JP4706851B2 - Lithographic underlayer film forming composition comprising cyclodextrin containing inclusion molecules - Google Patents

Description

  The present invention relates to a composition for forming an underlayer film for lithography containing a cyclodextrin containing an inclusion molecule, an underlayer film obtained thereby, a method for forming a resist pattern using the underlayer film, and a semiconductor device using the same Related to the method.

  Conventionally, in the manufacture of semiconductor devices, fine processing by lithography using a photoresist has been performed. The microfabrication is obtained by forming a thin film of photoresist on a semiconductor substrate such as a silicon wafer substrate, irradiating it with an actinic ray such as ultraviolet rays through a mask pattern on which a semiconductor device pattern is drawn, and developing it. This is a processing method in which fine irregularities corresponding to the pattern are formed on the substrate surface by etching the substrate using the photoresist pattern thus formed as a protective film. However, in recent years, the degree of integration of semiconductor devices has increased, and the actinic rays used tend to be shortened from KrF excimer laser (248 nm) to ArF excimer laser (193 nm). Accordingly, the influence of diffuse reflection of active rays from the substrate and standing waves has become a serious problem. Therefore, in order to solve this problem, a method for providing an antireflection film between the photoresist and the substrate has been widely studied. As such an antireflection film, many studies have been made on an organic antireflection film composed of a light-absorbing substance and a polymer compound because of its ease of use (see Patent Documents 1 and 2).

  The properties required for organic anti-reflection coatings include high absorbance to light and radiation, no intermixing with photoresist (insoluble in photoresist solvent), anti-reflection during heating and baking In some cases, the low molecular weight material does not diffuse from the film to the upper photoresist, and the dry etching rate is higher than that of the photoresist.

  In recent years, studies have been made to use copper as a wiring material in order to solve the problem of wiring delay that has become apparent with the progress of pattern rule miniaturization of semiconductor devices. At the same time, a dual damascene process is being studied as a method for forming wiring on a semiconductor substrate. In the dual damascene process, a via hole is formed, and an antireflection film is formed on a substrate having a large aspect ratio. For this reason, antireflection films used in this process are required to have a filling characteristic that can fill holes without gaps, and a flattening characteristic that allows a flat film to be formed on the substrate surface. Yes.

  However, it is difficult to apply a material for an organic antireflection film to a semiconductor substrate having a large aspect ratio, and in recent years, materials with emphasis on embedding characteristics and planarization characteristics have been developed (for example, (See Patent Document 3, Patent Document 4, Patent Document 5, and Patent Document 6).

  In addition, in the manufacture of devices such as semiconductors, a barrier layer formed from a composition containing a crosslinkable polymer or the like is provided between the dielectric layer and the photoresist layer in order to reduce the poisoning effect of the photoresist layer by the dielectric layer. The method of providing in is disclosed (patent document 7).

  As described above, in the manufacture of semiconductor devices in recent years, in order to achieve various effects including an antireflection effect, a composition containing an organic compound between the semiconductor substrate and the photoresist layer, that is, as a lower layer of the photoresist layer. Organic underlayer films formed from materials have been arranged. In order to satisfy the required performance of the underlayer film, which has been increasing in diversity, there is always a need to develop a new composition for the underlayer film.

  By the way, a composition containing a certain kind of sugar compound is known. For example, an antireflection film-forming composition containing a cellulose compound is known (see, for example, Patent Document 8 and Patent Document 9). In addition, a pattern forming method using a water-soluble antireflection organic film mainly composed of a polysaccharide, bullulan, is disclosed (see, for example, Patent Document 10). Moreover, it describes about the antireflection film material containing the polysaccharide which has a silyl substituent (for example, refer patent document 11).

It is described that a compound obtained by esterifying 50% of the hydroxyl group of dextrin was used in a composition for forming a lower layer film for lithography (Patent Document 12).
US Pat. No. 5,919,599 US Pat. No. 5,693,691 etc. JP 2000-294504 A JP 2002-47430 A JP 2002-190519 A International Publication No. 02/05035 Pamphlet In JP 2002-128847 A WO99 / 56178 pamphlet International Publication No. 02/071155 Pamphlet JP-A-60-223121 JP 2002-107938 A International Publication No. 05/043248 Pamphlet

  An object of the present invention is to provide an underlayer film forming composition that can be used in the manufacture of a semiconductor device. An underlayer film for lithography having a higher dry etching rate than that of a photoresist without causing intermixing with the photoresist applied and formed on the upper layer, and an underlayer film forming composition for forming the underlayer film Is to provide.

  Another object of the present invention is to provide an underlayer film forming composition for lithography for forming an underlayer film having excellent hole filling properties on a semiconductor substrate.

  Another object of the present invention is to provide a lower antireflection film for reducing reflection of exposure light from a substrate formed on a semiconductor substrate from a substrate in a lithography process for manufacturing a semiconductor device. A lower layer film for lithography that can be used as a planarizing film for forming a film, a film for preventing contamination of a photoresist by a substance generated from a semiconductor substrate during heating and firing, and a lower film forming composition for forming the lower layer film It is to be. And it is providing the formation method of the lower layer film for lithography using this lower layer film formation composition, and the formation method of a photoresist pattern.

The present invention, as a first aspect, an underlayer film forming composition for lithography comprising cyclodextrin containing inclusion molecules,
As a second aspect, the underlayer film forming composition for lithography according to the first aspect, wherein the inclusion molecule is a halogen molecule, an acid molecule, a base molecule, an acid generator, or a base generator,
As a third aspect, the cyclodextrin is an α-type, β-type, γ-type, or δ-type cyclodextrin, the composition for forming an underlayer film for lithography according to the first aspect or the second aspect,
As a fourth aspect, the cyclodextrin has a hydroxyl group contained in the molecule represented by the formula (1):

(In the formula (1), R ₁ has 1 to 1 carbon atoms which may be substituted with a group selected from the group consisting of a halogen group, an alkoxy group having 1 to 6 carbon atoms, a phenyl group, a cyano group and a nitro group. 10 alkyl or aromatic groups, or formula (2):

In the formula (2), R ₂ is substituted with a group selected from the group consisting of a halogen group, an alkoxy group having 1 to 6 carbon atoms, a phenyl group, a cyano group, and a nitro group. Or an alkyl group having 1 to 10 carbon atoms or an aromatic group. The composition for forming an underlayer film for lithography according to any one of the first to third aspects, which is a chemically modified cyclodextrin substituted with an organic group represented by:
As a fifth aspect, the cyclodextrin includes any one of the first to fourth aspects including a chemically modified cyclodextrin in which the hydroxyl group contained in the molecule is replaced with an organic group of the formula (1) at a ratio of 10 to 90%. The composition for forming an underlayer film for lithography according to any one of the above,
As a sixth aspect, the composition for forming a lower layer film for lithography according to any one of the first aspect to the fifth aspect, further containing a polymer and a solvent,
As a seventh aspect, the composition for forming a lower layer film for lithography according to any one of the first aspect to the sixth aspect, which further contains a crosslinkable compound and a crosslinking catalyst, and as the eighth aspect, the first aspect to the seventh A step of applying the underlayer film forming composition for lithography according to any one of the aspects onto a semiconductor substrate and baking to form a lower layer film, a step of forming a photoresist layer on the lower layer film, and the lower layer film And a step of exposing the semiconductor substrate coated with the photoresist layer, and a step of developing the photoresist layer after the exposure.

