JP5177132B2 - Composition for resist underlayer film and method for forming dual damascene structure - Google Patents

Description

  The present invention relates to a resist underlayer film composition and a method for forming a dual damascene structure. More specifically, a resist underlayer film composition that can be formed into a resist underlayer film that is well embedded in a via hole, has good etching resistance, can be easily removed, and has excellent pattern transfer performance, and this composition The present invention relates to a method for forming a dual damascene structure using an object.

  Conventionally, when manufacturing an integrated circuit element or the like, an organic film such as a photoresist film is formed on an inorganic film such as a silicon-based oxide film or an interlayer insulating film, for example, radiation irradiation, development, pattern transfer, etc. A desired resist pattern is formed on the organic film and the inorganic film by a resist process (that is, photolithography) through the above steps. In this photolithography, it is common to provide a resist underlayer film which is an organic coating under the photoresist film. That is, after a resist underlayer film is formed in advance, a photoresist film is formed on the resist underlayer film.

  This resist underlayer film fills and flattens gaps such as irregularities and grooves on the base substrate, absorbs radiation reflected from the substrate to prevent halation in the pattern, and finely processes the inorganic coating Therefore, a function as a mask is required.

  As a resist underlayer film composition for forming a resist underlayer film having these functions, for example, a composition mainly composed of a polymer having an acenaphthylene unit has been proposed (for example, Patent Documents 1 and 2). .

  In particular, regarding the resist underlayer film having a function as a mask for finely processing the inorganic coating, that is, the resist underlayer film having etching resistance, various studies have been made on the polymer contained in the resist underlayer film. And several empirical relations for polymer structure have been proposed.

For example, Onishi et al. Have proposed that etching resistance can be evaluated by the following formula (i) called Onishi parameter (for example, Non-Patent Document 1).
(I): NT / {NC-NO- (2 × NX)}
(In the above formula (i), NT is the total number of atoms, NC is the number of carbon atoms, NO is the number of oxygen atoms, and NX is the number of halogen atoms.)

  According to this Onishi parameter, when the parameter value is small, for example, a resist underlayer film having a large number of carbon atoms and a small number of oxygen atoms and halogen atoms means that the etching resistance is good.

  Onishi et al. Have proposed that plasma ashing (hereinafter sometimes referred to as “ashing”) can be evaluated using the Onishi parameters. Specifically, it has been proposed that when the value of the Onishi parameter is large, it can be evaluated that the processing speed of plasma ashing is good (fast).

  As the resist underlayer film having a high Onishi parameter value (which can be satisfactorily ashed), for example, a resist underlayer film formed of a composition containing halogenated polyhydroxystyrene (for example, Patent Document 3), etc. Can be mentioned.

JP 2001-40293 A JP 2000-143937 A JP 2003-57828 A J. et al. Electrochem. Soc. 130, 143 (1983)

  The resist underlayer film formed by the composition described in Patent Documents 1 and 2 is a resist underlayer film having a low Onishi parameter and good etching resistance. However, in ashing, the Onishi parameter is too low, that is, for ashing. There is a problem that it takes time (the ashing processing speed is slow) and the ashing of the resist underlayer film damages the inorganic coating formed under the resist underlayer film.

  Specifically, when the above-mentioned inorganic coating, particularly a low dielectric insulating film (hereinafter sometimes referred to as “Low-k film”) is used by ashing, the effective dielectric constant is increased. there were. More specifically, in the resist pattern formation by the via first dual damascene process, when the resist underlayer film filled in the via hole is removed, the low-k film around the via hole is damaged by being exposed to plasma by ashing. The effective dielectric constant sometimes increased. Note that when the effective dielectric constant increases, the electrical characteristics of the manufactured integrated circuit element and the like are significantly deteriorated.

  The resist underlayer film formed from the composition of Patent Document 3 has high Onishi parameters and good plasma ashing processing speed, so that it is difficult to damage the low-k film by ashing the resist underlayer film, but etching resistance Is not sufficient (Onishi parameter is too high), and there is a problem that it is difficult to form a highly accurate resist pattern.

  As described above, the resist underlayer film formed by the conventional resist underlayer film composition is not well-balanced to have good etching resistance and good plasma ashing processing speed, Development of a resist underlayer film composition capable of forming a resist underlayer film that satisfies both of these has been desired.

  The present invention has been made in view of such problems of the prior art, and is well embedded in via holes, has good etching resistance, can be easily removed, and has excellent pattern transfer performance. A resist underlayer film composition capable of forming a resist underlayer film and a method for forming a dual damascene structure using the composition are provided.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that a composition for a resist underlayer film having a nitrogen atom content of 10% by mass or more in a resist underlayer film formed under predetermined conditions, and this It has been found that the above problems can be solved by a method for forming a dual damascene structure using a composition, and the present invention has been completed.

  Specifically, the present invention provides the following resist underlayer film composition and a method for forming a dual damascene structure using this composition.

[1] When a resist underlayer film having a thickness of 300 nm is formed by coating on a substrate and heating and drying at 250 ° C. for 60 seconds, the content of nitrogen atoms in the formed resist underlayer film is 10 mass. der least% is, the resin containing a nitrogen atom, and includes a solvent, the resin is a resist underlayer film composition containing 10 to 20 wt% of the nitrogen atoms.

[ 2 ] The resist underlayer film composition according to [ 1], wherein the resin contains at least one selected from the group consisting of structural units represented by the following formulas (1), (2), and (3): object.

[ 3 ] The resist underlayer according to [ 2 ], wherein the total proportion of the structural units represented by the formulas (1), (2) and (3) contained in the resin is 10 to 50% by mass. Film composition.

[ 4 ] The resist underlayer film composition according to [ 2 ] or [ 3 ], wherein the resin further includes a structural unit represented by the following general formula (4).

（前記一般式（４）中、Ｒ^１は、炭素数１〜２０の直鎖状、分岐状若しくは環状のアルキル基、ヒドロキシル基、炭素数１〜６の置換可能なヒドロキシアルキル基、炭素数１〜２０の置換可能なアルコキシル基、炭素数１〜６の置換可能なアルキルチオ基、アラルキルチオ基若しくはアリールチオ基、アミノ基、炭素数１〜６の置換可能なアルキルアミノ基、アラルキルアミノ基若しくはアリールアミノ基、ハロゲン原子、または炭素数７〜２０の置換可能なアリール基を示す。ｘは１〜６の整数であり、ｙは０〜２の整数であり、ｘが２以上である場合は、Ｒ^１は各々同一でも異なってもよい）

(In the general formula (4), R ¹ is a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, a hydroxyl group, a substitutable hydroxyalkyl group having 1 to 6 carbon atoms, or 1 carbon atom. ˜20 substitutable alkoxyl group, C 1-6 substitutable alkylthio group, aralkylthio group or arylthio group, amino group, C 1-6 substitutable alkylamino group, aralkylamino group or arylamino A group, a halogen atom, or a substitutable aryl group having 7 to 20 carbon atoms, x is an integer of 1 to 6, y is an integer of 0 to 2, and when x is 2 or more, R ¹ may be the same or different.

[ 5 ] The resist underlayer film composition according to any one of [1] to [ 4 ], further including at least one selected from the group consisting of an acid generator and a crosslinking agent.

[ 6 ] Using the photoresist film, which is disposed on the resist underlayer film formed by the composition for a resist underlayer film according to any one of [1] to [ 5 ] and has a resist pattern, as a mask, A step of transferring the resist pattern of the photoresist film to the resist underlayer film by etching, and using the resist underlayer film to which the resist pattern of the photoresist film has been transferred as a mask, disposed under the resist underlayer film Transferring the resist pattern of the resist underlayer film to the formed low dielectric insulating film; and transferring the resist pattern of the resist underlayer film to the low dielectric insulating film and then removing the resist underlayer film by plasma ashing And a method of forming a dual damascene structure.

[ 7 ] The method for forming a dual damascene structure according to [ 6 ], wherein the gas used for the plasma ashing is a mixed gas of ammonia, nitrogen, and hydrogen.

  The resist underlayer film composition of the present invention is well embedded in a via hole, has good etching resistance, can be easily removed, and can form a resist underlayer film excellent in pattern transfer performance. There is an effect.

  According to the method for forming a dual damascene structure of the present invention, the composition for a resist underlayer film of the present invention that is well embedded in a via hole, has good etching resistance, can be easily removed, and has excellent pattern transfer performance. Since this method uses a material, the resist pattern is good and the dual damascene structure can be formed with little damage to the low dielectric insulating film.

It is a schematic diagram explaining 1 process of the formation method of the dual damascene structure of this embodiment. It is a schematic diagram explaining 1 process of the formation method of the dual damascene structure of this embodiment. It is a schematic diagram explaining 1 process of the formation method of the dual damascene structure of this embodiment. It is a schematic diagram explaining 1 process of the formation method of the dual damascene structure of this embodiment. It is a schematic diagram explaining 1 process of the formation method of the dual damascene structure of this embodiment. It is a schematic diagram explaining 1 process of the formation method of the dual damascene structure of this embodiment. It is a schematic diagram explaining 1 process of the formation method of the dual damascene structure of this embodiment. It is a schematic diagram explaining 1 process of the formation method of the dual damascene structure of this embodiment. It is a schematic diagram explaining 1 process of the formation method of the dual damascene structure of this embodiment. It is sectional drawing which shows the state after giving wiring to the dual damascene structure formed by the formation method of the dual damascene structure of this embodiment.

Explanation of symbols

1: substrate, 2: first low dielectric insulating film, 3, 13: resist underlayer film, 4: wiring trench (trench), 5, 15: barrier metal, 6: lower copper wiring layer, 7: second low Dielectric insulating film, 8: first etching stopper layer, 9: third low dielectric insulating film, 10: second etching stopper layer, 11: resist underlayer film, 12: via hole, 14: trench, 16: via wiring 17: Upper copper wiring layer.

  BEST MODE FOR CARRYING OUT THE INVENTION The best mode for carrying out the present invention will be described below, but the present invention is not limited to the following embodiment, and is based on the ordinary knowledge of those skilled in the art without departing from the gist of the present invention. It should be understood that modifications and improvements as appropriate to the following embodiments also fall within the scope of the present invention.

[1] Composition for resist underlayer film:
One embodiment of the resist underlayer film composition of the present invention is a resist formed when a resist underlayer film having a thickness of 300 nm is formed by coating on a substrate and drying at 250 ° C. for 60 seconds. The nitrogen atom content in the lower layer film is 10% by mass or more.

The resist underlayer film composition of the present embodiment is contained in the resist underlayer film at the time of etching (RIE processing) by setting the content of nitrogen atoms in the resist underlayer film formed under the above conditions to 10% by mass or more. The generated nitrogen atoms react with fluorine derived from an etching gas such as CF ₄ or C ₂ F ₅ to generate nonvolatile ammonium fluoride, ammonium fluorosilicate, or the like. It is considered that the etching resistance of the resist underlayer film is improved by the blocking action of these ammonium fluorides and ammonium fluorosilicates. In ashing, volatile gases such as HCN and C ₂ N ₂ are generated in the resist underlayer film due to nitrogen atoms in the resist underlayer film, so that the resist underlayer film is easily removed. It is considered a thing.

