JP2008102277A - Chemically amplified positive resist composition for thermal lithography, and resist pattern forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a chemically amplified positive resist composition for thermal lithography, capable of forming a resist pattern by thermal lithography, and to provide a resist pattern forming method using the chemically amplified positive resist composition for thermal lithography. <P>SOLUTION: The chemically amplified positive resist composition for thermal lithography is for forming a resist film for thermal lithography, and the resist film, formed using the chemically amplified positive resist composition for thermal lithography, has absorbance of 0.08 or higher per 100 nm of the film thickness at the wavelength of the exposure light source, used in the thermal lithography. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a chemically amplified positive resist composition for thermal lithography and a resist pattern forming method using the chemically amplified positive resist composition for thermal lithography.

Lithography technology is frequently used for the production of fine structures in various electronic devices such as semiconductor devices and liquid crystal devices.
In the lithography technique, a photosensitive organic material called a photoresist has been conventionally used. As the photoresist, those whose solubility (alkali solubility) in an alkali developer is changed by irradiation (exposure) of radiation such as short-wavelength light such as vacuum ultraviolet rays or electron beam (exposure) is generally used. . Such a photoresist changes its alkali solubility due to, for example, partial decomposition of the structure or formation of a cross-linkage upon exposure. For this reason, a difference in alkali solubility occurs between the exposed portion and the unexposed portion, thereby making it possible to form a resist pattern. That is, when the photoresist is selectively exposed, the alkali solubility of the photoresist partially changes, and the photoresist is composed of a portion having a high alkali solubility and a portion having a low alkali solubility. It will have a pattern. When this photoresist is developed with an alkali, a portion having high alkali solubility is dissolved and removed, whereby a resist pattern is formed.
The photoresist includes a positive type in which the alkali solubility in the exposed area is increased and a negative type in which the alkali solubility in the exposed area is decreased.
As one of photoresists having high sensitivity to an exposure light source with a short wavelength, a photoacid generator (PAG) that generates acid by the action of radiation, and a base material component whose alkali solubility changes by the action of the acid Chemically amplified resist compositions containing these are known (see, for example, Patent Documents 1 and 2).

In the data writing process of an optical ROM (Read Only Memory) disk, in the near future, a lithography technique that realizes pits of at least 100 nm or less is desired in order to realize ultra-high density recording.
As described above, the development of a technique using a light source having a shorter wavelength or a technique using an electron beam has been performed so far.
However, as the wavelength of the light source used for exposure becomes shorter, various difficult problems are caused not only by the light source but also by optical factors. For example, exposure machines tend to increase in price and size as the wavelength of the light source decreases, and when using an electron beam, high voltage conditions, a vacuum chamber, etc. are required to generate an electron beam. As a result, large-scale facilities are required. These problems increase the manufacturing cost of products such as optical CD-ROM discs.

One technique that has been recently developed is thermal lithography. In this method, light is not used directly, but heat distribution generated by light is used. According to thermal lithography, it is possible to perform fine drawing less than the spot diameter of light, and it is possible to form a fine pattern and achieve high speed and low cost.
As an already reported thermal lithography method, there is a method using an inorganic material whose properties are rapidly changed when the temperature becomes a certain level or more. For example, Non-Patent Document 1 describes a method using a laminate in which a ZnS—SiO ₂ layer, a TbFeCo layer, and a ZnS—SiO ₂ layer are laminated in this order on a substrate. This method is thermal lithography using a change in volume due to heat. In such a method, the TbFeCo layer absorbs laser light and generates heat, and when the temperature exceeds 200 ° C., the volume starts to increase. The pattern is formed by increasing the film thickness of the irradiated portion of the laser beam.
In addition, a method using platinum oxide as the inorganic material has been reported (for example, see Non-Patent Document 2). This method uses the property that platinum oxide evaporates explosively when the temperature exceeds a certain temperature. Blue oxide light is applied to the platinum oxide applied to the substrate surface to heat it, and the parts required for processing are removed. I try to remove it. According to this method, it is said that fine pattern formation of 100 nm or less can be realized with blue laser light (wavelength 405 nm).
For example, Non-Patent Document 3 describes a method of using a laminate in which a Ge ₂ Sb ₂ Te ₅ layer, a ZnS—SiO ₂ layer, and a photoresist film are laminated in this order on a polycarbonate substrate. Yes. In this method, first, when irradiated with red laser from the lower side of the substrate, the laser light is absorbed in the _Ge 2 _Sb 2 Te _5, are Ge 2 _Sb 2 Te ₅ generates heat. This heat is transmitted to the upper resist film (negative), and the resist film changes to alkali-insoluble by the action of the heat. Therefore, a resist pattern is formed by alkali developing this.
Japanese Patent No. 2881969 JP 2003-241385 A Jpn. J. et al. Appl. Phys. Vol. 43, no. 8B (2004) pp. L1045-L1047 53rd Joint Conference on Applied Physics, Preliminary Proceedings, pp. 1051 (Spring 2006), 22a-D-9 Jpn. J. et al. Appl. Phys. Vol. 41, no. 9A / B (2002) pp. L1022-L1024

All of the thermal lithography techniques that have been proposed so far use inorganic materials to absorb light and convert its energy into heat. However, many of these inorganic materials are expensive, and there are problems such as poor processability such as substrate etching after resist pattern formation.
As one means for solving the above problem, it is conceivable to perform thermal lithography using only an organic material. However, until now, no technology has been proposed for performing thermal lithography using only organic materials without using inorganic materials.
The present invention has been made in view of the above circumstances, and is a chemically amplified positive resist composition for thermal lithography capable of forming a resist pattern by thermal lithography, and the chemically amplified positive resist composition for thermal lithography. An object of the present invention is to provide a method for forming a resist pattern using the above.

As a result of intensive studies, the present inventors have obtained the above problem by using a chemically amplified positive resist composition in which the absorbance of the formed resist film with light having a wavelength of a light source used for exposure is a predetermined value or more. The present invention has been completed.
That is, the first aspect of the present invention is a chemically amplified positive resist composition for thermal lithography for forming a resist film used for thermal lithography,
The resist film formed using the chemical amplification type positive resist composition for thermal lithography has an absorbance of 0.08 or more per 100 nm thickness at the wavelength of the exposure light source used in the thermal lithography. A chemically amplified positive resist composition for thermal lithography.
According to a second aspect of the present invention, there is provided a step of forming a resist film on a support using the chemically amplified positive resist composition for thermal lithography according to the first aspect. The resist pattern forming method includes a step of performing selective exposure using light having a wavelength of 0.08 or more per 100 nm of film thickness and a step of developing the resist film to form a resist pattern.

In the present specification and claims, “exposure” is a concept including general radiation irradiation.
Unless otherwise specified, the “alkyl group” includes linear, branched and cyclic monovalent saturated hydrocarbon groups.
A “lower alkyl group” is an alkyl group having 1 to 5 carbon atoms.
The “alkylene group” includes linear, branched and cyclic divalent saturated hydrocarbon groups unless otherwise specified.
“Structural unit” means a monomer unit (monomer unit) constituting a resin (polymer).

  The present invention can provide a chemically amplified positive resist composition for thermal lithography capable of forming a resist pattern by thermal lithography, and a resist pattern forming method using the chemically amplified positive resist composition for thermal lithography.

≪Chemically amplified positive resist composition for thermal lithography≫
In the chemically amplified positive resist composition for thermal lithography of the present invention, the resist film formed using the chemically amplified positive resist composition for thermal lithography has a wavelength of an exposure light source used in the thermal lithography, It is necessary to have an absorbance of 0.08 or more per 100 nm of film thickness. When the absorbance is 0.08 or more, a resist pattern can be formed by thermal lithography. That is, the chemical amplification type positive resist composition usually requires a base component (A) whose alkali solubility is increased by the action of acid and an acid generator component (B) which generates an acid by the action of heat. It is contained as a component. The acid generator component (B) used in the chemically amplified positive resist composition usually generates an acid even when heated to a certain temperature or higher, as in the case of exposure. When the resist film comprising the chemically amplified positive resist composition has an absorbance of 0.08 or more, the acid generator component (B) in the resist film is exposed when the resist film is exposed by thermal lithography. Heat is generated at a temperature sufficient to generate acid from the substrate. Therefore, when the resist film is selectively exposed in the formation of the resist pattern, an acid is generated from the acid generator component (B) in the exposed portion, and the alkali solubility of the base material component (A) is caused by the action of the acid. On the other hand, since the unexposed portion remains alkali-insoluble and does not change, a resist pattern can be formed by alkali-developing the resist film.
The upper limit of the absorbance is not particularly limited, and is preferably 0.5 or less, more preferably 0.45 or less, and more preferably 0.45 or less per 100 nm of film thickness in consideration of the influence of thermal interference and lithography characteristics such as sensitivity. Most preferred is 4 or less.