With the composition for forming a lower layer film for lithography of the present invention, a high filling property inside the hole can be achieved without generating voids (gap).

  Moreover, the unevenness | corrugation of the board | substrate which has a hole can be filled and planarized with the lower-layer-film formation composition for lithography of this invention. Therefore, the uniformity of the film thickness of a photoresist or the like applied and formed thereon can be increased. Therefore, a good photoresist pattern shape can be formed even in a process using a substrate having holes.

The underlayer film forming composition for lithography of the present invention can provide an underlayer film having a higher dry etching rate than that of a photoresist and causing no intermixing with the photoresist.
The underlayer film of the present invention can be used as an antireflection film, a planarization film, a photoresist contamination prevention film, and the like. This makes it possible to easily and accurately form a photoresist pattern in a lithography process for manufacturing a semiconductor device.

  The underlayer film formed from the underlayer film forming composition of the present invention contains a cyclodextrin compound having an inclusion action. Since cyclodextrin contains halogen molecules (particularly iodine molecules and iodine-containing compounds) as inclusion molecules, the etching rate is high. Since cyclodextrin contains an acid molecule, a base molecule, a thermal acid generator, or a thermal base generator as an inclusion molecule, the lower layer film-forming composition containing cyclodextrin containing the inclusion molecule is heated to form a lower layer. In the process of forming the film, the acid component and the base component included in the cyclodextrin are released into the lower layer film to promote the curing of the thermosetting film.

  In addition, since cyclodextrin includes a photoacid generator and a photobase generator as an inclusion molecule, by heating the underlayer film-forming composition containing cyclodextrin containing the inclusion molecule, The photobase generator is released into the lower layer film, and an acid or base can be supplied from the lower layer film to the photoresist film during exposure of the upper photoresist film, thereby improving the profile of the photoresist film. In addition, photoacid generators and photobase generators released from cyclodextrins generate acids and bases during exposure of photoresists, which can be converted into alkali-soluble resins that can be removed with a developer. Become.

  In addition, the lower layer film containing cyclodextrin can adsorb low molecular weight compounds derived from the amine component contained in the semiconductor substrate and generated during firing, thereby causing resist poisoning phenomenon (damage to the protective group of the photoresist). Phenomenon).

  In the present invention, since cyclodextrin contains acid molecules, base molecules, acid generators, base generators, etc. as inclusion molecules, the composition for forming an underlayer film for lithography contains these components, polymer components, Since the crosslinking agent component does not come into direct contact, the storage stability of the underlayer film forming composition for lithography is improved.

  The composition for forming a lower layer film for lithography of the present invention contains a cyclodextrin compound containing an inclusion molecule. And a polymer compound, a crosslinkable compound, a crosslinking catalyst, surfactant, a solvent, etc. can be included.

  The ratio of the solid content in the underlayer film forming composition of the present invention is not particularly limited as long as each component is uniformly dissolved in the solvent, but is, for example, 0.5 to 50% by mass, or 1 to 30 % By mass, or 1-25% by mass, or 1-15% by mass. Here, the solid content is obtained by removing the solvent from all the components of the composition for forming a lower layer film for lithography.

  Cyclodextrins are also called cyclic oligosaccharides, and α-D-glucopyranose groups are cyclically linked by α-1,4-glycosidic bonds, and α-type (having 6 pyranose groups depending on the number of pyranose groups. Cyclohexaamylose structure, porosity = 0.45-0.60 nm), β-type (having seven pyranose groups. Cycloheptaamylose, porosity = 0.70-0.80 nm), γ-type ( There are 8 pyranose groups: cyclooctaamylose, porosity = 0.85 to 1.0 nm), and δ type (having 9 pyranose groups. Cyclononaamylose).

  Among the glucose units, hydroxyl groups are present at the 2nd, 3rd and 6th positions, the hydroxyl group present at the 6th position is a primary hydroxyl group, and the hydroxyl groups present at the 2nd and 3rd positions are secondary.

  The cyclodextrins used in the present invention are α-type, β-type, γ-type, and δ-type cyclodextrins (case 1), and their hydroxyl groups are organic groups represented by formula (1). There are cases where a chemically modified cyclodextrin is used (case 2) and a mixture of the former and the latter (case 3). In the present invention, these cyclodextrin compounds can be used.

Case 1 is the case where the cyclodextrin used in the composition for forming an underlayer film for lithography of the present invention uses a cyclodextrin whose hydroxyl group contained in the molecule is chemically unmodified.
Case 2 is the case where a cyclodextrin in which the hydroxyl group contained in the molecule is chemically modified is used, and 10 to 90% of the total hydroxyl groups at the 2nd, 3rd and 6th positions are represented by the formula (1). It is chemically modified with an organic group.
The hydroxyl group of cyclodextrin is substituted with a group selected from the group consisting of the formula (1) [wherein R ₁ is a halogen group, an alkoxy group having 1 to 6 carbon atoms, a phenyl group, a cyano group, or a nitro group. Represents an optionally substituted alkyl group or aromatic group having 1 to 10 carbon atoms, or a group represented by formula (2), wherein R ₂ is a halogen group, having 1 to 6 carbon atoms. An alkyl group having 1 to 10 carbon atoms or an aromatic group which may be substituted with a group selected from the group consisting of an alkoxy group, a phenyl group, a cyano group and a nitro group. A chemically modified cyclodextrin substituted with an organic group represented by the following formula can be used.
Examples of the alkyl group having 1 to 10 carbon atoms in the above formula (1) include a methyl group, an ethyl group, an isopropyl group, a normal pentyl group, a cyclohexyl group, and a normal octyl group. Examples of the alkoxy group having 1 to 6 carbon atoms include a methoxy group, an ethoxy group, an isopropyloxy group, and a cyclohexyloxy group. The halogen group includes a chloro group, a fluoro group, a bromo group, and an iodo group. Examples of the aromatic group include carbocyclic aromatic groups such as benzene ring, naphthalene ring and anthracene ring, and nitrogen-containing aromatic groups such as pyridine ring, pyrimidine ring, triazine ring, thiazole ring and imidazole ring.

The case where R ₁ in Formula (1) is the alkyl group having 1 to 10 carbon atoms or the aromatic group is a case where the hydroxyl group of cyclodextrin is an ether group. The case where R ₁ is a group represented by the formula (2) is a case where the hydroxyl group of cyclodextrin is an ester group.

  Cyclodextrin is a compound having a large number of hydroxyl groups and has low solubility in a solvent. Therefore, it is difficult to use for the lower layer film formation composition using a solvent. Therefore, in the composition for forming a lower layer film for lithography according to the present invention, a cyclodextrin compound having a hydroxyl group as an ether group or an ester group and improved solubility in a solvent is used. The cyclodextrin compound used in the composition for forming a lower layer film for lithography of the present invention is 10% or more of the total number of hydroxyl groups contained in the cyclodextrin, for example, 10% to 90%, or 20% to 80%, or 30% to 60% is a cyclodextrin compound having a group represented by the formula (1), that is, an ether group or an ester group. In the cyclodextrin compound, the group represented by the formula (1) may be an ether group alone, an ester group alone, or an ether group and an ester group may be mixed. May be.

