KR20220062987A - Resist underlayer composition, and method of forming patterns using the composition - Google Patents

Abstract

The present invention relates to: a resist underlayer composition comprising a copolymer comprising a structural unit represented by chemical formula 1 below and a structural unit represented by chemical formula 2 and a solvent; and a pattern forming method using the resist underlayer composition. The resist underlayer composition can improve patterning performance and patterning efficiency and the definition of chemical formula 1 and chemical formula 2 is the same as described in the specification.

Description

Composition for resist underlayer and pattern formation method using same

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

Recently, the semiconductor industry is developing from a pattern of several hundreds of nanometers to an ultra-fine technology having a pattern of several to tens of nanometers. An effective lithographic technique is essential to realize such ultra-fine technology.

The lithographic technique is to form a thin film by coating a photoresist film on a semiconductor substrate such as a silicon wafer, and irradiate activating radiation such as ultraviolet rays through a mask pattern on which the device pattern is drawn, and then develop the obtained photoresist pattern. It is a processing method of forming a fine pattern corresponding to the pattern on the surface of the substrate by etching the substrate using the protective film.

The exposure process performed in the photoresist pattern formation step is one of the important factors for obtaining a high-resolution photoresist image.

As ultra-fine pattern manufacturing technology is required, short wavelengths such as i-line (wavelength 365 nm), KrF excimer laser (wavelength 248 nm), and ArF excimer laser (wavelength 193 nm) are used as activating radiation used for photoresist exposure. . Accordingly, in order to solve problems caused by diffuse reflection or standing waves from the semiconductor substrate of the activating radiation, many studies have been made to solve the problem by interposing a resist underlayer having an optimized reflectance between the resist and the semiconductor substrate. there is.

Meanwhile, in addition to the activating radiation, a method of using high energy rays such as EUV (extreme ultraviolet; wavelength 13.5 nm) and E-Beam (electron beam) as a light source for manufacturing a fine pattern has also been made, and in the case of the light source, reflection from the substrate However, the thickness of the resist underlayer has to be further reduced according to pattern refinement, and studies to improve the adhesion between the resist and the lower layer are being widely reviewed to improve the pattern collapse phenomenon. In addition, in order to maximize the efficiency of the light source, research on improving the sensitivity through the lower layer is being studied.

The pattern collapse of the resist does not occur even in the fine patterning process, and it is formed into an ultra-thin film, so the etching process time can be shortened, and the patterning performance and efficiency can be improved by improving the sensitivity and light absorption efficiency to the exposure light source. do.

Another embodiment provides a pattern forming method using the composition for a resist underlayer film.

One embodiment, a copolymer comprising a structural unit represented by the following formula (1), and a structural unit represented by the formula (2); And it provides a resist underlayer composition comprising a solvent.

[Formula 1]

In Formula 1,

A is a nitrogen-containing heterocyclic group,

R ¹ and R ² are each independently a vinyl group, an allyl group, a substituted or unsubstituted C1 to C10 alkyl group, a substituted or unsubstituted C2 to C10 alkenyl group, a substituted or unsubstituted C2 to C10 alkynyl group, substituted or an unsubstituted C1 to C10 heteroalkyl group, a substituted or unsubstituted C1 to C10 heteroalkenyl group, a substituted or unsubstituted C1 to C10 heteroalkynyl group, a substituted or unsubstituted C3 to C20 cycloalkyl group, a substituted or unsubstituted a C2 to C20 heterocycloalkyl group, a substituted or unsubstituted C6 to C20 aryl group, or a substituted or unsubstituted C1 to C20 heteroaryl group;

* is the point of connection with the backbone or end group of the polymer;

[Formula 2]

In Formula 2,

L is a single bond, a substituted or unsubstituted C1 to C10 alkylene group, or a substituted or unsubstituted C1 to C10 heteroalkylene group,

R ^a is hydrogen or a C1 to C5 alkyl group,

R ^k is a hydrophilic moiety,

* is a point connected to the main chain or end group of the polymer.

A in Formula 1 may be represented by at least one of Formula A-1 or Formula A-2.

[Formula A-1]

[Formula A-2]

In Formula A-1 and Formula A-2,

* indicates a point connected to any one of the main chain of the polymer or R ¹ and R ² of Formula 1, respectively.

R ¹ and R ² of Formula 1 are each independently a vinyl group, an allyl group, a substituted or unsubstituted C1 to C10 alkyl group, a substituted or unsubstituted C1 to C10 heteroalkyl group, a substituted or unsubstituted C3 to C20 It may be a cycloalkyl group, or a substituted or unsubstituted C6 to C20 aryl group, wherein the substitution may consist of a hydroxy group, a thiol group, an amino group, or a cyano group, and the hetero atom of the heteroalkyl group is oxygen, nitrogen, or may be selected from elemental sulfur.

L in Formula 2 is a single bond, a substituted or unsubstituted C1 to C10 alkylene group, or a substituted or unsubstituted C1 to C10 heteroalkylene group,

R ^k is a C1 to C10 alkyl group, C1 to C10 heteroalkyl group, C3 to C20 cycloalkyl group, C2 to C20 heterocycloalkyl group, It may be a C6 to C20 aryl group, or a C1 to C20 heteroaryl group, or a substituted or unsubstituted C2 to C5 lactone-containing group.

