JP2007206728A - Fine pattern formation aid - Google Patents

Abstract

Disclosed is a fine pattern formation auxiliary agent having good filterability and excellent coating defects, development defects, and stability over time.
A water-soluble modified PVA such as acetalized polyvinyl alcohol (PVA) is subjected to demetallization ion and deoxidation by ion exchange treatment, followed by heat treatment at 80 ° C. or higher. Thereby, the amount of high molecular weight components having a weight average molecular weight of 250,000 or more in the modified PVA is reduced. The fine pattern formation auxiliary agent containing the modified PVA and the crosslinking agent after the heat treatment is applied onto the resist pattern 3 to form the coating layer 4, and then the resist pattern 3 and the coating layer 4 are heated to thereby form the resist pattern 3. Acid diffuses from the coating into the coating layer. The coating layer in the vicinity of the resist pattern surface is crosslinked and cured by the diffused acid. By developing the coating layer 4, a hole pattern or the like having a cross-linked and hardened layer 5 on the resist pattern surface and having a size not larger than the resolution limit of the exposure wavelength is formed.
[Selection] Figure 1

Description

  The present invention is applied to a photoresist pattern in microfabrication when manufacturing a three-dimensional microstructure such as an electronic component such as a semiconductor or a micromachine, thickens the resist pattern, and has a size less than the limit resolution of the exposure wavelength. It is related with the fine pattern formation adjuvant used with the pattern formation method which can form the resist pattern of this.

  Conventionally, a photolithography method is generally used in microfabrication in the manufacture of electronic parts such as semiconductors and three-dimensional microstructures. In the photolithography method, a positive type or negative type radiation sensitive resin composition is used to form a resist pattern. Among these radiation-sensitive resin compositions, as a positive photoresist, for example, a radiation-sensitive resin composition comprising an alkali-soluble resin and a quinonediazide compound that is a photosensitive substance is widely used.

  By the way, in recent years, with the high integration and high speed of LSI, the fine electronic device manufacturing industry is required to make the design rule finer to a quarter micron or lower. In order to cope with the further miniaturization of such design rules, those that have been conventionally used such as visible light or near ultraviolet light (wavelength 400 to 300 nm) are not sufficient as an exposure light source, and KrF excimer laser (248 nm) or It is necessary to use far ultraviolet rays such as an ArF excimer laser (193 nm), and further, shorter wavelength radiation such as X-rays and electron beams. A lithography process using these exposure light sources has been proposed and put into practical use. is there. In order to cope with the miniaturization of the design rule, a radiation-sensitive resin composition used as a photoresist in fine processing is also required to have a high resolution. Furthermore, in addition to resolution, radiation-sensitive resin compositions are also required to improve performance such as sensitivity and image size accuracy. In order to respond to this, a “chemically amplified radiation-sensitive resin composition” has been proposed as a high-resolution radiation-sensitive resin composition that is sensitive to short-wavelength radiation. This chemically amplified radiation-sensitive resin composition contains a compound that generates an acid upon irradiation with radiation, an acid is generated from this acid-generating compound upon irradiation with radiation, and a catalytic image forming process using the generated acid is performed. Since it is advantageous in that high sensitivity is obtained, it is replacing the conventional radiation-sensitive resin composition and is becoming popular.

  However, the pattern formation by KrF excimer laser (248 nm) has not caught up with the currently desired fine pattern size, and the process by ArF excimer laser (193 nm) has not yet been put into practical use. Therefore, a resist pattern is formed using a chemically amplified resist by a pattern forming process using a KrF excimer laser, and a fine pattern forming auxiliary agent, which is a water-soluble resin composition that is crosslinked and cured by an acid, is applied on the resist pattern to form a water-soluble solution. A water-soluble resin film was formed on the pattern, and the entire surface was exposed and / or heated to diffuse the acid from the resist pattern to the water-soluble resin film, thereby cross-linking and curing the water-soluble resin film and insolubilizing in the developer. After that, the uncured portion is removed by development to thicken the resist pattern, and as a result, the resist pattern is made finer by narrowing the width between the resist patterns, and effectively a fine resist that is less than the resolution limit of the exposure wavelength A fine pattern forming method for forming a pattern has been proposed (for example, Patent Document 1, Patent Document 2, Patent reference 3). This method is attracting attention as a useful method because it can effectively reduce the size of the space portion of the resist pattern without making expensive capital investment such as an exposure apparatus for a short wavelength. The fine pattern forming auxiliary agent comprising the water-soluble resin composition used for forming the fine pattern has already been put on the market as, for example, the RELACS series (manufactured by Clariant).

