JP2019121638A - Method for removing organic underlayer film and acidic cleaning solution - Google Patents

Abstract

To provide a method of removing an organic underlayer film which can satisfactorily remove an organic underlayer film such as a mask material and an antireflective film formed on a substrate while suppressing damage to a metal film used for forming an insulating film or a wiring, and an acidic cleaning solution that can be preferably used in the method.SOLUTION: When removing an organic underlayer film on a substrate, by bringing the organic underlayer film into contact with an acidic cleaning solution, an acidic cleaning solution containing an optionally halogenated alkyl sulfonic acid is used as the acidic cleaning solution. Content of the optionally halogenated alkyl sulfonic acid in the acidic cleaning solution is preferably 40% by mass or more.SELECTED DRAWING: None

Description

  The present invention relates to a method of removing an organic lower layer film formed on a substrate, and an acidic cleaning solution suitably used in the method.

In the process of manufacturing a semiconductor substrate, a film to be etched such as an interlayer insulating film or a metal film formed on a substrate such as a semiconductor wafer is etched using an organic cured film or the like such as a carbon hard mask as a mask material. Thus, the step of forming a predetermined pattern is performed.
Moreover, when processing by a photolithographic method using a photoresist composition, in order to suppress the standing wave by reflection from the substrate at the time of exposure, an antireflective film is formed under the resist film There are many.
Such a mask material and an antireflective film are called a lower layer film.

  For example, the mask material remaining on the substrate after etching needs to be removed from the substrate. As a method of such removal, for example, there is known a method of removing a mask material made of amorphous carbon by a wet method using a mixed solution (SPM) of sulfuric acid and hydrogen peroxide solution (Patent Document 1). reference.).

JP 2017-117938

  However, when the mask material is removed using a mixed solution (SPM) of sulfuric acid and hydrogen peroxide solution, the cured organic film can be removed well while the high dielectric constant material (High (High) is provided on the substrate. There is a problem that damage to the -k material), the metal film used for forming the insulating film or the wiring tends to occur.

  The present invention has been made in view of the above problems, and an organic lower layer film such as a mask material or an antireflective film formed on a substrate while suppressing damage to a metal film used for forming an insulating film or wiring. It is an object of the present invention to provide a method of removing an organic lower layer film which can satisfactorily remove the acid, and an acidic cleaning solution which can be preferably used in the method.

  By removing the organic lower layer film on the substrate, the present inventors bring the organic lower layer film into contact with the acidic cleaning solution, and use the acidic cleaning solution containing the alkylsulfonic acid which may be halogenated as the acidic cleaning solution. It has been found that the above problems can be solved, and the present invention has been completed. More specifically, the present invention provides the following.

A first aspect of the present invention is a method for removing the organic lower film from the substrate by bringing the organic lower film on the substrate into contact with an acidic cleaning solution,
The acidic cleaning solution contains an alkylsulfonic acid,
At least a part of hydrogen atoms in the alkyl group possessed by the alkylsulfonic acid may be substituted by a halogen atom.

A second aspect of the present invention is an acidic cleaning solution used in the method according to the first aspect to remove the organic underlayer film from the substrate,
The acidic cleaning solution contains an alkylsulfonic acid,
At least a part of hydrogen atoms in the alkyl group of the alkylsulfonic acid may be substituted by a halogen atom, which is an acidic cleaning solution.

  According to the present invention, it is possible to satisfactorily remove an organic lower layer film such as a mask material or an antireflective film formed on a substrate while suppressing damage to a metal film used for forming an insulating film or wiring. It is possible to provide a method of removing the lower layer film and an acidic cleaning solution which can be preferably used in the method.

«Method to remove organic lower layer film»
The method of removing the organic lower layer film is a method of removing the organic lower layer film from the substrate by bringing the organic lower layer film on the substrate into contact with the acidic cleaning solution.
In the above method, an acidic cleaning solution containing an alkylsulfonic acid is used as the acidic cleaning solution. By using such an acidic cleaning solution, the organic lower layer film can be peeled well from the substrate while suppressing damage to the insulating film or the metal film used for forming the wiring.

