JP2012137778A - Silicon-containing composition for fine pattern formation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composition for forming a fine pattern with high dry etching resistance.SOLUTION: The composition for fine pattern formation contains: a resin containing a repeating unit having a silazane bond; and a solvent. A method for fine pattern formation using the same is also provided.

Description

  In the manufacturing process of a semiconductor or the like, the present invention can form a finer pattern by reducing the pitch size or pattern opening size of a resist pattern that has already been formed. The present invention relates to a composition for forming a fine pattern.

  In order to form a finer pattern using a general photolithography technique, it is necessary to improve the exposure apparatus. In particular, in order to form a pattern having a pitch size of 60 nm or less by an optical lithography technique, a special apparatus such as immersion optical lithography developed in recent years is necessary, and enormous investment is required.

For this reason, various techniques for obtaining a fine pattern without using such an expensive apparatus have been studied. The most practical method is to refine the resist pattern by forming a coating layer on the formed resist pattern using a composition containing a water-soluble resin and, if necessary, an additive. Is. This technique can form a fine pattern that exceeds the limit of photolithography regardless of the exposure wavelength. Such a technique has a short history and has been implemented for about 10 years.
For example,
(1) A method of forming a resist pattern, then applying a mixing generation resist, baking to form a mixing layer, developing to a fine pattern dimension, and forming a pattern (Patent Document 1),
(2) A positive photoresist pattern is formed on a substrate and then uniformly irradiated with electromagnetic radiation, and then a water-based paint is uniformly applied, and the positive photoresist is dissolved and peeled off with an alkaline aqueous solution (lift-off). ) To form a fine pattern of water-based paint (Patent Document 2),
(3) The resist pattern containing a material that generates an acid upon exposure is covered with a resist containing a material that crosslinks in the presence of the acid, and an acid is generated in the resist pattern by heating or exposure to cause crosslinking at the interface. A method in which a layer is formed as a coating layer of a resist pattern, the resist pattern is thickened, and a reduction in the hole diameter or separation width of the resist pattern is achieved (Patent Document 3),
(4) A fine pattern forming material obtained by dissolving a completely water-soluble crosslinking agent selected from glycol lauryl in which at least one imino group hydrogen atom is substituted with a hydroxyalkyl group, and a water-soluble resin in an aqueous medium. In addition, after forming a resist pattern on the substrate using a chemically amplified resist containing an acid generator, a coating film made of the fine pattern forming material is provided on the resist pattern, and heat treatment is performed to coat the resist pattern and the resist pattern. A method of forming a fine pattern by forming a water-insoluble reaction layer at the interface with the film and then removing the non-reacted portion of the coating film with an aqueous solvent (Patent Document 4),
(5) The surface layer portion of the resist pattern is infiltrated with a chemical solution containing a crosslinking agent that crosslinks in the presence of an acid and a swelling accelerator to swell the surface layer portion, and a cross-linked film is formed on the swollen surface layer portion of the resist pattern. A method of forming a resist pattern 2 (Patent Document 5),
(6) A resist pattern is covered with a first upper layer film containing an acid component, and a second upper layer film containing a basic component is further formed thereon, and then the acid component is put into the first resist pattern by heat treatment. The basic component is diffused into the first upper layer film to form a solubilized layer in the resist pattern, while the acid component is formed in the vicinity of the interface between the first upper layer film and the second upper layer film. A method of reducing the pattern width by removing the solubilized layer (Patent Document 6),
(7) A resist pattern refinement coating forming agent containing a copolymer of (meth) acrylic acid monomer and water-soluble vinyl monomer is applied to the entire surface or a part of the resist pattern formed on the substrate, and A method of thermally shrinking the resist pattern by heating to refine the pattern (Patent Document 7),
(8) A resist pattern forming method in which a resist pattern thickening material containing a resin and a surfactant is applied after applying the surfactant-containing liquid (Patent Document 8)
Etc. have been proposed. Furthermore, a resist pattern refinement composition is sold as AZ RELACS (registered trademark) by AZ Electronic Materials.

