JP2005258174A - Positive photoresist composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a positive photoresist composition capable of forming both a high density pattern and an isolated pattern with good profiles even when an ultrafine resist pattern is formed. <P>SOLUTION: The positive photoresist composition contains (A) an alkali-soluble novolac resin including an m-cresol unit represented by formula (I) and/or formula (II), a 3,4-xylenol unit represented by formula (III), and a 2,5-xylenol unit represented by formula (IV), and (B) a naphthoquinonediazido ester compound of a specified phenol compound. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a positive photoresist composition.

As a positive photoresist composition for i-line (365 nm) lithography, a composition containing an alkali-soluble novolak resin and a 1,2-naphthoquinonediazide group-containing compound is a material excellent in sensitivity, resolution, and heat resistance. It is widely used in various fields such as the field of semiconductor integrated circuit (IC) creation.
In recent years, with the progress of semiconductor technology, higher integration of ICs has progressed, and the production of logic ICs, which are high value-added ICs, has become active.
Since a logic IC has a circuit in which a dense pattern and an isolated pattern are mixedly mixed, an ultrafine resist pattern of 0.35 μm or less is formed as a dense pattern or an isolated pattern in order to form the complicated and fine circuit. A photoresist material that can be formed in good shape is desired.

However, the positive photoresist composition has a strong tendency to reduce the resist pattern, and it is difficult to form an ultrafine resist pattern of 0.35 μm or less in a good shape.
In the isolated pattern, the pattern is thinned and the pattern collapses easily, and in the dense pattern, there is a problem that the separation pattern cannot be formed or the film is significantly reduced.
As described above, in the region of 0.35 μm or less, the depth of focus characteristics are remarkably deteriorated, and it is difficult to form a practical resist pattern. Therefore, an ultrafine resist pattern of 0.35 μm or less is formed. Even in this case, there is a demand for a material that can form a dense pattern and an isolated pattern in good shape and has excellent depth of focus characteristics.

The alkali-soluble novolak resin used in the positive photoresist composition is generally synthesized from two or more phenols as raw materials. Among them, m-cresol and p-cresol are used as essential components. The novolak resin synthesized in this way is widely used because of its excellent balance between sensitivity and resolution.
However, p-cresol is a monomer with poor reactivity, and most of the p-cresol used in the preparation is present in the resin after synthesis as unreacted products or low-nucleated products such as dimers and trimers. There is a problem of deteriorating resist characteristics such as causing scum at the time of pattern formation.
From the above, there is no problem of deteriorating resist characteristics such as causing scum at the time of resist pattern formation. Even when forming an ultrafine resist pattern of 0.35 μm or less, both dense and isolated patterns have good shape. Realization of a resist material suitable for the field of manufacturing logic ICs that can be formed and has excellent depth of focus characteristics is desired.

（式中、Ｒ^２１は低級アルキル基を、Ｒ^２２は水素原子または低級アルキル基を、各々あらわす）
で示されるフェノール類のフェノール類混合物並びにアルデヒド類を縮合反応させて得られるノボラック樹脂、及び感光性成分としてフラバン骨格を有するフェノール化合物のナフトキノンジアジドエステル化物を含有してなるポジ型ホトレジスト組成物が記載されている。 Therefore, in the following Patent Document 1, m-cresol, 3,4-xylenol, and the following general formula (VII)

(Wherein R ²¹ represents a lower alkyl group, and R ²² represents a hydrogen atom or a lower alkyl group)
And a novolak resin obtained by condensation reaction of aldehydes with a phenol mixture of phenols and a positive photoresist composition comprising a naphthoquinonediazide esterified product of a phenol compound having a flavan skeleton as a photosensitive component. Has been.

Patent Document 2 listed below includes a novolak resin synthesized using mixed phenols composed of m-cresol 40 to 90 mol%, p-cresol 2 to 4 mol%, and xylenol 10 to 60 mol%, and a photosensitive component. A positive photoresist composition comprising a naphthoquinonediazide esterified product of a polyhydroxy compound having 3 to 7 phenolic hydroxyl groups in the molecule is described.
Japanese Unexamined Patent Publication No.7-191461 Japanese Patent Laid-Open No. 8-184963

 However, the photoresist composition described in Patent Document 1 is a material with less scum generation and can cope with the formation of a dense pattern (so-called line and space pattern (L & S pattern)) of about 0.5 μm, but 0.35 μm. In the field where it is desired to form the following ultrafine resist patterns with good shape in both dense patterns and isolated patterns, there are difficulties in resolution and depth of focus (DOF) characteristics, and their application is difficult.

 In addition, the photoresist composition described in Patent Document 2 has a problem of scum generation and can cope with the formation of an L & S pattern of about 0.4 μm, but an ultrafine resist pattern of 0.35 μm or less is a dense pattern, isolated pattern In the field where it is desired to form both patterns in good shape, there are difficulties in resolution and depth of focus (DOF) characteristics, and their application is difficult.

  Therefore, the object of the present invention is to form a dense pattern and an isolated pattern in a good shape even when an ultrafine resist pattern of 0.35 μm or less is formed, and is excellent in sensitivity, resolution, and depth of focus characteristics. In particular, it is an object of the present invention to provide a positive photoresist composition suitable for the field of manufacturing logic ICs.

