Blank photomask, method for processing blank photomask, and method for manufacturing blank photomask

Abstract

The invention relates to a blank photomask, a processing method of the blank photomask and a manufacturing method of the blank photomask. The present invention addresses the problem of providing a blank photomask including a silicon-containing hard mask film that can function as a hard mask when an absorber layer is processed by dry etching and contributes to improvement of the resolution of a resist pattern. The solution of the invention is a blank photomask. A multilayer reflective film layer which is formed on the substrate and reflects EUV light; an absorber layer which is formed on the multilayer reflective film layer and absorbs the EUV light; a silicon-containing hard mask film which is directly or indirectly formed on the absorber layer; and a photoresist film which is formed on the silicon-containing hard mask film. The silicon-containing hard mask film is a cured product of a composition for forming a silicon-containing hard mask film, which is cured at a temperature of 50-180 DEG C (inclusive).

Description

Technical Field

[0001] This invention relates to materials for making photomasks, including a blank photomask of a hard mask film used in etching a thin film deposited on a substrate, a method for processing the blank photomask using the same, and a method for manufacturing the same. Background Technology

[0002] With the miniaturization of semiconductor devices, there are now exposure methods that use optical projection exposure devices with ArF excimer lasers to transfer patterns onto wafers using photomasks. However, these exposure methods using optical projection exposure devices will eventually reach their resolution limits, so there are proposals for new pattern formation methods such as direct drawing or imprint lithography or EUV lithography using electron beam lithography devices.

[0003] Among these new lithography technologies, EUV exposure, considered the limit for shortening ultraviolet light wavelengths, uses EUV light with a wavelength of approximately 13.5 nm, which is shorter than that of excimer lasers, reducing the exposure time to about one-quarter of the usual wavelength. It has attracted attention as a next-generation lithography technology for semiconductor devices. Because of the short wavelength, refractive optics cannot be used in EUV exposure, and there are proposals to use reflective optics in reflective masks (Patent Document 1). The reflective film (multilayer reflective film) used in the aforementioned reflective mask typically employs a multilayer film with a relatively high refractive index layered alternately with a relatively low refractive index layered on a scale of several nm. For example, multilayer films with alternating layers of Si and Mo films are known to have high reflectivity for EUV light in the 13-14 nm range.

[0004] In the formation of a photomask pattern, for example, a composite substrate has a substrate on which multiple reflective film layers are formed, a cover layer on which a protective layer is formed to act as an anti-oxidation layer for the multiple reflective film layers or a protective layer during mask cleaning, a buffer layer on which a buffer layer is formed to prevent etching damage during the formation of the photomask pattern, an absorber layer on which an absorber layer is formed, and a hard mask layer on which a hard mask layer is formed to be resistant to etching of the absorber layer. A blank photomask is made by forming a photoresist film on the composite substrate. The photoresist film of the blank photomask is patterned by an electron beam, and then a photoresist pattern is obtained by development. The obtained photoresist pattern is used as a mask to etch the absorber layer and process the absorber layer pattern. However, if the photoresist film thickness is maintained in the same manner as before miniaturization when the absorber layer pattern is refined, the ratio of film thickness to pattern (i.e., aspect ratio) increases. This degrades the shape of the photoresist pattern, making it difficult to transfer the pattern smoothly, or, depending on the situation, causing the photoresist pattern to collapse or peel off. Therefore, the photoresist film thickness needs to be reduced with miniaturization.

[0005] On the other hand, regarding the absorber layer etched using a photoresist pattern as a mask, materials with Ta as the main component, such as Ta, TaB, TaBN, TaO, and TaN, or materials with Cr as the main component and having at least one component selected from N, O, and C, are used. Etching of materials with Ta as the main component can be patterned using chlorine-based dry etching, and etching of materials with Cr as the main component can be patterned using fluorine-based dry etching. However, for the reasons described above, the method of etching the absorber layer using a thin-film photoresist becomes increasingly difficult to ensure sufficient processing accuracy in the formation of mask patterns for EUV exposure. Therefore, a hard mask layer needs to be formed under the photoresist film.

[0006] Although not a method for processing reflective blank photomasks, for example, in order to dry etch a silicon-based light-shielding film using a thin-film photoresist, a thin chromium-based material film with sufficient thickness to serve as a hard mask is used as the hard mask film, thereby achieving high precision in the mask pattern, as disclosed in Patent Document 2. Similarly, as a hard mask for a chromium light-shielding film, a silicon-based material film can be used, as disclosed in Patent Document 3.

[0007] Furthermore, as mentioned above, regarding the method of forming a hard mask by forming a film of a chromium-based material processed under chlorine-based dry etching conditions and a material containing transition metals and silicon processed under fluorine-based dry etching conditions, it is further proposed to use an SOG film as the hard mask film for processing chromium-based material films (Patent Document 4).

[0008] When SOG films are used as hard mask films, they are baked at high temperatures after coating to harden them, and it is necessary to prevent them from mixing with photoresist films. For example, the embodiment in Patent Document 4 uses a baking process at 190°C. On the other hand, the processing method for reflective blank masks with multilayer reflective films does not mention whether SOG films can be used as hard masks, and their practicality as EUV blank masks is unclear. One reason for this is that when the SOG film is hardened in a reflective blank mask, the multilayer reflective films stacked below the SOG film are also subjected to high temperatures, disrupting the periodic structure of the multilayer reflective films, thus causing a decrease in the reflectivity of EUV light or the generation of phase defects.

[0009] In an embodiment of Patent Document 5, a phase transfer film is formed on a quartz substrate, a light-shielding layer is formed thereon to prepare photomask substrates, a silicon-containing composition is spin-coated, and the substrate is baked at 250°C to form a silicon-containing film.

[0010] Existing technical documents

[0011] Patent documents

[0012] [Patent Document 1] Japanese Patent Application Publication No. 63-201656

[0013] [Patent Document 2] Japanese Patent Application Publication No. 2007-241060

[0014] [Patent Document 3] Japanese Patent Application Publication No. 2006-146152

[0015] [Patent Document 4] Japanese Patent Application Publication No. 2008-26500

[0016] [Patent Document 5] Japanese Patent Application Publication No. 2010-230986 Summary of the Invention

[0017] [The problem that the invention aims to solve]

[0018] As mentioned above, further improvements in the precision of reflective photomask technology require the ability to transfer resist patterns onto the absorber layer with even higher accuracy. The use of SOG films as hard mask films is useful in addressing the insufficient dry etching resistance of thin-film photoresists or in improving the pattern resolution of photoresists. However, challenges remain regarding suppressing intermixing with the photoresist and suppressing interlayer mixing of multiple reflective films.

[0019] The present invention was made in view of the above-mentioned matters, and its purpose is to provide a blank photomask containing a silicon-containing hard mask film that can function as a hard mask when the absorber layer is processed by dry etching and also contributes to the improvement of the resolution of the resist pattern, a processing method of the blank photomask using the same, and a manufacturing method of the blank photomask.

[0020] [Methods for solving the problem]

[0021] To address the aforementioned issues, the present invention provides a blank photomask, characterized by comprising:

[0022] substrate,

[0023] Multilayer reflective film for reflecting EUV light formed on the substrate

[0024] An absorber layer that absorbs EUV light is formed on the multilayer reflective film.

[0025] Silicon-containing hard mask film formed directly or indirectly on the absorber layer, and

[0026] A photoresist film is formed on the silicon-containing hard mask film;

[0027] The silicon-containing hard mask is a cured product of a silicon-containing hard mask forming composition that is cured at a temperature of 50°C to 180°C.

[0028] Because this blank photomask contains a silicon-containing hard mask film that functions as a hard mask film, it can transfer fine resist patterns onto the absorber layer with high precision. Furthermore, since the silicon-containing hard mask film can be formed within the aforementioned temperature range, it does not cause interlayer mixing of multiple reflective layers, thus improving the transfer accuracy of the resist pattern. In other words, by using the blank photomask of the present invention, a photomask containing an absorber layer with finely patterned absorber layers formed with high precision can be provided without degrading the reflectivity of EUV light. In other words, the blank photomask of the present invention is a blank photomask containing a silicon-containing hard mask film that functions as a hard mask when the absorber layer is processed by dry etching, and also contributes to improving the resolution of the resist pattern.

[0029] Furthermore, the composition for forming the silicon-containing hard mask film is preferably a silicon-containing compound containing any one or more of the following general formula (Sx-1), the following general formula (Sx-2), and the following general formula (Sx-3).

[0030] [Chemistry 1]

[0031]

[0032] (where R is in the formula) a R b and R c Each can be a monovalent organic group with 1 to 30 carbon atoms, which may be the same or different.

[0033] As long as the composition for forming a silicon-containing hard mask film is as described, it exhibits excellent thermosetting properties, and thus a hardened film can be formed by baking at a temperature of 50°C to 180°C. Furthermore, a silicon-containing hard mask film with excellent resistance to dry etching can be formed. Therefore, as long as a blank photomask containing a hardened form of such a silicon-containing hard mask formation composition is used, a photomask containing an absorber layer with finely patterned microstructures can be provided.

[0034] In this case, in the above equations (Sx-1) to (Sx-3), R a ~R c At least one of them should be an organic group having one or more carbon-oxygen single bonds or carbon-oxygen double bonds.

[0035] As long as the composition is a silicon-containing hard mask film forming component containing a silicon-containing compound with such organic groups, it has excellent thermosetting properties, and can be formed by baking at a temperature of 50°C to 180°C.

[0036] The aforementioned composition for forming silicon-containing hard mask films preferably also contains a crosslinking catalyst.

[0037] As long as the composition for forming such a silicon-containing hard mask film is excellent, the thermosetting properties are even better, so that a hardened film can be reliably formed by baking at a temperature of 50°C to 180°C.

[0038] The aforementioned crosslinking catalyst is preferably a sulfonium salt, monazine salt, phosphonium salt, ammonium salt, alkali metal salt, or a polysiloxane having any one of sulfonium salt, monazine salt, phosphonium salt, and ammonium salt as part of its structure.

[0039] As long as it is a composition for forming such a silicon-containing hard mask film, it has particularly excellent thermosetting properties, so that a hardened film can be formed more reliably by baking at a temperature of 50°C to 180°C.

[0040] Furthermore, the present invention provides a method for processing a blank photomask, comprising the following steps:

[0041] (i-1) An electron beam is irradiated onto the blank photomask of the present invention, and then developed using a developer to form a photoresist pattern on the photoresist film.

[0042] (i-2) By etching the photoresist pattern as a mask, the silicon-containing film pattern is formed on the silicon-containing hard mask film, and

[0043] (i-3) The absorber layer is processed directly or indirectly by etching the silicon-containing film pattern as a mask.

[0044] Because this blank photomask fabrication method uses a silicon-containing hard mask film, which exhibits superior dry etching resistance to chlorine-based gases compared to photoresist films, as the hard mask, the resist pattern can be transferred to the absorber layer of the blank photomask with high precision. Furthermore, the silicon-containing hard mask film can be deposited in a temperature range of 50°C to 180°C, thus preventing interlayer mixing of multiple reflective layers and improving the transfer accuracy of the resist pattern. In other words, by using the blank photomask fabrication method of this invention, a photomask containing an absorber layer with finely patterned absorbers formed with high precision can be provided without degrading the reflectivity of EUV light.

[0045] Furthermore, the present invention provides a method for manufacturing a blank photomask, comprising the following steps:

[0046] Prepare substrate,

[0047] A multilayer reflective film layer for reflecting EUV light is formed on the substrate.

[0048] An absorber layer that absorbs EUV light is formed on the multilayer reflective film.

[0049] A coating is obtained by directly or indirectly coating a silicon-containing hard mask film forming composition that is cured at a temperature of 50°C to 180°C onto the absorber layer, and then curing the coating at a temperature of 50°C to 180°C to form a silicon-containing hard mask film.

[0050] A photoresist film is formed on the silicon-containing hard mask film.

[0051] As long as the method for manufacturing such a blank photomask is applicable, a silicon-containing hard photomask film that is useful as a hard photomask film can be formed. Therefore, a blank photomask capable of transferring fine resist patterns onto the absorber layer with high precision can be manufactured. Furthermore, by forming the silicon-containing hard photomask film within the aforementioned temperature range, interlayer mixing of multiple reflective layers is prevented, thereby improving the transfer accuracy of the resist pattern. In other words, as long as the method for manufacturing the blank photomask of the present invention is applicable, a blank photomask that does not degrade the reflectivity of EUV light and can form fine patterns onto the absorber layer with high precision can be provided.

