Pattern forming method

Abstract

To provide a pattern forming method for a resist underlayer film exhibiting excellent edge roughness by plasma irradiation in comparison to a conventional organic underlayer film pattern.SOLUTION: A pattern forming method includes: a process of forming a resist underlayer on a substrate; a process of forming a silicon-containing resist interlayer on the resist underlayer; a process of forming a resist upper layer on the silicon-containing resist interlayer; a process of forming a pattern on the resist upper layer; a process of forming a resist underlayer pattern by a plurality of times of etching using the resist pattern as a mask; and a process of irradiating the resist underlayer pattern with plasma, wherein a composition containing a resin having an aromatic ring is used as a composition for forming the resist underlayer, and a plasma by which the resist underlayer is less etched than by an etching gas used in the process of forming the resist underlayer pattern is used as the plasma for the plasma irradiation.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for forming a resist underlayer film pattern that can be used for fine patterning by a multilayer resist method in the manufacturing process of a semiconductor device. [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] On the other hand, in recent years, the miniaturization of DRAM memory has accelerated, and in fine patterns with high resolution on the order of nanometers, the proportion of edge roughness to the line width of the pattern has increased, and since it has become more difficult than ever to reduce the edge roughness of the pattern, there has been an increasing need for resist underlayer film patterns with good edge roughness. In particular, in the sidewall spacer method (Non-Patent Document 1), which attaches a film to the sidewalls on both sides of a line pattern to thereby halve the pitch, reducing the edge roughness of the resist underlayer film pattern has become an issue.

[0009] One proposed sidewall spacer method involves forming sidewalls on a core pattern using CVD techniques with materials such as SiO2, α-Si, or α-C, and then removing the core pattern by dry etching to leave the sidewalls as a pattern, thereby halving the pattern pitch. In a multilayer resist method using an organic resist underlayer film and a silicon-containing intermediate film, a resist pattern is transferred to a core material made of an organic underlayer film by dry etching, and then sidewalls are formed on the core material to which the pattern has been transferred. The core material is then removed, resulting in a pattern with a 1 / 2 pattern pitch. The edge roughness of the sidewall pattern with a 1 / 2 pattern pitch is strongly affected by the edge roughness of the core resist underlayer film pattern.

[0010] Various methods have been investigated to reduce the line width variation of the pattern of the etched layer. One example is a method in which a resist film is hardened by performing a plasma treatment using H2 gas to reduce edge roughness of the resist pattern (Patent Document 2). However, when using the above method as an etching mask for advanced generations, there are concerns about the dry etching resistance of the resist pattern, and deterioration of edge roughness is expected when the pattern is transferred to the substrate to be processed. Furthermore, when using it as the core of the sidewall spacer method, there are concerns about the heat resistance of the resist pattern, and deterioration of edge roughness is expected when forming sidewalls by CVD. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-205685 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-219292 [Non-patent literature]

[0012] [Non-Patent Document 1] J.Vac.Sci.Technol.B17(6), Nov / Dec1999 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 an object of the present invention is to provide a method for forming a resist underlayer film pattern that, by irradiating with plasma, exhibits superior edge roughness compared to conventional organic underlayer film patterns. [Means for solving the problem]

[0014] In order to solve the above problems, the present invention provides: A method for forming a resist underlayer film pattern on a substrate, comprising: (i-1) applying a composition for forming a resist underlayer film onto the substrate and then performing a heat treatment to form a resist underlayer film; (i-2) applying a silicon-containing resist intermediate film onto the resist underlayer film, followed by heat treatment to form a silicon-containing resist intermediate film; (i-3) forming a resist upper layer film on the silicon-containing resist intermediate film; (i-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; (i-5) forming a resist underlayer film pattern by performing etching a plurality of times using the resist upper layer film pattern as a mask; (i-6) a step of irradiating the resist underlayer film pattern with plasma; and The resist underlayer film-forming composition contains a resin having an aromatic ring, The present invention provides a pattern formation method, characterized in that the plasma used for the plasma irradiation in the step (i-6) etches the resist underlayer film less than the etching gas used in the step (i-5) of forming a resist underlayer film pattern by etching the resist underlayer film.

[0015] According to such a method for forming a resist underlayer film pattern, the film surface on the pattern sidewalls is modified by plasma irradiation, and a resist underlayer film pattern with good edge roughness can be formed.

[0016] Also, there is provided a method for forming a resist underlayer film pattern on a substrate, comprising the steps of: (ii-1) applying a composition for forming a resist underlayer film onto the substrate and then performing a heat treatment to form a resist underlayer film; (ii-2) forming an inorganic hard mask intermediate film selected from a silicon oxide film, a silicon nitride film, and a silicon oxynitride film on the resist underlayer film; (ii-3) forming an upper layer resist film on the inorganic hard mask intermediate film; (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) forming a resist underlayer film pattern by performing etching a plurality of times using the resist upper layer film pattern as a mask; (ii-6) a step of irradiating the resist underlayer film pattern with plasma; and The resist underlayer film-forming composition contains a resin having an aromatic ring, The present invention provides a pattern formation method, characterized in that the plasma used for the plasma irradiation in the step (ii-6) etches the resist underlayer film less than the etching gas used in the step (ii-5) of forming a resist underlayer film pattern by etching the resist underlayer film.

[0017] According to such a method for forming a resist underlayer film pattern, the film surface on the pattern sidewalls is modified by plasma irradiation, and a resist underlayer film pattern with good edge roughness can be formed.

[0018] In this case, the pattern forming method may include, after the plasma irradiation step, a step of forming a pattern directly or indirectly on a substrate using the plasma-irradiated resist underlayer film pattern as an etching mask.

[0019] In this manner, the pattern forming method of the present invention can form a pattern on a substrate.

[0020] The pattern forming method is preferably such that the plasma irradiation step is carried out in an atmosphere of N2, NF3, H2, a fluorocarbon, a rare gas, or a mixture of any of these.

[0021] By irradiating the resist underlayer film pattern with plasma in an atmosphere containing the above gas, side etching of the resist underlayer film pattern can be suppressed and edge roughness can be improved.

[0022] In this case, the pattern forming method is preferably such that the plasma irradiation step is carried out in an atmosphere containing hydrogen or helium.

[0023] Thus, from the viewpoint of productivity, a gas containing H2 or helium is preferable.

[0024] The composition for forming a resist underlayer film, (a) a polymer compound having an aromatic ring in the main chain and a weight average molecular weight of 2,500 or more and 20,000 or less in terms of polystyrene as determined by gel permeation chromatography; Preferably, the pattern forming method described above is characterized in that it contains (b) an aromatic ring-containing compound having a weight average molecular weight of 600 or more and 3,000 or less in terms of polystyrene measured by gel permeation chromatography, or an (A) resin which is a combination thereof.

[0025] In the pattern formation method using the composition for forming a resist underlayer film containing the above-mentioned (A) resin, modification by plasma irradiation is likely to occur, and a resist underlayer film pattern with better edge roughness can be formed.

[0026] In this case, the (A) resin preferably has at least one crosslinkable group selected from a vinyl group, an allyl group, an allyloxy group, an ethynyl group, a propargyl group, a propargyloxy group, an epoxy group, an oxetanyl group, and a hydroxyl group.

[0027] Since the resin (A) having the crosslinkable group has excellent curability, a pattern formation method using a composition for forming a resist underlayer film containing the resin (A) can form a dense resist underlayer film pattern. The resist underlayer film pattern obtained thereby is more susceptible to modification by plasma irradiation, and a resist underlayer film pattern with good edge roughness can be formed.

[0028] A method for forming a pattern on the substrate at a pitch that is 1 / 2 of the pitch of the resist upper layer film pattern, comprising: After the step of irradiating the resist underlayer film pattern with plasma, forming an inorganic silicon film made of any one of polysilicon, amorphous silicon, silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, and composite materials thereof by a CVD method or an ALD method so as to cover the resist underlayer film pattern; a step of removing the resist underlayer film pattern by dry etching or using a stripping solution to form an inorganic silicon film pattern having a pattern pitch that is half that of the resist upper layer film pattern; It is preferable that the pattern forming method described above is characterized by comprising:

[0029] Such a pattern formation method can form a resist underlayer film pattern with good edge roughness, and when used as the core of the sidewall spacer method, it can improve the edge roughness of the sidewall pattern with a pattern pitch reduced to 1 / 2. [Effects of the Invention]

[0030] As explained above, in recent years, the miniaturization of DRAM memory has accelerated, and in fine patterns with high resolution on the order of nanometers, the proportion of edge roughness relative to the line width of the pattern has increased. Furthermore, reducing the edge roughness of the pattern has become more difficult than ever before, which has led to an increasing need for resist underlayer film patterns with good edge roughness. In particular, in the sidewall spacer method, in which a film is applied to both sidewalls of a line pattern to thereby halve the pitch, reducing the edge roughness of the resist underlayer film pattern has become an issue. The resist underlayer film pattern formation method of the present invention can provide a resist underlayer film pattern that exhibits superior edge roughness compared to conventional organic underlayer film patterns by irradiating the pattern with plasma, and is therefore particularly suitable for use in multilayer resist processes and extremely useful in fine patterning for semiconductor device manufacturing. [Brief explanation of the drawings]

[0031] [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 pattern forming method of the present invention (sidewall spacer method). [Figure 3] FIG. 3 is an explanatory diagram of an example of the pattern forming method of the present invention (sidewall spacer method using wet peeling). [Figure 4] FIG. 4 is an explanatory diagram of an example of the pattern forming method of the present invention (sidewall spacer method). [Figure 5] FIG. 5 is an explanatory diagram of another example (sidewall spacer method) of the pattern forming method of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0032] As described above, in a fine patterning process using a multilayer resist method, there has been a demand for a method for forming a resist underlayer film pattern that can transfer a resist pattern to a substrate to be processed with higher accuracy, and for the development of a resist underlayer film pattern that is useful as a core material in the sidewall spacer method.

[0033] The present inventors have sought a method for forming a resist underlayer film pattern with small edge roughness and conducted extensive research. As a result, they have found that a resist underlayer film pattern with small edge roughness can be formed by transferring a resist upper layer film pattern by dry etching to a resist underlayer film formed using a composition for forming a resist underlayer film containing a resin having an aromatic ring, and then irradiating the resist underlayer film with plasma, thereby completing the present invention.

[0034] That is, the present invention is A method for forming a resist underlayer film pattern on a substrate, comprising: (i-1) applying a composition for forming a resist underlayer film onto the substrate and then performing a heat treatment to form a resist underlayer film; (i-2) applying a silicon-containing resist intermediate film onto the resist underlayer film, followed by heat treatment to form a silicon-containing resist intermediate film; (i-3) forming a resist upper layer film on the silicon-containing resist intermediate film; (i-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; (i-5) forming a resist underlayer film pattern by performing etching a plurality of times using the resist upper layer film pattern as a mask; (i-6) a step of irradiating the resist underlayer film pattern with plasma; and The resist underlayer film-forming composition contains a resin having an aromatic ring, The pattern formation method is characterized in that the plasma used for the plasma irradiation in the step (i-6) etches the resist underlayer film less than the etching gas used in the step (i-5) of forming a resist underlayer film pattern by etching the resist underlayer film.

[0035] The present invention also provides a method for forming a resist underlayer film pattern on a substrate, comprising the steps of: (ii-1) applying a composition for forming a resist underlayer film onto the substrate and then performing a heat treatment to form a resist underlayer film; (ii-2) forming an inorganic hard mask intermediate film selected from a silicon oxide film, a silicon nitride film, and a silicon oxynitride film on the resist underlayer film; (ii-3) forming an upper layer resist film on the inorganic hard mask intermediate film; (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) forming a resist underlayer film pattern by performing etching a plurality of times using the resist upper layer film pattern as a mask; (ii-6) a step of irradiating the resist underlayer film pattern with plasma; and The resist underlayer film-forming composition contains a resin having an aromatic ring, The pattern formation method is characterized in that the plasma used for the plasma irradiation in the step (ii-6) etches the resist underlayer film less than the etching gas used in the step (ii-5) of forming a resist underlayer film pattern by etching the resist underlayer film.

[0036] The present invention will be described in detail below, but the present invention is not limited thereto.

