JP2012068314A - Photomask blank and processing method for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable, in patterning that employs a resist film for regular use, processing to be done at a more advantageous etching selection ratio than with a film of chromic material and, in transferring this hard mask film pattern on this silicon oxide-based material to a film containing transition metal, such as molybdenum, and silicon, on a transparent substrate, an effective selection ratio to be obtained by dry etching that uses chlorine gas whose oxygen content ratio is controlled, resulting in achievement of highly accurate transfer of a resist pattern to an optical film, such as a light shielding film formed on a transparent substrate.SOLUTION: There is provided a photomask blank in which a film of a material containing transition metal and silicon via or not via another film is formed over a transparent substrate, and a hard mask film for use in dry etching is disposed over the film. The hard mask film is a film of silicon oxide-based material formed using a composition for forming a silicon oxide material film which contains organic solvent and a hydrolyzed and condensed product of a hydrolytic silane compound.

Description

  The present invention relates to a photomask blank which is a material for producing a photomask and has a hard mask film when etching a thin film formed on a substrate, and a photomask blank processing method using the photomask blank. .

  In recent years, in semiconductor processing, circuit pattern miniaturization has become more and more necessary, especially due to high integration of large-scale integrated circuits. There is an increasing demand for miniaturization technology of contact hole patterns for wiring. For this reason, even in the manufacture of photomasks with circuit patterns written thereon, which are used in photolithography to form these wiring patterns and contact hole patterns, a technique capable of writing circuit patterns more finely and accurately along with the above-mentioned miniaturization. Is required.

  In order to form a photomask pattern with higher accuracy on the photomask substrate, it is first necessary to form a high-precision resist pattern on the photomask blank. Since optical lithography when processing an actual semiconductor substrate performs reduction projection, the photomask pattern is about four times as large as the actually required pattern size. The photomask that is the original plate is required to have higher accuracy than that required for pattern accuracy after exposure.

  Furthermore, in the lithography that is currently being performed, the circuit pattern to be drawn is a size that is considerably smaller than the wavelength of the light to be used, and if a photomask pattern in which the shape of the circuit is four times as it is is used, Due to the influence of light interference or the like generated during the photolithography, the shape according to the photomask pattern is not transferred to the resist film. Therefore, in order to reduce these effects, the photomask pattern may need to be processed into a more complicated shape than an actual circuit pattern (a shape to which so-called OPC: Optical Proximity Effect Correction (optical proximity effect correction) or the like is applied). . Therefore, even in lithography technology for obtaining a photomask pattern, a highly accurate processing method is currently required. Lithographic performance may be expressed with a limit resolution, but this resolution limit is equivalent to or higher than the resolution limit required for optical lithography used in semiconductor processing processes using photomasks. Limiting resolution accuracy is required for the lithography technique in the photomask processing process.

  In the formation of a photomask pattern, a photoresist film is usually formed on a photomask blank having a light shielding film on a transparent substrate, a pattern is drawn with an electron beam, a resist pattern is obtained through development, and Using the resist pattern as a mask, the light-shielding film is etched into a light-shielding pattern, but when the light-shielding pattern is miniaturized, an attempt is made to keep the resist film thickness as it was before miniaturization. As a result, the ratio of the film thickness to the pattern, the so-called aspect ratio, increases, the pattern shape of the resist deteriorates and pattern transfer cannot be performed properly, or the resist pattern collapses or peels off in some cases. Therefore, it is necessary to reduce the resist film thickness with miniaturization.

  On the other hand, many light-shielding film materials that have been etched using a resist as a mask have been proposed so far. However, since there is much knowledge about etching and it has been established as a standard processing step, it is always practically a chromium compound. Membranes have been used. However, in order to manufacture a mask for use in exposure such that the minimum line width of a target pattern is 45 nm, a light-shielding film made of a chromium-based material is directly formed with a resist thinned for the above-described reason. The etching method cannot secure sufficient processing accuracy.

  As a method of dry-etching a metal-based material film with a thinned resist, a film that is resistant to the dry-etching conditions of the metal-based material film and that can be dry-etched under conditions that do not relatively damage the resist film is used. A method for use as a mask film is known. For example, a mask obtained by using a thin chromium-based material film as a hard mask as a hard mask film, for example, in order to dry-etch a light-shielding film made of a silicon-based material with a thin resist. JP 2007-214060 A (Patent Document 1) discloses that the pattern can be highly accurate. Similarly, it is disclosed in Japanese Patent Laid-Open No. 2006-146152 (Patent Document 2) that a silicon-based material film can be used as a hard mask for the chromium light-shielding film.

  On the other hand, when a silicon-based material film is used as a hard mask film for a chromium-based material film, not only a film formed by sputtering as described above but also a method using a coating-type silicon oxide-based film, so-called SOG film. (Patent Document 3: JP 2008-26500 A).

JP 2007-2441060 A JP 2006-146152 A JP 2008-26500 A JP-A 63-85553 JP 2007-302873 A JP 2008-19423 A Japanese Patent Laid-Open No. 2001-27799

  In the transfer of a resist pattern to a molybdenum silicide material film or a chromium material film formed by sputtering in the processing of a photomask blank, the etching selectivity between the resist film and the film to be processed is not sufficiently high. Furthermore, how to ensure the processing accuracy by thinning the resist film due to the progress of miniaturization has become an important proposition.

  As a method for forming a highly accurate pattern, a method of using a hard mask technique has been adopted for a long time when manufacturing a photomask. For example, when processing a halftone phase shift film with a molybdenum silicide compound, the resist pattern is temporarily transferred to a light shielding film made of a chromium material formed on the halftone phase shift film and then transferred to the halftone phase shift film. The way to be done.

  Further, in order to cope with the recent miniaturization, a method using a hard mask has been proposed even when the light shielding film itself is processed. For example, in Japanese Patent Application Laid-Open No. 2007-241060 (Patent Document 1), molybdenum is proposed. The light-shielding film made of a material containing silicon and silicon is processed using a hard mask film made of a chromium-based material, and the film made of a material containing molybdenum and silicon can be processed with high accuracy. In this method, when attention is paid to the chromium-based material, the processing accuracy is improved by using the chromium-based material that imposes a burden on the resist as a thin film as much as possible.

  In addition, a chromium-based material generally processed under chlorine-based dry etching conditions as described above, and a transition metal and silicon-containing material generally processed under fluorine-based dry etching conditions are used as a hard mask. As a method for this, it has been proposed to use an SOG film as a hard mask film when processing a chromium-based material film (Patent Document 3: Japanese Patent Application Laid-Open No. 2008-26500).

