JP2008166475A - Resist pattern miniaturization material and method for forming micro resist pattern - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exposure device and a resist pattern miniaturization material capable of forming a micropattern transcending a limit caused by wavelength, and to provide a method for forming a micro resist pattern using them. <P>SOLUTION: The resist pattern miniaturization material is the material applied on the resist pattern formed by exposing and developing a photoresist film and miniaturizing the resist pattern by developing after the heat treatment, a liquid including alcohol of a straight-chain or forked alkyl group having one to twelve (12) carbon number filtered by a filter having a hole diameter of not more than 40 nm, and includes an interfacial active agent and/or water. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a resist pattern reducing material used for reducing a line width of a pattern in a resist pattern forming stage in a semiconductor process, and a fine resist pattern forming method using the resist pattern reducing material.

Along with the high integration of semiconductor devices, miniaturization of wiring, specifically reduction of the line width of wiring, is increasingly required in the manufacturing process. Conventionally, a fine pattern is formed by forming a resist pattern on the surface of a substrate such as a silicon wafer on which various thin films are deposited by photolithography, and then etching the underlying thin film using the resist pattern as a mask. It is done by.
For this reason, the photolithography technique is very important in forming a fine pattern. The photolithography technique is composed of resist coating, mask alignment, exposure, and development. For miniaturization, it is effective to shorten the exposure wavelength. However, there is a problem that the renewal of the exposure apparatus accompanying this requires a large amount of cost, and a resist material corresponding to a shorter wavelength is not immediately supplied. Also, there is a limit to shortening the exposure wavelength itself.

Conventionally, a resist pattern reducing material containing an acidic water-soluble resin, and a line width of a positive chemically amplified resist pattern using this resist pattern reducing material are reduced, and the fineness exceeds the limit of the exposure apparatus and wavelength. A method for forming a resist pattern is known (Patent Document 1).
However, this reducing material and fine resist pattern forming method must prepare an acidic water-soluble resin, and the reducing material and the forming method are insufficient when a pattern having a line width of 40 nm or less is to be formed. There is a problem that.
JP 2001-281886 A

  The present invention has been made to address such problems, and provides a resist pattern reducing material capable of forming a fine pattern exceeding the limit due to the exposure apparatus and wavelength, and a fine resist pattern forming method using the same. With the goal.

The resist pattern reducing material of the present invention is applied to a resist pattern formed by exposing and developing a photoresist film, and the resist pattern reducing material for making the resist pattern finer by developing after heat treatment The resist pattern reducing material is an organic liquid containing a linear or branched alkyl group alcohol having 1 to 12 carbon atoms filtered through a filter having a pore diameter of 40 nm or less.
The alcohol is characterized by containing 70% by mass or more when the entire resist reducing material is 100% by mass.
Further, the resist pattern reducing material further contains a surfactant. This surfactant is characterized by being 5% by mass or less when the entire resist pattern reducing material is 100% by mass.
The resist pattern reducing material further contains water.

In the fine resist pattern forming method of the present invention, a photoresist film is exposed and developed to form a resist pattern, a resist pattern reducing material composed of an organic solvent is applied to the resist pattern, heat-treated, and an alkaline developer. It is characterized by developing.
Further, the resist pattern reducing material is the resist pattern reducing material according to the present invention.

Since the resist pattern reducing material of the present invention contains a linear or branched alkyl group alcohol having 1 to 12 carbon atoms filtered through a filter having a pore diameter of 40 nm, it can be easily applied onto the resist pattern. The pattern collapse after reduction is less likely to occur, and the LWR (Line Width Roughness) is also small.
In the fine resist pattern forming method of the present invention, a resist pattern is formed using the resist pattern reducing material, and therefore a fine resist pattern exceeding the limit of the exposure apparatus and wavelength can be formed.