および／または下記化学式（ＩＩ）

で表されるｍ−クレゾール単位、下記一般式（ＩＩＩ）

で表される３，４−キシレノール単位、および下記一般式（ＩＶ）

で表される２，５−キシレノール単位を含有してなるアルカリ可溶性ノボラック樹脂、および（Ｂ）下記一般式（Ｖ）

〔式中、Ｒ^１〜Ｒ^８はそれぞれ独立に水素原子、ハロゲン原子、炭素原子数１〜６のアルキル基、炭素原子数１〜６のアルコキシ基、または炭素原子数３〜６のシクロアルキル基を表し；Ｒ^９〜Ｒ^１１はそれぞれ独立に水素原子または炭素原子数１〜６のアルキル基を表し；Ｑは水素原子、炭素原子数１〜６のアルキル基、または下記の化学式（ＶＩ）で表される残基、

（式中、Ｒ^１２およびＲ^１３はそれぞれ独立に水素原子、ハロゲン原子、炭素原子数１〜６のアルキル基、炭素原子数１〜６のアルコキシ基、または炭素原子数３〜６のシクロアルキル基を表し；ｃは１〜３の整数を示す）であり、ＱがＲ^９の末端と結合する場合は、Ｑ、Ｒ^９、及びＱとＲ^９との間の炭素原子とともに、炭素原子鎖３〜６のシクロアルキル基を表し；ａ、ｂは１〜３の整数を表し；ｄは０〜３の整数を表し；ｎは０〜３の整数を表す〕
で表されるフェノール化合物のナフトキノンジアジドエステル化物を含有してなることを特徴とする。 In order to achieve the above object, the positive photoresist composition of the present invention comprises (A) the following general formula (I),

And / or the following chemical formula (II)

M-cresol unit represented by the following general formula (III)

3,4-xylenol unit represented by the following general formula (IV)

An alkali-soluble novolak resin containing a 2,5-xylenol unit represented by formula (B):

[Wherein R ^{1 to} R ⁸ are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a cycloalkyl group having 3 to 6 carbon atoms. R ^{9 to} R ¹¹ each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms; Q is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or the following chemical formula (VI) The residue represented,

Wherein R ¹² and R ¹³ are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a cycloalkyl group having 3 to 6 carbon atoms. C represents an integer of 1 to 3), and when Q is bonded to the end of R ⁹ , together with Q, R ⁹ , and the carbon atom between Q and R ⁹ , carbon atom chain 3 Represents a cycloalkyl group of -6; a and b represent an integer of 1 to 3; d represents an integer of 0 to 3; and n represents an integer of 0 to 3]
It contains the naphthoquinone diazide esterified product of the phenol compound represented by these.

In the claims and specification, “unit” refers to a monomer unit constituting a polymer (resin).
In the present specification, the mass average molecular weight (Mw) and the content of the low-nuclear substance described later are measured on a chromatogram at a detection wavelength of 280 nm by gel permeation chromatography (hereinafter sometimes abbreviated as GPC). Is the existence ratio. Specifically, values measured using the following GPC system are used.
Device name: SYSTEM 11 (product name, Showa Denko)
Precolumn: KF-G (product name, manufactured by Shodex)
Column: KF-802 (product name, manufactured by Shodex)
Detector: UV41 (product name, manufactured by Shodex), measured at 280 nm.
Solvent etc .: Tetrahydrofuran was allowed to flow at a flow rate of 1.0 ml / min and measured at 35 ° C.
Further, in the claims and the specification, the low nucleus in phenol is a condensate molecule having several (for example, about 2 to 5) phenol nuclei.

  In the present invention, even when an ultrafine resist pattern of 0.35 μm or less is formed, both a dense pattern and an isolated pattern can be formed in good shape, and excellent in sensitivity, resolution, and depth of focus characteristics. A positive photoresist composition suitable for the IC manufacturing field can be provided.

(A) Alkali-soluble novolak resin The component (A) is an m-cresol unit represented by the above general formula (I) and / or the above chemical formula (II), or 3,4- represented by the above general formula (III). An alkali-soluble novolak resin containing a xylenol unit and a 2,5-xylenol unit represented by the following general formula (IV).
By using such a specific alkali-soluble novolak resin in combination with the component (B), the positive photoresist composition of the present invention can form an ultrafine resist pattern of 0.35 μm or less. In addition, both dense patterns and isolated patterns can be formed with good shape, and excellent sensitivity, resolution, and depth of focus characteristics, particularly suitable for the field of manufacturing logic ICs can be obtained.

-M-cresol unit The m-cresol unit is represented by the general formula (I) and / or the chemical formula (II).
Here, the unit of the general formula (I) has two bonding positions for bonding with aldehydes and / or ketones described later. Two bonding positions are appropriately selected from the two o-positions and p-positions. Those having three binding positions are called trifunctional.
In addition, the bonding position of the unit of the chemical formula (II) with the aldehydes and / or ketones is three of two o-positions and p-positions.
General formulas (I) and (II) are units derived from m-cresol, and depending on the conditions during synthesis of the novolak resin, the weight average molecular weight, etc., both are usually included. .

The m-cresol unit is preferably contained in the range of 30 to 80 mol%, particularly 35 to 50 mol% in all phenolic units constituting the component (A).
By setting the ratio of m-cresol units to be equal to or higher than the lower limit of the above range, it is possible to suppress the tendency for the sensitivity to be slow, and by setting the ratio to the upper limit or lower, the tendency to increase the film reduction rate of the unexposed portion is suppressed. it can.