On the other hand, the method of the hard mask using an etching selectivity between the silicon base material, but less example, been proposed a method using a SiO ₂ film formed by sputtering MoSi ₂ film to the hard mask layer (Patent Document 4: Japanese Patent Laid-Open No. 63-85553). Here, the resist pattern is transferred to the SiO ₂ film by fluorine-based dry etching, and the transferred SiO ₂ film pattern is transferred to the MoSi ₂ film by chlorine-based dry etching containing oxygen.

Furthermore, the method proposed in Japanese Patent Application Laid-Open No. 63-85553 (Patent Document 4) is a fluorine-based dry process in which transfer of a resist pattern to a hard mask film provides an advantageous etching selectivity with respect to the resist film. can be processed by etching, furthermore, although an ArF excimer laser beam (wavelength 193 nm) interesting in that it is high absorption coefficient of silicon-based material to, if an attempt is made to realistic commercialized by sputtering SiO ₂ film formed When the film is formed, a great number of defects are often generated, and it is extremely difficult to put it to practical use.

  As a hard mask film used when dry-etching a silicon-based material, a resist pattern can be transferred with high accuracy by using a material with better workability, and further improvement in accuracy of photomask technology is required.

  The present invention has been made in view of the above circumstances, and when a transition metal silicon material film such as a MoSi system is processed by dry etching, a pattern by dry etching that uses a commonly used photoresist that functions as a hard mask. An object of the present invention is to provide a photomask blank having a hard mask film that gives etching selectivity more advantageous than a chromium-based material, and a photomask blank processing method using the photomask blank.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have been able to process MoSi-based transition metal silicon materials by chlorine-based dry etching using the SOG film as a hard mask, and further, Si— in the SOG film. The present inventors have found that an SOG film obtained using a composition for forming an SOG film containing a crosslinking formation accelerator that promotes O—Si crosslinking can function sufficiently as a hard mask even with a thinner film.

Accordingly, the present invention provides the following photomask blank and processing method thereof.
Claim 1:
A photomask blank in which a film made of a material containing a transition metal and silicon is formed on a transparent substrate with or without another film, and a hard mask film for dry etching is provided on the film. And
The hard mask film has the following general formula (1)
R _n SiX _4-n (1)
(In the formula, R is a hydrogen atom, a methyl group, an oxygen atom or an oxygen-containing functional group and an aliphatic hydrocarbon group or aromatic hydrocarbon group having 2 to 12 carbon atoms, and X is the number of carbon atoms. An alkoxy group having 1 to 4 carbon atoms, a halogen atom, or an alkylcarbonyloxy group having 2 to 5 carbon atoms, and n is 0 or 1.)
A film is formed using a composition for forming a silicon oxide-based material film containing a hydrolyzable silane compound hydrolyzate / condensate obtained using a raw material containing at least one silane compound represented by formula (II) and an organic solvent. A photomask blank, which is a silicon oxide material film.
Claim 2:
The composition for forming a silicon oxide-based material film further comprises the following general formula (2) or (3):
L _a H _b X (2)
(Wherein L is lithium, sodium, potassium, rubidium or cesium, X is a hydroxyl group, or a monovalent or divalent or higher organic acid group having 1 to 30 carbon atoms, a is an integer of 1 or more, and b is 0. Or an integer of 1 or more, and a + b is a valence of a hydroxyl group or an organic acid group.)
MA (3)
(Wherein M is tertiary sulfonium, secondary iodonium or quaternary ammonium, and A is a non-nucleophilic counter ion.)
The photomask blank according to claim 1, comprising a crosslinking formation accelerator represented by the formula:
Claim 3:
The hydrolyzable silane compound is a simple substance or a mixture of two or more hydrolyzable silane compounds containing 70% or more of the compound represented by the general formula (1) based on silicon. Or the photomask blank of 2.
Claim 4:
4. The photomask blank according to claim 1, wherein the transition metal is molybdenum.
Claim 5:
Forming a resist pattern on the photomask blank according to any one of claims 1 to 4,
Using a step of transferring the resist pattern to the hard mask film by fluorine-based dry etching and the hard mask film pattern formed by the pattern transfer, a gas having an oxygen / chlorine concentration of 0.001 to 0.25 (molar ratio) A method for processing a photomask blank, comprising a step of transferring a pattern to a film made of a material containing the transition metal and silicon by chlorine dry etching.

  The hard mask film in the photomask blank of the present invention is a hard mask film made of a silicon oxide-based material, and can be processed with an etching selectivity that is more advantageous than a chromium-based material film in patterning using a normal resist film. In addition, when transferring the hard mask film pattern of this silicon oxide-based material to a film containing transition metal such as molybdenum and silicon on a transparent substrate, dry etching is performed using chlorine gas with a controlled oxygen content ratio. An effective selection ratio can be obtained, and a resist pattern can be transferred with high accuracy to an optical film such as a light-shielding film formed on a transparent substrate.

Hereinafter, the present invention will be described in more detail.
In the photomask blank of the present invention, a film made of a material containing a transition metal and silicon is formed on a transparent substrate with or without another film, and the film made of a material containing the transition metal and silicon. A hard mask film for dry etching is provided thereon.

This hard mask film has the following general formula (1)
R _n SiX _4-n (1)
(In the formula, R is a hydrogen atom, a methyl group, an oxygen atom or an oxygen-containing functional group and an aliphatic hydrocarbon group or aromatic hydrocarbon group having 2 to 12 carbon atoms, and X is the number of carbon atoms. An alkoxy group having 1 to 4 carbon atoms, a halogen atom, or an alkylcarbonyloxy group having 2 to 5 carbon atoms, and n is 0 or 1.)
A film is formed using a composition for forming a silicon oxide-based material film containing a hydrolyzable silane compound hydrolyzate / condensate obtained using a raw material containing at least one silane compound represented by formula (II) and an organic solvent. It is a silicon oxide-based material film.

  In the general formula (1), X is a hydrolyzable group, which becomes a silanol group by the hydrolysis reaction, and further causes a condensation reaction. X is selected from an alkoxy group having 1 to 4 carbon atoms, a halogen atom such as a chlorine atom, or an alkylcarbonyloxy group having 2 to 5 carbon atoms. In particular, those having an alkoxy group having 1 to 4 carbon atoms are readily available, and are preferably used because a cleaner product is obtained compared to halogen. Specific examples of the alkoxy group include a methoxy group, an ethoxy group, a propoxy group including a structural isomer, and a butoxy group. Examples of the alkylcarbonyloxy group having 2 to 5 carbon atoms include an acetoxy group and a propionyloxy group including a structural isomer of an alkyl part, a butyryloxy group, and a pentyloxy group.

