Metal resist developer, developing method, and metal resist pattern forming method

Abstract

To provide a developer for metal resist, with improved metal removability and excellent stability, a development method using the developer for metal resist, and a metal resist pattern formation method using the developer for metal resist.SOLUTION: The present invention provides a developer for metal resist. The developer contains a solvent and a strong acid to be liquid at 20°C. The developer diluted by a factor of 10 fold with pure water has a pH value of 1.99 or more as measured with a pH meter.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a metal resist developer, a developing method, and a method for forming a metal resist pattern. [Background technology]

[0002] The fabrication of semiconductor circuits and devices has involved a continuous reduction in critical dimensions with each generation. As these dimensions decrease, new materials and methods are required to meet the demands of processing and patterning smaller and smaller structures. Patterning generally involves selective exposure of a thin layer of radiation-sensitive material (resist) to form a pattern that is transferred to a subsequent layer or functional material. Metal resists suitable for providing good absorption to EUV (extreme ultraviolet) and EB (electron beam) radiation while simultaneously providing very high etching contrast have been proposed (see, for example, Patent Document 1).

[0003] In patterning using such a metal resist, the ligands coordinated to the metal peroxide in the metal resist are decomposed by exposure to light, hydrolysis and condensation proceed, forming metal oxides, and the resist becomes insoluble in a developer. The resist is then developed to form a pattern with high etching resistance.

[0004] Generally, the pattern is developed using radiation, reactive gases, or liquid solutions to remove selectively sensitive portions of the resist, while other portions of the resist can function as a protective etch-resistant layer. For example, Patent Document 2 proposes the use of a mixture of a first solvent having a low sum of Hansen solubility parameters ΔH+ΔP and a second solvent having a higher sum of Hansen solubility parameters ΔH+ΔP than the first solvent as a developer for metal resists. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] U.S. Patent No. 9,176,377 [Patent Document 2] International Publication No. 2020 / 210660 Summary of the Invention [Problem to be solved by the invention]

[0006] As a result of investigations by the present inventors, it has been found that the developer for metal resists as described in Patent Document 1 has room for improvement in terms of developer stability and metal removability. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a metal resist developer that has improved metal removability and good stability, a developing method using the metal resist developer, and a method for forming a metal resist pattern using the metal resist developer. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention employs the following configuration.

[0008] A first aspect of the present invention is a developer for metal resist, the developer containing a solvent and a strong acid that is liquid at 20°C, and the developer diluted 10 times with pure water has a pH value of 1.99 or higher as measured with a pH meter.

[0009] A second aspect of the present invention is a developing method comprising the step of developing a metal resist using the developer according to the first aspect.

[0010] A third aspect of the present invention is a method for forming a metal resist pattern, comprising the steps of applying a metal resist to a substrate to form a metal resist film, exposing the metal resist film to radiation, and developing the metal resist film, including the area exposed to radiation, using the developer according to the first aspect. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a metal resist developer that has improved metal removability and good stability, a developing method using the metal resist developer, and a method for forming a metal resist pattern using the metal resist developer. DETAILED DESCRIPTION OF THE INVENTION

[0012] (developer) The developer according to the first aspect of the present invention contains a solvent and a strong acid that is liquid at 20° C. The developer according to this aspect is used to develop a metal resist.

[0013] The developer of this embodiment has a pH value of 1.99 or more, preferably 2.00 or more, and more preferably 2.01 or more, measured with a pH meter when the developer is diluted 10 times with pure water. If the pH value of the developer diluted 10 times with pure water, as measured with a pH meter, is 1.99 or higher, it is easy to suppress pattern thinning during development to a sufficiently small range while maintaining metal removal properties. The upper limit of the pH value of the developer is not particularly limited, and is preferably adjusted appropriately depending on the type of metal resist for which the developer of the present embodiment is used. For example, the upper limit is preferably 3.5 or less, more preferably 3.3 or less, and even more preferably 3.12 or less.

