Photolithography process liquid composition and pattern forming method using the same

Abstract

The present invention relates to a process liquid composition for improving crack defects and reducing the number of defects in a photoresist pattern in a photoresist pattern process, and a pattern forming method using the same. The photoresist pattern has a hydrophobicity with a contact angle of water on the photoresist surface of 70° or more. More specifically, the present invention relates to a process liquid composition comprising 0.00001 to 0.1 wt% of a fluorine-based surfactant, 0.0001 to 0.1 wt% of a hydrocarbon-based anionic surfactant, 0.0001 to 0.1 wt% of an alkaline substance, and 99.7 to 99.99979 wt% of water, and having a surface tension of 40 mN / m or less and a contact angle of 60° or less.

Description

Technical Field

[0001] The present invention relates to a process liquid composition for improving crack defects in a photoresist pattern in a photoresist pattern process and a photoresist pattern forming method using the same, wherein the photoresist pattern has hydrophobicity with a contact angle of water on the photoresist surface of 70° or more. Background Art

[0002] Typically, semiconductors are manufactured using a photolithography process that uses ultraviolet light in wavelengths such as 193nm, 248nm, or 365nm as an exposure light source. Companies are competing fiercely to reduce the critical dimension (CD).

[0003] Therefore, in order to form finer patterns, a light source with a smaller wavelength is required. Currently, photolithography technology using extreme ultraviolet (EUV) light source with a wavelength of 13.5nm is widely used, which can achieve finer patterns.

[0004] However, the etching resistance of EUV photoresists has not been improved, and thus photoresist patterns with large aspect ratios continue to be required. As a result, pattern crack defects are easily generated during development, and the number of defects increases, resulting in a significant reduction in process margin in the manufacturing process.

[0005] Therefore, there is a need to develop a technology that can improve the severity and reduce the number of crack defects generated during fine pattern formation. The best way to improve the severity and reduce the number of defects in pattern cracks is to improve the performance of photoresists. However, it is currently difficult to develop new photoresists that meet all the requirements.

[0006] While the need for new photoresist development remains, efforts are ongoing to improve the degree of pattern cracking and reduce the number of defects through other methods. Summary of the Invention

[0007] Technical problems to be solved

[0008] The purpose of the present invention is to develop a process liquid composition and a method for forming a photoresist pattern using the same, wherein the process liquid composition is used to improve the degree of crack defects in the pattern produced after photoresist development and reduce the number of defects, wherein the photoresist pattern has a hydrophobicity with a contact angle of water on the photoresist surface of greater than 70°.

[0009] Solutions to the Problem

[0010] Although various surfactants are currently used in aqueous process liquid compositions used in development processes, in the present invention, an effective process liquid composition is prepared using a fluorine-based surfactant and a hydrocarbon-based anionic surfactant.

[0011] When using a hydrocarbon nonionic surfactant that tends to be hydrophobic in the process liquid composition of the aqueous type of ultrapure water, the hydrophobization of the photoresist wall is induced, thereby being able to induce the dissolution (melting) and collapse reduction of the pattern. However, due to the strong tendency of hydrocarbon nonionic surfactants to aggregate with each other, the physical properties of the process liquid composition become uneven, so there is the possibility of inducing defects (defects) by the aggregated hydrocarbon nonionic surfactants during use. That is, when using hydrocarbon nonionic surfactants, it is necessary to increase the usage amount in order to improve dissolution, which has the concern of causing damage to the photoresist. In addition, when using an unsuitable surfactant for the purpose of reducing the surface tension of the process liquid composition in order to reduce capillary force, it is possible to further induce pattern collapse due to the dissolution of the induced pattern.

[0012] Furthermore, hydrocarbon-based cationic surfactants rarely dissociate their active groups into cations in aqueous solution to secure metals, which can lead to serious defects in photolithography processes.

[0013] In this invention, the use of fluorinated surfactants and hydrocarbon anionic surfactants has been shown to be highly effective in improving the severity and number of pattern crack defects. This is believed to be due to the lower surface tension and contact angle, increased penetration and diffusivity, and improved micropattern formation compared to hydrocarbon nonionic surfactants.

[0014] As a representative developer used in most current photolithography development processes, pure water is used as a base, and tetramethylammonium hydroxide is diluted to a certain concentration for use (in most processes, 2.38 wt % tetramethylammonium hydroxide is mixed with 97.62 wt % water for use).

