JP2009116003A - Material for multilayer processing and pattern forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pattern forming method using a material for multilayer processing, capable of forming a film having a high etching selective ratio to a film formed from an organic material, at a low temperature. <P>SOLUTION: The pattern forming method is characterized in that: a multilayered body is formed on a substrate, wherein an underlay organic film that can be dry-etched, an intermediate layer formed by using the material for multilayer processing, which contains a metal compound (W) that can generate a hydroxyl group by hydrolysis, and an overlay resist film, are laminated in order; and the multilayered body is subjected to processing including dry etching to form a pattern. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pattern forming method using a multilayer process material.

  In general, in semiconductor manufacturing, a laminate including a resist film formed on a substrate such as a silicon wafer is subjected to treatment including dry etching, for example, by selectively exposing the resist film to form a resist pattern on the resist film, Using this as a mask, dry etching is performed to form a pattern on the substrate.

As one of the resist pattern forming methods, a three-layer resist method is known (see, for example, Patent Document 1). In the three-layer resist method, first, an organic material containing a film-forming resin or the like is applied on a substrate to provide a lower organic film, an intermediate layer is provided thereon, and a resist film is further provided thereon. A resist pattern is formed by a normal lithography technique, and the intermediate layer is etched by using the resist pattern as a mask to form a pattern in the intermediate layer. Then, using the patterned intermediate layer as a mask, the lower organic film is formed by oxygen plasma. Etching is performed to form a pattern on the substrate.
A two-layer resist method having a smaller number of steps than the three-layer resist method has also been proposed (see, for example, Patent Documents 2 and 3). In the two-layer resist method, a lower layer organic film is provided on a substrate in the same manner as the three-layer resist method, and then a resist film is provided thereon, a resist pattern is formed by ordinary lithography technology, and the resist pattern is masked Etching with oxygen plasma or the like is performed to form a pattern in the lower organic film. Then, etching is performed using the pattern as a mask to form a pattern on the substrate.

In a multilayer process application in which a pattern is formed on a multilayer laminate including such a resist film, the lower layer organic film is etched for the material for forming the intermediate layer in the three-layer resist method or the resist film in the two-layer resist method. Therefore, it is necessary to have a high etching selectivity with respect to a film formed from an organic material used as a lower organic film.
At present, silica (SiO ₂ ) -based coatings are mainly used as such multilayer process materials. For example, as the intermediate layer in the three-layer resist method, an inorganic film (SiO ₂ film) containing SiO ₂ as a main component is mainly used because etching resistance is good. As a resist film in the two-layer resist method, a resist film containing a silicon-containing polymer is used.

On the other hand, chemical vapor deposition (hereinafter sometimes referred to as CVD), SOG (spin-on-glass), and the like are known as methods conventionally used for forming a silica-based film such as a SiO ₂ film. ing. The SOG method is generally a film containing SiO ₂ as a main component (hereinafter referred to as an SOG coating) by applying a solution (hereinafter sometimes referred to as an SOG solution) in which a silicon compound is dissolved in an organic solvent, followed by heat treatment. (See, for example, Patent Documents 4 to 6).
JP 2001-51422 A JP-A 61-239243 Japanese Patent Laid-Open No. 62-25744 Japanese Patent Publication No. 8-3074 Japanese Patent No. 2739902 Japanese Patent No. 3228714

However, in order to obtain a high-quality silica-based film such as a film having a high etching selectivity with respect to a film formed from an organic material by these methods, a dense oxide film is formed by baking at a high temperature of 200 ° C. or higher. There is a need to. For example, a silica-based film formed by a CVD method needs to be reflowed at a high temperature of about 950 to 1100 ° C. after the film formation in order to flatten the surface. Further, in the SOG method, in order to form a silica-based film having a flat surface, it is necessary to bake at a temperature of, for example, about 200 to 450 ° C. after applying the coating liquid. Such a high temperature process has problems such as low manufacturing efficiency and high cost.
An object of the present invention is to provide a pattern forming method using a multilayer process material capable of forming a film having a high etching selectivity with respect to a film formed from an organic material at a low temperature.

  The first aspect of the present invention that solves the above problems uses a multilayer process material containing, on a substrate, a lower organic film that can be dry-etched and a metal compound (W) that can generate a hydroxyl group by hydrolysis. A pattern forming method, comprising: forming a multilayer laminate in which the formed intermediate layer and an upper resist film are sequentially laminated; and performing a process including dry etching on the multilayer laminate. It is.

  In the claims and the specification, “exposure” is a concept including general radiation irradiation, and includes, for example, electron beam drawing and irradiation through a mask.

  ADVANTAGE OF THE INVENTION According to this invention, the pattern formation method using the material for multilayer processes which can form the film | membrane which has a high etching selectivity with respect to the film | membrane formed from an organic material at low temperature can be provided.

≪Multilayer process material used in pattern formation process≫
First, a multilayer process material used for forming an intermediate layer in the pattern forming method of the present invention will be described.
The multilayer process material is used in a method of forming a pattern on a multilayer laminate including a resist film, and contains a metal compound (W) that can generate a hydroxyl group by hydrolysis.
When a multilayer processing material containing a metal compound (W) is applied on a surface (for example, a lower organic film described later) and brought into contact with water, preferably deionized water, the metal compound (W) is hydrolyzed, A hydroxyl group is generated, whereby a film (intermediate layer) containing a metal oxide is formed. The film thus obtained has high etching resistance and a high etching selectivity with respect to a film formed from an organic material.