  These methods can easily form a fine pattern that generally exceeds the resolution limit of photolithography. However, there is room for improvement in the formation of ultrafine patterns having a pattern size of 50 nm or less because defects are likely to occur. In particular, in recent years, there has been a tendency to reduce the film thickness in order to increase the sensitivity of the resist.

JP-A-5-166717 JP-A-7-191214 Japanese Patent Laid-Open No. 10-73927 JP 2000-267268 A Japanese Patent Application Laid-Open No. 2001-1000042 JP 2002-6512 A JP 2003-84459 A JP 2004-191465 A

  In view of the above problems, the present invention aims to improve the dry etching resistance of a pattern finally obtained when a very fine pattern is formed.

  The composition for forming a fine pattern according to the present invention is a composition for forming a fine pattern for reducing the size of the resist pattern by directly applying to a resist pattern surface having a pitch size of 60 nm or less formed by a photolithography method. The resin comprises a resin comprising a repeating unit having a silazane bond, and a solvent that dissolves the resin and does not dissolve the resist pattern.

  ADVANTAGE OF THE INVENTION According to this invention, the composition for forming a fine pattern with high dry etching tolerance is provided.

  In addition, the composition for forming a fine pattern according to the present invention can be selected as a resist pattern material to be miniaturized, and is highly miniaturized with high resistance to dry etching against a wide variety of resist patterns. Pattern can be obtained.

The figure which shows typically the fine pattern formation method by this invention.

Composition for forming a fine pattern The composition for forming a fine pattern according to the present invention comprises a resin comprising a repeating unit having a silazane bond. Here, the silazane bond means a Si—N bond, which has a bond for bonding to another unit, and the remaining bond is substituted with an arbitrary substituent.
Generally, the substituent is hydrogen or a hydrocarbon group, but may be substituted with a silicon-containing group or a functional group such as a hydroxyl group, a carboxyl group, or an amino group. Further, when the number of bonds in the repeating unit is 2 or more and the number of bonds is 3 or more, the resin can have a two-dimensional or three-dimensional structure.

式中、Ｒ^１〜Ｒ^３は、それぞれ独立に、水素、炭素数１〜６の飽和炭化水素基、および炭素数１〜６の飽和炭化水素基を有するシラザン基からなる群から選択される基である。
飽和炭化水素基は、線状、分岐鎖状、または環状のいずれであってもよい。 Preferable examples of such repeating units include those represented by the following formula (I).

In the formula, R ^{1 to} R ³ are each independently a group selected from the group consisting of hydrogen, a saturated hydrocarbon group having 1 to 6 carbon atoms, and a silazane group having a saturated hydrocarbon group having 1 to 6 carbon atoms. It is.
The saturated hydrocarbon group may be linear, branched or cyclic.

The resin represented by the above formula (I) is generally called polysilazane. This polysilazane can take a two-dimensional or three-dimensional structure when any of R ^{1 to} R ³ is a silazane group represented by the formula (I). Moreover, the repeating unit represented by the said formula (I) can also combine 2 or more types.

Among such resins, perhydropolysilazane consisting only of silicon, nitrogen and hydrogen is one of the preferred ones. One of them is that in formula (I), all of R ^{1 to} R ³ are hydrogen. In addition, other perhydropolysilazanes are used as repeating units.
- _(SiH 2 NH) - and - _(SiH 2 N) have a <city, those ends are hydrogen or -SiH _3. This perhydropolysilazane can take various structures depending on the blending ratio of the repeating units, and examples thereof include the following structures.

  The molecular weight of such a resin is arbitrarily selected depending on the type of resist to be applied, the type of target pattern, and the like, but is preferably 500 to 100,000 in terms of weight average molecular weight, and 600 to More preferably, it is 10,000.