-3,4-xylenol unit A 3,4-xylenol unit is represented by the said general formula (III). There are two bonding positions with aldehydes and / or ketones (bifunctional), and usually two o-positions.
The 3,4-xylenol unit is preferably contained in a range of 10 to 60 mol%, particularly 20 to 50 mol% in all phenolic units constituting the component (A).
By setting the ratio of 3,4-xylenol units to be equal to or higher than the lower limit value of the above range, the tendency of the contrast to be lowered can be suppressed, and by setting the ratio to the upper limit value or lower, the tendency of the sensitivity to be delayed can be suppressed.

-2,5-xylenol unit A 2,5-xylenol unit is represented by the said general formula (IV). There are two bonding positions with aldehydes and / or ketones (bifunctional), which are usually in the o-position and p-position.
The 2,5-xylenol unit is preferably contained in the range of 5 to 55 mol%, particularly 10 to 40 mol% in all phenolic units constituting the component (A).
By setting the proportion of 2,5-xylenol units to be equal to or higher than the lower limit of the above range, the tendency of poor resolution can be suppressed, and by setting the ratio to the upper limit or lower, the film reduction rate of unexposed portions tends to increase. Can be suppressed.

Synthetic method and other blending etc. The component (A) is a phenol (m-cresol, 3,4-xylenol, 2,5-) which is a raw material of the units represented by the general formulas (I) to (IV). Phenols containing xylenol) and aldehydes and / or ketones can be obtained by a condensation reaction in the presence of an acid catalyst.

As the phenols, in addition to the phenols that are raw materials of the units represented by the general formulas (I) to (IV), other phenols may be used as long as the effects of the present invention are not impaired.
In addition, it is preferable that the phenolic unit corresponding to the said other phenols is 30 mol% or less in the whole phenolic unit which comprises (A) component, especially 20 mol% or less.

  Examples of other phenols include: phenol; cresols such as p-cresol and o-cresol; xylenols such as 2,3-xylenol and 3,5-xylenol; m-ethylphenol, p-ethylphenol, o- Ethylphenol, 2,3,5-trimethylphenol, 2,3,5-triethylphenol, 4-tert-butylphenol, 3-tert-butylphenol, 2-tert-butylphenol, 2-tert-butyl-4-methylphenol, Alkylphenols such as 2-tert-butyl-5-methylphenol; alkoxyphenols such as p-methoxyphenol, m-methoxyphenol, p-ethoxyphenol, m-ethoxyphenol, p-propoxyphenol and m-propoxyphenol Isopropenyl phenols such as o-isopropenylphenol, p-isopropenylphenol, 2-methyl-4-isopropenylphenol and 2-ethyl-4-isopropenylphenol; arylphenols such as phenylphenol; Examples thereof include polyhydroxyphenols such as' -dihydroxybiphenyl, bisphenol A, resorcinol, hydroquinone and pyrogallol. These may be used alone or in combination of two or more.

Examples of the aldehydes include formaldehyde, paraformaldehyde, trioxane, acetaldehyde, propionaldehyde, butyraldehyde, trimethylacetaldehyde, acrolein, crotonaldehyde, cyclohexanealdehyde, furfural, furylacrolein, benzaldehyde, terephthalaldehyde, phenylacetaldehyde, α-phenylpropyl. Aldehyde, β-phenylpropylaldehyde, o-hydroxybenzaldehyde, m-hydroxybenzaldehyde, p-hydroxybenzaldehyde, o-methylbenzaldehyde, m-methylbenzaldehyde, p-methylbenzaldehyde, o-chlorobenzaldehyde, m-chlorobenzaldehyde, p- Chlorobenzaldehyde, cinnamon Examples include aldehyde. Among these aldehydes, formaldehyde is preferable because it is easily available. In particular, in order to improve heat resistance, it is preferable to use a combination of hydroxybenzaldehydes and formaldehyde.
Examples of the ketones include methyl ethyl ketone and acetone.
These may be used alone or in combination of two or more.

  As the acidic catalyst, hydrochloric acid, sulfuric acid, formic acid, oxalic acid, p-toluenesulfonic acid and the like can be used.

  As the component (A), m-cresol units are 30 to 80 mol%, 2,5-xylenol units are 5-55 mol%, 3,4-xylenol units are 10 to 60 mol%, m- Particularly preferred is a novolak resin in which the sum of cresol units, 2,5-xylenol units, and 3,4-xylenol units is 100 mol%.

  In addition, the novolak resin used as the component (A) can be purified after the synthesis reaction by cutting the low-molecular region by a known fractionation operation, etc. High resolution, suppression of degassing phenomenon, and improvement of heat resistance From the point of view, it is preferable. Thereby, it becomes easy to make the dispersity (Mw / Mn) into a preferable range. Preferably, the content of the binuclear body after purification is 4% or less.

For the treatment such as fractionation, for example, the novolak resin obtained by the condensation reaction is dissolved in a good solvent, for example, alcohol such as methanol or ethanol, ketone such as acetone or methyl ethyl ketone, ethylene glycol monoethyl ether acetate, tetrahydrofuran or the like, It can be performed by a method such as pouring into water for precipitation.
Alternatively, the content of low nuclei such as binuclear compounds can be reduced by performing, for example, steam distillation in the middle of the synthesis reaction (condensation reaction) of the novolak resin (see JP 2000-13185 A).
Or it is also possible to refine | purify using an ion exchange resin.

