JP2013235187A - Resin composition for hole shrink - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin composition for hole shrink, capable of obtaining circular fine holes having uniform size by a hole shrink process.SOLUTION: The resin composition for hole shrink comprises: a block-copolymer (I) including an aromatic ring containing polymer and a poly (meta) acrylate as a block portion and having a molecular weight of 10,000 or more and 1 million or less (a ratio of the total of the aromatic ring containing polymer portion (Ia) and the poly (meta) acrylate portion (Ib) relative to the whole I is 50 mol % or more, and a molar ratio of Ia to Ib is 1:1 to 10:1.); and an aromatic ring containing homopolymer (II) consisting of a repeating unit constituting Ia of I as a by-product of I and having a molecular weight equal to or more than that of Ia of I. A ratio of II to I is more than 0 mass% and 10 mass% or less.

Description

  The present invention relates to a resin composition for forming a pattern of a state-of-the-art microstructure in a semiconductor. More specifically, the present invention relates to a resin composition for hole shrink that can obtain a circular refined hole having a uniform size by a hole shrink method.

According to the International Semiconductor Technology Roadmap (ITRS), it is said that a 16 nm node microfabrication technology is required in 2016 (see Non-Patent Document 1 below).
As one of the techniques for achieving this level of ultrafine processing, a DSA (Directed Self-Assembly) method using a block copolymer has attracted attention. DSA is a technique for forming a finer pattern by forming a microphase separation structure of a block copolymer in a pattern formed by lithography.

For example, in Patent Document 1 below, a block made of polystyrene (hereinafter also referred to as PS) and polymethyl methacrylate (hereinafter also referred to as PMMA) is formed in a hole having a diameter of 60 to 110 nm formed using a photoresist. A copolymer (hereinafter also referred to as PS-b-PMMA) is embedded, self-assembled, and a cylindrical structure composed of a PMMA portion is formed at the center of the hole, and the portion is removed by plasma etching or the like. It is disclosed that fine holes of 40 to 45 nm can be formed. Such a technique is called “hole shrink”.
Further, in Patent Document 1, even when holes having a diameter of 60 to 110 nm manufactured using a photoresist cannot be separated due to a too small pitch, PS-b-PMMA is embedded and self-organized. , It is disclosed that a separated cylindrical structure part composed of a PMMA part is formed and the part can be removed to form a separated hole. Such a technique is called “hole self-healing”.

JP 2010-269304 A International Publication No. WO2010 / 131680A1

International Technology Roadmap for Semiconductors 2011 Edition Lithography p14-15 (http://www.itrs.net)

  In order to perform hole shrink and hole self-repair using the DSA technique, the shape and size of the fine holes formed by the block copolymer must be constant. Furthermore, it is often desirable that the shape be circular. The fine holes are generally formed by selectively etching a phase separated pattern with plasma. Therefore, it is necessary that the component of the block copolymer in the part that becomes the fine hole is more easily plasma-etched than the component around the hole. In general, a structure containing an aromatic ring exhibits plasma etching resistance, while a (meth) acrylic acid ester structure is easily etched, so that a block copolymer of the combination is a preferred component.

As a method for synthesizing such a block copolymer, for example, a vinyl monomer containing an aromatic ring such as styrene is polymerized by a living anion method to form an active polystyrene having an anion at the end, and then methyl methacrylate (hereinafter referred to as MMA). And a method of synthesizing PS-b-PMMA by adding a (meth) acrylic acid ester monomer such as Here, when a protic impurity such as water or alcohol is present in the MMA monomer solution to be added, it reacts with the above polystyrene anion to produce homopolystyrene. In addition, the chain reaction between polystyrene anion and MMA is inhibited, it reacts with another molecule of polystyrene anion, and a homopolymer having a molecular weight almost twice that of polystyrene anion is often contained in the block copolymer as an impurity. When hole shrinking is performed using such a block copolymer containing 10% by mass or more of homopolystyrene or homopolymer, it is difficult to form a circular refined hole, and the shape and size are not uniform. Sometimes. In order to prevent the production of homopolystyrene and homopolymer, it is necessary to strictly carry out precise purification of solvents and monomers and temperature control. However, when producing block copolymers on an industrial scale, This measure would be an unrealistic response.
In view of the above, the problem to be solved by the present invention is to provide a resin composition for hole shrink that can obtain a circular refined hole having a uniform size by the hole shrink method.

