KR20230117233A - Manufacturing method of thick film resist pattern, manufacturing method of thick film solution and processed substrate - Google Patents

Abstract

[Problem] To provide a method for producing a thick resist pattern.
[Solution] (1) Applying a resist composition on a substrate to form a resist layer from the resist composition;
(2a) exposing the resist layer to light;
(2b) forming a thickening layer by applying a thickening solution containing a polymer (A) and a solvent (B) on the resist layer; and
(3) a method of manufacturing a thick-film resist pattern, comprising a step of developing the resist layer and the thick-film layer.

Description

Manufacturing method of thick film resist pattern, manufacturing method of thick film solution and processed substrate

The present invention relates to a method of manufacturing a thick film resist pattern, a thick film solution used in the method, and a method of manufacturing a processing substrate.

In recent years, demands for higher integration of LSIs are increasing, and it is required to make resist patterns even finer. To meet these demands, lithography processes using KrF excimer laser (248 nm), ArF excimer laser (193 nm), extreme ultraviolet (EUV; 13 nm), short-wavelength X-rays, and electron beams have been put into practice.

In order to obtain a finer pattern, a method of covering a resist pattern formed in a range that can be stably obtained by a conventional method with a composition containing a polymer to thicken the resist pattern and hole diameter or to make the separation width finer is a method. There is (for example, Patent Document 1). This method mainly aims at thickening the width of a resist pattern, and further applies a composition containing a polymer after developing the resist pattern once.

In addition, while a thick film resist pattern with a high aspect ratio is required, a composition using a vinyl resin and an amine compound has also been developed (Patent Document 2).

JP 2014-170190 A JP 2017-165846 A

The inventors of the present application believe that there are at least one problem in the method of manufacturing a resist pattern that still needs improvement. This includes, for example: thickening the fine resist pattern; obtaining fine resist patterns useful as etching masks; obtaining sufficient resolution even using an exposure machine with an increased numerical aperture; obtaining micropatterns with good shapes; obtaining a resist pattern with a high aspect ratio; enlargement of the process window; Improvement in manufacturing yield.

The inventors of the present application have considered and examined as follows.

DOF (depth of focus) indicates the range of depth of focus in which a resist pattern can be formed with a dimension in which a difference from a target dimension falls within a predetermined range when exposure is performed by moving the focal point up and down with the same exposure amount.

DOF is represented by the following equation:

k2×λ/NA ²

In the above equation, k2 is a constant, λ is an exposure wavelength, and NA is a numerical aperture.

The larger the DOF, the wider the process window, which is preferable. However, in high-precision lithography techniques, such as IC, the NA of an exposure machine tends to gradually increase, and the DOF is expected to become narrower and narrower.

In EUV exposure, which is expected as a high-precision technology, formation of fine patterns composed of thin films is performed. The inventors of the present application considered that thickening the resist pattern is preferable for making the resist pattern more resistant when using the high-precision pattern as a mask in a subsequent process. If the resist pattern is thin, for example, when used as an etching mask, durability as a mask cannot be sufficiently achieved, and even an object to be masked may be scraped at the end of the etching process.

When the resist film thickness is thick, the process window tends to narrow. For example, if the focus is shifted due to a slight shift in the thickness of the substrate, the shape of the resist pattern to be formed may deviate from the rectangular shape, and pattern collapse may easily occur. As another example, if the dose is out of sync, there is a possibility that pattern bridge and pattern collapse may occur due to a shift in line width. In high-precision techniques requiring high resolution, thinner resist films are readily used.

The present invention is made on the basis of the above technical background, and provides a method for manufacturing a thick-film resist pattern and a thick-film solution used therein.

The method of manufacturing a thick-film resist pattern according to the present invention includes the following steps:

(1) applying a resist composition on a substrate to form a resist layer from the resist composition;

(2a) exposing the resist layer to light;

(2b) forming a thickening layer by applying a thickening solution containing a polymer (A) and a solvent (B) on the resist layer; and

(3) developing the resist layer and the thickening layer.

The manufacturing method of a processed substrate according to the present invention includes the following steps:

forming the thick-film resist pattern; and

(4) A processing step of using the thickened resist pattern as a mask.

According to the present invention, one or more of the following effects may be desirable:

thickening the fine resist pattern; obtaining fine resist patterns useful as etching masks; obtaining sufficient resolution even using an exposure machine with an increased numerical aperture; obtaining micropatterns with good shapes; obtaining a resist pattern with a high aspect ratio; enlargement of the process window; and improvement in manufacturing yield.

[Fig. 1] Fig. 1 is a diagram schematically showing one aspect of a method for manufacturing a thick-film resist pattern.

[Justice]

Unless specifically stated otherwise, the definitions and examples set forth in this paragraph apply.

The singular form includes the plural form, and “a” or “the” means “at least one”. An element of a concept may be expressed by a plurality of species, and when an amount (eg, mass % or mol %) is described, the amount refers to the sum of the plurality of species.

“And/or” includes any combination of any of the elements, and includes use of any of the elements alone.

When "to" or "-" is used to indicate a numerical range, it is inclusive of both endpoints and their units are common. For example, 5 to 25 mol% means 5 mol% or more and 25 mol% or less.

References such as "C _xy ", "C _x -C _y ", and "C _x " refer to the number of carbons in the molecule or substituent. For example, C _1-6 alkyl means an alkyl chain (methyl, ethyl, propyl, butyl, pentyl, hexyl, etc.) having 1 to 6 carbon atoms.