  The composition for forming a fine pattern according to the present invention comprises a solvent. This solvent needs to be capable of dissolving the resin. That is, when the composition is applied onto the resist pattern, the composition is preferably uniform. Therefore, the solubility of the resin with respect to the solvent may be dissolved to such an extent that the composition becomes uniform. On the other hand, if the solvent dissolves the pattern when it is applied onto the resist pattern, the pattern is destroyed before the pattern is miniaturized. Therefore, the resist pattern needs not to be dissolved. Furthermore, it is preferable that the resin does not react.

  As the solvent that can be used in the present invention, any solvent can be selected as long as it satisfies the above conditions. Moreover, it can select according to the kind of resin to be used, the material of the resist to apply, etc. Such solvents include (a) ethers such as dibutyl ether (DBE), dipropyl ether, diethyl ether, methyl-t-butyl ether (MTBE), and anisole, and (b) saturated hydrocarbons such as decalin, n-pentane, i-pentane, n-hexane, i-hexane, n-heptane, i-heptane, n-octane, i-octane, n-nonane, i-nonane, n-decane, i-decane, ethylcyclohexane (C) unsaturated hydrocarbons such as cyclohexene, and dipentene (limonene); (d) ketones such as methyl isobutyl ketone (MIBK), (e) aromatic hydrocarbons For example, benzene, toluene, xylene, ethylbenzene, di Ethylbenzene, trimethylbenzene, and triethylbenzene like, and the like. Among these, a solvent selected from the group consisting of (a) ethers and (b) saturated hydrocarbons is preferable. More specifically, dibutyl ether and decalin change the type of resin or resist material. Even so, it is widely applicable and is a preferred solvent. These solvents can be used in combination of two or more as required.

  The composition for forming a fine pattern according to the present invention is obtained by dissolving the resin in the solvent, but the concentration is not particularly limited. However, it can be appropriately adjusted according to the coating property on the resist surface, the desired pattern shrinkage amount, and the like. In general, the content of the resin is preferably 0.01 to 30%, more preferably 0.3 to 5%, based on the total weight of the composition.

  The composition for forming a fine pattern according to the present invention may contain other additives as necessary. Such additives include surfactants, leveling agents, plasticizers and the like.

Fine Pattern Forming Method The fine pattern forming method of the present invention is a conventionally known method except that the fine pattern forming composition of the present invention is used as the fine pattern forming composition. Therefore, the photoresist used for forming the resist pattern and the method for forming the resist using the photoresist may be either a conventionally known photoresist or a conventionally known resist forming method. In addition, the resist pattern can use the arbitrary thing generally used. In addition, as a method of coating the resist pattern with the composition for forming a fine pattern, any conventionally known method can be used.

  The fine pattern forming method according to the present invention will be described with reference to the drawings. In the following description, a case where a resist pattern is formed using an ArF resist will be described as an example.

  FIGS. 1A to 1F are conceptual diagrams for explaining a method of making a pattern finer by using the composition for forming a fine pattern of the present invention on the surface of a resist pattern. In each figure, the board | substrate 1, the resist pattern 2, the composition layer 3 for fine pattern formation, and the insolubilized layer 4 are shown as a schematic cross section.

First, a resist (for example, a positive chemical amplification resist) is applied on a substrate 1 to be processed such as a semiconductor substrate, and exposed and developed by a usual method to form a positive resist pattern 2. Here, the exposed portion of the resist is almost removed by development, but the properties of the inner wall portion of the removed portion are different from the properties of the portion not exposed at all, and the compatibility with the solvent is increased. Yes. Next, as shown in FIG. 1A, the composition for forming a fine pattern according to the present invention is applied so as to cover the resist pattern 2 to form a coating layer 3. By this application, the resin 5 in the composition is physically adsorbed to the resist pattern (FIG. 1B).
The resin adsorbed on the resist surface penetrates into the resist, and the resist film swells (FIG. 1C). Here, by heating the resist, the penetration of the resin and the reaction between the resin and the resist are promoted (FIG. 1D). And in the part which was not exposed, reaction with resin and a resist hardly arises, and the thickness of an insolubilized layer becomes thin. On the other hand, the reaction between the resin and the resist is likely to occur at the exposed portion or in the vicinity of the exposed portion, for example, the side surface of the resist pattern in FIG. 1, and the insolubilized layer is formed thick. When the reaction is completed, the insolubilized layer 4 is formed (FIG. 1 (e)). This insolubilized layer is a layer that is insolubilized after the resin physically adsorbed on the first resist surface penetrates not only into the resist surface but also into the resist, and as a result, the pattern shrinks. Finally, the unreacted composition for forming a fine pattern is removed by rinsing with a solvent to obtain a refined pattern (FIG. 1 (f)).