Specific examples of R ₁ in the formula (1) include methyl group, ethyl group, isopropyl group, cyclohexyl group, normal octyl group, cyanomethyl group, methoxymethyl group, benzyl group, chloropropyl group, phenyl group, naphthyl group, Anthryl group, fluorophenyl group, pyridyl group, 2-pyrimidinyl group, triazinyl group, 4,6-dimethoxytriazin-2-yl group, 2,4-dinitrophenyl group and 2-chlorotriazin-4-yl group .

Specific examples of R ₂ in the formula (2) include methyl group, ethyl group, isopropyl group, cyclohexyl group, normal octyl group, phenylethyl group, trifluoromethyl group, chloromethyl group, cyanomethyl group, phenyl group, naphthyl. Group, anthryl group, fluorophenyl group, ethoxymethyl group, bromophenyl group, chloronaphthyl group, nitrophenyl group, pyridyl group, 2-pyrimidinyl group, triazinyl group, benzyl group, 2-thiazolyl group and 2-benzoxazolyl Group.

The chemically modified cyclodextrin in which 10 to 90% of the hydroxyl groups of the cyclodextrin used in the present invention are replaced by the organic group of the formula (1) can be obtained by the following method.
For example, by reacting a cyclodextrin with an alkyl compound having a leaving group or an aromatic compound in a suitable solvent in the presence of a base, R ₁ in formula (1) is an alkyl having 1 to 10 carbon atoms. A cyclodextrin compound which is a group or the aromatic group can be obtained. Examples of the alkyl compound having a leaving group include methyl iodide, ethyl iodide, 2-iodopropane, 1-bromopentane, benzyl bromide, methoxymethyl chloride, bromoacetonitrile, 1-bromooctane and the like. Examples of the aromatic compound having a leaving group include 2-chlorotriazine, 2-chloro-4,6-dimethoxytriazine, 2-chloropyrimidine, and 2,4-dinitrochlorobenzene. Examples of the base include sodium hydroxide, sodium carbonate, sodium acetate, potassium carbonate, sodium methoxide, pyridine, 4- (N, N-dimethylamino) pyridine, and triethylamine.

Further, for example, by reacting cyclodextrin with an aromatic compound having a phenolic hydroxyl group in a suitable solvent in the presence of triphenylphosphine and diethyl azodicarboxylate (Mitsunobu reaction), R in formula (1) _A cyclodextrin compound in which ₁ is the aromatic group can be obtained. Examples of the aromatic compound having a phenolic hydroxyl group include phenol, paracresol, 1-naphthol, 2-naphthol, 2-hydroxyanthracene, 9-hydroxyanthracene, 4-hydroxypyridine, and 3-hydroxypyridine.

The cyclodextrin compound in which R ₁ in the formula (1) is a group represented by the formula (2) includes cyclodextrin and acid chloride, acid bromide, carbonylimidazole compound, carboxylic acid active ester compound, and acid anhydride. It can be obtained by converting a hydroxyl group into an ester group by reaction with the like. For example, conversion of the hydroxyl group of cyclodextrin to an acetyloxy group can be performed by reacting cyclodextrin with acetyl chloride or acetic anhydride under conditions using a base such as pyridine.

  For conversion of hydroxyl group to ester group, acetic acid, propionic acid, butyric acid, cyclohexanecarboxylic acid, chloroacetic acid, trifluoroacetic acid, cyanoacetic acid, ethoxyacetic acid, isobutyric acid, benzoic acid, bromobenzoic acid, hydroxybenzoic acid, iodobenzoic acid Acid chlorides derived from carboxylic acid compounds such as acids, nitrobenzoic acid, methylbenzoic acid, ethoxybenzoic acid, tert-butoxybenzoic acid, naphthalenecarboxylic acid, chloronaphthalenecarboxylic acid, hydroxynaphthalenecarboxylic acid, and anthracenecarboxylic acid, Acid bromides, carbonyl imidazole compounds, and carboxylic acid active ester compounds can be used. Moreover, the anhydride of these carboxylic acid compounds can also be used. Furthermore, conversion of the hydroxyl group of cyclodextrin to an ester group can also be carried out by reacting the above carboxylic acid compound with cyclodextrin in the presence of a condensing agent such as dicyclohexylcarbodiimide.

  The ratio of the conversion of the hydroxyl group of cyclodextrin to the ester group can be adjusted by changing the equivalents of the acid chloride, acid bromide, carbonylimidazole compound, carboxylic acid active ester compound and acid anhydride to be used.

  The amount of hydroxyl group remaining in the cyclodextrin compound can be measured by a general hydroxyl value measurement method. For example, the residual amount of hydroxyl groups in a cyclodextrin compound can be measured by acetylating a cyclodextrin compound with acetic anhydride in the presence of pyridine, adding water to convert excess acetic anhydride into acetic acid, and quantifying the acetic acid with an alkali. it can.

  The cyclodextrin and the cyclodextrin obtained by chemically modifying the cyclodextrin have properties that the inside of the cyclodextrin structure such as a crown is hydrophobic and the outside is hydrophilic. Therefore, in order to dissolve these compounds in a highly hydrophobic organic solvent, an organic group having affinity for the organic solvent by chemical modification of a part of the hydrophilic structure (hydroxyl group) existing outside the cyclodextrin Need to be converted. Therefore, a chemically modified cyclodextrin having a structure in which 10 to 90% of the hydroxyl groups of the cyclodextrin are replaced with the organic group of the formula (1) can be used. In the case of using a highly hydrophilic organic solvent, a cyclodextrin having an unmodified hydroxyl group is used, or a chemically modified cyclodextrin having a low rate of replacement of the hydroxyl group with an organic group of the formula (1) (for example, about 10 to 30%). Dextrin can be used.

  The cyclodextrin containing an inclusion molecule used in the present invention is a host-guest compound in which a molecule is included inside the cyclodextrin structure such as a crown.

  The inclusion molecule is contained in an amount of 1 to 80% by mass, preferably 1 to 50% by mass, and more preferably 1 to 30% by mass with respect to the cyclodextrin.

  The inclusion molecule and the cyclodextrin are basically complexed at a molar ratio of 1: 1, but when the inclusion molecule is bulky, the inclusion molecule and the cyclodextrin have a molar ratio of 1: 2. Complexes can also be formed in proportions. This is a barrel-shaped complex in which the cyclodextrin has the bottom of the chair-type conformation (secondary hydroxyl group side) facing the inclusion molecule and the inclusion molecule is sandwiched from both sides. Depending on the shape of the inclusion molecule, the inclusion molecule and the cyclodextrin can form 1: 3 and 1: 4 complexes in molar ratio. Therefore, the ratio of inclusion molecules in cyclodextrin is expressed by the ratio of inclusion molecules in all cyclodextrins.

  For example, an iodine inclusion complex of β-cyclodextrin (β-cyclodextrin iodine complex) having an effective iodine amount of 5 to 20% by mass is commercially available. In addition, methylated β-cyclodextrin iodine inclusion complex (Methyl-β-cyclodextrin iodine complex, in which a part of hydroxyl group is converted to methoxy group) is available in 3-15% effective iodine amount on the market Has been.

  Examples of the inclusion molecules incorporated inside the cyclodextrin include halogen molecules, acid molecules, base molecules, acid generators, and base generators.

  The halogen molecule is a fluorine molecule, a chlorine molecule, a bromine molecule, or an iodine molecule, and an iodine molecule is particularly preferable.

