KR101863634B1 - Self-crosslinking polymer, resist under-layer composition including the same, and method for forming pattern using the same - Google Patents

Abstract

상기 화학식 1에서, Ar은 탄소수 6 내지 30의 아릴(aryl)기이고, R은 수소 또는 탄소수 1 내지 6의 알킬(alkyl)기이며, a는 Ar에 치환된 히드록시기(-OH)의 개수로서, 1 내지 3의 정수이고, b는 Ar에 치환된 카보닐기(-COR)의 개수로서, 1 내지 3의 정수이다.A self-crosslinking polymer used in a semiconductor lithography process, a resist underlayer film composition comprising the same, and a pattern forming method using the same. The self-crosslinking polymer includes a repeating unit represented by the following formula (1).
[Chemical Formula 1]

Wherein Ar is an aryl group having 6 to 30 carbon atoms, R is hydrogen or an alkyl group having 1 to 6 carbon atoms, a is the number of hydroxyl groups (-OH) substituted in Ar, And b is an integer of 1 to 3 as the number of carbonyl groups (-COR) substituted on Ar.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a self-crosslinking polymer, a resist underlayer film composition containing the self-crosslinking polymer, and a pattern forming method using the self-crosslinking polymer,

More particularly, the present invention relates to a self-crosslinking polymer used in a semiconductor lithography process, a resist underlayer film composition containing the self-crosslinking polymer, and a pattern forming method using the self-crosslinking polymer will be.

2. Description of the Related Art In recent years, along with the increase in integration and speed of a large scale integrated circuit (LSI), semiconductor patterns have become finer, and lithography using light exposure, which is currently used as general purpose technology, Lt; RTI ID = 0.0 > resolution. ≪ / RTI > As a light source for lithography used for forming a resist pattern, g-line (436 nm) and i-line (365 nm) using a mercury lamp have been widely used. Recently, KrF excimer laser excimer laser (248 nm), and ArF excimer laser (193 nm).

In addition, with the miniaturization and integration of semiconductor devices, the thickness of the photoresist film and the pattern gradually become thinner in order to prevent the collapse of the photoresist pattern as the pattern size becomes smaller. However, since it is difficult to etch the etching layer by using a thinned photoresist pattern, an inorganic or organic film having high etching resistance is introduced between the photoresist and the etching layer. do. The step of etching the lower layer film by using a photoresist pattern and patterning, and then etching the etching layer by using the pattern of the lower layer film may be referred to as an underlayer film process. The lower inorganic layer film used in the lower layer film process is formed of silicon nitride, silicon oxynitride, polysilicon, titanium nitride, amorphous carbon or the like and is usually formed by a chemical vapor deposition (CVD) . The lower layer film produced by the chemical vapor deposition method is excellent in etching selectivity and etching resistance, but has some problems such as particle problem and initial facility investment cost. As a method for solving this problem, an organic undercoat film capable of spin coating has been researched instead of the above-mentioned evaporated underlayer film.

The multilayer film resist including the organic underlayer film usually has a two-layer film structure (two-layer resist method) or a three-layer film structure (three-layer resist method). In the case of a resist having a two-layer structure, the upper layer film is a photoresist film capable of realizing a pattern, and the lower layer film is a hydrocarbon compound film capable of etching with oxygen gas. When the substrate under the lower layer film is etched, the resist lower layer film must have a high etching resistance because it has to serve as a hard mask. In order to etch the oxygen gas, It is necessary to be composed of only the non-hydrocarbon. In addition, when the KrF and ArF light sources are used, the resist underlayer film needs to have a function of a diffused reflection preventing film of the light source in order to prevent standing wave control of the upper resist film and collapse of the pattern. Specifically, it is necessary to suppress the reflectance from the lower layer film to the upper layer resist film to 1% or less.