R ¹ and R ² in Formula 1 may each independently be a vinyl group, an allyl group, a substituted or unsubstituted C1 to C10 alkyl group, or a substituted or unsubstituted C1 to C10 heteroalkyl group, wherein the substituted Silver may consist of a hydroxyl group or a thiol group, and the hetero atom of the heteroalkyl group may be selected from oxygen or sulfur element.

R ¹ and R ² in Formula 1 may each independently be a C1 to C10 alkyl group substituted with a vinyl group, an allyl group, a hydroxyl group, or a C1 to C10 heteroalkyl group substituted with a hydroxyl group and containing a sulfur element. .

In Formula 2, L is a single bond, or a substituted or unsubstituted C1 to C10 alkylene group, R ^k is a C3 to C20 cycloalkyl group substituted with a hydroxy group or a thiol group, a C6 to C20 aryl group substituted with a hydroxyl group or a thiol group, or It may be a substituted or unsubstituted C3 to C5 lactone-containing cyclic group.

In Formula 2, L is a single bond or an unsubstituted C1 to C4 alkylene group, R ^k is a C3 to C10 cycloalkyl group substituted with a hydroxyl group, a C6 to C10 aryl group substituted with a hydroxyl group, or a substituted or unsubstituted C3 to C5 lactone-containing cyclic group.

The polymer may include at least one of a structural unit represented by Formula 3-1 or Formula 3-2, and a structural unit represented by Formula 4 to Formula 6 below.

[Formula 3-1]

[Formula 3-2]

[Formula 4]

[Formula 5]

[Formula 6]

In Formulas 4 to 6,

R ^a is hydrogen or a methyl group,

* is the connection point.

The polymer may have a weight average molecular weight of 1,000 g/mol to 100,000 g/mol.

The polymer may be included in an amount of 0.1 wt% to 50 wt% based on the total weight of the composition for a resist underlayer film.

The composition may further include one or more polymers selected from an acrylic resin, an epoxy resin, a novolac resin, a glycoluril-based resin, and a melamine-based resin.

The composition may further include an additive including a surfactant, a thermal acid generator, a plasticizer, a crosslinking agent, or a combination thereof.

Another embodiment is,

forming a film to be etched on the substrate;

forming a resist underlayer film by applying the composition for a resist underlayer film according to an embodiment on the etching target film;

forming a photoresist pattern on the resist underlayer, and

sequentially etching the resist underlayer layer and the etch target layer using the photoresist pattern as an etching mask

It provides a pattern forming method comprising a.

Forming the photoresist pattern is

forming a photoresist film on the resist underlayer;

exposing the photoresist film; and

It may include developing the photoresist layer.

The forming of the resist underlayer film may further include heat-treating the composition for a resist underlayer film at a temperature of 100°C to 500°C after coating the composition.

The composition for a resist underlayer according to an embodiment is capable of forming an ultra-thin film for a predetermined wavelength, such as EUV, and at the same time has excellent coating properties, planarization properties, and adhesion to photoresist, and is excellent for solutions used in the lithography process It is possible to provide a resist underlayer layer having chemical resistance and a fast etch rate. Accordingly, the composition for a resist underlayer according to an exemplary embodiment or a resist underlayer film prepared therefrom may be advantageously used to form a fine pattern of a photoresist using a high energy light source such as EUV.

1 to 5 are cross-sectional views for explaining a pattern forming method using a composition for a resist underlayer according to an exemplary embodiment.

Hereinafter, embodiments of the present invention will be described in detail so that those of ordinary skill in the art to which the present invention pertains can easily implement them. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein.

In order to clearly express the various layers and regions in the drawings, the thickness is enlarged and the same reference numerals are given to similar parts throughout the specification. When a part, such as a layer, film, region, plate, etc., is said to be “on” another part, it includes not only cases where it is “directly on” another part, but also cases where there is another part in between. Conversely, when we say that a part is "just above" another part, we mean that there is no other part in the middle.

Unless otherwise defined herein, 'substituted' means that a hydrogen atom in a compound is a halogen atom (F, Br, Cl, or I), a hydroxy group, an alkoxy group, a nitro group, a cyano group, an amino group, an azido group, an amino group Dino group, hydrazino group, hydrazono group, carbonyl group, carbamyl group, thiol group, ester group, carboxyl group or its salt, sulfonic acid group or its salt, phosphoric acid or its salt, vinyl group, C1 to C20 alkyl group, C2 to C20 alke Nyl group, C2 to C20 alkynyl group, C6 to C30 aryl group, C7 to C30 arylalkyl group, C6 to C30 allyl group, C1 to C30 alkoxy group, C1 to C20 heteroalkyl group, C3 to C20 heteroarylalkyl group, C3 to C30 cycloalkyl group , means substituted with a substituent selected from a C3 to C15 cycloalkenyl group, a C6 to C15 cycloalkynyl group, a C3 to C30 heterocycloalkyl group, and combinations thereof.

