WO2022172878A1 - 反射型フォトマスクブランク及び反射型フォトマスク - Google Patents
反射型フォトマスクブランク及び反射型フォトマスク Download PDFInfo
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- WO2022172878A1 WO2022172878A1 PCT/JP2022/004498 JP2022004498W WO2022172878A1 WO 2022172878 A1 WO2022172878 A1 WO 2022172878A1 JP 2022004498 W JP2022004498 W JP 2022004498W WO 2022172878 A1 WO2022172878 A1 WO 2022172878A1
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- phase shift
- layer
- reflective photomask
- absorption layer
- reflective
- Prior art date
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- 230000010363 phase shift Effects 0.000 claims abstract description 86
- 239000000463 material Substances 0.000 claims abstract description 61
- 239000000758 substrate Substances 0.000 claims abstract description 33
- 238000012546 transfer Methods 0.000 claims abstract description 25
- 230000008033 biological extinction Effects 0.000 claims abstract description 20
- 230000003287 optical effect Effects 0.000 claims abstract description 18
- 238000010521 absorption reaction Methods 0.000 claims description 101
- 229910052718 tin Inorganic materials 0.000 claims description 22
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 claims description 21
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 19
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims description 19
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 claims description 10
- 239000010949 copper Substances 0.000 claims description 10
- 229910052750 molybdenum Inorganic materials 0.000 claims description 10
- 239000011733 molybdenum Substances 0.000 claims description 10
- 229910052738 indium Inorganic materials 0.000 claims description 9
- APFVFJFRJDLVQX-UHFFFAOYSA-N indium atom Chemical compound [In] APFVFJFRJDLVQX-UHFFFAOYSA-N 0.000 claims description 8
- 229910052759 nickel Inorganic materials 0.000 claims description 7
- 229910052697 platinum Inorganic materials 0.000 claims description 7
- 229910052797 bismuth Inorganic materials 0.000 claims description 6
- 239000010955 niobium Substances 0.000 claims description 6
- 150000004767 nitrides Chemical class 0.000 claims description 6
- 229910052714 tellurium Inorganic materials 0.000 claims description 6
- PORWMNRCUJJQNO-UHFFFAOYSA-N tellurium atom Chemical compound [Te] PORWMNRCUJJQNO-UHFFFAOYSA-N 0.000 claims description 6
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 5
- KJTLSVCANCCWHF-UHFFFAOYSA-N Ruthenium Chemical compound [Ru] KJTLSVCANCCWHF-UHFFFAOYSA-N 0.000 claims description 5
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims description 5
- JCXGWMGPZLAOME-UHFFFAOYSA-N bismuth atom Chemical compound [Bi] JCXGWMGPZLAOME-UHFFFAOYSA-N 0.000 claims description 5
- 229910017052 cobalt Inorganic materials 0.000 claims description 5
- 239000010941 cobalt Substances 0.000 claims description 5
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 claims description 5
- 229910052802 copper Inorganic materials 0.000 claims description 5
- 229910052707 ruthenium Inorganic materials 0.000 claims description 5
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- 239000004332 silver Substances 0.000 claims description 5
- JBQYATWDVHIOAR-UHFFFAOYSA-N tellanylidenegermanium Chemical compound [Te]=[Ge] JBQYATWDVHIOAR-UHFFFAOYSA-N 0.000 claims description 5
- 229910052758 niobium Inorganic materials 0.000 claims description 3
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 claims description 3
- 239000006096 absorbing agent Substances 0.000 claims 1
- 230000000694 effects Effects 0.000 abstract description 35
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 25
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- 238000011156 evaluation Methods 0.000 description 7
- 229910052715 tantalum Inorganic materials 0.000 description 7
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 description 7
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 6
- 239000000460 chlorine Substances 0.000 description 6
- 229910052801 chlorine Inorganic materials 0.000 description 6
- 238000005530 etching Methods 0.000 description 6
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- 238000000034 method Methods 0.000 description 6
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- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 5
- YZCKVEUIGOORGS-IGMARMGPSA-N Protium Chemical compound [1H] YZCKVEUIGOORGS-IGMARMGPSA-N 0.000 description 5
- 239000011737 fluorine Substances 0.000 description 5
- 229910052731 fluorine Inorganic materials 0.000 description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 4
- 230000006866 deterioration Effects 0.000 description 4
- 238000002149 energy-dispersive X-ray emission spectroscopy Methods 0.000 description 4
- 238000001900 extreme ultraviolet lithography Methods 0.000 description 4
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- 229910052710 silicon Inorganic materials 0.000 description 4
- 239000010703 silicon Substances 0.000 description 4
- XOLBLPGZBRYERU-UHFFFAOYSA-N tin dioxide Chemical compound O=[Sn]=O XOLBLPGZBRYERU-UHFFFAOYSA-N 0.000 description 4
- 229910001887 tin oxide Inorganic materials 0.000 description 4
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 3
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- 238000000059 patterning Methods 0.000 description 3
- 238000004544 sputter deposition Methods 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- 229910006404 SnO 2 Inorganic materials 0.000 description 2
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- 229910052735 hafnium Inorganic materials 0.000 description 2
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- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
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- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 230000002745 absorbent Effects 0.000 description 1
- 239000002250 absorbent Substances 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- CXOWYMLTGOFURZ-UHFFFAOYSA-N azanylidynechromium Chemical compound [Cr]#N CXOWYMLTGOFURZ-UHFFFAOYSA-N 0.000 description 1
- 229910052790 beryllium Inorganic materials 0.000 description 1
- ATBAMAFKBVZNFJ-UHFFFAOYSA-N beryllium atom Chemical compound [Be] ATBAMAFKBVZNFJ-UHFFFAOYSA-N 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
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- VSZWPYCFIRKVQL-UHFFFAOYSA-N selanylidenegallium;selenium Chemical compound [Se].[Se]=[Ga].[Se]=[Ga] VSZWPYCFIRKVQL-UHFFFAOYSA-N 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
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- 239000010937 tungsten Substances 0.000 description 1
Images
Classifications
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- 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
- G03F1/22—Masks or mask blanks for imaging by radiation of 100nm or shorter wavelength, e.g. X-ray masks, extreme ultraviolet [EUV] masks; Preparation thereof
- G03F1/24—Reflection masks; 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
- 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
- G03F1/26—Phase shift masks [PSM]; PSM blanks; 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
- 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
- G03F1/54—Absorbers, e.g. of opaque materials
Definitions
- the present disclosure relates to a reflective photomask blank and a reflective photomask.