[0052] [The effects of the invention]

[0053] As described above, by using the blank photomask of the present invention, a photomask with an absorber layer having finely patterned microstructures formed with high precision can be provided without degrading the reflectivity of EUV light. That is, the blank photomask of the present invention becomes a blank photomask containing a silicon-containing hard mask film that functions as a hard mask when the absorber layer is processed by dry etching, and also contributes to improving the resolution of the resist pattern.

[0054] Furthermore, the blank photomask processing method according to the present invention can provide a photomask having an absorber layer with finely patterned microstructures formed with high precision, which does not degrade the reflectivity of EUV light.

[0055] Furthermore, according to the blank photomask manufacturing method of the present invention, a blank photomask can be manufactured that does not degrade the reflectivity of EUV light and can form fine patterns on the absorber layer with high precision. Attached Figure Description

[0056] [ Figure 1 A schematic cross-sectional view of an example of the blank photomask of the present invention. Detailed Implementation

[0057] As mentioned above, further improvements in the precision of reflective photomask technology require the ability to transfer resist patterns onto the absorber layer with even higher accuracy. The use of a hard mask film as an SOG film is useful in compensating for the insufficient dry etching resistance of thin-film photoresists (Patent Document 4), and it is also expected to improve the pattern resolution of the photoresist. However, it is unclear whether SOG films can be used as hard masks in the fabrication methods of reflective photomasks with multiple reflective layers. Furthermore, it is believed that the following issues exist: when hardening the SOG film in a reflective photomask, high temperatures are applied to the multilayer reflective films stacked beneath the SOG film, disrupting the periodic structure of the multilayer reflective films, which could lead to a decrease in EUV light reflectivity or the generation of phase defects.

[0058] The inventors of this application explored blank photomasks, methods for processing blank photomasks, and methods for manufacturing blank photomasks, which transfer resist patterns to absorber layers with high precision. Through repeated and in-depth research, they discovered that by using a hardened material formed from a silicon-containing hard mask film composition that is cured at a temperature of 50°C to 180°C as a hard mask, interlayer mixing of multiple reflective film layers can be avoided, thereby improving the transfer precision of the resist pattern to the absorber layer. This led to the completion of the present invention.

[0059] That is, the present invention is a blank photomask, characterized by having:

[0060] substrate,

[0061] Multilayer reflective film for reflecting EUV light formed on the substrate

[0062] An absorber layer that absorbs EUV light is formed on the multilayer reflective film.

[0063] Silicon-containing hard mask film formed directly or indirectly on the absorber layer, and

[0064] A photoresist film is formed on the silicon-containing hard mask film;

[0065] The hardened form of the silicon-containing hard mask is a component for forming a silicon-containing hard mask that is cured at a temperature between 50°C and 180°C.

[0066] The blank photomask, its processing method, and its manufacturing method of the present invention utilize a hardened material formed from a silicon-containing hard mask film forming composition that can be cured at a temperature between 50°C and 180°C. This prevents interlayer mixing of multiple reflective layers and improves the transfer accuracy of the resist pattern on the absorber layer. In other words, the present invention provides a blank photomask that achieves a photomask containing an absorber layer with a finely patterned absorber layer without degrading the reflectivity of EUV light, making it extremely useful in the fine patterning of semiconductor device manufacturing.

[0067] The present invention will now be described in detail, but the present invention is not limited thereto.

[0068] <Blank light mask>

[0069] First, the structure of the reflective blank photomask and the reflective photomask of the present invention will be described below with reference to the drawings. In the description of the drawings, the same reference numerals are used for the same constituent elements, and sometimes the description is omitted. In addition, for convenience, the drawings are sometimes enlarged, and the size ratios of each constituent element are not necessarily the same as in reality.

[0070] The curing of the silicon-containing hard mask film forming composition in this specification is such that when the photoresist material is coated on the silicon-containing hard mask film, the reduction in film thickness of the silicon-containing hard mask film is so slight that it does not cause intermingling with the photoresist film. At this point, the reduction in film thickness of the silicon-containing hard mask film relative to the film thickness before photoresist coating should preferably be less than 5%, more preferably less than 3%, further preferably less than 1%, and especially preferably less than 0.5%.

[0071] [Overall structure of blank photomask]

[0072] The blank photomask (reflective photomask substrate) of the present invention generally comprises a substrate, a multilayer reflective film layer formed on the substrate (e.g., on a main surface of the substrate) that reflects EUV light (exposure light), an absorber layer (light absorption film) formed on the multilayer reflective film layer, a silicon-containing hard mask film formed directly or indirectly on the absorber layer, and a photoresist film formed on the silicon-containing hard mask film. The blank photomask may also further include an etching mask film that functions as an etching mask during the processing of the absorber film. Furthermore, a back conductive film may be provided on another main surface (back side) of the substrate. Further, the blank photomask may also include a protective film.

[0073] Figure 1This is a schematic cross-sectional view showing an example of the blank photomask (reflective blank photomask) of the present invention. The reflective blank photomask 101 includes: a substrate 1; a multilayer reflective film layer 2 formed on the substrate 1 that reflects EUV light exposure light; a protective film 3 (any configuration in the present invention) formed on the multilayer reflective film layer 2 to protect the multilayer reflective film layer 2; an absorber layer (light absorption film) 4 formed on the protective film 3 to absorb exposure light; a first layer 5 (any configuration in the present invention) of a hard mask film formed on the absorber layer 4 that functions as a hard mask when the absorber layer 4 is patterned by dry etching; a silicon-containing hard mask film 6 that functions as a second hard mask film when the first layer 5 of the hard mask film is patterned by dry etching; and a photoresist film 7 formed on the silicon-containing hard mask film 6.

[0074] The following describes in detail each of the constituent components (mandatory and optional components) of the blank photomask of the present invention.

[0075] [Substrate]

[0076] The substrate should preferably have low thermal expansion characteristics, for example, a coefficient of thermal expansion of ±2×10⁻⁶. -8 Materials formed within a temperature range of / ℃. Examples of such materials include titanium dioxide-doped quartz glass (SiO2-TiO2 type glass). Furthermore, the surface roughness of the main surface of the substrate should preferably be 0.5 nm or less in terms of RMS value.

[0077] [Conductive film on the back]

[0078] A conductive film (back conductive film) for electrostatically holding a reflective photomask in an exposure device (e.g., an EUV scanner) can also be provided on one main surface of the substrate and the other main surface (back side), which is the opposite side.

[0079] The back conductive film should preferably have a thin-film resistivity of 100 Ω / □ or less, and there are no particular restrictions on the material. Materials containing tantalum (Ta) or chromium (Cr) can be used as examples of back conductive films. Furthermore, materials containing oxygen (O) or nitrogen (N) can also be used. The thickness of the back conductive film is sufficient to perform its function of electrostatic clamping and is not particularly limited; it is typically about 20–300 nm.

[0080] [Multi-layer reflective coating]

[0081] A multilayer reflective film is a film in a reflective mask that reflects EUV light as exposure light. A multilayer reflective film is, for example, a periodic stacked structure having, alternately, a high refractive index layer with a relatively high refractive index for exposure light and a low refractive index layer with a relatively low refractive index for exposure light.

[0082] The high-refractive-index layer is preferably formed using a material containing silicon (Si), and the low-refractive-index layer is preferably formed using a material containing molybdenum (Mo). The thickness of the multilayer reflective coating is preferably above 270 nm, and more preferably below 400 nm.

[0083] [Protective film]

[0084] Any protective film is also called a cover film. A protective film is used to protect multiple reflective layers. The protective film is preferably formed from materials containing ruthenium (Ru), and may also contain titanium (Ti), zirconium (Zr), niobium (Nb), etc. In addition, it may also contain oxygen (O), nitrogen (N), carbon (C), etc. There is no particular limitation on the thickness of the protective film, but it is preferably above 2 nm and below 5 nm.

[0085] [Absorber layer]

[0086] The absorber layer (light-absorbing film) can be made of any material that absorbs EUV light and can be patterned. There are no particular limitations on the material used for the absorber layer; for example, a film containing tantalum (Ta) is preferable, and it may also contain oxygen (O), nitrogen (N), boron (B), etc. There are no particular limitations on the thickness of the absorber layer, but it is preferable to be between 50 nm and 80 nm.

[0087] [The first layer of the hard mask]

[0088] The first layer of the hard mask film of the present invention, which is arbitrarily constructed, is a layer that can function as an etch mask (hard mask) in etching as an absorber layer.

[0089] The first layer of the hard mask film is preferably a material resistant to fluorine-based dry etching of the absorber layer and removable by chlorine-based dry etching. The first layer of the hard mask film is preferably formed of a material containing chromium (Cr). In addition to chromium, it may contain one or more materials selected from oxygen (O), nitrogen (N), and carbon (C), and is more preferably composed of chromium and one or more materials selected from oxygen, nitrogen, and carbon. It is preferable to contain nitrogen, and particularly suitable is chromium nitride (CrN) composed of chromium and nitrogen. Furthermore, it is preferable to contain nitrogen and oxygen, and particularly suitable is chromium oxide nitride (CrNO) composed of chromium and nitrogen and oxygen.

[0090] Furthermore, it may also contain nitrogen, oxygen, and carbon. In the case of carbon, chromium nitride oxide carbide (CrNOC) composed of chromium, nitrogen, oxygen, and carbon is suitable. There is no particular limitation on the thickness of the etching mask film, but it is preferable to be above 5 nm and below 20 nm.

[0091] [Silicon-containing hard mask (second layer of hard mask)]

[0092] The silicon-containing hard mask film (the second layer of the hard mask film) in this invention is, for example, a layer that functions as an etching mask (hard mask) in the etching of the first layer of the hard mask film. In the case of using it as an etching mask in the etching of the first layer of the hard mask film, the silicon-containing hard mask film (the second layer of the hard mask film) is preferably a material that is resistant to chlorine-based dry etching of the first layer of the hard mask film and can be removed by fluorine-based dry etching. The silicon-containing hard mask film (the second layer of the hard mask film) is a hardened composition containing silicon (Si), in other words, it is formed by a material containing silicon (Si). The silicon (Si)-containing material may contain one or more elements selected from oxygen (O), nitrogen (N), and carbon (C) in addition to silicon, and is more preferably composed of silicon and one or more elements selected from oxygen, nitrogen, and carbon.

[0093] In this invention, the silicon-containing hard mask film (the second layer of the hard mask film) is a cured product of a silicon-containing hard mask film forming composition that is cured at a temperature of 50°C to 180°C. Particularly suitable is a cured product (silicon oxide-based material film) obtained by baking a silicon-containing hard mask film forming composition (A) containing any one or more of a silicon-containing compound having repeating units represented by the following general formula (Sx-1), repeating units represented by the following general formula (Sx-2), and partial structures represented by the following general formula (Sx-3), after coating at a temperature of 50°C to 150°C.

[0094] [Chemistry 2]

[0095]

[0096] (where R is in the formula) a R b and R c (These are monovalent organic groups, which may be the same or different, with 1 to 30 carbon atoms.)

[0097] In the case of a hard silicon mask that is a composition cured at a temperature higher than 180°C, the reflectivity of the multilayer reflective film will decrease. On the other hand, in the case of a hard silicon mask that is a composition cured at a temperature lower than 50°C, even if the product is stored in the usage environment (e.g., a clean room: 23°C), some of it will harden, which will become the cause of defects.

[0098] The composition for forming the silicon-containing hard mask film (A) mentioned above is preferably a polysiloxane (Sx) and a solvent, and may also contain additives such as crosslinking catalysts and crosslinking agents.

[0099] The following describes in more detail the components that may be contained in (A) the composition for forming silicon hard mask films.

[0100] (Polysiloxane (Sx))

[0101] The polysiloxane (Sx) is preferably one or more of the repeating unit represented by the following general formula (Sx-1), the repeating unit represented by the following general formula (Sx-2), and the partial structure represented by the following general formula (Sx-3).

