KR20210040614A - Diblock copolymer containing gradient random-copolymer block and method for forming fine pattern using diblock copolymer - Google Patents

Abstract

Disclosed are a diblock copolymer including a block having a concentration gradient and a method of forming a fine pattern using the same. The block copolymer according to an embodiment of the present invention includes: a first block; and a second block comprising a random copolymer having a concentration gradient, wherein the first block may include polymethyl methacrylate (PMMA), and the second block may include a random copolymer having a concentration gradient of styrene (S) and pentafluorostyrene (PFS).

Description

Diblock copolymer containing gradient random-copolymer block and method for forming fine pattern using diblock copolymer}

The present invention relates to a double block copolymer, and more specifically, by including a block having a concentration gradient, it is possible to improve pattern alignment without performing a neutral brush polymer treatment on the floor, and to form a fine pattern with high resolution. The present invention relates to a double block copolymer and a method for forming a fine pattern using the same.

In order to increase the density of semiconductor integrated circuits in order to satisfy Moore's Law, the size of the device has been continuously reduced, but the size of the device has reached a size that cannot be reached by the optical lithography process, and new lithography methods are being studied. . Among them, directed self-assembly (DSA) technology using block copolymers is expected as a next-generation lithography process. (Republic of Korea Patent Publication No. 10-2016-0073408).

DSA technology has the advantage of simpler process and cost advantage over other optical-based lithography. It also has the advantage of being able to form various structures such as cylinders, lamellars, gyroids, and spherical structures according to the difference in structure of the block copolymer.

However, the block copolymer proposed so far is difficult to reduce the line width of the pattern to less than 10 nm, and to make a vertically oriented lamella structure, a neutral brush polymer having a composition suitable for the surface needs to be treated. Has difficulty. In addition, if the composition of the neutral brush polymer does not match, a vertically oriented lamellar structure is not formed, and accordingly, the neutral brush polymer affects defects in the pattern.

Accordingly, there is a need to develop a block copolymer having a pattern size of 10 nm or less and capable of forming a vertically oriented lamella pattern without a brush polymer.

The embodiments of the present invention include a block having a concentration gradient, thereby improving pattern alignment without performing a neutral brush polymer treatment on the floor, and forming a fine pattern having a high resolution, and a double block copolymer using the same. It provides a method of forming a fine pattern.

The block copolymer according to an embodiment of the present invention comprises a first block; And a second block including a random copolymer having a gradient of concentration.

The first block may include polymethyl methacrylate (PMMA), and the second block may include a random copolymer having a styrene (S) and pentafluorostyrene (PFS) concentration gradient.

The block copolymer may include the first block having a repeating unit represented by Formulas 1 to 2 below, and the second block having a repeating unit represented by Formulas 3 to 5 below.

[Formula 1]

[Formula 2]

[Formula 3]

[Formula 4]

[Formula 5]

(Wherein, in Formulas 1 to 5, R ₁ and R ₂ are an alkyl group having 1 to 6 carbon atoms including -CH3, -C2H5, and -C3H7, and an aryl group having 6 to 20 carbon atoms, and X ₁ to X ₅ Is independently of each other, -H, -F, an alkyl group having 1 to 10 carbon atoms in which at least one F is substituted, a cycloalkyl group having 3 to 10 carbon atoms in which at least one F is substituted, or a C 6 to 20 carbon atom in which at least one F is substituted It is an aryl group, but not all -H, and grad means a gradient, which means that the composition of the random block copolymer has a concentration gradient, and the concentration gradient ranges from 0 to 1.)

에서의 프로리 허긴스 파라미터(Flory-Huggins parameter, χ) 값이 0.01 내지 0.26일 수 있다.The block copolymer is 25

The Flory-Huggins parameter (χ) value of may be 0.01 to 0.26.

The block copolymer may form a vertically oriented lamellar pattern.

The lamellar pattern may be formed in a pattern size of 5 nm to 30 nm.

