JP2007249154A - Method for forming resist laminate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form a resist laminate having a satisfactory antireflection effect in a photolithography process using light in a vacuum ultraviolet region, and also having satisfactory development properties in a development process. <P>SOLUTION: A method for forming the photoresist laminate is provided which includes a step of forming a photoresist layer on a substrate, and a step of forming an antireflection layer by applying a coating composition comprising a fluorine-containing polymer comprising 0.1-100 mol% of a structural unit derived from a fluorine-containing monomer of formula (1). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for forming a resist laminate in which an antireflection layer is provided on a photoresist layer, and a coating composition that can be used for the formation.

In recent years, along with higher integration and higher speed of LSIs, miniaturization of design rules in lithography has been demanded. For this reason, exposure light sources used for forming resist patterns have been shortened. KrF excimer laser (248nm) was used for mass production process of 64Mbit DRAM (dynamic random access memory), but shorter wavelength ArF (193nm) excimer was used for manufacturing 256M or 1Gbit or more DRAM. A laser is used as the exposure source. In recent years, a shorter wavelength F ₂ (157 nm) laser has also been studied as a new exposure light for further miniaturization.

  The combination of monochromatic light and refractive optical system lenses is the mainstream of these lithography exposure systems, but the incident light and the reflected light from the substrate interfere during the exposure, and a standing wave is generated. Dimensional change and shape collapse have occurred. In particular, when a fine resist pattern is formed on a semiconductor substrate having a level difference, the dimensional variation and shape collapse due to this standing wave are significant (standing wave effect).

  Conventionally, as a method for suppressing the standing wave effect, a method of putting a light absorber in a resist material, a method of providing an antireflection layer on the upper surface of the resist layer (TARC method, Patent Document 1, Patent Document 2, Patent Document 3), a resist, A method of providing an antireflection layer on the lower surface (BARC method, Patent Document 4) has been proposed. Among them, the TARC method is being put into practical use from i-line, and includes a step of forming a transparent upper antireflection film on the resist upper surface and peeling after exposure. This is a method of forming a pattern with high alignment accuracy.

  The BARC method can also provide a high antireflection effect. However, when there is a step on the base, the film thickness of the antireflection film varies greatly on the step, and the reflectance varies greatly. When the thickness of the antireflection film is increased, there are disadvantages such as an increase in reflectivity. Therefore, the combined use with an upper antireflection film provided on the upper surface of the photoresist layer is desired. In addition, the upper antireflection film has not only the original antireflection function, but also a function of preventing development defects by increasing the affinity with the developer after exposure, or a function as an environmental barrier film. It will become an increasingly important material in the future.

  At first, perfluoropolyether having a low refractive index was studied as an antireflection film material used in the TARC method. However, a fluorine-containing hydrocarbon solvent must be used as a diluent or a release agent, which increases costs and forms a film. There was also a problem in the performance, and there was a demerit in practical use.

  In order to overcome this difficulty, fluorine-based antireflection film materials that can be easily peeled off with an alkaline aqueous solution used as a developing solution or pure water used as a rinsing solution have been developed (Patent Document 5, Patent Document 6, Patent Document). 7, Patent Document 8, Patent Document 9, Patent Document 10, Patent Document 11, Patent Document 12).

  These are mainly non-fluorinated binder polymers such as polyvinyl pyrrolidone and polyvinyl alcohol, low molecular weight fluorine-containing alkyl sulfonic acids, fluorine-containing alkyl carboxylic acids and their amine salts, and also main chain terminals. Is a composition comprising a high molecular weight fluorine-containing polyether which is a sulfonic acid, a carboxylic acid or an amine salt thereof.

  However, when low molecular weight fluorine-containing alkyl sulfonic acid, fluorine-containing alkyl carboxylic acid or amine salt thereof is used, the molecular weight is small, so that it diffuses into the resist layer and the pattern profile of the resist deteriorates. .

  In addition, when a high molecular weight fluorine-containing polyether whose main chain terminal is a sulfonic acid, carboxylic acid or amine salt thereof is used, water solubility decreases or becomes insoluble at a high molecular weight sufficient to prevent diffusion. There are drawbacks, and the film formability also deteriorates.

  Furthermore, in the antireflection film using polyvinylpyrrolidone developed for KrF as a binder polymer, polyvinylpyrrolidone has a high refractive index at the exposure wavelength of ArF excimer laser and low transmittance of exposure light, so that it is antireflection for ArF resist. It is unsuitable as a film material.

  On the other hand, in order to compensate for these drawbacks, a fluorinated polymer having a sulfonic acid or an amine salt thereof in the side chain of the fluorine-based polymer (Patent Document 13, Patent Document 14), a fluorinated alkylamine salt or alkanol of a carboxylic acid. An antireflective film composition using a perfluoro compound having an amine salt as a counter ion has been developed (Patent Document 15).

  Among these, fluorine-based antireflection film materials using sulfonic acid or its amine salt in the side chain (Patent Documents 13 and 14), the acidity of sulfonic acid and its amine salt is too strong, and the resist pattern after development The surface layer becomes round and causes a problem in the etching process, the surface layer of the unexposed area also undergoes a chemical amplification reaction and the film is reduced, and the element production equipment is corroded and rusted due to the acid component, resulting in product defects There are problems such as causing problems.

  On the other hand, a fluorine-based antireflection film material (Patent Document 15) using a perfluoro compound having a fluorinated alkylamine salt or alkanolamine salt of a carboxylic acid as a counter ion has a low fluorine content and is sufficiently low for practical use. A refractive index cannot be obtained. Further, since the amount of the hydrophilic group contained in the monomer is small, there is a disadvantage that the solubility (= dissolution rate) in the resist developer and the aqueous solvent is very low, and the film formability is poor. .

  In addition, compositions for antireflection films using fluorine-containing polymers having a high carboxyl group content (Patent Documents 16 and 17) have been studied, but these have a low molecular weight as carboxyl group-containing fluorine-containing polymers. The composition for anti-reflective film for resist is examined using the low molecular weight fluorine-containing polymer.

  These low molecular weight fluoropolymers are insufficiently soluble in water and require the addition of amines or surfactants, thereby reducing the refractive index of the antireflective coating or reducing the transparency. There is a problem.

  Furthermore, in order to solubilize, it becomes necessary to mix a large amount of a water-soluble organic solvent such as alcohol with water. As a result, the interface between the resist layer and the antireflection layer is intermixed when applied on the resist film. As a result, a sufficient antireflection effect cannot be obtained.

  Accordingly, the present situation is that there is a craving for an upper layer antireflection film material having practical water solubility that improves these problems, and in particular, an upper layer antireflection film material for KrF and ArF photoresists.

  As described above, the polymer used for the conventional antireflection film material has a high refractive index, and a sufficient effect in pattern formation cannot be obtained.

  On the other hand, even when the conventional material has a low refractive index, the water-soluble property or the solubility in an aqueous solvent is insufficient. Therefore, when an antireflection layer is formed on a photoresist layer, a coating containing a polymer is used. It is necessary to use an organic solvent in the composition, the photoresist layer and the antireflection layer are intermixed, the interface between them becomes unclear, and the sufficient effect due to the low refractive index cannot be exhibited in pattern formation It was. Also, the developer solubility (dissolution rate) is insufficient, and the antireflection layer cannot be removed by the conventional development process, or the antireflection layer cannot be removed smoothly even in the resist layer removal step of the exposed part in the development process. is there.

JP 60-38821 A JP-A-62-62520 JP-A-62-62521 JP 62-159143 A JP-A-5-188598 JP-A-6-41768 JP-A-6-51523 JP 7-234514 A JP-A-8-305032 JP-A-8-292562 JP-A-11-349857 JP-A-11-352697 JP 2001-194798 A JP 2001-200019 A JP 2001-133984 A Japanese Patent Laid-Open No. 11-124531 JP 2004-37887 A

  Therefore, an antireflection film for resist made of a fluorine-containing polymer having a lower refractive index and excellent developer solubility is provided on the photoresist layer, so that light in the ultraviolet region shorter than i-line (365 nm) can be obtained. Aiming at forming a resist laminate having sufficient antireflection effect in the photolithographic process to be used and sufficient development characteristics in the development process, various fluorine-containing heavy compounds having hydrophilic groups As a result of studying the coalescence, a fluoropolymer capable of achieving both low refractive index properties and solubility in water, an aqueous solvent or a developer (2.38 mass% tetramethylammonium hydroxide aqueous solution) can be found, and further, photo By providing the resist layer with an antireflective layer made of this fluoropolymer, it can be used in the photolithography exposure process. Particularly excellent antireflection effect Te be exhibited, it was also found to be able to remove easily antireflection layer in yet development process.

That is, the present invention
(I) a step of forming a photoresist layer (L1) on the substrate; and (II) an antireflection layer by applying a coating composition containing the fluoropolymer (A) on the photoresist layer (L1). A method of forming a photoresist laminate including a step of forming (L2),
The fluorine-containing polymer (A) has the formula (M):
-(M)-(N)-(M)
[Wherein, the structural unit M represents the formula (1):

(In the formula, X ¹ and X ² are the same or different, and all are H, F or CF ₃ ; Rf ¹ and Rf ² are the same or different, and both are fluorine-containing alkyl groups having 1 to 8 carbon atoms; H, an alkyl group which may contain an ether bond or a fluorine-containing alkyl group which may contain an ether bond; Y is H, F, CH ₃ or CF ₃ ; Z is CH ₂ , CHF, CF ₂ or C═ O: a structural unit derived from a fluorine-containing monomer (m) represented by n is an integer of 0 to 4; a structural unit N is a monomer copolymerizable with the fluorine-containing monomer (m) (n ) Derived structural unit], and is a fluoropolymer having a structural unit M of 0.1 to 100 mol% and a structural unit N of 0 to 99.9 mol%. Regarding the method.

  The present invention also relates to a coating composition comprising the fluoropolymer (A) and (B) an aqueous solvent or an organic solvent.

  The present invention is particularly characterized by the specific fluoropolymer (A) used for the antireflection layer (L2), and the fluoropolymer (A) is used as a main component in the antireflection layer (L2). By being present, the adverse effect on the resist pattern due to the standing wave effect generated in the case of the photoresist layer (L1) alone or the multiple reflection effect in the patterning with a step can be reduced, and the external atmosphere (acidity in the air or The change in the pattern shape due to the influence of a basic substance, moisture, and the like) can be reduced. As a result, the pattern shape and dimensional accuracy can be improved, and an extremely fine resist pattern having excellent reproducibility can be formed.

  The fluorine-containing polymer (A) used in the antireflection layer (L2) of the present invention can achieve both low refractive index and water-soluble or aqueous solvent solubility or developer solubility (dissolution rate), which has been difficult in the past. As a result, in addition to the effects in the pattern formation described above, the conventional photolithography process, in particular, the development process, in particular, has a performance that can be applied as usual.