When the polymer has plural types of repeating units, the repeating units are copolymerized. The copolymerization may be any of alternating copolymerization, random copolymerization, block copolymerization, graft copolymerization, or a mixture thereof. When a polymer or resin is represented by a structural formula, n or m or the like written next to parentheses indicates the number of repetitions.

Celsius is used as the unit of temperature. For example, 20 degrees means 20 degrees Celsius.

The additive refers to the compound itself having its function (for example, in the case of a base generator, the compound itself that generates a base). An embodiment in which the compound is dissolved or dispersed in a solvent and added to the composition can also be used. As one aspect of the present invention, this solvent is preferably contained in the composition according to the present invention as solvent (B) or other component.

Hereinafter, aspects of the present invention will be described in detail.

<Method of manufacturing thick resist pattern>

The method of manufacturing a thick-film resist pattern according to the present invention includes the following steps:

(1) applying a resist composition on a substrate to form a resist layer from the resist composition;

(2a) exposing the resist layer to light;

(2b) forming a thickening layer by applying a thickening solution containing a polymer (A) and a solvent (B) on the resist layer; and

(3) developing the resist layer and the thickening layer.

Hereinafter, each step will be described with reference to the drawings. Although described for clarity, steps (1) and (2) are performed before step (3). Numbers in parentheses indicate the order. However, the order of (2a) and (2b) is arbitrary. the same below

step (1)

In step (1), a resist composition is applied on a substrate to form a resist layer.

Examples of substrates include silicon/silicon dioxide coated substrates, silicon nitride substrates, silicon wafer substrates, glass substrates and ITO substrates.

The resist composition is not particularly limited, but from the viewpoint of forming a fine resist pattern at high resolution, it is preferably a chemically amplified resist composition, and examples thereof include a chemically amplified PHS-acrylate hybrid EUV resist composition. It is also a preferred embodiment that the resist composition contains a photoacid generator. A suitable resist composition of the present invention is a positive type chemically amplified resist composition.

A typical high-resolution positive-type resist composition includes a combination of an alkali-soluble resin whose side chain is protected with a protecting group and a photoacid generator. When a resist layer formed of such a composition is irradiated with ultraviolet rays, electron beams, extreme ultraviolet rays, etc., the photoacid generator releases acid from the irradiated portion (exposed portion), and the protecting group bonded to the alkali-soluble resin is oxidized by the acid. dissociates (hereinafter referred to as deprotection). Since the deprotected alkali-soluble resin is soluble in an alkaline developer, it is removed by the development treatment. In the case of the present invention in which a thickening layer is formed on the resist layer, if a region of the lower resist layer is soluble, both the mixed layer and the resist layer in the region are removed. This will be explained later.

As the resist composition of the present invention, a negative type resist composition may be used. Known negative resist compositions and processes may be used. For example, by insolubilizing the polymer with a crosslinking agent or using an organic solvent in a developing solution, both the resist layer and the mixed layer in the unexposed region are removed.

The resist composition of the present invention is applied onto a substrate by an appropriate method. In the present invention, "on a substrate" includes a case of being applied directly on a substrate and a case of being applied through another layer. For example, a resist underlayer film (eg, spin on carbon (SOC) and/or an adhesion enhancement film) may be formed directly on the substrate, and the resist composition may be applied directly on the resist underlayer film. Preferably, the resist composition of the present invention is applied directly onto a substrate. Further, in another preferred embodiment, the SOC is formed directly on the substrate, the adhesion enhancement film is formed directly on the SOC, and the resist composition is applied directly on the adhesion enhancement film.

The application method is not particularly limited, but may include, for example, application by spin coating.

Preferably, a resist layer is formed on the substrate coated with the resist composition by heating. The heating is also referred to as prebaking, and is performed using, for example, a hot plate. The heating temperature is preferably 100 to 250°C, more preferably 100 to 200°C, still more preferably 100 to 160°C. The temperature is the heating surface temperature of the hot plate. The heating time is preferably 30 to 300 seconds, more preferably 30 to 120 seconds, still more preferably 45 to 90 seconds. The heating is preferably performed in an air or nitrogen gas atmosphere, more preferably in an air atmosphere.

1(i) is a schematic diagram in which a resist layer 2 is formed on a substrate 1 . The film thickness of the resist layer is selected depending on the intended purpose, but is preferably 10 to 100 nm, more preferably 10 to 40 nm, still more preferably 10 to 30 nm.

Step (2a)

In step (2a), the resist layer is exposed through a mask as needed.

The wavelength of the radiation (light) used for exposure is not particularly limited, but exposure with light having a wavelength of 13.5 to 248 nm is preferred. In particular, KrF excimer laser (wavelength: 248 nm), ArF excimer laser (wavelength: 193 nm), EUV (extreme ultraviolet light, wavelength 13.5 nm), and the like can be used. EUV light is more preferred. The above wavelength is allowed in the range of ±1%.

After exposure, post-exposure baking (PEB) may be performed if necessary. The temperature of PEB can be selected in the range of 70 to 150 °C, preferably 80 to 120 °C. The heating time of PEB can be selected in the range of 0.3 to 5 minutes, preferably 0.5 to 2 minutes.

Fig. 1(ii) is a schematic diagram showing a state in which the resist layer 2 is exposed through a mask in the case of using a general positive type chemically amplified resist composition. Acid is released from the photoacid generator into the exposure area 4 to deprotect the polymer and increase its alkali solubility. In the unexposed area 3, the alkali solubility of the polymer does not change.