[0037] [Pattern formation method] The present invention provides a method for forming a resist underlayer film pattern on a substrate, comprising the steps of: (i-1) applying a composition for forming a resist underlayer film onto the substrate and then performing a heat treatment to form a resist underlayer film; (i-2) applying a silicon-containing resist intermediate film onto the resist underlayer film, followed by heat treatment to form a silicon-containing resist intermediate film; (i-3) forming a resist upper layer film on the silicon-containing resist intermediate film; (i-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; (i-5) forming a resist underlayer film pattern by performing etching a plurality of times using the resist upper layer film pattern as a mask; (i-6) a step of irradiating the resist underlayer film pattern with plasma; and The resist underlayer film-forming composition contains a resin having an aromatic ring, The present invention provides a pattern formation method, characterized in that the plasma used for the plasma irradiation in the step (i-6) etches the resist underlayer film less than the etching gas used in the step (i-5) of forming a resist underlayer film pattern by etching the resist underlayer film.

[0038] In the present invention, the plasma used for the plasma irradiation in the step (i-6) must be one that etches the resist underlayer film less than the etching gas used in the step (i-5). By using a plasma used for the plasma irradiation in the step (i-6) that etches the resist underlayer film less than the etching gas used in the step (i-5), a pattern of the resist underlayer film can be obtained in the step (i-5), while preventing the pattern of the resist underlayer film formed in the step (i-6) from being damaged or lost.

[0039] Furthermore, there is provided a method for forming a resist underlayer film pattern on a substrate, comprising the steps of: (ii-1) applying a composition for forming a resist underlayer film onto the substrate and then performing a heat treatment to form a resist underlayer film; (ii-2) forming an inorganic hard mask intermediate film selected from a silicon oxide film, a silicon nitride film, and a silicon oxynitride film on the resist underlayer film; (ii-3) forming an upper layer resist film on the inorganic hard mask intermediate film; (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) forming a resist underlayer film pattern by performing etching a plurality of times using the resist upper layer film pattern as a mask; (ii-6) a step of irradiating the resist underlayer film pattern with plasma; and The resist underlayer film-forming composition contains a resin having an aromatic ring, The pattern formation method may be characterized in that the plasma used for the plasma irradiation in the step (ii-6) etches the resist underlayer film less than the etching gas used in the step (ii-5) of forming a resist underlayer film pattern by etching the resist underlayer film.

[0040] As described above, in the present invention, the plasma used for the plasma irradiation in the step (ii-6) must be one that etches the resist underlayer film less than the etching gas used in the step (ii-5). By using a plasma used for the plasma irradiation in the step (ii-6) that etches the resist underlayer film less than the etching gas used in the step (ii-5), a pattern of the resist underlayer film can be obtained in the step (ii-5), while preventing the pattern of the resist underlayer film formed in the step (ii-6) from being damaged or lost.

[0041] Specific examples of the pattern forming method of the present invention include the following pattern forming methods.

[0042] FIG. 1 shows an explanatory diagram of one example of the pattern formation method of the present invention (three-layer resist process). A resist underlayer film (3), a silicon-containing intermediate film (4), and a resist toplayer film (5) are formed on a workpiece substrate (1) having a workpiece layer (2). The resist toplayer film is exposed (6), developed, and removed by rinsing to form a resist toplayer film pattern (5a). Dry etching is performed using the resulting resist toplayer film pattern (5a) as a mask, and these are transferred to a silicon-containing intermediate film pattern (4a) and a resist underlayer film pattern (3a), followed by plasma exposure. The silicon-containing intermediate film (4b) and resist underlayer film (3b) after plasma exposure are then pattern-transferred to the workpiece layer (2) by dry etching, forming a workpiece layer pattern (2b).

[0043] FIG. 2 illustrates another example of the pattern formation method of the present invention (the sidewall spacer method). A resist underlayer film (3), a silicon-containing intermediate film (4), and a resist toplayer film (5) are formed on a substrate (1) having a workpiece layer (2). The resist toplayer film is exposed (6), developed, and then removed by rinsing to form a resist toplayer film pattern (5a). Using the resulting resist toplayer film (5a) as a mask, dry etching is performed to transfer the silicon-containing intermediate film pattern (4a) and the resist underlayer film pattern (3a), followed by plasma exposure. The silicon-containing intermediate film (4b) and the resist underlayer film (3b) after plasma exposure are covered with an inorganic silicon film (7) by CVD or ALD, followed by dry etching to remove the silicon-containing intermediate film (4b) and the resist underlayer film (3b), thereby forming an inorganic silicon film pattern (7a).

[0044] Each step will be described in detail below.

[0045] [Step (i-1), step (ii-1)] Step (i-1) and step (ii-1) are steps of forming a resist underlayer film on a substrate.

[0046] <Substrate> The substrate is a semiconductor manufacturing substrate on which a metal film, metal carbide film, metal oxide film, metal nitride film, or a composite of these films is formed as a processed layer (processed portion). etc. can be used.

[0047] Silicon substrates are generally used as substrates for semiconductor manufacturing, but there are no particular limitations. Instead, a material different from the work layer may be used, such as Si, amorphous silicon (α-Si), p-Si, SiO2, SiN, SiON, W, TiN, Al, etc. The metal constituting the work layer may be any of silicon, titanium, tungsten, hafnium, zirconium, chromium, germanium, copper, aluminum, and iron, or an alloy thereof. Examples of work layers containing such metals include Si, SiO2, SiN, SiON, SiOC, p-Si, α-Si, TiN, WSi, BPSG, SOG, Cr, CrO, CrON, MoSi, W, W-Si, Al, Cu, and Al-Si, as well as various low-dielectric films and their etching stopper films, and can be formed to a thickness of typically 50 to 10,000 nm, particularly 100 to 5,000 nm.

[0048] <Organic resist underlayer film> The organic underlayer film-forming composition used in the present invention is preferably a resin having an aromatic ring from the viewpoints of film-forming properties in spin coating, curing properties, etching resistance, optical properties, heat resistance, etc. Furthermore, when the resin contains an aromatic ring, film modification by plasma irradiation is more likely to occur, and a resist underlayer film pattern with reduced edge roughness can be formed.

[0049] Examples of the aromatic ring include benzene, naphthalene, anthracene, pyrene, indene, fluorene, furan, pyrrole, thiophene, phosphole, pyrazole, oxazole, isoxazole, thiazole, pyridine, pyrazine, pyrimidine, pyridazine, triazine, carbazole, etc. Among these, benzene, naphthalene, and fluorene are particularly preferred.

[0050] The composition for forming a resist underlayer film, (a) a polymer compound having an aromatic ring in the main chain and a weight average molecular weight of 2,500 or more and 20,000 or less in terms of polystyrene as determined by gel permeation chromatography; It is more preferable to contain (b) an aromatic ring-containing compound having a weight average molecular weight of 600 or more and 3,000 or less in terms of polystyrene as determined by gel permeation chromatography, or (A) a resin which is a combination of these.

[0051] It is more preferable that the (A) resin has at least one crosslinkable group selected from a vinyl group, an allyl group, an allyloxy group, an ethynyl group, a propargyl group, a propargyloxy group, an epoxy group, an oxetanyl group, and a hydroxyl group.

[0052] Since the resin (A) having the crosslinkable group has excellent curability, a pattern formation method using a composition for forming a resist underlayer film containing the resin (A) can form a dense resist underlayer film pattern. The resist underlayer film pattern obtained thereby is more susceptible to modification by plasma irradiation, and a resist underlayer film pattern with good edge roughness can be formed.

[0053] Examples of resins having an aromatic ring that can be used in the present invention include resins containing the following structures described in JP-A Nos. 2012-1687 and 2012-77295. [ka] (In formula (1), the ring structures Ar1 and Ar2 represent a benzene ring or a naphthalene ring. X represents a single bond or an alkylene group having 1 to 20 carbon atoms. m represents 0 or 1. n represents any natural number such that the molecular weight is 100,000 or less. Note that the symbols in the formula apply only within this formula.)

[0054] [ka] (In formula (2), the ring structures Ar1 and Ar2 represent a benzene ring or a naphthalene ring. n represents any natural number such that the weight average molecular weight, as calculated using polystyrene standards by gel permeation chromatography, is 100,000 or less. Note that the symbols in the formula are used only within this formula.)

[0055] Further examples of resins having an aromatic ring that can be used in the present invention include resins containing the following structures described in JP-A Nos. 2004-264710, 2005-043471, 2005-250434, 2007-293294, and 2008-65303. [ka] (In formula (3) and formula (4), R 1 and R 2 represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or an aryl group; R 3 represents an alkyl group having 1 to 3 carbon atoms, a vinyl group, an allyl group, or an aryl group which may be substituted, n represents 0 or 1, and m represents 0, 1, or 2. The symbols in the formulae apply only within the formulae.

[0056] [ka] (In formula (5), R1 is a monovalent atom or group other than a hydrogen atom, and n is an integer of 0 to 4. However, when n is 2 to 4, multiple R1s may be the same or different. R2 and R3 are independently a monovalent atom or group. X is a divalent group. Note that the symbols in the formula apply only within this formula.)

[0057] [ka] (In formula (6), R 1 is a hydrogen atom or a methyl group. 2 R is a single bond, a linear, branched or cyclic alkylene group having 1 to 20 carbon atoms, or an arylene group having 6 to 10 carbon atoms, and may have an ether, ester, lactone or amide.3 , R 4 are each a hydrogen atom or a glycidyl group. X represents a polymer of any one of hydrocarbons containing an indene skeleton, cycloolefins having 3 to 10 carbon atoms, and maleimide, and may have any one of ethers, esters, lactones, and carboxylic acid anhydrides. R 5 , R 6 R is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 7 is a hydrogen atom, a linear, branched, or cyclic alkyl group having 1 to 6 carbon atoms, a hydroxy group, or an alkoxycarbonyl group. p and q are each an integer of 1 to 4. r is an integer of 0 to 4. a, b, and c are in the ranges of 0.5≦a+b+c≦1, 0≦a≦0.8, 0≦b≦0.8, 0.1≦a+b≦0.8, and 0.1≦c≦0.8, respectively. Note that the symbols in the formula apply only within this formula.

[0058] [ka] (In formula (7), R1 represents a hydrogen atom or a monovalent organic group, and R2 and R3 each independently represent a monovalent atom or a monovalent organic group. Note that the symbols in the formula apply only within this formula.)

[0059] Specific examples of resins having an aromatic ring that can be used in the present invention include resins containing the following structures described in JP-A Nos. 2004-205685, 2007-171895, and 2009-14816. [ka] (In formula (8) and formula (9), R 1 ~R 8 are each independently a hydrogen atom, a hydroxyl group, an optionally substituted alkyl group having 1 to 6 carbon atoms, an optionally substituted alkoxy group having 1 to 6 carbon atoms, an optionally substituted alkoxycarboxyl group having 2 to 6 carbon atoms, an optionally substituted aryl group having 6 to 10 carbon atoms, a hydroxyalkyl group having 1 to 6 carbon atoms, an isocyanate group, or a glycidyl group. m and n are positive integers. Note that the symbols in the formula apply only within this formula.

[0060]

Chem.

[0061]

Chem.

[0062] For example, the following compounds are exemplified. [ka]

[0063] Examples of resins having an aromatic ring that can be used in the present invention include resins containing the following structures described in JP-A Nos. 2007-199653, 2008-274250, and 2010-122656. [ka] (In formula (12), R 1 and R 2 are independently the same or different hydrogen atoms, linear, branched or cyclic alkyl groups having 1 to 10 carbon atoms, aryl groups having 6 to 10 carbon atoms, or alkenyl groups having 2 to 10 carbon atoms, and R 3 is a single bond or an alkylene group having a linear, branched or cyclic structure and having 1 to 30 carbon atoms, which may have a bridged cyclic hydrocarbon group, a double bond, a heteroatom or an aromatic group having 6 to 30 carbon atoms; R 4 and R 5 are each independently a hydrogen atom or a glycidyl group, and n is an integer of 1 to 4. The symbols in the formula are applicable only within this formula.

[0064] [ka] (In formula (13), R1 and R 2 are independently the same or different hydrogen atoms, linear, branched or cyclic alkyl groups having 1 to 10 carbon atoms, aryl groups having 6 to 10 carbon atoms, or alkenyl groups having 2 to 10 carbon atoms, and R 3 is a single bond or an alkylene group having a linear, branched or cyclic structure and having 1 to 30 carbon atoms, which may have a bridged cyclic hydrocarbon group, a double bond, a heteroatom or an aromatic group having 6 to 30 carbon atoms; R 4 and R 5 are each independently a hydrogen atom or a glycidyl group, and R 6 is a single bond or a linear or branched alkylene group having 1 to 10 carbon atoms. The symbols in the formula are only applicable within this formula.