  The auxiliary agent contains water-soluble or alkali-soluble modified polyvinyl alcohol (hereinafter sometimes simply referred to as “modified polyvinyl alcohol”) protected with a specific protecting group as a component. It is known to produce aggregates. This aggregate is a kind of polymer gel and can be regarded as a solvent swelling body having a three-dimensional network structure in which the whole system is connected by intermolecular hydrogen bonding. Polyvinyl alcohol is a crystalline polymer, and the crosslinking point is considered to be an entanglement point confined between the microcrystals. This aggregate is very strong in an aqueous solution, and may cause problems such as a decrease in filtration rate when a filter having a size of 0.1 μm or less is used, and may cause foreign matter in the coating film. I have a problem. Furthermore, this aggregate also has a problem of stability over time, that is, it is generated again with time even if it is removed.

  Similarly to polyvinyl alcohol, modified polyvinyl alcohol used as a raw material for the fine pattern formation auxiliary agent also contains a high molecular weight component based on association, etc., and has problems in filterability and stability over time, and is formed using this modified polyvinyl alcohol. Further, the fine pattern forming auxiliary has the same problem as described above. Furthermore, the fine pattern formation aid using modified polyvinyl alcohol has a problem that a coating defect occurs when it is applied to the substrate, and the fine pattern formation aid is applied on the resist pattern and cured after exposure, heating, etc. When developing and removing the fine pattern formation auxiliary agent that has not been developed, there is also a problem of pattern development defects due to the unnecessary fine pattern formation auxiliary agent remaining without being removed.

JP-A-5-241348 JP-A-6-250379 Japanese Patent Laid-Open No. 10-73927

  Therefore, the object of the present invention is to be used in semiconductor production etc. in which the above-mentioned problems are improved, that is, the filterability is good, the number of coating defects and development defects is small, and the stability over time is also good. It is to provide an auxiliary agent for forming a fine pattern.

  In view of the above situation, as a result of intensive studies and examinations, the present inventors found that gel permeation chromatography (GPC) contained in the modified polyvinyl alcohol in the fine pattern forming auxiliary agent containing the modified polyvinyl alcohol. When a high molecular weight component having a weight average molecular weight of more than 250,000 calculated by a method and calculated from a polyethylene glycol standard substance is not more than a specific amount, an auxiliary agent having the above preferable characteristics can be obtained. It has been found that the modified polyvinyl alcohol having the above can be obtained by performing a heat treatment after removing impurities from the modified polyvinyl alcohol.

  That is, the present invention is a solution of modified polyvinyl alcohol protected with a protecting group selected from a formal group, an acetal group and a butyral group, after removing the acid content and metal ions of the solution using an ion exchange resin, The amount of a high molecular weight component having a weight average molecular weight of not less than 250,000, which is obtained by a gel permeation chromatography method and is calculated from a polyethylene glycol standard substance, which is produced by heat treatment at a temperature of 80 ° C. or higher is 1000 ppm or less, and Fine pattern containing modified polyvinyl alcohol protected with a protecting group having a metal ion concentration of 1.0 ppm or less and an acid content of 50 ppm or less, a water-soluble crosslinking agent, and water or a mixed solvent of water and a water-soluble organic solvent It relates to a forming aid.