[0014] <Solvent> The solvent is not particularly limited, but examples thereof include water and organic solvents. Examples of organic solvents include glycol ethers and esters thereof, such as propylene glycol methyl ether (PGME), propylene glycol methyl ethyl acetate (PGMEA), propylene glycol butyl ether (PGBE), and ethylene glycol methyl ether; alcohols, such as ethanol, propanol, isopropyl alcohol, isobutyl alcohol, hexanol, ethylene glycol, and propylene glycol; cyclic esters, such as γ-butyrolactone; esters, such as n-butyl acetate and ethyl acetate; ketones, such as 2-heptanone; liquid cyclic carbonates, such as propylene carbonate and butylene carbonate; and cyclic sulfones, such as sulfolane. Among these, the solvent is preferably an organic solvent having no hydroxyl group, more preferably a glycol ether and its ester or ketone, further preferably propylene glycol methyl ethyl acetate (PGMEA) or 2-heptanone, and particularly preferably propylene glycol methyl ethyl acetate (PGMEA). By using an organic solvent that does not have a hydroxyl group as the solvent, it is easy to suppress the esterification reaction of the acid (strong acid) in the developer, and it is easy to improve the stability of the developer over time.

[0015] In this embodiment, the solvent may be used alone or as a mixed solvent of two or more kinds. In the developer according to this embodiment, the content of the solvent is preferably 77 to 99.9 mass%, more preferably 82.5 to 99.84 mass%, even more preferably 88 to 99.43 mass%, still more preferably 93.5 to 98.92 mass%, and particularly preferably 96 to 98.41 mass%, relative to the total mass (100 mass%) of the developer. When the content of the solvent is within the above preferred range, it is easy to suppress pattern thinning during development to a sufficiently small range while maintaining metal removability.

[0016] <Strong acid that is liquid at 20°C> In this embodiment, the strong acid is not particularly limited as long as it is liquid at 20°C. As the strong acid, an acid having a pKa of 2 or less is preferred. In this embodiment, the pKa value of a strong acid is a calculated value according to the SPARC pKa calculation method.

[0017] The strong acid is preferably at least one organic acid selected from the group consisting of sulfuric acid (pKa: 0.81), phosphoric acid (pKa: 1.75), methanesulfonic acid (pKa: 0.42), phosphonic acid (pKa: 1.76), trifluoroacetic acid (pKa: 1.14), and trifluoromethanesulfonic acid (pKa: 0.98), more preferably at least one selected from the group consisting of sulfuric acid, methanesulfonic acid, trifluoroacetic acid, phosphoric acid, and phosphonic acid, and even more preferably sulfuric acid.

[0018] In the developer according to this embodiment, the content of the strong acid is preferably 0.05 to 3 mass %, more preferably 0.06 to 2.5 mass %, even more preferably 0.07 to 2 mass %, still more preferably 0.08 to 1.5 mass %, and particularly preferably 0.09 to 1 mass %, relative to the total mass (100 mass %) of the developer. When the content of the strong acid is within the above preferred range, it is easy to suppress pattern thinning during development to a sufficiently small range while maintaining metal removability.

[0019] <Other ingredients> The developer according to this embodiment may contain other components (hereinafter also referred to as "additives") in addition to the above components, as long as the effects of the present invention are not impaired. Examples of additives include organic acids other than the above-mentioned strong acids, inorganic hydrofluoric acid, tetraalkylammonium compounds, surfactants, and the like. Examples of organic acids include carboxylic acids such as acetic acid, formic acid, citric acid, oxalic acid, 2-nitrophenylacetic acid, 2-ethylhexanoic acid, and dodecanoic acid; sugar acids such as ascorbic acid, tartaric acid, and glucuronic acid; sulfonic acids such as benzenesulfonic acid and p-toluenesulfonic acid; and phosphate esters such as bis(2-ethylhexyl)phosphoric acid. Of these, organic acids that are liquid at room temperature, such as acetic acid, formic acid, 2-ethylhexanoic acid, glucuronic acid, and bis(2-ethylhexyl)phosphoric acid, are preferred. Examples of inorganic hydrofluoric acid include hexafluorosilicic acid, hexafluorophosphoric acid, and fluoroboric acid. Examples of the tetraalkylammonium compound include tetramethylammonium fluoride, tetrabutylammonium fluoride, and tetrabutylammonium fluorosilicate. Examples of the surfactant include polyalkylene oxide alkyl phenyl ether surfactants, polyalkylene oxide alkyl ether surfactants, block polymer surfactants consisting of polyethylene oxide and polypropylene oxide, polyoxyalkylene distyrene-substituted phenyl ether surfactants, polyalkylene tribenzyl phenyl ether surfactants, and acetylene polyalkylene oxide surfactants. Among these, acetic acid is preferred as the additive. Any one of the additives may be used alone, or two or more of them may be used in combination. When the developer according to this embodiment contains an additive, the content of the additive is preferably 1 to 60 mass %, more preferably 1 to 50 mass %, and even more preferably 1 to 45 mass %, relative to the total mass (100 mass %) of the developer.