[0102] [Chemistry 3]

[0103]

[0104] (where R is in the formula) a R b and R c (These are monovalent organic groups, which may be the same or different, with 1 to 30 carbon atoms.)

[0105] The aforementioned polysiloxane (Sx) may be a thermally crosslinked polysiloxane (Sx).

[0106] The aforementioned thermally crosslinked polysiloxane (Sx) can be manufactured by hydrolyzing and condensing the following hydrolyzable monomer (Sm).

[0107] Specifically, examples of hydrolyzable monomers (Sm) include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetraisopropoxysilane, trimethoxysilane, triethoxysilane, tripropoxysilane, triisopropoxysilane, methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, methyltriisopropoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltripropoxysilane, ethyltriisopropoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltripropoxysilane, vinyltriisopropoxysilane, propyltrimethoxysilane, propyltriethoxysilane, propyltripropoxysilane, propyltriisopropoxysilane, isopropyltrimethoxysilane, and isopropyltriethoxysilane. Isopropyltripropoxysilane, Isopropyltriisopropoxysilane, Butyltrimethoxysilane, Butyltriethoxysilane, Butyltripropoxysilane, Butyltriisopropoxysilane, sec-Butyltrimethoxysilane, sec-Butyltriethoxysilane, sec-Butyltripropoxysilane, sec-Butyltriisopropoxysilane, tert-Butyltrimethoxysilane, tert-Butyltriethoxysilane, tert-Butyltripropoxysilane, tert-Butyltriisopropoxysilane, Cyclopropyltrimethoxysilane, Cyclopropyltriethoxysilane, Cyclopropyltripropoxysilane, Cyclopropyltriisopropoxysilane, Cyclobutyltrimethoxysilane, Cyclobutyltriethoxysilane, Cyclobutyltripropoxysilane, Cyclobutyltriisopropoxysilane, Cyclopentyltrimethoxysilane, Cyclopentyltriethoxysilane, Cyclopentyltripropoxysilane Cyclopentyltriisopropoxysilane, cyclohexyltrimethoxysilane, cyclohexyltriethoxysilane, cyclohexyltripropoxysilane, cyclohexyltriisopropoxysilane, cyclohexenyltrimethoxysilane, cyclohexenyltriethoxysilane, cyclohexenyltripropoxysilane, cyclohexenyltriisopropoxysilane, cyclohexenylethyltrimethoxysilane, cyclohexenylethyltriethoxysilane, cyclohexenylethyltripropoxysilane, cyclohexenylethyltriisopropoxysilane, cyclooctyltrimethoxysilane, cyclooctyltriethoxysilane, cyclooctyltripropoxysilane, cyclooctyltriisopropoxysilane, cyclopentadienylpropyltrimethoxysilane, cyclopentadienylpropyltriethoxysilane, cyclopentadienylpropyltripropoxysilane, cyclopentadienylpropyltriisopropoxysilane Silanes, including dicycloheptenyltrimethoxysilane, dicycloheptenyltriethoxysilane, dicycloheptenyltripropoxysilane, dicycloheptenyltriisopropoxysilane, dicycloheptenyltrimethoxysilane, dicycloheptenyltriethoxysilane, dicycloheptenyltripropoxysilane, dicycloheptenyltriisopropoxysilane, adamantyltrimethoxysilane, adamantyltriethoxysilane, adamantyltripropoxysilane, adamantyltriisopropoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, phenyltripropoxysilane, phenyltriisopropoxysilane, benzyltrimethoxysilane, benzyltriethoxysilane, benzyltripropoxysilane, benzyltriisopropoxysilane, methoxyphenyltrimethoxysilane, methoxyphenyltriethoxysilane, methoxyphenyltripropoxysilane.Methoxyphenyl triisopropoxysilane, tolyltrimethoxysilane, tolyltriethoxysilane, tolyltripropoxysilane, tolyltriisopropoxysilane, phenethyltrimethoxysilane, phenethyltriethoxysilane, phenethyltripropoxysilane, phenethyltriisopropoxysilane, naphthyltrimethoxysilane, naphthyltriethoxysilane, naphthyltripropoxysilane, naphthyltriisopropoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, methylethyldimethoxysilane, methylethyldiethoxysilane, dimethyldipropoxysilane, dimethyldiisopropoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, diethyldipropoxysilane, diethyldiisopropoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, diethyldipropoxysilane, diethyldiisopropoxysilane, dipropyldimethoxysilane, dipropyldi... Ethoxysilane, dipropyldipropoxysilane, dipropyldiisopropoxysilane, diisopropyldimethoxysilane, diisopropyldiethoxysilane, diisopropyldipropoxysilane, diisopropyldiisopropoxysilane, dibutyldimethoxysilane, dibutyldiethoxysilane, dibutyldipropoxysilane, dibutyldiisopropoxysilane, disec-butyldimethoxysilane, disec-butyldiethoxysilane, disec-butyldipropoxysilane, disec-butyldiisopropoxysilane, ditert-butyldimethoxysilane, ditert-butyldiethoxysilane, ditert-butyldipropoxysilane, ditert-butyldiisopropoxysilane, dicyclopropyldimethoxysilane, dicyclopropyldiethoxysilane, dicyclopropyldipropoxysilane, dicyclopropyldiisopropoxysilane, dicyclopropyldiisopropoxysilane, dicyclopropyldimethoxysilane Butyl dimethoxysilane, dicyclobutyl diethoxysilane, dicyclobutyl dipropoxysilane, dicyclobutyl diisopropoxysilane, dicyclopentyl dimethoxysilane, dicyclopentyl diethoxysilane, dicyclopentyl dipropoxysilane, dicyclopentyl diisopropoxysilane, dicyclohexyl dimethoxysilane, dicyclohexyl diethoxysilane, dicyclohexyl dipropoxysilane, dicyclohexyl diisopropoxysilane, dicyclohexenyl dimethoxysilane, dicyclohexenyl diethoxysilane, dicyclohexenyl dipropoxysilane, dicyclohexenyl diisopropoxysilane, dicyclohexenyl ethyl dimethoxysilane, dicyclohexenyl ethyl diethoxysilane, dicyclohexenyl ethyl dipropoxysilane, dicyclohexenyl ethyl diisopropoxysilane, dicyclooctyl dimethoxysilane Dicyclooctyldiethoxysilane, dicyclooctyldiethoxysilane, dicyclooctyldiethiopropoxysilane, dicyclopentadienylpropyldimethoxysilane, dicyclopentadienylpropyldiethoxysilane, dicyclopentadienylpropyldipropoxysilane, dicyclopentadienylpropyldiisopropoxysilane, bis(bicycloheptenyl)dimethoxysilane, bis(bicycloheptenyl)diethoxysilane, bis(bicycloheptenyl)dipropoxysilane, bis(bicycloheptenyl)diisopropoxysilane, bis(bicycloheptenyl)dimethoxysilane, bis(bicycloheptenyl)diethoxysilane, bis(bicycloheptenyl)dipropoxysilane, bis(bicycloheptenyl)diisopropoxysilane, diadamantyldimethoxysilane, diadamantyldiethoxysilane, diadamantyldipropoxysilaneDiadamyl diisopropoxysilane, diphenyl dimethoxysilane, diphenyl diethoxysilane, methylphenyl dimethoxysilane, methylphenyl diethoxysilane, diphenyl dipropoxysilane, diphenyl diisopropoxysilane, trimethylmethoxysilane, trimethylethoxysilane, dimethyl ethyl methoxysilane, dimethyl ethyl ethoxysilane, dimethyl phenyl methoxysilane, dimethyl phenyl ethoxysilane, dimethyl benzyl methoxysilane, dimethyl benzyl ethoxysilane, dimethyl phenylethyl methoxysilane, dimethyl phenylethyl ethoxysilane, etc.

[0108] Examples of the aforementioned hydrolyzable monomer (Sm) include tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, propyltrimethoxysilane, propyltriethoxysilane, isopropyltrimethoxysilane, isopropyltriethoxysilane, butyltrimethoxysilane, butyltriethoxysilane, isobutyltrimethoxysilane, isobutyltriethoxysilane, allyltrimethoxysilane, allyltriethoxysilane, cyclopentyltrimethoxysilane, cyclopentyltriethoxysilane, cyclohexyltrimethoxysilane, cyclohexyltriethoxysilane, and cyclohexenyltrimethoxysilane. Oxysilanes, cyclohexenyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, benzyltrimethoxysilane, benzyltriethoxysilane, phenethyltrimethoxysilane, phenethyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, diethylethyldimethoxysilane, methylethyldimethoxysilane, dipropyldimethoxysilane, dibutyldimethoxysilane, methylphenyldimethoxysilane, methylphenyldiethoxysilane, trimethylmethoxysilane, dimethylethylmethoxysilane, dimethylphenylmethoxysilane, dimethylbenzylmethoxysilane, dimethylphenethylmethoxysilane, etc.

[0109] The above-described R corresponds to the hydrolyzable monomer (Sm) in the compounds exemplified above. a R b and R c Other examples of the represented organic groups include organic groups having one or more carbon-oxygen single bonds or carbon-oxygen double bonds. Specifically, it refers to organic groups having one or more groups selected from the group consisting of ether bonds, ester bonds, alkoxy groups, hydroxyl groups, etc. Examples of such groups include those represented by the following general formula (Sm-R). By containing such organic groups, thermosetting properties can be improved, making it suitable for the blank photomask of the present invention. Furthermore, the adhesion to the upper photoresist film becomes good, and a highly rectangular photoresist pattern can be obtained after development.

[0110] [Chemistry 4]

[0111] (P-Q1-(S1) v1 -Q2-) u -(T) v2 -Q3-(S2) v3 -Q4- (Sm-R)

[0112] In the general formula (Sm-R), P is a hydrogen atom, a cyclic ether group, a hydroxyl group, an alkoxy group with 1 to 4 carbon atoms, an alkyl carbonyloxy group with 1 to 6 carbon atoms, or an alkyl carbonyl group with 1 to 6 carbon atoms, and Q1, Q2, Q3, and Q4 are each independently -C. q H (2q-p) P p -(In the formula, P is the same as above, p is an integer from 0 to 3, q ​​is an integer from 0 to 10 (but q = 0 indicates a single bond.), u is an integer from 0 to 3, S1 and S2 each independently represent -O-, -CO-, -OCO-, -COO-, or -OCOO-. v1, v2, and v3 each independently represent 0 or 1. T is a divalent group selected from the group consisting of divalent atoms other than carbon, alicyclic rings, aromatic rings, or heterocyclic rings. Examples of alicyclic rings, aromatic rings, or heterocyclic rings that may also contain heteroatoms such as oxygen atoms are shown below as T. The positions of T with Q2 and Q3 are not particularly limited, and can be appropriately selected considering reactivity due to steric factors or the availability of commercially available reagents used in the reaction.)

[0113] [Chemistry 5]

[0114]

[0115] Preferred examples of organic groups having one or more carbon-oxygen single or double bonds in the general formula (Sm-R) include the following. Furthermore, in the following formula, (Si) indicates the bonding site with Si.

[0116] [Chemistry 6]

[0117]

[0118] [Chemistry 7]

[0119]

[0120] In addition, as R a R b and R c Examples of organic groups include those containing silicon-silicon bonds. Specifically, the following examples can be listed.

[0121] [Chemistry 8]

[0122]

[0123] In addition, as R a R b and R c Examples of organic groups may also be organic groups having protecting groups that decompose by acid. Specifically, examples include the organic groups listed in paragraphs

[0043] to

[0048] of Japanese Patent Application Publication No. 2013-167669, and the organic groups obtained from silicon compounds shown in paragraph

[0056] of Japanese Patent Application Publication No. 2013-224279.

[0124] Additionally, as R a R b and R c Examples of organic groups may also be organic groups having fluorine atoms. Specifically, examples of organic groups obtained from silicon compounds shown in paragraphs

[0059] to

[0065] of Japanese Patent Application Publication No. 2012-53253 can be cited.

[0125] The aforementioned hydrolyzable monomer (Sm) has one, two, or three chlorine, bromine, iodine, acetoxy, methoxy, ethoxy, propoxy, or butoxy groups bonded as hydrolyzable groups on silicon (represented by (Si) in the above partial structure).