In addition, the component (A) has a dissolution rate of 1 to 100 nm / sec. In a 3.5% by mass TMAH aqueous solution at 23 ° C. after purification as necessary. In particular, 10 to 50 nm / sec. It is preferable that it exists in the range.
By setting it as more than the lower limit of said range, the tendency for the film reduction rate of an unexposed part to become high can be suppressed, and the tendency for the solubility of an exposed part to be inferior at the time of image development can be suppressed by setting it as an upper limit or less.

  Here, the value of the dissolution rate is specifically a value obtained as follows. First, a solution obtained by dissolving a resin in an organic solvent (a concentration of 22% by mass) is applied onto a silicon wafer, and prebaked at 110 ° C. for 90 seconds to form a resin film having a thickness of 1000 nm. Next, the wafer is immersed in a TMAH developer at 23 ° C. and 3.5% by mass. Then, the time during which the resin film is completely dissolved is measured, and the amount of reduction (nm / sec.) Of the resin film per unit time is obtained therefrom. The amount of reduction of the resin film per unit time thus determined is the dissolution rate of the novolak resin.

Further, the mass average molecular weight (Mw) of the component (A) is preferably in the range of 2000 to 20000, particularly 3000 to 12000. The tendency which a film formability is inferior can be suppressed as it is more than the lower limit of the said range, and the tendency for sensitivity to be inferior can be suppressed by setting it as an upper limit or less.
The dispersity (Mw / Mn) is preferably 10 or less, particularly 6 or less. By setting it within this range, a high-resolution resist pattern can be easily obtained.

  Moreover, (A) component may consist of 1 type of novolak resins, and may consist of 2 or more types of novolak resins.

(B) Naphthoquinonediazide esterified product As the component (B), a naphthoquinonediazide esterified product of a phenol compound represented by the general formula (V) is used.
In the positive photoresist composition of the present invention, both a dense pattern and an isolated pattern are formed in good shape even when an ultrafine resist pattern of 0.35 μm or less is formed by a combination of the esterified product and the novolak resin. And a resist composition having excellent DOF characteristics.

Among these, an esterified product of a phenol compound represented by the general formula (V) and a 1,2-naphthoquinone diazide sulfonic acid compound is suitable and preferable for photolithography using i-line.
The 1,2-naphthoquinonediazide sulfonic acid compound is preferably a 1,2-naphthoquinonediazide-4-sulfonyl compound or a 1,2-naphthoquinonediazide-5-sulfonyl compound.

Incidentally, Q and ^{R 9} and, together with the carbon atoms between Q and ^{R 9,} when forming a cycloalkyl group having a carbon chain 3-6, Q and ^{R 9} are bonded, carbon atoms 2-5 The alkylene group is formed.

  Examples of the phenol compound corresponding to the general formula include tris (4-hydroxyphenyl) methane, bis (4-hydroxy-3-methylphenyl) -2-hydroxyphenylmethane, and bis (4-hydroxy-2,3,5). -Trimethylphenyl) -2-hydroxyphenylmethane, bis (4-hydroxy-3,5-dimethylphenyl) -4-hydroxyphenylmethane, bis (4-hydroxy-3,5-dimethylphenyl) -3-hydroxyphenylmethane Bis (4-hydroxy-3,5-dimethylphenyl) -2-hydroxyphenylmethane, bis (4-hydroxy-2,5-dimethylphenyl) -4-hydroxyphenylmethane, bis (4-hydroxy-2,5 -Dimethylphenyl) -3-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-2,5-dimethylphenyl) -2,4-dihydroxyphenylmethane, bis (4-hydroxyphenyl) -3-methoxy-4-hydroxyphenylmethane, bis ( 5-cyclohexyl-4-hydroxy-2-methylphenyl) -4-hydroxyphenylmethane, bis (5-cyclohexyl-4-hydroxy-2-methylphenyl) -3-hydroxyphenylmethane, bis (5-cyclohexyl-4-) Hydroxy-2-methylphenyl) -2-hydroxypheny Methane, bis (5-cyclohexyl-4-hydroxy-2-methylphenyl) -3,4-trisphenol compounds such dihydroxyphenylmethane;

  Linear type 3 such as 2,4-bis (3,5-dimethyl-4-hydroxybenzyl) -5-hydroxyphenol, 2,6-bis (2,5-dimethyl-4-hydroxybenzyl) -4-methylphenol Nuclear phenol compound; 1,1-bis [3- (2-hydroxy-5-methylbenzyl) -4-hydroxy-5-cyclohexylphenyl] isopropane, bis [2,5-dimethyl-3- (4-hydroxy) -5-methylbenzyl) -4-hydroxyphenyl] methane, bis [2,5-dimethyl-3- (4-hydroxybenzyl) -4-hydroxyphenyl] methane, bis [3- (3,5-dimethyl-4) -Hydroxybenzyl) -4-hydroxy-5-methylphenyl] methane, bis [3- (3,5-dimethyl-4-hydroxybenzyl) -4-hydride Xyl-5-ethylphenyl] methane, bis [3- (3,5-diethyl-4-hydroxybenzyl) -4-hydroxy-5-methylphenyl] methane, bis [3- (3,5-diethyl-4-) Hydroxybenzyl) -4-hydroxy-5-ethylphenyl] methane, bis [2-hydroxy-3- (3,5-dimethyl-4-hydroxybenzyl) -5-methylphenyl] methane, bis [2-hydroxy-3 -(2-hydroxy-5-methylbenzyl) -5-methylphenyl] methane, bis [4-hydroxy-3- (2-hydroxy-5-methylbenzyl) -5-methylphenyl] methane, bis [2,5 -Linear tetranuclear phenol compounds such as dimethyl-3- (2-hydroxy-5-methylbenzyl) -4-hydroxyphenyl] methane; 2,4- [2-hydroxy-3- (4-hydroxybenzyl) -5-methylbenzyl] -6-cyclohexylphenol, 2,4-bis [4-hydroxy-3- (4-hydroxybenzyl) -5-methylbenzyl] Linear pentanuclear phenol compounds such as -6-cyclohexylphenol and 2,6-bis [2,5-dimethyl-3- (2-hydroxy-5-methylbenzyl) -4-hydroxybenzyl] -4-methylphenol Linear polyphenol compounds such as

