Polymer with a good heat resistance and storage stability, underlayer film composition containing the polymer and process for forming underlayer film using the composition

Abstract

Provided are a polymer for an underlayer film, used in semiconductor and display manufacturing processes, an underlayer film composition for semiconductor and display manufacturing processes, containing the same, and a method for forming an underlayer film for semiconductor and display manufacturing processes using the underlayer film composition. The polymer according to the present invention is a polymer including a repeating unit represented by the following Chemical Formula 1: ##STR00001##
in Chemical Formula 1, Ar, R.sub.1 to R.sub.6, L, and R and R are the same as those in the detailed description of the present invention.

Claims

1. A polymer comprising a repeating unit represented by the following Chemical Formula 1: ##STR00017## in Chemical Formula 1, Ar is (C6-C20)arylene; R.sub.1 to R.sub.6 are each independently hydrogen, (C1-C20)alkyl, nitrile, or (C6-C20)arylmethyl, at least one of R.sub.1 to R.sub.6 being (C6-C20)arylmethyl; L is a single bond, (C1-C10)alkylene, or (C6-C20)arylene, alkylene and arylene of L being further substituted with one or more substituents selected from (C1-C20)alkyl, (C6-C20)aryl, and (C1-C20)alkoxy; and R and R are each independently hydrogen, (C1-C20)alkyl, (C1-C20)alkoxy, or (C6-C20)aryl, or are linked to each other via (C2-C10)alkenylene to form a fused ring.

2. The polymer of claim 1, wherein the polymer has a weight average molecular weight of 500 to 20,000.

3. The polymer of claim 2, wherein a substitution amount of (C6-C20)aralkyl in the polymer is 10 to 50 mol % based on the weight average molecular weight of the polymer.

4. The polymer of claim 1, wherein Ar is phenylene, naphthylene, or anthrylene; R.sub.1 to R.sub.6 are each independently hydrogen, methyl, nitrile, benzyl, naphthylmethyl, anthrylmethyl, or pyrenylmethyl; L is a single bond, ##STR00018## R.sub.11 and R.sub.12 are each independently methyl, ethyl, propyl, or phenyl; and R and R are each independently hydrogen or are linked to each other via C4alkenylene to form a fused ring.

5. The polymer of claim 1, wherein Ar is phenylene or naphthylene; R.sub.1 to R.sub.6 are each independently hydrogen or benzyl; L is ##STR00019## and R and R are each independently hydrogen or are linked to each other via C4alkenylene to form a fused ring.

6. An underlayer film composition for semiconductor and display manufacturing processes, the underlayer film composition comprising a polymer including a repeating unit represented by the following Chemical Formula 1: ##STR00020## in Chemical Formula 1, Ar is (C6-C20)arylene; R.sub.1 to R.sub.6 are each independently hydrogen, (C1-C20)alkyl, nitrile, or (C6-C20)arylmethyl, at least one of R.sub.1 to R.sub.6 being (C6-C20)arylmethyl; L is a single bond, (C1-C10)alkylene, or (C6-C20)arylene, alkylene and arylene of L being further substituted with one or more substituents selected from (C1-C20)alkyl, (C6-C20)aryl, and (C1-C20)alkoxy; and R and R are each independently hydrogen, (C1-C20)alkyl, (C1-C20)alkoxy, or (C6-C20)aryl, or are linked to each other via (C2-C10)alkenylene to form a fused ring.

7. The underlayer film composition of claim 6, wherein a content of the polymer is 1 to 50 wt % based on total amount of the underlayer film composition.

8. The underlayer film composition of claim 6, further comprising at least one additive selected from crosslinking agents, acid catalysts, acid generators, antifoaming agents, and surfactants.

9. The underlayer film composition of claim 8, wherein the crosslinking agent is at least one selected from compounds represented by Chemical Formulas 2 to 8 below: ##STR00021## in Chemical Formula 4, R.sub.21 and R.sub.22 are each independently hydroxyl, (C1-C3)alkoxy, and R.sub.23 is (C1-C10)alkyl, ##STR00022## in Chemical Formula 6, R.sub.24 to R.sub.27 are each independently hydroxyl or (C1-C3)alkoxy, and R.sub.28 and R.sub.29 are each independently hydrogen, (C1-C10)alkyl, or halo(C1-C10)alkyl, ##STR00023## in Chemical Formula 7, R.sub.30 to R.sub.33 are each independently hydroxyl or (C1-C3)alkoxy, and ##STR00024## in Chemical Formula 8, R.sub.34 to R.sub.39 are each independently hydroxyl or (C1-C3)alkoxy.