  The said light absorbency can be adjusted by adjusting the kind and compounding quantity of a component mix | blended with a chemically amplified positive resist composition. For example, the absorbance can be adjusted by blending a dye (C) that absorbs light having a wavelength of an exposure light source, which will be described later. The higher the content of the dye (C), the more the light absorption of the dye (C). The higher the performance, the greater the absorbance. Further, the base material component (A) described later absorbs light having a wavelength of an exposure light source used in thermal lithography as in the case of the dye (C) (hereinafter simply referred to as “having light absorption”). In the case of a compound), the absorbance can also be adjusted by adjusting the type and amount of the base component (A).

In the present specification and claims, the absorbance is obtained by forming a resist film on a quartz substrate using the chemically amplified positive resist composition for thermal lithography, and the resist film at the wavelength of the exposure light source. The absorbance is measured, and the absorbance per 100 nm thickness of the resist film is calculated from the value and the thickness of the resist film.
The resist film can be formed by applying an organic solvent solution of the chemically amplified positive resist composition for thermal lithography on a quartz substrate by spin coating and baking. The baking temperature is not particularly limited, and may be set as appropriate according to the chemically amplified positive resist composition to be used.
The absorbance of the resist film can be measured using, for example, a commercially available spectrophotometer.

  As a preferred embodiment of the chemically amplified positive resist composition for thermal lithography of the present invention (hereinafter sometimes simply referred to as the positive resist composition of the present invention), a base component whose alkali solubility is increased by the action of an acid. (A) (hereinafter referred to as component (A)), an acid generator component (B) (hereinafter referred to as component (B)) that generates an acid by the action of heat, and light having a wavelength of the exposure light source. And a positive resist composition containing the absorbing dye (C) (hereinafter referred to as the component (C)). When a resist film formed using such a positive resist composition is selectively exposed at the time of forming a resist pattern, the component (C) mainly absorbs the light and generates heat. This heat acts on the component (B) to generate heat, and the acid acts on the component (A) to increase its alkali solubility.

<(A) component>
The component (A) is not particularly limited, and any component can be selected and used from among a number of components that have been proposed as base materials for chemically amplified positive resist compositions. . As the substrate component, one having an acid dissociable, dissolution inhibiting group is generally used. Such a substrate component is insoluble in alkali before exposure, and when an acid is generated from the component (B) after exposure, the acid dissociable, dissolution inhibiting group is dissociated by the action of the acid and changes to alkali-soluble.

Here, the “base material component” is an organic compound having a film forming ability, and an organic compound having a molecular weight of 500 or more is preferably used. When the molecular weight of the organic compound is 500 or more, the film forming ability is improved and a nano-level pattern is easily formed.
The organic compound having a molecular weight of 500 or more is roughly classified into a low molecular weight organic compound having a molecular weight of 500 or more and 2000 or less (hereinafter referred to as a low molecular compound) and a high molecular weight resin having a molecular weight of 2000 or more (polymer). Is done. As the low molecular weight compound, a non-polymer is usually used. In the case of a resin (polymer), a polystyrene-reduced weight average molecular weight by GPC (gel permeation chromatography) is used as the “molecular weight”. Hereinafter, the term “resin” simply means a resin having a molecular weight of more than 2000.
The component (A) may be a low molecular compound whose alkali solubility is increased by the action of an acid, a resin whose alkali solubility is increased by the action of an acid, or a mixture thereof. Good.

The component (A) preferably has a hydrophilic group in addition to the acid dissociable, dissolution inhibiting group. By having a hydrophilic group, the hydrophilicity of the entire component (A) is increased, the affinity with the developer is increased, the alkali solubility in the exposed area is improved, and the resolution is improved.
The hydrophilic group is selected from the group consisting of a hydroxyl group, a carboxy group, a carbonyl group (—C (O) —), an ester group (ester bond; —C (O) —O—), an amino group, and an amide group. One or more of these are preferred. Among these, a hydroxyl group (particularly an alcoholic hydroxyl group or a phenolic hydroxyl group), a carboxy group, and an ester group are more preferable. Among these, a carboxy group, an alcoholic hydroxyl group, and a phenolic hydroxyl group are preferable because they can form a pattern with small line edge roughness (unevenness on the pattern side wall) at the nano level. The hydrophilic group may also serve as an acid dissociable, dissolution inhibiting group.

As the (A) component of the positive resist composition of the present invention, the following (A-1) component and / or (A-2) component are preferable.
-(A-1) component: Resin which has a structural unit which has an acid dissociable, dissolution inhibiting group.
Component (A-2): a low molecular compound having an acid dissociable, dissolution inhibiting group.
Hereinafter, preferred embodiments of the component (A-1) and the component (A-2) will be described more specifically.

[(A-1) component]
The component (A-1) is a resin having a structural unit having an acid dissociable, dissolution inhibiting group.
The proportion of the structural unit having the acid dissociable, dissolution inhibiting group in the component (A-1) is 20 to 80 mol% with respect to the total amount of all the structural units constituting the component (A-1). It is preferably 20 to 70 mol%, more preferably 30 to 60 mol%.

The component (A-1) preferably further has a structural unit having a hydrophilic group in addition to the structural unit having the acid dissociable, dissolution inhibiting group.
Preferably, the structural unit having a hydrophilic group is a structural unit having a carboxy group, an alcoholic hydroxyl group or a phenolic hydroxyl group, more preferably an acrylic acid, methacrylic acid or an alcoholic hydroxyl group (α-lower alkyl). A unit derived from an acrylate ester and hydroxystyrene.
It is preferable that the ratio of the structural unit which has the said hydrophilic group in a (A-1) component is 20-80 mol% with respect to the total amount of all the structural units which comprise the said (A-1) component. 20-70 mol% is more preferable, and 20-60 mol% is further more preferable.

More specifically, as the component (A-1), a novolak resin having an acid dissociable, dissolution inhibiting group, a hydroxystyrene resin, a (α-lower alkyl) acrylic acid ester resin, a structural unit derived from hydroxystyrene; A copolymer resin containing a structural unit derived from an (α-lower alkyl) acrylate ester is preferably used.
In this specification, “(α-lower alkyl) acrylic acid” refers to one or both of acrylic acid (CH ₂ ═CH—COOH) and α-lower alkylacrylic acid. α-Lower alkyl acrylic acid refers to one in which a hydrogen atom bonded to a carbon atom to which a carbonyl group in acrylic acid is bonded is substituted with a lower alkyl group. “(Α-Lower alkyl) acrylic acid ester” is an ester derivative of “(α-lower alkyl) acrylic acid” and represents one or both of acrylic acid ester and α-lower alkyl acrylic acid ester.
The “structural unit derived from (α-lower alkyl) acrylic acid ester” is a structural unit formed by cleavage of an ethylenic double bond of (α-lower alkyl) acrylic acid ester. -Lower alkyl) acrylate structural unit. “(Α-lower alkyl) acrylate” refers to one or both of acrylate and α-lower alkyl acrylate.
The “structural unit derived from hydroxystyrene” is a structural unit formed by cleaving an ethylenic double bond of hydroxystyrene or α-lower alkylhydroxystyrene, and may hereinafter be referred to as a hydroxystyrene unit. “Α-lower alkylhydroxystyrene” indicates that the lower alkyl group is bonded to the carbon atom to which the phenyl group is bonded.
In the “structural unit derived from an α-lower alkyl acrylate ester” and the “structural unit derived from an α-lower alkylhydroxystyrene”, the lower alkyl group bonded to the α-position has 1 to 5 carbon atoms. An alkyl group, preferably a linear or branched alkyl group, methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, pentyl group, isopentyl group, neopentyl group Etc. Industrially, a methyl group is preferable.

The resin component suitable as the component (A-1) is not particularly limited. For example, a unit having a phenolic hydroxyl group such as the following structural unit (a1), the following structural unit (a2) and the following structural unit A structural unit having at least one acid dissociable, dissolution inhibiting group selected from the group consisting of units (a3), and a resin component having an alkali-insoluble unit such as (a4) used as necessary (hereinafter referred to as “a”). (It may be called (A-11) component.).
In the component (A-11), cleavage occurs in the structural unit (a2) and / or the structural unit (a3) by the action of the acid generated from the acid generator upon exposure. In the resin which is insoluble to the resin, the alkali solubility is increased. As a result, a chemically amplified positive pattern can be formed by exposure and development.

..Structural unit (a1)
The structural unit (a1) is a unit having a phenolic hydroxyl group, and is preferably a unit derived from hydroxystyrene represented by the following general formula (I ′).