Hereinafter, the present invention will be described in more detail.
In the present invention, examples of the protective group of the modified polyvinyl alcohol protected with a protective group include a formal group, an acetal group, and a butyral group. The modified polyvinyl alcohol protected with these protecting groups is obtained by a gel permeation chromatography (GPC) method and calculated from a polyethylene glycol standard substance (hereinafter simply referred to as “weight average molecular weight by GPC”) 250,000. The above high molecular weight component is required to be 1000 ppm or less with respect to the modified polyvinyl alcohol, and the amount of the high molecular weight component is preferably 100 ppm or less. When the amount of the high molecular weight component having a weight average molecular weight of 250,000 or more by GPC exceeds 1000 ppm, a fine pattern forming auxiliary agent having excellent filterability, coating characteristics, and development characteristics cannot be obtained. Such modified polyvinyl alcohol having a content of a high molecular weight component having a weight average molecular weight of 250,000 or more by GPC in a resin of 1000 ppm or less reacted with a compound that forms a protective group to form a protective group. Later, it can be produced by performing a heat treatment at 80 ° C. or higher, preferably 90 ° C. or higher. Further, in order to obtain a modified polyvinyl alcohol having excellent stability over time, it is necessary to remove impurities in the polymer solution by performing demetallization ion treatment and deoxidation treatment before the heat treatment.

  A modified polyvinyl alcohol protected with a protecting group such as a formal group, an acetal group, or a butyral group, and a production method thereof are all well known. In the present invention, these modified polyvinyl alcohols subjected to heat treatment, deoxidation, and demetallization ion treatment may be produced by any conventionally known method. For example, polyvinyl alcohol having an acetal group as a protective group is produced by dissolving polyvinyl alcohol in water and reacting acetaldehyde in the presence of an acid. A formal group, a butyral group, and the like can also be formed by reacting polyvinyl alcohol with formaldehyde or butyraldehyde by the same method as the method for introducing an acetal group. Since the modified polyvinyl alcohol used in the present invention is required to be water-soluble, the degree of modification such as the degree of acetalization needs to be in an appropriate range so that the modified polyvinyl alcohol after the reaction has water solubility. It is. The same applies to the introduction of other protecting groups. The polyvinyl alcohol used for producing the modified polyvinyl alcohol usually has a polymerization degree of 300 to 2400, preferably 500 to 1000, and a saponification degree of 70 to 99 mol%, preferably 88 to 95 mol%. Some are used.

  The heat treatment conditions in the production of the modified polyvinyl alcohol of the present invention are 80 ° C. or higher, preferably 90 ° C. or higher. When the treatment temperature is less than 80 ° C., the amount of the high molecular weight component of the modified polyvinyl alcohol after the treatment is not sufficiently reduced. This is because, in comparison with the case of the above heat treatment, the application defects, development defects, filtration characteristics, and the like of the auxiliary agent are inferior. The heat treatment time is not particularly limited because it varies depending on the heating temperature, but it is preferably 5 minutes or more, more preferably 15 minutes or more. In addition, the modified polyvinyl alcohol is dissolved in a solvent and subjected to a solution state during the heat treatment. As the solvent, water is usually used and the heat treatment is performed at a concentration of about 5 to 20%.

  Further, the treatment for removing impurities such as acid content and metal ions of the modified polyvinyl alcohol prior to heating can be performed by treating an aqueous solution of the modified polyvinyl alcohol with, for example, an ion exchange resin. Many ion exchange resins used for such deoxidation and demetallization ion treatment are already known. In the present invention, any of these conventionally known or publicly known ion exchange resins may be used for deoxidation and demetallized ion removal treatment. The metal ion concentration and acid content concentration of the modified polyvinyl alcohol after the impurity removal treatment is, for example, preferably 1.0 ppm or less in the former, and 50 ppm or less, preferably 5 ppm or less in the latter.