Step (2b)

In step (2b), a thickening solution containing a polymer (A) and a solvent (B) is applied on the resist layer to form a thickening layer. In the present invention, a thickening solution is not applied between the resist patterns (after the resist layer is developed).

The application method is not particularly limited, but includes, for example, application by spin coating.

Preferably, by heating or spin-drying (more preferably by heating), a thickening layer is formed on the substrate on which the thickening solution is applied. Heating is performed using, for example, a hot plate. The heating temperature is preferably 45 to 150°C, more preferably 90 to 130°C. The heating time is preferably 30 to 180 seconds, more preferably 45 to 90 seconds. The heating is preferably performed in an air or nitrogen gas atmosphere, more preferably in an air atmosphere. Heating in step (2b) is also referred to as mixing bake.

The order of steps (2a) and (2b) may be any order. A process of performing step (2b) after step (2a) is more preferable because it is not necessary to pass through the thickening layer for exposure. A process of performing step (2a) after step (2b) can also be used, and in this case, it is preferable to perform exposure after adjusting the influence of the transmittance through the thickening layer.

1(iii) is a schematic diagram of a state in which a thickening layer 5 is formed on a resist layer 2 .

In step (2b), an insolubilization layer is preferably formed in a region near where the thickening layer and the resist layer contact each other. Without wishing to be bound by theory, it is thought that the mixed layer is formed by infiltrating (mixing) the respective polymers in the region where the thickening layer and the resist layer contact each other. Whether the mixed layer is soluble or insoluble in the developer in a subsequent development process depends on whether the underlying resist layer is soluble or insoluble in the developer. When the region of the lower resist layer is insoluble to the developer, the mixed layer becomes an insoluble layer. If the region of the lower resist layer is soluble in the developer, the mixed layer is also soluble.

An example of a positive type resist layer will be described. Since the exposed area of the resist layer is soluble in the developer, the resist layer (matrix component, preferably a polymer) that has penetrated into the mixed layer in the same area is dissolved, and the mixed layer is also dissolved. In addition, the exposed area of the resist layer below the mixed layer is also dissolved. On the other hand, the unexposed areas of the resist layer are insoluble to the developer (eg, not deprotected). Therefore, the resist layer that penetrates the mixed layer in the same area is insoluble, and the mixed layer is also insoluble. Also, unexposed regions of the resist layer below the mixed layer are not dissolved.

1(iv) is a schematic diagram of a state in which an insolubilization layer 6 is formed. A mixed layer is also formed in a dissolving region (exposed region in the case of a positive type), but is not shown in (iv) for convenience because it is dissolved and removed during development.

In the above step (2b), it is also preferable to perform cleaning after formation of the thickening layer to remove the upper part of the thickening layer (thickening layer above the mixed layer). For washing, a solvent having the same composition as the solvent (B) of the thickening solution may be used, and preferably water (eg, DIW) may be used. Cleaning in the present invention is different from the phenomenon described later. That is, the cleaning is not for dissolving the soluble region of the resist layer to form a resist pattern.

[Thickening solution]

The thickening solution according to the present invention comprises a polymer (A) and a solvent (B), and is used to thicken an applied resist layer prior to development of the resist layer. The thickening solution according to the present invention is not applied between resist patterns after development. However, "development" in the expression "after development" does not include development when an already removed resist layer is patterned. For example, in the case of a design in which resist patterning is continuously performed a plurality of times, the thickening solution of the present invention can be used to thicken a resist layer in a subsequent process even after the resist has been developed in a previous process.

(A) polymer

The polymer (A) used in the present invention is not particularly limited as long as it has excellent affinity with the resist pattern, and examples thereof include polyacrylic acid, vinyl resin and the like.

Preferably, polymer (A) is a polymer containing amino groups in repeating units. Herein, the amino group denotes a primary amino group (-NH ₂ ), a secondary amino group (-NHR) and a tertiary amino group (-NRR'). In the present application, the amino group also includes a nitrogen bonded to an adjacent element through a double bond, for example, -N=. These amino groups may be contained in the side chain of the repeating unit or may be contained in the main chain structure of the polymer.

Polymer (A) is preferably a polymer comprising at least one repeating unit selected from the group consisting of a repeating unit (A1) represented by formula (a1) and a repeating unit (A2) represented by formula (a2). An aspect in which the polymer (A) includes the repeating unit (A1) represented by the formula (a1) is more preferable.

The repeating unit (A1) represented by the formula (a1) is as follows.

[Formula (a1)]

In the above formula (a1),

R ¹¹ , R ¹² and R ¹³ are each independently H, C _1-4 alkyl or carboxy. R ¹¹ and R ¹² are preferably H. R ¹³ is preferably H or methyl, more preferably H.

L ¹¹ is a single bond or C _1-4 alkylene, preferably a single bond or methylene, more preferably a single bond.

R ¹⁴ is a single bond, H or C _1-5 alkyl, preferably a single bond, H, methyl, ethyl, n-propyl or n-butyl, more preferably a single bond, H or methyl. When R ¹⁴ is a single bond, it is bonded to R ¹³ .

R ¹⁵ is H, C _1-5 alkyl, C _1-5 acyl or formyl (-CHO), preferably H, methyl, ethyl, n-propyl, n-butyl, acetyl or formyl, more preferably H, methyl, ethyl or n-propyl, more preferably H or n-propyl.

