Reflective mask blank, and method for producing reflective mask

Abstract

SOLUTION: A reflective mask blank that includes a substrate, a multilayer reflective film formed on a main surface of the substrate and reflecting exposure beam, a protective film formed on the multilayer reflective film, and an absorption film formed on the protective film and absorbing exposure beam, used in EUV lithography where EUV light is the exposure light, along with an etching stop film formed in contact with both between the protective film and the absorption film, and a first hard mask film formed on the absorption film.EFFECT: It is possible to provide a reflective mask blank with a thinner absorption film that can reduce the shadowing effect. Additionally, it is possible to form a pattern of an absorption film made from a material containing a metal that allows for the thinning of the absorption film, without damaging the protective film provided beneath the absorption film (on the substrate side), thereby providing a reflective mask with a fine absorption film pattern.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a reflective mask blank, which is a material for a reflective mask used in the manufacture of semiconductor devices such as LSIs, and a method for manufacturing a reflective mask from the reflective mask blank. [Background technology]

[0002] In the manufacturing process of semiconductor devices (semiconductor device), photolithography technology is repeatedly used, in which exposure light is irradiated onto a transfer mask, and the circuit pattern formed on the mask is transferred onto a semiconductor substrate (semiconductor wafer) via a reduced projection optical system. Conventionally, the wavelength of the exposure light has mainly been 193 nm using argon fluoride (ArF) excimer laser light, and a process called multi-patterning, which combines exposure processes and processing processes multiple times, has been used to ultimately form patterns with dimensions smaller than the exposure wavelength.

[0003] However, as the device patterns continue to become finer, the formation of even finer patterns is now required, and so EUV lithography technology, which uses extreme ultraviolet (EUV) light with a shorter wavelength than ArF excimer laser light as exposure light, has come to be used. EUV light is light with a wavelength of about 0.2 to 100 nm, more specifically, light with a wavelength of about 13.5 nm. EUV light has extremely low transparency to materials, so that conventional transmission type projection optical systems and masks cannot be used, and therefore reflective optical elements are used. For this reason, reflective masks have been proposed for pattern transfer.

[0004] A reflective mask generally has a multilayer reflective film that reflects EUV light formed on one main surface of a low-thermal expansion substrate made of glass, and an absorbing film that absorbs EUV light formed in a pattern on the multilayer reflective film. On the other hand, a mask in a state before patterning the absorbing film (including a mask in a state where a resist film is formed) is called a reflective mask blank, and this is used as a material for a reflective mask. A reflective mask blank has a multilayer reflective film that reflects EUV light formed on one main surface of a low-thermal expansion substrate made of glass, and an absorbing film that absorbs EUV light formed on the multilayer reflective film, and has a basic structure including a multilayer reflective film and an absorbing film.

[0005] As the multilayer reflective film, a Mo / Si multilayer reflective film is usually used, which ensures the reflectance of EUV light by alternately stacking molybdenum (Mo) layers and silicon (Si) layers. As the material of the absorbing film, a material mainly composed of tantalum (Ta), which has a relatively large extinction coefficient value for EUV light, is used (JP Patent Publication 2002-246299 (Patent Document 1)). On the other hand, on the other main surface of the substrate, a backside conductive film such as a metal film is formed for electrostatic chucking when the reflective mask is held in the exposure device. As the backside conductive film, a film containing chromium (Cr) and tantalum (Ta) is mainly used.

[0006] In addition, a protective film is usually formed between the multilayer reflective film and the absorbing film to protect the multilayer reflective film. The protective film is provided to protect the multilayer reflective film when it is exposed to an etching gas in the etching carried out to form a mask pattern on the absorbing film, or when it is exposed to a cleaning solution in the cleaning after the mask pattern is formed, and further to prevent the multilayer reflective film from being damaged in a pattern correction process when a defect is detected after the mask pattern is formed. For example, ruthenium (Ru) is used as the material of the protective film (JP Patent Publication 2002-122981 (Patent Document 2)), and it has also been proposed to use a material obtained by adding niobium (Nb), rhodium (Rh), zirconium (Zr), or the like to ruthenium (Ru). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2002-246299 A [Patent Document 2] JP 2002-122981 A Summary of the Invention [Problem to be solved by the invention]

[0008] In a reflective mask blank for EUV exposure, a material containing tantalum (Ta) is generally used as an absorbing film. When forming a pattern of an absorbing film made of a material containing tantalum (Ta), dry etching using a chlorine-based gas or a fluorine-based gas is usually used.

[0009] As the pattern of the absorbing film becomes finer, there is a demand for thinner absorbing films to reduce the shadowing effect during exposure using a reflective mask, but there is a limit to how thin the absorbing film can be made using materials that contain tantalum (Ta). Therefore, it is necessary to form the absorbing film using materials that contain other metals. Materials that can make the absorbing film thinner must have a higher extinction coefficient k than materials that contain tantalum (Ta), and if the absorbing film is to function as a phase shift film, it is necessary to use materials that have a lower refractive index n than materials that contain tantalum (Ta).

[0010] However, many materials containing other metals that have a higher extinction coefficient k than materials containing tantalum (Ta) or a lower refractive index n than materials containing tantalum (Ta) are poorly suited to etching, and in such cases, it is difficult to form a pattern by dry etching using a chlorine-based gas or a fluorine-based gas, which is used when forming a pattern of an absorbing film made of a material containing tantalum (Ta).

[0011] In order to form a pattern of an absorbing film which is difficult to form a pattern by dry etching using a chlorine-based gas or a fluorine-based gas, other etching methods such as ion beam etching and methanol etching can be used. However, these etching methods can also etch the protective film and even the multilayer reflective film provided below the absorbing film (on the substrate side), resulting in damage to the protective film and even the multilayer reflective film after etching of the absorbing film.

[0012] The present invention has been made to solve the above-mentioned problems, and has an object to provide a reflective mask blank in which an absorbing film is formed from a material containing a metal that can be thinned, and even when the absorbing film is etched using an etching method with high processability different from dry etching using a chlorine-based gas or a fluorine-based gas in forming a pattern of the absorbing film, no damage is caused to a film provided below the absorbing film (on the substrate side), and to provide a method for manufacturing a reflective mask from such a reflective mask blank. [Means for solving the problem]

[0013] As a result of extensive investigations to solve the above problems, the inventors have found that the above problems can be solved by forming an absorbing film of a reflective mask blank from a material containing a metal that can be made thin, and providing an etching stop film between the absorbing film and a protective film provided below the absorbing film (on the substrate side) in order to prevent etching during pattern formation of the absorbing film from reaching the protective film. They have also found that by providing a hard mask film above the absorbing film (on the side away from the substrate) and using the pattern of the hard mask film as an etching mask, the absorbing film can be etched to form a pattern of the absorbing film, thereby completing the present invention.