  In the general formula (1), R represents a hydrogen atom, a methyl group, an oxygen atom or an oxygen-containing functional group, an aliphatic hydrocarbon group having 2 to 12 carbon atoms or an aromatic hydrocarbon group. The aliphatic hydrocarbon group has 2 to 12 carbon atoms, and may include an alkyl group, an alkenyl group, an alkynyl group, etc., and may be any of linear, branched, and cyclic. It may be an aralkyl group substituted with an aromatic group. In the case of an aromatic hydrocarbon group, the carbon number is 6-12. Further, the aliphatic hydrocarbon group and the aromatic hydrocarbon group may have an oxygen atom or an oxygen-containing functional group, and the oxygen atom and the oxygen-containing functional group are an aliphatic hydrocarbon group and an aromatic hydrocarbon group. The carbon chain may be bonded to either the terminal of the carbon chain or between the carbon atoms. Examples of the oxygen atom and the oxygen-containing functional group include —O—, —CO—, —OCO—, —COO—, —OCOO—, and the like. Furthermore, one or more of the hydrogen atoms of the aliphatic hydrocarbon group and aromatic hydrocarbon group may have a halogen atom, an ether bond or a halogen substituent, an aliphatic group such as an alkyl group, or a cycloalkyl group. A group substituted with an alicyclic group or the like may be used.

  Specific examples of R include many examples in JP-A-2007-302873 (Patent Document 5) and JP-A-2008-19423 (Patent Document 6), and any of them can be used. Among them, as a hydrogen atom and an aliphatic hydrocarbon group, a methyl group, an ethyl group, an n-propyl group including a structural isomer, an alkyl group such as a butyl group, a pentyl group, and a hexyl group, a cycloalkyl group such as a cyclohexyl group, Preferable examples of the alkenyl group such as vinyl group and allyl group and the aromatic hydrocarbon group include a phenyl group. Examples of the substituent for the hydrogen atom include halogen atoms such as fluorine atom, chlorine atom, bromine atom and iodine atom, alkoxy groups such as methoxy group and ethoxy group, acyl group, acyloxy group, epoxy group, ester group, acetal group, Preferred examples include a substituent containing a hydroxy group or a lactone ring.

  The hydrolyzable silane compound represented by the general formula (1) may be used alone or as a mixture of two or more kinds. In particular, the content of the hydrolyzable silane compound represented by the general formula (1) is silicon from the viewpoint of improving the etching resistance of the obtained SOG film and obtaining a low-cost, high-performance and stable quality product. It is preferable to set it as 70 mol% or more on the basis.

  In addition to the hydrolyzable silane compound represented by the general formula (1), a divalent hydrolyzable silane compound in which n is 2 in the general formula (1), or a monovalent hydrolyzate if the amount is small. Although a functional silane compound can also be used, these have a tendency to reduce the etching resistance of the resulting silicon oxide-based material film, and is preferably 30 mol% or less based on silicon. Also, hydrolyzable silanes containing a plurality of silicon atoms as described in JP-A-2007-302873 (Patent Document 5) and JP-A-2008-19423 (Patent Document 6) may be used. it can.

  The above-mentioned hydrolyzable silane compound is prepared using an acid or alkali as a catalyst in accordance with known methods described in JP2007-302873 (Patent Document 5), JP2008-19423 (Patent Document 6) and the like. A condensate is obtained by hydrolysis and condensation. In order to obtain higher etching resistance, when using an acid as a main component, that is, using only an acid condensed catalyst or an alkali condensed catalyst In addition, it is preferable to use a mixture such that the product condensed with an acid is contained at a higher mass ratio than the product condensed with an alkali as a catalyst.

Examples of the acid catalyst preferably used for the hydrolysis and condensation by the acid catalyst include hydrofluoric acid, hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid, perchloric acid, phosphoric acid, methanesulfonic acid, benzenesulfonic acid, and toluenesulfonic acid. Can be mentioned. The amount of the catalyst used is 10 ⁻⁶ mol to 10 mol, preferably 10 ⁻⁵ mol to 5 mol, more preferably 10 ⁻⁴ mol to 1 mol, relative to 1 mol of silicon monomer.

  The amount of water used to obtain a condensate by hydrolysis condensation from the hydrolyzable silane compound is 0.01 to 100 mol per mol of hydrolyzable substituent bonded to the hydrolyzable silane compound. More preferably, 0.05 to 50 mol, and still more preferably 0.1 to 30 mol are added. Addition in excess of 100 moles is uneconomical because only the apparatus used for the reaction becomes excessive.

  Specifically, as an operation method of the hydrolysis, first, a monomer is added to the aqueous catalyst solution to start the hydrolysis condensation reaction. At this time, an organic solvent may be added to the catalyst aqueous solution, the monomer may be diluted with the organic solvent, or both may be performed. The reaction temperature is 0 to 100 ° C, preferably 5 to 80 ° C. A method in which the temperature is maintained at 5 to 80 ° C. when the monomer is dropped and then ripened at 20 to 80 ° C. is preferable.

  As the organic solvent that can be added to the catalyst aqueous solution or that can dilute the hydrolyzable silane compound, various known solvents can be used, and among them, a water-soluble one is preferable. For example, alcohols such as methanol, ethanol, 1-propanol and 2-propanol, polyhydric alcohols such as ethylene glycol and propylene glycol, propylene glycol monomethyl ether, ethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl ether And polyhydric alcohol condensate derivatives such as propylene glycol monopropyl ether and ethylene glycol monopropyl ether, acetone, acetonitrile, tetrahydrofuran and the like. Among these, those having a boiling point of 100 ° C. or less are particularly preferable. In addition, the usage-amount of an organic solvent is 0-1,000 ml with respect to 1 mol of monomers, Especially 0-500 ml is preferable. If the amount of organic solvent used is large, the reaction vessel becomes excessive and uneconomical.

  Thereafter, if necessary, a neutralization reaction of the catalyst is performed, and the alcohol generated by the hydrolysis condensation reaction is removed under reduced pressure to obtain an aqueous reaction mixture solution. At this time, the amount of the alkaline substance that can be used for neutralization is preferably 0.1 to 2 equivalents relative to the acid used in the catalyst. The alkaline substance may be any substance as long as it shows alkalinity in water.

  The obtained condensate is obtained by removing the catalyst by a known method (for example, a method by ion exchange described in JP-A-2007-302873 (Patent Document 5), a method using an epoxy compound, or JP-A-2008-19423. In general, the alcohol used in the reaction is removed under reduced pressure without removing the condensate as a single substance, and at the same time for application. By changing to a solvent, a coating composition is obtained.