  The fine pattern forming auxiliary agent of the present invention contains a water-soluble crosslinking agent and a solvent in addition to the modified polyvinyl alcohol thus treated. Any water-soluble crosslinking agent can be used as long as it can crosslink and cure the modified polyvinyl alcohol with an acid to form a film insoluble in the developer. Preferred examples of such a water-soluble crosslinking agent include melamine derivatives, guanamine derivatives, urea derivatives, glycolurils, alkoxyalkylated amino resins, and the like. Among these water-soluble crosslinking agents, examples of melamine derivatives include melamine, methoxymethylated melamine, ethoxymethylated melamine, propoxymethylated melamine, butoxymethylated melamine, hexamethylol melamine and the like. Examples of guanamine derivatives include acetoguanamine, benzoguanamine, methylated benzoguanamine and the like. Furthermore, examples of urea derivatives include urea, monomethylol urea, dimethylol urea, alkoxymethylene urea, N-alkoxymethylene urea, ethylene urea, ethylene urea carboxylic acid and the like.

  On the other hand, examples of alkoxyalkylated amino resins include alkoxyalkylated melamine resins, alkoxyalkylated benzoguanamine resins, and alkoxyalkylated urea resins. Specifically, methoxymethylated melamine resins and ethoxymethylated melamine resins Propoxymethylated melamine resin, butoxymethylated melamine resin, ethoxymethylated benzoguanamine resin, methoxymethylated urea resin, ethoxymethylated urea resin, propoxymethylated urea resin, butoxymethylated urea resin, and the like.

  These water-soluble crosslinking agents can be used alone or in combination of two or more thereof, and the blending amount thereof is 1 to 70 parts by weight, preferably 10 to 33 parts by weight, per 100 parts by weight of the modified polyvinyl alcohol.

As the solvent, water or a mixed solvent of water and a water-soluble organic solvent is used. The water used as the solvent is not particularly limited as long as it is water, and water from which organic impurities and metal ions have been removed by distillation, ion exchange treatment, filter treatment, various adsorption treatments, and the like, for example, pure water is preferable. On the other hand, the water-soluble organic solvent is not particularly limited as long as it is a solvent that dissolves 0.1% by weight or more with respect to water. For example, alcohol such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol (IPA), etc. , Ketones such as acetone, methyl ethyl ketone and 2-heptanone cyclohexanone, esters such as methyl acetate and ethyl acetate, ethylene glycol monoalkyl ethers such as ethylene glycol monomethyl ether and ethylene glycol monoethyl ether, ethylene glycol monomethyl ether acetate , Ethylene glycol monoalkyl ether acetates such as ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether, propylene glycol monoethyl ether Propylene glycol monoalkyl ethers such as propylene glycol monomethyl ether acetate, propylene glycol monoalkyl ether acetates such as propylene glycol monoethyl ether acetate, lactic acid esters such as methyl lactate and ethyl lactate, and aromatic carbonization such as toluene and xylene Examples thereof include hydrogens, amides such as N, N-dimethylacetamide and N-methylpyrrolidone, and lactones such as γ-butyrolactone, and preferable examples include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl lower alcohols _C 1 -C _4, such as alcohols, N, N- dimethylformamide, and dimethyl sulfoxide. These solvents can be used alone or in admixture of two or more. These solvents are used in a range that does not dissolve the resist pattern when the water-soluble resin composition is used.

  In addition, the fine pattern formation aid of the present invention may contain an additive such as a surfactant, if necessary. Examples of the surfactant include Fluorard manufactured by 3M, Nonipol manufactured by Sanyo Kasei Co., Ltd., Megafac manufactured by Dainippon Ink and Chemicals, acetylene alcohols, acetylene glycols, polyethoxylates of acetylene alcohols, and acetylene glycols. Of polyethoxylates.

  The fine pattern formation auxiliary of the present invention is 1 to 30 parts by weight, preferably 2 parts, of modified polyvinyl alcohol subjected to heat treatment or impurity removal treatment and heat treatment per 100 parts by weight of water or a mixture of water and a water-soluble solvent. -15 parts by weight, 0.01 to 10 parts by weight, preferably 0.1 to 5 parts by weight of a water-soluble crosslinking agent.