As a result of intensive studies and repeated experiments, the inventors of the present invention have formed a block copolymer (I) containing an aromatic ring-containing polymer and poly (meth) acrylate as a block portion in order to form uniform fine holes by the hole shrink method. The aromatic ring-containing homopolymer (II) consisting of repeating units constituting the aromatic ring-containing polymer part (Ia) as a by-product in the synthesis is extracted, and the ratio of (II) to (I) is 0% by mass. It was discovered that by carrying out hole shrinkage using a highly pure block copolymer (I) -containing composition that has been reduced to 10% by mass or less, circular refined holes of uniform dimensions can be obtained. Based on this, the present invention has been completed.
That is, the present invention is as follows.

[1] The following:
Block copolymer (I) comprising an aromatic ring-containing polymer and poly (meth) acrylate as a block portion, wherein the molecular weight of the block copolymer (I) is from 10,000 to 1,000,000, based on the entire block copolymer (I) The total ratio of the aromatic ring-containing polymer portion (Ia) and the poly (meth) acrylate portion (Ib) is 50 mol% or more, and the aromatic ring-containing polymer portion (Ia): the poly (meth) acrylate portion (Ib) The repeating unit constituting the aromatic ring-containing polymer part (Ia) of the block copolymer (I) as a by-product in the synthesis of the block copolymer (I) Comprising an aromatic ring having a molecular weight equal to or greater than the molecular weight of the aromatic ring-containing polymer part (Ia) of the block copolymer (I). Homopolymer (II);
A resin composition for whole shrink, comprising a ratio of the aromatic ring-containing homopolymer (II) to the block copolymer (I) in the composition of more than 0% by mass and 10% by mass or less. The resin composition for hall shrink.

  [2] The resin composition for whole shrink according to [1], wherein the ratio of the aromatic ring-containing homopolymer (II) to the block copolymer (I) is greater than 0% by mass and 5% by mass or less.

  [3] The resin composition for hole shrink according to [2], wherein the ratio of the aromatic ring-containing homopolymer (II) to the block copolymer (I) is greater than 0% by mass and 2.5% by mass or less.

  [4] The resin composition for hole shrink according to any one of [1] to [3], wherein the aromatic ring-containing polymer part (Ia) is an aromatic ring-containing vinyl polymer.

  [5] The resin composition for hole shrink according to [4], wherein the aromatic ring-containing vinyl polymer is polystyrene, and the poly (meth) acrylate moiety (Ib) is polymethyl methacrylate.

[6] The following steps:
Block copolymer (I) comprising an aromatic ring-containing polymer and poly (meth) acrylate as a block portion, wherein the molecular weight of the block copolymer (I) is from 10,000 to 1,000,000, based on the entire block copolymer (I) The total ratio of the aromatic ring-containing polymer portion (Ia) and the poly (meth) acrylate portion (Ib) is 50 mol% or more, and the aromatic ring-containing polymer portion (Ia): the poly (meth) acrylate portion (Ib) The molar ratio is 1: 1 to 10: 1; and consists of repeating units constituting the aromatic ring-containing polymer part (Ia) of the block copolymer (I) as a by-product, the molecular weight of which is the block copolymer Synthesizing a mixture of an aromatic ring-containing homopolymer (II) that is equal to or higher than the molecular weight of the aromatic ring-containing polymer part (Ia) of (I); The aromatic ring-containing homopolymer (II) is extracted by heating the obtained mixture in an organic solvent that is a good solvent for the aromatic ring-containing homopolymer (II), Reducing the proportion of II) to greater than 0% by weight and not more than 10% by weight;
The manufacturing method of the resin composition for hole shrinks in any one of said [1]-[5] containing.

  [7] The method according to [6], wherein the aromatic ring-containing homopolymer (II) is extracted at a temperature 20 ° C. or more lower than the boiling point of the organic solvent.

  [8] The method according to [7], wherein the aromatic ring-containing homopolymer (II) is extracted at a temperature 30 ° C. to 40 ° C. lower than the boiling point of the organic solvent.

[9] The following steps:
Applying the resin composition for hole shrink according to any one of [1] to [5] to a substrate on which holes are formed,
In the hole, an island portion of the poly (meth) acrylate portion (Ib) of the block copolymer (I), an aromatic ring-containing polymer portion (Ia) of the block copolymer (I) and an aromatic ring-containing homopolymer ( II) is formed by heating the sea part, and the island part is removed by etching.
Including a hall shrink method.