  The resist underlayer film formed from the resist underlayer film composition of the present embodiment uses the resist underlayer film having a resist pattern as a mask, and follows the trend of Onishi parameters when transferring the pattern to the low dielectric insulating film. Etching resistance. However, when it is removed by plasma ashing, it is easily removed from the trend of Onishi parameters (the processing speed of plasma ashing is good). Therefore, it is difficult to damage the low dielectric insulating film during plasma ashing. As described above, the resist underlayer film formed from the resist underlayer film composition of the present embodiment is easily removed by plasma ashing, has good etching resistance, and has excellent pattern transfer performance. is there.

  By the way, the conventional resist underlayer film composition has a nitrogen atom content of less than 10% by mass in the resist underlayer film formed under the above conditions, and the resist underlayer film formed by the conventional resist underlayer film composition is However, in addition to having good etching resistance, it has been reported that it can be easily removed by plasma ashing. It wasn't possible.

  According to the Onishi parameter, it has been proposed that mainly the number of carbon atoms, number of oxygen atoms, and number of halogen atoms in the resist underlayer film are involved in improving the etching resistance and the processing speed of plasma ashing. Therefore, a conventional resist underlayer film composition has been taken by a method of decreasing the Onishi parameter (increasing the amount of carbon atoms) in order to improve etching resistance. Moreover, in order to improve the processing speed of plasma ashing, the method of raising Onishi parameter (increasing the amount of oxygen atoms) has been taken. As described above, it is difficult to improve both the etching resistance and the plasma ashing processing speed in the conventional method (that is, the etching resistance and the plasma ashing processing speed are in a trade-off relationship). Therefore, the present inventors pay attention to the specific property of nitrogen atoms (the property of generating a non-volatile gas during etching and the generation of volatile gas during plasma ashing), and adding nitrogen atoms to the resist underlayer film. Thus, it was found that both the etching resistance and the plasma ashing processing speed can be improved by setting the ratio to a predetermined value or more (10% by mass or more).

  The composition for resist underlayer film of this embodiment will be described in detail below.

  The resist underlayer film composition of the present embodiment is coated on a substrate, dried by heating at 250 ° C. for 60 seconds, and the content of nitrogen atoms in the resist underlayer film having a thickness of 300 nm is not less than the predetermined amount. As long as it is, the substrate used for forming the resist underlayer film is not particularly limited, and for example, a silicon wafer, a silicon oxide film, silicon nitride, or the like can be used. The method for applying the resist underlayer film composition is not particularly limited, but a spin coating method is preferred.

  Specifically, the resist underlayer film composition of the present embodiment (solid content: 10% by mass) is applied on a silicon wafer having a diameter of 8 inches as a base material by, for example, spin coating, and “ ACT8 ", dried at 180 ° C. for 60 seconds, and then placed so that the silicon wafer is in contact with the hot plate, and heated and dried on the hot plate at 250 ° C. for 60 seconds to dry the resist underlayer film having a thickness of 300 nm Form.

  In the resist underlayer film composition of the present embodiment, the resist underlayer film formed as described above contains 10% by mass or more of nitrogen atoms, and preferably contains 10 to 50% by mass. More preferably, the content is 20 to 40% by mass. When the nitrogen atom content is less than 10% by mass, a resist underlayer film having a good ashing speed cannot be obtained. On the other hand, if it is more than 50% by mass, the carbon atom content in the resist underlayer film is relatively reduced, so that sufficient etching resistance may not be obtained according to the Onishi parameter. Here, the “content ratio of nitrogen atom” in the present specification is a value measured by an organic element analyzer. For example, an organic element analyzer (trade name “CHN coder JM10”) manufactured by J Science can be used.

  The composition for a resist underlayer film of the present embodiment is particularly included in the composition (for example, the type of resin) as long as the nitrogen atom content in the resist underlayer film formed under the above conditions is 10% by mass or more. Although there is no restriction | limiting, It is preferable that the resin containing a nitrogen atom and a solvent are included.

[1-1] Resin containing nitrogen atom:
The resin containing a nitrogen atom that can be included in the resist underlayer film composition of the present embodiment is not particularly limited as long as it contains a nitrogen atom, but contains 10% by mass or more of a nitrogen atom. It is preferable that the content is 15% by mass or more. If the nitrogen atom content in the resin is less than 10% by mass, it may not be possible to obtain a sufficient processing speed in plasma ashing. On the other hand, if the nitrogen content in the resist underlayer film exceeds 15% by mass, it is possible to obtain a sufficient processing speed in plasma ashing, and in addition, non-volatility due to nitrogen atoms generated during etching. This gas has the advantage that the etching resistance is greatly improved.

  The resin containing a nitrogen atom preferably has a weight average molecular weight (Mw) of 1000 to 20000, more preferably 1000 to 3000. When the weight average molecular weight is less than 1000, when the resist underlayer film is formed, a low molecular component may volatilize from the resist underlayer film at the time of baking, and the coating apparatus may be contaminated. On the other hand, if it exceeds 3000, the via hole filling property required for the dual damascene process may be lowered. On the other hand, if it exceeds 20000, the via hole embedding property necessary for the dual damascene process may be further deteriorated. Here, “weight average molecular weight” in the present specification means a polystyrene-equivalent number average molecular weight by gel permeation chromatography (GPC).

  The ratio (Mw / Mn) between the weight average molecular weight (Mw) and the number average molecular weight (hereinafter sometimes referred to as “Mn”) of the resin containing a nitrogen atom is preferably 3.0 or less. There exists a possibility that applicability | paintability may deteriorate that the said Mw / Mn is more than 3.0. Here, the “number average molecular weight” in the present specification means a polystyrene-equivalent number average molecular weight by gel permeation chromatography (GPC).

  Specifically, Mw and Mn are the high-speed GPC device (model “HLC-8120”) manufactured by Tosoh Corporation and the GPC columns (trade name “G2000HXL”; two, “G3000HXL”; one by Tosoh Corporation. , “G4000HXL”; 1) and measured by gel permeation chromatography (GPC) using monodisperse polystyrene as a standard under the analysis conditions of a flow rate of 1.0 ml / min, elution solvent tetrahydrofuran, and column temperature of 40 ° C. Value.

  Examples of resins containing nitrogen atoms include amino resins produced by reaction with formaldehyde (urea resins, thiourea resins, guanamine resins, melamine resins, guanidine resins and other condensation resins, urea-melamine resins, urea-benzoguanamine resins. , Phenol-melamine resin, naphthol-melamine resin, benzoguanamine-melamine resin, copolycondensation resin such as aromatic polyamine-melamine resin), aromatic amine-formaldehyde resin (aniline resin, etc.), polyamide resin (for example, nylon 3, Nylon 6, nylon 66, nylon 11, nylon 12, nylon MXD, 6, nylon 4-6, nylon 6-10, nylon 6-11, nylon 6-12, nylon 6-66-610, or a single or copolymer polyamide , Methylol group Alkoxy and substituted polyamides having a methyl group), polyester amides, polyamide-imide, polyacrylamides, amino thioether, and the like. These can be used alone or in combination of two or more.

  Among these, a resin containing at least one selected from the group consisting of structural units represented by the following formulas (1), (2) and (3) (hereinafter sometimes referred to as “first resin”) It is preferable that

  Specific examples of such first resin include urea resins, thiourea resins, guanamine resins, melamine resins, guanidine resins and other condensation resins, urea-melamine resins, urea-benzoguanamine resins, phenol-melamine resins, Amino resins such as naphthol-melamine resins, alkoxyphenyl-melamine resins, alkoxynaphthalene-melamine resins, alkoxyanthracene-melamine resins, benzoguanamine-melamine resins, and aromatic polyamine-melamine resins are preferred. Among these, phenol-melamine resin, naphthol-melamine resin, alkoxyphenyl-melamine resin, alkoxynaphthalene-melamine resin, alkoxyanthracene-melamine resin, melamine resin (melamine-formaldehyde resin) and the like are preferable.

  The weight average molecular weight (Mw) of the first resin is particularly preferably 1000 to 8000. If the weight average molecular weight (Mw) is less than 1000, when the resist underlayer film is formed, low molecular components may volatilize from the resist underlayer film during baking, and the coating apparatus may be contaminated. On the other hand, if it exceeds 8000, the via hole filling property required for the dual damascene process may be lowered.

  The ratio (Mw / Mn) between the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the first resin is preferably 7.0 or less. There exists a possibility that applicability | paintability may deteriorate that said Mw / Mn is more than 7.0.

  The resist underlayer film composition of the present embodiment is represented by the above formulas (1), (2), and (3), which has a large content of nitrogen atoms contained in one structural unit as a resin containing nitrogen atoms. By including a resin (first resin) containing at least one selected from the group consisting of structural units, there is an advantage that the amount of nitrogen atoms contained in the resist underlayer film can be increased.

  The first resin can be produced, for example, by reacting a compound having a triazine structure with a compound having an aldehyde group. Thus, when the compound which has a triazine structure and the compound which has an aldehyde group are made to react, there exists an advantage that a 1st resin can be obtained easily.

  The compound having a triazine structure that can be used in the production of the first resin is not particularly limited as long as it has a triazine structure, but the compound represented by the following general formula (5), Examples include compounds represented by the general formula (6). In addition, these compounds can be used individually or in combination of 2 or more types.

（上記一般式（５）中、Ｒ^３は、炭素数１〜６アミノ基、炭素数１〜６のアルキル基、フェニル基、ヒドロキシル基、炭素数１〜６のヒドロキシルアルキル基、炭素数１〜８のアルキルエーテル基、炭素数１〜１２のカルボン酸エステル基、炭素数１〜８のカルボン酸基、炭素数１〜６のシアノ基、またはハロゲン原子を示す。なお、Ｒ^３はそれぞれ同一でも異なっていてもよい）

(In the above general formula (5), R ³ represents an amino group having 1 to 6 carbon atoms, an alkyl group having 1 to 6 carbon atoms, a phenyl group, a hydroxyl group, a hydroxyl alkyl group having 1 to 6 carbon atoms, or 1 to 1 carbon atoms. 8 represents an alkyl ether group, a carboxylic acid ester group having 1 to 12 carbon atoms, a carboxylic acid group having 1 to 8 carbon atoms, a cyano group having 1 to 6 carbon atoms, or a halogen atom, wherein R ³ may be the same. May be different)

（上記一般式（６）中、Ｒ^４は、水素原子、炭素数１〜６アルキル基、フェニル基、ヒドロキシル基、炭素数１〜６のヒドロキシルアルキル基、炭素数１〜１２のカルボン酸エステル基、炭素数１〜８のカルボン酸基、炭素数１〜６のシアノ基、またはハロゲン原子を示す。なお、Ｒ^４は、それぞれ同一でも異なっていてもよい）

(In the general formula (6), R ⁴ is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a phenyl group, a hydroxyl group, a hydroxyl alkyl group having 1 to 6 carbon atoms, or a carboxylic acid ester group having 1 to 12 carbon atoms. Represents a carboxylic acid group having 1 to 8 carbon atoms, a cyano group having 1 to 6 carbon atoms, or a halogen atom, wherein R ⁴ may be the same or different.

Examples of the compound represented by the general formula (5) include guanamine derivatives such as melamine, acetoguanamine, or benzoguanamine, cyanuric acid, or cyanuric acid derivatives such as methyl cyanurate, ethyl cyanurate, acetyl cyanurate, or cyanuric chloride. Etc. Among these, melamine or a guanamine derivative such as acetoguanamine or benzoguanamine, in which two or three R ³ are amino groups, is preferable. In addition, these can be used individually or in combination of 2 or more types.