In addition, unless otherwise defined herein, 'hetero' means containing 1 to 10 heteroatoms each independently selected from N, O, S and P.

Unless otherwise specified herein, the weight average molecular weight is measured by dissolving a powder sample in tetrahydrofuran (THF) and then using Agilent Technologies' 1200 series Gel Permeation Chromatography (GPC) (column is Shodex). Company LF-804, standard sample is Shodex polystyrene).

In addition, unless otherwise defined herein, '*' indicates a connection point of a structural unit of a compound or a compound moiety.

Hereinafter, a composition for a resist underlayer film according to an embodiment will be described.

The present invention prevents the collapse of a resist pattern during the micropattern formation process of photolithography using a short wavelength light source such as ArF excimer laser (wavelength 193 nm) or high energy rays such as EUV (extreme ultraviolet; wavelength 13.5 nm), and is applied in an ultra-thin film It relates to a composition for a resist underlayer film, which can reduce the etching process time, and can improve patterning of a photoresist by improving sensitivity and light absorption efficiency to an exposure light source, and a photoresist pattern forming method using such an underlayer film.

Specifically, the composition for a resist underlayer according to an embodiment may include a copolymer including a structural unit represented by the following Chemical Formula 1 and a structural unit represented by Chemical Formula 2; and solvents.

[Formula 1]

In Formula 1,

A is a nitrogen-containing heterocyclic group,

R ¹ and R ² are each independently a vinyl group, an allyl group, a substituted or unsubstituted C1 to C10 alkyl group, a substituted or unsubstituted C2 to C10 alkenyl group, a substituted or unsubstituted C2 to C10 alkynyl group, substituted or an unsubstituted C1 to C10 heteroalkyl group, a substituted or unsubstituted C1 to C10 heteroalkenyl group, a substituted or unsubstituted C1 to C10 heteroalkynyl group, a substituted or unsubstituted C3 to C20 cycloalkyl group, a substituted or unsubstituted a C2 to C20 heterocycloalkyl group, a substituted or unsubstituted C6 to C20 aryl group, or a substituted or unsubstituted C1 to C20 heteroaryl group;

* is the point of connection with the backbone or end group of the polymer;

[Formula 2]

In Formula 2,

L is a single bond, a substituted or unsubstituted C1 to C10 alkylene group, or a substituted or unsubstituted C1 to C10 heteroalkylene group,

R ^a is hydrogen or a C1 to C5 alkyl group,

R ^k is a hydrophilic moiety,

* is a point connected to the main chain or end group of the polymer.

A of Formula 1 is a composition for a resist underlayer which is represented by at least one of Formula A-1 or Formula A-2:

[Formula A-1]

[Formula A-2]

In Formula A-1 and Formula A-2,

* indicates a point connected to any one of the main chain of the polymer or R ¹ and R ² of Formula 1, respectively.

By applying the composition according to the embodiment to the lower part of the photoresist to form a film, the adhesion between the film and the photoresist is improved, thereby preventing the resist pattern from collapsing during the fine patterning process, and the sensitivity to the exposure light source is improved. Accordingly, the patterning performance and efficiency of the photoresist may be improved. In addition, since the underlayer film can be formed as an ultra-thin film using the composition, there is an advantage in that the time of the etching process can be shortened.

In the polymer included in the composition, the structural unit represented by Formula 1 includes a triazine or isocyanurate skeleton capable of improving film density, and the triazine or isocyanurate skeleton It may include a functional group including a double bond in the anurate (isocyanurate) backbone. The functional group including the double bond has a high electron density because it is possible to bond with a triazine or isocyanurate backbone and sp ² -sp ² It can be implemented in the form of an ultra-thin film, and light absorption efficiency can be improved during exposure of the resist underlayer composition. In addition, when the resist underlayer film is formed using the resist underlayer film composition including the same, secondary electrons may be additionally generated during the photo process, and the additionally generated secondary electrons affect the photoresist during the photo process. It is possible to maximize the acid generation efficiency. Accordingly, the sensitivity of the photoresist may be improved by improving the photo-processing speed of the photoresist. In addition, since the triazine skeleton is included, the etch selectivity is excellent, and energy efficiency can be improved when the pattern is formed after exposure to high energy rays such as EUV (extreme ultraviolet; wavelength 13.5 nm) and E-beam (electron beam).

In the polymer included in the composition, the structural unit represented by Formula 2 includes a hydrophilic moiety, so that the physical properties of the composition including the same can be appropriately adjusted, and a triazine or isocyanurate skeleton in the polymer By allowing it to exist in this densely connected form, it is possible to increase the film density of the resist underlayer and aid in ultra-thin coating.

Although the polymer is polymerized to have a relatively high molecular weight, it has excellent solubility in organic solvents such as propylene glycol methyl ether (PGME). Accordingly, the resist underlayer film composition may exhibit excellent coatability due to excellent solubility with the organic solvent.

In addition, since the polymer is stable to organic solvents and heat, when a resist underlayer film is formed using a composition for a resist underlayer film containing the polymer, it is peeled off by solvent or heat during the process for forming a photoresist pattern. It is possible to minimize the generation of by-products due to the generation of chemical substances, etc., and also minimize the thickness loss due to the upper photoresist solvent.