[0015] It has been confirmed that, after developing a hydrophobic photoresist pattern with a water contact angle of 70° or greater on the photoresist surface during the photolithography process, pattern cracking defects occur when the pattern is continuously washed with pure water alone. It has also been confirmed that pattern collapse occurs when a process liquid composition containing tetramethylammonium hydroxide in pure water is continuously used after development, or when pure water is continuously used.

[0016] In the case of the process liquid composition containing tetramethylammonium hydroxide, it is presumed that the exposed fine pattern is weakened and the pattern collapses due to a strong or uneven capillary force.

[0017] Therefore, in order to improve the collapse of the exposed pattern and further improve the line width roughness (LWR) and defects of the photoresist pattern required in the process, it is necessary to study alkaline substances that impart a relatively weaker force to the exposed pattern than tetramethylammonium hydroxide.

[0018] In the present invention, it was confirmed that when tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide among alkaline substances were used, defects including LWR and pattern collapse were improved.

[0019] Therefore, the present invention, as a preferred first embodiment, provides a process liquid composition for improving the degree of crack defects in a photoresist pattern occurring during photoresist development and reducing the number of defects, characterized in that the process liquid composition is composed of 0.00001 to 0.1 weight % of a fluorine-based surfactant, 0.0001 to 0.1 weight % of a hydrocarbon-based anionic surfactant, 0.0001 to 0.1 weight % of an alkaline substance, and 99.7 to 99.99979 weight % of water, and has a surface tension of less than 40 mN / m (millinewtons / meter, millinewtons / meter = 1 / 1000 Newtons / meter) and a contact angle of less than 60°.

[0020] In addition, the present invention, as a more preferred second embodiment, provides a process liquid composition for improving the degree of crack defects in a photoresist pattern occurring during photoresist development and reducing the number of defects, characterized in that the process liquid composition is composed of 0.0001 to 0.1 weight % of a fluorine-based surfactant, 0.001 to 0.1 weight % of a hydrocarbon-based anionic surfactant, 0.001 to 0.1 weight % of an alkaline substance and 99.7 to 99.9979 weight % of water, and has a surface tension of less than 40 mN / m and a contact angle of less than 60°.

[0021] In addition, the present invention, as the most preferred third embodiment, provides a process liquid composition for improving the degree of crack defects in a photoresist pattern occurring during photoresist development and reducing the number of defects, characterized in that the process liquid composition is composed of 0.001 to 0.1 weight % of a fluorochemical surfactant, 0.01 to 0.1 weight % of a hydrocarbon anionic surfactant, 0.01 to 0.1 weight % of an alkaline substance, and 99.7 to 99.979 weight % of water, and has a surface tension of less than 40 mN / m and a contact angle of less than 60°.

[0022] The fluorine-based surfactant according to the above embodiment can be selected from the group consisting of fluoroacrylcarboxylate, fluoroalkyl ether, fluoroalkylene ether, fluoroalkyl sulfate, fluoroalkylphosphate, fluoroacryl co-polymer, fluoroco-polymer, perfluorinated acid, perfluorinated carboxylate, perfluorinated sulfonate, or a mixture thereof.

[0023] The hydrocarbon-based anionic surfactant according to the above embodiment may be selected from the group consisting of polycarboxylic acid ammonium salts, sulfonates, sulfates, phosphates, or mixtures thereof.

[0024] The alkaline substance according to the above embodiment may be selected from the group consisting of tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, or a mixture thereof.

[0025] In addition, the present invention also provides a method for forming a photoresist pattern, which is characterized in that it includes the following steps: (a) coating a photoresist on a semiconductor substrate to form a film; (b) exposing the photoresist film and then developing it to form a pattern; and (c) using a process liquid composition for improving crack defects in the photoresist pattern and reducing the number of defects to wash the photoresist pattern.

[0026] The cause of pattern collapse is believed to be the capillary force generated between patterns when the patterns are washed with pure water after development. However, it is known from experience that simply reducing the capillary force cannot completely improve pattern collapse and reduce the number of defects.

[0027] When an unsuitable surfactant is used excessively for the purpose of reducing the surface tension of the process liquid composition in order to reduce capillary force, dissolution of the pattern may be induced, thereby further inducing pattern crack defects or increasing the number of defects.

[0028] In order to improve pattern crack defects and reduce the number of defects, it is important to select a surfactant that can reduce the surface tension of the process liquid composition while preventing the dissolution of the photoresist pattern.