  According to the present invention, in the step of forming a photoresist laminate for lithography, particularly in lithography using KrF (248 nm) laser or ArF (193 nm) laser as exposure light, the antireflection layer of the resist laminate is provided with a hydrophilic group. Since it is composed of a fluorine-containing polymer with a high fluorine content, the pattern dimensional accuracy decreases due to interference between the light irradiated in the photoresist layer and the reflected light from the substrate, and the dissolution rate in the development process is reduced. It is possible to prevent the deterioration and improve the fine workability.

  First, the specific fluorine-containing polymer (A) constituting the antireflection layer (L2) in the method for forming a photoresist laminate of the present invention will be described.

In the present invention, the fluoropolymer (A) used for the antireflection layer (L2) has the formula (M):
-(M)-(N)-(M)
[Wherein, the structural unit M represents the formula (1):

(In the formula, X ¹ and X ² are the same or different, and all are H, F or CF ₃ ; Rf ¹ and Rf ² are the same or different, and both are fluorine-containing alkyl groups having 1 to 8 carbon atoms; H, an alkyl group which may contain an ether bond or a fluorine-containing alkyl group which may contain an ether bond; Y is H, F, CH ₃ or CF ₃ ; Z is CH ₂ , CHF, CF ₂ or C═ O: a structural unit derived from a fluorine-containing monomer (m) represented by n is an integer of 0 to 4; a structural unit N is a monomer copolymerizable with the fluorine-containing monomer (m) (n ) Derived structural unit], and is a fluoropolymer having a structural unit M of 0.1 to 100 mol% and a structural unit N of 0 to 99.9 mol%.

  By having a specific structural unit M, it is possible to achieve both a low refractive index and water solubility or developer solubility (dissolution rate). Furthermore, when it is used as a thin antireflection coating, it provides good mechanical strength as a free-standing film. it can.

  In particular, it is preferable that the structural unit constituting the fluoropolymer (A) is substantially constituted only by the structural unit M, whereby good water solubility or aqueous solvent solubility or developer solubility (dissolution). The refractive index can be further lowered while maintaining the speed. By containing the —OH group, it is particularly excellent in transparency and has a low refractive index.

  The fluorine content of the fluoropolymer (A) used for the antireflection layer (L2) of the present invention is preferably 50% by mass or more. When the fluorine content becomes small, the refractive index measured at that wavelength becomes too high in the photolithography process using the light in the ultraviolet region of 365 nm or less at the time of exposure, the antireflection effect cannot be obtained sufficiently, and the standing wave effect or The effect of improving the adverse effect on the resist pattern due to the multiple reflection effect may be insufficient.

  The fluorine content of the fluoropolymer (A) is preferably 55% by mass or more, more preferably 57.5% by mass or more. Thereby, for example, the refractive index at 193 nm can be 1.46 or less, and can be 1.44 or less, and more preferably 1.42 or less.

  The upper limit of the fluorine content is 70% by mass, preferably 65% by mass, more preferably 62.5% by mass, and particularly 60% by mass. If the fluorine content is too high, the water repellency of the coating film to be formed becomes too high, and the developer dissolution rate may be lowered, or the reproducibility of the developer dissolution rate may be deteriorated.

  The specific fluoropolymer (A) has a structural unit M of 0.1 to 100 mol% and a structural unit N of 0 to 99.9 mol%.

  Further, in the present invention, it is preferable to use a fluorine-containing polymer having an OR group content of a specific amount or more, that is, a higher OR group content than conventional ones, in the antireflection layer (L2).

  Specifically, the number of moles of the OR group in 100 g of the fluoropolymer (A) is 0.14 or more, which makes the water solubility and developer solubility (dissolution rate) good and practical. Can be anything.

  If the number of moles of OR groups in 100 g of the fluoropolymer (A) is less than 0.14, it becomes insoluble in water or developer, or even if dissolved in the developer, the dissolution rate during the development process is increased. It is low and may be insufficient in practicality in the photolithography process.

  Preferably, the number of moles of OR groups per 100 g of the fluoropolymer (A) is 0.21 or more, more preferably 0.22 or more.

  The upper limit of the OR group content (number of moles) is 0.5, more preferably 0.45, and still more preferably 0.4 per 100 g of the fluoropolymer (A). If the OR group content is too high, the refractive index particularly in the vacuum ultraviolet region may be high.

  In the method for forming a photoresist laminate of the present invention, by using a specific fluoropolymer (A) for the antireflection layer (L2), it can be practically applied to a conventional photoresist process, and standing wave. This can improve the adverse effect on the resist pattern due to the effect and the multiple reflection effect.

In the structural unit M of the fluoropolymer (A), preferred X ¹ and X ² are the same or different, and all are H, F or CF ₃ , Rf ¹ and Rf ² are the same or different, and both are carbon A fluorine-containing alkyl group of 1 to 8; R is H, an alkyl group which may contain an ether bond or a fluorine-containing alkyl group which may contain an ether bond; Y is H, F, CH ₃ or CF ₃ ; Z is CH _2, CHF, CF ₂ or C = O; n is an integer of 0-4.

Rf ¹ and Rf ² are preferably CF ₃ , C ₂ F _5, C ₄ F _{7, and} C ₈ F ₁₇ , and can maintain the solubility of a solvent or a developer that can easily obtain the same structure in the synthesis method. From the point, they are CF ₃ and C ₂ F ₅ .

  The first preferred R is a hydrogen atom, that is, one in which OR is a hydroxyl group. By using a hydroxyl group, an excellent effect is exhibited particularly in terms of solubility in water, an aqueous solvent or a developer.

The second preferable R is an alkyl group having 1 to 8 carbon atoms and an alkyl group containing an ether bond having 2 to 8 carbon atoms. When R is an alkyl group, the effect of dissolution in a hydrocarbon solvent that does not attack the photoresist layer is exhibited. Specific examples include, for example, CH ₃ , C ₂ H ₅ , C ₃ H ₇ , CH (CH ₃ ) ₂ , C ₄ H ₉ , C (CH ₃ ) ₃ , C ₅ H ₁₁ , cyclopentyl, C ₆ H _13, Examples include cyclohexyl, C ₇ H ₁₃ , C ₈ H _{17 and the} like. When R is an alkyl group containing an ether bond, the effect of increasing the solubility in water, an aqueous solvent or a developer is exhibited. Specific examples include CH ₂ OCH ₃ , CH ₂ CH ₂ OCH ₃ , CH ₂ CH ₂ OCH ₂ CH ₃ , CH ₂ OCH ₂ OCH ₃ , polyethylene glycol group and the like.

The third preferable R is a fluorine-containing alkyl group having 1 to 8 carbon atoms and a fluorine-containing alkyl group containing an ether bond having 2 to 8 carbon atoms. When R is a fluorine-containing alkyl group, the effect of lowering the refractive index in the ultraviolet region is achieved by improving the fluorine content. Specific examples include CF ₃ , C ₂ F ₅ , C ₂ F ₄ H, C ₃ F ₇ , CF (CF ₃ ) ₂ , C ₄ F ₉ , C (CF ₃ ) ₃ , C ₅ F ₁₁ , C ₆ F _13, C ₇ F ₁₃ , C ₈ F _{17 and the} like. In the case where R is a fluorine-containing alkyl group containing an ether bond, the effect of lowering the refractive index in the ultraviolet region by improving the fluorine content and the effect of improving the transparency by using an amorphous resin are exhibited. Specific examples include CF ₂ OCF ₂ CF ₃ , CF (CF ₃ ) CF ₂ OCF (CF ₃ ) CF ₃ , CF ₂ CF ₂ CF ₂ OCF ₂ CF _{3, and the} like.

Y is H, F, CH ₃ or CF ₃ , and is preferably F or CF ₃ from the viewpoint that low refractive index can be achieved.

Z is CH ₂ , CHF, CF ₂ or C═O, and is preferably CHF or CF ₂ from the viewpoint that low refractive index can be achieved.

  n is an integer of 0 to 4, and 0 to 2, particularly 0 from the viewpoint of easy synthesis.

  Preferred as the monomer (m) that gives the structural unit M of the fluoropolymer (A) is the formula (2):

(Wherein R and n are the same as those in the above formula (1)), and in particular,

Is preferred.

  The fluorine-containing polymer (A) of the formula (M) used for the antireflection layer (L2) of the present invention may be a homopolymer of the fluorine-containing monomer (m) that gives the structural unit M of the formula (1). Further, it may be a copolymer with another monomer (n) giving the structural unit N.

  In the case of a copolymer, the structural unit (N) of the copolymer component can be appropriately selected, but is preferably selected for the purpose of setting the refractive index low within a range that maintains the developer solubility. It is selected from structural units derived from fluorine-containing ethylenic monomers.

Among these, those selected from the following structural units N1 to N8 are preferable.
(N1) A structural unit derived from a fluorine-containing ethylenic monomer having 2 or 3 carbon atoms and having at least one fluorine atom:
This structural unit N1 is preferable in that the refractive index can be effectively lowered without decreasing the developer solubility and the transparency can be improved. Moreover, it is preferable at the point which can improve the film strength of an antireflection layer.

In particular,
CF ₂ = CF ₂ , CF ₂ = CFCl, CH ₂ = CF ₂ , CFH = CH ₂ , CFH = CF ₂ , CF ₂ = CFCF ₃ , CH ₂ = CFCF ₃ , CH ₂ = CHCF _{3 and the} like. However, tetrafluoroethylene (CF ₂ ═CF ₂ ), chlorotrifluoroethylene (CF ₂ ═CFCl), vinylidene fluoride is advantageous in that it has good copolymerizability and high transparency and low refractive index. (CH ₂ = CF ₂ ) is preferred.

(N2) Formula (n2):

(In the formula, X ¹ , X ² , Y, Z and n are the same as those in the formula (1); Q is H, CH ₂ OH, COOH, CONH ₂ , CN, CH ₂ OP (P is 1 to 8 carbon atoms) A fluorine-containing alkyl group or a fluorine-containing alkyl group having an ether bond having 2 to 8 carbon atoms), a structural unit derived from a monomer represented by SO ₃ H, SO ₂ NH ₂ ):
This structural unit is preferable in that it can effectively improve the solubility of water or an aqueous solvent or developer, lower the refractive index, and improve the transparency.

  In particular,

Etc. are preferred.

