JP6865794B2 - Composition for semiconductor resist and pattern formation method using it - Google Patents

Description

The present invention relates to a composition for a semiconductor resist and a pattern forming method using the same.

EUV (extreme ultraviolet) lithography is drawing attention as one of the elemental technologies for manufacturing next-generation semiconductor devices. EUV lithography is a pattern forming technique that uses EUV with a wavelength of 13.5 nm as an exposure light source. According to EUV lithography, it has been demonstrated that extremely fine patterns (for example, 20 nm or less) can be formed in the exposure process of the semiconductor device manufacturing process.

The realization of extreme ultraviolet (EUV) lithography requires the development of compatible photoresists that can be performed at spatial resolutions of 16 nm or less. Currently, traditional chemically amplified photoresists are used for resolution, speed of light, and feature roughness and line edge roughness for next-generation devices. Development is being carried out to satisfy the specifications for (also called roughness or LER)).

Intrinsic image blur caused by acid-catalyzed reactions in polymeric photoresists limits resolution with small feature sizes, which has long been in electron beam (e-beam) lithography. It is a fact that has been informed. Chemically amplified (CA) photoresists have been designed for high sensitivity, but their typical elemental composition reduces the absorbance of the photoresist with light at a wavelength of 13.5 nm, resulting in Due to the reduced sensitivity, it may be more difficult to form finer patterns, partly under EUV exposure.

CA photoresists can also make it difficult to form fine patterns due to roughness problems at small feature sizes. Experiments have confirmed that the line edge roughness (LER) increases as the speed of light decreases, partly due to the nature of the acid-catalyzed process. Due to the shortcomings and problems of CA photoresists, there is a demand for new types of high performance photoresists in the semiconductor industry.

Japanese Patent No. 3990146

An object of the present invention is to provide a composition for a semiconductor resist, which has excellent etching resistance and sensitivity and is easy to handle.

Another object of the present invention is to provide a pattern forming method using the composition for semiconductor resist.

The composition for a semiconductor resist according to one embodiment of the present invention contains an organometallic compound represented by the following chemical formula 1 and a solvent.

In the above chemical formula 1,
R ¹ is a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 20 carbon atoms, a substituted or unsubstituted alkenyl group. Substituted alkynyl groups with 2 to 20 carbon atoms, substituted or unsubstituted alkenylalkyl groups with 3 to 20 carbon atoms, substituted or unsubstituted alkynylalkyl groups with 3 to 20 carbon atoms, substituted or unsubstituted alkynylalkyl groups with 6 to 20 carbon atoms 30 aryl groups, substituted or unsubstituted arylalkyl groups having 7 to 30 carbon atoms, or -R ^c- O-R ^d (where R ^c is a substituted or unsubstituted alkylene group having 1 to 20 carbon atoms. R ^d is a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms).
R ^{2 to} R ⁴ are independently −OR ^a or −OC (= O) R ^b , respectively.
At this time, ^Ra is a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 20 carbon atoms, and the like. A substituted or unsubstituted alkynyl group having 2 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, a substituted or unsubstituted arylalkyl group having 7 to 30 carbon atoms, or a combination thereof.
^Rb is a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 20 carbon atoms, A substituted or unsubstituted alkynyl group having 2 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, a substituted or unsubstituted arylalkyl group having 7 to 30 carbon atoms, or a combination thereof.

The pattern forming method according to another embodiment of the present invention is a step of forming an etching target film on a substrate, and a photoresist film is formed by applying the above-mentioned semiconductor resist composition on the etching target film. The step includes a step of patterning the photoresist film to form a photoresist pattern, and a step of etching the etching target film using the photoresist pattern as an etching mask.

Since the composition for semiconductor resist according to the present invention is relatively excellent in etching resistance and sensitivity and easy to handle, it is excellent in sensitivity and limit resolution, and the pattern is broken even if it has a high aspect ratio. No photoresist pattern can be provided.

It is sectional drawing for demonstrating the pattern forming method using the composition for semiconductor resist by one Embodiment of this invention. It is sectional drawing for demonstrating the pattern forming method using the composition for semiconductor resist by one Embodiment of this invention. It is sectional drawing for demonstrating the pattern forming method using the composition for semiconductor resist by one Embodiment of this invention. It is sectional drawing for demonstrating the pattern forming method using the composition for semiconductor resist by one Embodiment of this invention. It is sectional drawing for demonstrating the pattern forming method using the composition for semiconductor resist by one Embodiment of this invention. An SEM showing a resist wire produced by patterning with a semiconductor resist composition (Example 3) according to an embodiment of the present invention at a 36 nm pitch having a calculated line width roughness (LWR) of 3.4 nm. It is a photograph.

Hereinafter, examples of the present invention will be described in detail with reference to the attached drawings. However, in explaining this description, the description regarding the functions or configurations already known will be omitted for the sake of clarifying the gist of this description.

In order to clarify this description, unnecessary parts are omitted, and the same or similar components are designated by the same reference numerals throughout the specification. Moreover, since the size and thickness of each configuration shown in the drawings are arbitrarily shown for convenience of explanation, this description is not necessarily limited to those shown in the drawings.

The thickness has been enlarged to clearly represent the various layers and regions in the drawings. Then, for convenience of explanation, the thickness of some layers and regions is exaggerated in the drawings. When parts such as layers, membranes, regions, plates, etc. are "above" or "above" other parts, this is not only when they are "directly above" other parts, but also in between. Including the case where there is a part of.