At least one of -CH ₂ - in the alkyl of L ¹¹ , the alkyl of R ¹⁴ , and the alkyl or acyl of R ¹⁵ may each independently be replaced by -NH-. Preferably, one of -CH ₂ - in the alkyl or acyl of R ¹⁵ is replaced by -NH-. An embodiment in which -NH- is not replaced is also preferable.

A single bond of R ¹⁴ or an alkyl of R ¹³ may be bonded together to form a saturated or unsaturated heterocycle. Preferably, a single bond of R ¹⁴ and an alkyl of R ¹³ may be bonded together to form a saturated heterocycle. The aspect in which a heterocycle is not formed is also preferable.

The alkyl of R ¹⁴ and the alkyl, acyl or formyl of R ¹⁵ may be bonded together to form a saturated or unsaturated heterocycle. Preferably, the alkyl of R ¹⁴ and the alkyl of R ¹⁵ are bonded together to form an unsaturated heterocycle. -CH ₂ - of R ¹⁴ and/or R ¹⁵ used for bonding may be replaced with -NH-. The aspect in which a heterocycle is not formed is also preferable.

m11 and m12 are each independently a number from 0 to 1, preferably 0 or 1, more preferably 0.

The repeating unit of polyvinylimidazole (P1) described later is explained with reference to formula (a1). m11 = m12 = 0. R ¹¹ , R ¹² and R ¹³ are H. L ¹¹ is a single bond. R ¹⁴ is methyl. R ¹⁵ is C ₃ alkyl (n-propyl), and one of -CH ₂ - is replaced by -NH-. In addition, an unsaturated heterocycle (imidazole) is formed by combining the alkyl of R ¹⁴ and the alkyl of R ¹⁵ .

The repeating unit of polyallylamine (P2) described later is explained with reference to formula (a1). m11 = m12 = 0. R ¹¹ , R ¹² and R ¹³ are H. L ¹¹ is methylene. R ¹⁴ and R ¹⁵ are H.

The repeating unit of the vinylpyrrolidone-vinylimidazole copolymer (P3) described later is explained with reference to formula (a1). The polymer having (A1) has two types of repeating units, each of which is represented by formula (a1). The relevant part of vinyl imidazole is the same as that of P1 above. Relevant portions of vinylpyrrolidone are described. m11 = m12 = 0. R ¹¹ , R ¹² and R ¹³ are H. L ¹¹ is a single bond. R ¹⁴ is C ₂ alkyl(ethyl). R ¹⁵ is C ₂ acyl (CH ₃ -CO-, acetyl). The alkyl of R ¹⁴ and the acyl of R ¹⁵ are bonded together to form a saturated heterocycle (2-pyrrolidone). This is a random copolymerization of a vinyl imidazole-corresponding moiety and a vinylpyrrolidone-corresponding moiety in a repeating unit ratio of 4:6.

The repeating units of the following polydiallylamine are explained with reference to formula (a1). m11 = m12 = 1. R ¹¹ and R ¹² are H. L ¹¹ is methylene and R ¹³ is methyl. R ¹⁴ is a single bond, and R ¹⁴ combines with R ¹³ to form a saturated heterocycle. R ¹⁵ is H.

The following repeating units are explained with reference to formula (a1). m11 = m12 = 0. R ¹¹ , R ¹² and R ¹³ are H. L ¹¹ is a single bond. R ¹⁴ is C ₄ alkyl (n-butyl). R ¹⁵ is C ₂ acyl (CH ₃ -CO-, acetyl). The alkyl of R ¹⁴ and the acyl of R ¹⁵ are bonded together to form a saturated heterocycle.

Examples of polymers having (A1) include polyvinylimidazole, polyvinylamine, polyallylamine, polydiallylamine and vinylpyrrolidone-vinylimidazole copolymers. Polymer (A) may be a copolymer having two or more types of (A1), examples thereof include vinylpyrrolidone-vinylimidazole copolymer and poly(allylamine-co-diallylamine). The repeating unit contained in the polymer having (A1) is 1 type or 2 types, more preferably 1 type. When a copolymer is used, it is preferable that the repeating unit contained in the polymer having (A1) is two types.

The repeating unit (A2) represented by the formula (a2) is as follows.

[Formula (a2)]

In the above formula (a2),

Each R ²¹ is independently H, a single bond, C _1-4 alkyl or carboxy (-COOH), preferably H, a single bond or methyl, more preferably H or a single bond, still more preferably is H. A single bond of R ²¹ is used as a repeating unit for another repeating unit (A2). H or the like may be bonded to a single bond not used at the end of the polymer.

R ²² , R ²³ , R ²⁴ and R ²⁵ are each independently H, C _1-4 alkyl or carboxy, preferably H or methyl, more preferably H.

m21 is a number from 0 to 3, preferably 0 or 1, more preferably 1.

Examples of polymers with (A2) include polyethyleneimine. The polyethyleneimine may be linear or branched, with linear being more preferred.

Linear polyethyleneimines are described with reference to formula (a2). m21 = 1, and R ²¹ , R ²² , R ²³ , R ²⁴ and R ²⁵ are H.

Branched polyethyleneimines are described with reference to formula (a2). m21 = 1, and R ²¹ is H or a single bond. R ²² , R ²³ , R ²⁴ and R ²⁵ are H.