[0065] [ka] (In formula (14), ring Z 1 and ring Z 2 is a fused polycyclic aromatic hydrocarbon ring, R 1a , R 1b , R 2a , and R 2b are the same or different and represent a substituent. k1 and k2 are the same or different and represent an integer of 0 or 1 to 4, m1 and m2 are each an integer of 0 or 1 or more, and n1 and n2 are each an integer of 0 or 1 or more, provided that n1+n2≧1. The symbols in the formulae are only applicable within this formula.

[0066] [ka] (In formula (15), R 1 , R 2 are the same or different and are hydrogen atoms, linear, branched or cyclic alkyl groups having 1 to 10 carbon atoms, aryl groups having 6 to 10 carbon atoms, or alkenyl groups having 2 to 10 carbon atoms. 3 , R 4 are hydrogen atoms or glycidyl groups, and R 5 is a single bond or a linear or branched alkylene group having 1 to 10 carbon atoms, and R 6 , R 7It is a benzene ring or a naphthalene ring. p and q are each 1 or 2. n satisfies 0 < n ≤ 1. Note that the symbols in the formula are applicable only within this formula.)

[0067] For example, the following compounds are exemplified.

Chemical formula

[0068]

Chemical formula

[0069]

Chemical formula

[0070]

Chemical formula

[0071] Examples of the resin having an aromatic ring applicable to the present invention include resins described in JP-A-2014-29435, International Publication WO2012 / 077640, and International Publication WO2010 / 147155.

Chemical formula

[0072] In addition, a polymer containing a unit structure represented by the following formula (18) and a unit structure represented by the following formula (19) described in International Publication WO2012 / 077640, and having a molar ratio of the unit structure represented by formula (18) to the unit structure represented by formula (19) of 3 to 97:97 to 3 can be exemplified. [ka] In formula (18), R1 and R2 each independently represent a hydrogen atom, a halogen atom, a nitro group, an amino group, a hydroxy group, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an aryl group having 6 to 40 carbon atoms, or a combination of these groups which may contain an ether bond, a ketone bond, or an ester bond. R3 represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an aryl group having 6 to 40 carbon atoms, or a combination of these groups which may contain an ether bond, a ketone bond, or an ester bond. represents a combination of these groups. R4 represents a hydrogen atom, or an aryl group having 6 to 40 carbon atoms which may be substituted with a halogen atom, a nitro group, an amino group, or a hydroxy group, or a heterocyclic group; R5 represents a hydrogen atom, or an alkyl group having 1 to 10 carbon atoms which may be substituted with a halogen atom, a nitro group, an amino group, or a hydroxy group, or an aryl group having 6 to 40 carbon atoms, or a heterocyclic group; R4 and R5 may together form a ring; n1 and n2 each represent an integer of 1 to 3; and the symbols in the formula are applicable only within this formula.

[0073] [ka] In formula (19), Ar represents an aromatic ring group having 6 to 20 carbon atoms, R6 represents a hydroxy group, R7 represents a hydrogen atom, a halogen atom, a nitro group, an amino group, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an aryl group having 6 to 40 carbon atoms, or a combination of these groups which may contain an ether bond, a ketone bond, or an ester bond, and R8 may be substituted with a hydrogen atom, a halogen atom, a nitro group, an amino group, or a hydroxy group. R8 represents an aryl group or heterocyclic group having 6 to 40 carbon atoms, R9 represents a hydrogen atom, or an alkyl group having 1 to 10 carbon atoms which may be substituted with a halogen atom, a nitro group, an amino group, or a hydroxy group, or an aryl group or heterocyclic group having 6 to 40 carbon atoms, and R8 and R9 may together form a ring. n6 represents an integer of 1 to p, and n7 represents an integer of p-n6, where p represents the maximum number of substituents that can be substituted on the aromatic ring group Ar. The symbols in the formula are only applicable within this formula.

[0074] An example of a resin having an aromatic ring that can be used in the present invention is a polymer containing a unit structure represented by the following formula (20), which is described in International Publication WO2010 / 147155. [ka] (In formula (20), R1 and R2 are each selected from the group consisting of a hydrogen atom, a halogen group, a nitro group, an amino group, a hydroxy group, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an aryl group having 6 to 40 carbon atoms, and combinations thereof, and the alkyl group, the alkenyl group, or the aryl group represents a group which may contain an ether bond, a ketone bond, or an ester bond; R3 is selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an aryl group having 6 to 40 carbon atoms, and combinations thereof, and the alkyl group, the alkenyl group Alternatively, the aryl group represents a group which may contain an ether bond, a ketone bond, or an ester bond; R4 represents an aryl group or heterocyclic group having 6 to 40 carbon atoms which may be substituted with a halogen group, a nitro group, an amino group, or a hydroxy group; R5 represents a hydrogen atom, or an alkyl group having 1 to 10 carbon atoms, an aryl group or a heterocyclic group having 6 to 40 carbon atoms which may be substituted with a halogen group, a nitro group, an amino group, or a hydroxy group; R4 and R5 may form a ring together with the carbon atoms to which they are bonded; and n1 and n2 are each an integer of 1 to 3. Note that the symbols in the formula apply only within this formula.

[0075] Examples of resins having an aromatic ring that can be used in the present invention include novolak resins obtained by reacting one or more phenols, such as phenol, cresol, xylenol, catechol, resorcinol, hydroquinone, pyrogallol, hydroxyquinol, and phloroglucinol, with one or more aldehyde sources, such as formaldehyde, paraformaldehyde, and trioxane, using an acidic catalyst; and resins containing a repeating unit structure represented by the following formula (21), which is described in International Publication WO2012 / 176767. [ka] (In formula (21), A represents a hydroxy-substituted phenylene group derived from polyhydroxybenzene, and B represents a monovalent fused aromatic hydrocarbon ring group in which 2 to 6 benzene rings are fused. Note that the symbols in the formula apply only within this formula.)

[0076] Examples of resins having an aromatic ring that can be used in the present invention include novolak resins having a fluorene or tetrahydrospirobiindene structure, as described in JP-A Nos. 2005-128509, 2006-259249, 2006-259482, 2006-293298, and 2007-316282, which contain a repeating unit structure represented by the following formula (22-1) or (22-2): [ka] (In formula (22-1) and formula (22-2), R 1 , R 2 , R 6 , R 7 are independently a hydrogen atom, a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, an allyl group, or a halogen atom; R 3 , R 4 , R 8 , R 9 are independently a hydrogen atom, a linear, branched or cyclic alkyl group having 1 to 6 carbon atoms, a linear, branched or cyclic alkenyl group having 2 to 6 carbon atoms, an aryl group having 6 to 10 carbon atoms or a glycidyl group, and R 5 , R 14 are independently a hydrogen atom, a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 10 carbon atoms. n, m, p and q are integers of 1 to 3. R 10 ~R 13 are independently a hydrogen atom, a halogen atom, a hydroxy group, a linear, branched or cyclic alkyl group having 1 to 6 carbon atoms, or a linear, branched or cyclic alkoxy group having 1 to 6 carbon atoms. Note that the symbols in the formula apply only within this formula.)

[0077] An example of a resin having an aromatic ring that can be used in the present invention is a reaction product obtained by the method described in JP-A-2012-145897. More specifically, examples of the polymers include those obtained by condensing one or more compounds represented by the following general formula (23-1) and / or (23-2) with one or more compounds represented by the following general formula (24-1) and / or (24-2) and / or their equivalents. [ka] (In formula (23-1) and formula (23-2), R 1 ~R 8 are each independently a hydrogen atom, a halogen atom, a hydroxyl group, an isocyanato group, a glycidyloxy group, a carboxyl group, an amino group, an alkoxy group having 1 to 30 carbon atoms, an alkoxycarbonyl group having 1 to 30 carbon atoms, an alkanoyloxy group having 1 to 30 carbon atoms, or an optionally substituted saturated or unsaturated organic group having 1 to 30 carbon atoms. 1 ~R 4 or R 5 ~R 8 Two substituents arbitrarily selected from the following may be bonded to form a cyclic substituent. The symbols in the formula are applicable only within this formula.) [ka] (In formula (24-1) and formula (24-2), Q is an organic group having 1 to 30 carbon atoms which may be substituted, and two Qs arbitrarily selected in the molecule may be bonded to form a cyclic substituent. n1 to n6 are the numbers of each substituent, and n1 to n6 = 0, 1, 2, and hydroxybenzaldehyde is excluded in formula (24-1). In formula (24-2), the relationships 0≦n3+n5≦3, 0≦n4+n6≦4, 1≦n3+n4≦4 are satisfied. Note that the symbols in the formulas apply only within this formula.)

[0078] Further, examples of the polymers include those obtained by condensing one or more compounds represented by the above general formula (23-1) and / or (23-2), one or more compounds represented by the above general formula (24-1) and / or (24-2) and / or equivalents thereof, and one or more compounds represented by the following general formula (25) and / or equivalents thereof. [ka] (In formula (25), Y is a hydrogen atom or a monovalent organic group having 30 or less carbon atoms which may have a substituent, and formula (25) is different from formula (24-1) and formula (24-2). Note that the symbols in the formula apply only within this formula.)

[0079] Examples of resins having an aromatic ring that can be used in the present invention include polymers having a repeating unit represented by the following general formula (27-1), which are described in JP-A-2019-44022. [ka] In formula (27-1), AR1 and AR2 are benzene rings or naphthalene rings which may have a substituent, and R 1 , R 2 are each independently a hydrogen atom or an organic group having 1 to 30 carbon atoms, and R 1 and R 2 If is an organic group, R 1 and R 2 may form a cyclic organic group by bonding intramolecularly. n is 0 or 1, and when n=0, AR1 and AR2 do not form a bridged structure between the aromatic rings of AR1 and AR2 via Z, and when n=1, AR1 and AR2 form a bridged structure between the aromatic rings of AR1 and AR2 via Z, and Z is either a single bond or the following formula (27-2). Y is a group represented by the following formula (27-3). Note that the symbols in the formula apply only within this formula. [ka] [ka] (In the formula, R3 is a single bond or a divalent organic group having 1 to 20 carbon atoms, and R 4 represents a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms, and the dashed line represents a bond. Note that the symbols in the formula are only applicable within this formula.

[0080] For example, the following polymers are exemplified. [ka]

[0081] [ka]

[0082] The resin having an aromatic ring may be synthesized by a known method, or a commercially available product may be used.

[0083] Examples of resins having an aromatic ring that can be used in the present invention include resins containing the following structure described in JP-A-2012-214720. [ka] (In formula (16), the ring structures Ar1 and Ar2 represent a benzene ring or a naphthalene ring. x and z each independently represent 0 or 1. Note that the symbols in the formula apply only within this formula.)

[0084] Examples of resins having an aromatic ring that can be used in the present invention include resins containing the following structure described in JP-A-2017-119671. [ka] (In formula (26-1), R is a single bond or an organic group having 1 to 50 carbon atoms, X is a group represented by the following general formula (26-2), and m1 is an integer satisfying 2≦m1≦10. Note that the symbols in the formula apply only within this formula.) [ka] (In the formula, X2 is a divalent organic group having 1 to 10 carbon atoms, n1 is 0 or 1, n2 is 1 or 2, and X 3 is a group represented by the following general formula (26-3), and n5 is 0, 1, or 2. The symbols in the formula apply only within this formula. [ka] (In the formula, R 10 is a hydrogen atom or a saturated or unsaturated hydrocarbon group having 1 to 10 carbon atoms, and the hydrogen atom on the benzene ring in the formula may be substituted with a methyl group or a methoxy group. Note that the symbols in the formula apply only within this formula.

[0085] For example, the following compounds are exemplified. [ka]

[0086] The method for coating the composition for forming a resist underlayer film in the steps (i-1) and (ii-1) is not particularly limited. Details of the composition for forming a resist underlayer film will be described later.

