JP2010026073A - Coating agent for pattern miniaturization and fine pattern forming method using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating agent for pattern miniaturization meeting the demand for further miniaturization of a semiconductor device in recent years, and to provide a fine pattern forming method using the same. <P>SOLUTION: The coating agent containing water-soluble peptide, preferably water-soluble collagen peptide is used as the coating agent for pattern miniaturization used to coat a photoresist pattern formed on a substrate so as to form a fine pattern. The coating agent has a large narrowing amount and ensures small temperature dependency in pattern narrowing and small density distribution dependency of pattern spacing. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pattern miniaturization coating agent and a fine pattern forming method using the same, which can cope with, for example, miniaturization of a resist pattern in the field of lithography technology.

  In recent years, the trend toward higher integration and miniaturization of semiconductor devices has increased, and ultrafine processing has also been required for the formation of resist patterns. Actinic rays used for resist pattern formation use short-wavelength irradiation light such as KrF, ArF excimer laser light, EB, EUV, and soft X-ray, and the resist material also has physical properties corresponding to these irradiation light. Research and development of materials systems with

  As one of the methods for refining the resist pattern, a method of narrowing the pattern width by coating the resist pattern with a coating agent is known. For example, in Patent Document 1 below, a resist pattern containing an acid generator is covered with a material containing a material that crosslinks in the presence of an acid, and an acid is generated in the resist pattern by subsequent heating or exposure treatment. A method for narrowing the pattern width is disclosed by forming a resist pattern coating layer on the cross-linked layer formed in (1).

  In Patent Document 2 below, a resist pattern is coated with a predetermined water-soluble resin and then heat-treated to narrow the pattern width by utilizing the shrinkage of the water-soluble resin, and then the water-soluble resin is removed. A method is disclosed.

Japanese Patent Laid-Open No. 10-073927 JP 2003-084459 A

  However, the method of Patent Document 1 has a problem that the thermal dependency of the coating layer is large, and the variation in pattern width after the miniaturization process is noticeable. In addition, it is difficult to suppress the occurrence of defects (pattern defects) after the miniaturization process.

  The method of Patent Document 2 is a coating for pattern miniaturization that can overcome the problems of Patent Document 1, but in recent years there has been a demand for further narrowing of the pattern width, and a material that can cope with this has been demanded. It was.

  The present invention has been made in view of the above problems, and its object is to provide a coating for pattern miniaturization capable of meeting the recent demand for further miniaturization of resist patterns, and a micropattern forming method using the same. It is to provide.

  In order to solve the above-mentioned problems, the present invention is a pattern miniaturization coating agent used for coating a photoresist pattern formed on a substrate and forming a fine pattern, which contains a water-soluble peptide. A coating for pattern miniaturization is provided.

  Further, in the present invention, after the photoresist pattern formed on the substrate is coated with the above-described coating for pattern miniaturization, the coating for pattern miniaturization is thermally contracted by heat treatment at 60 ° C. or more and 250 ° C. or less, Next, a method for forming a fine pattern including the step of removing the coating agent for pattern refinement is provided.

  According to the pattern refinement coating material and the forming method of the present invention, a defect is not generated after processing, and a large narrowing amount (= resist pattern width before processing−resist pattern after processing) compared to the conventional coating material. Width) can be easily obtained.

  Further, since the temperature dependency and the pattern density dependency are small when the pattern width is narrowed, a stable pattern width can be obtained. Furthermore, the resist pattern has an excellent effect that the shape of the top portion and the bottom portion of the resist pattern is less likely to cause a shape change such as slightly rounding (rounding).

≪Pattern forming agent for pattern refinement≫
The pattern refinement coating agent of the present invention (hereinafter simply referred to as “coating agent”) is composed of an aqueous solution containing a water-soluble peptide.

<Water-soluble peptide>
The water-soluble peptide is not particularly limited as long as it is a peptide that is highly soluble in water at room temperature and does not easily gel at low temperatures. The mass average molecular weight of the water-soluble peptide is preferably 10,000 or less, more preferably 5000 or less. When the mass average molecular weight is 10,000 or less, the solubility in water is high and the gelation is difficult even at a low temperature, so that the stability of the solution is increased. The lower limit of the mass average molecular weight is more preferably 500 or more. The water-soluble peptide may be derived from a natural product or a synthetic product. Further, it may be a derivative of a water-soluble peptide.

  Examples of the water-soluble peptide include collagen-derived hydrolyzed peptide, silk protein-derived hydrolyzed peptide, soybean protein-derived hydrolyzed peptide, wheat protein-derived hydrolyzed peptide, rice protein-derived hydrolyzed peptide, sesame protein-derived Hydrolyzed peptides, pea protein-derived hydrolyzed peptides, wool protein-derived hydrolyzed peptides, casein-derived hydrolyzed peptides, and the like.