Examples of the compound represented by the general formula (6) include isocyanuric acid, methyl isocyanurate, ethyl isocyanurate, allyl isocyanurate, 2-hydroxyethyl isocyanurate, 2-carboxylethyl isocyanurate, and chlorinated isocyanuric acid. Examples include isocyanuric acid derivatives. Among these, isocyanuric acid in which all of R ⁴ are hydrogen atoms is preferable. In addition, these can be used individually or in combination of 2 or more types.

  The compound having an aldehyde group that can be used in the production of the first resin is not particularly limited as long as it has an aldehyde group. For example, formaldehyde, paraformaldehyde, trioxane, acetaldehyde, propionaldehyde, butyl Aldehyde, trimethylacetaldehyde, acrolein, crotonaldehyde, cyclohexanealdehyde, furfural, furylacrolein, benzaldehyde, terephthalaldehyde, phenylacetaldehyde, α-phenylpropylaldehyde, β-phenylpropylaldehyde, o-hydroxybenzaldehyde, m-hydroxybenzaldehyde, p- Hydroxybenzaldehyde, o-methylbenzaldehyde, m-methylbenzaldehyde, p-methylbenzaldehyde Examples thereof include aldehyde, o-chlorobenzaldehyde, m-chlorobenzaldehyde, p-chlorobenzaldehyde, and cinnamic aldehyde. In addition, these can be used individually or in combination of 2 or more types. Among these compounds having an aldehyde group, formaldehyde is preferable from the viewpoint of easy availability and easy handling. Formaldehyde is not particularly limited, but formalin, paraformaldehyde and the like can be suitably used.

  The amount of the compound having a triazine structure and the compound having an aldehyde group that can be used in the production of the first resin is not particularly limited. For example, the compound having a triazine structure is represented by the general formula (5). When the compound used is used, the compound having an aldehyde group is preferably used in an amount of 10 to 200 parts by weight, more preferably 20 to 100 parts by weight, based on 100 parts by weight of the compound represented by the general formula (5). It is particularly preferable to use 20 to 60 parts by mass. The molecular weight can be controlled by setting the amount of the compound having an aldehyde group within the above range.

  The first resin can also be obtained, for example, by polymerizing a glycoluril derivative represented by the following formula (7).

（前記一般式（７）中、Ｒ^５は、相互に独立して、水素原子、メチル基、エチル基、プロピル基、又はブチル基を示す。なお、Ｒ^５は、それぞれ同一でも異なっていてもよい）

(In the general formula (7), R ⁵ independently represents a hydrogen atom, a methyl group, an ethyl group, a propyl group, or a butyl group. The R ^{5 s} may be the same or different. Good)

  The reaction conditions for producing the first resin are not particularly limited, but the reaction temperature is preferably 50 to 200 ° C, more preferably 50 to 150 ° C, and 50 to 100 ° C. Is particularly preferred. The reaction time is particularly preferably 1 to 5 hours.

  The resin containing a nitrogen atom contains at least one selected from the group consisting of the structural units represented by the above formulas (1), (2) and (3), and in addition, the following general formula (4) It is more preferable that the resin contains a structural unit represented by (hereinafter, referred to as “second resin” in some cases).

（前記一般式（４）中、Ｒ^１は、炭素数１〜２０の直鎖状、分岐状若しくは環状のアルキル基、ヒドロキシル基、炭素数１〜６の置換可能なヒドロキシアルキル基、炭素数１〜２０の置換可能なアルコキシル基、炭素数１〜６の置換可能なアルキルチオ基、アラルキルチオ基若しくはアリールチオ基、アミノ基、炭素数１〜６の置換可能なアルキルアミノ基、アラルキルアミノ基若しくはアリールアミノ基、ハロゲン原子、または炭素数７〜２０の置換可能なアリール基を示す。ｘは１〜６の整数であり、ｙは０〜２の整数であり、ｘが２以上である場合は、Ｒ^１は各々同一でも異なってもよい）

(In the general formula (4), R ¹ is a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, a hydroxyl group, a substitutable hydroxyalkyl group having 1 to 6 carbon atoms, or 1 carbon atom. ˜20 substitutable alkoxyl group, C 1-6 substitutable alkylthio group, aralkylthio group or arylthio group, amino group, C 1-6 substitutable alkylamino group, aralkylamino group or arylamino A group, a halogen atom, or a substitutable aryl group having 7 to 20 carbon atoms, x is an integer of 1 to 6, y is an integer of 0 to 2, and when x is 2 or more, R ¹ may be the same or different.

  The resist underlayer film composition of this embodiment can further improve etching resistance by the structural unit represented by the general formula (4) in the second resin.

In the general formula (4), R ¹ is, for example, methyl, ethyl, propyl, isopropyl, butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl Hydroxyl groups; hydroxyalkyl groups such as methylol, 2-hydroxyethyl, 3-hydroxypropyl; methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, tert-butoxy, pentyloxy, hexyloxy, heptyloxy Alkoxy groups such as octyloxy, nonyloxy, decyloxy, undecyloxy, dodecyloxy, tridecyloxy, tetradecyloxy, pentadecyloxy, pentadecyloxy; mercapto groups; Alkylthio groups such as methylthio, ethylthio, propylthio, butylthio, hexylthio; aralkylthio groups or arylthio groups optionally having substituents such as benzylthio, phenylthio;

  An amino group optionally having an alkyl group such as amino, methylamino, ethylamino, propylamino, isopropylamino, butylamino, hexylamino, dimethylamino, methylethylamino, diethylamino, dipropylamino, dibutylamino; benzyl; Aralkylamino group or arylamino group such as amino, benzhydryl, tritylamino, etc .; halogen atom such as fluorine, chlorine, iodine, etc .; having the above hydroxyl group, hydroxyalkyl group, alkoxyl group, mercapto group, alkylthio group, substituent An aralkylthio group or arylthio group, an amino group optionally having an alkyl group, an aralkylamino group, an arylamino group, etc., a phenyl group substituted with a halogen atom, an alkyl group, a group substituted with a phenyl group, etc., Feni , Naphthyl, anthryl, and the like aryl groups such as a methyl anthryl.

  Among these, hydroxyl group, methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, tert-butoxy, pentyloxy, hexyloxy, heptyloxy, octyloxy, nonyloxy, decyloxy, undecyloxy, dodecyloxy, tridecyloxy An alkoxyl group such as tetradecyloxy, pentadecyloxy, pentadecyloxy and the like is preferable, and a methoxy group, an ethoxy group, and a tert-butoxy group are more preferable.

  The reason is that when the second resin having an alkyl group, a hydroxyalkyl group, or an aryl group is polymerized, other substituents described above (substituents other than alkyl groups, hydroxyalkyl groups, and aryl groups) are used. The second resin having an alkylthio group, an aralkylthio group, an arylthio group, or a halogen atom may have other substituents (alkylthio group, aralkylthio group, arylthio group) as described above. And the second resin having an amino group, an aralkylamino group, or an arylamino group may have the above-mentioned other substituents (amino groups). , Aralkylamino groups, and substituents other than arylamino groups) There may be a case that reacts with acid (PAG) contained in the resist film.

  In the general formula (4), x is an integer of 1 to 6, and is preferably 1 or 2 and more preferably 2 from the viewpoint of obtaining a second resin having a narrow molecular weight distribution.

  In said general formula (4), y is an integer of 0-2. That is, the structural unit represented by the general formula (4) is derived from a phenyl derivative when y is “0”, derived from a naphthalene derivative when y is “1”, and y is “ “2” is derived from an anthracene derivative.

  In addition, the resin containing a nitrogen atom has a structure other than the structural unit represented by the above formulas (1), (2), and (3) and the structural unit represented by the above general formula (4). It may contain other structural units copolymerizable with the units. That is, the first resin contains other structural units copolymerizable with these structural units in addition to the structural units represented by the above formulas (1), (2), and (3). In addition to the structural units represented by the above formulas (1), (2), (3), and (4), the second resin may be other structural units copolymerizable with these structural units. May be contained.

  The second resin can be produced as follows, for example. That is, the second resin is obtained by coupling reaction of a phenyl derivative, a compound having a triazine structure, and a compound having an aldehyde group, for example, as in the method described in JP-A-8-311142. Can do. It can also be obtained by reacting a phenyl derivative with a glycoluril derivative represented by the above formula (7) under an acidic catalyst.

  In addition, since the resin containing a nitrogen atom contained in the resist underlayer film composition of the present embodiment is not particularly limited as long as it can constitute the structural unit represented by the general formula (4), Instead of the phenyl derivative, it can be synthesized using a naphthalene derivative or an anthracene derivative. Alternatively, the compound can be synthesized using a compound containing at least one selected from the group consisting of phenyl derivatives, naphthalene derivatives, and anthracene derivatives.

  The phenyl derivative is not particularly limited as long as it can constitute the structural unit represented by the general formula (4). For example, alkylphenols such as phenol, cresol, xylenol, ethylphenol, butylphenol, nonylphenol, octylphenol, etc. , Polyphenols such as bisphenol A, bisphenol F, bisphenol S, resorcin, and catechol, halogenated phenols, phenylphenol, aminophenol, and the like. In addition, these can be used individually or in mixture of 2 or more types.

  The naphthalene derivative is not particularly limited as long as it can constitute the structural unit represented by the general formula (4). For example, 1,3-dihydroxynaphthalene, 1,3-dimethoxynaphthalene, 1,3 -Di-tert-butoxynaphthalene, 2,3-dihydroxynaphthalene, 2,3-dimethoxynaphthalene, 2,3-di-tert-butoxynaphthalene, 2,4-dihydroxynaphthalene, 2,4-dimethoxynaphthalene, 2,4 -Di-tert-butoxynaphthalene, 2,5-dihydroxynaphthalene, 2,5-dimethoxynaphthalene, 2,5-di-tert-butoxynaphthalene, 2,6-dihydroxynaphthalene, 2,6-dimethoxynaphthalene, 2,6 -Di-tert-butoxynaphthalene, 2,7-dihydroxynaphthalene, 2 7-dimethoxynaphthalene, 2,7-di-tert-butoxynaphthalene, 2,8-dihydroxynaphthalene, 2,8-dimethoxynaphthalene, 2,8-di-tert-butoxynaphthalene, 2,2-bis {4- ( 6-hydroxy-2-naphthoxy) phenyl} propane, 2,2-bis {4- (6-hydroxy-2-naphthoxy) phenyl} -1,3-hexafluoropropane, and the like. In addition, these can be used individually or in mixture of 2 or more types.

  The anthracene derivative is not particularly limited as long as it can constitute the structural unit represented by the general formula (4). For example, 1-anthracene carboxylic acid, 2-anthracene carboxylic acid, 9-anthracene carboxylic acid 1,8-anthracene dicarboxylic acid dimethyl ester, 9,10-bis (3,5-dihydroxyphenyl) anthracene, 1,8-bis (hydroxymethyl) anthracene, 9,10-dibromoanthracene, 9,10-dichloroanthracene 9,10-dimethylanthracene, 9,10-diphenylanthracene, 9- (2-hydroxyethyl) anthracene, 2- (hydroxymethyl) anthracene, 9- (hydroxymethyl) anthracene, 9-methylanthracene, 9-phenylanthracene 1,8,9-to Hydroxy anthracene, and the like. In addition, these can be used individually or in mixture of 2 or more types.