A method for forming a fine pattern according to an embodiment of the present invention includes forming a block copolymer including a random copolymer having a concentration gradient; And forming a pattern using the formed block copolymer.

The block copolymer includes a first block containing polymethyl methacrylate (PMMA); And a second block including a random copolymer having a concentration gradient of styrene (S) and pentafluorostyrene (PFS).

The block copolymer may include a first block having a repeating unit represented by Formulas 1 to 2 below and a second block having a repeating unit represented by Formulas 3 to 5 below.

[Formula 1]

[Formula 2]

[Formula 3]

[Formula 4]

[Formula 5]

(Wherein, in Formulas 1 to 5, R ₁ and R ₂ are an alkyl group having 1 to 6 carbon atoms including -CH3, -C2H5, and -C3H7, and an aryl group having 6 to 20 carbon atoms, and X ₁ to X ₅ Is independently of each other, -H, -F, an alkyl group having 1 to 10 carbon atoms in which at least one F is substituted, a cycloalkyl group having 3 to 10 carbon atoms in which at least one F is substituted, or a C 6 to 20 carbon atom in which at least one F is substituted It is an aryl group, but not all -H, and grad means a gradient, which means that the composition of the random block copolymer has a concentration gradient, and the concentration gradient ranges from 0 to 1.)

에서의 프로리 허긴스 파라미터(Flory-Huggins parameter, χ) 값이 0.01 내지 0.26일 수 있다.The block copolymer is 25

The Flory-Huggins parameter (χ) value of may be 0.01 to 0.26.

The block copolymer may form a vertically oriented lamellar pattern.

The lamellar pattern may be formed in a pattern size of 5 nm to 30 nm.

According to embodiments of the present invention, by including a block having a concentration gradient, pattern alignment can be improved and a fine pattern having high resolution can be formed without performing a neutral brush polymer treatment on the floor.

According to the embodiments of the present invention, a block copolymer including a block of a random composition having a concentration gradient, for example, a double block copolymer, is used in a range of 10 nm or less under a wide range of thickness conditions regardless of the composition of the surface. It is possible to form a vertically oriented lamellar pattern.

The present invention can be applied to a lithography field using a self-assembled pattern.

1 shows an exemplary view of a change in a thickness range in which vertical orientation is possible and a change in a neutral brush composition according to a block copolymer composition.
FIG. 2 shows an exemplary diagram comparing the difference in surface energy between a vertically oriented lamella pattern and a horizontal oriented lamella pattern in a random composition (Example 1) and a concentration gradient composition (Example 2).
FIG. 3 shows an exemplary view of dry etching a block copolymer having a concentration gradient on various surfaces after annealing in a heating process.
4 is a flowchart illustrating an operation of a method for forming a fine pattern according to an exemplary embodiment of the present invention.

Advantages and features of the present invention, and a method of achieving them will become apparent with reference to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in a variety of different forms, only the present embodiments are intended to complete the disclosure of the present invention, and common knowledge in the technical field to which the present invention pertains. It is provided to completely inform the scope of the invention to those who have, and the invention is only defined by the scope of the claims.

The terms used in the present specification are for describing exemplary embodiments, and are not intended to limit the present invention. In this specification, the singular form also includes the plural form unless specifically stated in the phrase. As used herein, "comprises" and/or "comprising" refers to the presence of one or more other components, steps, actions and/or elements in which the recited component, step, operation and/or element is Or does not preclude additions.

Unless otherwise defined, all terms (including technical and scientific terms) used in the present specification may be used with meanings that can be commonly understood by those of ordinary skill in the art to which the present invention belongs. In addition, terms defined in a commonly used dictionary are not interpreted ideally or excessively unless explicitly defined specifically.

Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the accompanying drawings. The same reference numerals are used for the same elements in the drawings, and duplicate descriptions for the same elements are omitted.