[0020] When the developer of the present embodiment contains acetic acid as an additive, the content of acetic acid is preferably 0.05 to 20 mass %, more preferably 0.1 to 15 mass %, even more preferably 0.5 to 10 mass %, still more preferably 1 to 5 mass %, and particularly preferably 1.5 to 3 mass %, relative to the total mass of the developer. When the content of acetic acid is within the above preferred range, it is easy to suppress pattern thinning during development to a sufficiently small range while maintaining metal removability.

[0021] The developer of this embodiment may be a developer consisting only of a solvent, a strong acid, acetic acid, and inevitable impurities (hereinafter also referred to as "developer A"). In developer A, the content of the solvent is preferably 77 to 99.9 mass%, more preferably 82.5 to 99.84 mass%, even more preferably 88 to 99.43 mass%, still more preferably 93.5 to 98.92 mass%, and particularly preferably 96 to 98.41 mass%, relative to the total mass (100 mass%) of developer A. Furthermore, the content of the strong acid in developer A is preferably 0.05 to 3 mass %, more preferably 0.06 to 2.5 mass %, even more preferably 0.07 to 2 mass %, still more preferably 0.08 to 1.5 mass %, and particularly preferably 0.09 to 1 mass %, relative to the total mass (100 mass %) of developer A. Furthermore, the content of acetic acid in developer A is preferably 0.05 to 20 mass %, more preferably 0.1 to 15 mass %, even more preferably 0.5 to 10 mass %, still more preferably 1 to 5 mass %, and particularly preferably 1.5 to 3 mass %, relative to the total mass (100 mass %) of developer A. When the contents of the solvent, strong acid, and acetic acid in the developer A are within the above-mentioned preferred ranges, it is easy to suppress pattern thinning during development to a sufficiently small range while maintaining metal removability.

[0022] When developer A contains water as a solvent, the water content is preferably 30% by mass or less, more preferably 25% by mass or less, and even more preferably 20% by mass or less, relative to the total mass (100% by mass) of developer A. The lower limit of the water content is not particularly limited, and may be, for example, 0.01% by mass or more, 0.05% by mass or more, or 0.1% by mass or more, relative to the total mass (100% by mass) of developer A. When the water content in the developer A is within the above preferred range, the metal removal ability of the developer is likely to be improved.

[0023] The developer of this embodiment may be a developer consisting only of a solvent, a strong acid, and inevitable impurities (hereinafter also referred to as "developer B"). In developer B, the content of the solvent is preferably 98 to 99.95 mass%, more preferably 98.3 to 99.94 mass%, even more preferably 98.5 to 99.93 mass%, still more preferably 98.7 to 99.92 mass%, and particularly preferably 99.2 to 99.91 mass%, relative to the total mass (100 mass%) of developer B. Furthermore, the content of the strong acid in developer B is preferably 0.05 to 0.9 mass%, more preferably 0.06 to 0.85 mass%, even more preferably 0.07 to 0.83 mass%, still more preferably 0.08 to 0.81 mass%, and particularly preferably 0.09 to 0.80 mass%, relative to the total mass (100 mass%) of developer B. When the contents of the solvent, strong acid, and acetic acid in the developer B are within the above-mentioned preferred ranges, it is easy to suppress pattern thinning during development to a sufficiently small range while maintaining metal removability.