（式中、Ｒは水素原子または低級アルキル基を示す。）

(In the formula, R represents a hydrogen atom or a lower alkyl group.)

R is a hydrogen atom or a lower alkyl group. The lower alkyl group is as described above, and a hydrogen atom or a methyl group is particularly preferable. The description of R is the same below.
The bonding position of —OH to the benzene ring is not particularly limited, but the position 4 (para position) described in the formula is preferred.
The structural unit (a1) is contained in the component (A-11) in an amount of 40 to 80 mol%, preferably 50 to 75 mol%. By setting it as 40 mol% or more, the solubility with respect to an alkali developing solution can be improved, and the improvement effect of a pattern shape is also acquired. The balance with other structural units can be taken by setting it as 80 mol% or less.

..Structural unit (a2)
The structural unit (a2) is a structural unit having an acid dissociable, dissolution inhibiting group, and is represented by the following general formula (II ′).

（式中、Ｒは上記と同じであり、Ｘは酸解離性溶解抑制基を示す。）

(In the formula, R is the same as above, and X represents an acid dissociable, dissolution inhibiting group.)

The acid dissociable, dissolution inhibiting group X is an alkyl group having a tertiary carbon atom, and the tertiary carbon atom of the tertiary alkyl group is bonded to the ester group [—C (O) O—]. Examples thereof include acid-dissolving dissolution inhibiting groups, tetrahydropyranyl groups, and cyclic acetal groups such as tetrahydrofuranyl groups.
As such an acid dissociable, dissolution inhibiting group X, for example, those other than those described above can be arbitrarily used from among those used in a chemically amplified positive resist composition.

  As the structural unit (a2), for example, those represented by general formula (III ′) shown below are preferred.

In the formula, R is the same as described above, and R ¹¹ , R ¹² , and R ¹³ are each independently a lower alkyl group (which may be linear or branched. Preferably, it has 1 to 5 carbon atoms). is there. Or, among R ¹¹ , R ¹² and R ¹³ , R ¹¹ may be a lower alkyl group, and R ¹² and R ¹³ may be bonded to form a monocyclic or polycyclic aliphatic cyclic group. . The aliphatic cyclic group preferably has 5 to 12 carbon atoms.
Here, “aliphatic” means that the group or compound does not have aromaticity, and “aliphatic cyclic group” means a monocyclic group or polycyclic group having no aromaticity. Means group.
When R ¹¹ , R ¹² and R ¹³ do not have an aliphatic cyclic group, for example, it is preferable that R ¹¹ , R ¹² and R ¹³ are all methyl groups.
In the case where any of R ¹¹ , R ¹² and R ¹³ has an aliphatic cyclic group, when the aliphatic cyclic group is a monocyclic aliphatic cyclic group, as the structural unit (a2), for example, cyclopentyl And those having a cyclohexyl group are preferred.
When the aliphatic cyclic group is a polycyclic alicyclic group, preferred examples of the structural unit (a2) include those represented by the following general formula (IV ′).

［式中、Ｒは上記と同じであり、Ｒ^１４は低級アルキル基（直鎖、分岐鎖のいずれでもよい。好ましくは炭素数１〜５である。）である。］

[Wherein, R is the same as described above, and R ¹⁴ represents a lower alkyl group (which may be linear or branched, preferably has 1 to 5 carbon atoms). ]

  Moreover, what is represented by the following general formula (V ') as a thing which has an acid dissociable, dissolution inhibiting group containing a polycyclic aliphatic cyclic group is also preferable.

［式中、Ｒは上記と同じであり、Ｒ^１５、Ｒ^１６は、それぞれ独立に低級アルキル基（直鎖、分岐鎖のいずれでもよい。好ましくは炭素数は１〜５である。）である。］

[Wherein, R is the same as defined above, and R ¹⁵ and R ¹⁶ each independently represent a lower alkyl group (which may be either a straight chain or a branched chain, preferably has 1 to 5 carbon atoms). . ]

  The structural unit (a2) is preferably present in the component (A-11) in an amount of 5 to 50 mol%, preferably 10 to 40 mol%, more preferably 10 to 35 mol%.

..Structural unit (a3)
The structural unit (a3) is a structural unit having an acid dissociable, dissolution inhibiting group, and is represented by the following general formula (VI ′).

（式中、Ｒは上記と同じであり、Ｘ’は酸解離性溶解抑制基を示す。）

(In the formula, R is the same as above, and X ′ represents an acid dissociable, dissolution inhibiting group.)

The acid dissociable, dissolution inhibiting group X ′ is a tertiary alkyloxycarbonyl group such as tert-butyloxycarbonyl group or tert-amyloxycarbonyl group; tert-butyloxycarbonylmethyl group or tert-butyloxycarbonylethyl group. Tertiary alkyloxycarbonylalkyl groups such as these; tertiary alkyl groups such as tert-butyl and tert-amyl groups; cyclic acetal groups such as tetrahydropyranyl and tetrahydrofuranyl groups; ethoxyethyl groups and methoxypropyl groups And the like.
Of these, a tert-butyloxycarbonyl group, a tert-butyloxycarbonylmethyl group, a tert-butyl group, a tetrahydropyranyl group, and an ethoxyethyl group are preferable.
As the acid dissociable, dissolution inhibiting group X ′, those other than those described above can be arbitrarily used from among those used in, for example, a chemically amplified positive resist composition.
In the general formula (VI ′), the bonding position of the group (—OX ′) bonded to the benzene ring is not particularly limited, but the position 4 (para position) shown in the formula is preferable.

  The structural unit (a3) is in the range of 5 to 50 mol%, preferably 10 to 40 mol%, more preferably 10 to 35 mol% in the component (A-11).

..Structural unit (a4)
The structural unit (a4) is an alkali-insoluble unit and is represented by the following general formula (VII ′).

（式中、Ｒは上記と同じであり、Ｒ^４’は低級アルキル基を示し、ｎ’は０または１〜３の整数を示す。）

(In the formula, R is the same as above, R ^{4 ′} represents a lower alkyl group, and n ′ represents 0 or an integer of 1 to 3).

The lower alkyl group for R ^{4 ′} may be either a straight chain or a branched chain, and preferably has 1 to 5 carbon atoms.
n ′ represents 0 or an integer of 1 to 3, and is preferably 0.

  The structural unit (a4) is 1 to 40 mol%, preferably 5 to 25 mol%, in the component (A-11). By setting it to 1 mol% or more, the effect of improving the shape (particularly, improving film loss) is enhanced, and by setting it to 40 mol% or less, it is possible to balance with other structural units.

In the component (A-11), the structural unit (a1) and at least one selected from the group consisting of the structural unit (a2) and the structural unit (a3) are essential, and may optionally include (a4). Good. In addition, a copolymer having all these units may be used, or a mixture of polymers having one or more of these units may be used. Or these may be combined.
Moreover, although the component (A-11) can optionally contain components other than the structural units (a1) to (a4), the total proportion of the structural units (a1) to (a4) is 80 mol%. Above, preferably 90 mol% or more (100 mol% is most preferable).

In particular, “any one of the copolymers having the structural units (a1) and (a3), or a mixture of two or more of the copolymers”, or “the structural units (a1), (a2) and An embodiment in which any one of the copolymers having (a4) or a mixture of two or more of the copolymers is used or mixed is most preferable because an effect can be easily obtained. Moreover, it is preferable also from the point of heat resistance improvement.
In particular, a mixture of polyhydroxystyrene protected with a tertiary alkyloxycarbonyl group and polyhydroxystyrene protected with a 1-alkoxyalkyl group is preferred. When such mixing is performed, the mixing ratio (mass ratio) of each polymer (polyhydroxystyrene protected with a tertiary alkyloxycarbonyl group / 1-polyhydroxystyrene protected with 1-alkoxyalkyl group) is, for example, 1/9 to The ratio is 9/1, preferably 2/8 to 8/2, and more preferably 2/8 to 5/5.

In addition to the component (A-11), the resin component suitable as the component (A-1) is an (α-lower alkyl) acrylate resin, particularly in that a pattern with lower etching resistance can be formed. Is preferably a resin component ((α-lower alkyl) acrylate resin), more preferably a resin component comprising (α-lower alkyl) acrylate resin.
In the (α-lower alkyl) acrylate resin (hereinafter referred to as “component (A-12)”), a structural unit (a5) derived from an (α-lower alkyl) acrylate ester containing an acid dissociable, dissolution inhibiting group. ) Is preferred. The α-lower alkyl group is the same as described above.
The acid dissociable, dissolution inhibiting group of the structural unit (a5) has an alkali dissolution inhibiting property that renders the entire resin component before exposure to alkali insolubility, and simultaneously dissociates by the action of an acid generated from the (B) component after exposure, (A-12) A group that changes the entire component to alkali-soluble.