As used herein, the term "substitution" means that the hydrogen atom is a heavy hydrogen, a halogen group, a hydroxy group, an amino group, a substituted or unsubstituted primary to quaternary amino group having 1 to 30 carbon atoms, a nitro group, or a substituent. Alternatively, an unsubstituted silyl group having 1 to 40 carbon atoms, an alkyl group having 1 to 30 carbon atoms, a haloalkyl group having 1 to 10 carbon atoms, an alkylsilyl group having 1 to 10 carbon atoms, and a cycloalkyl group having 3 to 30 carbon atoms. , It means that it was substituted with an aryl group having 6 to 30 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, or a cyano group. "Unsubstituted" means that a hydrogen atom is not substituted with another substituent and remains as a hydrogen atom.

As used herein, the term "alkyl group" means a linear or branched aliphatic hydrocarbon group, unless otherwise defined. The alkyl group can be a "saturated alkyl group" that does not contain any double or triple bonds.

The alkyl group can be an alkyl group having 1 to 20 carbon atoms. More specifically, the alkyl group can be an alkyl group having 1 to 10 carbon atoms or an alkyl group having 1 to 6 carbon atoms. For example, an alkyl group having 1 to 4 carbon atoms means that the alkyl chain contains 1 to 4 carbon atoms, and a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, and the like. The one selected from the group consisting of sec-butyl group and t-butyl group is shown.

Specific examples of the alkyl group include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, t-butyl group, pentyl group, hexyl group, cyclopropyl group, cyclobutyl group and cyclopentyl group. It means a group, a cyclohexyl group, etc.

As used herein, the term "cycloalkyl group" means a monovalent cyclic aliphatic hydrocarbon group unless otherwise defined.

As used herein, the term "aryl group" refers to a substituent in which all the elements of the cyclic substituent have a p-orbital and these p-orbitals form a condensation. Means that it comprises a monocyclic or condensed polycyclic (ie, a ring that shares adjacent pairs of carbon atoms) functional group.

The composition for a semiconductor resist according to one embodiment of the present invention contains an organometallic compound and a solvent.

The organometallic compound is one in which various organic groups are bonded to a metal atom located at the center, and is represented by the following chemical formula 1.

In the above chemical formula 1,
R ¹ is a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 20 carbon atoms, substituted or unsubstituted. Substituted alkynyl groups with 2 to 20 carbon atoms, substituted or unsubstituted alkenylalkyl groups with 3 to 20 carbon atoms, substituted or unsubstituted alkynylalkyl groups with 3 to 20 carbon atoms, substituted or unsubstituted alkynylalkyl groups with 6 to 20 carbon atoms 30 aryl groups, substituted or unsubstituted benzylarylalkyl groups having 7 to 30 carbon atoms, and -R ^c- O-R ^d (where R ^c is a substituted or unsubstituted alkylene having 1 to 20 carbon atoms. It is a group, and R ^d is a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms).
R ^{2 to} R ⁴ are independently −OR ^a or −OC (= O) R ^b , respectively.
At this time, ^Ra is a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 20 carbon atoms, and the like. A substituted or unsubstituted alkynyl group having 2 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, a substituted or unsubstituted arylalkyl group having 7 to 30 carbon atoms, or a combination thereof.
^Rb is a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 20 carbon atoms, A substituted or unsubstituted alkynyl group having 2 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, a substituted or unsubstituted arylalkyl group having 7 to 30 carbon atoms, or a combination thereof.

In one embodiment of the invention, R ¹ can bind to Sn to improve its solubility in organic solvents. In one embodiment of the present invention, R ¹ can generate radicals by dissociating the ^{Sn—R 1} bond during extreme ultraviolet exposure. For example, R ¹ is a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 carbon atoms, a substituted or unsubstituted alkenyl group having 3 to 20 carbon atoms, or a substituted alkenyl group. Alternatively, an unsubstituted or unsubstituted alkynyl group having 3 to 20 carbon atoms, a substituted or unsubstituted alkenylalkyl group having 3 to 20 carbon atoms, a substituted or unsubstituted alkynylalkyl group having 3 to 20 carbon atoms, or a substituted or unsubstituted alkynyl alkyl group. 6 to 30 aryl groups, substituted or unsubstituted arylalkyl groups having 7 to 30 carbon atoms, and -R ^c- O-R ^d (where R ^c is substituted or unsubstituted having 1 to 20 carbon atoms. It is an alkylene group, and R ^d can be selected from substituted or unsubstituted alkyl groups having 1 to 20 carbon atoms).

In one embodiment of the invention, the ^Ra is a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 carbon atoms, a substituted or unsubstituted alkyl group having 2 carbon atoms. Selected from ~ 8 alkenyl groups, substituted or unsubstituted alkynyl groups having 2 to 8 carbon atoms, and substituted or unsubstituted arylalkyl groups having 7 to 30 carbon atoms.
The R ^b is a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 carbon atoms, or an substituted or unsubstituted alkenyl group having 2 to 8 carbon atoms. , A substituted or unsubstituted alkynyl group having 2 to 8 carbon atoms, and a substituted or unsubstituted arylalkyl group having 7 to 30 carbon atoms are selected.

In one embodiment of the present invention, R ^{2 to} R ⁴ impart a metal-oxygen bond to Sn, unlike ^{R 1} described above. In one embodiment of the invention, ^{at least one of R 2 to} R ⁴ can be -OC (= O) R ^b . Specifically, ^{at least two or more of R 2 to} R ⁴ can be −OC (= O) R ^b . More specifically, R ^{2 to} R ⁴ can all be −OC (= O) R ^b . When ^{at least one of R 2 to} R ⁴ contains -OC (= O) R ^b , the pattern formed using the semiconductor resist composition containing the -OC (= O) R b can exhibit excellent sensitivity and limit resolution. ..

However, the present invention is not limited to ^this, or at least one of R 2 to R ⁴ is -OR ^a, may be R 2 to R ⁴ are all -OR ^a.

