Resist underlayer film material, pattern forming method, and resist underlayer film forming method

Abstract

To provide: a resist underlay film material having good dry etching resistance, heat resistant characteristics at 500°C or higher, and a high degree of embedding / flattening characteristics; and a resist underlay film formation method and a pattern formation method using the material.SOLUTION: Provided is a resist underlay film material comprising (A) a resin having a condensed ring compound of a specific structure having a specific aromatic substituent and (B) an organic solvent, where the Mw / Mn of the (A) compound satisfies 1.00≤Mw / Mn≤1.25.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a resist underlayer film material used for fine patterning by a multilayer resist method in a semiconductor device manufacturing process, a pattern forming method using the material, and a resist underlayer film forming method.

Background Art

[0002] With the high integration and high speed of LSIs, the miniaturization of pattern dimensions has been rapidly progressing. Along with this miniaturization, lithography technology has achieved the formation of fine patterns by shortening the wavelength of the light source and appropriately selecting a resist composition therefor. The core of this is a positive photoresist composition used as a single layer. This single-layer positive photoresist composition has a skeleton in the resist resin that has etching resistance against dry etching with chlorine-based or fluorine-based gas plasmas, and has a switching mechanism such that the exposed portion dissolves, thereby dissolving the exposed portion to form a pattern, and dry-etching the substrate to be processed using the remaining resist pattern as an etching mask.

[0003] However, when the film thickness of the photoresist film used is directly miniaturized, that is, when the pattern width is made smaller, the resolution performance of the photoresist film decreases, and when trying to develop the photoresist film into a pattern with a developer, the so-called aspect ratio becomes too large, resulting in a problem that pattern collapse occurs. For this reason, the photoresist film has been thinned as the pattern is miniaturized.

[0004] On one hand, for processing a substrate to be processed, generally, a method of processing the substrate by dry etching using a photoresist film with a pattern formed thereon as an etching mask is used. However, in reality, there is no dry etching method that can achieve perfect etching selectivity between the photoresist film and the substrate to be processed. Therefore, during the processing of the substrate, the photoresist film is also damaged and collapses, resulting in the problem that the resist pattern cannot be accurately transferred to the substrate to be processed. Thus, with the miniaturization of patterns, higher dry etching resistance has been required for resist compositions. However, on the other hand, in order to improve the resolution, resins used in photoresist compositions have been required to have little light absorption at the exposure wavelength. Therefore, as the exposure light becomes shorter in wavelength, such as i-line, KrF, and ArF, the resins have also changed from novolak resins, polyhydroxystyrene, to resins having an aliphatic polycyclic skeleton. However, in reality, the etching rate under dry etching conditions during substrate processing has become faster, and recent photoresist compositions with high resolution tend to have weaker etching resistance.

[0005] Therefore, it has become necessary to dry-etch the substrate to be processed with a thinner and less etching-resistant photoresist film, and ensuring the materials and processes in this processing step has become an urgent task.

[0006] As one method to solve such problems, there is a multilayer resist method. This method involves interposing a resist intermediate film with different etching selectivity from the photoresist film (i.e., the resist upper layer film) between the resist upper layer film and the substrate to be processed. After obtaining a pattern on the resist upper layer film, the resist upper layer film pattern is used as a dry etching mask to transfer the pattern to the resist intermediate film by dry etching, and further, using the resist intermediate film as a dry etching mask, the pattern is transferred to the substrate to be processed by dry etching.

[0007] One of the multilayer resist methods is a three-layer resist method that can be performed using a general resist composition used in the single-layer resist method. In this three-layer resist method, for example, an organic film made of a novolak resin or the like is formed as a resist lower layer film on a substrate to be processed, a silicon-containing resist intermediate film is formed as a resist intermediate film thereon, and a normal organic photoresist film is formed as a resist upper layer film thereon. When performing dry etching with a fluorine-based gas plasma, the organic resist upper layer film has a good etching selectivity with respect to the silicon-containing resist intermediate film, so the resist upper layer film pattern can be transferred to the silicon-containing resist intermediate film by dry etching with a fluorine-based gas plasma. According to this method, even when using a resist composition that is difficult to form a pattern with a sufficient film thickness for directly processing the substrate to be processed or a resist composition that does not have sufficient dry etching resistance for substrate processing, a pattern can be transferred to the silicon-containing resist intermediate film (resist intermediate film), and then, if pattern transfer is performed by dry etching with an oxygen-based or hydrogen-based gas plasma, a pattern of an organic film (resist lower layer film) made of a novolak resin or the like that has sufficient dry etching resistance for substrate processing can be obtained. As the resist lower layer film as described above, many are already known, such as those described in Patent Document 1.

[0008] On the one hand, in recent years, the miniaturization of DRAM memory has been accelerating, and in addition to dry etching resistance, the need for an underlying film with excellent embedding characteristics or planarization characteristics has been increasing. For example, when there is a fine pattern structure with a high aspect ratio on the underlying substrate to be processed, embedding characteristics are required to fill the inside of the pattern with a film without voids. Further, when a fine pattern dense portion and a patternless region as described above exist on the same wafer, it is necessary to planarize the surface with a resist underlayer film. By planarizing the surface with a resist underlayer film, the film thickness variation of the resist intermediate film and the resist upper layer film formed thereon can be suppressed, and the focus margin of lithography and the margin of the subsequent processing steps of the substrate to be processed can be expanded. Furthermore, as the inorganic hard mask intermediate film formed on the resist underlayer film, a SiON film having a high effect as an antireflection film is preferably used. However, since the substrate temperature when forming the SiON film is 400 to 500 ° C, the resist underlayer film is required to have a high temperature resistance of 500 ° C or higher. In addition, due to the complication of the process, a method of forming a hard mask that requires a high temperature treatment of 400 to 500 ° C on the resist underlayer film material a plurality of times is also used, and a resist underlayer film material having more excellent high temperature resistance is required.

[0009] As a method for improving the embedding / planarization characteristics of the resist underlayer film material, the addition of a liquid additive such as polyether polyol has been proposed (Patent Document 2). However, the resist underlayer film formed by the above method contains a large amount of polyether polyol units that are inferior in etching resistance, so the etching resistance is significantly reduced, and it is unsuitable as a resist underlayer film.

[0010] As resist underlayer films that combine high-level filling / planarization properties and etching resistance, compounds in which hydroxyl groups are protected with groups containing triple bonds have been proposed, as described in Patent Documents 3, 4, and 5. However, these materials have insufficient adhesion to the substrate being processed, and there is a concern that defects such as peeling may occur during processing in dense areas of high-aspect ratio fine pattern structures in the advanced generation of miniaturization. For this reason, there is a need for materials that can fill / planarize dense areas of high-aspect ratio fine pattern structures without peeling from the substrate. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] JP 2004-205685 A [Patent Document 2] Patent No. 6550760 [Patent Document 3] Patent No. 6641879 [Patent Document 4] Patent No. 6714493 [Patent Document 5] Patent No. 6462602 Summary of the Invention [Problem to be solved by the invention]

[0012] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a resist underlayer film material that has good dry etching resistance, heat resistance at 500°C or higher, and high-level filling / planarization properties, and a method for forming a resist underlayer film and a pattern formation method using this material. [Means for solving the problem]

[0013] In order to solve the above problems, in the present invention, there is provided a resist underlayer film material used in a multilayer resist method, which contains (A) a resin having a compound represented by the following general formula (1A) and (B) an organic solvent. The ratio Mw / Mn of the weight average molecular weight Mw to the number average molecular weight Mn in terms of polystyrene by gel permeation chromatography of the compound represented by the general formula (1A) is 1.00 ≦ Mw / Mn ≦ 1.25. In the general formula (1A), X is a group represented by the following general formula (1B). In the general formula (1B), R1 is any one of a hydrogen atom, an organic group having 1 to 10 carbon atoms, and a structure represented by the following general formula (1C). Among the structures constituting R1, when the proportion of the hydrogen atom is a and the proportion of the organic group having 1 to 10 carbon atoms or the structure represented by the general formula (1C) is b, the resist underlayer film material satisfies the relationship of a + b = 1 and 0.2 ≦ b ≦ 0.8 in the whole component (A).

Chemical formula

Chemical formula

Chemical formula

Chemical formula

[0014] With such a resist underlayer film material, it is possible to provide a resist underlayer film material having good dry etching resistance, heat resistance characteristics of 500 °C or higher, and advanced embedding / planarization characteristics. Further, by controlling the ratio b of the above organic structure constituting R1 in general formula (1B) within such a range, it is possible to highly parallelize the embedding / planarization characteristics and the peeling resistance.

[0015] Further, in the present invention, in the general formula (1B), it is preferable that the constituent components of R1 are constituted by either a hydrogen atom or the following general formula (1F). [Chemical formula] (In the general formula (1F), * represents a bonding site to an oxygen atom.)

[0016] With such a resist underlayer film material, since it has excellent fluidity, it is possible to provide a resist underlayer film material having advanced embedding / planarization characteristics.

[0017] Further, it is preferable that the weight average molecular weight of the compound represented by the general formula (1A) is 2,500 or less.

[0018] If the weight average molecular weight of the compound represented by the general formula (1A) is as described above, the thermal fluidity of the resist underlayer film material becomes better. Therefore, when blended with the resist underlayer film material, not only can the fine structure formed on the substrate be well embedded, but also a resist underlayer film that makes the entire substrate flat can be formed.

[0019] Further, in the present invention, it is preferable that the resist underlayer film material further contains (C) a crosslinking agent.

[0020] Also, the content of the crosslinking agent (C) is preferably 5 to 50 parts by mass with respect to 100 parts by mass of the resin (A).

[0021] By including the crosslinking agent (C) within such a range, the curing reaction with the hydroxyl groups contained in the resin (A) proceeds sufficiently, and a dense film can be formed. Therefore, a resist underlayer film excellent in heat resistance characteristics of 500°C or higher can be formed.

[0022] In the present invention, it is preferable that the resist underlayer film material further contains one or more of (D) surfactant, (E) acid generator, (F) plasticizer, and (G) pigment.

[0023] In the resist underlayer film material of the present invention, depending on necessity, by the presence / selection of the above additives, fine adjustment of performance according to requirements such as coating film-forming property by spin coating, curing temperature, embedding / planarization characteristics, and optical characteristics (light absorption characteristics) becomes possible, which is practically preferable.

[0024] In the present invention, it is preferable that the organic solvent (B) contains a high-boiling solvent.

[0025] At this time, it is preferable that the high-boiling solvent is one or more organic solvents having a boiling point of 180°C or higher.

[0026] With such a resist underlayer film material, the fluidity increases, so that the embedding / planarization characteristics become even better.

[0027] In the present invention, a method for forming a pattern on a substrate to be processed, (I-1) A step of forming a resist underlayer film by applying the resist underlayer film material described above on the substrate to be processed and then performing heat treatment, (I-2) A step of forming a resist upper layer film on the resist underlayer film using a photoresist material, (I-3) After pattern-exposing the resist upper layer film, developing it with a developer to form a pattern in the resist upper layer film; (I-4) Using the resist upper layer film on which the pattern is formed as a mask, transferring the pattern to the resist lower layer film by dry etching, and (I-5) Using the resist lower layer film on which the pattern is formed as a mask, processing the substrate to be processed to form a pattern in the substrate to be processed A pattern forming method having the above steps is provided.

[0028] Also, in the present invention, a method for forming a pattern on a substrate to be processed, comprising: (II-1) After coating the resist lower layer film material described above on the substrate to be processed, forming a resist lower layer film by heat treatment; (II-2) Forming a resist intermediate film on the resist lower layer film; (II-3) Forming a resist upper layer film using a photoresist material on the resist intermediate film; (II-4) After pattern-exposing the resist upper layer film, developing it with a developer to form a pattern in the resist upper layer film; (II-5) Using the resist upper layer film on which the pattern is formed as a mask, transferring the pattern to the resist intermediate film by dry etching; (II-6) Using the resist intermediate film to which the pattern is transferred as a mask, transferring the pattern to the resist lower layer film by dry etching, and (II-7) Using the resist lower layer film on which the pattern is formed as a mask, processing the substrate to be processed to form a pattern in the substrate to be processed A pattern forming method having the above steps is provided.

