graphene in the main layer prevents damage to the pellicle film during pellicle fabrication and ensures sufficient mechanical strength.
• Patent No. 6858817 Japanese Patent Application Laid-Open No. 2020-98227
• the core materials used in pellicle films which have high EUV transmittance, as mentioned above, form a natural oxide film of several nanometers thick on their surface in the atmosphere.
• This oxide film absorbs EUV light, reducing the EUV transmittance of the pellicle film.
• Be in particular, is a material with high EUV transmittance, but it is said that a natural oxide film of 2 to 3 nm thick forms on its surface, resulting in a significant transmittance loss of 6 to 9%.
• the process of producing pellicle films sometimes involves treatment with gases other than the atmosphere, such as fluorine or chlorine, or with acid or alkaline solutions, which can cause a side reaction film to form on the surface of the core material, which can reduce EUV transmittance. Therefore, it is desirable to form a protective layer on the surface of the core material to suppress the formation of these films.
• gases other than the atmosphere such as fluorine or chlorine
• acid or alkaline solutions which can cause a side reaction film to form on the surface of the core material, which can reduce EUV transmittance. Therefore, it is desirable to form a protective layer on the surface of the core material to suppress the formation of these films.
• a reaction-suppressing protective layer to the surface of core materials such as Si or Be can prevent a significant decrease in the EUV transmittance of the pellicle film, such protective layers still have a lower EUV transmittance than the pure core material, leading to a decrease in the EUV transmittance of the pellicle film as a whole.
• Ru can be used as a protective layer for Be core material.
• the Ru protective layer causes a loss of EUV transmittance of approximately 3-6%, significantly reducing the performance of the pellicle film.
• pellicle films are also desired to have not only high EUV transmittance but also excellent in-plane uniformity of EUV transmittance. This is because the better the in-plane uniformity of EUV transmittance, the more uniform the in-plane exposure dose and the improved homogeneity of devices manufactured through EUV exposure.
• the inventors have now discovered that by adopting a five-layer structure of amorphous carbon layer/nitride layer/metallic beryllium layer/nitride layer/amorphous carbon layer, it is possible to provide an EUV transmitting film that has high EUV transmittance and excellent in-plane uniformity of EUV transmittance, even while having protective layers on both sides.
• a metallic beryllium layer having a first surface and a second surface; a first nitride layer covering a first surface of the metal beryllium layer and including at least one selected from the group consisting of silicon nitride, beryllium nitride, boron nitride, and zirconium nitride; a second nitride layer covering a second surface of the metal beryllium layer and including at least one selected from the group consisting of silicon nitride, beryllium nitride, boron nitride, and zirconium nitride; a first protective layer including amorphous carbon covering a surface of the first nitride layer opposite to the metal beryllium layer; a second protective layer including amorphous carbon covering the second nitride layer on the side opposite to the metal beryllium layer; An EUV transmitting film having a five
• a method for processing an EUV transmitting film comprising: [Aspect 9] A step of installing the EUV transmitting film according to any one of aspects 1 to 7 in an apparatus that generates hydrogen plasma and/or hydrogen radicals, or oxygen plasma and/or oxygen radicals; contacting the EUV transmitting film with hydrogen plasma and/or hydrogen radicals, or oxygen plasma and/or oxygen radicals, thereby thinning the first protective layer and the second protective layer; a step of attaching the EUV transmitting film in which the first protective layer and the second protective layer have been thinned in an EUV exposure apparatus, allowing EUV to transmit through the EUV transmitting film, and performing pattern exposure on a