- the minimum resolution dimension of a transfer pattern in photolithography largely depends on the wavelength of the exposure light source, and the shorter the wavelength, the smaller the minimum resolution dimension can be. Therefore, as the exposure light source, application of EUV (Extreme Ultra Violet) with a wavelength of 13.5 nm has started from the conventional ArF excimer laser light with a wavelength of 193 nm.
- EUV Extreme Ultra Violet
- Patent Document 1 Since most substances absorb light in the EUV region at a high rate, a reflective photomask (EUV mask) is used as a photomask for EUV exposure (see, for example, Patent Document 1).
- An EUV mask obtained by forming a layer and patterning the light absorbing layer is disclosed.
- EUV lithography cannot use a refractive optical system that utilizes the transmission of light, so the optical system members of the exposure machine are not lenses but reflective (mirrors). For this reason, there is a problem that the incident light and the reflected light to the EUV mask cannot be designed to be coaxial.
- the optical axis is inclined 6 degrees from the vertical direction of the EUV mask, and the light is incident at an angle of -6 degrees. A method of guiding the reflected light to the semiconductor substrate is adopted.
- the optical axis is tilted via a mirror, so the EUV light incident on the EUV mask casts a shadow on the mask pattern (patterned light absorption layer) of the EUV mask, a problem called projection effect. occurs.
- the absorption layer contains 50 atomic % (at %) or more of Ta as a main component, and further Te, Sb, Pt, I, Bi, Ir, Os, W, Re, Sn, In, Po , Fe, Au, Hg, Ga and Al.
- the phase shift effect is to adjust the phase of the transmitted light that has passed through the phase shift section adjacent to the opening to be opposite to the phase of the transmitted light that has passed through the opening, thereby reducing the amount of light in the portion where the transmitted light interferes with each other. It refers to the effect of weakening the intensity and, as a result, improving the transfer contrast and improving the resolution of the transfer pattern. Therefore, by using the phase shift effect also in the reflective mask blank, further improvement in transferability can be expected.
- the reflective mask blank using the phase shift effect described in Patent Document 3 limits the combination of the film thickness and material composition of the phase shift layer from the phase difference that improves the reflectance and contrast.
- Patent document 3 describes that the phase shift layer can be thinned to a thickness of 60 nm or less, and the phase shift effect can be obtained while reducing the shadowing effect.
- the film thickness is derived from the material and the target reflectance/retardation, and it is claimed that the film thickness is thinner than the conventional one, but the actual transferability is not mentioned.
- phase shift film is made of a material such as Ni or Co that absorbs a large amount of EUV, even if the film is thinner than the conventional film, the obliquely incident EUV light is strongly hindered and the transferability may not be improved.
- An object of the present invention is to provide a reflective photomask blank and a reflective photomask with high transfer performance by maximizing the phase shift effect and suppressing or reducing the influence of the projection effect.
- a reflective photomask blank for producing a reflective photomask for pattern transfer using extreme ultraviolet light as a light source.
- a substrate for reflecting incident light
- a low reflection portion formed on the reflection portion to absorb the incident light
- the low reflection portion comprising: A laminated structure of at least two layers including an absorption layer and a phase shift layer, wherein the absorption layer and the phase shift layer are laminated in this order on the reflective section, and a material constituting the absorption layer.
- the optical constant for a wavelength of 13.5 nm satisfies an extinction coefficient k>0.04, the optical constant for a wavelength of 13.5 nm of the material constituting the phase shift layer satisfies a refractive index n ⁇ 0.94, and It is characterized by satisfying an extinction coefficient k ⁇ 0.02.
- the absorbing layer in the reflective photomask blank includes tellurium (Te), cobalt (Co), nickel (Ni), platinum (Pt), silver (Ag), tin (Sn), A total of 50 atoms and molecules of at least one kind selected from the group consisting of indium (In), copper (Cu), zinc (Zn), bismuth (Bi) and their oxides, nitrides and oxynitrides It is preferable if the content is atomic % or more.
- phase shift layer in the reflective photomask blank includes molybdenum (Mo), ruthenium (Ru), niobium (Nb), and the group consisting of oxides, nitrides, and oxynitrides thereof. It is preferable that the total content of at least one kind of atoms and molecules selected from the group is 50 atomic % or more.
- the low-reflection portion composed of the absorption layer and the phase shift layer has a phase difference of 160 to 200 degrees with respect to the reflection portion, and the It is preferable if the reflectance is 1% to 40% depending on the film thickness ratio of the absorption layer and the phase shift layer.
- a reflective photomask is a reflective photomask for pattern transfer using extreme ultraviolet rays as a light source, and includes a substrate and a reflective photomask formed on the substrate to reflect incident light. and a low-reflection portion formed on the reflection portion to absorb incident light, wherein the low-reflection portion is a laminated structure of at least two layers including an absorption layer and a phase shift layer.
- the absorption layer and the phase shift layer are laminated in this order on the reflection part, and the optical constant of the material constituting the absorption layer at a wavelength of 13.5 nm is an extinction coefficient k>0.04. and the optical constant for a wavelength of 13.5 nm of the material constituting the phase shift layer satisfies a refractive index n ⁇ 0.94 and an extinction coefficient k ⁇ 0.02.
- a reflective photomask according to an aspect of the present disclosure and a reflective photomask blank for manufacturing the same provide a reflective photomask and a reflective photomask having high transfer performance while suppressing the projection effect. It becomes possible to provide a mask blank.
- FIG. 1 is a cross-sectional view schematically showing one configuration example of a reflective photomask blank according to the present embodiment
- FIG. 1 is a cross-sectional view schematically showing one configuration example of a reflective photomask according to the present embodiment
- FIG. 4 is a graph showing the optical constants of each metal at the wavelength of EUV light
- 1A to 1D are schematic cross-sectional views showing manufacturing steps of a reflective photomask according to the present embodiment
- 1A to 1D are schematic cross-sectional views showing manufacturing steps of a reflective photomask according to the present embodiment
- 1A to 1D are schematic cross-sectional views showing manufacturing steps of a reflective photomask according to the present embodiment
- 1A to 1D are schematic cross-sectional views showing manufacturing steps of a reflective photomask according to the present embodiment
- 1A to 1D are schematic cross-sectional views showing manufacturing steps of a reflective photomask according to the present embodiment
- 1A to 1D are schematic cross-sectional views showing manufacturing steps of a reflective photomask
- FIG. 1 is a schematic cross-sectional view showing a reflective photomask blank 100 according to an embodiment of the invention.