As the acid dissociable, dissolution inhibiting group, for example, a resin for resist compositions of ArF excimer laser can be appropriately selected and used from among many proposed ones. In general, a group that forms a cyclic or chain tertiary alkyl ester with a carboxy group of (α-lower alkyl) acrylic acid, or a cyclic or chain alkoxyalkyl group is widely known.
Here, the “group that forms a tertiary alkyl ester” is a group that forms an ester by substituting the hydrogen atom of the carboxy group of acrylic acid. That is, it shows a structure in which the tertiary carbon atom of a chain-like or cyclic tertiary alkyl group is bonded to the oxygen atom at the terminal of the carbonyloxy group [—C (O) —O—] of the acrylate ester. In this tertiary alkyl ester, when an acid acts, a bond is cut between an oxygen atom and a tertiary carbon atom.
The tertiary alkyl group is an alkyl group having a tertiary carbon atom.
Examples of the group that forms a chain-like tertiary alkyl ester include a tert-butyl group and a tert-amyl group.
Examples of the group that forms a cyclic tertiary alkyl ester include those exemplified in the “acid dissociable, dissolution inhibiting group containing an alicyclic group” described later.

The “cyclic or chain alkoxyalkyl group” forms an ester by substituting a hydrogen atom of a carboxy group. That is, a structure is formed in which the alkoxyalkyl group is bonded to the terminal oxygen atom of the carbonyloxy group [—C (O) —O—] of the acrylate ester. In such a structure, the bond between the oxygen atom and the alkoxyalkyl group is broken by the action of the acid.
Examples of such cyclic or chain alkoxyalkyl groups include 1-methoxymethyl group, 1-ethoxyethyl group, 1-isopropoxyethyl, 1-cyclohexyloxyethyl group, 2-adamantoxymethyl group, 1-methyladamant Examples thereof include a xymethyl group, a 4-oxo-2-adamantoxymethyl group, a 1-adamantoxyethyl group, and a 2-adamantoxyethyl group.

As the structural unit (a5), a structural unit containing an acid dissociable, dissolution inhibiting group containing a cyclic group, particularly an aliphatic cyclic group, is preferred.
Here, “aliphatic” and “aliphatic cyclic group” are as defined above.
The aliphatic cyclic group may be monocyclic or polycyclic, and can be appropriately selected and used from among many proposed, for example, ArF resists. From the viewpoint of etching resistance, a polycyclic alicyclic group is preferred. The alicyclic group is preferably a hydrocarbon group, and particularly preferably a saturated hydrocarbon group (alicyclic group).
Examples of the monocyclic alicyclic group include groups in which one hydrogen atom has been removed from a cycloalkane. Examples of the polycyclic alicyclic group include groups in which one hydrogen atom has been removed from bicycloalkane, tricycloalkane, tetracycloalkane and the like.
Specifically, examples of the monocyclic alicyclic group include a cyclopentyl group and a cyclohexyl group. Examples of the polycyclic alicyclic group include groups in which one hydrogen atom has been removed from a polycycloalkane such as adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane.
Among these, an adamantyl group obtained by removing one hydrogen atom from adamantane, a norbornyl group obtained by removing one hydrogen atom from norbornane, a tricyclodecanyl group obtained by removing one hydrogen atom from tricyclodecane, and tetracyclo A tetracyclododecanyl group obtained by removing one hydrogen atom from dodecane is preferred industrially.

More specifically, the structural unit (a5) is preferably at least one selected from the following general formulas (I ″) to (III ″).
In addition, a unit derived from an (α-lower alkyl) acrylic acid ester having a cyclic alkoxyalkyl group as described above, specifically a 2-adamantoxymethyl group, 1-methyladamant Aliphatic polycyclic alkyloxy lower alkyl (α which may have a substituent such as xymethyl group, 4-oxo-2-adamantoxymethyl group, 1-adamantoxyethyl group, 2-adamantoxyethyl group, etc. -Lower alkyl) It is preferably at least one selected from units derived from acrylic acid esters.

［式（Ｉ”）中、Ｒは上記と同じであり、Ｒ^１は低級アルキル基である。］

[In the formula (I ″), R is the same as above, and R ¹ is a lower alkyl group.]

［式（ＩＩ”）中、Ｒは上記と同じであり、Ｒ^２及びＲ^３はそれぞれ独立に低級アルキル基である。］

[In the formula (II ″), R is the same as defined above, and R ² and R ³ are each independently a lower alkyl group.]

［式（ＩＩＩ”）中、Ｒは上記と同じであり、Ｒ^４は第３級アルキル基である。］

[In the formula (III ″), R is the same as above, and R ⁴ is a tertiary alkyl group.]

In formulas (I ″) to (III ″), the hydrogen atom or lower alkyl group for R is the same as described above for the hydrogen atom or lower alkyl group bonded to the α-position of the acrylate ester.
The lower alkyl group for R ¹ is preferably a linear or branched alkyl group having 1 to 5 carbon atoms, and specifically includes a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, and an isobutyl group. , A pentyl group, an isopentyl group, a neopentyl group, and the like. Among these, a methyl group and an ethyl group are preferable because they are easily available industrially.
The lower alkyl group for R ² and R ³ is preferably each independently a linear or branched alkyl group having 1 to 5 carbon atoms. Of these, the case where R ² and R ³ are both methyl groups is industrially preferred. Specific examples include structural units derived from 2- (1-adamantyl) -2-propyl acrylate.

R ⁴ is a chain-like tertiary alkyl group or a cyclic tertiary alkyl group. Examples of the chain-like tertiary alkyl group include a tert-butyl group and a tert-amyl group, and the tert-butyl group is industrially preferable.
The cyclic tertiary alkyl group is the same as that exemplified in the aforementioned “acid dissociable, dissolution inhibiting group containing an aliphatic cyclic group”, and includes a 2-methyl-2-adamantyl group, 2-ethyl- A 2-adamantyl group, 2- (1-adamantyl) -2-propyl group, 1-ethylcyclohexyl group, 1-ethylcyclopentyl group, 1-methylcyclohexyl group, 1-methylcyclopentyl group and the like can be mentioned.
The group —COOR ⁴ may be bonded to the 3 or 4 position of the tetracyclododecanyl group shown in the formula, but the bonding position cannot be specified. Similarly, the carboxy group residue of the acrylate structural unit may be bonded to the position 8 or 9 shown in the formula.

The structural unit (a5) can be used alone or in combination of two or more.
In the component (A-12), the proportion of the structural unit (a5) is preferably 20 to 60 mol%, and preferably 30 to 50 mol based on the total of all the structural units constituting the component (A-12). % Is more preferable, and 35 to 45 mol% is most preferable. A pattern can be obtained by setting it to the lower limit value or more, and balancing with other structural units can be achieved by setting the upper limit value or less.

In addition to the structural unit (a5), the component (A-12) preferably further has a structural unit (a6) derived from an acrylate ester having a lactone ring. The structural unit (a6) is effective in increasing the adhesion of the resist film to the substrate and increasing the hydrophilicity with the developer.
In the structural unit (a6), a lower alkyl group or a hydrogen atom is bonded to the α-position carbon atom. The lower alkyl group bonded to the α-position carbon atom is the same as described for the structural unit (a5), and is preferably a methyl group.
As the structural unit (a6), a structural unit in which a monocyclic group consisting of a lactone ring or a polycyclic cyclic group having a lactone ring is bonded to the ester side chain portion of the acrylate ester can be mentioned. At this time, the lactone ring indicates one ring containing an —O—C (O) — structure, and this is counted as the first ring. Therefore, here, in the case of only a lactone ring, it is called a monocyclic group, and when it has another ring structure, it is called a polycyclic group regardless of the structure.
Examples of the structural unit (a6) include a monocyclic group obtained by removing one hydrogen atom from γ-butyrolactone and a polycyclic group obtained by removing one hydrogen atom from a lactone ring-containing bicycloalkane. It is done.
More specifically, the structural unit (a6) is preferably at least one selected from, for example, the following general formulas (IV ″) to (VII ″).

［式（ＩＶ”）中、Ｒは上記と同じであり、Ｒ^５、Ｒ^６は、それぞれ独立に、水素原子または低級アルキル基である。］

[In formula (IV ″), R is the same as defined above, and R ⁵ and R ⁶ each independently represents a hydrogen atom or a lower alkyl group.]

［式（Ｖ”）中、Ｒは上記と同じであり、ｍは０または１である。］

[In the formula (V ″), R is the same as above, and m is 0 or 1.]

