Pattern forming method

Abstract

The invention relates to a pattern forming method. Provided is a method for forming a resist underlayer film pattern which exhibits excellent edge roughness compared to a conventional organic underlayer film pattern by performing plasma irradiation. The invention provides a pattern forming method. The method includes forming a resist underlayer film on a substrate, forming a silicon-containing resist intermediate film on the resist underlayer film, forming a resist upper layer film on the silicon-containing resist intermediate film, forming a pattern on the resist upper layer film, and forming a resist underlayer film pattern by a plurality of times of etching using the resist pattern as a mask. Subjecting the resist underlayer film pattern to plasma irradiation; the resist underlayer film is etched less than the resist underlayer film in the step of forming the pattern of the resist underlayer film by using a resin containing an aromatic ring as the composition for forming the resist underlayer film and using an etching gas used in the step of forming the pattern of the resist underlayer film as the plasma used in the plasma irradiation.

Description

Technical Field

[0001] The present invention relates to a method for forming a finely patterned resist underlayer film pattern that can be used in the multilayer resist method in the manufacturing process of semiconductor devices. Background Technology

[0002] With the increasing integration and speed of LSI (Lithium-ion Sensor), the miniaturization of pattern sizes has progressed rapidly. Photolithography technology combines this miniaturization by using shorter wavelengths of light sources and appropriate selection of resist compositions to achieve the formation of fine patterns. At its core is a single-layer positive photoresist composition. This single-layer positive photoresist composition has an etch-resistant framework in the resist resin that is etch-resistant to dry etching by chlorine-based or fluorine-based gas plasmas, and has a switching mechanism that allows the exposed portion to dissolve, thereby forming a pattern. The remaining resist pattern is then used as an etching mask to perform dry etching on the substrate being processed.

[0003] However, miniaturizing the photoresist film while maintaining its thickness (i.e., reducing the pattern width) reduces the film's resolution. Furthermore, if the photoresist film is to be developed using a developer, the aspect ratio becomes too large, resulting in pattern distortion. Therefore, along with pattern miniaturization, the photoresist film is thinned.

[0004] On the other hand, in the processing of substrates, a method is typically used where a patterned photoresist film is used as an etching mask, and the substrate is processed by dry etching. However, in reality, there is no dry etching method that can achieve complete etch selectivity between the photoresist film and the substrate. Therefore, there is a problem that the photoresist film is also damaged and broken during substrate processing, making it impossible to correctly transfer the resist pattern to the substrate. Therefore, with the miniaturization of patterns, higher dry etching resistance is required for the resist composition. However, on the other hand, in order to improve resolution, the resin used in the photoresist composition is required to have low light absorption at the exposure wavelength. Therefore, with the shortening of exposure wavelengths such as i-rays, KrF, and ArF, the resins have also changed to phenolic varnish resins, polyhydroxystyrene, and resins with aliphatic polycyclic skeletons. In reality, the most recent photoresist compositions that have become the fastest etching speed and highest resolution in the dry etching conditions during substrate processing tend to have weaker etching resistance.

[0005] Considering this situation, it becomes necessary to dry etch the substrate with a thinner photoresist film that has weaker etching resistance. The immediate priority is to ensure the quality of materials and processes in this step.

[0006] One method to address this problem is the multilayer resist method. This method involves inserting an intermediate resist film with a different etching selectivity than the photoresist film (i.e., the upper resist film) between the upper resist film and the substrate being processed. After a pattern is obtained on the upper resist film, the pattern on the upper resist film is used as a dry etching mask, and the pattern is transferred to the intermediate resist film by dry etching. The intermediate resist film is then used as a dry etching mask, and the pattern is transferred to the substrate being processed by dry etching.

[0007] One type of multilayer photoresist method is the three-layer photoresist method, which uses common photoresist compositions applicable to single-layer photoresist methods. In this three-layer photoresist method, for example, an organic film such as phenolic resin is formed as the lower photoresist film on the substrate being processed, a silicon-containing photoresist intermediate film is formed on top of this, and a conventional organic photoresist film is formed as the upper photoresist film. During dry etching using fluorine-based gas plasma, the organic upper photoresist film achieves a better etch selectivity than the silicon-containing photoresist intermediate film; therefore, the pattern on the upper photoresist film can be transferred to the silicon-containing photoresist intermediate film by dry etching using fluorine-based gas plasma. According to this method, even if a resist composition that is difficult to form a pattern with sufficient film thickness for direct processing of the substrate is used, or a resist composition that does not have sufficient dry etching resistance for substrate processing, as long as the pattern can be transferred to a silicon-containing resist intermediate film (resist intermediate film), and then a pattern transfer performed by dry etching using oxygen-based or hydrogen-based gas plasma is performed, a pattern of an organic film (resist underlayer film) such as phenolic varnish resin with sufficient dry etching resistance for substrate processing can be obtained. As such resist underlayer films, for example, those described in Patent Document 1, numerous examples are known.

[0008] On the other hand, in recent years, the miniaturization of DRAM memory has accelerated. In nanoscale high-resolution micropatterns, the proportion of edge roughness relative to the linewidth of the pattern has increased. Furthermore, reducing the edge roughness of the pattern has become more difficult than before, thus increasing the necessity for resist underlayer patterns with good edge roughness. In particular, the sidewall spacer method (Non-Patent Document 1), which involves attaching films to the sidewalls on both sides of the line pattern and thereby halving the pitch, has made reducing the edge roughness of the resist underlayer pattern a key issue.

[0009] As a sidewall backing method, one proposal involves using CVD to form sidewalls from materials such as SiO2, α-Si, and α-C, then removing the core pattern via dry etching to create the sidewall pattern, thus achieving a pattern pitch of half. In multilayer resist methods using an organic resist underlayer and a silicon-containing intermediate film, the resist pattern is transferred to the core material composed of the organic underlayer using dry etching. Sidewalls are then formed on the transferred core material, and the core material is removed, thereby creating a pattern with a 1 / 2 pattern pitch. The edge roughness of the sidewall pattern with a 1 / 2 pattern pitch is strongly influenced by the edge roughness of the resist underlayer pattern that forms the core.

[0010] Various methods have been explored to reduce the linewidth deviation of the etched layer pattern. As an example, there is a method that reduces the edge roughness of the resist pattern by performing plasma treatment using H2 gas to harden the resist film (Patent Document 2).

[0011] However, when considering the use of the above method as an advanced generation of etch mask, concerns remain regarding the dry etching resistance of the resist pattern, and deterioration of edge roughness is anticipated during pattern transfer to the processed substrate. Furthermore, when considering its use as a core component of the sidewall liner method, concerns remain regarding the heat resistance of the resist pattern, and deterioration of edge roughness is anticipated during sidewall formation using the CVD method.

[0012] Existing technical documents

[0013] Patent documents

[0014] [Patent Document 1] Japanese Patent Application Publication No. 2004-205685

[0015] [Patent Document 2] Japanese Patent Application Publication No. 2007-219292

[0016] Non-patent literature

[0017] [Non-Patent Literature 1] J.Vac.Sci.Technol.B17(6), Nov / Dec1999 Summary of the Invention

[0018] [The problem that the invention aims to solve]

[0019] The present invention was made in view of the above circumstances, and its purpose is to provide a method for forming a resist underlayer pattern that exhibits excellent edge roughness for conventional organic underlayer pattern by means of plasma irradiation.

[0020] [Methods for solving the problem]

[0021] To address the aforementioned issues, the present invention provides a pattern forming method for forming a resist underlayer pattern on a substrate, characterized by comprising the following steps:

[0022] (i-1) After coating the substrate with a composition for forming a photoresist underlayer, a photoresist underlayer is formed by heat treatment.

[0023] (i-2) After coating the silicon-containing photoresist intermediate film with a composition for forming a silicon-containing photoresist, a silicon-containing photoresist intermediate film is formed by heat treatment.

[0024] (i-3) A top layer of photoresist is formed on the silicon-containing photoresist intermediate film.

[0025] (i-4) After the upper layer of the photoresist is exposed to a pattern, it is developed with a developer to form a pattern on the upper layer of the photoresist.

[0026] (i-5) A lower resist film pattern is formed by repeated etching using the upper resist film pattern as a mask, and

[0027] (i-6) The pattern of the lower layer of the resist film is subjected to plasma irradiation;

[0028] As a component for forming the lower film of this resist, a resin containing an aromatic ring is used.

[0029] The plasma used for plasma irradiation in step (i-6) is less etched than the etching gas used in step (i-5) to form the resist underlayer pattern by etching the resist underlayer.

[0030] If such a method of forming a resist underlayer film pattern is used, the film surface of the pattern sidewalls can be modified by plasma irradiation, thereby forming a resist underlayer film pattern with good edge roughness.

[0031] Furthermore, a pattern forming method is provided, which is a method for forming a resist underlayer film pattern on a substrate, characterized by comprising the following steps:

[0032] (ii-1) After coating the substrate with a composition for forming a photoresist underlayer, a photoresist underlayer is formed by heat treatment.

[0033] (ii-2) An inorganic hard mask intermediate film selected from silicon oxide film, silicon nitride film, and silicon oxide nitride film is formed on the lower layer of the resist film.

[0034] (ii-3) A resist upper layer film is formed on the intermediate film of the inorganic hard mask.

[0035] (ii-4) After the upper layer of the photoresist is exposed to a pattern, it is developed using a developer to form a pattern on the upper layer of the photoresist.

[0036] (ii-5) A lower resist film pattern is formed by repeated etching using the upper resist film pattern as a mask, and

[0037] (ii-6) The pattern of the lower layer of the resist film is subjected to plasma irradiation;

[0038] As a component for forming the lower film of this resist, a resin containing an aromatic ring is used.

[0039] The plasma used for plasma irradiation in step (ii-6) is less etched than the etching gas used in step (ii-5) to form the resist underlayer pattern by etching the resist underlayer.

[0040] If such a method of forming a resist underlayer film pattern is used, the film surface of the pattern sidewalls can be modified by plasma irradiation, thereby forming a resist underlayer film pattern with good edge roughness.

[0041] This situation could be a pattern forming method that, after the aforementioned plasma irradiation step, includes using the plasma-irradiated resist lower layer film pattern as an etching mask to directly or indirectly form a pattern on the substrate.

[0042] The pattern forming method of the present invention enables patterns to be formed on a substrate in such a manner.

[0043] The pattern formation method is preferably performed by carrying out the above-mentioned plasma irradiation step in an environment of N2, NF3, H2, fluorocarbons, rare gases, or any mixture thereof.

[0044] By performing plasma irradiation on the resist underlayer pattern in an environment containing the aforementioned gases, edge roughness can be improved while suppressing lateral etching of the resist underlayer pattern.

[0045] In this case, the pattern formation method should be performed by carrying out the above-mentioned plasma irradiation step in an environment containing hydrogen or helium.

[0046] As mentioned above, from a productive perspective, gases containing H2 or helium are also suitable.

[0047] The above-described pattern formation method is characterized by:

[0048] The composition for forming the lower layer film of the above-mentioned resist contains resin (A), which is...

[0049] (a) Polystyrene-equivalent polymers with a weight average molecular weight of 2,500 to 20,000 as determined by gel permeation chromatography with aromatic rings in the main chain.

[0050] (b) Compounds containing aromatic rings with a weight-average molecular weight of 600 to 3,000 based on polystyrene equivalents obtained by gel permeation chromatography.

[0051] Or a combination thereof.

[0052] If a pattern forming method is used that uses a composition for forming a resist underlayer film containing the above-mentioned (A) resin, it is easy to cause modification due to plasma irradiation, and a resist underlayer film pattern with better edge roughness can be formed.

[0053] In this case, the resin (A) mentioned above should preferably have at least one crosslinking group selected from vinyl, allyl, allyloxy, ethynyl, propargyl, propargyloxy, epoxy, oxetane, and hydroxyl.

[0054] As long as the resin (A) has the aforementioned crosslinking groups, it exhibits excellent curing properties. Therefore, as long as a pattern forming method using a composition for forming a resist underlayer film containing it is employed, a dense resist underlayer film pattern can be formed. The resist underlayer film pattern obtained in this way is more susceptible to modification by plasma irradiation, resulting in a resist underlayer film pattern with good edge roughness.

[0055] A pattern forming method is a method for forming a pattern of 1 / 2 pitch of the upper layer pattern of the resist on the substrate, characterized in that, after the step of subjecting the lower layer pattern of the resist to plasma irradiation, the following steps are included:

[0056] An inorganic silicon film composed of any of the following materials—polycrystalline silicon, amorphous silicon, silicon oxide, silicon nitride, silicon nitride oxide, silicon carbide, and composites thereof—is formed by CVD or ALD methods, covering the underlying pattern of the resist film.

[0057] The lower resist film pattern is removed by dry etching or stripping solution to form an inorganic silicon film pattern with a pattern pitch of 1 / 2 that of the upper resist film pattern.

[0058] Since such a pattern forming method can form a resist underlayer film pattern with good edge roughness, when used as the core of the sidewall liner method, it is possible to produce a sidewall pattern with even better edge roughness when the pattern pitch is 1 / 2.

[0059] [The effects of the invention]

[0060] As explained above, the miniaturization of DRAM memory has accelerated in recent years. In nanoscale high-resolution micropatterns, the proportion of edge roughness relative to the linewidth of the pattern has increased. Furthermore, reducing the edge roughness of the pattern has become more difficult than before, thus increasing the necessity for resist underlayer patterns with good edge roughness. In particular, the sidewall liner method, which adds films to the sidewalls on both sides of the line pattern to halve the pitch, makes reducing the edge roughness of the resist underlayer pattern a challenge. The resist underlayer patterning method of the present invention can provide resist underlayer patterns that exhibit excellent edge roughness compared to conventional organic underlayer patterns by plasma irradiation, and is therefore particularly suitable for use in multilayer resist processes, and is extremely useful in the micropatterning of semiconductor device manufacturing. Attached Figure Description

[0061] [ Figure 1 ] Figure 1 This is an illustrative diagram of an example of the pattern forming method of the present invention (3-layer resist process).

[0062] [ Figure 2 ] Figure 2 This is an explanatory diagram of an example of the pattern forming method of the present invention (sidewall lining method).

[0063] [ Figure 3 ] Figure 3 This is an illustrative diagram of an example of the pattern forming method of the present invention (utilizing a wet peeling sidewall lining method).

