Composition for forming metal oxide film, pattern forming method, and method for forming metal oxide film

Abstract

To provide a composition for forming a metal oxide film, a method for forming a pattern, and a method for forming a resist underlayer film, which have excellent dry etching resistance, excellent embedding properties, and can reduce cracks caused by thickening of the film.SOLUTION: A composition for forming a metal oxide film includes metal oxide nanoparticles, a structure having a fluidity promoter containing a resin having a structural unit represented by the following formula (1), and two or more benzene rings or one benzene ring, and a dispersion stabilizer and an organic solvent consisting of an aromatic-containing compound with a molecular weight of 500 or less, and the content of the fluidity promoter in the entire composition is 9 mass% or more, Mw / Mn is 2.50≤Mw / Mn≤9.00, and no cardo structure is included.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a composition for forming a metal oxide film, a pattern forming method, and a method for forming a metal oxide film. [Background technology]

[0002] As LSIs become more highly integrated and faster, pattern dimensions are becoming increasingly fine. Lithography technology has achieved this by shortening the wavelength of light sources and selecting appropriate resist compositions to match. Single-layer positive photoresist compositions have become the key to this. These single-layer positive photoresist compositions incorporate a backbone that provides etching resistance to dry etching with chlorine- or fluorine-based gas plasma, and a switching mechanism that dissolves exposed areas. This allows the exposed areas to be dissolved to form a pattern, and the remaining resist pattern is then used as an etching mask to dry etch the substrate.

[0003] However, if the thickness of the photoresist film used is made finer, i.e., the pattern width is made smaller, the resolution of the photoresist film decreases, and when an attempt is made to develop the photoresist film into a pattern using a developer, the aspect ratio becomes too large, resulting in pattern collapse. For this reason, photoresist films have been made thinner as patterns become finer.

[0004] On the other hand, substrate processing typically involves dry etching using a patterned photoresist film as an etching mask. However, in reality, no dry etching method can achieve perfect etching selectivity between the photoresist film and the substrate. As a result, the photoresist film can be damaged and disintegrated during substrate processing, preventing accurate transfer of the resist pattern to the substrate. Therefore, as patterns become finer, resist compositions are required to have higher dry etching resistance. However, to improve resolution, resins used in photoresist compositions must have low light absorption at the exposure wavelength. As a result, as exposure light wavelengths have become shorter (i-line, KrF, and ArF), resins have evolved, such as novolac resins, polyhydroxystyrenes, and resins with aliphatic polycyclic skeletons. However, in reality, the etching rates under dry etching conditions during substrate processing have become faster, and recent photoresist compositions with high resolution tend to have weaker etching resistance.

[0005] This means that substrates to be processed must be dry etched using thinner photoresist films with weaker etching resistance, and there is an urgent need to secure the materials and processes required for this processing step.

[0006] One method for solving these problems is the multilayer resist method, in which a resist intermediate film having an etching selectivity different from that of a photoresist film (i.e., a resist upper layer film) is interposed between the resist upper layer film and the substrate to be processed, a pattern is formed on the resist upper layer film, and then the pattern is transferred to the resist intermediate film by dry etching using the resist upper layer film pattern as a dry etching mask, and the pattern is further transferred to the substrate to be processed by dry etching using the resist intermediate film as a dry etching mask.

[0007] One type of multilayer resist method is the three-layer resist method, which can be performed using a typical resist composition used in single-layer resist methods. In this three-layer resist method, for example, an organic film made of a novolac resin or the like is deposited on a substrate to be processed as a resist underlayer, a silicon-containing resist intermediate film is deposited on top of that as a resist intermediate film, and a conventional organic photoresist film is deposited on top of that as a resist upper layer. When dry etching is performed using a fluorine-based gas plasma, the organic resist upper layer exhibits a favorable etching selectivity relative to the silicon-containing resist intermediate film, allowing the resist upper layer pattern to be transferred to the silicon-containing resist intermediate film by dry etching with a fluorine-based gas plasma. This method allows for pattern transfer to the silicon-containing resist intermediate film (resist intermediate film) even when using a resist composition that is difficult to directly form a pattern with a sufficient thickness for processing the substrate or that does not have sufficient dry etching resistance for substrate processing. Subsequent pattern transfer by dry etching with an oxygen- or hydrogen-based gas plasma allows for the formation of a pattern in an organic film (resist underlayer) made of a novolac resin or the like that has sufficient dry etching resistance for substrate processing. Many resist underlayer films such as those described above are already known, for example, those described in Patent Document 1.

[0008] Meanwhile, in recent years, the trend toward higher stacking density in 3D-NAND memory has accelerated, increasing the need for thick-film resist underlayer materials that combine void-free filling properties that enable high-aspect-ratio patterned substrates to be filled with them, and excellent dry-etching resistance that enables highly accurate transfer of fine structure patterns to workpiece substrates. Thick-film organic underlayer materials with excellent filling properties have been reported, such as those described in Patent Document 2. However, considering application in advanced generations, there are concerns about dry-etching resistance, and conventional coating-type organic underlayer materials are approaching their application limits.

[0009] To address the dry etching resistance issue of coating-type organic resist underlayer film materials, the use of a metal oxide film as a resist underlayer film has attracted attention. However, metal oxide materials alone have insufficient fluidity, making it difficult to fill high-aspect ratio pattern substrates. Therefore, compositions to which an organic material has been added to improve fluidity are preferred. Compositions in which an organic material has been added to a metal oxide compound have been reported in Patent Documents 3 and 4. Although no mention is made of filling properties, the metal oxide dicarboxylate used in Patent Document 3 and the hydrolysis condensate of the metal alkoxide used in Patent Document 4 have large thermal shrinkage, which induces significant deterioration in filling properties, raising concerns that they may be insufficient as resist underlayer film materials that require high filling properties.

[0010] In response to this, a composition for forming a metal oxide film has been proposed in which a high-carbon polymer is added to metal oxide nanoparticles (Patent Document 5). It has been reported that the use of metal oxide nanoparticles with low thermal shrinkage relative to a metal oxide compound can improve the embedding characteristics of the metal oxide compound. The addition of a high-carbon polymer as a fluidity promoter for metal oxide nanoparticles has also been proposed, but the thermal fluidity of the high-carbon polymer is insufficient, raising concerns that it may be insufficient to fill high-aspect-ratio patterned substrates. Furthermore, the high-carbon polymer has a high carbon content and a rigid structure, raising concerns that cracks may occur when a thick film is formed.

[0011] Examples of organic materials with excellent dry etching resistance and thermal fluidity include materials with a fluorene skeleton having a cardo structure. Resist underlayer film materials exist that combine a compound or polymer with a cardo structure as a thermal fluidity promoter with metal oxide nanoparticles. While these materials have excellent dry etching resistance and filling properties, the thermal fluidity promoter has a high carbon content and a rigid cardo structure, which has been shown to cause cracking when thickened. Furthermore, it has been shown that as a sacrificial film for filling advanced 3D-NAND, it has insufficient filling ability for high aspect ratio patterned substrates. Furthermore, increasing the concentration of the composition to a level sufficient for thick film formation leads to the aggregation of nanoparticles, resulting in defects, and thus insufficient storage stability. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-205685 [Patent Document 2] Patent No. 6550760 [Patent Document 3] Patent No. 6342998 [Patent Document 4] Patent No. 5756134 [Patent Document 5] Patent No. 7008075 Summary of the Invention [Problem to be solved by the invention]

[0013] The present invention has been made in view of the above circumstances, and aims to provide a metal oxide film-forming composition that has superior dry etching resistance compared to conventional organic underlayer film materials, superior filling properties compared to conventional metal hard masks, can reduce cracks that accompany thickening, and has excellent storage stability, a pattern formation method using this material, and a metal oxide film (resist underlayer film) formation method. [Means for solving the problem]

[0014] In order to solve the above problems, the present invention provides a metal oxide film-forming composition, comprising: (A) metal oxide nanoparticles; (B) a flowability promoter containing a resin having a structural unit represented by the following general formula (1): (C) a dispersion stabilizer consisting of an aromatic-containing compound containing two or more benzene rings, or one benzene ring and a structure represented by the following general formula (C-1), and having a molecular weight represented by a molecular formula of 500 or less; and (D) contains an organic solvent, The present invention provides a metal oxide film-forming composition, in which the content of the flow promoter (B) relative to the total composition is 9 mass % or more, the ratio Mw / Mn of the weight average molecular weight Mw and the number average molecular weight Mn in terms of polystyrene as determined by gel permeation chromatography is 2.50≦Mw / Mn≦9.00, and the composition does not contain a compound or polymer having a cardo structure. [ka] (In the general formula (1), R a represents a saturated monovalent organic group having 1 to 30 carbon atoms or an unsaturated monovalent organic group having 2 to 30 carbon atoms, X represents a divalent organic group having 1 to 30 carbon atoms, p represents an integer of 0 to 5, q1 represents an integer of 1 to 6, p+q1 represents an integer of 1 or greater and 6 or less, and q2 represents 0 or 1. [ka] (In the formula, * indicates a bonding position, and W is an organic group having 1 to 4 carbon atoms.)

[0015] Such a metal oxide film-forming composition can be used as a resist underlayer film material for multilayer resist processes. Because it contains a flowability promoter with excellent crack resistance, it is possible to form thick films that exhibit excellent dry etching resistance derived from metal oxide nanoparticles. Furthermore, the synergistic effect of the flowability promoter and dispersion stabilizer provides excellent thermal flowability, making it possible to provide a resist underlayer film material that can fill high-aspect-ratio patterned substrates without voids, something that would be difficult to achieve with metal oxide nanoparticles alone. Furthermore, the inclusion of a dispersion stabilizer with a specific structure allows the nanoparticles to maintain a well-dispersed state even in highly concentrated chemical solutions with a resin content of 9% by mass or more, providing a metal oxide film-forming composition with excellent storage stability.

[0016] The (B) flowability promoter preferably contains a resin having a structural unit represented by the following general formula (2) in addition to a resin having a structural unit represented by the general formula (1), or is a resin having both a structural unit represented by the general formula (1) and a structural unit represented by the following general formula (2). [ka] (In the above general formula (2), R a is a saturated monovalent organic group having 1 to 30 carbon atoms or an unsaturated monovalent organic group having 2 to 30 carbon atoms, R b represents a saturated hydrocarbon group having 1 to 30 carbon atoms or an unsaturated hydrocarbon group having 2 to 10 carbon atoms, X represents a divalent organic group having 1 to 30 carbon atoms, p represents an integer of 0 to 5, q1 represents an integer of 1 to 6, p+q1 represents an integer of 1 or more and 6 or less, and q2 represents 0 or 1.

[0017] If the flow promoter contains a resin having a structural unit represented by the general formula (2) or a resin having both the structural unit represented by the general formula (1) and the structural unit represented by the general formula (2), the flow promoter increases the flowability and is effective for filling high aspect ratio pattern substrates. In addition, since the flow promoter has low affinity with polar solvents, it is effective for reducing the amount of residual solvent in the filling film.

[0018] In the general formula (2), R bis either an alkyl group having 1 to 30 carbon atoms or a structure represented by the following general formula (3), and the content of the general formula (2) preferably satisfies the relationship a+b=1, 0.2≦b≦0.8, where a is the proportion of the general formula (1) and b is the proportion of the general formula (2). [ka] (In the general formula (3), * represents a bonding site to an oxygen atom, and R A represents an optionally substituted divalent organic group having 1 to 10 carbon atoms, R B is a hydrogen atom or an optionally substituted monovalent organic group having 1 to 10 carbon atoms.

[0019] A composition for forming a metal oxide film containing such a flowability promoter (B) exhibits increased flowability and is therefore more effective in filling high aspect ratio patterned substrates. When the contents of the general formulas (1) and (2) are within the above ranges, it becomes possible to adjust various physical properties required for use in forming a metal oxide film, such as filling characteristics, dry etching resistance, and substrate adhesion, within appropriate ranges. Furthermore, by adjusting the contents of the general formulas (1) and (2) according to the surface condition of the metal oxide nanoparticles, it becomes possible to improve the dispersion stability of the metal oxide nanoparticles in the composition.

[0020] It is preferable that the (C) dispersion stabilizer has a weight loss rate of less than 30% from 30°C to 190°C and a weight loss rate of 98% or more from 30°C to 350°C.

[0021] The weight loss rate from 30°C to 190°C is less than 30%, and from 30°C to 350°C is 98% or more. This contributes to improving the fluidity of the composition when it is applied, and it is removed from the film after baking at 350°C, which enables improved filling / planarization properties without deteriorating dry etching resistance. In addition, it can suppress the occurrence of defects caused by drying, contributing to improved yields in semiconductor manufacturing.

[0022] The dispersion stabilizer (C) preferably contains one or more compounds selected from the following general formulae (I) to (III). [ka] (In the formula, R 1 are each independently a hydrogen atom, a hydroxyl group, or an optionally substituted organic group having 1 to 10 carbon atoms. 1 W is a phenylene group or a divalent group represented by the following general formula (I-1): 2 , W 3 is a single bond or a divalent group represented by the following general formula (I-2): 1 is an integer between 1 and 10, and n 1 is an integer between 0 and 5.) [ka] (where * indicates a bonding position, and R 10 , R 11 , R 12 , R 13 is a hydrogen atom, a hydroxyl group, or an organic group having 1 to 10 carbon atoms. 10 , W 11 Each m is independently a single bond or a carbonyl group. 10 , m 11 is an integer between 0 and 10, and m 10 +m 11 ≧1.) [ka] (In the formula, * indicates the bonding position.) [ka] (In the formula, R 2 are each independently a hydrogen atom or an optionally substituted organic group having 1 to 10 carbon atoms. 4 is a divalent group represented by any one of the following general formulas (II-1): 5 is a single bond or a divalent group represented by the following general formula (II-2): 2is an integer between 2 and 10, and n 3 is an integer between 0 and 5.) [ka] (where * indicates a bonding position, and R 20 , R 21 , R 22 , R 23 is a hydrogen atom, a hydroxyl group, or an organic group having 1 to 10 carbon atoms. 20 , m 21 is an integer between 0 and 10, and m 20 +m 21 ≧1.) [ka] (In the formula, * indicates the bonding position.) [ka] (In the formula, R 3 , R 4 R is a hydrogen atom, a hydroxyl group, or an organic group having 1 to 10 carbon atoms which may be substituted, and may be bonded to form a cyclic structure. 5 , R 6 is an organic group having 1 to 10 carbon atoms, and R 5 is a group containing either an aromatic ring or a divalent group represented by the following general formula (III-1): 6 , W 7 is a single bond or a divalent group represented by the following general formula (III-2), and at least one of them is a divalent group represented by the following general formula (III-2). [ka] (where * indicates a bond position, and W 30 is an organic group having 1 to 4 carbon atoms. [ka] (In the formula, * indicates the bonding position.)

[0023] By using a dispersion stabilizer having an aromatic ring as a hydrophobic portion and a structure having an oxygen atom, including a (C-1) structure as a hydrophilic portion, it is possible to prepare a composition for forming a metal oxide film that has excellent dispersibility / stability of metal oxide nanoparticles, even when the concentration of the flow promoter resin in the composition is 9% by mass or more.

[0024] The (A) metal oxide nanoparticles are preferably one or more metal oxide nanoparticles selected from the group consisting of zirconium, hafnium, aluminum, tungsten, titanium, copper, tin, cerium, indium, zinc, yttrium, lanthanum, chromium, cobalt, platinum, iron, antimony, and germanium.

[0025] By using such metal oxide nanoparticles, it is possible to prepare a composition for forming a metal oxide film in which the dispersibility / stability of the metal nanoparticles is excellent.

[0026] The (A) metal oxide nanoparticles are preferably one or more nanoparticles selected from the group consisting of zirconium oxide nanoparticles, hafnium oxide nanoparticles, tungsten oxide nanoparticles, titanium oxide nanoparticles, and tin oxide nanoparticles.

[0027] By using such metal oxide nanoparticles, it is possible to form a metal oxide film with excellent etching resistance.

[0028] The (A) metal oxide nanoparticles preferably have an average primary particle size of 100 nm or less.

[0029] By using such metal oxide nanoparticles, it is possible to prepare a composition for forming a metal oxide film in which the dispersibility and fluidity of the metal nanoparticles are excellent.

[0030] The weight ratio of the (A) metal oxide nanoparticles to the (B) flowability promoter is preferably 80 / 20 to 10 / 90.

[0031] When the ratio of (A) to (B) is within this range, the various properties required for forming a metal oxide film, such as filling characteristics, dry etching resistance, and substrate adhesion, can be adjusted within appropriate ranges. Furthermore, it is possible to provide a composition for forming a metal oxide film without impairing the dispersion stability of metal oxide nanoparticles in the composition.

[0032] The metal oxide film-forming composition preferably further contains one or more of a crosslinking agent, a surfactant, and an acid generator.

[0033] A metal oxide film-forming composition containing the above additives will have better coatability, dry etching resistance, and filling properties.

[0034] The present invention also provides a method for forming a pattern on a substrate to be processed, comprising the steps of: (I-1) a step of applying the composition for forming a metal oxide film onto a substrate to be processed, followed by heat treatment to form a metal oxide film; (I-2) forming a resist top layer film on the metal oxide film using a photoresist material; (I-3) a step of pattern-exposing the resist upper layer film and then developing it with a developer to form a pattern on the resist upper layer film; (I-4) a step of transferring the pattern to the metal oxide film by dry etching using the resist upper layer film on which the pattern has been formed as a mask; and (I-5) A step of processing the substrate to be processed using the metal oxide film on which the pattern has been formed as a mask to form a pattern on the substrate to be processed. The present invention provides a pattern forming method comprising the steps of:

[0035] By using the pattern forming method using the two-layer resist process, a fine pattern can be formed on a workpiece (substrate).

[0036] The present invention also provides a method for forming a pattern on a substrate to be processed, comprising the steps of: (II-1) A step of applying the composition for forming a metal oxide film onto a substrate to be processed, followed by heat treatment to form a metal oxide film; (II-2) forming a silicon-containing resist intermediate film on the metal oxide film using a silicon-containing resist intermediate film material; (II-3) forming a resist upper layer film on the silicon-containing resist intermediate film using a photoresist material; (II-4) a step of pattern-exposing the resist upper layer film and then developing it with a developer to form a pattern on the resist upper layer film; (II-5) a step of transferring the pattern to the silicon-containing resist intermediate film by dry etching using the resist upper layer film on which the pattern has been formed as a mask; (II-6) a step of transferring a pattern to the metal oxide film by dry etching using the silicon-containing resist intermediate film to which the pattern has been transferred as a mask; and (II-7) A step of processing the substrate to be processed using the metal oxide film on which the pattern has been formed as a mask to form a pattern on the substrate to be processed. The present invention provides a pattern forming method comprising the steps of:

[0037] The pattern formation method using the three-layer resist process described above makes it possible to form a fine pattern on a substrate to be processed with high precision.

[0038] The present invention also provides a method for forming a pattern on a substrate to be processed, comprising the steps of: (III-1) A step of applying the composition for forming a metal oxide film to a substrate to be processed, followed by heat treatment to form a metal oxide film; (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 metal oxide film; (III-3) forming an organic thin film on the inorganic hard mask intermediate film; (III-4) forming a resist top layer film on the organic thin film using a photoresist material; (III-5) a step of pattern-exposing the resist upper layer film and then developing it with a developer to form a pattern on the resist upper layer film; (III-6) a step of transferring the pattern to the organic thin film and the inorganic hard mask intermediate film by dry etching using the resist upper layer film on which the pattern has been formed as a mask; (III-7) transferring the pattern to the metal oxide film by dry etching using the inorganic hard mask intermediate film to which the pattern has been transferred as a mask; and (III-8) A step of processing the substrate to be processed using the metal oxide film on which the pattern has been formed as a mask to form a pattern on the substrate to be processed. The present invention provides a pattern forming method comprising the steps of:

[0039] The pattern formation method using the four-layer resist process described above makes it possible to form fine patterns on the substrate to be processed with high precision.

[0040] The present invention also provides a method for forming a pattern on a substrate to be processed, comprising the steps of: (IV-1) forming a resist underlayer film on a substrate to be processed; (IV-2) forming a resist intermediate film or a combination of an inorganic hard mask intermediate film selected from a silicon oxide film, a silicon nitride film, and a silicon oxynitride film and an organic thin film on the resist underlayer film; (IV-3) forming a resist upper layer film using a photoresist material on the resist intermediate film or the combination of the inorganic hard mask intermediate film and the organic thin film; (IV-4) a step of pattern-exposing the resist upper layer film and then developing it with a developer to form a pattern on the resist upper layer film; (IV-5) a step of transferring a pattern to the resist intermediate film, or the organic thin film and the inorganic hard mask intermediate film, by dry etching using the resist upper layer film on which the pattern has been formed as a mask; (IV-6) a step of transferring a pattern to the resist underlayer film by dry etching using the resist interlayer film or inorganic hard mask interlayer film to which the pattern has been transferred as a mask; (IV-7) a step of applying the composition for forming a metal oxide film onto the resist underlayer film on which the pattern has been formed, followed by heat treatment to cover the resist underlayer film with a metal oxide film, and filling spaces between the resist underlayer film patterns with the metal oxide film; (IV-8) etching back the metal oxide film covering the resist underlayer film on which the pattern has been formed by chemical stripping or dry etching to expose the upper surface of the resist underlayer film on which the pattern has been formed; (IV-9) a step of removing the resist intermediate film or inorganic hard mask intermediate film remaining on the upper surface of the resist underlayer film by dry etching; (IV-10) a step of removing the resist underlayer film on which the pattern is formed and the surface is exposed by dry etching, thereby forming a reverse pattern of the original pattern on the metal oxide film; (IV-11) A step of processing the substrate to be processed using the metal oxide film on which the reversal pattern is formed as a mask to form a tone-reversal pattern on the substrate to be processed. The present invention provides a pattern forming method comprising the steps of:

[0041] The pattern forming method using the above-described reversal process makes it possible to form fine patterns on a substrate to be processed with even greater precision.