[0024] The developer of this embodiment may not contain at least one selected from the group consisting of carboxylic acids such as acetic acid, formic acid, citric acid, oxalic acid, 2-nitrophenylacetic acid, 2-ethylhexanoic acid, and dodecanoic acid; sugar acids such as ascorbic acid, tartaric acid, and glucuronic acid; sulfonic acids such as benzenesulfonic acid and p-toluenesulfonic acid; phosphoric acid esters such as bis(2-ethylhexyl)phosphoric acid; organic acids such as hexafluorosilicic acid, hexafluorophosphoric acid, and fluoroboric acid; tetraalkylammonium compounds such as tetramethylammonium fluoride, tetrabutylammonium fluoride, and tetrabutylammonium fluorosilicate; and surfactants such as polyalkylene oxide alkylphenyl ether surfactants, polyalkylene oxide alkyl ether surfactants, block polymer surfactants composed of polyethylene oxide and polypropylene oxide, polyoxyalkylene distyrenated phenyl ether surfactants, polyalkylene tribenzyl phenyl ether surfactants, and acetylene polyalkylene oxide surfactants.

[0025] <Metal Resist> The developer according to this embodiment is used to wash away metal resist. The metal resist is not particularly limited, and examples thereof include those containing at least one metal selected from the group consisting of Sn, Bi, Hf, Zr, In, Te, Sb, Ni, Co, Ti, W, Ta, and Mo.

[0026] The developer of this embodiment described above contains a strong acid that is liquid at 20° C. as the acid component, thereby improving metal removability. Therefore, when a metal resist is developed using the developer of this embodiment, development defects (such as microbridging) in the resulting metal resist pattern can be reduced. Furthermore, the developer of this embodiment has good stability because the progress of decomposition of the solvent is suppressed when the amount of acid present is within an appropriate range, making the developer of this embodiment highly useful industrially.

[0027] (Developing method) A second aspect of the present invention is a developing method having a step of developing a metal resist using the developer according to the first aspect.

[0028] In this embodiment, the metal resist that is the object to be developed is typically a metal resist film formed on a support.

[0029] The support is not particularly limited, and conventionally known supports can be used, such as substrates for electronic components and substrates on which a predetermined wiring pattern is formed, etc. More specifically, examples include silicon wafers, substrates made of metals such as copper, chromium, iron, and aluminum, and glass substrates.

[0030] The metal resist is not particularly limited, and examples thereof include those containing at least one metal selected from the group consisting of Sn, Bi, Hf, Zr, In, Te, Sb, Ni, Co, Ti, W, Ta, and Mo.

[0031] In this embodiment, the metal resist preferably contains at least one selected from the group consisting of metal-oxo compounds and metal-hydroxo compounds.

[0032] As metal-oxo compounds and metal-hydroxo compounds (hereinafter collectively also referred to as "metal-oxo / hydroxo compounds"), compounds containing at least one metal selected from the group consisting of Sn, Bi, Hf, Zr, In, Te, Sb, Ni, Co, Ti, W, Ta, and Mo are not particularly limited, but compounds containing Sn (hereinafter also referred to as "tin-oxo / hydroxo compounds") are preferred.

[0033] In this embodiment, the metal-oxo / hydroxo compound is not particularly limited. For example, compounds described in U.S. Patent No. 5,059,059, U.S. Patent Application No. 9,310,684B2, U.S. Patent Application No. 2016 / 0116839A1, U.S. Patent No. 10,228,618B2, U.S. Patent Application No. 2002 / 0076495, U.S. Patent No. 5,419,096, U.S. Patent No. 9,372,402B2, U.S. Patent Application No. 2015 / 0234272A1, etc. can be mentioned.

[0034] As the tin-oxo / hydroxo compound, generally, a radiation-sensitive compound represented by the formula R , x ,

[0035] , , , z , (2-(z / 2)-(x / 2)) , ,

[0036] , SnO (2-(z / 2)-(x / 2)) (OH) x is used. Here, 0 < z ≦ 2 and 0 < (z + x) ≦ 4. Here, R is a hydrocarbyl group having 1 to 31 carbon atoms or a blend thereof having different R groups in the case of N different compositions, and can be described as RN.

[0035] In this embodiment, the form of the metal-oxo / hydroxo compound is not particularly limited. Typically, it is a complex, but it may form a cluster. Alternatively, the metal-oxo / hydroxo compound may form an oxo / hydroxo network.