  If the resin composition for hole shrink according to the present invention is used, circularly refined holes with uniform dimensions can be obtained.

FIG. 3 is a schematic diagram of a whole shrink process. It is a figure which shows the shape of a refined hole. Da is the major axis, Db is the minor axis, and the Da / Db value is the circular coefficient.

Hereinafter, the present invention will be described in detail.
First, the hall shrink process will be described with reference to FIG.
(A) is a substrate in which openings for forming a microphase separation structure by a block copolymer are arranged, and is composed of a layer (A1) having an opening and a base substrate (A2). This opening is typically a photoresist film processed by photolithography, or a substrate from which the photoresist is removed by etching the underlying layer using the processed photoresist pattern as a mask. (B) shows the structure which filled the resin composition (block copolymer composition) (B1) for hole shrink into the opening part of (a). Filling is generally achieved by spin-coating a substrate with an organic solvent solution of the block copolymer composition (B1) and removing the solvent by heating. The substrate is then heated using a hot plate or oven to form a self-organized structure of the block copolymer. The state is shown in (c), where C1 is the “sea” part of the phase separation structure and C2 is the “island” part. Next, the island portion is removed by plasma etching. Here, it is necessary to design the sea portion to be an aromatic ring-containing polymer portion that is difficult to be etched and the island portion to be a (meth) acrylic acid ester polymer portion. The state of the cross section after etching is shown in (d), and the opening formed by removing the island portion becomes the miniaturized hole according to the present invention.

Next, components of the resin composition for pattern formation according to the present invention will be described.
First, the block copolymer (I) will be described. As a typical example of the aromatic ring-containing polymer portion (Ia) which is one of the essential components of the block constituting the block copolymer (I) used in the present invention, a vinyl monomer having a heteroaromatic ring such as an aromatic ring or a pyridine ring For example, polystyrene, polymethylstyrene, polyethylstyrene, polyt-butylstyrene, polymethoxystyrene, polyN, N-dimethylaminostyrene, polychlorostyrene, polybromostyrene, polytrifluoromethyl Examples include styrene, polytrimethylsilylstyrene, polydivinylbenzene, polycyanostyrene, poly α-methylstyrene, polyvinyl naphthalene, polyvinyl biphenyl, polyvinyl pyrene, polyvinyl phenanthrene, polyisopropenyl naphthalene, and polyvinyl pyridine. . Examples of the other aromatic ring-containing polymer (Ia) include polymethylphenylsiloxane and polydiphenylsiloxane. Here, the aromatic ring-containing polymer preferably used in the present invention is an aromatic ring or a heteroaromatic ring-containing vinyl polymer, and is more preferable from the viewpoint of excellent phase separation, availability of raw material monomers, and ease of synthesis. Is polystyrene (PS).

  The poly (meth) acrylate moiety (Ib), which is another essential component of the block constituting the block copolymer (I) used in the present invention, is at least one selected from the group consisting of the following acrylate monomers and methacrylate monomers. Homopolymer or copolymer. Examples of the group consisting of acrylate monomers and methacrylate monomers that can be used here include, for example, methyl methacrylate (MMA), ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, T-butyl methacrylate, n-hexyl methacrylate, cyclohexyl methacrylate, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, Examples include n-hexyl acrylate and cyclohexyl acrylate. The most preferred poly (meth) acrylate is methyl methacrylate homopolymer polymethyl methacrylate (PMMA) from the viewpoint of excellent phase separation, availability of raw material monomers, and ease of synthesis.

The block copolymer (I) used in the present invention is a diblock, triblock or more multiblock in which one end or both ends of the aromatic ring-containing polymer and one end or both ends of the poly (meth) acrylate are bonded. From the viewpoint of ease of synthesis, the copolymer is preferably a diblock copolymer in which one end of an aromatic ring-containing polymer and poly (meth) acrylate are bonded to each other, more preferably a PS and PMMA diblock copolymer. is there.
The block copolymer (I) contains blocks of other polymer components in a proportion not exceeding 50 mol% in addition to the aromatic ring-containing polymer portion (Ia) and the poly (meth) acrylate portion (Ib). You can also. That is, as described above, the resin composition for pattern formation according to the present invention has a total of the aromatic ring-containing polymer portion (Ia) and the poly (meth) acrylate portion (Ib) with respect to the entire block copolymer (I). The ratio must satisfy 50 mol% or more. Specific examples of other polymer components include polyethylene oxide, polypropylene oxide, polytetramethylene glycol and the like.