  Bis (2,3,4-trihydroxyphenyl) methane, bis (2,4-dihydroxyphenyl) methane, 2,3,4-trihydroxyphenyl-4′-hydroxyphenylmethane, 2- (2,3,4) -Trihydroxyphenyl) -2- (2 ', 3', 4'-trihydroxyphenyl) propane, 2- (2,4-dihydroxyphenyl) -2- (2 ', 4'-dihydroxyphenyl) propane, 2 -(4-hydroxyphenyl) -2- (4'-hydroxyphenyl) propane, 2- (3-fluoro-4-hydroxyphenyl) -2- (3'-fluoro-4'-hydroxyphenyl) propane, 2- (2,4-dihydroxyphenyl) -2- (4′-hydroxyphenyl) propane, 2- (2,3,4-trihydroxyphenyl) -2- (4′-hydroxyphenyl) Bisphenol type compounds such as propane, 2- (2,3,4-trihydroxyphenyl) -2- (4′-hydroxy-3 ′, 5′-dimethylphenyl) propane; 1- [1- (4- Hydroxyphenyl) isopropyl] -4- [1,1-bis (4-hydroxyphenyl) ethyl] benzene, 1- [1- (3-methyl-4-hydroxyphenyl) isopropyl] -4- [1,1-bis Examples include polynuclear branched compounds such as (3-methyl-4-hydroxyphenyl) ethyl] benzene; and condensed phenol compounds such as 1,1-bis (4-hydroxyphenyl) cyclohexane. These can be used alone or in combination of two or more.

  As the phenol compound, a trisphenol type compound and a linear type polyphenol compound are particularly preferable, and particularly preferable when a striped pattern is formed. In addition, as (B) component, the naphthoquinone diazide esterified product of phenol compounds other than this can also be used together.

The blending amount of the component (B) in the positive photoresist composition is 10 to 60% by mass with respect to the total amount of the component (A) and the following component (C) added as necessary from the viewpoint of the effect. , Preferably 20 to 50% by mass.
By making the compounding quantity of (B) component more than the lower limit of the said range, an image faithful to a pattern can be obtained and the tendency for transferability to fall can be suppressed. On the other hand, when the blending amount of the component (B) is not more than the upper limit of the above range, the sensitivity deterioration and the homogeneity of the formed resist film are lowered, and the tendency of the resolution to deteriorate can be suppressed.

  Moreover, in the positive photoresist composition of this invention, in the range which does not impair the preferable performance, (C) a sensitivity improvement agent can be further contained as desired.

(C) Sensitivity improver
As the sensitivity improver, various types such as those described in JP-A No. 11-35650 are known and can be appropriately selected and used. For example, bis (4-hydroxy-2,3,5-trimethylphenyl) -2-hydroxyphenylmethane, 1,4-bis [1 (3,5-dimethyl-4-hydroxyphenyl) isopropyl] benzene, 2,4- Bis (3,5-dimethyl-4-hydroxyphenylmethyl) -6-methylphenol, 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, 1- [1- (4-hydroxyphenyl) isopropyl] -4- [1 , 1-bis (4-hydroxyphenyl) ethyl] benzene, 1- [1- (3-methyl-4-hydroxypheny) ) Isopropyl] -4- [1,1-bis (3-methyl-4-hydroxyphenyl) ethyl] benzene, 2,6-bis [1- (2,4-dihydroxyphenyl) isopropyl] -4-methylphenol, 4,6-bis [1- (4-hydroxyphenyl) isopropyl] resorcin, 4,6-bis (3,5-dimethoxy-4-hydroxyphenylmethyl) pyrogallol, 4,6-bis (3,5-dimethyl- 4-hydroxyphenylmethyl) pyrogallol, 2,6-bis (3-methyl-4,6-dihydroxyphenylmethyl) -4-methylphenol, 2,6-bis (2,3,4-trihydroxyphenylmethyl)- 4-methylphenol, 1,1-bis (4-hydroxyphenyl) cyclohexane, 6-hydroxy-4a- (2,4-dihydro Ciphenyl) -9-1'-spirocyclohexyl-1,2,3,4,4a, 9a-hexahydroxanthene, 6-hydroxy-5-methyl-4a- (2,4-dihydroxy-3-methylphenyl)- And 9-1′-spirocyclohexyl-1,2,3,4,4a, 9a-hexahydroxanthene. Of these, 2,6-bis (2,5-dimethyl-4-hydroxybenzyl) -4-methylphenol, 1,4-bis [1 (3,5-dimethyl-4-hydroxyphenyl) isopropyl] benzene and the like are preferable. 2,4-bis [1- (4-hydroxyphenyl) isopropyl] -5-hydroxyphenol is also preferred.

  The content of the component (C) is preferably 5 to 50% by mass, more preferably 10 to 35% by mass with respect to the component (A).