The "alkyl group" described in the present invention means a monovalent organic radical including both straight chain or branched form. "Aryl group" is a monovalent organic radical derived from an aromatic hydrocarbon by the removal of one hydrogen, and a single or fused ring system containing 4 to 7, preferably 5 or 6 ring atoms suitably in each ring It includes, and includes a form in which a plurality of aryls are connected by a single bond. Specific examples of the aryl group include aromatic groups such as phenyl, naphthyl, biphenyl, indenyl, fluorenyl, phenanthrenyl, anthracenyl, triphenylenyl, pyrenyl, chrysenyl, and naphthacenyl. .

The material most frequently used as a block copolymer material for DSA technology is polystyrene-b-polymethylmethacrylate block copolymer (PS-b-PMMA). PS-b-PMMA has the advantage of excellent pattern aspect ratio and excellent vertical orientation characteristics. However, PS-b-PMMA has a disadvantage in that it cannot form a pattern of 10 nm or less, and vertical orientation is possible only by applying a neutral brush layer on the bottom.

This is because PS-b-PMMA has a low Flory-Huggins parameter (χ) value, which has a direct relationship with the pattern formation of the block copolymer. That is, although the χN value, which is the product of the number of polymer repeating units (N) and the χ value, must exceed 10.5, a self-assembled pattern can be obtained. If the value of N is decreased, the value of χN becomes smaller than 10.5, and a self-assembled pattern cannot be obtained.

In addition, through a patent already filed by the present applicant, when the block copolymer has a χ value (middle-χ) in a specific range, it is possible to form a vertically oriented lamella pattern of a target line width, and F is substituted by one or more. When a styrene group is used in an appropriate amount, a block copolymer having a χ value in a specific range can be formed (Korean Patent Laid-Open No. 10-2018-0033084).

At this time, in the case of the material used, poly(strene-random-pentafluorostyrene)-b-polymethylmethacrylate (P(S-co-PFS)-b-PMMA), as the composition of PFS increases, It has a disadvantage in that the range of the vertically oriented thickness is reduced, and it is difficult to match the neutral brush composition.

Embodiments of the present invention, by including a block having a concentration gradient, to improve pattern alignment without performing a neutral brush polymer treatment on the floor, and to form a fine pattern having a high resolution is the gist.

That is, the present invention is to improve the properties of the block copolymer by adding a random composition having a concentration gradient to one block of the double block copolymer, and furthermore, the form of a film produced using such a block copolymer and Fine patterns can be formed.

1 shows an exemplary view of a change in a thickness range in which vertical orientation is possible and a change in a neutral brush composition according to a block copolymer composition.

As shown in FIG. 1, when a neutral brush is used, the vertical alignment thickness range is narrow, whereas the block copolymer made by the present invention does not require a neutral brush layer, and the thickness condition for vertical alignment is also widened. It can be seen that, through this, the effect of the block copolymer having a concentration gradient can be confirmed.

The reason for this phenomenon is that when self-assembly is attempted using a block copolymer having a concentration gradient, unlike in the case of a random composition, as shown in Example 1 of FIG. 2, a horizontally oriented lamella is preferred. As shown in Example 2, it can be seen that in the condition having a concentration gradient, the surface energy of the vertically oriented lamella pattern decreases compared to the horizontal oriented lamella, so that the vertical orientation is preferred.

Specifically, the block copolymer according to the present invention is a double block copolymer having a first block having a repeating unit represented by the following Formulas 1 and 2 and a second block having a repeating unit represented by Formulas 3, 4, and 5. I can.

[Formula 1]

[Formula 2]

[Formula 3]

[Formula 4]

[Formula 5]

In Formulas 1 to 5, R ₁ and R ₂ are an alkyl group having 1 to 6 carbon atoms and an aryl group having 6 to 20 carbon atoms including -CH3, -C2H5, -C3H7, and the like. X ₁ to X ₅ are independently of each other, -H, -F, an alkyl group having 1 to 10 carbon atoms in which one or more F is substituted, a cycloalkyl group having 3 to 10 carbon atoms in which one or more F is substituted, or one or more F is substituted It is an aryl group having 6 to 20 carbon atoms, but not all -H. grad is an abbreviation for gradient, meaning that the composition of the random block copolymer has a concentration gradient. In this case, the concentration gradient may be from 0 to 1, may be from 1 to 0, and a concentration gradient condition between them is also possible. The average concentration fraction of the random copolymer having a concentration gradient can be varied.