• 1 is a schematic cross-sectional view showing one embodiment of an EUV transmitting film according to the present invention.
• 1 is a process flow diagram showing the first half of a manufacturing procedure for an EUV transmitting film in an example.
• 1 is a process flow diagram showing the latter half of the manufacturing procedure for the EUV transmitting film in the example.
• FIG. 1 shows a schematic cross-sectional view of an EUV transmitting film 10 according to one embodiment of the present invention.
• the EUV transmitting film 10 is a five-layer film consisting of a metal beryllium layer 12, a first nitride layer 14a, a second nitride layer 14b, a first protective layer 16a, and a second protective layer 16b.
• the metal beryllium layer 12 has a first surface 12a and a second surface 12b.
• the first nitride layer 14a is a layer covering the first surface 12a of the metal beryllium layer 12 and containing at least one selected from the group consisting of silicon nitride, beryllium nitride, boron nitride, and zirconium nitride.
• the second nitride layer 14b is a layer covering the second surface 12b of the metal beryllium layer 12 and containing at least one selected from the group consisting of silicon nitride, beryllium nitride, boron nitride, and zirconium nitride.
• the first protective layer 16a is a layer containing amorphous carbon that covers the surface of the first nitride layer 14a opposite the metal beryllium layer 12.
• the second protective layer 16b is a layer containing amorphous carbon that covers the surface of the second nitride layer 14b opposite the metal beryllium layer 12.
• the EUV transmitting coating 10 has an EUV transmittance of 85% or more at a wavelength of 13.5 nm.
• first protective layer 16a amorphous carbon layer
• first nitride layer 14a metal beryllium layer 12
• second nitride layer 14b metal beryllium layer 12
• second protective layer 16b amorphous carbon layer
• core materials with high EUV transmittance may form a native oxide film several nanometers thick on their surface in the atmosphere.
• the process of manufacturing a pellicle film may involve treatment with gases other than the atmosphere, such as fluorine or chlorine, or with acid or alkaline solutions, which can result in the formation of a side reaction film on the surface of the core material.
• gases other than the atmosphere such as fluorine or chlorine
• acid or alkaline solutions which can result in the formation of a side reaction film on the surface of the core material.
• applying a reaction-suppressing protective layer to the surface of the core material leads to a decrease in the EUV transmittance of the pellicle film as a whole.
• a pellicle film it is desirable for a pellicle film to not only have high EUV transmittance, but also excellent in-plane uniformity of EUV transmittance. This is because the better the in-plane uniformity of EUV transmittance, the more uniform the in-plane exposure dose, improving the homogeneity of devices manufactured through EUV exposure.
• the EUV transmitting film of the present invention comprises a main layer 11 made of a first nitride layer 14a, a metal beryllium layer 12, and a second nitride layer 14b, each of which has a high EUV transmittance, and a first protective layer 16a and a second protective layer 16b covering both sides of the main layer 11, and these protective layers 16a and 16b can prevent the formation of a natural oxide film or a side reaction film that would occur on the surface of the main layer 11 (if the protective layers 16a and 16b were not present) during the time period until the fabricated pellicle is loaded into an EUV exposure tool and subjected to an exposure process.
• the EUV transmitting film 10 of the present invention can exhibit high EUV transmittance despite having a five-layer structure including the protective layers 16a and 16b.
• the five-layer EUV transmitting film 10 having the protective layers 16a and 16b has the advantage of superior in-plane uniformity of EUV transmittance compared to a three-layer main layer alone without the protective layers 16a and 16b. This is thought to be because the protective layers 16a and 16b formed on both sides more even out the irregularities on both sides of the three-layer main layer. This advantage ensures a uniform in-plane exposure dose during EUV exposure through the EUV transmitting film 10, improving the uniformity of devices manufactured through EUV exposure.