Polymer (A) may be a copolymer having two or more types of (A2). Preferably, the repeating unit contained in the polymer having (A2) is one or two types, more preferably one type. Polymer (A) may be a copolymer having (A1) and (A2).

The polymer (A) may be appropriately selected from the above in view of the type of resist composition to be applied, the availability of the polymer, etc., and is preferably polyvinylimidazole, polyvinylamine, polyallylamine, or polydiallyl. It is selected from the group consisting of amines, polyethyleneimines, vinylpyrrolidone-vinylimidazole copolymers and poly(allylamine-co-diallylamine).

Polymer (A) may be a copolymer containing repeating units not containing an amino group, as long as the scope of the present invention is not impaired. For example, copolymers containing polyacrylic acid, polymethacrylic acid, polyvinyl alcohol and the like as copolymerized units can be mentioned.

Considering affinity with the polymer in the resist, the number of repeating units not containing an amino group is preferably 50 mol% or less, more preferably 30 mol% or less, based on all repeating units constituting the polymer (A). , more preferably 5 mol% or less. It is also a preferred embodiment of the present invention that the repeating unit not containing an amino group is 0 mol% (not contained).

The mass average molecular weight of the polymer (A) is preferably 5,000 to 200,000, more preferably 5,000 to 150,000, still more preferably 6,000 to 10,000. In the present invention, the mass average molecular weight (Mw) means the mass average mass molecular weight in terms of polystyrene measured by gel permeation chromatography.

The content of the polymer (A) is preferably 1 to 30% by mass, more preferably 1 to 20% by mass, still more preferably 2 to 10% by mass based on the total mass of the film thickening solution.

The thickening solution contains polymer (A), but may contain any polymer other than polymer (A) (preferably, a polymer having repeating units not containing amino groups). The content of the polymer other than the polymer (A) is preferably 0 to 20% by mass, more preferably 0 to 10% by mass, still more preferably 0 to 5%, based on the total mass of the film thickening solution. More preferably, it is 0 mass % (aspect which does not contain polymers other than polymer (A)).

(B) solvent

The solvent (B) is for dissolving the polymer (A) and other components used as needed. These solvents need not dissolve the resist layer. Solvent (B) preferably comprises water. The water is preferably deionized water (DIW). Since the solvent (B) is used for forming a fine resist pattern, it is preferable that the solvent (B) contains few impurities. A preferable solvent (B) has impurities of 1 ppm or less, more preferably 100 ppb or less, still more preferably 10 ppb or less. It is also a preferred embodiment of the present invention to prepare a thick film solution by filtering a solution in which solutes are dissolved for use in microprocessing.

The water content is preferably 80 to 100% by mass, more preferably 90 to 100% by mass, still more preferably 98 to 100% by mass, and even more preferably, based on the total mass of the solvent (B). It is 100 mass %. In a preferred embodiment of the present invention, solvent (B) consists essentially of only water. However, an embodiment in which an additive is contained in the thickening solution according to the present invention in a state of being dissolved and/or dispersed in a solvent other than water (eg, surfactant) is also acceptable as a preferred embodiment of the present invention.

Exemplary embodiments of solvent (B) other than water suitably include cyclohexanone, cyclopentanone, propylene glycol monomethyl ether (PGME), propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, Propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol 1-monomethyl ether 2-acetate (PGMEA), propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, γ-butyrolactone, ethyl lactate or these mixtures of any of them. These are preferable from the point of storage stability of a solution. Two or more of the above solvents may be mixed and used.

The content of the solvent (B) is preferably 70 to 99% by mass, more preferably 80 to 99% by mass, still more preferably 90 to 98% by mass based on the total mass of the film thickening solution.

The pH of the entire thickening solution of the present invention is preferably 5 to 12, more preferably 7 to 12, still more preferably 9 to 12.

(C) acid

The thickening solution according to the present invention may further include an acid (C). Without wishing to be bound by theory, it is believed that the incorporation of acid (C) can adjust the pH of the thickening solution, which tends to be basic due to polymer (A). It is believed to be able to inhibit dissolution of the polymer in the partially deprotected resist layer present on the surface of the resist layer.

Acid (C) comprises sulfonic acid, carboxylic acid, sulfuric acid, nitric acid or a mixture of at least any two thereof, preferably sulfonic acid, sulfuric acid or nitric acid, more preferably sulfonic acid or nitric acid. Examples of the sulfonic acid include p-toluenesulfonic acid, benzenesulfonic acid, p-dodecylbenzenesulfonic acid, 1,4-naphthalenedisulfonic acid and methanesulfonic acid, preferably p-toluenesulfonic acid. Examples of carboxylic acids include acetic acid, formic acid, oxalic acid, maleic acid, fumaric acid, o-phthalic acid and succinic acid.

The pH of the entire thickening solution of the present invention can be adjusted by the amount of acid (C) added. As the acid (C), it is preferable not to use an acid strong enough to modify the resist film. For example, it is preferable that the resist film is not deprotected by acid (C).

The content of the acid (C) is preferably 0 to 20% by mass, more preferably 0 to 15% by mass, still more preferably 0.1 to 10% by mass, and even more, based on the total mass of the film thickening solution. Preferably it is 0.1-5 mass %. An embodiment in which the film thickening solution does not contain acid (C) (0% by mass) is also a preferred embodiment of the present invention.