  When performing the solvent exchange, the silicon-containing compound may become unstable, and a stabilizer may be added. As the stabilizer, a monovalent or divalent or higher organic acid having 1 to 30 carbon atoms can be preferably used. As a particularly preferred stabilizer, oxalic acid, maleic acid, formic acid, acetic acid, propionic acid, citric acid and the like are used. Can be mentioned. In order to maintain stability, two or more kinds of acids may be mixed and used. The addition amount is 0.001 to 25 parts by mass, preferably 0.01 to 15 parts by mass, and more preferably 0.1 to 5 parts by mass with respect to 100 parts by mass of the silicon-containing compound contained in the composition.

  By using a silicon oxide-based material film formed using such a composition for forming a silicon oxide-based material film as a hard mask film, a film containing a transition metal such as molybdenum and silicon can be further obtained. When nitrogen and / or oxygen is contained together with silicon and silicon, for example, even in the case of a film having an antireflection function, selective etching can be performed by applying chlorine-based dry etching conditions.

  When the silicon oxide-based material film is used as a hard mask film, if the density of Si—O—Si crosslinks is low, there is a risk that sufficient etching resistance cannot be obtained, and LER (line edge roughness) of the transfer pattern May become large. This problem of etching resistance can be basically solved by increasing the thickness of the hard mask film, but if the film thickness is sufficiently increased, there is a high risk of generating a residue when removing the unused portion film. There is a risk that defects, that is, black defects, remain in the film material that must be removed after pattern transfer. Therefore, it is preferable that the silicon oxide-based material film has a high Si—O—Si cross-linking density. This can be achieved by further adding a cross-linking accelerator to the silicon oxide-based material film forming composition. it can.

As a preferable material of the crosslinking accelerator, the following general formula (2)
L _a H _b X (2)
(Wherein L is lithium, sodium, potassium, rubidium or cesium, X is a hydroxyl group, or a monovalent or divalent or higher organic acid group having 1 to 30 carbon atoms, a is an integer of 1 or more, and b is 0. Or an integer of 1 or more, and a + b is a valence of a hydroxyl group or an organic acid group.)
Or the following general formula (3)
MA (3)
(Wherein M is tertiary sulfonium, secondary iodonium or quaternary ammonium, and A is a non-nucleophilic counter ion.)
Can be mentioned.

  Examples of the compound represented by the general formula (2) include alkali metal hydrates and alkali metal organic acid salts. For example, lithium, sodium, potassium, rubidium, cesium hydrochloride, formate, acetate, propionate, butanoate, pentanoate, hexanoate, heptanoate, octanoate, nonanoate, Decanoate, oleate, stearate, linoleate, linolenate, benzoate, phthalate, isophthalate, terephthalate, salicylate, trifluoroacetate, monochloroacetate, dichloroacetate Salt, monovalent salt such as trichloroacetate, monovalent or divalent oxalate, malonate, methylmalonate, ethylmalonate, propylmalonate, butylmalonate, dimethylmalonate , Diethyl malonate, succinate, methyl succinate, glutarate, adipate, itaconate, maleate, fumarate, citracone Salt, citric acid, and carbonic acid.

  Examples of the compound represented by the general formula (3) include a sulfonium compound, an iodonium compound, and an ammonium compound represented by the following formula (Q-1), (Q-2), or (Q-3).

（式中、Ｒ²⁰⁴、Ｒ²⁰⁵、Ｒ²⁰⁶はそれぞれ炭素数１〜１２の直鎖状、分岐状又は環状のアルキル基、アルケニル基、オキソアルキル基又はオキソアルケニル基、炭素数６〜２０の置換又は非置換のアリール基、又は炭素数７〜１２のアラルキル基又はアリールオキソアルキル基を示し、これらの基の水素原子の一部又は全部がアルコキシ基等によって置換されていてもよい。また、Ｒ²⁰⁵とＲ²⁰⁶とは環を形成してもよく、環を形成する場合には、Ｒ²⁰⁵、Ｒ²⁰⁶はそれぞれ炭素数１〜６のアルキレン基を示す。Ａ^-は非求核性対イオンを表す。Ｒ²⁰⁷、Ｒ²⁰⁸、Ｒ²⁰⁹、Ｒ²¹⁰は、Ｒ²⁰⁴、Ｒ²⁰⁵、Ｒ²⁰⁶と同様であるが、水素原子であってもよい。Ｒ²⁰⁷とＲ²⁰⁸、Ｒ²⁰⁷とＲ²⁰⁸とＲ²⁰⁹とは環を形成してもよく、環を形成する場合には、Ｒ²⁰⁷とＲ²⁰⁸及びＲ²⁰⁷とＲ²⁰⁸とＲ²⁰⁹は炭素数３〜１０のアルキレン基を示す。）

(Wherein R ²⁰⁴ , R ²⁰⁵ and R ²⁰⁶ are each a linear, branched or cyclic alkyl group, alkenyl group, oxoalkyl group or oxoalkenyl group having 1 to 12 carbon atoms, and substitution having 6 to 20 carbon atoms. Or an unsubstituted aryl group, an aralkyl group having 7 to 12 carbon atoms, or an aryloxoalkyl group, and a part or all of hydrogen atoms of these groups may be substituted with an alkoxy group or the like. ²⁰⁵ and R ²⁰⁶ may form a ring, and in the case of forming a ring, R ²⁰⁵ and R ²⁰⁶ each represent an alkylene group having 1 to 6 carbon atoms, A ⁻ represents a non-nucleophilic counter ion. R ²⁰⁷ , R ²⁰⁸ , R ²⁰⁹ , and R ²¹⁰ are the same as R ²⁰⁴ , R ²⁰⁵ , and R ²⁰⁶ , but may be a hydrogen atom, R ²⁰⁷ and R ²⁰⁸ , R ²⁰⁷ and R ^208, and R ²⁰⁹ and may form a ring, when they form a ring, R ²⁰⁷ and R ²⁰⁸及R ^207, R ²⁰⁸ and R ²⁰⁹ represents an alkylene group having 3 to 10 carbon atoms.)