[0029] Also, in the present invention, a method for forming a pattern on a substrate to be processed, comprising: (III-1) After coating the resist lower layer film material described above on the substrate to be processed, forming a resist lower layer film by heat treatment; (III-2) A step of forming an inorganic hard mask intermediate film selected from a silicon oxide film, a silicon nitride film, and a silicon oxynitride film on the resist lower layer film; (III-3) A step of forming an organic thin film on the inorganic hard mask intermediate film; (III-4) A step of forming a resist upper layer film on the organic thin film using a photoresist material; (III-5) After pattern exposure of the resist upper layer film, developing with a developer to form a pattern in the resist upper layer film; (III-6) A step of transferring a pattern to the organic thin film and the inorganic hard mask intermediate film by dry etching using the resist upper layer film with the pattern formed thereon as a mask; (III-7) A step of transferring a pattern to the resist lower layer film by dry etching using the inorganic hard mask intermediate film with the pattern transferred thereon as a mask, and (III-8) A step of processing the substrate to be processed using the resist lower layer film with the pattern formed thereon as a mask to form a pattern on the substrate to be processed A pattern forming method having the above steps is provided.

[0030] Thus, the resist lower layer film material of the present invention can be suitably used in various pattern forming methods such as a two-layer resist process, a three-layer resist process using a resist intermediate film, and a four-layer resist process using an organic thin film in addition to these. With these pattern forming methods, the unevenness and steps of the substrate to be processed can be effectively alleviated by forming the resist lower layer film, and it is suitable for photolithography of the resist upper layer film.

[0031] Further, in the pattern forming method of the present invention, as the substrate to be processed, a substrate having a structure or step with a height of 30 nm or more can be used.

[0032] The pattern forming method of the present invention uses the resist lower layer film material of the present invention capable of forming a resist lower layer film having high embedding / planarization characteristics, and is particularly useful for microfabrication of a substrate having such a structure or step.

[0033] The present invention also provides a method for forming a resist underlayer film that functions as an organic flat film used in the manufacturing process of a semiconductor device, which comprises spin-coating the resist underlayer film material described above onto a substrate to be processed, and heat-treating the substrate coated with the resist underlayer film material at a temperature of 100°C or higher and 600°C or lower for 10 to 600 seconds to form a cured film.

[0034] The present invention also provides a method for forming a resist underlayer film that functions as an organic flat film used in the manufacturing process of a semiconductor device, which comprises spin-coating the resist underlayer film material described above onto a substrate to be processed, and heat-treating the substrate coated with the resist underlayer film material in an atmosphere having an oxygen concentration of 1% or more and 21% or less to form a hardened film.

[0035] By using such a method, the crosslinking reaction during the formation of the resist underlayer film can be promoted, and mixing with the resist toplayer film can be more effectively suppressed. In addition, by appropriately adjusting the heat treatment temperature, time, and oxygen concentration within the above ranges, the resist underlayer film can have filling / planarization properties and curing properties suitable for the application.

[0036] The present invention also provides a method for forming a resist underlayer film that functions as an organic flat film used in the manufacturing process of a semiconductor device, which comprises spin-coating the resist underlayer film material described above onto a substrate to be processed, and heat-treating the substrate coated with the resist underlayer film material in an atmosphere with an oxygen concentration of less than 1%, thereby forming a hardened film.

[0037] This method is useful because it promotes the crosslinking reaction during the formation of the resist underlayer film and more effectively suppresses mixing with the resist toplayer film without causing deterioration of the substrate to be processed, even when the substrate contains a material that is unstable when heated in an oxygen atmosphere.

[0038] In this case, the substrate to be processed may be a substrate having a structure or steps with a height of 30 nm or more.

[0039] The resist underlayer film forming method of the present invention uses the resist underlayer film material of the present invention, which can form a resist underlayer film having high-level filling / planarizing properties, and is therefore particularly suitable for forming a resist underlayer film on a substrate having such structures or steps. [Effects of the Invention]

[0040] As described above, the resist underlayer film material, pattern formation method, and resist underlayer film formation method of the present invention are particularly suitable for use in multilayer resist processes, including filling / planarizing substrates having steps or irregularities, and are extremely useful in fine patterning for semiconductor device manufacturing. In particular, in fine patterning processes using multilayer resist methods in semiconductor device manufacturing processes, even on substrates having areas that are difficult to fill / planarize, such as dense areas of high-aspect-ratio fine pattern structures typified by increasingly miniaturized DRAM memories, filling is possible without causing defects such as voids or peeling, and a resist underlayer film with excellent flatness can be formed.

[0041] Compounds containing triple bonds, as reported in prior art patents 6641879 and 6714493, are known as methods for improving filling and planarization characteristics. However, these materials lack sufficient adhesion to the substrate, raising concerns about peeling and other defects during processing in dense areas of high-aspect-ratio fine pattern structures in advanced generations of miniaturization. In dense areas of high-aspect-ratio fine pattern structures, the contact area between the resist underlayer film and the substrate increases, making good adhesion to the substrate essential for the resist underlayer film. Furthermore, recent device manufacturing processes have become more complex, leading to the use of methods that involve forming hard masks multiple times on the resist underlayer material, which requires high-temperature treatment at 400-500°C. This necessitates the use of resist underlayer film materials with better high-temperature resistance. In contrast, the resist underlayer film material of the present invention uses a resin having a compound represented by formula (1A) in which the ratio of organic groups such as allyl groups and propargyl groups that contribute to improving fluidity and hydroxyl groups that contribute to improving substrate adhesion and heat resistance is controlled, thereby making it possible to provide a material that combines excellent filling / planarization properties with excellent substrate adhesion and excellent heat resistance. [Brief description of the drawings]

[0042]

Figure 1

Figure 2

Figure 3

[0043] As described above, in the fine patterning process using the multilayer resist method in the semiconductor device manufacturing process, even on a substrate to be processed having a portion where embedding / planarization is difficult, such as a dense portion of a high aspect ratio fine pattern structure typified by a DRAM memory with increasing miniaturization, embedding / planarization can be achieved without causing defects such as voids or peeling, and a resist underlayer film material having a heat resistance of 500°C or higher that enables the formation of a hard mask requiring high-temperature treatment on the resist underlayer film has been demanded.

[0044] As a result of intensive studies on the above problems, the present inventors have explored various resist underlayer film materials and pattern formation methods in order to enable the realization of advanced embedding / planarization by forming a resist underlayer film and the coexistence of excellent heat resistance in the multilayer resist method using a resist underlayer film. As a result, it has been found that a resist underlayer film material containing a compound having a specific structure and an optimized ratio of a hydroxyl group and an organic crosslinking group, and a pattern formation method using the same are very effective, and the present invention has been completed.

[0045] That is, the present invention is a resist underlayer film material used in the multilayer resist method, which contains (A) a resin having a compound represented by the following general formula (1A) and (B) an organic solvent, and the ratio Mw / Mn of the weight average molecular weight Mw to the number average molecular weight Mn in terms of polystyrene by gel permeation chromatography of the compound represented by the general formula (1A) is 1.00 ≦ Mw / Mn ≦ 1.25. In the general formula (1A), X is a group represented by the following general formula (1B). In the general formula (1B), R1 is any one of a hydrogen atom, an organic group having 1 to 10 carbon atoms, and a structure represented by the following general formula (1C). Among the structures constituting R1, when the ratio of the hydrogen atom is a and the organic group having 1 to 10 carbon atoms or the structure represented by the general formula (1C) is b, the resist underlayer film material satisfies the relationship of a + b = 1 and 0.2 ≦ b ≦ 0.8 in the whole component (A).

Chemical formula

Chemical formula

Chemical formula

Chemical formula

[0046] Hereinafter, the present invention will be described in detail, but the present invention is not limited thereto.

[0047] <Resist underlayer film material> The resist underlayer film material of the present invention is a resist underlayer film material used in a multilayer resist method, containing (A) a resin having a compound represented by the following general formula (1A) and (B) an organic solvent. The ratio Mw / Mn of the weight average molecular weight Mw to the number average molecular weight Mn in terms of polystyrene by gel permeation chromatography of the compound represented by the general formula (1A) is 1.00 ≦ Mw / Mn ≦ 1.25. In the general formula (1A), X is a group represented by the following general formula (1B). In the general formula (1B), R1 is any one of a hydrogen atom, an organic group having 1 to 10 carbon atoms, and a structure represented by the following general formula (1C). Among the structures constituting R1, when the proportion of the hydrogen atom is a and the proportion of the organic group having 1 to 10 carbon atoms or the structure represented by the general formula (1C) is b, the resist underlayer film material satisfies the relationship of a + b = 1 and 0.2 ≦ b ≦ 0.8 in the whole component (A).

Chemical formula

Chemical formula

Chemical formula

Chemical formula

[0048] [(A) Resin having a compound represented by general formula (1A)] The resist underlayer film material of the present invention contains (A) a resin having a compound represented by the following general formula (1A), and therefore can fill without causing defects such as voids or peeling, even on a substrate to be processed that has areas that are difficult to fill / planarize, such as dense areas of a high aspect ratio fine pattern structure, and can form a resist underlayer film with excellent planarization properties. [ka] [ka] (In general formula (1B), n1 is 0 or 1, n2 is 1 or 2, R1 is any one of a hydrogen atom, an organic group having 1 to 10 carbon atoms, and a structure represented by the following general formula (1C), and among the structures constituting R1, when the proportion of hydrogen atoms is a and the proportion of the organic group having 1 to 10 carbon atoms or the structure represented by general formula (1C) is b, the relationship a+b=1, 0.2≦b≦0.8 is satisfied for the entire component (A). X2 is a group represented by the following general formula (1D), and n3 is 0, 1, or 2.) [ka] (In general formula (1C), * represents a bonding site to an oxygen atom, and R A is a divalent organic group having 1 to 10 carbon atoms, R B is a hydrogen atom or a monovalent organic group having 1 to 10 carbon atoms. [ka] (In general formula (1D), R2 is a hydrogen atom or a saturated or unsaturated hydrocarbon group having 1 to 10 carbon atoms, and the hydrogen atom on the benzene ring in general formula (1D) may be substituted with a methyl group or a methoxy group.)

[0049] In the general formula (1B) above, n1 is preferably 1, and n2 is preferably 1. Further, R1 is any one of a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, and a structure represented by the general formula (1C), and preferably includes both a hydrogen atom and the structure represented by the general formula (1C).

[0050] By having a structure with many aromatic ring structures as described above, a resist underlayer film excellent in heat resistance and dry etching resistance can be formed. Further, by having both a hydroxyl group which is a hydrophilic group and the general formula (1C) which is a hydrophobic group, a resist underlayer film material having excellent thermal fluidity and substrate adhesion can be provided.

[0051] In the general formula (1C) above, R A Examples of the divalent organic group having 1 to 10 carbon atoms represented by include alkane diyl groups such as methylene group, ethanediyl group, propanediyl group, butanediyl group, pentanediyl group, hexanediyl group, octanediyl group, decanediyl group, and arene diyl groups such as benzenediyl group, methylbenzenediyl group, naphthalenediyl group, etc.

[0052] In the general formula (1C) above, R B Examples of the monovalent organic group having 1 to 10 carbon atoms represented by include alkyl groups such as methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl group, t-butyl group, n-pentyl group, n-hexyl group, n-octyl group, n-decyl group, and aryl groups such as phenyl group, tolyl group, xylyl group, mesityl group, naphthyl group, etc.