• the EUV transmitting film 10 has a high EUV transmittance.
• the EUV transmitting film 10 has an EUV transmittance at a wavelength of 13.5 nm of 85% or more, preferably 90% or more, more preferably 91% or more, and even more preferably 92% or more.
• the metal beryllium layer 12 is a layer containing metal beryllium as its main component.
• the "main component" of the metal beryllium layer 12 refers to a component that accounts for 50 mol % or more of the metal beryllium layer 12, preferably 70 mol % or more, more preferably 80 mol % or more, and even more preferably 90 mol % or more.
• the metal beryllium layer 12 may also contain impurities in addition to the metal beryllium as its main component. Therefore, the metal beryllium layer 12 may consist of metal beryllium and unavoidable impurities.
• the thickness of the metal beryllium layer 12 is preferably 5 to 25 nm, more preferably 7 to 20 nm, and even more preferably 9 to 15 nm.
• Each of the first nitride layer 14a and the second nitride layer 14b contains at least one nitride selected from the group consisting of silicon nitride, beryllium nitride, boron nitride, and zirconium nitride. Silicon nitride is particularly preferred.
• the advantages of providing the first nitride layer 14a and the second nitride layer 14b on both sides of the metal beryllium layer 12 are explained as follows. For example, if an amorphous carbon protective layer is provided directly on the main layer, which is a metal beryllium layer, the amorphous carbon may react with the metal beryllium to form beryllium carbide.
• the main layer with a three-layer structure of the first nitride layer 14a/metal beryllium layer 12/first nitride layer 14a and providing the amorphous carbon protective layers 16a and 16b on the nitride layers 14a and 14b, the reaction between the amorphous carbon and the metal beryllium can be prevented, i.e., the reaction between the main layer and the protective layer can be suppressed.
• the terms "silicon nitride,”"berylliumnitride,””boronnitride,” and “zirconium nitride” refer to comprehensive compositions that include not only stoichiometric compositions such as Si 3 N 4 , Be 3 N 2 , BN, and ZrN, but also non-stoichiometric compositions such as Si 3 N 4- x (wherein 0 ⁇ x ⁇ 4), Be 3 N 2- x (wherein 0 ⁇ x ⁇ 2), BN x (wherein 0 ⁇ x ⁇ 1), and ZrN x (wherein 0 ⁇ x ⁇ 1).
• the thickness of each of the first nitride layer 14a and the second nitride layer 14b is preferably 1 to 5 nm, and more preferably 1 to 3 nm.
• the first nitride layer 14a, the metal beryllium layer 12, and the second nitride layer 14b constitute the main layer 11 of the EUV-transmitting film.
• the main layer 11 contributes to achieving high EUV transmittance while ensuring the basic functions of a pellicle film (such as preventing particle adhesion).
• the thickness of the main layer 11 is preferably 7 to 30 nm, more preferably 9 to 26 nm, and even more preferably 11 to 21 nm.
• the main layer 11 preferably has a nitrogen concentration gradient region in which the nitrogen concentration decreases toward the metal beryllium layer 12. That is, as described above, beryllium nitride compositions can range from stoichiometric compositions such as Be3N2 to non-stoichiometric compositions such as Be3N2 -x (where 0 ⁇ x ⁇ 2) . However, it is preferable for the beryllium nitride constituting the beryllium nitride layer to have a gradient composition that approaches a beryllium-rich composition toward the metal beryllium layer 12.
• the thickness of the nitrogen concentration gradient region is preferably smaller than the thickness of each of the nitride layers 14a, 14b. That is, the entire thickness of each of the nitride layers 14a, 14b does not need to be the nitrogen concentration gradient region.
• each of the nitride layers 14a, 14b for example, a region of 10 to 70% of the thickness of each of the nitride layers 14a, 14b is the nitrogen concentration gradient region, and more preferably, a region of 15 to 50% is the nitrogen concentration gradient region.
• Each of the first protective layer 16a and the second protective layer 16b is a layer containing amorphous carbon.