  The resist pattern to which the fine pattern forming aid of the present invention is applied may be formed by a conventionally known or well-known method. One example will be described with reference to FIGS. 1 (a) and 1 (b). First, as shown in FIG. 1A, a chemically amplified positive radiation-sensitive resin composition is applied onto a substrate to be processed such as a semiconductor substrate 1 and prebaked (for example, baking temperature: The photoresist layer 2 is formed at 70 to 150 ° C. for about 1 minute). Next, after exposure through a photomask (not shown), post-exposure baking (PEB) (for example, baking temperature: 50 to 150 ° C.) is performed if necessary, followed by development. (For example, baking temperature: 60 to 120 ° C.) is performed to form a positive resist pattern 3 as shown in FIG.

  The semiconductor substrate used in the formation of the resist pattern may be a bare semiconductor substrate, but if necessary, a silicon oxide film, a metal film such as aluminum, molybdenum, or chromium on the surface, a metal oxide film such as ITO, polysilicon, etc. A substrate made of silicon or the like having a silicon film, or a substrate on which a circuit pattern or a semiconductor element is formed on these substrates may be used. Further, the chemical amplification type positive radiation sensitive resin composition may be applied by a conventionally known method such as a spin coating method, a roll coating method, a land coating method, a casting coating method, or a dip coating method. As the exposure light source, for example, far ultraviolet rays such as KrF excimer laser and ArF excimer laser, X-rays, electron beams and the like are used. Furthermore, the developer for the photoresist film may be any one that can develop the chemically amplified positive-type radiation-sensitive resin composition to be used. Usually, tetramethylammonium hydroxide, sodium hydroxide, etc. An alkaline aqueous solution is used. The developing method may be a method conventionally used for developing a photoresist, such as a paddle method or a spray method. In addition, the radiation sensitive resin composition should just be a thing by which an acid is diffused from the resist pattern 3 to the coating layer 4 by exposure and / or heating after resist pattern formation, and said chemical amplification type positive radiation sensitive. The resin composition is not limited to this.

  Next, a method of forming a coating layer crosslinked with an acid on the resist pattern, narrowing the distance between the resist patterns, and forming a pattern below the limit resolution of the exposure wavelength is shown in FIGS. 1 (c) to 1 (e). This will be described with reference to FIG. First, as shown in FIG.1 (c), the fine pattern formation adjuvant of this invention is apply | coated on the resist pattern 3, and it bakes as needed (for example, baking temperature: 65-85 degreeC for about 1 minute). Thus, the covering layer 4 is formed. Next, in order to diffuse the acid from the resist pattern 3 into the coating layer 4, exposure and / or baking (for example, baking temperature: 90 to 140 ° C. for about 1 minute) is performed. As a result, the acid diffuses from the resist pattern 3 and a cross-linked / cured layer 5 is formed on the coating layer 4 as shown in FIG. By developing the coating layer 4 with a dedicated developer and removing the coating layer that has not been crosslinked / cured, a pattern thickened by the crosslinked / cured layer 5 is formed as shown in FIG. As a result, the space between the resist patterns is narrowed, and a pattern having a resolution lower than the limit resolution of the exposure wavelength is formed. The formed pattern is used as a fine mask for a substrate such as an etching mask or an ion implantation mask or a resist mask to be processed.

  The present invention will be described in the following examples, but the present invention is not limited to these examples.

Production example (production of acetalized polyvinyl alcohol)
Polyvinyl alcohol (PVA) (manufactured by Nippon Synthetic Chemical Co., Ltd.) having a saponification degree of 88% and a polymerization degree of 500 is acetalized by reacting with acetaldehyde under a hydrochloric acid catalyst, and then neutralized with an aqueous sodium hydroxide solution. Then, a modified PVA (polymer a) having an acetalization rate of 30 mol% was synthesized. Polymer a had a sodium ion content of 28 ppm, an acetate ion content of 1250 ppm, and a chloro ion content of 221 ppm.

