Dry etching mask composition

Abstract

Provided is a technique related to a dry etching mask composition with which it is possible to form a mask (resist) having improved etching resistance.　One aspect of the present invention is a dry etching mask composition. The dry etching mask composition contains an organic metal salt and a polar solvent. The content of the organic metal salt with respect to the total solid content during drying is 90 mass% or more.

Description

Dry etching mask composition

[0001] The present invention relates to a composition for a dry etching mask.

[0002] In recent years, electronic materials, including semiconductors such as LSIs, have become increasingly miniaturized and finer due to their higher integration, and in particular, the development of technologies for producing fine patterns at the nanometer level has been progressing. Etching using a mask is a common method for producing fine patterns, and dry etching is known as a technology for forming even finer patterns due to its high etching accuracy.

[0003] JP 2012-185484 A

[0004] In dry etching, in order to improve the reproducibility of the transferred pattern and the etching rate, it is necessary to further improve the etching resistance of the mask, and there is still room for improvement. The present invention has been made in consideration of the above-mentioned problems, and an object of the present invention is to provide a composition for a dry etching mask that can form a mask (resist) with improved etching resistance.

[0005] One aspect of the present invention is a composition for use as a dry etching mask, which comprises an organometallic salt and a polar solvent, and in which the content of the organometallic salt relative to the total solid content of the composition when dried is 90 mass % or more.

[0006] In the dry etching mask composition of the above embodiment, the organometallic salt may be a metal salt of an organic carboxylic acid having 1 to 6 carbon atoms. The organometallic salt may contain magnesium or zinc. The viscosity of the dry etching mask composition at 25°C may be 0.1 mP·s to 1000 mP·s. The composition may be used for forming a mask by a pattern transfer method. The composition may be used for forming a mask by a nanoimprint method.

[0007] According to the present invention, it is possible to provide a technique relating to a dry etching mask composition that can form a mask with improved etching resistance.

[0008] 1A and 1B are schematic diagrams showing a mask formation process by a pattern transfer method, and 2A and 2B are schematic diagrams showing a mask formation process by a nanoimprint method.

[0009] Hereinafter, embodiments of the present invention will be described in detail. In this specification, the expression "a to b" in the description of a range of values ​​means that the range is from a to b, unless otherwise specified.

[0010] (Dry Etching Mask Composition) The dry etching mask composition according to the embodiment contains an organometallic salt and a polar solvent.

[0011] Examples of the organic metal salt include organic carboxylic acid metal salts. Here, organic carboxylic acid metal salts having 1 to 10 carbon atoms are preferred, and organic carboxylic acid metal salts having 1 to 6 carbon atoms are more preferred. It is even more preferred that the organic carboxylic acid metal salt have 1 to 4 carbon atoms, thereby improving solubility in polar solvents such as water and methanol and enhancing the dry etching resistance of the mask. Examples of metals contained in the organic metal salt include magnesium or zinc. From the viewpoint of improving etching resistance, it is preferable to use an organic metal salt containing magnesium. Furthermore, the use of an organic metal salt containing magnesium can further improve cleanability after dry etching. Specific examples of the organic metal salt include magnesium formate, magnesium acetate, magnesium acrylate, magnesium gluconate, magnesium bis(2-ethylhexanoate), magnesium decanoate, zinc formate, zinc acetate, and zinc acrylate.

[0012] The dry etching mask composition according to the embodiment may contain, as other components, additives such as a binder such as polyvinyl alcohol, a surfactant, a leveling agent, etc. Furthermore, the dry etching mask composition according to the embodiment may contain a metal inorganic salt such as magnesium chloride, or a metal oxide such as magnesium oxide.

[0013] The contact angle of the polar solvent obtained by the measurement method described below is preferably 90° or less, more preferably 50° or less, and even more preferably 30° or less. When the contact angle of the polar solvent is within the above range, the solubility of the organometallic salt in the polar solvent is maintained, and when the dry etching mask composition is applied to a substrate, the dry etching mask composition is less likely to be repelled by the substrate, resulting in the formation of a coating film with a more uniform thickness. Furthermore, in the pattern transfer method described below, erosion of the pattern transfer resist can be suppressed. <Contact Angle Measurement Method> A 1 μl droplet of polar solvent is dropped onto a substrate (silicon wafer) under conditions of 23°C and 65% RH, and the contact angle is measured 2000 ms after the drop using a contact angle meter (DMo-502, manufactured by Kyowa Interface Science Co., Ltd.). Specifically, the polar solvent may be one or more selected from the group consisting of water, methanol, and ethanol. These may be used alone or in the form of a mixture containing water and methanol, or a mixture containing water and ethanol. This allows the formation of a coating film with a more uniform thickness while maintaining the solubility of the organometallic salt in the polar solvent.