- FIG. 2 is a schematic cross-sectional view showing a reflective photomask 200 according to an embodiment of the present invention.
- the reflective photomask 200 according to the embodiment of the present invention shown in FIG. 2 is formed by patterning the low reflection portion 18 of the reflective photomask blank 100 according to the embodiment of the present invention shown in FIG. be.
- a reflective photomask blank 100 includes a substrate 11, a reflective portion 17 formed on the substrate 11, and a low reflective portion formed on the reflective portion 17. 18.
- the reflective photomask blank 100 also includes the multilayer reflective film 12 and the capping layer 13 in the reflective portion 17 , and the absorbing layer 14 and the phase shift layer 15 in the low reflective portion 18 . That is, the reflective photomask 200 has a multilayer reflective film 12, a capping layer 13, an absorption layer 14, and a phase shift layer 15 laminated in this order on one side of a substrate 11. FIG. Each layer will be described in detail below.
- the substrate 11 is a layer that serves as a base material of the reflective photomask blank 100 .
- a flat Si substrate, a synthetic quartz substrate, or the like can be used as the substrate 11 according to the embodiment of the present invention.
- the substrate 11 can be made of titanium-added low-thermal-expansion glass, but the present invention is not limited to this as long as the material has a small thermal expansion coefficient.
- a back conductive film 16 can be formed on the surface of the substrate 11 on which the multilayer reflective film 12 is not formed.
- the back conductive film 16 is a film for fixing the reflective photomask blank 100 using the principle of an electrostatic chuck when the reflective photomask blank 100 is installed in the exposure machine.
- the reflective portion 17 is formed on the substrate 11 and provided to reflect light incident on the reflective photomask blank 100 .
- the reflective portion 17 includes a multilayer reflective film 12 and a capping layer 13 .
- the multilayer reflective film 12 is a layer formed on the substrate 11 and is a layer provided for reflecting EUV light (extreme ultraviolet light), which is exposure light, in the reflective photomask blank 100 .
- the multilayer reflective film 12 is composed of a plurality of reflective films made of a combination of materials having greatly different refractive indices with respect to EUV light.
- the multilayer reflective film 12 can be formed by repeatedly stacking a combination of Mo (molybdenum) and Si (silicon) or Mo (molybdenum) and Be (beryllium) about 40 cycles.
- the capping layer 13 is a layer formed on the multilayer reflective film 12, and functions as an etching stopper for preventing damage to the multilayer reflective film 12 when the absorption layer pattern is dry-etched.
- the capping layer 13 according to the embodiment of the present invention is made of a material that is resistant to dry etching performed during pattern formation of the absorbing layer 14 .
- capping layer 13 is typically applied with ruthenium (Ru).
- Ru ruthenium
- the low-reflection portion 18 is a layer formed on the reflection portion 17 and provided in the reflective photomask blank 100 to absorb EUV light, which is exposure light.
- the low reflection portion 18 has an absorption layer 14 and a phase shift layer 15 .
- the low reflection portion 18 is composed of at least two layers, one of which is the absorption layer 14 and the phase shift layer 15 is provided on the absorption layer 14 .
- the absorption layer 14 is a layer formed on the capping layer 13 and is a layer composed of at least one layer.
- the absorption layer 14 is a layer for forming an absorption layer pattern (transfer pattern), which is a fine pattern for transfer.
- the absorption pattern (absorption layer pattern) of the reflective photomask 200 is formed by removing a portion of the absorption layer 14 of the reflective photomask blank, that is, by patterning the absorption layer 14 . be done.
- EUV lithography EUV light is obliquely incident and reflected by the reflecting portion 17, but the low-reflecting portion pattern 18a impedes the optical path, resulting in a projection effect that degrades transfer performance onto a wafer (semiconductor substrate). There is This deterioration in transfer performance can be reduced by reducing the thickness of the absorption layer 14 that absorbs EUV light.
- a material that has a higher absorption of EUV light than conventional materials that is, a material that has a high extinction coefficient k for a wavelength of 13.5 nm. preferable.
- FIG. 3 is a graph showing the optical constants of each metal material with respect to the EUV light wavelength of 13.5 nm.
- the horizontal axis of the graph in FIG. 3 represents the refractive index n, and the vertical axis represents the extinction coefficient k.
- the extinction coefficient k of tantalum (Ta) which is the main material of the conventional absorption layer 14, is 0.041. If the main material of the absorption layer 14 is a compound material having an extinction coefficient k larger than that of tantalum (Ta), the thickness of the absorption layer 14 can be made thinner than in the prior art, and the projection effect can be reduced. . Note that if the extinction coefficient k is 0.06 or more, the thickness of the absorption layer 14 can be made sufficiently thin, and the projection effect can be reduced.
- Materials having an extinction coefficient k of 0.041 or more as described above include silver (Ag), platinum (Pt), indium (In), cobalt (Co), tin (Sn), as shown in FIG. , nickel (Ni), tellurium (Te), copper (Cu), zinc (Zn) and bismuth (Bi). Therefore, materials for the absorption layer 14 include tellurium (Te), cobalt (Co), nickel (Ni), platinum (Pt), silver (Ag), tin (Sn), indium (In), copper (Cu), The total content of at least one element selected from the group consisting of zinc (Zn), bismuth (Bi), and their oxides, nitrides, and oxynitrides is preferably 50 atomic % or more.
- the absorption layer 14 in the reflective photomask blank must be easily patterned.
- tin oxide is known to be dry-etchable with a chlorine-based gas.
- tin (Sn) alone has a low melting point and poor thermal stability, but tin oxide is known to increase the melting point. Therefore, in this embodiment, the absorption layer 14 preferably contains tin (Sn) and oxygen (O).
- the material of the absorption layer 14 is an absorption material with high resistance to hydrogen radicals.
- a material with a film reduction rate of 0.1 nm / s or less under a hydrogen radical environment with a power of 1 kW and a hydrogen pressure of 0.36 mbar or less is treated with a material having a high hydrogen radical resistance.
- tin (Sn) alone has low resistance to hydrogen radicals, but the addition of oxygen increases the resistance to hydrogen radicals. Specifically, hydrogen radical resistance was confirmed in materials in which the atomic ratio of tin (Sn) and oxygen (O) exceeded 1:2.
