Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Radiation sensitive composition or product or process of making
Reexamination Certificate
2000-10-13
2002-02-05
Ashton, Rosemary (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Radiation sensitive composition or product or process of making
C430S281100, C522S031000
Reexamination Certificate
active
06344307
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a novel photosensitive resin composition.
BACKGROUND ART
Photoresist for forming a pattern image by photography is widely used in the field of manufacturing printed circuit boards. Especially, an aqueous photoresist developable with a dilute alkaline solution is less problematic, as compared to a photoresist developable with an organic solvent, from the viewpoints of toxicity to human body, environmental pollution, fire risk and the like. As such aqueous photoresist, there has been known, for example, an aqueous photosensitive resin composition comprising a protic ammonium salt-containing resin obtained by neutralizing a carboxyl group-containing resin with a basic compound such as tertiary amine, a compound having two or more vinylether groups in a molecule and a compound which generates an acid upon irradiation with actinic energy rays (Japanese Unexamined Patent Publication No. 313134/1994).
The resin composition functions as a positive photoresist by such a mechanism that, by heating a coating film of the resin composition, the coating film is cured by crosslinking by an addition reaction of a carboxyl group and a vinylether group, so that the coating film becomes insoluble to an organic solvent or an alkaline solution, and then the coating film is irradiated with actinic energy rays and subsequently heated, so that the crosslinked structure in the coating film are broken by a catalytic action of an acid generated upon irradiation, thereby the irradiated areas become soluble to the organic solvent or the alkaline solution.
However, the above composition has a problem that the composition fails to form a pattern image excellent in resolution, since the acid generated by the irradiation with the actinic energy rays is trapped by a basic compound contained in the coating film to result in an insufficient breakage of the crosslinked structure in the coating film, so that the irradiated areas cannot be removed sufficiently by the organic solvent or the alkaline solution. Such problem is considered attributable to the use of the protic ammonium salt-containing resin, i.e., in the case of using the protic ammonium salt-containing resin for forming a coating film, the basic compound used for neutralization of the resin is regenerated upon heating the coating film and traps the acid generating upon irradiation with actinic energy rays to cause the problem.
DISCLOSURE OF INVENTION
An object of the present invention is to provide a novel photosensitive resin composition which can overcome the problem of the conventional techniques.
Another object of the present invention is to provide a novel photosensitive resin composition capable of forming a pattern image excellent in resolution as a positive photoresist.
Other objects and features of the present invention will become apparent from the following description.
The present invention provides a photosensitive resin composition characterized by comprising
(A) a resin having at least one aprotic onium salt represented by the general formula:
—COO
−
·W
+
(1)
and/or the general formula:
{in each of the above general formulas, W
+
represents
wherein, Z represents a nitrogen atom or a phosphorus atom; Y represents a sulfur atom; R
1
, R
2
, R
3
and R
4
are the same or different and each represents an organic group having 1 to 30 carbon atoms; R
1
and R
2
or R
1
, R
2
and R
3
may combine to form a heterocyclic ring together with the nitrogen atom, phosphorus atom or sulfur atom to which they are bound; and any one of R
1
to R
4
may be a group represented by the general formula:
(wherein, R
5
is a hydrocarbon group having 1 to 28 carbon atoms which may optionally be substituted by a hydroxyl group, an alkoxy group, an ester group or a halogen atom, or a hydrogen atom)},
(B) a compound having two or more vinylether groups in a molecule, and
(C) a compound which generates an acid upon irradiation with actinic energy rays.
The inventors have carried out an extensive research to solve the above problem of the prior art and found that it is possible to solve the problem by the use of the above specific aprotic onium salt-containing resin. Based on the findings, the present invention has been accomplished.
When a coating film of the composition of the invention is heated to cure, the onium base W
+
contained in the aprotic onium salt-containing resin (A) is thermally decomposed via the Hoffman degradation or the like to be released from the resin skeleton and volatilized. Therefore, the acid generated by the irradiation with actinic energy rays is never trapped in the cured coating film since no basic compound exists therein. Consequently, the crosslinked structure in the cured coating film is efficiently broken, to thereby achieve a pattern image excellent in resolution.
The composition of the invention is designed to achieve a pattern image excellent in resolution as a positive photoresist in such a manner that the composition coated on a printed board is heated to be cured by crosslinking, followed by subjecting the cured coating film to irradiation with actinic energy rays to generate an acid which breaks crosslinks in areas exposed to the irradiation, thereby making only the exposed areas to be soluble to a developing solution and removed.
Components of the composition of the invention are described in detail in the following.
(A) Aprotic Onium Salt-Containing Resin
The resin (A) comprised in the photosensitive resin composition of the invention has at least one aprotic onium salt represented by the general formula (1) and/or the general formula (2).
The organic groups having 1 to 30 carbon atoms represented by R
1
, R
2
, R
3
and R
4
in the general formulas (1) and (2) are not limited insofar as they do not substantially inhibit ionization of an ammonium base, a phosphonium base or a sulfonium base, and, for example, hydrocarbon groups having 1 to 30 carbon atoms which may contain a heteroatom such as an oxygen atom in the form of a hydroxyl group, an alkoxy group and so on are typically used as the organic groups.
Examples of the hydrocarbon groups are aliphatic, alicyclic or aromatic hydrocarbon groups such as an alkyl group, a cycloalkyl group, a cycloalkylalkyl group, an aryl group and an aralkyl group.
The alkyl group may be a straight- or branched-chain group having 8 or less carbon atoms, preferably lower groups; examples of which include methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl, tert-butyl, pentyl, heptyl and octyl groups, etc.
The cycloalkyl group or the cycloalkylalkyl group may preferably be those having 5 to 8 carbon atoms; examples of which include cyclopentyl, cyclohexyl, cyclohexylmethyl and cyclohexylethyl groups, etc. Phenyl, toluyl and xylyl groups or the like may suitably be used as the aryl group, and a benzyl group or the like may suitably be used as the aralkyl group.
Further, preferred examples of the hydrocarbon group containing the heteroatom such as an oxygen atom include a hydroxyalkyl group (especially a hydroxy-lower-alkyl group), specifically a hydroxymethyl, hydroxyethyl, hydroxybutyl, hydroxypropyl, hydroxypentyl, hydroxyheptyl and hydroxyoctyl groups, etc. and alkoxyalkyl group (especially a lower-alkoxy-lower-alkyl group), specifically a methoxymethyl, ethoxymethyl, ethoxyethyl, propoxymethyl, propoxyethyl, butoxymethyl and butoxyethyl groups, etc.
In the general formulas (1) and (2), R
5
is a hydrocarbon group having 1 to 28 carbon atoms which may optionally be substituted by a hydroxy group, an alkoxy group, an ester group or a halogen atom, or a hydrogen atom. Examples of a hydrocarbon group which is not substituted include an aliphatic, alicyclic or aromatic hydrocarbons such as an alkyl group, an alkenyl group, a cycloalkyl group, a cycloalkylalkyl group, an aryl group and an aralkyl group.
Among above hydrocarbon groups, the alkyl group and the alkenyl group are preferred and these may be straight- or branched-chain groups; examples of which include a methyl, ethyl, pr
Imai Genji
Isozaki Osamu
Kogure Hideo
Kojima Daisuke
Armstrong Westerman Hattori McLeland & Naughton LLP
Ashton Rosemary
Kansai Paint Co. Ltd.
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