[0014] The viscosity of the dry etching mask composition according to the embodiment can be measured in accordance with JIS Z 8803:2011. The viscosity of the dry etching mask composition is preferably 1,000 mPa·s or less, more preferably 0.1 mPa·s to 500 mPa·s, even more preferably 0.1 mPa·s to 100 mPa·s, and particularly preferably 0.5 mPa·s to 10 mPa·s, using the following measurement method. A viscosity within the above range allows for the formation of a coating film with a more uniform thickness. <Viscosity Measurement Method> A predetermined amount (e.g., 50 mL) of a solution of the dry etching mask composition is prepared under conditions of 25°C and 65% RH, and the viscosity is measured using a Brookfield viscometer (TVB-10M, manufactured by Toki Sangyo Co., Ltd.). The rotor, rotor rotation speed, and other factors may be selected and used depending on the viscosity of the solution to be measured.

[0015] In the dry etching mask composition according to the embodiment, after drying, the content of the organometallic salt relative to the total solid content is preferably 90% by mass or more, more preferably 95% by mass or more, and even more preferably 98% by mass or more. This allows the dry etching resistance of a mask formed using the dry etching mask composition to be further improved. Here, the solid content can be calculated from the weight ratio before and after drying when the dry etching mask composition is dried for 3 minutes in a hot air dryer at 100°C.

[0016] As long as the content of the organometallic salt relative to the total solid content after drying is 90 mass % or more, the content of the polar solvent relative to the total composition for a dry etching mask according to the embodiment is not particularly limited, but from the viewpoint of maintaining good coatability, it is preferably 60 to 99 mass %. When the content of the polar solvent is within the above range, a coating film with a more uniform thickness can be formed.

[0017] (Uses) The dry etching mask composition according to this embodiment is suitable for use in forming a mask by a pattern transfer method, a nanoimprint method, a printing method, etc. Below, an overview of the pattern transfer method and the nanoimprint method using the dry etching mask composition according to this embodiment will be described.

[0018] FIG. 1 is a schematic diagram showing a mask formation process using a pattern transfer method. As shown in FIG. 1( a), a resist 20 is patterned on a material 10 to be etched, such as a silicon wafer, by lithography. Next, as shown in FIG. 1( b), a dry etching mask composition 30 is applied to the openings in the resist 20. The method for applying the dry etching mask composition 30 is not particularly limited, and examples include spraying, spin coating, dipping, and roll coating. Next, as shown in FIG. 1( c), a drying process (e.g., 100° C., 3 minutes) is performed to solidify the dry etching mask composition, forming a mask 32. Next, as shown in FIG. 1( d), the resist is removed to obtain a mask 32 with the transferred resist pattern.

[0019] FIG. 2 is a schematic diagram illustrating a mask formation process using nanoimprinting. As shown in FIG. 2( a), a dry etching mask composition 30 is applied onto a material 10 to be etched, such as a silicon wafer. The method for applying the dry etching mask composition 30 is not particularly limited, and examples thereof include spraying, spin coating, dipping, and roll coating. Next, as shown in FIG. 2( b), a nanoimprinting mold 40 having a predetermined pattern of protrusions and recesses is pressed against the flowable dry etching mask composition 30. Next, as shown in FIG. 2( c), the dry etching mask composition 30 is patterned using the nanoimprinting mold 40. Next, as shown in FIG. 2( d), a drying treatment (e.g., 100°C, 3 minutes) is performed to solidify the dry etching mask composition, forming a mask 32. Next, as shown in FIG. 2( e), the nanoimprinting mold 40 is demolded, yielding a mask 32 to which the pattern of the imprinting mold 40 has been transferred.

[0020] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various other configurations can also be adopted.

[0021] EXAMPLES The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited to these.

[0022] The raw materials and compositions (parts by mass) shown in Table 1 were mixed and stirred to prepare dry etching mask compositions for each Example and Comparative Example.

[0023] (Method for evaluating appearance (paint)) Each dry etching mask composition was transferred to a 10 ml glass screw bottle, and the state of the composition was evaluated. ◯: No undissolved matter, transparent. Δ: No undissolved matter, but cloudy. ×: Undissolved matter present. (Method for evaluating appearance (coated surface)) Each dry etching mask composition was applied to a silicon wafer so that the film thickness after drying would be 200 nm, and the state of the coated surface (exposed surface) of the dry etching mask composition was evaluated. ◯: No repelling was observed on the coated surface. Δ: Repelling was observed on part of the entire coated surface. ×: Repelling was observed on the entire coated surface.

[0024] (Method for Evaluating Resist Erosion Resistance) [Preparation of Evaluation Sample] A resist (OFPR-800, manufactured by Tokyo Ohka Kogyo Co., Ltd.) pattern with an L / S=100 μm / 100 μm was formed on a silicon wafer by lithography so that the resulting pattern would have a thickness of 1.0 μm after drying. A dry etching mask composition was applied between the resulting patterns so that the resulting thickness would be 50 nm after drying, and the coating was allowed to stand for 10 minutes. Thereafter, the dry etching mask composition was dissolved and removed using running water, and the side surface of the resist was observed to evaluate the resist erosion resistance according to the following criteria. ◯: The thickness of the edge of the resist that had been in contact with the dry etching mask composition was 0.7 μm or more and less than 1.3 μm, and the surface that faced the mask was smooth. △: The thickness of the edge of the resist that had been in contact with the dry etching mask composition was 0.5 μm or more and less than 0.7 μm, or 1.3 μm or more and less than 1.5 μm, and the surface that faced the mask was smooth. x: The surface facing the mask is uneven, or the thickness of the edge of the resist that was in contact with the dry etching composition is less than 0.7 μm or 1.5 μm or more.