Therefore, by using the resist underlayer composition according to the embodiment, it is possible to form a resist underlayer film with improved adhesion and chemical resistance, and through this, a faster etching effect can be expected compared to the upper photoresist, and the light absorption efficiency for the exposure light source is improved. It can be improved to improve the patterning performance.

In one embodiment, R ¹ and R ² of Formula 1 are each independently a vinyl group, an allyl group, a substituted or unsubstituted C1 to C10 alkyl group, a substituted or unsubstituted C1 to C10 heteroalkyl group, substituted or unsubstituted It may be a cyclic C3 to C20 cycloalkyl group, or a substituted or unsubstituted C6 to C20 aryl group, wherein the substitution may consist of a hydroxy group, a thiol group, an amino group, or a cyano group, and the hetero atom of the heteroalkyl group is may be selected from elemental oxygen, nitrogen, or sulfur.

In one embodiment, L in Formula 2 is a single bond, a substituted or unsubstituted C1 to C10 alkylene group, or a substituted or unsubstituted C1 to C10 heteroalkylene group,

R ^k is a C1 to C10 alkyl group, C1 to C10 heteroalkyl group, C3 to C20 cycloalkyl group, C2 to C20 heterocycloalkyl group, It may be a C6 to C20 aryl group, or a C1 to C20 heteroaryl group, or a substituted or unsubstituted C2 to C5 lactone-containing group.

In one embodiment, R ¹ and R ² in Formula 1 are each independently a vinyl group, an allyl group, a substituted or unsubstituted C1 to C10 alkyl group, or a substituted or unsubstituted C1 to C10 heteroalkyl group, and may be , Here, the substitution may be made of a hydroxyl group or a thiol group, and the hetero atom of the heteroalkyl group may be selected from oxygen or sulfur element.

R ¹ and R ² in Formula 1 may each independently be a C1 to C10 alkyl group substituted with a vinyl group, an allyl group, a hydroxyl group, or a C1 to C10 heteroalkyl group substituted with a hydroxyl group and containing a sulfur element. .

In one embodiment, L of Formula 2 is a single bond, or a substituted or unsubstituted C1 to C10 alkylene group, R ^k is a C3 to C20 cycloalkyl group substituted with a hydroxy group or a thiol group, C6 to substituted with a hydroxy group or a thiol group It may be a C20 aryl group, or a substituted or unsubstituted C3 to C5 lactone-containing cyclic group.

In Formula 2, L is a single bond or an unsubstituted C1 to C4 alkylene group, R ^k is a C3 to C10 cycloalkyl group substituted with a hydroxyl group, a C6 to C10 aryl group substituted with a hydroxyl group, or a substituted or unsubstituted C3 to C5 lactone-containing cyclic group.

In an embodiment, the polymer may include at least one of a structural unit represented by the following Chemical Formula 3 and a structural unit represented by the following Chemical Formulas 4 to 6.

[Formula 3]

[Formula 4]

[Formula 5]

[Formula 6]

In Formulas 4 to 6,

R ^a is hydrogen or a methyl group,

* is the connection point.

Meanwhile, the polymer may have a weight average molecular weight (Mw) of 1,000 g/mol to 100,000 g/mol. More specifically, the polymer may have a weight average molecular weight of 1,000 g/mol to 50,000 g/mol, or the polymer may have a weight average molecular weight of 2,000 g/mol to 30,000 g/mol. By having a weight average molecular weight within the above range, it can be optimized by controlling the carbon content and solubility in a solvent of the composition for a resist underlayer including the polymer.

The solvent is not particularly limited as long as it has sufficient solubility or dispersibility for the polymer, for example, propylene glycol, propylene glycol diacetate, propylene glycol methyl ether acetate, methoxy propanediol, diethylene glycol, diethylene glycol butyl ether, Tri(ethylene glycol) monomethyl ether, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, cyclohexanone, ethyl lactate, gamma-butyrolactone, N,N-dimethylformamide, N,N-dimethylacet amide, methylpyrrolidone, methylpyrrolidinone, methyl 2-hydroxyisobutyrate, acetylacetone, ethyl 3-ethoxypropionate, or combinations thereof.

The polymer may be included in an amount of 0.1 to 50% by weight, 0.1 to 30% by weight, or 0.1 to 15% by weight based on the total weight of the composition for the resist underlayer. By being included in the above range, it is possible to control the thickness, surface roughness, and planarization degree of the resist underlayer.

The content of the solid content in the composition for a resist underlayer may be, for example, 0.1 to 10 wt%, for example, 0.1 to 5 wt%, for example, 0.1 to 3 wt%. The solid content is obtained by excluding the solvent component from all components of the resist underlayer composition. By being included in the above range, it is possible to control the thickness, surface roughness, and planarization degree of the resist underlayer.

In addition, the composition for the resist underlayer may further include at least one other polymer selected from among an acrylic resin, an epoxy resin, a novolak resin, a glycoluril resin, and a melamine resin, in addition to the above-described polymer, but is limited thereto not.