  Acid molecules include hydrogen chloride, hydrogen bromide, hydrogen iodide, hydrogen sulfide, sulfuric acid, phosphoric acid, nitric acid, oxalic acid, benzoic acid, p-toluenesulfonic acid, pyridinium-p-toluenesulfonic acid, salicylic acid, sulfosalicylic acid, Examples include 4-chlorobenzenesulfonic acid, 4-hydroxybenzenesulfonic acid, benzenedisulfonic acid, 1-naphthalenesulfonic acid, and pyridinium-1-naphthalenesulfonic acid, and hydrogen chloride and p-toluenesulfonic acid are particularly preferable.

  Examples of base molecules include ammonia and amines. Examples of amines include aliphatic primary amines such as methylamine, ethylamine, propylamine, isopropylamine, butylamine, and octylamine, dimethylamine, diethylamine, methylethylamine, and diisopropylamine. Aliphatic secondary amine, triethylamine, triethylamine, methyldiethylamine, tributylamine and other aliphatic tertiary amines, allylamine, diallylamine and other aliphatic unsaturated amines, cyclopropylamine, cyclohexylamine and other alicyclic amines, aniline, benzyl Aromatic amines such as amine, diphenylamine, triphenylamine and naphthylamine can be mentioned, and ammonia, methylamine and the like are particularly preferable.

  Examples of the photoacid generator include onium salt compounds, sulfonimide compounds, and disulfonyldiazomethane compounds.

  Examples of onium salt compounds include diphenyliodonium hexafluorophosphate, diphenyliodonium trifluoromethanesulfonate, diphenyliodonium nonafluoro-normal butanesulfonate, diphenyliodonium perfluoro-normaloctanesulfonate, diphenyliodonium camphorsulfonate, bis (4-tert-butylphenyl) Iodonium salt compounds such as iodonium camphorsulfonate and bis (4-tert-butylphenyl) iodonium trifluoromethanesulfonate, and triphenylsulfonium hexafluoroantimonate, triphenylsulfonium nonafluoro-normal butanesulfonate, triphenylsulfonium camphorsulfonate and triphenyl Sulfonium salt compounds such as sulfonium trifluoromethanesulfonate, and the like.

  Examples of the sulfonimide compound include N- (trifluoromethanesulfonyloxy) succinimide, N- (nonafluoro-normalbutanesulfonyloxy) succinimide, N- (camphorsulfonyloxy) succinimide, and N- (trifluoromethanesulfonyloxy) naphthalimide. Can be mentioned.

  Examples of the disulfonyldiazomethane compound include bis (trifluoromethylsulfonyl) diazomethane, bis (cyclohexylsulfonyl) diazomethane, bis (phenylsulfonyl) diazomethane, bis (p-toluenesulfonyl) diazomethane, and bis (2,4-dimethylbenzenesulfonyl). ) Diazomethane, methylsulfonyl-p-toluenesulfonyldiazomethane, and the like.

  Examples of the photobase generator include bis [[(2-nitrobenzyl) oxy] carbonylhexane-1,6-diamine], nitrobenzylcyclohexyl carbamate, di (methoxybenzyl) hexamethylene dicarbamate, and the like.

A method for producing a cyclodextrin containing a inclusion molecule and a chemically modified cyclodextrin by incorporating inclusion molecules inside the three-dimensional structure of the cyclodextrin and the chemically modified cyclodextrin is performed by a known method. For example, if the inclusion molecule is a gaseous molecule, it can be obtained by bringing a gaseous molecule (for example, halogen molecule, ammonia, hydrogen chloride) into contact with the cyclodextrin in a solid-gas state. When the inclusion molecule is a gaseous molecule, it is obtained by blowing gaseous molecules (for example, halogen molecules, ammonia, and hydrogen chloride) into the solvent in which the cyclodextrin is dissolved, and contacting with liquid-gas.
Further, if the inclusion molecule is soluble in the organic solvent, the cyclodextrin can be dissolved in the organic solvent in which the inclusion molecule is dissolved, and inclusion can be performed in a liquid-liquid manner.

  The underlayer film forming composition for lithography of the present invention contains a crosslinkable compound. As the crosslinkable compound, a compound having two or more substituents capable of reacting with a hydroxyl group in the cyclodextrin, for example, 2 to 6, or 2 to 4, is used.

  When such a crosslinkable compound is used, a reaction occurs between the cyclodextrin compound and the crosslinkable compound during firing for forming the lower layer film, and the formed lower layer film has a crosslinked structure. Become. As a result, the lower layer film becomes strong and has low solubility in the organic solvent used in the photoresist solution applied to the upper layer. Examples of the substituent capable of reacting with a hydroxyl group in the cyclodextrin compound include an isocyanate group, an epoxy group, a hydroxymethylamino group, and an alkoxymethylamino group. Therefore, a compound having two or more of these substituents, for example, 2 to 6, or 2 to 4, can be used as the crosslinkable compound.

  Examples of the crosslinkable compound of the present invention include nitrogen-containing compounds having a nitrogen atom substituted with a hydroxymethyl group or an alkoxymethyl group. It is a nitrogen-containing compound having a nitrogen atom substituted with a group such as a hydroxymethyl group, a methoxymethyl group, an ethoxymethyl group, a butoxymethyl group, and a hexyloxymethyl group.

  Specifically, hexamethoxymethylmelamine, tetramethoxymethylbenzoguanamine, 1,3,4,6-tetrakis (butoxymethyl) glycoluril, 1,3,4,6-tetrakis (hydroxymethyl) glycoluril, 1,3 -Bis (hydroxymethyl) urea, 1,1,3,3-tetrakis (butoxymethyl) urea, 1,1,3,3-tetrakis (methoxymethyl) urea, 1,3-bis (hydroxymethyl) -4, And nitrogen-containing compounds such as 5-dihydroxy-2-imidazolinone and 1,3-bis (methoxymethyl) -4,5-dimethoxy-2-imidazolinone.

  Examples of the crosslinkable compound include methoxymethyl type melamine compounds (trade names: Cymel 300, Cymel 301, Cymel 303, Cymel 350) manufactured by Mitsui Cytec Co., Ltd., butoxymethyl type melamine compounds (trade names: Mycoat 506, Mycoat 508). ), Glycoluril compound (trade name Cymel 1170, powder link 1174), methylated urea resin (trade name UFR65), butylated urea resin (trade names UFR300, U-VAN10S60, U-VAN10R, U-VAN11HV), Dainippon Examples include commercially available compounds such as urea / formaldehyde resins (high condensation type, trade names Beccamin J-300S, Beccamin P-955, and Beckamine N) manufactured by Ink Chemical Industry Co., Ltd.

  The crosslinkable compound is a compound obtained by condensing the melamine compound, urea compound, glycoluril compound and benzoguanamine compound as described above in which the hydrogen atom of the amino group is substituted with a hydroxymethyl group or an alkoxymethyl group. May be. For example, a high molecular weight compound produced from a melamine compound (trade name Cymel 303) and a benzoguanamine compound (trade name Cymel 1123) described in US Pat. No. 6,323,310 can be used as the crosslinkable compound.

  Examples of the crosslinkable compound include N-hydroxymethyl acrylamide, N-methoxymethyl methacrylamide, N-ethoxymethyl acrylamide, N-butoxymethyl methacrylamide, and other acrylamide compounds or methacrylic compounds substituted with hydroxymethyl groups or alkoxymethyl groups. Polymer compounds produced using amide compounds can be used. Examples of such a polymer compound include poly (N-butoxymethyl acrylamide), a copolymer of N-butoxymethyl acrylamide and styrene, a copolymer of N-hydroxymethyl methacrylamide and methyl methacrylate, and N-ethoxymethyl methacryl. Examples thereof include a copolymer of amide and benzyl methacrylate, a copolymer of N-butoxymethylacrylamide, benzyl methacrylate, and 2-hydroxypropyl methacrylate.