[0029] The process liquid composition of the present invention has an excellent effect on photoresist, in particular, it has the effect of improving pattern crack defects occurring during the development of the photoresist and reducing the number of defects, wherein the photoresist pattern has a hydrophobicity with a contact angle of water on the photoresist surface of 70° or more.

[0030] Effects of the Invention

[0031] The process liquid composition of the present invention has the effect of improving pattern crack defects and reducing the number of defects when forming a pattern using a hydrophobic photoresist having a water contact angle of 70° or more on the photoresist surface. This is an effect that cannot be achieved when using the photoresist alone. In particular, the photoresist pattern forming method including a washing step using such a process liquid composition shows the effect of significantly reducing production costs.

[0032] Best Practice

[0033] Hereinafter, the present invention will be described in more detail.

[0034] The present invention, developed after extensive research over a long period of time, relates to a process liquid composition for improving crack defects in a photoresist pattern and reducing the number of defects. The composition comprises 0.00001 to 0.1 wt% of a fluorochemical surfactant, 0.0001 to 0.1 wt% of an anionic surfactant, 0.0001 to 0.1 wt% of an alkaline substance, and 99.7 to 99.99979 wt% of water, wherein the fluorochemical surfactant is selected from the group consisting of fluoroacryl carboxylate, fluoroalkyl ether, fluoroalkylene ether, fluoroalkyl sulfate, fluoroalkyl phosphate, fluoroacryl co-polymer, fluoroco-polymer, perfluorinated acid, and the like. The process liquid composition of the present invention is selected from the group consisting of: a polycarboxylate, a perfluorinated carboxylate, a perfluorinated sulfonate, or a mixture thereof; the anionic surfactant is selected from the group consisting of: a polycarboxylate, an ammonium sulfonate, a sulfate, a phosphate, or a mixture thereof; and the alkaline substance is selected from the group consisting of: tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, or a mixture thereof. The components and composition ratios of the process liquid composition of the present invention are set as Examples 1 to 60, and the corresponding components and composition ratios are set as Comparative Examples 1 to 12.

[0035] Hereinafter, preferred embodiments of the present invention and comparative examples for comparison will be described. However, the following embodiments are merely preferred embodiments of the present invention, and the present invention is not limited thereto. DETAILED DESCRIPTION

[0036] [Example 1]

[0037] A process liquid composition for improving the collapse degree of a photoresist pattern, comprising 0.001 wt % of fluoropropylene carboxylate, 0.01 wt % of polycarboxylic acid ammonium salt, and 0.005 wt % of tetrabutylammonium hydroxide, was prepared by the following method.

[0038] 0.001 wt % of fluoropropylene carboxylate, 0.01 wt % of polycarboxylic acid ammonium salt, and 0.005 wt % of tetrabutylammonium hydroxide were added to the remaining amount of distilled water, stirred for 5 hours, and then passed through a 0.01 μm filter to remove fine solid impurities, thereby preparing a process liquid composition for improving the collapse degree of a photoresist pattern.

[0039] [Example 2 to Example 60]

[0040] According to the compositions described in Tables 1 to 12, the same process liquid compositions as those in Example 1 for improving the degree of defects in a photoresist pattern were prepared.

[0041] [Comparative Example 1]

[0042] Distilled water, which is generally used as a final washing solution in a development process in a semiconductor device manufacturing process, was prepared.

[0043] [Comparative Examples 2 to 12]

[0044] For comparison with the examples, process liquid compositions were prepared according to the compositions described in Tables 1 to 12 in the same manner as in Example 1.

[0045] [Experimental Examples 1 to 60, Comparative Experimental Examples 1 to 12]

[0046] In Examples 1 to 60 and Comparative Examples 1 to 12, pattern crack defects and defect reduction ratios were measured on patterned silicon wafers and expressed as Experimental Examples 1 to 60 and Comparative Experimental Examples 1 to 12. The results are recorded in Table 13.

[0047] (1) Confirmation of preventing pattern cracks

[0048] After splitting the exposure energy and focus, a critical dimension scanning electron microscope (CD-SEM, Hitachi) was used to measure the number of blocks with no pattern collapse among all 89 blocks.

[0049] (2) Reduction ratio of crack defects

[0050] For the photoresist patterns rinsed with the respective process liquid composition reagents, the number of defects (A) was measured using a surface defect observation device (product of KLA TechnoCorp) and expressed as a percentage (%) of the number of defects (B) when rinsed with pure water alone, that is, expressed as (A / B)×100.