The metal compound (W) can be used without particular limitation as long as it has a functional group capable of generating a hydroxyl group by hydrolysis.
It is desirable that the functional group is directly bonded to the metal atom.
The number of functional groups is preferably 2 or more per metal atom, more preferably 2 to 4, and particularly preferably 4. By having two or more functional groups, the hydroxyl groups generated by hydrolysis undergo dehydration condensation, and a plurality of metal compound (W) molecules are bonded together to form a good metal oxide film.

Examples of such a functional group include an alkoxy group, an isocyanate group, and a carbonyl group. Moreover, since a halogen atom also has the same function, a halogen atom is also contained in a functional group in this invention.
Examples of the alkoxy group include linear or branched alkoxy groups having 1 to 5 carbon atoms such as a methoxy group (-O-Me), an ethoxy group (-O-Et), and an n-propoxy group (-O-nPr). , Isopropoxy group (-O-iPr), n-butoxy group (-O-nBu) and the like.
Examples of the halogen atom include a chlorine atom, a fluorine atom, a bromine atom, and an iodine atom, and among them, a chlorine atom is preferable.
Among the above, alkoxy groups and isocyanate groups are particularly reactive groups such as carboxy groups and hydroxyl groups on the surface (for example, the surface of a lower organic film described later) on which the multilayer process material is applied to form an intermediate layer. When present, it is preferable because it undergoes a condensation reaction. Thereby, the hydroxyl group formed after hydrolysis and the reactive group on the surface undergo a condensation reaction, and the intermediate layer and the surface are firmly adhered.
Among the above, carbonyl groups and halogen atoms are particularly reactive groups such as carboxy groups and hydroxyl groups on the surface (for example, the surface of the lower organic film described later) on which the multilayer process material is applied to form an intermediate layer. If present, it is preferred because it adsorbs to it. Thereby, the hydroxyl group formed after hydrolysis and the reactive group on the surface are adsorbed, and the intermediate layer and the surface are firmly adhered.
Among these, an isocyanate group and a halogen atom (especially a chlorine atom) are preferable because they are highly active and a metal oxide film can be easily formed without any heat treatment, and an isocyanate group is particularly preferable.

The metal compound (W) may have an atom or an organic group other than the above-mentioned “functional group capable of generating a hydroxyl group by hydrolysis”. Examples of the atom include a hydrogen atom. Examples of the organic group include an alkyl group (preferably a lower alkyl group having 1 to 5 carbon atoms) and the like, and an ethyl group and a methyl group are preferable.
In the present specification and claims, “alkyl group” includes linear, branched and cyclic monovalent saturated hydrocarbon groups unless otherwise specified.

Here, in the present invention, the metal constituting the metal compound (W) includes boron, silicon, germanium, antimony, selenium, tellurium and the like in addition to a normal metal.
Suitable examples of the metal composing the metal compound (W) include titanium, zirconium, aluminum, niobium, silicon, boron, lanthanide, yttrium, barium, cobalt, iron, zirconium, tantalum, and the like. Silicon is preferred, and silicon is particularly preferred.
Further, the number of metal atoms in the metal compound (W) may be 1 or 2 or more, preferably 1.

Examples of the metal compound (W) include the following.
Examples of the metal compound having an alkoxy group (hereinafter sometimes referred to as “metal alkoxides”) include the following.
For example, titanium butoxide (Ti (O-nBu) ₄ ), zirconium propoxide (Zr (O-nPr) ₄ ), aluminum butoxide (Al (O-nBu) ₃ ), niobium butoxide (Nb (O-nBu) ₅ ) Metal alkoxide compounds other than rare earth metals such as silicon tetramethoxide (Si (O-Me) ₄ ) and boron ethoxide (B (O-Et) ₃ );
Metal alkoxide compounds of rare earth metals such as lanthanide isopropoxide (Ln (O-iPr) ₃ ), yttrium isopropoxide (Y (O-iPr) ₃ );
Double alkoxide compounds such as barium titanium alkoxide (BaTi (OR ⁶⁰ ) _x ) (where “R ⁶⁰ ” is a lower alkoxy group having 1 to 5 carbon atoms, and X is an integer of 2 to 4). ;
It has two or more alkoxy groups such as methyltrimethoxysilane (MeSi (O-Me) ₃ ) and diethyldiethoxysilane (Et ₂ Si (O-Et) ₂ ), and has an organic group other than the alkoxy group. Metal alkoxide compounds;
Examples thereof include metal alkoxide compounds having a ligand such as acetylacetone and having two or more alkoxy groups.
Further, fine particles of alkoxide sol or alkoxide gel obtained by adding a small amount of water to the metal alkoxides and partially hydrolyzing and condensing them can also be used.
Further, a binuclear or cluster type alkoxide compound having a plurality of or plural kinds of metal elements such as titanium butoxide tetramer (C ₄ H ₉ O [Ti (OC ₄ H ₉ ) ₂ O] ₄ C ₄ H ⁹ ). In addition, a polymer based on a metal alkoxide compound cross-linked one-dimensionally through an oxygen atom is also included in the metal alkoxides.