<Board>
The type of substrate is not particularly limited. The substrate may be, for example, a substrate made of an inorganic material such as a silicon substrate, a glass substrate or a metal substrate, or may be a resin made of polyester such as PET, polycarbonate, polyimide or the like.
The substrate is typically a semiconductor substrate such as a silicon substrate.
When the substrate is a resin substrate, the organic lower layer film and the acidic cleaning solution are used so that the substrate is not in direct contact with the acidic cleaning solution by, for example, the liquid deposition method, from the viewpoint of suppressing the damage to the substrate. It is preferable to make contact with

In addition to the organic lower layer film, various other layers may be formed on the substrate.
As other layers, an insulating layer, a conductive layer (wiring material) made of a conductive material such as metal or metal oxide such as ITO, a semiconductor layer, an antireflective layer, etc. may be mentioned.
As a metal film used for insulating film or wiring formation, for example, aluminum (Al); aluminum-silicon (Al-Si), aluminum-copper (Al-Cu), aluminum-silicon-copper (Al-Si-Cu) Aluminum alloys (Al alloys); titanium (Ti); titanium alloys (Ti alloys) such as titanium nitride (TiN) and titanium tungsten (TiW); tantalum (Ta), tantalum nitride (TaN), tungsten (W), etc. Tungsten nitride (WN), copper (Cu), cobalt (Co) or the like is used.
Examples of the insulating layer include an SiO ₂ film, aluminum oxide, a low dielectric constant film (Low-k film), a high dielectric constant film (High-k film), and the like.
For example, as the Low-k film, a SiOC film, a SiCOH film, or the like, which is a film having a relative dielectric constant lower than that of silicon dioxide, may be mentioned. Examples of the High-k film include films made of a material such as hafnium oxide.

  An organic lower layer film and, if necessary, other layers are laminated on the above-described substrate so as to have a desired layer configuration.

<Organic lower layer film>
The organic lower layer film may be an organic lower layer film used in various lamination processing processes such as a manufacturing process of a semiconductor element. Examples of the organic lower layer film include an organic lower layer film used as a mask material, an antireflective film, and the like.
Curing is a concept including not only so-called chemical curing reaction such as curing reaction of epoxy resin but also physical curing of film such as film tightness by baking film containing resin. is there.

  The organic lower layer film preferably contains a resin having an ether bond and / or an ester bond from the viewpoint of easy removal by an acidic washing solution described later.

Examples of the organic lower layer film include a layer made of a thermosetting cross-linked polymer and a photoresist film (in particular, an ion-implanted photoresist film used as a mask material for an ion implantation process). And a lower layer film such as an antireflective film or a carbon hard mask film (organic hard mask film).
When forming a pattern by etching the layer to be etched on the substrate by fine processing using a lithography process, a patterned layer made of a material whose etching selectivity is significantly different from that of the layer to be etched is formed and used as a mask The etching of the layer to be etched is performed.
A layer used as a mask, which has a large difference in etching selectivity from the layer to be etched, is called a hard mask.

  Commercially available anti-reflection film materials include “SWK-EX1D55”, “SWK-EX3”, “SWK-EX4”, “SWK-T5D60”, “SWK-T7”, etc. by Tokyo Ohka Kogyo Co., Ltd., Brewer science Materials sold under the trade names of DUV-42, DUV-44, ARC-28, ARC-29, etc. manufactured by Shin-Etsu Co., Ltd., AR-3 manufactured by Shipley, AR The material etc. marketed by brand names, such as "-19", etc. are mentioned.

Hereinafter, specific examples of the organic lower layer film will be described with reference to some patent documents. The organic lower layer film is not limited to the specific example of the organic lower layer film described below.
In the following description, the general formula described in each patent document is cited as it is. Therefore, the same abbreviation may be included in a plurality of different general formulas for the abbreviations of substituents and the like.
Thus, when the same abbreviation is included in a plurality of different general formulas, the definition of each abbreviation follows the definition for each general formula.

  As an organic lower layer film used as an antireflective film, for example, an organic lower layer film (coated lower layer film) formed using a composition as described in Japanese Patent No. 4895049 is known. .

  Specifically, an organic lower layer film (coating type lower layer film) formed using the composition described in Japanese Patent No. 4895049 is a compound represented by the following formula (1) or the following formula (2). Including.

（式中、Ａは芳香族基を有する有機基を示し、Ｒ_１はヒドロキシ基、アルキル基、アルコキシ基、ハロゲン基、チオール基、アミノ基、又はアミド基を示し、ｍ１はナフタレン環に置換したＡの数であり１以上６以下の整数を示し、ｍ２はナフタレン環に置換したＲ１の数であり０以上５以下の整数であり、ｍ１＋ｍ２の和は１以上６以下の整数であり６以外の場合の残部は水素原子を示す。ｎは２以上７０００以下の繰り返し単位を示す。）

(Wherein, A represents an organic group having an aromatic group, R ₁ represents a hydroxy group, an alkyl group, an alkoxy group, a halogen group, a thiol group, an amino group, or an amide group, and m1 represents a naphthalene ring) It is the number of A and shows an integer of 1 or more and 6 or less, m 2 is the number of R 1 substituted on the naphthalene ring and is an integer of 0 or more and 5 or less. The sum of m 1 + m 2 is an integer of 1 or more and 6 or less The remainder of the cases indicate a hydrogen atom, and n indicates a repeating unit of 2 or more and 7,000 or less.)