  As described above, the insolubilized layer 4 is formed mainly on the inner wall of the pattern on the surface of the resist pattern 2, thereby reducing the width between the resist patterns and effectively limiting the pitch size or hole opening size of the resist pattern. It becomes possible to make it fine below.

  The radiation-sensitive resin composition that can be used for forming the resist pattern 2 may be any conventionally known and publicly used radiation-sensitive resin composition. Examples of the radiation-sensitive resin composition include a positive resist containing an alkali-soluble resin such as a novolak resin, a hydroxystyrene resin, an acrylic resin, and a quinonediazide compound, an acid generated by light irradiation, and a catalytic action of the generated acid Examples include chemically amplified positive or negative resists that form a resist pattern by using an acid, but the chemistry that generates an acid by light irradiation and uses the catalytic action of the generated acid to form a resist pattern An amplification type positive resist is preferable. Many resist materials have already been proposed and are commercially available, and any known or publicly available resist material may be used. Moreover, the resist pattern formation method using a radiation sensitive resin composition can use any conventionally known methods including a coating method, an exposure method, a baking method, a developing method, a developer, a rinsing method, and the like. .

  In the pattern forming method according to the present invention, the method for applying the fine pattern forming composition of the present invention is, for example, a spin coating method, a spray coating method, or the like conventionally used when applying a radiation sensitive resin composition. An appropriate method such as a dip coating method or a roller coating method may be used. The applied coating layer is pre-baked as necessary to form a composition layer 3 for forming a fine pattern. The conditions for the heat treatment of the composition layer for forming a fine pattern are, for example, a temperature of 60 to 150 ° C., preferably 80 to 100 ° C., 10 to 300 seconds, preferably about 60 to 120 seconds. It is preferably a temperature at which intermixing of the forming composition layer occurs. The film thickness of the fine pattern forming composition layer to be formed can be appropriately adjusted depending on the temperature and time of the heat treatment, the radiation-sensitive resin composition used, the water-soluble resin composition, and the like. Therefore, these conditions may be set depending on how fine the resist pattern is to be made, in other words, how much the width of the resist pattern needs to be increased. However, the thickness of the coating layer is the thickness from the surface of the resist pattern, and is generally 0.01 to 100 μm.

  Furthermore, the solvent used for the rinsing process that leaves the insolubilized layer 4 formed by heating and removes the unreacted fine pattern-forming composition layer 3 is low in solubility in the insolubilized layer. A highly soluble composition is selected for the pattern forming composition. More preferably, the solvent used in the composition for forming a fine pattern is preferably used for the rinsing treatment.

  The present invention will be described below by examples. In addition, the aspect of this invention is not limited only to these examples.

Reference Example 1 Shrink Confirmation of Composition According to the Present Invention in Unexposed Resist Polysilazane manufactured by AZ Electronic Materials was dissolved in dibutyl ether at a concentration of about 10% by weight and filtered through a 0.05 micron filter to obtain a fine pattern. A forming composition was prepared.

  On the other hand, a resist for ArF (AX1120P (registered trademark): manufactured by AZ Electronic Materials) or a resist for KrF (DX5250P (registered trademark): manufactured by AZ Electronic Materials) is applied to a silicon wafer, and an exposure process is performed. First, a test substrate was obtained by baking at 90 ° C. for 60 seconds.