The composition for the resist underlayer may further include an additive of a surfactant, a crosslinking agent, a thermal acid generator, a plasticizer, or a combination thereof.

The surfactant can be used to improve coating defects caused by an increase in the solid content when forming the resist underlayer, for example, alkylbenzenesulfonic acid salt, alkylpyridinium salt, polyethylene glycol, quaternary ammonium salt, etc. However, the present invention is not limited thereto.

In addition, the composition for a resist underlayer may further include a crosslinking agent. The crosslinking agent may be used to further harden the lower layer by inducing a crosslinking reaction, for example, melamine-based, substituted urea-based, or these polymers. Preferably, crosslinking agents having at least two crosslinking substituents are, for example, methoxymethylated glycouryl, butoxymethylated glycouryl, methoxymethylated melamine, butoxymethylated melamine, methoxymethylated benzoguanamine, butoxy A compound such as methylated benzoguanamine, methoxymethylated urea, butoxymethylated urea, methoxymethylated thiourea, or butoxymethylated thiourea may be used. The present invention is not limited thereto. As the crosslinking agent, a crosslinking agent having high heat resistance may be used, for example, a compound containing a crosslinking substituent having an aromatic ring (eg, a benzene ring or a naphthalene ring) in a molecule may be used. The crosslinking agent may have, for example, two or more crosslinking sites.

The thermal acid generator is, for example, an acidic compound such as p-toluenesulfonic acid, trifluoromethanesulfonic acid, pyridinium p-toluenesulfonate, salicylic acid, sulfosalicylic acid, citric acid, benzoic acid, hydroxybenzoic acid, naphthalenecarboxylic acid, and/or benzoin Tosylate, 2-nitrobenzyltosylate, and other organic sulfonic acid alkyl esters may be used, but the present invention is not limited thereto.

The plasticizer is not particularly limited, and various known plasticizers may be used. Examples of the plasticizer include low molecular weight compounds such as phthalic acid esters, adipic acid esters, phosphoric acid esters, trimellitic acid esters, and citric acid esters, and compounds such as polyether-based, polyester-based, and polyacetal-based compounds. can

The additive may be included in an amount of 0.001 to 40 parts by weight based on 100 parts by weight of the composition for a resist underlayer. By including it in the said range, solubility can be improved without changing the optical characteristic of the composition for resist underlayer films.

According to another embodiment, there is provided a resist underlayer film prepared by using the above-described composition for a resist underlayer film. The resist underlayer film may be in a form that is cured through a heat treatment process after coating the above-described composition for a resist underlayer film on, for example, a substrate.

Hereinafter, a method of forming a pattern using the above-described composition for a resist underlayer film will be described with reference to FIGS. 1 to 5 .

1 to 5 are cross-sectional views for explaining a pattern forming method using a composition for a resist underlayer 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 the thin film 102 formed on the semiconductor substrate 100 . Hereinafter, only the case where the object to be etched is the thin film 102 will be described. In order to remove contaminants and the like remaining on the thin film 102, the thin film surface is pre-cleaned. The thin film 102 may be, for example, a silicon nitride film, a polysilicon film, or a silicon oxide film.

Then, a composition for a resist underlayer film comprising a solvent and a polymer having moieties represented by Chemical Formulas 1 and 2 is coated on the surface of the cleaned thin film 102 by applying a spin coating method.

Thereafter, drying and baking processes are performed to form the resist underlayer 104 on the thin film. The baking treatment may be performed at 100 °C to 500 °C, for example, at 100 °C to 300 °C. A more detailed description of the composition for a resist underlayer film is omitted in order to avoid duplication since it has been described in detail above.

Referring to FIG. 2 , a photoresist layer 106 is formed by coating a photoresist on the resist underlayer layer 104 .

Examples of the photoresist include a positive photoresist containing a naphthoquinonediazide compound and a novolac resin, an acid generator capable of dissociating an acid upon exposure, decomposition in the presence of an acid to increase solubility in an alkaline aqueous solution, and a compound and A chemically amplified positive photoresist containing an alkali-soluble resin, a chemically amplified positive photoresist containing an alkali-soluble resin having a group capable of imparting a resin that increases solubility in aqueous alkali solution by decomposition in the presence of an acid generator and acid type photoresist and the like.

Next, a first baking process of heating the substrate 100 on which the photoresist film 106 is formed is performed. The first baking process may be performed at a temperature of 90 °C to 120 °C.

Referring to FIG. 3 , the photoresist layer 106 is selectively exposed.

When the exposure process for exposing the photoresist film 106 is described as an example, an exposure mask having a predetermined pattern formed thereon is placed on a mask stage of an exposure apparatus, and the exposure mask ( 110) are sorted. Then, by irradiating light to the mask 110 , a predetermined portion of the photoresist film 106 formed on the substrate 100 selectively reacts with the light passing through the exposure mask.

For example, examples of the light that can be used in the exposure process include an i-line activating radiation having a wavelength of 365 nm, a KrF excimer laser having a wavelength of 248 nm, and short-wavelength light such as an ArF excimer laser having a wavelength of 193 nm. In addition, extreme ultraviolet (EUV) light having a wavelength of 13.5 nm corresponding to extreme ultraviolet light may be used.