[0042] A pattern forming method using a metal oxide film-forming composition as a sacrificial film, comprising: (V-1) a step of applying the composition for forming a metal oxide film onto a substrate to be processed having a structure or a step, and then performing a heat treatment to fill the substrate with a metal oxide film; (V-2) a step of removing the metal oxide film outside the structure or step on the substrate to be processed by a CMP method, thereby removing the metal oxide film from the surface of the substrate to be processed; (V-3) a step of alternately laminating insulating films and conductive films on the substrate to be processed filled with the metal oxide film; (V-4) forming an organic resist underlayer film on the laminated film of the insulating film and the conductive film formed on the substrate to be processed filled with the metal oxide film; (V-5) forming a resist intermediate film, or an inorganic hard mask intermediate film selected from a silicon oxide film, a silicon nitride film, and a silicon oxynitride film, or a combination of the inorganic hard mask intermediate film and an organic thin film on the organic resist underlayer film; (V-6) forming a resist upper layer film using a photoresist material on the resist intermediate film, or the inorganic hard mask intermediate film, or the combination of the inorganic hard mask intermediate film and the organic thin film; (V-7) a step of pattern-exposing the resist upper layer film and then developing it with a developer to form a pattern on the resist upper layer film; (V-8) a step of transferring a pattern to the resist intermediate film, or the inorganic hard mask intermediate film, or the organic thin film and the inorganic hard mask intermediate film by dry etching using the resist upper layer film on which the pattern has been formed as a mask; (V-9) a step of transferring a pattern to the resist underlayer film by dry etching using the resist interlayer film or inorganic hard mask interlayer film to which the pattern has been transferred as a mask; (V-10) a step of transferring a pattern to the laminated film of the insulating film and the conductive film by dry etching using the resist underlayer film to which the pattern has been transferred as a mask; (V-11) A step of removing the metal oxide film filled on the substrate to be processed using the laminated film of the insulating film and the conductive film to which the pattern has been transferred as a mask. The present invention provides a pattern forming method comprising the steps of:

[0043] The above pattern formation method makes it possible to form a multi-stack structure in 3D-NAND manufacturing, contributing to even higher stacking.

[0044] The insulating film may be formed from any suitable insulating material(s). By way of example, and without limitation, the insulating material may include silicon oxide (e.g., SiO2). The conductive film may be formed from any suitable conductive material(s). The conductive film may include one or more of polysilicon and metals such as tungsten, nickel, titanium, platinum, aluminum, gold, tungsten nitride, tantalum nitride, titanium nitride, and silicon nitride. The methods for forming each of the conductive and insulating materials are not described in detail herein, but may be formed by conventional techniques.

[0045] As the substrate to be processed, it is preferable to use a substrate having a structure or steps with an aspect ratio of 5 or more.

[0046] In the present invention, the above-mentioned substrates can be used as the substrate to be processed.

[0047] The present invention also provides a method for forming a metal oxide film that functions as a flat film used in the manufacturing process of a semiconductor device, which comprises applying the above-mentioned metal oxide film-forming composition to a substrate to be processed and then heat-treating the substrate at a temperature of 100°C or higher and 600°C or lower for 10 to 600 seconds to form a hardened film.

[0048] The present invention also provides a method for forming a metal oxide film that functions as a flat film used in the manufacturing process of a semiconductor device, which comprises applying the above-mentioned metal oxide film-forming composition to a substrate to be processed and then heat-treating the substrate in an atmosphere with an oxygen concentration of 1% by volume or more and 21% by volume or less to form a hardened film.

[0049] By using such a method, the crosslinking reaction of the composition for forming a metal oxide film can be promoted during the formation of a resist underlayer film, and mixing with the upper layer film can be more effectively suppressed. In addition, by appropriately adjusting the heat treatment temperature, time, and oxygen concentration within the above ranges, it is possible to obtain the metal oxide film filling / planarization properties and curing properties suitable for the intended use.

[0050] The present invention also provides a method for forming a metal oxide film that functions as a flat film used in the manufacturing process of a semiconductor device, which comprises applying the above-mentioned metal oxide film-forming composition to a substrate to be processed and then heat-treating the substrate in an atmosphere with an oxygen concentration of less than 1% by volume to form a hardened film.

[0051] This method is useful because it promotes the crosslinking reaction of the composition for forming a metal oxide film during the formation of the metal oxide film without causing deterioration of the substrate to be processed, even when the substrate to be processed contains a material that is unstable when heated in an oxygen atmosphere, and it can more effectively suppress mixing with the overlying film. [Effects of the Invention]

[0052] As described above, the metal oxide film-forming composition, pattern formation method, and metal oxide film-forming method of the present invention are particularly suitable for use in multilayer resist processes, including filling / planarizing uneven or uneven substrates, and are extremely useful in fine patterning for semiconductor device manufacturing. Specifically, the inclusion of a flowability promoter with excellent crack resistance enables the formation of thick films exhibiting excellent dry etching resistance derived from metal oxide nanoparticles. Furthermore, the inclusion of a dispersion stabilizer capable of further improving the thermal fluidity of the flowability promoter resin allows for the provision of a metal oxide film-forming composition that can be used as a resist underlayer film material, enabling void-free filling of high-aspect-ratio patterned substrates, which is difficult to achieve with metal oxide nanoparticles alone. Furthermore, the inclusion of a dispersion stabilizer with a specific structure allows for the nanoparticles to maintain a well-dispersed state even in highly concentrated chemical solutions containing 9% or more resin by weight, providing a metal oxide film-forming composition with excellent storage stability. In the fine patterning process using the multilayer resist method in semiconductor device manufacturing, this technology can fill without causing defects such as voids or peeling, even on substrates with areas that are difficult to fill / planarize, such as high aspect ratio pattern substrates typified by 3D-NAND memory, which are becoming increasingly highly stacked.In addition, it can form thick films with extremely superior dry etching resistance compared to conventional coating-type organic resist underlayer film materials, allowing for the formation of fine patterns on workpieces with even greater precision. [Brief explanation of the drawings]

[0053] [Figure 1] FIG. 1 is an explanatory diagram of an example of the pattern forming method of the present invention (three-layer resist process). [Figure 2] FIG. 2 is an explanatory diagram of an example of the tone reversal pattern forming method of the present invention (reversal of the SOC pattern in a three-layer resist process). [Figure 3] FIG. 3 is an explanatory diagram of an example of a pattern formation method using a sacrificial film of the present invention. [Figure 4] FIG. 4 is an explanatory diagram of the embedding characteristic evaluation method. DETAILED DESCRIPTION OF THE INVENTION

[0054] As described above, in the fine patterning process using the multilayer resist method in the semiconductor device manufacturing process, there has been a need for a thick-film resist underlayer material that can fill and planarize without causing defects such as voids or peeling, even on substrates that have areas that are difficult to fill and planarize, such as dense areas of high-aspect ratio fine pattern structures typified by 3D-NAND memory, which are becoming increasingly highly stacked.The thick-film resist underlayer material also has superior dry etching resistance compared to conventional coating-type organic resist underlayer materials, and can transfer resist patterns to substrates with higher accuracy.

[0055] The present inventors have conducted extensive research into the above-mentioned problems and have searched for various resist underlayer film materials and pattern formation methods to enable a multilayer resist method using a resist underlayer film to simultaneously achieve high-level filling / planarization by forming an underlayer film and excellent dry etching resistance. As a result, they have found that a pattern formation method using a metal oxide film-forming composition comprising metal oxide nanoparticles with excellent dry etching resistance, a flowability promoter containing a resin with a specific structure that has excellent crack resistance, and a dispersion stabilizer that is effective in improving the flowability and storage stability of the resin is very effective, leading to the completion of the present invention.

[0056] That is, the present invention is A metal oxide film-forming composition, (A) metal oxide nanoparticles; (B) a flowability promoter containing a resin having a structural unit represented by the following general formula (1): (C) a dispersion stabilizer consisting of an aromatic-containing compound containing two or more benzene rings, or one benzene ring and a structure represented by the following general formula (C-1), and having a molecular weight represented by a molecular formula of 500 or less; and (D) contains an organic solvent, The metal oxide film-forming composition is characterized in that the content of the flow promoter (B) in the entire composition is 9 mass % or more, the ratio Mw / Mn of the weight average molecular weight Mw to the number average molecular weight Mn in terms of polystyrene as determined by gel permeation chromatography is 2.50≦Mw / Mn≦9.00, and the composition does not contain any compound or polymer having a cardo structure. [ka] (In the general formula (1), R a represents a saturated monovalent organic group having 1 to 30 carbon atoms or an unsaturated monovalent organic group having 2 to 30 carbon atoms, X represents a divalent organic group having 1 to 30 carbon atoms, p represents an integer of 0 to 5, q1 represents an integer of 1 to 6, p+q1 represents an integer of 1 or greater and 6 or less, and q2 represents 0 or 1. [ka] (In the formula, * indicates a bonding position, and W is an organic group having 1 to 4 carbon atoms.)

[0057] The present invention will be described in detail below, but the present invention is not limited thereto.

[0058] <Composition for forming metal oxide film> The metal oxide film-forming composition of the present invention contains (A) metal oxide nanoparticles, (B) a flowability promoter represented by a specific general formula, (C) a dispersion stabilizer consisting of an aromatic-containing compound containing two or more benzene rings or one benzene ring and a structure represented by the following general formula (C-1), and having a molecular weight of 500 or less, and (D) an organic solvent, wherein the content of the flowability promoter in the composition is 9% by mass or more, the ratio Mw / Mn of the weight-average molecular weight Mw to the number-average molecular weight Mn as measured by gel permeation chromatography (GPC) is 2.50≦Mw / Mn≦9.00, and the composition is free of compounds with cardo structures or polymers, and may optionally contain additives such as surfactants and crosslinkers. The components contained in the composition of the present invention are described below.

[0059] <(A) Metal oxide nanoparticles> The (A) metal oxide nanoparticles contained in the metal oxide film-forming composition of the present invention are preferably one or more metal oxide nanoparticles selected from the group consisting of zirconium, hafnium, aluminum, tungsten, titanium, copper, tin, cerium, indium, zinc, yttrium, lanthanum, chromium, cobalt, platinum, iron, antimony, and germanium. Among these, zirconium oxide nanoparticles, hafnium oxide nanoparticles, tungsten oxide nanoparticles, titanium oxide nanoparticles, and tin oxide nanoparticles are preferred from the viewpoints of dispersibility and dry etching resistance.

[0060] By selecting the above metal oxides, it is possible to form a metal oxide film having excellent dispersibility and dry etching resistance.

[0061] The (A) metal oxide nanoparticles preferably have an average primary particle diameter of 100 nm or less, more preferably 50 nm or less, even more preferably 30 nm or less, and particularly preferably 15 nm or less. The average primary particle diameter of the metal oxide nanoparticles before dispersion in an organic solvent can be determined by directly measuring the size of the primary particles from an electron microscope photograph. Specifically, the minor axis diameter and major axis diameter of each primary particle are measured, and the average is taken as the particle diameter of that particle. Next, the volume (mass) of each of 100 or more particles is calculated by approximating it to a rectangular parallelepiped of the calculated particle diameter, and the volume-average particle diameter is calculated and taken as the average particle diameter. Note that the same results can be obtained using any of a transmission electron microscope (TEM), a scanning electron microscope (SEM), and a scanning transmission electron microscope (STEM).

[0062] Within this particle size range, the particles can exhibit good dispersibility in the composition for forming a metal oxide film, and a metal oxide film can be formed that has excellent filling / planarizing properties in dense areas of a fine pattern structure.

[0063] As the (A) metal oxide nanoparticles contained in the composition for forming a metal oxide film of the present invention, commercially available metal oxide nanoparticles can be used.

[0064] Examples of titania nanoparticles include the TTO series (TTO-51(A), TTO-51(C), etc.), TTO-S, V series (TTO-S-1, TTO-S-2, TTO-V-3, etc.) manufactured by Ishihara Sangyo Kaisha, Ltd., the MT series (MT-01, MT-05, MT-100SA, MT-500SA, NS405, etc.) manufactured by Teika Corporation, and STR-100A-LP manufactured by Sakai Chemical Industry Co., Ltd.

[0065] Examples of zirconia nanoparticles include PCS (manufactured by Nippon Denko Corporation), JS-01, JS-03, JS-04 (manufactured by Nippon Denko Corporation), UEP, UEP-50, UEP-100 (manufactured by Daiichi Kigenso Kagaku Kogyo Co., Ltd.), PCPB-2-50-PGA and PCPA-2-502-PGA (manufactured by Pixelligent Technologies), ZrO2 nanoparticles 915505 (manufactured by Sigma-Aldrich), SZR-M, SZR-K, SZR-En10 (manufactured by Sakai Chemical Industry Co., Ltd.), and zirconia nanoparticle dispersions Zircostar ZP-153 and HR-101 (manufactured by Nippon Shokubai Co., Ltd.).

[0066] The metal oxide nanoparticles (A) contained in the metal oxide film-forming composition of the present invention may be used singly or in combination of two or more types, and any combination can be selected according to the required performance. The amount of component (A) can be 11 to 400 parts by mass per 100 parts by mass of the flowability promoter in the composition.

[0067] <(B) Flow promoter> The composition for forming a metal oxide film of the present invention is characterized by containing 9 mass % or more of a flow promoter (B) containing a resin having a structural unit represented by the following general formula (1) based on the total mass of the composition, and not containing a compound or polymer having a cardo structure. [ka] (In the general formula (1), R a represents a saturated monovalent organic group having 1 to 30 carbon atoms or an unsaturated monovalent organic group having 2 to 30 carbon atoms, X represents a divalent organic group having 1 to 30 carbon atoms, p represents an integer of 0 to 5, q1 represents an integer of 1 to 6, p+q1 represents an integer of 1 or greater and 6 or less, and q2 represents 0 or 1.

[0068] When the content of the (B) flow promoter is 9% by mass or more, a thick metal oxide film can be formed. This suggests that even on a substrate to be processed that has a large aspect ratio and portions that are particularly difficult to fill, a resist underlayer film can be formed with excellent filling characteristics without defects such as voids or peeling. Considering the increasing aspect ratio of patterns that require filling due to the further increase in stacking density of 3D-NAND, the content of the (B) flow promoter is more preferably 15% by mass or more, and even more preferably 20% by mass or more.

[0069] Since the flow promoter (B) does not contain compounds or polymers with a cardo structure, a thick metal oxide film with excellent crack resistance can be formed. The fluorene ring with a cardo structure has a rigid structure and large steric hindrance, so a film with excellent heat resistance can be formed. However, high-carbon materials are prone to cracking due to thermal shrinkage during baking, making them unsuitable for forming thick films.

[0070] It is preferable that the flow promoter (B) does not contain a resin with a high carbon content, not limited to a cardo structure. A coating film is formed on a substrate using a composition in which only the flow promoter is dissolved in a solvent component without using a nanoparticle component, and the resulting film is baked at 350°C for about 60 seconds and then measured. The carbon content of the flow promoter (B) is preferably 90% by mass or less, more preferably 85% by mass or less, as measured by elemental analysis.

[0071] In the above general formula (1), R aExamples of the saturated monovalent organic group having 1 to 30 carbon atoms and the unsaturated monovalent organic group having 2 to 30 carbon atoms represented by the formula (I) include monovalent saturated hydrocarbon groups such as methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl group, tert-butyl group, n-pentyl group, iso-pentyl group, sec-pentyl group, and tert-pentyl group; monovalent unsaturated chain groups such as ethenyl group, propenyl group, butenyl group, pentenyl group, ethynyl group, and propynyl group; Examples of the hydrocarbon group include monocyclic saturated cyclic hydrocarbon groups such as a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group; monovalent monocyclic unsaturated cyclic hydrocarbon groups such as a cyclobutenyl group, a cyclopentenyl group, and a cyclohexenyl group; monovalent polycyclic cyclic hydrocarbon groups such as a norbornyl group and an adamantyl group; and monovalent aromatic hydrocarbon groups such as a phenyl group, a methylphenyl group, a naphthyl group, a methylnaphthyl group, an anthryl group, and a methylanthryl group.

[0072] Above R a Examples of the organic group represented by the formula (I) include alkoxy groups such as a methoxy group, an ethoxy group, an n-propoxy group, an i-propoxy group, an n-butoxy group, an i-butoxy group, a sec-butoxy group, a t-butoxy group, an n-pentyloxy group, and an n-hexyloxy group; and alkoxycarbonyl groups such as a methoxycarbonyl group, an ethoxycarbonyl group, an n-propoxycarbonyl group, an i-propoxycarbonyl group, an n-butoxycarbonyl group, an i-butoxycarbonyl group, a sec-butoxycarbonyl group, a t-butoxycarbonyl group, an n-pentyloxycarbonyl group, and an n-hexyloxycarbonyl group.

[0073] Some or all of the hydrogen atoms of the saturated hydrocarbon group, unsaturated chain hydrocarbon group, monocyclic saturated cyclic hydrocarbon group, monocyclic unsaturated cyclic hydrocarbon group, polycyclic cyclic hydrocarbon group, aromatic hydrocarbon group, alkoxy group, alkoxycarbonyl group, etc. may be substituted, and examples of the substituent include halogen atoms such as a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom; a hydroxyl group, a cyano group, a carboxy group, a nitro group, an amino group, an alkoxy group, an alkoxycarbonyl group, an acyl group, an alkoxycarbonyloxy group, an aryl group, and an aliphatic heterocyclic group such as a lactone group; and aromatic heterocyclic groups such as a furyl group and a pyridyl group.

[0074] Above R a From the viewpoint of raw material availability, a methyl group is preferred as the organic group represented by the formula:

[0075] In the above general formula (1), examples of the divalent organic group having 1 to 30 carbon atoms represented by X include alkanediyl groups such as methylene, ethanediyl, propanediyl, butanediyl, pentanediyl, hexanediyl, octanediyl, and decanediyl groups; monocyclic cycloalkanediyl groups such as cyclopropanediyl, cyclobutanediyl, cyclopentanediyl, cyclohexanediyl, cycloheptanediyl, cyclooctanediyl, cyclodecanediyl, methylcyclohexanediyl, and ethylcyclohexanediyl groups; bicyclo[2.2.1]heptanediyl, bicyclo[2.2.2]octanediyl, and tricyclo[5.2.1.0]octanediyl groups; 2,6 ]decanediyl group (dicyclopentylene group), tricyclo[3.3.1.1 3,7 ]decanediyl group, tetracyclo[6.2.1.1 3,6 .0 2,7 ] Polycyclic cycloalkanediyl groups such as dodecanediyl group and adamantanediyl group, and arenediyl groups such as phenylene group and naphthylene group.

[0076] Examples of the alkanediyloxy group represented by X include groups formed by combining the above alkanediyl group with an oxygen atom, and examples of the cycloalkanediyloxy group represented by X include groups formed by combining the above cycloalkanediyl group with an oxygen atom.

[0077] Some or all of the hydrogen atoms of the above alkanediyl group, cycloalkanediyl group, alkanediyloxy group, cycloalkanediyloxy group, arenediyl group, etc. may be substituted, and examples of the substituent include the above R a Examples of the substituent that the organic group represented by the following formula may have include the same groups as those mentioned above.

[0078] Examples of the organic group represented by X include groups represented by the following formulas. [ka] (In the above formula, * represents a bond.)

[0079] From the viewpoint of raw material availability, a methylene group is preferable as the above X.

[0080] (B) Specific examples of resins having a structural unit represented by the above general formula (1) include the following. [ka]

[0081] [ka]

[0082] The ratio Mw / Mn of the weight average molecular weight Mw to the number average molecular weight Mn of the (B) fluidity promoter, as calculated using polystyrene standards by gel permeation chromatography, is 2.50≦Mw / Mn≦9.00, preferably 3.00≦Mw / Mn≦8.00.

[0083] Such a degree of dispersion further improves the thermal fluidity of the resin contained in the flowability promoter, and therefore when incorporated into a composition, it is possible to not only satisfactorily embed the fine structure formed on the substrate, but also to form a resist underlayer film that flattens the entire substrate.

[0084] The weight average molecular weight Mw of the (B) flow promoter, as calculated on a polystyrene basis by gel permeation chromatography, is preferably 1,500≦Mw≦20,000, more preferably 3,000≦Mw≦15,000, and particularly preferably 4,000≦Mw≦12,000.

[0085] Within this molecular weight range, the resin contained in the flowability promoter has better thermal fluidity, and therefore, when incorporated into a composition, it is possible to form a resist underlayer film that not only satisfactorily embeds fine structures formed on a substrate but also flattens the entire substrate.Furthermore, it is possible to form a metal oxide film that has excellent film thickness uniformity and a small amount of sublimation product.

[0086] The (B) fluidity promoter may contain a resin having a structural unit represented by the following general formula (2) in addition to the resin having the structural unit represented by the general formula (1). [ka] (In the above general formula (2), R a is a saturated monovalent organic group having 1 to 30 carbon atoms or an unsaturated monovalent organic group having 2 to 30 carbon atoms, R b represents a saturated hydrocarbon group having 1 to 30 carbon atoms or an unsaturated hydrocarbon group having 2 to 10 carbon atoms, X represents a divalent organic group having 1 to 30 carbon atoms, p represents an integer of 0 to 5, q1 represents an integer of 1 to 6, p+q1 represents an integer of 1 or more and 6 or less, and q2 represents 0 or 1.

[0087] In the above general formula (2), R b Examples of the saturated monovalent organic group having 1 to 30 carbon atoms or the unsaturated monovalent organic group having 2 to 10 carbon atoms include R a Similar examples include:

[0088] If the flow promoter contains a resin having the structural unit represented by the general formula (2), the flowability is increased, which is effective for filling high aspect ratio patterned substrates. In addition, since the flow promoter has low affinity with polar solvents, it is effective for reducing the amount of residual solvent in the filling film.

[0089] Furthermore, a preferred embodiment of the general formula (2) is R b is an alkyl group having 1 to 30 carbon atoms, or a resin having a structural unit represented by any of the structures represented by the following general formula (3). [ka] (In the general formula (3), * represents a bonding site to an oxygen atom, and R A represents an optionally substituted divalent organic group having 1 to 10 carbon atoms, R B is a hydrogen atom or an optionally substituted monovalent organic group having 1 to 10 carbon atoms.

[0090] In the above general formula (3), R A Examples of the divalent organic group having 1 to 10 carbon atoms represented by the formula (I) include alkanediyl groups such as a methylene group, an ethanediyl group, a propanediyl group, a butanediyl group, a pentanediyl group, a hexanediyl group, an octanediyl group, and a decanediyl group, and arenediyl groups such as a benzenediyl group, a methylbenzenediyl group, and a naphthalenediyl group.