As described above, the double block copolymer including the first block satisfying Formulas 1 and 2 and the second block satisfying Formulas 3, 4, and 5 has excellent vertical orientation characteristics, and is thus vertical by a very short self-assembly process. Oriented lamellar patterns can be formed, and nano-patterns that are almost perfectly aligned on a large-area substrate can be formed. In addition, it has the advantage that vertical orientation is possible regardless of the surface material. In this case, the self-assembly process may be used without particular limitation as long as it is a method commonly used in the art to spontaneously self-assemble the block copolymer, and as an example, thermal annealing, solvent annealing, or a mixture thereof Can be done.

The number average molecular weight of the double block copolymer according to an example of the present invention may be 3,000 to 500,000 g/mol, preferably 5,000 to 300,000 g/mol, as a non-limiting example. The polydispersity index (PDI, = Mw/Mn) of the block copolymer may be 1.5 or less, preferably 1.0 to 1.2, as a non-limiting example. The polydispersity index means a value obtained by dividing the weight average molecular weight by the number average molecular weight, and can be usually measured by size exclusion chromatography (SEC or GPC), and calculated through measurement conditions known in the art. Can be.

When the number average molecular weight and the polydispersity index are satisfied, it may be preferable in that a vertically oriented lamella pattern can be obtained even on a large-area substrate, but the present invention is not limited to the numerical range.

In addition, the unit of the additive not specifically described in the detailed description of the present invention may be a weight %.

[Example 1]

Referring to the process of an embodiment of synthesizing the block copolymer of the present invention, AIBN (Azobisisobutyronitrile), RAFT reagent (cyanoisopropyl dithiobenzoate), and methyl methacrylate are dissolved in benzene in a molar ratio of 2:1:10000 (total concentration: 50% by weight) and reacted at 80° C. for 1 hour in a nitrogen atmosphere to synthesize a large initiator (number average molecular weight: 11,500, molecular weight distribution: 1.13). Then, a giant initiator, ACHN (1,1'-Azobis (cycolohexanecarbonitrile)), styrene (S), and pentafluorostyrene (PFS) were dissolved in chlorobenzene at a molar ratio of 1:0.2:900:100 (total concentration: 50 Wt%), and reacting at 100° C. for 1 hour in a nitrogen atmosphere to a first block containing polymethyl methacrylate (PMMA) and a second including a random copolymer having a styrene and pentafluorostyrene concentration gradient A double block copolymer consisting of blocks (number average molecular weight: 42,100 molecular weight distribution: 1.18) was synthesized.

At this time, the block copolymer synthesized in the present invention may have a Flory-Huggins parameter (χ) value of 0.01 to 0.26 at 25°C.

The method of synthesizing the double block copolymer of the present invention is not limited to the above-described method, and may be synthesized in a variety of ways including chaingrowth polymerization and step-growth polymerization. Here, as the chain polymerization method, RAFT (Reversible addition-fragmentation chain transfer), NMP (Nitroxide-mediated polymerization), ATRP (Atomic transfer radical polymerization), cation (Cationic polymerization) and anionic polymerization method (Anionic polymerization), radical polymerization ( Radical polymerization) and the like, and dehydration condensation reaction (Condensation) may be used as a step polymerization method.

The resulting diblock copolymer was analyzed using NMR to confirm the mole fraction of each repeating unit. If the molar ratio of B and C is tracked through NMR analysis during block copolymerization of the block copolymer thus made, it can be as shown in <Table 1> and <Table 2>, and Table 1 shows that the average PFS mole fraction is 41%. For the phosphorus gradient block copolymer, Table 2 is for the gradient block copolymer with an average PFS mole fraction of 67%.