  As the crosslinkable compound, only one kind of compound can be used, or two or more kinds of compounds can be used in combination.

  The crosslinkable compound is used in an amount of 1 to 100 parts, or 3 to 70 parts, or 5 to 50 parts, or 10 to 40 parts, or 20 to 30 parts by weight with respect to 100 parts by weight of the cyclodextrin compound. Can do. By changing the type and content of the crosslinkable compound, the step coverage of the photoresist profile and the underlying substrate can be adjusted.

  The composition for forming an underlayer film for lithography of the present invention contains a crosslinking catalyst. By using a crosslinking catalyst, the reaction of the crosslinkable compound is promoted.

  Examples of the crosslinking catalyst include acids such as p-toluenesulfonic acid, trifluoromethanesulfonic acid, methanesulfonic acid, pyridinium-p-toluenesulfonic acid, salicylic acid, camphorsulfonic acid, sulfosalicylic acid, citric acid, benzoic acid, and hydroxybenzoic acid. Compounds can be used.

  An aromatic sulfonic acid compound can be used as the crosslinking catalyst. Specific examples of the aromatic sulfonic acid compound include p-toluenesulfonic acid, pyridinium-p-toluenesulfonic acid, sulfosalicylic acid, 4-chlorobenzenesulfonic acid, 4-hydroxybenzenesulfonic acid, benzenedisulfonic acid, and 1-naphthalenesulfonic acid. And pyridinium-1-naphthalenesulfonic acid.

  A crosslinking catalyst can use only 1 type and can also be used in combination of 2 or more type.

  The crosslinking catalyst is 0.01 to 10 parts by mass, or 0.05 to 8 parts by mass, or 0.1 to 5 parts by mass, or 0.3 to 3 parts by mass, or 0. It can be used at 5 to 1 part by mass.

  The composition for forming an underlayer film for lithography of the present invention can contain a polymer compound. The type of the polymer compound is not particularly limited. Addition polymerization polymers and condensation polymerization polymers such as polyester, polystyrene, polyimide, acrylic polymer, methacrylic polymer, polyvinyl ether, phenol novolak, naphthol novolak, polyether, polyamide, and polycarbonate can be used. A polymer compound having an aromatic ring structure such as a benzene ring, naphthalene ring, anthracene ring, triazine ring, quinoline ring, and quinoxaline ring that functions as a light absorption site is preferably used.

  As the polymer compound, for example, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, or 2-hydroxypropyl methacrylate is used, and these monomer components are contained in an amount of 50% to 50% in the entire unit structure constituting the polymer compound. A polymer compound having a ratio of 100% can be preferably used.

  Only 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, or 2-hydroxypropyl methacrylate can be used for the synthesis of the polymer compound. In addition, a compound capable of undergoing a polymerization reaction with the acrylate compound or the methacrylate compound can be used for the synthesis of the polymer compound within a range satisfying the condition of the ratio of the unit structure. Examples of such a compound capable of polymerization reaction include acrylic acid, methacrylic acid, acrylic ester compound, methacrylic ester compound, acrylamide compound, methacrylamide compound, vinyl compound, styrene compound, maleimide compound, maleic anhydride and acrylonitrile. Is mentioned.

  Specific examples of the polymer compound include poly (2-hydroxyethyl acrylate), poly (2-hydroxyethyl methacrylate), poly (2-hydroxypropyl acrylate), poly (2-hydroxypropyl methacrylate), and 2-hydroxyethyl acrylate. Copolymer of 2-hydroxypropyl acrylate, copolymer of 2-hydroxyethyl acrylate and 2-hydroxypropyl acrylate, copolymer of 2-hydroxyethyl acrylate and methyl methacrylate, copolymer of 2-hydroxypropyl methacrylate and ethyl acrylate Polymer, copolymer of 2-hydroxypropyl methacrylate and benzyl methacrylate, 2-hydroxyethyl methacrylate and anthrylmethyl methacrylate DOO copolymer, a copolymer such as 2-hydroxyethyl methacrylate and styrene copolymer, and 2-hydroxyethyl acrylate and 4-hydroxy styrene.

  By using the polymer compound, the refractive index, attenuation coefficient, dry etching rate, and the like of the lower layer film can be adjusted.

  The molecular weight of the polymer compound is, for example, 1000 to 300,000, or 3000 to 100,000, for example, 5000 to 50000, or 9000 to 20000 as the weight average molecular weight.

  When a polymer compound is contained in the composition for forming a lower layer film for lithography of the present invention, 1 to 1000 parts by mass, or 10 to 500 parts by mass, or 20 to 200 parts by mass, or 30 to 30 parts by mass with respect to 100 parts by mass of the cyclodextrin compound. It can be used at 100 parts by mass or 40 to 50 parts by mass.

  As the solvent for the composition for forming a lower layer film for lithography according to the present invention, any solvent can be used as long as it dissolves the solid content to form a uniform solution. Examples of such solvents include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, methyl cellosolve acetate, ethyl cellosolve acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate. , Propylene glycol propyl ether acetate, toluene, xylene, methyl ethyl ketone, cyclopentanone, cyclohexanone, ethyl 2-hydroxypropionate, ethyl 2-hydroxy-2-methylpropionate, ethyl ethoxy acetate, ethyl hydroxyacetate, 2-hydroxy-3 -Methyl methylbutanoate, 3-methoxypropion Methyl, ethyl 3-methoxypropionate, ethyl 3-ethoxypropionate, methyl 3-ethoxypropionate, methyl pyruvate, ethyl pyruvate, ethyl acetate, butyl acetate, ethyl lactate, water, butyl lactate and the like can be used . These solvents can be used alone or in combination of two or more. Furthermore, high boiling point solvents such as propylene glycol monobutyl ether and propylene glycol monobutyl ether acetate can be mixed and used.

  Further, in the formation of the lower layer film, the lower layer film forming composition of the present invention is applied to a semiconductor substrate as will be described later, followed by firing. From the viewpoint of the firing temperature, the boiling point of the solvent is preferably in the range of 145 ° C to 220 ° C, or 155 ° C to 200 ° C, or 160 ° C to 180 ° C. In particular, when used for a semiconductor substrate having a hole having an aspect ratio of 1 or more represented by height / diameter, the boiling point of the solvent is preferably in the above range. By using such a solvent having a relatively high boiling point, the fluidity of the lower layer film-forming composition during firing can be maintained for a certain period of time. Therefore, it is possible to improve the hole filling property and planarization by the lower layer film formed from the lower layer film forming composition. Among the solvents, butyl lactate, propylene glycol monobutyl ether, propylene glycol monomethyl ether acetate, cyclohexanone and diethylene glycol monomethyl ether, or a mixture thereof is preferable.

  A surfactant, a rheology adjusting agent, an adhesion aid, and the like can be added to the composition for forming a lower layer film for lithography according to the present invention, if necessary. Surfactants are effective in suppressing the occurrence of pinholes and installations. The rheology modifier improves the fluidity of the lower layer film-forming composition, and is effective for enhancing the filling property of the lower layer film-forming composition into the holes, particularly in the firing step. The adhesion aid is effective in improving the adhesion between the semiconductor substrate or photoresist and the lower layer film, and in particular, suppressing the peeling of the photoresist during development.