  When a resin containing a nitrogen atom is synthesized using a compound containing at least one selected from the group consisting of a phenyl derivative, a naphthalene derivative, and an anthracene derivative, first, from the phenyl derivative, the naphthalene derivative, and the anthracene derivative A compound containing at least one selected from the group consisting of a compound having an aldehyde group and a compound having a triazine structure is mixed, and the temperature is 80 to 220 ° C., 1 to 12 hours, and the pH is 4 to 10 (preferably pH 5 to 9). React under conditions. In the above reaction, a catalyst may be used, and a basic catalyst is preferably used as the catalyst. Examples of the basic catalyst include ammonia, primary to tertiary amines, hexamethylenetetramine, and the like.

  In the above reaction, the reaction order (drop order) of each raw material is not particularly limited. First, at least one selected from the group consisting of a phenyl derivative, a naphthalene derivative, and an anthracene derivative is reacted with a compound having an aldehyde group. Thereafter, a compound having a triazine structure can be added to the reaction solution. Further, after reacting a compound having a triazine structure with a compound having an aldehyde group, at least one selected from the group consisting of a phenyl derivative, a naphthalene derivative, and an anthracene derivative may be added to the reaction solution. Furthermore, you may react by adding all the raw materials simultaneously.

  The molar ratio of the compound having an aldehyde group is preferably 0.2 to 0.9 with respect to the total amount “1” of the total amount of the phenyl derivative, naphthalene derivative, and anthracene derivative and the compound having a triazine structure. 0.4 to 0.8 is more preferable.

  Moreover, it is preferable that mass ratio of the total amount of a phenyl derivative, a naphthalene derivative, and an anthracene derivative and the compound which has a triazine structure is 10-98: 90-2, and it is 30-95: 70-5. Further preferred. If the total amount of the phenyl derivative, naphthalene derivative, and anthracene derivative is less than 10, it may be difficult to synthesize the resin.

  In the case of the said reaction, it can also carry out in presence of various reaction solvent from a viewpoint of controlling reaction. Examples of the reaction solvent include acetone, MEK (methyl ethyl ketone), toluene, xylene, methyl isobutyl ketone, ethyl acetate, ethylene glycol monomethyl ether, N, N-dimethylformamide, methanol, ethanol and the like. These reaction solvents can be used alone or in combination of two or more.

  Moreover, the reaction temperature in the above reaction is preferably 40 to 120 ° C, and more preferably 50 to 100 ° C. The reaction time is preferably 1 to 48 hours, and more preferably 1 to 24 hours.

  It is preferable that the resin containing a nitrogen atom has few impurities such as halogen and metal, and the residual monomer and oligomer components are not more than predetermined values. For example, the residual monomer or oligomer component measured by HPLC (high performance liquid chromatography) is preferably 0.1% by mass. There are few impurities and residual monomers and oligomer components are below the default value, which improves embedding, reduces the amount of sublimation during baking, and further improves coating properties and process stability. In addition to being able to do so, a resist underlayer film composition can be obtained in which the foreign matter present in the liquid is little changed with time.

  Examples of the method for purifying a resin containing a nitrogen atom include the following methods. As a method for removing impurities such as metal, the metal is chelated by washing the resin solution with an acidic aqueous solution such as oxalic acid or sulfonic acid, or by adsorbing the metal in the resin solution using a zeta potential filter. And the like.

  Methods for removing residual monomers and oligomer components below specified values include water-washing and liquid-liquid extraction methods that remove residual monomers and oligomer components by combining appropriate solvents, and those with specific molecular weights or less. A purification method in a solution state by ultrafiltration or the like that extracts and removes only the resin, coagulating the resin in the poor solvent by dripping the resin solution into the poor solvent, and a reprecipitation method for removing residual monomers, etc., and There is a purification method in a solid state, for example, by washing the filtered resin slurry with a poor solvent.

  The weight average molecular weight (Mw) of the second resin is preferably 1000-20000, more preferably 1000-7000, and particularly preferably 1000-5000. If the weight average molecular weight (Mw) is less than 1000, when the resist underlayer film is formed, low molecular components may volatilize from the resist underlayer film during baking, and the coating apparatus may be contaminated. On the other hand, if it exceeds 20000, the via hole embedding property required for the dual damascene process may be lowered.

  The ratio (Mw / Mn) between the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the second resin is preferably 7 or less. If the Mw / Mn is more than 7, applicability may be deteriorated.

  In addition, resin containing a nitrogen atom can be used individually or in mixture of 2 or more types.

[1-2] Solvent:
The solvent that can be contained in the resist underlayer film composition of the present embodiment is not particularly limited as long as it is a solvent for dissolving the resin containing the nitrogen atom. For example, ethylene glycol monomethyl ether, ethylene glycol Ethylene glycol monoalkyl ethers such as monoethyl ether, ethylene glycol mono-n-propyl ether, ethylene glycol mono-n-butyl ether; ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol mono-n-propyl ether Ethylene glycol monoalkyl ether acetates such as acetate and ethylene glycol mono-n-butyl ether acetate; diethylene glycol dimethyl ether and diethylene Recall diethyl ether, diethylene glycol di -n- propyl ether, diethylene glycol dialkyl ethers di -n- butyl ether and the like; triethylene glycol dimethyl ether, triethylene glycol dialkyl ethers such as triethylene glycol diethyl ether;

  Propylene glycol monoalkyl ethers such as propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-n-propyl ether, propylene glycol mono-n-butyl ether; propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol di-n Propylene glycol dialkyl ethers such as propyl ether and propylene glycol di-n-butyl ether; propylene glycol monomethyl ether acetate, propylene glycol monoether ether acetate, propylene glycol mono-n-propyl ether acetate, propylene glycol mono-n-butyl ether acetate Propylene glycol such as Roh alkyl ether acetates;

  Lactic acid esters such as methyl lactate, ethyl lactate, n-propyl lactate, i-propyl lactate, n-butyl lactate, i-butyl lactate; methyl formate, ethyl formate, n-propyl formate, i-propyl formate, n-formate Butyl, i-butyl formate, n-amyl formate, i-amyl formate, methyl acetate, ethyl acetate, n-propyl acetate, i-propyl acetate, n-butyl acetate, i-butyl acetate, n-amyl acetate, i -Amyl, n-hexyl acetate, methyl propionate, ethyl propionate, n-propyl propionate, i-propyl propionate, n-butyl propionate, i-butyl propionate, methyl butyrate, ethyl butyrate, n-propyl butyrate Aliphatic carboxylic acid esters such as i-propyl butyrate, n-butyl butyrate and i-butyl butyrate;

  Ethyl hydroxyacetate, ethyl 2-hydroxy-2-methylpropionate, methyl 3-methoxy-2-methylpropionate, methyl 2-hydroxy-3-methylbutyrate, ethyl methoxyacetate, ethyl ethoxyacetate, methyl 3-methoxypropionate , Ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, 3-methoxypropyl acetate, 3-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate, 3-methyl-3-methoxybutylpropionate, 3 -Other esters such as methyl-3-methoxybutyl butyrate, methyl acetoacetate, methyl pyruvate, ethyl pyruvate;

  Aromatic hydrocarbons such as toluene and xylene; ketones such as methyl ethyl ketone, methyl-n-propyl ketone, methyl-n-butyl ketone, 2-heptanone, 3-heptanone, 4-heptanone, cyclohexanone; N-methylformamide, N , N-dimethylformamide, N-methylacetamide, N, N-dimethylacetamide, N-methylpyrrolidone and other amides; γ-butyrolactone and other lactones.

  These solvents can be appropriately selected. Preferred are propylene glycol monomethyl ether, ethylene glycol monoethyl ether acetate, ethyl lactate, n-butyl acetate, ethyl 3-ethoxypropionate, methyl 3-methoxypropionate, 2-heptanone, cyclohexanone, γ-butyrolactone and the like. These solvents can be used alone or in admixture of two or more.

  Although the usage-amount of the said solvent is not specifically limited, It is preferable to use so that solid content concentration of the composition for resist lower layer films | membranes obtained may be 5-80 mass%, and it may become 5-40 mass%. It is more preferable to use it, and it is especially preferable to use it so that it may become 10-30 mass%. In general, the solid content concentration is preferably appropriately selected depending on the thickness of the resist underlayer film to be formed.

  The composition for a resist underlayer film of the present embodiment includes various additives such as an acid generator, a crosslinking agent, a radiation absorber, a surfactant, a storage stabilizer, an antifoaming agent, and an adhesion aid as necessary. Can be further blended. Among these additives, it is preferable to include at least one selected from the group consisting of an acid generator and a crosslinking agent.

[1-3] Acid generator:
The acid generator is a component that generates an acid upon exposure or heating. With this acid generator, acid is generated in the resist underlayer film by stimulation of light, heat, etc., and the acid (PAG) contained in the photoresist film formed on the resist underlayer film penetrates into the resist underlayer film by this acid. Can be prevented. Therefore, a good resist pattern can be formed.

  Examples of the acid generator that generates an acid upon exposure (hereinafter sometimes referred to as “photoacid generator”) include diphenyliodonium trifluoromethanesulfonate, diphenyliodonium nonafluoro-n-butanesulfonate, diphenyliodonium pyrenesulfonate, and diphenyl. Iodonium n-dodecylbenzenesulfonate, diphenyliodonium 10-camphorsulfonate, diphenyliodonium naphthalenesulfonate, diphenyliodonium hexafluoroantimonate, bis (4-t-butylphenyl) iodonium trifluoromethanesulfonate, bis (4-t-butylphenyl) iodonium Nonafluoro-n-butanesulfonate, bis (4-t-butylphenyl) iodonium n-dodecylbenzene Sulfonate, bis (4-tert-butylphenyl) iodonium 10-camphorsulfonate, bis (4-tert-butylphenyl) iodonium naphthalenesulfonate, bis (4-tert-butylphenyl) iodonium hexafluoroantimonate, triphenylsulfonium trifluoromethane Sulfonate, triphenylsulfonium nonafluoro-n-butanesulfonate, triphenylsulfonium n-dodecylbenzenesulfonate, triphenylsulfonium naphthalenesulfonate, triphenylsulfonium 10-camphorsulfonate, triphenylsulfonium hexafluoroantimonate, 4-hydroxyphenyl phenyl・ Methylsulfonium p-toluenesulfonate, 4-hydroxyphenyl benzyl Methyl sulfonium p- toluenesulfonate,

  Cyclohexyl methyl 2-oxocyclohexylsulfonium trifluoromethanesulfonate, 2-oxocyclohexyldicyclohexylsulfonium trifluoromethanesulfonate, 2-oxocyclohexyldimethylsulfonium trifluoromethanesulfonate, 1-naphthyldimethylsulfonium trifluoromethanesulfonate, 1-naphthyldiethylsulfonium trifluoromethanesulfonate 4-cyano-1-naphthyldimethylsulfonium trifluoromethanesulfonate, 4-cyano-1-naphthyldiethylsulfonium trifluoromethanesulfonate, 4-nitro-1-naphthyldimethylsulfonium trifluoromethanesulfonate, 4-nitro-1-naphthyldiethylsulfonium trifluoro Lome Sulfonate, 4-methyl-1-naphthyldimethylsulfonium trifluoromethanesulfonate, 4-methyl-1-naphthyldiethylsulfonium trifluoromethanesulfonate, 4-hydroxy-1-naphthyldimethylsulfonium trifluoromethanesulfonate, 4-hydroxy-1-naphthyldiethyl Sulfonium trifluoromethanesulfonate,