In one embodiment of the invention, ^Ra and R ^b are independently substituted or unsubstituted alkyl groups having 1 to 10 carbon atoms, substituted or unsubstituted cycloalkyl groups having 3 to 20 carbon atoms, and substituted. Alternatively, select from an unsubstituted alkenyl group having 2 to 8 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 8 carbon atoms, a substituted or unsubstituted arylalkyl group having 7 to 30 carbon atoms, or a combination thereof. it can.

The organometallic compound represented by the above-mentioned chemical formula 1 is an organotin compound, and since tin can strongly absorb extreme ultraviolet rays having a wavelength of 13.5 nm, it has excellent sensitivity to light having high energy. Therefore, the organotin compounds according to one embodiment of the present invention can exhibit superior stability and sensitivity as compared with conventional organic and / or inorganic resists.

On the other hand, in one embodiment of the present invention, the organometallic compound can be at least one of the compounds represented by the following chemical formulas 2 to 4.

In the above chemical formulas 2 to 4,
R ¹ is an independently substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, substituted or unsubstituted cycloalkyl group having 3 to 20 carbon atoms, and substituted or unsubstituted alkenyl having 2 to 20 carbon atoms. Group, substituted or unsubstituted alkynyl group having 2 to 20 carbon atoms, substituted or unsubstituted alkenylalkyl group having 3 to 20 carbon atoms, substituted or unsubstituted alkynylalkyl group having 3 to 20 carbon atoms, substituted or unsubstituted 6 to 30 carbon atoms, substituted or unsubstituted arylalkyl groups having 7 to 30 carbon atoms, and -R ^c- O-R ^d (where R ^c is substituted or unsubstituted carbon number 1). ~ 20 alkylene groups, R ^d is a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms).
R ¹² , R ¹³ , R ¹⁴ and R ³³ are independently substituted or unsubstituted alkyl groups having 1 to 10 carbon atoms, substituted or unsubstituted cycloalkyl groups having 3 to 20 carbon atoms, substituted or unsubstituted. Selected from unsubstituted alkenyl groups having 2 to 8 carbon atoms, substituted or unsubstituted alkynyl groups having 2 to 8 carbon atoms, and substituted or unsubstituted arylalkyl groups having 7 to 30 carbon atoms.
R ²² , R ²³ , R ²⁴ , R ³² , and R ³⁴ are independently hydrogen atoms, substituted or unsubstituted alkyl groups having 1 to 10 carbon atoms, and substituted or unsubstituted alkyl groups having 3 to 20 carbon atoms, respectively. Among cycloalkyl groups, substituted or unsubstituted alkenyl groups having 2 to 8 carbon atoms, substituted or unsubstituted alkynyl groups having 2 to 8 carbon atoms, and substituted or unsubstituted arylalkyl groups having 7 to 30 carbon atoms. Be selected.

Specifically, the R ¹ is a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 carbon atoms, or a substituted or unsubstituted alkenyl having 3 to 20 carbon atoms. Alkyl groups, substituted or unsubstituted alkynyl alkyl groups having 3 to 20 carbon atoms, and -R ^c- O-R ^d (where R ^c is a substituted or unsubstituted alkylene group having 1 to 20 carbon atoms. , R ^d can be any one selected from substituted or unsubstituted alkyl groups having 1 to 20 carbon atoms).

Specifically, the organometallic compound according to one embodiment can be at least one of the compounds represented by the following chemical formulas 5 to 13.

In the case of a commonly used organic resist, the etching resistance may be insufficient and the pattern with a high aspect ratio may be broken.

Further, in the case of a conventional inorganic resist (for example, a metal oxide compound), since a mixture of sulfuric acid and hydrogen peroxide having high corrosiveness is used, it is difficult to handle and the storage stability is poor, and the performance of the mixture is improved. It is relatively difficult to change the configuration, and a high-concentration developer must be used.

On the other hand, the composition for a semiconductor resist according to one embodiment of the present invention has a structure in which an organometallic compound has various organic groups bonded to a central metal atom as described above. As a result, it has relatively excellent etching resistance and sensitivity as compared with existing organic and / or inorganic resists, and is easy to handle.

Specifically, in the organometallic compound represented by the chemical formula 1, in addition to the metal-oxygen bond to the central metal element, ^{an aliphatic hydrocarbon group such as R 1} or a functional group such as -alkyl-O-alkyl when is coupled, improved solubility in solvents, extreme ultraviolet Sn-R ¹ bonds when exposed at is dissociated, it is possible to generate a radical. Thereby, the semiconductor resist composition of the present invention can be used to form a pattern having excellent sensitivity and limit resolution.

Further, the pattern formed by using the composition for semiconductor resist according to the embodiment of the present invention does not easily collapse even if it has a high aspect ratio.

In the semiconductor resist composition according to the embodiment of the present invention, the organometallic compound represented by the chemical formula 1 is contained in a content of 0.01% by mass to 10% by mass based on the total mass of the composition. Is preferable. When it is contained in such a content, it is excellent in storage stability and easy to form a thin film.

As the organometallic compound, a commercially available product or a synthetic product may be used. As the synthesis method, a conventionally known method can be appropriately adopted.

The composition for a semiconductor resist according to one embodiment of the present invention preferably contains the above-mentioned organometallic compound and a solvent.

The solvent contained in the semiconductor resist composition according to the embodiment of the present invention may be an organic solvent. Examples include aromatic compounds (eg, xylene, toluene, etc.), alcohols (eg, 4-methyl-2-pentanol, 4-methyl-2-propanol, 1-butanol, methanol, isopropyl alcohol). , 1-propanol, etc.), ethers (eg, anisole, tetrahydrofuran, etc.), esters (n-butyl acetate, propylene glycol monomethyl ether acetate, ethyl acetate, ethyl lactate, etc.), ketones (eg, methyl ethyl ketone, 2-heptanone, etc.) Etc.), or a mixture thereof, etc., but is not limited to these.

The semiconductor resist composition according to one embodiment of the present invention may further contain a resin in addition to the organometallic compound and the solvent.