The photoresist film 106a of the exposed portion has relatively hydrophilicity compared to the photoresist film 106b of the unexposed portion. Accordingly, the photoresist film of the exposed portion 106a and the non-exposed portion 106b has different solubility.

Next, a second baking process is performed on the substrate 100 . The second baking process may be performed at a temperature of 90 °C to 150 °C. By performing the second baking process, the photoresist film corresponding to the exposed region is easily dissolved in a specific solvent.

Referring to FIG. 4 , a photoresist pattern 108 is formed by dissolving and then removing the photoresist layer 106a corresponding to the exposed area using a developer. Specifically, by using a developer such as tetra-methyl ammonium hydroxide (TMAH) to dissolve and then remove the photoresist film corresponding to the exposed region, the photoresist pattern 108 is completed.

Next, the resist underlayer layer is etched using the photoresist pattern 108 as an etching mask. The organic layer pattern 112 is formed through the etching process as described above. The etching may be performed, for example, by dry etching using an etching gas, and the etching gas may be, for example, CHF ₃ , CF ₄ , Cl ₂ , O ₂ , or a mixture thereof. As described above, since the resist underlayer film formed by the resist underlayer film composition according to the exemplary embodiment has a fast etching rate, a smooth etching process can be performed within a short time.

Referring to FIG. 5 , the exposed thin film 102 is etched by applying the photoresist pattern 108 as an etch mask. As a result, the thin film is formed as a thin film pattern 114 . In the exposure process performed above, the activating radiation also i-line (wavelength 365 nm), KrF excimer laser (wavelength 248 nm), and ArF excimer laser (wavelength 193 nm) a thin film pattern formed by the exposure process performed using a short-wavelength light source ( 114 may have a width of several tens of nm to several hundreds of nm, and the thin film pattern 114 formed by an exposure process performed using an EUV light source may have a width of 20 nm or less.

Hereinafter, the present invention will be described in more detail through examples relating to the synthesis of the above-described polymer and the preparation of a composition for a resist underlayer film comprising the same. However, the present invention is not technically limited by the following examples.

Synthesis example

Synthesis Example 1

1,3,5-triallyl-1,3,5-triazinane-2,4,6-trione (1,3,5-triallyl-1,3,5-triazinane- 2,4,6-trione) 25g and 3-mercapto-1-propanol (3-mercapto-1-propanol) 9.2g, AIBN (azobisisobutyronitrile) 7.4g, 4-vinylphenol (4-Vinylphenol) 12g and N, After adding 64.5 g of N-dimethylformamide (N,N-dimethylformamide), the temperature was raised while stirring using a magnetic bar, and the polymerization reaction was carried out at 80°C. After reacting for 10 hours, the temperature was lowered to room temperature (23° C.) and purified three times using toluene and hexane, and finally a polymer (molecular weight (Mw) = 7,000 g/mol).

[Formula 3] [Formula 4-1]

Synthesis Example 2

Formula 3 below in the same manner as in Synthesis Example 1, except that 17.8 g of 1-hydroxy-3-vinyl adamantane was used instead of 4-vinylphenol and a polymer (molecular weight (Mw) = 6,100 g/mol) including a structural unit represented by Formula 5-1 was obtained.

[Formula 3] [Formula 4-1]

Synthesis Example 3

In the same manner as in Synthesis Example 1, except that 11.2 g of 3-vinyldihydro-2(3H)-furanone was used instead of 4-vinylphenol, A polymer (molecular weight (Mw) = 7,200 g/mol) including structural units represented by the following Chemical Formulas 3 and 6-1 was obtained.

[Formula 3] [Formula 6-1]

Comparative Synthesis Example 1

1-[(hydroxyethyl]-3,5-bis[3-[(2-hydroxyethyl)thio]propyl]-1,3,5-triazine-2,4, After putting 64 g of 6-trion, 8.6 g of 1,3-propanedithiol (1,3-Propanedithiol), 6.3 g of AIBN and 86 g of N,N-dimethylformamide (DMF), the temperature was raised while stirring using a magnetic bar, The polymerization reaction was carried out at 80 ° C. After reacting for 10 hours, the reaction was carried out at room temperature (lower the temperature to 23 ° C. and purified three times using toluene and hexane. (Mw) = 6,800 g/mol) was obtained.

[Formula 7]

Preparation of a composition for a resist underlayer film

Examples 1 to 3 and Comparative Example 1

For each of the polymers prepared in Synthesis Examples 1 to 3 and Comparative Synthesis Example 1, 0.2 g of the polymer, PD1174 (TCI Corporation; crosslinking agent) 0.05 g, and pyridinium p-toluenesulfonate (PPTS) Total solid content (Total) by completely dissolving in 100 g of a mixed solvent (mixing volume ratio = 7:3) of propylene glycol methyl ether (PGME) and ethyl lactate (EL) together with 0.005 g Solid Content, TSC) was prepared so that the composition for the resist underlayer of Examples 1 to 3 and Comparative Example 1 was 1%, respectively.

polymer crosslinking agent thermal acid generator menstruum Example 1 Synthesis Example 1 PD1174 PPTS PGME/EL Example 2 Synthesis Example 2 Example 3 Synthesis Example 3 Comparative Example 1 Comparative Synthesis Example 1

Membrane density evaluation

The resist underlayer compositions according to Examples 1 to 3 and Comparative Example 1 were respectively coated on a silicon substrate by a spin-on coating method, and then heat treated at 205° C. for 1 minute on a hot plate to form a resist underlayer film with a thickness of about 100 nm. .