[0091] In the above general formula (3), R B Examples of the monovalent organic group having 1 to 10 carbon atoms represented by the formula (I) include alkyl groups such as a 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, and n-decyl group, and aryl groups such as a phenyl group, tolyl group, xylyl group, mesityl group, and naphthyl group.

[0092] Some or all of the hydrogen atoms of the alkanediyl group, arenediyl group, alkyl group, aryl group, etc. may be substituted, and examples of the substituent include the above-mentioned R a Examples of the substituent that the organic group represented by the following formula may have include the same groups as those mentioned above.

[0093] Particularly preferred examples include the structure shown below. When the composition has such a structure, it is possible to provide a metal oxide film-forming composition capable of forming a filling film with excellent filling properties for high aspect ratio patterns. Furthermore, the composition exhibits good heat resistance and film-forming properties, suppresses the generation of sublimates during heat curing, prevents contamination of the device by the sublimates, and prevents the occurrence of coating defects. [ka] (In the above formula, * represents the bonding site to the oxygen atom.)

[0094] By having such a crosslinking group, it is possible to further improve the flowability and form a cured film with excellent film-forming properties and little outgassing.

[0095] Specific examples of polymers having a structural unit represented by the above general formula (2) include the following. [ka]

[0096] The content of the polymer having the structural unit of the general formula (2) preferably satisfies the relationship a+b=1, 0.2≦b≦0.8, where a is the proportion of the resin having the structural unit of the general formula (1) and b is the proportion of the resin having the structural unit of the general formula (2), and more preferably satisfies the relationship 0.3≦b≦0.7.

[0097] By controlling the ratio of the resin of the above general formula (2) within such a 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 it is desired to improve the film-forming property and the adhesion of the film to the substrate, the ratio a of the resin having a hydroxyl group may be increased, that is, a > b. When it is desired to improve the curability, heat resistance, and planarization characteristics, a < b may be set, and these can be adjusted to any ratio according to the required performance. Further, by adjusting the contents of the above general formula (1) and the above general formula (2) according to the surface state of the metal oxide nanoparticles, it is possible to improve the dispersion stability of the metal oxide nanoparticles in the composition.

[0098] Furthermore, as described above, not only by mixing two kinds of resins at a desired ratio, but also by controlling the ratio of substituents in one kind of resin, it is possible to obtain an equivalent composition. Specifically, it is a resin having both a structural unit represented by the above general formula (1) and a structural unit represented by the following general formula (2). In this case, preferably, the resin shown in the following general formula (4) is used, and by controlling the ratio of the structure constituting R c it can be prepared. Specifically, when the ratio of the hydrogen atoms of the structure constituting R c is a, and the ratio of an alkyl group having 1 to 30 carbon atoms or the structure represented by the above general formula (3) is b, the relationship a + b = 1 is satisfied, and in this case, it is preferable that the ratio satisfies the relationship 0.2 ≦ b ≦ 0.8, and the relationship 0.3 ≦ b ≦ 0.7 can be exemplified as a more preferable ratio.

Chemical formula

[0099] In the composition for forming a metal oxide film of the present invention, the weight ratio of the (A) metal oxide nanoparticles to the (B) flowability promoter is preferably 80 / 20 to 10 / 90, more preferably 70 / 30 to 20 / 80, and even more preferably 70 / 30 to 30 / 70.

[0100] By controlling the ratio of (A) metal oxide nanoparticles to (B) flow promoter within the above range, it is possible to achieve high levels of dry etching resistance and fillability / planarization properties. A ratio within the range of 80 / 20 to 10 / 90 does not result in a decrease in heat resistance or dry etching resistance, and it is easy to achieve thicker films. To improve dry etching resistance, simply increase the ratio of (A) metal oxide nanoparticles. To improve fillability / planarization properties, simply increase the ratio of (B) flow promoter. These ratios can be adjusted to any desired performance. The amount of component (B) can be 25 to 900 parts by mass per 100 parts by mass of metal oxide nanoparticles in the composition.

[0101] <(C) Dispersion stabilizer> The dispersion stabilizer (C) used in the present invention is an aromatic-containing compound that has a molecular weight represented by a molecular formula of 500 or less and preferably contains an oxygen atom and an aromatic ring.

[0102] When the dispersion stabilizer (C) is within the above molecular weight range, it exhibits sufficient thermal fluidity during baking, thereby exhibiting high-level embedding properties and reducing the amount of residue in the metal oxide film after baking. The molecular weight of the dispersion stabilizer, as determined by the molecular formula, is preferably 180 to 500, more preferably 200 to 450, and particularly preferably 240 to 400.

[0103] When the dispersion stabilizer has a molecular weight of 180 or more, the dispersion stabilizer is not easily reduced by evaporation or the like during heat treatment, resulting in excellent thermal fluidity and sufficient filling / planarization properties. When the molecular weight exceeds 500, evaporation of the dispersion stabilizer during heat treatment is suppressed, resulting in a crosslinking reaction between the metal oxide nanoparticles and the fluidity promoter in the metal oxide film-forming composition and evaporation of the dispersion stabilizer simultaneously occurring, resulting in a deterioration in film formability and in-plane uniformity. Furthermore, there is a concern that residual dispersion stabilizer in the film may also deteriorate etching resistance.

[0104] The aromatic ring is essentially a benzene ring, and other examples include aromatic carbon rings such as a naphthalene ring, and aromatic heterocycles such as a furan ring, a pyrrole ring, a thiophene ring, a phosphole ring, a pyrazole ring, an oxazole ring, an isoxazole ring, a thiazole ring, a pyridine ring, a pyrazine ring, a pyrimidine ring, a pyridazine ring, and a triazine ring.

[0105] The metal oxide film-forming composition of the present invention uses a thermal fluidity promoter having an aromatic skeleton. If the dispersion stabilizer is an aromatic-containing compound, it is preferred because it has excellent compatibility with the resin for the thermal fluidity promoter and therefore is less likely to cause film formation defects such as pinholes during film formation. Furthermore, among aromatic rings, aromatic carbon rings are preferred, and benzene rings are more preferred.

[0106] The dispersion stabilizer (C) may be a compound containing two or more benzene rings, or one benzene ring and a structure represented by the following general formula (C-1). [ka] (In the formula, * indicates a bonding position, and W is an organic group having 1 to 4 carbon atoms.)

[0107] More specific examples of W include a methylene group, an ethylene group, a propylene group, a butylene group, a trimethylene group, and a tetramethylene group. Of these, an ethylene group is more preferred.

[0108] The dispersion stabilizer (C) preferably has a weight loss rate of less than 30% between 30°C and 190°C, and a weight loss rate of 98% or more between 30°C and 350°C.

[0109] A dispersion stabilizer that exhibits a weight loss rate of less than 30% between 30°C and 190°C and a weight loss rate of 98% or more between 30°C and 350°C is preferred because evaporation during heat treatment is suppressed, thereby maintaining a low viscosity, providing excellent thermal fluidity, and leaving little dispersion stabilizer remaining in the metal oxide film after firing. In this specification, the weight loss rate is based on a value determined by TG (thermogravimetry) measurement using a differential thermobalance.

[0110] The upper limit of the temperature range in which the weight loss rate of the dispersion stabilizer is less than 30% is more preferably 210° C., and even more preferably 230° C. By setting the temperature range in which the weight loss rate of the dispersion stabilizer is less than 30% within the above temperature range, the filling / planarization properties can be further improved.

[0111] The temperature at which the weight loss rate of the dispersion stabilizer is 98% or more is more preferably 330° C., and particularly preferably 310° C. By setting the temperature at which the weight loss rate of the dispersion stabilizer is 98% or more within the above temperature range, it is possible to further reduce the amount of dispersion stabilizer remaining in the metal oxide film after firing.

[0112] By incorporating the dispersion stabilizer as described above, the thermal fluidity of the metal oxide film-forming composition is improved from the start of heat treatment to curing by the crosslinking reaction, resulting in excellent filling / planarization properties. On the other hand, the dispersion stabilizer is reduced by evaporation or the like during heat treatment, so etching resistance and optical properties are not impaired.

[0113] Further, a more preferred embodiment of the dispersion stabilizer includes one or more compounds selected from the following general formulae (I) to (III). [ka] (In the formula, R 1are each independently a hydrogen atom, a hydroxyl group, or an optionally substituted organic group having 1 to 10 carbon atoms. 1 W is a phenylene group or a divalent group represented by the following general formula (I-1): 2 , W 3 is a single bond or a divalent group represented by the following general formula (I-2): 1 is an integer between 1 and 10, and n 1 is an integer between 0 and 5.) [ka] (where * indicates a bonding position, and R 10 , R 11 , R 12 , R 13 is a hydrogen atom, a hydroxyl group, or an organic group having 1 to 10 carbon atoms. 10 , W 11 Each m is independently a single bond or a carbonyl group. 10 , m 11 is an integer between 0 and 10, and m 10 +m 11 ≧1.) [ka] (In the formula, * indicates the bonding position.)

[0114] [ka] (In the formula, R 2 are each independently a hydrogen atom or an optionally substituted organic group having 1 to 10 carbon atoms. 4 is a divalent group represented by any one of the following general formulas (II-1): 5 is a single bond or a divalent group represented by the following general formula (II-2): 2 is an integer between 2 and 10, and n 3 is an integer between 0 and 5.) [ka] (where * indicates a bonding position, and R 20 , R21 , R 22 , R 23 is a hydrogen atom, a hydroxyl group, or an organic group having 1 to 10 carbon atoms. 20 , m 21 is an integer between 0 and 10, and m 20 +m 21 ≧1.) [ka] (In the formula, * indicates the bonding position.)

[0115] [ka] (In the formula, R 3 , R 4 R is a hydrogen atom, a hydroxyl group, or an organic group having 1 to 10 carbon atoms which may be substituted, and may be bonded to form a cyclic structure. 5 , R 6 is an organic group having 1 to 10 carbon atoms, and R 5 is a group containing either an aromatic ring or a divalent group represented by the following general formula (III-1): 6 , W 7 is a single bond or a divalent group represented by the following general formula (III-2), and at least one of them is a divalent group represented by the following general formula (III-2). [ka] (where * indicates a bond position, and W 30 is an organic group having 1 to 4 carbon atoms. [ka] (In the formula, * indicates the bonding position.)

[0116] In the above general formula (I), R 1 are each independently a hydrogen atom, a hydroxyl group, or an optionally substituted organic group having 1 to 10 carbon atoms.

[0117] Here, in the present invention, the term "organic group" means a group containing at least one carbon atom, and may further contain hydrogen, nitrogen, oxygen, sulfur, silicon, halogen atoms, and the like.

[0118] R 1 R may be a single type or a mixture of multiple types. 1 More specifically, examples of the alkyl group include a hydrogen atom, a hydroxyl group, a methyl group, an ethyl group, a vinyl group, a 2,2,2-trifluoroethyl group, a propyl group, an isopropyl group, an allyl group, a butyl group, a s-butyl group, a t-butyl group, an isobutyl group, a pentyl group, a cyclopentyl group, a hexyl group, a cyclohexyl group, a cyclohexenyl group, a decyl group, a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, a s-butoxy group, a t-butoxy group, a norbornyl group, an adamantyl group, a phenyl group, a tolyl group, a xylyl group, a naphthyl group, a benzyl group, a 2-furanyl group, and a 2-tetrahydrofuranyl group. Among these, a hydrogen atom is more preferred.

[0119] W 1 is a phenylene group or a divalent group represented by the above general formula (I-1). 2 , W 3 is a single bond or a divalent group represented by the above general formula (I-2). 1 is an integer between 1 and 10, and n 1 are each independently an integer of 0 to 5.

[0120] R 10 , R 11 , R 12 , R 13is a hydrogen atom, a hydroxyl group, or an organic group having 1 to 10 carbon atoms. More specific examples include a hydrogen atom, a hydroxyl group, a methyl group, an ethyl group, a vinyl group, a 2,2,2-trifluoroethyl group, a propyl group, an isopropyl group, an allyl group, a butyl group, a s-butyl group, a t-butyl group, an isobutyl group, a pentyl group, a cyclopentyl group, a hexyl group, a cyclohexyl group, a cyclohexenyl group, a decyl group, a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, a s-butoxy group, a t-butoxy group, a norbornyl group, an adamantyl group, a phenyl group, a tolyl group, a xylyl group, a naphthyl group, a benzyl group, a 2-furanyl group, and a 2-tetrahydrofuranyl group. Among these, a hydrogen atom and a methyl group are more preferred, and a hydrogen atom is even more preferred.

[0121] W 10 , W 11 Each m is independently a single bond or a carbonyl group. 10 , m 11 is an integer between 0 and 10, and m 10 +m 11 ≧1.

[0122] R 2 R may be a single type or a mixture of multiple types. 2 More specifically, examples of the alkyl group include a hydrogen atom, a methyl group, an ethyl group, a vinyl group, a 2,2,2-trifluoroethyl group, a propyl group, an isopropyl group, an allyl group, a butyl group, a s-butyl group, a t-butyl group, an isobutyl group, a pentyl group, a cyclopentyl group, a hexyl group, a cyclohexyl group, a cyclohexenyl group, a decyl group, a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, a s-butoxy group, a t-butoxy group, a norbornyl group, an adamantyl group, a phenyl group, a tolyl group, a xylyl group, a naphthyl group, a benzyl group, a 2-furanyl group, and a 2-tetrahydrofuranyl group. Among these, a hydrogen atom is more preferred.

[0123] W 4 is a divalent group represented by the above general formula (II-1). 5 is a single bond or any divalent group represented by the above general formula (II-2).2 is an integer between 2 and 10, and n 3 is an integer between 0 and 5.

[0124] R 20 , R 21 , R 22 , R 23 More specifically, examples of the alkyl group include a hydrogen atom, a hydroxyl group, a methyl group, an ethyl group, a vinyl group, a 2,2,2-trifluoroethyl group, a propyl group, an isopropyl group, an allyl group, a butyl group, a s-butyl group, a t-butyl group, an isobutyl group, a pentyl group, a cyclopentyl group, a hexyl group, a cyclohexyl group, a cyclohexenyl group, a decyl group, a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, a s-butoxy group, a t-butyl group, a butoxy group, a norbornyl group, an adamantyl group, a phenyl group, a tolyl group, a xylyl group, a naphthyl group, a benzyl group, a 2-furanyl group, and a 2-tetrahydrofuranyl group. Among these, a hydrogen atom and a methyl group are more preferred, and a hydrogen atom is even more preferred.

[0125] m 20 , m 21 is an integer between 0 and 10, and m 20 +m 21 ≧1.

[0126] R 3 , R 4 is a hydrogen atom, a hydroxyl group, or an optionally substituted organic group having 1 to 10 carbon atoms. More specific examples include a hydrogen atom, a hydroxyl group, a methyl group, an ethyl group, a vinyl group, a 2,2,2-trifluoroethyl group, a propyl group, an isopropyl group, an allyl group, a butyl group, a s-butyl group, a t-butyl group, an isobutyl group, a pentyl group, a cyclopentyl group, a hexyl group, a cyclohexyl group, a cyclohexenyl group, a decyl group, a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, a s-butoxy group, a t-butoxy group, a norbornyl group, an adamantyl group, a phenyl group, a tolyl group, a xylyl group, a naphthyl group, a benzyl group, a 2-furanyl group, and a 2-tetrahydrofuranyl group. Among these, a hydrogen atom is more preferred.

[0127] R6 is an organic group having 1 to 10 carbon atoms. 5 is an organic group having 1 to 10 carbon atoms and containing either an aromatic ring or a divalent group represented by the general formula (III-1). 3 , R 4 Examples include the groups listed above.

[0128] W 6 , W 7 is a single bond or a divalent group represented by the above general formula (III-2), and at least one of these is a divalent group represented by any of the above general formulas (III-2).

[0129] W 30 is an organic group having 1 to 4 carbon atoms. More specific examples include a methylene group, an ethylene group, a propylene group, a butylene group, a trimethylene group, and a tetramethylene group. Of these, an ethylene group is more preferred.

[0130] More specific examples of the compound represented by the above general formula (I) include, but are not limited to, the following. [ka]

[0131] Specific examples of the compound represented by the above general formula (II) include, but are not limited to, the following: [ka]

[0132] Specific examples of the compound represented by the above general formula (III) include, but are not limited to, the following: [ka]

[0133] In consideration of the improvement in dispersion stability of metal oxide nanoparticles in the metal oxide film-forming composition, film-forming properties, substrate embedding / planarization performance, and the like, the dispersion stabilizer (C) used in the metal oxide film-forming composition of the present invention is preferably an aromatic-containing compound having a benzyl group or a benzoyl group, and in particular, the following aromatic-containing compounds are preferred. (i) (Poly)ethylene glycol dibenzoate (ii) (Poly)ethylene glycol dibenzyl ether (iii) (Poly)propylene glycol dibenzyl ether (iv) (Poly)butylene glycol dibenzyl ether (v) Dibenzyl linear aliphatic dicarboxylate (vi) (Poly)ethylene glycol monobenzyl ether (vii) (Poly)phenyl ethers

[0134] [ka] In the above formulas (i) to (vii), n is an integer that results in a molecular weight in the range of 500 or less, and is applied only within these formulas.

[0135] The dispersion stabilizer (C) used in the metal oxide film-forming composition of the present invention has a structure that combines a hydrophobic portion consisting of an aromatic ring and a hydrophilic portion consisting of a structure containing O, such as the (C-1) structure, and therefore provides excellent dispersion stability for metal oxide nanoparticles even when the composition contains a high concentration of a flowability promoter resin, which is necessary for thick film formation. This makes it possible to provide a metal oxide film-forming composition with good storage stability.

[0136] The blend amount of (C) dispersion stabilizer is preferably 0.1 to 50 parts by mass, more preferably 0.5 to 30 parts by mass, and even more preferably 1 to 10 parts by mass, per 100 parts by mass of metal oxide nanoparticles. When the blend amount of dispersion stabilizer is 0.1% by mass or more, the fluidity of the metal oxide film-forming composition and the dispersion stability of the metal oxide nanoparticles are sufficiently improved. When the content of dispersion stabilizer relative to the metal nanoparticles is sufficiently high, the dispersion stabilization effect of the nanoparticles and the thermal fluidity improvement effect of the metal oxide film are sufficiently high. On the other hand, when the content of dispersion stabilizer is not too high, there is no risk of adversely affecting the film-forming properties and dry etching resistance of the resulting coating film.

[0137] The dispersion stabilizer of the present invention can use one of the above aromatic-containing compounds alone or a combination of two or more of them.

[0138] <(D) Organic Solvent> The organic solvent (D) that can be used in the metal oxide film-forming composition of the present invention is not particularly limited, as long as it can disperse the (A) metal oxide nanoparticles and dissolve the (B) flow promoter, (C) dispersion stabilizer, and, if included, the crosslinker, surfactant, acid generator, and other additives described below. Specifically, solvents with a boiling point below 180°C, such as those described in paragraphs

[0091] and

[0092] of JP 2007-199653 A, can be used. Among these, propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, 2-heptanone, cyclopentanone, cyclohexanone, and mixtures of two or more of these are preferred. The amount of organic solvent added is preferably 50 to 1,000 parts, more preferably 70 to 900 parts, and even more preferably 100 to 850 parts per 100 parts of the (B) flow promoter.

[0139] Such a composition for forming a metal oxide film allows (A) metal oxide nanoparticles to be dispersed well and can be applied by spin coating, making it possible to form a metal oxide film that has both dry etching resistance and high-level filling / planarization properties.

[0140] <Other ingredients> [Crosslinking agent] A crosslinking agent can also be added to the metal oxide film-forming composition of the present invention to enhance curability and further suppress intermixing with the overlying film. The crosslinking agent is not particularly limited, and a wide variety of known crosslinking agents can be used. Examples include methylol or alkoxymethyl crosslinking agents of polynuclear phenols (polynuclear phenol crosslinking agents), melamine crosslinking agents, glycoluril crosslinking agents, benzoguanamine crosslinking agents, urea crosslinking agents, β-hydroxyalkylamide crosslinking agents, isocyanurate crosslinking agents, aziridine crosslinking agents, oxazoline crosslinking agents, and epoxy crosslinking agents. When a crosslinking agent is added, the amount added is preferably 1 to 100 parts, more preferably 5 to 50 parts, based on the flowability promoter (B).

[0141] Specific examples of the melamine-based crosslinking agent include hexamethoxymethylated melamine, hexabutoxymethylated melamine, alkoxy- and / or hydroxy-substituted products thereof, and partial self-condensates thereof.

[0142] Specific examples of glycoluril crosslinking agents include tetramethoxymethylated glycoluril, tetrabutoxymethylated glycoluril, alkoxy and / or hydroxy substituted products thereof, and partial self-condensates thereof.

[0143] Specific examples of benzoguanamine-based crosslinking agents include tetramethoxymethylated benzoguanamine, tetrabutoxymethylated benzoguanamine, alkoxy- and / or hydroxy-substituted products thereof, and partial self-condensates thereof.

[0144] Specific examples of urea-based crosslinking agents include dimethoxymethylated dimethoxyethylene urea, its alkoxy and / or hydroxy substituted derivatives, and partial self-condensates thereof.

[0145] A specific example of the β-hydroxyalkylamide crosslinking agent is N,N,N',N'-tetra(2-hydroxyethyl)adipamide.

[0146] Specific examples of the isocyanurate crosslinking agent include triglycidyl isocyanurate and triallyl isocyanurate.

[0147] Specific examples of the aziridine crosslinking agent include 4,4'-bis(ethyleneiminocarbonylamino)diphenylmethane and 2,2-bishydroxymethylbutanol-tris[3-(1-aziridinyl)propionate].

[0148] Specific examples of the oxazoline-based crosslinking agent include 2,2'-isopropylidenebis(4-benzyl-2-oxazoline), 2,2'-isopropylidenebis(4-phenyl-2-oxazoline), 2,2'-methylenebis4,5-diphenyl-2-oxazoline, 2,2'-methylenebis-4-phenyl-2-oxazoline, 2,2'-methylenebis-4-tertbutyl-2-oxazoline, 2,2'-bis(2-oxazoline), 1,3-phenylenebis(2-oxazoline), 1,4-phenylenebis(2-oxazoline), and 2-isopropenyloxazoline copolymer.

[0149] Specific examples of epoxy-based crosslinking agents 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.