- atomic ratio of tin (Sn) and oxygen (O) is 1: 2 or less, not all bonds of tin become tin oxide (SnO 2 ) . : atomic number ratio greater than 2 is required.
- the above atomic number ratio is the result of measuring a material deposited with a film thickness of 1 ⁇ m by EDX (energy dispersive X-ray spectroscopy).
- the material containing tin (Sn) and oxygen (O) for forming the absorption layer 14 preferably contains more oxygen than stoichiometric tin oxide (SnO 2 ). That is, the atomic ratio of tin (Sn) and oxygen (O) in the material of the absorption layer preferably exceeds 1:2. Further, the atomic ratio of tin (Sn) and oxygen (O) is preferably less than 1:4, more preferably 1:3.5 or less. When the atomic ratio of tin (Sn) and oxygen (O) is 1:3.5 or less, it is possible to suppress a decrease in absorption of the absorption layer 14 .
- the material of the absorption layer 14 preferably contains tin (Sn) and oxygen (O) in a total amount of 50 atomic % or more. This is because if the absorption layer contains components other than tin (Sn) and oxygen (O), the EUV light absorbability and hydrogen radical resistance may decrease. For example, the deterioration in EUV light absorbability and resistance to hydrogen radicals is very slight, and there is almost no deterioration in performance as the absorption layer 14 of the EUV mask.
- Materials other than tin (Sn) and oxygen (O) for the absorption layer 14 include tantalum (Ta), platinum (Pt), tellurium (Te), zirconium (Zr), hafnium (Hf), titanium (Ti), and tungsten.
- W silicon (Si), chromium (Cr), indium (In), palladium (Pd), nickel (Ni), fluorine (F), nitrogen (N), carbon (C) and hydrogen (H) mixed may have been
- indium (In) the film can have electrical conductivity while ensuring high absorption. This makes it possible to improve the inspectability in mask pattern inspection using DUV (Deep Ultraviolet) light with a wavelength of 190 to 260 nm.
- DUV Deep Ultraviolet
- the film quality is made more amorphous in order to improve the roughness of the absorption layer pattern after dry etching, the in-plane dimensional uniformity, and the in-plane uniformity of the transferred image. becomes possible.
- the phase shift layer 15 is a layer formed on the absorption layer 14, and is a layer provided for obtaining high resolution by exhibiting a phase shift effect by changing the phase of incident light.
- the phase shift effect is that the phase of transmitted light that has passed through the phase shift layer 15 is adjusted to be opposite to the phase of transmitted light that has not passed through the phase shift layer 15, thereby reducing the portion where the transmitted light interferes with each other. It refers to the effect of weakening the light intensity and, as a result, improving the transfer contrast and improving the resolution of the transfer pattern.
- the phase shift layer 15 is formed into a phase shift pattern (phase shift layer pattern) by removing part of the phase shift layer 15 in the same manner as the absorption layer 14 .
- a phase shift layer pattern phase shift layer pattern
- an absorption layer 14 and a phase shift layer 15 are stacked in this order on the reflective portion.
- the phase shift layer 15 preferably has a refractive index n ⁇ 1, more preferably a refractive index n ⁇ 0.94.
- n of the phase shift layer 15 is smaller than the vacuum refractive index 1, it becomes easier to adjust the phase difference by changing the film thickness.
- the thickness of the phase shift layer 15 is increased, the thickness of the entire low reflection portion 18 is increased, and the shadowing effect deteriorates the resolution.
- the material of the phase shift layer 15 a material that can be etched with a fluorine-based gas or a chlorine-based gas is preferable because the phase shift layer 15 is patterned.
- the material of the phase shift layer 15 is preferably a material having an extinction coefficient k ⁇ 0.02 so as not to affect the shadowing effect.
- the material of the phase shift layer 15 includes molybdenum (Mo), ruthenium (Ru), niobium (Nb), and at least one element selected from oxides, nitrides, and oxynitrides thereof. It is preferable to contain In order not to lower the etching rate, it is desirable that the phase shift layer 15 is made of a material containing at least 50% of the above material.
- the absorption layer 14 contains tin or indium (In) that can be etched with a chlorine gas
- molybdenum (Mo) that can be etched with a chlorine-based gas can be suitably selected for the phase shift layer 15 as well.
- the low-reflection portion 18 including the absorption layer 14 and the phase shift layer 15 described above has a phase difference of 160 to 200 degrees with respect to the reflection portion 17, and the thickness ratio of the absorption layer 14 and the phase shift layer 15 is It is preferred to have a corresponding reflectance of 1% to 40%.
- the low reflection portion 18 has a phase difference of 170 to 190 degrees with respect to the reflection portion 17, and has a reflectance of 10% to 40% according to the film thickness ratio between the absorption layer 14 and the phase shift layer 15. is more preferable.
- FIG. 4 As shown in FIG. 4, a positive chemically amplified resist (SEBP9012: manufactured by Shin-Etsu Chemical Co., Ltd.) was spin-coated to a film thickness of 120 nm on the low-reflection portion 18 provided in the reflective photomask blank 100. A film was formed. Thereafter, baking was performed at 110° C. for 10 minutes to form a resist film 19 as shown in FIG. Next, a predetermined pattern was drawn on the resist film 19 formed of a positive chemically amplified resist by an electron beam lithography machine (JBX3030, manufactured by JEOL Ltd.). Thereafter, baking treatment was performed at 110° C. for 10 minutes, followed by spray development (SFG3000: manufactured by Sigma Meltec Co., Ltd.). Thereby, a resist pattern 19a was formed as shown in FIG.
- SEBP9012 manufactured by Shin-Etsu Chemical Co., Ltd.
- the phase shift layer 15 was patterned by dry etching mainly using a fluorine-based gas to form a phase shift layer pattern.
- the absorption layer 14 was patterned by dry etching mainly using a chlorine-based gas to form an absorption layer pattern.
- a low-reflection portion pattern 18a including a phase shift layer pattern and an absorption layer pattern was formed.
- the low-reflection pattern 18a formed in the low-reflection portion 18 is a LS (line and space) pattern with a line width of 100 nm on the reflective photomask 200 for transfer evaluation, and is used for measuring the film thickness of the absorption layer using an AFM. 200 nm line width LS pattern, and a 4 mm square low-reflection part removal part for EUV reflectance measurement.
- the line width 100 nm LS pattern is designed in both the x direction and the y direction as shown in FIG.