Next, in order to remove the metal ions in the polymer a, ion exchange resin Amberlite EG-290 (manufactured by Organo) is used to perform metal removal ion treatment, and then to remove the acid content, the ion exchange resin Amberlyst IRA96SB ( The product was subjected to a deoxidation treatment using a product of Organo to obtain a demetallized ion and a deoxidized modified PVA (polymer A). Polymer A was finally prepared as a 10% strength aqueous solution. The ion exchange treatment reduced the sodium ion content of the modified PVA from 28 ppm to 5 ppb, the acetate ion content from 1250 ppm to 41 ppm, and the chloro ion content from 221 ppm to 1 ppm or less.
Sodium ion was measured by atomic absorption, and acetate ion and chloro ion were measured by ion chromatography.

Example 1
1 kg of a 10% by weight aqueous solution of polymer A was placed in a three-necked flask and heat-treated at 100 ° C. for 180 minutes with an oil bath to obtain polymer B. Measurement of the amount of a high molecular weight component (hereinafter simply referred to as “high molecular weight component”) having a weight average molecular weight of 250,000 or more by GPC and evaluation of filterability of the polymer B were performed as follows. The results are shown in Table 1.

Measurement of polymer high-molecular-weight component amount As a GPC measuring apparatus, LC module-1 (manufactured by Waters) was used, and the columns were SB-800P, SB-804HQ, SB-803HQ, SB-802.5HQ (all Showa Denko Co., Ltd.) was used. The eluent was prepared by adding 1 part by weight of acetonitrile to 9 parts by weight of a 0.1 mol / liter sodium nitrate aqueous solution. The flow rate was 0.8 milliliter (ml) / minute (min), the sample injection volume was 200 microliters (μl), and the column temperature was 40 ° C.
The measurement is performed by dissolving 0.50 g of a 10% by weight aqueous solution of polymer B in 10 ml of an eluent and performing separation according to molecular weight by GPC under the above conditions, and a high molecular weight having a weight average molecular weight of 250,000 or more in terms of polyethylene glycol. This was done by detecting and calibrating body components. The calibration was calculated from the area ratio of the high molecular weight component having a weight average molecular weight of 250,000 or more in terms of polyethylene glycol to the main peak area.

Evaluation of filterability A polytetrafluoroethylene (PTFE) filter (manufactured by Microlith) having a pore diameter of 0.20 μm and a diameter of 13 mm was used, and pressure filtration was performed with 1.4 kgf / cm ^{2 of} nitrogen to obtain 3 of polymer B The change in the filtration rate of the weight% aqueous solution was examined. The filterability was evaluated by measuring and comparing the filtration amount for 1 to 2-3 minutes and the filtration amount for 1 to 9 minutes after the start of filtration, and evaluating the following evaluation criteria.

(Evaluation criteria for filterability)
○: The decrease in the filtration amount for 1 to 10 minutes with respect to the filtration amount for 1 to 2-3 minutes after the start of filtration is 30% or less. X: 9− with respect to the filtration amount for 1 to 2-3 minutes after the start of filtration. More than 30% decrease in filtration volume per tenth

Example 2
1 kg of a 10 wt% aqueous solution of polymer A was placed in a three-necked flask and heat-treated at 100 ° C. for 15 minutes with an oil bath to obtain polymer C. GPC measurement was performed in the same manner as in Example 1 to determine the amount of the high molecular weight component of polymer C. Further, the filterability was evaluated in the same manner as in Example 1. The results are shown in Table 1.