[0150] Specific examples of polynuclear phenol-based crosslinking agents include compounds represented by the following general formula (XL-1). [ka] (In the formula, Q is a single bond or a q-valent hydrocarbon group having 1 to 20 carbon atoms. R3 is a hydrogen atom or an alkyl group having 1 to 20 carbon atoms. q is an integer of 1 to 5.)

[0151] Q is a single bond or an s-valent hydrocarbon group having 1 to 20 carbon atoms. q is an integer of 1 to 5, and more preferably 2 or 3. Specific examples of Q include groups obtained by removing q hydrogen atoms from methane, ethane, propane, butane, isobutane, pentane, cyclopentane, hexane, cyclohexane, methylpentane, methylcyclohexane, dimethylcyclohexane, trimethylcyclohexane, benzene, toluene, xylene, ethylbenzene, ethylisopropylbenzene, diisopropylbenzene, methylnaphthalene, ethylnaphthalene, and eicosane. R3 is a hydrogen atom or an alkyl group having 1 to 20 carbon atoms. Specific examples of the alkyl group having 1 to 20 carbon atoms include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, isopentyl, hexyl, octyl, ethylhexyl, decyl, and eicosanyl, with a hydrogen atom or a methyl group being preferred.

[0152] Specific examples of compounds represented by the general formula (XL-1) include the following compounds. Among these, hexamethoxymethylated triphenolmethane, triphenolethane, 1,1,1-tris(4-hydroxyphenyl)ethane, and tris(4-hydroxyphenyl)-1-ethyl-4-isopropylbenzene are preferred from the viewpoint of improving the curability and thickness uniformity of the organic film. R3 is the same as above. [ka]

[0153] [ka]

[0154] [Surfactants] A surfactant can be added to the metal oxide film-forming composition of the present invention to improve the coating properties during spin coating. Examples of surfactants that can be used include those described in paragraphs

[0142] to

[0147] of JP-A No. 2009-269953. When a surfactant is added, the amount added is preferably 0.01 to 10 parts, more preferably 0.05 to 5 parts, per 100 parts by mass of the (B) flowability promoter.

[0155] [Acid generator] In the metal oxide film-forming composition of the present invention, an acid generator can be added to further accelerate the curing reaction. Acid generators include those that generate acid by thermal decomposition and those that generate acid by light irradiation, and either can be added. Specifically, materials described in paragraphs

[0061] to

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

[0156] The acid generators can be used alone or in combination of two or more. When an acid generator is added, the amount added is preferably 0.05 to 50 parts, more preferably 0.1 to 10 parts, per 100 parts by mass of the (B) flowability promoter.

[0157] [Plasticizer] A plasticizer can be added to the metal oxide film-forming composition of the present invention to further improve the planarization / filling properties. The plasticizer is not particularly limited, and various known plasticizers can be widely used. Examples include low-molecular-weight compounds such as phthalates, adipates, phosphates, trimellitates, and citrates, as well as polymers such as polyethers, polyesters, and polyacetal polymers described in JP 2013-253227 A. When a plasticizer is added, the amount added is preferably 1 to 100 parts, more preferably 5 to 30 parts, per 100 parts by mass of the (B) flowability promoter.

[0158] Furthermore, in the metal oxide film-forming composition of the present invention, additives that impart filling / planarizing properties similar to those of plasticizers are preferably used, such as liquid additives having a polyethylene glycol or polypropylene glycol structure, or thermally decomposable polymers that have 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. These thermally decomposable polymers preferably contain repeating units having an acetal structure represented by the following general formulas (DP1) and (DP1a):

[0159] [ka] (In the formula, R6 is a hydrogen atom or an optionally substituted saturated or unsaturated monovalent organic group having 1 to 30 carbon atoms. Y is a saturated or unsaturated divalent organic group having 2 to 30 carbon atoms.)

[0160] [ka] (In the formula, R 6a is an alkyl group having 1 to 4 carbon atoms. a is a saturated or unsaturated divalent hydrocarbon group having 4 to 10 carbon atoms, which may have an ether bond; and n represents the average number of repeating units and is 3 to 500.

[0161] [Dispersant] In addition to the dispersion stabilizer (C), a conventional dispersant may be added to the metal oxide film-forming composition of the present invention. The type of dispersant used is not particularly limited, and known dispersants can be used. Examples include low-molecular-weight dispersants such as alkylamines, alkanethiols, alkanediols, and phosphate esters, polymeric dispersants having various functional groups, and silane coupling agents. Examples of polymeric dispersants include styrene-based resins (styrene-(meth)acrylic acid copolymers, styrene-maleic anhydride copolymers, etc.), acrylic resins (methyl (meth)acrylate-(meth)acrylic acid copolymers, poly(meth)acrylic acid, and other (meth)acrylic acid-based resins), water-soluble urethane resins, water-soluble acrylic urethane resins, water-soluble epoxy resins, water-soluble polyester resins, and cellulose derivatives (nitrocellulose; Examples of suitable dispersants include alkyl celluloses (e.g., ethyl cellulose), alkyl-hydroxyalkyl celluloses (e.g., ethylhydroxyethyl cellulose), hydroxyalkyl celluloses (e.g., hydroxyethyl cellulose, hydroxypropyl cellulose), and carboxyalkyl celluloses (e.g., carboxymethyl cellulose), polyvinyl alcohol, polyalkylene glycols (e.g., liquid polyethylene glycol and polypropylene glycol), natural polymers (e.g., polysaccharides (e.g., gelatin, casein, dextrin, and gum arabic), polyethylene sulfonic acid or its salts, polystyrene sulfonic acid or its salts, formalin condensates of naphthalene sulfonic acid, and nitrogen-containing polymeric compounds (e.g., polymeric compounds having amino groups, such as polyalkyleneimines (e.g., polyethyleneimines), polyvinylpyrrolidone, polyallylamine, and polyetherpolyamines (e.g., polyoxyethylenepolyamines)). The amount of dispersant used is preferably 0.1 to 50 parts by weight, more preferably 0.5 to 30 parts by weight, and even more preferably 1 to 10 parts by weight, per 100 parts by weight of metal oxide nanoparticles.

[0162] Adding the dispersant in addition to the dispersion stabilizer (C) can further improve the ability to prevent aggregation of metal nanoparticles.

[0163] The metal oxide film-forming composition of the present invention can be used alone or in combination of two or more. The metal oxide film-forming composition can be used as a metal oxide film material or a planarizing material for manufacturing semiconductor devices.

[0164] As described above, the metal oxide film-forming composition of the present invention contains a (B) flowability promoter with excellent crack resistance, making it possible to form thick films that exhibit excellent dry etching resistance derived from (A) metal oxide nanoparticles. Furthermore, the inclusion of a (C) dispersion stabilizer, which can further improve the thermal fluidity of the flowability promoter resin, makes it possible to provide a resist underlayer film material that can fill high-aspect ratio patterned substrates without voids, which is difficult to achieve with metal oxide nanoparticles alone. Furthermore, the inclusion of a dispersion stabilizer with a specific structure allows the nanoparticles to maintain a well-dispersed state even in highly concentrated chemical solutions with a resin content of 9% by mass or more, providing a metal oxide film-forming composition with excellent storage stability.

[0165] (Pattern formation method) Further, in the present invention, a pattern forming method by a two-layer resist process using such a composition for forming a metal oxide film is provided, which includes the steps of: A method for forming a pattern on a workpiece substrate, comprising: (I-1) a step of applying the composition for forming a metal oxide film onto a substrate to be processed, followed by heat treatment to form a metal oxide film; (I-2) forming a resist top layer film on the metal oxide film using a photoresist material; (I-3) a step of pattern-exposing the resist upper layer film and then developing it with a developer to form a pattern on the resist upper layer film; (I-4) a step of transferring the pattern to the metal oxide film by dry etching using the resist upper layer film on which the pattern has been formed as a mask; and (I-5) A step of processing the substrate to be processed using the metal oxide film on which the pattern has been formed as a mask to form a pattern on the substrate to be processed. The present invention provides a pattern forming method comprising the steps of:

[0166] The resist top layer film in the two-layer resist process exhibits etching resistance against chlorine-based gases, and therefore, in the two-layer resist process, it is preferable to perform dry etching of the metal oxide film using the resist top layer film as a mask using an etching gas mainly containing a chlorine-based gas.

[0167] Further, in the present invention, a pattern forming method by a three-layer resist process using such a composition for forming a metal oxide film is provided, which includes the steps of: A method for forming a pattern on a workpiece substrate, comprising: (II-1) A step of applying the composition for forming a metal oxide film onto a substrate to be processed, followed by heat treatment to form a metal oxide film; (II-2) forming a silicon-containing resist intermediate film on the metal oxide film using a silicon-containing resist intermediate film material; (II-3) forming a resist upper layer film on the silicon-containing resist intermediate film using a photoresist material; (II-4) a step of pattern-exposing the resist upper layer film and then developing it with a developer to form a pattern on the resist upper layer film; (II-5) a step of transferring the pattern to the silicon-containing resist intermediate film by dry etching using the resist upper layer film on which the pattern has been formed as a mask; (II-6) a step of transferring a pattern to the metal oxide film by dry etching using the silicon-containing resist intermediate film to which the pattern has been transferred as a mask; and (II-7) A step of processing the substrate to be processed using the metal oxide film on which the pattern has been formed as a mask to form a pattern on the substrate to be processed. The present invention provides a pattern forming method comprising the steps of:

[0168] An example of a three-layer resist process is specifically shown below with reference to Figure 1. In the three-layer resist process, as shown in Figure 1(A), a metal oxide film (metal-containing resist underlayer film) 3 is formed on a processable layer 2 laminated on a processable substrate 1 using the metal oxide film-forming material of the present invention, and then a silicon atom-containing resist intermediate film 4 is formed thereon, and a resist upper layer film 5 is formed thereon.

[0169] Next, as shown in FIG. 1(B), a desired portion (exposed portion) 6 of the resist top layer 5 is exposed, followed by PEB and development to form a resist top layer pattern 5a (FIG. 1(C)). Using the resulting resist top layer pattern 5a as a mask, the silicon-containing resist intermediate film 4 is etched with a CF-based gas to form a silicon-containing resist intermediate film pattern 4a (FIG. 1(D)). After removing the resist top layer pattern 5a, the metal oxide film 3 is plasma-etched with a chlorine-based gas using the resulting silicon-containing resist intermediate film pattern 4a as a mask to form a metal oxide film pattern (metal-containing resist bottom layer pattern) 3a (FIG. 1(E)). After removing the silicon-containing resist intermediate film pattern 4a, the workpiece layer 2 is etched using the metal oxide film pattern 3a as a mask to form a pattern 2a to be formed in the workpiece layer (FIG. 1(F)).

[0170] The silicon-containing resist intermediate film in the three-layer resist process exhibits etching resistance to chlorine-based gases. Therefore, in the three-layer resist process, dry etching of the metal oxide film using the silicon-containing resist intermediate film as a mask is preferably performed using an etching gas mainly containing a chlorine-based gas.

[0171] Polysiloxane-based interlayers are also preferred as the silicon-containing resist interlayer in the three-layer resist process. By providing the silicon-containing resist interlayer with anti-reflection properties, reflection can be reduced. For 193 nm exposure, in particular, using an organic film containing many aromatic groups and exhibiting high etching selectivity with respect to the substrate increases the k value and substrate reflection. However, by providing the silicon-containing resist interlayer with an absorption that results in an appropriate k value, reflection can be reduced, reducing substrate reflection to 0.5% or less. For silicon-containing resist interlayers with anti-reflection properties, anthracene is preferred for 248 nm and 157 nm exposure, while for 193 nm exposure, polysiloxanes with pendant light-absorbing groups having phenyl groups or silicon-silicon bonds and crosslinked by acid or heat are preferred.

[0172] In addition, the present invention provides a pattern formation method by a four-layer resist process using such a metal oxide film-forming composition, comprising the steps of forming a metal oxide film on a substrate to be processed using the metal oxide film-forming composition, forming a silicon-containing resist intermediate film on the resist underlayer film using a silicon-containing resist intermediate film material, forming an organic antireflective coating (BARC) or an adhesion film on the silicon-containing resist intermediate film, forming a resist upper layer film on the BARC using a photoresist material, pattern-exposing the resist upper layer film and then developing it with a developer to form a pattern in the resist upper layer film, using the resist upper layer film on which the pattern has been formed as a mask to transfer the pattern to the BARC or adhesion film and the silicon-containing resist intermediate film by dry etching, using the silicon-containing resist intermediate film on which the pattern has been transferred as a mask to transfer the pattern to the metal oxide film by dry etching, and processing the substrate to be processed using the metal oxide film on which the pattern has been formed as a mask to form a pattern on the substrate to be processed.

[0173] Alternatively, an inorganic hard mask may be formed instead of the silicon-containing resist intermediate film. In this case, a semiconductor device circuit pattern can be formed on a substrate by at least forming a metal oxide film on a workpiece using the metal oxide film-forming composition of the present invention, forming an inorganic hard mask selected from a silicon oxide film, a silicon nitride film, and a silicon oxynitride film on the metal oxide film, forming a resist upper layer film on the inorganic hard mask using a photoresist composition, forming a circuit pattern on the resist upper layer film, etching the inorganic hard mask using the resist upper layer film on which the pattern has been formed as a mask, etching the metal oxide film using the inorganic hard mask on which the pattern has been formed as a mask, and further etching the workpiece using the metal oxide film on which the pattern has been formed as a mask to form a pattern on the workpiece.

[0174] The present invention also provides A method for forming a pattern on a workpiece substrate, comprising: (III-1) A step of applying the composition for forming a metal oxide film to a substrate to be processed, followed by heat treatment to form a metal oxide film; (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 metal oxide film; (III-3) forming an organic thin film on the inorganic hard mask intermediate film; (III-4) forming a resist top layer film on the organic thin film using a photoresist material; (III-5) a step of pattern-exposing the resist upper layer film and then developing it with a developer to form a pattern on the resist upper layer film; (III-6) a step of transferring the pattern to the organic thin film and the inorganic hard mask intermediate film by dry etching using the resist upper layer film on which the pattern has been formed as a mask; (III-7) transferring the pattern to the metal oxide film by dry etching using the inorganic hard mask intermediate film to which the pattern has been transferred as a mask; and (III-8) A step of processing the substrate to be processed using the metal oxide film on which the pattern has been formed as a mask to form a pattern on the substrate to be processed. The present invention provides a pattern forming method comprising the steps of:

[0175] In this case, the inorganic hard mask is preferably formed by a CVD method or an ALD method.

[0176] When the inorganic hard mask is formed by the CVD method or the ALD method, a fine pattern can be formed on the workpiece with higher precision.

[0177] As described above, when forming an inorganic hard mask on a metal oxide film, a silicon oxide film, a silicon nitride film, or a silicon oxynitride film (SiON film) can be formed by a CVD method, an ALD method, or the like. For example, methods for forming a silicon nitride film are described in Japanese Patent Application Laid-Open No. 2002-334869 and International Publication No. 2004 / 066377. The thickness of the inorganic hard mask is preferably 5 to 200 nm, more preferably 10 to 100 nm. Furthermore, a SiON film, which is highly effective as an anti-reflective coating, is most preferably used as the inorganic hard mask. Since the substrate temperature during SiON film formation is 300 to 500°C, the metal oxide film must be able to withstand temperatures of 300 to 500°C. The metal oxide film-forming composition used in the present invention has high heat resistance and can withstand high temperatures of 300 to 500°C, making it possible to combine an inorganic hard mask formed by a CVD method or an ALD method with a metal oxide film formed by a spin-coating method.

[0178] As described above, a photoresist film can be formed on an inorganic hard mask as a resist top layer. Alternatively, an organic antireflective coating (BARC) or adhesion film can be formed on the inorganic hard mask by spin coating, and then a photoresist film can be formed on top of that. In particular, when a SiON film is used as the inorganic hard mask, the two-layer antireflective coating consisting of the SiON film and the BARC can suppress reflection even in immersion lithography with a high NA exceeding 1.0. Another advantage of forming a BARC is that it reduces the footing of the photoresist pattern directly above the SiON film.

[0179] The resist top layer film in the above multilayer resist process may be either positive or negative, and the same photoresist compositions as those commonly used can be used. After spin-coating the photoresist composition, pre-baking is performed, preferably at 60 to 180°C for 10 to 300 seconds. Thereafter, exposure is performed according to a conventional method, followed by post-exposure baking (PEB) and development to obtain a resist pattern. The thickness of the resist top layer film is not particularly limited, but is preferably 30 to 500 nm, and more preferably 50 to 400 nm.

[0180] Examples of exposure light include high energy rays with a wavelength of 300 nm or less, specifically excimer lasers with wavelengths of 248 nm, 193 nm, and 157 nm, soft X-rays with wavelengths of 3 to 20 nm, electron beams, and X-rays.

[0181] When the above method is used as a method for forming a circuit pattern on the resist upper layer film, a fine pattern can be formed on the workpiece with higher precision.

[0182] The method for forming a pattern on the resist upper layer film is preferably photolithography with a wavelength of 5 nm or more and 300 nm or less, direct writing with an electron beam, nanoimprinting, or a combination thereof.

[0183] In addition, the development method in the pattern formation method is preferably alkaline development or organic solvent development. Specifically, in the pattern formation method, exposure and development are performed to form a circuit pattern on the resist upper layer film, and the development is preferably alkaline development or organic solvent development.

[0184] When alkaline development or development using an organic solvent is used as the development method, a fine pattern can be formed on the workpiece with higher precision.

[0185] Next, etching is performed using the obtained resist pattern as a mask. In the three-layer resist process, etching of the silicon-containing resist intermediate film and inorganic hard mask is performed using a fluorocarbon-based gas as a mask for the upper resist pattern. This results in the formation of a silicon-containing resist intermediate film pattern and an inorganic hard mask pattern.

[0186] Next, the metal oxide film is etched using the silicon-containing resist intermediate film pattern or inorganic hard mask pattern as a mask, preferably using a chlorine-based gas.

[0187] The next etching of the workpiece can also be carried out using standard methods. For example, if the workpiece is made of SiO2, SiN, or a silica-based low-k insulating film, etching is carried out using mainly fluorocarbon gases. When etching the substrate with fluorocarbon gases, the silicon-containing resist intermediate film pattern in the three-layer resist process is removed at the same time as the substrate is processed.

[0188] The metal oxide film obtained from the metal oxide film-forming composition of the present invention is characterized by excellent etching resistance when etching the workpiece.

[0189] The workpiece (substrate) is not particularly limited, and may be a substrate such as Si, α-Si, p-Si, SiO2, SiN, SiON, W, TiN, or Al, or a substrate with a workpiece layer formed thereon. The workpiece layer may be a low-k film or a stopper film thereof, such as Si, SiO2, SiON, SiN, p-Si, α-Si, W, W-Si, Al, Cu, or Al-Si, and may be formed to a thickness of typically 50 to 10,000 nm, particularly 100 to 5,000 nm. When forming a workpiece layer, the substrate and workpiece layer are made of different materials.

[0190] The workpiece is preferably a semiconductor device substrate, or a semiconductor device substrate having any of a metal film, a metal carbide film, a metal oxide film, a metal nitride film, a metal carbide oxide film, and a metal oxynitride film formed thereon. More specifically, although not limited to, substrates such as Si, α-Si, p-Si, SiO, SiN, SiON, W, TiN, and Al, or a substrate having the above-mentioned metal film formed thereon as a workpiece layer, may be used.

[0191] The work layer may be a low-k film or a stopper film thereof, such as Si, SiO2, SiON, SiN, p-Si, α-Si, W, W-Si, Al, Cu, or Al-Si, and may be formed to a thickness of typically 50 to 10,000 nm, particularly 100 to 5,000 nm. When forming the work layer, the substrate and the work layer are made of different materials.

[0192] The metal constituting the workpiece is preferably silicon, titanium, tungsten, hafnium, zirconium, chromium, germanium, copper, silver, gold, aluminum, indium, gallium, arsenic, palladium, iron, tantalum, iridium, cobalt, manganese, molybdenum, ruthenium, or an alloy thereof.

[0193] The above metals can be used as the metal oxide film. In this way, when a pattern is formed using the metal oxide film-forming composition of the present invention, it becomes possible to transfer and form the pattern of the upper photoresist layer onto the workpiece with high precision.

[0194] The pattern formation method of the present invention preferably uses a substrate to be processed having structures or steps with an aspect ratio of 5 or more. As described above, the metal oxide film-forming composition of the present invention has excellent filling / planarizing properties, and therefore can fill without voids even if the substrate to be processed has structures or steps (unevenness) with an aspect ratio of 5 or more, thereby forming a flat cured film. The aspect ratio of the structures or steps of the substrate to be processed is preferably 5 or more, and more preferably 10 or more. In a method for processing a substrate to be processed having structures or steps with the above aspect ratios, forming a film using the metal oxide film-forming composition of the present invention to perform filling / planarization makes it possible to uniformize the film thicknesses of the subsequently formed resist intermediate film and resist top layer film, which is highly preferred because it makes it easy to ensure a depth of exposure margin (DOF) during photolithography.

[0195] Further, in the present invention, a method for forming a tone-reversal pattern using such a composition for forming a metal oxide film is provided, which comprises: A method for forming a pattern on a workpiece substrate, comprising: (IV-1) forming a resist underlayer film on a substrate to be processed; (IV-2) forming a resist intermediate film or a combination of an inorganic hard mask intermediate film selected from a silicon oxide film, a silicon nitride film, and a silicon oxynitride film and an organic thin film on the resist underlayer film; (IV-3) forming a resist upper layer film using a photoresist material on the resist intermediate film or the combination of the inorganic hard mask intermediate film and the organic thin film; (IV-4) a step of pattern-exposing the resist upper layer film and then developing it with a developer to form a pattern on the resist upper layer film; (IV-5) a step of transferring a pattern to the resist intermediate film, or the organic thin film and the inorganic hard mask intermediate film, by dry etching using the resist upper layer film on which the pattern has been formed as a mask; (IV-6) a step of transferring a pattern to the resist underlayer film by dry etching using the resist interlayer film or inorganic hard mask interlayer film to which the pattern has been transferred as a mask; (IV-7) a step of applying the composition for forming a metal oxide film onto the resist underlayer film on which the pattern has been formed, followed by heat treatment to cover the resist underlayer film with a metal oxide film, and filling spaces between the resist underlayer film patterns with the metal oxide film; (IV-8) etching back the metal oxide film covering the resist underlayer film on which the pattern has been formed by chemical stripping or dry etching to expose the upper surface of the resist underlayer film on which the pattern has been formed; (IV-9) a step of removing the resist intermediate film or inorganic hard mask intermediate film remaining on the upper surface of the resist underlayer film by dry etching; (IV-10) a step of removing the resist underlayer film on which the pattern is formed and the surface is exposed by dry etching, thereby forming a reverse pattern of the original pattern on the metal oxide film; (IV-11) A step of processing the substrate to be processed using the metal oxide film on which the reversal pattern is formed as a mask to form a tone-reversal pattern on the substrate to be processed. The present invention provides a pattern forming method comprising the steps of:

[0196] An example of forming a tone reversal pattern is specifically shown below with reference to Figure 2. As shown in Figure 2(G), a resist underlayer film 7 made of a coating-type organic underlayer film material is formed on a processable layer 2 laminated on a processable substrate 1, and then a silicon-containing resist intermediate film 4 is formed, and a resist upper layer film 5 is formed thereon.