Standardized chain length Molar fraction of PFS 0.216 62.5 0.354 56.3 0.801 47.2 One 40.5

Standardized chain length Molar fraction of PFS 0.429 82.8 0.807 74.2 One 67.1

In Tables 1 and 2, the mole fraction of PFS is a mole fraction of a pentafluorostyrene group (PFS) repeating unit, and specifically, means PFS mole number / (ST mole number + PFS mole number).

As shown in Table 1 above, a block copolymer in which a random copolymer having a concentration gradient was introduced according to the present invention was synthesized, and a diblock copolymer was prepared by adjusting the molar fraction of each repeating unit, as shown in FIG. 3. As described above, it can be seen that the block copolymer is formed on a silicon wafer, on a polystyrene brush, on a polymethyl methacrylate brush, or a pattern of a lamellar structure is formed regardless of the composition of the bottom. Here, FIG. 3 shows that a block copolymer having a concentration gradient on various surfaces is dry-etched after annealing by a heating process, and it can be seen that a vertically oriented lamella pattern is formed on all surfaces. In this case, the lamella pattern may be formed in a pattern size of 5 nm to 30 nm.

As described above, since the block copolymer according to the embodiment of the present invention includes blocks having a concentration gradient, pattern alignment can be improved and fine patterns having high resolution can be formed without performing a neutral brush polymer treatment on the floor. .

In addition, the block copolymer according to the embodiment of the present invention is a block copolymer including a block of a random composition having a concentration gradient, for example, a double block copolymer, in a wide range of thickness conditions regardless of the composition of the surface. Vertically oriented lamellar patterns of 10 nm or less can be formed.

Further, the block copolymer according to the present invention is not limited to the above-described double block copolymer, and may be synthesized as a triple block copolymer.

4 is a flowchart illustrating an operation of a method for forming a fine pattern according to an exemplary embodiment of the present invention.

Referring to FIG. 4, in the method of forming a fine pattern according to an embodiment of the present invention, a block copolymer including a random copolymer having a concentration gradient is formed (S410).

Here, in step S410, a block copolymer including a random copolymer having a concentration gradient may be formed on a substrate or on a neutral brush. The substrate may be used without particular limitation as long as it is commonly used in the art, and the substrate may be in the shape of a wafer or film, and physical properties, the substrate may be a rigid substrate or a flexible substrate. Crystallographically, the substrate may be monocrystalline, polycrystalline, or amorphous, or may be a mixed phase in which a crystalline and amorphous phase are mixed. When the substrate is a laminated substrate in which two or more layers are stacked, each of the layers may be monocrystalline, polycrystalline, amorphous or mixed independently of each other. Materially, the substrate can be an inorganic substrate. As a non-limiting example, a group 4 semiconductor including silicon (Si), germanium (Ge), or silicon germanium (SiGe); Group 3-5 semiconductors including gallium arsenide (GaAs), indium phosphorus (InP), or gallium phosphorus (GaP); Group 2-6 semiconductors including cadmium sulfide (CdS) or zinc telluride (ZnTe); Group 4-6 semiconductor including lead sulfide (PbS); And a laminated substrate in which two or more materials selected from these oxides form each layer, and may be preferably a Si substrate.

For example, the block copolymer synthesized in step S410 includes a first block containing polymethyl methacrylate (PMMA) and a random copolymer having a styrene (S) and pentafluorostyrene (PFS) concentration gradient. It may include a second block.

As another example, the block copolymer synthesized in step S410 is a double comprising a first block having a repeating unit represented by Formulas 1 and 2 and a second block having a repeating unit represented by Formulas 3, 4, and 5. It may be a block copolymer.

The block copolymer synthesized by step S410 may have a Flory-Huggins parameter (χ) value at 25° C. of 0.01 to 0.26, may form a vertically oriented lamella pattern, and the lamella pattern may be It can be formed in a pattern size of 5nm to 30nm.

When the block copolymer having the concentration gradient is formed in step S410, a fine pattern is formed using the block copolymer having the concentration gradient (S420).