[0053] Some or all of the hydrogen atoms of the above-mentioned alkandiyl group, arenediyl group, alkyl group, aryl group, etc. may be substituted, and examples of the substituent include, for example, alkoxy groups such as methoxy group, ethoxy group, n-propoxy group, i-propoxy group, n-butoxy group, i-butoxy group, sec-butoxy group, t-butoxy group, n-pentyloxy group, n-hexyloxy group, methoxycarbonyl group, ethoxycarbonyl group, n-propoxycarbonyl group, i-propoxycarbonyl group, n-butoxycarbonyl group, i-butoxycarbonyl group, sec-butoxycarbonyl group, t-butoxycarbonyl group, n-pentyloxycarbonyl group, n-hexyloxycarbonyl group, and other alkoxycarbonyl groups.

[0054] Particularly preferred examples include structures in which, in the general formula (1B), the constituent component of R1 is composed of either a hydrogen atom or the following general formula (1F). When having such a structure, the thermal fluidity is good, and a resist underlayer film material excellent in embedding / planarization characteristics can be provided. In addition, the heat resistance and film-forming properties are good, the generation of sublimates during heat curing can be suppressed, the contamination of the device by sublimates can be suppressed, and the occurrence of coating defects can be suppressed.

Chemical formula

[0055] When the ratio of the hydrogen atom is a and the organic group having 1 to 10 carbon atoms or the structure represented by the above general formula (1C) is b, the whole component (A) satisfies the relationship of a + b = 1 and 0.2 ≤ b ≤ 0.8, and the relationship of 0.3 ≤ b ≤ 0.7 is preferred, and the relationship of 0.4 ≤ b ≤ 0.6 is more preferred.

[0056] Here, when the whole component (A) satisfies the relationship of a + b = 1 and 0.2 ≦ b ≦ 0.8, when the compound represented by the general formula (1A) is used alone, it satisfies the above relationship alone. When two or more compounds represented by the general formula (1A) are used, each compound satisfies the above relationship, or the whole compounds used satisfy the above relationship.

[0057] By controlling the ratio of the hydrogen atom and the organic group having 1 to 10 carbon atoms or the general formula (1C) within the above range, it is possible to highly exhibit fluidity and substrate adhesion, and a resist underlayer film material with improved embedding / planarization characteristics can be provided. When the range of b is b > 0.8, the content of the hydroxyl group may be insufficient and the adhesion to the substrate may deteriorate. In addition, a crosslinking reaction between hydroxyl groups is preferable for forming a dense film, and it is necessary to contain hydroxyl groups at a certain ratio or more from the viewpoint of heat resistance characteristics. On the other hand, when the range of b is b < 0.2, the thermal fluidity of the resin becomes insufficient, and the embedding / planarization characteristics may deteriorate.

[0058] Examples of R2 in the general formula (1D) include linear or branched alkyl groups such as methyl group, ethyl group, isopropyl group, alicyclic hydrocarbon groups such as cyclopentyl group, cyclohexyl group, norbornyl group, linear or branched alkenyl groups such as vinyl group and propenyl group, linear or branched alkynyl groups such as ethynyl group and propargyl group, phenyl group, toluyl group, etc. Aryl groups and the like can be exemplified.

[0059] In addition, as the compound represented by the general formula (1A), particularly preferable structures include the following. Among them, those having two cardo structures are more preferable.

Chemical formula

[0060] For a resist underlayer film material containing such a component (A), since it has a rigid structure containing many aromatic rings, a resist underlayer film material with better heat resistance and etching resistance can be formed. Furthermore, due to the action of the caldo structure introduced into the molecule, it not only relaxes the intermolecular interaction and imparts solubility in an organic solvent, but also improves the film-forming property during the formation of a coating film. Also, despite introducing a plurality of condensed carbon rings with a high carbon density, it is possible to achieve both heat resistance and the contradictory performance of embedding / planarization properties.

[0061] In addition, the ratio Mw / Mn (i.e., dispersity) of the weight average molecular weight Mw to the number average molecular weight Mn in terms of polystyrene conversion by gel permeation chromatography of the compound represented by the general formula (1A) is 1.00 ≤ Mw / Mn ≤ 1.25. When the dispersity is outside the above range, the thermal fluidity of the resist underlayer film material decreases. Therefore, when compounded in the resist underlayer film material, not only is it impossible to embed the fine structure formed on the substrate, but also a resist underlayer film that makes the entire substrate flat cannot be formed. By definition, for a single-molecule compound, Mw / Mn is 1.00, but due to the separation property of GPC, the measured value may exceed 1.00. Generally, for a polymer having repeating units, it is extremely difficult to approach Mw / Mn = 1.00 without using a special polymerization method, and it has a distribution of Mw and Mw / Mn becomes a value exceeding 1. In the present invention, 1.00 ≤ Mw / Mn ≤ 1.25 is defined as an index indicating monomolecularity to distinguish between a single-molecule compound and a polymer.

[0062] In addition, the weight average molecular weight of the compound represented by the general formula (1A) is preferably 2,500 or less. With such a molecular weight, the thermal fluidity of the resist underlayer film material becomes better. Therefore, when compounded in the resist underlayer film material, not only can the fine structure formed on the substrate be well embedded, but also a resist underlayer film that makes the entire substrate flat can be formed.

[0063] In the present invention, the resin having the compound represented by the general formula (1A) may be used alone, or resins having equivalent compounds can also be obtained by mixing two or more compounds represented by the following general formula (1A') and general formula (1A'') at a desired ratio.

[0064]

Chemical formula

Chemical formula

[0065]

Chemical formula

Chemical formula

[0066] When the resin having the compounds represented by the general formulas (1A') and (1A'') is mixed, when R4 in the structure represented by the general formula (3B) is c and R5 in the structure represented by the general formula (4B) is d, those satisfying the relationship of c + d = 1 and 0.2 ≤ d ≤ 0.8 are preferable, the relationship of 0.3 ≤ d ≤ 0.7 is more preferable, and the relationship of 0.4 ≤ d ≤ 0.6 is even more preferable.

[0067] By controlling the mixing ratio of the resins having the compounds represented by the above general formulas (1A') and (1A'') within the above range, it is possible to highly exhibit fluidity and substrate adhesion, and a resist underlayer film material with improved embedding / planarization characteristics can be provided. When the range of d is d ≤ 0.8, the content of hydroxyl groups is sufficient and the adhesion to the substrate does not deteriorate. Also, for forming a dense film, a cross-linking reaction between hydroxyl groups is preferable, and it is preferable to contain hydroxyl groups at a certain ratio or more from the viewpoint of heat resistance characteristics. On the other hand, when the range of d is d ≥ 0.2, the thermal fluidity of the resin is sufficient and the embedding / planarization characteristics do not deteriorate.

[0068] When two or more compounds represented by the above general formula (1A') and the above general formula (1A'') are mixed and used in a desired ratio, the ratio Mw / Mn (i.e., dispersity) of the weight average molecular weight Mw and the number average molecular weight Mn in terms of polystyrene by gel permeation chromatography is preferably within the range of 1.00 ≤ Mw / Mn ≤ 1.25 for each compound.

[0069] In the present invention, a resin not containing the compound represented by the above general formula (1A) may be mixed and used. In that case, as the resin that may be mixed, known resins can be used without particular limitation, but specifically, acrylic resins, styrene resins, phenolic resins, polyether resins, and epoxy resins are preferable.

[0070] Another compound or polymer can also be blended into the resist underlayer film material of the present invention. The blending compound or blending polymer is mixed with the resin having the compound represented by the above general formula (1A) and has the role of improving the film-forming property of spin coating and the embedding / planarization characteristics on a substrate having steps. Also, as the blending compound or blending polymer, a compound having a phenolic hydroxyl group is preferable.

[0071] Such materials include phenol, o-cresol, m-cresol, p-cresol, 2,3-dimethylphenol, 2,5-dimethylphenol, 3,4-dimethylphenol, 3,5-dimethylphenol, 2,4-dimethylphenol, 2,6-dimethylphenol, 2,3,5-trimethylphenol, 3,4,5-trimethylphenol, 2-tert-butylphenol, 3-tert-butylphenol, 4-tert-butylphenol, 2-phenylphenol, 3-phenylphenol, 4-phenylphenol, 3,5-diphenylphenol, 2-naphthylphenol, 3-naphthylphenol, 4-naphthylphenol, 4-tritylphenol, resorcinol, 2-methylresorcinol, 4-methylresorcinol, 5-methylresorcinol, catechol, 4-tert-butylcatechol, 2-methoxyphenol, 3-methoxyphenol, 2-propylphenol, 3-propylphenol, 4-propylphenol, 2-isopropylphenol, 3-isopropylphenol, 4-isopropylphenol, 2-methoxy-5-methylphenol, 2-tert-butyl-5-methylphenol, pyrogallol, thymol, isothymol, 4,4'-(9H-fluorene-9-ylidene)bisphenol, 2,2'-dimethyl-4,4'-(9H-fluorene-9-ylidene)bisphenol, 2,2'-diallyl-4,4'-(9H-fluorene-9-ylidene)bisphenol, 2,2'-difluoro-4,4'-(9H-fluorene-9-ylidene)bisphenol, 2,2'-diphenyl-4,4'-(9H-fluorene-9-ylidene)bisphenol, 2,2'-dimethoxy-4,4'-(9H-fluorene-9-ylidene)bisphenol, 2,3,2',3'-tetrahydro-(1,1')-spirobiinden-6,6'-diol, 3,3,3',3'-tetramethyl-2,3,2',3'-tetrahydro-(1,1')-spirobiinden-6,6'-diol, 3,3,3',3',4,4'-hexamethyl-2,3,2',3'-tetrahydro-(1,1')-spirobiinden-6,6'-diol, 2,3,2',3'-tetrahydro-(1,1')-spirobiinden-5,5'-diol, 5,5'-dimethyl-3,3,3',3'-tetramethyl-2,3,2',3'-tetrahydro-(1,1')-spirobiindene-6,6'-diol, 1-naphthol, 2-naphthol, 2-methyl-1-naphthol, 4-methoxy-1-naphthol, 7-methoxy-2-naphthol, and dihydroxynaphthalenes such as 1,5-dihydroxynaphthalene, 1,7-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, methyl 3-hydroxynaphthalene-2-carboxylate, indene, hydroxyindene, benzofuran, hydroxyanthracene, acenaphthylene, biphenyl, bisphenol, trisphenol, dicyclopentadiene, tetrahydroindene, 4-vinylcyclohexene, norbornadiene, 5-vinylnorborn-2-ene, α-pinene, β-pinene, limonene, etc. novolak resins, polyhydroxystyrene, polystyrene, polyvinylnaphthalene, polyvinylanthracene, polyvinylcarbazole, polyindene, polyacenaphthylene, polynorbornene, polycyclodecene, polytetracyclododecene, polynortricyclene, poly(meth)acrylate, and copolymers thereof. Further, a naphthol dicyclopentadiene copolymer described in JP-A-2004-205685, a fluorene bisphenol novolak resin described in JP-A-2005-128509, an acenaphthylene copolymer described in JP-A-2005-250434, a fullerene having a phenol group described in JP-A-2006-227391, a bisphenol compound and its novolak resin described in JP-A-2006-293298, a novolak resin of an adamantane phenol compound described in JP-A-2006-285095, a bisnaphthol compound and its novolak resin described in JP-A-2010-122656, a fullerene resin compound described in JP-A-2008-158002, etc. can also be blended.,

[0072] The blending amount of the compound or polymer for blending is preferably 5 to 100 parts by mass, more preferably 5 to 50 parts by mass, based on 100 parts by mass of the resin having the compound represented by the general formula (1A).