10. The underlayer film composition of claim 8, wherein the acid catalyst or the acid generator is at least one selected from compounds represented by Chemical Formulas 9 to 14 below: ##STR00025##

11. A method for forming an underlayer film for semiconductor and display manufacturing processes, the method comprising: applying the underlayer film composition of claim 6 on a wafer; and baking the wafer on which the underlayer film composition is applied.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows mask CD point images after a photolithography process.

(2) FIG. 2 shows CD point images after an etching process.

DETAILED DESCRIPTION OF EMBODIMENTS

(3) Hereinafter, the present invention will be described in detail.

(4) The present invention provides a polymer including a repeating unit represented by the following Chemical Formula 1, as a core material for forming an underlayer film composition having excellent physical properties used in semiconductor and display manufacturing processes.

(5) ##STR00003##

(6) in Chemical Formula 1,

(7) Ar is (C6-C20)arylene;

(8) R.sub.1 to R.sub.6 are each independently hydrogen, (C1-C20)alkyl, nitrile, or (C6-C20)arylmethyl, at least one of R.sub.1 to R.sub.6 being (C6-C20)arylmethyl;

(9) L is a single bond, (C1-C10)alkylene, or (C6-C20)arylene, alkylene and arylene of L being further substituted with one or more substituents selected from (C1-C20)alkyl, (C6-C20)aryl, and (C1-C20)alkoxy; and

(10) R and R are each independently hydrogen, (C1-C20)alkyl, (C1-C20)alkoxy, or (C6-C20)aryl, or may be linked to each other via (C2-C10)alkenylene to form a fused ring.

(11) As disclosed herein, the terms .sup.alkyl.sub. and .sup.alkoxy.sub. include both of the straight chain type and the branched chain type.

(12) As disclosed herein, the term .sup.aryl.sub., which is an organic radical derived from aromatic hydrocarbon by removing one hydrogen atom therefrom, may include a single ring or a fused ring containing, properly 4 to 7 ring atoms, and preferably 5 or 6 ring atoms, and include rings in which two or more aryls are combined through single bond(s). Specific examples of the aryl radical include aromatic groups such as phenyl, naphthyl, biphenyl, indenyl, fluorenyl, phenanthrenyl, anthracenyl, triphenylenyl, pyrenyl, chrysenyl, and naphthacenyl.

(13) The polymer according to the present invention has a weight average molecular weight (Mw) of 500 or more, but in view of improving coating uniformity, hole-filling characteristics, and solubility, it is preferable that the polymer may have a weight average molecule weight of 500 to 20,000.

(14) In the polymer according to the present invention, at least one of R.sub.1 to R.sub.6, preferably, at least two of R.sub.1 to R.sub.6, and more preferably, at least four of R.sub.1 to R.sub.6 are (C6-C20)arylmethyl.

(15) A substitution amount of (C6-C20)aralkyl in the polymer may be 10 to 50 mol % based on the weight average molecular weight of the polymer.

(16) In the polymer according to the present invention, Ar may be phenylene, naphthylene, or anthrylene; R.sub.1 to R.sub.6 may be each independently hydrogen, methyl, nitrile, benzyl, naphthylmethyl, anthrylmethyl, or pyrenylmethyl; L may be a single bond,

(17) ##STR00004##
R.sub.11 and R.sub.12 may be each independently methyl, ethyl, propyl, or phenyl; and R and R may be each independently hydrogen or be linked to each other via C4alkenylene to form a fused ring.

(18) In the polymer according to the present invention, Ar may be phenylene or naphthylene; R.sub.1 to R.sub.6 may be each independently hydrogen or benzyl; L may be

(19) ##STR00005##
and R and R may be each independently hydrogen or be linked to each other via C4alkenylene to form a fused ring.

(20) The polymer according to the present invention has excellent etching resistance, heat stability, and coating uniformity, and simultaneously has optimized etch selectivity and planarization characteristics, such that the polymer may be used as a material of a hard mask in a multilayer semiconductor lithography process. In addition, since the polymer contains a number of arylmethyl groups, in spite of a high content of carbon, the polymer has excellent solubility in an organic solvent, thereby making it possible to improve storage stability.