Further, in the case of a resist having a three-layer film structure, an inorganic hard mask intermediate layer film (second lower layer film made of an inorganic material) is further formed between the upper layer film (photoresist film) and the resist lower layer film (first lower layer film made of a hydrocarbon compound) do. As the second lower layer film, a silicon oxide film (silicon oxide film), a silicon nitride film (silicon nitride film), a silicon oxynitride film (silicon oxynitride film, SiON film) or the like formed by a chemical vapor deposition method can be used And a SiON film having a high effect as an antireflection film can be preferably used. The film thickness of the second lower layer film is 5 to 200 nm, preferably 10 to 100 nm. In order to form the second lower layer film (particularly, the SiON film) on the resist lower layer film (the first lower layer film), the temperature of the substrate must be raised to 240 to 500 DEG C, And should have thermal stability at 240 to 500 ° C. If the resist underlayer film does not have thermal stability at a high temperature (for example, 400 ° C or higher), there is a fear that the resist underlayer film is decomposed when the inorganic hard mask interlayer film (second lower layer film) is formed, and the inside of the equipment is contaminated.

Accordingly, an object of the present invention is to provide a self-crosslinking polymer which is excellent in thermal stability and can be spin-coated to form a hard mask, a resist underlayer film composition containing the same, and a pattern forming method using the same.

Another object of the present invention is to provide a self-crosslinking polymer capable of performing the function of an organic antireflection film, a resist underlayer film composition comprising the same, and a pattern forming method using the same.

It is still another object of the present invention to provide a self-crosslinking polymer having excellent etching resistance as well as excellent planarization even when applied to a patterned wafer having a step, a resist underlayer film composition containing the same, and a pattern forming method using the same .

In order to achieve the above object, the present invention provides a polymer comprising a repeating unit represented by the following formula (1).

[Chemical Formula 1]

Wherein Ar is an aryl group having 6 to 30 carbon atoms, R is hydrogen or an alkyl group having 1 to 6 carbon atoms, a is the number of hydroxyl groups (-OH) substituted in Ar, And b is an integer of 1 to 3 as the number of carbonyl groups (-COR) substituted on Ar.

The present invention also relates to a self-crosslinking polymer comprising the repeating unit represented by Formula 1 above; And a resist underlayer film composition comprising an organic solvent.

According to another aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising: forming a resist underlayer film on a substrate to be etched using the resist underlayer film composition; Forming a photoresist layer on the resist underlayer film; Exposing the photoresist layer to radiation in a predetermined pattern to produce a pattern of radiation exposed areas in the photoresist layer; Selectively removing the photoresist layer and the resist underlayer film along the pattern to expose the substrate in the form of the pattern; And etching the exposed portion of the substrate.

The polymer for forming a resist lower layer film according to the present invention is capable of forming a hard mask by spin coating and is characterized by excellent thermal stability and etching resistance due to self-crosslinking as compared with conventional novolak resins. In addition, the underlayer film formed according to the present invention is not only capable of functioning as an organic antireflection film, but also has an advantage of being highly planarized even when applied to a stepped wafer.

Hereinafter, the present invention will be described in detail.

The self-crosslinking polymer according to the present invention is for forming a lower layer film (serving as a hard mask) for etching a substrate in a predetermined pattern, which is located between a substrate to be etched and a photoresist film, Unit.

), 나프탈렌(

), 안트라센(

), 파이렌(pyrene,

) 등을 예시할 수 있다. 상기 R은 서로 같거나 다를 수 있으며, 구체적으로는, 메틸기, 에틸기, 노말-프로필기, 이소-프로필기, 노말-부틸기, 이소-부틸기, 터셔리-부틸기, 펜틸기, 사이클로펜틸기, 헥실기 등을 예시할 수 있다. 상기 Ar의 좌측 및 우측 결합손과 Ar에 치환되는 하나 이상의 히드록시기(-OH) 및 하나 이상의 카보닐기(-COR)는 Ar을 형성하는 아릴기의 어느 탄소에도 위치할 수 있다. 또한, 필요에 따라, 상기 아릴기(Ar) 및 알킬기(R)은 할로겐 원자, 히드록시기, 니트로기, 시아노기, 아미노기, 탄소수 1 내지 6의 저급 알킬기 등으로 더욱 치환되어 있을 수 있다.
In Formula 1, Ar is an aryl group having 6 to 30 carbon atoms, preferably 6 to 20 carbon atoms, R is hydrogen or an alkyl group having 1 to 6 carbon atoms, a is a hydroxyl group substituted with Ar, (-OH) is an integer of 1 to 3, and b is an integer of 1 to 3, as the number of carbonyl groups (-COR) substituted on Ar. Specific examples of Ar include an aromatic ring group or an aromatic fused ring group, and more specifically, benzene (