[0073] [(B) Organic solvent] As the (B) organic solvent that can be used in the resist underlayer film material of the present invention, there is no particular limitation as long as it can dissolve the resin having the compound represented by the above general formula (1A), and those that can also dissolve the (C) crosslinking agent, (D) surfactant, (E) acid generator, (F) plasticizer, and (G) dye described later are preferable.

[0074] Specifically, the organic solvents described in paragraphs

[0091] to

[0092] of JP-A-2007-199653 can be added. More specifically, propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, 2-heptanone, cyclopentanone, cyclohexanone, and γ-butyrolactone, or a mixture containing one or more of these is preferably used.

[0075] The blending amount of the organic solvent is preferably adjusted according to the set film thickness of the resist underlayer film, but usually, it is in the range of 100 to 50,000 parts by mass with respect to 100 parts by mass of the resin having the compound represented by the above general formula (1A).

[0076] Further, it is preferable that the (B) organic solvent contains a high-boiling solvent. That is, in the resist underlayer film material of the present invention, the (B) organic solvent may be used as a mixture of one or more organic solvents having a boiling point of less than 180°C and one or more organic solvents having a boiling point of 180°C or higher (high-boiling solvents).

[0077] Specific examples of the organic solvent having a boiling point of less than 180°C include propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, 2-heptanone, cyclopentanone, and cyclohexanone.

[0078] As the high-boiling solvent, there are no particular restrictions as long as it can dissolve each component of the resist underlayer film material of the present invention, and examples include hydrocarbons, alcohols, ketones, esters, ethers, chlorinated solvents, etc. Specific examples include 1-octanol, 2-ethylhexanol, 1-nonanol, 1-decanol, 1-undecanol, ethylene glycol, 1,2-propylene glycol, 1,3-butylene glycol, 2,4-pentanediol, 2-methyl-2,4-pentanediol, 2,5-hexanediol, 2,4-heptanediol, 2-ethyl-1,3-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol, glycerin, n-nonyl acetate 、eExamples thereof include ethylene glycol mono-2-ethylhexyl ether, ethylene glycol monophenyl ether, ethylene glycol monobenzyl ether, diethylene glycol monoethyl ether, diethylene glycol monoisopropyl ether, diethylene glycol mono-n-butyl ether, diethylene glycol monoisobutyl ether, diethylene glycol monohexyl ether, diethylene glycol monophenyl ether, diethylene glycol monobenzyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, diethylene glycol butyl methyl ether, triethylene glycol dimethyl ether, triethylene glycol monomethyl ether, triethylene glycol-n-butyl ether, triethylene glycol butyl methyl ether, tetraethylene glycol dimethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol mono-n-propyl ether, dipropylene glycol mono-n-butyl ether, tripropylene glycol dimethyl ether, tripropylene glycol monomethyl ether, tripropylene glycol mono-n-propyl ether, tripropylene glycol mono-n-butyl ether, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, triacetin, propylene glycol diacetate, dipropylene glycol methyl-n-propyl ether, dipropylene glycol methyl ether acetate, 1,4-butanediol diacetate, 1,3-butylene glycol diacetate, 1,6-hexanediol diacetate, triethylene glycol diacetate, γ-butyrolactone, methyl benzoate, ethyl benzoate, propyl benzoate, butyl benzoate, dihexyl malonate, diethyl succinate, dipropyl succinate, dibutyl succinate, dihexyl succinate, dimethyl adipate, diethyl adipate, dibutyl adipate, etc. These may be used alone or in combination.

[0079] The high-boiling solvent may be appropriately selected from the above-mentioned ones, for example, according to the temperature for heat-treating the resist underlayer film material of the present invention. The boiling point of the high-boiling solvent is preferably 180°C to 300°C, and more preferably 200°C to 300°C. With such a boiling point, there is no fear that the volatilization during baking (heat treatment) will be too fast, so sufficient heat fluidity can be obtained during film formation, and it is considered that a resist underlayer film excellent in embedding / planarization characteristics can be formed. Also, with such a boiling point, it will not remain in the film without volatilizing even after baking, so there is no fear of adversely affecting the film physical properties such as etching resistance.

[0080] In addition, when using a high-boiling solvent, the blending amount is preferably 1 to 30 parts by mass with respect to 100 parts by mass of an organic solvent having a boiling point of less than 180°C. With such a blending amount, sufficient heat fluidity can be imparted during baking, and it will not remain in the film and lead to deterioration of film physical properties such as etching resistance, so it is preferable.

[0081] [(C) Crosslinking agent] Further, the resist underlayer film material of the present invention may further contain a (C) crosslinking agent in order to enhance the curability and further suppress the intermixing with the resist upper layer film. The crosslinking agent is not particularly limited, and various known types of crosslinking agents can be widely used. As an example, melamine-based crosslinking agents, glycoluril-based crosslinking agents, benzoguanamine-based crosslinking agents, urea-based crosslinking agents, β-hydroxyalkylamide-based crosslinking agents, isocyanurate-based crosslinking agents, aziridine-based crosslinking agents, oxazoline-based crosslinking agents, epoxy-based crosslinking agents, phenol-based crosslinking agents (for example, methylol or alkoxymethyl type crosslinking agents of polynuclear phenols) can be exemplified. The content of the (C) crosslinking agent is preferably 5 to 50 parts by mass, more preferably 10 to 40 parts by mass, with respect to 100 parts by mass of the (A) resin.

[0082] As the melamine-based crosslinking agent, specifically, hexamethoxymethylated melamine, hexabutoxymethylated melamine, their alkoxy and / or hydroxy-substituted products, and their partial self-condensates can be exemplified. As the glycoluril-based crosslinking agent, specifically, tetramethoxymethylated glycoluril, tetrabutoxymethylated glycoluril, their alkoxy and / or hydroxy-substituted products, and their partial self-condensates can be exemplified. As the benzoguanamine-based crosslinking agent, specifically, tetramethoxymethylated benzoguanamine, tetrabutoxymethylated benzoguanamine, their alkoxy and / or hydroxy-substituted products, and their partial self-condensates can be exemplified. As the urea-based crosslinking agent, specifically, dimethoxymethylated dimethoxyethyleneurea, its alkoxy and / or hydroxy-substituted products, and their partial self-condensates can be exemplified. As the β-hydroxyalkylamide-based crosslinking agent, specifically, N,N,N’,N’-tetra(2-hydroxyethyl) adipic acid amide can be exemplified. As the isocyanurate-based crosslinking agent, specifically, triglycidyl isocyanurate, triallyl isocyanurate can be exemplified. As the aziridine-based crosslinking agent, specifically, 4,4’-bis(ethyleneiminocarbonylamino) diphenylmethane, 2,2-bishydroxymethylbutanol-tris[3-(1-aziridinyl) propionate] can be exemplified. As the oxazoline-based crosslinking agent, specifically, 2,2’-isopropylidene bis(4-benzyl-2-oxazoline), 2,2’-isopropylidene bis(4-phenyl-2-oxazoline) 、2 , 2’-methylenebis-4,5-diphenyl-2-oxazoline, 2,2’-methylenebis-4-phenyl-2-oxazoline, 2,2’-methylenebis-4-tert butyl-2-oxazoline, 2,2’-bis(2-oxazoline), 1,3-phenylene bis(2-oxazoline), 1,4-phenylene bis(2-oxazoline), 2-isopropenyl oxazoline copolymer can be exemplified. Specific examples of the epoxy crosslinking agent include diglycidyl ether, ethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,4-cyclohexanedimethanol diglycidyl ether, poly(glycidyl methacrylate), trimethylolethane triglycidyl ether, trimethylolpropane triglycidyl ether, and pentaerythritol tetraglycidyl ether.

[0083] Specific examples of the polynuclear phenol crosslinking agent include compounds represented by the following general formula (2).

Chemical formula

[0084] In the above general formula (2), Q is a single bond or a q-valent hydrocarbon group having 1 to 20 carbon atoms. q is an integer of 1 to 5, and more preferably 2 or 3. When Q is a q-valent hydrocarbon group having 1 to 20 carbon atoms, Q is a q-valent hydrocarbon group obtained by removing q hydrogen atoms from a hydrocarbon having 1 to 20 carbon atoms. More specifically, examples of the hydrocarbon having 1 to 20 carbon atoms in this case include methane, ethane, propane, butane, isobutane, pentane, cyclopentane, hexane, cyclohexane, methylpentane, methylcyclohexane, dimethylcyclohexane, trimethylcyclohexane, benzene, toluene, xylene, ethylbenzene, ethylisopropylbenzene, diisopropylbenzene, methylnaphthalene, ethylnaphthalene, and eicosane.

[0085] In the above general formula (2), R3 is a hydrogen atom or a methyl group, and preferably a methyl group.

[0086] By having the compound represented by the above general formula (2) as a crosslinking agent, the crosslinking reactivity of the hydroxyl groups contained in the compound represented by the above general formula (1A) can be increased, and the denseness of the film can be improved. Thereby, it becomes possible to further improve the heat resistance characteristics of the resist underlayer film material of the present invention.

[0087] As examples of the compound represented by the above general formula (2), specifically, the following compounds can be exemplified, but are not limited thereto. In the following formula, R3 is the same as above. The case where q = 3 and R3 satisfies a methyl group is preferable from the viewpoints of curability, improvement in film thickness uniformity, and reduction in sublimates. In particular, hexamethoxymethylated products of triphenolmethane, triphenolethane, 1,1,1-tris(4-hydroxyphenyl)ethane, and tris(4-hydroxyphenyl)-1-ethyl-4-isopropylbenzene are preferable.

[0088]

Chemical formula

[0089]

Chemical formula

[0090] The above crosslinking agent (C) can be used alone or in combination of two or more. The content of the crosslinking agent (C) is preferably 5 to 50 parts by mass, more preferably 10 to 40 parts by mass, based on 100 parts by mass of the resin (A). If the content is 5 parts by mass or more, the crosslinking reaction with the resin (A) is promoted, and a dense film excellent in curability is formed, so that a resist underlayer film having good heat resistance characteristics, dry etching resistance, and film thickness uniformity can be formed. On the other hand, if the content is 50 parts by mass or less, the generation of sublimates due to the inactivation of the crosslinking reaction between the resin (A) and the crosslinking agent (C) can be suppressed, and the generation of sublimates and the deterioration of film thickness uniformity can be reduced.

[0091] [(D) Surfactant] The resist underlayer film material of the present invention can contain (D) a surfactant in order to improve the coatability in spin coating. As the (D) surfactant, for example, those described in

[0142] to

[0147] of JP-A-2009-269953 can be used. When containing the (D) surfactant, the content is preferably 0.001 to 20 parts by mass, more preferably 0.01 to 10 parts by mass, based on 100 parts by mass of the resin having the compound represented by the above general formula (1A).

[0092] [(E) Acid generator] In the resist underlayer film material of the present invention, (E) an acid generator can be contained in order to further accelerate the curing reaction. The (E) acid generator includes those that generate an acid by thermal decomposition and those that generate an acid by light irradiation, and any of them can be contained. Specifically, the materials described in paragraphs

[0061] to

[0085] of JP-A-2007-199653 can be added, but are not limited thereto.

[0093] The above (E) acid generator can be used alone or in combination of two or more. When containing the (E) acid generator, the content is preferably 0.05 to 50 parts by mass, more preferably 0.1 to 10 parts by mass, based on 100 parts by mass of the resin having the compound represented by the above general formula (1A).

[0094] [(F) Plasticizer] In addition, the resist underlayer film material of the present invention can contain (F) a plasticizer in order to further improve the planarization / embedding characteristics. The (F) plasticizer is not particularly limited, and various known types of plasticizers can be widely used. As an example, low molecular weight compounds such as phthalic acid esters, adipic acid esters, phosphoric acid esters, trimellitic acid esters, and citric acid esters, and polymers such as polyether-based, polyester-based, and polyacetal-based polymers described in JP-A-2013-253227 can be exemplified. When containing the (F) plasticizer, the content is preferably 5 to 500 parts by mass, more preferably 10 to 200 parts by mass, based on 100 parts by mass of the resin having the compound represented by the above general formula (1A).