• Layers containing amorphous carbon not only provide high protection against various chemicals (e.g., highly reactive fluorine-based etching agents) used in the pellicle film manufacturing process (e.g., the self-supporting film process), but also have the advantages of high EUV transmittance, minimal impact on the main layer 11 from residues left behind when the protective layers 16a and 16b are thinned or removed, and ease of thinning or removal of the protective layers 16a and 16b.
• the first protective layer 16a and the second protective layer 16b preferably contain amorphous carbon as their primary component, and are more preferably composed of amorphous carbon.
• Amorphous carbon generally does not have a completely random atomic arrangement, and while it has a crystalline structure microscopically (i.e., it has microcrystals), these microcrystals are often arranged irregularly, resulting in an amorphous structure overall.
• DLC diamond-like carbon
• GLC graphite-like carbon
• the first protective layer 16a and the second protective layer 16b may be carbon with a completely irregular atomic arrangement, or carbon with irregular microcrystals.
• the first protective layer 16a and the second protective layer 16b may be amorphous carbon that is not completely dense and contains fine pores.
• the "major component" in the first protective layer 16a and the second protective layer 16b refers to a component that accounts for 50 wt% or more, preferably 60 wt% or more, more preferably 70 wt% or more, and even more preferably 80 wt% or more of the total weight of the first protective layer 16 or the second protective layer 16b.
• the first protective layer 16a and the second protective layer 16b may be composed solely of amorphous carbon.
• each of the first protective layer 16a and the second protective layer 16b be 1 to 10 nm or less, more preferably 2 to 7 nm, and even more preferably 3 to 5 nm. These ranges make it possible to more effectively achieve high EUV transmittance and improve the in-plane uniformity of EUV transmittance. Furthermore, thicker protective layers 16a and 16b are desirable to protect the EUV-transmitting film 10 (particularly the main layer 11) from various chemicals (e.g., highly reactive fluorine-based etching agents) used in the pellicle film manufacturing process (e.g., the self-supporting film process). However, increasing the film thickness reduces the EUV transmittance of the EUV-transmitting film 10.
• various chemicals e.g., highly reactive fluorine-based etching agents
• each of the first protective layer 16a and the second protective layer 16b extremely thin, preferably at least 1 nm but less than 2 nm, and more preferably at least 1 nm but less than 1.5 nm.
• the EUV transmitting film 10 preferably has a main region for transmitting EUV in the form of a free-standing film. That is, it is preferable that the substrate (e.g., Si substrate) used during film formation remains as a border only at the outer edge of the EUV transmitting film 10; in other words, it is preferable that no substrate (e.g., Si substrate) remains in the main region other than the outer edge; that is, the main region is preferably composed only of the main layer 11 and protective layers 16a and 16b.
• the substrate e.g., Si substrate
• the EUV transmitting film according to the present invention can be produced by forming a laminated film to be used as the EUV transmitting film on a Si substrate, and then removing unnecessary portions of the Si substrate by etching to form a free-standing film. Therefore, as described above, the main part of the EUV transmitting film is in the form of a free-standing film with no Si substrate remaining.
• a Si substrate is prepared on which a laminated film is to be formed.
• the main region i.e., the region to be a free-standing film
• the wet etching mask may be made of any material that is corrosion-resistant to a wet etching solution for Si, such as SiO2 .
• the wet etching solution is not particularly limited as long as it can etch Si.
• TMAH tetramethylammonium hydroxide
• TMAH tetramethylammonium hydroxide
• a laminated film consisting of the second protective layer 16b, the second nitride layer 14b, the metal beryllium layer 12, the first nitride layer 14a, and the first protective layer 16a is formed in this order on the Si substrate.