Such a resin may be a phenolic resin containing at least one aromatic moiety shown in Group 1 below.

The resin can have a weight average molecular weight of 500 to 20,000.

The resin may be contained in an amount of 0.1% by mass to 50% by mass with respect to the total mass of the composition for semiconductor resist.

When the content of the resin is in the above range, it can have excellent etching resistance and heat resistance.

The composition for a semiconductor resist according to one embodiment of the present invention preferably comprises the above-mentioned organometallic compound, solvent, and resin. However, the composition for semiconductor resist according to the above-described embodiment may further contain additives in some cases. Examples of the additive include a surfactant, a cross-linking agent, a leveling agent, or a combination thereof.

As the surfactant, for example, alkylbenzene sulfonate, alkylpyridinium salt, polyethylene glycol, quaternary ammonium salt, or a combination thereof can be used, but the surfactant is not limited thereto.

Examples of the cross-linking agent include, but are not limited to, a melamine-based cross-linking agent, a substituted urea-based cross-linking agent, and a polymer-based cross-linking agent. Cross-linking agents having at least two cross-linking substituents include, for example, methoxymethylated glycol uryl, butoxymethylated glycol uryl, methoxymethylated melamine, butoxymethylated melamine, methoxymethylated benzoguanamine, butoxymethylated benzoguanamine, methoxymethylated. Compounds such as urea, butoxymethylated urea, or methoxymethylated thiourea can be used.

The leveling agent is for improving the flatness of the coating film at the time of printing (coating), and a known leveling agent available by a commercially available method can be used.

The amount of these additives used can be easily adjusted according to desired physical properties and can be appropriately set.

Further, the composition for semiconductor resist of the present invention is a silane cup as an adhesive strength improving agent for improving the adhesive strength with the substrate (for example, for improving the adhesive strength of the composition for semiconductor resist with the substrate). The ring agent can be further used as an additive. Examples of the silane coupling agent include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltrichlorosilane, vinyltris (β-methoxyethoxy) silane; 3-methacryloxypropyltrimethoxysilane, and 3-acrylicoxypropyltrimethoxysilane. , P-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane and other carbon-carbon unsaturated bond-containing silane compounds; trimethoxy [3- (phenylamino) propyl] silane, etc. Can be used, but is not limited to these.

Even if a pattern having a high aspect ratio is formed, the composition for a semiconductor resist of the present invention does not cause pattern collapse or can greatly reduce the risk of pattern collapse. Therefore, for example, a fine pattern having a line width of 5 nm to 100 nm, for example, a fine pattern having a line width of 5 nm to 80 nm, for example, a fine pattern having a line width of 5 nm to 70 nm, for example, a line width of 5 nm to 50 nm. To form a fine pattern having, for example, a fine pattern having a line width of 5 nm to 40 nm, for example, a fine pattern having a line width of 5 nm to 30 nm, for example, a fine pattern having a line width of 5 nm to 20 nm, a wavelength of 5 nm. A photoresist step using light from ~ 150 nm, eg, a photoresist step using light from 5 nm to 100 nm, eg, a photoresist step using light from 5 nm to 80 nm, eg, a photo using light from 5 nm to 50 nm. The composition of the present invention can be used in a resisting step, for example, a photoresist step using light having a wavelength of 5 nm to 30 nm, for example, a photoresist step using light having a wavelength of 5 nm to 20 nm. Therefore, by using the composition for semiconductor resist according to one embodiment of the present invention, extreme ultraviolet lithography using an EUV light source having a wavelength of 13.5 nm can be realized.

According to another embodiment of the present invention, there is provided a method of forming a pattern using the above-mentioned composition for semiconductor resist. As an example, the manufactured pattern can be a photoresist pattern.

The pattern forming method according to one embodiment of the present invention includes a step of forming an etching target film on a substrate, a step of applying the above-mentioned semiconductor resist composition on the etching target film to form a photoresist film, and the above. It includes a step of patterning a photoresist film to form a photoresist pattern, and a step of etching the etching target film using the photoresist pattern as an etching mask.

Hereinafter, a method of forming a pattern using the above-mentioned composition for semiconductor resist will be described with reference to FIGS. 1 to 5. 1 to 5 are schematic cross-sectional views for explaining a pattern forming method using the composition for semiconductor resist according to the present invention.

Referring to FIG. 1, first, an object to be etched is prepared. An example of the object to be etched may be a thin film 102 formed on the semiconductor substrate 100. Hereinafter, the description will be limited to the case where the object to be etched is the thin film 102, but the present invention is not limited to the present embodiment. The surface of the thin film 102 is cleaned in order to remove contaminants and the like remaining on the thin film 102. The thin film 102 can be, for example, a silicon nitride film, a polysilicon film, or a silicon oxide film.

Next, a composition for forming a resist underlayer film 104 for forming a resist underlayer film 104 on the surface of the washed thin film 102 is coated by applying a spin coating method. However, the form of the present invention is not limited to this, and various known coating methods such as spray coating method, dip coating method, knife edge coating method, printing method, such as inkjet printing method and screen printing method can be used. It can also be used.

The step of coating the resist underlayer film forming composition may be omitted. The case of forming the resist underlayer film will be described below.

After coating, a drying and baking step is performed to form a resist underlayer film 104 on the thin film 102. The baking process can be carried out at a temperature of, for example, 100 to 500 ° C., for example, 100 ° C. to 300 ° C.

The resist underlayer film 104 is formed between the substrate 100 and the photoresist film 106, and the irradiation line reflected from the interface between the substrate 100 and the photoresist film 106 or the interlayer hard mask (hardmask) is an unintended photo. When scattered in the resist region, it is possible to prevent the photoresist line width (linewise) from interfering with non-uniformity and pattern forming property.