  It is preferable that at least a part of the water-soluble peptide of the present invention can form a triple helical structure. Whether or not at least a part of the water-soluble peptide has a triple helical structure can be specified in a circular dichroism spectrum (see, for example, JP-A No. 2003-321500). Since at least a part of the water-soluble peptide has a triple helical structure, the water retention effect is high, so that a film retaining moisture is formed. If the triple helical structure is broken by heating, water molecules cannot be adsorbed in the film. Further, the moisture held in the film is volatilized by heating. As a result, it is estimated that the volume decreases and shrinks, thereby contributing to the narrowing of the pattern width. In addition, due to this triple helical structure, it is presumed that the film-forming agent of the present invention has almost no change in the amount of heat shrinkage due to the heat treatment temperature, and the pattern density dependence is extremely small.

  The water-soluble peptide of the present invention is preferably a water-soluble collagen peptide. Collagen is a kind of protein constituting the dermis, ligament, tendon, bone, cartilage and the like, and is the main component of the extracellular substance of multicellular animals. The amino acids constituting the peptide chain of the collagen protein have a primary structure of-(glycine)-(amino acid X)-(amino acid Y)-and glycine repeating every 3 residues. Since this collagen molecule has an elongated rod-like shape, it can take about four times as much surface area as a sphere having the same volume. Therefore, since the water retention effect before heat treatment is high, it is estimated that a large volume difference from that after heat treatment contributes to narrowing of the pattern width.

  As the water-soluble collagen peptide, either natural collagen or synthetic collagen can be used. Examples of natural collagen include hydrolyzed collagen composed of cow skin / pig skin derived gelatin, hydroxypropyltrimonium hydrolyzed collagen, cocodimonium hydroxypropyl hydrolyzed collagen, (dihydroxymethylsilylpropoxy) hydroxypropyl hydrolyzed collagen, Cocoyl hydrolyzed collagen K, cocoyl hydrolyzed collagen K, cocoyl hydrolyzed collagen Na, cocoyl hydrolyzed collagen TEA, undecylenoyl hydrolyzed collagen K, isostearoyl hydrolyzed collagen AMPD, isostearoyl hydrolyzed collagen, rosin hydrolyzed collagen AMPD, rosin Hydrolyzed collagen and the like, hydrolyzed collagen composed of fish skin-derived gelatin, and cocoyl hydrolysate composed of fish scales Collagen K, Isostearoyl hydrolyzed collagen AMPD, Isostearoyl hydrolyzed collagen, (dihydroxy methyl silyl propoxy) hydroxypropyl hydrolyzed collagen, and the like.

  The synthetic collagen is not particularly limited, and examples thereof include synthetic collagen described in JP2003-321500, JP2005-60550, JP2007-223981, JP2007-262087, and the like. The collagen in the present invention includes a “collagen-like” substance as described in the above publication.

  As a thermal property of the water-soluble peptide, it is preferable that a triple helical structure is formed when the coating film is formed. Thereby, it is possible to prevent deterioration of the shape such that the top and bottom portions of the resist pattern are slightly rounded (rounded) after the miniaturization process. Further, there is no problem that the amount of miniaturization of the resist fluctuates due to fluctuations in the heating temperature, and the amount of thermal shrinkage of the coating becomes constant, so that the pattern width can be reduced at low temperatures.

  Moreover, in this invention, you may mix | blend the following surfactant and antiseptic | preservative with respect to a coating material in the range which does not impair the effect of this invention as needed. Examples of such optionally added components include the following.

<Surfactant>
The surfactant needs to have properties such as high solubility in the water-soluble peptide and no suspension. By using a surfactant that satisfies these characteristics, it is possible to suppress the generation of bubbles (microfoam), particularly when applying a coating, and to prevent the occurrence of defects that are related to the occurrence of microfoam. It can be effectively prevented.

