WO2006003810A1

WO2006003810A1 - Positive-working resist composition and method for resist pattern formation

Info

Publication number: WO2006003810A1
Application number: PCT/JP2005/011334
Authority: WO
Inventors: Kazufumi Sato; Sachiko Yoshizawa
Original assignee: Tokyo Ohka Kogyo Co., Ltd.
Priority date: 2004-07-01
Filing date: 2005-06-21
Publication date: 2006-01-12
Also published as: JP2006018016A; TW200606587A; TWI299435B

Abstract

This invention provides a positive-working resist composition, which has a high level of resolution and, at the same time, can improve at least one of rectangular profile, LER, DOF, and EL margin of a resist pattern, and a method for resist pattern formation. The positive-working resist composition comprises a resin component (A), which can undergo an increase in alkali solubility through the action of an acid, and an acid generating agent component (B) which generates an acid upon exposure to light. The resin component (A) comprises a copolymer (A1) comprising constitutional units (a1) containing a phenolic hydroxyl group, constitutional units (a2) containing a lactone-containing monocyclic or polycyclic group, and constitutional units (a3) containing an acid-dissociative dissolution inhibiting group.

Description

Specification

Positive resist composition and resist pattern forming method

Technical field

[0001] The present invention relates to a positive resist composition and a resist pattern forming method using the positive resist composition.

Background art

In recent years, in the manufacture of semiconductor elements and liquid crystal display elements, miniaturization has rapidly progressed due to advances in lithography technology. As a technique for miniaturization, the wavelength of an exposure light source is generally shortened. Specifically, in the past, ultraviolet rays typified by g-line and i-line were used, but now KrF excimer laser (248 nm) has been introduced, and ArF excimer laser (193 nm) has begun to be introduced. Yes.

[0003] As one of resist materials that satisfy the high-resolution conditions that can reproduce patterns with fine dimensions, a base resin that changes alkali solubility under the action of an acid and an acid generator that generates an acid upon exposure to light. A chemically amplified resist composition dissolved in an organic solvent is known.

Chemically amplified positive resist compositions, which have been proposed as resist materials suitable for exposure using a KrF excimer laser, generally use a part of the hydroxyl groups of polyhydroxystyrene-based resin as acid dissociation as the base resin. Those protected with a soluble dissolution inhibiting group are used (for example, see Patent Document 1).

The acid dissociable, dissolution inhibiting group is represented by a so-called acetal group such as a chain ether group represented by a 1-ethoxyethyl group or a cyclic ether group represented by a tetrahydrobiranyl group, and a tert-butyl group. Tertiary alkyl groups, tertiary alkoxycarbonyl groups typified by tert-butoxycarbonyl groups, etc. are mainly used. Patent Document 1: Japanese Patent Application Laid-Open No. 5-249682

Disclosure of the invention

Problems to be solved by the invention

[0004] In recent years, resist patterns have become increasingly finer, and as the demand for high resolution has further increased, the linearity of resist patterns and the line pattern sidewall surface becomes non-uniform. Improvements in shape problems such as roughness (LER), and exposure margin (EL margin), which represents the amount of change in exposure when the variation in depth of focus (DOF) and pattern dimensions are within the specified range It has become an important issue.

The present invention has been made in view of the above circumstances, and has a high resolution and a positive resist composition that can improve at least one of the rectangularity of a resist pattern, LER, DOF, and EL margin. It is an object of the present invention to provide an object and a method for forming a resist pattern.

Means for solving the problem

In order to achieve the above object, the present invention employs the following configuration.

That is, the positive resist composition of the present invention comprises a positive resist composition comprising a resin component (A) whose alkali solubility increases by the action of an acid and an acid generator component (B) that generates an acid upon exposure to light. In the product, the resin component (A) comprises a structural unit (al) having a phenolic hydroxyl group, a structural unit (a2) having a ratatone-containing monocyclic or polycyclic group, and an acid dissociable, dissolution inhibiting group. And a copolymer (A1) having a structural unit (a3).

In the resist pattern forming method of the present invention, a positive resist film is formed on a substrate using the positive resist composition of the present invention, and the positive resist film is selectively exposed, A resist pattern is formed by performing development processing.

In the present invention, exposure includes electron beam irradiation. “Unit” and “constituent unit” mean a monomer unit constituting a polymer.

The invention's effect

[0007] According to the present invention, a positive resist yarn composition and a resist pattern that have high resolution and can improve at least one of the rectangularity of the resist pattern, LER, D OF, and EL margin. A forming method is obtained.

BEST MODE FOR CARRYING OUT THE INVENTION

[0008] The positive resist composition of the present invention comprises a resin component (A) whose alkali solubility is increased by the action of an acid, and an acid generator component (B) which generates an acid upon exposure.

[0009], Axillary component (A) (hereinafter, also referred to as (A) component) The resin component (A) comprises a structural unit (al) having a phenolic hydroxyl group, a structural unit (a2) having a ratatone-containing monocyclic or polycyclic group, and a structural unit having an acid dissociable, dissolution inhibiting group (a 3) (A1) (hereinafter also referred to as component (A1)).

In component (A), when the acid generated from component (B) acts upon exposure, the acid dissociable, dissolution inhibiting group contained in component (A1) dissociates, and as a result, the entire component (A) is alkali-free. Changes from soluble to alkali-soluble.

Therefore, in the formation of a resist pattern, if exposure is performed through a mask pattern or if post-exposure heating is performed in addition to exposure, the exposed portion turns to Al force-resoluble, while the unexposed portion remains alkali-insoluble. By developing, a positive resist pattern can be formed.

[0010] '(Al) component

The structural unit (al) is a structural unit having a phenolic hydroxyl group. Preferred is a structural unit (al-1) represented by the following general formula (I), that is, a structural unit derived from (α-methyl) hydroxystyrene.

The term “(α-methyleno) hydroxystyrene” means one or both of hydroxystyrene and α-methylenohydroxystyrene. In other words, “—methyl) hydroxystyrene” is a general term for hydroxystyrene and α-methylhydroxystyrene. “Structural unit from which (α-methyl) hydroxystyrene force is also derived” is a structural unit that is formed by the cleavage of the ethylenic double bond of (α-methyl) hydroxystyrene, which is evident from the general formula (I) Means.

In the structural unit (al-1), the position of the hydroxyl group can be any of the o-position, m-position, and p-position, but the p-position is preferred because it is readily available and inexpensive. ,.

[0011] [Chemical 1]

[In the formula, R is a hydrogen atom or a methyl group.]

[0013] <Structural unit (a2)>

The structural unit (a2) is a structural unit having a latathone-containing monocyclic or polycyclic group.