(21) The present invention is intended to achieve excellent solubility characteristics in a general organic solvent by alkylation of the polymer in order to allow the polymer to have excellent solubility while having a high content of carbon. To this end, in the present invention, a novel heat-resistant polymer having the repeating unit represented by Chemical Formula 1 is prepared, and it was confirmed that at the time of evaluating an underlayer film composition containing the prepared polymer, etching resistance, heat stability, and coating uniformity were excellent. Particularly, it was also confirmed that in spite of a high content of carbon, the polymer had excellent solubility in an organic solvent, such that storage stability and line compatibility in a semiconductor process were significantly improved. An underlayer film composition having excellent physical properties as described above may be prepared using the polymer including the repeating unit represented by Chemical Formula 1.

(22) The polymer according to the present invention may be synthesized by a chemical reaction known in the art, and examples of a preparation process thereof are illustrated in the following Reaction Schemes 1 to 3, but are not limited thereto.

(23) As illustrated in the following Reaction Schemes 1 to 3, the polymer may be prepared by three-step reactions including: 1) preparing polyarylketone ether (P1) using a phenolic compound (S1) and 4,4-dichlorobenzophenone (S2); 2) preparing a polymer having hydroxyl groups by reacting a ketone functional group of the prepared polyarylketone ether (P1) with a phenol derivative; and 3) preparing a polymer (P3) including the repeating unit represented by Chemical Formula 1 by introducing an arylmethyl group into the polymer prepared in step 2) in order to improve solubility characteristics while increasing etching resistance and the content of carbon.

(24) As illustrated in the following Reaction Scheme 1, the polyarylketone ether polymer (P1) may be synthesized using the phenolic compound (S1) having two hydroxyl groups and 4,4-dichlorobenzophenone (S2). A generally used reaction catalyst is a basic compound, and examples thereof may include K.sub.2CO.sub.3, NaOH, KOH, LiOH, and the like. This polymer has low solubility in an organic solvent, such that it is advantageous to use a polymerization regulator (S3). A phenol derivative having one hydroxyl group is used as the polymerization regulator, which may be helpful to etching resistance, and examples of the phenol derivative may include phenol, naphthol, pyrenol, anthracenol, and the like.

(25) ##STR00006##

(26) [In Reaction Scheme 1, R, R, and L are the same as defined in Chemical Formula 1, X is halogen, Z is (C6-C20)aryl, and m is an integer of 1 or more.]

(27) Specific examples of the phenol derivative (S1) having two hydroxyl groups suitable for preparing polyarylketone ether may include phenol derivatives represented by the following structures but are not limited thereto.

(28) ##STR00007##

(29) R(s) are each independently hydrogen, (C1-C20)alkyl, (C1-C20)alkoxy, or (C6-C20)aryl.

(30) In general, it is known that the ketone functional group of polyarylketone ether (P1) has excellent reactivity. In the case in which polyarylketone ether reacts with a phenol derivative (S4) in the presence of a strong acid catalyst, a reaction with the ketone function group occurs at an ortho or para position of the phenols. As a specific example, this reaction is represented by the following Reaction Scheme 2.

(31) ##STR00008##

(32) [In Reaction Scheme 2, R, R, and L are the same as defined in Chemical Formula 1, Ar is (C6-C20)arylene, Z is (C6-C20)aryl, and m is an integer of 1 or more.]

(33) The polymer (P2) obtained in Reaction Scheme 2 may also be used as a material of an underlayer film, but in order to additionally improve etching resistance of the polymer (P2), there is a need to further increase a content of carbon. As a substitution amount of an arylmethyl group such as a benzyl group is increased, a content of carbon in a compound is increased. When the content of carbon is increased, dry etching resistance may be improved, such that there is no need to excessively increase a thickness of a coating film. In order to further increase the content of carbon, the benzyl group may be further introduced, or an arylmethyl derivative having a large aryl group such as a naphthalenemethyl group may be introduced. Solubility as well as etching resistance may be significantly improved by partially introducing the arylmethyl group in order to increase the content of carbon. A reaction for introducing the arylmethyl group may be performed by reacting arylmethylalcohol (S5) or arylmethylmethylether (S6) in the presence of a strong acid. As a specific example, this reaction is represented by the following Reaction Scheme 3.