Referring to FIG. 2, the resist underlayer film 104 is coated with the above-mentioned semiconductor resist composition to form a photoresist film 106. The photoresist film 106 may be in the form of a thin film 102 formed on the substrate 100, coated with the above-mentioned composition for semiconductor resist, and then cured by a heat treatment step.

More specifically, at the stage of forming a pattern using the composition for semiconductor resist, the above-mentioned composition for semiconductor resist is applied onto the substrate 100 on which the thin film 102 is formed by a spin coating method, a slit coating method, or an inkjet. A step of applying by printing or the like and a step of drying the applied composition for a semiconductor resist to form a photoresist film 106 can be included.

Since the composition for semiconductor resist has already been described in detail, a duplicate description will be omitted.

Next, a first baking step is performed in which the substrate 100 on which the photoresist film 106 is formed is heated. The first baking step can be performed at a temperature of 80 ° C. to 120 ° C.

With reference to FIG. 3, the photoresist film 106 is selectively exposed.

As an example, examples of light that can be used in the exposure process include only light having a short wavelength such as i-line (wavelength 365 nm), KrF excimer laser (wavelength 248 nm), and ArF excimer laser (wavelength 193 nm). However, light having a high energy wavelength such as extreme ultraviolet (EUV, Extreme UltraViolet; wavelength 13.5 nm) and E-Beam (electron beam) can also be exemplified.

More specifically, the light for exposure according to one embodiment of the present invention may be short wavelength light having a wavelength in the range of 5 nm to 150 nm, such as extreme ultraviolet light (wavelength 13.5 nm), E-Beam (electron beam), and the like. Can be light having a high energy wavelength of.

The exposed region 106a in the photoresist film 106 has a solubility different from that of the unexposed region 106b of the photoresist film 106 by forming a polymer by a cross-linking reaction such as condensation between organometallic compounds.

Next, the substrate 100 is subjected to a second baking step. The second baking step can be performed at a temperature of 90 ° C to 200 ° C. By performing the second baking step, the exposed region 106a of the photoresist film 106 is in a state in which dissolution in the developing solution is unlikely to occur.

FIG. 4 shows a photoresist pattern 108 formed by dissolving and removing the photoresist film 106b corresponding to the unexposed region using a developing solution. Specifically, the photoresist pattern 108 corresponding to the negative tone image is completed by dissolving and then removing the photoresist film 106b corresponding to the unexposed region using an organic solvent such as 2-heptanone. To.

As described above, the developer used in the pattern forming method according to the embodiment of the present invention can be an organic solvent. Examples of the organic solvent used in the pattern forming method according to the embodiment of the present invention include ketones such as methyl ethyl ketone, acetone, cyclohexanone and 2-heptanone, 4-methyl-2-propanol, 1-butanol, isopropanol, 1 -Alcohols such as propanol and methanol, esters such as propylene glycol monomethyl ester acetate, ethyl acetate, ethyl lactate, n-butyl acetate and butyrolactone, aromatic compounds such as benzene, xylene and toluene, or combinations thereof. Be done.

However, the photoresist pattern according to one embodiment of the present invention is not necessarily limited to being formed as a negative tone image, and may be formed so as to have a positive tone image. In this case, examples of the developer that can be used for forming a positive tone image include tetraethylammonium hydroxide, tetrapropylammonium hydroxide, quaternary ammonium hydroxide such as tetrabutylammonium hydroxide or a combination thereof.

As described above, not only light having wavelengths such as i-line (wavelength 365 nm), KrF excimer laser (wavelength 248 nm), ArF excimer laser (wavelength 193 nm), but also extreme ultraviolet (EUV, Extreme UltraViolet; wavelength 13.5 nm). The photoresist pattern 108 formed by exposure to light having high energy such as E-Beam (electron beam) can have a line width of 5 nm to 100 nm. As an example, the photoresist pattern 108 can be formed with a line width of 5 nm to 90 nm, 5 nm to 80 nm, 5 nm to 70 nm, 5 nm to 60 nm, 10 nm to 50 nm, 10 nm to 40 nm, 10 nm to 30 nm, and 10 nm to 20 nm.

The photoresist pattern 108 can have a half pitch of 50 nm or less, for example 40 nm or less, for example 30 nm or less, for example 25 nm or less, and a pitch having a line width roughness of 10 nm or less and 5 nm or less.

Next, the photoresist pattern 108 is used as an etching mask to etch the resist underlayer film 104. The organic film pattern 112 is formed by the etching step as described above, and the formed organic film pattern 112 can also have a width corresponding to the photoresist pattern 108.

Referring to FIG. 5, the photoresist pattern 108 is applied as an etching mask to etch the exposed thin film 102. As a result, the thin film is formed as a thin film pattern 114.

The etching of the thin film 102 can be performed by, for example, dry etching using an etching gas, and as the etching gas, for example, CHF ₃ , CF ₄ , Cl ₂ , BCl _3, or a mixed gas thereof or the like can be used.

The thin film pattern 114 formed using the photoresist pattern 108 formed by the exposure process performed using the EUV light source can have a width corresponding to the photoresist pattern 108. As an example, it can have a line width of 5 nm to 100 nm, similar to the photoresist pattern 108. For example, the thin film pattern 114 formed by the exposure step performed using the EUV light source has 5 nm to 90 nm, 5 nm to 80 nm, 5 nm to 70 nm, 5 nm to 60 nm, and 10 nm to 50 nm, similarly to the photoresist pattern 108. It can have a line width of 10 nm to 40 nm, 10 nm to 30 nm, 10 nm to 20 nm, and more specifically, it can be formed with a line width of 20 nm or less.

Hereinafter, the present invention will be described in more detail through examples relating to the synthesis of an organometallic compound and the production of a composition for a semiconductor resist containing the same. However, the following examples do not technically limit the present invention.