R ²⁰⁴ , R ²⁰⁵ , R ²⁰⁶ , R ²⁰⁷ , R ²⁰⁸ , R ²⁰⁹ , and R ²¹⁰ may be the same as or different from each other. Specific examples of the alkyl group include a methyl group, an ethyl group, and a propyl group. , Isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group, heptyl group, octyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclopropylmethyl group, 4-methylcyclohexyl Group, cyclohexylmethyl group, norbornyl group, adamantyl group and the like. Examples of the alkenyl group include a vinyl group, an allyl group, a propenyl group, a butenyl group, a hexenyl group, and a cyclohexenyl group. Examples of the oxoalkyl group include 2-oxocyclopentyl group, 2-oxocyclohexyl group, and the like. 2-oxopropyl group, 2-cyclopentyl-2-oxoethyl group, 2-cyclohexyl-2-oxoethyl group, 2- (4 -Methylcyclohexyl) -2-oxoethyl group and the like can be mentioned. Examples of the aryl group include a phenyl group, a naphthyl group, a p-methoxyphenyl group, an m-methoxyphenyl group, an o-methoxyphenyl group, an ethoxyphenyl group, a p-tert-butoxyphenyl group, and an m-tert-butoxyphenyl group. Alkylphenyl groups such as alkoxyphenyl groups, 2-methylphenyl groups, 3-methylphenyl groups, 4-methylphenyl groups, ethylphenyl groups, 4-tert-butylphenyl groups, 4-butylphenyl groups, dimethylphenyl groups, etc. Alkyl naphthyl groups such as methyl naphthyl group and ethyl naphthyl group, alkoxy naphthyl groups such as methoxy naphthyl group and ethoxy naphthyl group, dialkyl naphthyl groups such as dimethyl naphthyl group and diethyl naphthyl group, dimethoxy naphthyl group and diethoxy naphthyl group Dialkoxynaphthyl group And the like. Examples of the aralkyl group include a benzyl group, a phenylethyl group, and a phenethyl group. As the aryloxoalkyl group, 2-aryl-2-oxoethyl group such as 2-phenyl-2-oxoethyl group, 2- (1-naphthyl) -2-oxoethyl group, 2- (2-naphthyl) -2-oxoethyl group and the like Groups and the like. Non-nucleophilic counter ions of A ⁻ include hydroxide ion, formate ion, acetate ion, nitrate ion, propionate ion, butanoic acid ion, pentanoic acid ion, hexanoic acid ion, heptanoic acid ion, octanoic acid ion, and nonanoic acid. Ion, decanoate ion, oleate ion, stearate ion, linoleate ion, linolenate ion, benzoate ion, phthalate ion, isophthalate ion, terephthalate ion, salicylate ion, trifluoroacetate ion, monochloroacetate ion, Monovalent ion such as dichloroacetate ion, trichloroacetate ion, fluoride ion, chloride ion, bromide ion, iodide ion, monovalent or divalent oxalate ion, malonate ion, methylmalonate ion, ethyl Malonate ion, propylmalonate ion, Lumalonate ion, dimethylmalonate ion, diethylmalonate ion, succinate ion, methylsuccinate ion, glutarate ion, adipate ion, itaconic acid ion, maleate ion, fumarate ion, citraconic acid ion, citrate ion, Examples include carbonate ions.

  In addition, the said crosslinking formation promoter can be used individually by 1 type or in combination of 2 or more types. The addition amount of the crosslinking formation accelerator in the composition for forming a silicon oxide-based material film is preferably 0.01 to 50 parts by mass with respect to 100 parts by mass of the hydrolyzable / condensate of the hydrolyzable silane compound. Preferably it is 0.1-40 mass parts.

  The organic solvent used as a coating solvent for the composition for forming a silicon oxide-based material film used in the present invention is preferably the organic solvent used in the production of the above-mentioned silicon-containing compound, particularly ethylene glycol, diethylene glycol, It is preferable to use monoalkyl ethers such as triethylene glycol, propylene glycol and dipropylene glycol. 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, ethylene glycol monopropyl ether is preferable. It can also be used for additional dilution.

  Furthermore, in addition to the above solvent, a known stabilizing solvent component such as water can be added. In order to form a silicon oxide-based material layer having a thickness of 1 to 10 nm in a 152 mm (6 inch) square photomask blank. The amount of the total solvent containing water is 1,000 to 250,000 parts by mass, particularly 10,000 to 200,000 parts by mass with respect to 100 parts by mass of the hydrolyzable / condensed product of the hydrolyzable silane compound. Is preferred.

  Further, in order to stably store and use the composition for forming a silicon oxide-based material film, it is preferable to add a stabilizer. Examples of the stabilizer include monovalent or divalent or higher organic acids having 1 to 30 carbon atoms. Acids added at this time include formic acid, acetic acid, propionic acid, butanoic acid, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, oleic acid, stearic acid, linoleic acid, linolenic 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, itaconic acid, maleic acid, fumaric acid, citraconic acid, citric acid and the like. In particular, oxalic acid, maleic acid, formic acid, acetic acid, propionic acid, citric acid and the like are preferable. In order to maintain stability, two or more kinds of acids may be mixed and used. The addition amount is 0.001 to 25 parts by mass, preferably 0.01 to 15 parts by mass, more preferably 0.1 to 100 parts by mass of the hydrolyzable / condensate of the hydrolyzable silane compound contained in the composition. -5 parts by mass. The organic acid is blended so that the pH of the composition is preferably 0 ≦ pH ≦ 7, more preferably 0.3 ≦ pH ≦ 6.5, and still more preferably 0.5 ≦ pH ≦ 6. It is also preferable.

  The composition for forming a silicon oxide-based material film prepared as described above is applied onto a film made of a material containing a transition metal and silicon as a workpiece by a known method such as a spin coat method, and heated. By performing the treatment, a photomask blank having the silicon oxide material film of the present invention as a hard mask film is obtained. In particular, when the crosslinking formation accelerator represented by the general formula (2) or (3) is added, a photomask having a hard mask film having sufficient etching resistance even when the film thickness is 1 to 10 nm. It will be blank.

  In the above film formation, a Si—O—Si bridge having a sufficient density is formed by heating after coating. The heating conditions at this time are within the temperature range of 100 to 400 ° C. A time range of 1,200 seconds is preferably used. In particular, when the crosslinking formation accelerator represented by the general formula (2) or (3) is blended, there is almost no adverse effect on the film formed below the hard mask film, such as an optical film of the photomask blank. Even when heated at a temperature of not higher than 300 ° C., a sufficient crosslinking density can be obtained and high etching resistance to chlorine-based dry etching conditions can be obtained.

  In the photomask blank of the present invention, one or more films are formed on a transparent substrate such as a quartz substrate, and the film on at least the surface side (side away from the substrate) of the film contains a transition metal and silicon. Made of materials. A hard mask film for dry etching, which is a silicon oxide-based material film, is provided on the layer containing the transition metal and silicon.

  The above-mentioned silicon oxide-based material film is formed on a film made of a material containing a transition metal and silicon. On the surface side of the film made of a material containing a transition metal and silicon, a photomask is exposed. In order to control the reflectance with respect to the exposure light when used, an antireflection layer is provided, and a material containing nitrogen and / or oxygen in addition to a transition metal and silicon is preferably selected for the antireflection layer. The film made of a material containing a transition metal and silicon may be a light-shielding film or a halftone phase shift film, and between the transparent substrate and the film made of a material containing a transition metal and silicon, A functional film may be provided.