As described above, although the embodiments have been described by the limited embodiments and drawings, various modifications and variations are possible from the above description to those of ordinary skill in the art. For example, the described techniques are performed in a different order from the described method, and/or components such as systems, structures, devices, circuits, etc. described are combined or combined in a form different from the described method, or other components Alternatively, even if substituted or substituted by an equivalent, an appropriate result can be achieved.

Therefore, other implementations, other embodiments, and those equivalent to the claims also fall within the scope of the claims to be described later.

Claims (12)

First block; And
A second block containing a random copolymer having a gradient of concentration
Block copolymer comprising a.
The method of claim 1,
The first block is
Including polymethyl methacrylate (PMMA),
The second block is
A block copolymer comprising a random copolymer having a concentration gradient of styrene (S) and pentafluorostyrene (PFS).
The method of claim 1,
The block copolymer is
A block copolymer comprising the first block having a repeating unit represented by Formulas 1 to 2 below and the second block having a repeating unit represented by Formulas 3 to 5 below.
[Formula 1]

[Formula 2]

[Formula 3]

[Formula 4]

[Formula 5]

(Wherein, in Chemical Formulas 1 to 5,
R ₁ and R ₂ are an alkyl group having 1 to 6 carbon atoms including -CH3, -C2H5, and -C3H7, and an aryl group having 6 to 20 carbon atoms,
X ₁ to X ₅ are independently of each other, -H, -F, an alkyl group having 1 to 10 carbon atoms in which one or more F is substituted, a cycloalkyl group having 3 to 10 carbon atoms in which one or more F is substituted, or one or more F is substituted It is an aryl group having 6 to 20 carbon atoms, but not all -H,
grad means a gradient, which means that the composition of the random block copolymer has a concentration gradient, and the concentration gradient ranges from 0 to 1.)
The method of claim 1,
The block copolymer is
25

A block copolymer, characterized in that the value of the Flory-Huggins parameter (χ) in is 0.01 to 0.26.
The method of claim 1,
The block copolymer is
Block copolymer, characterized in that to form a vertically oriented lamellar pattern.
The method of claim 5,
The lamella pattern is
Block copolymer, characterized in that formed in a pattern size of 5nm to 30nm.
Forming a block copolymer including a random copolymer having a gradient of concentration; And
Forming a pattern using the formed block copolymer
Fine pattern forming method comprising a.
The method of claim 7,
The block copolymer is
A first block comprising polymethyl methacrylate (PMMA); And
A second block comprising a random copolymer having a styrene (S) and pentafluorostyrene (PFS) concentration gradient
Fine pattern forming method comprising a.
The method of claim 7,
The block copolymer is
A method for forming a fine pattern, comprising: a first block having a repeating unit represented by the following Formulas 1 to 2 and a second block having a repeating unit represented by the following Formulas 3 to 5.
[Formula 1]

[Formula 2]

[Formula 3]

[Formula 4]

[Formula 5]

(Wherein, in Chemical Formulas 1 to 5,
R ₁ and R ₂ are an alkyl group having 1 to 6 carbon atoms including -CH3, -C2H5, and -C3H7, and an aryl group having 6 to 20 carbon atoms,
X ₁ to X ₅ are independently of each other, -H, -F, an alkyl group having 1 to 10 carbon atoms in which one or more F is substituted, a cycloalkyl group having 3 to 10 carbon atoms in which one or more F is substituted, or one or more F is substituted It is an aryl group having 6 to 20 carbon atoms, but not all -H,
grad means a gradient, which means that the composition of the random block copolymer has a concentration gradient, and the concentration gradient ranges from 0 to 1.)
The method of claim 7,
The block copolymer is
25

The method of forming a fine pattern, characterized in that the value of the Flory-Huggins parameter (χ) in is 0.01 to 0.26.
The method of claim 7,
The block copolymer is
A method of forming a fine pattern, characterized in that forming a vertically oriented lamellar pattern.
The method of claim 11,
The lamella pattern is
A method of forming a fine pattern, characterized in that formed in a pattern size of 5nm to 30nm.

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