（式中、Ａ、Ｒ_１、ｍ１、ｍ２、及びｎは式（１）における意味と同じであり、Ａｒ１は置換又は未置換の芳香族基である。）

(Wherein, A, R ₁ , m 1, m 2 and n have the same meanings as in formula (1), and Ar 1 is a substituted or unsubstituted aromatic group)

（式中、Ｘは単結合、メチレン基、炭素原子数２以上１０以下のアルキレン基、炭素原子数２以上１０以下のエーテル結合を有する２価の炭化水素基、又はカルボニル基を示し、Ｚは−Ｏ−、−ＯＣ（＝Ｏ）−で示される連結基を示し、Ａｒ_２は未置換又はカルボン酸、カルボン酸エステル基、ヒドロキシ基、アルキル基、アルコキシ基、スルホン酸基、若しくはハロゲンで置換された芳香族環を示し、そしてＲ_１、ｍ１、ｍ２、及びｎは式（１）における意味と同じである。） As a compound represented by Formula (1), the compound represented by following formula (3) is preferable.

(Wherein X represents a single bond, a methylene group, an alkylene group having 2 to 10 carbon atoms, a divalent hydrocarbon group having an ether bond having 2 to 10 carbon atoms, or a carbonyl group, and Z represents -O- or -OC (= O)-represents a linking group, and Ar ₂ is unsubstituted or substituted with a carboxylic acid, a carboxylic acid ester group, a hydroxy group, an alkyl group, an alkoxy group, a sulfonic acid group, or a halogen And R ₁ , m 1, m 2 and n are as defined in formula (1).

（式中、Ｘ及びＺは、式（３）における意味と同一であり、Ａｒ_１は式（２）における意味と同一であり、Ａｒ_２は式（３）における意味と同一であり、そして、Ｒ_１、ｍ１、ｍ２、及びｎは式（１）における意味と同じである。） As a compound represented by Formula (2), the compound represented by following formula (4) is preferable.

(Wherein, X and Z are the same as the meaning in Formula (3), Ar ₁ is the same as the meaning in Formula (2), Ar ₂ is the same as the meaning in Formula (3), and R ₁ , m 1, m 2 and n are as defined in the formula (1).)

  Examples of the material of the carbon hard mask film include amorphous carbon and various resin materials. As the resin material, a resin containing an aromatic group such as novolak resin or polyhydroxystyrene resin is preferably used.

  Further, as a carbon hard mask film made of a resin containing an aromatic group, for example, a hard mask film formed using a composition as described in Japanese Patent No. 4433933 is also known.

  Specifically, the composition described in Japanese Patent No. 4433933 includes a copolymer having a repeating unit represented by the following formula (1) and a repeating unit represented by the following formula (2): It is a radiation sensitive composition containing a radiation type acid generator and a solvent.

（式（１）において、Ｒ^１は水素原子又は１価の有機基（ただし、エポキシ基を有するものを除く。）を示し、各Ｒ^２は相互に独立に水素原子又は１価の有機基（ただし、エポキシ基を有するものを除く。）を示し、Ｒ^３はエポキシ基を有する１価の有機基を示す。）

(In formula (1), R ¹ represents a hydrogen atom or a monovalent organic group (excluding those having an epoxy group), and each R ² independently represents a hydrogen atom or a monovalent organic group ( With the exception of those having an epoxy group), and R ³ represents a monovalent organic group having an epoxy group)

（式（２）において、各Ｒ^４は相互に独立に水素原子又は１価の有機基（ただし、エポキシ基を有するものを除く。）を示す。）

(In formula (2), each R ⁴ independently represents a hydrogen atom or a monovalent organic group (excluding those having an epoxy group).)

The hard mask film formed using such a radiation sensitive composition has an aromatic group derived from the repeating unit represented by the formula (2) and an ester bond derived from the repeating unit represented by the formula (1) Including.
In addition, when the epoxy groups represented by R ³ contained in the repeating unit represented by the formula (1) react with each other, an ether bond may be generated.
Thus, the hard mask film may include a polymer having an ester bond or an ether bond.

Furthermore, the hard mask film may contain fluorine, chlorine and sulfur elements.
For example, a fluorine-containing functional group may be introduced into the material of the hard mask film for various purposes, or a dry etching using a fluorine-containing gas is performed on a laminate provided with the hard mask film. The material of the hard mask film may be fluorinated.