[0064] [ Figure 4 ] Figure 4 This is an explanatory diagram of an example of the pattern forming method of the present invention (sidewall lining method).

[0065] [ Figure 5 ] Figure 5 This is an explanatory diagram of another example of the pattern forming method of the present invention (sidewall lining method). Detailed Implementation

[0066] As mentioned above, there are methods for forming resist underlayer film patterns that can transfer resist patterns to the substrate with higher precision in micro-patterning processes using multilayer resist methods, and the development of resist underlayer film patterns that are useful as core materials in sidewall liner methods.

[0067] The inventors of this application explored a method for forming a resist underlayer pattern with low edge roughness. Through repeated and in-depth research, they discovered that by using a resist underlayer film formed with a composition containing a resin having aromatic rings, and then transferring the resist upper layer pattern by dry etching, followed by plasma irradiation, a resist underlayer film pattern with low edge roughness can be formed, thus completing this invention.

[0068] That is, the present invention provides a pattern forming method, which is a method for forming a resist underlayer film pattern on a substrate, characterized by comprising the following steps:

[0069] (i-1) After coating the substrate with a composition for forming a photoresist underlayer, a photoresist underlayer is formed by heat treatment.

[0070] (i-2) After coating the silicon-containing photoresist intermediate film with a composition for forming a silicon-containing photoresist, a silicon-containing photoresist intermediate film is formed by heat treatment.

[0071] (i-3) A top layer of photoresist is formed on the silicon-containing photoresist intermediate film.

[0072] (i-4) After the upper layer of the photoresist is exposed to a pattern, it is developed with a developer to form a pattern on the upper layer of the photoresist.

[0073] (i-5) A lower resist film pattern is formed by repeated etching using the upper resist film pattern as a mask, and

[0074] (i-6) The pattern of the lower layer of the resist film is subjected to plasma irradiation;

[0075] As a component for forming the lower film of this resist, a resin containing an aromatic ring is used.

[0076] The plasma used for plasma irradiation in step (i-6) is less etched than the etching gas used in step (i-5) to form the resist underlayer pattern by etching the resist underlayer.

[0077] Furthermore, the present invention is a pattern forming method, which is a method for forming a resist underlayer film pattern on a substrate, characterized by comprising the following steps:

[0078] (ii-1) After coating the substrate with a composition for forming a photoresist underlayer, a photoresist underlayer is formed by heat treatment.

[0079] (ii-2) An inorganic hard mask intermediate film selected from silicon oxide film, silicon nitride film, and silicon oxide nitride film is formed on the lower layer of the resist film.

[0080] (ii-3) A resist upper layer film is formed on the intermediate film of the inorganic hard mask.

[0081] (ii-4) After the upper layer of the photoresist is exposed to a pattern, it is developed using a developer to form a pattern on the upper layer of the photoresist.

[0082] (ii-5) A lower resist film pattern is formed by repeated etching using the upper resist film pattern as a mask, and

[0083] (ii-6) The pattern of the lower layer of the resist film is subjected to plasma irradiation;

[0084] As a component for forming the lower film of this resist, a resin containing an aromatic ring is used.

[0085] The plasma used for plasma irradiation in step (ii-6) is less etched than the etching gas used in step (ii-5) to form the resist underlayer pattern by etching the resist underlayer.

[0086] The present invention will now be described in detail, but the present invention is not limited thereto.

[0087] [Pattern Formation Method]

[0088] This invention provides a pattern forming method for forming a resist underlayer pattern on a substrate, characterized by comprising the following steps:

[0089] (i-1) After coating the substrate with a composition for forming a photoresist underlayer, a photoresist underlayer is formed by heat treatment.

[0090] (i-2) After coating the silicon-containing photoresist intermediate film with a composition for forming a silicon-containing photoresist, a silicon-containing photoresist intermediate film is formed by heat treatment.

[0091] (i-3) A top layer of photoresist is formed on the silicon-containing photoresist intermediate film.

[0092] (i-4) After the upper layer of the photoresist is exposed to a pattern, it is developed with a developer to form a pattern on the upper layer of the photoresist.

[0093] (i-5) A lower resist film pattern is formed by repeated etching using the upper resist film pattern as a mask, and

[0094] (i-6) The pattern of the lower layer of the resist film is subjected to plasma irradiation;

[0095] As a component for forming the lower film of this resist, a resin containing an aromatic ring is used.

[0096] The plasma used for plasma irradiation in step (i-6) is less etched than the etching gas used in step (i-5) to form the resist underlayer pattern by etching the resist underlayer.

[0097] Furthermore, in this invention, the plasma used for plasma irradiation in step (i-6) needs to be one that etches the lower resist film to a lesser extent compared to the etching gas used in step (i-5) for the lower resist film. By using a plasma for plasma irradiation in step (i-6) that etches the lower resist film to a lesser extent compared to the etching gas used in step (i-5), a pattern for the lower resist film can be obtained in step (i-5), while preventing damage or loss of the pattern in the lower resist film obtained in step (i-6).

[0098] Alternatively, a pattern forming method may be used, which is a method for forming a resist underlayer pattern on a substrate, characterized by comprising the following steps:

[0099] (ii-1) After coating the substrate with a composition for forming a photoresist underlayer, a photoresist underlayer is formed by heat treatment.

[0100] (ii-2) An inorganic hard mask intermediate film selected from silicon oxide film, silicon nitride film, and silicon oxide nitride film is formed on the lower layer of the resist film.

[0101] (ii-3) A resist upper layer film is formed on the intermediate film of the inorganic hard mask.

[0102] (ii-4) After the upper layer of the photoresist is exposed to a pattern, it is developed using a developer to form a pattern on the upper layer of the photoresist.

[0103] (ii-5) A lower resist film pattern is formed by repeated etching using the upper resist film pattern as a mask, and

[0104] (ii-6) The pattern of the lower layer of the resist film is subjected to plasma irradiation;

[0105] As a component for forming the lower film of this resist, a resin containing an aromatic ring is used.

[0106] The plasma used for plasma irradiation in step (ii-6) is less etched than the etching gas used in step (ii-5) to form the resist underlayer pattern by etching the resist underlayer.

[0107] Furthermore, as described above, the plasma used for plasma irradiation in step (ii-6) needs to be one that etches the resist underlayer film to a lesser extent than the etching gas used in step (ii-5) for the resist underlayer film. By using a plasma for plasma irradiation in step (ii-6) that etches the resist underlayer film to a lesser extent than the etching gas used in step (ii-5), a pattern for the resist underlayer film can be obtained in step (ii-5), while preventing damage or loss of the pattern in the resist underlayer film obtained in step (ii-6).

[0108] Specifically, the pattern forming method of the present invention can be exemplified by the following pattern forming methods.

[0109] An illustrative diagram illustrating an example of the pattern forming method of the present invention (a 3-layer resist process) is shown in [the diagram]. Figure 1 A lower resist film (3), a silicon-containing intermediate film (4), and a upper resist film (5) are formed on a substrate (1) having a processing layer (2). The upper resist film is exposed (6) and removed by development and washing to form an upper resist film pattern (5a). The obtained upper resist film pattern (5a) is used as a mask for dry etching, and then transferred to the silicon-containing intermediate film pattern (4a) and the lower resist film pattern (3a), followed by plasma irradiation. The plasma-irradiated silicon-containing intermediate film pattern (4b) and the lower resist film pattern (3b) are transferred to the processing layer (2) by dry etching to form the processing layer pattern (2b).

[0110] Another example of the pattern forming method of the present invention (sidewall lining method) is illustrated in the explanatory diagram. Figure 2 A lower resist film (3), a silicon-containing intermediate film (4), and a upper resist film (5) are formed on a substrate (1) having a processing layer (2). The upper resist film is exposed (6) and removed by development and washing to form an upper resist film pattern (5a). The obtained upper resist film pattern (5a) is used as a mask for dry etching, and then transferred to the silicon-containing intermediate film pattern (4a) and the lower resist film pattern (3a), followed by plasma irradiation. The plasma-irradiated silicon-containing intermediate film pattern (4b) and the lower resist film pattern (3b) are coated with an inorganic silicon film (7) by CVD or ALD, and then dry-etched to remove the silicon-containing intermediate film (4b) and the lower resist film (3b), thereby forming an inorganic silicon film pattern (7a).

[0111] The following steps are described in detail in sequence.

[0112] [Step (i-1), Step (ii-1)]

[0113] Steps (i-1) and (ii-1) are steps of forming a resist underlayer film on the substrate.

[0114] <Substrate>

[0115] As a substrate, it can be used as a processed layer (processed part) on a semiconductor manufacturing substrate, and is formed by forming any one of a metal film, a metal carbide film, a metal oxide film, a metal nitride film, and a composite of these films.

[0116] As a substrate for semiconductor manufacturing, silicon substrates are generally used, but there are no particular limitations. Materials different from those of the processed layer, such as Si, amorphous silicon (α-Si), p-Si, SiO2, SiN, SiON, W, TiN, and Al, can also be used. As the metal constituting the processed layer, any of silicon, titanium, tungsten, hafnium, zirconium, chromium, germanium, copper, aluminum, and iron, or their alloys, can be used. As the processed layer containing such metals, materials such as 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 etch-blocking films, can be used, and a thickness of 50 to 10,000 nm, especially 100 to 5,000 nm, can be formed.

[0117] <Organic corrosion resist underlayer film>

[0118] As the composition for forming the organic underlayer film used in this invention, considering factors such as spin-coating film-forming properties, curing properties, etching resistance, optical properties, and heat resistance, a resin containing aromatic rings is preferable. Furthermore, by containing aromatic rings in the resin, it is easier to induce film modification due to plasma irradiation, thereby forming a resist underlayer film pattern with low edge roughness.

[0119] Examples of aromatic rings mentioned above include benzene, naphthalene, anthracene, pyrene, indene, fluorene, furan, pyrrole, thiophene, phosphole, pyrazole, oxazole, isoxazole, thiazole, pyridine, pyrazine, pyrimidine, pyridazine, triazine, and carbazole. Among these, benzene, naphthalene, and fluorene are particularly suitable.

[0120] The composition for forming the lower layer film of the aforementioned resist is more preferably a resin containing (A), wherein the (A) resin is

[0121] (a) Polystyrene-equivalent polymers with a weight average molecular weight of 2,500 to 20,000 as determined by gel permeation chromatography with aromatic rings in the main chain.

[0122] (b) Compounds containing aromatic rings with a weight-average molecular weight of 600 to 3,000 based on polystyrene equivalents obtained by gel permeation chromatography.

[0123] Or a combination thereof.

[0124] It is preferable to use a resin having at least one crosslinking group selected from vinyl, allyl, allyloxy, ethynyl, propargyl, propargyloxy, epoxy, oxetane, and hydroxyl for the above (A) resin.

[0125] If the resin (A) has the aforementioned crosslinking groups, it exhibits excellent curing properties. Therefore, if a pattern forming method using a composition for forming a resist underlayer film containing this resin is employed, a dense resist underlayer film pattern can be formed. The resist underlayer film pattern obtained in this way is more susceptible to modification by plasma irradiation, resulting in a resist underlayer film pattern with good edge roughness.

[0126] Examples of resins containing aromatic rings suitable for use in this invention include resins containing the following structures as described in Japanese Patent Application Publication No. 2012-1687 and Japanese Patent Application Publication No. 2012-77295.

[0127] [Chemistry 1]

[0128]

[0129] (In formula (1), ring structures Ar1 and Ar2 represent benzene rings or naphthalene rings. 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 that makes the molecular weight less than 100,000. Furthermore, the symbols in the formula are only applicable to this formula.)

[0130] [Chemistry 2]

[0131]

[0132] (In equation (2), the ring structures Ar1 and Ar2 represent benzene rings or naphthalene rings. n represents any natural number that makes the equivalent weight-average molecular weight of polystyrene for gel permeation chromatography less than 100,000. Furthermore, the symbols in the equation are only applicable to this equation.)

[0133] Resins containing aromatic rings applicable to the present invention may further be exemplified by resins containing the following structures as described in Japanese Patent Application Publication Nos. 2004-264710, 2005-043471, 2005-250434, 2007-293294, and 2008-65303.

[0134] [Chemistry 3]

[0135]

[0136] (In equations (3) and (4), R) 1 and R 2 R represents a hydrogen atom or an alkyl or aryl group having 1 to 3 carbon atoms. 3 The symbols represent alkyl, vinyl, allyl, or substituted aryl groups having 1 to 3 carbon atoms; n represents 0 or 1, and m represents 0, 1, or 2. Furthermore, the symbols in the formula apply only to that specific formula.

[0137] [Chemistry 4]

[0138]

[0139] (In equation (5), R1 is a monovalent atom or group other than hydrogen, and n is an integer from 0 to 4. However, when n is 2 to 4, the complex R1s can be the same or different. R2 and R3 are independently monovalent atoms or groups. X is a divalent group. In addition, the symbols in the equation are only applicable to this equation.)

[0140] [Chemistry 5]

[0141]

[0142] (In equation (6), R) 1 It is a hydrogen atom or a methyl group. R 2 It is any of the following: a single bond, a straight-chain, branched, or cyclic alkylene group having 1 to 20 carbon atoms, or an arylene group having 6 to 10 carbon atoms; it may also be any of the following: ether, ester, lactone, or amide. R 3 R 4 Each is either a hydrogen atom or an epoxypropyl group. X represents a polymer containing an indene skeleton, a cycloolefin with 3 to 10 carbon atoms, or a maleimide; it may also contain any of the following: ether, ester, lactone, or carboxylic anhydride. R 5 R 6 Each is one of a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R 7 It is any one of hydrogen atoms, and a linear, branched, or cyclic alkyl, hydroxyl, or alkoxycarbonyl group having 1 to 6 carbon atoms. p and q are each integers from 1 to 4. R is an integer from 0 to 4. a, b, and c are each within the range 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. Furthermore, the symbols in the formula are only applicable within that specific formula.

[0143] [Chemistry 6]

[0144]

[0145] (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. In addition, the symbols in the formula are only applicable to that formula.)

[0146] As the resin having an aromatic ring applicable to the present invention, specifically, resins containing the following structures described in JP-A-2004-205685, JP-A-2007-171895, and JP-A-2009-14816 can be exemplified, etc.