  As the transition metal, one or more selected from titanium, vanadium, cobalt, nickel, zirconium, niobium, molybdenum, hafnium, tantalum and tungsten are preferable, but molybdenum is particularly preferable from the viewpoint of dry etching processability.

  The composition of the light shielding film and the composition of the light shielding layer constituting the light shielding film are 10 atomic% or more and 95 atomic% or less, particularly 30 atomic% or more and 85 atomic% or less for silicon, and 0.5 atomic% or more and 35 atomic% or less for transition metal. In particular, it is preferably 1 atomic% or more and 20 atomic% or less. Further, when a light element is included, oxygen is 0 atomic% or more and 50 atomic% or less, especially more than 0 atomic% and 30 atomic% or less, and nitrogen is contained. It is preferably more than 0 atomic% and 50 atomic% or less, particularly preferably more than 0 atomic% and 30 atomic% or less. Moreover, if it is 5 atomic% or less, other light elements, such as carbon and hydrogen, may be contained.

  The composition of the antireflection layer constituting the light-shielding film is as follows: silicon is 10 atomic% to 80 atomic%, particularly 30 atomic% to 50 atomic%, transition metal is 0.5 atomic% to 35 atomic%, particularly 1 atom. % To 20 atomic% or less, and when light elements are included, oxygen is 0 atomic% to 60 atomic%, particularly more than 0 atomic% to 50 atomic% or less, and nitrogen is 0 atomic%. It is preferably 57 atom% or less, particularly 20 atom% or more and 50 atom% or less, and the total of oxygen and nitrogen is preferably 10 atom% or more and 60 atom% or less. Moreover, if it is 5 atomic% or less, other light elements, such as carbon and hydrogen, may be contained.

  On the other hand, the composition of the halftone phase shift film is 30 atomic% or more and 70 atomic% or less of silicon, particularly 30 atomic% or more and 50 atomic% or less, and the transition metal exceeds 0 atomic% and 30 atomic% or less, particularly 1 atomic%. Preferably, the content is 20 atomic% or less, and when light elements are included, oxygen exceeds 0 atomic% to 60 atomic% or less, particularly 3 atomic% to 50 atomic%, and nitrogen exceeds 0 atomic%. It is preferably 57 atom% or less, particularly 5 atom% or more and 50 atom% or less, and the total of oxygen and nitrogen is preferably 30 atom% or more and 60 atom% or less. Moreover, if it is 5 atomic% or less, other light elements, such as carbon and hydrogen, may be contained.

  Each of the antireflection layer and the light shielding layer constituting the light shielding film may have a single-layer structure or a multilayer structure (including a structure having a gradient composition). Further, the light shielding film may have a structure in which the composition is inclined, or may have an antireflection function on the surface side.

  The light-shielding film can be a light-shielding film having the same composition of the antireflection layer and the light-shielding layer, that is, a single-layer light-shielding film in a state in which the reflectance is suppressed. It will be thick. Therefore, in order to obtain high processing accuracy, the light shielding film is composed of an antireflection layer and a light shielding layer having different compositions, and the total content of oxygen and nitrogen in the antireflection layer is made higher than that of the light shielding layer. It is preferable.

  The film thickness of the light shielding film is the above-mentioned material, and the required optical characteristics, that is, the optical density of the light shielding film with respect to the exposure light is usually 2.5 or more. If there is a light absorbing layer, it may be set so that the optical density with respect to the exposure light is 2.5 or more. Specifically, for example, an optical density suitable for a film thickness of about 30 to 200 nm can be found. Note that the thickness of the antireflection layer in the light shielding film is preferably 4 nm or more for ArF excimer laser exposure, and preferably about 5 to 20 nm in order to obtain a strong antireflection effect.

  The processing method of the photomask blank of the present invention will be described as follows by taking an example having a light shielding film. In the case of a light-shielding film having an antireflection layer and a light-shielding layer, and also in the case of a photomask blank for a binary mask and a halftone phase shift mask blank having a halftone phase shift film, the silicon oxide material film is used. The relationship with the hard mask is the same, and the same effect can be obtained in either case.

  First, a resist film is formed on a silicon oxide-based material hard mask film formed on a light-shielding film made of a material containing transition metal and silicon. The resist used here is selected according to the pattern exposure method, but in order to form a fine pattern using the photomask blank of the present invention, generally a method by electron beam exposure is used. A chemically amplified electron beam resist using an aromatic resin is used. Depending on the type of pattern, this resist can be used either positively or negatively. The resist film is irradiated with a pattern of an electron beam according to the resist to be used, and then a resist pattern is formed through a heating and developing process.

The obtained resist pattern is first transferred to a hard mask film of silicon oxide-based material by dry etching. As the dry etching conditions, fluorine-based dry etching under a gas condition containing fluorine that is commonly used can be used. Examples of the gas containing fluorine include fluorine gas, gas containing carbon and fluorine such as CF ₄ and C ₂ F ₆ , gas containing sulfur and fluorine such as SF ₆ , and fluorine such as helium. It may be a mixed gas of a gas not containing and a gas containing fluorine. Moreover, you may add gas, such as oxygen, as needed.

  Next, the resist film is peeled or left, and the pattern is transferred to a light-shielding film made of a material containing a transition metal and silicon using the obtained pattern made of the silicon oxide-based material as a hard mask. As the dry etching used here, chlorine-based dry etching in which the oxygen content ratio is controlled can be used. JP-A-2001-27799 (Patent Document 7) discloses that the MoSiON film can be processed by chlorine-based dry etching. When this condition is applied, the oxidation of the present invention, which is a hard mask film, is disclosed. The silicon-based material film functions effectively as a material having etching resistance.

The dry etching conditions are, for example, a mixing ratio of chlorine gas and oxygen gas (Cl ₂ gas: O ₂ gas) in a volume ratio of 1: 0.001 to 1: 1, preferably 1: 0.001 to 1: If necessary, dry etching can be performed using a gas mixed with an inert gas such as helium. Further, as other etching conditions, the gas pressure is set to 0.1 to 1,000 mtorr, the etching power is set to 10 to 10,000 W, for example, and the etching conditions can be appropriately adjusted. Furthermore, dry etching can be performed using a gas mixed with an inert gas such as helium as necessary. If conditions other than the mixing ratio of chlorine gas and oxygen gas, such as gas pressure and etching power, are constant, the etching selectivity of the material containing transition metal and silicon is increased by increasing the mixing ratio of chlorine gas. However, the optimum conditions for the etching conditions may be selected by preparing a material sample to be etched and a sample of a material not to be etched, and selecting an appropriate condition from the above range.