Other components etc. In the positive photoresist composition, p-toluenesulfonic acid chloride (PTSC), 4,4′-diethylaminobenzophenone, 1,4-bis [ 1- (2-methyl-4-hydroxy-5-cyclohexylphenyl) isopropyl] benzene, 1,3-bis [1- (2-methyl-4-hydroxy-5-cyclohexylphenyl) isopropyl] benzene, etc. You may add in the range of about 0.01-5 mass%, 0.01-5 mass%, and 0.01-10 mass%, respectively.

  Further, the positive photoresist composition of the present invention may further contain a compatible additive, for example, an ultraviolet absorber for preventing halation, such as 2,2 ′, 4,4′-tetrahydroxybenzophenone, if necessary. 4-dimethylamino-2 ′, 4′-dihydroxybenzophenone, 5-amino-3-methyl-1-phenyl-4- (4-hydroxyphenylazo) pyrazole, 4-dimethylamino-4′-hydroxyazobenzene, 4, -Diethylamino-4'-ethoxyazobenzene, 4,4'-diethylaminoazobenzene, curcumin, etc., and surfactants for preventing striation, such as Fluorard FC-430, FC431 (trade name, manufactured by Sumitomo 3M Co., Ltd.) , Ftop EF122A, EF122B, EF122C, EF126 (trade name, TO Fluorosurfactants such as -Chem Products Co., Ltd., etc. can be added and contained within a range that does not hinder the object of the present invention.

Adjustment Method The positive photoresist composition is preferably used in the form of a solution by dissolving the above-described components in a suitable solvent.
Examples of such solvents include those used in conventional positive photoresist compositions, for example, ketones such as acetone, methyl ethyl ketone, cyclohexanone, methyl isoamyl ketone, 2-heptanone; ethylene glycol, propylene glycol , Diethylene glycol, ethylene glycol monoacetate, propylene glycol monoacetate, diethylene glycol monoacetate, or polyhydric alcohols such as monomethyl ether, monoethyl ether, monopropyl ether, monobutyl ether or monophenyl ether and derivatives thereof; Cyclic ethers; and ethyl lactate, methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methoxypro Include methyl propionic acid, esters such as ethyl ethoxypropionate. These may be used alone or in combination of two or more. Especially, ketones such as acetone, methyl ethyl ketone, cyclohexanone, methyl isoamyl ketone, 2-heptanone; ethyl lactate, methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methyl methoxypropionate, ethyl ethoxypropionate, etc. Esters are preferred.
Although it does not specifically limit, when the organic solvent is used by the compounding quantity used as the density | concentration of solid content of 20-50 mass%, Preferably it is 25-45 mass%, it is preferable from a coating | coated point.

Method of Use, etc. An example of a preferred method of using the positive photoresist composition of the present invention is as follows. First, a positive photoresist composition solution is applied onto a support such as a silicon wafer with a spinner and dried. A photosensitive layer is formed, and then exposed using a light source that emits ultraviolet light, such as a low-pressure mercury lamp, a high-pressure mercury lamp, or an ultrahigh-pressure mercury lamp, through a photomask on which a pattern is drawn. Next, when this is immersed in a weak alkaline aqueous solution such as an aqueous solution of 1 to 10% by mass of tetramethylammonium hydroxide (TMAH), the exposed portion is dissolved and removed, and an image (resist pattern) faithful to the mask pattern is obtained. Can be obtained.

  As described above, the positive photoresist composition of the present invention is preferably applied to those having a circuit in which dense patterns and isolated patterns are complicatedly mixed, particularly as in logic ICs. If the positive photoresist composition of the present invention is used, an ultrafine resist pattern of 0.35 μm or less can be formed in good shape both in a dense pattern and an isolated pattern. In this case, a resist pattern is obtained using a photomask in which various patterns corresponding to the logic IC are formed.

  Thus, in the present invention, even when an ultrafine resist pattern of 0.35 μm or less is formed, both dense patterns and isolated patterns can be formed with good shape, and excellent sensitivity, resolution, and depth of focus characteristics are obtained. In particular, characteristics suitable for the field of manufacturing logic ICs can be obtained.

[Synthesis Example 1] (Synthesis of Resin 1 of m-cresol / 3,4-xylenol / 2,5-xylenol = 50/10/40 (mol%, hereinafter the same))
A mixed phenol of 1-54 g of m-cresol, 12.2 g of 3,4-xylenol and 48.8 g of 2,5-xylenol and 1 g of p-toluenesulfonic acid were dissolved in γ-butyrolactone to prepare a 40% by mass solution.
37 mass% formalin 56.8g was dripped at this, and reaction was performed at 100 degreeC for 8 hours.
After completion of the reaction, 500 g of 2-heptanone was added, and then washing was performed 3 times using 500 g of pure water.
After the washing with pure water was completed, the solution was concentrated under reduced pressure to obtain a novolak resin solution having a mass average molecular weight (Mw) of 3800 and a dispersity (Mw / Mn) of 4.8.
The novolak resin was subjected to fractionation treatment to obtain a novolak resin 1 having a Mw of 5600, Mw / Mn of 3.0, and a dissolution rate of 33.33 nm / sec (23 ° C., dissolution rate in a 3.5 mass% TMAH aqueous solution).