  1- (4-hydroxynaphthalen-1-yl) tetrahydrothiophenium trifluoromethanesulfonate, 1- (4-methoxynaphthalen-1-yl) tetrahydrothiophenium trifluoromethanesulfonate, 1- (4-ethoxynaphthalene-1- Yl) tetrahydrothiophenium trifluoromethanesulfonate, 1- (4-methoxymethoxynaphthalen-1-yl) tetrahydrothiophenium trifluoromethanesulfonate, 1- (4-ethoxymethoxynaphthalen-1-yl) tetrahydrothiophenium trifluoromethane Sulfonate, 1- [4- (1-methoxyethoxy) naphthalen-1-yl] tetrahydrothiophenium trifluoromethanesulfonate, 1- [4- (2-methoxyethoxy) naphthalene 1-yl] tetrahydrothiophenium trifluoromethanesulfonate, 1- (4-methoxycarbonyloxynaphthalen-1-yl) tetrahydrothiophenium trifluoromethanesulfonate, 1- (4-ethoxycarbonyloxynaphthalen-1-yl) tetrahydrothio Phenium trifluoromethanesulfonate, 1- (4-n-propoxycarbonyloxynaphthalen-1-yl) tetrahydrothiophenium trifluoromethanesulfonate,

  1- (4-i-propoxycarbonyloxynaphthalen-1-yl) tetrahydrothiophenium trifluoromethanesulfonate, 1- (4-n-butoxycarbonyloxynaphthalen-1-yl) tetrahydrothiophenium trifluoromethanesulfonate, 1 -(4-t-butoxycarbonyloxynaphthalen-1-yl) tetrahydrothiophenium trifluoromethanesulfonate, 1- [4- (2-tetrahydrofuranyloxy) naphthalen-1-yl] tetrahydrothiophenium trifluoromethanesulfonate, 1 -[4- (2-tetrahydropyranyloxy) naphthalen-1-yl] tetrahydrothiophenium trifluoromethanesulfonate, 1- (4-benzyloxy) tetrahydrothiophenium trifluoro Tan sulfonate, 1- (naphthyl acetamide methyl) onium salt photoacid generators such as tetrahydrothiophenium trifluoromethanesulfonate;

  Halogen-containing compound-based photoacid generators such as phenylbis (trichloromethyl) -s-triazine, 4-methoxyphenylbis (trichloromethyl) -s-triazine, 1-naphthylbis (trichloromethyl) -s-triazine; 2-naphthoquinonediazide-4-sulfonyl chloride, 1,2-naphthoquinonediazide-5-sulfonyl chloride, 1,3,4-naphthoquinonediazide-4-sulfonic acid ester of 2,3,4,4′-tetrahydroxybenzophenone or 1, Diazoketone compound photoacid generators such as 2-naphthoquinonediazide-5-sulfonic acid ester; sulfone compound photoacid generators such as 4-trisphenacylsulfone, mesitylphenacylsulfone, and bis (phenylsulfonyl) methane ;

  Benzoin tosylate, pyrogallol tris (trifluoromethanesulfonate), nitrobenzyl-9,10-diethoxyanthracene-2-sulfonate, trifluoromethanesulfonylbicyclo [2,2,1] hept-5-ene-2,3-di Examples thereof include sulfonic acid compound photoacid generators such as carbodiimide, N-hydroxysuccinimide trifluoromethanesulfonate, and 1,8-naphthalenedicarboxylic acid imide trifluoromethanesulfonate.

  Among the photoacid generators, diphenyliodonium trifluoromethanesulfonate, diphenyliodonium nonafluoro-n-butanesulfonate, diphenyliodonium pyrenesulfonate, diphenyliodonium n-dodecylbenzenesulfonate, diphenyliodonium 10-camphorsulfonate, diphenyliodonium naphthalenesulfonate, bis (4-t-butylphenyl) iodonium trifluoromethanesulfonate, bis (4-t-butylphenyl) iodonium nonafluoro-n-butanesulfonate, bis (4-t-butylphenyl) iodonium n-dodecylbenzenesulfonate, bis (4 -T-butylphenyl) iodonium 10-camphorsulfonate, bis (4-t-butylphenyl) io De iodonium naphthalene sulfonate, and the like are preferable. In addition, the said photo-acid generator can be used individually or in mixture of 2 or more types.

  Examples of the acid generator that generates an acid by heating (hereinafter sometimes referred to as “thermal acid generator”) include 2,4,4,6-tetrabromocyclohexadienone, benzoin tosylate, 2- Examples thereof include nitrobenzyl tosylate and alkyl sulfonates. These thermal acid generators can be used alone or in admixture of two or more. A photo acid generator and a thermal acid generator can be used in combination.

  The amount of the acid generator used is preferably 5000 parts by mass or less, more preferably 0.1 to 1000 parts by mass, and more preferably 0.1 to 100 parts by mass with respect to 100 parts by mass of the resin containing nitrogen atoms. The part by mass is particularly preferred.

[1-4] Crosslinking agent:
The crosslinking agent is a component having an action of preventing cracking of the resist underlayer film in addition to preventing intermixing between the resist underlayer film and the photoresist film. Examples of such a crosslinking agent include polynuclear phenols and curing agents.

  Examples of polynuclear phenols include dinuclear phenols such as 4,4′-biphenyldiol, 4,4′-methylene bisphenol, 4,4′-ethylidene bisphenol, and bisphenol A; 4,4 ′, 4 ″ -methyl Trinuclear phenols such as reddentrisphenol, 4,4 ′-[1- {4- (1- [4-hydroxyphenyl] -1-methylethyl) phenyl} ethylidene] bisphenol; polyphenols such as novolac Among these polynuclear phenols, 4,4 ′-[1- {4- (1- [4-hydroxyphenyl] -1-methylethyl) phenyl} ethylidene] bisphenol, novolak, polyhydroxystyrene, etc. These polynuclear phenols may be used alone or in combination of two or more. To be used.

  Examples of the curing agent include 2,3-tolylene diisocyanate, 2,4-tolylene diisocyanate, 3,4-tolylene diisocyanate, 3,5-tolylene diisocyanate, and 4,4′-diphenylmethane diester. Diisocyanates such as isocyanate, hexamethylene diisocyanate, 1,4-cyclohexane diisocyanate can be mentioned.

  Various commercially available curing agents can be used. Specifically, Epicoat 812, 815, 826, 828, 834, 836, 836, 871, 1001, 1004, 1007, 1009, 1031 Shell Epoxy), Araldite 6600, 6700, 6800, 502, 6071, 6084, 6084, 6097, 6099 (above, Ciba Geigy), DER331, 332, 333, 661, 644 667 (above, manufactured by Dow Chemical Co., Ltd.); Cymel 300, 301, 303, 350, 370, 771, 325, 327, 703, 712, 701, 701, etc. 272, 202, My Coat 506, 508 (above, manufactured by Mitsui Cyanamid Co., Ltd.) and the like; Cymel 1123 Benzoguanamine-based curing agents such as 1123-10, 1128, Mycoat 102, 105, 106, 130 (above, Mitsui Cyanamid); Cymel 1170, 1172 (above, Mitsui Cyanamid), Nicalack Examples include glycoluril-based curing agents such as N-2702 (manufactured by Sanwa Chemical Co., Ltd.).

  Of these curing agents, melamine curing agents, glycoluril curing agents and the like are preferable. These curing agents can be used alone or in admixture of two or more. Moreover, polynuclear phenols and a hardening | curing agent can also be used together as a crosslinking agent.

  The amount of the crosslinking agent used is preferably 50 parts by mass or less, and more preferably 20 parts by mass or less, with respect to 100 parts by mass of the resin containing nitrogen atoms.

  Examples of the radiation absorber include oil-soluble dyes, disperse dyes, basic dyes, methine dyes, pyrazole dyes, imidazole dyes, hydroxyazo dyes, and the like; bixin derivatives, norbixine, stilbene, 4,4 Fluorescent brighteners such as' -diaminostilbene derivatives, coumarin derivatives, pyrazoline derivatives; hydroxyazo dyes, UV absorbers such as Ciba Geigy's trade name "Tinuvin 234", Ciba Geigy's trade name "Tinuvine 1130" And aromatic compounds such as anthracene derivatives and anthraquinone derivatives. In addition, these radiation absorbers can be used individually or in mixture of 2 or more types.

  The amount of the radiation absorber used is preferably 30 parts by mass or less, and more preferably 10 parts by mass or less, with respect to 100 parts by mass of the resin containing nitrogen atoms.

  The surfactant is a component having an effect of improving coatability, striation, wettability, developability and the like. Examples of such surfactants include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene-n-octylphenyl ether, polyoxyethylene-n-nonylphenyl ether, and polyethylene. Nonionic surfactants such as glycol dilaurate and polyethylene glycol distearate, and the following trade names, KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.), Polyflow No. 75, no. 95 (above, manufactured by Kyoeisha Yushi Chemical Co., Ltd.), Ftop EF101, EF204, EF303, EF352 (above, manufactured by Tochem Products), MegaFuck F171, F172, F173 (above, Dainippon Ink and Chemicals, Inc.) (Manufactured by Kogyo Co., Ltd.), FLORARD FC430, FC431, FC135, FC135, FC93 (above, manufactured by Sumitomo 3M), Asahi Guard AG710, Surflon S382, SC101, SC102, SC103, SC104, SC105, SC106 ( As mentioned above, Asahi Glass Co., Ltd.) can be mentioned. In addition, these surfactant can be used individually or in mixture of 2 or more types.

  The amount of the surfactant used is preferably 15 parts by mass or less and more preferably 10 parts by mass or less with respect to 100 parts by mass of the resin containing nitrogen atoms.

[2] Method for producing resist underlayer film composition:
The method for producing the resist underlayer film composition of the present embodiment is not particularly limited, but when it contains the above-described resin containing a nitrogen atom and the above-mentioned solvent, for example, it can be produced as follows. it can. First, the above solvent is added to the resin containing nitrogen atoms (the nitrogen atom content is 10% by mass or more) and the additive, and the solid content concentration thereof, that is, the solid content concentration of the resist underlayer film composition is 5. Adjust to ˜50 mass%. At this time, the usage-amount of the said resin is adjusted so that the content rate of the nitrogen atom in the resist underlayer film to form may be 10 mass% or more. Then, what is obtained by filtering with a filter having a pore size of about 0.1 μm can be used as a resist underlayer film composition.

[3] Method for forming dual damascene structure:
One embodiment of the method for forming a dual damascene structure of the present invention uses a photoresist film, which is disposed on a resist underlayer film formed by the above-described resist underlayer film composition and has a resist pattern formed thereon, as a mask. The process of transferring the resist pattern of the resist film to the resist underlayer film by etching (first transfer process), and using the resist underlayer film to which the resist pattern of the photoresist film is transferred as a mask, is placed under the resist underlayer film. A process of transferring the resist pattern of the resist underlayer film to the low dielectric insulating film (second transfer process), and a process of transferring the resist pattern of the resist underlayer film to the low dielectric insulating film and then removing the resist underlayer film by plasma ashing (Underlayer film removal step).