As other materials for the carbon hard mask film, for example, Japanese Patent No. 5440755, Japanese Patent No. 5229044, Japanese Patent No. 5920588, International Publication WO 2014/014034, Japanese Patent No. 4639919, and International Publication WO 2012/161126. And materials listed in the
The materials described in each patent document will be described below, but the numbers of the general formulas and the abbreviations indicating substituents and the like may be duplicated because they are described using the numbers described in each patent document.

と、下記式（２）で表される構造単位と、下記式（３）で表される構造単位：

（上記式中、Ｒ_３、Ｒ_４、Ｒ_５、Ｒ_１０、Ｒ_１１及びＲ_１２は、それぞれ、水素原子、ハロゲン原子又は炭素原子数１ないし３のアルキル基を表し、
Ｒ_６、Ｒ_７及びＲ_８は、それぞれ、水素原子又は炭素原子数１ないし１０の鎖状又は環状のアルキル基を表し、
Ｒ_９は炭素原子数１ないし１０の鎖状又は環状のアルキル基又は炭素原子数６ないし２０の芳香族基を表し、また、
Ｒ_７とＲ_８は互いに結合して環を形成していてもよく、
Ｍ及びＱはそれぞれ直接結合又は連結基を表し、
ｎは０又は１の整数を表す。）
を含むポリマーであって、当該ポリマーを構成する全ての単位構造の総数を１．０とした場合、式（１−１）、式（１−２）、式（１−３）又は式（１−４）で表される単位構造の数（ａ）の割合、式（２）で表される単位構造の数（ｂ）の割合及び式（３）で表される単位構造の数（ｃ）の割合が、０．５≦ａ≦０．８、０．１≦ｂ≦０．２、０．１≦ｃ≦０．３となるポリマーが開示されている。 Japanese Patent No. 5440755 has a unit structure represented by the following formula (1-1), (1-2), (1-3) or (1-4):

And a structural unit represented by the following formula (2), and a structural unit represented by the following formula (3):

(Wherein, R ₃ , R ₄ , R ₅ , R ₁₀ , R ₁₁ and R ₁₂ each represent a hydrogen atom, a halogen atom or an alkyl group having 1 to 3 carbon atoms,
R ₆ , R ₇ and R ₈ each independently represent a hydrogen atom or a linear or cyclic alkyl group having 1 to 10 carbon atoms,
R ₉ represents a linear or cyclic alkyl group having 1 to 10 carbon atoms or an aromatic group having 6 to 20 carbon atoms, and
R ₇ and R ₈ may be bonded to each other to form a ring,
M and Q each represent a direct bond or a linking group,
n represents an integer of 0 or 1. )
And the total number of unit structures constituting the polymer is 1.0, the polymer represented by formula (1-1), formula (1-2), formula (1-3) or formula (1) -4) The ratio of the number (a) of unit structures, the ratio of the number (b) of unit structures represented by the equation (2), and the number of unit structures represented by the equation (3) (c) Polymers are disclosed in which the ratio of is 0.5 ≦ a ≦ 0.8, 0.1 ≦ b ≦ 0.2, 0.1 ≦ c ≦ 0.3.

A polymer obtainable as a carbon hard mask described in Japanese Patent No. 5440755 has an ester bond derived from a unit represented by the formula (2). Moreover, since the unit represented by Formula (3) has an epoxy group (oxiranyl group) or oxetanyl group, the polymer contained in a carbon hard mask may have an ether bond by reaction of these groups.
Furthermore, the aromatic ring in the structural unit represented by Formula (1-1)-(1-4) may be fluorinated by the dry etching etc. which use fluorine-containing gas.

（式（１）中、複数のＲは、それぞれ独立に、水素原子、アダマンチル基、又はグリシジルエーテル基を示す。ただし、複数のＲのうち、１つ又は２つがアダマンチル基であるとともに、１つ又は２つがグリシジルエーテル基である。ｎは０以上３以下の整数を示す。）
で表される化合物と、
（Ｃ）有機溶媒と、を含有する組成物を用いて形成されるポリマーをカーボンハードマスクとして使用し得ることが記載されている。
特許第５２２９０４４号公報には、（Ａ）芳香族環を有する重合体として、ノボラック樹脂を好適に使用できることも記載されている。 Japanese Patent No. 5229 044
(A) a polymer having an aromatic ring,
(B) the following formula (1):

(In formula (1), a plurality of R's each independently represent a hydrogen atom, an adamantyl group, or a glycidyl ether group, provided that one or two of a plurality of R's are an adamantyl group, and Or two are glycidyl ether groups, n represents an integer of 0 or more and 3 or less)
And a compound represented by
It is described that a polymer formed using a composition containing (C) an organic solvent can be used as a carbon hard mask.
Japanese Patent No. 5229044 also describes that a novolak resin can be suitably used as the polymer (A) having an aromatic ring.