  Examples of the surfactant include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene cetyl ether, polyoxyethylene alkyl ethers such as polyoxyethylene oleyl ether, polyoxyethylene octyl phenol ether, polyoxyethylene, and the like. Polyoxyethylene alkyl allyl ethers such as nonylphenol ether, polyoxyethylene / polyoxypropylene block copolymers, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, sorbitan trioleate, sorbitan trioleate Sorbitan fatty acid esters such as stearate, polyoxyethylene sorbitan monolaurate, polyoxyethylene Nonionic surfactants such as polyoxyethylene sorbitan fatty acid esters such as bitane monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan trioleate, polyoxyethylene sorbitan tristearate, trade name EFTOP EF301, EF303, EF352 (manufactured by Tochem Products Co., Ltd.), trade names MegaFuck F171, F173, R-08, R-30 (Dainippon Ink Chemical Co., Ltd.), Florard FC430, FC431 (Sumitomo 3M Co., Ltd.) Manufactured by Asahi Guard AG710, Surflon S-382, SC101, SC102, SC103, SC104, SC105, SC106 (manufactured by Asahi Glass Co., Ltd.), and organosiloxane polymer KP3 1 (manufactured by Shin-Etsu Chemical Co., Ltd.), and the like. These surfactants may be used alone or in combination of two or more. When a surfactant is contained in the underlayer film forming composition of the present invention, the content thereof is usually 0.2% by mass or less, or 0.1% by mass or less in all components of the underlayer film forming composition.

  Hereinafter, the use of the composition for forming a lower layer film for lithography of the present invention will be described.

  As a semiconductor substrate to which the underlayer film forming composition of the present invention is applied, for example, a semiconductor substrate commonly used for manufacturing a semiconductor device having a hole having an aspect ratio of 1 or more shown in height / diameter as shown in FIG. (For example, silicon / silicon dioxide coated substrate, silicon nitride substrate, glass substrate, ITO substrate, etc.). A semiconductor substrate having such holes is a substrate used particularly in a dual damascene process. It can also be used for a semiconductor substrate having holes with an aspect ratio smaller than 1 or a semiconductor substrate having steps. It can also be used for a semiconductor substrate having no step.

  On the semiconductor substrate, the underlayer film forming composition of the present invention is applied by an appropriate application method such as a spinner or a coater, and then the underlayer film is formed by baking. The conditions for firing are appropriately selected from firing temperatures of 60 ° C. to 220 ° C. and firing times of 0.3 to 60 minutes. Preferably, the firing temperature is 130 ° C to 250 ° C, or 170 ° C to 220 ° C. The firing time is 0.3 to 5 minutes or 0.5 to 2 minutes. Here, the film thickness of the lower layer film is, for example, 0.01 to 3.0 μm, and for example, 0.03 to 1.0 μm.

  Next, a layer of photoresist is formed on the lower layer film. Formation of the photoresist layer can be performed by a well-known method, that is, by applying a photoresist composition solution onto the lower layer film and baking.

  The photoresist applied and formed on the lower layer film of the present invention is not particularly limited as long as it is sensitive to light used for exposure. Moreover, either a negative photoresist or a positive photoresist can be used. A positive photoresist comprising a novolak resin and 1,2-naphthoquinonediazide sulfonic acid ester, a chemically amplified photoresist comprising a binder having a group that decomposes with an acid to increase the alkali dissolution rate and a photoacid generator, and an acid. Chemically amplified photoresist comprising a low molecular weight compound that decomposes to increase the alkali dissolution rate of the photoresist, an alkali-soluble binder, and a photoacid generator, a binder and an acid having a group that decomposes with acid to increase the alkali dissolution rate There are chemically amplified photoresists composed of a low-molecular compound and a photoacid generator that are decomposed by an alkali to increase the alkali dissolution rate of the photoresist. For example, trade name APEX-E manufactured by Shipley Co., Ltd., manufactured by Sumitomo Chemical Co., Ltd. Product name PAR710 and Shin-Etsu Chemical Co., Ltd. product name SEPR430 And the like.

  Next, exposure is performed through a predetermined mask. For the exposure, a KrF excimer laser (wavelength 248 nm), an ArF excimer laser (wavelength 193 nm), an F2 excimer laser (wavelength 157 nm), or the like can be used. After the exposure, post-exposure bake can be performed as necessary. The post-exposure heating is appropriately selected from a heating temperature of 70 ° C. to 150 ° C. and a heating time of 0.3 to 10 minutes.

  Next, development is performed with a developer. Thus, for example, when a positive photoresist is used, the exposed portion of the photoresist is removed, and a photoresist pattern is formed.

  Developers include aqueous solutions of alkali metal hydroxides such as potassium hydroxide and sodium hydroxide, aqueous solutions of quaternary ammonium hydroxides such as tetramethylammonium hydroxide, tetraethylammonium hydroxide and choline, ethanolamine, propylamine, An alkaline aqueous solution such as an aqueous amine solution such as ethylenediamine can be mentioned as an example. As the developer, a 2.38 mass% tetramethylammonium hydroxide aqueous solution that is widely used can be used. Further, a surfactant or the like can be added to these developers. The development conditions are appropriately selected from a temperature of 5 to 50 ° C. and a time of 0.1 to 5 minutes.

  Then, using the photoresist pattern thus formed as a protective film, the lower layer film is removed and the semiconductor substrate is processed. The removal of the lower layer film is made of tetrafluoromethane, perfluorocyclobutane, perfluoropropane, trifluoromethane, carbon monoxide, argon, oxygen, nitrogen, sulfur hexafluoride, difluoromethane, nitrogen trifluoride, chlorine trifluoride, etc. Performed using gas.

  An organic antireflection film layer may be formed before or after the lower layer film of the present invention is formed on the semiconductor substrate. The antireflective coating composition used there is not particularly limited, and can be arbitrarily selected from those conventionally used in the lithography process, and can be used by a conventional method such as a spinner. The antireflection film can be formed by coating and baking with a coater. Examples of the antireflection film composition include a light-absorbing compound, a polymer and a solvent as a main component, a polymer having a light-absorbing group linked by a chemical bond, a cross-linking agent and a solvent as a main component, and a light-absorbing compound. And those having a crosslinking agent and a solvent as main components and those having a light-absorbing polymer crosslinking agent and a solvent as main components. These anti-reflective coating compositions can also contain an acid component, an acid generator component, a rheology modifier, and the like, if necessary. Any light-absorbing compound can be used as long as it has a high absorption capability for light in the photosensitive characteristic wavelength region of the photosensitive component in the photoresist provided on the antireflection film. Examples include triazole compounds, azo compounds, naphthalene compounds, anthracene compounds, anthraquinone compounds, triazine compounds, and the like. Examples of the polymer include polyester, polyimide, polystyrene, novolac resin, polyacetal, and acrylic polymer. Examples of the polymer having a light-absorbing group linked by a chemical bond include polymers having a light-absorbing aromatic ring structure such as an anthracene ring, naphthalene ring, benzene ring, quinoline ring, quinoxaline ring, and thiazole ring.

  In addition, the semiconductor substrate to which the lower layer film-forming composition of the present invention is applied may have an inorganic antireflection film formed on the surface thereof by a CVD method or the like, on which the lower layer of the present invention is formed. A film can also be formed.