[0014] Accordingly, the present invention provides the following reflective mask blank and method for producing a reflective mask. 1. A substrate; a multilayer reflective film formed on one main surface of the substrate for reflecting exposure light; a protective film formed on the multilayer reflective film; an absorbing film formed on the protective film for absorbing exposure light; A reflective mask blank serving as a material for a reflective mask used in EUV lithography using EUV light as exposure light, an etching stopper film formed between the protective film and the absorbing film in contact with both of them; and a first hard mask film formed on the absorbing film. A reflective mask blank comprising: 2. A reflective mask blank as described in 1, characterized in that when the absorbing film and the etching stop film are subjected to ion beam etching under the same conditions, the etching selectivity of the etching stop film to the absorbing film is less than 1. 3. A reflective mask blank as described in 1, characterized in that when the absorbing film and the etching stop film are etched with methanol under the same conditions, the etching selectivity of the etching stop film to the absorbing film is less than 1. 4. A reflective mask blank as described in 1, characterized in that when the absorbing film and the etching stop film are dry etched using a chlorine-based gas or a fluorine-based gas under the same conditions, the etching selectivity of the etching stop film to the absorbing film exceeds 1. 5. The reflective mask blank according to 1, characterized in that when the first hard mask film and the absorbing film are dry etched using a chlorine-based gas or a fluorine-based gas under the same conditions, the etching selectivity of the absorbing film to the first hard mask film is 0.3 or less. 6. The reflective mask blank according to 1, wherein the absorbing film contains a metal other than tantalum (Ta). 7. The reflective mask blank according to 6, wherein the metal other than tantalum (Ta) is one or more selected from platinum (Pt), nickel (Ni), gold (Au), palladium (Pd), rhodium (Rh), iridium (Ir), silver (Ag), iron (Fe), cobalt (Co) and zinc (Zn). 8. The reflective mask blank according to 6, wherein the etching stop film contains tantalum (Ta). 9. The reflective mask blank according to 6, wherein the first hard mask film contains tantalum (Ta). 10. The reflective mask blank according to 6, wherein the etching stop film and the first hard mask film each contain tantalum (Ta) and nitrogen (N). 11. The reflective mask blank described in 1, characterized in that the multilayer reflective film includes a high refractive index layer formed of a material containing silicon (Si) and a low refractive index layer formed of a material containing molybdenum (Mo). 12. The reflective mask blank according to 1, wherein the protective film contains ruthenium (Ru). 13. The reflective mask blank according to 1, further comprising a second hard mask film on the first hard mask film. 14. The reflective mask blank according to 13, wherein the second hard mask film contains chromium (Cr). 15. A method for producing a reflective mask from the reflective mask blank according to any one of claims 1 to 12, comprising the steps of: dry etching the first hard mask film using a chlorine-based gas or a fluorine-based gas; patterning the absorbing film by ion beam etching or by ion beam etching and methanol etching; dry etching the etching stopper film using a chlorine-based gas or a fluorine-based gas; A method for manufacturing a reflective mask comprising the steps of: 16. A method for producing a reflective mask from a reflective mask blank according to 13 or 14, comprising the steps of: dry etching the second hard mask film using a chlorine-based gas containing chlorine (Cl) and oxygen (O); dry etching the first hard mask film using a chlorine-based gas or a fluorine-based gas; patterning the absorbing film by ion beam etching or by ion beam etching and methanol etching; dry etching the etching stopper film using a chlorine-based gas or a fluorine-based gas; A method for manufacturing a reflective mask comprising the steps of: 17. A substrate; a multilayer reflective film formed on one main surface of the substrate for reflecting exposure light; a protective film formed on the multilayer reflective film; A method for manufacturing a reflective mask by patterning an absorbing film of a reflective mask blank having an absorbing film formed on a protective film and absorbing exposure light, the method comprising: an etching stop film is provided on the reflective mask blank between the protective film and the absorbing film so as to be in contact with both of them, and a first hard mask film is provided on the absorbing film; forming a pattern of the first hard mask film by dry etching using a chlorine-based gas or a fluorine-based gas; patterning the absorbing film by ion beam etching or by ion beam etching and methanol etching using the pattern of the first hard mask film as an etching mask; The etching stopper film is removed by dry etching using a chlorine-based gas or a fluorine-based gas, A method for producing a reflective mask, comprising forming a pattern of the absorbing film. 18. The reflective mask blank further includes providing a second hard mask film on the first hard mask film; forming a pattern of the second hard mask film by dry etching using a gas containing chlorine (Cl) and oxygen (O); 18. The method for producing a reflective mask according to item 17, wherein the pattern of the first hard mask film is formed by using the pattern of the second hard mask film as an etching mask. 19. The manufacturing method according to claim 17 or 18, wherein an etching selectivity of the etching stopper film to the absorbing film in the ion beam etching is less than 1. 20. The manufacturing method according to claim 17 or 18, wherein an etching selectivity of the etching stopper film to the absorbing film in the methanol etching is less than 1. 21. The manufacturing method according to claim 17 or 18, characterized in that in dry etching using a chlorine-based gas or a fluorine-based gas to remove the etching stop film, the etching selectivity of the etching stop film to the absorbing film is greater than 1. 22. The manufacturing method according to claim 17 or 18, characterized in that in the dry etching using the chlorine-based gas or fluorine-based gas to form a pattern of the first hard mask film, the etching selectivity of the absorbing film to the first hard mask film is 0.3 or less. 23. The manufacturing method according to 17 or 18, wherein the absorbing film contains a metal other than tantalum (Ta). 24. The manufacturing method according to 23, characterized in that the metal other than tantalum (Ta) is one or more selected from platinum (Pt), nickel (Ni), gold (Au), palladium (Pd), rhodium (Rh), iridium (Ir), silver (Ag), iron (Fe), cobalt (Co) and zinc (Zn). 25. The manufacturing method according to claim 23, wherein the etching stop film contains tantalum (Ta). 26. The manufacturing method according to 23, wherein the first hard mask film contains tantalum (Ta). 27. The manufacturing method according to claim 23, wherein the etching stop film and the first hard mask film each contain tantalum (Ta) and nitrogen (N). 28. The manufacturing method described in 17 or 18, characterized in that the multilayer reflective film includes a high refractive index layer formed of a material containing silicon (Si) and a low refractive index layer formed of a material containing molybdenum (Mo). 29. The manufacturing method according to claim 17 or 18, wherein the protective film contains ruthenium (Ru). Effect of the Invention

[0015] According to the present invention, it is possible to provide a reflective mask blank having a thinner absorbing film capable of reducing the shadowing effect. Also, it is possible to provide a reflective mask having a fine absorbing film pattern by patterning an absorbing film made of a material containing a metal that allows the absorbing film to be thinned without damaging a protective film provided below the absorbing film (on the substrate side). [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a cross-sectional view showing one example (first embodiment) of a reflective mask blank of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view showing one example (second embodiment) of the reflective mask blank of the present invention. [Diagram 3] FIG. 1 is a cross-sectional view showing an example of a reflective mask of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] The present invention will now be described in further detail. The reflective mask blank of the present invention comprises a substrate, a multilayer reflective film formed on one main surface (front surface) of the substrate and reflecting exposure light, a protective film formed on the multilayer reflective film, and an absorbing film formed on the protective film and absorbing exposure light. The reflective mask blank of the present invention also comprises an etching stop film formed between the protective film and the absorbing film. Furthermore, the reflective mask blank of the present invention comprises a first hard mask film formed on the absorbing film.

[0018] The reflective mask blank of the present invention is suitable as a material for a reflective mask used in EUV lithography using EUV light as exposure light. The wavelength of EUV light used in EUV lithography using EUV light as exposure light is 13 to 14 nm, and is usually light with a wavelength of about 13.5 nm. The reflective mask blank and the reflective mask using EUV light as exposure light are also called EUV mask blank and EUV mask, respectively.

[0019] 1 is a cross-sectional view showing one example (first embodiment) of a reflective mask blank of the present invention. This reflective mask blank 11 includes a substrate 1, a multilayer reflective film 2 formed on the substrate 1 in contact with the substrate 1, a protective film 3 formed in contact with the multilayer reflective film 2, an etching stop film 4 formed in contact with the protective film 3, an absorbing film 5 formed in contact with the etching stop film 4, and a first hard mask film 6 formed in contact with the absorbing film 5.

[0020] The substrate preferably has low thermal expansion characteristics for EUV light exposure, and has a thermal expansion coefficient of, for example, ±2×10 -8 / ℃, preferably within ±5×10 -9 It is preferable that the material is made of a material having a temperature within a range of 100°C / °F. Such a material is titania-doped quartz glass (SiO 2 -TiO 2 Glass-based glass, etc. It is preferable to use a substrate having a sufficiently flat surface, and the surface roughness of the main surface of the substrate is preferably 0.5 nm or less, more preferably 0.2 nm or less, in terms of RMS value. Such a surface roughness can be obtained by polishing the substrate, etc. The size of the substrate is preferably 152 mm square for the main surface, and about 6.35 mm thick. A substrate of this size is a so-called 6025 substrate (a substrate with a main surface size of 6 inches square and a thickness of 0.25 inches).

[0021] The multilayer reflective film is a film that reflects exposure light in a reflective mask. The multilayer reflective film is preferably provided in contact with one main surface of the substrate, but another film such as an undercoat film may be provided between the multilayer reflective film and the one main surface of the substrate. The multilayer reflective film includes a high refractive index layer having a relatively high refractive index to the exposure light and a low refractive index layer having a relatively low refractive index to the exposure light. The multilayer reflective film generally has a periodic stacking structure in which high refractive index layers and low refractive index layers are alternately stacked.