In the present invention, the ratatone-containing monocyclic or polycyclic group is a monocyclic group having a rataton ring force or a polycyclic group having a rataton ring. At this time, the Rataton ring means one ring containing the CO—O structure, and this is counted as the first ring. Therefore, in the case of only a rataton ring, it is called a rataton-containing monocyclic group, and when it has another ring structure, it is called a rataton-containing polycyclic group regardless of the structure.

[0014] The structural unit (a2) is preferably the structural unit (a2-1) represented by the following general formula (II), that is, the hydrogen atom of the carboxy group of (meth) acrylic acid is X (latatone-containing). A structural unit derived from a (meth) acrylate ester substituted with a monocyclic or polycyclic group). In the present specification, “(meth) acrylic acid” means either methacrylic acid or acrylic acid. In other words, “(meth) acrylic acid” is a general term for methacrylic acid and acrylic acid. In the present specification, “(meth) acrylate” means one or both of meta acrylate and acrylate. In other words, “(meth) acrylate” means either one of meta acrylate or acrylate. Means.

[0015] [Chemical 2]

[In the formula, R represents a hydrogen atom or a methyl group, and X represents a ratatone-containing monocyclic or polycyclic group.]

Specifically, as the structural unit (a2), a structural unit (a2-11) represented by the following general formula (IV) and a structural unit (a2-12) represented by the following general formula (V): , A structural unit (a2-13) represented by the following general formula (VI), and a structural unit (a2-14) represented by the following general formula (VII), at least one selected from group power is preferably used. It is done.

Particularly preferred is the structural unit (a2-13) represented by the general formula (VI).

[0018] [Chemical 3]

[In the formula, R is a hydrogen atom or a methyl group.] [0022] [Chemical 5]

[0023] The compound represented by the general formula (VI) exists as a mixture of heterogeneous substances in which the binding position of carboxyl oxygen is at the 5th or 6th position.

(In the formula, R is a hydrogen atom or a methyl group.)

[0024] [Chemical 6]

[In the formula, R is a hydrogen atom or a methyl group.]

[0026] <Structural unit (a3)>

The structural unit (a3) is a structural unit having an acid dissociable, dissolution inhibiting group. The structural unit (a3) is not particularly limited, and is a hydroxystyrene-based resin (meta) that has been proposed as a base resin for conventional chemically amplified KrF positive resist compositions and ArF positive resist compositions. ) In acrylic acid-based rosin and the like, those proposed as a structural unit having an acid dissociable, dissolution inhibiting group can be appropriately used. As the structural unit (a3), preferably, the structural unit (a3-1) represented by the following general formula (III), that is, the hydrogen atom of the hydroxyl group of (a-methyl) hydroxystyrene is Y (acid-dissociable, dissolution inhibiting group). ) And the structural unit (a3-2) represented by the following general formula (m), that is, the hydrogen atom of the carboxy group of (meth) acrylic acid is Y (acid dissociable, dissolution inhibiting group). Replaced structural unit force At least one selected is used. Particularly preferred is a structural unit (a3-l) represented by the following general formula (ΠΙ).

[0027] [Chemical 7]

(Wherein R represents a hydrogen atom or a methyl group, and Y represents an acid dissociable, dissolution inhibiting group.) [0028] [Chemical Formula 8]

(In the formula, R represents a hydrogen atom or a methyl group, and Y represents an acid dissociable, dissolution inhibiting group.) [0029] Specific examples of the acid dissociable, dissolution inhibiting group Y include an alkoxyalkyl group, preferably 1 alkoxy Examples thereof include an alkyl group, a tertiary alkyloxycarbonyl group, a tertiary alkyl group, a tertiary alkoxycarboalkyl group, and a cyclic ether group.

[0030] The 1 alkoxyalkyl group has a structure represented by the following general formula (VIII), in which the 1-position is substituted with a chain, branch, or cyclic alkoxy group.

[0031] [Chemical 9] (VIII)

[0032] (wherein, R ¹ represents a hydrogen atom or an alkyl group having a carbon number of 1 to 2, R ² represents a linear, branched, or cyclic alkyl group having 1 to 12 carbon atoms, the R ¹ The end of the alkyl group and the end of the chain or branched alkyl group may be combined to form a ring.) Specific examples include a 1-methoxyethyl group, 1 ethoxyethyl group, l-iso propoxy Echiru group, 1 n Butokishechiru group, 1 tert Butokishechiru group, methoxymethyl group, ethoxymethyl group, i _so propoxymethyl radical, n-butoxymethyl group, 1 alkoxyalkyl groups such as tert-butoxy methyl group; 1-cyclopentyl Ruo key Chez chill Group, 1-cyclohexyloxyl group, 1-tricyclo [5.2.1.0 ² ' ⁶ ] de-loxychetyl group, cyclopentyloxymethyl group, cyclohexyloxymethyl group, tricyclo [5 .2.1.0 ^{^2'6]} de force - Ruokishimechiru 1 alkoxyalkyl group having an alicyclic structure such as groups; Tetorahido Rovira - group, and cyclic ether groups such as tetrahydrofuranyl group.

[0033] Examples of the tertiary alkyl group include chain tertiary alkyl groups such as tert butyl group and tert-amyl group; 1-methyl-1-cyclopentyl group, 1-ethyl-1-cyclopentyl group, 1-methyl 1-cyclo Hexyl group, 1-ethyl 1-cyclohexyl group, 2-methyl 2-adamantyl group, 2-ethyl-2-adamantyl group, 2-propyl 2-adamantyl group, 2- (1-adamantyl) 2-propyl group, 8-methyl-8-tricyclo [5.2 1.0 ^2. ^'6] de force - group, 8 Echiru 8 tricyclo [5.2.1.0 ^2' ^6] dec force - group, 8-methyl - 8 tetracyclo [4.4.0.1 ² ^'5 .1 ⁷ ^'10] de de force - group, 8 -. Echiru 8 tetracyclo ^{^{[4.4.0 1 2' 5 .1 "}} °] tertiary alkyl group having an alicyclic structure such as dodecanyl group Examples of the tertiary alkyloxycarbonyl group include a tert-butyloxycarboxyl group, a tert-amino group. Ruokishikarubo - group, and the like.

Examples of the tertiary alkoxycarboalkyl group include a tert-butyloxycarbonylmethyl group, a tert-amyloxycarboromethyl group, and the like.

[0034] Among these, the 1-alkoxyalkyl group and the 3rd- Secondary alkyl groups are preferred, especially 1 alkoxyalkyl groups. Among them, 1 ethoxyethyl group is particularly preferable.

[0035] In the positive resist composition of the present invention, the proportion of the structural unit (a2) to the total structural units constituting the copolymer (A1) is preferably 5 to 50 mol%, preferably 10 to 30 mol. % Is more preferred. When the structural unit (a2) is more than the above range, the solubility in the developer is insufficient, and a resist pattern may not be formed. On the other hand, if the amount is small, the effect of using the structural unit (a2) cannot be obtained sufficiently! /.