  The block copolymer (I) can be synthesized by living anion polymerization, living radical polymerization, or coupling of polymers having reactive end groups. For example, in living anionic polymerization, an anionic species such as butyl lithium (BuLi) is used as an initiator, and then an aromatic ring-containing polymer is synthesized, and then a (meth) acrylate monomer is polymerized starting from the terminal. A block copolymer of an aromatic ring-containing polymer and poly (meth) acrylate can be synthesized. In addition, an aromatic ring-containing polymer (Ia) is synthesized using an initiator such that both ends are anion starting points, and a (meth) acrylate monomer is polymerized using the terminal as the starting point, whereby an aromatic ring-containing polymer and A triblock copolymer of (meth) acrylate can be synthesized. In these living anionic polymerizations, the molecular weight of the resulting polymer can be increased by lowering the amount of initiator added, and the molecular weight of the polymer can be controlled by removing impurities in the system such as water and air. it can. Further, when polymerizing the poly (meth) acrylate moiety, the side reaction can be suppressed by lowering the temperature of the system to 0 ° C. or lower.

The molecular weight of the block copolymer (I) is determined by the following method.
First, among the block copolymers (I), the block copolymer (I) in a selective solvent that is a good solvent for the aromatic ring-containing polymer portion (Ia) and a poor solvent for the poly (meth) acrylate portion (Ib). And the aromatic ring-containing homopolymer (II) is extracted. The operating conditions are the same as the extraction conditions for the aromatic ring-containing homopolymer (II) described later. Next, the block copolymer (I) and the solution are separated, and the solution is evaporated to dryness to isolate the aromatic ring-containing homopolymer (II). Gel permeation chromatography (hereinafter also referred to as GPC) of the isolated aromatic ring-containing homopolymer (II) is measured. The efflux of the carrier solvent showing the maximum value of the obtained chromatogram was obtained, the molecular weight obtained using the calibration curve prepared using standard polystyrene was taken as the peak molecular weight (Mp), and the block copolymer (I ) Is the molecular weight of the aromatic ring-containing polymer portion (Ia). When there are two maximum values in the chromatogram, the above calculation is performed for the maximum value on the low molecular weight side to obtain the molecular weight of the aromatic ring-containing polymer portion (Ia) in the block copolymer (I).
In the case of carrying out the present invention by polymerizing the block copolymer (I) by the living anion method, a part of the aromatic ring-containing polymer having an active terminal from the reaction mixture at the time when the polymerization of the aromatic ring-containing monomer is completed. The molecular weight of the homopolymer obtained by extracting the sample from methanol and the like is measured by GPC, and the same calculation as above is performed for the maximum value of the chromatogram to obtain the molecular weight of the (Ia) portion of the block copolymer (I). You can also.
Next, the proton nuclear magnetic resonance spectrum (NMR) of the block copolymer (I) solution is measured, and the number of protons directly bonded to the aromatic ring and the number of protons directly bonded to the carboxy group of the poly (meth) acrylate is determined. The molar ratio of the containing polymer part (Ia) and the poly (meth) acrylate part (Ib) is calculated to determine the molecular weight of the Ib part. The sum of the molecular weights of both portions is defined as the molecular weight of the block copolymer (I).

Next, a method for purifying the block copolymer (I) according to the present invention will be described.
For example, in the case of the synthesis of PS-b-PMMA, homopolystyrene is produced as a by-product, which is composed of a homopolymer having the same molecular weight as the molecular weight of the PS portion of the corresponding block copolymer, In general, it is a mixture of Here, in the case of a block copolymer in which the molecular weight of the PMMA portion in the block copolymer is sufficiently larger than the molecular weight of the PS portion, it is a good solvent for PS called a selective solvent, but is a poor solvent for PMMA. Homopolystyrene can be efficiently extracted by Soxhlet extraction using a certain solvent such as cyclohexane (see Patent Document 2). However, the block copolymer used for the hole shrink needs to occupy a majority of the polymer portion having high dry etching resistance, that is, the aromatic ring-containing polymer portion. For example, in PS-b-PMMA, the molecular weight of the PS moiety is greater than that of the PMMA moiety. In this case, for example, when Soxhlet extraction is attempted with cyclohexane, the block copolymer itself exhibits solubility in cyclohexane at a temperature close to the boiling point, so that the block copolymer itself is extracted together with homopolystyrene or swells to a shape that is difficult to handle.

