Alkenylphenol copolymer and process for producing the same

Details Alkenylphenol copolymer and process for producing the same Alkenylphenol copolymer and process for producing the same

2002-03-01

2004-06-01

Seidleck, James J. (Department: 1711)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Mixing of two or more solid polymers; mixing of solid...

C525S094000, C528S086000, C528S100000, C528S152000

Reexamination Certificate

active

06743861

ABSTRACT:

TECHNICAL FIELDS
The present invention relates to narrow-disperse alkenylphenol copolymers that have not known yet and to processes for the preparation of the same. In more detail, it relates to narrow-disperse alkenylphenol copolymers that have controlled structures and with alkenylphenol units, alkenylphenyl ether units and (meth)acrylic ester units as essential constituent units, and to processes for the preparation of the same. The alkenylphenol copolymers of the present invention have expectations to be used as resist materials for excimer lasers.
BACKGROUND ART
Alkenylphenol copolymers useful as resist materials have been well known so far. For example, Japanese Patents Laid-open Nos. Hei 4-211258, 7-209868, 7-49569, 9-160244 and 11-125907 describe random copolymers containing repeating units represented by Formulae (I), (II) and (III). Japanese Patent Laid-open No. Hei 11-125907 describes positive-type radiation-sensitive resin compositions that have, as constituents, resins insoluble or hardly soluble in alkali and protected with groups to be dissociated with acids. The resins become soluble in alkali when the said acid dissociating groups are dissociated. It describes, as constituent units of the said resins, random copolymers or block copolymers each having constituent units represented by Formula (IV) (wherein, R
13
and R
14
are each independently hydrogen or methyl, and R
15
is hydrogen, t-butoxy or another group).
Japanese Patent Laid-open No. Hei 10-265524 describes a polymer compound having a repeating unit represented by Formula (VII) shown below (wherein, R is hydroxyl or OR
20
, and R
20
is a group unstable to acids). The polymer is cross-linked by a cross-linking group with an intramolecular and/or intermolecular C—O—C groups that are obtained by a reaction of part of the phenolic hydroxyl group and/or carboxyl group, which are represented by R of Formula (VII), with an alkenyl ether compound or halogenated alkyl ether. The polymer has the weight-average molecular weight of 1,000 to 500,000, with the total amount of the said acid-unstable groups and cross-linking groups at a ratio exceeding 0 mole% and less than 80 mole% of the average of the whole phenolic hydroxyl and carboxyl groups.
Japanese Patent Laid-open No. Hei 10-53621 describes polymers having a structure represented by Formula (VIII) (wherein, R
21
is hydrogen or lower alkyl, R
23
and R
24
are hydrogen, alkyl optionally substituted with halogen or another, R
25
is alkyl optionally substituted with halogen or another, and R
26
is carboxyl optionally substituted with alkyl or another), with dispersibility of more than 1 and less than 1.5.
DISCLOSURE OF THE INVENTION
Homopolymers and copolymers of alkenylphenols, represented by poly-p-hydroxystyrene and the like, are useful as materials for chemical amplification type resists for excimer lasers. Among them, particularly resists produced using copolymers consisting of hydroxystyrenes and acrylic esters are known as so-called ESCAP type resists able to give higher resolution.
In this field, technology to make resolution higher has been advanced remarkably, and higher resolution is always looked for. A desirable structure for the ESCAP type polymers to realize higher resolution is a structure with groups that protect part of the alkenylphenol portions and are eliminated and/or decomposed with acids produced when the groups are exposed to light. Besides, a desirable polymer has a narrow molecular distribution and a controlled structure. This kind of structure controls unnecessary, excessive diffusion of acids generated from photoacid generators of a resist composition, and the solubility of the phenolic hydroxyl or carboxyl groups is controlled so as not to dissolve excessively in alkali developers. Thanks to these effects, the obtained polymer is expected to be a resist material to contribute to make resolution higher.
Many of ESCAP type polymers with such structures and which have been reported so far are synthesized by radical polymerization, and are not satisfactory because of the dispersibility (Mw/Mn) of more than 1.50. The said Japanese Patent Laid-open No. Hei 10-265524 has disclosed an ESCAP type polymer having a narrow molecular distribution and a controlled structure. The polymer is unsatisfactory, however, because the ester portion as a protecting group is a group that is not eliminated with an acid, such as methyl, or that has a carboxylic acid residue. With such an ester structure, it is difficult to make solubility in an alkali developer different between an area exposed to light and that not exposed. Besides, a method is applied of introducing the said group protecting the hydroxyl or carboxylic acid group partially at a later stage. Because of it, there is a problem of difficulty to completely protect particularly the carboxylic acid portions in the polymer.
The said Japanese Patent Laid-open No. Hei 11-125907 describes random copolymers or block copolymers, but has no description of synthetic methods and molecular distributions of these polymers. The said Japanese Patent Laid-open No. Hei 10-53621 has disclosed ESCAP type polymers with narrow dispersibility, but actually described only random copolymers, which were not satisfactory as materials for high resolution resists.
It is an object of the present invention to provide narrow-disperse, ESCAP type polymers that do not contain carboxylic acid residues, have controlled structures, and have groups protecting phenolic hydroxyl groups and being eliminated and/or decomposed with acids selectively and partially.
The inventors of the present invention have studied in earnest to accomplish the above object and found that block copolymerization consisting of alkenylphenols with protected phenolic hydroxyl groups or the said alkenylphenols and vinylaromatic compounds, with (meth)acrylic esters results in eliminating and/or decomposing the groups protecting the phenolic hydroxyl groups with acids selectively and partially. It was confirmed that alkenylphenol copolymers with narrow molecular distributions and controlled structures could be synthesized from the said block copolymers. Thus the present invention has been completed.
The present invention relates to alkenylphenol copolymers that Component (A) containing a repeating unit represented by Formula (I)
(wherein, R
1
is hydrogen or methyl, R
2
is alkyl having 1 to 5 carbons, m is 0, 1 or 2 and R
2
is the same or different when m is 2) and a repeating unit represented by Formula (II)
(wherein, R
3
is hydrogen or methyl, R
4
is a group to be eliminated and/or decomposed with an acid, R
5
is alkyl having 1 to 5 carbons, n is 0, 1 or 2 and R
5
is the same or different when n is 2), and Component (B) containing a repeating unit represented by Formula (III)
(wherein, R
6
is hydrogen or methyl, and R
7
is a group having a t-butyl group and to be eliminated and/or decomposed with an acid) are bound in block in the (A)-(B) form, and that have a ratio (Mw/Mn) of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn) in a range of 1.00 and 1.50 and without carboxylic acid residues. It also relates to the said alkenylphenol copolymers with weight-average molecular weight of 1,000 to 100,000.
The present invention relates to a process for the preparation of the said alkenylphenol copolymer, characterized by that a compound represented by Formula (IV) with the protected hydroxyl group of the phenol residue
(wherein, R
8
is hydrogen or methyl, R
9
is a group to be eliminated and/or decomposed with an acid, R
10
is alkyl having 1 to 5 carbons, p is 0, 1 or 2 and R
10
may be the same or different when p is 2) is polymerized, or a compound of Formula (IV) and a vinylaromatic compound are copolymerized, by anionic polymerization using an anionic polymerization initiator as a polymerization initiator, followed by copolymerization with a (meth)acrylic ester represented by Formula (V)
(wherein, R
11
is hydrogen or methyl, and R
12
is a group having a t-butyl group and to be eliminated and/or decompo

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