The total proportion of the structural units (al) and (a3) with respect to all structural units constituting the copolymer (A1) is to ensure good solubility in the developer and to obtain the effects of the present invention. it is preferable preferable instrument 50-90 mole ^_0/0 power is 95 mol ^_0/0.

The ratio of the structural unit (a3) to the total of the structural units (al) and (a3) is preferably 5 to 50 mol%, more preferably 10 to 30 mol%. By setting the proportion of the structural unit (a3) to be equal to or less than the upper limit of the above range, the rectangularity of the resist pattern after development is particularly good. In addition, it is possible to effectively prevent development defects (differences) in the resist pattern after development. On the other hand, when the proportion of the structural unit (a3) is not less than the lower limit of the above range, good resolution performance can be obtained.

In the copolymer (A1), the total amount of the structural unit (al), the structural unit (a2), and the structural unit (a3) is 80 mol% with respect to all the structural units constituting the copolymer (A1). It is preferable that this is the case. If it is less than 80 mol%, the resolution tends to deteriorate. The total of the structural unit (al), the structural unit (a2), and the structural unit (a3) is more preferably 90 mol% or more, and most preferably 100 mol%.

[0036] <Other structural units (a4)>

The copolymer (A1) may contain a structural unit (a4) having an acid-stable dissolution inhibiting group in addition to the structural unit (al), the structural unit (a2), and the structural unit (a3). The structural unit (a4) is not particularly limited, and is a hydroxystyrene-based resin (meta) that has been proposed as a base resin in the conventional chemically amplified positive resist composition for KrF and the positive resist composition for ArF. ) In acrylic acid-based rosin, those proposed as a structural unit having an acid-stable dissolution inhibiting group can be appropriately used. [0037] The structural unit (a4) is preferably the structural unit (a4-1) represented by the following general formula (IX), that is, the structural unit from which (α-methyl) styrene force is also derived, and the following general formula (ix) At least one selected from the structural unit (a42), ie, the structural unit substituted with a hydrogen nuclear atom (acid-stable dissolution inhibiting group) of the carboxy group of (meth) acrylic acid is used. .

Among them, the structural unit (a4-1) represented by the general formula (IX) is particularly preferable because of excellent dry etching resistance.

The acid stable dissolution inhibiting group means a group that is not dissociated by an acid.

[0038] [Chemical 10]

(Wherein R is a hydrogen atom or a methyl group, R ³ is a linear or branched alkyl group having 5 carbon atoms, and n is 0 or an integer of 1 to ^3. )

[0040] [Chemical 11]

(In the formula, R represents a hydrogen atom or a methyl group, and Z represents an acid-stable dissolution inhibiting group.) [0042] In the general formula (IX), R ³ represents a straight chain having 1 to 5 carbon atoms. A chain or branched alkyl group, specifically a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, an isopentyl group, a neopentyl group, etc. Are listed. Industrially, a methyl group or an ethyl group is preferred.

n is 0 or an integer of 1 to 3. Of these, n is preferably 0 or 1

In particular, it is preferably 0 from an industrial viewpoint.

In addition, when n is 1 to ³ , the substitution position of R ³ may be o-position, m-position, or p-position. Furthermore, when n is 2 or 3, it is optional. The replacement positions of can be combined.

[0043] Specific examples of the acid-stable dissolution inhibiting group Z in the general formula (ix) include linear and branched alkyl groups such as a methyl group, an ethyl group, and an isopropyl group; a cyclopentyl group, a cyclohexane hexyl group, Isoboru - group, tricyclo [5.2.1.0 ² ^'6] de force - group, 2-Adamanchiru group, tetracyclo [4.4.0.1 ^2' to ^5.1 ⁷ ^'10] alicyclic structure such as dodecyl Mention may be made of the alkyl groups possessed.

[0044] In the present invention, the structural unit (a4) is not essential, but if it is contained, advantages such as an improved focal depth and improved dry etching resistance can be obtained.

In the case where the structural unit (a4) is used, the proportion of the structural unit (a4) in the copolymer (A1) is 0.5 to LO mol% of the total of all the structural units constituting the copolymer (A1). It is preferably 2 to 5 mol%. When the structural unit (a4) is more than the above range, the solubility in the developer tends to deteriorate.

[0045] The mass average molecular weight Mw (in terms of polystyrene by gel permeation chromatography (GPC), the same applies hereinafter) of the copolymer (A1) is not particularly limited, but is preferably 3000 to 30000, more preferably 5000 to 20000. As for the degree of dispersion (MwZMn ratio, Mn is the number average molecular weight) of the copolymer (A1), it is preferable that the degree of dispersion is small because of excellent resolution. Specifically, it is preferably 2.0 or less, more preferably 1.7 or less.

[0046] Examples of the method for producing the copolymer (A1) include [1] a monomer corresponding to the structural unit (al). The monomer corresponding to the structural unit (a2) and the monomer corresponding to the structural unit in the state before the introduction of the acid dissociable, dissolution inhibiting group of the structural unit (a3) are copolymerized and then the structural unit (a3 ), And (2) a monomer corresponding to the structural unit (a3) into which an acid dissociable, dissolution inhibiting group has been introduced in advance. A monomer corresponding to the unit (al), a method of copolymerizing with the monomer corresponding to the unit (a2), and [3] a monomer corresponding to the unit (a3) and a monomer corresponding to the unit (a2). After polymerization, it can be obtained by a method of purifying the structural unit (al) by changing some of the substituents of the structural unit (a3) protected with acid dissociable, dissolution inhibiting groups by hydrolysis or the like to hydroxyl groups. .

[0047] The polymerization method is not particularly limited, but is preferred because radical polymerization is easy.

In particular, solution radical polymerization in which a raw material monomer, a polymerization initiator, a polymerization catalyst, and a chain transfer agent are polymerized in a state of being dissolved in a polymerization solvent is preferable. In this case, for example, a so-called batch polymerization method in which all monomers, polymerization initiator, polymerization catalyst, and chain transfer agent are dissolved in a polymerization solvent and heated to the polymerization temperature, or a monomer is dissolved in the solvent and heated to the polymerization temperature. After polymerization, a polymerization initiator, a polymerization catalyst, a post-addition method of adding a chain transfer agent, a monomer, a polymerization initiator, a polymerization catalyst, a part or all of the chain transfer agent are mixed or independently heated to a polymerization temperature. Dropping inside can be carried out by a so-called drop polymerization method or the like. Above all, the so-called drop polymerization method is preferred because it has high reproducibility for each production lot, and in particular, a so-called independent dropping method in which a monomer and a radical generation source, a polymerization initiator, a polymerization catalyst, and a chain transfer agent are dropped separately. preferable. The polymerization catalyst, polymerization initiator, and chain transfer agent can be supplied in advance in the polymerization system in whole or in part before supplying the polymerizable monomer. In these dropping methods, the molecular weight distribution and composition distribution of the copolymer can be controlled by changing the respective feed rates in accordance with the monomer concentration and composition in the polymerization system, the radical concentration, and the like. it can.