[0087] In the above steps (i-1) and (ii-1), the heat treatment (baking) temperature of the coating film is from 100°C to 800°C, more preferably from 150°C to 600°C, even more preferably from 150°C to 450°C, and even more preferably from 200°C to 400°C. The baking time is in the range of 10 to 7,200 seconds, more preferably from 30 to 600 seconds.

[0088] By adjusting the bake temperature and time within the above ranges, it is possible to obtain the planarization and filling characteristics, as well as curing characteristics such as dry etching resistance and heat resistance, that are appropriate for the application. Heat treatment (baking) within a temperature range of 150°C to 600°C results in a high concentration of active sites in the underlayer film where carbon bonds dissociate and recombine, facilitating film modification by plasma irradiation, resulting in the formation of a resist underlayer film pattern with minimal edge roughness after plasma irradiation. Baking temperatures of 100°C or higher reduce residual solvent in the film and suppress deterioration due to film shrinkage caused by plasma irradiation. Baking temperatures of 800°C or lower suppress thermal decomposition of the base resin, resulting in a resist underlayer film with minimal sublimation. Multiple heating steps (step baking) are also possible.

[0089] In the above steps (i-1) and (ii-1), the heat treatment can be carried out in an atmosphere with an oxygen concentration of 1% or more and 21% or less.

[0090] By using such a method, reactive points of the resin in the resist underlayer film can be activated, and the curing reaction caused by plasma irradiation can be accelerated.

[0091] Alternatively, in the steps (i-1) and (ii-1), the heat treatment can be carried out in an atmosphere with an oxygen concentration of less than 1%.

[0092] The atmosphere during baking can be selected as needed from either an oxygen-containing atmosphere such as air (oxygen concentration 1% to 21%) or an oxygen-free atmosphere such as nitrogen. For example, if the substrate to be processed is susceptible to air oxidation, substrate damage can be suppressed by forming a hardened film by heat treating in an atmosphere with an oxygen concentration of less than 1%.

[0093] In the steps (i-1) and (ii-1), the resist underlayer film may be exposed to plasma after baking. The plasma exposure step is described below.

[0094] In the pattern forming method of the present invention, plasma irradiation may be performed in a plurality of steps, including after forming the resist underlayer film and after forming the resist underlayer film pattern. By using the method, modification of the resist underlayer film pattern can be further promoted.

[0095] [Process (i-2)] The step (i-2) is a step of forming a silicon-containing resist intermediate film on the resist underlayer film.

[0096] <Silicon-containing resist interlayer> The silicon-containing resist interlayer (silicon-containing coating-type interlayer) used in the pattern forming method of the present invention is not particularly limited. Although many silicon-containing interlayers are known that can be used here, in the present invention, when the resist underlayer film pattern is one in which the silicon-containing resist interlayer remains on the resist underlayer film, the dry-etched silicon-containing film residue and the resist underlayer film must be simultaneously washed and removed with a stripping solution. Therefore, the silicon content in the silicon-containing resist interlayer is preferably 45% by weight or less, more preferably 40% by weight or less, and particularly preferably 35% by weight or less.

[0097] The silicon-containing resist intermediate film is preferably formed from a silicon-containing resist intermediate film composition that contains a compound having a crosslinkable organic structure.

[0098] In this case, cleaning with a stripping solution after dry etching can be performed more reliably. This results in a silicon-containing resist intermediate film that can be removed simultaneously with the resist underlayer film.

[0099] In this case, the crosslinkable organic structure may be an oxirane ring, an oxetane ring, a hydroxyl group, or a carboxyl group. It is preferable to use one or more types selected from the group.

[0100] Such a crosslinkable organic structure results in a silicon-containing resist intermediate film that can be more reliably removed simultaneously with the resist underlayer film by washing with a stripping solution after dry etching.

[0101] It is also preferable that the composition for forming a silicon-containing resist intermediate film further contains an acid generator that generates an acid in response to either heat or light, or both.

[0102] It is also preferable that the composition for forming a silicon-containing resist intermediate film further contains a crosslinking agent.

[0103] Such a composition for forming a silicon-containing resist interlayer film promotes crosslinking of the oxirane ring, oxetane ring, hydroxyl group, carboxyl group, and the like contained as the crosslinkable organic structure, and also enables the formation of a silicon-containing resist interlayer film that can be reliably washed away together with the resist underlayer film even after dry etching.

[0104] The composition for forming such a silicon-containing resist intermediate film and the resin used in the composition are not particularly limited, but examples include the resins and compositions disclosed in JP-A Nos. 2004-310019, 2005-15779, 2005-18054, 2005-352104, and 2007-226170.

[0105] Specific examples of resins contained in the composition for forming a silicon-containing resist interlayer film used in the present invention include polysiloxanes containing one or more of compounds represented by the following general formula (A-1), their hydrolysates, their condensates, and their hydrolyzed condensates: [ka] (In the formula, R 0A is a hydrocarbon group having 1 to 6 carbon atoms, and R 1A , R 2A , R 3A is a hydrogen atom or a monovalent organic group. A1, A2, and A3 are 0 or 1, and 0≦A1+A2+A3≦3.

[0106] This R 1A , R 2A , R 3AExamples of organic groups represented by the formula (A-1) include organic groups having one or more carbon-oxygen single bonds or carbon-oxygen double bonds. Specifically, they are organic groups having one or more groups selected from the group consisting of an oxirane ring, an oxetane ring, an ester bond, an alkoxy group, and a hydroxyl group. Examples of such organic groups include those represented by the following general formula (A-2): [ka] (In general formula (A-2), P represents a hydrogen atom, an oxirane ring, an oxetane ring, a hydroxyl group, an alkoxy group having 1 to 4 carbon atoms, an alkylcarbonyloxy group having 1 to 6 carbon atoms, or an alkylcarbonyl group having 1 to 6 carbon atoms; Q1, Q2, Q3, and Q4 each independently represent -CqH(2q-p)Pp- (wherein P is as defined above, p represents an integer of 0 to 3, and q represents an integer of 0 to 10 (wherein q=0 represents a single bond)); u represents an integer of 0 to 3; S1 and S2 each independently represent -O- , -CO-, -OCO-, -COO-, or -OCOO-. v1, v2, and v3 each independently represent 0 or 1. Together with these, T is a divalent group consisting of an alicyclic or aromatic ring which may contain a heteroatom and an oxirane ring or an oxetane ring, and examples of the alicyclic or aromatic ring of T which may contain a heteroatom such as an oxygen atom are shown below. The positions at which Q2 and Q3 are bonded in T are not particularly limited, but can be appropriately selected taking into consideration reactivity due to steric factors, the availability of commercially available reagents used in the reaction, etc.

[0107] [Step (ii-2)] The step (ii-2) is a step of forming an inorganic hard mask intermediate film selected from a silicon oxide film, a silicon nitride film, and a silicon oxynitride film on the resist underlayer film.

[0108] <Inorganic hard mask interlayer> When forming an inorganic hard mask intermediate film on a resist underlayer 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 JP 2002-334869 A and WO 2004 / 066377 A. The thickness of the inorganic hard mask intermediate film is preferably 5 to 200 nm, more preferably 10 to 100 nm. Furthermore, a SiON film, which has a high anti-reflective coating effect, is most preferably used as the inorganic hard mask intermediate film. Since the substrate temperature during the formation of the SiON film is 300 to 500°C, the resist underlayer film must be able to withstand temperatures of 300 to 500°C. The resist underlayer 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 intermediate film formed by a CVD method or an ALD method with a resist underlayer film formed by a spin coating method.

[0109] A photoresist film can be formed on the inorganic hard mask intermediate film as a resist top layer, or an organic antireflective coating (BARC) or adhesion film can be formed on the inorganic hard mask intermediate film 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 intermediate film, the two-layer antireflective coating consisting of the SiON film and the BARC can suppress reflection even in immersion exposure 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.

[0110] [Steps (i-3) and (ii-3)] Steps (i-3) and (ii-3) are steps for forming a resist top layer film.

[0111] <Resist top layer> The resist upper layer film that can be used in the pattern forming method of the present invention is not particularly limited. Any of various conventionally known resist films can be used.

[0112] In the pattern formation method, the resist top layer film may be either positive or negative, and the same photoresist composition as commonly used may be used. The photoresist composition may also contain metal atoms such as Sn, In, Ga, Ge, Al, Ce, La, Cs, Zr, Hf, Ti, Bi, Sb, and Zn. When forming the resist top layer film using the photoresist composition, it may be formed by spin coating or by vapor deposition using CVD or ALD.

[0113] When forming a photoresist composition by spin coating, the resist is prebaked after application, preferably at 60 to 180°C for 10 to 300 seconds. Then, 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 10 to 500 nm, and more preferably 20 to 400 nm.

[0114] When a photoresist composition is formed by deposition using CVD or ALD, the resist composition is an EUV-sensitive metal oxide film, and the metal is selected from Sn, Zr, Hf, Ti, Bi, Sb, etc., with Sn being preferred due to its excellent EUV sensitivity. The metal oxide-containing film may be a photosensitive organometallic oxide film such as an organotin oxide (e.g., haloalkyltin, alkoxyalkyltin, or amidoalkyltin). Specific examples of suitable precursors include trimethyltin chloride, dimethyltin dichloride, methyltin trichloride, tris(dimethylamino)methyltin(IV), and (dimethylamino)trimethyltin(IV).

[0115] Metal oxide films may be deposited by PECVD or PEALD, for example, using a Lam Vector® tool. In the ALD example, the Sn oxide precursor is separated from the O precursor / plasma. The deposition temperature is preferably in the range of 50°C to 600°C. The deposition pressure is preferably between 100 and 6000 mTorr. The metal oxide-containing film precursor liquid flow rate (e.g., organotin oxide precursor) may be 0.01 to 10 cm³, and the gas flow rate (CO₂, CO₂, Ar, N₂) may be 100 to 10,000 sccm. The plasma power may be 200 to 1,000 W per 300 mm wafer station using a high-frequency plasma (e.g., 13.56 MHz, 27.1 MHz, or higher). The deposition thickness is preferably 100 to 2,000 Å.

[0116] <Water repellent coating film> In addition, when forming the resist upper layer film pattern, immersion exposure is used. When a protective film for the resist upper layer is required, a water-repellent coating film may be further formed on the resist upper layer film. The water-repellent coating film is not particularly limited, and various types can be used.

[0117] [Steps (i-4) and (ii-4)] Steps (i-4) and (ii-4) are steps 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.

[0118] Examples of exposure light include high energy rays with wavelengths of 300 nm or less, specifically soft X-rays, electron beams, X-rays, and the like with wavelengths of 248 nm, 193 nm, and 3 to 20 nm.

[0119] 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.

[0120] In the pattern forming method, the development method is preferably alkaline development or development using an organic solvent.

[0121] [Steps (i-5) and (ii-5)] Steps (i-5) and (ii-5) are steps of forming a resist underlayer film pattern by performing etching multiple times using the resist upper layer film pattern as a mask.

[0122] Steps (i-5) and (ii-5) are steps of transferring the resist upper layer film pattern to a silicon-containing intermediate film or an inorganic hard mask intermediate film by dry etching using the resist upper layer film on which the resist upper layer film pattern has been formed as a mask, and further transferring the resist upper layer film pattern to a resist underlayer film by dry etching using the silicon-containing resist intermediate film or inorganic hard mask intermediate film on which the resist upper layer film pattern has been transferred as a mask, thereby forming a resist underlayer film pattern.

[0123] In steps (i-5) and (ii-5), when the resist upper layer film pattern is used as an etching mask and the silicon-containing resist intermediate film or the inorganic hard mask intermediate film is etched under dry etching conditions under which the etching rate of the silicon-containing resist intermediate film and the inorganic hard mask intermediate film is dominantly higher than that of the resist upper layer film pattern, for example, dry etching using a fluorine-based gas plasma, the resist upper layer film pattern can be transferred to the silicon-containing resist intermediate film or the inorganic hard mask intermediate film with almost no effect of pattern changes due to side etching of the resist film.

[0124] Next, the resist underlayer film is etched under dry etching conditions that result in a superior etching rate for the resist underlayer film relative to the silicon-containing resist intermediate film or inorganic hard mask intermediate film to which the resist upper layer film pattern has been transferred, such as reactive dry etching using an oxygen-containing gas plasma or reactive dry etching using a hydrogen-nitrogen-containing gas plasma.

