Radiation imagery chemistry: process – composition – or product th – Diazo reproduction – process – composition – or product – Composition or product which contains radiation sensitive...
Reexamination Certificate
2002-03-15
2004-06-01
Chu, John S. (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Diazo reproduction, process, composition, or product
Composition or product which contains radiation sensitive...
C430S270100, C430S905000
Reexamination Certificate
active
06743562
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a positive photoresist composition used for the production of semiconductor integrated circuit devices, masks for fabricating integrated circuits, printed circuit boards, liquid crystal panels, and the like.
BACKGROUND OF THE INVENTION
As positive photoresist compositions, chemically amplified resist compositions are described in U.S. Pat. No. 4,491,628 and European Patent No. 29,139.
Chemically amplified positive resist compositions are materials for forming patterns on a substrate by generating an acid on a region exposed to radiation such as far ultraviolet rays, and changing a solubility in a developer between the exposed region and non-exposed region to active radiation.
The above-described chemically amplified positive resist compositions can be can be roughly classified into three groups, that is, a three component system formed of an alkali soluble resin, a compound (photoacid generator) which generates an acid by exposure to radiation, and a dissolution inhibitive compound having an acid decomposable group and inhibiting dissolution in the alkali soluble resin; a two component system formed of a resin having a group which decomposes by the reaction with an acid and becomes alkali soluble and a photoacid generator; and a hybrid system formed of a resin having a group which decomposes by the reaction with an acid and becomes alkali soluble, a low-molecular dissolution inhibitive compound having an acid decomposable group, and a photoacid generator.
Various techniques for improving the performance of such chemically amplified positive resist compositions by mixing at least two resins (acid decomposable resins) which decompose by the action of an acid, thereby having a heightened solubility in an alkali developer are known.
In European Patent Application Laid-Open No. 1024406, described is a technique of improving the performance by mixing an acid decomposable resin with at least 2 photoacid generators.
There is however a demand for suppressing deteriorations in resolving power and size accuracy which owe to miniaturization of patterns, and for improving PED stability to control size fluctuations.
The term “PED (Post Exposure Delay) stability” means stability of the film allowed to stand in an exposure apparatus or an applicator until heating operation is started after exposure.
SUMMARY OF THE INVENTION
An object of the present invention is therefore to provide a chemically amplified positive photoresist composition excellent in both the depth of focus and PED stability.
With the foregoing in view, the present inventors have carried out an extensive investigation. As a result, the above-described object has been attained by using a positive photoresist composition containing an acid decomposable resin and at least two photoacid generators, leading to the completion of the present invention.
The positive photoresist composition according to the present invention has the following constitution:
(1) A positive photoresist composition comprising:
(a) a resin which decomposes by the action of an acid, thereby having an increased solubility in an alkali developer; and
(b) at least one compound which is represented by the following formula (1) and generates an acid by exposure to active rays or radiation, and at least one compound which is represented by the following formula (2) and generates an acid by exposure to active rays or radiation:
wherein R
1
and R
2
each independently represents one of an alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group and a cycloalkenyl group each of which has 1 to 16 carbon atoms and may have at least one substituent, an aryl group and a heteroaryl group each of which may have at least one substituent and a cyano group,
at least one of R
1
and R
2
may be bonded to at least one of R
1
and R
2
of another compound represented by the formula (1) via one of an alkylene chain, an alkenylene chain and an alkynylene chain each of which has 2 to 8 carbon atoms and may have at least one substituent and a connecting chain comprising one of phenylene, furylene and thienylene each of which may have at least one substituent and a connecting chain comprising one of —O—, —S—, —N— and —CO—,
R
3
represents one of an alkyl group and a cycloalkyl group each of which has 1 to 16 carbon atoms and may have at least one substituent and an aryl group may have at least one substituent and
R
4
and R
5
each independently represents one of an alkyl group, cycloalkyl group and aryl group each of which may have at least one substituent.
According to the present invention, chemically amplified positive photoresist compositions excellent in both the depth of focus and PED stability are provided.
DETAILED DESCRIPTION OF THE INVENTION
The present invention will hereinafter be described more specifically.
(a) A resin which decomposes by the action of an acid, thereby having a heightened solubility in an alkali developer (the resin of (a)).
The term “resin having a group decomposable by the action of an acid (which may be called “acid decomposable group”)” as used herein means a compound which has a structure obtained by introducing an acid decomposable group into a compound available by polymerization of a monomer and having a molecular weight distribution, and becomes alkali soluble by the action of an acid.
The resin having an acid decomposable group means a resin having this acid decomposable group in either of the main chain or side chain thereof or in both of these chains. Of these, the resin having an acid decomposable group in its side chain is preferred.
The parent resin having such an acid decomposable group bonded thereto as a side chain is an alkali soluble resin having, in the side chain thereof, a group —OH or —COOH, preferably a group —R
0
—COOH or —Ar—OH in the side chain.
Here, —R
0
— represents a substituted or unsubstituted aliphatic or aromatic hydrocarbon having at least two valences, while the group —Ar— represents a monocyclic or polycyclic aromatic group which have at least two valences and may have a substituent.
In the present invention, alkali soluble resins having a phenolic hydroxyl group are preferred as the parent resin.
As the alkali soluble resin usable in the invention and having a phenol hydroxyl group, preferred are copolymers or homopolymers each containing at least 30 mole %, preferably 50 mole % of repeating units corresponding to o-, m- or p-hydroxystyrene (which will hereinafter be called “hydroxystyrene”, collectively) or o-, m- or p-hydroxy-&agr;-methylstyrene (which will hereinafter be called “hydroxy-&agr;-methylstyrene”, collectively), or resins wherein the benzene nucleus of the units has been partially hydrogenated. Of these, a p-hydroxystyrene homopolymer is more preferred.
Examples of a monomer other than hydroxystyrene and hydroxy-&agr;-methylstyrene to be used for preparation of the copolymer include acrylate esters, methacrylate esters, acrylamides, methacrylamides, acrylonitrile, methacrylonitrile, maleic anhydride, styrene, &agr;-methylstyrene, acetoxystyrene, alkoxystyrenes and alkylstyrenes. Of these, styrene, acetoxystyrene and t-butylstyrene are more preferred.
In the invention, although no limitation is imposed on the resin (a) insofar as its solubility in an alkali developer can be increased, the following ones are usable:
In the above formulas, W represents an acid decomposable group and R
14
represents an inert group.
Examples of the acid decomposable group as W include groups of the below-described formulas (X), (X1), (X2) and (X3), of which those of the formula (X) are preferred.
In the formula (X), R
1
and R
2
may be the same or different and each independently represents a hydrogen atom or an alkyl or cycloalkyl group which may have a substituent,
Z represents a C
1-10
alkyl or cycloalkyl group which may have a substituent, and
m stands for an integer of 1 to 20.
In the formulas (X1) to (X3), R, R′ and R″ may be the same or different and each independently represents a C
1-12
alkyl group which may have a subs
Kawabe Yasumasa
Momota Mokoto
Chu John S.
Fuji Photo Film Co. , Ltd.
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