[0036] The development process can be carried out by a known development method, such as a method of immersing the support in a developer for a certain period of time (dip method), a method of piling up the developer on the surface of the support by surface tension and leaving it standing for a certain period of time (puddle method), a method of spraying the developer onto the surface of the support (spray method), or a method of continuously applying the developer while scanning a developer application nozzle at a constant speed onto a support rotating at a constant speed (dynamic dispense method).

[0037] The development time is not particularly limited, and may be, for example, 2 seconds to 30 minutes, 3 seconds to 15 minutes, 4 seconds to 10 minutes, or 5 seconds to 5 minutes.

[0038] In this embodiment, the metal resist preferably includes a region that has been exposed to radiation. The region that has been exposed to radiation can be formed in the same manner as in the step of exposing a metal resist film to radiation in the method for forming a metal resist pattern, which will be described later. When the metal resist contains areas exposed to radiation, a pattern can be formed by removing the areas with a developer in the case of a positive pattern, or by leaving the areas exposed to radiation and removing the areas not exposed to radiation with a developer in the case of a negative pattern.

[0039] According to the developing method of this embodiment, the metal resist is developed using the developer according to the first aspect, and therefore, according to this embodiment, development defects (such as microbridging) in the resulting metal resist pattern can be reduced.

[0040] (Metal Resist Pattern Forming Method) The method for forming a metal resist pattern of this embodiment includes a step of applying a metal resist to a substrate to form a metal resist film (hereinafter also referred to as a "metal resist film forming step"), a step of exposing the metal resist film to radiation (hereinafter also referred to as an "exposure step"), and a step of developing the metal resist film, including the area exposed to radiation, using the developer according to the first aspect (hereinafter also referred to as a "development step").

[0041] <Metal resist film formation process> The method for forming the metal resist film is not particularly limited, and examples thereof include those described in U.S. Pat. No. 9,176,377 B2, U.S. Patent Application Publication No. 2013 / 0224652, U.S. Pat. No. 9,310,684, U.S. Patent Application Publication No. 2016 / 0116839, Jiang, Jing; Chakrabarty, Souvik; Yu, Mufei; et al., “Metal Oxide Nanoparticle Photoresists for EUV Patterning”, Journal of Photopolymer Science and Technology 27(5), 663-6662014, A Platinum-Fullerene Complex for Patterning Metal Containing Nanostructures, DX Yang, A. Frommhold, DS He, ZY Li, RE Palmer, MA Lebedeva, TW Chamberlain, AN Khlobystov, APG Robinson, Proc SPIE Advanced Lithography, Metal resists and patterning methods described in US Patent Application Publication Nos. 2014, 2009 / 0155546, and 6,566,276 can be used.

[0042] Furthermore, as a method for forming a metal resist film, for example, a method of depositing a metal oxide-containing film on a support by vapor phase growth or the like, as described in JP-A-2015-201622, JP-A-2020-84330, etc., may be used.

[0043] The film thickness of the metal resist film can generally be adjusted by the concentration, viscosity, and spin speed of the precursor solution. For other coating processes, such as vapor deposition, the thickness can also generally be adjusted by selecting the coating parameters. In this embodiment, it may be desirable to employ thin film thicknesses to facilitate high resolution patterning. In this embodiment, the metal resist film may be 1 μm or less, 250 nm or less, 1 to 50 nm, or 1 to 40 nm.

[0044] The substrate in the metal resist film forming step is the same as the support described in the first embodiment, and the metal resist in the metal resist film forming step is the same as the metal resist in the first and second embodiments.

[0045] <Edge rinse process> The metal resist pattern forming method of this embodiment may include, after the metal resist film forming step, a step of applying a cleaning liquid along the peripheral edge of the substrate to remove edge beads on the substrate with the metal resist (hereinafter also referred to as an "edge rinsing step"). The method of edge rinsing is not particularly limited as long as it is a conventionally known process, and examples thereof include the method described in WO 2018 / 031896.