), Naphthalene (

), Anthracene (

), Pyrene (pyrene,

), And the like. The R may be the same or different from each other and specific examples thereof include a methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, iso-butyl group, tertiary butyl group, pentyl group, , Hexyl group, and the like. The left and right binding hands of Ar and one or more hydroxyl groups (-OH) and one or more carbonyl groups (-COR) substituted on Ar may be located on any carbon of the aryl group forming Ar. The aryl group (Ar) and the alkyl group (R) may be further substituted with a halogen atom, a hydroxy group, a nitro group, a cyano group, an amino group, a lower alkyl group having 1 to 6 carbon atoms and the like.

The polymer having the repeating unit represented by the formula (1) has a weight average molecular weight of 500 to 1,000,000, preferably 1,000 to 20,000, more preferably 2,000 to 10,000. When the polymer has a weight average molecular weight of less than 500, the formation of a thin film at the time of forming a resist lower layer film is not easy, while when it exceeds 1,000,000, the solubility of the polymer in a solvent decreases and viscosity increases, This is a difficult disadvantage. The self-crosslinking polymer according to the present invention may contain a small amount of another repeating unit as long as the object of the present invention is not impaired. The self-crosslinking polymer according to the present invention can be prepared by condensation reaction of a phenol derivative compound containing a carbonyl group (including an aldehyde group) with formaldehyde as shown in the following examples.

The self-crosslinking polymer according to the present invention has a phenol structure with a carbonyl group (including an aldehyde group) as compared with a general novolak resin, so that when a resist underlayer film is formed, the hydroxyl group of the main chain of the polymer reacts with the carbonyl group , The polymer is self-crosslinked to form a hard mask having excellent etching resistance. The cross-linked polymer at high temperature has a lower solubility in the solvent, so that the polymer is resistant to the solvent, and the flow is controlled in comparison with the novolak-type resin. In addition, the crosslinking of the polymer can be confirmed by the reduction of the etching rate due to the formation of the matrix due to the crosslinking.

The present invention also provides a resist underlayer film composition comprising a self-crosslinking polymer comprising the repeating unit represented by the above-mentioned formula (1) and an organic solvent. Examples of the organic solvent include, but are not limited to, propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monomethyl ether (PGME), propylene glycol monomethyl ether ), Cyclohexanone (CH), ethyl lactate (EL), gamma-butyrolactone (GBL), and the like are preferably used alone or in combination. In the resist underlayer film composition, the content of the self-crosslinking polymer is 1 to 30% by weight, preferably 3 to 15% by weight, more preferably 5 to 12% by weight, , And it is 70 to 99% by weight, preferably 85 to 97% by weight, more preferably 88 to 95% by weight. If the content of the polymer is less than 1% by weight, a lower layer film having a desired thickness may not be formed, and there is a possibility that the lower layer film will not be formed uniformly. If the content of the polymer exceeds 30% There is a possibility that the film is not uniformly formed.

The resist underlayer film composition according to the present invention may further include a cross-linking agent, an acid catalyst, or the like for improving the crosslinking rate or the curing rate of the underlayer film. In addition to the self-crosslinking reaction of the polymer according to the present invention, the crosslinking agent is used for further curing the lower layer film by inducing an additional crosslinking reaction, and it is possible to use a conventional melamine resin, an amino resin, a glycoluril compound, a bisepoxy compound and the like . The content of the crosslinking agent is generally 0.1 to 5% by weight, preferably 0.1 to 3% by weight based on the total lower layer film composition. The acid catalyst may be a conventional thermal acid generator such as p-toluene sulfonic acid monohydrate or pyridinium p-toluene sulfonate or a photoacid generator such as p-toluene sulfonate, Can be used. The content of the acid catalyst is generally 0.001 to 0.05% by weight, and more preferably 0.001 to 0.03% by weight, based on the total lower layer film composition. The resist underlayer film composition according to the present invention has a film-forming property capable of forming a film by conventional spin coating.