As a result of intensive research on materials that can smoothly solubilize the resist pattern surface layer by heat treatment and can be easily removed by subsequent alkaline aqueous solution treatment, the above-mentioned specific alcohol is obtained. It was found that a reduced pattern can be formed efficiently.
That is, when the resist pattern reducing material of the present invention is applied to a patterned resist, a predetermined alcohol permeates into the resist pattern surface layer, so that an acid generator in the resist or an acid generated during pattern formation forms a pattern. It is considered that the acid dissociable group, which is a protective group for the pattern surface layer, is cut by heat when moved to the surface layer, the pattern surface layer becomes alkali-soluble again, and the pattern is reduced by development. The present invention has been completed based on this finding.

The alcohol used for the resist pattern reducing material may be any alcohol that does not cause intermixing with the photoresist film when applied onto the photoresist film.
Such an alcohol is preferably a linear or branched alkyl alcohol having 1 to 12 carbon atoms, preferably 1 to 8 carbon atoms. Examples of the alcohol having 1 to 12 carbon atoms include 1-propanol, isopropanol, 1-butanol, 2-butanol, t-butanol, 1-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1 -Butanol, 3-methyl-1-butanol, 3-methyl-2-butanol, 1-hexanol, 2-hexanol, 3-hexanol, 2-methyl-1-pentanol, 2-methyl-2-pentanol, 2 -Methyl-3-pentanol, 3-methyl-1-pentanol, 3-methyl-2-pentanol, 3-methyl-3-pentanol, 4-methyl-1-pentanol, 4-methyl-2- Examples include pentanol, 1-heptanol, 2-heptanol, 2-methyl-2-heptanol, and 2-methyl-3-heptanol. .
Among these alcohols, 1-butanol and 2-butanol are preferable.
The said alcohol can be used individually or in combination of 2 or more types.

  The blending ratio of the alcohol is 70% by mass or more, preferably 90% by mass or more, and more preferably 100% by mass in the total resist pattern reducing material. If it is less than 70% by mass, problems such as alcohol applicability and poor permeability may occur, and the line width reduction degree may be reduced.

The resist pattern reducing material of the present invention may be mixed with another solvent for the purpose of adjusting the coating property when applied on the photoresist film. The other solvent acts to uniformly apply the resist pattern reducing material without eroding the photoresist film.
Other solvents include cyclic ethers such as tetrahydrofuran and dioxane; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether Alkyl ethers of polyhydric alcohols such as diethylene glycol ethyl methyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether; ethylene glycol ethyl ether acetate, diethylene glycol ethyl ether acetate, propylene glycol ethyl ether acetate And alkyl ether acetates of polyhydric alcohols such as propylene glycol monomethyl ether acetate; aromatic hydrocarbons such as toluene and xylene; acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, 4-hydroxy-4-methyl-2-pentanone , Ketones such as diacetone alcohol; ethyl acetate, butyl acetate, ethyl 2-hydroxypropionate, ethyl 2-hydroxy-2-methylpropionate, ethyl ethoxyacetate, ethyl hydroxyacetate, 2-hydroxy-3-methylbutanoic acid And esters such as methyl, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, ethyl 3-ethoxypropionate, methyl 3-ethoxypropionate, ethyl acetate, butyl acetate .
Among these, cyclic ethers, alkyl ethers of polyhydric alcohols, alkyl ether acetates of polyhydric alcohols, ketones, and esters are preferable.

  The blending ratio of the other solvent is less than 30% by mass, preferably 20% by mass or less, based on the total resist pattern reducing material. If it is 30% by mass or more, problems such as erosion of the photoresist film may occur, and the resist pattern shape may be significantly degraded.

  In the resist pattern reducing material of the present invention, optional additives such as a surfactant and a pH adjuster can be blended as necessary. These are used as long as the object and effect of the present invention are not impaired.

In the resist pattern reducing material of the present invention, a surfactant can be blended for the purpose of improving coating properties, antifoaming properties, leveling properties and the like.
Examples of such surfactants include BM-1000, BM-1100 (above, manufactured by BM Chemie), MegaFuck F142D, F172, F173, F183 (above, manufactured by Dainippon Ink & Chemicals, Inc.). ), FLORARD FC-135, FC-170C, FC-430, FC-431 (above, manufactured by Sumitomo 3M), Surflon S-112, S-113, S-131, S- 141, S-145 (made by Asahi Glass Co., Ltd.), SH-28PA, -190, -193, SZ-6032, SF-8428 (above, made by Toray Dow Corning Silicone) Fluorosurfactants marketed by name can be used.
The compounding amount of these surfactants is 5% by mass or less based on the total resist pattern reducing material.