The polymer to be used as the carbon hard mask described in Japanese Patent No. 5229044 is, for example, a phenolic hydroxyl group and a surface represented by the formula (1) when the polymer having an aromatic ring (A) is a novolac resin. The compound has an ether bond formed by reaction with a glycidyl group.
Furthermore, the aromatic ring derived from the polymer having (A) an aromatic ring or the compound represented by the formula (1) may be fluorinated by dry etching or the like using a fluorine-containing gas.

Japanese Patent No. 5920588 discloses the following formula (2):
_{- (- O-Ar 2 -O} -Ar 3 -T-Ar 4 -) - ··· (2)
(However, in the formula (2), Ar ₂ , Ar ₃ and Ar ₄ each represent an organic group containing an arylene group having 6 to 50 carbon atoms, and T represents a carbonyl group.)
Structural unit represented by or the following formula (1)
— (— O—Ar ₁ —) — (1)
(In formula (1), Ar ₁ represents an organic group containing an arylene group or heterocyclic group having 6 to 50 carbon atoms)
A polymer is described which comprises a combination of a structural unit represented by and a structural unit represented by the above formula (2).

The polymers obtainable as carbon hard masks described in patent 5229 044 are aromatic polyethers which necessarily have ether linkages.
Furthermore, the aromatic ring contained in the polymer described in Japanese Patent No. 5229044 may be fluorinated by dry etching or the like using a fluorine-containing gas.

International Publication WO 2014/014034 includes a resin containing an aromatic ring, and a compound represented by the following formula (i):
Ar- (X-Q) _n (i)
(In the formula (i),
X is a carbonyl group or a sulfonyl group.
Q is a monovalent heteroaromatic group or -OR ¹ . R1 is a monovalent organic group having 1 to 30 carbon atoms.
Ar is an aromatic hydrocarbon group or a heteroaromatic group.
n is an integer of 1 or more and 8 or less. When n is 2 or more, a plurality of X and Q may be the same or different. )
The polymer formed using the composition containing the crosslinking agent which has a partial structure represented by these is described.

International Publication WO 2014/014034 describes novolak resins and polyarylene resins such as polyarylene ethers as specific examples of resins containing an aromatic ring, and compounds of the following structure are disclosed as specific examples of crosslinking agents. ing. The polymer formed by crosslinking the novolac resin with a crosslinking agent having the following structure contains an ester bond. A polymer formed by crosslinking the polyarylene ether with a crosslinking agent having the following structure contains an ether bond and an ester bond. In addition, when a crosslinking agent containing 1,1,1,3,3,3-hexafluoropropan-2-yl group is used, the polymer to be produced may contain a fluorine atom.
Furthermore, the aromatic ring contained in the polymer described in International Publication WO 2014/014034 may be fluorinated by dry etching or the like using a fluorine-containing gas.

（式（４）〜（６）において、Ｒはメチル基を示し；ｎは０又は１の整数を示す。）
で表される構造単位を有する重合体を含む組成物を用いて形成される膜のハードマスク膜としての使用が記載されている（段落［００３５］〜［００３７］を参照。）。 Japanese Patent No. 4639919 discloses the following formulas (4) to (6):

(In the formulas (4) to (6), R represents a methyl group; n represents an integer of 0 or 1)
The use as a hard mask film | membrane of the film | membrane formed using the composition containing the polymer which has a structural unit represented by these is described (refer to stage [0035]-[0037]).

In addition, it is described in Japanese Patent No. 4639919 that the composition may contain various resins such as polyethers, polyamides, polyesters and polyimides in addition to the above-mentioned polymers. (See paragraphs [0063]-[0065]). That is, the hard mask film formed using the composition described in Japanese Patent No. 4639919 is not limited to the amide bond and the ester bond derived from the structural units represented by the formulas (4) to (6). , An ether bond, an amide bond, an ester bond, and an imide bond derived from a binder resin.
Furthermore, the aromatic ring contained in the hard mask film formed using the composition described in Japanese Patent No. 4639919 may be fluorinated by dry etching or the like using a fluorine-containing gas.