(D) surfactant

The thickening solution according to the present invention may further include a surfactant (D). Coatability may be improved by including the surfactant (D). Examples of surfactants that can be used in the present invention include (I) anionic surfactants, (II) cationic surfactants or (III) nonionic surfactants, more specifically (I) alkyl sulfonates, alkyl Benzene sulfonic acid and alkyl benzene sulfonates, (II) lauryl pyridinium chloride and lauryl methyl ammonium chloride and (III) polyoxyethylene octyl ether, polyoxyethylene lauryl ether, polyoxyethylene acetylene glycol ether, fluorine-containing surfactants (eg Fluorad (3M), Megafac (DIC), Surflon (AGC)) and organosiloxane surfactants (eg KF-53, KP341 (Shinetsu Chemical Industry)).

These surfactants may be used alone or in combination of two or more of them.

The content of the surfactant (D) is preferably 0 to 5% by mass, more preferably 0.001 to 2% by mass, still more preferably 0.01 to 1% by mass based on the total mass of the film thickening solution. An aspect (0% by mass) in which the film thickening solution does not contain the surfactant (D) is also an aspect of the present invention.

(E) additives

The film thickening solution according to the present invention may further include an additive (E) in addition to the above components (A) to (D). Additives (E) are preferably plasticizers, crosslinking agents, antibacterial agents, bactericides, preservatives, antifungal agents, bases or mixtures of any of these. Preferably, additive (E) comprises a base, more preferably consists of a base. The base is a low molecular weight compound unlike the polymer (A) containing an amino group. The molecular weight of the low molecular weight compound is 50 to 200, preferably 70 to 150, more preferably 100 to 125.

Examples of such bases include tertiary amines, diamines, and amine compounds having a cage-like three-dimensional structure.

Examples of the diamine compound include N,N,N',N'-tetramethylethylene diamine,

N,N,N',N'-tetraethylethylene diamine;

N,N,N',N'-tetrapropylethylene diamine;

N,N,N',N'-tetraisopropylethylene diamine;

N,N,N',N'-tetramethyl-1,2-propylene diamine;

N,N,N',N'-tetraethyl-1,2-propylene diamine;

N,N,N',N'-tetrapropyl-1,2-propylene diamine;

N,N,N',N'-tetraisopropyl-1,2-propylene diamine;

N,N,N',N'-tetramethyl-1,3-propylene diamine;

N,N,N',N'-tetraethyl-1,3-propylene diamine;

N,N,N',N'-tetrapropyl-1,3-propylene diamine;

N,N,N',N'-tetraisopropyl-1,3-propylene diamine;

N,N,N',N'-tetramethyl-1,2-butylene diamine;

N,N,N',N'-tetraethyl-1,2-butylene diamine;

N,N,N',N'-tetrapropyl-1,2-butylene diamine;

N,N,N',N'-tetraisopropyl-1,2-butylene diamine;

N,N,N',N'-tetramethyl-1,3-butylene diamine;

N,N,N',N'-tetraethyl-1,3-butylene diamine;

N,N,N',N'-tetrapropyl-1,3-butylene diamine;

N,N,N',N'-tetraisopropyl-1,3-butylene diamine;

N,N,N',N'-tetramethyl-1,4-butylene diamine;

N,N,N',N'-tetraethyl-1,4-butylene diamine;

N,N,N',N'-tetrapropyl-1,4-butylene diamine and

N,N,N',N'-tetraisopropyl-1,4-butylene diamine.

Examples of amine compounds having a cage-type three-dimensional structure include 1,4-diazabicyclo[2.2.2]octane, 2-methyl-1,4-diazabicyclo[2.2.2]octane, 1,4-diazabicyclo[ 2.2.2] octan-2-one, 1,4-diaza-2-oxabicyclo [2.2.2] octane, 1,5-diazabicyclo- [3.2.2] nonane, 1,5-diazabi Cyclo[3.3.2]decane and 1,5-diazabicyclo[3.3.3]undecane. An embodiment in which the base of additive (E) is 1,4-diazabicyclo[2.2.2]octane is a preferred embodiment of the present invention. Without wishing to be bound by theory, it is thought that the penetration of the thickening solution into the resist layer can be promoted by including the base of the additive (E), and the underlying resist layer is further expanded.

The content of the additive (E) is preferably 0 to 10% by mass, more preferably 0.001 to 5% by mass, still more preferably 0.01 to 4% by mass, and even more, based on the total mass of the film thickening solution. Preferably it is 0.1-3 mass %. An aspect (0% by mass) in which the film thickening solution according to the present invention does not contain the additive (E) is also a preferable aspect of the present invention.

step (3)

In step (3), the resist layer and the thickening layer are developed.

Examples of the method of applying the developer include a paddle method, a dip method, and a spray method. The temperature of the developing solution is preferably 5 to 50°C, more preferably 25 to 40°C, and the developing time is preferably 15 to 120 seconds, more preferably 30 to 60 seconds. After application of the developer, the developer is removed. The resist pattern after development may be subjected to cleaning treatment. The cleaning treatment may preferably be performed with water (DIW).

The developing solution is preferably an alkaline aqueous solution or an organic solvent, more preferably an alkaline aqueous solution. Examples of alkaline aqueous solutions are inorganic alkalis such as sodium hydroxide, potassium hydroxide, sodium carbonate and sodium silicate, organic amines such as ammonia, ethylamine, propylamine, diethylamine, diethylaminoethanol and triethylamine , and an aqueous solution containing a quaternary amine, such as tetramethylammonium hydroxide (TMAH), more preferably an aqueous TMAH solution, and even more preferably a 2.38% by mass TMAH aqueous solution. .