Therefore, in order to efficiently extract the aromatic ring-containing homopolymer from the block copolymer disclosed in the present invention, the homopolymer containing the aromatic ring is extracted by introducing the block copolymer into a selective solvent and stirring the mixture. It is preferable to do. The liquid temperature at that time is preferably a temperature that is 20 ° C. or more lower than the boiling point of the solvent, and more preferably a temperature that is 30 to 40 ° C. lower than the boiling point.
If the difference from the boiling point is less than 20 ° C., the block copolymer swells and the extraction efficiency is lowered, and it becomes difficult to separate the block copolymer from the solution after extraction. In addition, the extraction rate becomes slow at a temperature lower than the boiling point by 40 ° C. or more. By such extraction, the ratio of the aromatic ring-containing homopolymer (II) to the block copolymer (I) is greater than 0% by mass, preferably 10% by mass or less, preferably 5% by mass or less, more preferably 2.5% by mass or less. It is desirable to make it.

In the present invention, the term “hole shrink” refers to further reducing the diameter of the opening provided in advance in the substrate.
Hereinafter, the method for carrying out hole shrinkage using the resin composition for hole shrinkage according to the present invention will be described in detail. As described above, FIG. 1A shows a substrate having a plurality of openings for forming holes. The layer A1 having an opening may be a photoresist layer having an opening formed by photolithography, or may be a layer processed by nanoimprinting, laser processing, or the like, and a pattern formed by these methods is used as a mask. It may be a layer in which an opening is formed by etching. The opening of A1 is also called a hole or a pre-pattern. A2 is the base substrate.

  As a substrate, a silicon wafer, an inorganic material substrate such as a compound semiconductor wafer, an organic material substrate, a metal substrate, a wiring substrate, an inorganic substrate provided with a metal thin film, an inorganic substrate provided with a polyimide thin film, a plurality of semiconductor devices, etc. Examples include a substrate made of a material. FIG.1 (b) shows the state which embedded resin composition B1 for hole shrink containing a block copolymer in the opening part of Fig.1 (a). The resin composition for whole shrink according to the present invention can be embedded in the opening by applying a solution dissolved in an organic solvent and drying. Any solvent can be used as long as it can dissolve the above-described resin composition for whole shrink. For example, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, γ-butyrolactone, cyclohexane Pentanone, cyclohexanone, isophorone, N, N-dimethylacetamide, dimethylimidazolinone, tetramethylurea, dimethyl sulfoxide, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, dipropylene glycol Monomethyl ether, propylene glycol monomethyl ether acetate (hereinafter also referred to as PGMEA), methyl lactate, milk Ethyl, butyl lactate, methyl-1,3-butylene glycol acetate, 1,3-butylene glycol-3-monomethyl ether, methyl 3-methoxypropionate. These can be used alone or in admixture of two or more. Specific examples of more preferable solvents include N-methylpyrrolidone, cyclopentanone, cyclohexanone, γ-butyrolactone, ethyl lactate, propylene glycol monomethyl ether, propylene glycol monoethyl ether, and PGMEA. The mass ratio of the resin composition to the solution is preferably 0.1 to 30% by mass from the viewpoint of forming a thin film.

  As a method of filling the openings, a method of applying the above solution by spin coating, bar coating, die coating, blade coating, curtain coating, spray coating, ink jet, or the like, a screen printing machine And a method of filling with a gravure printing machine, an offset printing machine or the like. From the viewpoint of easy control of the film thickness, spin coating is preferred, and the number of rotations at that time is preferably 30 rpm to 5000 rpm. Next, the substrate with the openings filled with the solution is dried by heating or vacuum drying with an air dryer, an oven, a hot plate, or the like to remove the solvent. The method for removing the solvent can be roughly classified into a method of transferring heat directly from the lower side of the substrate like a hot plate and a method of convection of a high-temperature gas like an oven. Next, the substrate is further heated to cause phase separation of the resin composition for hole shrink in the opening. This state is shown in FIG. As the resin composition for hole shrinkage is heated, the poly (meth) acrylate portion (Ib) is localized in the central portion of the opening, and the aromatic ring-containing polymer portion (Ia) and the aromatic ring-containing homopolymer are so surrounded as to surround it. As a general expression of the phase separation structure in which the polymer part (II) is formed, the former is an “island” part (indicated by C2 in FIG. 1 (c)), and the latter is an “sea” part (in FIG. 1 (c)). C1). In this case, it is preferable that the island portion has a cylinder structure that exists from the surface of the opening to the bottom.