（式（１）中、Ｒ^１は水素原子又はメチル基を表し、Ｒ^２は炭素原子数１以上３以下のアルキレン基又は置換基を有してもよいフェニレン基を表し、Ｒ^３はヒドロキシ基又はカルボキシ基を表す。
式（２）中、Ｒ^４は水素原子又はメチル基を表し、Ｙは−Ｃ（＝Ｏ）−ＮＨ−基又は−Ｃ（＝Ｏ）−Ｏ−基で表される連結基を表し、Ｘはラクトン環を含む基、アダマンタン環を含む基又は置換されていてもよいベンゼン環基、置換されていてもよいナフタレン環基、若しくは置換されていてもよいアントラセン環基を表し、前記Ｙで表される連結基の炭素原子は前記ポリマーの主鎖と結合する。）
を含むポリマー（Ａ）と、ブロックイソシアネート基、メチロール基又は炭素原子数１以上５以下のアルコキシメチル基を少なくとも２つ有する架橋性化合物（Ｂ）と、溶剤（Ｃ）とを含む組成物を用いて形成されるカーボンハードマスク膜が記載されている。 A polymer obtainable as a carbon hard mask described in International Publication WO 2012/161126 includes a structural unit represented by the following formula (1) and a structural unit represented by the following formula (2):

(In formula (1), R ¹ represents a hydrogen atom or a methyl group, R ² represents an alkylene group having 1 to 3 carbon atoms, or a phenylene group which may have a substituent, and R ³ represents a hydroxy group Or a carboxy group.
In formula (2), R ⁴ represents a hydrogen atom or a methyl group, Y represents a linking group represented by —C (= O) —NH— group or —C (= O) —O— group, X Represents a group containing a lactone ring, a group containing an adamantane ring, a benzene ring group which may be substituted, a naphthalene ring group which may be substituted, or an anthracene ring group which may be substituted. The carbon atom of the linking group is attached to the main chain of the polymer. )
Using a composition containing a polymer (A) containing at least two, a blocked isocyanate group, a methylol group or a crosslinkable compound (B) having at least two alkoxymethyl groups having 1 to 5 carbon atoms, and a solvent (C) Carbon hard mask films are described.

  The polymer contained in the hard mask film formed using the composition described in International Publication WO 2012/161126 is a structural unit represented by Formula (1) or a structural unit represented by Formula (2) It has an amide bond derived or an ester bond derived from the structural unit represented by the formula (2).

As also described in some of the above-mentioned patent documents, a film formed using a composition containing a polymer of a desired structure and a crosslinking agent is preferably used as a carbon hard mask film.
As a general crosslinking agent mix | blended with the composition for carbon hard mask film formation, the melamine type crosslinking agent described in the patent 5920588, a substituted urea type crosslinking agent, or these oligomers, polymers, etc. are mentioned. Be
Crosslinkers having at least two crosslinkable substituents are preferred, for example methoxymethylated glycoluril, butoxymethylated glycoluril, methoxymethylated melamine, butoxymethylated melamine, methoxymethylated benzogguanamine, butoxymethylated benzogguanamine, methoxy Compounds such as methylated urea, butoxymethylated urea, methoxymethylated thiourea, or methoxymethylated thiourea, or a highly heat-resistant crosslinker described in paragraph [0035] of patent 5867732, in the molecule Compounds containing a bridge forming substituent having an aromatic ring (for example, a benzene ring, a naphthalene ring) can be particularly preferably used as the crosslinking agent.

Examples of such a compound include a compound having a partial structure represented by the following formula (4), and a polymer or an oligomer having a repeating unit represented by the following formula (5).

In formula (4), R ₁₀ and R ₁₁ each represent a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 20 carbon atoms, and n10 represents an integer of 1 to 4 , N11 represents an integer of 1 or more and (5-n10) or less, and (n10 + n11) represents an integer of 2 or more and 5 or less.
In formula (5), R ₁₂ represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, R ₁₃ represents an alkyl group having 1 to 10 carbon atoms, and n 12 represents an integer of 1 to 4 N13 represents 0 or more (4-n12), and (n12 + n13) represents an integer of 1 or more and 4 or less.
The oligomers and polymers can be used in the range of 2 to 100 or 2 to 50 in number of repeating unit structures.

  The organic underlayer film is favorably removed by bringing the organic underlayer film such as the antireflective film, the carbon hard mask film, the photoresist film and the like from the materials described above into contact with the acidic cleaning solution described later.

<Acid wash solution>
As the acidic washing solution, an acidic washing solution containing an alkylsulfonic acid is used. At least a part of hydrogen atoms in the alkyl group possessed by the alkylsulfonic acid may be substituted by a halogen atom. Hereinafter, in the specification of the present application, "alkylsulfonic acid" means an alkylsulfonic acid which may be substituted by a halogen atom.

  The halogen atom is not particularly limited, and examples thereof include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom, a fluorine atom and a chlorine atom are preferable, and a fluorine atom is more preferable.