[0022] The high refractive index layer is preferably formed of a material containing silicon (Si). The high refractive index layer may contain one or more additive elements selected from oxygen (O), nitrogen (N), carbon (C), boron (B) and hydrogen (H), or may be composed of a multilayer structure of a layer containing an additive element and a layer not containing an additive element. The thickness of the high refractive index layer is preferably 3.5 nm or more, more preferably 4 nm or more, and is preferably 4.9 nm or less, more preferably 4.4 nm or less.

[0023] The low refractive index layer is preferably formed of a material containing molybdenum (Mo). The low refractive index layer can also be formed of a material containing ruthenium (Ru). The low refractive index layer may contain one or more additive elements selected from oxygen (O), nitrogen (N), carbon (C), boron (B) and hydrogen (H), and may be composed of a multilayer structure including a layer containing an additive element and a layer not containing an additive element. The thickness of the low refractive index layer is preferably 2.1 nm or more, more preferably 2.6 nm or more, and is preferably 3.5 nm or less, more preferably 3 nm or less.

[0024] The periodic stacking structure may include a high refractive index layer and a low refractive index layer, and one or more high refractive index layers and one or more low refractive index layers may be included in one period. The number of layers included in one period is two or more, and one period may be composed of, for example, one high refractive index layer and one low refractive index layer. In addition, one period may include two or more high refractive index layers having different compositions (for example, different composition ratios, different compositions depending on the presence or absence of an additive element, etc.), and may include two or more low refractive index layers having different compositions (for example, different composition ratios, different compositions depending on the presence or absence of an additive element, etc.). In this case, the number of layers included in one period is three or more, and may be four or more or five or more, but is preferably eight or less. The number of periods in the periodic stacking structure is preferably 30 or more, and is preferably 50 or less, more preferably 40 or less. When the low refractive index layer is formed of a material containing ruthenium (Ru), it is preferable that the layer (uppermost layer) farthest from the substrate in the periodic stacking structure is a high refractive index layer.

[0025] The thickness of the multilayer reflective film having a periodic stacked structure is adjusted depending on the exposure wavelength and the incidence angle of the exposure light, but is preferably 200 nm or more, more preferably 270 nm or more, and is preferably 400 nm or less, more preferably 290 nm or less.

[0026] Methods for forming a multilayer reflective film include a sputtering method in which power is supplied to a target, the atmospheric gas is turned into plasma (ionized) by the supplied power, and sputtering is performed, and an ion beam sputtering method in which an ion beam is irradiated onto a target. Sputtering methods include a DC sputtering method in which a direct current voltage is applied to a target, and an RF sputtering method in which a high frequency voltage is applied to a target. The sputtering method is a film formation method in which a voltage is applied to a target with a sputtering gas introduced into a chamber, the gas is ionized, and the sputtering phenomenon caused by the gas ions is utilized. In particular, the magnetron sputtering method is advantageous in terms of productivity. The power applied to the target may be DC or RF, and DC also includes pulse sputtering in which the negative bias applied to the target is reversed for a short period of time to prevent the target from charging up.

[0027] The multilayer reflective film can be formed by a sputtering method using, for example, a sputtering device capable of mounting a plurality of targets. Specifically, the target can be appropriately selected from a molybdenum (Mo) target for forming a layer containing molybdenum (Mo), a ruthenium (Ru) target for forming a layer containing ruthenium (Ru), a silicon (Si) target for forming a layer containing silicon (Si), and the like, and can be formed by using a rare gas such as helium (He) gas, argon (Ar) gas, krypton (Kr) gas, or xenon (Xe) gas as the sputtering gas.

[0028] In addition, when sputtering is reactive sputtering using a reactive gas, for example, when forming a film containing nitrogen (N), nitrogen (N 2When forming a film containing oxygen (O), a nitrogen-containing gas such as oxygen (O 2 When forming a film containing nitrogen (N) and oxygen (O), nitrous oxide (N 2 O) gas, nitric oxide (NO) gas, nitrogen dioxide (NO 2 When forming a film containing carbon (C) and oxygen (O), carbon monoxide (CO) gas, carbon dioxide (CO 2 When forming a film containing carbon oxide gas such as SiO2 gas, or hydrogen (H2O), 2 ) gas, and methane (CH 4 ) gas may be used in conjunction with a rare gas.

[0029] Furthermore, when forming a layer containing boron (B), a molybdenum (Mo) target with boron (B) added (molybdenum boride (MoB) target), a silicon (Si) target with boron (B) added (silicon boride (SiB) target), or the like can be used.

[0030] The protective film is also called a capping film, and is a film for protecting the multilayer reflective film. The protective film is usually provided in contact with the multilayer reflective film. The protective film preferably contains ruthenium (Ru), and is preferably formed of a material containing ruthenium (Ru).

[0031] Examples of materials containing ruthenium (Ru) include ruthenium (Ru) alone, and alloys containing ruthenium (Ru) and a metal or metalloid different from ruthenium (Ru). Examples of metals or metalloids different from ruthenium (Ru) include niobium (Nb), rhenium (Re), zirconium (Zr), titanium (Ti), chromium (Cr), and silicon (Si). Examples of materials containing ruthenium (Ru) include ruthenium (Ru) alone and alloys containing ruthenium (Ru) and niobium (Nb). The content of metals or metalloids different from ruthenium (Ru) in the protective film is preferably 30 atomic % or less, more preferably 20 atomic % or less, on average throughout the film. The lower limit of the content of metals or metalloids different from ruthenium (Ru) in the protective film is not particularly limited, but is preferably 5 atomic % or more, more preferably 10 atomic % or more, on average throughout the film.

[0032] The protective film may be a single layer structure or a multilayer structure in which multiple layers with different compositions are combined, and each layer constituting the single layer or multiple layers may have a gradient composition structure in which the composition changes continuously in the thickness direction. The thickness of the protective film is preferably 2 nm or more, more preferably 3 nm or more, and is preferably 5 nm or less, more preferably 4 nm or less.

[0033] The protective film is formed by sputtering a target selected appropriately from a ruthenium (Ru) target, a target of a metal or semimetal different from ruthenium (Ru), specifically, a niobium (Nb) target, a rhenium (Re) target, a zirconium (Zr) target, a titanium (Ti) target, a chromium (Cr) target, a silicon (Si) target, a target in which two or more selected from niobium (Nb), rhenium (Re), zirconium (Zr), titanium (Ti), chromium (Cr) and silicon (Si) are mixed, and a target in which ruthenium (Ru) is mixed with one or more metals or semimetals different from ruthenium (Ru) selected from niobium (Nb), rhenium (Re), zirconium (Zr), titanium (Ti), chromium (Cr) and silicon (Si), and the like, and a rare gas such as helium (He) gas, argon (Ar) gas, krypton (Kr) gas, or xenon (Xe) gas is used as a sputtering gas. The sputtering is preferably performed by magnetron sputtering.

[0034] In a reflective mask, the absorbing film is a film that absorbs exposure light and reduces reflectance. In a reflective mask, a transfer pattern is formed by the difference in reflectance between a portion where the absorbing film is formed and a portion where the absorbing film is not formed. The absorbing film may be a single layer or a multilayer, and an anti-reflection layer or the like may be formed on the surface.

[0035] The present invention is suitable for cases where the material constituting the absorbing film is a material that is difficult to etch by dry etching using a chlorine-based gas or a fluorine-based gas, and in particular, is a material that is substantially not etched by dry etching using a chlorine-based gas or a fluorine-based gas.

[0036] In the present invention, the absorbing film preferably contains a metal other than tantalum (Ta), and more preferably contains a metal other than tantalum (Ta) and chromium (Cr). In the present invention, the absorbing film preferably does not contain tantalum (Ta). Also, the absorbing film preferably does not contain chromium (Cr). The absorbing film is a film made of a material that absorbs EUV light and can be patterned.