(34) ##STR00009##

(35) [In Reaction Scheme 3, R, R, and L are the same as defined in Chemical Formula 1, R.sub.1 to R.sub.6 are each independently hydrogen or benzyl, at least one of R.sub.1 to R.sub.6 being benzyl, Ar is (C6-C20)arylene, Z is (C6-C20)aryl, and m is an integer of 1 or more.]

(36) A method for introducing the arylmethyl group such as the benzyl group may be performed in the presence of an acid catalyst. Here, the used acid catalyst is not particularly limited, but the reaction may be performed using (C6-C20)aromatic sulfonic acids such as benzene sulfonic acid, toluene sulfonic acid, naphthalene sulfonic acid, and the like; (C1-C20)alkane sulfonic acids such as methane sulfonic acid, ethane sulfonic acid, propane sulfonic acid, and the like; sulfuric acid; hydrochloric acid; or perfluoro(C1-C20)alkane sulfonic acids such as trifluoromethane sulfonic acid, and the like. Of course, in the case of using arylmethyl halide, a Lewis acid such as trichloroaluminum may also be used. A usage amount of the acid catalyst may be 0.01 wt % to 10 wt % based on a total weight of the reactants. When the usage amount is excessively small, a reaction rate may be decreased, and when the usage amount is excessively large, it is difficult to remove the acid catalyst. In general, a preferable usage amount of the acid catalyst is 0.1 wt % to 5 wt %.

(37) An introduction reaction temperature of the arylmethyl group may be various from 80 C. to 200 C. However, in the case in which the introduction reaction temperature is lower than 110 C., the reaction rate may be excessively decreased, and in the case in which the introduction reaction temperature is higher than 170 C., the reaction rate may be excessively increased, and thus, a color may be excessively changed. A general reaction temperature may be preferably, 110 C. to 170 C., and more preferably, 150 C. or so.

(38) In an introduction reaction of the arylmethyl group, a solvent may not be used, but in general, a halogen compound or an aromatic compound may be used as a solvent in the introduction reaction. However, the solvent used in the introduction reaction is not particularly limited. An example of the halogen compound may include chlorobenzene, dichlorobenzene, and the like, and an example of the aromatic compound may include benzene, toluene, xylene, and the like. After the reaction is terminated, the resultant is precipitated in hexane, a non-polar solvent, filtered, and then vacuum-dried, thereby obtaining a compound.

(39) Further, the present invention provides an underlayer film composition for semiconductor and display manufacturing processes, containing a polymer including a repeating unit represented by Chemical Formula 1.

(40) In the underlayer film composition according to an exemplary embodiment of the present invention, the polymer may have an amount of 1 to 50 wt %, preferably 2 to 30 wt %, and more preferably, 3 to 20 wt %, based on total amount of the underlayer film composition. When the amount of the polymer is less than 1 wt %, an underlayer film having a desired thickness may not be formed, and when the amount of the polymer is more than 50 wt %, the underlayer film may not be uniformly formed.

(41) The underlayer film composition according to an exemplary embodiment of the present invention may form an underlayer film on the substrate such as a silicon wafer, or the like, by spin-coating, spin on carbon (SOC) methods, or the like. The underlayer film composition of the present invention includes the polymer including the repeating unit represented by Chemical Formula 1, thereby having excellent etching resistance, heat stability, coating uniformity, surface planarization, uniformity of pattern edges, and mechanical properties of patterns, such that the underlayer film composition of the present invention is applicable to a hard mask process or a planarization process of a wafer surface.

(42) The underlayer film composition according to an exemplary embodiment of the present invention may further include an organic solvent in addition to the polymer including the repeating unit represented by Chemical Formula 1.

(43) The underlayer film composition according to an exemplary embodiment of the present invention may further include at least one additive selected from crosslinking agents, acid catalysts, acid generators, antifoaming agents, and surfactants.

(44) The polymer including the repeating unit represented by Chemical Formula 1 according to an exemplary embodiment of the present invention may be dissolved in the organic solvent to be coated on the wafer, and then, a crosslinking reaction may be performed at a high temperature by itself. However, the crosslinking reaction is generally performed by adding a crosslinking agent and a catalyst. The composition obtained after the polymer, the crosslinking agent, and the catalyst are dissolved in a solvent, is subjected to a filtration process so that particulate impurities are completely removed.