- the low-reflection portion pattern of Example 1 was a 64 nm LS (line and space) pattern with a line width on a reflective photomask for evaluation of transfer, a 200 nm LS pattern with a line width for measuring the thickness of the absorption layer using AFM, It includes a 4 mm square low reflectance removal part for EUV reflectance measurement.
- This line width 64 nm LS pattern was designed in the x direction and the y direction so that the influence of the projection effect due to oblique irradiation of EUV can be easily seen.
- the reflective photomask blank 100 and the reflective photomask 200 according to this embodiment have the following effects.
- the optical constant of the material forming the phase shift layer 15 at a wavelength of 13.5 nm satisfies the refractive index n ⁇ 0.94 and the extinction coefficient k ⁇ 0. 02. According to this configuration, it is easy to adjust the phase difference by the film thickness, and the projection effect can be reduced.
- a synthetic quartz substrate having low thermal expansion was used as the substrate.
- a multi-layer reflective film was formed by laminating 40 laminated films each having a pair of silicon (Si) and molybdenum (Mo) on a substrate.
- the film thickness of the multilayer reflective film was set to 280 nm.
- ruthenium (Ru) was used to form a capping layer with a thickness of 3.5 nm on the multilayer reflective film.
- a reflective portion having a multilayer reflective film and a capping layer was formed on the substrate.
- An absorbing layer containing tin (Sn) and oxygen (O) was deposited on the capping layer.
- the film thickness of the absorption layer was set to 17 nm.
- the atomic number ratio of tin (Sn) and oxygen (O) was 1:2.5 as measured by EDX (energy dispersive X-ray spectroscopy). Further, when measured by XRD (X-ray diffraction device), it was found to be amorphous although slight crystallinity was observed.
- a phase shift layer with a thickness of 28 nm was formed on the absorption layer using molybdenum (Mo).
- Mo molybdenum
- a 45 nm-thick low-reflection portion was formed in which the absorption layer and the phase shift layer were laminated in this order on the reflection layer.
- the phase difference of the low reflection portion with respect to the reflection portion was set to 180 degrees.
- a 100 nm-thick back conductive film was formed using chromium nitride (CrN) on the side of the substrate on which the multilayer reflective film was not formed.
- CrN chromium nitride
- a reflective photomask blank was produced.
- a multi-source sputtering apparatus was used to form each film on the substrate. The film thickness of each film was controlled by the sputtering time.
- the absorption layer was formed by a reactive sputtering method so that the O/Sn ratio was 2.5 by controlling the amount of oxygen introduced into the chamber during
- a positive chemically amplified resist (SEBP9012: manufactured by Shin-Etsu Chemical Co., Ltd.) was spin-coated on the low-reflection portion to a film thickness of 120 nm, and baked at 110 degrees for 10 minutes to form a resist film. .
- a predetermined pattern was drawn on the positive chemically amplified resist using an electron beam drawing machine (JBX3030: manufactured by JEOL Ltd.). Thereafter, pre-baking treatment was performed at 110° C. for 10 minutes, and then development treatment was performed using a spray developing machine (SFG3000: manufactured by Sigma Meltec Co., Ltd.). A resist pattern was thus formed.
- the phase shift layer was patterned by dry etching mainly using a fluorine-based gas.
- the absorption layer was patterned by dry etching mainly using a chlorine-based gas to form an absorption layer pattern.
- a low reflection portion pattern was formed in which the absorption layer pattern and the phase shift layer pattern were laminated in this order in the low reflection portion.
- the remaining resist pattern was removed.
- a reflective photomask of Example 1 was produced. Note that the lamination of the absorption layer and the phase shift layer (that is, the low reflection portion) had a reflectance of 5% for EUV light with a wavelength of 13.5 nm.
- Example 2 The reflectance of the lamination of the absorption layer and the phase shift layer was changed to 10%. In order to obtain a reflectance of 10%, the film thickness of the absorption layer was changed to 9 nm, and the film thickness of the phase shift layer was changed to 36 nm. A reflective photomask of Example 2 was produced in the same manner as in Example 1 except for the above.
- Example 5 The material of the absorption layer was changed to cobalt (Co) and oxygen (O).
- a reflective photomask of Example 5 was produced in the same manner as in Example 1 except for the above.
- Example 6> The material of the absorption layer was changed to nickel (Ni) and oxygen (O).
- a reflective photomask of Example 6 was produced in the same manner as in Example 1 except for the above.
- Example 7> The material of the absorbing layer was changed to platinum (Pt).
- a reflective photomask of Example 7 was produced in the same manner as in Example 1 except for the above.
- Example 8> The material of the absorption layer was changed to silver (Ag) and oxygen (O). A reflective photomask of Example 8 was produced in the same manner as in Example 1 except for the above.
- Example 9> The material of the absorption layer was changed to indium (In) and oxygen (O). A reflective photomask of Example 9 was produced in the same manner as in Example 1 except for the above.
- Example 10> The material of the absorption layer was changed to copper (Cu) and oxygen (O).
- a reflective photomask of Example 10 was produced in the same manner as in Example 1 except for the above.
- Example 11 The material of the absorption layer was changed to zinc (Zn) and oxygen (O). A reflective photomask of Example 11 was produced in the same manner as in Example 1 except for the above.
- Example 12 The material of the absorption layer was changed to bismuth (Bi) and oxygen (O). A reflective photomask of Example 12 was produced in the same manner as in Example 1 except for the above.
- Example 13 The material of the absorption layer was changed to iron (Fe) and oxygen (O).
- a reflective photomask of Example 13 was produced in the same manner as in Example 1 except for the above.
- Example 14> The material of the phase shift layer was changed to carbon (C).
- a reflective photomask of Example 14 was produced in the same manner as in Example 1 except for the above.
- Example 15> The phase difference of the low reflection portion with respect to the reflection portion was set to 155 degrees.
- a reflective photomask of Example 15 was produced in the same manner as in Example 1 except for the above.
- Example 16> The reflectance of the lamination of the absorption layer and the phase shift layer was changed to 35%.
- a reflective photomask of Example 16 was produced in the same manner as in Example 1 except for the above.
- ⁇ Comparative Example 1> In the preparation of the reflective photomask blank, a phase shift layer with a thickness of 24 nm was formed on the capping layer using molybdenum (Mo). Next, an absorption layer containing tin (Sn) and oxygen (O) was formed on the phase shift layer. The film thickness of the absorption layer was set to 21 nm. That is, a 45 nm-thick low-reflection portion was formed by laminating a phase shift layer and an absorption layer in this order on a reflective layer.