Water can be blended in the resist pattern reducing material of the present invention.
The water is preferably pure water or ultrapure water used for semiconductor production.
The blending amount of water is 10% by mass or less in the total resist pattern reducing material.

The resist pattern reducing material of the present invention can be used as the above-mentioned alcohol alone solvent. Moreover, it can be used as a mixed solvent of the alcohol and at least one selected from the other solvents, surfactants, and water.
The resist pattern reducing material is used after being filtered through a filter having a pore diameter of 20 nm to 40 nm. Examples of the filter include an HDPE filter (pore size 30 nm or 40 nm) manufactured by Nippon Pole. The filtration method is not particularly limited, but is preferably a circulation filtration method.

Using the resist pattern reducing material, a reduced pattern can be formed by the following method.
(1) Step of forming resist pattern by exposure and development of photoresist film An antireflection film (organic film or inorganic film) is formed on an 8-inch or 12-inch silicon wafer substrate by a conventionally known method such as spin coating. Next, a photoresist is applied by a conventionally known method such as spin coating, and prebaking (PB) is performed under conditions of, for example, about 80 ° C. to 140 ° C. and about 60 to 120 seconds. Since the present invention is a reduced pattern forming method suitable as a method for forming a pattern of 40 nm or less, the photoresist is a positive for ArF comprising a combination of an alicyclic radiation-sensitive resin composition and an acid generator. Type photoresist is preferred. Then, exposure with ultraviolet rays such as g-line and i-line, KrF excimer laser beam, ArF excimer laser beam, X-ray, electron beam, etc., for example, post-exposure baking (PEB) under conditions of about 80 ° C to 140 ° C Then, development is performed to form a resist pattern.

(2) Step of applying and heat-treating resist pattern reducing material The resist pattern reducing material is applied to the substrate on which the resist pattern is formed by a conventionally known method such as spin coating.
Next, a resist pattern reducing material is applied onto the resist pattern, and the substrate having the pattern surface layer infiltrated with the alcohol is heat-treated. By the heat treatment, the acid derived from the photoresist diffuses from the interface with the photoresist to the surface layer where the resist pattern reducing material is applied and penetrated, and is converted into an alkali solubilized layer. The alkali solubilized layer of the photoresist surface layer is determined by the type of resist pattern reducing material, the type of photoresist used, the baking temperature, the baking time, and the like.
The heat treatment temperature and heat treatment time are usually about 90 ° C. to 180 ° C. and about 60 to 120 seconds.

(3) Step of developing with alkali developer Next, the pattern after the heat treatment is developed with an alkali developer such as an aqueous alkali solution such as tetramethylammonium hydroxide (TMAH) (for example, about 60 to 120 seconds), The alkali solubilized layer is dissolved and removed. Finally, the line pattern or the like can be reduced by washing with water.
The fine pattern forming method of the present invention is suitable for forming a fine pattern of 40 nm or less exceeding the limit due to the ArF exposure apparatus and its wavelength. Therefore, if the resist pattern before the reduction is the minimum pattern, the line / space pattern after the reduction is a fine pattern of 1 / 1.2 or more.

  Examples of the alkali developer include alkali metal salts such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium oxalate, sodium metasuccinate; ammonia water; ethylamine, n-propylamine, diethylamine, di-n-propylamine. Alkylamines such as triethylamine and methyldiethylamine; alkanolamines such as dimethylethanolamine and triethanolamine; heterocyclic amines such as pyrrole and piperidine; tetraalkylammonium such as tetramethylammonium hydroxide and tetraethylammonium hydroxide Ammonium hydroxide; dissolves one or more alkaline compounds such as choline, 1,8-diazabicyclo [5.4.0] -7-undecene, 1,5-diazabicyclo [4.3.0] -5-nonene Alkaline aqueous solution is used. A particularly preferred alkaline developer is an aqueous solution of tetraalkylammonium hydroxides. In addition, an appropriate amount of a water-soluble organic solvent such as methanol or ethanol, a surfactant, or the like can be added to the developer composed of the alkaline aqueous solution.

EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated further more concretely, this invention is not restrict | limited at all to these Examples, unless the summary is exceeded.
In order to evaluate the resist pattern reducing material, an evaluation substrate with a resist pattern was produced by the following method.
After forming a coating film with a film thickness of 77 nm (PB205 ° C., 60 seconds) on a 8-inch silicon wafer by spin coating a lower antireflection film ARC29A (Brewer Science Co., Ltd.) with CLEAN TRACK ACT8 (Tokyo Electron Ltd.), Patterning of JSR ArF AR2014J (manufactured by JSR Corporation, alicyclic radiation-sensitive resin composition) is performed. AR2014J was applied by spin coating (CLEAN TRACK ACT8) and PB (115 ° C., 90 seconds) to a film thickness of 1500 nm. ArF projection exposure apparatus S306C (Nikon Corporation), NA: 0.78, sigma: 0.00. 85, 2/3 Ann exposure (exposure 30mJ / cm ² ), PEB (115 ° C, 90 seconds) with CLEAN TRACK ACT8 hot plate, and LD nozzle of CLEAN TRACK ACT8 Paddle development (60 seconds), rinsing with ultrapure water, followed by spin drying at 4000 rpm for 15 seconds to obtain an evaluation substrate. The substrate obtained in this step is referred to as an evaluation substrate A. A plurality of evaluation substrates A prepared under the same conditions were prepared.
The obtained evaluation substrate was measured with a scanning electron microscope (S-9380, manufactured by Hitachi Sokki Co., Ltd.) to obtain an isolated line pattern having a line width of 40 nm.

In the examples shown in Table 1, the evaluation substrate with a resist pattern was evaluated for the resist pattern reducing material by the following method. Each evaluation result is shown in Table 1.
(1) Line width reduction degree After processing, the dimension of the resist pattern whose line width was 40 nm before application | coating of resist pattern reduction material was measured with the said scanning electron microscope, and the line width reduction degree was measured.

Line width reduction = Line width before processing (40 nm) −Line width after processing (unit, nm)

(2) LWR (Line Width Roughness)
Before processing the resist pattern reducing material, the dimension of the resist pattern whose line width was 40 nm was processed, and then measured in the LWR measurement mode of the scanning electron microscope. FIG. 1 is a schematic diagram showing a plan view of a line pattern (however, the unevenness is exaggerated from the actual state). The line width was measured from W1 to W32 at equal intervals between the vertical axis of the line patterns (measurement range 1000 nm), and the 3σ values of the line widths at the 32 locations were measured. This was measured with 10 different line patterns, and the average value of these 10 3σ values was defined as LWR.

LWR = {first line pattern (3σ value) + second line pattern (3σ value) +... 10th line pattern (3σ value)} / 10

Examples 1 to 3
1-Butanol was filtered through a filter having a pore diameter of 30 nm to prepare an organic liquid as a resist pattern reducing material. This is S-1. The performance of the resist pattern reducing material was evaluated using S-1. At this time, after S-1 was applied, the resist pattern was heated with a hot plate for 60 seconds and then developed. The evaluation results are shown in Table 1.

Example 4 to Example 6
2-Butanol was filtered through a filter having a pore diameter of 30 nm to prepare a resist pattern reducing material. This is S-2. The performance of the resist pattern reducing material was evaluated using S-2. At this time, after S-2 was applied, the resist pattern was heated with a hot plate for 60 seconds and then developed. The evaluation results are shown in Table 1.

Example 7
1-Pentanol was filtered through a filter having a pore diameter of 30 nm to prepare a resist pattern reducing material. This is S-3. The performance of the resist pattern reducing material was evaluated using S-3. At this time, after S-3 was applied, the resist pattern was heated with a hot plate for 60 seconds and then developed. The evaluation results are shown in Table 1.