The surfactant may be further added to the developing solution.

Fig. 1(v) shows a state in which a developer is applied to the resist layer and the thickening layer, and the developer is removed to form a thickened resist pattern 7.

When (height of the resist pattern thickened) - (height of the resist pattern formed in the same manner except that the thickening solution is not applied) is taken as the thickening amount, the thickening amount is preferably 2 to 20 nm, more preferably is 2 to 15 nm, more preferably 3 to 10 nm, and even more preferably 3 to 8 nm. Without wishing to be bound by theory, thin resist films are common in high-precision lithography techniques, such as EUV exposure. However, it is considered that durability as a mask can be ensured when used as an etching mask in a later step, for example, by making the resist film thicker according to the present invention.

<Method of Manufacturing Substrate and Device>

The method for manufacturing a processed substrate according to the present invention includes the following steps:

Forming a thick resist pattern as described above; and

(4) A processing step of using the thickened resist pattern as a mask.

step (4)

In step (4), processing is performed using the thickened resist pattern as a mask.

The thick resist pattern is preferably used for processing a resist underlayer film or a substrate (more preferably a substrate). In particular, using a resist pattern as a mask, various substrates to be the lower layer material can be processed by a dry etching method, a wet etching method, an ion implantation method, a metal plating method, or the like. Since the resist pattern becomes thick, it can function as a mask even under severe conditions, and therefore it is preferably used for processing by a dry etching method.

When the resist underlayer film is processed using a thick-film resist pattern, the process can be performed step by step. For example, the resist pattern can be used to process the adhesion enhancement film and the SOC, and the SOC pattern can be used to process the substrate. As the adhesion enhancing film, for example, SiARC (Si antireflection coating) can be used.

A method of manufacturing a device according to the present invention includes the above method, and preferably further includes forming a wiring on a processing substrate. A known method can be applied on the processing substrate. Then, as needed, the board is cut into chips, connected to a lead frame, and packaged with resin. In the present invention, this packaged thing is referred to as a device. Examples of devices include semiconductor devices, liquid crystal display devices, organic EL display devices, plasma display devices, and solar cell devices. The device is preferably a semiconductor device.

[Example]

The present invention is described below with reference to various embodiments. Also, aspects of the present invention are not limited to these examples.

[Preparation of Thickening Solutions 1 to 3]

The polymer (A), surfactant (D) and base (E) listed in Table 1 are dissolved in solvent (B). Each content is as showing in Table 1. The numerical values in Table 1 are the contents (% by mass) of each component based on the total mass of the film thickening solution.

The resulting solution is stirred at room temperature for 60 minutes. After visually confirming that the solute is completely dissolved, the solution is filtered through a 0.2 μm fluoride resin filter to obtain thickening solutions 1 to 3.

in the table,

· P1: polyvinylimidazole (Mw: 30,000),

· P2: polyallylamine (Mw 8,000),

P3: Random copolymer of vinylpyrrolidone and vinylimidazole (m:n = 4:6, Mw: 25,000),

S1: acetylenic diol polyoxyalkylene ether having the following structure:

[Example 1]

The silicon substrate is treated with HMDS (hexamethyldisilazane) at 90° C. for 30 seconds. A chemically amplified PHS-acrylate hybrid resist composition (positive type) was applied on an HMDS-treated substrate by spin coating, and the substrate was heated on a hot plate at 110° C. for 60 seconds to form a resist layer with a film thickness of 35 nm. form Using an EUV exposure device (NXE: 3300B, ASML), the resist layer is exposed through a mask having a size of 18 nm (line:space = 1:1) while varying the exposure amount. Thereafter, post-exposure baking (PEB) is performed at 100° C. for 60 seconds. Thereafter, the thickening solution 1 was applied on the resist layer by spin coating to form a thickening layer, and heated at 130 DEG C for 60 seconds. Thereafter, paddle development was performed for 30 seconds using a 2.38% by mass TMAH aqueous solution as a developer, water was started dropwise while the developer was paddled on the substrate, and water was continuously dropped while rotating the substrate so that the developer was reduced to water. replace After that, the substrate was rotated at high speed to dry the thick resist pattern of Example 1.

For comparison, a resist pattern was formed without performing application of the thickening solution. In particular, a resist pattern was formed in the same manner as in Example 1 except that the application of the thickening solution and subsequent heating were not performed. This is shown as a comparative resist pattern.

[evaluation]

Chips of the substrates of each of the thick-film resist pattern and comparative resist pattern of Example 1 were formed, and their cross-sectional shapes were observed with an SEM (SU8230, Hitachi High-Tech Fielding), and the heights of the patterns were measured. (Height of thick resist pattern) - (Height of comparative resist pattern) is calculated as the thickening amount. The obtained results are shown in Table 2.

In Examples 2 and 3, the amount of film thickening was calculated in the same manner as in Example 1, except that the type of the thickening solution was changed as shown in Table 2. The obtained results are shown in Table 2.