[0051] The number of defects after treatment with pure water alone was set as 100 as a reference, and the degree of reduction (improvement) or increase (deterioration) in the number of defects compared to the number of defects after treatment with pure water alone was expressed as a reduction ratio.

[0052] (3) Transparency

[0053] The transparency of the prepared process liquid composition was confirmed with the naked eye and expressed as transparent or opaque.

[0054] (4) Surface tension and contact angle

[0055] The surface tension and contact angle of the prepared process liquid composition were measured using a surface tension meter (K-100, a product of Kruss Company) and a contact angle meter (DSA-100, a product of Kruss Company).

[0056]

Table 1

[0057]

[0058]

[0059]

Table 2

[0060]

[0061]

Table 3

[0062]

[0063]

[0064]

Table 4

[0065]

[0066]

Table 5

[0067]

[0068]

Table 6

[0069]

[0070]

[0071]

Table 7

[0072]

[0073]

Table 8

[0074]

[0075]

[0076]

Table 9

[0077]

[0078]

Table 10

[0079]

[0080]

[0081]

Table 11

[0082]

[0083]

Table 12

[0084]

[0085]

[0086] [Experimental Examples 1 to 60, Comparative Experimental Examples 1 to 12]

[0087] In Examples 1 to 60 and Comparative Examples 1 to 12, the pattern crack defect degree, defect reduction ratio, transparency, contact angle, and surface tension of the patterned silicon wafers were measured, and the results are shown in Experimental Examples 1 to 60 and Comparative Experimental Examples 1 to 12, and are recorded in Table 13.

[0088] (1) Confirmation of preventing pattern cracks

[0089] After separating the exposure energy from the focus, a critical dimension scanning electron microscope (CD-SEM, Hitachi) was used to measure the number of blocks without pattern collapse among all 89 blocks.

[0090] (2) Number of crack defects

[0091] For the photoresist patterns rinsed with the respective process liquid composition reagents, the number of defects (A) was measured using a surface defect observation device (product of KLA TechnoCorp) and expressed as a percentage (%) of the number of defects (B) when rinsed with pure water alone, that is, expressed as (A / B)×100.

[0092] (3) Transparency

[0093] The transparency of the prepared process liquid composition was confirmed with the naked eye and expressed as transparent or opaque.

[0094] (4) Surface tension and contact angle

[0095] The surface tension and contact angle of the prepared process liquid composition were measured using a surface tension meter (K-100, a product of Kruss Company) and a contact angle meter (DSA-100, a product of Kruss Company), respectively.

[0096] Table 13

[0097]

[0098]

[0099]

[0100] Comparing the results of Experimental Examples 1 to 60 with Comparative Experimental Examples 1 to 12, it can be found that based on Comparative Experimental Example 1, if the number of blocks without pattern collapse is more than 50 and the defect reduction ratio is less than 90%, excellent improvement results are shown.

[0101] When the process liquid composition corresponding to Experimental Examples 1 to 60 is composed of 0.00001 to 0.1 weight % of a fluorine-based surfactant, 0.0001 to 0.1 weight % of an anionic surfactant, 0.0001 to 0.1 weight % of an alkaline substance, and 99.7 to 99.99979 weight % of water, when compared with Comparative Experimental Examples 1 to 12, it can be confirmed that the pattern crack defects are improved, and the defect count is also improved. The fluorine-based surfactant is selected from fluoroacryl carboxylate, fluoroalkyl ether, fluoroalkylene ether, fluoroalkyl sulfate, fluoroalkyl phosphate, fluoroacryl co-polymer, fluoroco-polymer, perfluorinated acid, perfluorinated carboxylate, and perfluorinated sulfonate; the anionic surfactant is selected from polycarboxylates, sulfonates, sulfates, and phosphates; and the alkaline substance is selected from tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide.

[0102] In addition, in the process liquid compositions corresponding to Experimental Examples 1 to 60, when the process liquid compositions are composed of 0.0001 to 0.1 weight % of a fluorine-based surfactant, 0.001 to 0.1 weight % of a hydrocarbon-based anionic surfactant, 0.001 to 0.1 weight % of an alkaline substance, and 99.7 to 99.9979 weight % of water, when compared with Comparative Experimental Examples 1 to 12, it can be confirmed that the pattern crack defect improvement and defect number improvement effects are preferably increased. The fluorine-based surfactant is selected from fluoroacryl carboxylate, fluoroalkyl ether, fluoroalkylene ether, fluoroalkyl sulfate, fluoroalkyl phosphate, fluoroacryl co-polymer, fluoroco-polymer, perfluorinated acid, perfluorinated carboxylate, and perfluorinated sulfonate; the hydrocarbon-based anionic surfactant is selected from polycarboxylates, sulfonates, sulfates, and phosphates; and the alkaline substance is selected from tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide.