[0037] The metal other than tantalum (Ta) contained in the absorbing film is preferably one or more selected from platinum (Pt), nickel (Ni), gold (Au), palladium (Pd), rhodium (Rh), iridium (Ir), silver (Ag), iron (Fe), cobalt (Co) and zinc (Zn). Materials containing these metals can be made thinner than an absorbing film formed of a material containing tantalum (Ta). Among these metals, platinum (Pt) and nickel (Ni) are more preferable. The material constituting the absorbing film may contain oxygen (O), nitrogen (N), carbon (C), etc., and may contain one or more selected from platinum (Pt), nickel (Ni), gold (Au), palladium (Pd), rhodium (Rh), iridium (Ir), silver (Ag), iron (Fe), cobalt (Co) and zinc (Zn) as well as other metals such as ruthenium (Ru).

[0038] The content of metals other than tantalum (Ta), particularly metals other than tantalum (Ta) and chromium (Cr), contained in the absorbing film is preferably 20 atomic % or more, more preferably 30 atomic % or more. The content of metals other than tantalum (Ta), particularly metals other than tantalum (Ta) and chromium (Cr), contained in the absorbing film may be 100 atomic % or less, less than 100%, particularly 90 atomic % or less.

[0039] The thickness of the absorbing film is preferably 10 nm or more, more preferably 20 nm or more, and even more preferably 30 nm or more, and is preferably 80 nm or less, more preferably 70 nm or less. The sheet resistance of the absorbing film is preferably 1×10 6 Ω / □ or less, more preferably 1×10 5The surface roughness Sq of the absorbing film is preferably 0.8 nm or less, and more preferably 0.6 nm or less.

[0040] The absorbing film can be formed by sputtering, and the sputtering is preferably a magnetron sputtering method. Specifically, the absorbing film can be formed by sputtering using a rare gas such as helium (He) gas, argon (Ar) gas, krypton (Kr) gas, or xenon (Xe) gas as a sputtering gas by appropriately selecting a target from among targets of metals constituting the absorbing film and targets of metal compounds constituting the absorbing film (targets containing a metal constituting the absorbing film and oxygen (O), nitrogen (N), carbon (C), or the like) according to the composition, and by reactive sputtering using a rare gas and a reactive gas such as an oxygen-containing gas, a nitrogen-containing gas, or a carbon-containing gas according to the composition. Specifically, the reactive gas is oxygen (O 2 ) gas, nitrogen (N 2 ) gas, nitrous oxide (N 2 O) gas, nitric oxide (NO) gas, nitrogen dioxide (NO 2 ) gas, such as nitrogen oxide gas, carbon monoxide (CO) gas, and carbon dioxide (CO 2 ) gas and other carbon dioxide gases.

[0041] In the present invention, the etching stopper film is a film for preventing the etching in the pattern formation of the absorbing film from reaching the protective film. The etching stopper film is usually provided in contact with both the protective film and the absorbing film. It is preferable that the etching stopper film has an etching resistance and thickness such that the etching in the pattern formation of the absorbing film does not reach the protective film below it (on the substrate side) during, for example, overetching after the etching in the pattern formation of the absorbing film reaches the etching stopper film, in other words, the etching stopper film does not disappear during the etching in the pattern formation of the absorbing film.

[0042] When the material constituting the absorbing film is a material that is difficult to etch by dry etching using a chlorine-based gas or a fluorine-based gas, ion beam etching or methanol etching can be suitably used as an etching method for forming a pattern of the absorbing film. However, since these etching methods can also etch the protective film, it is preferable that the etching stop film is formed of a material that is difficult to etch by ion beam etching or methanol etching compared to the absorbing film, that is, the etching rate of the etching stop film is lower than the etching rate of the absorbing film. Specifically, the etching selectivity of the etching stop film to the absorbing film in ion beam etching is preferably less than 1, more preferably 0.9 or less, and even more preferably 0.8 or less. In addition, the etching selectivity of the etching stop film to the absorbing film in methanol etching is preferably less than 1, more preferably 0.9 or less, and even more preferably 0.8 or less. In the present invention, the etching selectivity is the ratio of the etching rates of two films under the same etching conditions. For example, the etching selectivity of the etching stop film to the absorbing film is the ratio of the etching rate of the etching stop film to the etching rate of the absorbing film.

[0043] On the other hand, the etching stopper film is usually removed by etching after forming the pattern of the absorbing film. Therefore, when the material constituting the absorbing film is a material that is difficult to etch by dry etching using a chlorine-based gas or a fluorine-based gas, it is preferable that the etching stopper film is formed of a material that is easily etched by dry etching using a chlorine-based gas or a fluorine-based gas, that is, the etching rate of the etching stopper film is higher than the etching rate of the absorbing film. Specifically, the etching selectivity of the etching stopper film to the absorbing film in dry etching using a chlorine-based gas or a fluorine-based gas is preferably more than 1, more preferably 5 or more, and even more preferably 10 or more.

[0044] In the present invention, the dry etching using a chlorine-based gas is dry etching using a gas containing chlorine (Cl), for example,2 Dry etching using a gas containing hydrogen chloride (HCl) gas, dry etching using a gas containing chlorine (Cl) and oxygen (O), for example, dry etching using a gas containing chlorine (Cl) 2 ) gas and oxygen (O 2 ) gas. On the other hand, dry etching using a fluorine-based gas includes carbon tetrafluoride (CF 4 ) gas and sulfur hexafluoride (SF 6 ) gas.

[0045] The etching stopper film preferably contains tantalum (Ta), and is preferably formed of a material containing tantalum (Ta). The content of tantalum (Ta) in the etching stopper film is preferably 30 atomic % or more, more preferably 40 atomic % or more. The material constituting the etching stopper film may contain oxygen (O), nitrogen (N), carbon (C), etc. The etching stopper film particularly preferably contains nitrogen (N), and is particularly preferably made of tantalum (Ta) and nitrogen (N). When the metal contained in the absorbing film is platinum (Pt) or nickel (Ni), it is particularly preferable that the etching stopper film is made of tantalum (Ta) and nitrogen (N). When the etching stopper film contains tantalum (Ta) and nitrogen (N), and particularly when it is made of tantalum (Ta) and nitrogen (N), the content of nitrogen (N) is preferably 10 atomic % or more, more preferably 40 atomic % or more, and is preferably 70 atomic % or less, more preferably 60 atomic % or less.

[0046] The material constituting the etching stopper film may contain a metal other than tantalum (Ta), preferably a metal other than tantalum (Ta) and chromium (Cr), in particular a metal that is easily etched by dry etching using a chlorine-based gas or a fluorine-based gas, but it is preferable that the material does not contain the metals contained in the absorbing film, in particular platinum (Pt), nickel (Ni), gold (Au), palladium (Pd), rhodium (Rh), iridium (Ir), silver (Ag), iron (Fe), cobalt (Co), and zinc (Zn).

[0047] The thickness of the etching stop film is preferably equal to or less than the thickness of the absorbing film, more preferably equal to or less than half the thickness of the absorbing film. In addition, since it is preferable to make the total thickness of the absorbing film and the etching stop film (the thickness of the circuit pattern or mask pattern part of the reflective mask) thin, the thickness of the etching stop film is preferably equal to or less than 10 nm, more preferably equal to or less than 5 nm. On the other hand, in order to prevent the etching in the pattern formation of the absorbing film from reaching the protective film, the thickness of the etching stop film is preferably equal to or more than 1 nm, more preferably equal to or more than 2 nm.

[0048] The etching stopper film can be formed by sputtering, and magnetron sputtering is preferred. Specifically, the etching stopper film can be formed by sputtering using a rare gas such as helium (He) gas, argon (Ar) gas, krypton (Kr) gas, or xenon (Xe) gas as a sputtering gas, by appropriately selecting a target from among a target of the metal constituting the etching stopper film (e.g., tantalum (Ta)) or a target of a compound of the metal constituting the etching stopper film (a target containing the metal constituting the etching stopper film and oxygen (O), nitrogen (N), carbon (C), or the like) according to the composition, and by reactive sputtering using a reactive gas such as an oxygen-containing gas, nitrogen-containing gas, or carbon-containing gas together with the rare gas according to the composition. Specifically, the reactive gas is oxygen (O 2 ) gas, nitrogen (N 2 ) gas, nitrous oxide (N 2 O) gas, nitric oxide (NO) gas, nitrogen dioxide (NO2 ) gas, such as nitrogen oxide gas, carbon monoxide (CO) gas, and carbon dioxide (CO 2 ) gas and other carbon dioxide gases.