Examples of the metal compound having an isocyanate group include compounds having two or more isocyanate groups represented by the general formula “M (NCO) _m ” (wherein M is a metal atom, and m is 2 to 4). Is an integer).
Specific examples include tetraisocyanate silane (Si (NCO) ₄ ) titanium tetraisocyanate (Ti (NCO) ₄ ), zirconium tetraisocyanate (Zr (NCO) ₄ ), aluminum triisocyanate (Al (NCO) ₃ ), and the like. It is done.

The metal compound having a halogen atom has a general formula “M (X) _n ” (wherein M is a metal atom, X is a kind selected from a fluorine atom, a chlorine atom, a bromine atom and an iodine atom, n Is an integer of 2 to 4), and a metal halide compound having 2 or more (preferably 2 to 4) halogen atoms.
The compound having a halogen atom may be a metal complex.
Specifically, tetrachlorotitanium (TiCl ₄ ), tetrachlorosilane (SiCl ₄ ), and the like can be given. The metal complexes also include cobalt chloride (CoCl ₂₎ or the like.

Examples of the metal compound having a carbonyl group include metal carbonyl compounds such as titanium oxoacetyl acetate (TiO (CH ₃ COCH ₂ COO) ₂ ), pentacarbonyl iron (Fe (CO) ₅ ), and multinuclear clusters thereof.

Among these, since a metal oxide film having particularly high activity and good etching resistance can be easily formed without particularly performing heat treatment, two or more isocyanate groups and / or halogen atoms (preferably 2 (˜4) silicon compounds are preferred. The number of silicon in one molecule may be 1 or 2 or more, preferably 1.
Especially, the compound represented by the following general formula (S-1) is preferable.
SiW _a (S-1)
[Wherein, a represents an integer of 2 to 4, W represents an isocyanate group (NCO group) or a halogen atom, and a plurality of W may be the same or different from each other. ]

a is an integer of 2 to 4, and is preferably 4.
W is an isocyanate group or a halogen atom, and the halogen atom is the same as described above, and is preferably a chlorine atom. Among these, an isocyanate group is preferable.

  A metal compound (W) can be used 1 type or in mixture of 2 or more types.

In addition to the metal compound (W), an organic compound can be added to the multilayer process material. Thereby, a composite film of a metal oxide and an organic compound can be formed.
The organic compound is not particularly limited as long as it dissolves in a solvent used for a multilayer process material described later. The term “dissolution” as used herein includes not only the case where the organic compound is dissolved alone, but also the case where it is dissolved in a solvent such as chloroform by complexing with a metal alkoxide, such as 4-phenylazobenzoic acid.
There is no restriction | limiting in particular about the molecular weight of an organic compound.

As an organic compound, from the viewpoint of strengthening contact with a pattern, a compound having a plurality of reactive groups (preferably a hydroxyl group or a carboxy group) and having a solid property at room temperature (25 ° C.) should be used. Is preferred.
Examples of such organic compounds include polymer compounds having a hydroxyl group or a carboxy group such as polyacrylic acid, polyvinyl alcohol, polyvinylphenol, polymethacrylic acid, and polyglutamic acid; polysaccharides such as starch, glycogen, and colominic acid; glucose, A disaccharide such as mannose, a monosaccharide; a porphyrin compound having a hydroxyl group or a carboxy group at the end, a dendrimer, or the like is preferably used.

Moreover, a cationic polymer compound can also be preferably used as the organic compound. Since metal alkoxides and metal oxides can interact anionically with the cation of the cationic polymer compound, a strong bond can be realized.
Specific examples of the cationic polymer compound include PDDA (polydimethyldiallylammonium chloride), polyethyleneimine, polylysine, chitosan, and a dendrimer having an amino group at the terminal.

These organic compounds function as a structural component for forming a thin film having high mechanical strength. It can also serve as a functional part for imparting a function to the obtained thin film, or as a component for removing holes after film formation and forming vacancies corresponding to the molecular shape in the thin film. .
An organic compound can be used 1 type or in mixture of 2 or more types.

Moreover, in the said multilayer process material, it is desirable to use as a solution which melt | dissolved the metal compound (W) and the organic compound mix | blended as needed in a suitable solvent.
Examples of the solvent include methanol, ethanol, propanol, hexane, heptane, toluene, benzene, cumene, and the like, and heptane and cumene are preferable because a dense film can be formed. A solvent can be used 1 type or in mixture of 2 or more types.
The solid content concentration of the solution (the total concentration of the metal compound (W) and the organic compound used as necessary) is about 1 to 200 mM, preferably 50 to 150 mM, and more preferably 50 to 100 mM. Within this range, a more uniform film can be formed, which is preferable.

The multilayer processing material is used in a method for forming a pattern on a multilayer laminate including a resist film.
Here, the “multilayer laminate” is a laminate formed by laminating a resist film and another layer (a layer other than the resist film) formed of a material different from the resist film on the substrate. Means the body.
“Multilayer process material” means a material that forms one or more layers other than the resist film, which are laminated on a substrate.

  The multilayer processing material is used for forming an intermediate layer in the pattern forming method of the present invention.

≪Pattern formation method≫
The pattern forming method of the present invention comprises a multilayer laminate in which a lower organic film capable of dry etching, an intermediate layer formed using the multilayer processing material, and an upper resist film are sequentially laminated on a substrate. In this method, a pattern is formed by performing a process including dry etching on the multilayer laminate.