The alkyl group possessed by the alkylsulfonic acid may be a linear alkyl group or a branched alkyl group. The number of carbon atoms of the alkylsulfonic acid is not particularly limited. The number of carbon atoms of the alkylsulfonic acid is preferably 1 or more and 10 or less, more preferably 1 or more and 6 or less, and particularly preferably 1 or more and 4 or less, because the organic lower layer film can be easily removed.
Preferred specific examples of the alkylsulfonic acid include methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid, butanesulfonic acid, trifluoromethanesulfonic acid, pentafluoroethanesulfonic acid, heptafluoropropanesulfonic acid, and nonafluorobutanesulfonic acid. Can be mentioned.
It is more preferable that the acidic cleaning solution contains methanesulfonic acid and / or trifluoromethanesulfonic acid because it is easy to remove the organic lower layer film particularly well.

  The content of the alkylsulfonic acid in the acidic cleaning solution is not particularly limited as long as the organic lower layer film can be removed well. Typically, the content of the alkylsulfonic acid in the acidic cleaning solution is preferably 40% by mass or more, more preferably 50% by mass or more, still more preferably 80% by mass or more, still more preferably 90% by mass or more, 95 Mass% or more is especially preferable, and 100 mass% is the most preferable.

The acidic washing solution may contain an aliphatic carboxylic acid together with the alkylsulfonic acid. Aliphatic carboxylic acids are generally cheaper compared to alkyl sulfonic acids. When the alkyl sulfonic acid and the aliphatic carboxylic acid are used in combination, the content of the alkyl sulfo acid in the acidic cleaning solution is at least slightly, and the organic lower layer film can be easily removed easily using the acidic cleaning solution.
Examples of aliphatic carboxylic acids that can be used in combination with alkylsulfonic acids include formic acid, acetic acid, propionic acid, butyric acid, and lactic acid.

As content of the aliphatic carboxylic acid in an acidic washing | cleaning liquid, it is 1 mass% or more, for example, may be 5 mass% or more, 10 mass% or more, or 20 mass% or more.
The upper limit of the content of aliphatic carboxylic acid in the acidic cleaning solution is not particularly limited as long as the organic lower layer film can be removed well. The upper limit of the content of the aliphatic carboxylic acid in the acidic cleaning solution is, for example, 50% by mass or less and may be 20% by mass or less.
80 mass% or more is preferable, 90 mass% or more is more preferable, 95 mass% or more is still more preferable, 100 mass% is most preferable, as for the total of the alkyl sulfonic acid and aliphatic carboxylic acid in an acidic washing | cleaning liquid.

The acidic cleaning solution preferably contains substantially no film-forming polymer in that the organic lower layer film can be easily removed. The film-forming polymer is a polymer capable of forming a film so that the acidic cleaning solution does not easily flow when the acidic cleaning solution is deposited on the substrate provided with the organic lower layer film.
In addition, when the acidic cleaning solution does not contain a film-forming polymer, the acid cleaning solution has a low viscosity, so that the contact between the organic lower layer film to be peeled and the acid can be improved.

  The acidic cleaning solution may contain other components other than the above components as long as it does not inhibit the removal of the organic lower layer film or damage the metal film used for forming the insulating film or the wiring. . As other components, an anticorrosive agent, surfactant, etc. are mentioned.

The organic lower film on the substrate is removed by bringing the acidic cleaning solution described above into contact with the organic lower film on the substrate.
There is no particular limitation on the method of contacting the acidic cleaning solution with the organic lower layer film. Preferred methods include the following methods 1) to 4). Among the following methods, the immersion method 1) is preferable from the viewpoint of easy operation and easy contact of the acidic cleaning solution with the whole organic lower layer film.
1) Method of immersing a substrate provided with an organic lower layer film in an acidic cleaning solution 2) Method of depositing an acidic cleaning solution on an organic lower layer film 3) Method of spraying an acidic cleaning solution on an organic lower layer film 4) Organic lower layer Method of flowing acidic cleaning solution on the surface of membrane

The temperature of the acidic cleaning solution to be in contact with the organic lower layer film is not particularly limited as long as the organic lower layer film can be favorably removed while suppressing damage to the insulating film or the metal film used for forming the wiring.
Typically, the temperature of the acidic cleaning solution is preferably 50 ° C. or more and 170 ° C. or less, more preferably 55 ° C. or more and 150 ° C. or less, and particularly preferably 60 ° C. or more and 120 ° C. or less.
By bringing an acidic cleaning solution having a temperature within such a range into contact with the organic lower layer film, removal of the organic lower layer film can be carried out easily and satisfactorily while suppressing damage to the insulating film or the metal film used for forming the wiring. Can.

  The time for which the organic lower layer film and the acidic cleaning solution are in contact with each other is not particularly limited as long as the organic lower layer film can be removed well. Although depending on the temperature of the acidic cleaning solution, typically, the contact time is preferably 10 seconds or more and 1 hour or less, more preferably 30 seconds or more and 30 minutes or less, and particularly preferably 1 minute or more and 10 minutes or less.