• the laminated film may be formed by any film formation method.
• a preferred example of the film formation method is sputtering.
• the metal beryllium layer 12 is preferably formed by sputtering using a pure Be target.
• the amorphous carbon films serving as the first protective layer 16a and the second protective layer 16b are preferably formed by sputtering using a graphite target.
• the first nitride layer 14a and the second nitride layer 14b are also preferably formed by sputtering.
• a Si, Be, B, or Zr film may be formed by sputtering using a Si, Be, B, or Zr target, and then nitrogen plasma may be applied to cause a nitriding reaction of the Si, Be, B, or Zr, thereby forming the nitride layers 14a and 14b.
• the first nitride layer 14a and the second nitride layer 14b may be formed by reactive sputtering.
• This reactive sputtering can be performed, for example, by introducing nitrogen gas into the chamber during sputtering using a Si, Be, B, or Zr target, thereby reacting the Si, Be, B, or Zr with nitrogen to produce silicon nitride, beryllium nitride , boron nitride , or zirconium nitride.
• the nitride layers 14a and 14b may be directly formed by sputtering using a Si3N4 , Be3N2 , BN, or ZrN target.
• nitrogen gas may be introduced into the chamber to promote the reaction of Si, Be, B, or Zr with nitrogen to produce silicon nitride, beryllium nitride, boron nitride, or zirconium nitride, as in the reactive sputtering described above in (ii).
• the methods for forming the metal beryllium layer 12, nitride layers 14a, 14b, and protective layers 16a, 16b are not limited to these.
• the metal beryllium layer 12, nitride layers 14a, 14b, and protective layers 16a, 16b may be formed in a single-chamber sputtering system, as in the examples described below, or the metal beryllium layer 12, nitride layers 14a, 14b, and protective layers 16a, 16b may be formed in separate chambers using a multi-chamber sputtering system.
• first nitride layer 14a and the second nitride layer 14b are beryllium nitride layers containing a nitrogen concentration gradient region, i.e., when forming a nitrogen concentration gradient region in a main layer 11 with a three-layer structure of beryllium nitride/beryllium/beryllium nitride, nitrogen gas can be introduced into the chamber and sputtering using a pure Be target can be continued during the deposition of beryllium nitride and metallic beryllium. The introduction of nitrogen gas can then be stopped midway through the deposition of metallic beryllium.
• the nitrogen concentration gradient region can be formed by continuing sputtering and then starting the introduction of nitrogen gas midway through the deposition.
• the thickness of the nitrogen concentration gradient region can be controlled by adjusting the time for changing the nitrogen gas concentration.
• the manufactured EUV transmitting film 10 may be thinned as desired. As described above, thinning the first protective layer 16a and the second protective layer 16b can achieve higher EUV transmittance while maintaining a minimum level of protective performance. In particular, after the self- supporting film formation process using a fluorine-based etchant such as XeF2 described above, the first protective layer 16a and the second protective layer 16b no longer require strong protective properties against the fluorine-based etchant; a mild protective function such as oxidation resistance is sufficient. Therefore, after the EUV transmitting film 10 is formed into a self-supporting film, it may be advantageous to make the EUV transmitting film thinner than the protective layers 16a and 16b to further increase EUV transmittance.
• a fluorine-based etchant such as XeF2
• the thinning of the EUV transmitting film 10 is preferably performed by placing the EUV transmitting film 10 in an apparatus that generates hydrogen plasma and/or hydrogen radicals, or oxygen plasma and/or oxygen radicals, and exposing the EUV transmitting film 10 to hydrogen plasma and/or hydrogen radicals, or oxygen plasma and/or oxygen radicals.
• an apparatus that generates hydrogen plasma and/or hydrogen radicals, or oxygen plasma and/or oxygen radicals