[0095] [(G) Dye] In addition, the resist underlayer film material of the present invention can contain (G) a dye in order to further improve the resolution during patterning of multilayer lithography. The (G) dye is not particularly limited as long as it is a compound having appropriate absorption at the exposure wavelength, and various known compounds can be widely used. As an example, benzenes, naphthalenes, anthracenes, phenanthrenes, pyrenes, isocyanuric acids, and triazines can be exemplified. When containing the (G) dye, the content is preferably 0.01 to 10 parts by mass, more preferably 0.1 to 5 parts by mass, based on 100 parts by mass of the resin having the compound represented by the above general formula (1A).

[0096] Furthermore, a basic compound for improving the storage stability can be added to the resist underlayer film material of the present invention. The basic compound serves as a quencher for acid to prevent the acid generated in a trace amount from the acid generator from promoting the crosslinking reaction. Specific examples of such basic compounds include those described in paragraphs (0086) to (0090) of JP-A-2007-199653.

[0097] In addition to the above, additives for further improving the embedding / planarization characteristics may be added to the resist underlayer film material of the present invention. The additives are not particularly limited as long as they impart embedding / planarization characteristics. For example, polyethylene glycol, a liquid additive having a polypropylene glycol structure, or a thermally decomposable polymer having a weight loss rate of 40% by mass or more between 30°C and 250°C and a weight average molecular weight of 300 to 200,000 is preferably used. This thermally decomposable polymer preferably contains a repeating unit having an acetal structure represented by the following general formulas (DP1) and (DP1a).

[0098]

Chemical formula

[0099]

Chemical formula

[0100] As described above, in the resist underlayer film material of the present invention, by using a resin having a compound represented by the above general formula (1A) in which the ratio of organic groups such as allyl groups and propargyl groups that contribute to improving fluidity and hydroxyl groups that contribute to improving substrate adhesion and heat resistance is controlled, it is possible to provide a material that highly combines embedding / planarization characteristics, substrate adhesion, and heat resistance. Therefore, the resist underlayer film material of the present invention is extremely useful as a resist underlayer film material for multilayer resist processes such as a two-layer resist process, a three-layer resist process using a resist intermediate film or an inorganic hard mask intermediate film, and a four-layer resist process using a resist intermediate film or an inorganic hard mask intermediate film and an organic thin film.

[0101] [Pattern formation method] In addition, in the present invention, a method for forming a pattern on a substrate to be processed, (I-1) A step of forming a resist underlayer film by applying the resist underlayer film material described above on the substrate to be processed and then performing heat treatment, (I-2) A step of forming a resist upper layer film on the resist underlayer film using a photoresist material, (I-3) A step of forming a pattern on the resist upper layer film by performing pattern exposure on the resist upper layer film and then developing with a developer, (I-4) A step of transferring the pattern to the resist underlayer film by dry etching using the resist upper layer film on which the pattern is formed as a mask, and (I-5) A step of processing the substrate to be processed using the resist underlayer film on which the pattern is formed as a mask to form a pattern on the substrate to be processed A pattern formation method having the above steps is provided (two-layer resist process).

[0102] Furthermore, a method for forming a pattern on a substrate to be processed, (II-1) A step of forming a resist underlayer film by applying the resist underlayer film material described above on the substrate to be processed and then performing heat treatment, (II-2) A step of forming a resist intermediate film on the resist underlayer film, (II-3) Forming a resist upper layer film on the resist intermediate film using a photoresist material; (II-4) After pattern-exposing the resist upper layer film, developing it with a developer to form a pattern in the resist upper layer film; (II-5) Using the resist upper layer film with the pattern formed thereon as a mask, transferring the pattern to the resist intermediate film by dry etching; (II-6) Using the resist intermediate film with the pattern transferred thereto as a mask, transferring the pattern to the resist lower layer film by dry etching, and (II-7) Using the resist lower layer film with the pattern formed thereon as a mask to process the substrate to be processed and form a pattern on the substrate to be processed provided is a pattern forming method (three-layer resist process) having the above steps.

[0103] In addition, a method for forming a pattern on a substrate to be processed, comprising: (III-1) After coating the resist lower layer film material described above on the substrate to be processed, forming a resist lower layer film by heat treatment; (III-2) Forming an inorganic hard mask intermediate film selected from a silicon oxide film, a silicon nitride film, and a silicon oxynitride film on the resist lower layer film; (III-3) Forming an organic thin film on the inorganic hard mask intermediate film; (III-4) Forming a resist upper layer film on the organic thin film using a photoresist material; (III-5) After pattern-exposing the resist upper layer film, developing it with a developer to form a pattern in the resist upper layer film; (III-6) Using the resist upper layer film with the pattern formed thereon as a mask, transferring the pattern to the organic thin film and the inorganic hard mask intermediate film by dry etching; (III-7) Using the inorganic hard mask intermediate film with the pattern transferred thereto as a mask, transferring the pattern to the resist lower layer film by dry etching, and (III-8) A step of processing the substrate to be processed using the resist underlayer film on which the pattern is formed as a mask to form a pattern on the substrate to be processed To provide a pattern formation method having (4-layer resist process).

[0104] The thickness of the resist underlayer film used in the present invention is appropriately selected, but it is preferably 50 to 5,000 nm, particularly preferably 100 to 2,000 nm, and more preferably 100 to 1,000 nm. In the case of a resist underlayer film for a 3-layer process, a resist intermediate film containing silicon and a resist upper layer film not containing silicon can be formed thereon. In the case of a resist underlayer film for a 2-layer process, a resist upper layer film containing silicon or a resist upper layer film not containing silicon can be formed thereon.

[0105] The pattern formation method of the present invention is suitably used for multilayer resist processes such as a silicon-containing 2-layer resist process, a 3-layer resist process using a resist intermediate film, a 4-layer resist process using an inorganic hard mask intermediate film and an organic thin film, and a 2-layer resist process not containing silicon.

[0106] [3-Layer Resist Process] The pattern formation method of the present invention will be described below by taking the 3-layer resist process as an example, but it is not limited to this process. In this case, a resist underlayer film is formed on the substrate using the above resist underlayer film material, a resist intermediate film is formed on the resist underlayer film using a resist intermediate film material containing silicon atoms, and a resist upper layer film of a photoresist composition is formed on the resist intermediate film to form a multilayer resist film. After exposing the pattern circuit region of the resist upper layer film, it is developed with a developer to form a resist pattern on the resist upper layer film. The resist intermediate film is etched using the resist upper layer film on which the pattern is formed as a mask, the resist underlayer film is etched using the resist intermediate film on which the pattern is formed as a mask, and further, the substrate can be processed using the resist underlayer film on which the pattern is formed as a mask to form a pattern on the substrate.

[0107] Since the resist intermediate film containing silicon atoms exhibits etching resistance to oxygen gas or hydrogen gas, as described above, it is preferable to perform the etching of the resist underlayer film using the resist intermediate film as a mask with an etching gas mainly composed of oxygen gas or hydrogen gas.

[0108] Also, in the pattern forming method of the present invention, at least, a resist underlayer film is formed on a substrate using the above resist underlayer film material, an inorganic hard mask intermediate film selected from a silicon oxide film, a silicon nitride film, and a silicon oxynitride film is formed on the resist underlayer film, a resist upper layer film is formed on the inorganic hard mask intermediate film using a resist upper layer film material composed of a photoresist composition, after exposing the pattern circuit region of the resist upper layer film, developing with a developer to form a resist pattern on the resist upper layer film, using the obtained resist pattern as an etching mask to etch the inorganic hard mask intermediate film, using the obtained inorganic hard mask intermediate film pattern as an etching mask to etch the resist underlayer film, and using the obtained resist underlayer film pattern as a mask to process the substrate to form a pattern on the substrate.

[0109] As described above, when forming an inorganic hard mask intermediate film on the resist underlayer film, a silicon oxide film, a silicon nitride film, or a silicon oxynitride film (SiON film) is formed by a CVD method, an ALD method, or the like. As a method for forming the nitride film, it is described in JP-A-2002-334869 and WO2004 / 066377. The film thickness of the inorganic hard mask intermediate film is 5 to 3,000 nm, preferably 10 to 2,000 nm. Among them, the SiON film having a high effect as an antireflection film is most preferably used for ArF exposure applications.

[0110] As the resist intermediate film in a three-layer resist process, a polysilsesquioxane-based resist intermediate film can be preferably used. The polysilsesquioxane-based resist intermediate film can easily have an antireflection effect in excimer exposure, thereby suppressing reflected light during pattern exposure of the upper resist film and having the advantage of excellent resolution. In particular, for 193 nm exposure, when a material containing many aromatic groups is used as the lower resist film, the k value increases and the substrate reflection increases. However, by suppressing reflection with the resist intermediate film, the substrate reflection can be reduced to 0.5% or less. As the resist intermediate film having an antireflection effect, anthracene for 248 nm and 157 nm exposure, and a polysilsesquioxane having a phenyl group or an absorbing group having a silicon-silicon bond pendent and crosslinked by an acid or heat is preferably used for 193 nm exposure.

[0111] In this case, forming the resist intermediate film by the spin coating method is simpler and more cost-effective than the CVD method.

[0112] The upper resist film in the three-layer resist film can be either positive or negative, and the same photo resist composition as the commonly used one can be used. When forming the upper resist film with the above photo resist composition, the spin coating method is preferably used in the same manner as when forming the lower resist film. After spin coating the photo resist composition, prebaking is performed, and the range of 60 to 180 °C for 10 to 300 seconds is preferable. Thereafter, exposure is performed according to a conventional method, post-exposure baking (PEB) and development are performed to obtain a resist pattern. The thickness of the upper resist film is not particularly limited, but 10 to 500 nm, particularly 20 to 400 nm is preferable.

[0113] In addition, as the exposure light, high energy rays with a wavelength of 300 nm or less, specifically, excimer lasers of 248 nm, 193 nm, 157 nm, soft X-rays of 3 to 20 nm, electron beams, X-rays, etc. can be mentioned.

[0114] Next, etching is performed using the obtained resist pattern as a mask. The etching of the resist intermediate film in the three-layer process is performed using a fluorocarbon-based gas with the resist pattern as a mask. Then, using the resist intermediate film pattern as a mask, the lower resist film is etched using oxygen gas or hydrogen gas.

[0115] The etching of the next substrate to be processed can also be performed by a conventional method. For example, if the substrate is SiO2, SiN, or a silica-based low dielectric constant insulating film, etching mainly using a fluorocarbon-based gas is performed. For p-Si, Al, or W, etching mainly using a chlorine-based or bromine-based gas is performed. When the substrate is etched with a fluorocarbon-based gas, the resist intermediate film in the three-layer process is peeled off simultaneously with the substrate processing. When the substrate is etched with a chlorine-based or bromine-based gas, it is necessary to separately perform dry etching peeling with a fluorocarbon-based gas or the like after the substrate processing to peel off the resist intermediate film.

[0116] Note that for the substrate to be processed, a layer to be processed is formed on the substrate. The substrate is not particularly limited, and materials different from the layer to be processed, such as Si, α-Si, p-Si, SiO2, SiN, SiON, W, TiN, and Al, are used. As the layer to be processed, various Low-k films such as Si, SiO2, SiON, SiN, p-Si, α-Si, W, TiN, W-Si, Al, Cu, and Al-Si, and their stopper films are used, and they are usually formed to a thickness of 50 to 15,000 nm, particularly 100 to 10,000 nm.