Example 3
1 kg of a 10% by weight aqueous solution of polymer A was placed in a three-necked flask and heat-treated at 80 ° C. for 180 minutes with an oil bath to obtain polymer D. GPC measurement was performed in the same manner as in Example 1, and the amount of the high molecular weight component of polymer D was determined. Moreover, the filterability of the polymer D was evaluated in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 1
GPC measurement of the polymer A obtained in the production example was performed in the same manner as in Example 1, and the amount of the high molecular weight component of the polymer A was determined. In addition, the filterability of the polymer A was evaluated in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 2
1 kg of a 10% by weight aqueous solution of polymer A was placed in a three-necked flask and heat-treated at 60 ° C. for 180 minutes with an oil bath to obtain polymer E. GPC measurement was performed in the same manner as in Example 1 to determine the amount of the high molecular weight component of polymer E. Further, the filterability of the polymer E was evaluated in the same manner as in Example 1. The results are shown in Table 1.

  From Table 1, when the modified PVA is heat-treated at a temperature of 80 ° C. or higher, the amount of the high molecular weight component in the polymer is greatly reduced, and the modified PVA of the present invention having a small amount of high molecular weight component also has filterability. It turns out to be very good.

Example 4
(Preparation of fine pattern formation aid)
100 parts by weight of the polymer B obtained in Example 1 and 19 parts by weight of a water-soluble crosslinking agent for urea derivatives were mixed with a mixed solvent of pure water and isopropyl alcohol which is a water-soluble organic solvent (for 95 parts by weight of pure water, (5 parts by weight of isopropyl alcohol) was dissolved in 1470 parts by weight to prepare a fine pattern formation aid B (Composition B).
Next, the composition B was subjected to the following “defect inspection after coating” and “defect inspection after development”.

(Defect inspection after application)
Composition B was spin-coated on an 8-inch bare silicon wafer and baked on a direct hot plate at 85 ° C. for 70 seconds to form a 0.35 μm thick film. The coating film was inspected for defects by a surface defect inspection meter (KLA-2115 manufactured by KLA Tencor). Evaluation of the number of defects after coating was based on the total number of coating defects on the wafer. The results are shown in Table 2.

(Defect test after development)
AZ KrF-17B80 (manufactured by Clariant, “AZ” is a registered trademark (hereinafter the same)) was spin-coated on an 8-inch bare silicon wafer, baked on a direct hot plate at 180 ° C. for 60 seconds, An antireflection film having a thickness of 0.080 μm was formed. Further, AZ DX5240P (7 cP) (manufactured by Clariant) was applied by spin coating and baked by a direct hot plate at 90 ° C. for 60 seconds to form a resist film having a thickness of 0.450 μm. This resist film was selectively exposed through a binary mask with 248.4 nm KrF excimer laser light, post exposure bake (PEB) on a direct hot plate at 120 ° C. for 60 seconds, and then AZ 300MIF (Clariant) as a developer. A hole pattern was formed on the silicon wafer by paddle development for 60 seconds using a 2.38 wt% tetramethylammonium hydroxide aqueous solution). Composition B was spin-coated on the hole pattern, and baked on a direct hot plate at 85 ° C. for 70 seconds to form a 0.350 μm film. Next, in order to promote the cross-linking reaction at the interface between the resist layer and the fine pattern formation auxiliary agent, after baking at 110 ° C. for 70 seconds with a direct hot plate (mixing baking), AZ R2 developer (manufactured by Clariant) A fine pattern was formed by developing with running water for 60 seconds. Using a surface defect inspection meter (KLA-2115 manufactured by KLA Tencor), defect inspection measurement after development was performed. Evaluation of the number of defects after development is based on the case where a bridge or the like is formed in the hole pattern after development and the hole pattern is clearly removed and not developed, and the number of defects on the wafer is calculated after development. The number of defects. The results are shown in Table 2.

Example 5
A fine pattern formation aid C (Composition C) was prepared in the same manner as in Example 4 except that the polymer C obtained in Example 2 was used in place of the polymer B. In the same manner as in Example 4, “defect inspection after application” and “defect inspection after development” of composition C were performed. The results are shown in Table 2.