• exposing the EUV transmitting film 10 to hydrogen plasma and/or hydrogen radicals, or oxygen plasma and/or oxygen radicals By exposing the amorphous carbon films that are the first protective layer 16 a and the second protective layer 16 b to a hydrogen plasma and/or hydrogen radical atmosphere or an oxygen plasma and/or oxygen radical atmosphere, C on the surface of the amorphous carbon film reacts with H, thereby partially removing the amorphous carbon film, thereby making it possible to thin the first protective layer 16 a and the second protective layer 16 b.
• the first protective layer 16 a and the second protective layer 16 b As described above , by thinning the first protective layer 16 a and the second protective layer 16 b, it is possible to achieve even higher EUV transmittance while ensuring a minimum level of protective performance. Therefore, it is preferable to thin the first protective layer 16 a and the second protective layer 16 b during exposure.
• a preferred exposure method includes the steps of: installing the EUV transmitting film 10 in an apparatus that generates hydrogen plasma and/or hydrogen radicals, or oxygen plasma and/or oxygen radicals; bringing the EUV transmitting film 10 into contact with the hydrogen plasma and/or hydrogen radicals, or oxygen plasma and/or oxygen radicals, thereby thinning the first protective layer 16 a and the second protective layer 16 b; and installing the EUV transmitting film 10 with the thinned first protective layer 16 a and the second protective layer 16 b in an EUV exposure apparatus, allowing EUV light to pass through the EUV transmitting film 10, and performing pattern exposure on a photosensitive substrate in the EUV exposure apparatus.
• Example 1 According to the procedure shown in FIGS. 2A and 2B, a composite free-standing film (EUV-transmitting film) having a five-layer structure of amorphous carbon/silicon nitride/Be/silicon nitride/amorphous carbon was fabricated as follows.
• FIG. 2A(a) An 8-inch (20.32 cm) diameter Si wafer 20 was prepared ( FIG. 2A(a)).
• a 50-nm-thick SiO 2 film 22 was formed on both sides of the Si wafer 20 by thermal oxidation ( FIG. 2A(b)).
• Resist was applied to both sides of the Si wafer 20, and exposure and development were performed to create a 110 mm ⁇ 145 mm resist hole on one side to form a resist mask 24 for SiO 2 etching ( FIG. 2A(c)).
• One side of the substrate was wet-etched with hydrofluoric acid to remove the exposed portion of the SiO 2 film 22, thereby producing a SiO 2 mask 22a ( FIG. 2A(d)).
• the resist mask 24 for SiO 2 etching was removed using an ashing device ( FIG. 2A(e)). Subsequently, the Si was wet-etched using TMAH solution. The etching rate was measured in advance, and the etching was performed for the time required to achieve the target Si substrate thickness of 50 ⁇ m ( FIG. 2A(f)). Finally, the SiO2 film 22 formed on the unetched surface of the Si wafer was removed and cleaned with hydrofluoric acid to prepare a Si substrate 28 (FIG. 2B(g)). The Si substrate may be diced with a laser 30 (FIG. 2B(h)) to obtain a desired shape (FIG. 2B(i)). In this way, a 110 mm x 145 mm cavity 26 was provided in the center of the 8-inch (20.32 cm) Si wafer 20, and a Si substrate 28 with a Si thickness of 50 ⁇ m in the cavity 26 portion was prepared.
• the chamber was evacuated again, and sputtering was performed using a Si3N4 target at an internal pressure of 0.3 Pa with argon gas plus 20% nitrogen gas, and the sputtering was terminated when a 2 nm Si3N4 film was formed. Furthermore, the chamber was evacuated again, and sputtering was performed using a pure Be target at an internal pressure of 0.5 Pa with argon gas alone, and the sputtering was terminated when a 20 nm beryllium film was formed.
• the chamber was evacuated again, and sputtering was performed using a Si3N4 target at an internal pressure of 0.3 Pa with argon gas plus 20% nitrogen gas, and the sputtering was terminated when a 2 nm Si3N4 film was formed. Thereafter, sputtering was performed using a graphite target in the same manner as the first step, and the sputtering was terminated when a 2 nm amorphous carbon film was formed.