[0049] In the present invention, the first hard mask film is a film that functions as an etching mask in etching for forming a pattern of the absorbing film. In the present invention, the first hard mask film is provided on the absorbing film in order to apply ion beam etching or methanol etching as etching for forming a pattern of the absorbing film. The first hard mask film is usually provided in contact with the absorbing film. When the absorbing film includes a layer (reflectance reduction layer) on the upper part thereof that mainly plays a role of reducing the reflectance at the wavelength of light used in inspection such as pattern inspection, the first hard mask film can be formed on the reflectance reduction layer of the absorbing film.

[0050] When the material constituting the absorbing film is a material that is difficult to etch by dry etching using a chlorine-based gas or a fluorine-based gas, ion beam etching or methanol etching can be suitably used as the etching for forming the pattern of the absorbing film. Therefore, it is preferable that the first hard mask film is formed of a material that is difficult to etch by ion beam etching or methanol etching compared to the absorbing film, that is, the etching rate of the first hard mask film is lower than the etching rate of the absorbing film. Specifically, the etching selectivity of the first hard mask film to the absorbing film in the ion beam etching is preferably less than 1, more preferably 0.9 or less, and even more preferably 0.8 or less. In addition, the etching selectivity of the first hard mask film to the absorbing film in the methanol etching is preferably less than 1, more preferably 0.9 or less, and even more preferably 0.8 or less.

[0051] On the other hand, the first hard mask film is usually removed by etching after forming the pattern of the absorbing film. Therefore, when the material constituting the absorbing film is a material that is difficult to etch by dry etching using chlorine-based gas or fluorine-based gas, the first hard mask film is formed of a material that is easily etched by dry etching using chlorine-based gas or fluorine-based gas, in other words, the absorbing film is difficult to etch by dry etching using chlorine-based gas or fluorine-based gas, that is, the etching rate of the first hard mask film is preferably higher than the etching rate of the absorbing film. Specifically, the etching selectivity of the absorbing film to the first hard mask in dry etching using chlorine-based gas or fluorine-based gas is preferably 0.3 or less, more preferably 0.15 or less.

[0052] The first hard mask film preferably contains tantalum (Ta), and is preferably formed of a material containing tantalum (Ta). The content of tantalum (Ta) in the first hard mask film is preferably 30 atomic % or more, more preferably 40 atomic % or more. The material constituting the first hard mask film may contain oxygen (O), nitrogen (N), carbon (C), etc. It is particularly preferable that the first hard mask film contains nitrogen (N), and is particularly made of tantalum (Ta) and nitrogen (N). When the metal contained in the absorbing film is platinum (Pt) or nickel (Ni), it is particularly preferable that the first hard mask film is made of tantalum (Ta) and nitrogen (N). When the first hard mask film contains tantalum (Ta) and nitrogen (N), particularly when it is made of tantalum (Ta) and nitrogen (N), the content of nitrogen (N) is preferably 10 atomic % or more, more preferably 40 atomic % or more, and is preferably 70 atomic % or less, more preferably 60 atomic % or less.

[0053] The material constituting the first hard mask film may contain a metal other than tantalum (Ta), preferably a metal other than tantalum (Ta) and chromium (Cr), in particular a metal that is easily etched by dry etching using a chlorine-based gas or a fluorine-based gas, but it is preferable that the material does not contain the metals contained in the absorbing film, in particular platinum (Pt), nickel (Ni), gold (Au), palladium (Pd), rhodium (Rh), iridium (Ir), silver (Ag), iron (Fe), cobalt (Co), and zinc (Zn).

[0054] It is preferable that the first hard mask film can be removed at the same time when the etching stop film is etched and removed. Therefore, it is preferable that the first hard mask film is composed of the same elements as the etching stop film, particularly the same composition ratio, and the etching rate of the first hard mask film is equal to the etching rate of the etching stop film, specifically, the etching selectivity of the first hard mask film to the etching stop film is 0.5 to 1.5.

[0055] The thickness of the first hard mask film is the thickness of the first hard mask film remaining after etching in forming the pattern of the absorbing film, and the thickness of the first hard mask film remaining is preferably the same as or thinner than the thickness of the etching stop film. Specifically, the thickness of the first hard mask film is preferably 2 nm or more, more preferably 5 nm or more, and is preferably 30 nm or less, more preferably 15 nm or less.

[0056] The first hard mask film can be formed by sputtering, and the sputtering is preferably a magnetron sputtering method. Specifically, the first hard mask film can be formed by sputtering using a rare gas such as helium (He) gas, argon (Ar) gas, krypton (Kr) gas, or xenon (Xe) gas as a sputtering gas by appropriately selecting a target from a target of a metal constituting the first hard mask film (e.g., tantalum (Ta)) or a target of a compound of a metal constituting the first hard mask film (a target containing a metal constituting the first hard mask film and oxygen (O), nitrogen (N), carbon (C), or the like) according to the composition, and can also be formed by reactive sputtering using a reactive gas such as an oxygen-containing gas, a nitrogen-containing gas, or a carbon-containing gas together with the rare gas according to the composition. Specifically, the reactive gas is oxygen (O 2 ) gas, nitrogen (N 2 ) gas, nitrous oxide (N 2 O) gas, nitric oxide (NO) gas, nitrogen dioxide (NO 2 ) gas, such as nitrogen oxide gas, carbon monoxide (CO) gas, and carbon dioxide (CO 2 ) gas and other carbon dioxide gases.

[0057] A second hard mask film may be provided on the first hard mask film on the side away from the substrate. This second hard mask film functions as an etching mask when etching the first hard mask film, and may have etching characteristics different from those of the first hard mask film. The second hard mask film is preferably provided in contact with the first hard mask film.

[0058] 2 is a cross-sectional view showing one example (second embodiment) of the reflective mask blank of the present invention. This reflective mask blank 12 includes a substrate 1, a multilayer reflective film 2 formed on the substrate 1 in contact with the substrate 1, a protective film 3 formed in contact with the multilayer reflective film 2, an etching stop film 4 formed in contact with the protective film 3, an absorbing film 5 formed in contact with the etching stop film 4, a first hard mask film 6 formed in contact with the absorbing film 5, and a second hard mask film 7 formed in contact with the first hard mask film 6.

[0059] The second hard mask film preferably contains chromium (Cr), and is preferably formed of a material containing chromium (Cr). When processing the first hard mask film formed of a material containing tantalum (Ta), the material containing chromium (Cr) has different etching characteristics from the first hard mask film, and functions as an etching mask when etching the first hard mask film. Therefore, the material containing chromium (Cr) of the second hard mask film preferably does not contain tantalum (Ta).

[0060] Examples of materials containing chromium (Cr) include chromium (Cr) alone and chromium compounds containing chromium (Cr) and one or more selected from oxygen (O), nitrogen (N) and carbon (C). In particular, chromium compounds containing chromium (Cr) and one or more selected from oxygen (O), nitrogen (N) and carbon (C) are preferred. Examples of chromium compounds include CrO, CrN, CrON, CrC, CrOC, CrNC, and CrONC. In the case of chromium compounds, the content of chromium (Cr) is preferably 20 atomic % or more, more preferably 30 atomic % or more. The content of oxygen (O) is preferably 50 atomic % or less, more preferably 40 atomic % or less, the content of nitrogen (N) is preferably 40 atomic % or less, more preferably 30 atomic % or less, and the content of carbon (C) is preferably 20 atomic % or less.

[0061] The thickness of the second hard mask film is not particularly limited, but from the viewpoint of reducing the thickness of the resist film when forming a pattern of the second hard mask film, it is preferably 20 nm or less, more preferably 10 nm or less, and further preferably 7 nm or less. The thickness of the second hard mask film is usually 5 nm or more.