  The dual damascene structure forming method of the present embodiment uses the above-described resist underlayer film composition to form a dual damascene structure (dual damascene structure) with a good resist pattern and low damage to the low dielectric insulating film. Can be formed.

[3-1] First transfer step:
The dual damascene structure forming method of the present embodiment is a method in which a photoresist is first formed using a photoresist film, which is placed on a resist underlayer film formed by the above-described resist underlayer film composition and on which a resist pattern is formed, as a mask. The resist pattern of the film is transferred to the resist underlayer film by etching.

  The photoresist film is not particularly limited as long as it is disposed on the resist underlayer film formed by the above-described resist underlayer film composition and a resist pattern is formed, but a resist composition capable of forming a photoresist film It is preferable that it is formed by. Examples of the resist composition include a positive or negative chemically amplified resist composition containing a photoacid generator, a positive resist composition comprising an alkali-soluble resin and a quinonediazide-based photosensitizer, and an alkali-soluble resin. Examples thereof include a negative resist composition comprising a crosslinking agent. There is no restriction | limiting in particular in the method of arrange | positioning the said photoresist film on a resist underlayer film, For example, it can carry out by the spin coat method.

  Specifically, the resist composition can be applied onto the resist underlayer film by a spin coating method, and then prebaked to volatilize the solvent in the coating film. The pre-baking temperature is appropriately adjusted according to the type of resist composition used and the like, but is preferably 30 to 200 ° C, and more preferably 50 to 150 ° C.

  The film thickness of the photoresist film is preferably 100 to 20000 nm, and more preferably 100 to 200 nm.

  The photoresist film formed by the resist composition is a photolithography having a resist process that is disposed on the resist underlayer film by the above-described spin coating method or the like, and then undergoes processes such as radiation irradiation (exposure process) and development. Thus, a resist pattern can be formed.

The exposure process of the resist process is a process of irradiating the photoresist film with radiation through a mask (reticle) on which a device design is depicted. The radiation used in this exposure step is appropriately selected from visible light, ultraviolet light, far ultraviolet light, X-rays, electron beams, gamma rays, molecular beams, ion beams, etc., depending on the type of photoacid generator contained in the photoresist film. You can choose. Far ultraviolet rays are preferable, and in particular, KrF excimer laser (248 nm), ArF excimer laser (193 nm), F ₂ excimer laser (wavelength 157 nm), Kr ₂ excimer laser (wavelength 147 nm), ArKr excimer laser (wavelength 134 nm), pole Ultraviolet light (wavelength 13 nm or the like) is preferred.

  The developer used for the development of the resist process is appropriately selected according to the type of the resist composition, and the development used for the positive chemically amplified resist composition or the positive resist composition containing an alkali-soluble resin. Examples of the liquid include sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, dimethyl / ethanol. Amine, triethanolamine, tetramethylammonium hydroxide, tetraethylammonium hydroxide, pyrrole, piperidine, choline, 1,8-diazabicyclo [5.4.0] -7-undecene, 1,5-diazabicyclo [4.3. 0]- - it can be mentioned alkaline aqueous solution such as nonene. In addition, an appropriate amount of a water-soluble organic solvent, for example, an alcohol such as methanol or ethanol, or a surfactant can be added to these alkaline aqueous solutions.

  The thickness of the resist underlayer film is not particularly limited, but is preferably 100 to 2000 nm, more preferably 200 to 1000 nm, and particularly preferably 200 to 500 nm. If the film thickness of the resist underlayer film is less than 100 nm, the resist underlayer film is not thick enough as a mask for processing the substrate, and the substrate may not be processed. On the other hand, if it exceeds 2000 nm, the aspect ratio (aspect ratio) of the patterned resist underlayer film (pattern portion of the resist underlayer film on which the resist pattern is formed) described later becomes too large, and the patterned resist The lower layer film may collapse.

Subsequently, using the photoresist film as a mask, the resist pattern of the photoresist film is transferred to the resist underlayer film by etching. Etching is not particularly limited, and may be either dry etching or wet etching, and can be performed by a conventionally known method. For example, as a source gas in dry etching, for example, a gas containing oxygen atoms such as O ₂ , CO, and CO ₂ , an inert gas such as He, N ₂ , and Ar, a chlorine-based gas such as Cl ₂ and BCl ₂ , It may be used and other _{H 2,} NH 2. In addition, these gases can also be mixed and used.

[3-2] Second transfer step:
Next, the dual damascene structure forming method of this embodiment is disposed under the resist underlayer film using the resist underlayer film to which the resist pattern of the photoresist film is transferred as a mask in the first transfer step. The resist pattern of the resist underlayer film is transferred to the low dielectric insulating film.

  The type of the low dielectric insulating film (Low-k film) is not particularly limited as long as it is disposed under the resist underlayer film. For example, silicon oxide, silicon nitride, silicon oxynitride, polysiloxane, etc. An insulating film formed by the above can be given. Specifically, those formed by black diamond (manufactured by AMAT), silk (manufactured by Dow Chemical Co., Ltd.), LKD5109 (manufactured by JSR) and the like can be used under the trade names.

  The low dielectric insulating film is, for example, a film formed so as to cover a substrate such as a wafer, and the formation method is not particularly limited, and can be performed by a known method. For example, it can be formed by a coating method (SOD: Spin On Dielectric) or a chemical vapor deposition (CVD) method. In the dual damascene structure forming method of the present embodiment, a resist underlayer film is disposed on the low dielectric insulating film formed as described above. The method of disposing the resist underlayer film is not particularly limited, and examples thereof include a method of forming the resist underlayer film on the low dielectric insulating film by spin coating using the above-described resist underlayer film composition.

  Subsequently, the resist pattern formed on the resist underlayer film is transferred to the low dielectric insulating film. The method for transferring the resist pattern is not particularly limited, and can be performed by the etching described above.

[3-3] Lower layer removal process:
Next, in the method of forming the dual damascene structure of the present embodiment, after the resist pattern of the resist underlayer film is transferred to the low dielectric insulating film by the second transfer step, the resist underlayer film is removed by plasma ashing.

  In the method of forming the dual damascene structure of the present embodiment, since the resist underlayer film to be used contains 10% by mass or more of nitrogen atoms, the ashing process expected from the Onishi parameter of the resist underlayer film at the time of removal by plasma ashing It can be removed faster than the speed. Therefore, damage due to plasma ashing to the low dielectric insulating film disposed under the resist underlayer film can be suppressed.

Here, plasma ashing is removal of a mask made of an organic substance (for example, a resist underlayer film or a photoresist film) with a reactive gas plasma after dry etching, for example, a reactive gas plasma such as oxygen plasma is removed. Generating and decomposing and removing the mask into CO _x , H ₂ O and the like in the gas phase.

  The plasma ashing conditions are not particularly limited as long as the resist underlayer film can be removed. For example, the high frequency power applied to the susceptor is preferably 100 to 1000 W, and more preferably 100 to 500 W. Preferably, the susceptor temperature is preferably 20 to 100 ° C, more preferably 20 to 60 ° C. The pressure in the processing container is preferably 0.133 to 39.9 Pa, and more preferably 3.99 to 13.3 Pa.

  The gas used for plasma ashing is not particularly limited as long as the resist underlayer film can be removed, but from the viewpoint that it is possible to suppress an increase in the relative dielectric constant of the low dielectric insulating film due to ashing, for example, A gas containing at least one selected from the group consisting of nitrogen, hydrogen, ammonia, and argon is preferable. Moreover, when using the mixed gas of nitrogen and hydrogen, it is preferable that hydrogen is 0-20 with respect to nitrogen 100 by a volume ratio, and it is still more preferable that hydrogen is 1-10. Moreover, when using the mixed gas of ammonia and argon, it is preferable that argon is 0-10 with respect to ammonia 100 by a volume ratio. The resist underlayer film can be more efficiently removed by such mixed gas plasma. Moreover, it is also preferable that it is a mixed gas of ammonia, nitrogen, and hydrogen.

[3-4] Other steps:
After developing the exposed photoresist film, the photoresist film is preferably washed and dried. Further, in order to improve resolution, pattern profile, developability, etc., post-baking can be performed after exposure and before development.

  An intermediate layer can be formed between the photoresist film and the resist underlayer film. The intermediate layer means a resist underlayer film, a photoresist film, and a layer having a function that is insufficient for both in forming a resist pattern. For example, when the resist underlayer film lacks an antireflection function, a film having an antireflection function can be applied to the intermediate layer. As the material of the intermediate layer, an organic compound or an inorganic oxide is appropriately selected depending on a required function. For example, when the photoresist film is an organic compound, an inorganic oxide can be applied to the intermediate layer.

  The intermediate layer made of an organic compound is commercially available, for example, all trade names such as “DUV-42”, “DUV-44”, “ARC-28”, “ARC-29”, etc., manufactured by Brewer Science. By name, it can be formed by “AR-3”, “AR-19”, etc. manufactured by Rohm and Haas. In addition, the intermediate layer made of inorganic oxide is polysiloxane, titanium oxide, alumina oxide, tungsten oxide, and commercially available products such as “NFC SOG01” and “NFC SOG04” manufactured by JSR. And can be formed by a CVD method.

  As a method for forming the intermediate layer, a coating method, a CVD method, or the like can be used, but a coating method is preferable. This is because, in the case of the coating method, the intermediate layer can be continuously formed after the resist underlayer film is formed, but cannot be continuously formed by the CVD method.

  The thickness of the intermediate layer can be appropriately selected depending on the function required for the intermediate layer, but is preferably 10 to 3000 nm, and more preferably 20 to 300 nm. If the thickness of the intermediate layer is less than 10 nm, the intermediate layer may be scraped off during the etching of the resist underlayer film. On the other hand, when it exceeds 3000 nm, there is a possibility that a difference in processing conversion may occur remarkably when the resist pattern of the photoresist film is transferred to the intermediate layer.

  An embodiment of the method for forming a dual damascene structure of the present invention will be described more specifically.

  In FIG. 1, a first low dielectric insulating film 2 is formed on a substrate 1, and a resist underlayer film 3 formed on the first low dielectric insulating film 2 is subjected to a dry etching method to form a resist pattern of a photoresist film. Is an example in which

  Since the method for forming the dual damascene structure of the present embodiment uses the resist underlayer film formed by the resist underlayer film composition of the present embodiment described above, the etching resistance is good, and the resist pattern is good for the resist underlayer film 3. Can be transferred to.

  After the resist pattern is transferred to the resist underlayer film, a resist pattern (trench) is formed in the first low dielectric insulating film 2 using the resist underlayer film 3 as a mask, as shown in FIG. The resist pattern of the low dielectric insulating film is formed by removing the portion of the low dielectric insulating film corresponding to the resist pattern by reactive ion etching. FIG. 3 shows an example in which the resist underlayer film 3 is removed by plasma ashing after a resist pattern is formed on the dielectric insulating film 2.