  The process of FIG. 1 (b) and FIG. 1 (c) can be performed continuously, and directly from the lower side of the substrate like a hot plate rather than a method of convection of a hot gas like an oven. The method of transferring heat is preferable because phase separation proceeds in a shorter time and a sea-island structure can be obtained. The heating temperature is preferably 130 ° C. or higher and 280 ° C. or lower, more preferably 140 ° C. or higher and 270 ° C. or lower, and further preferably 150 ° C. or higher and 260 ° C. or lower. The heating time is 10 seconds or more and 100 hours or less, preferably 10 hours or less, more preferably 1 hour or less. In the case of a hot plate (direct heat transfer), it is preferably 10 seconds or longer and 1 hour or shorter, and more preferably 10 seconds or longer and 30 minutes or shorter. If the heating temperature is 130 ° C. or higher, a phase separation structure can be formed, and if it is 280 ° C. or lower, the decomposition of the polymer is suppressed. In the case of a hot plate (direct heat transfer), a phase separation structure can be formed if the heating time is 10 seconds or longer, and decomposition of the polymer is suppressed if it is 1 hour or shorter. The sea-island structure pattern can be obtained in a shorter time as the heating temperature is higher.

  The atmosphere during heating is not particularly limited, such as an inert gas such as nitrogen or argon, air, or vacuum. As shown in FIG. 1D, a micronized hole is formed by removing the phase-separated cylindrical island portion by etching. That is, hall shrink is realized. As an etching method, a dry etching method using a gas such as oxygen, argon, halogen gas, carbon tetrafluoride, or a wet etching method using an organic solvent or an aqueous solution is used. The etching can also be performed after irradiation with ultraviolet rays, electron beams, or the like.

Next, a method for evaluating the effect of the present invention will be described.
The electron micrograph of the board | substrate obtained through the said hall | hole shrink process of Fig.1 (a)-(d) is taken. The shape of all fine holes in an arbitrary rectangular area cut out in this is observed. Next, as shown in FIG. 2, the line segment that intersects with each miniaturized hole is determined to have the maximum length, the length is defined as Da, and this line segment is defined as the “major axis”, which is perpendicular to the major axis. Of the line segments intersecting with the miniaturized hole, the one with the maximum length is selected as the “short diameter”, and the length is set as Db. The absolute values of Da and Db are calculated from the scale of the electron micrograph. Here, the value of Da / Db is defined as “circular coefficient”, and the closer this value is to 1, the higher the circularity is determined. The average value of Da and Db is defined as “equivalent diameter”. The number of sample holes for this measurement is preferably in the range of 9-100. The effect of the present invention can be verified by obtaining the average value and standard deviation of the circular coefficient and equivalent diameter of all holes.

[Example 1: Synthesis of mixture of block copolymer (I) and aromatic ring-containing homopolymer (II)]
In a 1 L three-necked flask, 490 g of dehydrated and degassed tetrahydrofuran (hereinafter also referred to as THF) and a hexane solution (0.16 mol / L) of n-butyllithium (hereinafter also referred to as n-BuLi) as an initiator. ) 2.23 mL, 20.8 g of styrene dehydrated and degassed as a monomer was added, cooled to −78 ° C. under a nitrogen atmosphere and stirred for 30 minutes, and then a small amount of the reaction solution was extracted, and then dehydrated as a second monomer. Then, 8.6 g of degassed methyl methacrylate was added and stirred for 2 hours. Thereafter, the reaction solution was added to a container containing 3 L of denatured alcohol (Solmix AP-1 manufactured by Nippon Alcohol Sales Co., Ltd.) with stirring, the precipitated polymer was filtered, and vacuum dried at 80 ° C. for 3 hours.
From the analysis of homopolystyrene produced by adding the solution extracted after polymerizing styrene to methanol by GPC, and NMR and liquid chromatographic measurements of the product, this product has a molecular weight of PS of 114,000. , A polystyrene-polymethyl methacrylate (PS-b-PMMA) block copolymer (I) having a molecular weight of 44,000 and a total molecular weight of 150,000 and a mixture of 13% by mass of homopolystyrene (II) Thus, the ratio of (II) to (I) was found to be 15% by mass.
The GPC apparatus is HLC-8220 manufactured by Tosoh Corporation, the eluent is chloroform, the column is manufactured by Tosoh Corporation, and TSKgel-SuperHZ-2000 and TSKgel-SuperHZM-N are connected in series. The column temperature was 40 ° C. and the flow rate was 1.0 mL per minute. TSK Standard polystyrene (12 samples) manufactured by Tosoh Corporation was used as a standard substance for molecular weight calibration.
For measurement of NMR, JNM-GSX400 manufactured by JEOL Ltd. was used with methylene dichloride as a solvent.