[0062] The second hard mask film can be formed by sputtering, and the sputtering is preferably a magnetron sputtering method. Specifically, the second hard mask film can be formed by sputtering using a rare gas such as helium (He) gas, argon (Ar) gas, krypton (Kr) gas, or xenon (Xe) gas as a sputtering gas by appropriately selecting a target from a target of a metal (e.g., chromium (Cr)) constituting the second hard mask film or a target of a compound of a metal (a target containing a metal constituting the second hard mask film and oxygen (O), nitrogen (N), carbon (C), or the like) constituting the second hard mask film according to the composition, and can also be formed by reactive sputtering using a reactive gas such as an oxygen-containing gas, a nitrogen-containing gas, or a carbon-containing gas together with the rare gas according to the composition. Specifically, the reactive gas is oxygen (O 2 ) gas, nitrogen (N 2 ) gas, nitrous oxide (N 2 O) gas, nitric oxide (NO) gas, nitrogen dioxide (NO 2 ) gas, such as nitrogen oxide gas, carbon monoxide (CO) gas, and carbon dioxide (CO 2 ) gas and other carbon dioxide gases.

[0063] A back surface conductive film used for electrostatically chucking the reflective mask to an exposure device may be provided on the other main surface (back surface), which is the surface opposite to the one main surface of the substrate, preferably in contact with the other main surface.

[0064] The back conductive film preferably has a sheet resistance of 100Ω / □ or less, and there is no particular restriction on the material. Examples of the material of the back conductive film include materials containing tantalum (Ta) or chromium (Cr). In addition, the materials containing tantalum (Ta) or chromium (Cr) may contain oxygen (O), nitrogen (N), carbon (C), boron (B), etc. Examples of materials containing tantalum (Ta) include Ta alone, and tantalum (Ta) compounds such as TaO, TaN, TaON, TaC, TaCN, TaCO, TaCON, TaB, TaOB, TaNB, TaONB, TaCB, TaCNB, TaCOB, and TaCONB. Examples of materials containing chromium (Cr) include Cr alone, and chromium (Cr) compounds such as CrO, CrN, CrON, CrC, CrCN, CrCO, CrCON, CrB, CrOB, CrNB, CrONB, CrCB, CrCNB, CrCOB, and CrCONB.

[0065] The thickness of the back surface conductive film is not particularly limited as long as it functions for electrostatic chucking, but is usually about 5 to 100 nm. The thickness of the back surface conductive film is preferably set to a thickness that balances the film stress with the film and film pattern formed on one main surface (front surface) side after forming it as a reflective mask, i.e., after forming the pattern of the absorbing film. The back surface conductive film may be formed before forming the multilayer reflective film, or after forming all the films on the multilayer reflective film side of the substrate, or may be formed after forming a part of the film on the multilayer reflective film side of the substrate, and then forming the back surface conductive film, and then forming the remaining film on the multilayer reflective film side of the substrate. The back surface conductive film can be formed, for example, by magnetron sputtering.

[0066] The reflective mask blank of the present invention may have a resist film formed on the side farthest from the substrate. The resist film is preferably an electron beam (EB) resist.

[0067] From the reflective mask blank, for example, a reflective mask having a substrate, a multilayer reflective film formed on one main surface of the substrate, a protective film formed in contact with the multilayer reflective film, an etching stop film pattern formed in contact with the protective film, and an absorbing film pattern formed in contact with the etching stop film pattern can be obtained. In the reflective mask, a transfer pattern is formed due to the difference in reflectance between the absorbing film and the portion (circuit pattern or mask pattern) below it (substrate side) where the etching stop film is formed, and the portion where the circuit pattern or mask pattern is not formed.

[0068] 3 is a cross-sectional view showing an example of the reflective mask of the present invention. This reflective mask 10 comprises a substrate 1, a multilayer reflective film 2 formed on the substrate 1 in contact with the substrate 1, a protective film 3 formed in contact with the multilayer reflective film 2, an etching stop film pattern 41 formed in contact with the protective film 3, and an absorbing film pattern 51 formed in contact with the etching stop film pattern 41. In the case of this reflective mask 10, the absorbing film pattern 51 is formed on the protective film 3 via the etching stop film pattern 41.

[0069] From the reflective mask blank of the present invention, Etching the first hard mask film; patterning the absorbing film by etching; Etching the etch stop film. A reflective mask can be manufactured by a method including the steps of:

[0070] Also, from the reflective mask blank having the second hard mask film, Etching the second hard mask film; Etching the first hard mask film; patterning the absorbing film by etching; Etching the etch stop film. A reflective mask can be manufactured by a method including the steps of:

[0071] When a reflective mask is manufactured from a reflective mask blank that does not have a second hard mask film, specifically, providing a reflective mask blank; If necessary, forming a resist film on the first hard mask film; forming a resist pattern from a resist film on the first hard mask film; forming a pattern of the first hard mask film by etching the first hard mask film using the resist pattern as an etching mask; removing the resist pattern; forming a pattern of the absorbing film by etching the absorbing film using the pattern of the first hard mask film as an etching mask; removing the etching stopper film and the pattern of the first hard mask film by etching the etching stopper film and the pattern of the first hard mask film exposed by removing the absorbing film; The method can be produced by a method comprising the steps of:

[0072] On the other hand, when a reflective mask is manufactured from a reflective mask blank having a second hard mask film, specifically, providing a reflective mask blank; If necessary, forming a resist film on the second hard mask film; forming a resist pattern from the resist film on the second hard mask film; forming a pattern of the second hard mask film by etching the second hard mask film using the resist pattern as an etching mask; removing the resist pattern; forming a pattern of the first hard mask film by etching the first hard mask film using the pattern of the second hard mask film as an etching mask; Etching and removing the pattern of the second hard mask film; forming a pattern of the absorbing film by etching the absorbing film using the pattern of the first hard mask film as an etching mask; removing the etching stopper film and the pattern of the first hard mask film by etching the etching stopper film and the pattern of the first hard mask film exposed by removing the absorbing film; The method can be produced by a method comprising the steps of:

[0073] The resist film is preferably an electron beam (EB) resist, and the resist pattern can be formed by drawing or exposing the resist film to an electron beam (EB) or the like, and then developing the resist film. The resist pattern can be removed by washing with sulfuric acid / hydrogen peroxide (SPM).

[0074] The etching of the absorbing film is preferably ion beam etching or methanol etching. The etching of the absorbing film may be performed by only ion beam etching, only methanol etching, or a combination of ion beam etching and methanol etching. When both are combined, it is preferable to perform methanol etching after performing ion beam etching.

[0075] Ion beam etching is a method of physically etching an object to be etched by colliding accelerated charged particles (ions). Charged particles (ions) used in ion beam etching include charged particles (ions) of rare gases such as xenon (Xe) gas and argon (Ar) gas, but it is preferable to use charged particles (ions) of argon (Ar) gas. On the other hand, methanol etching is dry etching using methanol gas.

[0076] The etching for forming the pattern of the absorbing film may be performed by first performing ion beam etching, and before the absorbing film is completely etched, i.e., in a state where at least a part of the absorbing film in the thickness direction remains, preferably in a state where only a small part remains (for example, a thickness of about 1 to 5 nm remains), the etching is switched to methanol etching to etch the remaining part of the absorbing film, and the entire absorbing film may be etched. Such a method is particularly suitable when the metal contained in the absorbing film is platinum (Pt) or nickel (Ni).

[0077] The etching of the first hard mask film and its pattern, the etching of the second hard mask film and its pattern, and the etching of the etching stopper film are each preferably dry etching using a chlorine-based gas or a fluorine-based gas. In particular, the dry etching of the second hard mask film and its pattern using a chlorine-based gas is preferably dry etching using a chlorine-based gas containing chlorine (Cl) and oxygen (O). For example, a film containing tantalum (Ta) can be etched by dry etching using a fluorine-based gas. Also, a film containing tantalum (Ta) can be etched by dry etching using a chlorine-based gas. When a film containing tantalum (Ta) is etched by dry etching using a chlorine-based gas, it is preferable to use it in combination with dry etching using a fluorine-based gas. On the other hand, a film containing chromium (Cr) can be etched by dry etching using a chlorine-based gas, particularly dry etching using a chlorine-based gas containing chlorine (Cl) and oxygen (O). The etching of the pattern of the first hard mask film can be performed using the same etching method as that used for forming the pattern of the first hard mask film, and the etching of the pattern of the second hard mask film can be performed using the same etching method as that used for forming the pattern of the second hard mask film.

[0078] In order to avoid damage to the protective film provided below the absorbing film (on the substrate side) and further damage to the multilayer reflective film, it is preferable that the etching of the absorbing film is performed such that the entire etching stop film is not lost after etching in forming the pattern of the absorbing film, i.e., at least a portion of the etching stop film in the thickness direction remains.