(N3) Formula (n3):

(Wherein X ¹ and X ² are the same as those in formula (1); X ³ is H, F, Cl, CH ₃ or CF ₃ ; X ⁴ and X ⁵ are the same or different; H or F; a and c Are the same or different 0 or 1; Rf ³ is a structural unit derived from a monomer represented by a fluorine-containing alkyl group having 1 to 40 carbon atoms or a fluorine-containing alkyl group having an ether bond having 2 to 100 carbon atoms:
This structural unit is preferable in that it can effectively lower the refractive index and improve the transparency.

In particular,
_{CH 2 = CFCF 2 -O-Rf} 3,
CF ₂ = CF—O—Rf ³ ,
CF ₂ = CFCF ₂ —O—Rf ³ ,
CF ₂ = CF-Rf ³ ,
CH ₂ = CH-Rf ^3,
_{CH 2 = CH-O-Rf} 3
(Wherein, Rf ³ is the same as that in the above formula (n3)).
Formula (n4) containing (N4) -COOH group:

Wherein X ⁶ and X ⁷ are the same or different H or F; X ⁸ is H, F, Cl, CH ₃ or CF _{3 provided} that at least one of X ⁶ , X ⁷ and X ⁸ is A structural unit derived from a fluorine-containing monomer represented by:

  This structural unit contains a structural unit derived from fluorine-containing acrylic acid, which is a fluorine-containing monomer containing —COOH as a hydrophilic group, as a component that imparts water solubility and developer solubility. It is preferable at the point which becomes the thing excellent in liquid solubility.

  Specifically, the fluorine-containing monomer of the formula (n4) is

Among other things,

Is preferable from the viewpoint of good polymerizability.

(N5) Structural unit derived from fluorine-containing acrylate monomer:
Specifically, the formula (n5):

(Wherein X ⁹ is H, F or CH ₃ ; Rf ⁴ is a fluorine-containing alkyl group having 1 to 40 carbon atoms or a fluorine-containing alkyl group having an ether bond having 2 to 100 carbon atoms) Monomer-derived structural units are preferable, and these are preferable in that they have high copolymerizability with a fluorine-containing monomer and can impart low refractive index properties to the fluorine-containing polymer.

In the fluorine-containing acrylate of the formula (n5), the Rf ⁴ group is

(Wherein d3 is an integer of 1 to 4; e3 is an integer of 1 to 10).

(N6) Structural unit derived from fluorine-containing vinyl ether monomer:
Specifically, the formula (n6):
^{_{CH 2 = CHO-Rf 5 (}} n6)
In the formula, Rf ⁵ is preferably a structural unit derived from a fluorine-containing vinyl ether represented by a fluorine-containing alkyl group having 1 to 40 carbon atoms or a fluorine-containing alkyl group having an ether bond having 2 to 100 carbon atoms, These are preferable in that they are highly copolymerizable with the fluorine-containing monomer and can impart low refractive index properties to the fluorine-containing polymer.

  The monomer of formula (n6) is specifically

(Wherein e6 is an integer of 1 to 10).

  More specifically,

And other structural units derived from monomers.

  In addition, the following structural units (N7) and (N8) are also included.

(N7) Formula (n7):
_{CH 2 = CHCH 2 O-Rf} 6 (n7)
(Wherein Rf ⁶ is a fluorine-containing alkyl group having 1 to 40 carbon atoms or a fluorine-containing alkyl group having an ether bond having 2 to 100 carbon atoms).

(N8) Formula (n8):
^{_{CH 2 = CH-Rf 7 (}} n8)
A structural unit derived from a fluorinated vinyl monomer represented by (wherein Rf ⁷ is a fluorinated alkyl group having 1 to 40 carbon atoms or a fluorinated alkyl group having an ether bond having 2 to 100 carbon atoms).

  These are preferable in that a low refractive index property can be imparted to the fluoropolymer.

  Specifically, the monomers of the formulas (n7) and (n8) are:

And other structural units derived from monomers.

  The abundance ratio of each structural unit in the fluoropolymer of the formula (M) is appropriately selected within the range where the structural unit M is 0.1 to 100 mol% and the structural unit N is 0 to 99.9 mol%. The structural unit M is preferably 10 to 100 mol%, the structural unit N is 0 to 90 mol%, more preferably the structural unit M is 20 to 80 mol%, and the structural unit N is 20 to 80 mol%, and more preferably. The structural unit M is 30 to 70 mol%, the structural unit N is 30 to 70 mol%, particularly preferably the structural unit M is 40 to 60 mol%, and the structural unit N is 40 to 60 mol%.

  The number average molecular weight of the fluoropolymer (A) is preferably 10,000 to 750000.

  If the number average molecular weight is too low, the water-solubility is lowered, or even once water-solubilized, the stability of the aqueous solution becomes insufficient, and the fluorine-containing polymer is partially obtained by storage or addition of other additives. Precipitate, precipitate or become cloudy. A preferred lower limit is 20000, more preferably 31000.

  On the other hand, if the number average molecular weight is too high, the film formability of the antireflection coating is deteriorated, which is not preferable. A preferred upper limit is 500,000, more preferably 300,000.

  A preferred specific example of the fluoropolymer (A) used in the antireflection layer (L2) of the present invention is a single weight of the monomer (m1-1), (m1-2) and / or (m1-3). Examples thereof include copolymers or copolymers of these monomers with the above formulas (n1) to (n8), in particular, the formula (n1) (n2) or (n3).

  Among these, the following (co) polymers are preferred in that they are particularly transparent with respect to light in the ultraviolet region and the refractive index can be set low.

(P1) Homopolymer of structural unit M:
As described above, the structural unit M is represented by the formula (1):

(In the formula, X ¹ and X ² are the same or different, and all are H, F or CF ₃ ; Rf ¹ and Rf ² are the same or different, and both are fluorine-containing alkyl groups having 1 to 8 carbon atoms; H, an alkyl group which may contain an ether bond or a fluorine-containing alkyl group which may contain an ether bond; Y is H, F, CH ₃ or CF ₃ ; Z is CH ₂ , CHF, CF ₂ or C═ O; n is a structural unit derived from a fluorine-containing monomer (m) represented by 0 to 4).

  Furthermore, in terms of obtaining high solubility in the developer,

Homopolymers of monomers represented by are preferred.

(P2) Copolymer of structural unit M and structural unit N1:
The structural unit M is selected from monomers represented by the formula (1), and more preferably a structural unit that is the monomer (m1-1), (m1-2) and / or (m1-3). is there.

  The structural unit N1 is an ethylenic monomer having 2 or 3 carbon atoms as described above, and is a structural unit derived from a fluorine-containing ethylenic monomer having at least one fluorine atom.

By copolymerizing this structural unit N1, it is preferable in that the refractive index can be effectively lowered without lowering the developer solubility and the transparency can be improved. Moreover, it is preferable at the point which can improve the film strength of an antireflection layer. Among these, tetrafluoroethylene (CF ₂ ═CF ₂ ), chlorotrifluoroethylene (CF ₂ ═CFCl), fluorination is preferred because it has good copolymerizability and high effect of imparting transparency and low refractive index. Vinylidene (CH ₂ ═CF ₂ ) is preferred.

(P3) Copolymer of structural unit M and structural unit N2:
The structural unit M is selected from monomers represented by the formula (1), and more preferably a structural unit that is the monomer (m1-1), (m1-2) and / or (m1-3). is there.

  As described above, the structural unit N2 is represented by the formula (n2):

(In the formula, X ¹ , X ² , Y, Z and n are the same as those in the formula (1); Q is H, CH ₂ OH, COOH, CONH ₂ , CN, CH ₂ OP (P is 1 to 8 carbon atoms) A fluorine-containing alkyl group or a fluorine-containing alkyl group having an ether bond having 2 to 8 carbon atoms), a structural unit derived from a monomer represented by SO ₃ H, SO ₂ NH ₂ ).

  By copolymerizing this structural unit N2, it is preferable in that the solubility of water or an aqueous solvent or developer can be effectively improved, the refractive index can be lowered, and the transparency can be improved. Among them, in terms of a high effect of increasing solubility in water or aqueous solvents or solubility in developers,

Is preferred.

(P4) Copolymer of structural unit M and structural unit N3:
The structural unit M is selected from monomers represented by the formula (1), and more preferably a structural unit that is the monomer (m1-1), (m1-2) and / or (m1-3). is there.

  As described above, the structural unit N3 is represented by the formula (n3):

(Wherein X ¹ and X ² are the same as those in formula (1); X ³ is H, F, Cl, CH ₃ or CF ₃ ; X ⁴ and X ⁵ are the same or different; H or F; a and c Are the same or different 0 or 1; Rf ³ is a structural unit derived from a monomer represented by a fluorine-containing alkyl group having 1 to 40 carbon atoms or a fluorine-containing alkyl group having an ether bond having 2 to 100 carbon atoms) is there.

  The copolymerization of the structural unit N3 is preferable in that the refractive index can be effectively lowered and the transparency can be improved.

In particular,
_{CH 2 = CFCF 2 -O-Rf} 3,
CF ₂ = CF—O—Rf ³ ,
CF ₂ = CFCF ₂ —O—Rf ³ ,
CF ₂ = CF-Rf ³ ,
CH ₂ = CH-Rf ^3,
_{CH 2 = CH-O-Rf} 3
(Wherein, Rf ³ is the same as that in the above formula (n3)).

  In the method for forming a photoresist laminate of the present invention, the antireflection layer (L2) is applied on the preformed photoresist layer (L1) with a coating composition containing the aforementioned fluoropolymer (A). Formed with.

  The coating composition for forming the antireflection layer (L2) contains the fluoropolymer (A) and the solvent (B).

  The solvent (B) is preferably selected from solvents that do not re-dissolve the lower-layer photoresist film (L1) formed in advance when the coating composition is applied. From this point, the solvent (B) is water and / or alcohols. It is preferable.

  The aforementioned fluoropolymer (A) of the present invention has good solubility in these waters and alcohols.

  Of the solvent (B), water is not particularly limited as long as it is water, but water from which organic impurities and metal ions have been removed by distilled water, ion-exchanged water, filter-treated water, various adsorption treatments, and the like is preferable.

  The alcohol is selected from those which do not re-dissolve the photoresist layer (L1), and is appropriately selected according to the type of the lower photoresist layer (L1). Generally, lower alcohols are preferable, specifically methanol. , Ethanol, isopropanol, n-propanol, n-butanol, isobutanol, t-butanol and the like are preferable.

  In addition to these solvents (B), an organic solvent soluble in water may be used in combination for the purpose of improving coating properties and the like within a range where the photoresist layer (L1) is not redissolved.

  The organic solvent soluble in water is not particularly limited as long as it dissolves 1% by mass or more with respect to water. For example, ketones such as acetone and methyl ethyl ketone; acetates such as methyl acetate and ethyl acetate; polar solvents such as dimethylformamide, dimethyl sulfoxide, methyl cellosolve, cellosolve acetate, butyl cellosolve, butyl carbitol, and carbitol acetate are preferred. It is done.