  If necessary, a barrier metal film can be formed on the low dielectric insulating film. FIG. 4 shows an example in which a trench (wiring groove) 4 is formed and a barrier metal 5 is deposited on the surface of the first low dielectric insulating film 2 in which the wiring groove 4 is formed. When a barrier metal (barrier metal film) is formed, in addition to improving the adhesion between the copper buried in the wiring trench and the low dielectric insulating film, copper is prevented from diffusing into the low dielectric insulating film. be able to.

  Thereafter, copper can be embedded in the wiring trench by copper electrolytic plating or the like to form a lower copper wiring layer. The low dielectric insulating film on which the resist pattern is formed is not limited to a single layer, and may be a multilayer in which a plurality of low dielectric insulating films are stacked. FIG. 5 shows that copper is buried in the wiring groove 4 by copper electrolytic plating to form a lower copper wiring layer 6, and the copper adhering to the surface of the first low dielectric insulating film 2 and the barrier metal 5 are chemically treated. After removing by polishing (CMP) and flattening the surface of the first low dielectric insulating film 2, the second low dielectric insulating film 7 and the first low dielectric insulating film 2 are sequentially formed on the first low dielectric insulating film 2. The etching stopper film 8, the third low dielectric insulating film 9, and the second etching stopper film 10 are formed in a laminated form, and a resist pattern is formed on the resist underlayer film 11 on the etching stopper film 10 that is the uppermost layer. It is an example.

  Thereafter, as shown in FIG. 6, the second etching stopper film 10, the third low dielectric insulating film 9, the first etching stopper layer 8, and the first etching stopper film 11 are formed by reactive ion etching using the resist lower layer film 11 as a mask. A via hole (resist pattern) 12 that penetrates through the second low dielectric insulating film 7 and reaches the surface of the lower wiring layer 6 is formed, and then the resist lower layer film is removed by plasma ashing.

  After removing the resist underlayer film by plasma ashing, as shown in FIG. 7, the resist underlayer film composition is filled so as to fill the via hole 12, and the second etching stopper 10 (the uppermost layer of the laminate) is filled. And a resist pattern is formed on the resist underlayer film 13 again.

  After the resist pattern is formed on the resist underlayer film 13, the second etching stopper film 10 and the third low dielectric insulating material are formed by reactive ion etching using the resist pattern of the resist underlayer film 13 as a mask as shown in FIG. The film 9 is etched to form a trench (resist pattern) 14.

  After the trench (resist pattern) 14 is formed, the resist underlayer film 13 is removed by plasma ashing. In FIG. 9, the resist underlayer film embedded in the via hole 12 by ashing and the resist underlayer film disposed on the etching stopper film 10 are completely removed to form a dual damascene structure having the via hole 12 and the trench 14. It is an example.

  After the dual damascene structure is formed as described above, the barrier metal 15 is formed in the via hole 12 and the trench 14 as shown in FIG. The upper copper wiring layer 17 can be formed simultaneously.

  Note that the dual damascene structure is not limited to be formed by the via first, but can be formed by a trench first. Various multilayer wiring structures can be formed by sequentially repeating the above process.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples. In the examples and comparative examples, “parts” and “%” are based on mass unless otherwise specified.

(Reference Example 1)
[Preparation of resist composition solution]:
In a separable flask equipped with a reflux tube, 8-methyl-8-t-butoxycarbonylmethoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] dodec-3-ene 29 parts, 8-methyl-8-hydroxytetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] 10 parts dodec-3-ene, 18 parts maleic anhydride, 4 parts 2,5-dimethyl-2,5-hexanediol diacrylate, 1 part t-dodecyl mercaptan, azobisisobutyronitrile 4 Part and 60 parts of 1,2-diethoxyethane as a monomer component, polymerized at 70 ° C. for 6 hours with stirring, and a polymer having the following repeating units (a), (b), and (c) (Hereinafter, referred to as “photoresist polymer” in some cases) was obtained. Thereafter, this reaction solution was poured into a large amount of a mixed solvent of n-hexane / i-propyl alcohol (mass ratio = 1/1) to solidify the photoresist polymer in the reaction solution. The coagulated photoresist polymer was washed several times with the above mixed solvent. Then, it was made to vacuum-dry and the photoresist polymer was obtained (yield 60%). In this photoresist polymer, the molar ratio of the repeating units (a), (b), and (c) was 64:18:18, and Mw was 27,000.

  80 parts of the resulting photoresist polymer, 1.5 parts of 1- (4-methoxynaphthalen-1-yl) tetrahydrothiophenium nonafluoro-n-butanesulfonate and 0.04 part of tri-n-octylamine are propylene. A mixed solution obtained by dissolving in 533 parts of glycol monomethyl ether acetate was used as a resist composition solution.

[Measurement of molecular weight]:
The weight average molecular weight (Mw) of the photoresist polymer obtained in Reference Example 1 and the weight average molecular weights (Mw) of the resins (A-1) to (A-7) obtained in the following synthesis examples. And the number average molecular weight (Mn) are GPC columns (G2000HXL: 2, G3000HXL: 1) manufactured by Tosoh Corporation, flow rate: 1.0 ml / min, elution solvent: tetrahydrofuran, column temperature: 40 ° C. Under conditions, measurement was performed by a gel permeation chromatograph (detector: differential refractometer) using monodispersed polystyrene as a standard.

[Measurement of nitrogen atom content in resin]:
The nitrogen atom content (% by mass) of the resins (A-1) to (A-7) obtained in each of the following synthesis examples was determined using an organic element analyzer (trade name “CHN Coder JM10” manufactured by J Science). )).

(Synthesis Example 1)
[Synthesis of Resin (A-1)]:
To 100 parts of phenol, 30 parts of 40% formalin and 0.47 part of triethylamine were added and reacted at 80 ° C. for 3 hours. Next, 30 parts of melamine was added and reacted for another 2 hours. After the reaction, the temperature was raised to 180 ° C. over 2 hours while removing water under normal pressure. Next, unreacted phenol was removed under reduced pressure to obtain a resin (A-1) containing a nitrogen atom (hereinafter sometimes referred to as “resin (A-1)”). This resin (A-1) had Mw of 4500, Mw / Mn of 1.80, and a nitrogen atom content of 10% by mass.

(Synthesis Example 2)
[Synthesis of Resin (A-2)]:
Except for using 50 parts of melamine, a compound (A-2) containing nitrogen atoms, which was a yellowish white powder, was obtained in the same manner as in Synthesis Example 1 with the formulation shown in Table 1 (hereinafter referred to as “resin”). (A-2) "may be indicated). This resin (A-2) had Mw of 4100, Mw / Mn of 2.10, and a nitrogen atom content of 14% by mass.

(Synthesis Example 3)
[Synthesis of Resin (A-3)]:
Except that 70 parts of melamine was used, a resin (A-3) containing nitrogen atoms, which was a yellowish white powder, was obtained in the same manner as in Synthesis Example 1 except that 70 parts of melamine was used (hereinafter referred to as “resin”). (A-3) ”in some cases). This resin (A-3) had Mw of 3900, Mw / Mn of 2.20, and a nitrogen atom content of 21% by mass.

(Synthesis Example 4)
[Synthesis of Resin (A-4)]:
To 100 parts of 1-naphthol, 30 parts of 40% formalin and 0.47 parts of triethylamine were added and reacted at 80 ° C. for 3 hours. Next, 40 parts of melamine was added and reacted for another 2 hours. After the reaction, the temperature was raised to 180 ° C. over 2 hours while removing water under normal pressure. Subsequently, unreacted 1-naphthol was removed under reduced pressure to obtain a resin (A-4) containing a nitrogen atom (hereinafter sometimes referred to as “resin (A-4)”). This resin (A-4) had Mw of 5100, Mw / Mn of 2.20, and a nitrogen atom content of 15% by mass.

(Synthesis Example 5)
[Synthesis of Resin (A-5)]:
Except for using 70 parts of melamine, a compound (A-5) containing nitrogen atoms, which was a yellowish white powder, was obtained in the same manner as in Synthesis Example 4 with the formulation shown in Table 1 (hereinafter referred to as “resin”). (A-5) "may be indicated). This resin (A-5) had Mw of 3900, Mw / Mn of 2.30, and a nitrogen atom content of 19% by mass.

(Synthesis Example 6)
[Synthesis of Resin (A-6)]:
To 100 parts of 1,8-hydroxyanthracene, 30 parts of 40% formalin and 0.47 part of triethylamine were added and reacted at 80 ° C. for 3 hours. Next, 60 parts of benzoguanamine was added, and the mixture was further reacted for 2 hours. After the reaction, the temperature was raised to 180 ° C. over 2 hours while removing water under normal pressure. Next, unreacted 1,8-hydroxyanthracene was removed under reduced pressure to obtain a resin (A-6) containing a nitrogen atom (hereinafter sometimes referred to as “resin (A-6)”). This resin (A-6) had Mw of 5200, Mw / Mn of 3.30, and a nitrogen atom content of 18% by mass.

(Synthesis Example 7)
[Synthesis of Resin (A-7)]:
100 parts of 1-naphthol, 200 parts of tetramethoxymethyl glycoluril, and 3 parts of oxalic acid were dissolved in 900 parts of methyl isobutyl ketone, and then reacted at 80 ° C. for 5 hours. After the reaction, water was added to the reaction solution, and washing was performed until the aqueous layer became neutral. Next, unreacted 1-naphthol and the solvent were removed under reduced pressure to obtain a resin (A-7) containing a nitrogen atom (hereinafter sometimes referred to as “resin (A-7)”). This resin (A-7) had Mw of 1300, Mw / Mn of 1.50, and a nitrogen atom content of 16% by mass.

Example 1
[Preparation of composition for resist underlayer film]:
10 parts of the resin (A-1), 0.5 part of bis (4-t-butylphenyl) iodonium nonafluoro-n-butanesulfonate (shown as “C-1” in Table 2) as an acid generator, and crosslinking As an agent, 0.5 part of tetramethoxymethylglycoluril (shown by the following formula (8), shown as “D-1” in Table 2) is mixed with propylene glycol monomethyl acetate (“B-1” in Table 2) as a solvent. It was dissolved in 89 parts to obtain a mixed solution. Then, what was obtained by filtering this mixed solution with a membrane filter with a pore diameter of 0.1 μm was used as a resist underlayer film composition. This composition for resist underlayer film was used as a coating solution for various evaluations shown below.

[Measurement of nitrogen atom content in resist underlayer]:
First, a resist underlayer film composition was spin-coated on a silicon wafer having a diameter of 8 inches. After spin coating, heating was performed at 180 ° C. for 60 seconds, and then further heating on a hot plate at 250 ° C. for 60 seconds to obtain a resist underlayer film having a thickness of 300 nm. About the obtained resist lower layer film | membrane, the content rate (mass%) of each atom of carbon, hydrogen, oxygen, and nitrogen was measured. Each content rate was measured using an organic element analyzer (trade name “CHN Coder JM10”) manufactured by J-Science. In Table 4, “nitrogen content” indicates this evaluation.

[Onishi Parameter]:
As a result of the measurement of the content of nitrogen atoms in the resist underlayer film, the Onishi parameter of the resist underlayer film was calculated from the content of each element in the resist underlayer film by the following formula (i).
(I): NT / {NC-NO- (2 × NX)}
(In the above formula (i), NT is the total number of atoms, NC is the number of carbon atoms, NO is the number of oxygen atoms, and NX is the number of halogen atoms.)