[0147] [Chemical formula 7]

[0148]

[0149] (In formulas (8) and (9), R[[ID=​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​

[0153] [Chemistry 9]

[0154]

[0155] (In the formula, n represents 0 or 1. R) 1 This indicates a substituted methylene group, a substituted alkyl group having 2 to 20 carbon atoms, or a substituted aryl group having 6 to 20 carbon atoms. R 2 R represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms that can be substituted, or an aryl group having 6 to 20 carbon atoms that can be substituted. 3 ~R 7 R represents a hydroxyl group, an alkyl group having 1 to 6 carbon atoms that can be substituted, an alkoxy group having 1 to 6 carbon atoms that can be substituted, an alkoxycarbonyl group having 2 to 10 carbon atoms that can be substituted, an aryl group having 6 to 14 carbon atoms that can be substituted, or an epoxypropyl ether group having 2 to 6 carbon atoms that can be substituted. 9 This represents a hydrogen atom, a straight-chain, branched, or cyclic alkyl group having 1 to 10 carbon atoms, a straight-chain, branched, or cyclic alkyl ether group having 1 to 10 carbon atoms, or an aryl group having 6 to 10 carbon atoms. Furthermore, the symbols in the formula are only applicable in that specific formula.

[0156] For example, the following compounds are examples.

[0157] [Chemistry 10]

[0158]

[0159] Examples of resins containing aromatic rings suitable for use in this invention include resins containing the following structures as described in Japanese Patent Application Publication No. 2007-199653, Japanese Patent Application Publication No. 2008-274250, and Japanese Patent Application Publication No. 2010-122656.

[0160] [Chemistry 11]

[0161]

[0162] (In equation (12), R) 1 With R 2 Independently composed of the same or different hydrogen atoms, a straight-chain, branched, or cyclic alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, or an alkenyl group having 2 to 10 carbon atoms, R 3 It is a single bond, or a straight-chain, branched, or cyclic alkylene group having 1 to 30 carbon atoms; it may also have a bridged cyclic hydrocarbon group, double bond, heteroatom, or aromatic group having 6 to 30 carbon atoms. R 4 With R 5 Each atom can be independently represented as a hydrogen atom or an epoxypropyl group, where n is an integer from 1 to 4. Furthermore, the symbols used in the formula are only applicable within that specific formula.

[0163] [Chemistry 12]

[0164]

[0165] (In equation (13), R) 1 With R 2 Independently composed of the same or different hydrogen atoms, a straight-chain, branched, or cyclic alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, or an alkenyl group having 2 to 10 carbon atoms, R 3 It is a single bond, or a straight-chain, branched, or cyclic alkylene group having 1 to 30 carbon atoms; it may also have a bridged cyclic hydrocarbon group, double bond, heteroatom, or aromatic group having 6 to 30 carbon atoms. R 4 With R 5 Each is independently a hydrogen atom or an epoxypropyl group, R 6 It is a single-bonded, or straight-chain or branched alkylene group having 1 to 10 carbon atoms. Furthermore, the symbols in the formula apply only to that specific formula.

[0166] [Chemistry 13]

[0167]

[0168] (In equation (14), ring Z) 1 and ring Z 2 It is a condensed polycyclic aromatic hydrocarbon ring, R 1a R 1b R 2a and R 2b The same or different symbols indicate substituents. The same or different symbols for k1 and k2 indicate integers from 0 to 4; m1 and m2 each indicate integers greater than or equal to 1; n1 and n2 each indicate integers greater than or equal to 1. However, n1 + n2 ≥ 1. Furthermore, the symbols in the formula only apply to that specific formula.

[0169] [Chemistry 14]

[0170]

[0171] (In equation (15), R) 1 R 2 It can be the same or different hydrogen atoms, a straight-chain, branched, or cyclic alkyl group with 1 to 10 carbon atoms, an aryl group with 6 to 10 carbon atoms, or an alkenyl group with 2 to 10 carbon atoms. R 3 R 4 Each is either a hydrogen atom or an epoxypropyl group, R 5 It is a single-bonded, straight-chain or branched alkylene group with 1 to 10 carbon atoms, R 6 R 7It is a benzene ring or a naphthalene ring. p and q are each 1 or 2. n is 0 < n ≤ 1. In addition, the symbols in the formula are only applicable to this formula.)

[0172] For example, the following compounds are exemplified.

[0173] [Chemical Formula 15]

[0174]

[0175] [Chemical Formula 16]

[0176]

[0177] [Chemical Formula 17]

[0178]

[0179] [Chemical Formula 18]

[0180]

[0181] Examples of the resin having an aromatic ring applicable to the present invention include resins described in Japanese Patent Laid-Open No. 2014-29435, International Publication WO2012 / 077640, International Publication WO2010 / 147155, etc.

[0182] [Chemical Formula 19]

[0183]

[0184] (In Formula (17), A represents a structure having carbazole, B represents a structure having an aromatic ring, C represents a hydrogen atom, an alkyl group or a structure having an aromatic ring, and B and C may also form a ring with each other. The combination of the structures of A, B, and C has 1 to 4 carboxyl groups or their salts, or carboxylic acid ester groups. In addition, the symbols in the formula are only applicable to this formula.)

[0185] In addition, examples include a polymer described in International Publication WO2012 / 077640, which contains a unit structure represented by the following Formula (18) and a unit structure represented by the following Formula (19), and the ratio of the unit structure represented by Formula (18) to the unit structure represented by Formula (19) is 3 to 97:97 to 3 in terms of molar ratio.

[0186] [Chemical Formula 20]

[0187] [[ID=​In formula (18), R1 and R2 each independently represent a hydrogen atom, a halogen atom, a nitro group, an amino group, a hydroxyl group, an alkyl group with 1 to 10 carbon atoms, an alkenyl group with 2 to 10 carbon atoms, an aryl group with 6 to 40 carbon atoms, or may contain an ether bond, a ketone bond, or an ester bond. R3 represents a hydrogen atom, an alkyl group with 1 to 10 carbon atoms, an alkenyl group with 2 to 10 carbon atoms, an aryl group with 6 to 40 carbon atoms, or may contain an ether bond, a ketone bond, or an ester bond. A combination of these groups. R4 represents a hydrogen atom, or an aryl or heterocyclic group with 6 to 40 carbon atoms, which may also be substituted with a halogen atom, nitro group, amino group, or hydroxyl group. R5 represents a hydrogen atom, or an alkyl, aryl, or heterocyclic group with 1 to 10 carbon atoms, which may also be substituted with a halogen atom, nitro group, amino group, or hydroxyl group. R4 and R5 can also form rings with each other. n1 and n2 each represent integers from 1 to 3. Furthermore, the symbols in the formula are only applicable to this formula.

[0189] [Chemistry 21]

[0190]

[0191] (In formula (19), Ar represents an aromatic ring group with 6 to 20 carbon atoms, R6 represents a hydroxyl group, and R7 represents a combination of these groups, including hydrogen, halogen, nitro, amino, alkyl with 1 to 10 carbon atoms, alkenyl with 2 to 10 carbon atoms, aryl with 6 to 40 carbon atoms, or groups containing ether, ketone, or ester bonds. R8 represents a hydrogen atom, or an aryl or heterocyclic group with 6 to 40 carbon atoms that may be substituted with a halogen, nitro, amino, or hydroxyl group. R9 represents a hydrogen atom, or an alkyl, aryl, or heterocyclic group with 1 to 10 carbon atoms that may be substituted with a halogen, nitro, amino, or hydroxyl group. R8 and R9 can also form rings with each other. n6 represents an integer from 1 to p, and n7 represents an integer from p to n6. Here, p represents the largest number that Ar can be substituted for in the aromatic ring group. Furthermore, the symbols in the formula are only applicable to this formula.)

[0192] As a resin with an aromatic ring suitable for use in the present invention, a polymer containing a unit structure represented by the following formula (20) as described in International Publication No. WO2010 / 147155 may be cited as an example.

[0193] [Chemistry 22]

[0194]

[0195] In formula (20), R1 and R2 each represent a group selected from the group consisting of hydrogen atoms, halogen groups, nitro groups, amino groups, hydroxyl groups, alkyl groups having 1 to 10 carbon atoms, alkenyl groups having 2 to 10 carbon atoms, aryl groups having 6 to 40 carbon atoms, and combinations thereof, wherein the alkyl, alkenyl, or aryl group may also contain ether bonds, ketone bonds, or ester bonds; R3 represents a group selected from the group consisting of hydrogen atoms, alkyl groups having 1 to 10 carbon atoms, alkenyl groups having 2 to 10 carbon atoms, aryl groups having 6 to 40 carbon atoms, and combinations thereof, and The alkyl, alkenyl, or aryl group may also contain ether, ketone, or ester bonds. R4 represents an aryl or heterocyclic group with 6 to 40 carbon atoms, which may also be substituted with a halogen, nitro, amino, or hydroxyl group. R5 represents a hydrogen atom, or an alkyl, aryl, or heterocyclic group with 1 to 10 carbon atoms, which may also be substituted with a halogen, nitro, amino, or hydroxyl group. R4 and R5 may also form a ring with these bonded carbon atoms. n1 and n2 are each integers from 1 to 3. Furthermore, the symbols in the formula are only applicable to this specific formula.

[0196] As a resin with an aromatic ring suitable for use in this invention, examples include using an acidic catalyst to react one or more of the following phenols: phenol, cresol, xylenol, catechol, resorcinol, hydroquinone, pyrogallol, trimesophenol, and phlorogallol with formaldehyde, paraformaldehyde, and trioxane. Phenolic varnish resins obtained by reacting one or more aldehyde sources such as trioxane, and resins containing repeating unit structures represented by the following formula (21) as described in International Publication No. WO2012 / 176767.

[0197] [Chemistry 23]

[0198]

[0199] (In formula (21), A represents a hydroxylated phenylene derived from polyhydroxybenzene, and B represents a monovalent condensed aromatic hydrocarbon cyclic group formed by the condensation of 2 to 6 benzene rings. Furthermore, the symbols in the formula are only applicable to this formula.)

[0200] Examples of phenolic varnish resins with aromatic rings suitable for use in this invention include those described in Japanese Patent Application Publication Nos. 2005-128509, 2006-259249, 2006-259482, 2006-293298, and 2007-316282, which are resins containing repeating unit structures represented by the following formula (22-1) or (22-2).

[0201] [Chemistry 24]

[0202]

[0203] In equations (22-1) and (22-2), R 1 R 2 R 6 R 7 Independently comprising a hydrogen atom, a straight-chain, 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 Independently comprising a hydrogen atom, a straight-chain, branched, or cyclic alkyl group having 1 to 6 carbon atoms, a straight-chain, branched, or cyclic alkenyl group having 2 to 6 carbon atoms, an aryl group having 6 to 10 carbon atoms, or an epoxypropyl group, R 5 R 14 Independently composed of hydrogen atoms, a straight-chain, 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 from 1 to 3. R 10 ~R 13 Independently comprising a hydrogen atom, a halogen atom, a hydroxyl group, a straight-chain, branched, or cyclic alkyl group having 1 to 6 carbon atoms, or a straight-chain, branched, or cyclic alkoxy group having 1 to 6 carbon atoms. Furthermore, the symbols in the formula apply only to that formula.

[0204] As an aromatic ring-containing resin suitable for use in the present invention, the reactant obtained by the method described in Japanese Patent Application Publication No. 2012-145897 can be cited as an example.

[0205] More specifically, examples can be given of polymers obtained by condensing one or more compounds represented by the following general formulas (23-1) and / or (23-2) with one or more compounds represented by the following general formulas (24-1) and / or (24-2) and / or their equivalents.

[0206] [Chemistry 25]

[0207]

[0208] (In equations (23-1) and (23-2), R) 1 ~R 8 Independently, these groups can be hydrogen atoms, halogen atoms, hydroxyl groups, isocyanate groups, epoxypropoxy groups, carboxyl groups, amino groups, alkoxy groups with 1 to 30 carbon atoms, alkoxycarbonyl groups with 1 to 30 carbon atoms, alkanoyloxy groups with 1 to 30 carbon atoms, or substituted organic groups with 1 to 30 carbon atoms, whether saturated or unsaturated. Furthermore, they can also be formed intramolecularly from R... 1 ~R 4 or R 5 ~R 8Each group can arbitrarily select two substituents to form bonds, which can also form cyclic substituents. Furthermore, the symbols in the formula are only applicable to that specific formula.

[0209] [Chemistry 26]

[0210]

[0211] (In formulas (24-1) and (24-2), Q is an organic group with 1 to 30 carbon atoms that can be substituted. Furthermore, any two Q groups can be selected within the molecule to form a bond, or a cyclic substituent can be formed. n1 to n6 are the numbers of each substituent, n1 to n6 = 0, 1, and 2. Formula (24-1) excludes hydroxybenzaldehyde. In addition, formula (24-2) conforms to the relationships 0 ≤ n3 + n5 ≤ 3, 0 ≤ n4 + n6 ≤ 4, and 1 ≤ n3 + n4 ≤ 4. Furthermore, the symbols in the formula are only applicable to that specific formula.)

[0212] Furthermore, examples can be given of polymers 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 their equivalents, and one or more compounds represented by the following general formula (25) and / or their equivalents.

[0213] [Chemistry 27]

[0214] Y-CHO(25)

[0215] (In formula (25), Y is a hydrogen atom or a monovalent organic group with 30 or fewer carbon atoms that may have substituents. Formula (25) is different from formulas (24-1) and (24-2). Furthermore, the symbols in the formula are only applicable to this formula.)

[0216] Examples of resins containing aromatic rings suitable for use in this invention include polymers having repeating units represented by the following general formula (27-1) as described in Japanese Patent Application Publication No. 2019-44022.

[0217] [Chemistry 28]

[0218]

[0219] In formula (27-1), AR1 and AR2 are benzene rings or naphthalene rings that may also have substituents, R 1 R 2 Each is independently a hydrogen atom or an organic group having 1 to 30 carbon atoms, in R 1 With R 2 In the case of organic groups, it can also be achieved through R 1 With R 2Intramolecular bonding forms cyclic organic groups. n is 0 or 1. When n = 0, AR1 and AR2 do not intersect each other via Z to form a bridging structure between the aromatic rings of AR1 and AR2. When n = 1, AR1 and AR2 intersect each other via Z to form a bridging structure between the aromatic rings of AR1 and AR2. Z is a single bond or any of the following formula (27-2). Y is the group represented by the following formula (27-3). Furthermore, the symbols in the formula are only applicable to that specific formula.