  The fine pattern forming composition is applied to the obtained test substrate in a thickness of about 120 nm, further baked at 50, 70, or 90 ° C. for 60 or 180 seconds, and further rinsed with dibutyl ether. It was. When the film thickness was measured before the application of the composition for forming a fine pattern and after the rinse treatment, no change in the film thickness was observed.

Example 1
A resist for KrF (DX5250P (registered trademark): manufactured by AZ Electronic Materials) is applied to a silicon wafer, exposed and developed by a normal method, and trench patterns having a pitch of 1: 3 and 1: 5, respectively, are formed. Produced. Furthermore, after apply | coating the composition for fine pattern formation prepared in Reference Example 1 on the pattern, it baked at 90 degreeC for 60 second. Next, the baked pattern was rinsed with dibutyl ether for 60 seconds and then subjected to spin drying to obtain a pattern. The trench width of the pattern before and after the treatment with the fine pattern forming composition is measured using a length measurement scanning microscope (critical dimension SEM S-9200, manufactured by Hitachi, Ltd.), and the amount of shrinkage is calculated. did. The obtained results were as shown in Table 1.

この結果より、本発明による微細パターン形成用組成物で処理することにより、トレンチ幅が１６ｎｍ縮小されたことがわかった。

From this result, it was found that the trench width was reduced by 16 nm by the treatment with the composition for forming a fine pattern according to the present invention.

Example 2
A resist for ArF (AX1120P (registered trademark): manufactured by AZ Electronic Materials Co., Ltd.) was applied to a silicon wafer, and exposure and development processing were performed by a normal method to produce a trench pattern. Furthermore, after preparing the fine pattern formation composition prepared in Reference Example 1 on the pattern, it was baked at 90 ° C. for 60 seconds. Next, the baked pattern was rinsed with dibutyl ether for 60 seconds and then subjected to spin drying to obtain a pattern. The trench widths of the pattern before and after the treatment with the fine pattern forming composition were measured using a length measurement scanning microscope (S-9200, manufactured by Hitachi, Ltd.), and the shrinkage was calculated. It was found that the trench width changed from 142 nm to 127 nm, and the trench width was reduced by 15 nm.

Example 3
The resistance to oxygen plasma was evaluated for the pattern treated with the fine pattern forming composition obtained in Example 1 and the pattern before treatment using an etcher (NE-5000 manufactured by ULVAC, Inc.). It was found that the pattern treated with the composition for forming a fine pattern according to the present invention has a large amount of remaining film and is excellent in dry etching resistance.

DESCRIPTION OF SYMBOLS 1 Substrate 2 Resist film 3 Fine pattern forming composition layer 4 Insolubilized layer 5 Adsorption resin

Claims (5)

  A composition for forming a fine pattern for reducing the size of a resist pattern, which is directly applied to a resist pattern surface having a pitch size of 60 nm or less, formed by photolithography, and having repeating units having silazane bonds A composition for forming a fine pattern, comprising: a resin comprising: a resin that dissolves the resin and does not dissolve the resist pattern. The composition for forming a fine pattern according to claim 1, wherein the repeating unit having the silazane bond is represented by the following formula (I).

Wherein R ^{1 to} R ³ are each independently selected from the group consisting of hydrogen, a C 1-6 saturated hydrocarbon group, and a silazane group having a C 1-6 saturated hydrocarbon group. Group.)   The composition for forming a fine pattern according to claim 1 or 2, wherein the resin comprises two or more repeating units having a silazane bond.   The composition for fine pattern formation of any one of Claims 1-3 whose weight average molecular weights of the said resin are 500-100,000.   The composition for forming a fine pattern according to any one of claims 1 to 4, wherein the solvent is a solvent selected from the group consisting of ethers and saturated hydrocarbons.

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