[0125] This etching step yields a resist underlayer film pattern. At the same time, the top resist layer is usually lost, but a portion of the silicon-containing resist interlayer or inorganic hard mask interlayer that served as an etching mask may remain on top of the resist underlayer film pattern, as described below.

[0126] In the steps (i-5) and (ii-5), the resist underlayer film pattern may be one in which the silicon-containing resist interlayer film or the inorganic hard mask interlayer film remains on the resist underlayer film.

[0127] Alternatively, in steps (i-5) and (ii-5), the resist underlayer film pattern may be one in which the silicon-containing resist interlayer film or the inorganic hard mask interlayer film does not remain on the resist underlayer film.

[0128] The pattern formation method of the present invention makes it possible to form an inorganic silicon film pattern (sidewall pattern) without damaging the sidewall or substrate, regardless of whether or not there is a residue of the mask material after pattern transfer by dry etching.

[0129] In addition, in the actual semiconductor device manufacturing process, the pattern transfer of a multilayer resist by dry etching is often performed under conditions in which a portion of the mask pattern material remains on top of the transferred pattern in order to ensure the rectangular shape of the pattern after dry etching. That is, in the pattern formation method of the present invention, when a pattern is transferred to a silicon-containing resist intermediate film by dry etching using a resist top layer film as a mask, the process can be carried out under conditions in which a portion of the resist top layer film remains in order to ensure the rectangular shape of the cross-sectional shape of the pattern of the silicon-containing resist intermediate film. Similarly, when a pattern is transferred to a resist underlayer film using a silicon-containing resist intermediate film as a mask, the pattern transfer process can be carried out under conditions in which a portion of the silicon-containing resist intermediate film or inorganic hard mask intermediate film remains on top of the resist underlayer film in order to ensure the rectangular shape of the cross-sectional shape of the pattern of the resist underlayer film. Then, using this resist underlayer film pattern as a core material, a sidewall spacer method is performed, i.e., sidewalls are formed with an inorganic silicon film, and the resist underlayer film pattern is then removed to form an inorganic silicon film pattern. However, when attempting to remove the silicon-containing resist interlayer film residue or inorganic hard mask interlayer film residue remaining on the top of the resist underlayer film pattern by dry etching, the sidewalls and substrate formed of the inorganic silicon film are damaged by the dry etching, resulting in problems of deterioration in product performance and reduced yield. Therefore, in the pattern formation method of the present invention, it is preferable to avoid such problems by performing a wet treatment with a stripping solution to remove the silicon-containing resist interlayer film, as described below.

[0130] When the silicon-containing resist intermediate film is removed with a stripping solution, the stripping solution is not particularly limited as long as it is a basic solution, an acidic solution, or the like.

[0131] The acid-containing removal solution is not particularly limited as long as it is an acidic solution containing an acid, but one containing one or both of hydrogen fluoride, hydrogen peroxide, and sulfuric acid is preferred, and more specifically, an aqueous solution containing hydrochloric acid and hydrogen peroxide (SC-2 chemical solution), an aqueous solution containing sulfuric acid and hydrogen peroxide (SPM chemical solution), or an aqueous solution containing hydrofluoric acid and hydrogen peroxide (FPM chemical solution) is particularly preferred.

[0132] The base-containing removal solution is not particularly limited as long as it is a basic solution containing a base. Examples of bases include sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, dimethylethanolamine, triethanolamine, tetramethylammonium hydroxide (hereinafter also referred to as "TMAH"), tetraethylammonium hydroxide, pyrrole, piperidine, choline, 1,8-diazabicyclo[5.4.0]-7-undecene, and 1,5-diazabicyclo[4.3.0]-5-nonene. Among these, tetramethylammonium hydroxide (hereinafter also referred to as "TMAH") or ammonia is preferred from the viewpoint of avoiding damage to the substrate.

[0133] The base-containing removal liquid is preferably a liquid containing a base and water, or a liquid containing a base, hydrogen peroxide, and water. More specifically, a mixed aqueous solution of ammonia and hydrogen peroxide (a mixed aqueous solution of 25% ammonia aqueous solution / 30% hydrogen peroxide aqueous solution / water=1 / 2 / 40, a mixed aqueous solution of 25% ammonia aqueous solution / 30% hydrogen peroxide aqueous solution / water=1 / 1 / 5, etc. (SC1)) is particularly preferred.

[0134] To promote peeling, it is more preferable to adjust the pH by adding an acid or alkali. Examples of pH adjusters include inorganic acids such as hydrochloric acid and sulfuric acid, organic acids such as acetic acid, oxalic acid, tartaric acid, citric acid, and lactic acid, nitrogen-containing alkalis such as ammonia, ethanolamine, and tetramethylammonium hydroxide, and nitrogen-containing organic acid compounds such as EDTA (ethylenediaminetetraacetic acid).

[0135] The stripping solution is usually an aqueous solution, but may contain an organic solvent in some cases. Examples of the organic solvent include water-soluble alcohols, ethers, ketones, esters, amides, and imides. Specific examples include methanol, ethanol, propanol, butanol, ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, ethylene glycol methyl ether, ethylene glycol dimethyl ether, ethylene glycol ethyl ether, ethylene glycol ethyl ether, diethylene glycol methyl ether, diethylene glycol dimethyl ether, diethylene glycol ethyl ether, diethylene glycol diethyl ether, propylene glycol methyl ether, propylene glycol dimethyl ether, propylene glycol ethyl ether, propylene glycol ethyl ether, dipropylene glycol methyl ether, dipropylene glycol dimethyl ether, dipropylene glycol ethyl ether, dipropylene glycol diethyl ether, tetrahydrofuran, tetrahydrofurfuryl alcohol, acetone, methyl ethyl ketone, ethyl lactate, N-methylpyrrolidinone, N,N-dimethylformamide, and N,N-dimethylacetamide.

[0136] The wet stripping method is not particularly limited as long as it allows the silicon wafer on which the substrate to be processed is formed to come into contact with the stripping solution for a certain period of time under heated conditions, and examples include a method of immersing the silicon wafer on which the substrate to be processed is formed in heated alkaline hydrogen peroxide solution, a method of spraying alkaline hydrogen peroxide solution in a heated environment, a method of coating heated alkaline hydrogen peroxide solution, etc. After each of these methods, the substrate may be washed with water and dried.

[0137] The lower limit of the wet peeling temperature is preferably 23°C, more preferably 40°C, and more preferably 50°C. The upper limit of the temperature is preferably 100°C, and more preferably 90°C.

[0138] In the immersion method, the lower limit of the immersion time is preferably 1 second, more preferably 10 seconds, even more preferably 20 seconds, and particularly preferably 30 seconds. From the viewpoint of suppressing the influence on the substrate, the upper limit of the immersion time is preferably 60 minutes, more preferably 30 minutes, even more preferably 20 minutes, and particularly preferably 10 minutes.

[0139] The removal of the silicon-containing resist intermediate film remaining on the resist underlayer film pattern using a stripping solution may be carried out either before or after plasma irradiation.

[0140] When the silicon-containing resist intermediate film is removed before the plasma exposure, it becomes possible to improve the edge roughness of the resist underlayer film pattern, which deteriorates due to wet stripping, by the plasma exposure.

[0141] When the silicon-containing resist interlayer film is removed after plasma irradiation, the resistance of the resist underlayer film pattern to the stripping solution is improved, making it possible to suppress deterioration of the edge roughness of the resist underlayer film pattern due to wet stripping. Because the resistance of the resist underlayer film pattern to the stripping solution is improved by plasma irradiation, it is more preferable to perform wet stripping of the silicon-containing resist interlayer film after the plasma irradiation of the resist underlayer film pattern.

[0142] [Steps (i-6) and (ii-6)] Steps (i-6) and (ii-6) are steps of irradiating the resist underlayer film pattern with plasma.

[0143] In the steps (i-6) and (ii-6), plasma irradiation can be performed by a known method, such as the method described in Japanese Patent No. 5746670, "Improvement of the wiggling profile of spin-on carbon hard mask by H plasma treatment" (J.Vac.Sci.Technol. B26 (1), Jan / Feb 2008, pp. 67-71).

[0144] In the steps (i-6) and (ii-6), the plasma used for plasma irradiation needs to be one that etches the resist underlayer film less than the etching gas used in the steps (i-5) and (ii-5) of etching the resist underlayer film to form a resist underlayer film pattern.

[0145] The RF discharge power is preferably 100 to 10,000 W, and more preferably 500 to 5,000 W.

[0146] Examples of gas atmospheres include rare gases such as N2, NF3, H2, and He, and fluorocarbons, and more preferably He, Ar, N2, Ne, NF3, H2, CF4, CHF3, CH2F2, CH3F, C4F6, and C4F8. Two or more of these gases may be mixed for use. An advantage of the present invention is that the effects of the present invention can be expected even when a gas atmosphere that does not contain O2 is used.

[0147] The plasma irradiation time can be selected from the range of, for example, 10 to 240 seconds, and the pressure can be selected appropriately.

[0148] In the above steps (i-6) and (ii-6), the plasma irradiation is preferably carried out in an atmosphere of N2, NF3, H2, a fluorocarbon, a rare gas such as He, or a mixture of any of these.

[0149] From the viewpoint of productivity, particularly preferred gas atmospheres include He, Ar, N2, H2, etc., and a gas containing H2 or helium is preferred.

[0150] After plasma irradiation, the resist underlayer film may be subjected to a heat treatment. When heating after plasma irradiation, the heating conditions can be appropriately selected from the ranges of a heating temperature of 80 to 800°C (preferably 100 to 700°C, more preferably 200 to 600°C) and a heating time of 30 to 180 seconds (preferably 30 to 120 seconds). Without being bound by theory, it is believed that high-temperature heating after plasma irradiation can bond dangling bonds, contributing to densification of the cured film (resist underlayer film).

[0151] The atmosphere in which the substrate is heated after plasma irradiation can be selected as needed from either an oxygen-containing atmosphere such as air (oxygen concentration 1% to 21%) or an oxygen-free atmosphere such as nitrogen. For example, if the substrate is susceptible to air oxidation, substrate damage can be suppressed by forming a hardened film by heat treatment in an atmosphere with an oxygen concentration of less than 1%.

[0152] The irradiation device is not particularly limited as long as it is capable of irradiating plasma, and for example, Telius SP and Tactras Vigus manufactured by Tokyo Electron Ltd. can be used. The device can be selected and the conditions can be set so that the effects of the present invention can be more pronounced.

[0153] The design of the resist underlayer film pattern is not particularly limited. Examples include a line pattern and a contact hole pattern. From the viewpoint of uniformity of the surface modification by plasma irradiation, a line pattern is more preferable. Therefore, the resist underlayer film pattern forming method of the present invention can be suitably used in the sidewall spacer method.

[0154] In order to promote the modification of the resist underlayer film pattern by plasma irradiation, the silicon-containing resist interlayer film or inorganic hard mask interlayer film remaining on the resist underlayer film pattern is preferably thin.The preferred thickness of the silicon-containing resist interlayer film or inorganic hard mask film remaining on the resist underlayer film pattern is preferably 15 nm or less, more preferably 10 nm or less, and even more preferably 5 nm or less, and it may not even be present on the resist underlayer film pattern.

[0155] It is preferable to include, after the plasma exposure step, a step of forming a pattern directly or indirectly on a substrate using the plasma-exposed resist underlayer film pattern as an etching mask.

[0156] On the other hand, the present invention is a method for forming a pattern on a substrate to be processed at a pitch of 1 / 2 of the pitch of the resist upper layer film pattern (FIG. 3), After the step of irradiating the resist underlayer film pattern with plasma, forming an inorganic silicon film made of any one of polysilicon, amorphous silicon, silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, and composite materials thereof by a CVD method or an ALD method so as to cover the resist underlayer film pattern; a step of removing the resist underlayer film pattern by dry etching to form an inorganic silicon film pattern having a pattern pitch that is half the pitch of the resist upper layer film pattern; a step of forming a pattern having a pitch that is 1 / 2 of the pitch of the resist upper layer film pattern on a substrate to be processed using the inorganic silicon film pattern as a mask; The pattern forming method may also include the steps of:

[0157] Such a pattern formation method is extremely useful in microfabrication processes, since it is possible to form an inorganic silicon film pattern (sidewall pattern) with small edge roughness in the sidewall spacer method.