[0117] In the pattern formation method of the present invention, it is preferable to use, as the substrate to be processed, a substrate having a structure or step with a height of 30 nm or more. As described above, since the resist underlayer film material of the present invention has excellent embedding / planarization characteristics, even if the substrate to be processed has a structure or step (concavo-convex) with a height of 30 nm or more, a flat cured film can be formed. The height of the structure or step of the substrate to be processed is preferably 30 nm or more, more preferably 100 nm or more, still more preferably 200 nm or more, and particularly preferably 300 nm or more. In the method of processing a stepped substrate having a pattern with the above height, by forming the resist underlayer film material of the present invention and performing embedding / planarization, it becomes possible to make the film thicknesses of the resist intermediate film and the resist upper layer film to be formed thereafter uniform. Therefore, it becomes easy to secure the exposure depth margin (DOF) during photolithography, which is very preferable. Further, since the resist underlayer film material of the present invention has excellent adhesion to the substrate, it particularly exhibits an effect on the embedding / planarization of a pattern structure with a high aspect ratio. The aspect ratio of the above pattern is preferably 3 or more, more preferably 5 or more, and still more preferably 10 or more.

[0118] An example of a three-layer resist process is specifically shown as follows with reference to FIG. 1. In the case of a three-layer resist process, as shown in FIG. 1(A), after forming a resist underlayer film 3 on a processed layer 2 laminated on a substrate to be processed 1, a resist intermediate film 4 is formed, and a resist upper layer film 5 is formed thereon.

[0119] Next, as shown in FIG. 1(B), the exposed portion 6 of the upper resist film is exposed, and PEB (post-exposure bake) and development are performed to form an upper resist film pattern 5a (FIG. 1(C)). Using this obtained upper resist film pattern 5a as a mask, the intermediate resist film 4 is etched using a CF-based gas to form an intermediate resist film pattern 4a (FIG. 1(D)). After removing the upper resist film pattern 5a, the lower resist film 3 is etched with oxygen-based or hydrogen-based plasma using the obtained intermediate resist film pattern 4a as a mask to form a lower resist film pattern 3a (FIG. 1(E)). Further, after removing the intermediate resist film pattern 4a, the layer to be processed 2 is etched using the lower resist film pattern 3a as a mask to form a pattern 2a (FIG. 1(F)).

[0120] When using an inorganic hard mask intermediate film, the intermediate resist film 4 is an inorganic hard mask intermediate film, and when laying an organic thin film, an organic thin film is provided between the intermediate resist film 4 and the upper resist film 5. The etching of the organic thin film may be performed continuously prior to the etching of the intermediate resist film 4, or the etching of only the organic thin film may be performed and then the etching of the intermediate resist film 4 may be performed by changing the etching apparatus or the like.

[0121] [4-Layer Resist Process] In addition, the present invention can also be suitably used in a four-layer resist process using an organic thin film. In this case, at least, a resist lower layer film is formed on a substrate using the above resist lower layer film material, an inorganic hard mask intermediate film selected from a silicon oxide film, a silicon nitride film, and a silicon oxynitride film is formed on the resist lower layer film, an organic thin film is formed on the inorganic hard mask intermediate film, a resist upper layer film is formed on the organic thin film using a resist upper layer film material composed of a photoresist composition. After exposing the pattern circuit region of the resist upper layer film, it is developed with a developer to form a resist pattern on the resist upper layer film. Using the obtained resist pattern as an etching mask, the organic thin film and the inorganic hard mask intermediate film are etched. Using the obtained inorganic hard mask intermediate film pattern as an etching mask, the resist lower layer film is etched. Using the obtained resist lower layer film pattern as a mask, the substrate can be processed to form a pattern on the substrate.

[0122] A photoresist film may be formed as a resist upper layer film on the inorganic hard mask intermediate film. However, as described above, an organic thin film may be formed by spin coating on the inorganic hard mask intermediate film, and a photoresist film may be formed thereon. When a SiON film is used as the inorganic hard mask intermediate film and an organic antireflection film (BARC) having an absorptive group at the exposure wavelength is used as the organic thin film, it is possible to suppress reflection even in immersion lithography with a high NA exceeding 1.0 by the two-layer antireflection films of the SiON film and the organic thin film in excimer exposure. Another merit of forming the organic thin film is that it has an effect of reducing the undercut of the photoresist pattern directly on the SiON film. Also, when an adhesion film (ADL) having excellent affinity with the upper photoresist is used as the organic thin film, it is also an advantage that the pattern collapse of the photoresist can be suppressed.

[0123] [Resist Lower Layer Film Forming Method] The present invention provides a method for forming a resist underlayer film that functions as an organic planarizing film used in the manufacturing process of a semiconductor device. The method includes spin-coating the resist underlayer film material described above on a substrate to be processed, and heat-treating the substrate coated with the resist underlayer film material at a temperature of 100°C or higher and 600°C or lower for 10 to 600 seconds to form a cured film.

[0124] Alternatively, the present invention provides a method for forming a resist underlayer film that functions as an organic planarizing film used in the manufacturing process of a semiconductor device. The method includes spin-coating the resist underlayer film material described above on a substrate to be processed, and heat-treating the substrate coated with the resist underlayer film material in an atmosphere with an oxygen concentration of 1% or higher and 21% or lower to form a cured film.

[0125] Or, the present invention provides a method for forming a resist underlayer film that functions as an organic planarizing film used in the manufacturing process of a semiconductor device. The method includes spin-coating the resist underlayer film material described above on a substrate to be processed, and heat-treating the substrate coated with the resist underlayer film material in an atmosphere with an oxygen concentration of less than 1% to form a cured film.

[0126] In the method for forming a resist underlayer film of the present invention, the above-described resist underlayer film material is coated on a substrate to be processed using a spin coating method or the like. By using a spin coating method or the like, good embedding characteristics can be obtained. After spin coating, an organic solvent is evaporated, and baking is performed to promote a crosslinking reaction in order to prevent mixing with a resist upper layer film or a resist intermediate layer film. The baking is performed within a temperature range of 100°C or higher and 600°C or lower, preferably 100°C or higher and 450°C or lower, more preferably 150°C or higher and 400°C or lower, and is performed for 10 seconds to 600 seconds, preferably within a range of 10 to 300 seconds. By appropriately adjusting the baking temperature and time within the above ranges, flattening / embedding characteristics suitable for the application, and curing characteristics such as dry etching resistance and heat resistance can be obtained. When the baking temperature is 100°C or higher, curing proceeds sufficiently and mixing with the resist upper layer film or the resist intermediate film does not occur. If the baking temperature is 600°C or lower, thermal decomposition of the base resin can be suppressed, the film thickness does not decrease, and the film surface becomes uniform.

[0127] As the atmosphere during baking, either an oxygen-containing atmosphere such as in air (oxygen concentration 1% to 21%) or a non-oxygen atmosphere such as in nitrogen can be selected as needed. For example, when the substrate to be processed is easily oxidized by air, substrate damage can be suppressed by heat-treating in an atmosphere with an oxygen concentration of less than 1% to form a cured film.

[0128] The method for forming a resist underlayer film of the present invention preferably uses a substrate to be processed having a structure or step with a height of 30 nm or more. As described above, since the resist underlayer film material of the present invention has excellent embedding / planarization characteristics, even if the substrate to be processed has a structure or step (concavo-convex) with a height of 30 nm or more, a flat cured film can be formed. The height of the structure or step of the substrate to be processed is preferably 30 nm or more, more preferably 100 nm or more, even more preferably 200 nm or more, and particularly preferably 300 nm or more. In the method of processing a stepped substrate having the above height pattern, by forming the resist underlayer film material of the present invention and performing embedding / planarization, it becomes possible to make the film thicknesses of the resist intermediate film and the resist upper layer film to be formed thereafter uniform. Therefore, it becomes easy to secure the exposure depth margin (DOF) during photolithography, which is very preferable. In addition, since the resist underlayer film material of the present invention has excellent adhesion to the substrate, it particularly exhibits an effect on the embedding / planarization of a pattern structure with a high aspect ratio. The aspect ratio of the above pattern is preferably 3 or more, more preferably 5 or more, and even more preferably 10 or more.

Example

[0129] Hereinafter, the present invention will be specifically described by showing examples and comparative examples, but the present invention is not limited by these descriptions. The measurement of molecular weight and dispersity was carried out by the following methods. The weight average molecular weight (Mw) and dispersity (Mw / Mn) in terms of polystyrene were determined by gel permeation chromatography (GPC) using tetrahydrofuran as an eluent.

[0130] [Synthesis Example] In the following synthesis examples, the following compound groups G: (G1) to (G7) and modifiers H: (H1) to (H3) were used. Compound groups G: (G1) to (G7) are shown below.

[0131]

Chemical formula

[0132] The modifiers H: (H1) to (H3) are shown below.

Chemical formula

[0133] [Synthesis Example 1] Synthesis of Compound (A-1) Under a nitrogen atmosphere, 44.7 g of compound (G1), 16.5 g of potassium carbonate, and 150 g of DMF were added, and a homogeneous dispersion was obtained at an internal temperature of 50°C. 16.5 g of modifier (H1) was slowly added, and the reaction was carried out at an internal temperature of 50°C for 24 hours. 300 ml of methyl isobutyl ketone and 300 g of pure water were added to the reaction solution to dissolve the precipitated salt, and then the separated aqueous layer was removed. Further, the organic layer was washed 6 times with 100 g of 3% aqueous nitric acid solution and 100 g of pure water, and then the organic layer was dried under reduced pressure to obtain compound (A-1). When the weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, the following results were obtained. (A-1): Mw = 542, Mw / Mn = 1.02

[0134] [Synthesis Examples 2 to 14] Synthesis of Compounds (A-2) to (A-14) Compounds (A-2) to (A-14) shown in Tables 1 to 3 were obtained under the same reaction conditions as in Synthesis Example 1, except that the compound group G, modifier group H, and potassium carbonate were used in the amounts shown in Tables 1 to 3.

[0135]

Table 1

[0136]

Table 2

[0137]

Table 3

[0138] [Synthesis Example 15] Synthesis of Compound (A-15) [Chemical formula] Under a nitrogen atmosphere, 90.1 g of compound (G1), 9.7 g of 37% formalin solution, and 270 g of 2-methoxy-1-propanol were added. After making a homogeneous solution at a liquid temperature of 80 °C, 18 g of a 2-methoxy-1-propanol solution of 20% paratoluenesulfonic acid was slowly added, and the mixture was stirred at a liquid temperature of 110 °C for 8 hours. After cooling to room temperature, 600 g of methyl isobutyl ketone was added. The organic layer was washed 5 times with 200 g of pure water, and then the organic layer was dried to dryness under reduced pressure. 320 g of THF was added to the residue, and the polymer was reprecipitated with 1350 g of hexane. The precipitated polymer was separated by filtration and dried under reduced pressure to obtain compound (A-15). When the weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, the following results were obtained. Mw = 3460, Mw / Mn = 4.60

[0139] The structures of the obtained compounds, the weight average molecular weight (Mw), and the dispersity (Mw / Mn) are shown in Tables 4 to 6. Note that for compound (A-16), (G4) of the compound group G used as a raw material in the synthesis example was used.

[0140] [Table 4]

[0141] [Table 5]

[0142] [Table 6]

[0143] [(C) Crosslinking agent] Each (C) crosslinking agent used for the resist underlayer film material is shown below. [Chemical formula]

[0144] [Resist underlayer film material UL-1] The above compound (A-1) was dissolved in propylene glycol monomethyl ether acetate (PGMEA) containing 0.5% by mass of surfactant FC-4430 (manufactured by Sumitomo 3M Limited) at the ratio shown in Table 7, and filtered through a 0.02 μm membrane filter to prepare a resist underlayer film material (UL-1).