The pattern forming method of the present invention is not particularly limited as long as it uses the above multilayer laminate and performs a treatment including dry etching on the multilayer laminate.
The pattern formation method of this invention can be performed as follows, for example.
First, a laminated body forming step of forming a multilayer laminated body in which a lower organic film that can be dry-etched, an intermediate layer formed using the multilayer processing material, and an upper resist film are sequentially laminated on a substrate When,
Exposing the upper resist film and forming a resist pattern on the upper resist film by alkali development (resist pattern forming process);
Forming a pattern in the intermediate layer by performing dry etching of the intermediate layer using the resist pattern as a mask pattern (intermediate layer etching step);
A step of forming a pattern in the lower organic film by performing dry etching of the lower organic film using the resist pattern and the pattern of the intermediate layer as a mask pattern (lower organic film etching process) is sequentially performed. it can.

Hereinafter, an example of preferable embodiment is shown about each process.
<Laminated body formation process>
First, a solution of an organic material for forming a lower organic film is applied on a substrate such as a silicon wafer with a spinner or the like, preferably at 200 to 300 ° C. for 30 to 300 seconds, preferably 60 to 180 seconds. Baking is performed under heating conditions to form a lower organic film.

{substrate}
The substrate is not particularly limited, and a conventionally known substrate can be used. For example, a substrate for an electronic component or a substrate on which a predetermined wiring pattern is formed can be exemplified.
More specifically, examples of the substrate include a silicon wafer, a metal substrate such as copper, chromium, iron, and aluminum, and a glass substrate.
As a material for the wiring pattern, for example, copper, aluminum, nickel, gold or the like can be used.

{Lower layer organic film}
The organic film is an organic film that can be etched by a conventional dry etching method. The organic film is preferably insoluble in an alkaline developer used for development after exposure of the upper resist film.
By using an organic film that can be etched by a conventional dry etching method as a lower organic film, first, selective exposure of the upper resist film by lithography and alkali development are performed to form a resist pattern, and then the resist pattern is formed. By performing dry etching using the mask, the resist pattern is transferred to the intermediate layer (that is, the pattern is formed in the intermediate layer). Thereafter, the lower organic film is dry-etched using the intermediate layer pattern as a mask, whereby the resist pattern of the upper resist film and the intermediate layer pattern are transferred to the lower organic film (that is, the pattern is formed in the lower organic film). ) As a result, a pattern with a high aspect ratio can be formed without causing pattern collapse. The aspect ratio is represented by the ratio of the height of the pattern to the width below the pattern (substrate side).

  The organic film material for forming the lower organic film does not necessarily require sensitivity to an electron beam or light like the upper resist film. In the manufacture of semiconductor elements and liquid crystal display elements, resists and resins that are generally used may be used.

The lower organic film is particularly preferably a material that can be etched by oxygen plasma etching or CF ₄ gas or CHF ₃ gas, and particularly preferably a material that can be etched by oxygen plasma.
As such a material, a material mainly composed of at least one selected from the group consisting of novolak resin, acrylic resin and soluble polyimide is preferably used. These are easy to perform oxygen plasma etching, and at the same time have strong resistance to fluorocarbon gases used for etching silicon substrates and the like in subsequent processes.
Among these, a novolak resin and an acrylic resin having an alicyclic moiety or an aromatic ring in the side chain are preferably used because they are inexpensive and widely used and have excellent dry etching resistance in the subsequent steps.

As the novolak resin, those generally used in positive resist compositions can be used, and i-line and g-line resists containing a novolak resin as a main component can also be used.
The novolac resin is, for example, a resin obtained by addition condensation of an aromatic compound having a phenolic hydroxyl group (hereinafter simply referred to as “phenols”) and an aldehyde under an acid catalyst.

Examples of phenols include phenol, o-cresol, m-cresol, p-cresol, o-ethylphenol, m-ethylphenol, p-ethylphenol, o-butylphenol, m-butylphenol, p-butylphenol, 2, 3 -Xylenol, 2,4-xylenol, 2,5-xylenol, 2,6-xylenol, 3,4-xylenol, 3,5-xylenol, 2,3,5-trimethylphenol, 3,4,5-trimethylphenol , P-phenylphenol, resorcinol, hydroquinone, hydroquinone monomethyl ether, pyrogallol, phloroglicinol, hydroxydiphenyl, bisphenol A, gallic acid, gallic acid ester, α-naphthol, β-naphthol and the like.
Examples of aldehydes include formaldehyde, furfural, benzaldehyde, nitrobenzaldehyde, acetaldehyde and the like.
The catalyst for the addition condensation reaction is not particularly limited. For example, hydrochloric acid, nitric acid, sulfuric acid, formic acid, oxalic acid, acetic acid and the like are used as the acid catalyst.
The novolak resin has a mass average molecular weight of 3000 to 10000, preferably 6000 to 9000, and more preferably 7000 to 8000. If the mass average molecular weight is less than 3000, it may sublime when baked at a high temperature. If the mass average molecular weight exceeds 10,000, dry etching tends to be difficult, which is not preferable.