[0197] Next, as shown in FIG. 2(H), a desired portion (exposed portion) 6 of the resist top layer film 5 is exposed, followed by PEB and development to form a resist top layer film pattern 5a (FIG. 2(I)). Using the resulting resist top layer film pattern 5a as a mask, the silicon atom-containing resist intermediate film 4 is etched using a CF-based gas to form a silicon atom-containing resist intermediate film pattern 4a (FIG. 2(J)). After removing the resist top layer film pattern 5a, the resist underlayer film 7 made of a coating-type organic underlayer film material is oxygen plasma etched using the resulting silicon atom-containing resist intermediate film pattern 4a as a mask to form a resist underlayer film pattern 7a made of a coating-type organic underlayer film material (FIG. 2(K)).

[0198] The metal oxide film-forming composition of the present invention is applied to a resist underlayer film pattern 7a made of a coating-type organic underlayer film material, followed by heat treatment to form a metal oxide film 8, filling the spaces between the resist underlayer film patterns 7a made of the coating-type organic underlayer film material (FIG. 2(L)). Next, the metal oxide film 8 covering the resist underlayer film pattern 7a made of the coating-type organic underlayer film material is etched back using a chemical stripper or dry etching to expose the top surface of the resist underlayer film pattern 7a made of the coating-type organic underlayer film material, leaving a metal oxide film pattern 8a, which is the inverse of the resist underlayer film pattern, between the resist underlayer film patterns 7a made of the coating-type organic underlayer film material (FIG. 2(M)). Furthermore, the silicon-containing resist intermediate film pattern 4a remaining on the top surface of the resist underlayer film pattern 7a made of the coating-type organic underlayer film material is removed by dry etching (FIG. 2(N)). Next, the resist underlayer film pattern 7a made of the coating-type organic underlayer film material is removed by dry etching, and an inverted pattern of the original pattern is formed on the metal oxide film (forming a metal oxide film pattern 8a that is an inversion of the resist underlayer film pattern) (Figure 2(O)). After that, the substrate to be processed is processed using the metal oxide film pattern 8a that is an inversion of the resist underlayer film pattern as a mask, and a tone-reversed pattern 2a is formed on the substrate to be processed (Figure 2(P)).

[0199] As described above, when forming an organic resist underlayer film on a substrate to be processed, the organic resist underlayer film can be formed by a method using a coating type organic underlayer film material, a CVD method, or the like. Coating-type organic underlayer film materials include those described in JP 2012-1687 A, JP 2012-77295 A, JP 2004-264710 A, JP 2005-043471 A, JP 2005-250434 A, JP 2007-293294 A, JP 2008-65303 A, JP 2004-205685 A, JP 2007-171895 A, JP 2009-14816 A, JP 2007-199653 A, JP 2008-274250 A, JP 2010-122656 A, and JP 2012-214720 A. Examples of the resins and compositions disclosed in JP 2014-29435 A, WO 2012 / 077640 A, WO 2010 / 147155 A, WO 2012 / 176767 A, JP 2005-128509 A, JP 2006-259249 A, JP 2006-259482 A, JP 2006-293298 A, JP 2007-316282 A, JP 2012-145897 A, JP 2017-119671 A, JP 2019-44022 A, etc. Examples of the organic resist underlayer film formed by the CVD method include an amorphous carbon film.

[0200] In the tone reversal pattern formation method, it is preferable to coat the obtained resist underlayer film pattern with a metal oxide film-forming composition, and then remove the metal oxide film by dry etching using a chlorine-based gas to expose the upper surface of the resist underlayer film pattern. Thereafter, the resist intermediate film or hard mask intermediate film remaining on the resist underlayer film is removed by dry etching using a chlorofluorocarbon-based gas, and the exposed surface of the resist underlayer film pattern is removed by dry etching using an oxygen-based gas, thereby forming a metal oxide film pattern.

[0201] In the tone reversal pattern formation method, it is preferable to use a workpiece substrate having structures or steps with an aspect ratio of 5 or more. As described above, the metal oxide film-forming composition of the present invention has excellent filling / planarizing properties, so even if there are structures or steps (unevenness) with an aspect ratio of 5 or more, it can fill them without voids and form a flat cured film. The aspect ratio of the structures or steps of the workpiece substrate is preferably 5 or more, and more preferably 10 or more. In a method for reversing a resist underlayer film pattern having a pattern of the above height, forming a film using the metal oxide film-forming composition of the present invention and performing filling / planarization enables high-precision pattern reversal / transfer, which is highly preferable. Compared to resist underlayer films made with conventional coating-type organic underlayer film materials, the metal oxide film-forming composition has excellent dry etching resistance using fluorocarbon-based gases. Therefore, by reversing a resist underlayer film pattern with the metal oxide film-forming composition, a desired resist pattern can be formed on a workpiece film with high precision.

[0202] In the two-layer resist pattern forming method, three-layer resist pattern forming method, four-layer resist pattern forming method, and tone reversal pattern forming method of the present invention, it is preferable to form a pattern having an aspect ratio of 5 or more on the substrate to be processed. As described above, the metal oxide film-forming composition of the present invention can form a thick metal oxide film with excellent dry etching resistance, thereby enabling high-aspect-ratio patterns to be transferred to the substrate to be processed with high precision. The aspect ratio of the pattern formed on the substrate to be processed using the metal oxide film as a hard mask is preferably 5 or more, and more preferably 10 or more. In order to transfer a high-aspect-ratio pattern with high precision, the hard mask is required to have an expanded film-thickening margin and excellent dry etching resistance. However, the metal oxide film-forming composition of the present invention can form a thick metal oxide film of 1 μm or more by using a flowability promoter with excellent crack resistance.

[0203] The present invention also provides a pattern forming method using the above-mentioned metal oxide film-forming composition as a sacrificial film, comprising: (V-1) a step of applying the composition for forming a metal oxide film onto a substrate to be processed having a structure or a step, and then performing a heat treatment to fill the substrate with a metal oxide film; (V-2) a step of removing the metal oxide film outside the structure or step on the substrate to be processed by a CMP method, thereby removing the metal oxide film from the surface of the substrate to be processed; (V-3) a step of alternately laminating insulating films and conductive films on the substrate to be processed filled with the metal oxide film; (V-4) forming an organic resist underlayer film on the laminated film of the insulating film and the conductive film formed on the substrate to be processed filled with the metal oxide film; (V-5) forming a resist intermediate film, or an inorganic hard mask intermediate film selected from a silicon oxide film, a silicon nitride film, and a silicon oxynitride film, or a combination of the inorganic hard mask intermediate film and an organic thin film on the organic resist underlayer film; (V-6) forming a resist upper layer film using a photoresist material on the resist intermediate film, or the inorganic hard mask intermediate film, or the combination of the inorganic hard mask intermediate film and the organic thin film; (V-7) a step of pattern-exposing the resist upper layer film and then developing it with a developer to form a pattern on the resist upper layer film; (V-8) a step of transferring a pattern to the resist intermediate film, or the inorganic hard mask intermediate film, or the organic thin film and the inorganic hard mask intermediate film by dry etching using the resist upper layer film on which the pattern has been formed as a mask; (V-9) a step of transferring a pattern to the resist underlayer film by dry etching using the resist interlayer film or inorganic hard mask interlayer film to which the pattern has been transferred as a mask; (V-10) a step of transferring a pattern to the laminated film of the insulating film and the conductive film by dry etching using the resist underlayer film to which the pattern has been transferred as a mask; (V-11) A step of removing the metal oxide film filled on the substrate to be processed using the laminated film of the insulating film and the conductive film to which the pattern has been transferred as a mask. The present invention provides a pattern forming method comprising the steps of:

[0204] An example of a pattern formation method using the above-mentioned metal oxide film-forming composition as a sacrificial film is specifically shown below with reference to Fig. 3. As shown in Fig. 3(Q), insulating film patterns 10a and conductive film patterns 9a are alternately stacked, and a step formed in an alternately stacked film (lower layer) 100 of the insulating film patterns 10a and conductive film patterns 9a including upper and lower connecting insulating films 11 is coated with the metal oxide film-forming composition of the present invention, and then heat-treated to form a metal oxide film 12 (Fig. 3(R)).The metal oxide film 12 outside the step is then removed by CMP, and the metal oxide film 12 is removed from the surface of the workpiece substrate to flatten it (Fig. 3(S)). After removing the metal oxide film outside the step by the CMP planarization, an alternating laminated film (upper layer) 200 of an insulating film 10 and a conductive film 9 is formed (FIG. 3(T)), an organic resist underlayer film 13 is formed on the alternating laminated film, a silicon atom-containing resist intermediate film 14 (a polysiloxane-based resist intermediate film, or an inorganic hard mask intermediate film selected from a silicon oxide film, a silicon nitride film, and a silicon oxynitride film, or a combination of the inorganic hard mask intermediate film and an organic thin film) is formed on the organic resist underlayer film 13, and a resist upper layer film 15 is formed on the resist intermediate film 14 (FIG. 3(U)).

[0205] Next, the resist upper layer film 15 is exposed, and PEB and development are performed to form a resist upper layer film pattern 15a (FIG. 3(V)). Using the resulting resist upper layer film pattern 15a as a mask, the silicon atom-containing resist intermediate film 14 is etched using a CF-based gas to form a silicon atom-containing resist intermediate film pattern 14a (FIG. 3(W)). After removing the resist upper layer film pattern 15a, the organic resist lower layer film 13 is oxygen plasma etched using the resulting silicon atom-containing resist intermediate film pattern 14a as a mask to form an organic resist lower layer film pattern 13a (FIG. 3(X)). Using the resist lower layer film pattern 13a as a mask, the alternating laminate film (upper layer) 200 of the insulating film 10 and the conductive film 9 is dry etched using a CF-based gas to form a high aspect ratio pattern (FIG. 3(Y)). Thereafter, the metal oxide film 12a that has been planarized by CMP and that has filled the steps of the workpiece layer 100 is removed by dry etching using a chlorine-based gas, penetrating the pattern formed in the laminated film 200 and the pattern 16 formed in the alternating laminated film (lower layer) 100 of the insulating film pattern 10 and the conductive film pattern 9a (forming a penetrating pattern 16 of 100 layers and 200 layers) (Figure 3(Z)).

[0206] The stacked film 100 of the insulating film pattern 10a and the conductive film pattern 9a, as well as the alternating stacked film 200 of the insulating film 10 and the conductive film 9, are deposited on a substrate using suitable deposition precursors for CVD or atomic layer deposition (ALD). The insulating film pattern 10a and the insulating film 10 may be formed from any suitable insulating material(s). By way of example, and without limitation, the insulating material may include silicon oxide (e.g., SiO2). The conductive film pattern 9a and the conductive film 9 may be formed from any suitable conductive material(s), including one or more of polysilicon and metals such as tungsten, nickel, titanium, platinum, aluminum, gold, tungsten nitride, tantalum nitride, titanium nitride, and silicon nitride.

[0207] As described above, when forming the organic resist underlayer film 13 on the alternately laminated film 200 of the insulating film 10 and the conductive film 9, the organic resist underlayer film can be formed by a method using a coating type organic underlayer film material, a CVD method, or the like. Coating-type organic underlayer film materials include those described in JP 2012-1687 A, JP 2012-77295 A, JP 2004-264710 A, JP 2005-043471 A, JP 2005-250434 A, JP 2007-293294 A, JP 2008-65303 A, JP 2004-205685 A, JP 2007-171895 A, JP 2009-14816 A, JP 2007-199653 A, JP 2008-274250 A, JP 2010-122656 A, and JP 2012-214720 A. Examples of resins and compositions include those disclosed in JP 2014-29435 A, WO 2012 / 077640 A, WO 2010 / 147155 A, WO 2012 / 176767 A, JP 2005-128509 A, JP 2006-259249 A, JP 2006-259482 A, JP 2006-293298 A, JP 2007-316282 A, JP 2012-145897 A, JP 2017-119671 A, and JP 2019-44022 A. Alternatively, the resist underlayer film may be an organic resist underlayer film containing metal atoms selected from zirconium, hafnium, aluminum, tungsten, titanium, copper, tin, cerium, indium, zinc, yttrium, lanthanum, chromium, cobalt, platinum, iron, antimony, and germanium, or a combination thereof, and the metal oxide film-forming composition of the present invention may be used.

[0208] Examples of the organic resist underlayer film formed by the CVD method include an amorphous carbon film, or a doped carbon film containing metal atoms of zirconium, hafnium, aluminum, tungsten, titanium, copper, tin, cerium, indium, zinc, yttrium, lanthanum, chromium, cobalt, platinum, iron, antimony, and germanium, or a combination thereof.

[0209] The steps formed in the alternating laminate film 100 of the insulating film pattern 10a and the conductive film pattern 9a preferably have an aspect ratio of 5 or more. As described above, the metal oxide film-forming composition of the present invention has excellent filling / planarizing properties, and therefore can fill without voids even when the workpiece substrate has structures or steps (unevenness) with an aspect ratio of 5 or more, thereby forming a flat cured film. The aspect ratio of the structures or steps of the workpiece substrate is preferably 5 or more, more preferably 10 or more, even more preferably 20 or more, and particularly preferably 50 or more. In a method for filling a workpiece substrate having structures or steps with the above aspect ratios, forming a film of the metal oxide film-forming composition of the present invention and performing filling / planarization makes it possible to uniformize the film thickness of the subsequently formed alternating layers of insulating film and conductive film, and the film thickness of the photoresist formed on the alternating layers. This makes it easier to ensure a depth of exposure (DOF) during photolithography, which is highly preferred in a 3D-NAND multi-stack manufacturing process. Furthermore, since the composition for forming a metal oxide film of the present invention has excellent heat resistance, even when undergoing a process of forming alternating layers of insulating films and conductive films on a workpiece substrate filled with a metal oxide film, no voids or peeling occurs in the filled film, and it is possible to form a high aspect ratio pattern with high precision.

[0210] The thickness of the organic resist underlayer film 13 is determined in consideration of the thickness of the alternately laminated film 200 of the insulating film 10 and the conductive film 9, which are the films to be etched, and may be formed to a thickness of, for example, 10,000 to 100,000 Å.

[0211] The resist top layer film in the above multilayer resist process may be either positive or negative, and the same photoresist compositions as those commonly used can be used. After spin-coating the photoresist composition, pre-baking is performed, preferably at 60 to 180°C for 10 to 300 seconds. Thereafter, exposure is performed according to a conventional method, followed by post-exposure baking (PEB) and development to obtain a resist pattern. The thickness of the resist top layer film is not particularly limited, but is preferably 30 to 1,000 nm, and more preferably 50 to 500 nm.

[0212] Examples of exposure light include high energy rays with a wavelength of 300 nm or less, specifically excimer lasers with wavelengths of 248 nm, 193 nm, and 157 nm, soft X-rays with wavelengths of 3 to 20 nm, electron beams, and X-rays.

[0213] When the above method is used as a method for forming a circuit pattern on the resist upper layer film, a fine pattern can be formed on the workpiece with higher precision.

[0214] The method for forming a pattern on the resist upper layer film is preferably photolithography with a wavelength of 5 nm or more and 300 nm or less, direct writing with an electron beam, nanoimprinting, or a combination thereof.

[0215] In addition, the development method in the pattern formation method is preferably alkaline development or organic solvent development. Specifically, in the pattern formation method, exposure and development are performed to form a circuit pattern on the resist upper layer film, and the development is preferably alkaline development or organic solvent development.

[0216] When alkaline development or development using an organic solvent is used as the development method, a fine pattern can be formed on the workpiece with higher precision.

[0217] (Metal oxide film formation method) The present invention provides a method for forming a filling film that functions as a resist underlayer film of a multilayer resist film used in lithography or a planarizing film (organic planar film) for semiconductor manufacturing, using the above-mentioned metal oxide film-forming composition.

[0218] Specifically, the present invention provides a method for forming a metal oxide film that functions as a flat film used in the manufacturing process of a semiconductor device, in which the above-mentioned metal oxide film-forming composition is applied to a substrate to be processed, and the substrate is then heat-treated at a temperature of 100°C or higher and 600°C or lower for 10 to 600 seconds to form a hardened film.

[0219] The present invention also provides a method for forming a metal oxide film that functions as a flat film used in the manufacturing process of a semiconductor device, in which the above-mentioned metal oxide film-forming composition is applied to a substrate to be processed, and the substrate is then heat-treated in an atmosphere with an oxygen concentration of 1% by volume or more and 21% by volume or less to form a hardened film.

[0220] The present invention also provides a method for forming a metal oxide film that functions as a flat film used in the manufacturing process of a semiconductor device, in which the above-mentioned metal oxide film-forming composition is applied to a substrate to be processed, and the substrate is then heat-treated in an atmosphere with an oxygen concentration of less than 1% by volume to form a hardened film.

[0221] This method is useful because it promotes the crosslinking reaction of the composition for forming a metal oxide film during the formation of the metal oxide film without causing deterioration of the substrate to be processed, even when the substrate to be processed contains a material that is unstable when heated in an oxygen atmosphere, and it can more effectively suppress mixing with the overlying film.

[0222] In the method for forming a metal oxide film using the metal oxide film-forming composition of the present invention, the metal oxide film-forming composition is coated onto a substrate to be processed by spin coating or the like. By using spin coating or the like, excellent embedding properties can be obtained. After spin coating, the solvent is evaporated, and baking (heat treatment) is performed to promote crosslinking reactions and prevent mixing with the resist upper layer film or resist intermediate film. Baking is preferably performed at 100°C or higher and 600°C or lower for 10 to 600 seconds, more preferably 200°C or higher and 500°C or lower for 10 to 300 seconds. Considering the effects on device damage and wafer deformation, the upper limit of the heating temperature in lithography wafer processing is preferably 600°C or lower, more preferably 500°C or lower.

[0223] In addition, in a method for forming a metal oxide film using the metal oxide film-forming composition of the present invention, the metal oxide film can also be formed by coating the metal oxide film-forming composition of the present invention on a substrate to be processed by a spin coating method or the like as described above, and baking and curing the metal oxide film-forming composition in an atmosphere with an oxygen concentration of 0.1 vol % or more and 21 vol % or less.

[0224] By baking the metal oxide film-forming composition of the present invention in such an oxygen atmosphere, a sufficiently cured film can be obtained. Although air can be used as the atmosphere during baking, it is preferable to seal in an inert gas such as N2, Ar, or He to reduce the oxygen content and prevent oxidation of the metal oxide film. To prevent oxidation, the oxygen concentration must be controlled, preferably to 1000 ppm or less, more preferably 100 ppm or less (volume basis). Preventing oxidation of the metal oxide film during baking is preferable because it prevents increased absorption and reduced etching resistance. [Example]

[0225] The present invention will be described in more detail below with reference to Synthesis Examples, Examples, and Comparative Examples, but is not limited thereto. Regarding the molecular weight and dispersity, the weight average molecular weight (Mw) and number average molecular weight (Mn) in terms of polystyrene were determined by gel permeation chromatography (GPC) using tetrahydrofuran as an eluent, and the dispersity (Mw / Mn) was calculated.

[0226] Resins (B-1) to (B-6) for resist underlayer film materials were synthesized using the resin raw materials (b-1) to (b-6) shown below, and (B-7) to (B-8) were synthesized using resin (B-4). Comparative resin (R-1) was synthesized using resin (B-3), comparative resin (R-3) was synthesized using the comparative resin raw material (G-1), and comparative resin (R-4) was synthesized using the comparative resin raw material (G-2), and the reaction rate was controlled using modifying agents (c-1) to (c-2).

[0227] Resin raw material: [ka]

[0228] Resins used as intermediates: [ka]

[0229] Comparative resin raw materials: [ka]

[0230] Modifiers: [ka]

[0231] The resins (B-1) to (B-6) shown above were synthesized as follows.