[Synthesis Example 2] (Synthesis of Resin 2 with m-cresol / 3,4-xylenol / 2,5-xylenol = 50/30/20)
A mixed phenol of 54 g of m-cresol, 36.6 g of 3,4-xylenol and 24.4 g of 2,5-xylenol and 1 g of p-toluenesulfonic acid were dissolved in γ-butyrolactone to prepare a 40% strength by weight solution.
37 mass% formalin 52.7g was dripped at this, and reaction was performed at 100 degreeC for 8 hours.
After completion of the reaction, 500 g of 2-heptanone was added, and then washing was performed 3 times using 500 g of pure water.
After washing with pure water was completed, the solution was concentrated under reduced pressure conditions to obtain a novolak resin solution having Mw3500 and Mw / Mn4.7.
The novolak resin was fractionated to obtain a novolak resin 2 having a Mw of 5200, Mw / Mn of 2.8, and a dissolution rate of 25 nm / sec (23 ° C., dissolution rate in a 3.5 mass% TMAH aqueous solution).

[Synthesis Example 3] (Synthesis of Resin 3 with m-cresol / 3,4-xylenol / 2,5-xylenol = 40/20/40)
A mixed phenol of 43.2 g of m-cresol, 24.4 g of 3,4-xylenol and 48.8 g of 2,5-xylenol and 1 g of p-toluenesulfonic acid are dissolved in γ-butyrolactone to prepare a 40% by mass solution. did.
37 mass% formalin 52.7g was dripped at this, and reaction was performed at 100 degreeC for 8 hours.
After completion of the reaction, 500 g of 2-heptanone was added, and then washing was performed 3 times using 500 g of pure water.
After washing with pure water was completed, the solution was concentrated under reduced pressure conditions to obtain a novolac resin solution having Mw3800 and Mw / Mn6.5.
The novolak resin was fractionated to obtain a novolak resin 3 having a Mw of 5650, a Mw / Mn of 5.8, and a dissolution rate of 28.57 nm / sec (23 ° C., dissolution rate in a 3.5 mass% TMAH aqueous solution).

[Comparative Synthesis Example 1] (Synthesis of Resin 4 with m-cresol / p-cresol / 2,5-xylenol = 60/15/25)
In Synthesis Example 1, Mw8500, Mw / Mn5.7, dissolution rate 18.18 nm / sec (23), except that p-cresol was used in place of 3,4-xylenol and the blending amount was changed. Novolak resin 4 was synthesized at a dissolution rate of 3.5 ° C. and 3.5 mass% TMAH aqueous solution.

[Comparative Synthesis Example 2] (Synthesis of Resin 5 with m-cresol / p-cresol = 60/40)
Mw12000, Mw in the same manner as in Synthesis Example 1 except that m-cresol / p-cresol = 6/4 (molar ratio) mixed phenol was used instead of the mixed phenol used in Synthesis Example 1, and the blending amount was changed. Novolak resin 5 having a / Mn of 8.2 and a dissolution rate of 22.22 nm / sec (dissolution rate with respect to a 3.5 mass% TMAH aqueous solution at 23 ° C.) was synthesized.

[Comparative Synthesis Example 3] (Synthesis of Resin 6 with m-cresol / 3,4-xylenol = 80/20)
In place of the mixed phenol used in Synthesis Example 1, m-cresol / 3,4-xylenol = 80/20 (molar ratio) mixed phenol was used, except that the blending amount was changed, and in the same manner as in Synthesis Example 1, Mw 10000 , Novolak resin 6 having a Mw / Mn of 7.7 and a dissolution rate of 13.33 nm / sec (23 ° C., dissolution rate with respect to 3.5 mass% TMAH aqueous solution) was synthesized.

※樹脂組成は、ノボラック樹脂中の各単位のモル％である。なお、ｍ・・・ｍ−クレゾール、３，４・・・３，４−キシレノール、２，５・・・２，５−キシレノール、ｐ・・・ｐ−クレゾールを、それぞれ示す。

* The resin composition is the mol% of each unit in the novolak resin. In addition, m ... m-cresol, 3,4 ... 3,4-xylenol, 2,5 ... 2,5-xylenol, p ... p-cresol are shown, respectively.

[Examples 1-3, Comparative Examples 1-3]
Using the resins 1 to 6 synthesized in Synthesis Examples 1 to 3 and Comparative Synthesis Examples 1 to 3, coating solutions 1 to 6 for a positive photoresist composition having the following compositions were prepared.
Novolak resin 100 parts by mass The following naphthoquinone diazide esterified product 50 parts by mass (2,6-bis [2,5-dimethyl-3- (2-hydroxy-5-methylbenzyl) -4-hydroxybenzyl] -4-methylphenol 1 Esterification reaction product of 1 mol and 2 mol of 1,2-naphthoquinonediazide-5-sulfonic acid chloride)
Sensitivity improver (phenol compound X having the following structural formula) 30 parts by mass

480 parts by mass of the following solvent 2-heptanone

[Example 4]
A coating solution 7 was prepared in the same manner as in Example 1 except that the naphthoquinone diazide esterified product was changed to the following.
Esterification reaction product of 1 mol of bis (2-methyl-4-hydroxy-5-cyclohexylphenyl) -3,4-dihydroxyphenylmethane and 2 mol of 1,2-naphthoquinonediazide-5-sulfonic acid chloride

[Comparative Example 4]
A coating solution 8 was prepared in the same manner as in Example 1 except that the naphthoquinonediazide esterified product was changed to the following.
Esterification reaction product of 1 mol of the above phenol compound and 2 mol of 1,2-naphthoquinonediazide-5-sulfonic acid chloride

  The following evaluations were performed on the coating solutions 1 to 8 prepared in Examples 1 to 4 and Comparative Examples 1 to 4, and the results of Examples 1 to 3 and Comparative Examples 1 to 3 are shown in Table 2. The results of Comparative Example 4 are summarized in Table 3.

