JP7738469B2 - Metal resist developer, developing method, and metal resist pattern forming method - Google Patents

Description

The present invention relates to a metal resist developer, a development method, and a method for forming a metal resist pattern.

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, U.S. Patent No. 5,929,393).

When patterning using such metal resists, the ligands coordinated to the metal peroxides in the metal resist decompose upon exposure, causing hydrolysis and condensation to occur, forming metal oxides and making the resist insoluble in the developer. The resist is then developed to form a pattern with high etching resistance.

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.

U.S. Patent No. 9,176,377 International Publication No. 2020/210660

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.

To solve the above problems, the present invention adopts the following configuration.

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

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

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 areas exposed to radiation, using the developer according to the first aspect.

The present invention provides a metal resist developer that has improved metal removability and good stability, a development method using the metal resist developer, and a method for forming a metal resist pattern using the metal resist developer.

(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.

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.
When the pH value of a 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 removability.
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.

<Solvent>
The solvent is not particularly limited, but examples thereof include water and organic solvents.
Examples of the organic solvent 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, still more preferably propylene glycol methyl ethyl acetate (PGMEA) or 2-heptanone, and particularly preferably propylene glycol methyl ethyl acetate (PGMEA).
By using an organic solvent having no 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.

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 from 77 to 99.9 mass%, more preferably from 82.5 to 99.84 mass%, even more preferably from 88 to 99.43 mass%, still more preferably from 93.5 to 98.92 mass%, and particularly preferably from 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.

<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 the strong acid is a calculated value according to the SPARC pKa calculation method.

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 acid selected from the group consisting of sulfuric acid, methanesulfonic acid, trifluoroacetic acid, phosphoric acid, and phosphonic acid; and even more preferably sulfuric acid.

In the developer according to this embodiment, the content of the strong acid is preferably from 0.05 to 3 mass%, more preferably from 0.06 to 2.5 mass%, even more preferably from 0.07 to 2 mass%, still more preferably from 0.08 to 1.5 mass%, and particularly preferably from 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.

<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 the organic acid 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 still more preferably 1 to 45 mass %, relative to the total mass (100 mass %) of the developer.

When the developer of the present embodiment contains acetic acid as an additive, the content of acetic acid is preferably from 0.05 to 20 mass %, more preferably from 0.1 to 15 mass %, even more preferably from 0.5 to 10 mass %, still more preferably from 1 to 5 mass %, and particularly preferably from 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.

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 from 77 to 99.9 mass%, more preferably from 82.5 to 99.84 mass%, even more preferably from 88 to 99.43 mass%, still more preferably from 93.5 to 98.92 mass%, and particularly preferably from 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 from 0.05 to 3 mass%, more preferably from 0.06 to 2.5 mass%, even more preferably from 0.07 to 2 mass%, still more preferably from 0.08 to 1.5 mass%, and particularly preferably from 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 from 0.05 to 20% by mass, more preferably from 0.1 to 15% by mass, even more preferably from 0.5 to 10% by mass, still more preferably from 1 to 5% by mass, and particularly preferably from 1.5 to 3% by mass, relative to the total mass (100% by 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.

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-mentioned preferred range, the metal removal ability of the developer is likely to be improved.

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 from 98 to 99.95% by mass, more preferably from 98.3 to 99.94% by mass, still more preferably from 98.5 to 99.93% by mass, still more preferably from 98.7 to 99.92% by mass, and particularly preferably from 99.2 to 99.91% by mass, relative to the total mass (100% by mass) of developer B.
Furthermore, in developer B, the content of the strong acid is preferably from 0.05 to 0.9 mass%, more preferably from 0.06 to 0.85 mass%, still more preferably from 0.07 to 0.83 mass%, still more preferably from 0.08 to 0.81 mass%, and particularly preferably from 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.

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; phosphate 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 alkyl phenyl 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.

<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.

The developer of this embodiment described above contains a strong acid that is liquid at 20° C. as the acid component, and therefore has improved 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.

(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.

In this embodiment, the metal resist to be developed is typically a metal resist film formed on a support.

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

Metal resists are not particularly limited, but examples 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.

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

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

In this embodiment, the metal oxo/hydroxo compound is not particularly limited, and examples include compounds described in U.S. Patent No. 5,059,059, U.S. Patent Application No. 9,310,684 B2, U.S. Patent Application No. 2016/0116839 A1, U.S. Patent No. 10,228,618 B2, U.S. Patent Application No. 2002/0076495, U.S. Patent No. 5,419,096, U.S. Patent No. 9,372,402 B2, U.S. Patent Application No. 2015/0234272 A1, etc.

The tin oxo/hydroxo compound generally used is a radiation-sensitive compound represented by the formula _{RzSnO (2-(z/2)-(x/2))} (OH) _x , where 0<z≦2 and 0<(z+x)≦4, where R is a hydrocarbyl group having 1 to 31 carbon atoms or a blend thereof with different R groups in the case of N different compositions, which can be written as RN.

In this embodiment, the form of the metal oxo/hydroxo compound is not particularly limited, and is typically a complex, but may also form a cluster. Alternatively, the metal oxo/hydroxo compound may form an oxo/hydroxo network.