The present invention also provides a pattern forming method using the resist lower layer film composition. Specifically, the pattern forming method includes: (a) forming a resist underlayer film using the resist underlayer film composition according to the present invention on an upper surface of a substrate to be etched (for example, a silicon wafer having an aluminum layer formed thereon); (b) forming a photoresist layer on the resist underlayer film; (c) exposing the photoresist layer to radiation in a predetermined pattern to produce a pattern of radiation exposed areas in the photoresist layer; (d) selectively removing the photoresist layer and the resist undercoat film along the pattern to expose the substrate in the form of the pattern; And (e) etching the exposed portion of the substrate. If necessary, a conventional silicon-containing resist lower layer film (lower inorganic layer film) and / or a bottom anti-reflection coating (BARC) may be further formed on the upper resist underlayer film before the step (b) .

The step of forming the resist underlayer film may be performed by spin-coating the resist underlayer film composition according to the present invention to a thickness of 500 to 6,000 ANGSTROM on the substrate and heating at a temperature of 180 to 500 DEG C for 50 to 180 seconds And the thickness of the resist underlayer film thus formed is approximately 40 to 550 nm. In particular, the resist underlayer film composition according to the present invention can undergo self-crosslinking even at a low temperature of 180 to 250 占 폚 to easily form a lower layer film. On the other hand, in the case of a conventional novolak resin, since it is not crosslinked at a temperature of 180 to 250 ° C, resistance to a solvent is low and a film is reduced. The pattern formation of the photoresist film may be performed by developing using a conventional alkali aqueous solution such as a TMAH developer. The removal of the lower layer film may be performed by dry etching using a CHF ₃ / CF ₄ mixed gas or the like And etching of the substrate may be performed by Cl ₂ or HBr gas. Here, the thickness of the lower resist film, the heating temperature and time, the etching method, and the like are not limited to the above contents, but can be variously changed according to processing conditions.

The resist underlayer film formed in accordance with the present invention contains an aromatic ring having strong radiation absorption in a short wavelength region (for example, 193 nm or 248 nm) of ultraviolet light, so that light reflection can be minimized. Therefore, the resist underlayer film formed in accordance with the present invention may also serve as an organic antireflection film. Furthermore, the resist underlayer film formed according to the present invention has a resistance equal to or higher than that of the conventional novolac resin, thereby serving as a protective film (hard mask) for forming a pattern in a dry etching process. Generally, the lower the etching rate of the resist lower layer film, the less the loss of the mask is, and the etch amount of the lower film layer (substrate) can be increased. As described above, by increasing the etching amount of the underlying film, that is, by deepening the depth of the etching pattern, it is possible to more easily increase the interlayer spacing between the upper and lower layers at the time of forming the semiconductor chip.

Hereinafter, the present invention will be described in more detail with reference to specific examples. The following examples illustrate the present invention and are not intended to limit the scope of the present invention.

[Example 1-1] Preparation of polymer represented by formula (1-1)

In a 250 mL three-necked flask equipped with a reflux tube, 20 mL of ethyl lactate was placed, and the temperature was raised to 110 ° C. A mixed solution of 24.4 g (0.2 mol) of 4-hydroxybenzaldehyde, 17.8 g (0.22 mol) of a 37% formalin aqueous solution (aqueous solution of 37% formaldehyde), 0.5 g of oxalic acid and 40 g of ethyl lactate was stirred for 3 hours , And reacted for 5 hours. After the reaction was completed, the temperature of the reactor was lowered to room temperature, and 50 g of methanol was added to the reactor. Next, the reaction product was slowly added to 1500 mL of deionized water, the solid was filtered, and then dried in a 60 DEG C vacuum oven for 24 hours to obtain a polymer having the following formula 1-1 (wherein n represents the degree of polymerization) Were synthesized. The yield of the synthesized polymer was 94%, the weight average molecular weight (Mw) using GPC (gel chromatography) was 8,860, and the polydispersity (PD) was 4.58.