[0126] [Synthesis method of thermocrosslinkable polysiloxane (Sx)]

[0127] (Synthesis Method 1: Method using an acid catalyst)

[0128] The thermally crosslinked polysiloxane (Sx) used in this invention can be manufactured, for example, by hydrolyzing and condensing one hydrolyzable monomer (Sm) or a mixture of two or more hydrolyzable monomers (Sm) in the presence of an acid catalyst.

[0129] The acid catalysts used here can include organic acids such as formic acid, acetic acid, oxalic acid, maleic acid, methanesulfonic acid, benzenesulfonic acid, and toluenesulfonic acid, as well as inorganic acids such as hydrofluoric acid, hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid, perchloric acid, and phosphoric acid. The amount of catalyst used relative to 1 mole of monomer is 1 × 10⁻⁶. -6 ~10 moles, preferably 1×10 -5 ~5 moles, preferably 1×10 -4 ~1 mole.

[0130] When obtaining thermally crosslinked polysiloxanes (Sx) from these monomers via hydrolysis-condensation, the amount of water added should preferably be 0.01 to 100 moles per mole of hydrolytic substituents bonded to the monomers, more preferably 0.05 to 50 moles, and even more preferably 0.1 to 30 moles. Adding amounts below 100 moles results in a smaller and more economical reaction apparatus.

[0131] As an example of the operating method, the hydrolysis-condensation reaction can be initiated by adding a monomer to an aqueous catalyst solution. This can be done by adding an organic solvent to the aqueous catalyst solution, diluting the monomer with an organic solvent, or both. The reaction temperature is 0–100°C, preferably 5–50°C. It is preferable to maintain the temperature at 5–50°C during the dropwise addition of the monomer, and then allow it to mature at 20–50°C.

[0132] Suitable organic solvents for adding to aqueous catalyst solutions or for diluting monomers include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol, acetone, acetonitrile, tetrahydrofuran, toluene, hexane, ethyl acetate, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, methyl pentyl ketone, butanediol monomethyl ether, propylene glycol monomethyl ether, ethylene glycol monomethyl ether, butanediol monoethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl ether, propylene glycol dimethyl ether, diethylene glycol dimethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, tert-butyl acetate, tert-butyl propionate, propylene glycol monotert-butyl ether acetate, γ-butyrolactone, and mixtures thereof.

[0133] Among these solvents, water-soluble solvents are preferred. Examples include alcohols such as methanol, ethanol, 1-propanol, and 2-propanol; polyols such as ethylene glycol and propylene glycol; polyol condensate derivatives such as butanediol monomethyl ether, propylene glycol monomethyl ether, ethylene glycol monomethyl ether, butanediol monoethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl ether, butanediol monopropyl ether, propylene glycol monopropyl ether, and ethylene glycol monopropyl ether; acetone; acetonitrile; and tetrahydrofuran. Solvents with boiling points below 100°C are particularly preferred.

[0134] Furthermore, the amount of organic solvent used relative to 1 mole of monomer is 0–1,000 ml, and preferably 0–500 ml. Using less organic solvent results in a smaller reaction vessel, which is more economical.

[0135] Subsequently, a neutralization reaction of the catalyst is carried out as needed to obtain an aqueous solution of the reaction mixture. At this point, the amount of basic substance used for neutralization should preferably be 0.1 to 2 equivalents relative to the acid used in the catalyst. This basic substance can be any substance that exhibits basicity in water.

[0136] Then, byproducts such as alcohols generated during the hydrolysis-condensation reaction should be removed from the reaction mixture by means of vacuum removal. The temperature at which the reaction mixture is heated depends on the type of organic solvent added and the type of alcohols generated in the reaction, and is preferably 0–100°C, more preferably 10–90°C, and even more preferably 15–50°C. Furthermore, the vacuum pressure at this time will vary depending on the type of organic solvent and alcohols to be removed, the venting device, the condensation device, and the heating temperature, and is preferably below atmospheric pressure, more preferably below 80 kPa absolute pressure, and even more preferably below 50 kPa absolute pressure. Although it is difficult to know the exact amount of alcohol removed at this time, it is desirable to remove approximately 80% by mass or more of the alcohols generated.

[0137] The acid catalyst used in the hydrolysis-condensation can then be removed from the reaction mixture. As a method for removing the acid catalyst, water is mixed with a solution of the thermally crosslinked polysiloxane, and the thermally crosslinked polysiloxane is extracted using an organic solvent. The organic solvent used in this process should preferably be capable of dissolving the thermally crosslinked polysiloxane and separating into two layers when mixed with water. Examples include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol, acetone, tetrahydrofuran, toluene, hexane, ethyl acetate, cyclohexanone, methylpentyl ketone, butanediol monomethyl ether, propylene glycol monomethyl ether, ethylene glycol monomethyl ether, butanediol monoethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl ether, butanediol monopropyl ether, propylene glycol monopropyl ether, ethylene glycol monopropyl ether, propylene glycol dimethyl ether, diethylene glycol dimethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, tert-butyl acetate, tert-butyl propionate, propylene glycol monotert-butyl ether acetate, γ-butyrolactone, methyl isobutyl ketone, cyclopentyl methyl ether, and mixtures thereof.

[0138] Furthermore, mixtures of water-soluble organic solvents and water-poorly soluble organic solvents may also be used. Examples include, but are preferably, mixtures of methanol and ethyl acetate, ethanol and ethyl acetate, 1-propanol and ethyl acetate, 2-propanol and ethyl acetate, butanediol monomethyl ether and ethyl acetate, propylene glycol monomethyl ether and ethyl acetate, ethylene glycol monomethyl ether and ethyl acetate, butanediol monoethyl ether and ethyl acetate, propylene glycol monoethyl ether and ethyl acetate, ethylene glycol monoethyl ether and ethyl acetate, butanediol monopropyl ether and ethyl acetate, and propylene glycol monopropyl ether and ethyl acetate. Mixtures of ethylene glycol monopropyl ether and ethyl acetate, methanol and methyl isobutyl ketone, ethanol and methyl isobutyl ketone, 1-propanol and methyl isobutyl ketone, 2-propanol and methyl isobutyl ketone, propylene glycol monomethyl ether and methyl isobutyl ketone, ethylene glycol monomethyl ether and methyl isobutyl ketone, propylene glycol monoethyl ether and methyl isobutyl ketone, ethylene glycol monoethyl ether and methyl isobutyl ketone, propylene glycol monopropyl ether and methyl isobutyl ketone, methanol and ethyl acetate. Mixtures of cyclopentyl methyl ethers, ethanol-cyclopentyl methyl ethers, 1-propanol-cyclopentyl methyl ethers, 2-propanol-cyclopentyl methyl ethers, propylene glycol monomethyl ether-cyclopentyl methyl ethers, ethylene glycol monomethyl ether-cyclopentyl methyl ethers, propylene glycol monoethyl ether-cyclopentyl methyl ethers, ethylene glycol monoethyl ether-cyclopentyl methyl ethers, propylene glycol monopropyl ether-cyclopentyl methyl ethers, ethylene glycol monopropyl ether-cyclopentyl methyl ethers, methanol-propylene glycol methyl ether acetate mixtures, ethanol-propylene glycol Mixtures of methyl ether acetates, mixtures of 1-propanol-propylene glycol methyl ether acetates, mixtures of 2-propanol-propylene glycol methyl ether acetates, mixtures of propylene glycol monomethyl ether-propylene glycol methyl ether acetates, mixtures of ethylene glycol monomethyl ether-propylene glycol methyl ether acetates, mixtures of propylene glycol monoethyl ether-propylene glycol methyl ether acetates, mixtures of ethylene glycol monoethyl ether-propylene glycol methyl ether acetates, mixtures of propylene glycol monopropyl ether-propylene glycol methyl ether acetates, and mixtures of ethylene glycol monopropyl ether-propylene glycol methyl ether acetates, etc., are not limited to these combinations.

[0139] In addition, the mixing ratio of water-soluble organic solvent and water-poorly soluble organic solvent should be appropriately selected. The ratio of water-soluble organic solvent to water-poorly soluble organic solvent should be 0.1 to 1,000 parts by mass relative to 100 parts by mass, preferably 1 to 500 parts by mass, and more preferably 2 to 100 parts by mass.

[0140] Then, rinsing can be performed using neutral water. Deionized water or ultrapure water is generally sufficient. The amount of water relative to 1L of the thermally crosslinked polysiloxane solution should be 0.01–100L, more preferably 0.05–50L, and even more preferably 0.1–5L. The rinsing method involves adding both solutions to the same container, stirring to mix, allowing to stand, and then separating the water layers. One or more rinses are sufficient; however, rinsing more than 10 times may not achieve the desired cleaning effect, so approximately 1–5 rinses are preferable.

[0141] Other methods for removing acid catalysts include using ion exchange resins or neutralizing them with epoxides such as ethylene oxide and propylene oxide, followed by immediate removal. These methods can be appropriately selected in conjunction with the acid catalyst used in the reaction.

[0142] Sometimes, due to the water washing operation, some of the thermally crosslinked polysiloxane escapes into the water layer, achieving an effect substantially equivalent to the separation operation. Therefore, the number of water washes or the amount of washing water should be appropriately selected based on the catalyst removal effect and the separation effect.

[0143] Either a thermally crosslinked polysiloxane solution containing residual acid catalyst or a thermally crosslinked polysiloxane solution with the acid catalyst removed is subjected to solvent exchange under reduced pressure to obtain the desired thermally crosslinked polysiloxane solution. The solvent exchange temperature depends on the type of reaction solvent and extraction solvent to be removed, and is preferably 0–100°C, more preferably 10–90°C, and even more preferably 15–50°C. Furthermore, the reduced pressure varies depending on the type of extraction solvent to be removed, the exhaust system, the condenser, and the heating temperature, and is preferably below atmospheric pressure, more preferably below 80 kPa absolute pressure, and even more preferably below 50 kPa absolute pressure.

[0144] At this time, sometimes the thermally crosslinked polysiloxane becomes unstable due to a change in solvent. This can occur due to the compatibility between the final solvent and the thermally crosslinked polysiloxane. To prevent this, a mono- or di-ortho-ol having a cyclic ether as a substituent, as described in Japanese Patent Application Publication No. 2009-126940, paragraphs

[0181] to

[0182] , can be added as a stabilizer. The amount added is 0 to 25 parts by mass relative to 100 parts by mass of the thermally crosslinked polysiloxane in the solution before solvent exchange, preferably 0 to 15 parts by mass, more preferably 0 to 5 parts by mass, and preferably 0.5 parts by mass or more when added. If necessary, a mono- or di-ortho-ol having a cyclic ether as a substituent can be added to the solution before solvent exchange and a solvent exchange operation can be performed.

[0145] If thermally crosslinked polysiloxanes are concentrated to a certain concentration or higher, they may undergo further condensation reactions, potentially transforming into a state where they are no longer soluble in organic solvents. Therefore, it is advisable to obtain a solution of appropriate concentration. Furthermore, if the solution is too dilute, the amount of solvent becomes excessive; thus, obtaining a solution of appropriate concentration is economically preferable. The appropriate concentration at this point is preferably 0.1% to 20% by mass.

[0146] The preferred final solvent for adding to the thermally crosslinkable polysiloxane solution is an alcohol-based solvent, particularly ideally a monoalkyl ether derivative of ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, butanediol, etc. Specifically, butanediol monomethyl ether, propylene glycol monomethyl ether, ethylene glycol monomethyl ether, butanediol monoethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl ether, butanediol monopropyl ether, propylene glycol monopropyl ether, ethylene glycol monopropyl ether, diacetone alcohol, etc., are preferred.

[0147] As long as these solvents are the main components, non-alcoholic solvents can also be added as auxiliary solvents. Examples of such auxiliary solvents include acetone, tetrahydrofuran, toluene, hexane, ethyl acetate, cyclohexanone, methyl pentyl ketone, propylene glycol dimethyl ether, diethylene glycol dimethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, tert-butyl acetate, tert-butyl propionate, propylene glycol monotert-butyl ether acetate, γ-butyrolactone, methyl isobutyl ketone, cyclopentyl methyl ether, etc.