[0158] The method for removing the resist underlayer film pattern is not particularly limited, but removal by dry etching is preferred from the viewpoint of preventing collapse of the inorganic silicon film pattern (sidewall pattern).

[0159] When removal by dry etching is selected, the resist underlayer film is removed under dry etching conditions that result in a superior etching rate for the resist underlayer film relative to the sidewall pattern, such as reactive dry etching using a gas plasma containing oxygen or reactive dry etching using a gas plasma containing hydrogen and nitrogen.

[0160] The present invention also provides a method for forming a pattern on a substrate to be processed at a pitch equal to half the pitch of the resist upper layer film pattern (FIG. 4), comprising the steps of: After the step of irradiating the resist underlayer film pattern with plasma, forming an inorganic silicon film made of any one of polysilicon, amorphous silicon, silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, or a composite material thereof by a CVD method or an ALD method so as to cover the resist underlayer film pattern; a step of applying the composition for forming a resist underlayer film of the present invention, which is modified by plasma irradiation, onto an inorganic silicon film pattern for pattern separation, followed by heat treatment; a step of exposing the inorganic silicon film pattern by etching back and then irradiating the pattern with plasma; a step of removing the inorganic silicon film pattern by dry etching to form a resist underlayer film pattern having a pattern pitch that is half the pitch of the resist upper layer film pattern; a step of forming a pattern having a pitch that is half that of the resist upper layer film pattern on a substrate to be processed using the resist underlayer film pattern as a mask; The pattern forming method may include:

[0161] The present invention also provides a method for forming a pattern on a substrate to be processed at a pitch equal to 1 / 2 of the pitch of the resist upper layer film pattern (FIG. 5), comprising: Before the step of irradiating the resist underlayer film pattern with plasma, forming an inorganic silicon film made of any one of polysilicon, amorphous silicon, silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, or a composite material thereof by a CVD method or an ALD method so as to cover the resist underlayer film pattern; a step of applying the composition for forming a resist underlayer film of the present invention, which is modified by plasma irradiation, onto an inorganic silicon film pattern for pattern separation, followed by heat treatment; a step of exposing the inorganic silicon film pattern by etching back and then irradiating the pattern with plasma; a step of removing the inorganic silicon film pattern by dry etching to form a resist underlayer film pattern having a pattern pitch that is half the pitch of the resist upper layer film pattern; a step of forming a pattern having a pitch that is half that of the resist upper layer film pattern on a substrate to be processed using the resist underlayer film pattern as a mask; The pattern forming method may also include the steps of:

[0162] The method for removing the resist underlayer film pattern and inorganic silicon film pattern remaining on the substrate to be processed is not particularly limited, but they can be removed by, for example, the CMP method. [Example]

[0163] EXAMPLES The present invention will be specifically explained below using examples and comparative examples, but the present invention is not limited to these.

[0164] The present invention will be explained in more detail below with reference to Synthesis Examples, Comparative 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.

[0165] The compounds (G1) to (G13) shown below were used in the synthesis of the compounds (A1) to (A14) and the comparative compound (R1). [ka]

[0166] [Synthesis Example 1] Synthesis of Compound (A1) [ka] Under a nitrogen atmosphere, 180 g of compound (G1), 75 g of 37% formalin solution, and 5 g of oxalic acid were added and stirred at an internal temperature of 100°C for 24 hours. After cooling to room temperature, 500 g of methyl isobutyl ketone was added, and the organic layer was washed five times with 200 g of pure water, and then evaporated to dryness under reduced pressure. 320 g of THF was added to the residue, and the polymer was reprecipitated with 1350 g of hexane. The precipitated polymer was separated by filtration and dried under reduced pressure to obtain compound (A1). The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the following results were obtained. (A1): Mw = 11,200, Mw / Mn = 4.35

[0167] [Synthesis Example 2] Synthesis of Compound (A2) [ka] Under a nitrogen atmosphere, 160.2 g of compound (G2), 64.9 g of a 37% formaldehyde solution, and 300 g of 2-methoxy-1-propanol were added and homogenized at an internal temperature of 100 °C. Then, 18.0 g of a 20% solution of paratoluenesulfonic acid in 2-methoxy-1-propanol, which had been previously mixed and homogenized, was slowly added, 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, 1000 ml of methyl isobutyl ketone was added, and the mixture was washed six times with 200 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 2000 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 compound (A2). The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the following results were obtained. (A2): Mw = 4,000, Mw / Mn = 3.02

[0168] [Synthesis Example 3] Synthesis of Compound (A3) [ka] Under a nitrogen atmosphere, 100.0 g of compound (G1), 48.3 g of compound (G3), and 450 g of 1,2-dichloroethane were mixed and uniformly dispersed at an internal temperature of 60°C. Then, 82.4 g of methanesulfonic acid was added dropwise over 1 hour, followed by heating and stirring at an internal temperature of 70°C for 24 hours. After cooling to room temperature, 1000 g of methyl isobutyl ketone was added, and the organic layer was washed five times with 200 g of pure water. The organic layer was then evaporated to dryness under reduced pressure. 450 g of THF was added to the residue, and the polymer was reprecipitated with 1800 g of hexane. The precipitated polymer was separated by filtration and dried under reduced pressure to obtain compound (A3). The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the following results were obtained. (A3): Mw = 9,800, Mw / Mn = 3.50

[0169] [Synthesis Example 4] Synthesis of compound (A4) [ka] Under a nitrogen atmosphere, 180.0 g of compound (G1), 58.0 g of compound (G4), 75.0 g of 37% formalin solution, 5.0 g of oxalic acid, and 500 g of 2-methoxy-1-propanol were added and stirred at an internal temperature of 100°C for 24 hours. After cooling to room temperature, 1000 g of methyl isobutyl ketone was added, and the organic layer was washed five times with 200 g of pure water and then evaporated to dryness under reduced pressure. 480 g of THF was added to the residue, and the polymer was reprecipitated with 2400 g of hexane. The precipitated polymer was separated by filtration and dried under reduced pressure to obtain compound (A4). The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the following results were obtained. (A4): Mw = 9,350, Mw / Mn = 3.76

[0170] [Synthesis Example 5] Synthesis of Compound (A5) [ka] Under a nitrogen atmosphere, 50.0 g of compound (A1) obtained in Synthesis Example 1, 38.1 g of potassium carbonate, and 200 g of dimethylformamide were added and heated to 50°C to form a uniform dispersion. 23.4 g of allyl bromide was then slowly added dropwise, and the mixture was stirred at an internal temperature of 50°C for 8 hours. After cooling to room temperature, 400 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 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 (A5). The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the following results were obtained. (A5): Mw = 12,200, Mw / Mn = 4.38

[0171] [Synthesis Example 6] Synthesis of compound (A6) [ka] Under a nitrogen atmosphere, 50.0 g of compound (A1) obtained in Synthesis Example 1, 41.9 g of potassium carbonate, and 200 g of dimethylformamide were added and heated to 50°C to form a uniform dispersion. 29.5 g of 3-bromo-1-propyne was then slowly added dropwise, and the mixture was stirred at an internal temperature of 50°C for 8 hours. After cooling to room temperature, 400 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 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 (A6). The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the following results were obtained. (A6): Mw = 12,800, Mw / Mn = 4.43

[0172] [Synthesis Example 7] Synthesis of compound (A7) [ka] Under a nitrogen atmosphere, 90.1 g of compound (G5), 25.2 g of 37% formalin solution, and 270 g of 2-methoxy-1-propanol were added and the mixture was heated to an internal temperature of 80°C to form a homogeneous solution. Then, 18 g of a 20% solution of paratoluenesulfonic acid in 2-methoxy-1-propanol was slowly added and stirred at an internal temperature of 110°C for 8 hours. After cooling to room temperature, 600 g of methyl isobutyl ketone was added, and the organic layer was washed five times with 200 g of pure water. The organic layer was then evaporated to dryness under reduced pressure. 320 g of THF was added to the residue, and the polymer was reprecipitated with 1350 g of methanol. The precipitated polymer was separated by filtration and dried under reduced pressure to obtain compound (A7). The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the following results were obtained. (A7): Mw = 3,520, Mw / Mn = 2.60

[0173] [Synthesis Example 8] Synthesis of compound (A8) [ka] Under a nitrogen atmosphere, 42.8 g of compound (G5), 15.7 g of potassium carbonate, and 150 g of DMF were added and the mixture was kept at an internal temperature of 50°C to form a uniform dispersion. 28.2 g of propargyl bromide 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 (A8). The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the following results were obtained. (A8): Mw = 560, Mw / Mn = 1.01

[0174] [Synthesis Example 9] Synthesis of Compound (A9) [ka] Under a nitrogen atmosphere, 46.9 g of compound (G6), 10.1 g of potassium carbonate, and 150 g of DMF were added and the mixture was kept at an internal temperature of 50°C to form a uniform dispersion. 9.0 g of propargyl bromide 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 mixture 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 (A9). The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the following results were obtained. (A9): Mw = 903, Mw / Mn = 1.08

[0175] [Synthesis Example 10] Synthesis of Compound (A10) [ka] Under a nitrogen atmosphere, 3.8 g of methanesulfonic acid and 30 g of methylene chloride were mixed and homogenized at an internal temperature of 30°C. A mixture of 30.0 g of compound (G4) and 60.0 g of methylene chloride was then added dropwise over 1 hour, followed by heating and stirring at an internal temperature of 35°C for 24 hours. After cooling to room temperature, 300 g of toluene was added, and the mixture was washed six times with 100 g of pure water. The organic layer was evaporated to dryness under reduced pressure. 90 g of THF was added to the residue to form a homogeneous solution, which was then crystallized in 600 g of methanol. The precipitated crystals were separated by filtration, washed twice with 300 g of methanol, and then recovered. The recovered crystals were dried in vacuo at 70°C to obtain 28.7 g of compound (A10). The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the following results were obtained. (A10): Mw = 2400, Mw / Mn = 1.93

[0176] [Synthesis Example 11] Synthesis of Compound (A11) [ka] Under a nitrogen atmosphere, 60.0 g of compound (G7) and 300 g of 1,2-dichloroethane were mixed and homogenized at an internal temperature of 60°C. Then, 55.4 g of methanesulfonic acid was added dropwise over 1 hour, followed by heating and stirring at an internal temperature of 70°C for 6 hours. After cooling to room temperature, 400 g of 1,2-dichloroethane was added, and the insoluble matter was removed by filtration. The recovered filtrate was washed six times with 200 g of purified water, and the organic layer was evaporated to dryness under reduced pressure. 150 g of THF was added to the residue to form a homogenous solution, which was then crystallized in 500 g of methanol. The precipitated crystals were separated by filtration, washed with 300 g of methanol and then 300 g of diisopropyl ether, and then recovered. The recovered crystals were dried in vacuo at 70°C to obtain 33.2 g of compound (A11). The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the following results were obtained. (A11): Mw = 560, Mw / Mn = 2.43

[0177] [Synthesis Example 12] Synthesis of Compound (A12) [ka] 41.2 g of tertiary alcohol (G8) and 160 g of methylene chloride were mixed. 19.2 g of methanesulfonic acid was slowly added dropwise, and the mixture was heated under reflux for 8 hours. After cooling to room temperature, 250 g of toluene was added, washed with water, and concentrated under reduced pressure to obtain 37.6 g of compound (A12). The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the following results were obtained. (A12): Mw = 1850, Mw / Mn = 1.26

[0178] [Synthesis Example 13] Synthesis of Compound (A13) [ka] Under a nitrogen atmosphere, 60.0 g of compound (G10), 6.3 g of compound (G9), and 350 g of 1,2-dichloroethane were mixed and heated to a uniform solution at an internal temperature of 60°C. Then, 80.2 g of methanesulfonic acid was added dropwise over 1 hour, followed by heating and stirring at an internal temperature of 70°C for 6 hours. After cooling to room temperature, 200 g of 1,2-dichloroethane was added, and the organic layer was washed six times with 100 g of purified water. The organic layer was then evaporated to dryness under reduced pressure. 200 g of THF was added to the residue to form a uniform solution, which was then crystallized in 600 g of methanol. The precipitated crystals were separated by filtration, washed with 300 g of methanol and then 300 g of diisopropyl ether, and then recovered. The recovered crystals were dried in vacuo at 70°C to obtain 35.5 g of compound (A13). The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the following results were obtained. (A13): Mw = 730, Mw / Mn = 1.38