- Mo molybdenum
- O oxygen
- the absorption layer was patterned by dry etching mainly using a chlorine-based gas using the resist pattern as an etching mask to form the absorption layer pattern.
- the phase shift layer was patterned by dry etching mainly using a fluorine-based gas. That is, a low reflection portion pattern was formed by laminating a phase shift layer pattern and an absorption layer pattern in this order in the low reflection portion.
- a reflective photomask of Comparative Example 1 was produced in the same manner as in Example 1 except for the above.
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Abstract
Description
このように、EUVリソグラフィではミラーを介し光軸を傾斜することから、EUVマスクに入射するEUV光がEUVマスクのマスクパターン(パターン化された光吸収層)の影をつくる、射影効果と呼ばれる問題が発生する。
ここで、図面に示す構成は模式的なものであり、厚さと平面寸法との関係、各層の厚さの比率などは現実のものとは異なる。また、以下に示す実施形態は、本開示の技術的思想を具体化するための構成を例示するものであって、本開示の技術的思想は、構成部品の材質、形状、構造などが下記のものに限定されるものでない。本開示の技術的思想は、特許請求の範囲に記載された請求項が規定する技術的範囲内において、種々の変更を加えることができる。
本開示の実施形態に係る反射型フォトマスクブランクの基本構成について、図1を用いて説明する。
図1に示すように、本開示の一実施形態に係る反射型フォトマスクブランク100は、基板11と、基板11上に形成された反射部17と、反射部17上に形成された低反射部18とを備えている。また、反射型フォトマスクブランク100は、反射部17において多層反射膜12と、キャッピング層13とを備えており、低反射部18において吸収層14と、位相シフト層15とを備えている。すなわち、反射型フォトマスク200は、基板11の一方の面側に、多層反射膜12、キャッピング層13、吸収層14、及び位相シフト層15がこの順に積層されている。以下、各層について詳細に説明する。
基板11は、反射型フォトマスクブランク100の基材となる層である。本発明の実施形態に係る基板11には、平坦なSi基板や合成石英基板等を用いることができる。また、基板11には、チタンを添加した低熱膨張ガラスを用いることができるが、熱膨張率の小さい材料であれば、本発明ではこれらに限定されるものではない。
また、図4に示すように、基板11の多層反射膜12を形成していない面に裏面導電膜16を形成することができる。裏面導電膜16は、反射型フォトマスクブランク100を露光機に設置するときに静電チャックの原理を利用して固定するための膜である。
反射部17は、基板11上に形成され、反射型フォトマスクブランク100に入射した光を反射するために設けられている。反射部17は、多層反射膜12と、キャッピング層13とを備えている。
多層反射膜12は、基板11上に形成される層であり、反射型フォトマスクブランク100において露光光であるEUV光(極端紫外光)を反射するために設けられた層である。
多層反射膜12は、EUV光に対する屈折率の大きく異なる材料の組み合わせによる複数の反射膜から構成されている。例えば、多層反射膜12は、Mo(モリブデン)とSi(シリコン)、またはMo(モリブデン)とBe(ベリリウム)といった組み合わせの層を40周期程度繰り返し積層することにより形成することができる。
キャッピング層13は、多層反射膜12上に形成される層であり、吸収層パターンをドライエッチングする際に、多層反射膜12へのダメージを防ぐエッチングストッパとして機能する層である。本発明の実施形態に係るキャッピング層13は、吸収層14のパターン形成の際に行われるドライエッチングに対して耐性を有する材質で形成されている。例えば、キャッピング層13は一般的にルテニウム(Ru)が適用される。なお、多層反射膜12の材質やエッチング条件により、キャッピング層13はなくてもかまわない。
低反射部18は、反射部17上に形成され、反射型フォトマスクブランク100において露光光であるEUV光を吸収するために設けられた層である。低反射部18は、吸収層14と、位相シフト層15とを備えている。なお、低反射部18は少なくとも二層以上で構成されており、そのうちの一層を吸収層14とし、吸収層14上に位相シフト層15を備えている。
吸収層14は、キャッピング層13上に形成される層であり、少なくとも1層以上で構成される層である。また、吸収層14は、転写するための微細パターンである吸収層パターン(転写パターン)を形成する層である。
図2に示すように、反射型フォトマスクブランクの吸収層14の一部を除去することにより、即ち吸収層14をパターニングすることにより、反射型フォトマスク200の吸収パターン(吸収層パターン)が形成される。EUVリソグラフィにおいて、EUV光は斜めに入射し、反射部17で反射されるが、低反射部パターン18aが光路の妨げとなる射影効果により、ウェハ(半導体基板)上への転写性能が悪化することがある。この転写性能の悪化は、EUV光を吸収する吸収層14の厚さを薄くすることで低減される。
低反射部18の厚さを薄くするためには、従来の材料よりEUV光に対する吸収性の高い材料、つまり波長13.5nmに対する消衰係数kの高い材料を低反射部18に適用することが好ましい。
また、吸収層14の材料は、錫(Sn)及び酸素(O)を合計で50原子%以上含有することが好ましい。これは、吸収層に錫(Sn)と酸素(O)以外の成分が含まれているとEUV光吸収性と水素ラジカル耐性が低下する可能性があるものの、その成分が50原子%未満であれば、EUV光吸収性と水素ラジカル耐性の低下はごく僅かであり、EUVマスクの吸収層14としての性能の低下はほとんど無いためである。
位相シフト層15は、吸収層14上に形成される層であり、入射光の位相を変化させることにより位相シフト効果を発現して高い解像性を得るために設けられた層である。位相シフト効果とは、位相シフト層15を通過した透過光の位相が、位相シフト層15を通過していない透過光の位相と反転するように調整することによって、透過光が干渉し合う部分の光強度を弱め、その結果として、転写コントラストが向上し、転写パターンの解像性を向上させる効果のことをいう。