[0079] The etching stopper film in the portion exposed after the absorbing film is removed and the pattern of the first hard mask film can be simultaneously removed by the same etching. In this case, in order to avoid damage to the protective film provided below the absorbing film (on the substrate side) and further damage to the multilayer reflective film, it is preferable that the pattern of the first hard mask film is removed before the etching stopper film in the portion exposed after the absorbing film is completely removed.

[0080] In the present invention, an etching stop film is provided between a protective film and an absorbing film in contact with both of them in a reflective mask blank, and a first hard mask film is provided on the absorbing film; forming a pattern of the first hard mask film by dry etching; patterning the absorbing film by one or both of ion beam etching and methanol etching using the pattern of the first hard mask film as an etching mask; The etch stop film can be removed by dry etching to form a pattern of the absorbing film.

[0081] In this case, a second hard mask film is further provided on the first hard mask film, forming a pattern of a second hard mask film by dry etching using a gas containing chlorine (Cl) and oxygen (O); The pattern of the first hard mask film can also be formed using the pattern of the second hard mask film as an etching mask.

[0082] By providing an etching stop film between the protective film and the absorbing film, a reflective mask can be manufactured without damaging the film provided below the absorbing film (on the substrate side) even if the absorbing film is etched using ion beam etching or methanol etching in forming the pattern of the absorbing film. EXAMPLES

[0083] The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0084] [Example 1] Sputtering was performed on a titania-doped quartz substrate measuring 152 mm square and approximately 6 mm thick, using a molybdenum (Mo) target and a silicon (Si) target as the targets and argon (Ar) gas as the sputtering gas, to form a multilayer reflective film (thickness: 280 nm, reflectivity for light with a wavelength of 13.5 nm: 65%), which is a laminated film in which layers of molybdenum (Mo) and layers of silicon (Si) are alternately stacked.

[0085] Next, sputtering was performed using ruthenium (Ru) as a target and argon (Ar) gas as a sputtering gas to form a protective film (thickness: 5 nm) made of ruthenium (Ru).

[0086] Next, a tantalum (Ta) target was used as the target, and argon (Ar) gas and nitrogen (N 2 ) gas was used to form an etching stopper film made of tantalum nitride (TaN) (thickness: 5 nm, Ta: 52 atomic %, N: 48 atomic %).

[0087] Next, sputtering was performed using a nickel (Ni) target as the target and argon (Ar) gas as the sputtering gas to form an absorbing film (thickness: 20 nm) made of nickel (Ni).

[0088] Next, a tantalum (Ta) target was used as the target, and argon (Ar) gas and nitrogen (N 2 ) gas to form a first hard mask film made of tantalum nitride (TaN) (thickness: 15 nm, Ta: 52 atomic %, N: 48 atomic %).

[0089] Next, a chromium (Cr) target was used as the target, and argon (Ar) gas and nitrogen (N 2 ) gas to form a second hard mask film made of chromium nitride (CrN) (thickness: 10 nm, Cr: 87 atomic %, N: 13 atomic %), thereby obtaining a reflective mask blank.

[0090] A reflective mask was manufactured from the obtained reflective mask blank. First, a resist film (thickness: 100 nm) was applied onto the second hard mask film, and the resist film was irradiated with an electron beam and developed to form a resist pattern.

[0091] Next, using the resist pattern as an etching mask, a pattern of a second hard mask film made of chromium nitride (CrN) was formed by dry etching using a chlorine-based gas under the following conditions.

[0092] <Dry etching conditions for second hard mask film> Equipment: ICP (Inductively Coupled Plasma) method Gas: Chlorine (Cl 2 ) gas (flow rate: 185sccm), oxygen (O 2 ) Gas (flow rate: 2sccm) Gas pressure: 6mTorr (0.8Pa) ICP power: 400W

[0093] Next, the resist pattern was removed by SPM cleaning.

[0094] Next, using the pattern of the second hard mask film as an etching mask, a pattern of a first hard mask film made of tantalum nitride (TaN) was formed by dry etching using a fluorine-based gas under the following conditions.

[0095] <Dry Etching Conditions for First Hard Mask Film> Equipment: ICP (Inductively Coupled Plasma) method Gas: Sulfur hexafluoride (SF 6 ) gas, helium (He) gas Gas pressure: 4mTorr (0.53Pa) ICP power: 400W

[0096] Next, the pattern of the second hard mask film made of chromium nitride (CrN) was removed by dry etching using a chlorine-based gas under the above-mentioned dry etching conditions for the second hard mask film.

[0097] Next, using the pattern of the first hard mask film as an etching mask, an absorbing film pattern made of nickel (Ni) was formed by ion beam etching under the following conditions.

[0098] <Ion beam etching conditions for absorbing film> Gas: Ar (flow rate: 1.5 cm 3 / min) Acceleration voltage: 2 kV Beam current: 165μA

[0099] Next, the pattern of the first hard mask film made of tantalum nitride (TaN) was removed by dry etching using a fluorine-based gas under the dry etching conditions for the first hard mask film described above, and the etching stop film made of tantalum nitride (TaN) was removed from the portion exposed by removing the absorption film. When the pattern of the first hard mask film was completely removed, the dry etching using the fluorine-based gas was stopped.

[0100] Next, the remaining etching stopper film made of tantalum nitride (TaN) was removed by dry etching using a chlorine-based gas under the following conditions, to obtain a reflective mask.

[0101] <Dry etching conditions for etching stopper film> Equipment: ICP (Inductively Coupled Plasma) method Gas: Chlorine (Cl 2 )gas Gas pressure: 3mTorr (0.40Pa) ICP power: 350W

[0102] When the obtained reflective mask was checked, it was found that the absorbing film made of nickel (Ni) had been etched and the absorbing film pattern had been formed in the specified shape, and the protective film made of ruthenium (Ru) exposed in the parts of the reflective mask where the absorbing film pattern did not exist had not been damaged by the etching.

[0103] [Example 2] A reflective mask blank was obtained in the same manner as in Example 1, except that an absorbing film (film thickness: 20 nm) made of platinum (Pt) was formed using a platinum (Pt) target as the target. Next, a reflective mask was obtained from the reflective mask blank in the same manner as in Example 1.

[0104] When the obtained reflective mask was checked, it was found that the absorbing film made of platinum (Pt) had been etched and the absorbing film pattern had been formed in the specified shape, and the protective film made of ruthenium (Ru) exposed in the parts of the reflective mask where the absorbing film pattern did not exist had not been damaged by the etching.

[0105] [Comparative Example 1] A reflective mask blank was obtained in the same manner as in Example, except that the second etching mask film and the etching stopper film were not formed, and the absorbing film was formed directly on the protective film.

[0106] A reflective mask was manufactured from the obtained reflective mask blank. First, a resist film (thickness: 100 nm) was applied onto the first hard mask film, and the resist film was irradiated with an electron beam and developed to form a resist pattern.

[0107] Next, using the resist pattern as an etching mask, a pattern of a first hard mask film made of tantalum nitride (TaN) was formed by dry etching using a fluorine-based gas under the dry etching conditions for the first hard mask film in Example 1.

[0108] Next, the resist pattern was removed by SPM cleaning.

[0109] Next, using the pattern of the first hard mask film as an etching mask, an absorbing film pattern made of nickel (Ni) was formed by ion beam etching under the ion beam etching conditions for the absorbing film in Example 1.

[0110] Next, the pattern of the first hard mask film made of tantalum nitride (TaN) was removed by dry etching using a fluorine-based gas under the dry etching conditions for the first hard mask film, thereby obtaining a reflective mask.

[0111] When the obtained reflective mask was checked, it was found that the absorbing film made of nickel (Ni) had been etched and a pattern of the absorbing film had been formed in a predetermined shape, but the protective film made of ruthenium (Ru) that was exposed in the part of the reflective mask where the absorbing film pattern did not exist had been etched and part of the multilayer reflective film was exposed.