［式（ＶＩ”）中、Ｒは上記と同じである。］

[In the formula (VI ″), R is as defined above.]

［式（ＶＩＩ”）中、Ｒは上記と同じである。］

[In the formula (VII ″), R is the same as above.]

In formula (IV ″), R ⁵ and R ⁶ each independently represents a hydrogen atom or a lower alkyl group, preferably a hydrogen atom. In R ⁵ and R ⁶ , the lower alkyl group is preferably A linear or branched alkyl group having 1 to 5 carbon atoms, such as methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, pentyl group, isopentyl group, neopentyl group, etc. Industrially, a methyl group is preferable.

Among the structural units represented by the general formulas (IV ″) to (VII ″), the structural unit represented by (IV ″) is inexpensive and industrially preferable, and among the structural units represented by (IV ″) R is a methyl group, R ⁵ and R ⁶ are hydrogen atoms, and the position of the ester bond between the methacrylic acid ester and γ-butyrolactone is α-methacryloyloxy-γ-butyrolactone, which is the α-position on the lactone ring. Most preferred.
The structural unit (a6) can be used alone or in combination of two or more.
In the component (A-12), the proportion of the structural unit (a6) is preferably 20 to 60 mol%, more preferably 20 to 50 mol%, based on the total of all the structural units constituting the component (A-12). Preferably, 30 to 45 mol% is most preferable. Lithographic characteristics are improved by setting the value to the lower limit value or more, and balance with other structural units can be achieved by setting the upper limit value or less.

The component (A-12) is derived from an acrylate ester containing a polar group-containing polycyclic group in addition to the structural unit (a5) or in addition to the structural units (a5) and (a6). It is preferable to have a structural unit (a7).
By the structural unit (a7), the hydrophilicity of the entire component (A-12) is increased, the affinity with the developer is increased, the alkali solubility in the exposed area is improved, and the resolution is improved.
In the structural unit (a7), a lower alkyl group or a hydrogen atom is bonded to the α-position carbon atom. The lower alkyl group bonded to the α-position carbon atom is the same as described for the structural unit (a5), and is preferably a methyl group.
Examples of the polar group include a hydroxyl group, a cyano group, a carboxy group, and an amino group, and a hydroxyl group is particularly preferable.
As the polycyclic group, among the aliphatic cyclic groups exemplified in the “acid dissociable, dissolution inhibiting group containing an aliphatic cyclic group” which is the aforementioned unit (a5), a polycyclic group is appropriately selected. Can be used.
The structural unit (a7) is preferably at least one selected from the following general formulas (VIII ″) to (IX ″).

［式（ＶＩＩＩ”）中、Ｒは上記と同じであり、ｎは１〜３の整数である。］

[In formula (VIII ″), R is the same as described above, and n is an integer of 1 to 3.]

R in the formula (VIII ″) is the same as R in the above formulas (I ″) to (III ″).
Among these, those in which n is 1 and the hydroxyl group is bonded to the 3-position of the adamantyl group are preferable.

［式（ＩＸ”）中、Ｒは上記と同じであり、ｋは１〜３の整数である。］

[In formula (IX ″), R is the same as described above, and k is an integer of 1 to 3.]

  Among these, those in which k is 1 are preferable. Moreover, it is preferable that the cyano group has couple | bonded with 5-position or 6-position of the norbornyl group.

The structural unit (a7) can be used alone or in combination of two or more.
In the component (A-12), the proportion of the structural unit (a7) is preferably 10 to 50 mol%, more preferably 15 to 40 mol%, based on the total of all structural units constituting the component (A-12). Preferably, 20 to 35 mol% is more preferable. Lithographic characteristics are improved by setting the value to the lower limit value or more, and balance with other structural units can be achieved by setting the upper limit value or less.

  In the component (A-12), the total of these structural units (a5) to (a7) is preferably 70 to 100 mol%, more preferably 80 to 100 mol%, based on the total of all the structural units. It is more preferable.

The component (A-12) may contain a structural unit (a8) other than the structural units (a5) to (a7).
The structural unit (a8) is not particularly limited as long as it is another structural unit that is not classified into the structural units (a5) to (a7).
For example, a structural unit containing a polycyclic aliphatic hydrocarbon group and derived from an (α-lower alkyl) acrylate is preferable. The polycyclic aliphatic hydrocarbon group is appropriately selected from, for example, polycyclic ones among the aliphatic cyclic groups exemplified in the aforementioned “acid dissociable, dissolution inhibiting group containing an aliphatic cyclic group”. Can be used. In particular, at least one selected from a tricyclodecanyl group, an adamantyl group, a tetracyclododecanyl group, a norbornyl group, and an isobornyl group is preferable in terms of industrial availability. The structural unit (a8) is most preferably an acid non-dissociable group.
Specific examples of the structural unit (a8) include those having the following structures (X ″) to (XII ″).

（式中、Ｒは上記と同じである。）

(In the formula, R is the same as above.)

（式中、Ｒは上記と同じである。）

(In the formula, R is the same as above.)

（式中、Ｒは上記と同じである。）

(In the formula, R is the same as above.)

  In the case of having the structural unit (a8), the proportion of the structural unit (a8) in the component (A-12) is 1 to 25 mol% based on the total of all the structural units constituting the component (A-12). Preferably, 5 to 20 mol% is more preferable.

  The component (A-12) is preferably a copolymer having at least the structural units (a5), (a6) and (a7). Examples of such a copolymer include a copolymer composed of the structural units (a5), (a6) and (a7), and a copolymer composed of the structural units (a5), (a6), (a7) and (a8). A polymer etc. can be illustrated.

The component (A-1) can be obtained by polymerizing the monomer related to the structural unit by a known method. For example, the monomer related to each structural unit can be obtained by polymerizing by a known radical polymerization using a radical polymerization initiator such as azobisisobutyronitrile (AIBN).
The component (A-1) is preferably 30000 or less, more preferably 20000 or less, and further preferably 12000 or less, in terms of mass average molecular weight (polystyrene-converted mass average molecular weight by gel permeation chromatography, hereinafter the same). preferable. The lower limit may be more than 2000, and is preferably 4000 or more, and more preferably 5000 or more, from the viewpoint of suppressing pattern collapse and improving resolution.

[(A-2) component]
As the component (A-2), a low molecular compound having a molecular weight of 500 or more and 2000 or less and having an acid dissociable, dissolution inhibiting group X or X ′ as exemplified in the description of the component (A-1) above. preferable. Specifically, those in which part or all of the hydrogen atoms of the hydroxyl group of the compound having a plurality of phenol skeletons are substituted with the acid dissociable, dissolution inhibiting group X or X ′ can be mentioned.
The component (A-2) contains, for example, part or all of the hydrogen atoms of the hydroxyl group of a low molecular weight phenol compound known as a sensitizer or heat resistance improver in non-chemically amplified g-line or i-line resists. Those substituted with the above-mentioned acid dissociable, dissolution inhibiting group are preferred, and any of these can be used arbitrarily.
Examples of such low molecular weight phenol compounds include the following.
Bis (4-hydroxyphenyl) methane, bis (2,3,4-trihydroxyphenyl) methane, 2- (4-hydroxyphenyl) -2- (4′-hydroxyphenyl) propane, 2- (2,3,3) 4-trihydroxyphenyl) -2- (2 ′, 3 ′, 4′-trihydroxyphenyl) propane, tris (4-hydroxyphenyl) methane, bis (4-hydroxy-3,5-dimethylphenyl) -2- Hydroxyphenylmethane, bis (4-hydroxy-2,5-dimethylphenyl) -2-hydroxyphenylmethane, bis (4-hydroxy-3,5-dimethylphenyl) -3,4-dihydroxyphenylmethane, bis (4- Hydroxy-2,5-dimethylphenyl) -3,4-dihydroxyphenylmethane, bis (4-hydroxy-3-methylphenol) Nyl) -3,4-dihydroxyphenylmethane, bis (3-cyclohexyl-4-hydroxy-6-methylphenyl) -4-hydroxyphenylmethane, bis (3-cyclohexyl-4-hydroxy-6-methylphenyl) -3 , 4-dihydroxyphenylmethane, 1- [1- (4-hydroxyphenyl) isopropyl] -4- [1,1-bis (4-hydroxyphenyl) ethyl] benzene, phenol, m-cresol, p-cresol or xylenol And 2,3,4 nuclei of formalin condensates of phenols and the like. Of course, it is not limited to these.
The acid dissociable, dissolution inhibiting group is not particularly limited, and examples thereof include those described above.