[0179] [Synthesis Example 14] Synthesis of compound (A14) [ka] Under a nitrogen atmosphere, 80.0 g of epoxy compound (G11), 51.0 g of compound (G12), and 600 g of 2-methoxy-1-propanol were added and heated to 100°C to form a homogeneous solution. 5.7 g of benzyltriethylammonium chloride was then added and stirred at 120°C for 12 hours. After cooling to room temperature, 1,500 g of methyl isobutyl ketone was added, and the organic layer was washed five times with 300 g of pure water. The organic layer was evaporated to dryness under reduced pressure to obtain compound (A14). The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the following results were obtained. (A14): Mw = 900, Mw / Mn = 1.04

[0180] [Synthesis Example 15] Synthesis of Comparative Compound (R1) [ka] In a 500 ml flask, 100 g of monomer 1 (raw material G13) and 290.0 g of propylene glycol monomethyl ether acetate (PGMEA) were weighed and degassed with stirring to prepare a monomer solution. In a separate 500 ml flask, 2.9 g of dimethyl 2,2-azobis(2-methylpropionate) (V-601, manufactured by Wako Pure Chemical Industries, Ltd.) and 50.0 g of PGMEA were weighed and degassed with stirring to prepare an initiator solution. Furthermore, 60 g of PGMEA was weighed into a 1 L flask under a nitrogen atmosphere, degassed with stirring, and then heated to an internal temperature of 80°C. The monomer solution and initiator solution were added simultaneously and separately over 4 hours. After heating and stirring for 16 hours, the mixture was cooled to room temperature. The resulting polymerization solution was added dropwise to 1,500 g of stirred hexane, and the precipitated polymer was filtered off. The resulting polymer was washed twice with 600 g of hexane and then vacuum dried at 50° C. for 20 hours to obtain a white powdery polymer (R1). The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the following results were obtained. (R1): Mw = 10,000, Mw / Mn = 2.00

[0181] [Composition for forming resist underlayer film UDL-1] The resist underlayer film-forming compound (A1) was dissolved in propylene glycol monomethyl ether acetate (PGMEA) containing 0.5 mass % of a surfactant FC-4430 (manufactured by Sumitomo 3M Limited) in the proportions shown in Table 2, and the resulting solution was filtered through a 0.02 μm membrane filter to prepare a resist underlayer film-forming composition (UDL-1).

[0182] [Preparation of Resist Underlayer Film-Forming Compositions (UDL-2 to 17) and Comparative Example Resist Underlayer Film-Forming Composition (Comparative Example UDL-1)] 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 Table 2. In Table 2, "-" indicates that the corresponding component was not used. The acid generator (TAG) used was the one represented by formula (E1) below, and the flow promoter used was the one represented by formula (B1) below. The results for UDL-1 are also shown.

[0183] [Acid generator] The thermal acid generator (E1) used in the composition for forming a resist underlayer film is shown below. [ka]

[0184] [Flow promoter] Table 1 shows the flowability promoter (B1) used in the composition for forming a resist underlayer film. [Table 1]

[0185] [Crosslinking agent] The crosslinking agents (C) used in the resist underlayer film materials are shown below. [ka]

[0186] [Table 2]

[0187] [Evaluation of resist underlayer film pattern formation] Each of the above resist underlayer film-forming compositions (UDL-1 to 17 and comparative UDL-1) was applied onto a silicon wafer substrate on which an SiO2 film had been formed, and baked for 60 seconds at the temperatures shown in Tables 6 and 7 to form a resist underlayer film with a thickness of 60 nm. A silicon-containing resist middle layer material (SOG-1) was applied on top of this and baked at 220°C for 60 seconds to form a 20nm thick resist middle layer film, and then a single layer ArF resist top layer material was applied on top of that and baked at 105°C for 60 seconds to form a 100nm thick photoresist film. An immersion protective film material (TC-1) was applied on top of the photoresist film and baked at 90°C for 60 seconds to form a 50nm thick protective film.

[0188] The silicon-containing resist intermediate layer material (SOG-1) was prepared by dissolving a polymer designated as ArF silicon-containing intermediate film polymer (SiP1) and a crosslinking catalyst (CAT1) in an organic solvent containing 0.1 mass% of FC-4430 (manufactured by Sumitomo 3M) in the proportions shown in Table 3, and filtering the solution through a fluororesin filter with a pore size of 0.1 μm.

[0189] [Table 3]

[0190] The structural formulae of the ArF silicon-containing intermediate film polymer (SiP1) and crosslinking catalyst (CAT1) used are shown below. [ka]

[0191] 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 4 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.

[0192] [Table 4]

[0193] 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]

[0194] The immersion protective film material (TC-1) was prepared by dissolving the protective film polymer (PP1) in an organic solvent in the ratio shown in Table 5 and filtering the solution through a 0.1 μm fluororesin filter.

[0195] [Table 5]

[0196] The polymer (PP1) used in the immersion protective film material (TC-1) is shown below. [ka]

[0197] The resist was then exposed using an ArF immersion exposure system (Nikon Corporation; NSR-S610C, NA 1.30, σ 0.98 / 0.78, 35-degree dipole s-polarized illumination, 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 45 nm 1:1 positive line and space pattern (resist pattern).

[0198] Next, a silicon-containing resist intermediate layer material (SOG-1) was dry-etched using the resist pattern as a mask using a Telius etching system manufactured by Tokyo Electron Co., Ltd. to form a hard mask pattern, and the resist underlayer film was etched using the resulting SOG-1 pattern as a mask to form a resist underlayer film pattern. The line dimensions of the resulting resist underlayer film pattern were measured using a measuring SEM (CG5000) manufactured by Hitachi High-Technologies Corporation.

[0199] 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: 15sec

[0200] Conditions for transferring the silicon atom-containing resist middle layer material (SOG-1) pattern to the resist underlayer film. Chamber pressure: 10mT RF power (top): 1,000W RF power (bottom): 300W CO2 gas flow rate: 320sccm N2 gas flow rate: 80sccm Time: 55sec

[0201] Thereafter, each substrate on which the resist underlayer film pattern was formed was subjected to plasma treatment under the following conditions using a Telius etching system manufactured by Tokyo Electron, and the line dimensions of the resulting resist underlayer film pattern were measured using a length measuring SEM (CG5000) manufactured by Hitachi High-Technologies Corp. The cross section of the pattern was observed using an electron microscope (S-4700) manufactured by Hitachi, Ltd. Chamber pressure: 100mT RF power (top): 100W RF power (bottom): 3500W H2 gas flow rate: 200sccm Time: 20sec

[0202] The resist underlayer film pattern obtained in the above evaluation was used as a mask to etch an SiO2 film. The etching conditions are as follows. The line dimensions of the obtained pattern were measured using a measuring SEM (CG5000) manufactured by Hitachi High-Technologies Corporation. The cross section of the pattern was observed using an electron microscope (S-4700) manufactured by Hitachi, Ltd. Chamber pressure: 100mT RF power (top): 500W RF power (bottom): 300W CF4 gas flow rate: 150sccm CHF3 gas flow rate: 30sccm O2 gas flow rate: 10sccm Time: 130sec

[0203] (Comparative Example 1-2) As Comparative Example 1-2, the following evaluation was carried out.

[0204] The resist underlayer film composition (UDL-1) was applied to a silicon wafer substrate with a SiO2 film and baked at 350°C for 60 seconds to form a 60 nm thick resist underlayer film. A silicon-containing resist middle layer material (SOG-1) was applied on top of that and baked at 220°C for 60 seconds to form a 20 nm thick resist middle layer film. An ArF single-layer resist from the resist top layer material was applied on top of that and baked at 105°C for 60 seconds to form a 100 nm thick photoresist film. An immersion protective film material (TC-1) was applied on top of the photoresist film and baked at 90°C for 60 seconds to form a 50 nm thick protective film.

[0205] The resist was then exposed using an ArF immersion exposure system (Nikon Corporation; NSR-S610C, NA 1.30, σ 0.98 / 0.78, 35-degree dipole s-polarized illumination, 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 45 nm 1:1 positive line and space pattern (resist pattern).

[0206] The substrate on which the resist pattern was formed was then subjected to plasma treatment under the following conditions using a Telius etching system manufactured by Tokyo Electron, and the line dimensions of the resulting resist pattern were measured using a length measuring SEM (CG5000) manufactured by Hitachi High-Technologies Corp. The cross section of the pattern was observed using an electron microscope (S-4700) manufactured by Hitachi, Ltd. Chamber pressure: 100mT RF power (top): 100W RF power (bottom): 3500W H2 gas flow rate: 200sccm Time: 20sec

[0207] Next, a silicon-containing resist intermediate layer material (SOG-1) was dry-etched using the resist pattern as a mask using a Telius etching system manufactured by Tokyo Electron Co., Ltd. to form a hard mask pattern, and the resist underlayer film was etched using the resulting SOG-1 pattern as a mask to form a resist underlayer film pattern. The line dimensions of the resulting resist underlayer film pattern were measured using a measuring SEM (CG5000) manufactured by Hitachi High-Technologies Corporation.

[0208] 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: 15sec

[0209] Conditions for transferring the silicon atom-containing resist middle layer material (SOG-1) pattern to the resist underlayer film. Chamber pressure: 10mT RF power (top): 1,000W RF power (bottom): 300W CO2 gas flow rate: 320sccm N2 gas flow rate: 80sccm Time: 55sec

[0210] The resist underlayer film pattern obtained in the above evaluation was used as a mask to etch an SiO2 film. The etching conditions are as follows. The line dimensions of the obtained pattern were measured using a measuring SEM (CG5000) manufactured by Hitachi High-Technologies Corporation. The cross section of the pattern was observed using an electron microscope (S-4700) manufactured by Hitachi, Ltd. Chamber pressure: 100mT RF power (top): 500W RF power (bottom): 300W CF4 gas flow rate: 150sccm CHF3 gas flow rate: 30sccm O2 gas flow rate: 10sccm Time: 130sec

[0211] (Comparative Examples 1-3) As Comparative Examples 1-3, the following evaluations were carried out.

[0212] The resist underlayer film-forming composition (UDL-1) was applied to a silicon wafer substrate with a SiO2 film and baked at 350°C for 60 seconds to form a 60-nm-thick resist underlayer film. The resist underlayer film before pattern formation was then subjected to plasma irradiation treatment similar to the plasma irradiation conditions for the resist underlayer film pattern in the examples. A silicon-containing resist middle layer material (SOG-1) was applied on top of the resist underlayer film and baked at 220°C for 60 seconds to form a 20-nm-thick resist middle layer film. An ArF single-layer resist from the resist top layer material was then applied on top of that and baked at 105°C for 60 seconds to form a 100-nm-thick photoresist film. An immersion protective film material (TC-1) was applied on the photoresist film and baked at 90°C for 60 seconds to form a 50-nm-thick protective film.

[0213] The resist was then exposed using an ArF immersion exposure system (Nikon Corporation; NSR-S610C, NA 1.30, σ 0.98 / 0.78, 35-degree dipole s-polarized illumination, 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 45 nm 1:1 positive line and space pattern (resist pattern).

[0214] Next, a silicon-containing resist intermediate layer material (SOG-1) was dry-etched using the resist pattern as a mask using a Telius etching system manufactured by Tokyo Electron Co., Ltd. to form a hard mask pattern, and the resist underlayer film was etched using the resulting SOG-1 pattern as a mask to form a resist underlayer film pattern. The line dimensions of the resulting resist underlayer film pattern were measured using a measuring SEM (CG5000) manufactured by Hitachi High-Technologies Corporation.

[0215] 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: 15sec

[0216] Conditions for transferring the silicon atom-containing resist middle layer material (SOG-1) pattern to the resist underlayer film. Chamber pressure: 10mT RF power (top): 1,000W RF power (bottom): 300W CO2 gas flow rate: 320sccm N2 gas flow rate: 80sccm Time: 55sec

[0217] The resist underlayer film pattern obtained in the above evaluation was used as a mask to etch an SiO2 film. The etching conditions are as follows. The line dimensions of the obtained pattern were measured using a measuring SEM (CG5000) manufactured by Hitachi High-Technologies Corporation. The cross section of the pattern was observed using an electron microscope (S-4700) manufactured by Hitachi, Ltd. Chamber pressure: 100mT RF power (top): 500W RF power (bottom): 300W CF4 gas flow rate: 150sccm CHF3 gas flow rate: 30sccm O2 gas flow rate: 10sccm Time: 130sec

[0218] The results of the above examples and comparative examples are shown in Tables 6 and 7 below. If the line dimension after plasma irradiation changed by less than 5% compared to the line dimension before plasma irradiation, it was rated as "A (very good)", if it changed by 5% or more but less than 10%, it was rated as "B (good)", and if it changed by 10% or more, it was rated as "C (poor)". [Table 6] [Table 7] (In Tables 6 and 7, *1 indicates the resist underlayer film pattern, *2 indicates the resist pattern, and *3 indicates the resist underlayer film.)