  As the novolak resin that can be used in the present invention, commercially available ones can be used. In particular, the mass average molecular weight (Mw) is 5000 to 50000, preferably 8000 to 30000, and the molecular weight is 500 or less, preferably A novolak resin having a content of low nuclei of 200 or less in the gel permeation chromatography method is 1% by mass or less, preferably 0.8% by mass or less. The content of the low nucleus is preferably as small as possible, and is desirably 0% by mass.

The “low molecular weight having a molecular weight of 500 or less” is detected as a low molecular fraction having a molecular weight of 500 or less when analyzed by GPC using polystyrene as a standard. “Low molecular weight less than 500 molecular weight” includes monomers that have not been polymerized and those that have a low degree of polymerization, such as those in which 2 to 5 molecules of phenols are condensed with aldehydes, depending on the molecular weight. .
The content (mass%) of the low nuclei having a molecular weight of 500 or less is graphed by taking the analysis result by the GPC method with the fraction number on the horizontal axis and the concentration on the vertical axis. It is measured by determining the percentage (%) of the area under the curve of the low molecular fraction.

By setting Mw of the novolak resin to 50000 or less, excellent embedding characteristics with respect to a substrate having fine irregularities are excellent, and by setting Mw to 5000 or more, etching resistance to a fluorocarbon gas or the like is excellent, which is preferable. .
In addition, when the content of the low-nuclear body having a molecular weight of 500 or less is 1% by mass or less, the embedding property with respect to the substrate having fine unevenness is improved. Although the reason why the embedding property is improved by reducing the content of the low nuclei is not clear, it is presumed that the degree of dispersion becomes small.

  As the acrylic resin, those generally used in positive resist compositions can be used. For example, a structural unit derived from a polymerizable compound having an ether bond and a polymerizable compound having a carboxyl group can be used. Mention may be made of acrylic resins containing derived structural units.

  Examples of the polymerizable compound having an ether bond include 2-methoxyethyl (meth) acrylate, methoxytriethylene glycol (meth) acrylate, 3-methoxybutyl (meth) acrylate, ethyl carbitol (meth) acrylate, phenoxypolyethylene glycol (meta ), (Meth) acrylic acid derivatives having an ether bond and an ester bond such as methoxypolypropylene glycol (meth) acrylate and tetrahydrofurfuryl (meth) acrylate. These compounds can be used alone or in combination of two or more.

  Examples of the polymerizable compound having a carboxyl group include monocarboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid; dicarboxylic acids such as maleic acid, fumaric acid, and itaconic acid; 2-methacryloyloxyethyl succinic acid, and 2-methacryloyloxyethyl. Examples include maleic acid, 2-methacryloyloxyethylphthalic acid, 2-methacryloyloxyethylhexahydrophthalic acid, and other compounds having a carboxyl group and an ester bond, and acrylic acid and methacrylic acid are preferred. These compounds can be used alone or in combination of two or more.

  The soluble polyimide is a polyimide that can be made liquid by the organic solvent as described above.

  The thickness of the lower organic film is preferably 50 to 500 nm, more preferably 100 to 400 nm. By setting the thickness of the lower organic film within this range, it is possible to form a resist pattern with a high aspect ratio and to obtain sufficient etching resistance during substrate etching.

Next, an intermediate layer is formed on the lower organic film using a multilayer process material.
{Middle layer}
The intermediate layer can be formed by applying a solution of the above-mentioned multilayer process material on the lower organic film and hydrolyzing it.
Specifically, a multilayer processing material is applied to the surface of the lower organic film to form a coating film (coating layer), and a hydrolysis treatment such as bringing the coating layer into contact with water is performed. As a result, the metal compound (W) in the multilayer process material is hydrolyzed to generate hydroxyl groups, and the hydroxyl groups present in the coating layer are dehydrated and condensed to form a coating layer containing a metal oxide.

At this time, after performing the hydrolysis treatment, if necessary, it is left to advance chemical adsorption and / or physical adsorption between the lower organic film and the metal compound (W) in the coating layer as described later. May be.
Here, “chemical adsorption” in the present specification means a reactive group (for example, a reactive group having a reactivity with a metal compound (W) on the surface of a film formed of an organic material such as a lower organic film or an upper resist film). When a hydroxyl group or a carboxy group is present, a chemical bond (covalent bond, hydrogen bond, coordinate bond, etc.) or a static bond (ionic bond, etc.) is formed between the reactive group and the metal compound (W). Thus, it means a state in which the metal compound (W) and its metal ions are bonded to the surface of the film formed from the organic material.

The method of applying the solution of the multilayer process material may be any method that allows the lower layer organic film and the multilayer process material to be in contact with each other. For example, a multilayer body in which the lower layer organic film is formed on the substrate is used for the multilayer process. Examples include a method of dipping in a material (dip coating method) and a method of laminating a multilayer processing material on the lower organic film of the laminate by a spin coating method. It can also be formed by a method such as an alternating adsorption method.
Among these, the dip coating method is preferable because it is simple, and the spin coating method is preferable because the film thickness can be made constant.

  The contact time and contact temperature between the lower organic film and the multilayer processing material (including the coating film forming step and then the step of allowing the adsorption to proceed if necessary) are the activities of the metal compound (W) used. It is different depending on the situation and cannot be limited. Generally, it may be determined within a range of 0 to 100 ° C. in 1 minute to several hours. In addition, by using a catalyst such as an acid or a base during the chemical reaction, the time required for these steps can be significantly shortened.