[0232] (Synthesis Example 1) Synthesis of Resin (B-1) [ka] Under a nitrogen atmosphere, 188.2 g of resin raw material (b-1), 113.6 g of resin raw material (b-5), 9.0 g of oxalic acid, and 100 g of dioxane were added and reacted for 24 hours at an internal temperature of 100°C. After the reaction was completed, the mixture was cooled to room temperature, 2,000 ml of MIBK was added, and the mixture was washed six times with 500 ml of pure water. The organic layer was recovered, and the pressure was reduced to 2 mmHg at an internal temperature of 150°C to remove water, solvent, and residual monomers under reduced pressure, yielding resin (B-1). The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the following results were obtained. (B-1): Mw = 6,500, Mw / Mn = 2.87

[0233] (Synthesis Example 2) Synthesis of Resin (B-2) [ka] Under a nitrogen atmosphere, 94.1 g of resin raw material (b-1), 89.8 g of resin raw material (b-6), and 400 g of dichloromethane were added and the mixture was kept at an internal temperature of 30°C to form a uniform dispersion. Then, 211 g of methanesulfonic acid was added over 2 hours, and the reaction was carried out at an internal temperature of 30°C for 24 hours. After the reaction was completed, the mixture was cooled to room temperature, 2,000 ml of MIBK was added, and the mixture was washed six times with 500 ml of pure water. The organic layer was evaporated to dryness under reduced pressure. 300 g of THF was added to the residue to form a uniform solution, which was then crystallized in 2,000 g of hexane. The precipitated crystals were separated by filtration, washed twice with 500 g of hexane, and then recovered. The recovered crystals were dried in vacuo at 70°C to obtain resin (B-2). The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the following results were obtained. (B-2): Mw = 6,300, Mw / Mn = 3.11

[0234] (Synthesis Example 3) Synthesis of Resin (B-3) [ka] Under a nitrogen atmosphere, 216.3 g of resin raw material (b-2), 113.6 g of resin raw material (b-5), 10.8 g of oxalic acid, and 200 g of dioxane were added and reacted for 24 hours at an internal temperature of 100°C. After the reaction was completed, the mixture was cooled to room temperature, 2,000 ml of MIBK was added, and the mixture was washed six times with 500 ml of pure water. The organic layer was recovered, and the pressure was reduced to 2 mmHg at an internal temperature of 150°C to remove water, solvent, and residual monomers under reduced pressure, yielding resin (B-3). The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the following results were obtained. (B-3): Mw = 7,000, Mw / Mn = 3.50

[0235] (Synthesis Example 4) Synthesis of Resin (B-4) [ka] Under a nitrogen atmosphere, 108.2 g of resin raw material (b-2), 89.8 g of resin raw material (b-6), and 400 g of dichloromethane were added and the mixture was kept at an internal temperature of 30°C to form a uniform dispersion. Then, 211 g of methanesulfonic acid was added over 2 hours, and the reaction was carried out at an internal temperature of 30°C for 24 hours. After the reaction was completed, the mixture was cooled to room temperature, 2,000 ml of MIBK was added, and the mixture was washed six times with 500 ml of pure water. The organic layer was evaporated to dryness under reduced pressure. 300 g of THF was added to the residue to form a uniform solution, which was then crystallized in 2,000 g of hexane. The precipitated crystals were separated by filtration, washed twice with 500 g of hexane, and then recovered. The recovered crystals were dried in vacuo at 70°C to obtain resin (B-4). The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the following results were obtained. (B-4): Mw = 6,900, Mw / Mn = 3.34

[0236] (Synthesis Example 5) Synthesis of Resin (B-5) [ka] Under a nitrogen atmosphere, 144.2 g of resin raw material (b-3), 56.8 g of resin raw material (b-5), and 300 g of propylene glycol monomethyl ether (PGME) were mixed and homogenized at an internal temperature of 100°C. A premixed mixture of 7.1 g of paratoluenesulfonic acid monohydrate and 7.1 g of PGME was then slowly added dropwise, and the reaction was carried out at an internal temperature of 100°C for 8 hours. After the reaction was completed, the mixture was cooled to room temperature, 2,000 ml of MIBK was added, and the mixture was washed six times with 500 ml of purified water. The organic layer was evaporated to dryness under reduced pressure. 300 g of THF was added to the residue to form a homogenous solution, which was then crystallized in 2,000 g of hexane. The precipitated crystals were separated by filtration, washed twice with 500 g of hexane, and then recovered. The recovered crystals were dried in vacuo at 70°C to obtain resin (B-5). The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the following results were obtained. (B-5): Mw = 2,900, Mw / Mn = 2.76

[0237] (Synthesis Example 6) Synthesis of Resin (B-6) [ka] Under a nitrogen atmosphere, 160.2 g of resin raw material (b-4), 56.8 g of resin raw material (b-5), and 300 g of propylene glycol monomethyl ether (PGME) were mixed and homogenized at an internal temperature of 100°C. A premixed mixture of 8.0 g of paratoluenesulfonic acid monohydrate and 8.0 g of PGME was then slowly added dropwise, and the reaction was carried out at an internal temperature of 80°C for 8 hours. After the reaction was completed, the mixture was cooled to room temperature, 2,000 ml of MIBK was added, and the mixture was washed six times with 500 ml of purified water. The organic layer was evaporated to dryness under reduced pressure. 300 g of THF was added to the residue to form a homogenous solution, which was then crystallized in 2,000 g of hexane. The precipitated crystals were separated by filtration, washed twice with 500 g of hexane, and then recovered. The recovered crystals were dried in vacuo at 70°C to obtain resin (B-6). The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the following results were obtained. (B-6): Mw = 3,300, Mw / Mn = 2.54

[0238] (Synthesis Example 7) Synthesis of Resin (B-7) [ka] Under a nitrogen atmosphere, 20.0 g of resin (B-4), 15.8 g of potassium carbonate, and 100 g of DMF were added and a uniform dispersion was obtained at an internal temperature of 50°C. 7.9 g of modifying agent (c-1) 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 the separated aqueous layer was then removed. The organic layer was further washed six times with 100 g of 3% aqueous nitric acid solution and 100 g of pure water, and then the organic layer was evaporated to dryness under reduced pressure to obtain resin (B-7). The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the following results were obtained. (B-7): Mw = 7,700, Mw / Mn = 3.35

[0239] (Synthesis Example 8) Synthesis of Resin (B-8) [ka] Under a nitrogen atmosphere, 20.0 g of resin (B-4), 15.8 g of potassium carbonate, and 100 g of DMF were added and a uniform dispersion was obtained at an internal temperature of 50°C. 8.1 g of modifying agent (c-2) 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 the separated aqueous layer was then removed. The organic layer was further washed six times with 100 g of 3% aqueous nitric acid solution and 100 g of pure water, and then the organic layer was evaporated to dryness under reduced pressure to obtain resin (B-8). The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the following results were obtained. (B-8): Mw = 7,500, Mw / Mn = 3.37

[0240] (Synthesis Example 9) Synthesis of resin (R-1) [ka] Under a nitrogen atmosphere, 20.0 g of resin (B-3), 34.5 g of potassium carbonate, and 100 g of DMF were added and a uniform dispersion was obtained at an internal temperature of 50°C. 23.8 g of modifying agent (c-1) 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 the separated aqueous layer was then removed. The organic layer was further washed six times with 100 g of 3% aqueous nitric acid solution and 100 g of pure water, and then the organic layer was evaporated to dryness under reduced pressure to obtain resin (R-1). The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the following results were obtained. (R-1): Mw = 9,400, Mw / Mn = 3.59

[0241] (Synthesis Example 10) Synthesis of resin (R-2) [ka] 23.3 g of PGMEA was heated and stirred at 80°C under a nitrogen atmosphere. To this mixture, a mixture of 25.8 g of glycidyl methacrylate, 12.0 g of 2-phenoxyethyl acrylate, 12.9 g of tricyclodecanyl acrylate, and 46.7 g of PGMEA, and a mixture of 4.45 g of dimethyl 2,2-azobis(2-methylpropionate) and 46.7 g of PGMEA were added simultaneously and separately over 2 hours. After heating and stirring for an additional 16 hours, the mixture was cooled to 60°C, 200 g of heptane was added, and the mixture was cooled to room temperature and allowed to stand for 2 hours. The upper layer was separated and removed, and 100 g of PGMEA was added. The heptane was then distilled off under reduced pressure to obtain a PGMEA solution of the desired polymer (R-2). The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the following results were obtained. (R-2): Mw = 7700, Mw / Mn = 1.90

[0242] (Synthesis Example 11) Synthesis of resin (R-3) [ka] 10.0 g of compound (G-1) from the raw material group and 30 ml of 1-methoxy-2-propanol were weighed into a 200 ml three-neck flask and dissolved in a 75 °C oil bath under a nitrogen atmosphere with stirring. 0.25 g of paraformaldehyde was added, and 2.5 g of a 20% by mass solution of p-toluenesulfonic acid monohydrate in 1-methoxy-2-propanol was added dropwise. After the addition was complete, the temperature of the oil bath was raised to 85 °C, and the reaction was carried out for 4 hours. After cooling to room temperature, the mixture was diluted with 100 ml of methyl isobutyl ketone, and the insoluble matter was filtered off and transferred to a separatory funnel. The mixture was then washed with 30 ml of ultrapure water eight times. The organic layer was concentrated under reduced pressure to recover the polymer, which was then dried under reduced pressure to obtain the polymer for use as a flow promoter (R-3). The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the following results were obtained. (R-3): Mw = 4920, Mw / Mn = 1.75

[0243] (Synthesis Example 12) Synthesis of resin (R-4) [ka] Under a nitrogen atmosphere, 42.8 g of compound (G-2) from the raw material group, 15.7 g of potassium carbonate, and 150 g of DMF were added to form a uniform dispersion at an internal temperature of 50°C. 28.2 g of modifying agent (c-1) 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 the separated aqueous layer was then removed. The organic layer was further washed six times with 100 g of 3% aqueous nitric acid solution and 100 g of pure water, and then evaporated to dryness under reduced pressure to obtain compound (R-4) for use as a flow promoter. The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the following results were obtained. (R-4): Mw = 560, Mw / Mn = 1.01

[0244] (Synthesis Example 13) Synthesis of resin (R-5) [ka] 90 g of 2-phenylphenol, 15.6 g of 9-anthracenemethanol, and 9.8 g of divinylbenzene were dissolved in 25 g of cyclopentyl methyl ether and 90 g of diethylene glycol dimethyl ether and stirred at room temperature for 5 minutes under a nitrogen atmosphere. 1.14 g of trifluoromethanesulfonic acid was then added and stirred for an additional 5 minutes. The mixture was then stirred at 140°C for 3 hours. The reaction mixture was cooled, diluted with 250 ml of cyclopentyl methyl ether, transferred to a separatory funnel, washed with ultrapure water, and the polymer was precipitated with hexane. The precipitated polymer was filtered, collected, and dried under reduced pressure to obtain the desired polymer (R-5). The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the following results were obtained. (R-5): Mw=1960, Mw / Mn=1.45.

[0245] (Synthesis Example 14) Synthesis of resin (R-6) [ka] A mixture of 5.63 g of 9,9-bis(6-glycidyloxy-2-naphthyl)fluorene, 3.76 g of 6-hydroxy-2-naphthoic acid, 0.1 g of benzyltriethylammonium chloride, and 40 g of N-methylpyrrolidone was stirred at 120°C for 20 hours. After cooling, 2.76 g of potassium carbonate and 2.62 g of propargyl bromide were added and stirred at 60°C for 20 hours. The mixture was diluted with ethyl acetate, washed three times with water, and concentrated under reduced pressure to synthesize the intermediate. 40 g of N-methylpyrrolidone and 1.99 g of acrylic acid chloride were added to the resulting intermediate and stirred. 2.23 g of triethylamine was added dropwise to the mixture and stirred for 20 hours. The mixture was diluted with ethyl acetate, washed three times with water, concentrated under reduced pressure, and purified by silica gel column chromatography to obtain 8.98 g of compound (R-6). The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the following results were obtained. (R-6): Mw=1613, Mw / Mn=1.10.

[0246] Tables 1 to 3 show the structure, weight average molecular weight (Mw) and dispersity (Mw / Mn) of the obtained resin for use as a flowability promoter.

[0247] [Table 1]

[0248] [Table 2] [Table 3]

[0249] [(A) Metal oxide nanoparticles] The (A) metal oxide nanoparticles (A-1) used in the composition for forming a metal oxide film were ZrO2 nanoparticles (5 nm core, 915505, Sigma-Aldrich Corp).

[0250] [(A) Metal compound for comparison] The comparative metal compound (A-2) used in the comparative metal oxide film-forming composition was synthesized by the following procedure with reference to [Synthesis Example A-II] of Japanese Patent Publication No. 5756134. A mixture of 2.7 g of pure water and 50 g of isopropyl alcohol was added dropwise to a mixture of 32.7 g of zirconium tetraisopropoxide, 50 g of isopropyl alcohol, and 50 g of acetylacetone. After the addition, the mixture was stirred for 2 hours to allow hydrolysis and condensation, and then refluxed for another 2 hours. 200 g of PGMEA was added, and the mixture was concentrated under reduced pressure to obtain 250 g of a PGMEA solution of zirconium-containing compound (A-2). (A-2) is a hydrolysis condensation product of a metal alkoxide, and is a polymer with a polymetalloxane main chain skeleton, so it is structurally distinct from metal oxide nanoparticles, and for this reason, it is used as a comparative example.

[0251] [(C) Dispersion stabilizer] The compounds are listed in Tables 4 and 5. C-1: A compound represented by the following formula (C-1): C-2: A compound represented by the following formula (C-2): C-3: A compound represented by the following formula (C-3): C-4: A compound represented by the following formula (C-4): C-5: A compound represented by the following formula (C-5): RC-1: A compound represented by the following formula (RC-1) RC-2: A compound represented by the following formula (RC-2) RC-3: A compound represented by the following formula (RC-3)

[0252] [Table 4] [Table 5]

[0253] [(E) Crosslinking agent] The crosslinking agents (E) used in the metal oxide film-forming compositions are shown below. [ka]

[0254] [(F) Thermal acid generator] The thermal acid generators (F) used in the metal oxide film-forming compositions are shown below. [ka]

[0255] [Metal oxide film forming composition UDL-1] Metal oxide nanoparticles (A-1) and flow promoter (B-1) were dissolved in propylene glycol monomethyl ether acetate (PGMEA) containing 0.5 mass% of surfactant FC-4430 (Sumitomo 3M Limited) in the proportions shown in Table 6, and the solution was filtered through a 0.02 μm membrane filter to prepare a metal oxide film-forming composition (UDL-1).

[0256] [Metal oxide film-forming compositions UDL-2 to 14 and comparative examples UDL-1 to 14] Each chemical solution was prepared in the same manner as UDL-1, except that the type and content of each component were as shown in Tables 6 and 7. In Tables 6 and 7, "-" indicates that the corresponding component was not used. Pentaerythritol triacrylate was used as additive (G'-1).

[0257] [Table 6] [Table 7]

[0258] [Crack Resistance Evaluation (Examples 1-1 to 1-14, Comparative Examples 1-1 to 1-18)] The above metal oxide film-forming compositions (UDL-1 to 14 and Comparative UDL-1 to 18) were applied to silicon substrates and baked in air at 350°C for 60 seconds to form coating films, and the film thickness a was measured. PGMEA solvent was dispensed onto the coating, left for 30 seconds, spin-dried, and baked at 100°C for 60 seconds to evaporate the PGMEA solvent. The film thickness b was measured and the difference in film thickness before and after PGMEA treatment was determined to evaluate solvent resistance. In addition, the presence or absence of cracks in each coating film was evaluated before and after dispensing the PGMEA solvent. Films with no visible cracks were rated "○" (good), and films with visible cracks were rated "×" (poor). The results are shown in Tables 8 and 9.

[0259] [Table 8] [Table 9]

[0260] As shown in Tables 8 and 9, in Examples 1-1 to 1-14, which used the metal oxide film-forming compositions (UDL-1 to 14) of the present invention, good film-forming properties were obtained, with almost no film loss due to solvent treatment, and films with good solvent resistance were obtained. Example UDL-14 contained 25% flowability promoter, and Example UDL-12 contained a high concentration of metal oxide nanoparticles at 38%, but both samples were able to form metal oxide films with a thickness of 2 μm without cracking. In other words, when the content of the (B) flowability promoter of the present invention is 9% or more, and preferably when the weight ratio of the (A) metal oxide nanoparticles to the (B) flowability promoter is 80 / 20 to 10 / 90, a thick metal oxide film can be formed with excellent coatability. On the other hand, cracks were observed in comparative UDL-3 to 4, comparative UDL-11 to 14, which used R-3 and R-4, which have a cardo structure as flow promoters, and comparative UDL-5, which used R-5, a high-carbon polymer.

[0261] Cracking was also observed in Comparative UDL-7, in which the metal oxide nanoparticles of UDL-1 were replaced with Polymer A-2, a hydrolysis condensate of metal alkoxide with a polymetalloxane main chain skeleton. It is believed that metal compounds with polymer structures such as A-2 have low heat resistance and large thermal shrinkage during baking, which is why cracking occurred. Meanwhile, cracking was also observed in Comparative UDL-8, in which metal oxide nanoparticles A-1 were used alone. This suggests that the addition of a flow promoter is necessary to form a thick metal oxide film with excellent coatability. It is essential that this flow promoter be a resin having a structural unit represented by the general formula (1) of the present invention, and that it does not contain a compound / polymer with a cardo structure or a high-carbon polymer.

[0262] [Storage Stability Evaluation (Examples 2-1 to 2-14, Comparative Examples 2-1 to 2-9)] The metal oxide films of Examples UDL-1 to 14, Comparative UDL-1 to 2, Comparative UDL-6, Comparative UDL-9 to 10, and Comparative UDL-15 to 18, which showed good coating properties in the crack resistance evaluation, were counted for the number of 100 nm-sized defects using a defect inspection device (SP2) manufactured by KLA-Tencor Corporation. Furthermore, the liquid-borne particles of the metal oxide film-forming compositions were measured using a liquid-borne particle counter (KS-41) manufactured by Kyushu Rion Co., Ltd. The number of particles 0.15 μm or larger contained in 1 mL was counted five times, and the average value was used as the measured value. Furthermore, after storing the compositions for forming metal oxide films for six months in an environment at 10°C, the number of defects and the number of liquid-borne particles were counted in the same manner as above. The results are shown in Table 10.

[0263] [Table 10]

[0264] As shown in Table 10, Examples 2-1 to 2-14, which used compositions for forming metal oxide films (UDL-1 to 14) of the present invention, showed low particle counts in the liquid and low post-application defects after six months of storage, demonstrating excellent storage stability. On the other hand, Comparative Example 2-6, which used Comparative UDL-15, which was UDL-13 without the (C) dispersion stabilizer, and Comparative Examples 2-7 to 2-9, which used RC-1 to 3 as the (C) dispersion stabilizer, showed an increase in particle counts and post-application defects after six months. This is presumably due to poor dispersion stability of the metal oxide nanoparticles in the compositions, which led to aggregation of the nanoparticles during long-term storage.

[0265] [Etching Resistance Evaluation (Examples 3-1 to 3-11, Comparative Examples 3-1 to 3-5)] The metal oxide film-forming compositions of Examples UDL-1 to 11 and Comparative UDL-1 to 2, Comparative UDL-6, and Comparative UDL-9 to 10, which had good coatability in the crack resistance evaluation, were coated on a silicon substrate and baked in air at 350°C for 60 seconds to form a 1000 nm coated film, and the film thickness a was measured. Next, etching was performed with CF4 gas and O2 gas for 1 minute each under the following conditions using a Telius etching system manufactured by Tokyo Electron, and the film thickness b was measured.

[0266] The film thickness etched in one minute with CF4 gas (film thickness b - film thickness a) was calculated as the etching resistance to CF4 gas, and when the difference in film thickness between b and a was less than 60 nm, it was rated as "A" (very good), when it was 60 nm or more but less than 70 nm, it was rated as "B" (good), and when it was 70 nm or more, it was rated as "C" (poor).

[0267] The film thickness etched by O2 gas in one minute (film thickness d - film thickness c) was calculated as the etching resistance to O2 gas, and when the difference in film thickness between c and d was less than 75 nm, it was rated as "A" (very good), when it was 75 nm or more but less than 85 nm, it was rated as "B" (good), and when it was 85 nm or more, it was rated as "C" (poor).

[0268] The results are shown in Table 11.

[0269] Dry etching conditions with CF4 gas Chamber pressure: 100mT RF power (top): 500W RF power (bottom): 400W CF4 gas flow rate: 300sccm Time: 60sec

[0270] Dry etching conditions with O2 gas Chamber pressure: 15mT RF power (top): 300W RF power (bottom): 50W O2 gas flow rate: 30sccm N2 gas flow rate: 270sccm Time: 60sec

[0271] [Table 11]

[0272] As shown in Table 11, when comparing compositions containing (A) 6% metal oxide nanoparticles and (B) 15% flowability promoter, it was confirmed that Examples 3-1 to 3-10, which used the metal oxide film-forming composition of the present invention, had superior etching resistance to CF4 gas and O2 gas compared to Comparative Examples 3-2 to 3-3. Therefore, because they exhibit excellent etching resistance to both CF4 gas and O2 gas, it is suggested that they are useful as a mask when etching Si-based substrates with CF4-based gas, and in a reversal process in which an organic resist underlayer film pattern is removed with O2-based gas and the pattern is reversed to a metal oxide film.

[0273] A composition consisting only of a flow promoter without metal oxide nanoparticles, such as that in Comparative Example 3-4, cannot form a film with excellent dry etching resistance. On the other hand, even compositions containing metal oxide nanoparticles exhibit variable dry etching resistance depending on the selected flow promoter. Comparative Example 3-2 exhibits poor dry etching resistance due to the use of an acrylic resin as the flow promoter. On the other hand, the flow promoter R-6 used in Comparative Example 3-3 is a compound with a cardo structure that exhibits excellent dry etching resistance. However, because it contains a highly flexible acrylate as a crosslinking group, it is unable to form a dense cured film, presumably resulting in poor dry etching resistance. Comparative Example 3-5 uses pentaerythritol triacrylate, which is commonly used as a UV-curable binder, instead of a flow promoter. However, like Comparative Examples 3-2 and 3-3, it is unsuitable for forming a film with excellent dry etching resistance.

[0274] In other words, in order to realize a composition capable of forming a thick film having excellent dry etching resistance and crack resistance, it is important to use a resin having a structural unit represented by the above general formula (1) as a flow promoter.

[0275] [Evaluation of Filling Characteristics (Examples 4-1 to 4-14, Comparative Examples 4-1 to 4-18)] The metal oxide film-forming compositions (UDL-1 to 14 and Comparative Examples UDL-1 to 18) were applied to a SiO2 wafer substrate with a dense hole pattern (hole diameter 0.16 μm, hole depth 2.0 μm, center-to-center distance between adjacent two holes 0.40 μm) and heated on a hot plate at 350 °C for 60 seconds to form a metal oxide film. Similarly, the substrate was heated in air at 350 °C for 60 seconds and then baked at 450 °C for 60 seconds in a nitrogen stream with an oxygen concentration controlled to 0.2% or less. The substrate used was a base substrate 17 (SiO2 wafer substrate) with a dense hole pattern as shown in Figure 4(AA) (overhead view) and (AB) (cross-sectional view). The cross-sectional shape of each wafer substrate was observed using a Hitachi, Ltd. electron microscope (S-4700) to confirm the presence of voids (air gaps) within the metal oxide film filling the holes. The results are shown in Tables 12 and 13. When a metal oxide film-forming composition with poor filling properties was used, voids occurred within the metal oxide film that filled the hole in this evaluation. When a metal oxide film-forming composition with good filling properties was used, metal oxide film 18 was filled into the hole without voids or peeling, as shown in Figure 4(AC).