Development can be carried out by known development methods, such as immersing the support in a developer for a certain period of time (dip method), puddling the developer on the support surface using surface tension and leaving it there for a certain period of time (puddle method), spraying the developer onto the support surface (spray method), or continuously dispensing the developer by scanning a developer dispensing nozzle at a constant speed onto a support rotating at a constant speed (dynamic dispense method).

The development time is not particularly limited, but 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.

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.

According to the development method of this embodiment, the metal resist is developed using the developer according to the first aspect. Therefore, this embodiment can reduce development defects (such as microbridging) in the resulting metal resist pattern.

(Metal Resist Pattern Forming Method)
The method for forming a metal resist pattern of the present 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 region exposed to radiation, using the developer according to the first aspect (hereinafter also referred to as a "development step").

<Metal Resist Film Forming 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, D. X. Yang, A. Frommhold, D. S. He, Z. Y. Li, R. E. Palmer, M. A. Lebedeva, T. Metal resists and patterning methods described in W. Chamberlain, A. N. Khlobystov, A. P. G. Robinson, Proc. SPIE Advanced Lithography, 2014, U.S. Patent Application Publication No. 2009/0155546, U.S. Patent Application Publication No. 6,566,276, and the like can be used.

In addition, a method for forming a metal resist film may be used, for example, a method for 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.

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.

The substrate used in the metal resist film formation process is the same as the support described in the first embodiment. The metal resist used in the metal resist film formation process is the same as the metal resist used in the first and second embodiments.

<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.

The number of times the edge rinse is performed is not particularly limited, and it can be performed 1 to 20 times. Furthermore, two or more types of cleaning solutions can be applied during the edge rinse.
In the edge rinse, 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.

<Pre-baking (PAB) process>
Furthermore, the method for forming a metal resist pattern of this embodiment may include a step of performing a pre-baking (PAB) treatment on the substrate provided with the metal resist (pre-baking (PAB) step) after the metal resist film forming 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.

<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.

<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 minutes to 30 minutes, or may be 0.75 minutes to 10 minutes.

<Developing process>
The developing step is the same as that of the developing method according to the second aspect.

<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.

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

<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 of the post-baking 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 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.

According to the metal resist pattern forming method of this embodiment, the metal resist is developed using the developer according to the first aspect. Therefore, this embodiment can reduce development defects (such as microbridging) in the resulting metal resist pattern.

The present invention will be explained in more detail below using examples, but the present invention is not limited to these examples.

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

In Table 1, the abbreviations have the following meanings: The numerical values are the blending amounts (% by mass).
The pH of the developer in each example is the pH value measured with a pH meter for a solution obtained by diluting each developer 10 times with pure water.
PGMEA: propylene glycol methyl ethyl acetate.

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

<Evaluation of Sn reduction rate>
1.5 mL of organometallic tin oxyhydroxide resist (manufactured by Inpria) was applied onto a Si wafer, and a Sn resist film was formed by spin coating under application conditions of 2000 rpm and 60 seconds.
Next, 25 mL of each developer from Comparative Examples 2 to 3 and Examples 1 to 3 was applied to a Si wafer on which a Sn resist film had been formed, and the wafer was rotated at 500 rpm for 25 seconds until dry. After that, 5 mL of a mixed solution of propylene glycol methyl ether (PGME) and propylene glycol methyl ethyl acetate (PGMEA) in a mass ratio of 7/3 was applied, and the wafer was rotated at 500 rpm for 60 seconds until dry, thereby performing post-rinse.
Next, the amount of residual Sn (×10 ¹⁰ atoms/cm ² ) was measured using ChemTrace (registered trademark) by vapor phase decomposition-inductively coupled plasma-mass spectrometry (VPD-ICP-MS). The amount of residual 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 residual Sn. The results are shown in Table 2.

<Preparation of Metal Resist>
A Sn metal resist 1 was prepared according to the description of Example 1 of JP 2019-113855 A.

<Formation of Resist Pattern>
The above-mentioned metal resist 1 was spin-coated on an 8-inch silicon substrate that had been treated with hexamethyldisilazane (HMDS), and then pre-baked (PAB) on a hot plate at a temperature of 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) treatment 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.

The results shown in Table 2 confirm that the developers of Examples 1 to 3 are more stable and have 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 resist.

Claims (11)

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. The developer according to claim 1, wherein the strong acid has a pKa of 2 or less. The developer according to claim 1 or 2, wherein the content of the strong acid is 0.05 to 3% by mass based on the total mass of the developer. 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. 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. The developer according to any one of claims 1 to 5 , wherein the strong acid comprises sulfuric acid. A developing method, comprising the step of developing a metal resist using the developer according to any one of claims 1 to 6 . 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. The development method according to claim 7 , wherein the metal resist includes areas that have been exposed to radiation. A step of applying a metal resist to a substrate to form a metal resist film;
A method for forming a metal resist pattern, comprising: a step of exposing a metal resist film to radiation; and a step of developing the metal resist film including the region exposed to radiation using the developer according to any one of claims 1 to 6 . 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 .