(45) In the underlayer film composition according to an exemplary embodiment of the present invention, the organic solvent to be usable may be any organic solvent as long as the polymer including the repeating unit represented by Chemical Formula 1, the crosslinking agent, and the acid catalyst are easily dissolved therein. The organic solvent is an organic solvent generally used for a process for manufacturing a semiconductor, and cyclohexanone, 2-heptanone, propylene glycol monomethyl ether, propylene glycol monomethyl acetate, propylene glycol monomethyl ether acetate, gamma-butyrolactone, ethyl lactate, dimethylsulfoxide, dimethylacetamide, N-methylpyrrolidone, or the like, may be used. In addition, the surfactant may be additionally used in order to improve coating uniformity.

(46) In the underlayer film composition according to an exemplary embodiment of the present invention, the crosslinking agent is to induce the crosslinking reaction to better cure the underlayer film. The crosslinking agent usable in the underlayer film composition of the present invention is not limited, but for example, at least one selected from compounds represented by the following Chemical Formulas 2 to 8 may be used.

(47) ##STR00010##

(48) in Chemical Formula 4, R.sub.21 and R.sub.22 are each independently hydroxyl or (C1-C3)alkoxy, and R.sub.23 is (C1-C10)alkyl,

(49) ##STR00011##

(50) in Chemical Formula 6, R.sub.24 to R.sub.27 are each independently hydroxyl or (C1-C3)alkoxy, and R.sub.28 and R.sub.29 are each independently hydrogen, (C1-C10)alkyl, or halo(C1-C10)alkyl,

(51) ##STR00012##

(52) in Chemical Formula 7, R.sub.30 to R.sub.33 are each independently hydroxyl or (C1-C3)alkoxy, and

(53) ##STR00013##

(54) in Chemical Formula 8, R.sub.34 to R.sub.39 are each independently hydroxyl or (C1-C3)alkoxy.

(55) In the underlayer film composition according to an exemplary embodiment of the present invention, a crosslinking agent to be usable may be specifically exemplified by the following structures:

(56) ##STR00014## ##STR00015##

(57) In the underlayer film composition according to an exemplary embodiment of the present invention, an amount of the crosslinking agent may be slightly different depending on the kinds of crosslinking agents, but the amount of the crosslinking agent may be 0.1 to 30 parts by weight based on 100 parts by weight of the polymer including the repeating unit represented by Chemical Formula 1 of the present invention. When the amount of the crosslinking agent is excessively small, crosslinking is not sufficiently performed, such that the crosslinking agent is dissolved in a solvent during a process of coating organic materials at an upper part, and when the amount of the crosslinking agent is excessively large, the crosslinking agent remains after the crosslinking, such that fume largely occurs. The amount of the crosslinking agent may be preferably, 0.1 to 20 parts by weight, and more preferably, 0.5 to 10 parts by weight based on 100 parts by weight of the polymer including the repeating unit represented by Chemical Formula 1.

(58) In the underlayer film composition according to an exemplary embodiment of the present invention, a crosslinking catalyst may be used to increase a crosslinking speed in the crosslinking process. As the crosslinking catalyst, the acid catalyst or the acid generator more advantageously functions as compared to a basic catalyst.

(59) In the composition for preparing the underlayer film composition according to an exemplary embodiment of the present invention, the acid catalyst or the acid generator is added to lower a temperature of the crosslinking reaction of the polymer and improve a crosslinking rate. The acid catalyst or the acid generator usable in the present invention is not limited, but for example, may be at least one selected from compounds represented by Chemical Formulas 9 to 14 below:

(60) ##STR00016##

(61) In the underlayer film composition according to an exemplary embodiment of the present invention, the acid catalyst may be divided into strong acids such as toluene sulfonic acid, and potential acid generators that are decomposed by heat to generate acid. In preparing the composition, it is preferred to use the potential acid generators rather than using the strong acids such as toluene sulfonic acid in view of storage stability. When the strong acids are used, storage stability of the underlayer film composition is decreased. An amount of the acid catalyst or the acid generator may be 0.01 to 10 parts by weight, preferably, 0.05 to 5 parts by weight, and more preferably, 0.1 to 5 parts by weight, based on 100 parts by weight of the polymer including the repeating unit represented by Chemical Formula 1. When the amount thereof is excessively small, a curing speed is slow. Meanwhile, when the amount thereof is excessively large, physical properties of a cured product may be decreased. In particular, when strength of the acid is large or great, fume largely occurs.

(62) The underlayer film composition according to an exemplary embodiment of the present invention may have a film-forming property in which the film is capable of being formed by general spin-coating.