  The addition amount of the water-soluble organic solvent added in addition to water or alcohols is 0.1 to 95% by mass, preferably 0.5 to 75% by mass, more preferably based on the total amount of the solvent (B). It is 1-50 mass%, Most preferably, it is 1-30 mass%.

  The coating composition forming the antireflection layer (L2) of the present invention may contain at least one selected from basic substances such as ammonia or organic amines, if necessary. In this case, the acidic OH group having a pKa of 11 or less in the coating composition may be a hydrophilic derivative site in the form of, for example, an ammonium salt or an amine salt.

The addition of a basic substance is particularly effective when the structural unit N, which is an optional component in the fluoropolymer (A), has —COOH or —SO ₃ H as a hydrophilic group, and is soluble in water and developer. Is effective in improving the reproducibility of the developer and maintaining the reproducibility of the developer dissolution rate. It is also effective for adjusting the pH of the coating composition to an optimum range.

  The organic amine is preferably a water-soluble organic amine compound, for example, primary amines such as methylamine, ethylamine, propylamine, butylamine and cyclohexylamine; secondary amines such as dimethylamine, diethylamine, dipropylamine and dibutylamine. Amines; tertiary amines such as trimethylamine, triethylamine, tripropylamine, tributylamine, pyridine, pyrrole, piperidine, oxazole, morpholine; monoethanolamine, propanolamine, diethanolamine, triethanolamine, tris (hydroxymethyl) amino Hydroxylamines such as methane; tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide Quaternary ammonium compounds such as um; primary to tertiary polyvalent amines such as ethylenediamine, diethylenediamine, tetraethylenediamine, diethylenetriamine, tetraethylenetriamine, imidazole, imidazolidine, pyrazine, and s-triazine are preferable. can give.

  Of these, hydroxylamines such as monoethanolamine, propanolamine, diethanolamine, triethanolamine, and tris (hydroxymethyl) aminomethane are preferable in terms of maintaining a low refractive index and improving the dissolution rate of the developer. Of these, monoethanolamine is particularly preferable.

  In the coating composition, the addition amount of ammonia or organic amine can be added in the range of usually 0.01 mol to 10 mol with respect to 1 mol of the hydrophilic group of the fluorine-containing polymer (A) to be used. 1 to 5 mol, more preferably 0.5 to 1 mol.

  A known surfactant may be added to the coating composition for forming the antireflection layer (L2) of the present invention, if necessary.

  The addition of the surfactant is effective for improving the wettability of the coating composition to the surface of the underlying photoresist layer (L1) and forming a uniform thin film. Furthermore, after coating, the surface tension of the resulting antireflection layer (L2) is preferably reduced, and as a result, the developer solubility is stabilized. Furthermore, it is preferable also in terms of preventing striations.

  Examples of the surfactant to be added include nonionic surfactants, anionic surfactants, and amphoteric surfactants, and anionic surfactants are preferably used.

  Nonionic surfactants include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene cetyl ether, polyoxyethylene octylphenyl ether, and polyoxyethylene nonyl. Examples thereof include phenyl ether, polyethylene glycol dilaurate, polyethylene glycol distearate, polyoxyethylene fatty acid diester, polyoxy fatty acid monoester, polyoxyethylene polyoxypropylene block polymer, acetylene glycol derivative and the like.

  Anionic surfactants include alkyl diphenyl ether disulfonic acid and its ammonium salt or organic amine salt, alkyl diphenyl ether sulfonic acid and its ammonium salt or organic amine salt, alkylbenzene sulfonic acid, and its ammonium salt or organic amine salt. Polyoxyethylene alkyl ether sulfuric acid, and ammonium salt or organic amine salt thereof, alkyl sulfuric acid, ammonium salt or organic amine salt thereof, and the like.

  Examples of amphoteric surfactants include 2-alkyl-N-carboxymethyl-N-hydroxyethyl imidazolinium betaine, lauric acid amidopropyl hydroxysulfone betaine, and the like.

  Further, a fluorine-based surfactant is also preferable in that the low refractive index property can be maintained in the antireflection layer (L2). Specifically,

Etc.

  Further, the fluorosurfactant is preferable not only from the above low molecular compound but also from the following high molecular compound in that the antireflective layer (L2) can maintain low refractive index.

  Specifically, (a) acrylic acid ester or methacrylic acid ester having a fluoroalkyl group (monomer (a)), (b) polyalkylene glycol acrylate or polyalkylene glycol methacrylate (monomer (b)), (C) contains 3-chloro-2-hydroxypropyl (meth) acrylate (monomer (c)) and (d) a structural unit derived from glycerol mono (meth) acrylate (monomer (d)) And a copolymer having a number average molecular weight of 1,000 to 500,000, and a polymer type fluorosurfactant containing the copolymer.

  The monomer giving each structural unit will be described below.

As the monomer (a), for example, the formula:
Rf ²⁰ R ¹⁰ OCOCR ¹¹ ═CH ₂
[Wherein, Rf ²⁰ is a linear or branched perfluoroalkyl group having 3 to ²⁰ carbon atoms, R ¹¹ is a hydrogen atom or a methyl group, and R ¹⁰ is a linear or branched group having 1 to ¹⁰ carbon atoms. alkylene ^{_{group, -SO 2 N (R 12)}} R 13 - group (R ¹² is an alkyl group having 1 to 10 carbon atoms, R ¹³ is a linear or branched alkylene group having 1 to 10 carbon atoms) or -CH ₂ CH (OR ¹⁴ ) CH ₂ — group (wherein R ¹⁴ is a hydrogen atom or an acyl group having 1 to 10 carbon atoms)].

Preferred examples of the monomer (a) are listed below. You may use these individually or in mixture of 2 or more types.
(A-1) CF ₃ (CF ₂ ) _n (CH ₂ ) _m OCOCR ¹¹ ═CH ₂ (wherein R ¹¹ is a hydrogen atom or a methyl group, n is an integer of 2 to 19, and m is an integer of 1 to 10) )
As a specific example,
CF ₃ (CF ₂ ) ₇ (CH ₂ ) ₁₀ OCOCH═CH ₂ ,
CF ₃ (CF ₂ ) ₇ (CH ₂ ) ₂ OCOCH═CH ₂ ,
_{CF 3 (CF 2) 6 CH} 2 OCOC (CH 3) = CH 2,
_{CF 3 (CF 2) 7 (} CH 2) 2 OCOC (CH 3) = CH 2,
_{CF 3 (CF 2) 9 (} CH 2) 2 OCOC (CH 3) = CH 2,
CF ₃ (CF ₂ ) ₁₁ (CH ₂ ) ₂ OCOC (CH ₃ ) = CH ₂
Etc.

(A-2) (CF ₃ ) ₂ CF (CF ₂ ) _n (CH ₂ ) _m OCOCR ¹¹ ═CH ₂ (wherein R ¹¹ is a hydrogen atom or a methyl group, n is an integer of 0 to 17, and m is 1) An integer of -10)
As a specific example,
(CF ₃ ) ₂ CF (CF ₂ ) ₈ (CH ₂ ) ₂ OCOCH═CH ₂
Etc.

(A-3) CF ₃ (CF ₂ ) _n SO ₂ N (R ¹² ) (CH ₂ ) _m OCOCR ¹¹ ═CH ₂ (In the formula, R ¹¹ is a hydrogen atom or a methyl group, and R ¹² has 1 to 10 carbon atoms. Alkyl group, n is an integer of 2-19, m is an integer of 1-10)
As a specific example,
CF ₃ (CF ₂ ) ₇ SO ₂ N (CH ₃ ) (CH ₂ ) ₂ OCOCH═CH ₂ ,
_{CF 3 (CF 2) 7 SO} 2 N (C 2 H 5) (CH 2) 2 OCOC (CH 3) = CH 2
Etc.

(A-4) (CF ₃ ) ₂ CF (CF ₂ ) _n CH ₂ CH (OR ¹⁴ ) (CH ₂ ) _m OCOCR ¹¹ ═CH ₂ (wherein R ¹¹ is a hydrogen atom or a methyl group, R ¹⁴ is hydrogen) An atom or an acyl group having 1 to 10 carbon atoms, n is an integer of 0 to 17, and m is an integer of 1 to 10)
As a specific example,
_{(CF 3) 2 CF (CF} 2) 8 CH 2 CH (OCOCH 3) CH 2 OCOC (CH 3) = CH 2,
(CF ₃ ) ₂ CF (CF ₂ ) ₈ CH ₂ CH (OH) CH ₂ OCOCH═CH ₂
Etc.

As the monomer (b), for example, the formula:
^{_{CH 2 = CR 15 COO- (R}} 16 O) n -R 17
(Wherein R ¹⁵ and R ¹⁷ are a hydrogen atom or a methyl group, R ¹⁶ is an alkylene group having 2 to 6 carbon atoms, and n is an integer of 3 to 50). Is preferred.

R ¹⁶ is usually preferably —CH ₂ CH ₂ —, but may be —CH (CH ₃ ) CH ₂ —, —CH (C ₂ H ₅ ) CH ₂ — or the like. That is, in the present invention, polyethylene glycol acrylate or methacrylate in which R ¹⁶ is —CH ₂ CH ₂ — can be used particularly preferably. Further, n is selected from an integer of 3 to 50. However, when n is selected from an integer of 9 to 25, particularly good results are obtained. Of course, it may be in the form of a mixture of two or more monomers having different types of R ¹⁶ or n.

Examples of the monomer (b) are given below. You may use these individually or in mixture of 2 or more types.
_{(B-1) CH 2 =} CR 15 COO (CH 2 CH 2 O) n R 17 ( wherein, R ¹⁵ and R ¹⁷ are a hydrogen atom or a methyl radical, n is an integer of 3 to 50)
As a specific example,
_{CH 2 = C (CH 3)} COO (CH 2 CH 2 O) 3 H,
_{CH 2 = C (CH 3)} COO (CH 2 CH 2 O) 6 H,
_{CH 2 = C (CH 3)} COO (CH 2 CH 2 O) 9 H,
_{CH 2 = C (CH 3)} COO (CH 2 CH 2 O) 40 H,
_{CH 2 = C (CH 3)} COO (CH 2 CH 2 O) 9 CH 3,
_{CH 2 = C (CH 3)} COO (CH 2 CH 2 O) 23 CH 3
Etc.

(B-2) CH ₂ = CR ¹⁵ COO (CH ₂ CH (CH ₃ ) O) _n R ¹⁷ (wherein R ¹⁵ and R ¹⁷ are a hydrogen atom or a methyl group, and n is an integer of 3 to 50)
As a specific example,
_{CH 2 = C (CH 3)} COO (CH 2 CH (CH 3) O) 12 H,
CH ₂ = CHCOO (CH ₂ CH (CH ₃ ) O) ₁₁ CH ₃
Etc.