  The underlayer film formed from the underlayer film forming composition for lithography according to the present invention may have absorption of light depending on the wavelength of light used in the lithography process. It can be used as a layer having an effect of preventing reflection of light, that is, a lower antireflection film.

  Furthermore, the underlayer film of the present invention is a layer for preventing the interaction between the substrate and the photoresist, a material used for the photoresist, or a substance generated upon exposure to the photoresist to prevent an adverse effect on the substrate. It can also be used as a layer, a layer to prevent diffusion of the material generated from the semiconductor substrate upon firing into the upper photoresist, a barrier layer to reduce the poisoning effect of the photoresist layer by the semiconductor substrate dielectric layer, etc. It is.

  In addition, the lower layer film formed from the lower layer film forming composition is applied to a substrate in which a via hole used in a dual damascene process is formed, and can be used as an embedding material that can fill the hole without any gap. It can also be used as a planarizing material for planarizing.

Example 1
Β-cyclodextrin in which 5 to 20% by mass of iodine is included in 74.16 g of propylene glycol monomethyl ether (manufactured by Nichiho Chemical Co., Ltd., trade name: BCDI, terminal group ratio of β-cyclodextrin: all of β-cyclodextrin The hydroxyl group of the product was unmodified, and 100% of the hydroxyl group of β-cyclodextrin itself was present.) 10.0 g, tetramethoxymethyl glycoluril (trade name Powder Link 1174 manufactured by Mitsui Cytec Co., Ltd.) 3.50 g , 0.175 g of pyridinium-p-toluenesulfonic acid and 0.10 g of surfactant R-30 (Dainippon Ink Chemical Co., Ltd.) were added to make a 15% by mass solution, and then made of polyethylene having a pore size of 0.05 μm Filtration was performed using a microfilter to prepare a solution of an underlayer film forming composition for lithography.

Example 2
Β-cyclodextrin in which 2 to 20% by mass of iodine is included in 74.16 g of propylene glycol monomethyl ether (product of BCDI, trade name BCDI, β-cyclodextrin end group ratio: all of β-cyclodextrin The hydroxyl group of β-cyclodextrin itself was 100% hydroxyl group.) 10.0 g, hexamethoxymethylol melamine (trade name Cymel 303, manufactured by Mitsui Cytec Co., Ltd.) 3.50 g, pyridinium -0.175 g of p-toluenesulfonic acid and 0.10 g of surfactant R-30 (Dainippon Ink Chemical Co., Ltd.) were added to make a 15% by mass solution, and then a polyethylene microfilter having a pore size of 0.05 μm Was filtered to prepare a solution of an underlayer film forming composition for lithography.

Example 3
Methyl-β-cyclodextrin containing 2 to 20% by mass of p-toluenesulfonic acid in 74.16 g of propylene glycol monomethyl ether (manufactured by Wacker-Chemie GmbH, β-type chemically modified cyclodextrin, product Name CAVASOL W7M, terminal group ratio of β-cyclodextrin: 50% of the total hydroxyl group amount of β-cyclodextrin was converted to methoxy group, and the remaining 50% was hydroxyl group.) 10.0 g, hexamethoxymethylolmelamine ( Mitsui Cytec Co., Ltd., trade name Cymel 303), p-toluenesulfonic acid 0.350 g and surfactant R-30 (Dainippon Ink Chemical Co., Ltd.) 0.10 g are added, and a 15% by mass solution is added. And then filtered using a polyethylene microfilter with a pore size of 0.05 μm, A solution of an underlayer film forming composition for lithography was prepared.

Comparative Example 1
Chlorotriazinyl-β-cyclodextrin (made by Wacker-Chemie GmbH, trade name CAVASOL W7MCT, terminal group ratio of β-cyclodextrin: 50% of the total hydroxyl group amount of β-cyclodextrin is 684 g of water. Converted to 2-chlorotriazin-4-yl-oxy group, the remaining 50% were hydroxyl groups.) 100 g, tetramethoxymethylglycoluril 20.0 g, pyridinium-p-toluenesulfonic acid 0.6 g, and surface activity Agent R-30 (Dainippon Ink Chemical Co., Ltd.) 0.10 g was added to make a 15% by mass solution, followed by filtration using a polyethylene microfilter having a pore size of 0.05 μm, and a composition for forming a lower layer film for lithography. A solution of was prepared.

Comparative Example 2
Dextrin ester compound (manufactured by Gunei Chemical Industry Co., Ltd., trade name BZ-1, weight average molecule 7300, terminal group ratio of dextrin: 87% of the total hydroxyl amount of dextrin is benzoate group, and the remaining 13% is hydroxyl group Was added to 10.0 g of an ethyl lactate solution having a solid content concentration of 31%, 1.09 g of tetramethoxymethylglycoluril, 0.00546 g of pyridinium-p-toluenesulfonic acid, surfactant R-30 ( Dainippon Ink Chemical Co., Ltd.) 0.0153 g, propylene glycol monomethyl ether 5.26 g, and ethyl lactate 5.32 g were added to make an 18% by mass solution, and then a polyethylene microfilter having a pore size of 0.05 μm was used. Filtration was performed to prepare a solution of the underlayer film forming composition.

Elution test to photoresist solvent The solutions of the underlayer film forming compositions for lithography obtained in Examples 1 to 3 and Comparative Examples 1 to 2 were each applied onto a silicon wafer substrate by a spinner. Firing was performed at 205 ° C. for 1 minute on a hot plate to form a lower layer film (film thickness: 0.70 μm). These underlayer films were immersed in propylene glycol monomethyl ether acetate, which is a solvent used for a photoresist, and confirmed to be insoluble in these solvents.

Test of flattening rate and filling property Each of the solutions of the composition for forming a lower layer film for lithography obtained in Examples 1 to 3 and Comparative Examples 1 and 2 was subjected to holes (diameter 0.13 μm, depth 0. The film was applied onto a wafer substrate having a silicon dioxide (SiO ₂ ) insulating film having a thickness of 80 μm. The substrate used is a substrate having an iso (rough) and dense (dense) pattern of holes as shown in FIG. The Iso pattern is a pattern in which the distance from the hole center to the adjacent hole center is five times the diameter of the hole. The dense pattern is a pattern in which the distance from the hole center to the adjacent hole center is one time the diameter of the hole.

  After the coating, baking was performed at 205 ° C. for 1 minute on a hot plate to form a lower layer film. The film thickness was 0.70 μm in an open area where there was no hole pattern nearby. By using a scanning electron microscope (SEM), the planar shape of each substrate was evaluated by observing the cross-sectional shape of each substrate. The flattening rate was determined according to the following formula. The flattening rate when the holes on the substrate can be completely flattened is 100%.

Planarization rate = {1− (depth of recess in lower layer film a at the center of the hole) / (depth of hole b)} × 100
Moreover, no void (gap) was observed inside the hole, and it was observed that the inside of the hole was filled with a lower layer film.
[Table 1]
Table 1
――――――――――――――――――――――――――――――――――――
Film thickness (nm) Flattening rate (%)
Iso Dense Bias Iso Dense Bias
――――――――――――――――――――――――――――――――――――
Example 1 710 590 120 100 100 0
Example 2 690 580 110 100 100 0
Example 3 720 600 120 100 100 0
Comparative Example 1 700 580 120 100 100 0
Comparative Example 2 700 590 110 100 100 0
――――――――――――――――――――――――――――――――――――
The difference in film thickness (Bias) between the Iso (coarse) pattern and the Dense (dense) pattern of the lower layer films of Examples 1 to 3 is small. This is presumably because the solution of the lower layer film forming composition smoothly flowed into the holes even in the dense part where the number of holes per unit area (hole density) on the hole substrate was larger than that in the iso part. As a result, it is considered that the film thickness difference between the Iso portion and the Dense portion is small and the flattening rate is large.