In the present invention, the component (A) may have light absorption or may not have light absorption. Since it is excellent in the effect of this invention, it is preferable that (A) component has a light absorptivity. That is, when the component (A) has light absorptivity, the amount of the component (C) to be blended to achieve a desired absorbance can be reduced. Therefore, it is possible to reduce risks that may occur due to the inclusion of the component (C), for example, generation of sublimates due to heating during film formation, deterioration of yield associated therewith, generation of precipitates when used as a solution, and the like.
For example, among the organic compounds mentioned above, those having a molecular structure that absorbs light having a wavelength of an exposure light source used in thermal lithography have light absorptivity.

  (A) A component may be used individually by 1 type and may use 2 or more types together.

<(B) component>
The component (B) is a component that generates an acid by the action of heat. Here, “generating an acid by the action of heat” means generating an acid by heating at 80 ° C. or more and 200 ° C. or less.
As the component (B), any conventionally known acid generator for chemically amplified resists can be appropriately selected and used. Examples of such acid generators include onium salt acid generators such as iodonium salts and sulfonium salts, oxime sulfonate acid generators, bisalkyl or bisarylsulfonyldiazomethanes, and poly (bissulfonyl) diazomethanes. There are various known diazomethane acid generators, nitrobenzyl sulfonate acid generators, imino sulfonate acid generators, disulfone acid generators, and the like.
These acid generators are generally known as photoacid generators (PAGs) that generate acid upon exposure, but may also be used as thermal acid generators (TAG) that generate acid by the action of heat. Function. Therefore, as the component (B), a PAG that has been conventionally used in photolithography can be used.

  Specific examples of the onium salt acid generator include diphenyliodonium trifluoromethanesulfonate, (4-methoxyphenyl) phenyliodonium trifluoromethanesulfonate, bis (p-tert-butylphenyl) iodonium trifluoromethanesulfonate, and triphenylsulfonium trifluoromethanesulfonate. (4-methoxyphenyl) diphenylsulfonium trifluoromethanesulfonate, (4-methylphenyl) diphenylsulfonium nonafluorobutanesulfonate, (p-tert-butylphenyl) diphenylsulfonium trifluoromethanesulfonate, diphenyliodonium nonafluorobutanesulfonate, bis (p -Tert-Butylphenyl) iodonium nonafluorobutans Honeto include triphenylsulfonium nonafluorobutanesulfonate. Of these, onium salts having a fluorinated alkyl sulfonate ion as an anion are preferable.

  Examples of oxime sulfonate compounds include α- (methylsulfonyloxyimino) -phenylacetonitrile, α- (methylsulfonyloxyimino) -p-methoxyphenylacetonitrile, α- (trifluoromethylsulfonyloxyimino) -phenylacetonitrile, α -(Trifluoromethylsulfonyloxyimino) -p-methoxyphenylacetonitrile, α- (ethylsulfonyloxyimino) -p-methoxyphenylacetonitrile, α- (propylsulfonyloxyimino) -p-methylphenylacetonitrile, α- (methyl Sulfonyloxyimino) -p-bromophenylacetonitrile and the like. Of these, α- (methylsulfonyloxyimino) -p-methoxyphenylacetonitrile is preferred.

  Specific examples of the diazomethane acid generator include bis (isopropylsulfonyl) diazomethane, bis (p-toluenesulfonyl) diazomethane, bis (1,1-dimethylethylsulfonyl) diazomethane, bis (cyclohexylsulfonyl) diazomethane, bis (2, 4-dimethylphenylsulfonyl) diazomethane and the like.

As the component (B), one type may be used alone, or two or more types may be used in combination.
In the positive resist composition of the present invention, the content of the component (B) is 1 to 20 parts by mass, preferably 2 to 10 parts by mass with respect to 100 parts by mass of the component (A). By setting it to be equal to or higher than the lower limit value of the above range, pattern formation is sufficiently performed.

<(C) component>
The component (C) is not particularly limited as long as it is an organic compound that absorbs light having a wavelength of an exposure light source used in thermal lithography, and is appropriately selected from commercially available dyes according to the wavelength of the exposure light source to be used. Can be used.
Whether or not the dye absorbs light having the wavelength of the exposure light source to be used may be determined by referring to a pamphlet or the like issued by the manufacturer, or by a conventional method using a spectrophotometer.
In general, as the chemically amplified resist, light having a wavelength of 250 nm or less, such as an excimer laser such as a KrF excimer laser or an ArF excimer laser, or a light source having a shorter wavelength is generally used. Such a chemically amplified resist is usually not sensitive to light having a wavelength of 365 nm or more, for example, a visible light laser. Therefore, as the component (C), a compound that absorbs light having a wavelength of 365 nm or more is preferable, and a dye that absorbs a visible light laser is more preferable. In particular, a dye that absorbs light having a wavelength of 350 to 800 nm is preferable, a dye that absorbs light having a wavelength of 350 to 550 nm is more preferable, and a dye that absorbs light having a wavelength of 350 to 450 nm is most preferable.
For example, as a compound that absorbs light having a wavelength of around 400 nm, compounds mainly used as yellow dyes can be mentioned, and specific examples include trade names: OY-105, OY-107, OY-129, OY. -3G, OY-GG-S (above, manufactured by Orient Chemical Co., Ltd.), Diaresin Yellow F, Diaresin A (above, manufactured by Mitsubishi Chemical Corporation), Soldan Yellow GRN (above, manufactured by Chugai Kasei Co., Ltd.), Sumilast Yellow GG, Sumiplast Yellow F5G, Sumiplast Yellow FG (manufactured by Sumitomo Chemical Co., Ltd.), CH-1002 (manufactured by Daitokemix Co., Ltd.), and the like.

(C) A component may be used individually by 1 type and may be used in mixture of 2 or more types.
(C) The compounding quantity of a component should just be the quantity from which the light absorbency of the resist film formed using the said positive resist composition will be 0.08 or more per 100 nm of film thickness in the wavelength of the said exposure light source, What is necessary is just to adjust suitably according to a desired light absorbency, the kind of (C) component to be used, whether the said (A) component absorbs the wavelength of an exposure light source, etc.
(C) The preferable compounding quantity of component is adding in the ratio of 1-80 mass% with respect to (A) component, More preferably, it is 3-75 mass%, Most preferably, it is 4-70 mass. %, And most preferably 5 to 65% by mass. If it is 1% by mass or more, the absorbance is improved. When it is 80% by mass or less, the coatability is improved.

<Optional component>
The positive resist composition of the present invention further contains, as an optional component, a nitrogen-containing organic compound (D) (hereinafter referred to as “component (D)”) in order to improve the resist pattern shape, the stability over time, and the like. It is preferable to do.
Since a wide variety of components (D) have already been proposed, any known one may be used, but amines, particularly secondary lower aliphatic amines and tertiary lower aliphatic amines are preferred. .
Here, the lower aliphatic amine refers to an alkyl or alkyl alcohol amine having 5 or less carbon atoms, and examples of the secondary or tertiary amine include trimethylamine, diethylamine, triethylamine, di-n-propylamine, Tri-n-propylamine, tripentylamine, diethanolamine, triethanolamine, triisopropanolamine and the like can be mentioned, and tertiary alkanolamines such as triethanolamine and triisopropanolamine are particularly preferable.
Any of these may be used alone or in combination of two or more.
In the positive resist composition of the present invention, the component (D) is usually used in the range of 0.01 to 5.0 parts by mass with respect to 100 parts by mass of the component (A).

In addition, the positive resist composition of the present invention includes an organic carboxylic acid as an optional component for the purpose of preventing deterioration of sensitivity due to the blending with the component (D) and improving the pattern shape and stability of placement. An acid or phosphorus oxo acid or a derivative thereof (E) (hereinafter referred to as component (E)) can be contained. In addition, (D) component and (E) component can also be used together, and any 1 type can also be used.
As the organic carboxylic acid, for example, malonic acid, citric acid, malic acid, succinic acid, benzoic acid, salicylic acid and the like are suitable.
Phosphorus oxoacids or derivatives thereof include phosphoric acid, phosphoric acid di-n-butyl ester, phosphoric acid diphenyl ester and other phosphoric acid or derivatives thereof such as phosphonic acid, phosphonic acid dimethyl ester, phosphonic acid- Like phosphonic acids such as di-n-butyl ester, phenylphosphonic acid, phosphonic acid diphenyl ester, phosphonic acid dibenzyl ester and their esters, phosphinic acids such as phosphinic acid, phenylphosphinic acid and their esters Among these, phosphonic acid is particularly preferable.
(E) A component is normally used in the ratio of 0.01-5.0 mass parts per 100 mass parts of (A) component.

  If desired, the positive resist composition of the present invention further contains miscible additives such as an additional resin for improving the performance of the coating film of the resist composition, and a surface activity for improving the coating property. An agent, a dissolution inhibitor, a plasticizer, a stabilizer, a colorant, an antihalation agent, and the like can be appropriately contained.