(B-3) CH ₂ = CR ¹⁵ COO (CH ₂ CH ₂ O) _n (CH ₂ CH (CH ₃ ) O) _m R ¹⁷ (wherein R ¹⁵ and R ¹⁷ are a hydrogen atom or a methyl group, and n + m is An integer from 3 to 50)
As a specific example,
_{CH 2 = C (CH 3)} COO (CH 2 CH 2 O) 5 (CH 2 CH (CH 3) O) 3 H
Etc.

The monomer (c) 3-chloro-2-hydroxypropyl (meth) acrylate has the formula:
^{_{CH 2 = CR 18 COOCH 2 CH}} (OH) CH 2 Cl
(Wherein R ¹⁸ is a hydrogen atom or a methyl group) and / or 3-chloro-2-hydroxypropyl acrylate and / or 3-chloro-2-hydroxypropyl methacrylate.

Monomer (d) glycerol mono (meth) acrylate has the formula:
^{_{CH 2 = CR 19 COOCH 2 CH}} (OH) CH 2 OH
(Wherein R ¹⁹ is a hydrogen atom or a methyl group) and is glycerol monoacrylate and / or glycerol monomethacrylate.

  In the copolymer as a polymeric fluorine-based surfactant that can be used in the present invention, the copolymerization ratio of the (meth) acrylic acid ester (monomer (a)) having a fluoroalkyl group is at least 5% by mass, Preferably it is 6-70 mass%.

  The copolymerization ratio of the polyalkylene glycol (meth) acrylate (monomer (b)) is at least 10% by mass, preferably 14 to 60% by mass. If it is less than 10% by mass, the dispersibility in water tends to decrease.

  The copolymerization ratio of 3-chloro-2-hydroxypropyl (meth) acrylate (monomer (c)) is at least 0.5% by mass, preferably 0.5-30% by mass, and glycerol mono (meth) The copolymerization ratio of acrylate (monomer (d)) is at least 0.5% by mass, preferably 0.5-30% by mass.

  The total copolymerization ratio of 3-chloro-2-hydroxypropyl (meth) acrylate (monomer (c)) and glycerol mono (meth) acrylate (monomer (d)) is at least 1% by mass, Preferably it is 1.2-30 mass%. The ratio of 3-chloro-2-hydroxypropyl (meth) acrylate (monomer (c)) to the total of monomer (c) and monomer (d) is 10 to 90% by mass, particularly 20%. It is preferable that it is -80 mass%.

  The number average molecular weight of the polymer type fluorosurfactant is 1,000 to 500,000, preferably 5,000 to 200,000. If it is less than 1,000, the durability tends to decrease, and if it exceeds 500,000, the viscosity of the treatment liquid increases and workability may decrease. Further, the polymer type fluorosurfactant may be a random copolymer or a block copolymer.

  In addition to the monomers (a), (b), (c) and (d), the copolymers used as these polymer-type fluorosurfactants include ethylene, vinyl chloride copolymerizable with them. Does not contain fluoroalkyl groups such as vinylidene halide, styrene, (meth) acrylic acid, alkyl esters of (meth) acrylic acid, benzyl methacrylate, vinyl alkyl ketone, vinyl alkyl ether, isoprene, chloroprene, maleic anhydride, and butadiene Monomers can be copolymerized. By copolymerizing these other monomers, the dispersibility, uniform coating property, low refractive index property, water / oil repellency and durability of the copolymer can be improved. In addition, various properties such as solubility, water resistance and the like can be improved as appropriate. The copolymerization ratio of these comonomers not containing a fluoroalkyl group is 0 to 40% by mass, preferably 0 to 20% by mass.

  Specific examples of the copolymer suitable as the polymer-type fluorosurfactant in the present invention include the following copolymer compositions, but are not limited thereto.

(Composition I)
Monomer represented by CF ₃ CF ₂ (CF ₂ CF ₂ ) _n CH ₂ CH ₂ OCOC (CH ₃ ) = CH ₂ (a mixture of n = 3, 4, 5 in a weight ratio of 5: 3: 1) (A) is 19-22 mass parts,
8 to 13 parts by mass of the monomer (b) of CH ₂ ═C (CH ₃ ) COO (CH ₂ CH ₂ O) ₉ CH ₃
4 to 7 parts by mass of the monomer (b) of CH ₂ ═C (CH ₃ ) COO (CH ₂ CH (CH ₃ ) O) ₁₂ H,
₃ to 5 parts by mass of the monomer (c) of CH ₂ ═C (CH ₃ ) COOCH ₂ CH (OH) CH ₂ Cl;
A copolymer comprising 1-2 parts by mass of the monomer (d) of CH ₂ ═C (CH ₃ ) COOCH ₂ CH (OH) CH ₂ OH.

(Composition II)
CF ₃ CF ₂ (CF ₂ CF ₂ ) _n CH ₂ CH ₂ OCOC (CH ₃ ) ═CH ₂ (n = 3, a mixture of compounds having a weight ratio of 5.4: 1 of 5.4: 1) (a ) Is 8 to 13 parts by mass,
8-12 parts by mass of the monomer (b) of CH ₂ ═C (CH ₃ ) COO (CH ₂ CH ₂ O) ₉ CH ₃
4 to 9 parts by mass of the monomer (b) of CH ₂ ═C (CH ₃ ) COO (CH ₂ CH (CH ₃ ) O) ₁₂ H,
_{CH 2 = C (CH 3)} COOCH 2 CH (OH) CH 2 Cl monomer (c) 0.5 to 3 parts by weight,
A copolymer comprising 0.3 to 2 parts by mass of a monomer (d) of CH ₂ = C (CH ₃ ) COOCH ₂ CH (OH) CH ₂ OH.

(Composition III)
CF ₃ CF ₂ (CF ₂ CF ₂ ) _n CH ₂ CH ₂ OCOC (CH ₃ ) = CH ₂ (n = 3, a mixture of compounds having a weight ratio of 3.9: 1 of 3.9: 1) (a ) Is 5-8 parts by mass,
14 to 17 parts by mass of the monomer (b) of CH ₂ ═C (CH ₃ ) COO (CH ₂ CH ₂ O) ₉ CH ₃
5 to 8 parts by mass of the monomer (b) of CH ₂ ═C (CH ₃ ) COO (CH ₂ CH (CH ₃ ) O) ₁₂ H,
_{CH 2 = C (CH 3)} COOCH 2 CH (OH) CH 2 Cl monomer (c) is 0.5 to 1.5 parts by weight,
_{CH 2 = C (CH 3)} COOCH 2 CH (OH) monomer CH ₂ OH (d) consists of 0.5 to 1.5 parts by weight copolymer.

  In addition, as commercial products, KP341 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.), Polyflow No. 75, no. 95 (trade name, manufactured by Kyoeisha Yushi Chemical Industry Co., Ltd.), F-top EF301, EF303, EF352, EF352, EF204 (tradename, manufactured by Tochem Products), Megafuck F171, F173 (trade name, manufactured by Dainippon Ink and Chemicals, Inc.) ), FLORARD FC430, FC431 (trade name, manufactured by Sumitomo 3M), Asahi Guard AG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105, SC-106 (trade name, manufactured by Asahi Glass) and the like can be mentioned. These surfactants can be used alone or in admixture of two or more.

  The compounding amount of the surfactant is usually 100 parts by mass or less, preferably 70 parts by mass or less, particularly preferably 0.1 to 50 parts by mass per 100 parts by mass in total of the polymer components in the antireflection film material. is there.

  You may add a well-known acid to the coating composition which forms the antireflection layer (L2) of this invention as needed.

  The acid is added mainly for the purpose of adjusting the pH of the coating composition to 4 or less, preferably 3 or less, more preferably 2 or less.

  By forming the antireflection layer (L2) with an acidic coating composition, it is possible to prevent acid diffusion and migration from the photoresist layer (L1) to the antireflection layer (L2) after exposure, and the resist pattern shape T-topping can be prevented.

  The acid used in the present invention may be either an organic acid or an inorganic acid. Preferred examples of the organic acid include alkyl sulfonic acids, alkyl benzene sulfonic acids, alkyl carboxylic acids, alkyl benzene carboxylic acids, and those partially fluorinated. And as said alkyl group, a C1-C20 thing is preferable. These organic acids are generally used in the composition in an amount of 0.1 to 2.0% by mass, preferably 0.5 to 1.0% by mass.

  The fluorine-based organic acid may be a fluoroalkylsulfonic acid or fluoroalkylcarboxylic acid whose fluorine chain is composed of a perfluoroalkyl group or a hydrofluoroalkyl group, and may be a linear or branched chain.

  Examples of the fluoroalkyl group include not only a fluoroalkyl group having 1 to 4 carbon atoms but also a fluoroalkyl group having 5 to 15 carbon atoms, and 1,1,2,2,3,3,4 , 4,5,5-decafluoropentyl group; 1,1,2,2,3,3,4,4,5,5,6,6-dodecafluorohexyl group; 1,1,2,2,3 , 3,4,4,5,5,6,6,7,7-tetradecafluoroheptyl group; 1,1,2,2,3,3,4,4,5,5,6,6,7 , 7,8,8-hexadecafluorooctyl group; 1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9-octa Decafluorononyl group; 1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10-eicosafluorodecyl group ; -(Perfluorononyl) ethyl group, 2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11-eico Safluoroundecyl group, perfluorodecylmethyl group, 1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10, 10,11,11-docosafluoroundecyl group, perfluoroundecyl group; 2- (perfluorodecyl) ethyl group, 2,2,3,3,4,4,5,5,6,6,7, 7,8,8,9,9,10,10,11,11,12,12-docosafluorododecyl group, perfluoroundecylmethyl group, 1,1,2,2,3,3,4,4 5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12-tetracosafluorododecyl group, Fluorododecyl group; 2- (perfluoroundecyl) ethyl group, 2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10 , 11,11,12,12,13,13-tetracosafluorotridecyl group, perfluorododecylmethyl group, 1,1,2,2,3,3,4,4,5,5,6,6, 7,7,8,8,9,9,10,10,11,11,12,12,13,13-hexacosafluorotridecyl group, perfluorotridecyl group; 2- (perfluorododecyl) ethyl group 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 9, 9, 10, 10, 11, 11, 12, 12, 13, 13, 14 , 14-hexacosafluorotetradecyl group, perfluorotridecylmethyl group, 1,1,2,2,3,3,4 , 4, 5, 5, 6, 6, 7, 7, 8, 8, 9, 9, 10, 10, 11, 11, 12, 12, 13, 13, 14, 14-octacosafluorotetradecyl group, Perfluorotetradecyl group; 2- (perfluorotridecyl) ethyl group, 2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10 , 10, 11, 11, 12, 12, 13, 13, 14, 14, 15, 15-octacosafluoropentadecyl group, perfluorotetradecylmethyl group, 1,1,2,2,3,3,4 4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,13,13,14,14,15,15-triacontafluoro Examples thereof include a pentadecyl group and a perfluoropentadecyl group.