[Embedding properties in vias]:
The via embedding property was evaluated as to whether or not the obtained composition for resist underlayer film satisfactorily penetrated into the via hole and satisfactorily buried. Evaluation of the embedding property in the via was performed by the following method.

  First, a resist underlayer film composition was spin-coated on a tetraethylorthosilicate (TEOS) substrate processed so as to form a via hole having a via size of 140 nm, a via pitch of 1H / 1.2S, and a depth of 1000 nm. After spin coating, it was heated at 180 ° C. for 60 seconds, and then further heated on a hot plate at 250 ° C. for 60 seconds. In this way, a resist underlayer film having a thickness of 300 nm was formed in the via hole and on the TEOS surface. The prepared resist underlayer film was evaluated by observing the embedded state in the via hole with a scanning electron microscope. The evaluation criteria were good (“◯”) when the resist underlayer film was formed in the via hole (when embedded), and defective (“×”) when not embedded. In Table 4, “embeddability” indicates this evaluation.

[Pattern shape after development]:
First, a resist underlayer film composition was spin-coated on a silicon wafer having a diameter of 8 inches. After spin coating, it was heated at 180 ° C. for 60 seconds, and then further heated on a hot plate at 250 ° C. for 60 seconds to obtain a resist underlayer film having a thickness of 300 nm. Thereafter, an intermediate layer composition solution for a three-layer resist process (trade name: NFC SOG050, manufactured by JSR) was spin-coated on the resist underlayer film. After spin coating, the film was heated at 200 ° C. for 60 seconds, and then further heated on a hot plate at 250 ° C. for 60 seconds to form an intermediate layer film having a thickness of 50 nm. Thereafter, the resist composition solution obtained in Reference Example 1 was spin-coated on this intermediate layer film, and pre-baked on a hot plate at 130 ° C. for 90 seconds to form a 200 nm-thick photoresist film. Thereafter, the photoresist film was exposed for an optimal exposure time through a mask pattern using an ArF excimer laser exposure apparatus (lens numerical aperture 0.78, exposure wavelength 193 nm) manufactured by NIKON. Then, after post-baking on a hot plate at 130 ° C. for 90 seconds, using a 2.38 mass% aqueous tetramethylammonium hydroxide solution, developing at 25 ° C. for 1 minute, washing with water and drying, the photoresist A positive resist pattern was formed on the film.

  In order to evaluate the function of the resist underlayer film formed from the resist underlayer film composition as an antireflection film, the pattern shape of the positive resist pattern of the photoresist film was observed and evaluated with a scanning electron microscope. The evaluation criteria were good (“◯”) when the pattern shape was rectangular, and bad (“×”) when it was not. In Table 4, “resist shape” indicates this evaluation.

[Standing wave prevention effect]:
In addition, in order to evaluate the function of the resist underlayer film formed from the resist underlayer film composition as an antireflection film, the presence or absence of the influence of the standing wave of the positive resist pattern was observed and evaluated with a scanning electron microscope. . As the evaluation criteria, a case where there was no standing wave was judged as good (“◯”), and a case where there was no standing wave was judged as bad (“×”). In Table 4, “Standing wave prevention effect” indicates this evaluation.

[Etching resistance]:
The pattern transfer performance and etching resistance of the resist underlayer film formed from the resist underlayer film composition were evaluated by the following methods. First, a resist underlayer film having a film thickness of 300 nm was formed by spin coating. Thereafter, the resist underlayer film was etched (pressure: 0.03 Torr, high frequency power: 3000 W, Ar / CF ₄ = 40/100 sccm, substrate temperature: 20 ° C.), and the thickness of the resist underlayer film after the etching treatment was measured. . The etching rate (nm / min) was calculated from the relationship between the amount of decrease in film thickness and the processing time.

[NH ₃ peelability]:
The peelability of the resist underlayer film by plasma ashing using NH ₃ gas was performed by the following evaluation method. First, a resist underlayer film having a film thickness of 300 nm was formed by spin coating. Thereafter, plasma ashing (pressure: 0.1 Torr, high frequency power: 550 W, NH ₃ = 150 sccm, substrate temperature: 20 ° C.) was performed, and the film thickness of the resist underlayer film after the plasma ashing was measured. The etching rate (nm / min) was calculated from the relationship between the amount of decrease in film thickness and the processing time. In Table 4, “NH ₃ peelability” indicates this evaluation.

[O ₂ peelability]:
The peelability of the resist underlayer film by plasma ashing using O ₂ gas was performed by the following evaluation method. First, a resist underlayer film having a film thickness of 300 nm was formed by spin coating. Thereafter, plasma ashing (pressure: 0.1 Torr, high frequency power: 550 W, O ₂ = 150 sccm, substrate temperature: 20 ° C.) was performed, and the film thickness of the resist underlayer film after the plasma ashing was measured. The etching rate (nm / min) was calculated from the relationship between the amount of decrease in film thickness and the processing time. In Table 4, “O ₂ peelability” indicates this evaluation.

The resist underlayer film formed from the resist underlayer film composition of this example has a nitrogen content of 10% by mass, an Onishi parameter of 2.7, a via embedding property of “◯”, and development. The subsequent pattern shape is “◯”, the standing wave prevention effect is “◯”, the etching rate in etching resistance is 67 nm / min, the etching rate in NH ₃ peelability is 311 nm / min, and O ₂ The etching rate in peelability was 899 nm / min.

(Examples 2 to 21, Reference Examples 2 to 4 )
A resist underlayer film composition was prepared in the same manner as in Example 1 except that the formulation shown in Table 2 was used. In addition, “A-8” in Table 2 indicates a trade name “Sanol LS-944” manufactured by Sankyo Lifetech Co., Ltd.

(Comparative Examples 1-3)
A resist underlayer film composition was prepared in the same manner as in Example 1 except that the formulation shown in Table 3 was used. In Table 3, “R-1” is polyacenaphthylene (manufactured by JSR), “R-2” is polyhydroxystyrene (trade name: Marcalinker, manufactured by Maruzen Petrochemical), “R-3”. Indicates polymethacrylic acid (manufactured by JSR). In Table 3, R-1 to R-3 are shown as polymers.

(Comparative Examples 4 and 5)
Various evaluations described above were performed using commercially available resist underlayer film compositions. In Table 3, “NFC1400” indicates the product name “NFC1400” manufactured by JSR, and “NFC1500” indicates the product name “NFC1500” manufactured by JSR.

Each evaluation mentioned above was performed about the composition for resist underlayer films of Examples 2-21, Reference Examples 2-4 , and the composition for resist underlayer films of Comparative Examples 1-5. The evaluation results are shown in Tables 4 and 5.

As shown in Tables 4 and 5, the resist underlayer films formed from the compositions for resist underlayer films of Examples 1-21 and Reference Examples 2-4 have a nitrogen atom content of 10% by mass in the resist underlayer film. Since it is the above, it has confirmed that it had favorable peelability by plasma ashing compared with the resist underlayer film formed with the composition for resist underlayer films of Comparative Examples 1-5. In addition, the resist underlayer films formed from the compositions for resist underlayer films of Examples 1 to 21 and Reference Examples 2 to 4 are good in all evaluations of via embedding property, pattern shape after development, and standing wave prevention effect. It was confirmed that the results were correct.

Etching resistance, showed the evaluation results according to the trend of the Ohnishi parameter, NH ₃ releasability and O ₂ release property was confirmed to be a good etching rate than the trend of Ohnishi parameter. This is because the resist underlayer film compositions of Examples 1 to 21 and Reference Examples 2 to 4 are related to the amount of nitrogen atoms contained in the resist underlayer film when the resist underlayer film is formed. It is inferred. Therefore, it was confirmed that the resist underlayer film having a high nitrogen atom content has a relatively good etching rate.

In addition, the resist underlayer film formed with the resist underlayer film composition of Comparative Examples 1 to 5 is the same as the resist underlayer film formed with the resist underlayer film composition of Examples 1-21 and Reference Examples 2-4 . The etching resistance followed the trend of Onishi parameter. Moreover, NH ₃ peelability and O ₂ peelability were also etching rates in accordance with the trend of Onishi parameters. Therefore, the resist underlayer films formed from the compositions for resist underlayer films of Comparative Examples 1 to 5 have a nitrogen atom content of less than 10% by mass, so that the resist underlayers of Examples 1 to 21 and Reference Examples 2 to 4 are used. It was confirmed that the peelability by plasma ashing was inferior (difficult to peel) as compared with the resist underlayer film formed by the film composition.

  The resist underlayer film composition of the present invention is well embedded in a via hole, has good etching resistance, is easily peeled off by plasma ashing, and has excellent pattern transfer performance (pattern shape after development, antireflection effect). A resist underlayer film can be formed. That is, since peeling by plasma ashing is easy, it is difficult to damage the low dielectric insulating film (it is difficult to increase the effective dielectric constant of the low dielectric insulating film), the etching resistance is good, and the antireflection effect is high. Since the pattern shape after development is good, it can be suitably used for forming a dual damascene structure in a highly integrated circuit.

Claims (7)

When a resist underlayer film having a thickness of 300 nm is formed by coating on a substrate and heating and drying at 250 ° C. for 60 seconds, the content of nitrogen atoms in the formed resist underlayer film is 10% by mass or more. Oh it is,
Including a resin containing a nitrogen atom, and a solvent,
A composition for a resist underlayer film , wherein the resin contains 10 to 20% by mass of the nitrogen atom . The resist underlayer film composition according to claim 1 , wherein the resin contains at least one selected from the group consisting of structural units represented by the following formulas (1), (2), and (3).

The composition for a resist underlayer film according to claim 2 , wherein a total ratio of the structural units represented by the formulas (1), (2) and (3) contained in the resin is 10 to 50% by mass. . The resist underlayer film composition according to claim 2 or 3 , wherein the resin further contains a structural unit represented by the following general formula (4).

(In the general formula (4), R ¹ is a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, a hydroxyl group, a substitutable hydroxyalkyl group having 1 to 6 carbon atoms, or 1 carbon atom. ˜20 substitutable alkoxyl group, C 1-6 substitutable alkylthio group, aralkylthio group or arylthio group, amino group, C 1-6 substitutable alkylamino group, aralkylamino group or arylamino A group, a halogen atom, or a substitutable aryl group having 7 to 20 carbon atoms, x is an integer of 1 to 6, y is an integer of 0 to 2, and when x is 2 or more, R ¹ may be the same or different. Furthermore, the composition for resist underlayer films as described in any one of Claims 1-4 containing at least 1 type selected from the group which consists of an acid generator and a crosslinking agent. A photoresist film having a resist pattern formed on the resist underlayer film formed by the resist underlayer film composition according to any one of claims 1 to 5 , and using the photoresist film as a mask. Transferring the resist pattern to the resist underlayer film by etching;
Using the resist underlayer film to which the resist pattern of the photoresist film has been transferred as a mask, transferring the resist pattern of the resist underlayer film to a low dielectric insulating film disposed under the resist underlayer film; ,
A step of removing the resist underlayer film by plasma ashing after transferring the resist pattern of the resist underlayer film to the low dielectric insulating film;
A method for forming a dual damascene structure. The method for forming a dual damascene structure according to claim 6 , wherein the gas used for the plasma ashing is a mixed gas of ammonia, nitrogen, and hydrogen.

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