(63) Further, the present invention provides a method for forming an underlayer film using the underlayer film composition. In detail, the method for forming the resist underlayer film according to an exemplary embodiment of the present invention may include: applying the underlayer film composition on a wafer; and baking the wafer on which the underlayer film composition is applied.

(64) The underlayer film may be formed by spin coating the underlayer film composition and baking the wafer at 200 C. to 450 C. for 30 seconds to 3 minutes. The wafer subjected to a baking process is used for a subsequent process. In addition, a coating process, a thickness of the underlayer film, and a baking temperature and time are not limited to the above-mentioned ranges, but may be changed depending on the purpose.

(65) Further, the present invention provides a method for forming patterns using the underlayer film composition. In detail, the method for forming patterns according to an exemplary embodiment of the present invention may include: 1) forming an underlayer film by using the underlayer film composition of the present invention on an upper part of a substrate to be etched such as a silicon wafer on which an aluminum layer is formed, or the like; 2) forming a photoresist layer on the upper part of the underlayer film; 3) exposing the photoresist layer to radiation with predetermined patterns to form patterns of a region exposed to the radiation on the photoresist layer; 4) selectively removing the photoresist layer and the underlayer film along the pattern to expose the substrate in a shape of the patterns; and 5) etching an exposed portion of the substrate.

(66) In the method for forming patterns according to an exemplary embodiment of the present invention, the producing of the patterns on the photoresist layer may be performed by development using conventional alkaline aqueous solutions such as a tetramethylammonium hydroxide (TMAH) developer, etc., and the removing of the underlayer film may be performed by dry etching using CHF.sub.3/CF.sub.4 mixed gas, etc., and the etching of the substrate may be performed by plasma etching using Cl.sub.2 or HBr gas. Here, the etching method, etc., are not limited to the above-described methods, but may be variously changed according to process conditions.

(67) The underlayer film formed according to the present invention is formed by the polymer including the repeating unit represented by Chemical Formula 1, having excellent heat stability, etching resistance, and coating uniformity, such that the underlayer film has excellent heat stability, etching resistance, and coating uniformity. Further, in spite of a high content of carbon in the polymer, the polymer has excellent solubility in an organic solvent, such that the polymer has significantly improved storage stability and line compatibility in a semiconductor process.

(68) Hereinafter, the present invention will be described in detail through Examples and Comparative Examples. However, the following Examples are to illustrate the present invention, and the scope of the present invention is not limited to the following Examples.

Comparative Synthesis Example 1

(69) 35 g of 9,9-bis(hydroxyphenyl)fluorene, 20.1 g of 4,4-difluorobenzophenone, 4.4 g of pyrenol, and 34.5 g of potassium carbonate were dissolved in 240 g of dimethylacetamide in a flask, followed by stirring at 150 C. for 6 hours. When a reaction was terminated, a reaction mixture was cooled to room temperature and slowly added to an excessive amount of 2% aqueous hydrochloric acid solution, thereby precipitating a formed polymer. After the precipitated polymer was filtered, washed with an excessive amount of deionized water, and then filtered, the obtained solid ingredient was dried in a vacuum oven at 90 C. for 24 hours or more, thereby obtaining 42 g of a polymer A [corresponding to Reaction Scheme 1]. The dried polymer was analyzed using gel permeation chromatography (GPC), and as a result, a polystyrene-converted weight average molecular weight of the polymer was 3,200.

Comparative Synthesis Example 2

(70) 20 g of the polymer A obtained in Comparative Synthesis Example 1, 13.4 g of phenol, 1.7 g of toluene sulfonic acid, and 300 g of tetrahydronaphthalene were put into a flask, and a temperature was raised to 190 C., followed by stirring for 24 hours. Water formed during the reaction was removed using a Dean Stark apparatus. After the reaction was completely conducted, the reactant was cooled to room temperature, diluted with 300 g of ethyl acetate, and then, slowly added to an excessive amount of hexane/isopropyl alcohol (7/3) solution, thereby precipitating a polymer. A solid ingredient obtained by filtering the precipitated polymer was dried in a vacuum oven at 90 C. for 24 hours or more, thereby obtaining 15 g of a polymer B [corresponding to Reaction Scheme 2]. The dried polymer was analyzed using gel permeation chromatography (GPC), and as a result, a polystyrene-converted weight average molecular weight of the polymer was 3,680.