[0220] [Chemistry 29]

[0221] -CH2- -CH2-CH2- -O- -S-

[0222] [Chemistry 30]

[0223] ----R 3 -C≡CR 4 (27-3)

[0224] (where R is in the formula) 3 It is a single bond or a divalent organic group with 1 to 20 carbon atoms, R 4 It is a monovalent organic group with 1 to 20 hydrogen atoms or carbon atoms; the dashed line represents an atomic bond. Furthermore, the symbols in the formula are only applicable to that specific formula.

[0225] For example, the following polymers are exemplified.

[0226] [Chemistry 31]

[0227]

[0228] [Chemistry 32]

[0229]

[0230] Resins containing aromatic rings can be synthesized by known methods and can also be used in commercially available products.

[0231] Examples of resins containing aromatic rings suitable for use in this invention include resins containing the following structure as described in Japanese Patent Application Publication No. 2012-214720.

[0232] [Chemistry 33]

[0233]

[0234] (In equation (16), the ring structures Ar1 and Ar2 represent benzene rings or naphthalene rings. x and z each independently represent 0 or 1. Furthermore, the symbols in the equation are only applicable to this equation.)

[0235] Examples of resins containing aromatic rings suitable for use in this invention include resins containing the following structure as described in Japanese Patent Application Publication No. 2017-119671.

[0236] [Chemistry 34]

[0237]

[0238] (In formula (26-1), R is a single bond or an organic group with 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. Furthermore, the symbols in the formula are only applicable to this formula.)

[0239] [Chemistry 35]

[0240]

[0241] (where X) 2 It is a divalent organic group with 1 to 10 carbon atoms, where n1 is 0 or 1, n2 is 1 or 2, and X 3 It is the group represented by the following general formula (26-3), where n5 is 0, 1, or 2. Furthermore, the symbols in the formula apply only to that specific formula.

[0242] [Chemistry 36]

[0243]

[0244] (where R is in the formula) 10 It is a hydrogen atom or a saturated or unsaturated hydrocarbon group having 1 to 10 carbon atoms. The hydrogen atoms on the benzene ring in the formula can also be replaced by methyl or methoxy groups. Furthermore, the symbols in the formula are only applicable to that specific formula.

[0245] For example, the following compounds are examples.

[0246] [Chemistry 37]

[0247]

[0248] The coating method for the composition used to form the resist underlayer film in steps (i-1) and (ii-1) above is not particularly limited. Details regarding the composition used to form the resist underlayer film will be described later.

[0249] In steps (i-1) and (ii-1) above, the heat treatment (baking) temperature of the coating is set to a temperature of 100°C to 800°C, more preferably 150°C to 600°C, further preferably 150°C to 450°C, and even more preferably 200°C to 400°C. The baking time is set to a range of 10 seconds to 7,200 seconds, more preferably 30 seconds to 600 seconds.

[0250] By appropriately adjusting the baking temperature and time within the above range, curing properties such as planarization and embedding characteristics, dry etching resistance, and heat resistance suitable for the application can be obtained. By performing heat treatment (baking) within a temperature range of 150°C to 600°C, the film becomes rich in active sites that cause the dissociation and rebonding of carbon bonds in the underlying film, making it easier to promote film modification by plasma irradiation. Therefore, a resist underlying film pattern with low edge roughness after plasma irradiation can be formed. Baking temperatures above 100°C reduce residual solvent in the film and suppress film shrinkage degradation caused by plasma irradiation. Baking temperatures below 800°C suppress the thermal decomposition of the base resin and provide a resist underlying film with low sublimation content. Heat treatment can also be performed in stages (stage baking).

[0251] Furthermore, in steps (i-1) and (ii-1) above, the heat treatment can be carried out in an environment with an oxygen concentration of 1% to 21%.

[0252] This method can activate the reaction sites of the resin in the lower layer of the resist film, thereby promoting the hardening reaction caused by plasma irradiation.

[0253] Alternatively, in steps (i-1) and (ii-1) above, the heat treatment can also be carried out in an environment with an oxygen concentration of less than 1%.

[0254] Regarding the baking environment, either a moderately oxygenated environment (oxygen concentration of 1% to 21%) or a moderately oxygen-free environment (oxygen concentration of nitrogen) can be selected according to the requirements. For example, when the substrate being processed is easily oxidized by air, heat treatment in an environment with an oxygen concentration of less than 1% can form a hardened film, thus suppressing substrate damage.

[0255] In steps (i-1) and (ii-1) above, plasma irradiation can also be performed after the underlayer of the resist is baked. The plasma irradiation procedure is as described below.

[0256] The patterning method of the present invention can also perform plasma irradiation in multiple stages after the formation of the resist underlayer film and after the formation of the resist underlayer film pattern. This method can further promote the modification of the resist underlayer film pattern.

[0257] [Step (i-2)]

[0258] Step (i-2) is the step of forming a silicon-containing photoresist intermediate film on the photoresist lower layer film.

[0259] <Silicone-containing photoresist interlayer>

[0260] There are no particular limitations on the silicon-containing photoresist interlayer (silicon-coated interlayer) used in the pattern forming method of the present invention. The silicon-containing interlayers that can be used here are generally known. In the case where the pattern of the photoresist underlayer film results in the presence of silicon-containing photoresist interlayer residue on the photoresist underlayer film, the silicon-containing film residue from dry etching and the photoresist underlayer film need to be simultaneously removed by a stripping solution. Therefore, the silicon content in the silicon-containing photoresist interlayer film is preferably 45% by weight or less, more preferably 40% by weight or less, and particularly preferably 35% by weight or less.

[0261] Furthermore, it is preferable to form a silicon-containing photoresist interlayer film from a silicon-containing photoresist interlayer film composition containing a compound with a cross-linked organic structure.

[0262] If so, then the silicon-containing photoresist intermediate film can be more reliably removed simultaneously with the photoresist underlayer film by cleaning with the stripping solution after dry etching.

[0263] At this point, the cross-linked organic structure should preferably be selected from one or more of the following: ethylene oxide ring, oxobutane ring, hydroxyl group, or carboxyl group.

[0264] If it is such a cross-linked organic structure, then it becomes a silicon-containing photoresist intermediate film that can be more reliably removed simultaneously with the photoresist underlayer film by cleaning with a stripping solution after dry etching.

[0265] Furthermore, the composition for forming the intermediate film of the silicon resist should preferably contain an acid generating agent that generates acid by means of heat or light, or both.

[0266] Furthermore, the composition for forming the intermediate film of the silicon-containing photoresist should preferably contain a crosslinking agent.

[0267] If such a composition is used to form a silicon-containing photoresist intermediate film, a silicon-containing photoresist intermediate film can be formed that promotes the crosslinking of ethylene oxide rings, oxobutane rings, hydroxyl groups, or carboxyl groups contained in the crosslinking organic structure, and can be reliably cleaned and removed simultaneously with the photoresist underlayer film even after dry etching.

[0268] There are no particular limitations on the composition for forming such a silicon-containing photoresist intermediate film and the resin used in the composition. Examples of resins and compositions shown in Japanese Patent Application Publication Nos. 2004-310019, 2005-15779, 2005-18054, 2005-352104, and 2007-226170 are provided.

[0269] Specific examples of resins contained in the composition for forming a silicon-containing resist intermediate film used in this invention include polysiloxanes containing one or more of the following general formula (A-1), their hydrolysates, their condensates, and their hydrolysates.

[0270] [Chemistry 38]

[0271] R 1A A1 R 2A A2 R 3A A3 Si(OR OA ) (4-A1-A2-A3) (A-1)(where R is the formula) 0A It is a hydrocarbon group with 1 to 6 carbon atoms, R 1A R 2A R 3A It is a hydrogen atom or a monovalent organic group. Furthermore, A1, A2, and A3 are either 0 or 1, where 0 ≤ A1 + A2 + A3 ≤ 3.

[0272] As R 1A R 2A R 3A Examples of the organic groups represented include organic groups having one or more carbon-oxygen single bonds or carbon-oxygen double bonds. Specifically, it refers to organic groups having one or more groups selected from the group consisting of ethylene oxide rings, oxetane rings, ester bonds, alkoxy groups, and hydroxyl groups. Examples of such groups include those represented by the following general formula (A-2).

[0273] [Chemistry 39]

[0274] (

[0275] (In general formula (A-2), P is a hydrogen atom, an ethylene oxide ring, an oxobutane ring, a hydroxyl group, an alkoxy group with 1 to 4 carbon atoms, an alkyl carbonyloxy group with 1 to 6 carbon atoms, or an alkyl carbonyl group with 1 to 6 carbon atoms; Q1, Q2, Q3, and Q4 are each independently -CqH(2q-p)Pp- (where P is the same as above, p is an integer from 0 to 3, and q is an integer from 0 to 10 (but q = 0 indicates a single bond)); u is an integer from 0 to 3; and S1 and S2 independently represent -O- and -CO- respectively.) -OCO-, -COO-, or -OCOO-. v1, v2, and v3 each independently represent 0 or 1. Together with these, T is a divalent group composed of an alicyclic or aromatic ring, which may also contain heteroatoms and heteroatoms such as ethylene oxide rings, oxobutane rings, etc. Examples of alicyclic or aromatic rings containing heteroatoms such as oxygen atoms in T are described later. There are no particular restrictions on the position of the bonds in T to Q2 and Q3, and appropriate choices can be made considering factors such as reactivity due to steric factors or the availability of commercially available reagents used in the reaction.

[0276] [Step (ii-2)]

[0277] Step (ii-2) is the step of forming an inorganic hard mask intermediate film selected from silicon oxide film, silicon nitride film and silicon oxide nitride film on the resist underlayer film.

[0278] <Inorganic Hard Mask Intermediate Film>

[0279] In the case of forming an inorganic hard mask interlayer film on top of a photoresist underlayer film, silicon oxide films, silicon nitride films, and silicon oxide nitride films (SiON films) can be formed by methods such as CVD and ALD. For example, methods for forming silicon nitride films are described in Japanese Patent Application Publication No. 2002-334869 and International Publication No. 2004 / 066377. The thickness of the inorganic hard mask interlayer film is preferably 5 to 200 nm, and more preferably 10 to 100 nm. Furthermore, SiON films, which have high anti-reflection properties, are most suitable as inorganic hard mask interlayer films. The substrate temperature during SiON film formation is 300 to 500°C, therefore the photoresist underlayer film needs to be able to withstand temperatures of 300 to 500°C. The composition for forming the resist underlayer film used in this invention has high heat resistance and can withstand high temperatures of 300°C to 500°C. It can be combined with an inorganic hard mask intermediate film formed by CVD or ALD and a resist underlayer film formed by spin coating.

[0280] A photoresist film can be formed on top of the inorganic hard mask interlayer as the upper layer of the photoresist film. Alternatively, an organic antireflective film (BARC) or a close-fitting film can be formed on top of the inorganic hard mask interlayer by spin coating, and then a photoresist film can be formed on top of it. In particular, when a SiON film is used as the inorganic hard mask interlayer, the two-layer antireflective film of SiON film and BARC can suppress reflection even in immersion exposure with a high nanometer polarity (NA) exceeding 1.0. Another advantage of forming BARC is that it reduces the trailing of the photoresist pattern on the SiON film.

[0281] [Steps (i-3) and (ii-3)]

[0282] Steps (i-3) and (ii-3) are steps for forming the upper layer film of the resist.

[0283] <Resist Top Layer Film>

[0284] There are no particular limitations on the resist top film that can be used in the pattern forming method of the present invention, and any of the various resist films known in the past can be used.

[0285] In the above-described pattern formation method, the upper resist film can be either positive or negative, and can be the same as commonly used photoresist compositions. Furthermore, the photoresist composition may contain metal atoms such as Sn, In, Ga, Ge, Al, Ce, La, Cs, Zr, Hf, Ti, Bi, Sb, and Zn. When forming the upper resist film using the above-described photoresist composition, it can be done by spin coating or by vapor deposition using CVD or ALD.

[0286] When forming the top layer of the resist film by spin coating, pre-baking is performed after the resist is coated, preferably at 60–180°C for 10–300 seconds. Then, exposure is performed according to standard methods, followed by post-exposure baking (PEB) and development to obtain the resist pattern. Furthermore, the thickness of the top layer of the resist film is not particularly limited, but is preferably 10–500 nm, and particularly preferably 20–400 nm.

[0287] When a photoresist composition is formed by vapor deposition using CVD or ALD, the photoresist composition is an EUV-sensitive metal oxide film. The metal is selected from Sn, Zr, Hf, Ti, Bi, Sb, etc., with Sn being preferred due to its excellent EUV photosensitivity. The metal oxide film can be a photosensitive organometallic oxide film containing organotin oxides (e.g., haloalkyl Sn, alkoxyalkyl Sn, or amide alkyl Sn). Several specific examples of suitable precursors include trimethyltin chloride, dimethyltin dichloride, methyltin trichloride, tris(dimethylamino)methyltin (IV), and (dimethylamino)trimethyltin (IV).

[0288] The metal oxide film can be deposited, for example, using a Lam Vector (registered trademark) tool via PECVD or PEALD. In the ALD embodiment, 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 flow rate of the precursor solution containing the metal oxide film (e.g., organotin oxide precursor) can be 0.01 to 10 cmm, and the gas flow rate (CO2, CO, Ar, N2) can be 100 to 10000 sccm. High-frequency plasma (e.g., 13.56 MHz, 27.1 MHz, or higher) is used, and the power is 200 to 1000 W per 300 mm wafer station. The deposition thickness is preferably 100 to 2000 angstroms.

[0289] <Water-repellent coating>

[0290] Furthermore, when forming the upper resist film pattern, if a protective film for the upper resist film is required for immersion exposure, a water-repellent coating film can be formed on top of the upper resist film. There are no particular limitations on the water-repellent coating film; various water-repellent coating films can be used.

[0291] [Steps (i-4) and (ii-4)]

[0292] Steps (i-4) and (ii-4) are steps of developing the upper resist film with a developer after the pattern is exposed to the pattern.