[0148] In addition, as another reaction operation using an acid catalyst, water or an aqueous organic solvent can be added to the monomer or its organic solvent to initiate the hydrolysis reaction. In this case, the catalyst can be added to the monomer or its organic solvent, or to water or an aqueous organic solvent. The reaction temperature is 0–100°C, preferably 10–50°C. A preferred method is to heat to 10–50°C during the dropwise addition of water, and then raise the temperature to 20–50°C to allow it to mature.

[0149] When using organic solvents, water-soluble solvents are preferred. Examples include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol, acetone, tetrahydrofuran, acetonitrile, butanediol monomethyl ether, propylene glycol monomethyl ether, ethylene glycol monomethyl ether, butanediol monoethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl ether, butanediol monopropyl ether, propylene glycol monopropyl ether, ethylene glycol monopropyl ether, propylene glycol dimethyl ether, diethylene glycol dimethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether, and polyol condensate derivatives thereof, as well as mixtures thereof.

[0150] The amount of organic solvent used is 0 to 1,000 ml relative to 1 mole of monomer, and preferably 0 to 500 ml. Using less organic solvent results in a smaller and more economical reaction vessel. The resulting reaction mixture can be post-processed in the same manner as described above to obtain thermally crosslinked polysiloxanes.

[0151] (Synthesis Method 2: Method using an alkaline catalyst)

[0152] In addition, thermally crosslinked polysiloxanes (Sx) can also be manufactured by hydrolyzing and condensing one or more hydrolyzable monomers (Sm) in the presence of an alkaline catalyst.

[0153] The base catalysts used here include, for example, methylamine, ethylamine, propylamine, butylamine, ethylenediamine, hexamethylenediamine, dimethylamine, diethylamine, ethylmethylamine, trimethylamine, triethylamine, tripropylamine, tributylamine, cyclohexylamine, dicyclohexylamine, monoethanolamine, diethanolamine, dimethylmonoethanolamine, monomethyldiethanolamine, triethanolamine, diazabicyclooctane, diazabicyclononene, diazabicycloundecene, hexamethylenetetramine, aniline, N,N-dimethylaniline, pyridine, N,N-dimethylaminopyridine, pyrrole, piperazine, pyrrolidine, piperidine, methylpyridine, tetramethylammonium hydroxide, choline hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, ammonia, lithium hydroxide, sodium hydroxide, potassium hydroxide, barium hydroxide, calcium hydroxide, etc. The amount of catalyst used relative to 1 mole of silicon monomer is 1 × 10⁻⁶. -6 moles ~ 10 moles, preferably 1 × 10 -5 5 moles, preferably 1×10 -4 One mole ~ 1 mole.

[0154] When obtaining thermally crosslinked polysiloxanes from the above monomers via hydrolysis-condensation, the amount of water should preferably be 0.1 to 50 moles per mole of hydrolytic substituents bonded to the monomer. Adding 50 moles or less reduces the size of the apparatus used in the reaction, making it more economical.

[0155] As an example of the operating method, the addition of a monomer to an aqueous catalyst solution can be used to initiate the hydrolysis-condensation reaction. At this time, an organic solvent can be added to the aqueous catalyst solution, or the monomer can be diluted with an organic solvent, or both. The reaction temperature is 0–100°C, preferably 5–50°C. It is preferable to maintain the temperature at 5–50°C during the dropwise addition of the monomer, and then allow it to mature at 20–50°C.

[0156] As an organic solvent that can be added to an aqueous solution of a base catalyst or used to dilute the monomer, it is suitable to use the same organic solvent as that exemplified as that that can be added to an aqueous solution of an acid catalyst. Furthermore, to ensure a more economical reaction, the amount of organic solvent used should be 0 to 1,000 ml relative to 1 mole of the monomer.

[0157] Subsequently, if necessary, a neutralization reaction with a catalyst is carried out to obtain an aqueous solution of the reaction mixture. At this point, the amount of acidic substance used in the neutralization should preferably be 0.1 to 2 equivalents relative to the basic substance used with the catalyst. This acidic substance can be any substance that exhibits acidity in water.

[0158] Then, byproducts such as alcohols generated during the hydrolysis-condensation reaction should be removed from the reaction mixture by means of vacuum removal. The temperature at which the reaction mixture is heated depends on the type of organic solvent added and the type of alcohol produced in the reaction, and is preferably 0–100°C, more preferably 10–90°C, and even more preferably 15–50°C. Furthermore, the vacuum level at this time will vary depending on the type of organic solvent and alcohol to be removed, the venting device, the condensation device, and the heating temperature, and is preferably below atmospheric pressure, more preferably below 80 kPa absolute pressure, and even more preferably below 50 kPa absolute pressure. The amount of alcohol removed at this time is difficult to determine accurately, but it is desirable to remove approximately 80% by mass or more of the alcohol produced.

[0159] Then, in order to remove the alkaline catalyst used in the hydrolysis condensation, the thermally crosslinked polysiloxane is extracted with an organic solvent. The organic solvent used at this time should preferably be capable of dissolving the thermally crosslinked polysiloxane and should separate into two layers if mixed with water. Examples include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol, acetone, tetrahydrofuran, toluene, hexane, ethyl acetate, cyclohexanone, methylpentyl ketone, propylene glycol monomethyl ether, ethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl ether, propylene glycol monopropyl ether, ethylene glycol monopropyl ether, propylene glycol dimethyl ether, diethylene glycol dimethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, tert-butyl acetate, tert-butyl propionate, propylene glycol monotert-butyl ether acetate, γ-butyrolactone, methyl isobutyl ketone, cyclopentyl methyl ether, and mixtures thereof.

[0160] Furthermore, a mixture of water-soluble organic solvents and water-insoluble organic solvents may also be used.

[0161] Specific examples of organic solvents used when removing alkaline catalysts may be the same as those specifically exemplified by users when removing acid catalysts, or a mixture of water-soluble organic solvents and water-difficult organic solvents.

[0162] In addition, the mixing ratio of water-soluble organic solvent and water-insoluble organic solvent should be appropriately selected. The ratio of water-soluble organic solvent to 100 parts by mass of water-soluble organic solvent should be 0.1 to 1,000 parts by mass, preferably 1 to 500 parts by mass, and more preferably 2 to 100 parts by mass.

[0163] Then, rinse with neutral water. Deionized water or ultrapure water is generally sufficient. The amount of water relative to 1L of the thermally crosslinked polysiloxane solution is 0.01–100L, preferably 0.05–50L, and more preferably 0.1–5L. The rinsing method involves adding both solutions to the same container, stirring to mix, and then allowing the mixture to stand to separate the water layers. One or more rinses are sufficient; however, rinsing more than 10 times may not achieve the desired cleaning effect, so approximately 1–5 rinses are recommended.

[0164] The final solvent is added to the cleaned thermally crosslinked polysiloxane solution, and the desired thermally crosslinked polysiloxane solution is obtained by solvent exchange under reduced pressure. The solvent exchange temperature depends on the type of extraction solvent to be removed, and is preferably 0–100°C, more preferably 10–90°C, and even more preferably 15–50°C. Furthermore, the reduced pressure varies depending on the type of extraction solvent to be removed, the exhaust system, the condenser, and the heating temperature, and is preferably below atmospheric pressure, more preferably below 80 kPa absolute pressure, and even more preferably below 50 kPa absolute pressure.

[0165] Preferred final solvents added to the thermally crosslinked polysiloxane solution are alcohol-based solvents, particularly monoalkyl ethers of ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, etc. Specifically, monoalkyl ethers of propylene glycol monomethyl ether, ethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl ether, propylene glycol monopropyl ether, ethylene glycol monopropyl ether, diacetone alcohol, etc., are preferred.

[0166] In addition, as another reaction operation using a base catalyst, the addition of water or an aqueous organic solvent to the monomer or its organic solution can be cited as an example to initiate the hydrolysis reaction. In this case, the catalyst can be added to the monomer or its organic solution, or to water or an aqueous organic solvent. The reaction temperature is 0–100°C, preferably 10–50°C. A preferred method is to heat to 10–50°C during the dropwise addition of water, and then raise the temperature to 20–50°C to allow it to mature.

[0167] For organic solvents that can be used as monomeric organic solutions or aqueous organic solvents, those that are preferably water-soluble include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol, acetone, tetrahydrofuran, acetonitrile, propylene glycol monomethyl ether, ethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl ether, propylene glycol monopropyl ether, ethylene glycol monopropyl ether, propylene glycol dimethyl ether, diethylene glycol dimethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether, and polyol condensate derivatives thereof, as well as mixtures thereof.

[0168] The molecular weight of the thermally crosslinked polysiloxane obtained by the above-described synthesis method 1 or 2 can be adjusted not only by the choice of monomer but also by controlling the reaction conditions during polymerization. A weight-average molecular weight of 100,000 or less is preferable, more preferably 200–50,000, and even more preferably 300–30,000. As long as the weight-average molecular weight is below 100,000, no foreign matter or coating spots will be generated. Furthermore, the above-mentioned weight-average molecular weight data is expressed by conversion from polystyrene to molecular weight using gel permeation chromatography (GPC) with RI as the detector, tetrahydrofuran as the dissolution solvent, and polystyrene as the standard.

[0169] (Cross-linking catalyst)

[0170] In the composition for forming silicon-containing hard mask films, one or more crosslinking catalysts may also be incorporated. Examples of suitable crosslinking catalysts include compounds represented by the following general formula (Xc0). By incorporating such crosslinking catalysts, thermosetting properties can be further improved.

[0171] L a H b A(Xc0)

[0172] (In the formula, L represents lithium, sodium, potassium, rubidium, cesium, sulfonium, zinc, phosphorus, or ammonium. A represents a non-nucleophilic relative ion. a is an integer greater than or equal to 1, b is an integer greater than or equal to 0 or 1, and a+b represents the valence of the non-nucleophilic relative ion.)

[0173] Regarding the specific compounds represented by the general formula (Xc0) used as crosslinking catalysts in this invention, examples include sulfonium salts of the following general formula (Xc-1), monium salts of the following general formula (Xc-2), phosphonium salts of the following general formula (Xc-3), ammonium salts of the following general formula (Xc-4), alkali metal salts, etc., or polysiloxanes (Xc-10) having ammonium salts, sulfonium salts, phosphonium salts, or monium salts as part of their structure. Specifically, materials described in paragraphs

[0124] to

[0163] of Japanese Patent Application Publication No. 2020-118960 may be added.

[0174] [Chemistry 9]

[0175]

[0176] [Chemistry 10]

[0177]

[0178] (where R is in the formula) 204 R 205 R 206 and R 207 Each group independently represents a linear, branched, or cyclic alkyl, alkenyl, oxoalkyl, or oxoalkenyl group having 1 to 12 carbon atoms; a substituted or unsubstituted aryl group having 6 to 20 carbon atoms; or an aralkyl or aryloxoalkyl group having 7 to 12 carbon atoms. Some or all of the hydrogen atoms in these groups may also be substituted by alkoxy groups, etc. Furthermore, R 205 With R 206 It can also form a ring; in the case of a ring formation, R 205 and R 206 Each represents an alkylene group having 1 to 6 carbon atoms. A - Indicates a non-nucleophilic relative ion. R 208 R 209 R 210 and R 211 Is with R 204 R 205 R 206 and R 207 Similarly, it can also be a hydrogen atom. R 208 and R 209 、or R 208 R 209 and R 210 It can also form a ring; in the case of a ring formation, R 208 and R 209 Or R 208 R 209 and R 210 This refers to alkylene groups having 3 to 10 carbon atoms.

[0179] The aforementioned crosslinking catalysts (Xc-1), (Xc-2), (Xc-3), (Xc-4), and / or (Xc-10) can be used alone or in combination of two or more. The amount of crosslinking catalyst added relative to 100 parts by weight of the base polymer (e.g., the thermally crosslinked polysiloxane (Sx) obtained by the above method) is preferably 0.01 to 50 parts by weight, more preferably 0.1 to 40 parts by weight.

[0180] [Other ingredients]

[0181] The following raw materials may also be incorporated into the silicon-containing hard mask film forming composition used in this invention.