[0103] Moreover, in the process liquid compositions corresponding to Experimental Examples 1 to 60, when the compositions are composed of 0.001 to 0.1 weight % of a fluorine-based surfactant, 0.01 to 0.1 weight % of a hydrocarbon-based anionic surfactant, 0.01 to 0.1 weight % of an alkaline substance, and 99.7 to 99.979 weight % of water, when compared with Comparative Experimental Examples 1 to 12, it can be confirmed that the pattern crack defect improvement and defect number improvement effects are more preferably increased. The fluorine-based surfactant is selected from fluoroacryl carboxylate, fluoroalkyl ether, fluoroalkylene ether, fluoroalkyl sulfate, fluoroalkyl phosphate, fluoroacryl co-polymer, fluoroco-polymer, perfluorinated acid, perfluorinated carboxylate, and perfluoriauted sulfonate; the hydrocarbon-based anionic surfactant is selected from polycarboxylates, sulfonates, sulfates, and phosphates; and the alkaline substance is selected from tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide.

[0104] The results of evaluating the degree of collapse of the photoresist pattern according to Example 1 are shown in Table 13. The number of blocks (bolts) where no pattern collapse occurred was measured to be 80.

[0105] The results of evaluating the degree of collapse of the photoresist pattern according to Comparative Experimental Example 1 are shown in Table 13. The number of blocks (bolts) where no pattern collapse occurred was measured to be 46.

[0106] While specific aspects of the present invention have been described in detail above, it will be apparent to those skilled in the art that these specific techniques are merely preferred embodiments and that the scope of the present invention is not limited thereto. Therefore, the true scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A process liquid composition for improving crack defects and reducing the number of defects in a photoresist pattern, the process liquid composition comprising a surfactant, characterized in that: The process liquid composition is used in a photoresist pattern process to improve peeling defects of a photoresist pattern and reduce the number of defects, wherein the photoresist pattern has a hydrophobicity with a contact angle of water on the photoresist surface of 70° or more. The surface tension of the process liquid composition is less than 40 mN / m, and the contact angle is less than 60°. The process liquid composition for improving crack defects and reducing the number of defects in a photoresist pattern comprises 0.00001 to 0.1 weight percent of a fluorine-based surfactant, 0.0001 to 0.1 weight percent of a hydrocarbon-based anionic surfactant, 0.0001 to 0.1 weight percent of an alkaline substance, and the balance water. Wherein, the alkaline substance is selected from the group consisting of tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide or a mixture thereof.

2. The process liquid composition for improving crack defects and reducing the number of defects in a photoresist pattern according to claim 1, wherein: The process liquid composition consists of 0.0001 to 0.1 wt % of a fluorine-based surfactant, 0.001 to 0.1 wt % of a hydrocarbon-based anionic surfactant, 0.001 to 0.1 wt % of an alkaline substance, and 99.7 to 99.9979 wt % of water.

3. The process liquid composition for improving crack defects and reducing the number of defects in a photoresist pattern according to claim 2, wherein: The fluorine-based surfactant is selected from the group consisting of fluoropropylene carboxylates, fluoroalkyl ethers, fluoroalkylene ethers, fluoroalkyl sulfates, fluoroalkyl phosphates, fluoroacrylic acid copolymers, fluoro copolymers, perfluoro acids, perfluorocarboxylates, perfluorosulfonates, or mixtures thereof.

4. The process liquid composition for improving crack defects and reducing the number of defects in a photoresist pattern according to claim 2, wherein: The hydrocarbon-based anionic surfactant is selected from the group consisting of polycarboxylic acid ammonium salts, sulfonates, sulfates, phosphates or mixtures thereof.

5. A method for forming a photoresist pattern, characterized in that: The steps include: (a) coating a photoresist on a semiconductor substrate to form a film; (b) exposing the photoresist film and then developing it to form a pattern; and (c) washing the photoresist pattern using the process liquid composition for improving crack defects and reducing the number of defects in a photoresist pattern according to any one of claims 1 to 4.

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