[0276] [Table 12] [Table 13]

[0277] As shown in Tables 12 and 13, in Examples 4-1 to 4-14, which used the metal oxide film-forming compositions of the present invention (UDL-1 to 14), it was possible to fill a high-aspect ratio dense hole pattern without generating voids, confirming that they had good filling properties. On the other hand, in Comparative Example 4-8, which used Comparative UDL-8 containing metal oxide nanoparticles alone, significant voids were observed due to insufficient fluidity.

[0278] A small number of microvoids were observed in Comparative Example 4-15, which did not use a dispersion stabilizer. Furthermore, in Comparative Examples 4-16 to 4-18, which used dispersion stabilizers with weight loss rates of more than 30% from 30°C to 190°C, microvoids were also observed, possibly due to the fluidity promoter's ineffectiveness in enhancing the thermal fluidity of the flowability promoter. In other words, to achieve a metal oxide film-forming composition with excellent high-aspect-ratio pattern embedding capabilities, it is preferable to add not only a flowability promoter but also a dispersion stabilizer that further improves the thermal fluidity of the resin used for the thermal fluidity promoter. The dispersion stabilizer used in the present invention not only enhances the dispersion stability of metal oxide nanoparticles in the composition, but also improves the thermal fluidity of the composition.

[0279] As in Examples 4-7 to 4-8, by appropriately controlling the hydroxyl group modification rate in the flow promoter, as in B-7 or B-8, it is possible to achieve both good filling properties and high substrate adhesion. In Example 4-10, the same effect as in Example 4-7 was obtained by combining and adjusting Resin R-1 having a propargyl oxo group and Resin B-1 having a hydroxyl group. On the other hand, in Comparative Examples 4-1, 4-4, and 4-6, no voids were observed inside the holes, but deterioration of adhesion to the substrate was observed due to an insufficient amount of hydroxyl groups in the flow promoter. It can be said that it is preferable to contain a certain amount of hydroxyl groups in order to achieve adhesion to the substrate.

[0280] In Comparative UDL-7, in which the metal oxide nanoparticles in UDL-1 were replaced with polymer A-2, a hydrolysis condensation product of metal alkoxide with a polymetalloxane main chain skeleton, the low heat resistance of A-2 led to significant thermal shrinkage during baking, resulting in incomplete filling of the substrate and significant voids. In Comparative Example 4-2, voids were observed at 350°C bake due to the insufficient heat resistance of R-2 used as a flow promoter. Voids were also observed in Comparative Example 4-10 due to the insufficient heat resistance of pentaerythritol triacrylate used instead of a flow promoter. Meanwhile, in Comparative Examples 4-3 and 4-5, R-3 and R-5, which have excellent heat resistance, were used as flow promoters, but their poor fluidity likely led to voids during filling of high aspect ratio patterns. In Comparative Example 4-13, the fluidity promoter content was increased from 15% to 20% compared to Comparative Example 4-3 to increase the thickness of the film, but no improvement in voids was observed. Voids were also observed in Comparative Example 4-14, in which the weight ratio of fluidity promoter to metal oxide nanoparticles was increased to 90 / 10. Voids were also observed in Comparative Examples 4-11 and 4-12, which used Comparative UDL-11 and 12, which used R-3.

[0281] In other words, the presence of a flow promoter is essential to form a metal oxide with excellent embedding properties that can fill high aspect ratio patterns well. However, polymers with rigid cardo structures such as R-3 and high-carbon polymers such as R-5 are unsuitable due to their poor flowability, and it can be said that it is important to use a resin having a structural unit represented by general formula (1) of the present invention.

[0282] [Pattern Forming Method (Examples 5-1 to 5-11, Comparative Examples 5-1 to 5-5)] The metal oxide film-forming compositions of Examples UDL-1 to 11, Comparative UDL-1 to 2, Comparative UDL-6, and Comparative UDL-9 to 10, which showed good coatability in the crack resistance evaluation, were each applied to a silicon wafer substrate with a 1000 nm SiO2 film having a trench pattern (trench width 10 μm, trench depth 0.50 μm) and baked at 350 °C for 60 seconds in air to form a 1000 nm thick metal-containing film. A silicon-containing resist intermediate layer material (SOG-1) was applied thereon and baked at 220 °C for 60 seconds to form a 40 nm thick resist intermediate layer, and an ArF single-layer resist of the resist top layer material was applied thereon and baked at 105 °C for 60 seconds to form a 100 nm thick photoresist film.

[0283] The silicon-containing resist intermediate layer material (SOG-1) was prepared by dissolving the ArF silicon-containing intermediate film polymer (SiP1) and the crosslinking catalyst (CAT1) in an organic solvent containing 0.1 mass% of FC-4430 (manufactured by Sumitomo 3M) in the proportions shown in Table 14, and filtering the solution through a fluororesin filter with a pore size of 0.1 μm.

[0284] [Table 14]

[0285] The structural formulae of the ArF silicon-containing intermediate film polymer (SiP1) and crosslinking catalyst (CAT1) used are shown below. [ka]

[0286] The resist top layer material (ArF single-layer resist) was prepared by dissolving a polymer (RP1), an acid generator (PAG1), and a basic compound (Amine1) in the proportions shown in Table 15 in a solvent containing 0.1 mass% of surfactant FC-4430 (Sumitomo 3M Limited), and filtering the solution through a 0.1 μm fluororesin filter.

[0287] [Table 15]

[0288] The polymer (RP1), acid generator (PAG1), and basic compound (Amine1) used in the resist top layer material (ArF single layer resist) are shown below. [ka]

[0289] The resist was then exposed using an ArF immersion exposure system (Nikon Corporation; NSR-S610C, NA 1.30, σ 0.92 / 0.74, 35-degree cross pole, 6% halftone phase shift mask), baked at 100°C for 60 seconds (PEB), and developed in a 2.38% by mass aqueous solution of tetramethylammonium hydroxide (TMAH) for 30 seconds to obtain a 100 nm 1:1 positive line and space pattern (resist pattern).

[0290] Next, the silicon-containing resist intermediate layer material (SOG-1) was etched using the resist pattern as a mask by dry etching using a ULVAC etching system CE-300I to form a hard mask pattern, and the metal oxide film was etched using the resulting SOG-1 pattern as a mask to form a metal oxide film pattern, and the SiO2 film was etched using the resulting metal oxide film pattern as a mask. The etching conditions are as follows:

[0291] Transfer conditions of resist pattern to silicon atom-containing resist intermediate layer material (SOG-1). Dry etching conditions with CF4 gas Pressure: 1Pa Antenna RF power: 100W Bias RF power: 15W CF4 gas flow rate: 15sccm Time: 60sec

[0292] Conditions for transferring a silicon-containing resist intermediate layer material (SOG-1) pattern to a metal oxide film. Dry etching conditions using Cl2 gas Pressure: 1Pa Antenna RF power: 320W Bias RF power: 30W Cl2 gas flow rate: 25sccm Time: 1200sec

[0293] Conditions for transferring metal oxide film patterns to SiO2 films. Dry etching conditions with CF4 gas Pressure: 1Pa Antenna RF power: 100W Bias RF power: 15W CF4 gas flow rate: 15sccm Time: 450 seconds

[0294] The cross section of the pattern was observed using an electron microscope (S-4700) manufactured by Hitachi, Ltd. The results are shown in Table 16.

[0295] [Table 16]

[0296] As shown in Table 16, in Examples 5-1 to 5-11 in which the metal oxide film-forming compositions (UDL-1 to 11) of the present invention were used, the resist upper layer film pattern was successfully transferred to the substrate in all cases, and a line and space pattern with a depth of 1 μm was successfully formed. In other words, it was confirmed that the metal oxide film-forming composition of the present invention is suitable for use in microfabrication by the multilayer resist method.

[0297] On the other hand, Comparative Example 5-1, which used Comparative UDL-1, which was confirmed to have insufficient adhesion to the substrate in the embedding characteristic evaluation, experienced pattern collapse during pattern processing, and ultimately failed to obtain a good pattern. Also, Comparative Examples 5-2 to 5-5, which used Comparative UDL-2, 6, 9, and 10, which were confirmed to have insufficient performance in the dry etching resistance evaluation, experienced distortion of the pattern shape during pattern processing, and ultimately failed to obtain a good pattern.

[0298] [SOC Pattern Inversion Method (Examples 6-1 to 6-11, Comparative Examples 6-1 to 6-6)] A 2000nm thick SiO2 silicon wafer substrate was coated with a coating-type organic underlayer material (SOC-1) and baked at 350°C for 60 seconds to form a 1500nm thick underlayer. A silicon-containing resist middle layer material (SOG-1) was then coated on top and baked at 220°C for 60 seconds to form a 45nm thick middle layer. A single layer ArF resist top layer material was then coated on top and baked at 105°C for 60 seconds to form a 100nm thick photoresist film. An immersion protective film material (TC-1) was then coated on top of the photoresist film and baked at 90°C for 60 seconds to form a 50nm thick protective film.

[0299] The resist upper layer film material (ArF single layer resist) was the same as that used in the above pattern forming method (Example 5).

[0300] The coating-type organic underlayer film material (SOC-1) was prepared by dissolving the resist underlayer film polymer (SOP1) in an organic solvent containing 0.5 mass % of FC-4430 (manufactured by Sumitomo 3M Limited) in the proportions shown in Table 17 and filtering the solution through a fluororesin filter with a pore size of 0.2 μm.

[0301] [Table 17]

[0302] The structural formula of the resist underlayer film polymer (SOP1) used is shown in Table 18.

[0303] [Table 18]

[0304] The silicon-containing resist intermediate layer material (SOG-1) was prepared by dissolving the ArF silicon-containing intermediate film polymer (SiP1) and the crosslinking catalyst (CAT1) in an organic solvent containing 0.1 mass% of FC-4430 (manufactured by Sumitomo 3M) in the proportions shown in Table 19, and filtering the solution through a fluororesin filter with a pore size of 0.1 μm.

[0305] [Table 19]

[0306] The structural formulae of the ArF silicon-containing intermediate film polymer (SiP1) and crosslinking catalyst (CAT1) used are shown below. [ka]

[0307] The resist was then exposed using an ArF immersion exposure system (Nikon Corporation; NSR-S610C, NA 1.30, σ 0.92 / 0.74, 35-degree cross pole, 6% halftone phase shift mask), baked at 100°C for 60 seconds (PEB), and developed in a 2.38% by mass aqueous solution of tetramethylammonium hydroxide (TMAH) for 30 seconds to obtain a 100 nm 1:1 positive line and space pattern (resist pattern).

[0308] Next, using a Tokyo Electron Telius etching system, the silicon-containing resist intermediate layer material (SOG-1) was dry-etched using the resist pattern as a mask to form a hard mask pattern, and the resist underlayer film (SOC-1) was etched using the resulting hard mask pattern as a mask to form a SOC-1 film pattern. The etching conditions are as follows:

[0309] Transfer conditions of resist pattern to silicon atom-containing resist intermediate layer material (SOG-1). Chamber pressure: 50mT RF power (top): 500W RF power (bottom): 300W CF4 gas flow rate: 150sccm CHF3 gas flow rate: 50sccm Time: 20sec

[0310] Conditions for transferring the silicon atom-containing resist middle layer material (SOG-1) pattern to the resist underlayer film (SOC-1). Chamber pressure: 10mT RF power (top): 1,000W RF power (bottom): 300W CO2 gas flow rate: 150sccm CO gas flow rate: 50 sccm N2 gas flow rate: 50sccm H2 gas flow rate: 150sccm Time: 600sec

[0311] Next, the above-mentioned metal oxide film-forming compositions (UDL-1 to 11, Comparative UDL-1, 2, 6, 9, and 10) were applied to the obtained SOC-1 film pattern and baked in air at 350°C for 60 seconds to form a metal oxide film with a thickness of 1000 nm. The metal oxide film covering the SOC-1 film pattern was then etched to expose the top surface of the SOC-1 film pattern. The SOG-1 film remaining on the exposed SOC-1 film pattern surface was then removed by etching, and the exposed SOC-1 was then removed by etching to invert the above pattern onto the metal oxide film. The resulting metal oxide film pattern was used as a mask to etch the SiO2 film. As a comparative example, the SiO2 film was also etched using the SOC-1 film pattern as a mask without using the metal oxide film-forming composition (Comparative Example 6-6). The etching conditions were as follows:

[0312] Etching back the metal oxide film (exposing the SOC-1 film pattern). Pressure: 1Pa Antenna RF power: 320W Bias RF power: 30W Cl2 gas flow rate: 25sccm Time: 300sec

[0313] Removal of silicon-containing resist intermediate layer material (SOG-1) film from SOC-1 film pattern. Pressure: 1Pa Antenna RF power: 100W Bias RF power: 15W CF4 gas flow rate: 15sccm Time: 60sec

[0314] Removal of SOC-1 membrane pattern. Pressure: 1Pa Antenna RF power: 300W Bias RF power: 0W O2 gas flow rate: 25sccm Time: 500sec

[0315] Conditions for transferring metal oxide film patterns to SiO2 films. Pressure: 1Pa Antenna RF power: 100W Bias RF power: 15W CF4 gas flow rate: 15sccm Time:900sec

[0316] Comparative Example 6-6: Conditions for transferring the SOC-1 film pattern to the SiO2 film. Pressure: 1Pa Antenna RF power: 100W Bias RF power: 15W CF4 gas flow rate: 15sccm Time:900sec

[0317] The cross section of the pattern was observed using an electron microscope (S-4700) manufactured by Hitachi, Ltd. The results are shown in Table 20.

[0318] [Table 20]

[0319] As shown in Table 20, in Examples 6-1 to 6-11, in which the metal oxide film-forming compositions (UDL-1 to UDL-11) of the present invention were used, the SOC-1 film pattern was accurately reversed in all cases, and the reversed pattern was successfully transferred to the final substrate without pattern collapse. This confirms that the metal oxide film-forming compositions of the present invention are suitable for use in microfabrication using a tone-reversal etching method in a multilayer resist process. On the other hand, in Comparative Example 6-6, in which the SOC-1 film pattern was directly transferred to an SiO2 film, pattern distortion was observed due to insufficient etching resistance of the SOC-1 film. Furthermore, in Comparative Example 6-1, in which insufficient adhesion to the substrate was confirmed in the embedding characteristic evaluation, pattern collapse occurred during pattern processing, and ultimately, a satisfactory reversed pattern could not be obtained. On the other hand, in Comparative Examples 6-2 to 6-5, in which insufficient performance was confirmed in the dry etching resistance evaluation, pattern formation was presumably not confirmed due to insufficient etching selectivity relative to the SOC-1 film.

[0320] From the above, it has become clear that the metal oxide film-forming composition of the present invention not only has excellent storage stability, but also enables the formation of thick films with excellent crack resistance, and has both high embedding properties and dry etching resistance, making it extremely useful as a resist underlayer film material used in multilayer resist methods and as a reversal agent used in tone reversal etching methods, and that the pattern formation method of the present invention using this composition makes it possible to form fine patterns with high precision even if the workpiece is a substrate with steps.

[0321] The present specification includes the following aspects. [1]: A composition for forming a metal oxide film, (A) metal oxide nanoparticles; (B) a flowability promoter containing a resin having a structural unit represented by the following general formula (1): (C) a dispersion stabilizer consisting of an aromatic-containing compound containing two or more benzene rings, or one benzene ring and a structure represented by the following general formula (C-1), and having a molecular weight represented by a molecular formula of 500 or less; and (D) contains an organic solvent, A composition for forming a metal oxide film, characterized in that the content of the (B) flow promoter relative to the entire composition is 9 mass% or more, the ratio Mw / Mn of the weight average molecular weight Mw to the number average molecular weight Mn in terms of polystyrene measured by gel permeation chromatography is 2.50≦Mw / Mn≦9.00, and the composition does not contain any compound or polymer having a cardo structure. [ka] (In the general formula (1), R a represents a saturated monovalent organic group having 1 to 30 carbon atoms or an unsaturated monovalent organic group having 2 to 30 carbon atoms, X represents a divalent organic group having 1 to 30 carbon atoms, p represents an integer of 0 to 5, q1 represents an integer of 1 to 6, p+q1 represents an integer of 1 or greater and 6 or less, and q2 represents 0 or 1. [ka] (In the formula, * indicates a bonding position, and W is an organic group having 1 to 4 carbon atoms.) [2]: The composition for forming a metal oxide film according to [1] above, characterized in that the (B) flowability promoter contains a resin having a structural unit represented by the following general formula (2) in addition to a resin having a structural unit represented by the general formula (1) above, or is a resin having both a structural unit represented by the general formula (1) above and a structural unit represented by the following general formula (2): [ka] (In the above general formula (2), R a is a saturated monovalent organic group having 1 to 30 carbon atoms or an unsaturated monovalent organic group having 2 to 30 carbon atoms, R b represents a saturated hydrocarbon group having 1 to 30 carbon atoms or an unsaturated hydrocarbon group having 2 to 10 carbon atoms, X represents a divalent organic group having 1 to 30 carbon atoms, p represents an integer of 0 to 5, q1 represents an integer of 1 to 6, p+q1 represents an integer of 1 or more and 6 or less, and q2 represents 0 or 1. [3]: In the general formula (2), R b is either an alkyl group having 1 to 30 carbon atoms or a structure represented by the following general formula (3), and the content of the general formula (2) satisfies the relationship a+b=1, 0.2≦b≦0.8, where a is the proportion of the general formula (1) and b is the proportion of the general formula (2): [ka] (In the general formula (3), * represents a bonding site to an oxygen atom, and R A represents an optionally substituted divalent organic group having 1 to 10 carbon atoms, R B is a hydrogen atom or an optionally substituted monovalent organic group having 1 to 10 carbon atoms. [4]: The metal oxide film-forming composition according to any one of [1] to [3] above, characterized in that the (C) dispersion stabilizer has a weight loss rate of less than 30% from 30°C to 190°C and a weight loss rate of 98% or more from 30°C to 350°C. [5]: The composition for forming a metal oxide film according to any one of [1] to [4] above, wherein the (C) dispersion stabilizer contains one or more compounds selected from the following general formulas (I) to (III): [ka] (In the formula, R 1 are each independently a hydrogen atom, a hydroxyl group, or an optionally substituted organic group having 1 to 10 carbon atoms. 1 W is a phenylene group or a divalent group represented by the following general formula (I-1): 2 , W 3 is a single bond or a divalent group represented by the following general formula (I-2): 1 is an integer between 1 and 10, and n 1 is an integer between 0 and 5.) [ka] (where * indicates a bonding position, and R 10 , R 11 , R 12 , R 13 is a hydrogen atom, a hydroxyl group, or an organic group having 1 to 10 carbon atoms. 10 , W 11 Each m is independently a single bond or a carbonyl group. 10 , m 11 is an integer between 0 and 10, and m 10 +m 11 ≧1.) [ka] (In the formula, * indicates the bonding position.) [ka] (In the formula, R 2 are each independently a hydrogen atom or an optionally substituted organic group having 1 to 10 carbon atoms. 4 is a divalent group represented by any one of the following general formulas (II-1): 5 is a single bond or a divalent group represented by the following general formula (II-2): 2 is an integer between 2 and 10, and n 3 is an integer between 0 and 5.) [ka] (where * indicates a bonding position, and R 20 , R 21 , R 22 , R 23 is a hydrogen atom, a hydroxyl group, or an organic group having 1 to 10 carbon atoms. 20 , m 21 is an integer between 0 and 10, and m 20 +m 21 ≧1.) [ka] (In the formula, * indicates the bonding position.) [ka] (In the formula, R 3 , R 4 R is a hydrogen atom, a hydroxyl group, or an organic group having 1 to 10 carbon atoms which may be substituted, and may be bonded to form a cyclic structure. 5 , R 6 is an organic group having 1 to 10 carbon atoms, and R 5 is a group containing either an aromatic ring or a divalent group represented by the following general formula (III-1): 6 , W 7 is a single bond or a divalent group represented by the following general formula (III-2), and at least one of them is a divalent group represented by the following general formula (III-2). [ka] (where * indicates a bond position, and W 30 is an organic group having 1 to 4 carbon atoms. [ka] (In the formula, * indicates the bonding position.) [6]: The metal oxide film-forming composition according to any one of [1] to [5] above, wherein the (A) metal oxide nanoparticles are one or more metal oxide nanoparticles selected from the group consisting of zirconium, hafnium, aluminum, tungsten, titanium, copper, tin, cerium, indium, zinc, yttrium, lanthanum, chromium, cobalt, platinum, iron, antimony, and germanium. [7]: The metal oxide film-forming composition according to [6] above, wherein the (A) metal oxide nanoparticles are one or more selected from the group consisting of zirconium oxide nanoparticles, hafnium oxide nanoparticles, tungsten oxide nanoparticles, titanium oxide nanoparticles, and tin oxide nanoparticles. [8]: The composition for forming a metal oxide film according to any one of [1] to [7] above, wherein the (A) metal oxide nanoparticles have an average primary particle size of 100 nm or less. [9]: The composition for forming a metal oxide film according to any one of [1] to [8] above, characterized in that the weight ratio of the (A) metal oxide nanoparticles to the (B) flowability promoter is 80 / 20 to 10 / 90.

[10] : The composition for forming a metal oxide film according to any one of [1] to [9] above, characterized in that the composition for forming a metal oxide film further contains one or more of a crosslinking agent, a surfactant, and an acid generator.