• a composite film of amorphous carbon (C) 2 nm/silicon nitride (Si 3 N 4-x ) 2 nm/beryllium (Be) 20 nm/silicon nitride (Si 3 N 4-x ) 2 nm/amorphous carbon (C) 2 nm was formed as the EUV transmitting film 10.
• this EUV transmitting film 10 has a five-layer structure consisting of a main layer made up of three layers: a first silicon nitride layer, a metal beryllium layer, and a second silicon nitride layer, and a first protective layer and a second protective layer formed on both sides of the main layer and containing amorphous carbon as a main component.
• the valve between the auxiliary chamber and the chamber was opened, and XeF2 gas was introduced into the chamber.
• the XeF2 gas decomposed into Xe and F, and the F reacted with Si to produce SiF4 . Since the boiling point of SiF4 is -95°C, the generated SiF4 quickly evaporated, causing a reaction of F with the newly exposed Si substrate.
• the chamber was evacuated and XeF2 gas was again introduced into the chamber to continue etching.
• Example 2 An EUV transmitting film 10 having a Si border 20 was produced in the same manner as in Example 1. Thereafter, the amorphous carbon film exposed on both sides of the EUV transmitting film 10 was etched with hydrogen plasma to reduce the thickness of each amorphous carbon layer to 1 nm. In this way, a five-layer composite free-standing film having a Si border 20 and consisting of amorphous carbon (C) 1 nm/silicon nitride (Si 3 N 4-x ) 2 nm/beryllium (Be) 20 nm/silicon nitride (Si 3 N 4-x ) 2 nm/amorphous carbon (C) 1 nm was obtained as the EUV transmitting film 10.
• amorphous carbon (C) 1 nm/silicon nitride Si 3 N 4-x
• Be beryllium
• Example 3 (Comparison) An EUV transmitting film 10 having a Si border 20 was produced in the same manner as in Example 1. Thereafter, the amorphous carbon film exposed on both sides of the EUV transmitting film 10 was etched with hydrogen plasma to remove each amorphous carbon layer. In this way, a three-layer composite free-standing film having a Si border 20 and consisting of silicon nitride (Si 3 N 4-x ) 2 nm/beryllium (Be) 20 nm/silicon nitride (Si 3 N 4-x ) 2 nm was obtained as the EUV transmitting film 10.
• the freestanding films serving as EUV transmitting films prepared in Examples 1 to 3 for EUV transmittance and in-plane uniformity were irradiated with EUV light at an output of 600 W in a hydrogen atmosphere at 20 Pa for 15 minutes, and the transmitted EUV light intensity was measured with a sensor.
• the EUV transmittance was calculated by comparing the obtained measured values with the EUV light intensity directly measured with a sensor without an EUV transmitting film, and the results shown in Table 1 were obtained.
• the EUV light spot used for the transmittance measurement had an elliptical shape of 0.5 mm ⁇ 0.2 mm, and the EUV transmittance was measured within this spot size.
• the EUV transmittance was measured at each location by moving the EUV light spot, and the in-plane variation was calculated from the data as three times the standard deviation. Therefore, a smaller in-plane variation indicates better in-plane uniformity of EUV transmittance.
• the present invention can provide an EUV transmitting film that is suitable for improving device uniformity while achieving high EUV transmittance.

Landscapes

• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Health & Medical Sciences (AREA)
• Environmental & Geological Engineering (AREA)
• Epidemiology (AREA)
• Public Health (AREA)
• Plasma & Fusion (AREA)
• Preparing Plates And Mask In Photomechanical Process (AREA)
• Laminated Bodies (AREA)

Priority Applications (6)

Applications Claiming Priority (1)

Related Child Applications (1)

Publications (1)

Family

ID=96881136

Family Applications (1)

Country Status (6)

Families Citing this family (1)

Citations (10)

Family Cites Families (2)

• 2024
  • 2024-02-29 WO PCT/JP2024/007654 patent/WO2025182054A1/ja active Pending
  • 2024-02-29 EP EP24861346.5A patent/EP4636488A1/en active Pending
  • 2024-02-29 JP JP2025514414A patent/JPWO2025182054A1/ja active Pending
  • 2024-02-29 KR KR1020257008406A patent/KR20250134065A/ko active Pending
• 2025
  • 2025-01-03 TW TW114100249A patent/TW202540760A/zh unknown
  • 2025-03-18 US US19/082,623 patent/US20250278032A1/en active Pending

Patent Citations (11)

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events