(Synthesis Example 1)
After gradually adding 25 ml of acetic acid to the compound represented by the following chemical formula A-1 (10 g, 25.6 mmol) at room temperature, the mixture was heated under reflux at 110 ° C. for 24 hours.

Then, after lowering the temperature to room temperature, acetic acid was vacuum distilled to obtain a compound represented by the following chemical formula 5 (yield: 90%).

(Synthesis Example 2)
After gradually adding 25 ml of acrylic acid to the compound represented by the following chemical formula A-2 (10 g, 25.4 mmol) at room temperature, the mixture was heated under reflux at 80 ° C. for 6 hours.

Then, after lowering the temperature to room temperature, acrylic acid was vacuum-distilled to obtain a compound represented by the following chemical formula 6 (yield: 50%).

(Synthesis Example 3)
25 ml of propionic acid was gradually added dropwise to the compound represented by the following chemical formula A-3 (10 g, 23.7 mmol) at room temperature, and then heated under reflux at 110 ° C. for 24 hours.

Then, after lowering the temperature to room temperature, acrylic acid was vacuum distilled to obtain a compound represented by the following chemical formula 7 (yield: 95%).

(Synthesis Example 4)
To the compound represented by the chemical formula A-2 of Synthesis Example 2, 25 ml of isobutyl acid was gradually added dropwise at room temperature, and then the mixture was heated under reflux at 110 ° C. for 24 hours.

Then, after lowering the temperature to room temperature, isobutyl acid was vacuum-distilled to obtain a compound represented by the following chemical formula 8 (yield: 95%).

(Synthesis Example 5)
25 ml of propionic acid was gradually added dropwise to the compound represented by the following chemical formula A-4 (10 g, 24.6 mmol) at room temperature, and then heated under reflux at 110 ° C. for 24 hours.

Then, after lowering the temperature to room temperature, acrylic acid was vacuum distilled to obtain a compound represented by the following chemical formula 9 (yield: 90%).

(Synthesis Example 6)
The compound represented by the above chemical formula A-1 (10 g, 24.6 mmol) is _{dissolved in 50 mL of CH 2} Cl ₂ , and a 4M HCl diethyl ether solution (3 equivalents, 36.9 mmol) is gradually added at −78 ° C. for 30 minutes. Dropped. Then, the mixture was stirred at room temperature for 12 hours, and the solvent was concentrated to obtain a compound represented by the following chemical formula A-5 (yield: 80%).

The compound represented by the chemical formula A-5 (10 g, 35.4 mmol) was dissolved in 30 ml of anhydrous pentane, and the temperature was lowered to 0 ° C. Then, diethylamine (7.8 g, 106.3 mmol) was gradually added dropwise, t-BuOH (7.9 g, 106.3 mmol) was added, and the mixture was stirred at room temperature for 1 hour. After completion of the reaction, the mixture was filtered and concentrated, and then vacuum dried to obtain a compound represented by the following chemical formula 10 (yield: 60%).

(Synthesis Example 7)
The same applies except that the compound represented by the above-mentioned chemical formula A-2 is used in place of the above-mentioned compound represented by the chemical formula A-1 in the step of synthesizing the compound represented by the above-mentioned chemical formula A-5. A compound represented by the following chemical formula A-6 was obtained by the above method (yield: 75%).

The compound represented by the chemical formula A-6 (10 g, 37.3 mmol) was dissolved in anhydrous pentane, and the temperature was lowered to 0 ° C. Then, diethylamine (8.2 g, 111.9 mmol) was gradually added dropwise, then isopropanol (6.7 g, 111.9 mmol) was added, and the mixture was stirred at room temperature for 1 hour. After completion of the reaction, the mixture was filtered, concentrated, and vacuum dried to obtain a compound represented by the following chemical formula 11 (yield: 65%).

(Synthesis Example 8)
The same applies except that the compound represented by the above-mentioned chemical formula A-3 is used in place of the above-mentioned compound represented by the chemical formula A-1 in the step of synthesizing the compound represented by the above-mentioned chemical formula A-5. A compound represented by the following chemical formula A-7 was obtained by the above method (yield: 70%).

The compound represented by the chemical formula A-7 (10 g, 18.7 mmol) was dissolved in anhydrous pentane, and the temperature was lowered to 0 ° C. Then, diethylamine (7.4 g, 101.3 mmol) was gradually added dropwise, ethanol (6.1 g, 101.3 mmol) was added, and the mixture was stirred at room temperature for 1 hour. After completion of the reaction, the mixture was filtered, concentrated, and vacuum dried to obtain a compound represented by the following chemical formula 12 (yield: 60%).

(Synthesis Example 9)
After gradually adding 25 ml of formic acid to the compound represented by the following chemical formula A-2 (10 g, 25.4 mmol) at room temperature, the mixture was heated under reflux at 100 ° C. for 24 hours.

Then, after lowering the temperature to room temperature, acrylic acid was vacuum distilled to obtain a compound represented by the following chemical formula 13 (yield: 90%).

(Comparative synthesis example)
Dibutyltin dichloride (10 g, 33 mmol) was dissolved in 30 mL of ether, 70 mL of 1 M aqueous sodium hydroxide (NaOH) solution was added, and the mixture was stirred for 1 hour. After stirring, the produced solid is filtered, washed three times with 25 mL of deionized water, and then dried under reduced pressure at 100 ° C. to obtain an organometallic compound having a weight average molecular weight of 1,500 represented by the following chemical formula 14. It was.

(Examples 1 to 9)
The organometallic compounds synthesized in Synthesis Examples 1 to 9 are each dissolved in xylene at a concentration of 2% by mass, and then filtered through a 0.1 μm PTFE syringe filter to form the composition for semiconductor resist of Examples 1 to 9. Manufactured.