Comparative Synthesis Example 3

(71) A reaction was carried out by the same method as in Comparative Synthesis Example 2 except for using 20.6 g of naphthol instead of 13.4 g of phenol, thereby obtaining 17 g of a polymer C [corresponding to Reaction Scheme 2]. The dried polymer was analyzed using gel permeation chromatography (GPC), and as a result, a polystyrene-converted weight average molecular weight of the polymer was 3,740.

Synthesis Example 1

(72) 10 g of the polymer B obtained in Comparative Synthesis Example 2, 1.5 g of benzylmethyl ether, 0.05 g of toluene sulfonic acid, and 60 g of xylene were put into a flask, and stirred at 130 C. for 6 hours. The reactant was cooled to room temperature, diluted by adding 60 g of ethyl acetate, and slowly added to an excessive amount of a hexane solution, thereby precipitating a synthesized polymer. A solid ingredient obtained by filtering the precipitated polymer was dried in a vacuum oven at 90 C. for 24 hours or more, thereby obtaining 8 g of a polymer D [corresponding to Reaction Scheme 3]. The dried polymer was analyzed using gel permeation chromatography (GPC), and as a result, a polystyrene-converted weight average molecular weight of the polymer was 4,100, and a substitution amount of a benzyl group was 20 to 40 mol % based on the weight average molecular weight. The substitution amount of the benzyl group may be measured through an increase in molecular weight by GPC.

Synthesis Example 2

(73) 10 g of the polymer B obtained in Comparative Synthesis Example 2, 1 g of naphthalenemethanol, 0.05 g of toluene sulfonic acid, and 60 g of xylene were put into a flask, and stirred at 130 C. for 6 hours. The reactant was cooled to room temperature, diluted by adding 60 g of ethyl acetate, and slowly added to an excessive amount of a hexane solution, thereby precipitating a synthesized polymer. A solid ingredient obtained by filtering the precipitated polymer was dried in a vacuum oven at 90 C. for 24 hours or more, thereby obtaining 7.8 g of a polymer E [corresponding to Reaction Scheme 3]. The dried polymer was analyzed using gel permeation chromatography (GPC), and as a result, a polystyrene-converted weight average molecular weight of the polymer was 4,300, and a substitution amount of a benzyl group was 20 to 35 mol % based on the weight average molecular weight. The substitution amount of the benzyl group may be measured through an increase in molecular weight by GPC.

Examples 1 to 4 and Comparative Examples 1 to 3

(74) Underlayer film compositions were prepared according to compositions shown in the following Table 1. As a resin, one selected from polymers A to E was used.

(75) As a crosslinking agent, 1,3,4,6-tetrakis(methoxymethyl)glycoluril represented by Chemical Formula 2 was used, and as an acid catalyst, pyridinium p-toluenesulfonate represented by Chemical Formula 10 was used. As a solvent, propylene glycol monomethyl ether acetate (PGMEA) was used.

(76) The resin, the crosslinking agent, and the acid catalyst were dissolved in 50 g of the solvent according to the ingredients and contents shown in Table 1, and particulate impurities were completely removed using a filter (0.05 m).

(77) TABLE-US-00001 TABLE 1 Crosslinking Acid Resin Agent Catalyst Example 1 5 g (D in Synthesis Example 1) Example 2 5 g (E in Synthesis 0.1 g 0.05 g Example 2) Example 3 5 g (D in Synthesis 0.5 g 0.05 g Example 1) Example 4 5 g (D in Synthesis 0.2 g 0.08 g Example 1) Comparative 5 g (A in Comparative Example 1 Synthesis Example 1) Comparative 5 g (B in Comparative Example 2 Synthesis Example 2) Comparative 5 g (C in Comparative Example 3 Synthesis Example 3)

Experimental Example 1

Formation of Underlayer Film

(78) The underlayer film compositions in Examples 1 to 4 and Comparative Examples 1 to 3 were spin coated on wafers, and baked at 250 C. for 60 seconds. Thereafter, surfaces of the baked wafers were observed by the naked eyes or using scanning electron microscope (SEM), or the like. Cross-linking degrees, surface uniformity, and the presence or absence of cracks were evaluated (: excellent, : good, : fair, and X: poor) through surface observation, and the results were shown in the following Table 2.

(79) Further, at the time of evaluating solubility, when each of the underlayer film compositions was dissolved in propylene glycol methyl ether acetate (PMA), propylene glycol methyl ether (PM), ethyl 3-ethoxypropionate (EEP), or a mixed solvent of PMA/PM (3/7(v/v)) at a content of 20 wt %, transparency of each of the solutions was evaluated (: excellent, : good, : fair, and X: poor), and the results were shown in the following Table 2.