[0046] The number of times the edge is rinsed is not particularly limited, and it can be performed 1 to 20 times. Furthermore, two or more types of cleaning liquids can be applied during the edge rinse. In edge rinsing, the cleaning liquid can be dropped in an amount of preferably 0.05 to 50 mL, more preferably 0.075 to 40 mL, and even more preferably 0.1 to 25 mL. In another embodiment, in the edge rinse, the cleaning liquid may be sprayed at a flow rate of preferably 5 mL / min to 50 mL / min for preferably 1 second to 5 minutes, more preferably 5 seconds to 2 minutes. As the cleaning liquid, the solvent explained in the first embodiment can be used.

[0047] <Pre-bake (PAB) process> Furthermore, the method for forming a metal resist pattern of this embodiment may include, after the metal resist film forming step, a step of performing a pre-baking (PAB) treatment on the substrate provided with the metal resist (pre-baking (PAB) step). The treatment temperature for the pre-baking (PAB) treatment is not particularly limited, but may be 25°C to 250°C, 50°C to 200°C, or 80°C to 250°C. The processing time for the pre-baking (PAB) treatment is not particularly limited, but may be at least 0.1 minutes, may be 0.5 minutes to 30 minutes, or may be 0.75 minutes to 10 minutes.

[0048] <Exposure process> Radiation sources used in the exposure step include extreme ultraviolet (EUV), ultraviolet (UV), and electron beam (EB). The radiation can generally be directed at the metal resist film through a mask, or a radiation beam can be controllably scanned across the metal resist film to form a latent image in the metal resist film.

[0049] <Post-exposure heating (PEB) process> The method for forming a metal resist pattern of this embodiment may include a step of performing a post-exposure bake (PEB) treatment (post-exposure bake (PEB) step) after the exposure step. The processing temperature of the post-exposure bake (PEB) treatment is not particularly limited, but may be 45°C to 250°C, 50°C to 190°C, or 60°C to 175°C. The processing time of the post-exposure bake (PEB) treatment is not particularly limited, but may be at least 0.1 minutes, may be 0.5 to 30 minutes, or may be 0.75 to 10 minutes.

[0050] <Developing process> The developing step is the same as in the developing method according to the second embodiment.

[0051] <Rinse process> The method for forming a metal resist pattern of this embodiment may include, after the developing step, a step of rinsing the metal resist film with a rinsing composition containing the developer according to the first aspect (rinsing step). The rinsing step typically involves contacting the developed metal resist with a rinsing composition comprising the developer according to the first aspect. By including a rinsing step in the method for forming a metal resist pattern of this embodiment, development defects (microbridging, etc.) in the resulting metal resist pattern can be further reduced.

[0052] The processing time for the rinsing step is not particularly limited, but may be 1 second to 20 minutes, 2 seconds to 12 minutes, or 4 seconds to 6 minutes.

[0053] <Post-bake process> The method for forming a metal resist pattern of this embodiment may include a step of post-baking the metal resist film (post-baking step) after the developing step or the rinsing step. The processing time for the post-baking treatment is not particularly limited, but may be 45 to 250°C, 50 to 190°C, or 60 to 175°C. The processing time for the post-baking treatment is not particularly limited, but may be at least 0.1 minutes, may be 0.5 minutes to 30 minutes, or may be 0.75 minutes to 10 minutes.

[0054] According to the method for forming a metal resist pattern of this embodiment, the metal resist is developed using the developer according to the first aspect, and therefore, according to this embodiment, development defects (such as microbridging) in the resulting metal resist pattern can be reduced. [Example]

[0055] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0056] <Preparation of developer> (Examples 1 to 3, Comparative Examples 1 to 3) The respective components shown in Table 1 were mixed to prepare the developer for each example.

[0057]

Table 1

[0058] In Table 1, each abbreviation has the following meaning respectively. Also, the numerical values are the blending amounts (mass %). The pH of the developer for each example is the pH value measured with a pH meter of the solution obtained by diluting each developer 10-fold with pure water. PGMEA: Propylene glycol methyl ethyl acetate.

[0059] <Evaluation of developer stability> 100 mL of the developer for each example was heated at 60°C for 12 hours, and the compositional change before and after heating was observed. The stability of the developer was evaluated according to the following criteria. The results are shown in Table 2. ○: No change was observed in the composition of the developer before and after heating.<( ×: A change was observed in the composition of the developer before and after heating.