  In contrast to the above-mentioned chlorine-based dry etching, the pattern obtained from a silicon oxide-based material film obtained by adding a crosslinking formation accelerator is particularly high even if the silicon oxide-based material film is a thin film of about 2 to 30 nm. Since it has Si—O—Si crosslink density, etching resistance is high, and a pattern is transferred with high accuracy. The silicon oxide-based material film may be left as a part of the pattern after completion of the light shielding film pattern, or may be a part of the layer constituting the antireflection film or the antireflection film, or may be removed.

  When the pattern is peeled off by the silicon oxide material after the light shielding pattern is completed by dry etching, the peeling can be carried out by wet etching like a general SOG film. It can also be removed by dry etching. When removed by dry etching, it can also be removed by fluorine-based etching. However, in etching using chlorine gas and oxygen gas, if the ratio of oxygen gas in the etching gas is increased, transition metal and silicon are contained. Therefore, the etching rate of the silicon oxide material can be relatively increased, and only the silicon oxide material can be selectively removed by etching.

  EXAMPLES Hereinafter, although a synthesis example and an Example are shown and this invention is demonstrated concretely, this invention is not limited by the following Example.

[Synthesis Example 1]
60 g of methanol, 200 g of ion-exchanged water and 1 g of 35% hydrochloric acid were charged into a 1,000 ml glass flask, and a mixture of 50 g of tetraethoxysilane, 100 g of methyltrimethoxysilane and 10 g of phenyltrimethoxysilane was added at room temperature. The product was subjected to hydrolysis and condensation for 8 hours at room temperature, and then methanol and by-product ethanol were distilled off under reduced pressure. Thereto, 800 ml of ethyl acetate and 300 ml of propylene glycol monopropyl ether were added, the aqueous layer was separated, and hydrochloric acid used in the reaction was removed. To the remaining organic layer, 100 ml of a 1% maleic acid aqueous solution was added, stirred, allowed to stand, and separated. After repeating this twice, 100 ml of ion-exchanged water was added, stirred, allowed to stand, and separated. This was repeated three times. 200 ml of propylene glycol monopropyl ether was added to the remaining organic layer and concentrated under reduced pressure to obtain 300 g of a propylene glycol monopropyl ether solution of silicon-containing compound 1 (polymer concentration 21%). The resulting solution was analyzed for chloro ions by ion chromatography, but was not detected. It was Mw = 2,000 when the polystyrene conversion weight molecular weight of the silicon containing compound 1 was measured.

[Synthesis Example 2]
Propylene glycol of silicon-containing compound 2 in the same manner except that 50 g of tetraethoxysilane, 100 g of methyltrimethoxysilane and 10 g of phenyltrimethoxysilane in Synthesis Example 1 were replaced with 100 g of methyltrimethoxysilane and 20 g of phenyltrimethoxysilane. 300 g of monopropyl ether solution (polymer concentration 19%) was obtained. The resulting solution was analyzed for chloro ions by ion chromatography, but was not detected. It was Mw = 3,000 when the polystyrene conversion weight molecular weight of the silicon-containing compound 2 was measured.

[Synthesis Example 3]
60 g of Synthesis Example 1 methanol, 200 g of ion exchange water, 1 g of 35% hydrochloric acid, 50 g of tetraethoxysilane, 100 g of methyltrimethoxysilane and 10 g of phenyltrimethoxysilane were added to 260 g of ion exchange water, 5 g of 65% nitric acid, 70 g of tetramethoxysilane, and methyl. 300 g of propylene glycol monopropyl ether solution of the silicon-containing compound 3 (polymer concentration 20%) was obtained by the same operation except that 70 g of trimethoxysilane and 10 g of phenyltrimethoxysilane were used. The resulting solution was analyzed for nitrate ions by ion chromatography, but was not detected. It was Mw = 2,500 when the polystyrene conversion weight molecular weight of the silicon-containing compound 3 was measured.

[Synthesis Example 4]
Charge ion exchange water 260g, 35% hydrochloric acid 1g into a 1,000ml glass flask, add tetramethoxysilane 70g, methyltrimethoxysilane 25g, silane compound 25g of the following formula [i] and phenyltrimethoxysilane 10g at room temperature. It was. The product was subjected to hydrolysis and condensation for 8 hours at room temperature, and then by-product methanol was distilled off under reduced pressure. Thereto, 800 ml of ethyl acetate and 300 ml of propylene glycol monopropyl ether were added, and the aqueous layer was separated. To the remaining organic layer, 100 ml of ion exchange water was added, stirred, allowed to stand, and separated. This was repeated three times. 200 ml of propylene glycol monopropyl ether was added to the remaining organic layer and concentrated under reduced pressure to obtain 300 g of a propylene glycol monopropyl ether solution of silicon-containing compound 4 (polymer concentration 20%). The resulting solution was analyzed for chloro ions by ion chromatography, but was not detected. It was Mw = 1,800 when the polystyrene conversion weight molecular weight of the silicon-containing compound 4 was measured.

[Synthesis Example 5]
200 g of ethanol, 100 g of ion-exchanged water, and 3 g of methanesulfonic acid are charged in a 1,000 ml glass flask, and a mixture of 40 g of tetramethoxysilane, 10 g of methyltrimethoxysilane, 50 g of a silane compound of the following formula [ii] and 10 g of phenyltrimethoxysilane is prepared. Added at room temperature. The product was subjected to hydrolysis and condensation for 8 hours at room temperature, and then by-product methanol was distilled off under reduced pressure. Thereto, 800 ml of ethyl acetate and 300 ml of propylene glycol monoethyl ether were added, and the aqueous layer was separated. To the remaining organic layer, 100 ml of ion exchange water was added, stirred, allowed to stand, and separated. This was repeated three times. 200 ml of propylene glycol monoethyl ether was added to the remaining organic layer and concentrated under reduced pressure to obtain 300 g of a propylene glycol monoethyl ether solution of a silicon-containing compound 5 (polymer concentration 20%). When the resulting solution was analyzed for methanesulfonic acid ions by ion chromatography, it was found that 99% of those used in the reaction had been removed. It was Mw = 2,100 when the polystyrene conversion weight molecular weight of the silicon-containing compound 5 was measured.

[Examples 1 to 10]
The composition for forming a silicon-containing film is prepared by mixing the silicon-containing compounds 1 to 5, the acid, the cross-linking formation accelerator, the solvent, and the additive in the proportions shown in Table 1 and filtering with a 0.1 μm fluororesin filter. Each product solution was prepared and Sol. 1-10.