[0112] [Comparative Example 2] The second etching mask film and the etching stopper film are not formed, and the absorbing film is directly formed on the protective film. The absorbing film is formed by using a chromium (Cr) target as a target and argon (Ar) gas and nitrogen (N 2A reflective mask blank was obtained in the same manner as in the example, except that sputtering was performed using a CrN gas to form an absorbing film (thickness: 20 nm, Cr: 87 atomic %, N: 13 atomic %) made of chromium nitride (CrN).

[0113] A reflective mask was manufactured from the obtained reflective mask blank. First, a resist film (thickness: 100 nm) was applied onto the first hard mask film, and the resist film was irradiated with an electron beam and developed to form a resist pattern.

[0114] Next, using the resist pattern as an etching mask, a pattern of a first hard mask film made of tantalum nitride (TaN) was formed by dry etching using a fluorine-based gas under the dry etching conditions for the first hard mask film in Example 1.

[0115] Next, the resist pattern was removed by SPM cleaning.

[0116] Next, using the pattern of the first hard mask film as an etching mask, an absorbing film pattern made of chromium nitride (CrN) was formed by ion beam etching under the ion beam etching conditions for the absorbing film in Example 1.

[0117] Next, the pattern of the first hard mask film made of tantalum nitride (TaN) was removed by dry etching using a fluorine-based gas under the dry etching conditions for the first hard mask film, thereby obtaining a reflective mask.

[0118] When the obtained reflective mask was checked, it was found that the absorbing film made of chromium nitride (CrN) had been etched and a pattern of the absorbing film had been formed in the specified shape, but the protective film made of ruthenium (Ru) that was exposed in the part of the reflective mask where the absorbing film pattern did not exist had been etched and part of the multilayer reflective film was exposed. [Explanation of symbols]

[0119] 1 Board 10 Reflective mask 11, 12 Reflective mask blanks 2 Multilayer reflective film 3 Protective film 4. Etch stop film 41 Etch stop film pattern 5. Absorption membrane 51 Absorbing membrane pattern 6 First etching mask film 7 Second etching mask film

Claims

1. A substrate; a multilayer reflective film formed on one main surface of the substrate for reflecting exposure light; a protective film formed on the multilayer reflective film; an absorbing film formed on the protective film for absorbing exposure light; A reflective mask blank serving as a material for a reflective mask used in EUV lithography using EUV light as exposure light, an etching stopper film formed between the protective film and the absorbing film in contact with both of them; and a first hard mask film formed on the absorbing film. A reflective mask blank comprising:

2. 2. The reflective mask blank according to claim 1, wherein when the absorbing film and the etching stop film are subjected to ion beam etching under the same conditions, an etching selectivity of the etching stop film to the absorbing film is less than 1.

3. 2. The reflective mask blank according to claim 1, wherein when the absorbing film and the etching stop film are etched with methanol under the same conditions, an etching selectivity of the etching stop film to the absorbing film is less than 1.

4. The reflective mask blank described in claim 1, characterized in that when the absorbing film and the etching stop film are dry etched using a chlorine-based gas or a fluorine-based gas under the same conditions, the etching selectivity of the etching stop film to the absorbing film exceeds 1.

5. 2. The reflective mask blank according to claim 1, wherein when the first hard mask film and the absorption film are dry etched using a chlorine-based gas or a fluorine-based gas under the same conditions, an etching selectivity of the absorption film to the first hard mask film is 0.3 or less.

6. 2. The reflective mask blank according to claim 1, wherein the absorbing film contains a metal other than tantalum (Ta).

7. The reflective mask blank according to claim 6, characterized in that the metal other than tantalum (Ta) is at least one selected from platinum (Pt), nickel (Ni), gold (Au), palladium (Pd), rhodium (Rh), iridium (Ir), silver (Ag), iron (Fe), cobalt (Co) and zinc (Zn).

8. The reflective mask blank according to claim 6, wherein the etching stop film contains tantalum (Ta).

9. The reflective mask blank according to claim 6 , wherein the first hard mask film contains tantalum (Ta).

10. 7. The reflective mask blank according to claim 6, wherein the etching stop film and the first hard mask film each contain tantalum (Ta) and nitrogen (N).

11. 2. The reflective mask blank according to claim 1, characterized in that the multilayer reflective film includes a high refractive index layer formed of a material containing silicon (Si) and a low refractive index layer formed of a material containing molybdenum (Mo).

12. 2. The reflective mask blank according to claim 1, wherein the protective film contains ruthenium (Ru).

13. 2. The reflective mask blank according to claim 1, further comprising a second hard mask film on the first hard mask film.

14. The reflective mask blank according to claim 13, wherein the second hard mask film contains chromium (Cr).

15. A method for producing a reflective mask from the reflective mask blank according to any one of claims 1 to 12, comprising the steps of: dry etching the first hard mask film using a chlorine-based gas or a fluorine-based gas; patterning the absorbing film by ion beam etching or by ion beam etching and methanol etching; dry etching the etching stopper film using a chlorine-based gas or a fluorine-based gas; A method for manufacturing a reflective mask comprising the steps of:

16. A method for producing a reflective mask from the reflective mask blank according to claim 13 or 14, comprising the steps of: dry etching the second hard mask film using a chlorine-based gas containing chlorine (Cl) and oxygen (O); dry etching the first hard mask film using a chlorine-based gas or a fluorine-based gas; patterning the absorbing film by ion beam etching or by ion beam etching and methanol etching; dry etching the etching stopper film using a chlorine-based gas or a fluorine-based gas; A method for manufacturing a reflective mask comprising the steps of:

17. A substrate; a multilayer reflective film formed on one main surface of the substrate for reflecting exposure light; a protective film formed on the multilayer reflective film; A method for manufacturing a reflective mask by patterning an absorbing film of a reflective mask blank having an absorbing film formed on a protective film and absorbing exposure light, the method comprising: an etching stop film is provided on the reflective mask blank between the protective film and the absorbing film so as to be in contact with both of them, and a first hard mask film is provided on the absorbing film; forming a pattern of the first hard mask film by dry etching using a chlorine-based gas or a fluorine-based gas; Using the pattern of the first hard mask film as an etching mask, the absorbing film is patterned by ion beam etching or by ion beam etching and methanol etching; The etching stopper film is removed by dry etching using a chlorine-based gas or a fluorine-based gas, A method for manufacturing a reflective mask, comprising forming a pattern of the absorbing film.

18. the reflective mask blank further includes providing a second hard mask film on the first hard mask film; forming a pattern of the second hard mask film by dry etching using a gas containing chlorine (Cl) and oxygen (O); 18. The method for producing a reflective mask according to claim 17, wherein the pattern of the first hard mask film is formed using the pattern of the second hard mask film as an etching mask.

19. 19. The method according to claim 17, wherein an etching selectivity of the etching stop film to the absorbing film in the ion beam etching is less than 1.

20. 19. The method of claim 17, wherein an etching selectivity of the etching stop film to the absorbing film in the methanol etching is less than 1.

21. 19. The method according to claim 17, wherein an etching selectivity of the etching stop film to the absorbing film is greater than 1 in dry etching using a chlorine-based gas or a fluorine-based gas to remove the etching stop film.

22. 19. The manufacturing method according to claim 17, wherein an etching selectivity of the absorption film to the first hard mask film in dry etching using the chlorine-based gas or the fluorine-based gas to form a pattern of the first hard mask film is 0.3 or less.

23. 19. The method of claim 17, wherein the absorbing film contains a metal other than tantalum (Ta).

24. The manufacturing method according to claim 23, characterized in that the metal other than tantalum (Ta) is at least one selected from the group consisting of platinum (Pt), nickel (Ni), gold (Au), palladium (Pd), rhodium (Rh), iridium (Ir), silver (Ag), iron (Fe), cobalt (Co) and zinc (Zn).

25. 24. The method of claim 23, wherein the etch stop layer comprises tantalum (Ta).

26. 24. The method of claim 23, wherein the first hard mask film contains tantalum (Ta).

27. 24. The method of claim 23, wherein the etch stop film and the first hard mask film each contain tantalum (Ta) and nitrogen (N).

28. 19. The manufacturing method according to claim 17, wherein the multilayer reflective film includes a high refractive index layer formed of a material containing silicon (Si) and a low refractive index layer formed of a material containing molybdenum (Mo).

29. 19. The method according to claim 17, wherein the protective film contains ruthenium (Ru).

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