Further, from the viewpoint of film thickness uniformity, the excess metal compound (W) on the lower organic film may be washed and removed as necessary before hydrolysis. When the cleaning is performed, for example, the metal compound (W) adsorbed mainly by weak physical adsorption is removed, and the chemically adsorbed metal compound (W) remains uniformly on the surface of the lower organic film. A level thin film is formed with a uniform film thickness, extremely high accuracy, and high reproducibility. The cleaning is particularly effective when chemical adsorption occurs between the lower organic film and the metal compound (W).
An organic solvent that can be used as a solvent for the multilayer process material can be suitably used for the cleaning.
In addition, according to the spin coat method, the thickness of the coating film can be kept constant at all times, so that it is not necessary to perform this cleaning.
Cleaning can be performed by, for example, supplying an organic solvent to the surface of the coating film formed by applying the multilayer processing material by a spray method or the like, and then sucking excess organic solvent under reduced pressure. An immersion cleaning method, a spray cleaning method, a steam cleaning method, and the like are preferably employed.
As the temperature condition at the time of cleaning, the temperature of the operation for applying the multilayer process material is preferably employed.

Next, a hydrolysis treatment is performed. By the hydrolysis treatment, the metal compound (W) generates a hydroxyl group, and the hydroxyl group condenses to form a thin film (intermediate layer) made of a metal oxide on the surface of the lower organic film.
For the hydrolysis, a known method can be used without any particular limitation. For example, as described above, an operation of bringing a coating film formed by applying a multilayer processing material into contact with water is the most common.
As water, it is preferable to use deionized water in order to prevent impurities and the like from being produced and to produce a high-purity metal oxide.
Further, by using a catalyst such as an acid or a base in the hydrolysis, it is possible to significantly reduce the time required for these steps.
In addition, hydrolysis can be performed by immersing the laminate on which the coating film is formed in an organic solvent containing a small amount of water.
Moreover, when the said coating film contains the metal compound (W) with high reactivity with water, it hydrolyzes by utilizing the water | moisture content in air, for example, making it react in the air in which water vapor | steam exists. You can also.
The operation for forming the intermediate layer is preferably performed in an inert gas atmosphere from the viewpoint of reactivity control. In this case, the treatment is performed without using moisture in the air.
After hydrolysis, if necessary, the surface of the thin film is dried with a drying gas such as nitrogen gas. By this operation, a uniform thin film can be obtained.

The thickness of the intermediate layer can be adjusted by repeatedly performing the operation of contacting (coating) the lower organic film and the solution of the multilayer processing material and the operation of hydrolysis.
That is, a series of operations of applying a multilayer processing material on the lower organic film, forming a coating layer, washing as necessary, and then performing hydrolysis may be performed at least once, but preferably 5 times. By repeating the above, a uniform thin film (intermediate layer) having a desired thickness can be formed.

By such an operation, an intermediate layer of several nm to several tens nm, for example, and several hundreds nm can be formed with high accuracy depending on conditions.
For example, when a multilayer process material containing a metal alkoxide containing one kind of metal atom, such as titanium butoxide, is used as the metal compound (W), a thin film having a thickness of several angstroms may be sequentially laminated depending on contact conditions. it can.
In this case, the increase in the film thickness per cycle corresponds to the number of times the multilayer process material is stacked. On the other hand, when fine particles of alkoxide gel are used as the metal compound (W), a thin film having a thickness of about 60 nm can be laminated per cycle.
In addition, when a coating film is formed from a multilayer processing material by spin coating, the film thickness can be arbitrarily controlled from several nm to about 200 nm by changing the concentration of the solvent used, the metal compound (W), the spin speed, and the like. can do.
In that case, the laminated body by which the thin film which consists of a different kind of metal oxide (W) was laminated | stacked can also be obtained by changing the kind of metal compound (W) used for every cycle.

  The thickness of the intermediate layer is preferably 10 to 300 nm, more preferably 20 to 250 nm. By setting it within this range, there is an effect that sufficient resistance to etching, preferably dry etching is obtained.

  Next, a resist composition solution is applied onto the intermediate layer formed as described above with a spinner or the like, and prebaked at a temperature of 80 to 300 ° C. for 40 to 120 seconds, preferably 60 to 90 seconds. An upper resist film is formed to obtain a multilayer laminate in which at least three kinds of layers are laminated on the substrate.

{Upper resist film}
As the material for the upper resist film, those generally proposed as a resist material suitable for a method using an exposure process can be used. The resist material may be a chemically amplified resist or a non-chemically amplified resist.
As a method for forming the upper resist film, a conventionally known method can be used.

  The thickness of the upper resist film is preferably 50 to 150 nm, more preferably 50 to 100 nm. By setting the thickness of the upper resist film within this range, there are effects that a resist pattern can be formed with high resolution and sufficient resistance to dry etching can be obtained.

  In the multilayer laminate as described above, the thickness of the upper layer resist film, the intermediate layer and the lower layer organic film is a total from the balance of throughput considering the target aspect ratio and the time required for dry etching of the lower layer organic film, Preferably it is 1 micrometer or less, More preferably, it is 0.7 micrometer or less, Most preferably, it is 0.5 micrometer or less. The total lower limit value is not particularly limited, but is preferably 0.1 μm or more, more preferably 0.15 μm or more.