(80) TABLE-US-00002 TABLE 2 Cross- Presence or linking Surface Absence of Degree Uniformity Cracks Solubility Example 1 Example 2 Example 3 Example 4 Comparative X Example 1 Comparative Example 2 Comparative Example 3

(81) As shown in Table 2, it was confirmed that in Comparative Example 1 in which a resin made of pure polyarylketone ether was used, a large amount of fume was generated, such that cracks were observed, and surface uniformity was deteriorated. In addition, it may be appreciated that solubility was significantly deteriorated as compared to other Examples and Comparative Examples.

(82) It may be appreciated that in Examples 1 to 4 in which the novel polymer according to the present invention was used, surface uniformity was more excellent. It may be appreciated that in Examples 1 and 2, surface uniformity was relatively improved as compared to Comparative Examples 2 and in which alkylation was not performed. In Comparative Example 1, surface uniformity was deteriorated due to poor solubility.

Experimental Example 2

Formation of Patterns

(83) After forming an underlayer film having a thickness of 130 nm by spin-coating the underlayer film composition of Example 4 on a wafer and baking the wafer at 250 C. for 60 seconds, an ArF photoresist was coated on the underlayer film, and baked at 110 C. for 60 seconds, thereby forming a photoresist layer having a thickness of 90 nm. The photoresist layer was exposed using an ArF excimer laser scanner (NSR-S305B manufactured by Nikon Corp., numerical aperture (NA)=0.68, 0=0.85), and baked at 90 C. for 90 seconds. Then, development was performed thereon using a TMAH developer (2.38 w % aqueous solution) for 60 seconds, thereby obtaining photoresist patterns [FIG. 1]. The obtained photoresist patterns were used as an etching mask, and the underlayer film was dry etched using CHF.sub.3/CF.sub.4 mixed gas and then, dry etched using BCl.sub.3/Cl.sub.2 mixed gas again. Finally, all of the remaining organic materials were removed using O.sub.2 gas.

(84) Cross-sections of the pattern obtained using field emission-scanning electron microscope (FE-SEM) after a photolithography process and an etching process using the underlayer film composition of Example 4 were illustrated in FIGS. 1 and 2, respectively. As illustrated in FIGS. 1 and 2, it may be appreciated that the underlayer film composition of Example 4 was excellent in view of pattern fidelity, CD uniformity, surface roughness, and the like.

Experimental Example 3

Acceleration Test for Storage Stability

(85) The polymers (each 20 wt %) prepared in Synthesis Examples 1 and 2 according to the present invention were dissolved in various organic solvents in the same manner in the test for solubility in Experimental Example 1, respectively, and kept at 50 C. After 3 weeks, transparency of the solutions was observed, thereby performing an acceleration test for storage stability.

(86) Used organic solvent: ethyl acetate (E/L), Cyclohexanone (C/H), N-methylpyrrolidone (NMP), methyl 2-hydroxyisobutyrate (HBM), propylene glycol methyl ether acetate (PMA), propylene glycol methyl ether (PM), ethyl 3-ethoxypropionate (EEP), or a PMA/PM (3/7(v/v)) mixed solvent.

(87) It was confirmed that all of the polymers according to the present invention had excellent solubility in general organic solvents. In addition, as a result of the acceleration test for storage stability at 50 C., even after 3 weeks, it was confirmed that the solutions were stable without precipitation, such that the polymers had sufficiently improved storage stability.

(88) Since the novel polymer according to the present invention simultaneously may have the optimized etch selectivity and planarization characteristics, the underlayer film composition containing the same may be used to form the hard mask (spin on carbon (SOC) hard mask) by spin coating in the multilayer semiconductor lithography process.

(89) The underlayer film composition according to the present invention has excellent etching resistance, heat stability, and coating uniformity due to the novel polymer, and particularly, the underlayer film composition has excellent solubility in the organic solvent in spite of a high content of carbon, thereby making it possible to significantly improve storage stability and line compatibility in the semiconductor process.

(90) Further, even in the case of forming the underlayer film using the underlayer film composition according to the present invention and then performing the photolithography process and the etching process thereon, it is possible to obtain excellent pattern fidelity, critical dimension (CD) uniformity, surface roughness, and the like.