After contacting the organic lower layer film with the acidic cleaning solution for a desired time, the substrate is washed with water or an organic solvent, if necessary. By drying the washed substrate, a substrate from which the organic lower layer film has been removed can be obtained.
The substrate from which the organic lower layer film thus obtained is removed may be used as it is as a product or may be subjected to post-processing depending on the use of the substrate.

  Hereinafter, the present invention will be described in more detail by way of examples. The present invention is not limited to these examples.

[Examples 1 to 8, Comparative Examples 1 to 6]
The acid components of the types listed in Table 1 and, if necessary, the types of organic solvents listed in Table 1 or acetic acid are mixed so as to give the concentrations listed in Table 1; The acid cleaning solution was adjusted.
In Comparative Examples 1 to 6, the cleaning liquid described in Table 1 was used. The cleaning solutions used in Comparative Examples 1, 2 and 4 are commercially available cleaning solutions.

The organic solvents listed in Table 1 are as follows.
S1: isopropyl alcohol S2: sulfolane

  Using the cleaning liquid of each of the examples and the comparative examples, the evaluation of the removal of the organic lower layer film and the damage of the aluminum oxide was performed according to the following method. The evaluation results are shown in Table 1.

[Organic lower layer film removal]
As a test substrate, a silicon substrate provided with a film A as an organic lower layer film and a silicon substrate provided with a film B were used. As a material of film | membrane A, resin which consists of a structural unit of the following structure was used. The film thickness of the film A is 200 nm. The film B is an antireflective film with a film thickness of 89 nm, which is formed using ARC-29 manufactured by Brewer science.

The silicon substrate provided with the organic lower layer film on the surface was immersed in the cleaning liquid of each of the examples and the comparative examples under the conditions of Table 1. After immersion, the substrate was washed with pure water and dried by nitrogen blow.
The surface of the substrate after drying was observed by a scanning electron microscope (SEM) to evaluate removability.
Regarding the removal of the organic lower layer film, the case where it could be completely removed by immersion for 3 minutes was judged as A, and the case where most of it could be removed by immersion for 3 minutes was judged as B, The case where it could not be removed almost by immersion for 3 minutes was judged as C.

[Damage of aluminum oxide]
As a test substrate, a silicon substrate provided with an aluminum oxide film having a thickness of 200 nm on its surface was used.
The silicon substrate having an aluminum oxide film on the surface was immersed in the cleaning liquid of each of the examples and the comparative examples under the conditions of Table 1. After immersion, the substrate was washed with pure water and dried by nitrogen blow.
The surface of the substrate after drying was observed with a scanning electron microscope (SEM) to evaluate the presence or absence of damage to the aluminum oxide film.
Regarding damage to the aluminum oxide film, a case where no decrease in film thickness was observed after 3 minutes immersion was judged as ○, and a case where no decrease in film thickness was observed after 3 minutes immersion was judged as x.

  According to Table 1, when removing an organic lower layer film such as a mask material or an antireflective film formed on a substrate, an organic lower layer is obtained using an acidic cleaning solution containing an alkylsulfonic acid which may be halogenated. It can be seen that good removal of the organic lower layer film and suppression of damage to the aluminum oxide film were both achieved in Examples 1 to 8 in which the film was removed.

Claims (8)

A method of removing the organic underlayer film from the substrate by bringing the organic underlayer film on the substrate into contact with an acidic cleaning solution,
The acidic cleaning solution contains an alkylsulfonic acid,
At least a part of hydrogen atoms in the alkyl group possessed by the alkyl sulfonic acid may be substituted by a halogen atom.   The method according to claim 1, wherein the content of the alkyl sulfonic acid in the acidic cleaning solution is 40% by mass or more.   The method according to claim 1, wherein the organic underlayer film is a carbon hard mask.   The method according to any one of claims 1 to 3, wherein the organic lower layer film comprises a resin having an ether bond and / or an ester bond.   The method according to any one of claims 1 to 4, wherein the acidic cleaning solution comprises methanesulfonic acid and / or trifluoromethanesulfonic acid.   The method according to any one of claims 1 to 5, wherein the substrate is immersed in the acidic cleaning solution.   The method according to any one of claims 1 to 6, wherein the acidic cleaning solution at 50 ° C to 170 ° C is brought into contact with the organic lower layer film. The method according to any one of claims 1 to 7, wherein the cleaning solution is an acidic cleaning solution used to remove the organic lower layer film from the substrate,
The acidic cleaning solution contains an alkylsulfonic acid,
The acidic washing | cleaning liquid in which at least one part of the hydrogen atom in the alkyl group which the said alkyl sulfonic acid has may be substituted by the halogen atom.