[0060] <Evaluation of Sn reduction rate> 1.5 mL of an organometallic tin oxyhydroxide resist (manufactured by Inpria) was applied onto a Si wafer, and a Sn resist film was formed by spin coating under the coating conditions of 2000 rpm for 60 seconds. Next, 25 mL of the developer for each of Comparative Examples 2 to 3 and Examples 1 to 3 was applied onto the Si wafer on which the Sn resist film was formed, and the wafer was rotated at 500 rpm for 25 seconds until it dried. Thereafter, 5 mL of a mixed solution having a mass ratio of 7 / 3 of propylene glycol methyl ether (PGME) and propylene glycol methyl ethyl acetate (PGMEA) was applied, and the wafer was rotated at 500 rpm for 60 seconds until it dried to perform post rinse. Next, using vapor phase decomposition - inductively coupled plasma - mass spectrometry (VPD - ICP - MS), the residual Sn amount (×10 [[ID=:41]] 10atoms / cm 2 ) was measured. The amount of remaining Sn in the developer of Comparative Example 3 was set as a reference value of 100, and the relative value was used to evaluate the amount of remaining Sn. The results are shown in Table 2.

[0061] <Preparation of metal resist> A Sn metal resist 1 was prepared according to the description in Example 1 of JP 2019-113855 A.

[0062] <Formation of Resist Pattern> The above metal resist 1 was spin-coated onto an 8-inch silicon substrate that had been treated with hexamethyldisilazane (HMDS), and then pre-baked (PAB) on a hot plate at 100°C for 120 seconds, followed by drying to form a metal resist film with a thickness of 25 nm. Next, the metal resist film was subjected to patterning (exposure) using an electron beam lithography system JEOL-JBX-9300FS (manufactured by JEOL Ltd.) at an acceleration voltage of 100 kV. This was followed by post-exposure baking (PEB) at 160°C for 120 seconds. The film was then immersed in the developer of each of Comparative Examples 2 to 3 and Examples 1 to 3 at 23°C for 30 seconds to form a negative tone image. After development, post-baking was carried out at 150°C for 5 minutes to obtain a metal resist pattern. Furthermore, when a step of rinsing with each developer for 10 seconds was added before post-baking, metal resist patterns could also be obtained.

[0063] [Table 2]

[0064] From the results shown in Table 2, it was confirmed that the developers of Examples 1 to 3 have higher stability and better metal removal properties than the developers of Comparative Examples 1 to 3, and are able to reduce development defects in resist patterns formed using metal resists.

Claims

1. A developer for metal resist, A developer containing an organic solvent having no hydroxyl group, a strong acid that is liquid at 20°C, and acetic acid, the content of the organic solvent is 77 to 99.9% by mass based on the total mass of the developer, The developer is diluted 10 times with pure water, and the pH value measured with a pH meter is 1.99 or more.

2. 2. The developer according to claim 1, wherein the strong acid has a pKa of 2 or less.

3. 3. The developer according to claim 1, wherein the content of the strong acid is 0.05 to 3% by mass based on the total mass of the developer.

4. The developer according to any one of claims 1 to 3, wherein the content of the acetic acid is 0.05 to 20% by mass based on the total mass of the developer.

5. 5. The developer according to claim 1, wherein the strong acid comprises at least one selected from the group consisting of sulfuric acid, methanesulfonic acid, trifluoroacetic acid, phosphoric acid, and phosphonic acid.

6. The developer according to any one of claims 1 to 5, wherein the strong acid comprises sulfuric acid.

7. A developing method, comprising the step of developing a metal resist using the developer according to any one of claims 1 to 6.

8. 8. The developing method according to claim 7, wherein the metal resist contains at least one compound selected from the group consisting of a metal-oxo compound and a metal-hydroxo compound.

9. 9. The development method according to claim 7, wherein the metal resist includes areas that have been exposed to radiation.

10. A step of applying a metal resist to a substrate to form a metal resist film; exposing the metal resist film to radiation; and A method for forming a metal resist pattern, comprising: a step of developing a metal resist film including a region exposed to radiation using the developer according to any one of claims 1 to 6.

11. A method for forming a metal resist pattern, further comprising, after the developing step, a step of rinsing the metal resist film with a rinsing composition containing the developer according to any one of claims 1 to 5.

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