[Formula 1-1]

[Example 1-2] Preparation of a polymer represented by the general formula (1-2)

Was obtained in the same manner as in Example 1, except that 27.2 g (0.2 mol) of 4'-hydroxyacetophenone was used instead of 24.4 g (0.2 mol) of 4-hydroxybenzene aldehyde, and n represents the degree of polymerization). The yield of the synthesized polymer was 92%, the weight average molecular weight (Mw) using GPC (gel chromatography) was 7,150 and the polydispersity (PD) was 4.12.

[Formula 1-2]

[Example 1-3] Preparation of polymer represented by formula 1-3

Was obtained in the same manner as in Example 1, except that 30.0 g (0.2 mol) of 4'-hydroxypropiophenone was used instead of 24.4 g (0.2 mol) of 4-hydroxybenzene aldehyde, , and n represents the degree of polymerization). The yield of the synthesized polymer was 91%, the weight average molecular weight (Mw) using GPC (gel chromatography) was 6,240, and the polydispersity (PD) was 3.96.

[Formula 1-3]

[Example 1-4] Preparation of polymer represented by formula (1-4)

(0.2 mol) of 4-hydroxy-1-naphthalaldehyde was used instead of 24.4 g (0.2 mol) of 4-hydroxybenzene aldehyde in the same manner as in Example 1, (Where n represents the degree of polymerization). The yield of the synthesized polymer was 82%, the weight average molecular weight (Mw) using GPC (gel chromatography) was 4,630 and the polydispersity (PD) was 3.24.

[Formula 1-4]

[Example 1-5] Preparation of a polymer represented by the formula (1-5)

(0.2 mol) of 6-hydroxy-2-naphthalaldehyde was used in place of 24.4 g (0.2 mol) of 4-hydroxybenzene aldehyde in the same manner as in Example 1, (Where n represents the degree of polymerization). The yield of the synthesized polymer was 90%, the weight average molecular weight (Mw) using GPC (gel chromatography) was 6,880, and the polydispersity (PD) was 4.26.

[Formula 1-5]

[Example 1-6] Preparation of a polymer represented by the formula 1-6

(0.2 mol) of 4-hydroxybenzene aldehyde was replaced by 37.2 g (0.2 mol) of 4'-hydroxy-1'-acetonaphtone in place of 24.4 g (0.2 mol) of 4-hydroxybenzene aldehyde, -6 (where n represents the degree of polymerization). The yield of the synthesized polymer was 82%, the weight average molecular weight (Mw) using GPC (gel chromatography) was 5,580, and the polydispersity (PD) was 4.17.

[Chemical Formula 1-6]

[Example 1-7] Preparation of the polymer represented by the formula 1-7

(0.2 mol) of 10-hydroxy-anthracene-9-carboaldehyde was used instead of 24.4 g (0.2 mol) of 4-hydroxybenzene aldehyde in the same manner as in Example 1, 7, wherein n represents the degree of polymerization. The yield of the synthesized polymer was 63%, the weight average molecular weight (Mw) using GPC (gel chromatography) was 4,010 and the polydispersity (PD) was 6.38.

[Chemical Formula 1-7]

[Example 1-8] Preparation of polymer represented by the general formula 1-8

Was obtained in the same manner as in Example 1, except that 49.2 g (0.2 mol) of 6-hydroxy-pherene-1-carboaldehyde was used instead of 24.4 g (0.2 mol) of 4-hydroxybenzene aldehyde. -8 (wherein n represents the degree of polymerization). The yield of the synthesized polymer was 70%, the weight average molecular weight (Mw) using GPC (gel chromatography) was 3,120, and the polydispersity (PD) was 4.82.

[Chemical Formula 1-8]

[Example 1-9] Preparation of polymer represented by the general formula 1-9

Was obtained in the same manner as in Example 1, except that 41.2 g (0.2 mol) of 4'-hydroxyheptanophenone was used instead of 24.4 g (0.2 mol) of 4-hydroxybenzene aldehyde, , and n represents the degree of polymerization). The yield of the synthesized polymer was 98%, the weight average molecular weight (Mw) using GPC (gel chromatography) was 9,590, and the polydispersity (PD) was 4.04.