A 4-inch circular silicon wafer having a natural oxide film surface was prepared as a substrate for thin film film deposition, and the substrate was pretreated under a UV ozone cleaning system for 10 minutes. Then, the resist composition for semiconductors according to Examples 1 to 9 was spin-coated on the pretreated substrate at 1500 rpm for 30 seconds. On the hot plate, the substrate was fired at 100 ° C. for 120 seconds (baking after coating, post-apply bucket, PAB) to form a thin film.

After coating and baking, the thickness of the thin film measured by an ellipsometer was about 40 nm.

(Comparison example)
The compound represented by the above chemical formula 14 synthesized in the comparative synthesis example is dissolved in 4-methyl-2-pentanol at a concentration of 1% by mass, and then a 0.1 μm PTFE syringe filter is used. A composition for a semiconductor resist was produced by filtering with.

Then, a thin film was formed on the substrate of the manufactured composition for semiconductor resist according to the comparative example through the same steps as in the above-mentioned Examples.

After coating and baking, the thickness of the thin film measured by an ellipsometer was about 40 nm.

(Evaluation 1)
A linear array of 50 circular pads with a diameter of 500 μm was projected onto wafers coated with resists from Examples 1-9 and Comparative Examples using EUV light (Lawence Berkeley National Laboratory Micro Exposure Tool, MET). The pad exposure time was adjusted so that the EUV increased dose was applied to each pad.

Then, the resist and the substrate were subjected to post-exposure bake (PEB) after exposure at 150 ° C. for 120 seconds on a hot plate. The fired thin film was immersed in a developing solution (2-heptanone) for 30 seconds each, and then washed with the same developer for an additional 10 seconds to form a negative tone image, and the unexposed coated portion was removed. Finally, the process was completed by firing on a hot plate at 150 ° C. for 2 minutes.

An ellipsometer was used to measure the residual resist thickness of the exposed pad. The remaining thickness for each exposure amount was measured and graphed as a function for the exposure amount, and Dg (energy level at which development was completed) was shown in Table 1 below for each type of resist.

On the other hand, the solubility and storage stability of the resist compositions for semiconductors according to Examples 1 to 9 and Comparative Examples described above were evaluated by the following methods, and both are shown in Table 1 below. ..

[solubility]
The solubility of the compounds represented by the chemical formulas 5 to 13 of Synthesis Examples 1 to 9 and the compounds represented by the chemical formula 14 of the comparative synthesis example when dissolved in xylene was evaluated in the following three stages:
◯: Dissolves in xylene in an amount of 3% by mass or more Δ: Dissolves in xylene in an amount of 1% by mass or more and less than 3% by mass ×: Dissolves in xylene in an amount of less than 1% by mass.

[Storage stability]
When left at room temperature (0 ° C. to 30 ° C.) for a predetermined period of time, the degree of precipitation was observed with the naked eye, a standard was set for storage, and evaluation was made in the following three stages.

○: Can be stored for 1 month or more △: Can be stored for 1 week or more and less than 1 month ×: Can be stored for less than 1 week

As is clear from the results in Table 1 above, the resist compositions for semiconductors according to Examples 1 to 9 showed excellent solubility and storage stability as compared with Comparative Examples, and the patterns formed using them were also compared. It can be confirmed that the sensitivity is superior to that of the example. On the other hand, since the semiconductor resist composition according to the comparative example has poor solubility in the xylene solvent, it was confirmed that it is practically difficult to evaluate the storage stability of the composition and the pattern formation using the composition. ..

Evaluation 2
The resist-coated substrates of Examples 1-9 and Comparative Examples were exposed to extreme ultraviolet light (Lawence Berkeley National Laboratory Micro Exposure Tool). A 36 nm pitch 18 nm line pattern is projected onto the wafer using radiation at a wavelength of 13.5 nm, dipole illumination, a numerical aperture of 0.3, and ^{an imaging dose of 67 mJ / cm 2.} did. The patterned resist and substrate were then exposed on a hot plate at 180 ° C. for 2 minutes and then fired (PEB). The exposed thin film was then immersed in 2-heptanone for 30 seconds and additionally washed with the same developer for 15 seconds to form a negative tone image and remove the unexposed coated portion. After development, the product was finally fired on a hot plate at 150 ° C. for 5 minutes. FIG. 6 is an SEM photograph of a resist wire generated by patterning a substrate coated with the resist of Example 3 at a pitch of 36 nm having a calculated line width roughness (LWR) of 3.4 nm.

With reference to FIG. 6, it can be confirmed that the photoresist pattern satisfying the target line width and the line and space (L / S) is well formed without the pattern collapsing.

Although specific examples of the present invention have been described and illustrated above, the present invention is not limited to the described examples, and various modifications and modifications are made without departing from the ideas and scope of the present invention. What can be done is self-evident to those with ordinary knowledge in the field of this technology. Therefore, such modifications or modifications must not be individually understood from the technical idea or point of view of the invention, and the modified examples are said to belong to the claims of the invention. Will have to.

100 boards,
102 thin film,
104 Resist Underlayer Membrane,
106 photoresist film,
106a exposure area,
106b unexposed area,
108 photoresist pattern,
112 Organic Membrane Pattern,
114 thin film pattern.