  The multilayer laminate includes a laminate in which a pattern is formed in the upper resist film, the intermediate layer, and the lower organic film, and a laminate in which no pattern is formed.

<Resist pattern formation process>
Next to the laminated body forming step, the upper resist film of the multilayer laminated body is exposed and subjected to alkali development to form a resist pattern on the upper resist film.
The exposure can be performed by a conventionally known procedure. For example, selective exposure is performed by drawing directly through or without a desired mask pattern. At this time, the exposure through the mask pattern is preferable because of the advantages that the throughput is improved and a resist pattern having a small interval (pitch size) between patterns can be formed.
The exposure light source is not particularly limited, and may be appropriately selected and used according to the resist composition to be used. Specifically, it may be appropriately selected according to the dimension of the pattern to be formed, the type of resist material to be used, and the like, and although it is not possible to limit it generally, it is generally from a deep ultraviolet region of 300 nm or less to several nm. It can be appropriately selected within the range of extreme ultraviolet and X-ray regions.
For example, a KrF excimer laser, an ArF excimer laser, an electron beam, EUV (Extreme Ultraviolet light: wavelength of about 13.5 nm), X-ray, or the like is used. For example, when the above chemically amplified resist is used, KrF excimer laser, ArF excimer laser, F ₂ excimer laser, EUV (extreme ultraviolet), VUV (vacuum ultraviolet), electron beam, X-ray, soft X-ray and the like are preferable. On the other hand, in the case of a non-chemically amplified resist, g-line, i-line, and electron beam may be used.
When a chemically amplified resist is used as the resist material, it is preferable to apply PEB (post-exposure heating) for 40 to 120 seconds, preferably 60 to 90 seconds after the exposure under the temperature condition of 80 to 150 ° C.
Next, the upper resist film is developed using an alkali developer, for example, an aqueous 0.1 to 10% by mass tetramethylammonium hydroxide (TMAH) solution. In this way, a resist pattern (upper layer resist pattern) faithful to the mask pattern can be formed on the upper layer resist film.

<Intermediate layer etching process>
Next, the upper layer resist pattern is used as a mask pattern, and the intermediate layer is dry etched. Thereby, a pattern (intermediate layer pattern) faithful to the upper resist pattern can be formed in the intermediate layer.
Intermediate layer dry etching methods include chemical etching such as downflow etching and chemical dry etching; physical etching such as sputter etching and ion beam etching; and chemical and physical etching such as RIE (reactive ion etching). A known method such as can be used.
The most common dry etching is parallel plate RIE. In this method, first, a multilayer laminate is put into a chamber of an RIE apparatus, and a necessary etching gas is introduced. When a high-frequency voltage is applied to the holder of the multilayer stack placed in parallel with the upper electrode in the chamber, the etching gas is turned into plasma. In the plasma, there are charged particles such as positive and negative ions and electrons, and etching species such as neutral active species. When these etching species are adsorbed on the lower resist layer, a chemical reaction occurs, the reaction product is detached from the surface and exhausted to the outside, and etching proceeds.
As an etching gas used for etching the intermediate layer, a halogen-based gas is preferable because the etching selectivity with respect to the lower organic film is high. That is, the dry etching of the intermediate layer is preferably etching using a halogen-based gas.
Examples of the halogen-based gas include hydrocarbon gases in which some or all of the hydrogen atoms are substituted with halogen atoms such as fluorine atoms and chlorine atoms. Specifically, tetrafluoromethane (CF ₄ ) gas, trifluoro Examples thereof include fluorocarbon gases such as rhomethane (CHF ₃ ) gas, and carbon chloride gases such as tetrachloromethane (CCl ₄ ) gas. Fluorocarbon-based gas is preferable, and CF ₄ gas and / or CHF ₃ gas is particularly preferable.

<Lower layer organic film etching process>
Next, the lower layer organic film is dry etched using the upper layer resist pattern and the intermediate layer pattern as a mask pattern. Thereby, a pattern (lower layer pattern) faithful to the mask pattern can be formed in the lower organic film.
As a method of dry etching of the lower organic film, a known method similar to the above can be used.
Examples of the etching gas used for etching the lower organic film include oxygen gas, sulfur dioxide gas, and halogen-based gas similar to those described above.
In particular, oxygen plasma etching using oxygen gas as an etching gas or etching using CF ₄ gas and / or CHF ₃ gas is preferable. Among these, oxygen plasma etching is preferably used because it can be etched with high resolution by oxygen plasma and is generally used for etching organic films.

By etching the substrate using the lower layer pattern thus obtained as a mask, the pattern can be formed on the substrate.
As the etching method at this time, like the dry etching of the intermediate layer, an etching method using a halogen-based gas can be preferably used, and a fluorocarbon-based gas is particularly preferably used.
The pattern obtained as described above can be used for manufacturing semiconductors, for example.

As described above, according to the multilayer processing material of the present invention, a film having a high etching selectivity with respect to a film formed from an organic material can be formed at a low temperature.
Therefore, the multilayer process material of the present invention can be suitably used in a multilayer process performed using a multilayer laminate in which a plurality of layers including a resist film are laminated on a substrate as described above.
In addition, the multilayer process material of the present invention can be formed by processing at a low temperature and is simpler than the conventional silica-based film, for example, a silica-based film formed by a CVD method or an SOG method. Efficiency can be improved and costs can be reduced.