Next, the density of the resist underlayer film was measured, and the results are shown in Table 2. The density of the resist underlayer film was measured using an X-Ray Diffractometer (Model: X'Pert PRO MPD, manufactured by Panalytical (Netherlands)).

Membrane density (g/cm ³ ) Example 1 1.39 Example 2 1.38 Example 3 1.36 Comparative Example 1 1.34

Referring to Table 2, it can be seen that the film formed using the composition for the resist underlayer film according to Examples 1 to 3 has a higher density than the film formed using the composition for the resist underlayer film according to Comparative Example 1. This is presumed to be because the polymer included in the compositions for resist underlayer according to Examples 1 to 3 includes a functional group including a double defect, and thus the film density is improved due to high intermolecular bonding force and molecular polarity.

From the results of Table 2, it can be seen that, when the compositions for resist underlayer films according to Examples 1 to 3 are used, a film having a more dense structure than that of Comparative Example 1 can be formed.

Contact angle evaluation

2 ml of each of the compositions for resist underlayer prepared in Examples 1 to 3 and Comparative Example 1 were respectively applied on a 4-inch wafer, and then spin-coated at 1,500 rpm for 20 seconds using a spin coater (Mikasa). . Thereafter, after curing at 210° C. for 90 seconds to form a thin film, the contact angle when distilled water (DIW) was dropped on the surface was measured. The measured contact angles are as shown in Table 3 below. It can be seen that the larger the contact angle, the better the adhesion with the resist.

Contact angle (°) Example 1 66 Example 2 65 Example 3 64 Comparative Example 1 61

Exposure characteristics evaluation

After each of the compositions prepared in Examples 1 to 3 and Comparative Example 1 was applied by a spin-on coating method, heat treatment was performed on a hot plate at 205° C. for 1 minute to form a resist underlayer film having a thickness of about 10 nm.

Thereafter, a photoresist solution was applied on the photoresist underlayer by a spin-on coating method, and then heat-treated on a hot plate at 110° C. for 1 minute to form a photoresist layer. The photoresist layer was exposed to an acceleration voltage of 100 keV using an e-beam exposure machine (manufactured by Elionix), and then heat-treated at 110° C. for 60 seconds. Subsequently, the photoresist layer was developed for 60 seconds with a 2.38 mass% aqueous solution of tetramethylammonium hydroxide (TMAH) at 23° C., and then rinsed in pure water for 15 seconds to form a line and space (line and space, L/ A photoresist pattern of S) was formed.

Next, the optimal exposure amount of the photoresist pattern was evaluated, and the results are shown in Table 4. Here, the exposure dose that resolves the line and space of 100 nm 1:1 is called the optimal exposure dose (Eop, μC/cm 2 ).

Eop (μC/cm2) Example 1 320 Example 2 340 Example 3 330 Comparative Example 1 350

Referring to Table 4, when the resist underlayer film was formed using the composition for the photoresist underlayer film according to Examples 1 to 3, it can be confirmed that the optimal exposure amount of the photoresist pattern is superior to that of Comparative Example 1.

Therefore, from the results of Table 4, it can be seen that, when the compositions for resist underlayer films according to Examples 1 to 3 are used, a photoresist pattern having better sensitivity than Comparative Example 1 can be formed.

In the foregoing, specific embodiments of the present invention have been described and illustrated, but it is common knowledge in the art that the present invention is not limited to the described embodiments, and that various modifications and variations can be made without departing from the spirit and scope of the present invention. It is self-evident to those who have Accordingly, such modifications or variations should not be individually understood from the technical spirit or point of view of the present invention, and the modified embodiments should belong to the claims of the present invention.

100: substrate 102: thin film
104: resist underlayer film 106: photoresist film
108: photoresist pattern 110: mask
112: organic film pattern 114: thin film pattern

Claims (16)

a copolymer comprising a structural unit represented by the following formula (1) and a structural unit represented by formula (2); And a composition for a resist underlayer comprising a solvent:
[Formula 1]

In Formula 1,
A is a nitrogen-containing heterocyclic group,
R ¹ and R ² are each independently a vinyl group, an allyl group, a substituted or unsubstituted C1 to C10 alkyl group, a substituted or unsubstituted C2 to C10 alkenyl group, a substituted or unsubstituted C2 to C10 alkynyl group, substituted or an unsubstituted C1 to C10 heteroalkyl group, a substituted or unsubstituted C1 to C10 heteroalkenyl group, a substituted or unsubstituted C1 to C10 heteroalkynyl group, a substituted or unsubstituted C3 to C20 cycloalkyl group, a substituted or unsubstituted a C2 to C20 heterocycloalkyl group, a substituted or unsubstituted C6 to C20 aryl group, or a substituted or unsubstituted C1 to C20 heteroaryl group;
* is the point of connection with the backbone or end group of the polymer;
[Formula 2]