Example 6
A fine pattern formation aid D (Composition D) was prepared in the same manner as in Example 4 except that the polymer D obtained in Example 3 was used instead of the polymer B. In the same manner as in Example 4, “defect inspection after application” and “defect inspection after development” of composition D were performed. The results are shown in Table 2.

Comparative Example 3
In place of polymer B, fine pattern formation auxiliary agent A (composition A) was prepared in the same manner as in Example 4 except that polymer A which was not heat-treated obtained in Production Example was used. In the same manner as in Example 4, composition A “defect inspection after application” and “defect inspection after development” were performed. The results are shown in Table 2.

Comparative Example 4
A fine pattern formation auxiliary E (composition E) was prepared in the same manner as in Example 4 except that the polymer E obtained in Comparative Example 2 was used in place of the polymer B. In the same manner as in Example 4, “defect inspection after application” and “defect inspection after development” of composition E were performed. The results are shown in Table 2.

  From Table 2, in the fine pattern formation adjuvant of the present invention prepared using a modified PVA having a very small amount of high molecular weight component, heat treatment is not performed, or appropriate heat treatment is not performed. Compared to the fine pattern formation auxiliary using modified PVA whose body component amount exceeds 1000 ppm, the number of coating defects and development defects during coating and pattern formation is greatly improved, and the fine pattern formation auxiliary of the present invention is extremely It turns out that it has the outstanding characteristic.

(Stability evaluation over time)
Example 7
The polymer B was stored at room temperature (25 ° C.) and at a low temperature (5 ° C.), and after 2 weeks and 1 month, the amount of high molecular weight components was measured again by GPC. The results are shown in Table 3.

Comparative Example 5
1 kg of a 10% by weight aqueous solution of polymer a in Production Example that was not subjected to ion exchange treatment was placed in a three-necked flask and heat-treated at 100 ° C. for 180 minutes in an oil bath to obtain polymer F. When the amount of the high molecular weight component of the polymer F was measured by GPC in the same manner as in Example 1, it was a favorable result of 100 ppm or less. Polymer F was stored at room temperature (25 ° C.) and at a low temperature (5 ° C.), and after 2 weeks and 1 month, the amount of high molecular weight components was measured again by GPC. The results are shown in Table 3.

  It can be seen from Table 3 that modified polyvinyl alcohol having excellent stability over time can be supplied by performing the impurity removal step.

[The invention's effect]
As described above in detail, according to the present invention, a fine pattern formation auxiliary agent having excellent characteristics with good filterability and few defects during coating or pattern formation, a raw material polymer thereof, and production of the raw material polymer Law is provided. Furthermore, according to the present invention, it is possible to provide a fine pattern forming auxiliary agent having excellent temporal stability, a raw material polymer thereof, and a method for producing the raw material polymer. As a result, in microfabrication for manufacturing electronic parts such as semiconductors and three-dimensional microstructures, patterns with a size below the resolution limit of the exposure wavelength are formed with high accuracy and high throughput according to the design rules as designed. be able to.

It is explanatory drawing explaining the process of forming the resist pattern which thickens a resist pattern using a fine pattern formation adjuvant, narrows the size between resist patterns, and has a pattern dimension width below a resolution limit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 Photoresist layer 3 Resist pattern 4 Coating layer with fine pattern formation auxiliary agent 5 Insoluble cross-linked / cured layer in developer

Claims (1)

  After removing the acid content and metal ions of the modified polyvinyl alcohol protected with a protecting group selected from a formal group, an acetal group and a butyral group using an ion exchange resin, at a temperature of 80 ° C. or higher. The amount of the high molecular weight component having a weight average molecular weight of 250,000 or more calculated by the gel permeation chromatography method and calculated from the polyethylene glycol standard substance produced by heat treatment is 1000 ppm or less and the metal ion concentration is 1. A fine pattern formation auxiliary agent containing a modified polyvinyl alcohol protected with a protecting group having an acid content of 0 ppm or less and a water-soluble crosslinking agent, and water or a mixed solvent of water and a water-soluble organic solvent.

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