  Specific examples of such a fluoroalkylsulfonic acid include 2- (perfluoropropyl) ethanesulfonic acid, 1,1,2,2,3,3,4,4,5,5-decafluoropentanesulfonic acid, Perfluoropentanesulfonic acid; 2- (perfluorobutyl) ethanesulfonic acid, 1,1,2,2,3,3,4,4,5,5,6,6-dodecafluorohexanesulfonic acid, perfluorohexane 2-sulfonic acid; 2- (perfluoropentyl) ethanesulfonic acid, 1,1,2,2,3,3,4,4,5,5,6,6,7,7-tetradecafluoroheptanesulfonic acid, Fluoroheptanesulfonic acid; 2- (perfluorohexyl) ethanesulfonic acid, 1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8-hexadeca Fluorooct Sulfonic acid, perfluorooctanesulfonic acid; 2- (perfluoroheptyl) ethanesulfonic acid, 1,1,2,2,3,3,4,4,5,5,6,6,7,7,8, 8,9,9-octadecafluorononanesulfonic acid, perfluorononanesulfonic acid; 2- (perfluorooctyl) ethanesulfonic acid, 1,1,2,2,3,3,4,4,5,5 6,6,7,7,8,8,9,9,10,10-eicosafluorodecanesulfonic acid, perfluorodecanesulfonic acid; 2- (perfluorononyl) ethanesulfonic acid, 1,1,2, 2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11-docosafluoroundecanesulfonic acid, perfluoroundecanesulfonic acid; 2- (Perfluorodecyl) eta Sulfonic acid, 1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12 -Tetracosafluorododecanesulfonic acid, perfluorododecanesulfonic acid; 2- (perfluoroundecyl) ethanesulfonic acid, 1,1,2,2,3,3,4,4,5,5,6,6 7,7,8,8,9,9,10,10,11,11,12,12,13,13-hexacosafluorotridecanesulfonic acid, perfluorotridecanesulfonic acid; 2- (perfluorododecyl) Ethanesulfonic acid, 1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12, 12,13,13,14,14-octacosafluorotetradecanesulfonic acid, perfluorote Tradecanesulfonic acid; 2- (perfluorotridecyl) ethanesulfonic acid, 1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9 9, 10, 10, 11, 11, 12, 12, 13, 13, 14, 14, 15, 15-triacontafluoropentadecanesulfonic acid, perfluoropentadecanesulfonic acid, and the like.

  Specific examples of the fluoroalkylcarboxylic acid include 2- (perfluoropropyl) ethanecarboxylic acid, 1,1,2,2,3,3,4,4,5,5-decafluoropentanecarboxylic acid, Fluoropentanecarboxylic acid; 2- (perfluorobutyl) ethanecarboxylic acid, 1,1,2,2,3,3,4,4,5,5,6,6-dodecafluorohexanecarboxylic acid, perfluorohexanecarboxylic acid Acid; 2- (perfluoropentyl) ethanecarboxylic acid, 1,1,2,2,3,3,4,4,5,5,6,6,7,7-tetradecafluoroheptanecarboxylic acid, perfluoro Heptanecarboxylic acid; 2- (perfluorohexyl) ethanecarboxylic acid, 1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8-hexadecafluoro Octane Rubonic acid, perfluorooctanecarboxylic acid; 2- (perfluoroheptyl) ethanecarboxylic acid, 1,1,2,2,3,3,4,4,5,5,6,6,7,7,8, 8,9,9-octadecafluorononanecarboxylic acid, perfluorononanecarboxylic acid; 2- (perfluorooctyl) ethanecarboxylic acid, 1,1,2,2,3,3,4,4,5,5, 6,6,7,7,8,8,9,9,10,10-eicosafluorodecanecarboxylic acid, perfluorodecanecarboxylic acid; 2- (perfluorononyl) ethanecarboxylic acid, 1,1,2, 2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11-docosafluoroundecane carboxylic acid, perfluoroundecane carboxylic acid; 2- (Perfluorodecyl) ethanka Boronic acid, 1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12 -Tetracosafluorododecane carboxylic acid, perfluorododecane carboxylic acid; 2- (perfluoroundecyl) ethane carboxylic acid, 1,1,2,2,3,3,4,4,5,5,6,6 7,7,8,8,9,9,10,10,11,11,12,12,13,13-hexacosafluorotridecane carboxylic acid, perfluorotridecane carboxylic acid; 2- (perfluorododecyl) Ethanecarboxylic acid, 1,1,2,2,3,3,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12, 12,13,13,14,14-octacosafluorotetradecanecarboxylic acid, perfluorotetra Decanecarboxylic acid; 2- (perfluorotridecyl) ethanecarboxylic acid, 1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9, 9,10,10,11,11,12,12,13,13,14,14,15,15-triacontafluoropentadecanecarboxylic acid, perfluoropentadecanecarboxylic acid and the like can be mentioned.

  These fluoroalkylsulfonic acids and fluoroalkylcarboxylic acids can be used alone or in admixture of two or more.

  As the inorganic acid, sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, hydrofluoric acid, hydrobromic acid and the like are preferable. These inorganic acids are preferable for the purpose of adjusting the pH of the coating composition to 4.0 or less. Moreover, the usage-amount of an inorganic acid is normally used in the quantity of 0.01-0.2 mass% with respect to a coating composition. These organic acids and inorganic acids may be used alone or in combination of two or more.

  If necessary, a water-soluble polymer other than the fluoropolymer (A) may be added to the coating composition for forming the antireflection layer (L2) of the present invention. The water-soluble polymer can be used to improve the film formability, and may be used in a range (polymer type, amount used) that does not deteriorate the refractive index and transparency of the film.

  Examples of the water-soluble polymer include polyvinyl alcohols, polyalkyl vinyl ethers (polymethyl vinyl ether, polyethyl vinyl ether), polyacrylic acids, carboxyl group-containing acrylate resins, polymethacrylic acids, polyethylene glycols, and celluloses. .

  The amount of the water-soluble polymer used is 0.1 to 100 parts by weight, preferably 0.5 to 50 parts by weight, more preferably 100 parts by weight of the fluoropolymer (A) contained in the coating composition. 1 to 30 parts by mass, particularly preferably 1 to 10 parts by mass.

  If necessary, a known photoacid generator may be added to the coating composition for forming the antireflection layer (L2) of the present invention. By adding a photoacid generator to the coating composition, it is possible to prevent acid diffusion and migration from the photoresist layer (L1) to the antireflection layer (L2) after exposure, and to make the resist pattern shape T-topped. Can be prevented.

  Examples of the acid generator include onium salts, haloalkyl group-containing compounds, o-quinonediazide compounds, nitrobenzyl compounds, sulfonic acid ester compounds, sulfone compounds and the like. These acid generators may be used alone or in combination of two or more. Can be used. A preferred acid generator is an onium salt.

  The compounding amount of the acid generator is usually 20 parts by mass or less, preferably 10 parts by mass or less, particularly 5 parts by mass or less with respect to 100 parts by mass of the polymer (A) in the coating composition. When there is too much usage-amount of an acid generator, the developability of a resist laminated body will fall, or the transparency and refractive index of an antireflection layer (L2) will be deteriorated.

  Furthermore, the coating composition for forming the antireflection layer (L2) of the present invention includes an antifoaming agent, a light absorbing agent, a storage stabilizer, an antiseptic, an adhesion aid, a photoacid generator, and a dye as necessary. Etc. may be added.

  In the coating composition for forming the antireflection layer (L2) of the present invention, the content of the fluoropolymer (A) varies depending on the type of polymer, molecular weight, type of additive, amount, type of solvent, etc. The viscosity is appropriately selected so as to have an appropriate viscosity capable of forming a thin film. For example, it is 0.1-50 mass% with respect to the whole coating composition, Preferably it is 0.5-30 mass%, More preferably, it is 1-20 mass%, Especially 2-10 mass%.

  The coating composition is applied on the photoresist layer (L1) to form an antireflection layer (L2). As a coating method, a conventionally known method is adopted, and a spin coating method, a cast coating method, a roll coating method and the like can be preferably exemplified, and a spin coating method (spin coating method) is particularly preferable. Other methods for forming the antireflection layer (L2) will be described later.

  Next, an example of a method of forming a photoresist laminate by providing an antireflection layer (L2) on the photoresist layer (L1) of the present invention, and a method of forming a fine pattern using the photoresist laminate. Will be described with reference to the drawings.

  FIG. 1 is a schematic view for explaining each step (a) to (e) of a fine pattern forming method via a method for forming a photoresist laminate according to the present invention.

(A) Photoresist layer (L1) formation step:
First, as shown in FIG. 1A, a photoresist composition is applied to a substrate L0 by a spin coating method or the like in the range of 0.01 to 5 μm, preferably 0.05 to 0.5 μm, more preferably 0.1 to 0.3 μm. Apply with the film thickness.

  Next, a pre-bake process is performed at a predetermined temperature of 150 ° C. or lower, preferably 80 to 130 ° C., to form a photoresist layer L1.

  As the substrate used here, for example, a silicon wafer; a glass substrate; a silicon wafer or glass substrate provided with an organic or inorganic antireflection film; various insulating films, electrodes, wirings, etc. are formed on the surface. Silicon wafers having different steps; mask blanks; III-V compound semiconductor wafers such as GaAs and AlGaAs and II-VI compound semiconductor wafers; piezoelectric wafers such as quartz, quartz, and lithium tantalate.

  As the photoresist composition used in the present invention, a conventional photoresist composition can be used. For example, a positive photoresist (g-line or i-line lithography) mainly composed of novolak resin and diazonaphthoquinone, a chemically amplified positive or negative resist (KrF lithography) using polyhydroxystyrene as a binder resin, and a side chain A chemically amplified positive photoresist (ArF lithography) using an acrylic polymer having an alicyclic structure, an alicyclic polymer having a polynorbornene structure, or the like can be used.

  Since the antireflective layer (L2) of the present invention can realize a lower refractive index than that of the conventional one, in particular, an acrylic polymer having an alicyclic structure in the side chain or an alicyclic structure having a polynorbornene structure. It can be preferably applied in a photolithography process using a chemically amplified positive photoresist (ArF lithography) using a polymer, etc., and effectively aims at precise pattern shape, high dimensional accuracy of the pattern, and their reproducibility. Is achieved.