[0025] (Method for Evaluating Etching Resistance)

[0026] [Preparation of Evaluation Sample] A resist (OFPR-800, manufactured by Tokyo Ohka Kogyo Co., Ltd.) was formed on a silicon wafer by lithography, forming a pattern with an L / S of 100 μm / 100 μm, resulting in a thickness of 1.0 μm after drying. A dry etching mask composition was applied between the patterns obtained above, resulting in a thickness of 50 nm after drying, and then dried in a hot air dryer at 100°C for 3 minutes to solidify, forming a mask. Subsequently, the resist was removed by ashing, and a sample was prepared to which a pattern consisting of the solidified dry etching mask composition had been transferred.

[0027] Dry etching was performed on each sample using an etching device (RIE-101iPH, manufactured by SAMCO) under dry etching processing conditions that etched the silicon wafer by 100 nm. After etching, the etching resistance was evaluated according to the following criteria. Tetrafluoromethane was used as the etching gas. ◎: Mask thickness was 35 nm or more. ○: Mask thickness was 15 nm or more and less than 35 nm. △: Mask thickness was 1 nm or more and less than 15 nm. ×: Mask thickness was less than 1 nm, or mask thickness was less than 1 nm and the mask was at least partially lost, and the silicon wafer was etched.

[0028] (Cleaning Performance Evaluation Method 1) After etching, each sample was immersed and washed in dilute sulfuric acid (10% by mass aqueous solution) at 23°C, and then observed. (Cleaning Performance Evaluation Method 2) After etching, each sample was immersed and washed in a tetramethylammonium hydroxide aqueous solution (2.5% by mass aqueous solution) at 23°C, and then observed. Cleanability was evaluated according to the following criteria. ⊚: In (Cleaning Performance Evaluation Method 1), the mask was removed by immersion washing for 1 minute or less. ○: In (Cleaning Performance Evaluation Method 1), the mask was removed by immersion washing for more than 1 minute but not more than 10 minutes. ◯△: In (Cleaning Performance Evaluation Method 1), the mask remained on the silicon wafer surface by immersion washing for more than 10 minutes but not more than 20 minutes. In (Cleaning Performance Evaluation Method 2), the mask was removed by immersion washing for 10 minutes or less. △: In (Cleaning Performance Evaluation Method 1), the mask remained on the silicon wafer surface by immersion washing for more than 10 minutes but not more than 20 minutes. In (Cleaning Evaluation Method 2), the mask was able to be removed by immersion cleaning for more than 10 minutes but not more than 20 minutes. ×: In both (Cleaning Evaluation Method 1) and (Cleaning Evaluation Method 2), the mask remained on the silicon wafer surface after 20 minutes of immersion cleaning. XX: In (Cleaning Evaluation Method 1), the mask remained on the silicon wafer surface after 20 minutes of immersion cleaning. Or, "In (Cleaning Evaluation Method 1), the mask remained on the silicon wafer surface after immersion cleaning for more than 10 minutes but not more than 20 minutes." and "In (Cleaning Evaluation Method 2), the mask remained on the silicon wafer surface after 20 minutes of immersion cleaning."

[0029] (Viscosity Measurement Method) 50 g of each dry etching mask composition shown in each Example was prepared, and the viscosity was measured using a Brookfield viscometer (TVB-10M, manufactured by Toki Sangyo Co., Ltd.) (in accordance with JIS Z 8803:2011). The measurement conditions were a temperature of 25°C, humidity of 65% RH, container L adapter, rotor number M1, and rotor rotation speed of 60 rpm.

[0030]

[0031] The dry etching mask composition of the present invention is useful as a material for forming a mask when manufacturing electronic components having fine patterns at the nanometer level. CROSS-REFERENCE TO RELATED APPLICATIONS

[0032] This application claims priority based on Japanese Patent Application No. 2024-024973, filed with the Japan Patent Office on February 21, 2024, the entire disclosure of which is incorporated herein by reference in its entirety.

[0033] 10 Material to be etched, 20 Resist, 30 Dry etching mask composition, 32 Mask, 40 Nanoimprint mold

Claims

1. A composition for dry etching masks, comprising: an organometallic salt; and a polar solvent, wherein the content of the organometallic salt relative to the total solid content when dried is 90 mass % or more.

2. The dry etching mask composition according to claim 1, wherein the organic metal salt is a metal salt of an organic carboxylic acid having 1 to 6 carbon atoms.

3. The dry etching mask composition according to claim 1 or 2, wherein the organometallic salt contains magnesium or zinc.

4. A dry etching mask composition according to claim 1 or 2, wherein the viscosity of the dry etching mask composition at 25°C is 0.1 mP·s to 1000 mP·s.

5. The dry etching mask composition according to claim 1 or 2, which is used for forming a mask by a pattern transfer method.

6. The dry etching mask composition according to claim 1 or 2, which is used for forming a mask by nanoimprinting.

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