In the preferred embodiment of the positive resist composition of the present invention, that is, another preferred embodiment different from the positive resist composition containing the component (A), the component (B) and the component (C), an alkali is added by the action of an acid. A base material component (A ′) (hereinafter referred to as (A ′) component) that has increased solubility and absorbs light having a wavelength of an exposure light source used in thermal lithography, and the component (B) are essential. A positive resist composition contained as a component may be mentioned.
The positive resist composition of this embodiment may not contain the component (C). That is, since the component (A ′) has a light absorption capability of absorbing light having the wavelength of the exposure light source, and also has a function as the component (C), the component (C) is the same as the component (C). Even if it does not contain, the effect of this invention is acquired. Since it does not need to contain the component (C), it contains the component (C) such as generation of sublimation by heating at the time of film formation, deterioration of the yield accompanying it, generation of precipitates when it is used as a solution, etc. The risk that may be caused by this can be reduced.
Examples of the component (A ′) include those having a molecular structure that absorbs light having a wavelength of an exposure light source used in thermal lithography among the organic compounds listed as the component (A).
The positive resist composition of this embodiment may contain components other than the component (A ′) and the component (B). Examples of the other components include the above-described component (A), component (B), component (C), and other optional components. In particular, when the component (C) is used in combination, a desired absorbance can be achieved even when a component having a relatively low light absorption ability is used as the component (A ′).

The positive resist composition of the present invention can be produced by dissolving the above components in an organic solvent (S) (hereinafter referred to as (S) component).
As the component (S), any component can be used as long as it can dissolve each component to be used to obtain a uniform solution. Conventionally, any one or two of known solvents for resist compositions can be used. More than one species can be appropriately selected and used.
Specific examples include lactones such as γ-butyrolactone, ketones such as acetone, methyl ethyl ketone, cyclohexanone, methyl isoamyl ketone, 2-heptanone, ethylene glycol, ethylene glycol monoacetate, diethylene glycol, diethylene glycol monoacetate, propylene glycol, propylene glycol. Polyhydric alcohols such as monoacetate, propylene glycol monomethyl ether acetate (PGMEA), dipropylene glycol, or monomethyl ether, monoethyl ether, monopropyl ether, monobutyl ether or monophenyl ether of dipropylene glycol monoacetate and derivatives thereof; , Cyclic ethers such as dioxane, methyl lactate, ethyl lactate (EL), vinegar It is methyl, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methyl methoxypropionate, and the like esters such as ethyl ethoxypropionate. Among these, 2-heptanone, PGMEA, EL, and propylene glycol monomethyl ether (PGME) are preferable. These organic solvents may be used independently and may be used as 2 or more types of mixed solvents.
These organic solvents may be used independently and may be used as 2 or more types of mixed solvents.
The amount of component (S) used is not particularly limited, but an amount is used in which the positive resist composition of the present invention becomes a liquid having a concentration that can be applied onto a support.

The positive resist composition of the present invention is an amount (predetermined amount) that the absorbance of the resist film to be formed is 0.08 or more per 100 nm of film thickness with respect to a commercially available chemically amplified positive resist composition. The component (C) can be added and dissolved.
Usually, as described above, a commercially available chemically amplified positive resist composition contains the component (A) and a photoacid generator component that generates an acid upon exposure, and the photoacid generator The component is the same as the component (B). Therefore, the positive resist composition of the present invention can be produced by adding the predetermined amount of the component (C) to a commercially available chemically amplified positive resist composition.

  As described above, the resist film formed using the chemically amplified positive resist composition for thermal lithography of the present invention has an absorbance of 0.08 or more per 100 nm thickness at the wavelength of the exposure light source used in thermal lithography. Have Therefore, in thermal lithography, when the resist film absorbs light irradiated from the exposure light source, heat at a temperature sufficient to generate an acid from the acid generator component in the resist film is generated. Therefore, a resist pattern can be formed on the resist film by thermal lithography.

≪Resist pattern formation method≫
In the resist pattern forming method of the present invention, a step of forming a resist film on a support using the chemically amplified positive resist composition for thermal lithography of the present invention (hereinafter referred to as a resist film forming step), the above. A step of selectively exposing the resist film using light having a wavelength at which the absorbance per 100 nm of the thickness of the resist film is 0.08 or more (hereinafter referred to as an exposure step), and developing the resist film A step of forming a resist pattern (hereinafter referred to as a development step).
The resist pattern forming method of the present invention can be performed, for example, as follows.

(Resist film formation process)
In this step, first, the positive resist composition for thermal lithography of the present invention is applied onto a support with a spinner or the like, and pre-baked (post-apply bake (PAB)) at a temperature of 80 to 150 ° C. A resist laminate is obtained by forming a resist film by applying for 40 to 120 seconds, preferably 60 to 90 seconds.
The support is not particularly limited, and a conventionally known one can be used, and examples thereof include a substrate for electronic components and a substrate on which a predetermined wiring pattern is formed. More specifically, a silicon substrate, a metal substrate such as copper, chromium, iron, and aluminum, a glass (quartz glass, etc.) substrate, and the like can be given. As a material for the wiring pattern, for example, copper, aluminum, nickel, gold or the like can be used. Further, an inorganic and / or organic antireflection film may be provided on the substrate.
The thickness of the resist film is preferably 30 to 1000 nm, more preferably 50 to 600 nm, and still more preferably 50 to 450 nm. By setting it within this range, there are effects that a resist pattern can be formed with high resolution and sufficient resistance to etching can be obtained.

(Exposure process)
Next, selective exposure is performed to the obtained resist laminated body using the light of the wavelength whose light absorbency per 100 nm of film thickness of the said resist film is 0.08 or more as an exposure light source.
As an exposure light source, light having a wavelength of 350 nm or more is preferable, visible light laser is more preferable, and light having a wavelength of 350 to 450 nm is particularly preferable. Components (for example, the components (A) and (B) described above) contained in a normal chemical amplification type positive resist composition are light having a wavelength of 250 nm or less, such as KrF excimer laser, ArF excimer laser, etc. Excimer lasers and lasers that absorb little or no light at shorter wavelengths are generally used. Therefore, by using light having a wavelength of 350 nm or more, the influence of the light on the resist film can be reduced, and thermal lithography can be performed satisfactorily.
For selective exposure, a commercially available exposure apparatus can be appropriately selected and used according to the light source to be used. For example, when a visible light laser is used, a nano processing apparatus NEO-500 (semiconductor laser having a wavelength of 405 nm) manufactured by Pulstec can be used. This apparatus is an apparatus that performs drawing by irradiating an object (resist laminate) with semiconductor laser light condensed by a lens.

In this step, when light is irradiated on the surface (resist film side) of the resist laminate, the light is absorbed by the resist film. And the part (light absorption part) which absorbed light of the resist film generate | occur | produced heat, an acid generate | occur | produces from the (B) component which exists in a light absorption part by this heat, and the action of this acid WHEREIN: (A) component Alkali solubility increases. Therefore, when alkali development is performed in the subsequent development step, the resist film in the portion where the acid is generated is removed, and the resist film in other portions is left without being removed to form a resist pattern.
When the light is irradiated, the heat distribution of the heat generated in the light absorption part is the same as the intensity distribution of the absorbed light. For example, in the case of a light spot, the closer to the center, the higher the light intensity. The heat that goes up becomes higher in the center. Since the reaction of thermal lithography occurs when the temperature of the heated resist film becomes equal to or higher than a predetermined temperature (heat sensitive temperature), a high temperature portion (heat spot) higher than the heat sensitive temperature at the center of the light spot is formed by thermal lithography. Contributes to the reaction. Since the diameter of the heat spot is smaller than the spot diameter of the light, drawing can be performed with a diameter smaller than the spot diameter of the irradiated light, and as a result, a fine pattern can be formed.
In addition, although the said thermosensitive temperature changes with the kind etc. of (A) component and (B) component to be used, it is in the range of 140-300 degreeC normally.

  After selective exposure, it is preferable to apply PEB (post-exposure heating) to the resist laminate at a temperature of 80 to 150 ° C. for 40 to 120 seconds, preferably 60 to 90 seconds.

(Development process)
Subsequently, this is developed using an alkali developer, for example, 0.05 to 10% by mass, preferably 0.05 to 3% by mass of an aqueous tetramethylammonium hydroxide (TMAH) solution. Thereby, the exposed portion of the resist film is selectively dissolved and removed to form a resist pattern.