本実施形態では、反射型フォトマスクにおいて、反射部の上に吸収層14と位相シフト層15とがこの順に積層されている。吸収層14の上層に、吸収の小さい位相シフト層15を形成することにより、シャドウイング効果を最小限に抑え、位相シフト効果を発現し、高い解像性を得ることができる。
上述した吸収層14と位相シフト層15とを備える低反射部18は、反射部17に対して位相差160~200度を有し、且つ吸収層14と位相シフト層15との膜厚比に応じた反射率1%~40%を有することが好ましい。なお、低反射部18は、反射部17に対して位相差170~190度を有し、且つ吸収層14と位相シフト層15との膜厚比に応じた反射率10%~40%を有することがより好ましい。
次に、反射型フォトマスクの製造方法について図4から図8を用いて説明する。
図4に示すように、反射型フォトマスクブランク100に備えられた低反射部18の上に、ポジ型化学増幅型レジスト(SEBP9012:信越化学工業株式会社製)を120nmの膜厚にスピンコートで成膜した。その後、110℃で10分間ベークし、図5に示すように、レジスト膜19を形成した。
次いで、電子線描画機(JBX3030:日本電子株式会社製)によってポジ型化学増幅型レジストで形成されたレジスト膜19に所定のパターンを描画した。その後、110℃、10分間ベーク処理を施し、次いでスプレー現像(SFG3000:シグマメルテック株式会社製)した。これにより、図6に示すように、レジストパターン19aを形成した。
次に、塩素系ガスを主体としたドライエッチングにより吸収層14のパターニングを行い、吸収層パターンを形成した。これにより、位相シフト層パターン及び吸収層パターンを備える低反射部パターン18aが形成された。
本実施形態に係る反射型フォトマスクブランク100及び反射型フォトマスク200は、以下の効果を有する。
(1)本実施形態の反射型フォトマスクブランク100において、反射部17の上に吸収層14と、位相シフト層15とがこの順番で積層されている。
この構成によれば、射影効果を最小限に抑え、位相シフトの効果を発現し、高い解像性を得ることができる。
(2)本実施形態の反射型フォトマスクブランク100において、吸収層14の波長13.5nmに対する消衰係数kは、k>0.04である。
この構成によれば、従来の材料よりEUV光に対する吸収性の高い材料を用いることにより、低反射部18を薄膜化でき、射影効果を低減できる。
(3)本実施形態の反射型フォトマスクブランク100において位相シフト層15を構成する材料の波長13.5nmに対する光学定数は、屈折率n<0.94を満たし、且つ消衰係数k<0.02を満たす。
この構成によれば、膜厚による位相差の調節がしやすく、射影効果を低減できる。
基板として低熱膨張性を有する合成石英基板を用いた。基板の上に、シリコン(Si)とモリブデン(Mo)とを一対とする積層膜を40枚積層して多層反射膜を形成した。多層反射膜の膜厚は280nmとした。
次に、多層反射膜上に、ルテニウム(Ru)を用いて膜厚3.5nmのキャッピング層を成膜した。これにより、基板上には多層反射膜及びキャッピング層を有する反射部が形成された。
キャッピング層の上に、錫(Sn)と酸素(O)とを含む吸収層を成膜した。吸収層の膜厚は17nmとした。錫(Sn)と酸素(O)との原子数比率は、EDX(エネルギー分散型X線分析)で測定したところ1:2.5であった。また、XRD(X線回析装置)で測定したところ、わずかに結晶性が見られるものの、アモルファスであることが分かった。
次に、基板の多層反射膜が形成されていない側に、窒化クロム(CrN)を用いて膜厚100nmの裏面導電膜を成膜した。以上により、反射型フォトマスクブランクを作製した。
基板上へのそれぞれの膜の成膜は、多元スパッタリング装置を用いた。各々の膜の膜厚は、スパッタリング時間で制御した。吸収層は、反応性スパッタリング法により、スパッタリング中にチャンバーに導入する酸素の量を制御することで、O/Sn比が2.5になるように成膜した。
次いで、電子線描画機(JBX3030:日本電子株式会社製)によってポジ型化学増幅型レジストに所定のパターンを描画した。
その後、110度で10分間プリベーク処理を施し、次いでスプレー現像機(SFG3000:シグマメルテック株式会社製)を用いて現像処理をした。これによりレジストパターンを形成した。
次に、塩素系ガスを主体としたドライエッチングにより吸収層のパターニングを行い、吸収層パターンを形成した。これにより、低反射部において吸収層パターンと、位相シフト層パターンとがこの順に積層された低反射部パターンが形成された。
次に、残ったレジストパターンの剥離を行った。以上により、実施例1の反射型フォトマスクを作製した。
なお、吸収層と位相シフト層の積層(即ち、低反射部)は、波長13.5nmのEUV光に対して反射率が5%であった。
吸収層と位相シフト層との積層の反射率を10%に変更した。なお10%の反射率を得るために、吸収層の膜厚を9nmに変更し、位相シフト層の膜厚を36nmに変更した。それ以外は実施例1と同様の方法で、実施例2の反射型フォトマスクを作製した。
<実施例3>
吸収層と位相シフト層との積層の反射率を15%に変更した。なお15%の反射率を得るために、吸収層の膜厚を8nmに変更し、位相シフト層の膜厚を37nmに変更した。それ以外は実施例1と同様の方法で、実施例3の反射型フォトマスクを作製した。
<実施例4>
吸収層の材料をテルル(Te)と酸素(O)に変更した。それ以外は実施例1と同様の方法で、実施例4の反射型フォトマスクを作製した。
吸収層の材料をコバルト(Co)と酸素(O)に変更した。それ以外は実施例1と同様の方法で、実施例5の反射型フォトマスクを作製した。
<実施例6>
吸収層の材料をニッケル(Ni)と酸素(O)に変更した。それ以外は実施例1と同様の方法で、実施例6の反射型フォトマスクを作製した。
<実施例7>
吸収層の材料をプラチナ(Pt)に変更した。それ以外は実施例1と同様の方法で、実施例7の反射型フォトマスクを作製した。
吸収層の材料を銀(Ag)と酸素(O)に変更した。それ以外は実施例1と同様の方法で、実施例8の反射型フォトマスクを作製した。
<実施例9>
吸収層の材料をインジウム(In)と酸素(O)に変更した。それ以外は実施例1と同様の方法で、実施例9の反射型フォトマスクを作製した。
<実施例10>
吸収層の材料を銅(Cu)と酸素(O)に変更した。それ以外は実施例1と同様の方法で、実施例10の反射型フォトマスクを作製した。
吸収層の材料を亜鉛(Zn)と酸素(O)に変更した。それ以外は実施例1と同様の方法で、実施例11の反射型フォトマスクを作製した。
<実施例12>
吸収層の材料をビスマス(Bi)と酸素(O)に変更した。それ以外は実施例1と同様の方法で、実施例12の反射型フォトマスクを作製した。
<実施例13>
吸収層の材料を鉄(Fe)と酸素(O)に変更した。それ以外は実施例1と同様の方法で、実施例13の反射型フォトマスクを作製した。
位相シフト層の材料を炭素(C)に変更した。それ以外は実施例1と同様の方法で、実施例14の反射型フォトマスクを作製した。