[0219] As shown in Tables 6 and 7, in Examples 1-1 to 1-17, the CD change before and after plasma irradiation was smaller than in Comparative Example 1-1, and an improvement in LWR was observed due to plasma irradiation. Furthermore, the SiO2 film pattern processed using this as a mask had better LWR than in Comparative Example 1-1, and it was confirmed that it can be suitably used for microfabrication. In Comparative Example 1-1, which used Comparative Example UDL-1, which does not have an aromatic ring, the CD change before and after plasma exposure was large compared to Examples 1-1 to 1-17, distortion was observed in the cross-sectional shape of the line pattern, and it was confirmed that the LWR was also insufficient. On the other hand, in Comparative Example 1-2, in which the resist pattern was irradiated with plasma but the resist underlayer film pattern was not, a large change in line dimension was observed, and distortion of the line pattern was observed. This was used to process an SiO2 film pattern, but the pattern could not be transferred to the SiO2 film, probably because the dry etching of the resist pattern with fluorocarbon-based gases was insufficient. In Comparative Example 1-3, in which a resist pattern was transferred to a plasma-irradiated resist underlayer film, the LWR of the resist underlayer film pattern was larger than in Examples 1-1 to 1-17, and the LWR of the SiO2 film pattern processed using this as a mask was also insufficient. When plasma is irradiated onto a resist underlayer film without a pattern, it is expected that the thickening of the resist underlayer film will restrict uniform modification of the entire film. On the other hand, when plasma is irradiated onto the resist underlayer film pattern of the present invention, film modification of the pattern sidewall surface proceeds efficiently. Therefore, it can be inferred that plasma irradiation improved the edge roughness of the resist underlayer film pattern.

[0220] [Wet stripping evaluation of SOG film on resist underlayer film pattern] The SOG film remaining on the resist underlayer film pattern was immersed in a 25% aqueous solution of tetramethylammonium hydroxide at 70° C. for 10 minutes, and the cross-sectional shape of the resist underlayer film pattern was observed with an electron microscope (S-4700) manufactured by Hitachi, Ltd. The results were rated as "good" when the SOG film was removed and the cross-sectional shape of the resist underlayer film pattern was rectangular, and "bad" when the SOG film was removed but the cross-sectional shape of the resist underlayer film pattern was distorted. The results are shown in Table 8.

[0221] The resist underlayer film patterns evaluated are shown below. Example 2-1: After plasma irradiation of the resist underlayer film pattern prepared in Example 1-1 Comparative Example 2-1: After plasma irradiation of the resist underlayer film pattern prepared in Comparative Example 1-1 Comparative Example 2-2: Resist underlayer film pattern prepared in Comparative Example 1-3 above Comparative Example 2-3: Resist underlayer film pattern prepared in Example 1-1 before plasma irradiation

[0222] [Table 8]

[0223] As shown in Table 8, it was confirmed that in Example 2-1, the cross-sectional shape of the resist underlayer film pattern after SOG film removal was rectangular compared to Comparative Examples 2-1 and 2-2. On the other hand, in Comparative Example 2-3, in which the resist underlayer film pattern was not subjected to plasma irradiation, it was confirmed that the resist underlayer film pattern after SOG film removal was distorted, possibly due to insufficient resistance to the stripping solution. It has been found that the resist underlayer film pattern of the present invention has sidewall film quality modified by plasma irradiation, and has improved resistance to a stripping solution, making it extremely useful as a core material in the sidewall spacer method since it can be suitably used to remove a silicon-containing film using a stripping solution.

[0224] From the above, the method for forming a resist underlayer film pattern of the present invention can form a resist underlayer film pattern that exhibits excellent edge roughness by plasma irradiation, and is therefore extremely useful for next-generation microfabrication processes.

[0225] The present specification includes the following aspects. [1] A method for forming a resist underlayer film pattern on a substrate, comprising: (i-1) applying a composition for forming a resist underlayer film onto the substrate and then performing a heat treatment to form a resist underlayer film; (i-2) applying a silicon-containing resist intermediate film onto the resist underlayer film, followed by heat treatment to form a silicon-containing resist intermediate film; (i-3) forming a resist upper layer film on the silicon-containing resist intermediate film; (i-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; (i-5) forming a resist underlayer film pattern by performing etching a plurality of times using the resist upper layer film pattern as a mask; (i-6) a step of irradiating the resist underlayer film pattern with plasma; and The resist underlayer film-forming composition contains a resin having an aromatic ring, A pattern forming method, characterized in that the plasma used for the plasma irradiation in the step (i-6) etches the resist underlayer film less than the etching gas used in the step (i-5) of forming a resist underlayer film pattern by etching the resist underlayer film. [2] A method for forming a resist underlayer film pattern on a substrate, comprising: (ii-1) applying a composition for forming a resist underlayer film onto the substrate and then performing a heat treatment to form a resist underlayer film; (ii-2) forming an inorganic hard mask intermediate film selected from a silicon oxide film, a silicon nitride film, and a silicon oxynitride film on the resist underlayer film; (ii-3) forming an upper layer resist film on the inorganic hard mask intermediate film; (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) forming a resist underlayer film pattern by performing etching a plurality of times using the resist upper layer film pattern as a mask; (ii-6) a step of irradiating the resist underlayer film pattern with plasma; and The resist underlayer film-forming composition contains a resin having an aromatic ring, The pattern forming method, characterized in that the plasma used for the plasma irradiation in the step (ii-6) etches the resist underlayer film less than the etching gas used in the step (ii-5) of forming a resist underlayer film pattern by etching the resist underlayer film. [3] The pattern forming method according to [1] or [2], characterized in that after the plasma irradiation step, it comprises a step of forming a pattern directly or indirectly on a substrate using the plasma-irradiated resist underlayer film pattern as an etching mask. [4] The pattern formation method according to any one of [1] to [3], wherein the plasma irradiation step is carried out in an atmosphere of N2, NF3, H2, a fluorocarbon, a rare gas, or a mixture of any of these. [5] The pattern formation method according to any one of [1] to [4], wherein the plasma irradiation step is carried out in an atmosphere containing hydrogen or helium. [6] The composition for forming a resist underlayer film, (a) a polymer compound having an aromatic ring in the main chain and a weight average molecular weight of 2,500 or more and 20,000 or less in terms of polystyrene as determined by gel permeation chromatography; (b) The pattern forming method according to any one of [1] to [6], characterized in that the pattern forming method contains (A) a resin that is an aromatic ring-containing compound having a weight average molecular weight of 600 or more and 3,000 or less in terms of polystyrene, as determined by gel permeation chromatography, or a combination thereof. [7] The pattern forming method according to [6], wherein the resin (A) has at least one crosslinkable group selected from a vinyl group, an allyl group, an allyloxy group, an ethynyl group, a propargyl group, a propargyloxy group, an epoxy group, an oxetanyl group, and a hydroxyl group. [8] A method for forming a pattern on the substrate at a pitch equal to 1 / 2 of the pitch of the resist upper layer film pattern, comprising: After the step of irradiating the resist underlayer film pattern with plasma, forming an inorganic silicon film made of any one of polysilicon, amorphous silicon, silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, and composite materials thereof by a CVD method or an ALD method so as to cover the resist underlayer film pattern; a step of removing the resist underlayer film pattern by dry etching or using a stripping solution to form an inorganic silicon film pattern having a pattern pitch that is half that of the resist upper layer film pattern; The pattern forming method according to any one of [1] to [7], comprising:

[0226] 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]

[0227] 1...Substrate to be processed, 2...Layer to be processed, 2b...pattern (pattern formed on the processing layer), 3...resist underlayer film, 3a...resist underlayer film pattern, 3b...resist underlayer film pattern after plasma exposure, 4...silicon atom-containing resist intermediate film, 4a...silicon atom-containing resist intermediate film pattern, 4b...Silicon atom-containing resist intermediate film pattern after plasma exposure, 5...resist upper layer film, 5a...resist upper layer film pattern, 6...exposed portion, 7...inorganic silicon film, 7a...inorganic silicon film pattern

Claims

1. A method for forming a resist underlayer film pattern on a substrate, comprising: (i-1) applying a composition for forming a resist underlayer film onto the substrate and then performing a heat treatment to form a resist underlayer film; (i-2) applying a silicon-containing resist intermediate film onto the resist underlayer film, followed by heat treatment to form a silicon-containing resist intermediate film; (i-3) forming a resist upper layer film on the silicon-containing resist intermediate film; (i-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; (i-5) forming a resist underlayer film pattern by performing etching a plurality of times using the resist upper layer film pattern as a mask; (i-6) a step of exposing the resist underlayer film pattern to plasma; and The resist underlayer film-forming composition contains a resin having an aromatic ring, The pattern forming method, wherein the plasma used for the plasma irradiation in the step (i-6) etches the resist underlayer film less than the etching gas used in the step (i-5) of forming a resist underlayer film pattern by etching the resist underlayer film.

2. A method for forming a resist underlayer film pattern on a substrate, comprising: (ii-1) applying a composition for forming a resist underlayer film onto the substrate, followed by heat treatment to form a resist underlayer film; (ii-2) forming an inorganic hard mask intermediate film selected from a silicon oxide film, a silicon nitride film, and a silicon oxynitride film on the resist underlayer film; (ii-3) forming an upper layer resist film on the inorganic hard mask intermediate film; (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) forming a resist underlayer film pattern by performing etching a plurality of times using the resist upper layer film pattern as a mask; (ii-6) a step of irradiating the resist underlayer film pattern with plasma; and The resist underlayer film-forming composition contains a resin having an aromatic ring, The pattern formation method, characterized in that the plasma used for the plasma irradiation in the step (ii-6) is one that etches the resist underlayer film less than an etching gas used in the step (ii-5) of forming a resist underlayer film pattern by etching the resist underlayer film.

3. 3. The pattern forming method according to claim 1, further comprising, after the plasma irradiation step, a step of forming a pattern directly or indirectly on a substrate using the plasma-irradiated resist underlayer film pattern as an etching mask.

4. The plasma irradiation step is performed by using N ２ , N.F. ３ , H ２ 3. The pattern forming method according to claim 1, wherein the method is carried out in an atmosphere of a fluorocarbon, a rare gas, or a mixture of any of these.

5. 5. The pattern formation method according to claim 4, wherein the plasma irradiation step is carried out in an atmosphere containing hydrogen or helium.

6. The composition for forming a resist underlayer film, (a) a polymer compound having an aromatic ring in its main chain and having a weight average molecular weight of 2,500 or more and 20,000 or less in terms of polystyrene as determined by a gel permeation chromatography method; 3. The pattern forming method according to claim 1, further comprising (b) an aromatic ring-containing compound having a weight average molecular weight of 600 or more and 3,000 or less in terms of polystyrene as determined by gel permeation chromatography, or (A) a resin which is a combination thereof.

7. 7. The pattern formation method according to claim 6, wherein the resin (A) has at least one crosslinkable group selected from a vinyl group, an allyl group, an allyloxy group, an ethynyl group, a propargyl group, a propargyloxy group, an epoxy group, an oxetanyl group, and a hydroxyl group.

8. A method for forming a pattern on the substrate at a pitch that is 1 / 2 of the pitch of the resist upper layer film pattern, comprising: After the step of irradiating the resist underlayer film pattern with plasma, forming an inorganic silicon film made of any one of polysilicon, amorphous silicon, silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, and composite materials thereof by a CVD method or an ALD method so as to cover the resist underlayer film pattern; a step of removing the resist underlayer film pattern by dry etching or using a stripping solution to form an inorganic silicon film pattern having a pattern pitch that is half that of the resist upper layer film pattern; 3. The pattern forming method according to claim 1, further comprising:

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