[0048] In the case of radical polymerization, as a polymerization initiator, for example, 2,2'-azobisisobutyric-tolyl (

AIBN), 2,2'-azobis (2-methylbutyoxy-tolyl), 2,2'-azobisisobutyric acid dimethyl, 1,1'-azobis (cyclohexane-1- 1-carbonitryl), 4,4 ' —Azobis (4-cyananovalerate) and other azo compounds, decanol peroxide, lauroyl peroxide, Use organic peroxides such as benzoyl peroxide, bis (3,5,5-trimethylhexanoyl) peroxide, succinic acid peroxide, tert butyl peroxide 2-ethylhexanoate alone or in combination. Can do. In addition, a known thiol compound such as dodecyl mercaptan, mercaptoethanol, mercaptopropanol, mercaptoacetic acid, mercaptopropionic acid, 4,4 bis (trifluoromethyl) -4-hydroxy 1 mercaptobutane is used alone as a chain transfer agent. Or it can mix and use.

[0049] The solvent used for radical polymerization is not particularly limited as long as it is a solvent that can stably dissolve the raw material monomer, the obtained copolymer, the polymerization initiator, and the chain transfer agent. Specific examples of suitable solvents include alcohols such as methanol, ethanol and isopropyl alcohol; ketones such as acetone, methyl ethyl ketone, methyl amyl ketone and cyclohexanone; tetrahydrofuran, dioxane, glyme, Ethers such as propylene glycol monomethyl ether; esters such as ethyl acetate and lactate ethyl; ether esters such as propylene glycol methyl ether acetate; and lactones such as γ-butyrolataton. It can be used by mixing.

The polymerization conditions are not particularly limited, but generally the polymerization temperature is about 40 ° C to 100 ° C. The polymerization time varies depending on the polymerization method and cannot be defined unconditionally. For example, in the case of batch polymerization, the reaction time after reaching the polymerization temperature is selected from 1 to 24 hours, preferably 2 to 12 hours. In the case of dripping polymerization, the monomer composition, concentration and radical concentration in the polymerization system can be kept constant as the dripping time is longer, so the composition and molecular weight of the monomer generated during the dripping time become uniform. However, it is not preferable that the dropping time is too long because it is disadvantageous in terms of production efficiency per hour and stability of the monomer in the dropping solution. Accordingly, the dropping time is selected to be 0.5 to 25 hours, preferably 1 to 10 hours. Since unreacted monomer remains after the completion of the dropping, it is preferable to age the polymer while maintaining the polymerization temperature for a certain period of time. Aging time should be selected within 8 hours, preferably 1-6 hours.

[0050] The copolymer obtained by polymerization contains low molecular weight impurities such as unreacted monomers, oligomers, polymerization initiators and chain transfer agents, and reaction byproducts thereof, and therefore these were removed by the purification process. Is preferred. In this case, the polymerization reaction solution is diluted by adding a good solvent as necessary, and then brought into contact with a poor solvent to precipitate the copolymer as a solid, It is carried out by extracting impurities into the poor solvent phase (hereinafter referred to as reprecipitation) or by extracting impurities into the solvent phase as a liquid-liquid two-phase. In the case of reprecipitation, the precipitated solid is separated from the solvent by a method such as filtration or decantation, and then this solid is re-dissolved with a good solvent and further re-precipitated by adding a poor solvent, or precipitated. The solid can be further purified by a step of washing with a poor solvent or a mixed solvent of a good solvent and a poor solvent. In the case of liquid-liquid two-layer separation, after separation of the poor solvent phase by liquid separation, reprecipitation or liquid-liquid two-phase by adding a poor solvent or a mixed solvent of a good solvent and a poor solvent to the obtained copolymer solution. Further separation can be achieved by separation. These operations can be performed by repeating the same operation or by combining different operations.

[0051] As a method for protecting the hydroxyl group of the copolymer with an acid dissociable, dissolution inhibiting group, the copolymer obtained by the method [1] is prepared by using p-toluenesulfonic acid, trifluoroacetic acid, strong acid ion-exchange resin Examples thereof include a method of reacting with a compound giving an acid dissociable group such as butyl ether or halogenated alkyl ether in the presence of a known acid catalyst.

As a method of changing the acid dissociable, dissolution inhibiting group of the copolymer to a hydroxyl group, the copolymer obtained by the method of [3] can be obtained by using a known method such as p-toluenesulfonic acid, trifluoroacetic acid, strongly acidic ion exchange resin, etc. Examples thereof include a method of reacting with water in the presence of an acid catalyst for hydrolysis.

Among them, a copolymer containing the structural units (al) and (a2) is preferably prepared by the method [1], and then reacted with an alkyl vinyl ether in the presence of the acid catalyst. ) Is more preferable.

[0052] The solvent used in these reactions is not particularly limited as long as it is a solvent capable of dissolving the copolymer. As a specific example of a suitable solvent, the solvent exemplified for the polymerization solvent can be used as it is!

The reaction conditions are not particularly limited, and in general, the reaction temperature can be selected in the range of 0 to 100 ° C. However, considering the influence of the acid catalyst on the solvent and the production stability, 0 to 80 ° C, particularly preferably Select a range of 0-60 ° C. The reaction time varies depending on the reaction temperature and the like, and a time for reaching a desired reaction rate is selected.

After completion of the reaction, the reaction solution is contacted with a known basic compound or anion exchange resin. To remove the acid catalyst.

If necessary, ultrafine solids and insoluble foreign matter can be removed by passing through a filter having micropores with an average pore size of preferably 0.5 μm or less, more preferably 0.1 μm or less. can do. Further, the metal component can be removed by contacting with a filter having a positive zeta potential or a resin filter having an ion exchange group.

[0053] In addition, a low-boiling component can be removed under reduced pressure while supplying a solvent for forming a coating film, if necessary, so that a coating film-forming solution having a predetermined concentration can be obtained. The solvent for forming the coating film is not particularly limited as long as it dissolves the copolymer, but usually it takes into consideration the boiling point, the influence on the semiconductor substrate and other coating films, and the absorption of radiation used in lithography. Selected. Examples of solvents generally used for coating film formation include solvents such as propylene glycol methyl ether acetate, ethyl lactate, propylene glycol monomethyl ether, methyl amyl ketone, y-butyrate rataton, and cyclohexanone. . The amount of the solvent used is not particularly limited, but is usually in the range of 1 part by mass to 20 parts by mass with respect to 1 part by mass of the copolymer.