[Chemical Formula 1-9]

[Comparative Example 1] Preparation of a polymer represented by the formula (2)

Except that 18.8 g (0.2 mol) of phenol was used in place of 24.4 g (0.2 mol) of 4-hydroxybenzene aldehyde in the same manner as in Example 1, Were synthesized. The synthesized polymer had a weight average molecular weight (Mw) of 5,650 and a polydispersity (PD) of 4.25 by GPC (gel chromatography).

(2)

The thermal stability of the polymers obtained in Examples 1-1 to 1-9 and the novolac resin obtained in Comparative Example 1 was measured using a thermogravimetric analyzer (TGA, TA) The results are shown in Table 1 below.

division Bake temperature (캜) Mass loss by TGA (wt%) Example 1-1 400 6.5 Examples 1-2 400 5.6 Example 1-3 400 4.9 Examples 1-4 400 6.8 Examples 1-5 400 5.4 Examples 1-6 400 3.9 Examples 1-7 400 5.5 Examples 1-8 400 5.1 Examples 1-9 400 4.9 Comparative Example 1 400 62.4

[Examples 2-1 to 2-9 Resist Preparation of Undercoat Film Composition

As shown in the following Table 2, 10 g of the polymer resin obtained in Examples 1-1 to 1-9 was dissolved in 60 g of propylene glycol methyl ether acetate (PGMEA) and 30 g of cyclohexanone (CH) to form a solution, And filtered through a micro-filter having a pore size of 0.45 mu m to prepare a resist underlayer film composition.

[Examples 2-10 and 2-11] resist Preparation of Undercoat Film Composition

As shown in the following Table 2, 0.5 g of TAG-2678 (manufactured by King Industries) as a thermal acid generator was further added to the compositions of Examples 2-1 and 2-4 to prepare a resist underlayer film composition.

Comparative Example 2 A resist Preparation of Undercoat Film Composition

As shown in the following Table 2, a resist underlayer film composition was prepared in the same manner as in Example 2-1 except that 10 g of the polymer obtained in Comparative Example 1 was used instead of 10 g of the polymer of Example 1-1

[Comparative Example 3] The resist Preparation of Undercoat Film Composition

As shown in the following Table 2, 0.5 g of TAG-2678 (manufactured by King Industries) as a thermal acid generator was further added to the composition of Comparative Example 2 to prepare a resist underlayer film composition.

Comparative Example 4 Resist Preparation of Undercoat Film Composition

As shown in the following Table 2, 1.0 g of tetramethoxymethylglycoluril (trade name: MX-270) as a crosslinking agent was further added to the composition of Comparative Example 3 to prepare a resist underlayer film composition.

Polymer resin Cross-linking agent Thermal acid generator menstruum division Polymer usage PGMEA CH Example 2-1 (1-1) 10g - - 60g 30g Example 2-2 1-2 10g - - 60g 30g Example 2-3 1-3 10g - - 60g 30g Examples 2-4 Formula 1-4 10g - - 60g 30g Example 2-5 1-5 10g - - 60g 30g Examples 2-6 1-6 10g - - 60g 30g Examples 2-7 1-7 10g - - 60g 30g Examples 2-8 1-8 10g - - 60g 30g Examples 2-9 1-9 10g - - 60g 30g Examples 2-10 (1-1) 10g - TAG-2678 / 0.5g 60g 30g Examples 2-11 Formula 1-4 10g - TAG-2678 / 0.5g 60g 30g Comparative Example 2 (2) 10g - - 60g 30g Comparative Example 3 (2) 10g - TAG-2678 / 0.5g 60g 30g Comparative Example 4 (2) 10g MX-270 / 1g TAG-2678 / 0.5g 60g 30g

[Experimental Example 1] Measurement of solvent resistance of lower layer film

The resist lower layer film compositions prepared in Examples 2-1 to 2-11 and Comparative Examples 2 to 4 were applied to a silicon wafer using a spin coater and then hot-coated using a hot plate, Was heated at 200 DEG C for 1 minute to form a resist lower layer film having a thickness of about 200 nm. The silicon wafer having the lower layer formed thereon was immersed in propylene glycol methyl ether acetate (PGMEA) for 1 minute and then heated at 110 DEG C for 1 minute to remove residual solvent, and the change in thickness of the lower layer film was measured. The results are shown in Table 3 .