Etching treatment for etching the support may be further performed on the resist laminated body on which the resist pattern is formed as described above, using the formed resist pattern as a mask pattern.
For example, when using a support provided with an organic film (lower layer film) on a substrate, the resist pattern of the resist film is transferred to the organic film by etching the organic film, High aspect ratio patterns can be formed.
Etching of the organic film can be performed using a conventionally known etching method, and dry etching is particularly preferable, and etching using oxygen plasma is particularly preferable.

[Example 1]
(Preparation of positive resist composition 1)
First, a positive resist composition 1 was prepared by mixing and dissolving the following components.
Component (A): Resin 1 (11.97 parts by mass) and Resin 2 (5.13 parts by mass).
-(B) component: Acid generator 1 (0.56 mass part).
-(D) component: Triethanolamine (0.009 mass part).
-(E) component: Salicylic acid (0.019 mass part).
Additive: Dimethylacetamide (0.463 parts by mass).
Organic solvent: PGMEA (81.8 parts by mass).
Organic solvent: 2-heptanone (630 parts by mass).
-Yellow dye OY-108 (made by Orient Chemical) (1.0 mass part).

In the above composition, the resin 1 is a resin having a mass average molecular weight of 8000 composed of two types of structural units represented by the following formula (1), and m ₁ and n ₁ in the formula (1) are respectively in the resin. The ratio of each structural unit (unit: mol%) is m ₁ / n ₁ = 61/39.
Resin 2 is a resin having a mass average molecular weight of 8000 composed of two types of structural units represented by the following formula (2), and m ₂ and n _{2 in} formula (2) are the respective structural units in the resin. Ratio (unit: mol%), and m ₂ / n ₂ = 61/39.
Moreover, the acid generator 1 is a compound represented by following formula (3).

(Measurement of absorbance)
Using a spin coater (manufactured by MIKASA), the positive resist composition 1 prepared above is applied onto a 2-inch quartz substrate and baked at 230 ° C. for 15 minutes to form a resist film having a thickness of 100 nm. Thus, a sample for measurement was produced.
About this sample, the light absorbency of the said resist film was measured on the following measurement conditions using "Shimadzu self-recording spectrophotometer UV-3100PC" by Shimadzu Corporation.
[Measurement condition]
Measurement wavelength range: 600 nm to 200 nm.
Absorbance measurement range: 0-2.5abs.
Scan speed: fast.
Slit width: 2.0 nm.
Sampling pitch: AUTO.
Baseline: Air [device-side reference for background correction], new quartz substrate [sample-side reference for background correction].

  From the absorbance of the resist film at a wavelength of 405 nm obtained by the above measurement and the thickness of the resist film, the absorbance per 100 nm of the film thickness at a wavelength of 405 nm was calculated. As a result, the absorbance at a wavelength of 405 nm of the resist film formed using the positive resist composition 1 was 0.08 / 100 nm in film thickness.

(Confirmation of pattern formation)
Using a spin coater (manufactured by MIKASA), the positive resist composition 1 prepared above is applied onto a glass substrate that has been treated with hexamethyldisilazane (HDMS) (70 ° C., 7 minutes), and then on a hot plate Then, a resist film (film thickness 100 nm) was formed by heating at 110 ° C. for 90 seconds. Next, in the nano-processing apparatus NEO-500 (manufactured by Pulstec Industrial Co., Ltd.), the resist film was irradiated with blue laser light (semiconductor laser wavelength of 405 nm) at an output of 10 mW. The substrate was heated at 110 ° C. for 90 seconds, immersed in a 0.24 mass% tetramethylammonium hydroxide aqueous solution for 60 seconds, further washed with pure water, and then heated on a hot plate at 100 ° C. for 60 seconds. Thereafter, the surface of the substrate was observed using a scanning electron microscope (SEM). As a result, a resist pattern in which holes having an inner diameter of 900 nm were arranged at equal intervals (pitch 1200 nm) and holes having an inner diameter of 330 nm were equally spaced (pitch 600 nm). It was confirmed that the resist pattern arranged in (1) was formed.

[Example 2]
In Example 1, it replaced with 1.0 mass part of yellow dye OY-108 (made by Orient Chemical Co., Ltd.), and it was the same as that of Example 1 except having used 11.0 mass part of yellow dye CH-1002 (made by Daito Chemix). Thus, a positive resist composition 2 was prepared.
When the absorbance was measured using the positive resist composition 2 in the same manner as in Example 1, the absorbance at a wavelength of 405 nm of the resist film formed using the positive resist composition 2 was 0.32 / The film thickness was 100 nm.
Further, pattern formation was confirmed using the positive resist composition 2 in the same manner as in Example 1. As a result, a resist pattern in which holes with an inner diameter of 900 nm were arranged at equal intervals (pitch 1200 nm), and holes with an inner diameter of 330 nm were used. Can be confirmed to be formed at a regular interval (pitch 600 nm).

[Comparative Example 1]
In Example 1, it replaced with 1.0 mass part of yellow dye OY-108 (made by Orient Chemical Co., Ltd.), and Example was used except that 0.55 mass part of yellow dye OY-GG-S (made by Orient Chemical Co., Ltd.) was used. In the same manner as in Example 1, a positive resist composition 3 was prepared.
When the absorbance was measured using the positive resist composition 3 in the same manner as in Example 1, the absorbance at a wavelength of 405 nm of the resist film formed using the positive resist composition 3 was 0.07 / The film thickness was 100 nm.
Moreover, when the pattern formation was confirmed using the positive resist composition 3 in the same manner as in Example 1, the resist pattern was not resolved.

[Comparative Example 2]
In Example 1, it replaced with 1.0 mass part of yellow dye OY-108 (made by Orient Chemical Co., Ltd.), and changed into 0.90 mass part of yellow dye OY-105 (made by Orient Chemical Co., Ltd.) and Example 1 Similarly, a positive resist composition 4 was prepared.
When the absorbance was measured using the positive resist composition 4 in the same manner as in Example 1, the absorbance at a wavelength of 405 nm of the resist film formed using the positive resist composition 4 was 0.07 / The film thickness was 100 nm.
Moreover, when the pattern formation was confirmed using the positive resist composition 4 in the same manner as in Example 1, the resist pattern was not resolved.

[Comparative Example 3]
In Example 1, it replaced with 1.0 mass part of yellow dye OY-108 (made by Orient Chemical Co., Ltd.), and Example 1 except having used 1.25 mass part of yellow dye OY-129 (made by Orient Chemical Co., Ltd.). Similarly, a positive resist composition 5 was prepared.
When the absorbance was measured using the positive resist composition 5 in the same manner as in Example 1, the absorbance at a wavelength of 405 nm of the resist film formed using the positive resist composition 5 was 0.06 / The film thickness was 100 nm.
Further, when the pattern formation was confirmed using the positive resist composition 5 in the same manner as in Example 1, the resist pattern was not resolved.

[Comparative Example 4]
In Example 1, a positive resist composition 6 was prepared in the same manner as in Example 1 except that the yellow dye OY-108 was not added.
When the absorbance was measured using the positive resist composition 6 in the same manner as in Example 1, the absorbance at a wavelength of 405 nm of the resist film formed using the positive resist composition 6 was 0.06 / The film thickness was 100 nm.
Moreover, when the pattern formation was confirmed using the positive resist composition 6 as in Example 1, the resist pattern was not resolved.

As shown in the above results, in Examples 1 and 2 in which the absorbance of the resist film to be formed at the wavelength of the exposure light source (405 nm) was 0.08 / 100 nm or more, a resist pattern could be formed.
On the other hand, resist patterns could not be formed in Comparative Examples 1 to 3 in which the absorbance of the formed resist film at the wavelength of the exposure light source (405 nm) was 0.07 / 100 nm or less.
From these results, it is clear that the formation of the resist pattern in Examples 1 and 2 is due to the fact that the blue laser light directly acts on the resist film, that is, not by photolithography but by thermal lithography. .

Claims (3)

A chemically amplified positive resist composition for thermal lithography for forming a resist film used in thermal lithography,
The resist film formed using the chemical amplification type positive resist composition for thermal lithography has an absorbance of 0.08 or more per 100 nm thickness at the wavelength of the exposure light source used in the thermal lithography. A chemically amplified positive resist composition for thermal lithography.   A base component (A) whose alkali solubility is increased by the action of an acid, an acid generator component (B) which generates an acid by the action of heat, and a dye (C) which absorbs light of the wavelength of the exposure light source; The chemically amplified positive resist composition for thermal lithography according to claim 1, comprising:   A step of forming a resist film on the support using the chemically amplified positive resist composition for thermal lithography according to claim 1 or 2, the absorbance per 100 nm of the thickness of the resist film with respect to the resist film A resist pattern forming method including a step of performing selective exposure using light having a wavelength of 0.08 or more and a step of developing the resist film to form a resist pattern.