[0293] As exposure light, high-energy rays with wavelengths below 300nm can be listed, specifically soft X-rays, electron beams, and X-rays with wavelengths of 248nm, 193nm, and 3-20nm can be listed.

[0294] The preferred method for patterning the upper layer of the resist film is optical lithography with a wavelength of 5 nm to 300 nm, direct electron beam lithography, nanoimprinting, or a combination thereof.

[0295] In addition, the development method in the above pattern forming method should preferably be alkaline development or development using organic solvents.

[0296] [Steps (i-5) and (ii-5)]

[0297] Steps (i-5) and (ii-5) are steps of forming the lower resist film pattern by using the upper resist film pattern as a mask through multiple etching processes.

[0298] Steps (i-5) and (ii-5) involve using the upper resist film with the upper resist film pattern as a mask, and transferring the upper resist film pattern to a silicon-containing intermediate film or an inorganic hard mask intermediate film by dry etching. Further, the silicon-containing resist intermediate film or inorganic hard mask intermediate film with the transferred upper resist film pattern is used as a mask, and the upper resist film pattern is transferred to a lower resist film by dry etching to form a lower resist film pattern.

[0299] In steps (i-5) and (ii-5), if the upper resist film pattern is used as an etching mask, and dry etching conditions with significantly higher etching rates for the silicon-containing resist intermediate film and the inorganic hard mask intermediate film compared to the upper resist film pattern are used, such as dry etching with fluorine-based gas plasma, the silicon-containing resist intermediate film or the inorganic hard mask intermediate film will be almost unaffected by the pattern changes caused by the side etching of the resist film, and the upper resist film pattern can be transferred to the silicon-containing resist intermediate film or the inorganic hard mask intermediate film.

[0300] Then, the lower resist film is etched under dry etching conditions that have a significantly higher etching rate than the silicon-containing resist intermediate film or inorganic hard mask intermediate film with the resist upper film pattern transferred, such as reactive dry etching with oxygen-containing gas plasma or reactive dry etching with hydrogen-nitrogen-containing gas plasma.

[0301] The etching step yields the lower resist film pattern. The uppermost resist layer is typically lost, but it may remain on top of the lower resist film pattern as part of the silicon-containing resist intermediate film or inorganic hard mask intermediate film that forms the etching mask.

[0302] In addition, in steps (i-5) and (ii-5), the pattern of the lower resist film can also be a silicon-containing resist intermediate film or an inorganic hard mask intermediate film remaining on the lower resist film.

[0303] Alternatively, in steps (i-5) and (ii-5), the pattern of the lower resist film can also be a silicon-containing resist intermediate film or an inorganic hard mask intermediate film that does not remain on the lower resist film.

[0304] The pattern forming method of the present invention can form an inorganic silicon film pattern (sidewall pattern) without damaging the sidewalls or the substrate, regardless of whether there are residues of the mask material after pattern transfer by dry etching or no residues.

[0305] Furthermore, in the pattern transfer of multilayer resists by dry etching in the manufacturing process of practical semiconductor devices, in order to ensure the rectangularity of the pattern shape after dry etching, it is often set that a portion of the pattern material of the mask remains on the upper part of the transferred pattern. That is, even in the pattern formation method of the present invention, when using the upper resist film as a mask to perform pattern transfer on a silicon-containing resist intermediate film by dry etching, in order to ensure the rectangularity of the cross-sectional shape of the pattern of the silicon-containing resist intermediate film, the step can be performed with a portion of the upper resist film remaining. Then, when using the silicon-containing resist intermediate film as a mask to perform pattern transfer on a resist lower film, similarly, in order to ensure the rectangularity of the cross-sectional shape of the pattern of the resist lower film, the pattern transfer step can be performed with a portion of the silicon-containing resist intermediate film or inorganic hard mask intermediate film remaining on the upper part of the resist lower film. However, in the sidewall backing method using the resist underlayer pattern as the core material, the sidewalls are formed with an inorganic silicon film, and then the resist underlayer pattern is removed to form the inorganic silicon film pattern. However, if the residual silicon-containing resist intermediate film or inorganic hard mask intermediate film remaining on the resist underlayer pattern is to be removed by dry etching, the sidewalls or substrate formed with the inorganic silicon film will be damaged by the dry etching, resulting in performance degradation or reduced yield. Therefore, in the pattern forming method of the present invention, as described later, it is preferable to remove the silicon-containing resist intermediate film by wet processing with a stripping solution, thus avoiding such problems.

[0306] When removing the silicon-containing photoresist interlayer using a stripping solution, there are no particular limitations on the type of stripping solution, such as alkaline or acidic solutions.

[0307] As an acid removal solution, there are no particular limitations as long as it contains acid. It is preferable to contain any one or both of hydrogen fluoride, hydrogen peroxide, and sulfuric acid. More specifically, it is particularly preferable to be an aqueous solution containing hydrochloric acid and hydrogen peroxide (SC solution), an aqueous solution containing sulfuric acid and hydrogen peroxide (SPM solution), or an aqueous solution containing hydrofluoric acid and hydrogen peroxide (FPM solution).

[0308] As a alkali-containing removal liquid, there are no particular restrictions as long as it is an alkaline solution containing an alkali. Examples of alkalis include sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyl diethylamine, dimethylethanolamine, triethanolamine, tetramethylammonium hydroxide (hereinafter also referred to as "TMAH"), tetraethylammonium hydroxide, pyrrole, piperidine, choline, 1,8-diazabicyclo[5.4.0]-7-undecene, 1,5-diazabicyclo[4.3.0]-5-nonene, etc. Among these, considering the need to avoid damage to the substrate, tetramethylammonium hydroxide (hereinafter also referred to as "TMAH") or ammonia is preferable.

[0309] As a removal liquid containing alkali, it is preferable to be a liquid containing alkali and water, or a liquid containing alkali, hydrogen peroxide and water. More specifically, it is particularly preferable to be a mixed aqueous solution of ammonia and hydrogen peroxide (25% ammonia solution / 30% hydrogen peroxide solution / water = 1 / 2 / 40 mixed aqueous solution, 25% ammonia solution / 30% hydrogen peroxide solution / water = 1 / 1 / 5 mixed aqueous solution, etc. (SC1)).

[0310] Furthermore, to promote peeling, it is advisable to add an acid or base to adjust the pH. Examples of such pH adjusters include inorganic acids such as hydrochloric acid or sulfuric acid, organic acids such as acetic acid, oxalic acid, tartaric acid, citric acid, and lactic acid, nitrogen-containing bases such as ammonia, ethanolamine, and tetramethylammonium hydroxide, and nitrogen-containing organic acid compounds such as EDTA (ethylenediaminetetraacetic acid).

[0311] The stripping solution described above is typically an aqueous solution, but may also contain an organic solvent depending on the circumstances. Examples of such organic solvents include water-soluble alcohols, ethers, ketones, esters, amides, and imides. Specifically, 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, diethylene glycol methyl ether, diethylene glycol dimethyl ether, diethylene glycol ethyl ether, diethylene glycol diethyl ether, propylene glycol methyl ether, propylene glycol ethyl ether, dipropylene glycol methyl ether, dipropylene glycol dimethyl ether, dipropylene glycol ethyl ether, dipropylene glycol diethyl ether, dipropylene glycol diethyl ether, dipropylene glycol diethyl ether, tetrahydrofuran, tetrahydrofurfuryl alcohol, acetone, methyl ethyl ketone, ethyl lactate, N-methylpyrrolidone, N,N-dimethylformamide, and N,N-dimethylacetamide.

[0312] As for wet stripping methods, there are no particular limitations as long as the silicon wafer on which the substrate to be processed is formed is in contact with the stripping solution for a certain period of time under heating conditions. Examples include immersing the silicon wafer on which the substrate to be processed is formed in heated alkaline hydrogen peroxide water, spraying alkaline hydrogen peroxide water under heating conditions, and coating with heated alkaline hydrogen peroxide water. After each of these methods, the substrate can also be washed with water and dried.

[0313] The lower limit of the temperature for wet stripping is preferably 23°C, preferably 40°C, and more preferably 50°C. The upper limit of the above temperature is preferably 100°C, and more preferably 90°C.

[0314] The lower limit of the immersion time in the immersion method is preferably 1 second, more preferably 10 seconds, further preferably 20 seconds, and especially preferably 30 seconds. The upper limit of the above-mentioned immersion time, considering the viewpoint of suppressing the impact on the substrate, is preferably 60 minutes, more preferably 30 minutes, further preferably 20 minutes, and especially preferably 10 minutes.

[0315] The removal of the silicon-containing photoresist intermediate film remaining on the photoresist underlayer pattern using stripping solution can be performed before or after plasma irradiation.

[0316] In cases where the intermediate film containing silicon resist is removed before plasma irradiation, the edge roughness of the resist underlayer pattern, which has deteriorated due to wet stripping, can be improved by plasma irradiation.

[0317] In cases where plasma irradiation is used to remove the silicon-containing photoresist interlayer, the improved resistance to the stripping solution for the underlying photoresist pattern helps to suppress the deterioration of the edge roughness of the underlying photoresist pattern caused by wet stripping. Because plasma irradiation improves the resistance of the underlying photoresist pattern to the stripping solution, wet stripping of the silicon-containing photoresist interlayer is more suitable to be performed after plasma irradiation of the underlying photoresist pattern.

[0318] [Steps (i-6) and (ii-6)]

[0319] Steps (i-6) and (ii-6) are steps of plasma irradiating the resist underlayer film pattern.

[0320] In steps (i-6) and (ii-6) above, plasma irradiation can be performed using known methods. For example, the method described in Japanese Patent No. 5746670, "Improvement of the wiggling profile of spin-on carbon hardmask by H2 plasma treatment" (J.Vac.Sci.Technol.B26(1), Jan / Feb 2008, pp.67-71).

[0321] In steps (i-6) and (ii-6) above, the plasma used for plasma irradiation needs to be less etched than the etching gas used in the step of forming the resist underlayer pattern by etching the resist underlayer in steps (i-5) and (ii-5) above, so that the resist underlayer is etched to a lesser extent.

[0322] The RF discharge power should be 100–10,000W, and more suitable is 500–5,000W.

[0323] Examples of suitable gaseous environments include rare gases such as N2, NF3, H2, and He, as well as fluorocarbons. More suitable examples include He, Ar, N2, Ne, NF3, H2, CF4, CHF3, CH2F2, CH3F, C4F6, and C4F8. Two or more of these gases can also be mixed. The fact that the effects of this invention can be expected even when using a gaseous environment that does not contain O2 is an advantage of this invention.

[0324] The plasma irradiation time can be selected from, for example, 10 to 240 seconds. The pressure can be selected appropriately.

[0325] In steps (i-6) and (ii-6) above, it is preferable to irradiate the plasma in an environment where rare gases such as N2, NF3, H2, fluorocarbons, He, or any mixture thereof are present.

[0326] From a production perspective, He, Ar, N2, and H2 are among the most suitable gaseous environments, with gases containing H2 or helium being preferable.

[0327] Following plasma irradiation, the underlying resist film can also be heat-treated. When heating after plasma irradiation, the heating temperature can be appropriately selected from the range of 80–800°C (preferably 100–700°C, more preferably 200–600°C), and the heating time can be appropriately selected from the range of 30–180 seconds (preferably 30–120 seconds). While not bound by theoretical constraints, it is believed that high-temperature heating after plasma irradiation, which induces dangling bond formation, can contribute to the high density of the hardened film (underlying resist film).

[0328] As the environment for heating after plasma irradiation, either an oxygen-containing environment (oxygen concentration of 1% to 21%) or an oxygen-free environment (oxygen concentration of 1%) can be selected, depending on the requirements. For example, when the substrate being processed is easily oxidized by air, heat treatment in an environment with an oxygen concentration of less than 1% can form a hardened film, thus suppressing substrate damage.

[0329] As for the irradiation device, there are no particular limitations as long as it is a device capable of performing plasma irradiation; for example, the Telius SP and Tactras Vigus manufactured by Tokyo Power Technology Co., Ltd. can be used. The device and setting conditions can be selected in a way that more obviously exerts the effects of the present invention.

[0330] There are no particular limitations on the design of the resist underlayer pattern. Examples include line patterns and contact hole patterns. Considering the uniformity of surface modification caused by plasma irradiation, line patterns are more suitable. Therefore, the resist underlayer pattern formation method of the present invention is suitable for use in sidewall lining methods.

[0331] To facilitate the modification of the resist underlayer pattern by plasma irradiation, the thickness of the silicon-containing resist interlayer or inorganic hard mask interlayer remaining on the resist underlayer pattern should preferably be thin. The preferred thickness of the silicon-containing resist interlayer or inorganic hard mask interlayer remaining on the resist underlayer pattern is preferably less than 15 nm, more preferably less than 10 nm, and even more preferably less than 5 nm; it may also not exist on the resist underlayer pattern.

[0332] After the plasma irradiation step described above, it is advisable to include the step of using the plasma-irradiated resist lower film pattern as an etching mask to directly or indirectly form a pattern on the substrate.

[0333] On the other hand, the present invention can also be a pattern forming method, which is a method of forming a pattern on the resist upper film pattern on the substrate being processed at a 1 / 2 pitch. Figure 3 ),

[0334] After the step of plasma irradiating the underlying resist film pattern, the following steps are performed:

[0335] An inorganic silicon film composed of any of the following materials—polycrystalline silicon, amorphous silicon, silicon oxide, silicon nitride, silicon nitride oxide, silicon carbide, and composite materials thereof—is formed by CVD or ALD methods, covering the underlying resist film pattern.

[0336] The lower resist film pattern is removed by dry etching to form an inorganic silicon film pattern with a pattern pitch of 1 / 2 the pitch of the upper resist film pattern, and

[0337] Using the aforementioned inorganic silicon film pattern as a mask, a pattern with a pitch of 1 / 2 of the aforementioned resist upper film pattern is formed on the substrate being processed.

[0338] If such a pattern formation method is used, the sidewall liner method can form inorganic silicon film patterns (sidewall patterns) with small edge roughness, which is extremely useful in microfabrication processes.

[0339] There are no particular limitations on the removal of the resist film pattern. However, considering the need to suppress the degradation of the inorganic silicon film pattern (sidewall pattern), dry etching is preferable for removal.