[0182] (Acid generating agent)

[0183] The composition for forming silicon-containing hard mask films may also incorporate one or more acid-generating agents. As the acid-generating agent, any substance that functions as an acid precursor, such as a thermal acid-generating agent, a photoacid-generating agent, or an acid-increasing agent, can be used. In this invention, it is more preferable that the incorporated acid-generating agent be a sulfonate salt, or a photoacid-generating agent that generates acid through the action of high-energy rays. Specifically, the materials described in paragraphs

[0061] to

[0085] of Japanese Patent Application Publication No. 2007-199653 may be added, but are not limited to these.

[0184] The above-mentioned acid generating agents can be used alone or in combination of two or more. When adding an acid generating agent, the amount added relative to 100 parts of thermally crosslinked polysiloxane is preferably 0.05 to 50 parts, more preferably 0.1 to 10 parts.

[0185] (Cross-linking agent)

[0186] For compositions used in forming silicon-containing hard mask films, a crosslinking agent may be added to further improve thermosetting properties. There are no particular limitations on the crosslinking agent; various known systems of crosslinking agents can be widely used. Examples include melamine-based crosslinking agents, acetylenide-based crosslinking agents, benzoguanamine-based crosslinking agents, urea-based crosslinking agents, β-hydroxyalkylamide-based crosslinking agents, isocyanurate-based crosslinking agents, aziridine-based crosslinking agents, oxazoline-based crosslinking agents, epoxy-based crosslinking agents, and phenol-based crosslinking agents. One or more of the above crosslinking agents may be used alone. The amount of crosslinking agent added relative to 100 parts of the above-mentioned composition for forming silicon-containing hard mask films is preferably 5 to 50 parts, more preferably 10 to 40 parts, and even more preferably 10 to 30 parts.

[0187] (Organic acids)

[0188] To improve the stability of the composition used in forming silicon-containing hard mask films, it is advisable to add a monovalent or divalent or higher organic acid with 1 to 30 carbon atoms. Examples of acids added at this time include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, oleic acid, stearic acid, linoleic acid, perilla oleic acid, benzoic acid, phthalic acid, isophthalic acid, terephthalic acid, salicylic acid, trifluoroacetic acid, monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, oxalic acid, malonic acid, methylmalonic acid, ethylmalonic acid, propylmalonic acid, butylmalonic acid, dimethylmalonic acid, diethylmalonic acid, succinic acid, methylsuccinic acid, glutaric acid, adipic acid, iconic acid, maleic acid, fumaric acid, citrate, and citric acid. Oxalic acid, maleic acid, formic acid, acetic acid, propionic acid, and citric acid are particularly suitable. In addition, to maintain stability, two or more acids can be mixed for use.

[0189] The amount of organic acid added is 0.001 to 25 parts by mass relative to 100 parts by mass of thermally crosslinked polysiloxane contained in the composition for forming silicon hard mask film, preferably 0.01 to 15 parts by mass, and more preferably 0.1 to 5 parts by mass.

[0190] Alternatively, the organic acids mentioned above can be converted to the pH of the components used to form silicon hard mask films, and can be mixed in such a way that it is preferably 0≤pH≤7, more preferably 0.3≤pH≤6.5, and even more preferably 0.5≤pH≤6.

[0191] (solvent)

[0192] In order to improve coatability, the composition for forming silicon hard mask films may also contain a coating solvent.

[0193] The solvent used as a coating solvent for the composition of the silicon-containing hard mask film is preferably an organic solvent used directly in the manufacture of the aforementioned silicon-containing compound, and particularly preferably a monoalkyl ether of ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, etc. Specifically, an organic solvent selected from propylene glycol monomethyl ether, ethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl ether, propylene glycol monopropyl ether, and ethylene glycol monopropyl ether is preferred, and may be further diluted as needed.

[0194] Furthermore, in addition to the aforementioned solvent, known stabilizing solvent components such as water may also be added. In a blank photomask measuring 152 mm (6 inches) square, in order to form a silicon oxide material layer with a film thickness of 1 to 10 nm, the total amount of solvent including water used is preferably 1,000 to 250,000 parts by weight relative to 100 parts by weight of the thermally crosslinked polysiloxane, and particularly preferably 10,000 to 200,000 parts by weight.

[0195] (Stabilizer)

[0196] In addition, a stabilizer can be added to the composition for forming a silicon-containing hard mask film. A mono- or di- or more alcohol having a cyclic ether as a substituent can be added as a stabilizer. In particular, if the stabilizer described in paragraphs

[0181] to

[0182] of Japanese Patent Application Publication No. 2009-126940 is added, the stability of the composition for forming a silicon-containing hard mask film can be improved.

[0197] The amount of stabilizer used relative to 100 parts by weight of the thermally crosslinked polysiloxane (Sx) of the base polymer is preferably 0 to 25 parts by weight, particularly preferably 0 to 5 parts by weight, and preferably more than 0.5 parts by weight when added.

[0198] (surfactant)

[0199] Furthermore, surfactants may be incorporated into the composition as needed. Specifically, the material described in paragraph

[0185] of Japanese Patent Application Publication No. 2009-126940 may be added.

[0200] The amount of surfactant used should preferably be 0 to 10 parts by weight relative to 100 parts by weight of the thermally crosslinked polysiloxane (Sx) of the base polymer, and more preferably 0 to 5 parts by weight.

[0201] [Photoresist film]

[0202] A photoresist film is formed on a silicon-containing hard mask film. The photoresist used here depends on the pattern exposure method. To form fine patterns as with the blank photomask of this invention, a conventional electron beam exposure method is used; therefore, chemically amplified electron beam photoresist utilizing aromatic resins is generally used. This photoresist is used in positive and negative types depending on the type of pattern. The photoresist film is patterned by an electron beam, and the photoresist undergoes a predetermined post-irradiation heating and development step to obtain the photoresist pattern.

[0203] As described above, the blank photomask of the present invention contains a silicon-containing hard mask film that functions as a hard mask film, enabling the transfer of fine resist patterns to the absorber layer with high precision. Furthermore, the silicon-containing hard mask film can be formed in a temperature range of 50°C to 180°C, thus preventing interlayer mixing of multiple reflective layers and improving the transfer accuracy of the resist pattern. In other words, by using the blank photomask of the present invention, a photomask containing an absorber layer with fine patterns formed with high precision can be provided without degrading the reflectivity of EUV light. In other words, the blank photomask of the present invention is a blank photomask containing a silicon-containing hard mask film that functions as a hard mask when the absorber layer is processed by dry etching, and also contributes to improving the resolution of the resist pattern.

[0204] <Method for manufacturing blank photomasks>

[0205] The method for manufacturing the blank photomask of the present invention includes the following steps:

[0206] Prepare substrate,

[0207] A multilayer reflective film layer for reflecting EUV light is formed on the substrate.

[0208] An absorber layer that absorbs EUV light is formed on the multilayer reflective film.

[0209] A coating is obtained by directly or indirectly coating a silicon-containing hard mask film forming composition that is cured at a temperature of 50°C to 180°C onto the absorber layer, and then curing the coating at a temperature of 50°C to 180°C to form a silicon-containing hard mask film.

[0210] A photoresist film is formed on the silicon-containing hard mask film.

[0211] The multilayer reflective film, any protective film, absorber layer, first layer of any hard mask (etched mask film), and any conductive film described above can be formed, for example, by ion beam sputtering or magnetron sputtering.

[0212] The aforementioned silicon-containing hard mask film is formed by coating a silicon-containing hard mask forming composition (e.g., the aforementioned silicon-containing hard mask forming composition) directly or indirectly onto the absorber layer by means of a method such as spin coating, and then curing the coating film at a temperature of 50°C to 180°C.

[0213] After a coating is formed by spin coating or similar methods, it is baked to allow the organic solvent to evaporate and harden. The baking temperature is set at 50–180°C, more preferably 80–170°C, and even more preferably 100–150°C. The baking time is preferably 10–3,600 seconds, more preferably 300 to 2,400 seconds, and even more preferably 600 to 1,200 seconds.

[0214] As long as the baking conditions are such, the periodic structure of the multilayer reflective film formed on the lower layer of the silicon-containing hard mask film will not be disturbed. The hardened film of the silicon-containing hard mask film with sufficient density of Si-O-Si crosslinking can be formed directly or indirectly on the absorber layer, so high etching resistance to chlorine-based dry etching conditions can be obtained.

[0215] The thickness of the aforementioned silicon-containing hard mask film, while also depending on the thickness of the upper resist film or the thickness of the first layer of the lower hard mask film, is preferably 1–50 nm, more preferably 5–30 nm, and especially preferably 10–25 nm. As long as the film thickness is within such a range, sufficient etching resistance is provided, thus enabling the resist pattern to be transferred to the absorber layer or the first layer of the hard mask film with high precision.

[0216] The silicon content in the aforementioned silicon-containing hard mask film should preferably be at least 5%, more preferably at least 10%, and even more preferably at least 30%. As long as the film contains silicon in such a proportion, it exhibits excellent curing properties, thus providing a more reliable silicon-containing hard mask film that can be cured at temperatures between 50°C and 180°C. Furthermore, high etching resistance to chlorine-based dry etching conditions can be obtained.

[0217] The upper limit of the silicon content in the aforementioned silicon-containing hard mask film should preferably be below 50%, and more preferably below 45%. As long as the film contains silicon in such a proportion, for example, after dry etching a Cr-containing hard mask, the silicon-containing hard mask film remaining on the Cr-containing hard mask film pattern can be easily removed.

[0218] Photoresist films can be formed by coating methods such as spin coating.

[0219] The blank photomask of the present invention described above can be manufactured using the same method. However, the blank photomask of the present invention can also be manufactured using methods other than those described above.

[0220] <Processing Methods for Blank Photomasks>

[0221] The method for processing a blank photomask of the present invention is characterized by comprising the following steps:

[0222] (i-1) An electron beam is irradiated onto the blank photomask of the present invention, and then developed using a developer to form a photoresist pattern on the photoresist film.

[0223] (i-2) The silicon-containing film pattern is formed on the silicon-containing hard mask film by etching using the photoresist pattern as a mask.

[0224] (i-3) The absorber layer is processed directly or indirectly by etching the silicon-containing film pattern as a mask.

[0225] By using this blank photomask processing method, a silicon-containing hard mask film, which exhibits superior dry etching resistance to chlorine gases compared to photoresist films, can be used as the hard mask. This allows for high-precision transfer of the resist pattern to the absorber layer of the blank photomask. Furthermore, the silicon-containing hard mask film can be formed within a temperature range of 50°C to 180°C, thus preventing interlayer mixing of multiple reflective layers and improving the transfer accuracy of the resist pattern. In other words, by using the blank photomask processing method of this invention, the reflectivity of EUV light is not degraded, and a photomask containing an absorber layer with finely patterned absorbers can be provided.

[0226] If a specific example of the processing method for the blank photomask of the present invention is to be described, it will be as follows.

[0227] First, a substrate is formed, a multilayer reflective film layer on the substrate that reflects EUV light, a protective film on the multilayer reflective film layer to protect the multilayer reflective film layer, an absorber layer on the protective film layer to absorb the exposure light, and a Cr-containing hard mask film on the absorber layer layer that functions as the first layer of a hard mask when the absorber layer is patterned by dry etching.

[0228] Then, the previously described composition for forming a silicon-containing hard mask is coated onto the Cr-containing hard mask film, and a hardened film of the silicon-containing hard mask film is formed by baking at a temperature of 50°C to 180°C. That is, a silicon-containing hard mask film is formed directly or indirectly on the absorber layer. Then, a photoresist film is formed on the silicon-containing hard mask film. A blank photomask is thus obtained.

[0229] For the resist film of the blank photomask, an electron beam is used to irradiate the pattern, and then the resist pattern is formed through heating and development steps.

[0230] The obtained resist pattern is first transferred to a silicon-containing hard mask film by dry etching. The dry etching conditions can be fluorine-based dry etching using commonly used fluorine-containing gas conditions. Examples of fluorine-containing gases include fluorine gas, carbon- and fluorine-containing gases such as CF4, CHF3, and C2F6, sulfur- and fluorine-containing gases such as SF6, and even mixtures of fluorine-free gases such as helium and nitrogen with fluorine-containing gases. Furthermore, gases such as oxygen can be added as needed.