[0145] [Resist underlayer film materials UL-2 to 15 and Comparative UL-1 to 7] Except that the types and contents of the respective components were as shown in Table 7, the same operations as those for UL-1 were performed to prepare each chemical solution. In Table 7, "-" indicates that the corresponding component was not used. The following formula (E-1) was used as the acid generator (TAG), and 1,6-diacetoxyhexane: boiling point 260 °C was used as the high-boiling solvent (B-2). [Chemical formula] (Thermal acid generator)

[0146] [Table 7]

[0147] [Heat resistance property evaluation] Each of the above resist underlayer film materials (UL-1 to 15 and Comparative UL-1 to 7) was applied onto a silicon substrate and baked at 400 °C for 60 seconds to form a resist underlayer film having a film thickness of about 600 nm, and the film thickness T1 after baking at 400 °C was measured. An additional baking treatment was performed on this substrate at 550 °C for 60 seconds under a nitrogen stream in which the oxygen concentration was controlled to 0.2% or less, the film thickness T2 after baking at 550 °C was measured, and from these measurement results, the film reduction rate represented by T2 / T1 was calculated. When the value of the film reduction rate [T2 / T1] was 95% or more, it was evaluated as "A" (extremely good), when it was 90% or more and less than 95%, it was evaluated as "B" (good), and when it was less than 90%, it was evaluated as "C" (poor). The results are shown in Table 8.

[0148]

Table 8

[0149] As shown in Table 8, in the resist underlayer film materials (Examples 1-1 to 1-15) of the present invention, the decrease in film thickness after baking at 550 °C was as small as 10% or less, indicating that they have heat resistance properties at 550 °C or higher. Among these, Examples 1-3 to 1-10 containing a compound having two caldo structures have good heat resistance properties. Furthermore, Examples 1-11 and 1-12 combined with a crosslinking agent have shown results of more excellent heat resistance properties. This is presumably because the inclusion of the above crosslinking agent allows the crosslinking reaction of the resin to proceed in a high dimension, enabling the formation of a cured film with a high crosslink density. Comparing Examples 1-5 to 6, Examples 1-13 to 14, Comparative Examples 1-2 to 1-4, and Comparative Example 1-6, which contain the same skeletal structure and have the R configuration range changed, it was found that a higher proportion of hydroxyl groups results in the formation of a film with more excellent heat resistance properties.

[0150] [Evaluation of Embedding Characteristics] Each of the above resist underlayer film materials (UL-1 to 15 and Comparative UL-1 to 7) was applied onto a SiO2 wafer substrate having a densely packed hole pattern (hole diameter: 0.2 μm, hole depth: 1.0 μm, distance between the centers of two adjacent holes: 0.4 μm) that had been treated with HMDS, and heated at 400 °C for 60 seconds using a hot plate to form a resist underlayer film A. Separately from the resist underlayer film A, a bake was performed at 550 °C for 60 seconds under a nitrogen stream in which the oxygen concentration was controlled to 0.2% or less to form a resist underlayer film B. The substrate used was a base substrate 7 (SiO2 wafer substrate) having a densely packed hole pattern as shown in FIGS. 2(G) (plan view) and (H) (cross-sectional view). The cross-sectional shape of each obtained wafer substrate was observed using an electron microscope (S-4700) manufactured by Hitachi, Ltd., to confirm whether the holes were filled with the resist underlayer film without voids (gaps) inside the holes, and whether peeling had occurred at the interface between the resist underlayer film and the substrate. The results are shown in Table 9. When a resist underlayer film material with poor embedding characteristics was used, voids occurred inside the holes in this evaluation. Also, when a resist underlayer film material with poor adhesion was used, peeling occurred at the interface between the resist underlayer film and the substrate in this evaluation. When a resist underlayer film material with good embedding characteristics and good adhesion to the substrate was used, in this evaluation, as shown in FIG. 2(I), the holes in the base substrate 7 having a densely packed hole pattern were filled with a resist underlayer film 8 without voids and without peeling from the substrate.

[0151]

Table 9

[0152] As shown in Table 9, in Examples 2-1 to 2-15 using the resist underlayer film materials (UL-1 to 15) of the present invention, among the structures constituting R1 included in the general formula (1B), when the ratio of hydrogen atoms is a and the ratio of an alkyl group having 1 to 10 carbon atoms or the structure represented by the general formula (1C) is b, since the compound represented by the general formula (1A) satisfying the relationship of a + b = 1 and 0.2 ≤ b ≤ 0.8 is used for the whole of the component (A), it was found that the embedding characteristics after baking at 400 °C and 550 °C are good.

[0153] Further, in Examples 2-13 and 14 in which Compounds A-12 and A-16 that do not satisfy the above relationship alone were blended so as to satisfy the above relationship, it was found that the embedding characteristics after baking at 400 °C and 550 °C are good. Thus, even if the compound represented by the general formula (1A) contained in the resist underlayer film material of the present invention does not satisfy the above relationship alone, if the whole of the component (A) satisfies the above relationship, a resist underlayer film material having good embedding characteristics after baking at 400 °C and 550 °C can be provided.

[0154] On the other hand, in Comparative Example 2-4 and Comparative Example 2-6, since the ratio of b among the structures constituting R1 is less than 0.2 and the fluidity is insufficient, voids were observed after baking at both 400 °C and 550 °C. In Comparative Examples 2-1 to 2-3, since the ratio of b exceeds 0.8, the adhesion to the substrate becomes insufficient, and peeling of the resist underlayer film from the substrate was observed after baking at both 400 °C and 550 °C. Further, in Comparative Examples 2-5 and 2-7 containing a polymer, since the molecular weight of the resin is large and the fluidity is insufficient, voids were observed after baking at both 400 °C and 550 °C.

[0155] From the above results, in the resist underlayer film material of the present invention, by using a resin having a compound in which the ratio of an organic group contributing to the improvement of fluidity and a hydroxyl group contributing to the improvement of adhesion to the substrate is controlled, a resist underlayer film material having excellent embedding characteristics and adhesion to the substrate can be provided.

[0156] [Planarization characteristic evaluation] Each of the above-mentioned resist underlayer film materials (UL-1 to 15 and Comparative UL-1 to 7) was applied onto a SiO2 wafer substrate having a densely packed hole pattern (hole diameter 0.2 μm, hole depth 1.0 μm, distance between the centers of two adjacent holes 0.4 μm) that had been treated with HMDS, and baked at 400 °C for 60 seconds using a hot plate to form a resist underlayer film. The substrate used was a base substrate 9 (SiO2 wafer substrate) having a densely packed hole pattern as shown in Fig. 3(J). The cross-sectional shape of each obtained wafer substrate was observed using a scanning electron microscope (SEM), and the step (Delta 10 in Fig. 3(K)) of the resist underlayer film 10 between the densely packed hole pattern portion and the non-hole pattern forming portion was observed using an electron microscope (S-4700) manufactured by Hitachi, Ltd. In this evaluation, it can be said that the smaller the step, the better the planarization characteristics. Note that in this evaluation, a hole pattern with a depth of 1.0 μm was planarized using a resist underlayer film material with a normal film thickness of about 600 nm, and the evaluation conditions are severe in order to evaluate the superiority or inferiority of the planarization characteristics. When the step of the resist underlayer film was less than 300 nm, it was evaluated as "A" (extremely good), when it was 300 nm or more and less than 350 nm, it was evaluated as "B" (good), and when it was 350 nm or more, or when peeling of the resist underlayer film from the substrate was observed, it was evaluated as "C" (bad). The results are shown in Table 10.

[0157]

Table 10

[0158] As shown in Table 10, in Examples 3-1 to 3-15 using the resist underlayer film material (UL-1 to 15) of the present invention, among the structures constituting the above-mentioned R1 included in the above general formula (1B), when the ratio of hydrogen atoms is a and the ratio of an alkyl group having 1 to 10 carbon atoms or the structure represented by the above general formula (1C) is b, since the compound represented by the above general formula (1A) that satisfies the relationship of a + b = 1 and 0.2 ≤ b ≤ 0.8 in the whole component (A) is used, it was found that the planarization characteristics after baking at 400 °C are good in the densely packed hole pattern.

[0159] In addition, in Examples 3-13 and 14 in which compounds A-12 and A-16 that do not satisfy the above relationship alone were blended to satisfy the above relationship, it was found that the planarization characteristics after baking at 400 °C were good. Thus, even if the compound represented by the general formula (1A) contained in the resist underlayer film material of the present invention does not satisfy the above relationship alone, as long as the whole component (A) satisfies the above relationship, a resist underlayer film material with good planarization characteristics after baking at 400 °C can be provided.

[0160] On the other hand, in Comparative Examples 3-4 and 3-6, the proportion of b in the structure constituting R1 was less than 0.2, and due to insufficient fluidity, deterioration of the planarization characteristics was observed. In Comparative Examples 3-1 to 3-3, since the proportion of b exceeded 0.8, the adhesion to the substrate was insufficient, and peeling of the resist underlayer film from the substrate was observed. Further, in Comparative Examples 3-5 and 3-7 containing a polymer, deterioration of the planarization characteristics was observed due to insufficient fluidity.

[0161] Comparing Examples 3-5, 3-6, 3-13, 3-14, Comparative Examples 3-4, and 3-6, which have the same skeletal structure and in which the composition range of R1 is changed, it was found that Examples 3-5 and 3-6 in which the proportion of b is 0.4 ≦ b ≦ 0.6 exhibit particularly excellent flatness. This is presumably because the balance between the organic group contributing to fluidity and the hydroxyl group contributing to adhesion and heat resistance characteristics is optimal, and a film excellent in thermal fluidity and heat shrinkage resistance could be formed. Examples 3-11 and 3-12 using a crosslinking agent can form a dense film with excellent heat resistance characteristics, and thus show even better planarization characteristics than the resin single composition.

[0162] [Pattern etching test] Each of the above resist underlayer film materials (UL-1 to 15 and Comparative UL-1 to 7) was applied onto a SiO2 wafer substrate having an HMDS-treated trench pattern (trench width: 10 μm, trench depth: 0.50 μm), and heated at 400 °C for 60 seconds using a hot plate to form a resist underlayer film with a film thickness of 600 nm. A resist intermediate film material (SOG-1) was applied onto this resist underlayer film and baked at 220 °C for 60 seconds to form a resist intermediate film (SOG-1 film) with a film thickness of 35 nm. A resist upper layer film material (ArF SL resist) was applied and baked at 105 °C for 60 seconds to form a resist upper layer film with a film thickness of 100 nm. A liquid immersion protective film material (TC-1) was applied onto the resist upper layer film and baked at 90 °C for 60 seconds to form a protective film with a film thickness of 50 nm.

[0163] As the resist upper layer film material (ArF SL resist), a polymer (RP1), an acid generator (PAG1), and a basic compound (Amine1) were dissolved in an organic solvent containing 0.1 mass% of FC-430 (manufactured by Sumitomo 3M Limited) at the ratios shown in Table 11, and filtered through a 0.1-μm fluororesin filter.

[0164]

Table 11

[0165] The structural formulas of the polymer (RP1), acid generator (PAG1), and basic compound (Amine1) used are shown below.

Chemical formula

[0166] As the liquid immersion protective film material (TC-1), a protective film polymer (PP1) was dissolved in an organic solvent at the ratios shown in Table 12, and filtered through a 0.1-μm fluororesin filter.

[0167]

Table 12

[0168] The structural formula of the protective film polymer (PP1) used is shown below.

Chemical formula

[0169] As the resist intermediate film material (SOG-1), a polymer represented by an ArF silicon-containing intermediate film polymer (SiP1) and a thermal crosslinking catalyst (CAT1) were dissolved in an organic solvent containing 0.1% by mass of FC-4430 (manufactured by Sumitomo 3M Limited) at the ratios shown in Table 13, and filtered through a fluororesin filter with a pore size of 0.1 μm to prepare the resist intermediate film material (SOG-1).