(B) Step of forming the antireflection layer (L2):
As shown in FIG.1 (b), the coating composition containing the above-mentioned fluoropolymer (A) is apply | coated by the spin coating method etc. on the photoresist layer L1 after drying. Next, pre-baking is performed as necessary to form the antireflection layer L2.

At that time, the film thickness d _tarc of the antireflection layer L2 is _expressed by the formula:
d _tarc = x · λ / 4n _tarc
( _Where d _tarc is the thickness (nm) of the antireflection layer; x is an odd integer; λ is the exposure wavelength (nm); n _tarc is the refractive index measured at the exposure wavelength (λ) of the antireflection layer) It is preferable to adjust to the calculated film thickness. Thereby, the antireflection effect at the upper interface of the resist film, that is, the reflectance is reduced, and the influence of the standing wave can be reduced.

  The pre-baking conditions are appropriately selected for evaporating the residual solvent (B) in the antireflection layer L2 and further forming a homogeneous thin film. For example, the prebaking temperature is selected from the range of room temperature to 150 ° C, preferably 40 to 120 ° C, more preferably 60 to 100 ° C.

(C) Exposure process:
Next, as shown in FIG. 1C, a specific region 12 is formed by irradiating the photoresist laminate (L1 + L2) with an energy beam as indicated by an arrow 13 through a mask 11 having a desired pattern. A pattern is drawn by selectively exposing.

At this time, as the energy rays (or chemical radiation), for example, g rays (436 nm wavelength), i rays (365 nm wavelength), KrF excimer laser light (248 nm wavelength), ArF excimer laser light (193 nm wavelength), F ₂ laser light ( 157 nm wavelength) and the like, which are appropriately selected according to the photolithography process.

  In addition, X-rays, high-energy electron beams, synchrotron radiation, etc. can be used as exposure light, or the photoresist laminate can be directly subjected to pattern exposure by scanning electron beams, ion beam lines, etc. without using a mask. Is possible.

  Among these, when using KrF excimer laser light or ArF excimer laser light as exposure light, the antireflection effect of the present invention is most exhibited.

  Subsequently, by performing post-exposure baking (PEB process) at 70 to 160 ° C., preferably 90 to 140 ° C. for 30 seconds to 10 minutes, as shown in FIG. 1D, exposure of the photoresist layer L1 is performed. A latent image 14 is formed in the region 12. At this time, since the acid generated by exposure acts as a catalyst to dissolve the dissolution inhibiting group (protecting group), the developer solubility is improved and the exposed portion of the resist film is solubilized in the developer.

  Further, the antireflection layer L2 may be removed in advance by rinsing with pure water or the like before performing the post-exposure baking (PEB process), or may be removed in a development process after PEB.

(D) Development process:
Subsequently, when the photoresist layer L1 subjected to post-exposure baking is developed with a developer, an unexposed portion of the photoresist layer L1 remains on the substrate because of its low solubility in the developer. As described above, the exposed region 12 is dissolved in the developer.

  On the other hand, since the upper antireflection layer L2 is excellent in the solubility of the developer regardless of the exposed part and the unexposed part, even if it remains, it is removed at the same time as the exposed part in the development process.

  As the developer, a 2.38 mass% tetramethylammonium hydroxide aqueous solution is preferably used. Furthermore, in order to adjust the wettability with the antireflection layer L2 surface and the photoresist layer L1 surface, a surfactant, methanol, ethanol, propanol, or butanol or the like is added in a 2.38 mass% tetramethylammonium hydroxide aqueous solution. You may use what added alcohol.

  Next, the developer is washed away with pure water, lower alcohol, or a mixture thereof, and the substrate is then dried, whereby a desired resist pattern 15 as shown in FIG. 1E can be formed.

  In the above example, the case where the photoresist laminate is formed on the substrate L0 has been described. However, this is not limited to a so-called substrate, and may be formed on a predetermined layer such as a conductive film or an insulating film on the substrate. It is also possible to apply an antireflection film (lower antireflection layer) such as DUV-30, DUV-32, DUV-42, DUV-44 made by Brewer Science, etc. on such a substrate, and adhere the substrate closely You may process by a property improvement agent.

  Further, by using the fine resist pattern formed in this way as a mask, a predetermined layer underneath is etched to form a desired fine pattern of a conductive film or an insulating film, and another process is repeated to form an electronic device such as a semiconductor device. Can be manufactured. Since these steps are well known, description thereof will be omitted.

  Next, the present invention will be described based on examples, but the present invention is not limited only to these examples.

In addition, the measuring method of the various physical property values described in the present invention, the claims and the specification is as follows.
(1) Monomeric pKa
For the monomer (m1-1) used in Synthesis Example 1, pKa was measured and calculated by the following method.

(Measurement calculation method of pKa)
Monomer (m1-1):

The measurement calculation method is described by taking as an example.

  0.7865 g of the monomer (m1-1) was added to a water / acetone = 10/15 ml solution and stirred at room temperature. After confirming that the solution was homogeneous, titration was performed with a 0.2 mol / L NaOH solution. The titration curve was obtained by adding 0.15 ml of NaOH solution dropwise and recording the pH at that time. The equivalence point was determined from the inflection point of the titration curve (derivative value of titration curve = maximum value of dpH / dml). In this case, the equivalence point was 14.5 ml. The pH at this half value of 7.25 ml was read from the titration curve to be 10.58. From the titration curve of the water / acetone solution and aqueous solution measured in advance with a blank, the pH difference derived from the liquid-potential difference at the time of dropping 7.25 ml was 1.29. Therefore, from 10.98-1.29 = 9.69, the pKa of this monomer (m1-1) was determined to be 9.69.

  When 1.0865 g of monomer (m1-1) was titrated in the same manner, the equivalence point was 20.15 ml, the half equivalent point was 10.08 ml, and the half equivalent point was The pH was 10.78. The pH difference between the two solutions at 10.08 ml was 1.14, and from 10.78-1.14 = 9.64, the pKa of the monomer (m1-1) was determined to be 9.64.

  When the same operation was performed by replacing the titration solution with about 0.05 mol / L NaOH solution, the equivalence point of 0.115 g of monomer (m1-1) was 8.00 ml, which was 1/2 equivalent. The point was 4.00 ml, and the pH at this time was 10.92. The pH difference between the two solutions at 4.00 ml was 1.38. From 10.92-1.38 = 9.54, the pKa of the monomer (m1-1) was determined to be 9.54.

  From these three experiments, the pKa of the monomer (m1-1) was set to 9.6.

(2) Composition analysis: Calculated from ¹ H-NMR, ¹⁹ F-NMR and IR data.

  For NMR, AC-300 manufactured by BRUKER is used.

¹ H-NMR measurement conditions: 300 MHz (tetramethylsilane = 0 ppm)
¹⁹ F-NMR measurement conditions: 282 MHz (trichlorofluoromethane = 0 ppm)
Measure at room temperature under the following conditions.

  IR analysis: Measured at room temperature with a Fourier transform infrared spectrophotometer 1760X manufactured by Perkin Elmer.

(3) Number average molecular weight:
By gel permeation chromatography (GPC), Tosoh Co., Ltd. GPC HLC-8020 was used, Shodex column (one GPC KF-801, one GPC KF-802, two GPC KF-806M) This was measured by flowing tetrahydrofuran (THF) as a solvent at a flow rate of 1 ml / min, and the molecular weight was calculated using monodisperse polystyrene as a standard.

(4) Fluorine content of fluoropolymer (% by mass):
Burn 10 mg of sample by the oxygen flask combustion method, absorb the decomposition gas in 20 ml of deionized water, and measure the fluorine ion concentration in the absorption liquid by the fluorine selective electrode method (fluorine ion meter, model 901 manufactured by Orion). The value obtained by is adopted.

(5) OR group content of fluorine-containing polymer (number of moles / 100 g of polymer):
Calculated from ¹ H-NMR, ¹⁹ F-NMR and IR data. For NMR, AC-300 manufactured by BRUKER is used.

¹ H-NMR measurement conditions: 300 MHz (tetramethylsilane = 0 ppm)
¹⁹ F-NMR measurement conditions: 282 MHz (trichlorofluoromethane = 0 ppm)
The number of moles of the hydrophilic group contained in 100 g of the polymer is calculated from the existing ratio of each structural unit in the polymer.

(6) Solvent Solubility of Fluoropolymer The solvent is mixed with a solvent so that the concentration of the fluoropolymer is 5% by mass and left at room temperature for 24 hours while stirring, and the appearance of the solution is observed. Evaluation is performed according to the following criteria.
◯: Completely dissolved and became a transparent and uniform solution.
X: The solution was partially or completely insoluble and opaque.

(7) Solubility of fluorinated polymer in water / isopropanol mixed solvent To 1 g of fluorinated polymer, 9 g of water / isopropanol (IPA) mixed solvent was added and allowed to stand at room temperature for 24 hours with stirring, and further at room temperature for 24 hours. After placement, observe the appearance of the solution. Evaluation is performed according to the following criteria.
○: Completely dissolved, and became a transparent and low-viscosity uniform solution.
Δ: A transparent and uniform solution was obtained, but a highly viscous gel solution was obtained.
X: The solution was partially or completely insoluble and opaque.

(8) Fluoropolymer Developer Solubility Solubility in a standard developer (2.38% tetramethylammonium hydroxide aqueous solution) so that the fluoropolymer concentration is 5% by mass at room temperature while stirring. Leave for 24 hours and observe the appearance of the solution. Evaluation is performed according to the following criteria.
◯: Completely dissolved and became a transparent and uniform solution.
X: The solution was partially or completely insoluble and opaque.

(9) pH measurement of coating composition The pH is measured at 25 ° C using pH METER F-22 manufactured by HORIBA.

(10) Refractive index of coating A coating composition containing a fluoropolymer is applied to an 8-inch silicon wafer substrate using a spin coater for 3 seconds at 300 rpm, then for 20 seconds at 4000 rpm while rotating the wafer, A film is formed while adjusting to a film thickness of about 100 nm after drying.

  With respect to each coating film formed on the silicon wafer substrate by the above method, the refractive index and film thickness at 248 nm and 193 nm wavelength light are measured using a spectroscopic ellipsometer (VASE ellipsometer manufactured by JA Woollam).

(11) Contact angle of water to water of coating The contact angle of 3 μl of pure water is measured using a contact angle meter (CA-DT manufactured by Kyowa Interface Chemical Co., Ltd.).

(12) Dissolving speed of developer solution of coating film The developing solution dissolution speed (nm / sec) is measured by the following crystal oscillator method (QCM method).

Sample preparation:
A coating composition containing a fluoropolymer is applied to a quartz resonator plate with a diameter of 24 mm coated with gold and dried, and then a film of about 100 nm is prepared.