  From the above points, N-hexyl-2-pyrrolidone, N-heptyl-2-pyrrolidone, N-octyl-2-pyrrolidone, N-nonyl-2-pyrrolidone, N-decyl-2-pyrrolidone, N-decyl-2 -Pyrrolidone, N-undecyl-2-pyrrolidone, N-dodecyl-2-pyrrolidone, N-tridecyl-2-pyrrolidone, N-tetradecyl-2-pyrrolidone, N-pentadecyl-2-pyrrolidone, N-hexadecyl-2-pyrrolidone N-alkylpyrrolidone surfactants such as N-heptadecyl-2-pyrrolidone and N-octadecyl-2-pyrrolidone, dodecyltrimethylammonium hydroxide, tridecyltrimethylammonium hydroxide, tetradecyltrimethylammonium hydroxide, pentadecyltrimethyl Ammonium hydride Quaternary ammonium salt surfactants such as xoxide, hexadecyltrimethylammonium hydroxide, heptadecyltrimethylammonium hydroxide, octadecyltrimethylammonium hydroxide, “Plysurf A212E”, “Plysurf A210G” (all One or more of nonionic surfactants such as polyoxyethylene phosphate ester surfactants such as Ichi Kogyo Seiyaku Co., Ltd., polyoxyalkylene alkyl ethers or alkylamine oxide compounds are preferably used. It is done.

  In the case of adding such a surfactant, the amount added is preferably about 1 ppm to 10% by mass, more preferably about 100 ppm to 2% by mass in the solid content of the coating agent.

<Preservative>
When natural collagen is contained, water-soluble amine compounds, alkalis such as quaternary ammonium hydroxides, and acids such as acetic acid and peracetic acid can be added as preservatives in order to prevent spoilage and bacteria generation. .
Examples of the water-soluble amine compound include amines having a pKa (acid dissociation constant) in an aqueous solution at 25 ° C. of 7.5 or more. Specifically, for example, monoethanolamine, diethanolamine, triethanolamine, 2- (2-aminoethoxy) ethanol, N, N-dimethylethanolamine, N, N-diethylethanolamine, N, N-dibutylethanolamine , Alkanolamines such as N-methylethanolamine, N-ethylethanolamine, N-butylethanolamine, N-methyldiethanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine; diethylenetriamine, triethylenetetramine, propylenediamine, N, N-diethylethylenediamine, 1,4-butanediamine, N-ethyl-ethylenediamine, 1,2-propanediamine, 1,3-propanediamine, 1,6-hexane Polyalkylene polyamines such as amines; aliphatic amines such as 2-ethyl-hexylamine, dioctylamine, tributylamine, tripropylamine, triallylamine, heptylamine, cyclohexylamine; aromatic amines such as benzylamine and diphenylamine Cyclic amines such as piperazine, N-methyl-piperazine, and hydroxyethylpiperazine;
The quaternary ammonium hydroxide includes tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, methyltripropylammonium hydroxide, methyltributylammonium hydroxide. Thing, choline etc. are mentioned.

  When such a water-soluble amine compound is added, the addition amount is preferably about 0.1 to 30% by mass in the solid content of the coating agent, and particularly adjusted to about 2 to 15% by mass. preferable.

<Aqueous solution>
The coating agent of the present invention is preferably used as an aqueous solution, but may be a mixed solvent of water and an alcohol solvent as long as the effects of the present invention are not impaired. Examples of such alcohol solvents include methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, glycerin, ethylene glycol, propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, and 2,3-butylene. Glycol and the like. These alcohol solvents are preferably used in an amount of up to 30 parts by mass, more preferably 20 parts by mass with respect to 100 parts by mass of water.

≪Method for forming fine pattern≫
In the fine pattern forming method according to the present invention, a photoresist pattern formed on a substrate is coated with the above-mentioned coating agent, and then heat-treated at 60 ° C. or more and 250 ° C. or less to thermally shrink the coating agent, and then Removing the coating.

  The formation of the photoresist pattern on the substrate is not particularly limited. For example, a conventionally known photoresist composition is applied onto a substrate such as a silicon wafer by a spinner or the like, dried to form a photoresist layer, and then subjected to a conventionally known exposure and development treatment, whereby an arbitrary photoresist is formed on the substrate. A pattern can be formed.

As the photoresist composition which is a material of the resist pattern, is not particularly limited, i-line, g-line photoresist composition, KrF, ArF, excimer laser photoresist composition, such as F _2, further Widely and generally used photoresist compositions such as a photoresist composition for EB (electron beam) and a photoresist for EUV can be used.

<A. Coating agent application process>
Next, a coating agent is applied and coated over the entire surface of the photoresist pattern as the mask pattern. In addition, after apply | coating this coating agent, you may give a prebaking for 30 to 90 second at the temperature of 80-100 degreeC, for example.

  The coating method can be performed in accordance with a method usually performed in a conventional heat flow process. That is, for example, an aqueous solution of the above coating is applied to the photoresist pattern by a known coating means such as a bar coater method, a roll coater method, a slit coater method, or spin coating using a spinner. The coating thickness of the coating agent is preferably about the same as the height of the photoresist pattern or a height that covers it.