[0054] The positive resist composition includes, as component (A), a positive resist composition such as polyhydroxystyrene resin, (meth) acrylic resin, in addition to the copolymer (A1). In order to obtain the effects of the present invention, the copolymer (A1) is 80% by mass or more in the component (A) contained in the positive resist composition. It is preferably 90% by mass or more, and most preferably 100% by mass.

The proportion of the component (A) in the positive resist composition can be appropriately adjusted depending on the intended resist film thickness.

[0055], Acid generator (B) (hereinafter sometimes referred to as component (B))

The component (B) can be used without particular limitation from known acid generators used in conventional chemically amplified resist compositions.

Examples of such acid generators include onium salt-based acid generators such as iodine salts and sulfo-um salts, oxime sulfonate-based acid generators, bisalkyl or bis-aryl sulfo-diazomethanes, Diazomethane acid generators such as poly (bissulfol) diazomethanes, nitrobenzyl sulfonate acid generators, iminosulfonate acid generators A wide variety of agents, such as disulfide acid generators, are known.

Specific examples of acid salt-based acid generators include trifluoromethane sulfonate or nonafluorobutane sulfonate of diphenylodonone; trifluoromethanesulfonate or nonafluorolobium of bis (4-tert butylphenol) ododonium. Trifluorosulfonate, trifluoromethanesulfonate, heptafluoropropanosulfonate, or nonafluorobutanesulfonate; trifluorosulfonate sulfonate of tri (4 methylphenol) snorephonium; Its heptafunololpropane sulphonate or its nonafluorobutane sulphonate; dimethyl (4-hydroxynaphthyl) sulphoform trifunoleolomethanes sulphonate, its heptafunol propanes sulphonate Or Nonafluorobutane sulfonate; Trifluoro methane sulfonate of monophenyl dimethyl sulfone, Its heptafluoropropane sulfonate or Nonafluorobutane sulfonate thereof; Trifluoro of diphenyl monomethyl sulfone Fluoromethane sulfonate, its heptafluoropropane sulfonate or its nonafluorobutane sulfonate; (4-methylphenol) diphenylsulfotrifluoromethane sulfonate, its heptafluoropropane sulfonate or its nonafluorolob Tansusulfonate; (4-methoxyphenyl) diphenyl sulfone trifluoromethanesulfonate, heptafluoropropanesulfonate or nonafluorobutanesulfonate; tri (4-tert-butyl) phenol Luz E - © beam of triflate Ruo b methanesulfonyl Natick DOO, its like hepta full O b propane sulfonate or a nona Full O Rob Tan sulfonates over preparative like.

Specific examples of oxime sulfonate-based acid generators include: (methylsulfo-luoxyimino) -phenolacetonitrile, OC- (methylsulfo-roximino) -p-methoxyphenylacetonitrile, α- (trifluoromethylsulfo-luoximino) ) -Phenylaceto-tolyl, _α- (trifluoromethylsulfo-oxyximino) -p-methoxyphenylacetonitrile, at- (ethylsulfonyloxyximino) -p-methoxyphenylacetonitryl, α- ( Propylsulfo-luoxyimino) p-methylphenolacetonitrile, α (methylsulfo-luoxyimino) ρ-bromophenolacetonitrile, bis-Ο (η-butylsulfol) α-dimethyldaroxime, and the like. Among these, a- (Methylsulfo-luximino) -p-methoxyphenylacetonitrile is preferred.

[0057] Among the diazomethane acid generators, specific examples of bisalkyl or bisarylsulfol diazomethanes include bis (isopropylsulfol) diazomethane, bis (p toluenesulfol) diazomethane, bis (1 , 1-dimethylethylsulfol) diazomethane, bis (cyclohexylsulfol) diazomethane, bis (2,4 dimethylphenylsulfol) diazomethane, and the like.

Poly (bissulfonyl) diazomethanes include, for example, 1,3 bis (phenylsulfo-diazomethylsulfol) propane (compound A, decomposition point 135 ° C having the structure shown below. ), 1,4 bis (phenylsulfol diazomethylsulfol) butane (Compound B, decomposition point 147 ° C), 1,6 bis (phenylsulfol diazomethylsulfol) hexane (Compound C, melting point 132 ° C, decomposition point 145 ° C), 1, 10 bis (phenolsulfol diazomethylsulfol) decane (compound D, decomposition point 147 ° C), 1, 2 bis (Cyclohexylsulfol diazomethylsulfol) ethane (Compound E, decomposition point 149 ° C), 1, 3 bis (cyclohexylsulfol diazomethylsulfol) propane ( Compound F, decomposition point 153 ° C), 1, 6 bis (cyclohexylsulfol diazomethylsulfol) hexane ( Compound G, melting point 109 ° C, decomposition point 122 ° C), 1,10 bis (cyclohexylsulfo-diazomethylsulfonyl) decane (Compound H, decomposition point 116 ° C) .

[0058] [Chemical 12]

ON ₉ O

11! 1 It

(CH ₂ ) ₄ -S— C— S

o o

-C NCH

2

As the component (B), one type of these acid generators may be used alone, or two or more types may be used in combination.

Among them, the component (B) preferably contains a diazomethane acid generator. By combining the above component (A) with a diazomethane acid generator, LER is further reduced. And the resolution is improved. In component (B), the amount of diazomethane acid generator is 40-9.

5% by mass is preferred. 50 to 90% by mass is more preferred.

[0060] The component (B) preferably further contains an acid salt-based acid generator in addition to the diazomethane-based acid generator. This improves the sensitivity of the positive resist composition of the present invention. Also, mask reality (mask reproducibility) is improved.

In the component (B), the amount of the salt salt acid generator is preferably 5 to 60% by mass.

0% by mass is more preferable.

When using a combination of a diazomethane acid generator and an acid salt acid generator, the ratio of the two (diazomethane acid generator: sodium salt acid generator, mass ratio) is 9: 1-1: 9 is preferred 8: 2-6: 4 is more preferred.

Further, in the component (B), the total amount of the diazomethane acid generator and the salt salt acid generator is preferably 80% by mass or more and most preferably 100% by mass.

[0061] The content of component (B) is 0.5 to 30 parts by mass, preferably 1 with respect to 100 parts by mass of component (A).

-10 parts by mass. If the amount is less than the above range, pattern formation may not be sufficiently performed. If the amount exceeds the above range, it may be difficult to obtain a uniform solution and may cause a decrease in storage stability.

[0062] 'Organic solvent

The positive resist composition of the present invention can be produced by dissolving the above-described component (A), component (B), and optional components described later in an organic solvent.

As the organic solvent, it is sufficient if each component to be used can be dissolved into a uniform solution. Conventionally, any one or two of the known solvents for chemically amplified resists can be used. These can be appropriately selected and used.