<実施例15>
反射部に対する低反射部の位相差は155度とした。それ以外は実施例1と同様の方法で、実施例15の反射型フォトマスクを作製した。
<実施例16>
吸収層と位相シフト層との積層の反射率を35%に変更した。それ以外は実施例1と同様の方法で、実施例16の反射型フォトマスクを作製した。
反射型フォトマスクブランクの作製において、キャッピング層の上に、モリブデン(Mo)を用いて膜厚24nmの位相シフト層を成膜した。次に、位相シフト層上に、錫(Sn)と酸素(O)とを含む吸収層を成膜した。吸収層の膜厚は21nmとした。すなわち、反射層上に位相シフト層と、吸収層とがこの順番に積層された厚さ45nmの低反射部を形成した。
また、反射型フォトマスクの作製において、レジストパターン形成後に、レジストパターンをエッチングマスクとして、塩素系ガスを主体としたドライエッチングにより吸収層のパターニングを行い、吸収層パターンを形成した。
次に、フッ素系ガスを主体としたドライエッチングにより位相シフト層のパターニングを行った。すなわち、低反射部において位相シフト層パターンと、吸収層パターンとがこの順に積層された低反射部パターンを形成した。それ以外は実施例1と同様の方法で、比較例1の反射型フォトマスクを作製した。
上述した実施例1から16、比較例1、で得られた反射型フォトマスクについて、以下の方法で射影効果の影響及び転写性能の評価を行った。また、転写性能はウェハ露光評価により確認した。
実施例1から16と比較例1において、転写パターンの光強度分布から明部と暗部の傾きを示す特性値であるNILS(Normalized Image Log Slope)の値を算出した。なお、NILSの値が大きい方が、射影効果の影響をより低減できる。
EUV露光装置(NXE3300B:ASML社製)を用いて、EUVポジ型化学増幅型レジストを塗布した半導体ウェハ上に、各実施例、比較例及び参考例で作製した反射型フォトマスクの吸収層パターンを転写露光した。このとき、露光量は、x方向のLSパターンが設計通りに転写するように調節した。その後、電子線寸法測定機により転写されたレジストパターンの観察及び線幅測定を実施し、解像性とH-Vバイアスを確認した。
以上の評価結果を表1に示す。
12:多層反射膜
13:キャッピング層
14:吸収層
15:位相シフト層
16:裏面導電膜
17:反射部
18:低反射部
18a:低反射部パターン
19:レジスト膜
19a:レジストパターン
100:反射型フォトマスクブランク
200:反射型フォトマスク
Claims (5)
- 極端紫外線を光源としたパターン転写用の反射型フォトマスクを作製するための反射型フォトマスクブランクであって、
基板と、
前記基板上に形成されて入射した光を反射する反射部と、
前記反射部の上に形成されて入射した光を吸収する低反射部と、を備え、
前記低反射部は、吸収層と位相シフト層とを備える少なくとも2層以上の積層構造体であり、
前記反射部の上に前記吸収層と、前記位相シフト層とがこの順番で積層され、
前記吸収層を構成する材料の波長13.5nmに対する光学定数は、消衰係数k>0.041を満たし、
前記位相シフト層を構成する材料の波長13.5nmに対する光学定数は、屈折率n<0.94を満たし、且つ消衰係数k<0.02を満たすことを特徴とする反射型フォトマスクブランク。 - 前記吸収層は、テルル(Te)、コバルト(Co)、ニッケル(Ni)、プラチナ(Pt)、銀(Ag)、錫(Sn)、インジウム(In)、銅(Cu)、亜鉛(Zn)、及びビスマス(Bi)、並びにそれらの酸化物、窒化物、及び酸窒化物からなる群より選択される少なくとも一種類の元素を合計して50原子%以上含有することを特徴とする請求項1に記載の反射型フォトマスクブランク。
- 前記位相シフト層は、モリブデン(Mo)、ルテニウム(Ru)、及びニオブ(Nb)、並びにそれらの酸化物、窒化物、及び酸窒化物からなる群より選択される少なくとも一種類の原子、分子元素を合計して50原子%以上含有することを特徴とする請求項1または請求項2に記載の反射型フォトマスクブランク。
- 前記吸収層と前記位相シフト層とを備える前記低反射部は、前記反射部に対して位相差160~200度を有し、且つ前記吸収層と前記位相シフト層との膜厚比に応じた反射率1%~40%を有することを特徴とする請求項1から請求項3のいずれか1項に記載の反射型フォトマスクブランク。
- 極端紫外線を光源としたパターン転写用の反射型フォトマスクであって、
基板と、
前記基板上に形成されて入射した光を反射する反射部と、
前記反射部の上に形成されて入射した光を吸収する低反射部と、を備え、
前記低反射部は、吸収層と位相シフト層とを備える少なくとも2層以上の積層構造体であり、
前記反射部の上に前記吸収層と、前記位相シフト層とがこの順番で積層され、
前記吸収層を構成する材料の波長13.5nmに対する光学定数は、消衰係数k>0.041を満たし、
前記位相シフト層を構成する材料の波長13.5nmに対する光学定数は、屈折率n<0.94を満たし、且つ消衰係数k<0.02を満たすことを特徴とする反射型フォトマスク。
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US6274281B1 (en) * | 1999-12-28 | 2001-08-14 | Taiwan Semiconductor Manufacturing Company | Using different transmittance with attenuate phase shift mask (APSM) to compensate ADI critical dimension proximity |
JP2018120009A (ja) * | 2017-01-23 | 2018-08-02 | 凸版印刷株式会社 | 反射型フォトマスク及び反射型フォトマスクブランク |
JP2018173664A (ja) * | 2018-08-01 | 2018-11-08 | Hoya株式会社 | 反射型マスクブランク、反射型マスクの製造方法、及び半導体装置の製造方法 |
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US6274281B1 (en) * | 1999-12-28 | 2001-08-14 | Taiwan Semiconductor Manufacturing Company | Using different transmittance with attenuate phase shift mask (APSM) to compensate ADI critical dimension proximity |
JP2018120009A (ja) * | 2017-01-23 | 2018-08-02 | 凸版印刷株式会社 | 反射型フォトマスク及び反射型フォトマスクブランク |
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