Measurement of developer dissolution rate:
The film thickness is calculated and measured by converting from the vibration frequency of the crystal resonator plate.

  The quartz vibrator plate coated with the fluoropolymer prepared above is immersed in a 2.38 mass% concentration of tetramethylammonium hydroxide (TMAH) aqueous solution as a standard developer, and the film of the film with respect to time from the time of immersion is immersed. The change in thickness is measured by the change in frequency, and the dissolution rate per unit time (nm / sec) is calculated (Reference: Advances in Resist Technology and Processings of SPIE Vol. 4690, 904 (2002)).

(13) Reflectivity of laminate The reflectivity at 248 nm and 193 nm wavelength light is measured using a spectroscopic ellipsometer (VASE ellipsometer manufactured by JA Woollam).

Synthesis example 1
In a 100 ml glass four-necked flask equipped with a reflux condenser, a thermometer and a stirrer, the pKa is 9.6:

40.0g

Then, 9.2 g of an 8.0 mass% perfluorohexane solution was added, and while purging with a dry ice-methanol bath, nitrogen purging and evacuation were repeated to remove dissolved oxygen in the solution. Polymerization was carried out with stirring at 20 ° C. for 24 hours to obtain a highly viscous solid.

  A solution in which this solid was dissolved in acetone was put into hexane, purified by reprecipitation, and then vacuum dried to obtain 38.2 g of a colorless and transparent polymer.

When this polymer was analyzed by ¹⁹ F-NMR analysis, ¹ H-NMR analysis and IR analysis, it was a fluorine-containing polymer consisting only of the structural unit of the OH group-containing fluorine-containing allyl ether.

  Moreover, when GPC analysis was conducted, the number average molecular weight was 76,000.

  This fluorine-containing polymer had a fluorine content of 65.3% by mass and an OH group content of 0.259 mol / 100 g of polymer.

Synthesis example 2
In a 100 ml glass four-necked flask equipped with a reflux condenser, a thermometer, and a stirring device,
The monomer represented by the formula (m1-1) used in Synthesis Example 1 was 9.07 g.

6.14 g,

4.14 g of a 8% perfluorohexane solution of fluorine-containing peroxide was added, and while purging with a dry ice-methanol bath, nitrogen purging and evacuation were repeated to remove dissolved oxygen in the solution. Polymerization was carried out with stirring at 20 ° C. for 24 hours to obtain a highly viscous solid.

  A solution obtained by dissolving this solid material in acetone was put into hexane, purified by reprecipitation, and then vacuum dried to obtain 13.5 g of a fluoropolymer.

The obtained fluoropolymer was analyzed by ¹⁹ F-NMR and IR analysis with the monomer of formula (m1-1).

The mole% ratio was 50:50.

  The molecular weight measured by GPC analysis was 12,000 in terms of number average molecular weight Mn and 17,000 in terms of weight average molecular weight Mw.

  The obtained fluoropolymer was soluble in pure water, acetone, THF and pentafluorodichloropropane (HCFC-225).

Synthesis example 3
10.88 g of the monomer represented by the formula (m1-1) used in Synthesis Example 1

The reaction was conducted in the same manner as in Synthesis Example 2 except that 4.92 g was used to obtain 11.3 g of a fluoropolymer.

The obtained fluoropolymer was analyzed by ¹⁹ F-NMR and IR analysis with the monomer of formula (m1-1).

The mole% ratio was 60:40.

  The molecular weight measured by GPC analysis was 12,000 in terms of number average molecular weight Mn and 17,000 in terms of weight average molecular weight Mw.

  The obtained fluoropolymer swelled in pure water and was soluble in acetone, THF and pentafluorodichloropropane (HCFC-225).

Synthesis example 4
In a 100 ml stainless steel autoclave equipped with a valve, a pressure gauge, and a thermometer, 5.2 g of the monomer of the formula (m1-1) used in Synthesis Example 1 and CH ₃ CCl ₂ F (HCFC) 30 ml of -141b) and 10 g of a 10 mol% perfluorohexane solution of n-heptafluorobutyryl peroxide (HBP) were added, and the inside of the system was sufficiently substituted with nitrogen gas while cooling with a dry ice / methanol solution. Next, 10 g of tetrafluoroethylene (TFE) was charged from the valve, and the reaction was performed while shaking at 30 ° C. During the reaction, there was no change in the gauge pressure in the system (9.0 MPaG before reaction), and it was 9.0 MPaG after 20 hours.

  Unreacted monomer was released 20 hours after the start of the reaction, the precipitated solid was taken out, dissolved in acetone, and then reprecipitated with a hexane solvent to separate and purify the solid content. This solid content was vacuum-dried until it became a constant weight to obtain 3.0 g of a copolymer.

When the composition ratio of this copolymer was analyzed by ¹ H-NMR and ¹⁹ F-NMR, the monomer (m1-1) / tetrafluoroethylene was 93/7 (mol%).

  The molecular weights measured by GPC analysis were Mn 5,300 and Mw 13,000.

  The obtained fluoropolymer was insoluble in water and soluble in acetone, THF and pentafluorodichloropropane (HCFC-225).

  The solubility of the fluoropolymers obtained in the above synthesis examples in the solvents shown in Table 1 was examined. The results are shown in Table 1.

Example 1
(Preparation of coating composition)
10 g of the fluoropolymer obtained in Synthesis Example 1 was dissolved in 35 g of isopropanol. The whole isopropanol solution of the obtained fluoropolymer was added dropwise to 65 g of pure water over about 10 minutes while stirring at room temperature. Further, a mixed solution of water / isopropanol: 65/35% by mass was added to adjust the total amount of the composition to 200 g, and then filtered through a filter having a pore size of 0.2 μm to obtain a uniform coating composition.

  About the obtained coating composition, pH, the refractive index of the film formed using the coating composition, the contact angle with water, and the solution dissolution rate were measured. The results are shown in Table 2.

(Formation of resist laminate)
Formation of photoresist layer (L1):
After applying a photoresist for ArF lithography TArF-P6071 (Tokyo Ohka Kogyo Co., Ltd.) onto an 8-inch silicon substrate while adjusting the film thickness to 200 to 300 nm while changing the rotation speed, 130 A photoresist layer (L1) was formed by pre-baking at 60 ° C. for 60 seconds.

Formation of antireflection layer (L2):
On the photoresist layer (L1) formed above, the coating composition containing the fluorinated polymer prepared in Example 1 was first rotated with a spin coater for 3 seconds at 300 rpm and then for 20 seconds at 4000 rpm to form a film. An antireflection layer (L2) was formed while adjusting the thickness to about 100 nm, and a photoresist laminate was formed.

  The reflectance at 193 nm was measured for the obtained photoresist laminate. The results are shown in Table 2.

  In addition, the photoresist laminate in which the antireflection layer (L2) was formed in the same manner as described above was subjected to stationary paddle development with a developer of 2.38% by mass of tetramethylammonium hydroxide at a temperature of 23 ° C. for 60 seconds. It was confirmed that the antireflective layer (L2) was selectively removed when post-pure water rinsing was performed and this coating composition was used.

Examples 2-4
A coating composition was prepared in the same manner as in Example 1 except that the fluoropolymer and the solvent shown in Table 2 were used, and the characteristics of the film formed using the obtained coating composition were examined in the same manner as in Example 1. It was. The results are shown in Table 2.

  Further, a resist laminate was formed in the same manner as in Example 1, and the reflectance was measured. The results are shown in Table 2.

It is process drawing for demonstrating the formation method of the photoresist laminated body of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Photomask 12 Exposure area 13 Energy beam 14 Latent image 15 Resist pattern L0 Substrate L1 Photoresist layer L2 Antireflection layer

Claims (9)

(I) a step of forming a photoresist layer (L1) on the substrate; and (II) an antireflection layer by applying a coating composition containing the fluoropolymer (A) on the photoresist layer (L1). A method of forming a photoresist laminate including a step of forming (L2),
The fluorine-containing polymer (A) has the formula (M):
-(M)-(N)-(M)
[In the formula, the structural unit M represents the formula (1):

(In the formula, X ¹ and X ² are the same or different, and all are H, F or CF ₃ ; Rf ¹ and Rf ² are the same or different, and both are fluorine-containing alkyl groups having 1 to 8 carbon atoms; H, an alkyl group which may contain an ether bond or a fluorine-containing alkyl group which may contain an ether bond; Y is H, F, CH ₃ or CF ₃ ; Z is CH ₂ , CHF, CF ₂ or C═ O: a structural unit derived from a fluorine-containing monomer (m) represented by n is an integer of 0 to 4; a structural unit N is a monomer copolymerizable with the fluorine-containing monomer (m) (n ) Derived structural unit], and is a fluoropolymer having a structural unit M of 0.1 to 100 mol% and a structural unit N of 0 to 99.9 mol%. Method. The monomer giving the structural unit M is represented by the formula (2):

The method for forming a photoresist laminate according to claim 1, wherein R and n are structural units M1 derived from the monomer (m1) represented by the formula (1). Monomer (m1) is

The method for forming a photoresist laminate according to claim 2, wherein (A) Formula (M):
-(M)-(N)-(M)
[In the formula, the structural unit M represents the formula (1):

(In the formula, X ¹ and X ² are the same or different, and all are H, F or CF ₃ ; Rf ¹ and Rf ² are the same or different, and both are fluorine-containing alkyl groups having 1 to 8 carbon atoms; H, an alkyl group which may contain an ether bond or a fluorine-containing alkyl group which may contain an ether bond; Y is H, F, CH ₃ or CF ₃ ; Z is CH ₂ , CHF, CF ₂ or C═ O: a structural unit derived from a fluorine-containing monomer (m) represented by n is an integer of 0 to 4; a structural unit N is a monomer copolymerizable with the fluorine-containing monomer (m) (n ) Derived structural unit], wherein the structural unit M is 0.1 to 100 mol% and the structural unit N is 0 to 99.9 mol%, and (B) an aqueous solvent or an organic solvent. A coating composition comprising: The coating composition according to claim 4, wherein in the fluoropolymer (A), the structural unit M is 70 to 100 mol% and the structural unit N is 0 to 30 mol%. In the fluoropolymer (A), the monomer that gives the structural unit M is represented by the formula (2):

The coating composition according to claim 4 or 5, which is a structural unit M1 derived from the monomer (m1) represented by the formula (R and n are the same as those in the formula (1)). Monomer (m1) is

The coating composition according to claim 6, which is a monomer represented by: The coating composition according to any one of claims 4 to 7, wherein the coating composition further comprises (C) at least one selected from the group consisting of ammonia and organic amines. The coating composition according to claim 8, wherein at least one (C) selected from the group consisting of ammonia and organic amines is at least one selected from ammonia and hydroxylamines.

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