Example 8
1-Hexanol was filtered through a filter having a pore diameter of 30 nm to prepare a resist pattern reducing material. This is S-4. The performance of the resist pattern reducing material was evaluated using S-4. At this time, after S-4 was applied, the resist pattern was heated with a hot plate for 60 seconds and then developed. The evaluation results are shown in Table 1.

Example 9
1-heptanol was filtered through a filter having a pore diameter of 30 nm to prepare a resist pattern reducing material. This is designated as S-5. The performance of the resist pattern reducing material was evaluated using S-5. At this time, after S-5 was applied, the resist pattern was heated with a hot plate for 60 seconds and then developed. The evaluation results are shown in Table 1.

Example 10
Propylene glycol monoethyl ether was added to 1-butanol in an amount of 5.0% by mass and dissolved, followed by filtration with a filter having a pore diameter of 30 nm to prepare a resist pattern reducing material. This is S-6. The performance of the resist pattern reducing material was evaluated using S-6. At this time, after S-6 was applied, the resist pattern was heated with a hot plate for 60 seconds and then developed. The evaluation results are shown in Table 1.

Example 11
0.5% by mass of Megafac F142D was added to 1-butanol and dissolved, followed by filtration with a filter having a pore diameter of 30 nm to prepare a resist pattern reducing material. This is designated as S-7. The performance of the resist pattern reducing material was evaluated using S-7. At this time, after S-7 was applied, the resist pattern was heated with a hot plate for 60 seconds and then developed. The evaluation results are shown in Table 1.

Example 12
Water was added to 1-butanol in an amount of 5.0% by mass, dissolved, and filtered through a filter having a pore size of 30 nm to prepare a resist pattern reducing material. This is designated as S-8. The performance of the resist pattern reducing material was evaluated using S-8. At this time, after S-8 was applied, the resist pattern was heated with a hot plate for 60 seconds and then developed. The evaluation results are shown in Table 1.

Comparative Example 1
As an example in which the resist pattern reducing material was not used, only development of the resist pattern was performed. The evaluation results are shown in Table 1.

Comparative Example 2
As an example not using the resist pattern reducing material, the resist pattern was heated with a hot plate for 60 seconds, and then only the development of the resist pattern was performed. The evaluation results are shown in Table 1.

  The resist pattern reducing material of the present invention can reduce the resist pattern effectively and accurately, and can form a pattern that exceeds the wavelength limit in a favorable and economical manner. It can be used very suitably in the field of microfabrication represented by the production of integrated circuit elements.

It is a schematic diagram which shows a line pattern.

Explanation of symbols

  W1-W32 measurement line width

Claims (7)

A resist pattern reducing material for applying a photoresist film on a resist pattern formed by exposure and development, and developing the resist pattern after heat treatment to make it finer,
The resist pattern reducing material is an organic liquid containing a linear or branched alkyl group alcohol having 1 to 12 carbon atoms filtered through a filter having a pore size of 40 nm or less.   2. The resist pattern reducing material according to claim 1, wherein the alcohol is contained in an amount of 70% by mass or more when the entire resist reducing material is 100% by mass.   The resist pattern reducing material according to claim 1, wherein the resist pattern reducing material further contains a surfactant.   4. The resist pattern reducing material according to claim 3, wherein the surfactant is 5% by mass or less when the entire resist pattern reducing material is 100% by mass.   The resist pattern reducing material according to claim 1, wherein the resist pattern reducing material further contains water. Form a resist pattern by exposing and developing the photoresist film,
Applying a resist pattern reducing material made of an organic solvent to the resist pattern, heat-treating,
A method for forming a fine resist pattern, comprising developing with an alkali developer. Form a resist pattern by exposing and developing the photoresist film,
A method for forming a fine resist pattern, wherein the resist pattern reducing material according to any one of claims 1 to 5 is applied to the resist pattern, heat-treated, and developed with an alkali developer.

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