[0170]

Table 13

[0171] The structural formulas of the ArF silicon-containing intermediate film polymer (SiP1) and the thermal crosslinking catalyst (CAT1) used are shown below.

Chemical formula

[0172] Next, exposure was performed using an ArF immersion exposure apparatus (manufactured by Nikon Corporation; NSR-S610C, NA1.30, σ0.98 / 0.65, 35-degree dipole s-polarized illumination, 6% halftone phase shift mask), baking (PEB) was performed at 100 °C for 60 seconds, and development was performed for 30 seconds with a 2.38% by mass aqueous solution of tetramethylammonium hydroxide (TMAH) to obtain a 55 nm 1:1 positive line-and-space pattern.

[0173] Next, using a dry etching apparatus Telius manufactured by Tokyo Electron Limited, the resist upper layer film pattern by dry etching was used as an etching mask to process the SOG-1 film, the SOG-1 film pattern was used as an etching mask to process the resist lower layer film, and the resist lower layer film pattern was used as an etching mask to process the SiO2 film. The etching conditions are as shown below.

[0174] Transfer conditions of the resist upper layer film pattern to the SOG-1 film. Chamber pressure 10.0 Pa RF power 1,500 W CF4 gas flow rate 15 sccm O2 gas flow rate 75 sccm Time 15 sec

[0175] Transfer conditions of the SOG-1 film pattern to the resist lower layer film. Chamber pressure 2.0 Pa RF power 500 W Ar gas flow rate 75 sccm O2 gas flow rate 45 sccm Time 240 sec

[0176] Transfer conditions of the resist lower layer film pattern to the SiO2 film. Chamber pressure 2.0 Pa RF power 2,200 W C5F 12 Gas flow rate 20 sccm C2F6 gas flow rate 10 sccm Ar gas flow rate 300 sccm O2 gas flow rate 60 sccm Time 180 sec

[0177] Each of the above resist lower layer film materials (UL-1 to 15 and comparative UL-1 to 7) was applied onto a SiO2 wafer substrate having an HMDS-treated trench pattern (trench width 10 μm, trench depth 0.50 μm), and a coating film was formed in the same manner as in the pattern etching test except that it was baked at 550 °C under a nitrogen stream in which the oxygen concentration was controlled to 0.2% or less, and patterning and dry etching were performed, and the resulting pattern shape was observed.

[0178] Table 14 shows the results of observing the pattern cross-section with an electron microscope (S-4700) manufactured by Hitachi, Ltd.

[0179]

Table 14

[0180] As shown in Table 14, in Examples 4-1 to 4-15 using the resist underlayer film materials (UL-1 to 15) of the present invention, in all cases, the resist upper layer film pattern was finally successfully transferred to the substrate, and it was confirmed that the resist underlayer film material of the present invention is suitably used for fine processing by the multilayer resist method. On the other hand, in Comparative Examples 4-1 to 4-7 where deficiencies in performance were confirmed in the heat resistance property evaluation, embedding property evaluation, and planarization property evaluation after baking at each of 400°C and 550°C, pattern collapse occurred during pattern processing, and finally a good pattern could not be obtained.

[0181] From the above, the resist underlayer film material of the present invention has good dry etching resistance, has both high embedding / planarization properties / adhesion to the substrate, and further has heat resistance properties of 500°C or higher. Therefore, it is extremely useful as a resist underlayer film material used in the multilayer resist method. Also, in the pattern forming method of the present invention using this, it has become clear that even if the object to be processed is a substrate having steps, a fine pattern can be formed with high precision.

[0182] Note that the present invention is not limited to the above-described embodiments. The above-described embodiments are examples, and anything having a configuration substantially the same as the technical idea described in the claims of the present invention and exhibiting the same operational effects is included in the technical scope of the present invention.

Explanation of Reference Numerals

[0183] 1... Substrate to be processed, 2... Layer to be processed, 2a... Pattern (pattern formed on the layer to be processed), 3... Resist underlayer film, 3a... Resist underlayer film pattern, 4... Resist intermediate film, 4a... Resist intermediate film pattern, 5... Resist upper layer film, 5a…Resist upper layer film pattern, 6…Exposed part 7…Lower base substrate with dense hole pattern, 8…Resist lower layer film 9…Lower base substrate with dense hole pattern, 10…Resist lower layer film Delta 10…Step of the resist lower layer film 10 between the dense hole pattern part and the non-hole pattern forming part

Claims

1. A resist underlayer film material used in a multilayer resist method, comprising: (A) a resin having a compound represented by the following general formula (1A), and (B) an organic solvent, wherein the ratio Mw / Mn of the weight average molecular weight Mw to the number average molecular weight Mn in terms of polystyrene by gel permeation chromatography of the compound represented by the general formula (1A) is 1.00 ≦ Mw / Mn ≦ 1.

25. In the general formula (1A), X is a group represented by the following general formula (1B). In the general formula (1B), R １ is any one of a hydrogen atom, an organic group having 1 to 10 carbon atoms, and a structure represented by the following general formula (1C). Among the structures constituting the R １ when the ratio of the hydrogen atom is a and the ratio of the organic group having 1 to 10 carbon atoms or the structure represented by the general formula (1C) is b, the resist underlayer film material is characterized in that a + b = 1 and 0.2 ≦ b ≦ 0.8 in the whole component (A). 【Chemical 1】 【Chemical 2】 (In the general formula (1B), n １ is 0 or 1, and n ２ is 1 or 2, R １ is any one of a hydrogen atom, an organic group having 1 to 10 carbon atoms, and a structure represented by the following general formula (1C). Among the structures constituting the said R １ when the ratio of the hydrogen atom is a and the ratio of the organic group having 1 to 10 carbon atoms or the structure represented by the said general formula (1C) is b, it satisfies the relationship of a + b = 1 and 0.2 ≦ b ≦ 0.8 in the whole component (A). X ２ is a group represented by the following general formula (1D), and n ３ is 0, 1, or 2.) [Chemical 3] (In general formula (1C), * represents a bonding site to an oxygen atom, and R Ａ is a divalent organic group having 1 to 10 carbon atoms, and R Ｂ is a hydrogen atom or a monovalent organic group having 1 to 10 carbon atoms.) 【Chemical Formula 4】 (In the general formula (1D), R ２ is a hydrogen atom or a saturated or unsaturated hydrocarbon group having 1 to 10 carbon atoms, and the hydrogen atom on the benzene ring in the general formula (1D) may be substituted with a methyl group or a methoxy group.)

2. In the general formula (1B), R １ The resist underlayer film material according to claim 1, wherein the constituent of is composed of either a hydrogen atom or the following general formula (1F). 【Chemical Formula 5】 (In the general formula (1F), * represents the bonding site to the oxygen atom.)

3. The resist underlayer film material according to claim 1 or claim 2, wherein the weight average molecular weight of the compound represented by the general formula (1A) is 2,500 or less.

4. The resist underlayer film material according to any one of claims 1 to 3, wherein the resist underlayer film material further contains (C) a crosslinking agent.

5. The resist underlayer film material according to claim 4, wherein the content of the (C) crosslinking agent is 5 to 50 parts by mass with respect to 100 parts by mass of the (A) resin.

6. The resist underlayer film material according to any one of claims 1 to 5, wherein the resist underlayer film material further contains one or more of (D) a surfactant, (E) an acid generator, (F) a plasticizer, and (G) a pigment.

7. The resist underlayer film material according to any one of claims 1 to 6, wherein the (B) organic solvent contains a high-boiling solvent, and the high-boiling solvent is one or more organic solvents having a boiling point of 180 °C or higher.

8. A method for forming a pattern on a substrate to be processed, comprising: (I-1) A step of forming a resist underlayer film by applying the resist underlayer film material according to any one of claims 1 to 7 on a substrate to be processed and then performing a heat treatment; (I-2) A step of forming a resist upper layer film on the resist underlayer film using a photoresist material; (I-3) A step of forming a pattern on the resist upper layer film by pattern exposure and then developing with a developer; (I-4) A step of transferring the pattern to the resist underlayer film by dry etching using the resist upper layer film on which the pattern is formed as a mask; and (I-5) A step of processing the substrate to be processed using the resist underlayer film on which the pattern is formed as a mask to form a pattern on the substrate to be processed A pattern forming method characterized by comprising the above steps.

9. A method for forming a pattern on a substrate to be processed, comprising: (II-1) A step of forming a resist underlayer film by applying the resist underlayer film material according to any one of claims 1 to 7 on a substrate to be processed and then performing a heat treatment; (II-2) A step of forming a resist intermediate film on the resist underlayer film; Step (II-3): forming a resist upper layer film on the resist intermediate film using a photoresist material; Step (II-4): after pattern-exposing the resist upper layer film, developing with a developer to form a pattern in the resist upper layer film; Step (II-5): using the resist upper layer film with the pattern formed thereon as a mask, transferring the pattern to the resist intermediate film by dry etching; Step (II-6): using the resist intermediate film with the pattern transferred thereto as a mask, transferring the pattern to the resist lower layer film by dry etching; and Step (II-7): using the resist lower layer film with the pattern formed thereon as a mask, processing the substrate to be processed to form a pattern in the substrate to be processed A pattern forming method characterized by comprising the above steps.

10. A method for forming a pattern in a substrate to be processed, comprising: Step (III-1): forming a resist lower layer film by applying the resist lower layer film material according to any one of Claims 1 to 7 on the substrate to be processed and then performing a heat treatment; Step (III-2): forming an inorganic hard mask intermediate film selected from a silicon oxide film, a silicon nitride film, and a silicon oxynitride film on the resist lower layer film; Step (III-3): forming an organic thin film on the inorganic hard mask intermediate film; Step (III-4): forming a resist upper layer film on the organic thin film using a photoresist material; Step (III-5): after pattern-exposing the resist upper layer film, developing with a developer to form a pattern in the resist upper layer film; Step (III-6): using the resist upper layer film with the pattern formed thereon as a mask, transferring the pattern to the organic thin film and the inorganic hard mask intermediate film by dry etching; Step (III-7): using the inorganic hard mask intermediate film with the pattern transferred thereto as a mask, transferring the pattern to the resist lower layer film by dry etching; and Step (III-8): using the resist lower layer film with the pattern formed thereon as a mask, processing the substrate to be processed to form a pattern in the substrate to be processed A pattern forming method characterized by comprising the above steps.

11. The pattern forming method according to any one of Claims 8 to 10, characterized in that a substrate having a structure or step with a height of 30 nm or more is used as the substrate to be processed.

12. A method for forming a resist underlayer film that functions as an organic planarizing film used in a semiconductor device manufacturing process, comprising spin-coating a resist underlayer film material according to any one of claims 1 to 7 on a substrate to be processed, and heat-treating the substrate coated with the resist underlayer film material at a temperature of 100°C or higher and 600°C or lower for 10 to 600 seconds to form a cured film. A resist underlayer film forming method characterized by the above.

13. A method for forming a resist underlayer film that functions as an organic planarizing film used in a semiconductor device manufacturing process, comprising spin-coating a resist underlayer film material according to any one of claims 1 to 7 on a substrate to be processed, and heat-treating the substrate coated with the resist underlayer film material in an atmosphere with an oxygen concentration of 1% or more and 21% or less to form a cured film. A resist underlayer film forming method characterized by the above.

14. A method for forming a resist underlayer film that functions as an organic planarizing film used in a semiconductor device manufacturing process, comprising spin-coating a resist underlayer film material according to any one of claims 1 to 7 on a substrate to be processed, and heat-treating the substrate coated with the resist underlayer film material in an atmosphere with an oxygen concentration of less than 1% to form a cured film. A resist underlayer film forming method characterized by the above.

15. The resist underlayer film forming method according to any one of claims 12 to 14, characterized in that a substrate having a structure or step with a height of 30 nm or more is used as the substrate to be processed.

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