  The liquid chromatography apparatus used was LC-VP manufactured by Shimadzu Corporation, the column was Imtakt, Cadenza CD-C18 (4.6 mm ID x 100 mm), and an acetonitrile / THF mixture was used as the mobile phase. Used, eluting at a flow rate of 0.5 mL per minute at 40 ° C., and the gradient conditions are those where the mixing ratio of acetonitrile / THF was continuously changed from 70/30 to 30/70 over 15 minutes, and detection Was performed with UV light having a wavelength of 220 nm, and quantified using a calibration curve using TSK standard polystyrene manufactured by Tosoh Corporation.

[Extraction process of the homopolystyrene (II) from the block copolymer (I) containing the homopolystyrene (II) as a by-product]
To a 300 mL three-necked flask, 3.0 g of the block copolymer (I) synthesized as described above (including homopolystyrene (II) as a by-product) and 150 g of cyclohexane were added, and a reflux tube was attached. Stir for hours. Thereafter, the insoluble matter was filtered and dried under reduced pressure. When this product was analyzed by liquid chromatography, the ratio of (II) to (I) was 2% by mass.

A resin composition composed of block copolymer (I) and homopolystyrene (II), synthesized by the above method and extracted from homopolystyrene, in which the ratio of (II) to (I) is 2% by mass is dissolved in PGMEA. Then, a 1.0 mass% solution was prepared, and the obtained solution was spin-coated on a substrate having a hole with a diameter of 90 nm. Thereafter, pre-baking was performed at 110 ° C. for 90 seconds, and the polymer composition was buried in the substrate hole. Next, it heat-processed for 10 minutes on the hotplate set to 190 degreeC, and cooled at room temperature. The wafer was etched with oxygen plasma using a plasma etching apparatus EXAM (manufactured by Shinko Seiki Co., Ltd.) at a pressure of 60 Pa and a power of 133 W, and a field emission scanning electron microscope (FE-SEM) S-4800 (Hitachi Co., Ltd.). The formed fine holes were observed using a high technology.
Enlarging this electron micrograph, for the miniaturized holes in a total of 20 substrate holes in 4 rows and 5 columns, using a ruler, 20 sets of long diameter (Da) and short diameter (Db) were obtained by the above-described method, The equivalent diameter (Dc) and the circular coefficient (Da / Db), which are average values, were calculated. The average and standard deviation of the equivalent diameters of 20 samples were 44 ± 4.5 nm at 44 nm and 4.5 nm. The average and standard deviation of the circular coefficients are 1.11 and 0.08, respectively, and are expressed as 1.11 ± 0.08, and fine holes having good circularity and uniform equivalent diameter were formed. It was confirmed.

[Comparative Example 1]
Except that the homopolystyrene (II) was not extracted from the mixture of the block copolymer (I) and the homopolystyrene (II) synthesized as described above, a miniaturized hole was formed and the shape was measured in the same manner as in Example 1. did. As a result, the average of the equivalent diameters of 20 samples was 33 ± 3.5 nm and the circular coefficient was 1.49 ± 0.23, which was an undesirable circularity.

[Example 2]
A miniaturized hole was formed in the same manner as in Example 1 except that the plasma was etched with carbon tetrafluoride at a pressure of 25 Pa and a power of 133 W instead of oxygen plasma, and the shape thereof was measured. When 20 samples were taken from the electron micrograph and measured, the average equivalent diameter was 21 ± 2.2 nm and the circular coefficient was 1.07 ± 0.10. Both the circularity and the variation in equivalent diameter were good results.

[Comparative Example 2]
Except that the homopolystyrene (II) was not extracted from the mixture of the block copolymer (I) and the homopolystyrene (II) synthesized as described above, a miniaturized hole was formed and the shape was measured in the same manner as in Example 2. did. As a result, of the 20 samples, 2 samples did not have fine holes. The average of the equivalent diameters of the remaining 18 samples was 14 ± 5.8 nm, and the variation was very large. The circularity coefficient was 1.14 ± 0.15, and the circularity decreased compared to Example 2.