1. Substrate
2. Resist layer
3. Unexposed area
4. Exposure area
5. Thickening layer
6. Insoluble layer
7. Thickened resist pattern
8. Height of thick resist pattern

Claims (15)

As a method of manufacturing a thick film resist pattern,
(1) applying a resist composition onto a substrate to form a resist layer from the resist composition (preferably by heating);
(2a) exposing the resist layer (preferably with EUV light);
(2b) applying a thickening solution containing a polymer (A) and a solvent (B) onto the resist layer to form a thickening layer (preferably by heating or spin-drying); and
(3) A method for producing a thickened resist pattern, including a step of developing the resist layer and the thickening layer (preferably with an alkaline aqueous solution or organic solvent, more preferably with an alkaline aqueous solution). The method of claim 1 , further comprising the step of removing an upper portion of the thickening layer by washing after forming the thicker layer in step (2b). The method according to claim 1 or 2, wherein in the step (2b), an insolubilization layer is formed in a region near where the thickening layer and the resist layer contact each other. The method for producing a thick-film resist pattern according to any one of claims 1 to 3, wherein the polymer (A) is a polymer containing an amino group in a repeating unit. The method according to any one of claims 1 to 4, wherein the polymer (A) is selected from the group consisting of a repeating unit (A1) represented by formula (a1) and a repeating unit (A2) represented by formula (a2) A method for producing a thick-film resist pattern comprising at least one repeating unit that is a polymer.
[Formula (a1)]

In the above formula (a1),
R ¹¹ , R ¹² and R ¹³ are each independently H, C _1-4 alkyl or carboxy (preferably H);
L ¹¹ is a single bond or C _1-4 alkylene;
R ¹⁴ is a single bond, H or C _1-5 alkyl;
R ¹⁵ is H, C _1-5 alkyl, C _1-5 acyl or formyl;
At least one of -CH ₂ - in the alkyl of L ¹¹ , the alkyl of R ¹⁴ , and the alkyl or acyl of R ¹⁵ may each independently be replaced by -NH-, and a single bond of R ¹⁴ or an alkyl and R ¹³ Alkyl of may be bonded together to form a saturated or unsaturated heterocycle, the alkyl of R ¹⁴ and the alkyl, acyl or formyl of R ¹⁵ may be bonded together to form a saturated or unsaturated heterocycle,
m11 and m12 are each independently a number of 0 to 1.
[Formula (a2)]

In the above formula (a2),
R ²¹ are each independently H, a single bond, C _1-4 alkyl or carboxy (preferably H);
R ²² , R ²³ , R ²⁴ and R ²⁵ are each independently H, C _1-4 alkyl or carboxy (preferably H);
m21 is a number from 0 to 3. The method according to any one of claims 1 to 5, wherein the polymer (A) is polyvinylimidazole, polyvinylamine, polyallylamine, polydiallylamine, polyethyleneimine, vinylpyrrolidone-vinylimide A method for producing a thick-film resist pattern selected from the group consisting of sol copolymers and poly(allylamine-co-diallylamine). According to any one of claims 1 to 3,
The solvent (B) contains water,
Preferably, the water content is 80 to 100% by mass (more preferably 90 to 100% by mass, still more preferably 98 to 100% by mass, even more) based on the total mass of the solvent (B). preferably 100% by mass),
Preferably, the content of the polymer (A) is 1 to 30 mass% (more preferably 1 to 20 mass%, still more preferably 2 to 10 mass%) based on the total mass of the film thickening solution. ), or
Preferably, the content of the solvent (B) is 70 to 99 mass% (more preferably 80 to 99 mass%, still more preferably 90 to 98 mass%) based on the total mass of the film thickening solution ), a method for producing a thick-film resist pattern. According to any one of claims 1 to 7,
The thickening solution further contains an acid (C),
Preferably, the content of the acid (C) is 0 to 20 mass% (more preferably 0 to 15 mass%, still more preferably 0.1 to 10 mass%) based on the total mass of the film thickening solution. , more preferably 0.1 to 5% by mass),
Preferably, the pH of the entire thickening solution is 5 to 12 (more preferably 5 to 10, still more preferably 6 to 9), or
Preferably, the acid (C) is sulfonic acid, carboxylic acid, sulfuric acid, nitric acid, or a mixture of any of them. According to any one of claims 1 to 8,
The thickening solution further comprises a surfactant (D),
Preferably, the content of the surfactant (D) is 0 to 5 mass% (more preferably 0.001 to 2 mass%, still more preferably 0.01 to 1 mass%) based on the total mass of the film thickening solution. %)ego,
Preferably, the thickening solution further comprises an additive (E),
Preferably, the additive (E) is a plasticizer, a crosslinking agent, an antibacterial agent, a bactericide, a preservative, an antifungal agent, a base or a mixture of any of these, or
Preferably, the content of the additive (E) is 0 to 10 mass% (more preferably 0.001 to 5 mass%, still more preferably 0.01 to 4 mass%) based on the total mass of the film thickening solution. ), a method for producing a thick-film resist pattern. The method for producing a thick-film resist pattern according to any one of claims 1 to 9, wherein the resist composition is a chemically amplified resist composition. 11. The method of claim 10, wherein the resist composition further comprises a photoacid generator. A thickening solution comprising a polymer (A) and a solvent (B), which is applied prior to development of the resist layer to thicken the resist layer. The film-thickening solution of claim 12 , wherein the film-thickening solution is not a film-thickening solution applied between resist patterns. As a method of manufacturing a processed substrate,
Forming a thick-film resist pattern according to any one of claims 1 to 11; and
(4) a processing step of using the thick-film resist pattern as a mask. A method for manufacturing a device comprising the method according to claim 14,
Preferably, further comprising the step of forming a wiring on the processing substrate, or
Preferably, the method of manufacturing a device, wherein the device is a semiconductor device.