[0340] When dry etching is chosen as the removal method, the underlayer resist is removed under dry etching conditions that significantly increase the etching rate relative to the sidewall pattern, such as reactive dry etching with oxygen-containing gas plasma or reactive dry etching with hydrogen-nitrogen-containing gas plasma.

[0341] Furthermore, the present invention can be a pattern forming method, which is a method of forming a pattern on a substrate at a 1 / 2 pitch of the pattern on the upper layer of the resist film. Figure 4 ),

[0342] After the step of plasma irradiating the underlying resist film pattern, the following steps are performed:

[0343] An inorganic silicon film composed of any of the following materials—polycrystalline silicon, amorphous silicon, silicon oxide, silicon nitride, silicon nitride oxide, silicon carbide, and composite materials thereof—is formed by CVD or ALD methods, covering the underlying resist film pattern.

[0344] After coating the resist lower film formation composition of the present invention, which is modified by plasma irradiation, onto an inorganic silicon film pattern used for pattern separation, heat treatment is performed.

[0345] After the inorganic silicon film pattern is exposed by etching back, it is subjected to plasma irradiation.

[0346] The inorganic silicon film pattern is removed by dry etching to form a lower resist film pattern with a pattern pitch of 1 / 2 the pitch of the upper resist film pattern, and...

[0347] Using the aforementioned lower resist film pattern as a mask, a pattern with a pitch of 1 / 2 of the aforementioned upper resist film pattern is formed on the substrate being processed.

[0348] Furthermore, the present invention can also be a pattern forming method, which is a method of forming a pattern on a substrate at a 1 / 2 pitch of the pattern on the upper layer of the resist film. Figure 5 ),

[0349] Before subjecting the above-mentioned resist underlayer film pattern to plasma irradiation, the following steps are performed:

[0350] An inorganic silicon film composed of any one of polycrystalline silicon, amorphous silicon, silicon oxide, silicon nitride, silicon nitride oxide, silicon carbide, or composite materials thereof is formed by CVD or ALD methods, covering the underlying resist film pattern.

[0351] After coating the resist lower film formation composition of the present invention, which is modified by plasma irradiation, onto an inorganic silicon film pattern used for pattern separation, heat treatment is performed.

[0352] After the inorganic silicon film pattern is exposed by etching back, it is subjected to plasma irradiation.

[0353] The inorganic silicon film pattern is removed by dry etching to form a lower resist film pattern with a pattern pitch of 1 / 2 the pitch of the upper resist film pattern, and...

[0354] Using the aforementioned lower resist film pattern as a mask, a pattern with a pitch of 1 / 2 of the aforementioned upper resist film pattern is formed on the substrate being processed.

[0355] There are no particular limitations on the method for removing the resist underlayer pattern and inorganic silicon film pattern remaining on the substrate being processed. For example, it can be removed by CMP method.

[0356] Example

[0357] The present invention will be specifically described below using examples and comparative examples, but the present invention is not limited to these.

[0358] The present invention will be described in more detail below with examples of synthesis, comparative synthesis, examples, and comparative examples, but the invention is not limited thereto. Furthermore, the weight-average molecular weight (Mw) and number-average molecular weight (Mn) of polystyrene converted by gel permeation chromatography (GPC) with tetrahydrofuran as the dissolution solution were obtained, and the dispersibility (Mw / Mn) was then determined.

[0359] In the synthesis of compounds (A1) to (A14) and the comparative example compound (R1), the following compounds were used: (G1) to (G13).

[0360] [Chemistry 40]

[0361]

[0362] [Synthesis Example 1] Synthesis of compound (A1)

[0363] [Chemistry 41]

[0364]

[0365] Under nitrogen atmosphere, 180 g of compound (G1), 75 g of 37% formalin solution, and 5 g of oxalic acid were added, and the mixture was stirred at 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. The organic layer was then dried under reduced pressure. 320 g of THF was added to the residue, and 1350 g of hexane was used to reprecipitate the polymer. The precipitated polymer was separated by filtration and dried under reduced pressure to obtain compound (A1).

[0366] The weight-average molecular weight (Mw) and dispersion (Mw / Mn) were obtained by GPC, and the results are as follows.

[0367] (A1): Mw=11,200, Mw / Mn=4.35

[0368] [Synthesis Example 2] Synthesis of compound (A2)

[0369] [Chemistry 42]

[0370]

[0371] Under nitrogen atmosphere, 160.2 g of compound (G2), 64.9 g of 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 pre-mixed and homogenized 20% p-toluenesulfonic acid solution in 2-methoxy-1-propanol 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, and 1000 ml of methyl isobutyl ketone was added. The mixture was washed six times with 200 ml of pure water, and the organic layer was dried under reduced pressure. The residue was treated with 300 g of THF to form a homogeneous 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 recovered. The recovered crystals were dried under vacuum at 70°C to obtain compound (A2).

[0372] When the weight-average molecular weight (Mw) and dispersion (Mw / Mn) are obtained by GPC, the results are as follows.

[0373] (A2): Mw=4,000, Mw / Mn=3.02

[0374] [Synthesis Example 3] Synthesis of compound (A3)

[0375] [Chemistry 43]

[0376]

[0377] Under nitrogen atmosphere, 100.0 g of compound (G1), 48.3 g of compound (G3), and 450 g of 1,2-dichloroethane were 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. The organic layer was washed five times with 200 g of pure water and then dried under reduced pressure. For the residue, 450 g of THF was added, 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).

[0378] When the weight-average molecular weight (Mw) and dispersion (Mw / Mn) are obtained by GPC, the results are as follows.

[0379] (A3): Mw=9,800, Mw / Mn=3.50

[0380] [Synthesis Example 4] Synthesis of compound (A4)

[0381] [Chemistry 44]

[0382]

[0383] Under 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 the mixture was stirred at 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. The organic layer was then dried under reduced pressure. 480 g of THF was added to the residue, and 2400 g of hexane was used to reprecipitate the polymer. The precipitated polymer was separated by filtration and dried under reduced pressure to obtain compound (A4).

[0384] When the weight-average molecular weight (Mw) and dispersion (Mw / Mn) are obtained by GPC, the results are as follows.

[0385] (A4): Mw=9,350, Mw / Mn=3.76

[0386] [Synthesis Example 5] Synthesis of compound (A5)

[0387] [Chemistry 45]

[0388]

[0389] Under 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 a uniform dispersion was prepared at 50°C. Then, 23.4 g of bromopropylene was slowly added dropwise, and the mixture was stirred at 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 then washed six times with 100 g of 3% nitric acid aqueous solution and 100 g of pure water, and finally dried under reduced pressure to obtain compound (A5).

[0390] When the weight-average molecular weight (Mw) and dispersion (Mw / Mn) are obtained by GPC, the results are as follows.

[0391] (A5): Mw=12,200, Mw / Mn=4.38

[0392] [Synthesis Example 6] Synthesis of compound (A6)

[0393] [Chemistry 46]

[0394]

[0395] Under 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 a uniform dispersion was prepared at 50°C. Then, 29.5 g of 3-bromo-1-propyne was slowly added dropwise, and the mixture was stirred at 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 then washed six times with 100 g of 3% nitric acid aqueous solution and 100 g of pure water, and then dried under reduced pressure to obtain compound (A6).

[0396] When the weight-average molecular weight (Mw) and dispersion (Mw / Mn) are obtained by GPC, the results are as follows.

[0397] (A6): Mw=12,800, Mw / Mn=4.43

[0398] [Synthesis Example 7] Synthesis of Compound (A7)

[0399] [Chemistry 47]

[0400]

[0401] Under 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. A homogeneous solution was prepared at an internal temperature of 80°C. Then, 18 g of a 20% p-toluenesulfonic acid solution in 2-methoxy-1-propanol was slowly added, and the mixture was stirred at an internal temperature of 110°C for 8 hours. After cooling to room temperature, 600 g of methyl isobutyl ketone was added. The organic layer was washed five times with 200 g of pure water and then dried under reduced pressure. For the residue, 320 g of THF was added, and the polymer was redetermined with 1350 g of methanol. The precipitated polymer was filtered and dried under reduced pressure to obtain compound (A7).

[0402] When the weight-average molecular weight (Mw) and dispersion (Mw / Mn) are obtained by GPC, the results are as follows.

[0403] (A7): Mw=3,520, Mw / Mn=2.60

[0404] [Synthesis Example 8] Synthesis of compound (A8)

[0405] [Chemistry 48]

[0406]

[0407] Under nitrogen atmosphere, 42.8 g of compound (G5), 15.7 g of potassium carbonate, and 150 g of DMF were added to prepare a homogeneous dispersion at an internal temperature of 50°C. 28.2 g of propargyl bromide was slowly added, and the reaction was carried out at 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 removed. The organic layer was then washed six times with 100 g of 3% nitric acid aqueous solution and 100 g of pure water, and finally dried under reduced pressure to obtain compound (A8).

[0408] When the weight-average molecular weight (Mw) and dispersion (Mw / Mn) are obtained by GPC, the following results are obtained.

[0409] (A8): Mw=560, Mw / Mn=1.01

[0410] [Synthesis Example 9] Synthesis of compound (A9)

[0411] [Chemistry 49]

[0412]

[0413] Under nitrogen atmosphere, 46.9 g of compound (G6), 10.1 g of potassium carbonate, and 150 g of DMF were added to prepare a homogeneous dispersion at an internal temperature of 50°C. 9.0 g of propargyl bromide was slowly added, and the reaction was carried out at 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 removed. The organic layer was then washed six times with 100 g of 3% nitric acid aqueous solution and 100 g of pure water, and finally dried under reduced pressure to obtain compound (A9).

[0414] When the weight-average molecular weight (Mw) and dispersion (Mw / Mn) are obtained by GPC, the results are as follows.

[0415] (A9): Mw=903, Mw / Mn=1.08

[0416] [Synthetic Example 10] Synthesis of compound (A10)

[0417] [Transformation 50]

[0418]

[0419] Under nitrogen atmosphere, 3.8 g of methanesulfonic acid and 30 g of dichloromethane were mixed and homogenized at an internal temperature of 30°C. Then, a mixture of 30.0 g of compound (G4) and 60.0 g of dichloromethane was added dropwise over 1 hour, and the mixture was heated and stirred 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 then dried under reduced pressure. The residue was treated with 90 g of THF to form a homogeneous solution, which was then crystallized in 600 g of methanol. The precipitated crystals were separated by filtration and recovered by washing twice with 300 g of methanol. The recovered crystals were then vacuum dried at 70°C to obtain 28.7 g of compound (A10).

[0420] The weight-average molecular weight (Mw) and dispersion (Mw / Mn) were obtained by GPC, and the results are as follows.

[0421] (A10): Mw=2400, Mw / Mn=1.93

[0422] [Synthetic Example 11] Synthesis of compound (A11)

[0423] [Chemistry 51]

[0424]

[0425] Under nitrogen atmosphere, 60.0 g of compound (G7) and 300 g of 1,2-dichloroethane were mixed and uniformly dispersed 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 components were removed by filtration. The recovered filtrate was washed six times with 200 g of pure water, and the organic layer was dried under reduced pressure. The residue was treated with 150 g of THF to form a homogeneous solution, which was then crystallized in 500 g of methanol. The precipitated crystals were separated by filtration and washed and recovered in the order of 300 g of methanol and 300 g of diisopropyl ether. The recovered crystals were dried under vacuum at 70°C to obtain 33.2 g of compound (A11).

[0426] When the weight-average molecular weight (Mw) and dispersion (Mw / Mn) are obtained by GPC, the results are as follows.

[0427] (A11): Mw=560, Mw / Mn=2.43

[0428] [Synthetic Example 12] Synthesis of compound (A12)

[0429] [Chemistry 52]

[0430]

[0431] 41.2 g of a mixed tertiary alcohol (G8) and 160 g of dichloromethane were added dropwise. 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, followed by washing with water and concentration under reduced pressure to obtain 37.6 g of compound (A12).

[0432] When the weight-average molecular weight (Mw) and dispersion (Mw / Mn) are obtained by GPC, the results are as follows.

[0433] (A12): Mw=1850, Mw / Mn=1.26

[0434] [Synthetic Example 13] Synthesis of compound (A13)

[0435] [Chemistry 53]

[0436]

[0437] Under nitrogen atmosphere, 60.0 g of compound (G10), 6.3 g of compound (G9), and 350 g of 1,2-dichloroethane were mixed and prepared into a homogeneous solution at an internal temperature of 60°C. Then, 80.2 g of methanesulfonic acid was added dropwise over 1 hour, and the mixture was heated and stirred 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 pure water. The organic layer was then dried under reduced pressure. For the residue, 200 g of THF was added to prepare a homogeneous solution, which was then crystallized in 600 g of methanol. The precipitated crystals were separated by filtration and recovered by washing with 300 g of methanol and 300 g of diisopropyl ether in that order. The recovered crystals were then dried under vacuum at 70°C to obtain 35.5 g of compound (A13).

[0438] When the weight-average molecular weight (Mw) and dispersion (Mw / Mn) are obtained by GPC, the results are as follows.

[0439] (A13): Mw=730, Mw / Mn=1.38

[0440] [Synthetic Example 14] Synthesis of compound (A14)

[0441] [Chemistry 54]

[0442]

[0443] Under nitrogen atmosphere, 80.0 g of epoxide (G11), 51.0 g of compound (G12), and 600 g of 2-methoxy-1-propanol were added and mixed at 100 °C to form a homogeneous solution. Then, 5.7 g of benzyltriethylammonium chloride was added and the mixture was 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 then dried under reduced pressure to obtain compound (A14).

[0444] The weight-average molecular weight (Mw) and dispersion (Mw / Mn) were obtained by GPC, and the results are as follows.