Claims (15)

A composition for a semiconductor resist containing an organometallic compound represented by the following chemical formula 1 and a solvent:

In the above chemical formula 1,
R ¹ is a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 20 carbon atoms, a substituted or unsubstituted alkenyl group. Substituted alkynyl groups with 2 to 20 carbon atoms, substituted or unsubstituted alkenylalkyl groups with 3 to 20 carbon atoms, substituted or unsubstituted alkynylalkyl groups with 3 to 20 carbon atoms, substituted or unsubstituted alkynylalkyl groups with 6 to 20 carbon atoms 30 aryl groups, substituted or unsubstituted arylalkyl groups having 7 to 30 carbon atoms, and -R ^c- O-R ^d (where R ^c is a substituted or unsubstituted alkylene group having 1 to 20 carbon atoms. And R ^d is a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms).
R ^{2 to} R ⁴ are independently -OR ^a or -OC (= O) R ^b , and at least one of R ^{2 to} R ⁴ is -OC (= O) R ^b. And
At this time, ^Ra is a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 20 carbon atoms, and the like. A substituted or unsubstituted alkynyl group having 2 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, a substituted or unsubstituted arylalkyl group having 7 to 30 carbon atoms, or a combination thereof.
^Rb is a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 20 carbon atoms, A substituted or unsubstituted alkynyl group having 2 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, a substituted or unsubstituted arylalkyl group having 7 to 30 carbon atoms, or a combination thereof. The R ¹ is a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 carbon atoms, a substituted or unsubstituted alkenyl alkyl group having 3 to 20 carbon atoms, or a substituted alkyl group. Alternatively, an unsubstituted alkynyl alkyl group having 3 to 20 carbon atoms and an —R ^c −O—R ^d (where R ^c is a substituted or unsubstituted alkylene group having 1 to 20 carbon atoms, and R ^d is The composition for semiconductor resist according to claim 1, which is selected from (alkyl groups having 1 to 20 carbon atoms which are substituted or unsubstituted). The ^Ra is a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 8 carbon atoms, a substituted or substituted alkenyl group. Selected from unsubstituted alkynyl groups having 2 to 8 carbon atoms and substituted or unsubstituted arylalkyl groups having 7 to 30 carbon atoms.
The R ^b is a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 carbon atoms, or an substituted or unsubstituted alkenyl group having 2 to 8 carbon atoms. The composition for semiconductor resist according to claim 1 or 2, which is selected from a substituted or unsubstituted alkynyl group having 2 to 8 carbon atoms and a substituted or unsubstituted arylalkyl group having 7 to 30 carbon atoms. .. The composition for a semiconductor resist according to any one of claims 1 to 3 , wherein the organometallic compound is at least one of the compounds represented by the following chemical formulas 3 to 4.

In the above chemical formulas 3 to 4,
R ¹ is a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 20 carbon atoms, a substituted or unsubstituted alkenyl group. Substituted alkynyl groups with 2 to 20 carbon atoms, substituted or unsubstituted alkenylalkyl groups with 3 to 20 carbon atoms, substituted or unsubstituted alkynylalkyl groups with 3 to 20 carbon atoms, substituted or unsubstituted alkynylalkyl groups with 6 to 20 carbon atoms 30 aryl groups, substituted or unsubstituted arylalkyl groups having 7 to 30 carbon atoms, and -R ^c- O-R ^d (where R ^c is a substituted or unsubstituted alkylene group having 1 to 20 carbon atoms. And R ^d is a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms).
R ³³ is a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 8 carbon atoms, substituted or unsubstituted. It is selected from a substituted alkynyl group having 2 to 8 carbon atoms and a substituted or unsubstituted arylalkyl group having 7 to 30 carbon atoms.
R ²² , R ²³ , R ²⁴ , R ³² , and R ³⁴ are independently hydrogen atoms, substituted or unsubstituted alkyl groups having 1 to 10 carbon atoms, and substituted or unsubstituted alkyl groups having 3 to 20 carbon atoms, respectively. Among cycloalkyl groups, substituted or unsubstituted alkenyl groups having 2 to 8 carbon atoms, substituted or unsubstituted alkynyl groups having 2 to 8 carbon atoms, and substituted or unsubstituted arylalkyl groups having 7 to 30 carbon atoms. Be selected. The R ¹ has independently substituted or unsubstituted alkyl groups having 1 to 10 carbon atoms, substituted or unsubstituted cycloalkyl groups having 3 to 20 carbon atoms, and substituted or unsubstituted alkyl groups having 3 to 20 carbon atoms. Alkylalkyl groups, substituted or unsubstituted alkynylalkyl groups having 3 to 20 carbon atoms, and -R ^c- O-R ^d (where R ^c is a substituted or unsubstituted alkylene group having 1 to 20 carbon atoms. The composition for semiconductor resist according to claim 4 , wherein R ^d is a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms. The composition for semiconductor resist according to any one of claims 1 to 5 , wherein the composition for semiconductor resist further contains an additive of a surfactant, a cross-linking agent, a leveling agent, or a combination thereof. The composition for semiconductor resist according to claim 6 , wherein the surfactant contains an alkylbenzene sulfonate, an alkylpyridinium salt, polyethylene glycol, a quaternary ammonium salt, or a combination thereof. The composition for a semiconductor resist according to claim 6 or 7 , wherein the cross-linking agent contains a melamine-based cross-linking agent, a substituted urea-based cross-linking agent, a polymer-based cross-linking agent, or a combination thereof. The composition for a semiconductor resist according to any one of claims 6 to 8 , wherein the additive further contains a silane coupling agent. The composition for a semiconductor resist according to any one of claims 1 to 9 , wherein the organometallic compound is at least one of the compounds represented by the following chemical formulas 5 to 9 and chemical formula 13.

A step of applying the composition for semiconductor resist according to any one of claims 1 to 10 onto a film to be etched to form a photoresist film;
A pattern forming method comprising a step of patterning the photoresist film to form a photoresist pattern; and a step of etching the etching target film using the photoresist pattern as an etching mask. The pattern forming method according to claim 11 , wherein the step of forming the photoresist pattern includes using light having a wavelength of 5 nm to 150 nm. The pattern forming method according to claim 11 or 12 , further comprising the step of forming the etching target film on the substrate. The pattern forming method according to any one of claims 11 to 13, further comprising a step of forming a resist underlayer film between the substrate and the photoresist film. The pattern forming method according to any one of claims 11 to 14 , wherein the photoresist pattern has a line width of 5 nm to 100 nm.

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