[0231] Then, the photoresist is stripped off, or left behind, and the resulting silicon-containing hard mask pattern is used as a hard mask to transfer the pattern onto a Cr-containing hard mask. The hard etching used here can be chlorine-based dry etching. For example, commonly used oxygen-containing chlorine-based dry etching can be used as the dry etching condition; for instance, the chlorine to oxygen mixing ratio (Cl2 gas: O2 gas) can be set to 1:2 to 20:1 by volume flow rate. Depending on the requirements, a gas mixed with a passive gas such as helium can be used for dry etching. Silicon-containing hard masks have higher resistance to chlorine-based dry etching than photoresist films; therefore, by using silicon-containing hard masks as hard masks, the photoresist pattern can be transferred to the Cr hard mask with high precision.

[0232] The Cr hard mask film pattern is used as a hard mask, and the pattern is transferred to the absorber layer. The dry etching used here can be a fluorine-based dry etching performed under common fluorine-containing gas conditions. Examples of fluorine-containing gases include fluorine gas, carbon and fluorine-containing gases such as CF4, CHF3, and C2F6, sulfur and fluorine-containing gases such as SF6, and further, mixtures of fluorine-free gases such as helium and nitrogen with fluorine-containing gases. In addition, gases such as oxygen can be added as needed. The silicon-containing hard mask film remaining on the Cr hard mask film can be removed by the above-described fluorine-based dry etching. Furthermore, before the above-described fluorine-based dry etching, wet etching can also be performed in the same manner as for general SOG films.

[0233] The Cr hard mask film remaining on the absorber layer can be removed using chlorine-based dry etching. The protective film formed on the multilayer reflective film is resistant to chlorine-based dry etching, so the Cr hard mask film can be removed without damaging the multilayer reflective film.

[0234] The above illustrates an example of indirectly forming a silicon-containing hard mask film by spacing Cr hard mask films on the absorber layer. However, the present invention can also directly form a silicon-containing hard mask film on the absorber layer. In this case, the silicon-containing hard mask film pattern can be used as a mask for etching the absorber layer.

[0235] Example

[0236] The present invention will be specifically illustrated below with examples of synthesis, embodiments, and comparative examples, but the invention is not limited thereto by these descriptions. Furthermore, in the following examples, % represents mass%, and molecular weight Mw is the weight-average molecular weight of polystyrene as determined by GPC.

[0237] [Synthesis example 1]

[0238] A mixture of 120 g methanol, 0.1 g 10% nitric acid, and 60 g deionized water was mixed with 30.6 g of compound (101), 38.1 g of compound (102), and 5.9 g of compound (110). The mixture was kept at 40 °C for 12 hours to allow for hydrolysis and condensation. After the reaction was complete, 600 g propylene glycol ethyl ether (PGEE) was added. The water supplied for hydrolysis and condensation, as well as the byproduct alcohol, were distilled off under reduced pressure to obtain 440 g of a PGEE solution of polysiloxane compound 1 (compound concentration 10%). The polystyrene-converted molecular weight of polysiloxane compound 1 was determined to be Mw = 2,900.

[0239] [Synthesis Examples 2 to 8]

[0240] Using the same conditions as in Synthesis Example 1 and the monomers shown in Table 1, [Synthesis Example 2] to [Synthesis Example 8] were carried out to obtain the respective target compounds (polysiloxane compounds 2 to 8).

[0241] [Table 1]

[0242] Synthesis example reaction raw materials Mw 1 Compound (101): 30.6g, Compound (102): 38.1g, Compound (110): 5.9g 2900 2 Compound (101): 30.6g, Compound (102): 38.1g, Compound (111): 6.4g 2300 3 Compound (101): 30.6g, Compound (102): 38.1g, Compound (112): 7.0g 2900 4 Compound (101): 30.6g, Compound (102): 38.1g, Compound (113): 6.8g 2300 5 Compound (101): 30.6g, Compound (102): 38.1g, Compound (114): 7.1g 2500 6 Compound (101): 30.6g, Compound (102): 38.1g, Compound (115): 8.9g 2600 7 Compound (101): 30.6g, Compound (102): 38.1g, Compound (116): 8.0g 2300 8 Compound (100): 5.0 g, Compound (101): 30.6 g, Compound (102): 38.1 g 2500

[0243] The following describes the compounds used in the synthetic examples.

[0244] PhSi(OCH3)3··· compound (100)

[0245] CH3Si(OCH3)3··· compound (101)

[0246] Si(OCH3)4··· compound (102)

[0247] [Chemistry 11]

[0248]

[0249] [Synthesis Example 9]

[0250] A homogeneous solution was prepared by adding 1400 g of ethanol, 700 g of ultrapure water, and 50 g of 25% tetramethylammonium hydroxide under nitrogen atmosphere at 40 °C. A mixture of 138.6 g of 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane and 37.2 g of phenyltrimethoxysilane was slowly added dropwise to this homogeneous solution, and the reaction was carried out at 40 °C for 2 hours. After the reaction was completed, 35 g of acetic acid was added to the solution to stop the reaction, and the ethanol was removed by distillation under reduced pressure. 2000 ml of ethyl acetate was added to the distilled solution, and the aqueous layer was separated. The organic layer was washed twice with 400 ml of ultrapure water, and 1000 g of PGMEA (propylene glycol monomethyl ether acetate) was added. Water and low-boiling solvents were then distilled off, yielding 600 g of a PGMEA solution (20% compound concentration) of polysiloxane compound 9. The polystyrene-converted molecular weight of polysiloxane compound 9 was determined to be Mw = 2800.

[0251] [Preparation of Compositions for Forming Silicon-Containing Hard Mask Films]

[0252] The polysiloxane compounds 1 to 9 obtained in the above synthesis example, the crosslinking catalysts (XLC-1 to 3), the acid generators (AG1 to 4), the crosslinking agent (XL1), the organic solvent, and water were mixed in the proportions shown in Table 2. Each mixture was filtered through a 0.1 μm fluororesin filter to prepare a composition solution for forming a silicon-containing lower layer film, which were respectively designated as UDL-1 to 18.

[0253] [Table 2]

[0254]

[0255] The crosslinking catalyst used is as described below.

[0256] XLC-1…Triphenylsilane nitrate

[0257] XLC-2…maleic acid mono(triphenylsulfonium)

[0258] XLC-3…Triethylphenylammonium Iodide

[0259] The organic solvents used are as described below.

[0260] PGEE…Propylene Glycol Ethyl Ether

[0261] PGMEA…Propylene Glycol Methyl Ether Acetate

[0262] The acid-generating agents used are as described in Table 3 below.

[0263] [Table 3]

[0264]

[0265] The crosslinking agent (XL1) used is as follows.

[0266] [Chemistry 12]

[0267]

[0268] [Solvent Resistance Evaluation]

[0269] On a substrate, a 4nm Si film and a 3nm Mo film were formed as 1 pair to create 40 pairs, and then a 3nm Si film was formed on the surface to form a multilayer reflective film. A 2.5nm Ru protective layer and a 70nm TaN absorber layer were sequentially formed on this multilayer reflective film. Any of the aforementioned silicon-containing hard mask forming compositions (UDL-1 to 18) was coated onto the absorber layer, and the resulting coating was calcined under the baking conditions described in Table 4 to obtain a silicon-containing hard mask. Thus, the composites of Examples 1-1 to 1-20 were obtained.

[0270] The film thickness of the composites obtained in Examples 1-1 to 1-20 was measured from the center of the substrate to the outer edge, and the average film thickness (a [nm]) was calculated. Then, PGMEA solvent was dispensed onto it, left to stand for 30 seconds and rotated to dry, and baked at 110°C for 600 seconds to evaporate the PGMEA. The film thickness (b [nm]) was then measured.

[0271] Table 4 below shows the film thicknesses a and b, and the value of (b / a)×100 as an indicator of solvent resistance.

[0272] [Table 4]

[0273]

[0274]

[0275] As shown in Table 4, the residual film rate ((b / a)×100) after PGMEA rinsing treatment in Examples 1-1 to 1-20 was over 98%, indicating that crosslinking reaction still occurred on the photomask substrate, demonstrating sufficient solvent resistance. In particular, Examples UDL-10 to 17, which contain a crosslinking catalyst, exhibited excellent curing properties and could be processed at lower calcination temperatures. Furthermore, it was confirmed that higher baking temperatures or longer baking times in Examples 1-18 to 1-20 further improved solvent resistance.

[0276] Furthermore, it was confirmed that all the silicon-containing hard mask film forming compositions (UDL-1 to 18) prepared above were hardened at a temperature of 50°C to 180°C, and more specifically at a temperature of 120°C to 150°C.

[0277] [Reflectivity]

[0278] (The reference substrate with an attached multilayer reflective film)

[0279] On a substrate, 40 pairs of Si 4nm and Mo 3nm are formed as 1 pair, and then Si 3nm is formed on the surface to form a multilayer reflective film. A Ru 2.5nm layer is then formed on this multilayer reflective film as a protective film. Thus, a standard substrate with an attached multilayer reflective film is obtained.

[0280] When the peak reflectance of EUV light (wavelength 13.5 nm, hereinafter the same) on the main surface of the substrate with the attached multilayer reflective film of the reference was measured at an incident angle of 6°, it was 65%.

[0281] (Example 2-1)

[0282] Then, on the main surface of the aforementioned photomask substrate, a multilayer reflective film and a protective film were formed under the same conditions as those used in the fabrication of the reference substrate with the attached multilayer reflective film, thus fabricating the substrate with the attached multilayer reflective film of Example 2-1. This substrate with the attached multilayer reflective film was baked at 120°C for 600 seconds under conditions where the solvent resistance of the silicon-containing hard mask film in the above examples was 98% or higher. Thus, the evaluation substrate of Example 2-1 was obtained. The peak reflectance of EUV light (wavelength 13.5 nm, hereinafter the same) on the main surface of this evaluation substrate at an incident angle of 6° was measured and found to be 65%.

[0283] (Example 2-2)

[0284] The baking conditions on the substrate with the attached multilayer reflective film layer in Example 2-1 were changed to 150°C for 600 seconds. Otherwise, the evaluation substrate of Example 2-2 was fabricated under the same conditions as in Example 2-1. The peak reflectance of EUV light (wavelength 13.5 nm, hereinafter the same) on the main surface of the evaluation substrate at an incident angle of 6° was measured and found to be 65%.

[0285] (Examples 2-3)

[0286] The baking conditions on the substrate with the attached multilayer reflective film layer in Example 2-1 were changed to 180°C for 600 seconds. Otherwise, the evaluation substrate of Example 2-3 was fabricated under the same conditions as in Example 2-1. The peak reflectance of EUV light (wavelength 13.5 nm, hereinafter the same) on the main surface of the evaluation substrate at an incident angle of 6° was measured and found to be 64%.

[0287] (Comparative Example 2-1)

[0288] The baking conditions on the substrate with the multilayer reflective film were changed to 200°C for 600 seconds. Otherwise, the substrate for the photomask substrate was fabricated under the same conditions as in Example 2-1. The peak reflectance of EUV light (wavelength 13.5 nm, hereinafter the same) on the main surface of the substrate with the multilayer reflective film at an incident angle of 6° was measured and found to be 62%. Furthermore, when the cross-section of the obtained multilayer reflective film was observed by transmission electron microscopy (TEM), an interdiffusion layer of Si and Mo was observed.

[0289] Based on the above results, it can be seen that as long as the blank photomask of the present invention is used, because it contains a silicon-containing hard mask film containing a hardened composition of a silicon-containing hard mask forming material that is cured at a temperature of 50°C to 180°C, and the silicon-containing hard mask film does not need to be baked at a temperature exceeding 180°C during formation, the EUUV reflectivity of the multilayer reflective film layer will not be degraded at a temperature of 50°C to 180°C as demonstrated in Examples 2-1 to 2-3, and the film can be formed as a useful silicon-containing hard mask. On the other hand, it can be seen that in cases where the silicon-containing hard mask film is used in a silicon-containing hard mask forming material that requires a baking temperature exceeding 180°C, unlike the present invention, interlayer mixing of the multilayer reflective film layer occurs, and the EUUV reflectivity is degraded.

[0290] [Exposure and Evaluation]

[0291] (Examples 3-1 to 3-24)

[0292] On a substrate, a 4nm Si film and a 3nm Mo film are formed as 1 pair to create a 40-pair structure. Then, a 3nm Si film is formed on the surface to create a multilayer reflective film. On this multilayer reflective film, a 2.5nm Ru protective film and a 70nm TaN absorber layer are formed sequentially. A 6nm thick CrN film is formed on the absorber layer as the first layer of the hard mask.