[0445] (A14): Mw=900, Mw / Mn=1.04

[0446] [Synthetic Example 15] Synthesis of Compound (R1) in Comparative Example

[0447] [Chemistry 55]

[0448]

[0449] In a 500ml flask, 100g of monomer 1 (raw material G13) and 290.0g of propylene glycol monomethyl ether acetate (hereinafter referred to as "PGMEA") were weighed and degassed while stirring to prepare a monomer solution. In another 500ml flask, 2.9g of dimethyl 2,2'-azobis(2-methylpropionate) (Wako Pure Chemical Industries, Ltd., V-601) and 50.0g of PGMEA were weighed and degassed while stirring to prepare an initiator solution. In a 1L flask under nitrogen atmosphere, 60g of PGMEA was weighed and degassed while stirring, and then heated until the internal temperature reached 80°C. The monomer solution and initiator solution were added simultaneously over 4 hours each. After addition, the mixture was heated and stirred for 16 hours and then cooled to room temperature. The obtained polymerization solution was added dropwise to 1,500g of stirred hexane, and the precipitated polymer was separated by filtration. In addition, the obtained polymer was washed twice with 600g of hexane and then dried under vacuum at 50°C for 20 hours to obtain a white powder polymer (R1).

[0450] When the weight-average molecular weight (Mw) and dispersion (Mw / Mn) are obtained by GPC, the results are as follows.

[0451] (R1): Mw=10,000, Mw / Mn=2.00

[0452] [Content UDL-1 for forming the lower layer of the resist film]

[0453] The composition for forming the underlayer of the resist (UDL-1) was prepared by dissolving the resist underlayer film (A1) in propylene glycol monomethyl ether acetate (PGMEA) containing 0.5% by mass of surfactant FC-4430 (manufactured by Sumitomo 3M Co., Ltd.) at the proportions shown in Table 2 and filtering it through a 0.02 μm membrane filter.

[0454] [Preparation of resist underlayer film forming compositions (UDL-2 to 17) and comparative examples of resist underlayer film forming compositions (comparative examples of UDL-1)]

[0455] The types and amounts of each component are shown in Table 2. Otherwise, each solution was prepared using the same procedures as in UDL-1. In Table 2, "-" indicates that the component was not used. The acid generator (TAG) was prepared using formula (E1), and the flow enhancer using formula (B1). The results from UDL-1 are also presented.

[0456] [Acid generating agent]

[0457] The hot acid generator (E1) used in the composition for forming the lower layer film of the resist is shown below.

[0458] [Chemistry 56]

[0459]

[0460] [Liquidity enhancer]

[0461] The flow promoter (B1) to be used in the composition for forming the underlayer film of the resist is shown in Table 1.

[0462] [Table 1]

[0463]

[0464] [Cross-linking agent]

[0465] The following are the crosslinking agents (C) used in the resist underlayer film material.

[0466] [Chemistry 57]

[0467]

[0468] [Table 2]

[0469]

[0470] [Evaluation of Pattern Formation in the Underlayer of the Resist Film]

[0471] The above-mentioned components for forming the lower resist film (UDL-1 to 17 and UDL-1 for comparative examples) were each coated on a silicon wafer substrate on which a SiO2 film was formed, and calcined at the temperatures shown in Tables 6 and 7 for 60 seconds to form a lower resist film with a thickness of 60 nm.

[0472] A silicon-containing photoresist interlayer material (SOG-1) is coated onto the photoresist and baked at 220°C for 60 seconds to form a photoresist interlayer film with a thickness of 20 nm. An ArF monolayer photoresist top layer material is then coated onto the photoresist and baked at 105°C for 60 seconds to form a photoresist film with a thickness of 100 nm. A wettable protective film material (TC-1) is then coated onto the photoresist film and baked at 90°C for 60 seconds to form a protective film with a thickness of 50 nm.

[0473] As a silicon-containing photoresist interlayer material (SOG-1), a polymer represented by ArF silicon-containing interlayer polymer (SiP1) and a crosslinking catalyst (CAT1) were dissolved in an organic solvent containing 0.1% by mass of FC-4430 (manufactured by Sumitomo 3M) in the proportions shown in Table 3. The solution was filtered through a fluoropolymer filter with a pore size of 0.1 μm to prepare the silicon-containing photoresist interlayer material (SOG-1).

[0474] [Table 3]

[0475]

[0476] The structural formulas of the ArF silicon-containing intermediate membrane polymer (SiP1) and crosslinking catalyst (CAT1) used are shown below.

[0477] [Chem.58]

[0478]

[0479] As a top-layer resist material (a single-layer resist for ArF), the polymer (RP1), acid generator (PAG1), and basic compound (Amine1) are dissolved in a solvent containing 0.1% by mass of surfactant FC-4430 (manufactured by Sumitomo 3M Co., Ltd.) in the proportions shown in Table 4, and then filtered through a 0.1 μm fluororesin filter to prepare the material.

[0480] [Table 4]

[0481]

[0482] The polymer (RP1), acid generator (PAG1), and basic compound (Amine1) used in the upper layer film material of the resist (ArF single-layer resist) are as follows.

[0483] [Chemistry 59]

[0484]

[0485] As the impregnation protective film material (TC-1), the protective film polymer (PP1) is dissolved in an organic solvent at the proportions shown in Table 5, and then filtered through a 0.1 μm fluororesin filter to prepare the film.

[0486] [Table 5]

[0487]

[0488] The polymer (PP1) used in the impregnation protective film material (TC-1) is shown below.

[0489] [Transformation 60]

[0490]

[0491] Then, exposure was performed using an ArF immersion exposure apparatus (Nikon Corporation; NSR-S610C, NA 1.30, σ 0.98 / 0.78, 35-degree dipole s-polarized illumination, 6% half-step phase shift mask), followed by baking at 100°C for 60 seconds (PEB), and development with a 2.38% by mass tetramethylammonium hydroxide (TMAH) aqueous solution for 30 seconds to obtain a 45nm 1:1 positive line and spacing pattern (resist pattern).

[0492] Then, using the Telius etching apparatus manufactured by Tokyo-based Veritech, a hard mask pattern was formed by dry etching using the resist pattern as a mask to etch the silicon-containing resist intermediate layer material (SOG-1). The obtained SOG-1 pattern was then used as a mask to etch the resist underlayer film to form the resist underlayer film pattern. The line dimensions of the obtained resist underlayer film pattern were measured using a critical dimension scanning electron microscope (CG5000) manufactured by Hitachi High-Technologies Corporation.

[0493] Transfer conditions for resist patterns on silicon-containing resist interlayer material (SOG-1).

[0494] Chamber pressure: 50mT

[0495] RF power (top): 500W

[0496] RF power (bottom): 300W

[0497] CF4 gas flow rate: 150 sccm

[0498] CHF3 gas flow rate: 50 sccm

[0499] Time: 15 seconds

[0500] Transfer conditions for the resist underlayer film of the pattern of silicon atom resist intermediate layer material (SOG-1).

[0501] Chamber pressure: 10mT

[0502] RF power (top): 1,000W

[0503] RF power (bottom): 300W

[0504] CO2 gas flow rate: 320 sccm

[0505] N2 gas flow rate: 80 sccm

[0506] Time: 55 seconds

[0507] Subsequently, each substrate with the formed resist underlayer pattern was subjected to plasma treatment using the Telius etching apparatus manufactured by Tokyo Powertech under the following conditions. The line dimensions of the obtained resist underlayer pattern were measured using a critical dimension scanning electron microscope (CG5000) manufactured by Hitachi High-Technologies Corporation. The pattern cross-section was observed using an electron microscope (S-4700) manufactured by Hitachi, Ltd.

[0508] Chamber pressure: 100mT

[0509] RF power (top): 100W

[0510] RF power (bottom): 3500W

[0511] H2 gas flow rate: 200 sccm

[0512] Time: 20 seconds

[0513] The resist underlayer pattern obtained from the above evaluation was used as a mask to etch the SiO2 film. The etching conditions are shown below. The line dimensions of the obtained pattern were measured using a critical dimension scanning electron microscope (CG5000) manufactured by Hitachi High-Technologies Corporation. The pattern cross-section was observed using an electron microscope (S-4700) manufactured by Hitachi, Ltd.

[0514] Chamber pressure: 100mT

[0515] RF power (top): 500W

[0516] RF power (bottom): 300W

[0517] CF4 gas flow rate: 150 sccm

[0518] CHF3 gas flow rate: 30 sccm

[0519] O2 gas flow rate: 10 sccm

[0520] Time: 130 seconds

[0521] (Comparative Examples 1-2)

[0522] The following evaluations were conducted for Comparative Examples 1-2.

[0523] The aforementioned composition for forming the lower resist film (UDL-1) was coated onto a silicon wafer substrate on which a SiO2 film was formed, and calcined at 350°C for 60 seconds to form a lower resist film with a thickness of 60 nm. A silicon-containing intermediate resist material (SOG-1) was coated onto this film and baked at 220°C for 60 seconds to form a 20 nm thick intermediate resist film. An ArF monolayer resist of the upper resist film material was then coated onto this film and baked at 105°C for 60 seconds to form a 100 nm thick photoresist film. Finally, a wetting protective film material (TC-1) was coated onto the photoresist film and baked at 90°C for 60 seconds to form a 50 nm thick protective film.

[0524] Then, exposure was performed using an ArF immersion exposure apparatus (Nikon Corporation; NSR-S610C, NA 1.30, σ 0.98 / 0.78, 35-degree dipole s-polarized illumination, 6% half-step phase shift mask), followed by baking at 100°C for 60 seconds (PEB), and development with a 2.38% by mass tetramethylammonium hydroxide (TMAH) aqueous solution for 30 seconds to obtain a 45nm 1:1 positive line and spacing pattern (resist pattern).

[0525] The substrate with the resist pattern was then subjected to plasma treatment using the Telius etching apparatus manufactured by Tokyo Powertech under the following conditions. The line dimensions of the resulting resist pattern were measured using a critical dimension scanning electron microscope (CG5000) manufactured by Hitachi High-Technologies Corporation. The pattern cross-section was observed using an electron microscope (S-4700) manufactured by Hitachi, Ltd.

[0526] Chamber pressure: 100mT

[0527] RF power (top): 100W

[0528] RF power (bottom): 3500W

[0529] H2 gas flow rate: 200 sccm

[0530] Time: 20 seconds

[0531] Then, using the Telius etching apparatus manufactured by Tokyo-based Veritech, a hard mask pattern was formed by dry etching of the resist pattern as a mask and etching the silicon-containing resist intermediate layer material (SOG-1). The obtained SOG-1 pattern was then used as a mask to etch the resist underlayer film to form the resist underlayer film pattern. The line dimensions of the obtained resist underlayer film pattern were measured using a critical dimension scanning electron microscope (CG5000) manufactured by Hitachi High-Technologies Corporation.

[0532] Transfer conditions for resist patterning of silicon-containing resist interlayer material (SOG-1).

[0533] Chamber pressure: 50mT

[0534] RF power (top): 500W

[0535] RF power (bottom): 300W

[0536] CF4 gas flow rate: 150 sccm

[0537] CHF3 gas flow rate: 50 sccm

[0538] Time: 15 seconds

[0539] The pattern of the silicon-containing photoresist intermediate layer material (SOG-1) is related to the transfer conditions of the photoresist underlayer film.

[0540] Chamber pressure: 10mT

[0541] RF power (top): 1,000W

[0542] RF power (bottom): 300W

[0543] CO2 gas flow rate: 320 sccm

[0544] N2 gas flow rate: 80 sccm

[0545] Time: 55 seconds

[0546] The resist underlayer pattern obtained from the above evaluation was used as a mask to etch the SiO2 film. The etching conditions are shown below. The line dimensions of the obtained pattern were measured using a critical dimension scanning electron microscope (CG5000) manufactured by Hitachi High-Technologies Corporation. The pattern cross-section was observed using an electron microscope (S-4700) manufactured by Hitachi, Ltd.

[0547] Chamber pressure: 100mT

[0548] RF power (top): 500W

[0549] RF power (bottom): 300W

[0550] CF4 gas flow rate: 150 sccm

[0551] CHF3 gas flow rate: 30 sccm

[0552] O2 gas flow rate: 10 sccm

[0553] Time: 130 seconds

[0554] (Comparative Examples 1-3)

[0555] The following evaluations were made for Comparative Examples 1-3.

[0556] The aforementioned composition for forming the lower resist film (UDL-1) was coated onto a silicon wafer substrate on which a SiO2 film was formed, and calcined at 350°C for 60 seconds to form a lower resist film with a thickness of 60 nm. Subsequently, the lower resist film before patterning was subjected to plasma irradiation treatment under the same conditions as the plasma irradiation treatment of the lower resist film pattern in the embodiment. A silicon-atom-containing resist intermediate layer material (SOG-1) was coated onto it and baked at 220°C for 60 seconds to form a resist intermediate layer film with a thickness of 20 nm. An ArF monolayer resist of the upper resist film material was coated onto it and baked at 105°C for 60 seconds to form a photoresist film with a thickness of 100 nm. A wetting protective film material (TC-1) was coated onto the photoresist film and baked at 90°C for 60 seconds to form a protective film with a thickness of 50 nm.

[0557] Then, exposure was performed using an ArF immersion exposure apparatus (Nikon Corporation; NSR-S610C, NA 1.30, σ 0.98 / 0.78, 35-degree dipole s-polarized illumination, 6% half-step phase shift mask), followed by baking at 100°C for 60 seconds (PEB), and development with a 2.38% by mass tetramethylammonium hydroxide (TMAH) aqueous solution for 30 seconds to obtain a 45nm 1:1 positive line and spacing pattern (resist pattern).

[0558] Then, using the Telius etching apparatus manufactured by Tokyo-based Wistron Corporation, a silicon-containing photoresist interlayer material (SOG-1) was etched using dry etching with the photoresist pattern as a mask to form a hard mask pattern. The obtained SOG-1 pattern was then used as a mask to etch the underlying photoresist film to form the underlying photoresist film pattern. The line dimensions of the obtained underlying photoresist film pattern were measured using a critical dimension scanning electron microscope (CG5000) manufactured by Hitachi High-Technologies Corporation.

[0559] Transfer conditions for resist patterning of silicon-containing resist interlayer material (SOG-1).

[0560] Chamber pressure: 50mT

[0561] RF power (top): 500W

[0562] RF power (bottom): 300W

[0563] CF4 gas flow rate: 150 sccm

[0564] CHF3 gas flow rate: 50 sccm

[0565] Time: 15 seconds

[0566] Transfer conditions for the resist underlayer film of a pattern of silicon-containing resist intermediate layer material (SOG-1).