Hereinafter, the present invention will be described in detail with reference to examples.
[Preparation of multi-layer process materials]
Multi-layer process material 1 was prepared by dissolving tetraisocyanate silane (Si (NCO) ₄ ) in p-menthane to a concentration of 100 mM.

[Example 1]
A lower layer film was formed by spin-coating a lower layer film forming material BLC730 (manufactured by Tokyo Ohka Kogyo Co., Ltd.) on an 8-inch silicon substrate and performing a heat treatment at 250 ° C. for 90 seconds. Furthermore, the multilayer process material 1 was spin-coated on the lower layer film, and heat-treated at 120 ° C. for 60 seconds to form an intermediate film made of SiO ₂ with a film thickness of 30 nm.

[Example 2]
A lower layer film was formed by spin-coating a lower layer film forming material BLC730 (manufactured by Tokyo Ohka Kogyo Co., Ltd.) on an 8-inch silicon substrate and performing a heat treatment at 250 ° C. for 90 seconds. Furthermore, the multilayer process material 1 was spin-coated on the lower layer film, and heat-treated at 150 ° C. for 60 seconds to form an intermediate film made of SiO ₂ with a film thickness of 30 nm.

[Example 3]
A lower layer film was formed by spin-coating a lower layer film forming material BLC730 (manufactured by Tokyo Ohka Kogyo Co., Ltd.) on an 8-inch silicon substrate and performing a heat treatment at 250 ° C. for 90 seconds. Furthermore, the multilayer process material 1 was spin-coated on the lower layer film, and heat-treated at 200 ° C. for 60 seconds to form an intermediate film made of SiO ₂ with a film thickness of 30 nm.

[Comparative Example 1]
A lower layer film was formed by spin-coating a lower layer film forming material BLC730 (manufactured by Tokyo Ohka Kogyo Co., Ltd.) on an 8-inch silicon substrate and performing a heat treatment at 250 ° C. for 90 seconds.

[Comparative Example 2]
A lower layer film was formed by spin-coating a lower layer film forming material BLC730 (manufactured by Tokyo Ohka Kogyo Co., Ltd.) on an 8-inch silicon substrate and performing a heat treatment at 250 ° C. for 90 seconds. Further, an intermediate film forming material HM30 (manufactured by Tokyo Ohka Kogyo Co., Ltd.) was spin-coated on the lower layer film, and heat-treated at 250 ° C. for 90 seconds to form an intermediate film made of SiO _{2 having} a film thickness of 45 nm.

[Comparative Example 3]
A chemically amplified positive resist composition TDUR-P015 (manufactured by Tokyo Ohka Kogyo Co., Ltd.) was spin-coated on an 8-inch silicon substrate, and heat-treated at 90 ° C. for 90 seconds to form a resist film.

The substrates obtained in Examples 1 to 3 and Comparative Examples 1 to 3 were subjected to oxygen plasma etching (40 Pa, 300 W, 20 seconds / 60) using an RIE (reactive ion etching) apparatus RIE-10NR (manufactured by SAMCO). Second), etching (Example 1 and Comparative Example 2) using a fluorine-based gas (CF ₄ / CHF ₃ / He, 300 mm Torr, 300 W, 50 seconds) was performed. Table 1 shows the results of the remaining film amounts (nm) of the intermediate film and the lower layer film after the etching process.

From the above results, it was confirmed that the intermediate films of Examples 1 to 3 have oxygen plasma etching resistance equivalent to that of the conventional hard mask shown in Comparative Example 2 and can be formed at a low temperature. Moreover, etching with a fluorine-based gas was also possible.
Thus, since it has excellent oxygen plasma etching resistance, the intermediate layer has high etching selectivity with respect to the lower layer film and the resist film. Therefore, the intermediate layers of Examples 1 to 3 form a multilayer laminate in which the lower organic film capable of dry etching, the intermediate layer, and the upper resist film are sequentially laminated on the substrate, and the multilayer laminate Further, it was confirmed that the method was useful in a method for forming a pattern by performing a process including dry etching.

Claims (4)

  A lower organic film capable of dry etching, an intermediate layer formed using a multilayer processing material containing a metal compound (W) capable of generating a hydroxyl group by hydrolysis, and an upper resist film are sequentially laminated on the substrate. A pattern forming method, comprising: forming a multilayer laminate, and performing a process including dry etching on the multilayer laminate to form a pattern. Laminate forming step for forming a multilayer laminate in which an intermediate layer formed using a multilayer processing material containing a metal compound (W) capable of generating a hydroxyl group by hydrolysis and an upper resist film are sequentially laminated When,
Exposing the upper resist film and forming a resist pattern on the upper resist film by alkali development; and
Forming a pattern in the intermediate layer by performing dry etching of the intermediate layer using the resist pattern as a mask pattern;
The pattern forming method according to claim 1, wherein a step of forming a pattern on the lower organic film by sequentially performing dry etching of the lower organic film using the resist pattern and the pattern of the intermediate layer as a mask pattern.   The pattern forming method according to claim 2, wherein the dry etching of the intermediate layer is etching using a halogen-based gas. The pattern forming method according to claim 2, wherein the dry etching of the lower organic film is oxygen plasma etching or etching using CF ₄ gas and / or CHF ₃ gas.