For example, ketones such as γ-butyrolatatone, acetone, methyl ethyl ketone, cyclohexanone, methyl isoamyl ketone, 2-heptanone, ethylene glycol, ethylene glycol monoacetate, diethylene glycol, diethylene glycol monoacetate, propylene Glycol, propylene glycolol monoacetate, dipropylene glycol, or monomethyl ether, monoethyl ether, monopropyl ether, monobutyl ether or monophenyl ether of dipropylene glycol monoacetate, etc. Polyhydric alcohols and their derivatives, cyclic ethers such as dioxane, methyl lactate, ethyl lactate (EL), methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methoxypropionic acid Mention may be made of esters such as methyl and ethyl ethoxypropionate.

These organic solvents may be used alone or as a mixed solvent of two or more.

[0063] Among these, it is preferable to use at least one selected from propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monomethyl ether (PGME), and ethyl lactate (EL).

A mixed solvent obtained by mixing propylene glycol monomethyl ether acetate (PGMEA) and a polar solvent is preferable. The mixing ratio may be appropriately determined in consideration of the compatibility between PGMEA and the polar solvent, but may be within the range of 9: 1 to 1: 9, more preferably 8: 2 to 2: 8. preferable.

More specifically, when EL is blended as a polar solvent, the mass ratio of PGMEA: EL is preferably 8: 2 to 2: 8, more preferably 7: 3 to 3: 7.

In addition, as the organic solvent, a mixed solvent of at least one selected from among PGMEA and EL and γ-petit-mouth rataton is also preferable. In this case, the mixing ratio of the former and the latter is preferably 70: 30-95: 5.

The amount of the organic solvent used is not particularly limited, but it is a concentration that can be applied to a substrate and the like, and is appropriately set according to the coating film thickness. %, Preferably in the range of 5 to 15% by mass.

[0064] · Nitrogen-containing organic compound (C) (hereinafter sometimes referred to as component (C))

The positive resist composition of the present invention is further optional in order to improve the resist pattern shape, post exposure stability of the latent image formed oy the pattern-wise exposure of the resist layer, and the like. As the component, nitrogen-containing organic compound (C) (hereinafter referred to as component (C)) can be blended.

A variety of components (C) have already been proposed, and any known one may be used. Amines, particularly secondary lower aliphatic amines, are tertiary lower aliphatic amines. Is preferred.

Here, the lower aliphatic amine is an alkyl or alkyl alcohol amine having 5 or less carbon atoms, and examples of the secondary and tertiary amines include trimethylamine, jetylamine, triethylamine, di- _n — Forces such as propylamine, tri-n-propylamine, tripentylamine, diethanolamine, triethanolamine, triisopropanolamine, etc. Tertiary aldehyde such as triethanolamine, triisopropanolamine, etc. preferable.

These can be used alone or in combination of two or more.

Component (C) is usually used in the range of 0.01 to 5.0 parts by mass per 100 parts by mass of component (A).

[0065] Acid component (D) (hereinafter also referred to as component (D).)

The purpose is to prevent sensitivity deterioration due to the combination with the component (C) and to improve the resist pattern shape, post exposure stability of the latent image formed by the pattern-wise exposure of the resist layer, etc. In addition, an organic component such as an organic carboxylic acid or an oxo acid of phosphorus or an acid component (D) (hereinafter referred to as the component (D)) that also has a derivative power can be contained as an optional component. The (C) component and the (D) component can be used in combination, or V or one of them can be used.

[0066] As the organic carboxylic acid, for example, malonic acid, succinic acid, malic acid, succinic acid, benzoic acid, salicylic acid and the like are suitable.

Phosphoric acid or its derivatives include phosphoric acid, phosphoric acid di-n-butyl ester, phosphoric acid diphenyl ester, etc., phosphoric acid or derivatives thereof such as phosphonic acid, phosphonic acid dimethyl ester, phosphonic acid Phosphonic acid such as n-butyl ester, phenol phosphonic acid, phosphonic acid diphenyl ester, phosphonic acid dibenzyl ester and derivatives thereof; phosphinic acid such as phosphinic acid, phenylphosphinic acid and Examples thereof include derivatives such as esters, and phosphonic acid is particularly preferable among these.

Component (D) is used in a proportion of 0.01 to 5.0 parts by mass per 100 parts by mass of component (A).

[0067] <Other optional components> The positive resist composition of the present invention may further contain, if desired, miscible additives such as an additional resin for improving the performance of the resist film, a surfactant for improving coatability, and a plasticizer. In addition, stabilizers, colorants, antihalation agents and the like can be added and contained as appropriate.

[0068] Further, as an optional additive, the compound has at least one acid dissociable, dissolution inhibiting group (B), a compound capable of dissociating the dissolution inhibiting group by the action of the generated acid and generating an organic carboxylic acid. The product (E) may be contained.

As the component (E), for example, a phenol derivative having a mass average molecular weight of 200 to 1000 and having 1 to 6 substituted or unsubstituted benzene nuclei is preferable. Specific examples include compounds represented by the following general formula (1).

[0069] [Chemical 13]

(Wherein R ′ is an acid dissociable, dissolution inhibiting group.)

[0071] The acid dissociable, dissolution inhibiting group R 'has so far been known as a chemical amplification type positive resist and can be arbitrarily selected. Specifically, tertiary alkyloxycarbol groups such as tert-butyloxycarbo ol group, tert amyloxycarbolo group; tert butyloxycarboromethyl group, tert butyloxycarboxyl- Tertiary alkyloxycarboalkyl group such as ruetyl group; Tertiary alkyl group such as tert butyl group and tert amyl group; Cyclic ether group such as tetrahydrobiral group and tetrahydrofuranyl group; An alkoxyalkyl group such as a methoxypropyl group is preferred and may be mentioned as one. Of these, tert-butyloxycarbonyl group, tert-butyloxycarboxylmethyl group, tert-butyl group, tetrahydrobiral group, ethoxyethyl group, 1-methylcyclohexyl group and 1-ethylcyclohexyl group are preferred. ,.

However, at least one acid dissociable, dissolution inhibiting group R, needs to use a carboxylic acid generating group such as a tertiary alkyloxycarboalkyl group.

[0072] The positive resist composition of the present invention can be used for forming a resist pattern in the same manner as a conventional positive resist composition for KrF.

With the positive resist composition of the present invention, a LER with high rectangularity is reduced, and a resist pattern with excellent resolution performance can be obtained. Such a resist pattern is highly practical. It also improves DOF and EL margins.

With respect to the effect, the structural unit (a2) having a latathone-containing monocyclic or polycyclic group has hydrophilicity, and the latathone-containing monocyclic or polycyclic group is bulky. Al) is lower in alkali solubility than al), and as a result, a copolymer comprising the structural unit (al), the structural unit (a2), and the structural unit (a3) force is a polyhydroxystyrene that also includes only the structural unit (al). It is thought that this is related to the fact that the hydrophilicity is high and the alkali solubility is low.