[11] : A method for forming a pattern on a workpiece substrate, (I-1) A step of applying any one of the compositions for forming a metal oxide film according to [1] to

[10] above onto a substrate to be processed, followed by heat treatment to form a metal oxide film; (I-2) forming a resist top layer film on the metal oxide film using a photoresist material; (I-3) a step of pattern-exposing the resist upper layer film and then developing it with a developer to form a pattern on the resist upper layer film; (I-4) a step of transferring the pattern to the metal oxide film by dry etching using the resist upper layer film on which the pattern has been formed as a mask; and (I-5) A step of processing the substrate to be processed using the metal oxide film on which the pattern has been formed as a mask to form a pattern on the substrate to be processed. A pattern forming method comprising the steps of:

[12] : A method for forming a pattern on a workpiece substrate, (II-1) A step of applying any one of the compositions for forming a metal oxide film according to [1] to

[10] above onto a substrate to be processed, followed by heat treatment to form a metal oxide film; (II-2) forming a silicon-containing resist intermediate film on the metal oxide film using a silicon-containing resist intermediate film material; (II-3) forming a resist upper layer film on the silicon-containing resist intermediate film using a photoresist material; (II-4) a step of pattern-exposing the resist upper layer film and then developing it with a developer to form a pattern on the resist upper layer film; (II-5) a step of transferring the pattern to the silicon-containing resist intermediate film by dry etching using the resist upper layer film on which the pattern has been formed as a mask; (II-6) a step of transferring a pattern to the metal oxide film by dry etching using the silicon-containing resist intermediate film to which the pattern has been transferred as a mask; and (II-7) A step of processing the substrate to be processed using the metal oxide film on which the pattern has been formed as a mask to form a pattern on the substrate to be processed. A pattern forming method comprising the steps of:

[13] : A method for forming a pattern on a workpiece substrate, (III-1) A step of applying any one of the compositions for forming a metal oxide film according to [1] to

[10] above onto a substrate to be processed, followed by heat treatment to form a metal oxide film; (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 metal oxide film; (III-3) forming an organic thin film on the inorganic hard mask intermediate film; (III-4) forming a resist top layer film on the organic thin film using a photoresist material; (III-5) a step of pattern-exposing the resist upper layer film and then developing it with a developer to form a pattern on the resist upper layer film; (III-6) a step of transferring the pattern to the organic thin film and the inorganic hard mask intermediate film by dry etching using the resist upper layer film on which the pattern has been formed as a mask; (III-7) transferring the pattern to the metal oxide film by dry etching using the inorganic hard mask intermediate film to which the pattern has been transferred as a mask; and (III-8) A step of processing the substrate to be processed using the metal oxide film on which the pattern has been formed as a mask to form a pattern on the substrate to be processed. A pattern forming method comprising the steps of:

[14] : A method for forming a pattern on a workpiece substrate, comprising: (IV-1) forming a resist underlayer film on a substrate to be processed; (IV-2) forming a resist intermediate film or a combination of an inorganic hard mask intermediate film selected from a silicon oxide film, a silicon nitride film, and a silicon oxynitride film and an organic thin film on the resist underlayer film; (IV-3) forming a resist upper layer film using a photoresist material on the resist intermediate film or the combination of the inorganic hard mask intermediate film and the organic thin film; (IV-4) a step of pattern-exposing the resist upper layer film and then developing it with a developer to form a pattern on the resist upper layer film; (IV-5) a step of transferring a pattern to the resist intermediate film, or the organic thin film and the inorganic hard mask intermediate film, by dry etching using the resist upper layer film on which the pattern has been formed as a mask; (IV-6) a step of transferring a pattern to the resist underlayer film by dry etching using the resist interlayer film or inorganic hard mask interlayer film to which the pattern has been transferred as a mask; (IV-7) a step of applying a metal oxide film-forming composition according to any one of [1] to

[10] above onto the resist underlayer film on which the pattern has been formed, followed by heat treatment to cover the resist underlayer film with a metal oxide film, and filling spaces between the resist underlayer film patterns with the metal oxide film; (IV-8) etching back the metal oxide film covering the resist underlayer film on which the pattern has been formed by chemical stripping or dry etching to expose the upper surface of the resist underlayer film on which the pattern has been formed; (IV-9) a step of removing the resist intermediate film or inorganic hard mask intermediate film remaining on the upper surface of the resist underlayer film by dry etching; (IV-10) a step of removing the resist underlayer film on which the pattern is formed and the surface is exposed by dry etching, thereby forming a reverse pattern of the original pattern on the metal oxide film; (IV-11) A step of processing the substrate to be processed using the metal oxide film on which the reversal pattern is formed as a mask to form a tone-reversal pattern on the substrate to be processed. A pattern forming method comprising the steps of:

[15] : A pattern forming method using a metal oxide film-forming composition as a sacrificial film, (V-1) a step of applying any one of the compositions for forming a metal oxide film according to [1] to

[10] above onto a substrate to be processed having a structure or a step, and then performing a heat treatment to fill the substrate with a metal oxide film; (V-2) a step of removing the metal oxide film outside the structure or step on the substrate to be processed by a CMP method, thereby removing the metal oxide film from the surface of the substrate to be processed; (V-3) a step of alternately laminating insulating films and conductive films on the substrate to be processed filled with the metal oxide film; (V-4) forming an organic resist underlayer film on the laminated film of the insulating film and the conductive film formed on the substrate to be processed filled with the metal oxide film; (V-5) forming a resist intermediate film, or an inorganic hard mask intermediate film selected from a silicon oxide film, a silicon nitride film, and a silicon oxynitride film, or a combination of the inorganic hard mask intermediate film and an organic thin film on the organic resist underlayer film; (V-6) forming a resist upper layer film using a photoresist material on the resist intermediate film, or the inorganic hard mask intermediate film, or the combination of the inorganic hard mask intermediate film and the organic thin film; (V-7) a step of pattern-exposing the resist upper layer film and then developing it with a developer to form a pattern on the resist upper layer film; (V-8) a step of transferring a pattern to the resist intermediate film, or the inorganic hard mask intermediate film, or the organic thin film and the inorganic hard mask intermediate film by dry etching using the resist upper layer film on which the pattern has been formed as a mask; (V-9) a step of transferring a pattern to the resist underlayer film by dry etching using the resist interlayer film or inorganic hard mask interlayer film to which the pattern has been transferred as a mask; (V-10) a step of transferring a pattern to the laminated film of the insulating film and the conductive film by dry etching using the resist underlayer film to which the pattern has been transferred as a mask; (V-11) A step of removing the metal oxide film filled on the substrate to be processed using the laminated film of the insulating film and the conductive film to which the pattern has been transferred as a mask. A pattern forming method comprising the steps of:

[16] : The pattern forming method according to any one of

[11] to

[15] above, wherein the substrate to be processed is a substrate having a structure or steps with an aspect ratio of 5 or more.

[17] : A method for forming a metal oxide film that functions as a flat film used in the manufacturing process of a semiconductor device, characterized in that a substrate to be processed is coated with any one of the metal oxide film-forming compositions [1] to

[10] above, and the substrate is heat-treated at a temperature of 100°C or higher and 600°C or lower for 10 to 600 seconds to form a hardened film.

[18] : A method for forming a metal oxide film that functions as a flat film used in the manufacturing process of a semiconductor device, characterized in that a substrate to be processed is coated with any one of the metal oxide film-forming compositions [1] to

[10] above, and the substrate is heat-treated in an atmosphere with an oxygen concentration of 1% by volume or more and 21% by volume or less to form a hardened film.

[19] : A method for forming a metal oxide film that functions as a flat film used in the manufacturing process of a semiconductor device, characterized in that a substrate to be processed is coated with any one of the metal oxide film-forming compositions [1] to

[10] above, and the substrate is heat-treated in an atmosphere with an oxygen concentration of less than 1% by volume to form a hardened film.

[0322] The present invention is not limited to the above-described embodiments. The above-described embodiments are merely examples, and anything that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits similar effects is included within the technical scope of the present invention. [Explanation of symbols]

[0323] 1...Substrate to be processed, 2...Layer to be processed, 2a...pattern (pattern formed on the processing layer), 3...metal-containing resist underlayer film (metal oxide film), 3a...metal-containing resist underlayer film pattern, 4...silicon atom-containing resist intermediate film, 4a...silicon atom-containing resist intermediate film pattern, 5...resist upper layer film, 5a...resist upper layer film pattern, 6...exposed portion, 7...resist underlayer film made of a coating-type organic underlayer film material, 7a...resist underlayer film pattern made of coating-type organic underlayer film material; 8...metal oxide film, 8a...metal oxide film pattern inverted from the resist underlayer film pattern, 9...conductive film, 9a...conductive film pattern, 10...insulating film, 10a...insulating film pattern, 11...upper and lower connecting insulating film, 12...metal oxide film, 12a...metal oxide film after CMP planarization, 13...organic resist underlayer film, 13a...organic resist underlayer film pattern, 14...silicon atom-containing resist intermediate film, 14a...silicon atom-containing resist intermediate film pattern, 15...resist upper layer film, 15a...resist upper layer film pattern, 16...through patterns of 100th and 200th layers, 100...alternate laminated film (lower layer) of insulating film pattern 10a and conductive film pattern 9a, 200...Alternate laminated film (upper layer) of insulating film 10 and conductive film 9, 17...Base substrate having a dense hole pattern, 18...Metal oxide film

Claims

1. A metal oxide film-forming composition, (A) metal oxide nanoparticles; (B) a fluidity promoter containing a resin having a structural unit represented by the following general formula (1): (C) a dispersion stabilizer comprising an aromatic-containing compound containing two or more benzene rings, or one benzene ring and a structure represented by the following general formula (C-1), and having a molecular weight represented by a molecular formula of 500 or less; and (D) containing an organic solvent, A composition for forming a metal oxide film, characterized in that the content of the flow promoter (B) relative to the entire composition is 9 mass% or more, the ratio Mw / Mn of the weight average molecular weight Mw to the number average molecular weight Mn in terms of polystyrene measured by gel permeation chromatography method is 2.50≦Mw / Mn≦9.00, and the composition does not contain any compound having a cardo structure or a polymer. 【Chemistry 1】 (In the general formula (1), R ａ is a saturated monovalent organic group having 1 to 30 carbon atoms or an unsaturated monovalent organic group having 2 to 30 carbon atoms; X is a divalent organic group having 1 to 30 carbon atoms; p is an integer of 0 to 5; q １ is an integer from 1 to 6, p+q １ is an integer of 1 to 6, and q ２ is 0 or 1.) 【Chemistry 2】 (In the formula, * indicates the bonding position, and W is an organic group having 1 to 4 carbon atoms.)

2. 2. The composition for forming a metal oxide film according to claim 1, wherein the (B) flowability promoter contains a resin having a structural unit represented by the following general formula (2) in addition to a resin having a structural unit represented by the general formula (1), or is a resin having both the structural unit represented by the general formula (1) and a structural unit represented by the following general formula (2): 【Transformation 3】 (In the above general formula (2), R ａ is a saturated monovalent organic group having 1 to 30 carbon atoms or an unsaturated monovalent organic group having 2 to 30 carbon atoms; R ｂ represents a saturated hydrocarbon group having 1 to 30 carbon atoms or an unsaturated hydrocarbon group having 2 to 10 carbon atoms; X represents a divalent organic group having 1 to 30 carbon atoms; p represents an integer of 0 to 5; q １ is an integer from 1 to 6, p+q １ is an integer of 1 to 6, and q ２ is 0 or 1.)

3. In the general formula (2), R ｂ is either an alkyl group having 1 to 30 carbon atoms or a structure represented by the following general formula (3), and the content of the general formula (2) satisfies the relationship a+b=1, 0.2≦b≦0.8, where a is the proportion of the general formula (1) and b is the proportion of the general formula (2): 【Chemistry 4】 (In the general formula (3), * represents a bonding site to an oxygen atom, and R Ａ represents an optionally substituted divalent organic group having 1 to 10 carbon atoms; R Ｂ is a hydrogen atom or an optionally substituted monovalent organic group having 1 to 10 carbon atoms.

4. 2. The metal oxide film-forming composition according to claim 1, wherein the (C) dispersion stabilizer has a weight loss rate of less than 30% from 30°C to 190°C and a weight loss rate of 98% or more from 30°C to 350°C.

5. 2. The metal oxide film-forming composition according to claim 1, wherein the dispersion stabilizer (C) comprises one or more compounds selected from the group consisting of compounds represented by the following general formulas (I) to (III): 【Transformation 5】 (In the formula, R １ are each independently a hydrogen atom, a hydroxyl group, or an optionally substituted organic group having 1 to 10 carbon atoms. １ is a phenylene group or a divalent group represented by the following general formula (I-1): ２ , W ３ is a single bond or a divalent group represented by the following general formula (I-2): 1 is an integer from 1 to 10, and n １ is an integer from 0 to 5. 【Transformation 6】 (where * indicates a bonding position, R １０ , R １１ , R １２ , R １３ is a hydrogen atom, a hydroxyl group, or an organic group having 1 to 10 carbon atoms. １０ , W １１ are each independently a single bond or a carbonyl group. １０ , m １１ is an integer from 0 to 10, and m １０ +m １１ ≧1.) 【Transformation 7】 (In the formula, * indicates the bonding position.) 【Transformation 8】 (In the formula, R ２ are each independently a hydrogen atom or an optionally substituted organic group having 1 to 10 carbon atoms. ４ is a divalent group represented by the following general formula (II-1): ５ is a single bond or a divalent group represented by the following general formula (II-2): ２ is an integer from 2 to 10, and n ３ is an integer from 0 to 5. 【Chemistry 9】 (where * indicates a bonding position, R ２０ , R ２１ , R ２２ , R ２３ is a hydrogen atom, a hydroxyl group, or an organic group having 1 to 10 carbon atoms. ２０ , m ２１ is an integer from 0 to 10, and m ２０ +m ２１ ≧1.) 【Chemistry 10】 (In the formula, * indicates the bonding position.) 【Chemistry 11】 (In the formula, R ３ , R ４ R is a hydrogen atom, a hydroxyl group, or an organic group having 1 to 10 carbon atoms which may be substituted, and may be bonded to form a cyclic structure. ５ , R ６ is an organic group having 1 to 10 carbon atoms, and R ５ is a group containing either an aromatic ring or a divalent group represented by the following general formula (III-1): ６ , W ７ is a single bond or a divalent group represented by the following general formula (III-2), and at least one of them is a divalent group represented by the following general formula (III-2): 【Chemistry 12】 (where * indicates a bond position, W ３０ is an organic group having 1 to 4 carbon atoms. 【Chemistry 13】 (In the formula, * indicates the bonding position.)

6. 2. The metal oxide film-forming composition according to claim 1, wherein the (A) metal oxide nanoparticles are one or more metal oxide nanoparticles selected from the group consisting of zirconium, hafnium, aluminum, tungsten, titanium, copper, tin, cerium, indium, zinc, yttrium, lanthanum, chromium, cobalt, platinum, iron, antimony, and germanium.

7. 7. The metal oxide film-forming composition according to claim 6, wherein the (A) metal oxide nanoparticles are one or more nanoparticles selected from the group consisting of zirconium oxide nanoparticles, hafnium oxide nanoparticles, tungsten oxide nanoparticles, titanium oxide nanoparticles, and tin oxide nanoparticles.

8. 2. The metal oxide film-forming composition according to claim 1, wherein the metal oxide nanoparticles (A) have an average primary particle size of 100 nm or less.

9. 2. The metal oxide film-forming composition according to claim 1, wherein the weight ratio of the metal oxide nanoparticles (A) to the flowability promoter (B) is 80 / 20 to 10 / 90.

10. 2. The composition for forming a metal oxide film according to claim 1, further comprising at least one of a crosslinking agent, a surfactant, and an acid generator.

11. A method for forming a pattern on a workpiece substrate, comprising: (I-1) A step of applying the composition for forming a metal oxide film according to claim 1 onto a substrate to be processed, followed by heat treatment to form a metal oxide film; (I-2) forming a resist top layer film on the metal oxide film using a photoresist material; (I-3) a step of pattern-exposing the resist upper layer film and then developing it with a developer to form a pattern on the resist upper layer film; (I-4) a step of transferring the pattern to the metal oxide film by dry etching using the resist upper layer film on which the pattern has been formed as a mask; and (I-5) A step of processing the substrate to be processed using the metal oxide film on which the pattern has been formed as a mask to form a pattern on the substrate to be processed. A pattern forming method comprising the steps of:

12. A method for forming a pattern on a workpiece substrate, comprising: (II-1) A step of applying the composition for forming a metal oxide film according to claim 1 onto a substrate to be processed, followed by heat treatment to form a metal oxide film; (II-2) forming a silicon-containing resist intermediate film on the metal oxide film using a silicon-containing resist intermediate film material; (II-3) forming a resist upper layer film on the silicon-containing resist intermediate film using a photoresist material; (II-4) a step of pattern-exposing the resist upper layer film and then developing it with a developer to form a pattern on the resist upper layer film; (II-5) a step of transferring the pattern to the silicon-containing resist intermediate film by dry etching using the resist upper layer film on which the pattern has been formed as a mask; (II-6) A step of transferring a pattern to the metal oxide film by dry etching using the silicon-containing resist intermediate film to which the pattern has been transferred as a mask; and (II-7) A step of processing the substrate to be processed using the metal oxide film on which the pattern has been formed as a mask to form a pattern on the substrate to be processed. A pattern forming method comprising the steps of:

13. A method for forming a pattern on a workpiece substrate, comprising: (III-1) A step of applying the composition for forming a metal oxide film according to claim 1 onto a substrate to be processed, followed by heat treatment to form a metal oxide film; (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 metal oxide film; (III-3) forming an organic thin film on the inorganic hard mask intermediate film; (III-4) forming a resist top layer film on the organic thin film using a photoresist material; (III-5) a step of pattern-exposing the resist upper layer film and then developing it with a developer to form a pattern on the resist upper layer film; (III-6) a step of transferring the pattern to the organic thin film and the inorganic hard mask intermediate film by dry etching using the resist upper layer film on which the pattern has been formed as a mask; (III-7) transferring the pattern to the metal oxide film by dry etching using the inorganic hard mask intermediate film to which the pattern has been transferred as a mask; and (III-8) A step of processing the substrate to be processed using the metal oxide film on which the pattern has been formed as a mask to form a pattern on the substrate to be processed. A pattern forming method comprising the steps of:

14. A method for forming a pattern on a workpiece substrate, comprising: (IV-1) A step of forming a resist underlayer film on a substrate to be processed; (IV-2) forming a resist intermediate film or a combination of an inorganic hard mask intermediate film selected from a silicon oxide film, a silicon nitride film, and a silicon oxynitride film and an organic thin film on the resist underlayer film; (IV-3) forming a resist upper layer film using a photoresist material on the resist intermediate film or the combination of the inorganic hard mask intermediate film and the organic thin film; (IV-4) a step of pattern-exposing the resist upper layer film and then developing it with a developer to form a pattern on the resist upper layer film; (IV-5) a step of transferring a pattern to the resist intermediate film, or the organic thin film and the inorganic hard mask intermediate film, by dry etching using the resist upper layer film on which the pattern has been formed as a mask; (IV-6) A step of transferring a pattern to the resist underlayer film by dry etching using the resist interlayer film or the inorganic hard mask interlayer film to which the pattern has been transferred as a mask; (IV-7) a step of applying the composition for forming a metal oxide film according to claim 1 onto the resist underlayer film on which the pattern has been formed, followed by heat treatment to cover the resist underlayer film with a metal oxide film, and filling spaces between the resist underlayer film patterns with the metal oxide film; (IV-8) etching back the metal oxide film covering the resist underlayer film on which the pattern has been formed by a chemical stripper or dry etching to expose the upper surface of the resist underlayer film on which the pattern has been formed; (IV-9) A step of removing the resist intermediate film or the inorganic hard mask intermediate film remaining on the upper surface of the resist underlayer film by dry etching; (IV-10) a step of removing the resist underlayer film on which the pattern is formed and the surface is exposed by dry etching, thereby forming a reverse pattern of the original pattern on the metal oxide film; (IV-11) A step of processing the substrate to be processed using the metal oxide film on which the reversal pattern is formed as a mask to form a tone-reversal pattern on the substrate to be processed. A pattern forming method comprising the steps of:

15. A pattern forming method using a metal oxide film-forming composition as a sacrificial film, comprising: (V-1) a step of applying the composition for forming a metal oxide film according to claim 1 onto a substrate to be processed having a structure or a step, and then performing a heat treatment to fill the substrate with a metal oxide film; (V-2) a step of removing the metal oxide film outside the structure or step on the substrate to be processed by a CMP method, thereby removing the metal oxide film from the surface of the substrate to be processed; (V-3) A step of alternately laminating insulating films and conductive films on the substrate to be processed filled with the metal oxide film; (V-4) a step of forming an organic resist underlayer film on the laminated film of the insulating film and the conductive film formed on the substrate to be processed filled with the metal oxide film; (V-5) forming a resist intermediate film, or an inorganic hard mask intermediate film selected from a silicon oxide film, a silicon nitride film, and a silicon oxynitride film, or a combination of the inorganic hard mask intermediate film and an organic thin film on the organic resist underlayer film; (V-6) forming a resist upper layer film using a photoresist material on the resist intermediate film, or the inorganic hard mask intermediate film, or the combination of the inorganic hard mask intermediate film and the organic thin film; (V-7) a step of pattern-exposing the resist upper layer film and then developing it with a developer to form a pattern on the resist upper layer film; (V-8) a step of transferring a pattern to the resist intermediate film, or the inorganic hard mask intermediate film, or the organic thin film and the inorganic hard mask intermediate film by dry etching using the resist upper layer film on which the pattern has been formed as a mask; (V-9) a step of transferring a pattern to the resist underlayer film by dry etching using the resist interlayer film or inorganic hard mask interlayer film to which the pattern has been transferred as a mask; (V-10) a step of transferring a pattern to the laminated film of the insulating film and the conductive film by dry etching using the resist underlayer film to which the pattern has been transferred as a mask; (V-11) A step of removing the metal oxide film filled on the substrate to be processed using the laminated film of the insulating film and the conductive film to which the pattern has been transferred as a mask. A pattern forming method comprising the steps of:

16. 16. The pattern formation method according to claim 11, wherein the substrate to be processed is a substrate having a structure or steps with an aspect ratio of 5 or more.

17. A method for forming a metal oxide film that functions as a flat film used in a manufacturing process of a semiconductor device, the method comprising: applying the metal oxide film-forming composition according to any one of claims 1 to 10 onto a substrate to be processed; and heat-treating the substrate at a temperature of 100°C or higher and 600°C or lower for 10 to 600 seconds to form a cured film.

18. 11. A method for forming a metal oxide film that functions as a flat film used in a manufacturing process of a semiconductor device, the method comprising: applying a metal oxide film-forming composition according to claim 1 onto a substrate to be processed; and heat-treating the substrate in an atmosphere with an oxygen concentration of 1% by volume or more and 21% by volume or less to form a hardened film.

19. 11. A method for forming a metal oxide film that functions as a flat film used in a manufacturing process of a semiconductor device, the method comprising: applying a metal oxide film-forming composition according to claim 1 onto a substrate to be processed; and heat-treating the substrate in an atmosphere with an oxygen concentration of less than 1% by volume to form a hardened film.

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