<B. Heat treatment process>
Next, heat treatment is performed to heat shrink the coating agent. Due to the heat shrinking action of the coating agent, the photoresist pattern in contact with the coating agent becomes wider by the amount corresponding to the shrinkage of the coating agent. As a result, the photoresist patterns become close to each other, and the distance between the photoresist patterns (pattern width) is increased. It is narrowed.

  The heat treatment temperature is preferably 60 ° C. or higher and 250 ° C. or lower. In particular, a temperature of 80 ° C. or higher and 200 ° C. or lower is more preferable. When the heat treatment temperature is 80 ° C. or higher and 200 ° C. or lower, the coating agent can be effectively shrunk while preventing the thermal flow of the photoresist pattern itself. Further, the heat treatment at such a temperature makes it possible to more effectively form a fine pattern with a good profile, and in particular, the duty ratio in the wafer surface, that is, the pattern interval in the wafer surface. The dependence on can also be reduced. In addition, since the coating material of the present invention has no problem such as fluctuation of the fineness due to fluctuations in the heating temperature and the amount of thermal shrinkage of the coating material is constant, the pattern width can be stably narrowed even at low temperatures. .

<C. Coating agent removal process>
Thereafter, the coating film made of the coating agent remaining on the substrate having the photoresist pattern is removed by washing with an aqueous solvent, preferably pure water, for 10 to 60 seconds. Prior to the water removal, a rinse treatment may be performed with an alkaline aqueous solution (for example, tetramethylammonium hydroxide (TMAH), choline, etc.) as desired. The coating agent according to the present invention can be easily removed by washing with water, and can be completely removed from the substrate and the photoresist pattern. Then, a substrate having a miniaturized pattern defined between the wide and wide photoresist patterns is obtained on the substrate.

  The fine pattern obtained by the present invention has a finer pattern than the resolution limit obtained by the conventional methods, a good resist pattern shape, and physical properties that can sufficiently satisfy the required required characteristics. It is provided. Specifically, a large narrowing amount (= resist pattern width before processing−resist pattern width after processing) of about 15 to 30 nm per time, which could not be obtained with a conventional coating agent, is stably obtained without variation. be able to.

  In addition, you may perform the said ac process repeatedly several times. In this way, by repeating the steps a to c a plurality of times, the photoresist pattern can be gradually widened and widened.

The technical field to which the present invention is applied is not limited to the semiconductor field, and can be widely used for manufacturing liquid crystal display elements, magnetic heads, and microlenses.

  Hereinafter, the present invention will be described in detail with reference to examples. In addition, this invention is not limited to the following Example at all.

<Examples 1-4>
[Coating agent A]
10 g of “water-soluble collagen peptide PA” (manufactured by Kyowa Hakko Kogyo Co., Ltd.) and 0.1 g of “Plisurf A210G” (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) as a polyoxyethylene phosphate ester surfactant And the total amount was adjusted to 100 g.

[Coating agent B]
10 g of “water-soluble collagen peptide DS” (manufactured by Kyowa Hakko Kogyo Co., Ltd.) and 0.1 g of “Plysurf A210G” (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) as a polyoxyethylene phosphate ester surfactant And the total amount was adjusted to 100 g.

[Coating agent C]
10 g of “water-soluble collagen peptide SS” (manufactured by Kyowa Hakko Kogyo Co., Ltd.) and 0.1 g of “Plysurf A210G” (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) as a polyoxyethylene phosphate ester surfactant And the total amount was adjusted to 100 g.

[Coating agent D]
10 g of “water-soluble fish collagen peptide” (manufactured by Kyowa Hakko Kogyo Co., Ltd.) and 0.1 g of “Plysurf A210G” (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) as a polyoxyethylene phosphate ester surfactant And the total amount was adjusted to 100 g.

  On the other hand, an antireflection film of “ARC-29A” (manufactured by Nissan Chemical Industries, Ltd.) was spin-coated on an 8-inch silicon wafer and baked at 205 ° C. for 60 seconds to form a film. “TARF-P7152” (manufactured by Tokyo Ohka Kogyo Co., Ltd.), which is a positive photoresist, is spin-coated on a silicon wafer on which an antireflection film is formed, baked at 135 ° C. for 90 seconds, and has a thickness of 370 nm. A layer was formed.

  The photoresist layer was exposed using an exposure apparatus NSR-S302 (manufactured by Nikon Corp.), subjected to heat treatment at 110 ° C. for 60 seconds, and 2.38 mass% TMAH (tetramethylammonium hydroxide). Development processing was performed using an aqueous solution to form a hole pattern having a diameter of 154.0 nm (hole diameter: distance between hole patterns = 1: 1).

