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
2001-08-14
2003-10-07
Baxter, Janet (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
C430S311000
Reexamination Certificate
active
06630282
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a positive-working photoresist composition used for patterning in the manufacture of fine electronic devices or, more particularly, to a crosslinked positive-working photoresist composition of the chemical-amplification type capable of giving a patterned resist layer with high pattern resolution and excellent resistance against etching.
In recent years, chemical-amplification positive-working photoresist compositions are widely employed in the photo-lithographic patterning process in the mass production of certain fine electronic devices which require extremely fine patterning of the resist layer because pattern resolution with fineness of 0.15 to 0.22 &mgr;m can be accomplished with a photoresist composition of this type when used in combination with an underlying appropriate anti-reflection coating film.
On the other hand, the demand for finer and finer patterning of the resist layer is increasing year by year in the manufacture of semiconductor devices and an innovative process of next generation is now under way of development for accomplishing patterning fineness of 0.12 to 0.15 &mgr;m which is possible only by the use of an exposure light source of a very short wavelength such as KrF and ArF excimer laser beams. While the film thickness of the photoresist layer is a factor limiting fineness of pattern resolution and a thickness not exceeding 0.6 &mgr;m is desired for the above-mentioned fineness of resolution, a problem which must be solved with a photoresist layer of such a small thickness is the low resistance of the patterned resist layer therefrom against etching involved in the semiconductor processing.
Crosslinked chemical-amplification positive-working photoresist compositions are known as disclosed in Japanese Patent Kokai 6-148889 and 8-305025, in which the base resinous ingredient is a polymer containing monomeric units derived from a hydroxystyrene and crosslinks are formed between the molecules of the base resin by bridging the hydroxyl groups of the hydroxystyrene units with crosslinking units of divinyl ether and the like. The crosslinked chemical-amplification positive-working photoresist compositions, however, cannot fully comply with the technological requirement for high pattern resolution and etching resistance when the thickness of the resist layer is so small as mentioned above even though the requirement for improved etching resistance can be satisfied therewith.
SUMMARY OF THE INVENTION
The present invention accordingly has an object, in view of the above described problems and disadvantages in the prior art, to provide a novel and improved crosslinked chemical-amplification positive-working photoresist composition capable of giving a patterned resist layer of high pattern resolution and highly resistant against etching even when the thickness of the photoresist layer is so small as to be able to comply with the requirement in recent years.
Thus, the crosslinked positive-working photoresist composition is a uniform blend as dissolved in an organic solvent which comprises, according to the first aspect of the invention:
(a1) a polymeric resin which is subject to an increase of the solubility in an aqueous alkaline solution in the presence of an acid; and
(b) a radiation-sensitive acid-generating agent capable of releasing an acid when irradiated with a radiation, in which the polymeric resin as the component (a1) is a quaternary copolymer consisting of four kinds of monomeric units including
(a11) monomeric units of the first type represented by the general formula
—CR(Pn—OH)—CH
2
—,
in which R is a hydrogen atom or a methyl group and Pn is a phenylene group,
(a12) monomeric units of the second type represented by the general formula
—CRPh—CH
2
—,
in which R is a hydrogen atom or a methyl group and Ph is a phenyl group,
(a13) monomeric units of the third type represented by the general formula
in which R is a hydrogen atom or a methyl group, R
1
is an alkyl group having 1 to 4 carbon atoms and the subscript m is a positive integer of 3 to 7, and
(a14) monomeric units of the fourth type represented by the general formula
in which R is a hydrogen atom or a methyl group, each R
1
is, independently from the others, an alkyl group having 1 to 4 carbon atoms, the subscript n is 1, 2 or 3 and A is a single bond or an organic group of (n+1) valency.
Further, the crosslinked positive-working photoresist composition is a uniform blend as dissolved in an organic solvent which comprises, according to the second aspect of the invention:
(a2) a polymeric resin which is subject to an increase of the solubility in an aqueous alkaline solution in the presence of an acid; and
(b) a radiation-sensitive acid-generating agent capable of releasing an acid when irradiated with a radiation, in which the polymeric resin as the component (a2) is a quaternary copolymer consisting of four kinds of monomeric units including
(a21) monomeric units of the first type represented by the general formula
—CR(Pn—OH)—CH
2
—,
in which R is a hydrogen atom or a methyl group and Pn is a phenylene group,
(a22) monomeric units of the second type represented by the general formula
—CRPh—CH
2
—,
in which R is a hydrogen atom or a methyl group and Ph is a phenyl group,
(a23) monomeric units of the third type represented by the general formula
in which R is a hydrogen atom or a methyl group, R
2
3
jointly denoting three R
2
groups represents a combination of one saturated polycyclic hydrocarbon group and two alkyl groups each having 1 to 4 carbon atoms or a combination of an alkyl group having 1 to 4 carbon atoms as one of the three R
2
groups and a saturated polycyclic hydrocarbon group formed jointly from two divalent hydrocarbon groups as the rest of the three R
2
groups together with the carbon atom adjacent to the ester linkage, and
(a24) monomeric units of the fourth type represented by the general formula
in which R is a hydrogen atom or a methyl group, each R
1
is, independently from the others, an alkyl group having 1 to 4 carbon atoms, the subscript n is 1, 2 or 3 and A is a single bond or an organic group of (n+1) valency.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
As is understood from the above given description, the photoresist compositions of the invention according to the first and second aspects of the invention are each characterized in that the resinous component (a1) or (a2), which is imparted with increased solubility in an aqueous alkaline solution in the presence of an acid, is a quaternary copolymer consisting of four kinds of the monomeric units (a11) to (a14) or (a21) to (a24).
In the following, detailed descriptions are given of the inventive photoresist compositions first according to the first aspect of the invention and then according to the second aspect of the invention.
The monomeric unit of the first type, i.e. (a11), constituting the resinous component (a1) is represented by the general formula —CR(Pn—OH)—CH
2
—, in which R is a hydrogen atom or a methyl group and Pn is a phenylene group including 1,2-, 1,3- and 1,4-phenylene groups. These monomeric units can be introduced by using a hydroxystyrene or a-methyl hydroxystyrene as one of the comonomers from which the quaternary copolymeric resin (a1) is prepared by copolymerization. The monomeric units of this type contribute to the alkali-solubility and etching resistance of the copolymeric resin.
The monomeric units of the second type, i.e. (a12), are represented by the general formula —CRPh—CH
2
—, in which R has the same meaning as defined above and Ph is a phenyl group. These monomeric units (a12) can be introduced by the use of styrene or &agr;-methylstyrene as one of the comonomers from which the resinous component (a1) is prepared by copolymerization. These monomeric units (a12) contribute to the alkali-insolubility and etching resistance of the copolymeric resin (a1).
The monomeric units of the third type, i.e. (a13), are represented by the general formula (I) given above and are the units having acid-dissociable
Kinoshita Yohei
Oomori Katsumi
Takayama Toshikazu
Yamada Tomotaka
Baxter Janet
Tokyo Ohka Kogyo Co. Ltd.
Walke Amanda C.
Wenderoth , Lind & Ponack, L.L.P.
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