The effect of improving the resolution performance, rectangularity, and LER in the present invention can be confirmed by, for example, observing the resist pattern obtained through the development process with a SEM (scanning electron microscope).

Next, the resist pattern forming method of the present invention will be described.

First, the positive resist composition of the present invention is coated on a substrate such as silicon wafer by a spinner or the like, and then prebeta is performed. Next, using an exposure apparatus or the like, the coating film of the positive resist composition is selectively exposed through a desired mask pattern, and then PEB (post-exposure heating) is performed. Subsequently, after developing with an alkali developer, rinsing is performed, and the developer on the substrate and the resist composition dissolved by the developer are washed away and dried.

The steps so far can be performed using a known method. The operating conditions and the like are preferably set as appropriate according to the composition and characteristics of the positive resist composition to be used. The exposure is preferably performed using a KrF excimer laser, but is also useful for electron beam resists, EUV (extreme ultraviolet light), and the like.

In some cases, a post-beta step after the alkali development may be included, and an organic or inorganic antireflection film may be provided between the substrate and the coating layer of the resist composition.

[0074] The heating temperature in the pre-beta and the heating temperature in the post-exposure heating (PEB) may generally be 90 ° C or more, but in order to form a resist pattern with good rectangularity, it is particularly 90 to 120 respectively. ° C, preferably 90-110 ° C is preferred. In addition, by setting this temperature range, the generation of microbridges can be effectively suppressed.

Example

In the following, “%” is “% by mass” unless otherwise specified.

[Synthesis Example 1] <Synthesis of precursor of copolymer (A1)>

In a container kept in a nitrogen atmosphere, P-hydroxystyrene (hereinafter referred to as “PHS”) 24%, p-ethylphenol 43%, methanol 23%, water 10% mixed solution 933 g (hereinafter referred to as monomer 1 solution) ). Separately, in a container kept in a nitrogen atmosphere, 62 g of a mixed solution containing 24% PHS, 43% P-ethylphenol, 23% methanol and 10% water, 39 g of MAIB (dimethyl-2-2, azobis (2-methylpropionate)) Charged and dissolved to prepare an initiator solution. Separately, in a container kept in a nitrogen atmosphere, 252 g of 50% MEK (methylethyl ketone) solution of oxa-tricyclodecanone methacrylate (hereinafter referred to as OTM) and 5.9 g of TDM (tert-dodecyl mercaptan) Charge and mix to prepare a monomer 2 solution. The temperature of the monomer 1 solution was raised to 80 ° C. with stirring, and then the monomer 2 solution and the initiator solution were supplied into a polymerization tank maintained at 80 ° C. for 4 hours to be polymerized. After completion of the feeding, the polymerization temperature was kept at 80 ° C. for 1 hour, and cooled to room temperature. The obtained polymerization solution was dropped into 3500 g of toluene to precipitate a polymer, and then the supernatant was removed. Subsequently, the operation of dissolving in 500 g of methanol, reprecipitating in 3500 g of toluene, and removing the supernatant was repeated three times, and then redissolved in 100 g of methanol. Propylene glycol monomethyl etherate (hereinafter referred to as “PGMEA”) was added while heating the resulting methanol solution under reduced pressure to drive out low-boiling solvents such as methanol, and a copolymer (precursor). P containing 20% by mass A GMEA solution was prepared. This is designated as rosin 1. Carbon 13 (meaning carbon with a mass number of 13; the same applies hereinafter) Nuclear magnetic resonance spectrum ( ¹³ C-NMR) and analysis by GPC were performed to determine the composition (Mw, MwZMn) of the copolymer (precursor).

The composition of the copolymer (precursor);. PHSZ_〇_TM = 82. 5/17 5 (mol ^_0/0),

Molecular weight (Mw); 7300,

Molecular weight distribution (MwZMn); 1.55.

[0076] [Synthesis Example 2] <Introduction of acid dissociable, dissolution inhibiting group into precursor (acetalization)>

A container maintained in a nitrogen atmosphere was charged with 250 g of the resin 1 prepared above and heated to 40 ° C. Next, 20% trifluoroacetic acid (hereinafter referred to as TFA) ZPGMEA solution 1.5 g was added and stirred for 10 minutes, and then 50% ethyl vinyl ether (hereinafter referred to as EVE) ZPGME A solution 17.8 g was added and kept at 40 ° C. The reaction was continued for 6 hours. After completion of the reaction, the reaction mixture was cooled to room temperature, and then passed through an ion exchange resin (B20HG DRY made by Organo) packed in a glass column to remove TFA. This reaction product solution was passed through a filter settable 40QSH manufactured by Cuno Co., Ltd., and then concentrated under reduced pressure to prepare a PGMEA solution containing 30% by mass of an acetalized copolymer. This is designated as rosin 2. This solution was analyzed by ¹³ C-NMR and GPC to obtain the acetalization rate, Mw, and MwZMn.

Here, the acetalization rate means that the hydroxyl group of the precursor PHS unit was substituted with an acetal type acid dissociable, dissolution inhibiting group (1-ethoxy-1-ethyl group) that also induces ethyl vinyl ether force. The ratio of the product is expressed in mol% (the same applies hereinafter). Acetalization rate 33.8%,

Molecular weight Mw = 8000,

Molecular weight distribution Mw / Mn = l.

[0077] The acetal 匕 copolymer (resin 2) obtained in this synthesis example is composed of three structural units represented by the following chemical formula (14). In the chemical formula, x: y: z (molar ratio) = 54.6: 27.9: 17.

5.

[0078] [Chemical 14]

[0079] [Synthesis Example 3] <Introduction of acid dissociable, dissolution inhibiting group into precursor (acetalization)>

In Synthesis Example 2, the weight of the EVEZPGMEA solution was changed to 12.2 g, and the reaction time after the addition of the EVEZ PGMEA solution was changed to 5 hours. A PGMEA solution containing 30% by weight of coalescence was prepared. This is designated as rosin 3. This solution was analyzed by ¹³ C-NMR and GPC to obtain the acetalization rate and Mw and MwZMn.

Acetalization rate 22.9%

Molecular weight Mw = 7860

Molecular weight distribution Mw / Mn = l. 60

[0080] The acetal 匕 copolymer (resin 3) obtained in this synthesis example is composed of three structural units represented by the chemical formula (14). In the chemical formula, x: y: z (molar ratio) = 63. 6: 18. 9: 17.

5.

A positive resist composition was prepared using the resin 2 obtained in Synthesis Example 2 and the resin 3 obtained in Synthesis Example 3 as the component (A).