[0293] Any of the above-prepared silicon-containing hard mask film forming components (UDL-1 to 18) are coated onto the above-mentioned CrN film by spin coating, and calcined under the baking conditions described in Table 5 to form a silicon-containing hard mask layer (silicon oxide material film) with a film thickness of 20 nm as the second layer of the hard mask.

[0294] Then, a spin coater was used on the substrate on which the silicon-containing hard mask layer was formed to form a 90 nm or 60 nm thick electron beam chemical amplification resist liquid SEBP-504G manufactured by Shin-Etsu Chemical Industry Co., Ltd. In this way, blank photomasks for each embodiment were fabricated.

[0295] Then, the photoresist film of each blank photomask was exposed using an electron beam lithography apparatus (NuFLARE EBM5000, accelerating voltage 50keV), and baked at 110°C for 10 minutes (PEB: post-exposure bake). Development was then performed using a 2.38% by mass aqueous solution of tetramethylammonium hydroxide, thereby obtaining a positive photoresist pattern containing a 100nm line pattern. Furthermore, the optimal exposure (sensitivity: Eop) was determined by resolving the top and bottom of the obtained 100nm lines and spacing at a 1:1 ratio.

[0296] The line edge roughness of the above resist pattern was measured. The line edge roughness was measured at 80 points using a SEM (ADVANTEST CORPORATION E3640) for the edges of 32 lines of each 100nm LS pattern. The deviation (standard deviation, σ) was calculated as 3 times the value (3σ) and taken as LER (nm).

[0297] Then, using the above photoresist pattern as an etching mask, the photomask substrate is processed in the following order.

[0298] First, using the above-mentioned photoresist pattern as a mask, the silicon-containing hard mask film exposed from the photoresist pattern is patterned by dry etching under the following fluorine-based dry etching conditions using a dry etching apparatus.

[0299] [Etching conditions for silicon-containing films]

[0300] RF1(RIE): CW 54V

[0301] RF2(ICP): CW 325W

[0302] Pressure: 5mTorr

[0303] SF6: 18sccm

[0304] O2: 45sccm

[0305] Etching time: 1 min

[0306] Then, after the photoresist pattern is stripped by oxygen plasma, the exposed Cr hard mask film is patterned by dry etching under the following oxygen-containing chlorine dry etching conditions, using the patterned silicon hard mask film (silicon film pattern) as a mask.

[0307] Etching conditions for Cr hard mask film

[0308] RF1(RIE): CW 10W

[0309] RF2(ICP): CW 300W

[0310] Pressure: 5mTorr

[0311] Cl2: 150 sccm

[0312] O2: 50 sccm

[0313] He: 10sccm

[0314] Etching time: 1 min

[0315] Then, the exposed absorber layer TaN film is patterned by dry etching under etching condition-1 and continuous etching condition-2, using the patterned Cr hard mask film as a mask.

[0316] [Etching conditions for TaN films - 1]

[0317] RF1(RIE): CW 54W

[0318] RF2(ICP): CW 325W

[0319] Pressure: 5mTorr

[0320] SF6: 18sccm

[0321] He: 130sccm

[0322] Etching time: 10 seconds

[0323] [Etching Conditions for TaN Films - 2]

[0324] RF1(RIE): CW 7.6W

[0325] RF2(ICP): CW 300W

[0326] Pressure: 5mTorr

[0327] Cl2: 150 sccm

[0328] He: 10sccm

[0329] Etching time: 5 min

[0330] (Compare Examples 3-1 and 3-2)

[0331] No silicon-containing hard mask layer is formed on the CrN film described above. The photoresist film is formed directly with the film thickness shown in Table 5. Otherwise, blank photomasks are made in the same manner as in Examples 3-1 or 3-14. These blank photomasks are processed in the same manner as in Examples 3-1 or 3-14.

[0332] The edge roughness of the patterned lines etched as described above in Examples 3-1 to 3-24 and Comparative Examples 3-1 and 3-2 was measured. The edge roughness was measured using a SEM (ADVANTEST CORPORATION E3640), with 80 edge detections performed on the edges of 32 lines in each 100nm LS pattern. Three times the deviation (standard deviation, σ) (3σ) was calculated as the LER (nm). A smaller value indicates better performance. Furthermore, the cross-sectional shape (pattern shape) was observed using an electron microscope (S-4800) manufactured by Hitachi High-Tech Corporation. No tailing or undercut shape was observed, which was rated as good; obvious tailing or undercut shape was observed, which was rated as poor. The results are shown in Table 5.

[0333] [Table 5]

[0334]

[0335]

[0336] As shown in Table 5, the blank photomasks of Examples 3-1 to 3-24 containing the silicon-containing hard mask film of the present invention showed good edge roughness of the resist pattern compared to Comparative Examples 3-1 and 3-2 which did not contain the silicon-containing hard mask film, and the etched pattern shape was also excellent. Examples 3-1 to 3-8, which used polysiloxanes (compounds 1 to 7) containing organic groups having one or more carbon-oxygen single or double bonds, showed good edge roughness of the resist pattern. This is presumably due to good adhesion to the resist pattern. Furthermore, Examples 3-11 to 3-23, which used compositions for forming silicon-containing hard mask films containing crosslinking catalysts (UDL-10 to 17), showed even better edge roughness of the resist pattern compared to compositions without crosslinking catalysts, and the etched edge roughness was also good. This is presumably because the addition of the crosslinking catalyst improved the density of the silicon-containing hard mask film.

[0337] As shown in Comparative Example 3-2, when the resist film thickness was 60 nm, LER degradation was observed due to the deterioration of the cross-sectional shape. However, in Examples 3-14 and 3-19, which contained silicon-containing hard mask films, no deterioration of the cross-sectional shape was observed, and good LER was obtained. It is speculated that this is because of the good adhesion between the silicon-containing hard mask film and the resist film.

[0338] Based on the above, the blank photomask of the present invention, because it contains a silicon-containing hard mask film which is useful as a hard mask film, can transfer fine resist patterns to the absorber layer with high precision. Furthermore, the silicon-containing hard mask film forming composition used in the present invention can be cured in a temperature range of 50°C to 180°C, thus preventing interlayer mixing of the multilayer reflective films and improving the transfer accuracy of the resist pattern. In other words, the present invention provides a blank photomask that does not degrade the reflectivity of EUV light and provides a photomask with fine patterns formed with high precision.

[0339] This specification contains the following specifications.

[0340] [1] A blank photomask, characterized in that it comprises:

[0341] substrate,

[0342] Multilayer reflective film for reflecting EUV light formed on the substrate

[0343] An absorber layer that absorbs EUV light is formed on the multilayer reflective film.

[0344] Silicon-containing hard mask film formed directly or indirectly on the absorber layer, and

[0345] A photoresist film is formed on the silicon-containing hard mask film;

[0346] The hardened form of the silicon-containing hard mask is a component for forming a silicon-containing hard mask that is cured at a temperature between 50°C and 180°C.

[0347] [2] The blank photomask as in [1], wherein the composition for forming the silicon-containing hard mask film contains: a silicon-containing compound having any one or more of the following general formula (Sx-1), the following general formula (Sx-2), and the following general formula (Sx-3).

[0348] [Chemistry 13]

[0349]

[0350] (where R is in the formula) a R b and R c Each can be a monovalent organic group with 1 to 30 carbon atoms, which may be the same or different.

[0351] [3] As in [2], the blank light mask, where R in the above formulas (Sx-1)~(Sx-3) a ~R c At least one of them is an organic group having one or more carbon-oxygen single bonds or carbon-oxygen double bonds.

[0352] [4] A blank photomask as described in any of [1] to [3], wherein the composition for forming the silicon-containing hard mask film further contains a crosslinking catalyst.

[0353] [5] A blank photomask as in [4], wherein the crosslinking catalyst is a sulfonium salt, monazine salt, phosphonium salt, ammonium salt, alkali metal salt, or a polysiloxane having any one of sulfonium salt, monazine salt, phosphonium salt, and ammonium salt as part of its structure.

[0354] [6] A method for processing a blank photomask, comprising the following steps:

[0355] (i-1) An electron beam is irradiated onto a blank photomask as described in any of [1] to [5], and then developed using a developer to form a photoresist pattern on the photoresist film.

[0356] (i-2) By etching the photoresist pattern as a mask, the silicon-containing film pattern is formed on the silicon-containing hard mask film, and

[0357] (i-3) The absorber layer is processed directly or indirectly by etching the silicon-containing film pattern as a mask.

[0358] [7] A method for manufacturing a blank photomask, comprising the following steps:

[0359] Prepare substrate,

[0360] A multilayer reflective film layer for reflecting EUV light is formed on the substrate.

[0361] An absorber layer that absorbs EUV light is formed on the multilayer reflective film.

[0362] A coating is obtained by directly or indirectly coating a silicon-containing hard mask film forming composition that is cured at a temperature of 50°C to 180°C onto the absorber layer, and then curing the coating at a temperature of 50°C to 180°C to form a silicon-containing hard mask film.

[0363] A photoresist film is formed on the silicon-containing hard mask film.

[0364] Furthermore, this invention is not limited to the embodiments described above. The embodiments described above are examples; any invention having a substantially identical structure and function to the technical concept described in the claims of this invention is included within the scope of this invention.

[0365] Explanation of reference numerals in the attached figures

[0366] 1:Substrate

[0367] 2: Multilayer reflective film

[0368] 3: Protective film

[0369] 4: Absorber layer

[0370] 5: The first layer of the hard mask film

[0371] 6: Silicon-containing hard mask film (the second layer of the hard mask)

[0372] 7: Photoresist film

[0373] 101: Blank photomask

Claims

1. A blank photomask, characterized in that, have: substrate, Multilayer reflective film for reflecting EUV light formed on the substrate An absorber layer that absorbs EUV light is formed on the multilayer reflective film. Silicon-containing hard mask film formed directly or indirectly on the absorber layer, and A photoresist film is formed on the silicon-containing hard mask film; The hardened form of the silicon-containing hard mask is a component for forming a silicon-containing hard mask that is cured at a temperature between 50°C and 180°C.

2. The blank photomask according to claim 1, wherein, The composition for forming a silicon-containing hard mask film contains: a silicon-containing compound having any one or more of the following general formula (Sx-1), the following general formula (Sx-2), and the following general formula (Sx-3). In the formula, R a R b and R c Each of them consists of a monovalent organic group having 1 to 30 carbon atoms, which may be the same or different.

3. The blank photomask according to claim 2, wherein, In the above equations (Sx-1) to (Sx-3), R a ~R c At least one of them is an organic group having one or more carbon-oxygen single bonds or carbon-oxygen double bonds.

4. The blank photomask according to claim 1, wherein, The composition for forming silicon-containing hard mask films also contains a crosslinking catalyst.

5. The blank photomask according to claim 4, wherein, The crosslinking catalyst is a sulfonium salt, monazine salt, phosphonium salt, ammonium salt, alkali metal salt, or a polysiloxane having any one of sulfonium salt, monazine salt, phosphonium salt, and ammonium salt as part of its structure.

6. A method for processing a blank photomask, characterized in that, Includes the following steps: (i-1) An electron beam is irradiated onto a blank photomask according to any one of claims 1 to 5, and then developed using a developer to form a photoresist pattern on the photoresist film. (i-2) By etching the photoresist pattern as a mask, the silicon-containing film pattern is formed on the silicon-containing hard mask film, and (i-3) The absorber layer is processed directly or indirectly by etching the silicon-containing film pattern as a mask.

7. A method for manufacturing a blank photomask, characterized in that, Includes the following steps: Prepare substrate, A multilayer reflective film layer for reflecting EUV light is formed on the substrate. An absorber layer that absorbs EUV light is formed on the multilayer reflective film. A coating is obtained by directly or indirectly coating a silicon-containing hard mask film forming composition that is cured at a temperature of 50°C to 180°C onto the absorber layer, and then curing the coating at a temperature of 50°C to 180°C to form a silicon-containing hard mask film. A photoresist film is formed on the silicon-containing hard mask film.

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