ＴＰＳＯＡｃ：酢酸トリフェニルスルホニウム（光分解性熱架橋形成促進剤）
ＴＰＳＯＨ：水酸化トリフェニルスルホニウム（光分解性熱架橋形成促進剤）
ＴＰＳ−ＭＡ：マレイン酸モノ（トリフェニルスルホニウム）（光分解性熱架橋形成促進剤）
ＴＭＡＯＡｃ：酢酸テトラメチルアンモニウム（非光分解性熱架橋形成促進剤）
ＴＰＳ−Ｎｆ：トリフェニルスルホニウムノナフルオロブタンスルホネート（光酸発生剤）
ＴＰＳＮ：硝酸トリフェニルスルホニウム（光分解性熱架橋形成促進剤）

TPSOAc: Triphenylsulfonium acetate (photodegradable thermal crosslinking formation accelerator)
TPSOH: Triphenylsulfonium hydroxide (photodegradable thermal crosslinking formation accelerator)
TPS-MA: Mono (triphenylsulfonium) maleate (photodegradable thermal crosslinking formation accelerator)
TMAOAc: tetramethylammonium acetate (non-photodegradable thermal crosslinking formation accelerator)
TPS-Nf: Triphenylsulfonium nonafluorobutanesulfonate (photoacid generator)
TPSN: Triphenylsulfonium nitrate (photodegradable thermal crosslinking accelerator)

  A light shielding film (film thickness: 40 nm) made of molybdenum, silicon, and nitrogen was formed on a quartz substrate using a DC sputtering apparatus using two targets. Argon gas and nitrogen gas were used as the sputtering gas, and the internal pressure in the chamber was adjusted to 0.05 Pa. Two types of targets were used, a silicon target and a molybdenum silicide target. Sputtering was performed while simultaneously applying power to these targets, and deposition was performed while rotating the substrate. When the composition of the obtained light shielding film was examined by ESCA, it was Mo: Si: N = 1: 3: 1.5 (atomic ratio). Next, an antireflection film (film thickness: 15 nm) was formed on the light shielding film by the same method as the light shielding film. The composition of the antireflection film was Mo: Si: N = 1: 5: 5 (atomic ratio). Furthermore, Sol. Each of 1 to 10 was spin-coated and baked at 250 ° C. for 10 minutes to form a 5 nm-thick silicon oxide material film as a hard mask film.

  Next, Shin-Etsu Chemical Co., Ltd. electron beam chemically amplified resist solution SEBP-9902 was applied onto the silicon oxide-based material film using a spin coater to form a 90 nm-thick resist film.

  Next, exposure is performed using an electron beam exposure apparatus (EBM5000 acceleration voltage 50 keV manufactured by NuFLARE), baking is performed at 110 ° C. for 10 minutes (PEB: post exposure bake), and 2.38 mass% of tetramethylammonium hydroxide is added. Development was performed with an aqueous solution to obtain a positive pattern including a 200 nm line and space pattern and a 100 nm line pattern. In addition, the said exposure is exposed by making the exposure amount which resolves 1: 1 the top and bottom of the 200 nm line and space obtained as the optimal exposure amount (sensitivity: Eop).

Next, using the resist pattern as a mask, the silicon oxide-based material film exposed from the resist pattern was dry-etched under the following fluorine-based dry etching conditions and patterned by a dry etching apparatus.
RF1 (RIE): CW 54W
RF2 (ICP): CW 325W
Pressure: 5mTorr
SF ₆ : 18 sccm
O ₂ : 45 sccm
Etching time: 1 min

Next, using the patterned silicon oxide-based material film as a hard mask, the exposed antireflection film and light shielding film were subjected to dry etching under the following chlorine-based dry etching conditions containing oxygen and patterned.
RF1 (RIE): Pulse 700V
RF2 (ICP): CW 400W
Pressure: 6mTorr
Cl ₂ : 185 sccm
O ₂ : 1 sccm
He: 9.25 sccm
Etching time: 15 min

Further, the patterned silicon oxide-based material film was removed by dry etching under the following chlorine-based dry etching conditions containing oxygen.
RF1 (RIE): Pulse 700V
RF2 (ICP): CW 400W
Pressure: 6mTorr
Cl ₂ : 185 sccm
O ₂ : 55 sccm
He: 9.25 sccm
Etching time: 15 min

  In any case of Examples 1 to 10, the silicon oxide-based material film effectively functions as a hard mask film, and even when the silicon oxide-based material film is thin, it is used as a hard mask film for chlorine-based dry etching. It was confirmed that there was sufficient resistance and precision machining of transition metal silicon-based materials was possible.

Claims (5)

A photomask blank in which a film made of a material containing a transition metal and silicon is formed on a transparent substrate with or without another film, and a hard mask film for dry etching is provided on the film. And
The hard mask film has the following general formula (1)
R _n SiX _4-n (1)
(In the formula, R is a hydrogen atom, a methyl group, an oxygen atom or an oxygen-containing functional group and an aliphatic hydrocarbon group or aromatic hydrocarbon group having 2 to 12 carbon atoms, and X is the number of carbon atoms. An alkoxy group having 1 to 4 carbon atoms, a halogen atom, or an alkylcarbonyloxy group having 2 to 5 carbon atoms, and n is 0 or 1.)
A film is formed using a composition for forming a silicon oxide-based material film containing a hydrolyzable silane compound hydrolyzate / condensate obtained using a raw material containing at least one silane compound represented by A photomask blank, which is a silicon oxide material film. The composition for forming a silicon oxide-based material film further comprises the following general formula (2) or (3):
L _a H _b X (2)
(Wherein L is lithium, sodium, potassium, rubidium or cesium, X is a hydroxyl group, or a monovalent or divalent or higher organic acid group having 1 to 30 carbon atoms, a is an integer of 1 or more, and b is 0. Or an integer of 1 or more, and a + b is a valence of a hydroxyl group or an organic acid group.)
MA (3)
(Wherein M is tertiary sulfonium, secondary iodonium or quaternary ammonium, and A is a non-nucleophilic counter ion.)
The photomask blank according to claim 1, comprising a crosslinking formation accelerator represented by the formula:   The hydrolyzable silane compound is a simple substance or a mixture of two or more hydrolyzable silane compounds containing 70% or more of the compound represented by the general formula (1) based on silicon. Or the photomask blank of 2.   4. The photomask blank according to claim 1, wherein the transition metal is molybdenum. Forming a resist pattern on the photomask blank according to any one of claims 1 to 4,
Using a step of transferring the resist pattern to the hard mask film by fluorine-based dry etching and the hard mask film pattern formed by the pattern transfer, a gas having an oxygen / chlorine concentration of 0.001 to 0.25 (molar ratio) A method for processing a photomask blank, comprising a step of transferring a pattern to a film made of a material containing the transition metal and silicon by chlorine dry etching.