[Sensitivity evaluation]
The sample was applied onto a silicon wafer using a spinner and dried on a hot plate at 90 ° C. for 90 seconds to obtain a resist film having a thickness of 1 μm. The film was exposed through a mask using a reduced projection exposure apparatus NSR-2005i10D (Nikon Corporation, NA = 0.57) at intervals of 0.1 to 0.01 seconds, and then 110 ° C. for 90 seconds. This was subjected to a PEB (heating after exposure) treatment, developed with an aqueous 2.38 mass% tetramethylammonium hydroxide solution at 23 ° C. for 60 seconds, washed with water for 30 seconds and dried. At that time, the exposure time (Eop) required to faithfully reproduce the mask pattern set dimension (line width 0.35 μm, L & S = 1: 1) was expressed in milliseconds (ms) as sensitivity.

[Resolution evaluation]
The limit resolution in the exposure amount (the above Eop) for reproducing the mask pattern corresponding to 0.35 μmL & S is shown.

[Focus depth range characteristics]
1. Using the dense pattern reduction projection exposure system NSR-2005i10D (Nikon Corporation, NA = 0.57), Eop [mask pattern setting dimension (line width 0.35 μm, L & S = 1: 1) is faithfully reproduced. The exposure time required for the exposure is taken as a reference exposure amount, and the SEM (scanning electron microscope) photograph of the resist pattern obtained by performing exposure and development at the exposure amount by appropriately shifting the focus up and down is observed. It was. From the SEM photograph, the maximum focus deviation (μm) obtained within a range of dimensional change of ± 10% of the set dimension for a dense pattern with a line width of 0.35 μm and L & S = 1: 1 is the depth of focus width characteristic. did.

2. Using the isolated pattern reduction projection exposure system NSR-2005i10D (Nikon Corporation, NA = 0.57), Eop [mask pattern set dimensions (line width 0.35 μm, L & S = 1: 1) are faithfully reproduced. The exposure amount required to be performed] is a reference exposure amount, and the SEM (Scanning Electron Microscope) photograph of the resist pattern obtained by performing exposure and development at the exposure amount by appropriately shifting the focus up and down is observed. It was. From the SEM photograph, the maximum value (μm) of defocus obtained within an isolated pattern having a width of 0.35 μm within a dimensional change of ± 10% of the set dimension (0.35 μm) was defined as the depth-of-focus width characteristic.

3. Dot pattern reduction projection exposure apparatus NSR-2005i10D (Nikon, NA = 0.57), vertical 0.6 μm × 0.6 μm dot pattern compatible, duty ratio 2: 1 (dot to dot spacing is 1.20 μm) ) Eop [exposure amount required to faithfully reproduce the mask pattern set dimension (line width 0.35 μm, L & S is 1: 1)] as a reference exposure amount, The SEM photograph of the dot pattern (0.6 μm × 0.6 μm) obtained by shifting the focus up and down as appropriate and performing exposure and development was observed. From the SEM photograph, the maximum value (μm) of the focal shift obtained by a rectangular dot pattern of 0.6 μm × 0.6 μm within a range of ± 10% of the set dimension was defined as the depth of focus width characteristic (dot pattern).

4). Total focal depth characteristics In the above evaluations 1 to 3, a 0.35 μm rectangular resist pattern is within a range of ± 10% of the set dimension with respect to any resist pattern of dense pattern, isolated pattern, and dot pattern. The maximum value (μm) of the defocus obtained was taken as the total depth of focus characteristic.

From the results of the above-mentioned Examples and Comparative Examples, when using the same type of component (B), the results according to the present invention are similar to the Comparative Examples in sensitivity and resolution. In addition, it has been clarified that various patterns (particularly dot patterns) can be dealt with in the depth of focus width characteristics.

Claims (2)

(A) the following general formula (I),

And / or the following chemical formula (II)

M-cresol unit represented by the following general formula (III)

3,4-xylenol unit represented by the following general formula (IV)

An alkali-soluble novolak resin containing a 2,5-xylenol unit represented by formula (B):

[Wherein R ^{1 to} R ⁸ are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a cycloalkyl group having 3 to 6 carbon atoms. R ^{9 to} R ¹¹ each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms; Q is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or the following chemical formula (VI) The residue represented,

Wherein R ¹² and R ¹³ are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a cycloalkyl group having 3 to 6 carbon atoms. C represents an integer of 1 to 3), and when Q is bonded to the end of R ⁹ , together with Q, R ⁹ , and the carbon atom between Q and R ⁹ , carbon atom chain 3 Represents a cycloalkyl group of -6; a and b represent an integer of 1 to 3; d represents an integer of 0 to 3; and n represents an integer of 0 to 3]
A positive photoresist composition comprising a naphthoquinone diazide esterified product of a phenol compound represented by the formula: The (A) alkali-soluble novolak resin has m-cresol units of 30 to 80 mol%, 2,5-xylenol units of 5 to 55 mol%, and 3,4-xylenol units of 10 to 60 mol%, m 2. The positive photoresist composition according to claim 1, wherein the total amount of the cresol unit, the 2,5-xylenol unit and the 3,4-xylenol unit is 100 mol% of a novolak resin.