  Next, the coating agents A to D are respectively applied to the resist pattern on the silicon wafer to form a coating film having a film thickness of 200 nm, and the wafer is heat-treated at 140 ° C. for 60 seconds to form the hole pattern. Refinement processing was performed. Subsequently, the coating agent was removed using pure water at 23 ° C.

<Comparative example>
[Comparative coating agent]
As a phosphoric acid ester surfactant of 7.0 g of a copolymer (AA: VP = 2: 1.3 (polymerization ratio)) of acrylic acid / vinyl pyrrolidone (AA / VP), triethylamine 6 g, and polyoxyethylene 1 g of Surf A210G (Daiichi Kogyo Seiyaku Co., Ltd.) was dissolved in pure water and the total amount was adjusted to 100 g to obtain a comparative coating agent.

  As in the above example, after forming a hole pattern having a diameter of 154.0 nm (hole diameter: distance between hole patterns = 1: 1), the above-described comparative coating agent was applied to form a coating film having a thickness of 200 nm. The wafer was heat-treated at 140 ° C. for 60 seconds, and the hole pattern was refined. Subsequently, the coating agent was removed using pure water at 23 ° C.

<Test example>
About these refinement | miniaturization processes, the evaluations 1-4 shown below were performed, respectively.

Evaluation 1: Narrowing amount (miniaturization amount)
The resist pattern dimension after the above-mentioned miniaturization treatment was measured with a scanning electron microscope. Table 1 shows the amount of narrowing defined by “resist pattern width before processing−resist pattern width after processing”.

Evaluation 2: Fluctuation in the amount of narrowing of the sparse / dense pattern For a pattern in which the distance between the hole patterns of the hole pattern described above is 1 time (same size: dense pattern), 5 times (sparse pattern) Each was subjected to a miniaturization process. The resist pattern after the miniaturization treatment at this time was measured with a scanning electron microscope, and the difference between the minimum amount and the maximum amount of the narrowing amount is shown in Table 1, respectively.

Evaluation 3: Resist pattern shape after miniaturization treatment The resist pattern shape after the above-described miniaturization treatment was observed and evaluated with a scanning electron microscope. As a result, a resist pattern having a good rectangular shape is shown as A, and a resist pattern having a non-rectangular shape as B is shown in Table 1.

  From the results in Table 1, in Examples 1 to 4, a large narrowing amount of 20 nm or more was obtained, and the variation of the narrowing amount in the dense / dense pattern was as small as 5 nm or less. In addition, the top and bottom portions of the resist pattern seen in the comparative example did not easily change in shape, such as being slightly rounded (rounded), and the pattern shape was also good. In all of the examples, no defect was observed.

Evaluation 4: Fluctuation in the amount of narrowing due to fluctuations in the heat treatment temperature Using each of the film forming agent A and the comparative film forming agent, the heat treatment in the above-described miniaturization treatment was performed at three points of 145 ° C., 150 ° C., and 155 ° C. As shown in FIG. The dimension of the resist pattern after the miniaturization treatment was measured with a scanning electron microscope. The results are shown in Tables 2 and 3. Table 2 shows the hole diameters obtained by measuring the resist pattern dimensions after the miniaturization treatment with a scanning electron microscope, and Table 3 shows the respective narrowing amounts.

  From the results of Tables 2 and 3, the amount of narrowing of the coating agents of the Examples is larger than that of the Comparative Examples. It can also be seen that the temperature dependence at the time of narrowing the pattern width is small and the density dependence of the pattern interval is also small.

Claims (7)

A coating for pattern miniaturization used to coat a photoresist pattern formed on a substrate and to form a fine pattern,
A coating agent for pattern miniaturization containing a water-soluble peptide.   The coating agent for pattern miniaturization according to claim 1, wherein at least a part of the water-soluble peptide can form a triple helical structure.   The coating agent for pattern miniaturization according to claim 1 or 2, wherein the water-soluble peptide is a water-soluble collagen peptide.   The coating agent for pattern miniaturization according to any one of claims 1 to 3, wherein the water-soluble peptide has a mass average molecular weight of 10,000 or less.   The coating agent for pattern miniaturization according to any one of claims 1 to 4, wherein the coating agent for pattern miniaturization further contains a surfactant.   The pattern refinement coating agent according to claim 1, wherein the pattern refinement coating agent further contains a preservative.   A photoresist pattern formed on a substrate is coated with the pattern refinement coating agent according to any one of claims 1 to 6, and then the pattern refinement coating agent is applied by heat treatment at 60 ° C to 250 ° C. A method for forming a fine pattern, comprising a step of heat shrinking and then removing the coating material for pattern refinement.