In Formula 2,
L is a single bond, a substituted or unsubstituted C1 to C10 alkylene group, or a substituted or unsubstituted C1 to C10 heteroalkylene group,
R ^a is hydrogen or a C1 to C5 alkyl group,
R ^k is a hydrophilic moiety,
* is a point connected to the main chain or end group of the polymer. In claim 1,
A of Formula 1 is a composition for a resist underlayer which is represented by at least one of Formula A-1 or Formula A-2:
[Formula A-1]

[Formula A-2]

In Formula A-1 and Formula A-2,
* indicates a point connected to any one of the main chain of the polymer or R ¹ and R ² of Formula 1, respectively. In claim 1,
R ¹ and R ² of Formula 1 are each independently a vinyl group, an allyl group, a substituted or unsubstituted C1 to C10 alkyl group, a substituted or unsubstituted C1 to C10 heteroalkyl group, a substituted or unsubstituted C3 to C20 A cycloalkyl group, or a substituted or unsubstituted C6 to C20 aryl group, wherein the substitution consists of a hydroxy group, a thiol group, an amino group, or a cyano group, and the hetero atom of the heteroalkyl group is an oxygen, nitrogen, or sulfur element A composition for a resist underlayer film selected from. In claim 1,
L in Formula 2 is a single bond, a substituted or unsubstituted C1 to C10 alkylene group, or a substituted or unsubstituted C1 to C10 heteroalkylene group,
R ^k is a C1 to C10 alkyl group, C1 to C10 heteroalkyl group, C3 to C20 cycloalkyl group, C2 to C20 heterocycloalkyl group, A composition for a resist underlayer film comprising a C6 to C20 aryl group, a C1 to C20 heteroaryl group, or a substituted or unsubstituted C2 to C5 lactone-containing group. In claim 1,
R ¹ and R ² in Formula 1 are each independently a vinyl group, an allyl group, a substituted or unsubstituted C1 to C10 alkyl group, or a substituted or unsubstituted C1 to C10 heteroalkyl group, wherein the substitution is A composition for a resist underlayer film consisting of a hydroxy group or a thiol group, wherein the hetero atom of the heteroalkyl group is selected from oxygen or sulfur element. In claim 1,
R ¹ and R ² in Formula 1 are each independently selected from a C1 to C10 alkyl group substituted with a vinyl group, an allyl group, a hydroxyl group, or a C1 to C10 heteroalkyl group substituted with a hydroxyl group and containing a sulfur element A composition for a resist underlayer film. In claim 1,
L in Formula 2 is a single bond, or a substituted or unsubstituted C1 to C10 alkylene group,
R ^k is a C3 to C20 cycloalkyl group substituted with a hydroxyl group or a thiol group, a C6 to C20 aryl group substituted with a hydroxyl group or a thiol group, or a substituted or unsubstituted C3 to C5 lactone-containing cyclic group. In claim 1,
L in Formula 2 is a single bond, or an unsubstituted C1 to C4 alkylene group,
R ^k is a C3 to C10 cycloalkyl group substituted with a hydroxyl group, a C6 to C10 aryl group substituted with a hydroxyl group, or a substituted or unsubstituted C3 to C5 lactone-containing cyclic group. In claim 1,
The polymer is a composition for a resist underlayer film comprising at least one of a structural unit represented by the following Chemical Formula 3-1 or Chemical Formula 3-2, and a structural unit represented by the following Chemical Formulas 4 to 6:
[Formula 3]

[Formula 3-2]

[Formula 4]

[Formula 5]

[Formula 6]

In Formulas 4 to 6,
R ^a is hydrogen or a methyl group,
* is the connection point. The composition of claim 1, wherein the polymer has a weight average molecular weight of 1,000 g/mol to 100,000 g/mol. The composition for the resist underlayer according to claim 1, wherein the polymer is included in an amount of 0.1 to 50% by weight based on the total weight of the composition for the resist underlayer. The composition for a resist underlayer according to claim 1, further comprising at least one polymer selected from an acrylic resin, an epoxy resin, a novolak resin, a glycoluril-based resin, and a melamine-based resin. The composition of claim 1, further comprising an additive including a surfactant, a thermal acid generator, a plasticizer, a crosslinking agent, or a combination thereof. forming a film to be etched on the substrate;
Forming a resist underlayer film by applying the composition for a resist underlayer film according to any one of claims 1 to 13 on the etch target film;
forming a photoresist pattern on the resist underlayer, and
sequentially etching the resist underlayer layer and the etch target layer using the photoresist pattern as an etching mask
A pattern forming method comprising a. 15. In claim 14,
Forming the photoresist pattern is
forming a photoresist film on the resist underlayer;
exposing the photoresist film; and
and developing the photoresist film. The method of claim 14 , wherein the forming of the resist underlayer further comprises heat-treating at a temperature of 100° C. to 500° C. after coating the composition for the resist underlayer.

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