division Initial thickness (nm) Thickness after immersion (nm) Thickness variation (nm) Example 2-1 200 199 One Example 2-2 201 199 2 Example 2-3 204 204 0 Examples 2-4 203 202 One Example 2-5 200 198 2 Examples 2-6 200 200 0 Examples 2-7 205 205 0 Examples 2-8 200 198 2 Examples 2-9 203 203 0 Examples 2-10 201 200 One Examples 2-11 200 198 2 Comparative Example 2 200 48 152 Comparative Example 3 201 43 158 Comparative Example 4 205 204 One

As shown in Table 2, unlike the conventional novolac-type resist underlayer film formed according to the present invention, the resist underlayer film formed by the present invention was crosslinked only by heating at 200 ° C without adding an acid catalyst and a crosslinking agent, The loss of the film can be prevented. However, in the case of a general novolak resin, it was found that when both a crosslinking agent and a thermal acid generator were contained (Comparative Example 4), the resin had solvent resistance by a crosslinking reaction but contained only a thermal acid generator (Comparative Example 3) When the thermal acid generator was not included (Comparative Example 2), loss of the resist underlayer film caused by the solvent occurred. Therefore, it can be seen that the polymer according to the present invention is self-crosslinked by a carbonyl group and a hydroxyl group in the polymer without addition of a thermal acid generator (acid catalyst) and a crosslinking agent.

[Experimental Example 2] Measurement of refractive index (n) and optical absorption coefficient (k)

The resist underlayer film compositions prepared in Examples 2-1 to 2-11 and Comparative Example 4 were respectively applied to silicon wafers using a spin coater and the wafers coated with the undercoat film composition were heated to 200 Lt; 0 > C for 1 minute to form a resist underlayer film having a thickness of about 200 nm. The refractive index (n value) and the optical absorption coefficient (k value) of the underlayer film were measured at 248 nm and 193 nm wavelength using a spectroscopic ellipsometer (manufactured by Wollamics Co.), and the results are shown in Table 4.

division Refractive index n
(@ 248 nm) Optical absorption coefficient k
(@ 248 nm) Refractive index n
(@ 193 nm) Optical absorption coefficient k
(@ 193 nm) Example 2-1 1.78 0.71 1.38 0.51 Example 2-2 1.76 0.80 1.40 0.48 Example 2-3 1.86 0.80 1.41 0.46 Examples 2-4 1.84 0.74 1.44 0.49 Example 2-5 1.79 0.79 1.38 0.51 Examples 2-6 1.88 0.81 1.41 0.49 Examples 2-7 1.86 0.80 1.40 0.51 Examples 2-8 1.81 0.79 1.43 0.48 Examples 2-9 1.79 0.79 1.42 0.39 Examples 2-10 1.91 0.78 1.40 0.49 Examples 2-11 1.79 0.81 1.38 0.51 Comparative Example 4 1.92 0.81 1.48 0.70

[Example 3] The resist Bottom layer Measurement of dry etching rate (etching resistance)

After applying the compositions of Examples 2-1 to 2-11 and Comparative Example 4 to a wafer to a thickness of 300 nm, the lower layer films were baked at 240 ° C and 400 ° C for 1 minute, respectively, to form a resist lower layer film . The lower layer film thus formed was etched under CF ₄ / CHF ₃ gas conditions using TCP9400 SE equipment of LAM Research Co., Ltd. The etch rate was calculated from the difference in thickness before and after etching of the resist lower layer film, and the results are shown in Table 5.

division bake temperature (캜) Etching rate (Å / sec) bake temperature (캜) Etching rate (Å / sec) Example 2-1 240 85 400 83 Example 2-2 240 78 400 74 Example 2-3 240 89 400 89 Examples 2-4 240 78 400 75 Example 2-5 240 86 400 85 Examples 2-6 240 88 400 82 Examples 2-7 240 79 400 75 Examples 2-8 240 85 400 84 Examples 2-9 240 91 400 76 Examples 2-10 240 76 400 77 Examples 2-11 240 81 400 78 Comparative Example 4 240 120 400 -