  If the resin composition for hole shrink according to the present invention is used, circularly refined holes with uniform dimensions can be obtained. Therefore, the present invention can be suitably used as a resin composition for forming a pattern of the most advanced microstructure of a semiconductor.

A1 Layer having an opening A2 Substrate B1 Resin composition for hole shrinking C1 Self-organized structure “sea” portion C2 Self-organized structure “island” portion D1 Refined hole Da Longer diameter of refined hole Db Shortened refined hole Diameter

Claims (9)

below:
Block copolymer (I) comprising an aromatic ring-containing polymer and poly (meth) acrylate as a block portion, wherein the molecular weight of the block copolymer (I) is from 10,000 to 1,000,000, based on the entire block copolymer (I) The total ratio of the aromatic ring-containing polymer portion (Ia) and the poly (meth) acrylate portion (Ib) is 50 mol% or more, and the aromatic ring-containing polymer portion (Ia): the poly (meth) acrylate portion (Ib) The repeating unit constituting the aromatic ring-containing polymer part (Ia) of the block copolymer (I) as a by-product in the synthesis of the block copolymer (I) is 1: 1 to 10: 1 An aromatic ring having a molecular weight equal to or higher than the molecular weight of the aromatic ring-containing polymer part (Ia) of the block copolymer (I). Moporima (II);
A resin composition for whole shrink, comprising a ratio of the aromatic ring-containing homopolymer (II) to the block copolymer (I) in the composition of more than 0% by mass and 10% by mass or less. The resin composition for hall shrink.   The resin composition for hall shrinks of Claim 1 whose ratio of the said aromatic ring containing homopolymer (II) with respect to the said block copolymer (I) is more than 0 mass% and 5 mass% or less.   The resin composition for whole shrink according to claim 2, wherein a ratio of the aromatic ring-containing homopolymer (II) to the block copolymer (I) is greater than 0% by mass and 2.5% by mass or less.   The resin composition for hall shrinks according to any one of claims 1 to 3, wherein the aromatic ring-containing polymer part (Ia) is an aromatic ring-containing vinyl polymer.   The resin composition for whole shrink according to claim 4, wherein the aromatic ring-containing vinyl polymer is polystyrene, and the poly (meth) acrylate moiety (Ib) is polymethyl methacrylate. The following steps:
Block copolymer (I) comprising an aromatic ring-containing polymer and poly (meth) acrylate as a block portion, wherein the molecular weight of the block copolymer (I) is from 10,000 to 1,000,000, based on the entire block copolymer (I) The total ratio of the aromatic ring-containing polymer portion (Ia) and the poly (meth) acrylate portion (Ib) is 50 mol% or more, and the aromatic ring-containing polymer portion (Ia): the poly (meth) acrylate portion (Ib) Of the block copolymer (I) as a by-product, and comprising a repeating unit constituting the aromatic ring-containing polymer part (Ia), the molecular weight of the block copolymer (I) Synthesizing a mixture of an aromatic ring-containing homopolymer (II) that is greater than or equal to the molecular weight of the aromatic ring-containing polymer part (Ia) of I); The obtained mixture is heated in an organic solvent that is a good solvent for the aromatic ring-containing homopolymer (II) to extract the aromatic ring-containing homopolymer (II), and (II) for (II) ) Is reduced to greater than 0% by mass and less than 10% by mass,
The manufacturing method of the resin composition for hole shrinks of any one of Claims 1-5 containing this.   The method according to claim 6, wherein the aromatic ring-containing homopolymer (II) is extracted at a temperature 20 ° C. or more lower than the boiling point of the organic solvent.   The method according to claim 7, wherein the aromatic ring-containing homopolymer (II) is extracted at a temperature 30 to 40 ° C lower than the boiling point of the organic solvent. The following steps:
Applying the resin composition for hole shrink according to any one of claims 1 to 5 to a substrate on which holes are formed,
In the hole, an island portion of the poly (meth) acrylate portion (Ib) of the block copolymer (I), an aromatic ring-containing polymer portion (Ia) of the block copolymer (I) and an aromatic ring-containing homopolymer ( II) is formed by heating the sea part, and the island part is removed by etching.
Including a hall shrink method.

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