[0567] Chamber pressure: 10mT

[0568] RF power (top): 1,000W

[0569] RF power (bottom): 300W

[0570] CO2 gas flow rate: 320 sccm

[0571] N2 gas flow rate: 80 sccm

[0572] Time: 55 seconds

[0573] The resist underlayer pattern obtained from the above evaluation was used as a mask for etching the SiO2 film. The etching conditions are as described below. The line dimensions of the obtained pattern were measured using a critical dimension scanning electron microscope (CG5000) manufactured by Hitachi High-Technologies Corporation. The pattern cross-section was observed using an electron microscope (S-4700) manufactured by Hitachi, Ltd.

[0574] Chamber pressure: 100mT

[0575] RF power (top): 500W

[0576] RF power (bottom): 300W

[0577] CF4 gas flow rate: 150 sccm

[0578] CHF3 gas flow rate: 30 sccm

[0579] O2 gas flow rate: 10 sccm

[0580] Time: 130 seconds

[0581] The results of the above-described embodiments and comparative examples are presented in Tables 6 and 7 below. A change of less than 5% in line size after plasma irradiation relative to the line size before plasma irradiation is designated as "A (Excellent)", a change of 5% to less than 10% is designated as "B (Good)", and a change of 10% or more is designated as "C (Poor)".

[0582] [Table 6]

[0583]

[0584]

[0585] [Table 7]

[0586]

[0587] (In Tables 6 and 7, *1 represents the pattern of the underlayer resist, *2 represents the resist pattern, and *3 represents the underlayer resist.)

[0588] As shown in Tables 6 and 7, Examples 1-1 to 1-17 showed small changes in CD (diameter of plasma) before and after plasma irradiation compared to Comparative Example 1-1, or improvements in LWR (lower radiant temperature) due to plasma irradiation. Furthermore, the SiO2 film pattern processed using these examples as masks exhibited good LWR compared to Comparative Example 1-1, confirming their suitability for microfabrication.

[0589] Comparative Example 1-1, which uses Comparative Example UDL-1 without aromatic rings, showed a large change in CD before and after plasma irradiation compared to Examples 1-1 to 1-17. Twist could be observed in the cross-sectional shape of the line pattern, and the LWR was also confirmed to be insufficient.

[0590] On the other hand, in Comparative Examples 1-2, where plasma irradiation was performed on the resist pattern but not on the underlying resist film pattern, significant changes in line size and twisting of the line pattern were observed. When used for SiO2 film patterning, the pattern could not be transferred to the SiO2 film, possibly because the dry etching of the resist pattern against chlorofluorocarbon gases was insufficient.

[0591] Comparative Examples 1-3, which transferred resist patterns to the resist underlayer film through plasma irradiation, showed a larger LWR (Low Residue Flow Ratio) compared to Examples 1-1 to 1-17, while the LWR of the SiO2 film pattern obtained by masking was insufficient. Plasma irradiation of the resist underlayer film without a pattern leads to film thickening, which is expected to limit the uniform modification of the film as a whole. On the other hand, plasma irradiation of the resist underlayer film pattern according to the present invention efficiently modifies the film on the sidewall surface of the pattern. Therefore, it can be inferred that the edge roughness of the resist underlayer film pattern is improved by plasma irradiation.

[0592] [Evaluation of wet peeling of SOG film on resist underlayer pattern]

[0593] The SOG film remaining on the resist underlayer pattern was immersed in a 25% tetramethylammonium hydroxide aqueous solution at 70°C for 10 minutes, and the cross-sectional shape of the resist underlayer pattern was observed using an electron microscope (S-4700) manufactured by Hitachi, Ltd.

[0594] When the SOG film is removed, the cross-sectional shape of the resist underlayer pattern is rectangular, which is judged as "rectangular". When the SOG film is removed, but the cross-sectional shape of the resist underlayer pattern is twisted, it is judged as "defective". The results are shown in Table 8.

[0595] The pattern of the evaluated resist underlayer is shown below.

[0596] Example 2-1: Plasma irradiation of the resist lower layer film pattern obtained in Example 1-1 above.

[0597] Comparative Example 2-1: The resist underlayer pattern prepared in Comparative Example 1-1 above after plasma irradiation

[0598] Comparative Example 2-2: The pattern of the resist underlayer film obtained in Comparative Examples 1-3 above.

[0599] Comparative Examples 2-3: Before plasma irradiation of the resist underlayer film pattern prepared in Example 1-1 above.

[0600] [Table 8]

[0601]

[0602] As shown in Table 8, in Example 2-1, it was confirmed that the cross-sectional shape of the resist underlayer pattern after SOG film removal was rectangular, compared to Comparative Examples 2-1 to 2-2. On the other hand, in Comparative Example 2-3, where the resist underlayer pattern was not subjected to plasma irradiation, it was confirmed that the resist underlayer pattern was twisted after SOG film removal, possibly due to insufficient resistance to the stripping solution.

[0603] The resist underlayer pattern of the present invention undergoes plasma irradiation to modify the film quality of the sidewalls, significantly improving its resistance to stripping solutions. Because it is suitable for removing silicon-containing films that have been stripped using stripping solutions, it is extremely useful as a core material for sidewall liner methods.

[0604] Considering the above, the resist underlayer patterning method of the present invention is extremely useful as a next-generation microfabrication process because it can form a resist underlayer pattern with excellent edge roughness by means of plasma irradiation.

[0605] This specification contains the following specifications.

[0606] [1] A pattern forming method, which is a method for forming a resist underlayer film pattern on a substrate, characterized in that it includes the following steps:

[0607] (i-1) After coating the substrate with a composition for forming a photoresist underlayer, a photoresist underlayer is formed by heat treatment.

[0608] (i-2) After coating the silicon-containing photoresist intermediate film with a composition for forming a silicon-containing photoresist, a silicon-containing photoresist intermediate film is formed by heat treatment.

[0609] (i-3) A top layer of photoresist is formed on the silicon-containing photoresist intermediate film.

[0610] (i-4) After the upper layer of the photoresist is exposed to a pattern, it is developed with a developer to form a pattern on the upper layer of the photoresist.

[0611] (i-5) A lower resist film pattern is formed by repeated etching using the upper resist film pattern as a mask, and

[0612] (i-6) The pattern of the lower layer of the resist film is subjected to plasma irradiation;

[0613] As a component for forming the lower film of this resist, a resin containing an aromatic ring is used.

[0614] The plasma used for plasma irradiation in step (i-6) is less etched than the etching gas used in step (i-5) to form the resist underlayer pattern by etching the resist underlayer.

[0615] [2] A pattern forming method, which is a method for forming a resist underlayer film pattern on a substrate, characterized in that it includes the following steps:

[0616] (ii-1) After coating the substrate with a composition for forming a photoresist underlayer, a photoresist underlayer is formed by heat treatment.

[0617] (ii-2) An inorganic hard mask intermediate film selected from silicon oxide film, silicon nitride film, and silicon oxide nitride film is formed on the lower layer of the resist film.

[0618] (ii-3) A resist upper layer film is formed on the intermediate film of the inorganic hard mask.

[0619] (ii-4) After the upper layer of the photoresist is exposed to a pattern, it is developed using a developer to form a pattern on the upper layer of the photoresist.

[0620] (ii-5) A lower resist film pattern is formed by repeated etching using the upper resist film pattern as a mask, and

[0621] (ii-6) The pattern of the lower layer of the resist film is subjected to plasma irradiation;

[0622] As a component for forming the lower film of this resist, a resin containing an aromatic ring is used.

[0623] The plasma used for plasma irradiation in step (ii-6) is less etched than the etching gas used in step (ii-5) to form the resist underlayer pattern by etching the resist underlayer.

[0624] [3] The pattern forming method as in [1] or [2] further includes, after the plasma irradiation step, the step of using the plasma-irradiated resist lower film pattern as an etching mask to directly or indirectly form a pattern on the substrate.

[0625] [4] A pattern forming method as described in any of [1] to [3], wherein the plasma irradiation step is performed in an environment of N2, NF3, H2, fluorocarbons, rare gases, or any mixture thereof.

[0626] [5] A pattern forming method as described in any of [1] to [4], wherein the plasma irradiation step is performed in an environment containing hydrogen or helium.

[0627] [6] A pattern forming method as described in any of [1] to [5], wherein the composition for forming the resist underlayer film contains (A) resin,

[0628] The (A) resin is

[0629] (a) Polystyrene-converted polymers with a weight average molecular weight of 2,500 to 20,000 as determined by gel permeation chromatography with aromatic rings in the main chain;

[0630] (b) Compounds containing aromatic rings with a weight-average molecular weight of 600 to 3,000 based on polystyrene converted by gel permeation chromatography.

[0631] Or a combination thereof.

[0632] [7] The pattern forming method of [6] wherein the (A) resin has at least one crosslinking group selected from vinyl, allyl, allyloxy, ethynyl, propynyl, propynyloxy, epoxy, oxetane, and hydroxyl.

[0633] [8] A pattern forming method as described in any one of [1] to [7], wherein the method of forming a pattern of 1 / 2 pitch of the resist upper film pattern on the substrate,

[0634] After the step of plasma irradiating the underlying resist film pattern, the following steps are performed:

[0635] An inorganic silicon film composed of any of the following materials—polycrystalline silicon, amorphous silicon, silicon oxide, silicon nitride, silicon nitride oxide, silicon carbide, and composites thereof—is formed by CVD or ALD methods, covering the underlying pattern of the resist film.

[0636] The lower resist film pattern is removed by dry etching or stripping solution to form an inorganic silicon film pattern with a pattern pitch of 1 / 2 that of the upper resist film pattern.

[0637] Furthermore, this invention is not limited to the embodiments described above. The embodiments described above are illustrative examples, and any embodiments having substantially the same technical concept as those described in the claims of this invention, and performing the same effects, are all included within the technical scope of this invention.

[0638] Explanation of reference numerals in the attached figures

[0639] 1: The substrate being processed

[0640] 2: Processed layer

[0641] 2b: Pattern (the pattern formed on the processed layer)

[0642] 3: Underlayer film of resist

[0643] 3a: Pattern of the underlayer resist film

[0644] 3b: Pattern of the resist underlayer after plasma irradiation

[0645] 4: Silicon-containing photoresist interlayer

[0646] 4a: Pattern of resist interlayer containing silicon atoms

[0647] 4b: Pattern of silicon-containing resist interlayer after plasma irradiation.

[0648] 5: Top layer of resist film

[0649] 5a: Pattern of the upper layer of the resist film

[0650] 6: Exposure section

[0651] 7: Inorganic silicon film

[0652] 7a: Inorganic silicon film pattern

Claims

1. A pattern forming method, comprising forming a resist underlayer pattern on a substrate, characterized in that, Includes the following steps: (i-1) After coating the substrate with a composition for forming a photoresist underlayer, a photoresist underlayer is formed by heat treatment. (i-2) After coating the silicon-containing photoresist intermediate film with a composition for forming a silicon-containing photoresist, a silicon-containing photoresist intermediate film is formed by heat treatment. (i-3) A top layer of photoresist is formed on the silicon-containing photoresist intermediate film. (i-4) After the upper layer of the photoresist is exposed to a pattern, it is developed with a developer to form a pattern on the upper layer of the photoresist. (i-5) A lower resist film pattern is formed by repeated etching using the upper resist film pattern as a mask, and (i-6) The pattern of the lower layer of the resist film is subjected to plasma irradiation; As a component for forming the lower film of this resist, a resin containing an aromatic ring is used. The plasma used for plasma irradiation in step (i-6) is less etched than the etching gas used in step (i-5) to form the resist underlayer pattern by etching the resist underlayer.

2. A pattern forming method, comprising forming a resist underlayer pattern on a substrate, characterized in that, Includes the following steps: (ii-1) After coating the substrate with a composition for forming a photoresist underlayer, a photoresist underlayer is formed by heat treatment. (ii-2) An inorganic hard mask intermediate film selected from silicon oxide film, silicon nitride film, and silicon oxide nitride film is formed on the lower layer of the resist film. (ii-3) A resist upper layer film is formed on the intermediate film of the inorganic hard mask. (ii-4) After the upper layer of the photoresist is exposed to a pattern, it is developed using a developer to form a pattern on the upper layer of the photoresist. (ii-5) A lower resist film pattern is formed by repeated etching using the upper resist film pattern as a mask, and (ii-6) The pattern of the lower layer of the resist film is subjected to plasma irradiation; As a component for forming the lower film of this resist, a resin containing an aromatic ring is used. The plasma used for plasma irradiation in step (ii-6) is less etched than the etching gas used in step (ii-5) to form the resist underlayer pattern by etching the resist underlayer.

3. The pattern forming method according to claim 1 or 2, wherein, Following the plasma irradiation step, the method further includes using the plasma-irradiated resist underlayer pattern as an etching mask to directly or indirectly form a pattern on the substrate.

4. The pattern forming method according to claim 1 or 2, wherein, The plasma irradiation step is performed in an environment of N2, NF3, H2, fluorocarbons, rare gases, or any mixture of these gases.

5. The pattern forming method according to claim 4, wherein, The plasma irradiation step is performed in an environment containing hydrogen or helium.

6. The pattern forming method according to claim 1 or 2, wherein, The composition for forming the lower layer film of this resist contains (A) resin. The (A) resin is (a) Polystyrene-equivalent polymers with a weight average molecular weight of 2,500 to 20,000 as determined by gel permeation chromatography with aromatic rings in the main chain. (b) Compounds containing aromatic rings with a weight-average molecular weight of 600 to 3,000 based on polystyrene equivalents obtained by gel permeation chromatography. Or a combination thereof.

7. The pattern forming method according to claim 6, wherein, The (A) resin has at least one crosslinking group selected from vinyl, allyl, allyloxy, ethynyl, propargyl, propargyloxy, epoxy, oxobutyl and hydroxyl.

8. The pattern forming method according to claim 1 or 2, wherein, A method for forming a pattern with a 1 / 2 pitch of the upper layer pattern of the resist on the substrate. After the step of plasma irradiating the underlying resist film pattern, the following steps are performed: An inorganic silicon film composed of any of the following materials—polycrystalline silicon, amorphous silicon, silicon oxide, silicon nitride, silicon nitride oxide, silicon carbide, and composites thereof—is formed by CVD or ALD methods, covering the underlying pattern of the resist film. The lower resist film pattern is removed by dry etching or stripping solution to form an inorganic silicon film pattern with a pattern pitch of 1 / 2 that of the upper resist film pattern.

Images