100 parts by weight of component (A) (resin 2: resin 3 = 5: 5) and (B) as a compound represented by the following chemical formula (2) 1.0 part by weight of the following chemical formula (3) Compound represented by 4.0 parts by mass, compound represented by the following chemical formula (4) 4.0 parts by mass, and compound represented by the following chemical formula (5)

3 parts by weight, 0.28 parts by weight of triethanolamine as component (C) and 0.28 parts by weight of triisopropanolamine, and 2 parts by weight of a compound represented by the following chemical formula (6) as component (E) When , Fluorosurfactant (Product name XR-104, manufactured by Dainippon Ink & Chemicals, Inc.) 0.025 parts are dissolved in a mixed solvent of PGMEA and EL (PGMEA: EL mass ratio is 6: 4) A positive resist composition (solid content concentration 10 mass%) was obtained.

[0082] [Chemical 15]

(3)

H ₃ C—— C = N—— OS0 ₂ -nC ₄ H ₉

H ₃ C—— C = N—— OS0 ₂ -n C ₄ H ₉

(Five)

[0083] [Chemical 16]

[0084] An organic antireflective coating material (trade name DUV-44, manufactured by Brew Science Co., Ltd.) was applied on an 8-inch silicon wafer and baked at 225 ° C for 60 seconds to form a 65 nm thick antireflective coating. To form a substrate. On the substrate, the positive resist composition obtained above is uniformly applied using a spinner, pre-betaned at 100 ° C. for 60 seconds on a hot plate, and dried to form a resist having a thickness of 287 nm. A layer was formed.

[0085] Next, KrF exposure system (wavelength 248nm) NSR-S203B (Nikon, NA (numerical aperture))

= 0.68, 2Z3 annular illumination) and selectively exposed via 8% halftone reticle.

Then, a PEB treatment was conducted under conditions of 110 ° C, 60 seconds, further 23 ° C at 2.38 mass ^_0/0 tetra Mechiruanmo - 60 seconds and puddle developed with Umuhidorokishido solution, then 30 seconds with pure water water Rinse and shake-dry. Furthermore, it was heated at 100 ° C. for 60 seconds and dried to form a 120 nm line-and-space (1: 1) resist pattern (hereinafter referred to as LZS pattern).

[0086] When the substrate on which the LZS pattern was formed in this way was observed with a scanning electron microscope (measurement SEM, S-9200) manufactured by Hitachi, the cross-sectional shape of the LZS pattern was highly rectangular and good. It was something.

3 σ, which is a measure indicating the LER of the pattern formed above, was obtained. As a result, 3 σ of the obtained pattern was 3.4 nm. Note that 3 σ is the result of measuring the width of the resist pattern of the sample at 32 locations using the side length SEM (manufactured by Hitachi, Ltd., trade name “S-9220”) The force is also three times the calculated standard deviation (σ) (3σ). This 3σ means that the smaller the value, the smaller the roughness of the resist pattern.

The depth of focus (DOF) was 0.5 m.

The exposure dose margin (EL margin) obtained in the range of ± 10% for the 120 nmLZS pattern was 14.79%.

[0087] (Comparative Example 1)

As the component (A), prepared except that the 42 mole ^_0/0 of hydroxyl with榭脂γ protected with 1 Eto Kishechiru groups in the same manner as in Example 1 The positive resist composition of polyhydroxystyrene (Mw8000) Then, a resist pattern was formed using the positive resist composition. The resin Y is a copolymer having two structural unit forces represented by the following chemical formula. In the chemical formula, X: y (molar ratio) = 58: 42.

[0088] [Chemical 17]

— C ₂ H>;

The substrate on which the LZS pattern was thus formed was evaluated in the same manner as in Example 1. As a result, the force with which the 120 nm LZS pattern was formed had a round top shape. The LER was 3 σ = 5.5 nm, the depth of focus range was 0.2 / z m, and the exposure margin was 7.73%.

As is clear from the above results, in Example 1, compared with Comparative Example 1, the rectangularity of the resist pattern was better, the LER was reduced, and a fine resist pattern was obtained. In addition, the depth of focus and exposure margin were improved.

Claims

The scope of the claims

[1] A positive resist composition comprising a resin component (A) whose alkali solubility is increased by the action of an acid and an acid generator component (B) that generates an acid upon exposure,

The resin component (A) comprises a structural unit (al) having a phenolic hydroxyl group, a structural unit (a2) having a ratatone-containing monocyclic or polycyclic group, and a structural unit having an acid dissociable, dissolution inhibiting group. A positive resist composition comprising a copolymer (A1) having a position (a3)

[2] The structural unit (al) is represented by the following general formula (I):

[Chemical 1]

(Wherein R is a hydrogen atom or a methyl group), and the structural unit (a2) is represented by the following general formula (II):

[Chemical 2]

(Wherein R represents a hydrogen atom or a methyl group, and X represents a ratatone-containing monocyclic or polycyclic group), and the structural unit (a3 ) Is represented by the following general formula (III)

[Chemical 3]

2. The positive resist composition according to claim 1, which is a structural unit (a3-l) represented by the formula (wherein R represents a hydrogen atom or a methyl group, and Y represents an acid dissociable, dissolution inhibiting group).

[3] The structural unit (a2) is a structural unit (a2-11) represented by the following general formula (IV):

[Chemical 4]

(In the formula, R is a hydrogen atom or a methyl group, and m is 0 or 1.) A structural unit (a2-12) represented by the following general formula (V),

[Chemical 5]

(In the formula, R is a hydrogen atom or a methyl group.) A structural unit represented by the following general formula (VI) ( a2-13), and

. ·Pieces

(In the formula, R is a hydrogen atom or a methyl group.) A structural unit (a2-14) represented by the following general formula (VII):

[Chemical 7]

2. The positive resist composition according to claim 1, which is at least one selected from the group force consisting of: wherein R is a hydrogen atom or a methyl group.

[4] The positive resist composition according to claim 1, wherein the ratio of the structural unit (a3) to the total of the structural units (al) and (a3) is 5 to 50 mol%.

5. The positive resist composition according to claim 1, wherein the proportion of the structural unit (a2) in the copolymer (A1) is 5 to 50 mol%.

[6] The positive resist composition according to [1], wherein the acid dissociable, dissolution inhibiting group of the structural unit (a3) is an alkoxyalkyl group. [7] The positive resist composition according to [1], wherein the acid generator component (B) contains a diazomethane acid generator.

8. The positive resist yarn composition according to claim 7, wherein the acid generator component (B) further contains an onion salt acid generator.

9. The positive resist composition according to claim 1, further comprising a nitrogen-containing organic compound (C).

[10] A positive resist film is formed on the substrate using the positive resist yarn composition according to claim 1, and the positive resist film is selectively subjected to an exposure treatment. A resist pattern forming method, wherein a resist pattern is formed by performing a development process.