  Moreover, it turned out that it can planarize irrespective of Iso part and Dense part by the lower layer film forming composition of Examples 1-3 without being inferior to Comparative Examples 1-2.

Measurement of optical parameters The underlayer film forming composition solution prepared in Example 1 was applied onto a silicon wafer substrate by a spinner. Firing was performed at 205 ° C. for 1 minute on a hot plate to form a lower layer film (film thickness: 0.70 μm). Then, when the refractive index (n value) and the attenuation coefficient (k value) at a wavelength of 193 nm were measured for this lower layer film using a spectroscopic ellipsometer, the refractive index (n value) was 1.68 and the attenuation coefficient (k Value) was 0.09.
The underlayer film forming composition solution prepared in Example 2 was applied onto a silicon wafer substrate by a spinner. Firing was performed at 205 ° C. for 1 minute on a hot plate to form a lower layer film (film thickness: 0.70 μm). Then, when the refractive index (n value) and the attenuation coefficient (k value) at a wavelength of 193 nm were measured for this lower layer film using a spectroscopic ellipsometer, the refractive index (n value) was 1.70, and the attenuation coefficient (k Value) was 0.09.

The underlayer film forming composition solution prepared in Example 3 was applied onto a silicon wafer substrate by a spinner. Firing was performed at 205 ° C. for 1 minute on a hot plate to form a lower layer film (film thickness: 0.70 μm). Then, when the refractive index (n value) and the attenuation coefficient (k value) at a wavelength of 193 nm were measured for this lower layer film using a spectroscopic ellipsometer, the refractive index (n value) was 1.68 and the attenuation coefficient (k Value) was 0.08.
The lower layer film forming composition solution prepared in Comparative Example 1 was applied onto a silicon wafer substrate by a spinner. Firing was performed at 205 ° C. for 1 minute on a hot plate to form a lower layer film (film thickness: 0.70 μm). Then, when the refractive index (n value) and the attenuation coefficient (k value) at a wavelength of 193 nm were measured for this lower layer film using a spectroscopic ellipsometer, the refractive index (n value) was 1.70, and the attenuation coefficient (k Value) was 0.20.
The lower layer film forming composition solution prepared in Comparative Example 2 was applied onto a silicon wafer substrate by a spinner. Firing was performed at 205 ° C. for 1 minute on a hot plate to form a lower layer film (film thickness: 0.70 μm). Then, when the refractive index (n value) and the attenuation coefficient (k value) at a wavelength of 193 nm were measured for this lower layer film using a spectroscopic ellipsometer, the refractive index (n value) was 1.57, and the attenuation coefficient (k Value) was 0.68.

Test of Dry Etching Rate Each of the solutions of the composition for forming a lower layer film for lithography obtained in Examples 1 to 3 and Comparative Examples 1 and 2 was applied onto a silicon wafer substrate by a spinner. Firing was performed at 205 ° C. for 1 minute on a hot plate to form a lower layer film (film thickness: 0.70 μm). Then these, using Japan Scientific Ltd. RIE system ES401, was measured dry etching rate under a condition of using CF ₄ as a dry etching gas.

The results are shown in Table 2. The selection ratio indicates the dry etching rate of the lower layer film when the dry etching rate of the photoresist for ArF excimer laser lithography (product name: GARS8105G1 manufactured by Fuji Photo Film Co., Ltd.) is 1.00. .
[Table 2]
Table 2
――――――――――――
Selectivity ――――――――――――
Example 1 3.10
Example 2 3.15
Example 3 3.12
Comparative Example 1 2.70
Comparative Example 2 1.39
――――――――――――
It was confirmed that the etching rate of the lower layer films obtained from the lower layer film forming compositions of Examples 1 to 3 was much higher than that of Comparative Examples 1 and 2 compared to the photoresist. The reason why the resist underlayer film having selectivity of 3 or more was found is that cyclodextrin in which iodine was included was used.

  The dry etching rate of the lower layer film is required to be higher than the dry etching rate of the photoresist. It is a process that develops the photoresist and exposes the base of the substrate by dry etching. Since the dry etching rate of the lower layer film is higher than the dry etching rate of the photoresist, etching is performed while the lower layer film is removed by etching. This is because it is possible to suppress the amount of the photoresist that is scraped off, that is, the film thickness of the photoresist.

  The composition for forming a lower layer film for lithography containing cyclodextrin containing an inclusion molecule, the lower layer film obtained thereby, a method for forming a resist pattern using the lower layer film, and further, the production of a semiconductor device using them.

FIG. 1 is a sectional view showing a state in which a lower layer film is formed on a substrate having holes.

Explanation of symbols

  a is the depth (μm) of the recess of the lower layer film at the hole center.

  b is the initial hole depth (μm) in the substrate used.

  c is a lower layer film.

  d is a substrate.

Claims (8)

Composition for forming an underlayer film for lithography comprising the cyclodextrin containing inclusion molecule 1 to 80% by weight relative to the cyclodextrin. The composition for forming an underlayer film for lithography according to claim 1, wherein the inclusion molecule is a halogen molecule, an acid molecule, a base molecule, an acid generator, or a base generator. The underlayer film forming composition for lithography according to claim 1 or 2, wherein the cyclodextrin is an α-type, β-type, γ-type, or δ-type cyclodextrin. In the cyclodextrin, the hydroxyl group contained in the molecule is represented by the formula (1):

(In the formula (1), R ₁ has 1 to 1 carbon atoms which may be substituted with a group selected from the group consisting of a halogen group, an alkoxy group having 1 to 6 carbon atoms, a phenyl group, a cyano group and a nitro group. 10 alkyl or aromatic groups, or formula (2):

In the formula (2), R ₂ is substituted with a group selected from the group consisting of a halogen group, an alkoxy group having 1 to 6 carbon atoms, a phenyl group, a cyano group, and a nitro group. Or an alkyl group having 1 to 10 carbon atoms or an aromatic group. The composition for forming an underlayer film for lithography according to any one of claims 1 to 3, wherein the composition is a chemically modified cyclodextrin substituted with an organic group represented by: 5. The cyclodextrin according to claim 1, comprising a chemically modified cyclodextrin in which a hydroxyl group contained in the molecule is replaced with an organic group of the formula (1) at a ratio of 10 to 90%. A composition for forming an underlayer film for lithography. The composition for forming an underlayer film for lithography according to any one of claims 1 to 5, further comprising a polymer and a solvent. The composition for forming an underlayer film for lithography according to any one of claims 1 to 6, further comprising a crosslinkable compound and a crosslinking catalyst. A step of applying a composition for forming a lower layer film for lithography according to any one of claims 1 to 7 on a semiconductor substrate and baking to form a lower layer film, and forming a photoresist layer on the lower layer film A method for manufacturing a semiconductor device, comprising: a step of exposing a semiconductor substrate covered with the lower layer film and the photoresist layer; and a step of developing the photoresist layer after exposure.