As described above, the resist underlayer film made of the self-crosslinking polymer according to the present invention has improved thermal stability, optical characteristics, and etching resistance as a hard mask. In the case of a resist underlayer film made of a conventional novolac resin, it has thermal stability at a low temperature of 250 DEG C or less, but has a disadvantage in that thermal stability is lowered at a high temperature of about 400 DEG C. However, the self-crosslinking polymer according to the present invention has a good crosslinking ratio and improved thermal stability and etching resistance by containing a hydroxy group and a carbonyl group capable of crosslinking with the repeating unit.

Claims (12)

A polymer comprising a repeating unit represented by the following formula (1)
[Chemical Formula 1]

In the above formula (1), Ar represents benzene

), Naphthalene (

), Anthracene (

), And pyrene (

), R is hydrogen or an alkyl group having 1 to 6 carbon atoms, a is the number of hydroxyl groups (-OH) substituted in Ar and is an integer of 1 to 3, b is selected from the group consisting of Ar Is an integer of 1 to 3. The number of carbonyl groups (-COR) delete delete The polymer according to claim 1, wherein the polymer has a weight average molecular weight of 500 to 1,000,000. A self-crosslinking polymer containing a repeating unit represented by the following formula (1)
[Chemical Formula 1]

(In the above formula (1), Ar represents benzene

), Naphthalene (

), Anthracene (

), And pyrene (

), R is hydrogen or an alkyl group having 1 to 6 carbon atoms, a is the number of hydroxyl groups (-OH) substituted in Ar and is an integer of 1 to 3, and b is selected from the group consisting of Ar (-COR), which is an integer of 1 to 3; And
A resist underlayer film composition comprising an organic solvent. 6. The method of claim 5, wherein the organic solvent is selected from the group consisting of propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monomethyl ether (PGME), cyclohexanone (CH), ethyl lactate (EL), gamma butyrolactone (GBL) And mixtures thereof. ≪ RTI ID = 0.0 > 11. < / RTI > The resist underlayer film composition according to claim 5, wherein the content of the self-crosslinking polymer is 1 to 30% by weight, and the content of the organic solvent is 70 to 99% by weight. Forming a resist underlayer film on an upper surface of a substrate to be etched using a resist underlayer film composition comprising a self-crosslinking polymer and an organic solvent,
[Chemical Formula 1]

(In the above formula (1), Ar represents benzene

), Naphthalene (

), Anthracene (

), And pyrene (

), R is hydrogen or an alkyl group having 1 to 6 carbon atoms, a is the number of hydroxyl groups (-OH) substituted in Ar and is an integer of 1 to 3, and b is selected from the group consisting of Ar (-COR), which is an integer of 1 to 3;
Forming a photoresist layer on the resist underlayer film;
Exposing the photoresist layer to radiation in a predetermined pattern to produce a pattern of radiation exposed areas in the photoresist layer;
Selectively removing the photoresist layer and the resist underlayer film along the pattern to expose the substrate in the form of the pattern; And
And etching the exposed portion of the substrate. The method according to claim 8, wherein forming the resist underlayer film comprises: spin-coating the resist underlayer film composition onto the substrate to a thickness of 500 to 6,000 ANGSTROM; and heating the substrate at a temperature of 180 to 500 DEG C for 50 to 180 seconds And the thickness of the formed resist lower layer film is 40 to 550 nm. The pattern forming method according to claim 8, wherein the removal of the resist underlayer film is performed by dry etching using a mixed gas of CHF ₃ / CF ₄ . 9. The method of claim 8, wherein the organic solvent is selected from the group consisting of propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monomethyl ether (PGME), cyclohexanone (CH), ethyl lactate (EL), gamma butyrolactone (GBL) ≪ / RTI > and mixtures thereof. The pattern forming method according to claim 8, wherein the content of the self-crosslinking polymer is 1 to 30 wt%, and the content of the organic solvent is 70 to 99 wt%.