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
2002-12-12
2004-05-11
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
C430S905000, C430S907000
Reexamination Certificate
active
06733952
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a novel resist composition containing a fluoropolymer. More particularly, it relates to a resist composition which is useful as a chemical amplification type resist useful for fine processing employing various light beams, such as far ultraviolet rays such as KrF laser or ArF laser, vacuum ultraviolet rays such as F
2
laser or X-rays.
BACKGROUND ART
In recent years, along with the progress in fine circuit patterns in the process for producing semiconductor integrated circuits, a photoresist material having high resolution and high sensitivity is desired. As the circuit patterns become fine, a short wavelength of a light source for an exposure apparatus becomes essential. In an application to lithography employing an excimer laser of 250 nm or shorter, a polyvinyl phenol type resin, an alicyclic acrylic type resin or a polynorbornane type resin has, for example, been proposed, but no adequate resolution and sensitivity have been obtained.
It is an object of the present invention to provide a resist composition which is particularly excellent in transparency to light beams and dry etching properties, as a chemical amplification type resist and which gives a resist pattern excellent in sensitivity, resolution, evenness, heat resistance, etc.
DISCLOSURE OF THE INVENTION
The present invention is the following invention which has been made to solve the above-described problems.
A resist composition which comprises a fluoropolymer (A) comprising monomer units (a) of a fluorovinyl monomer having —CF
2
—OR (wherein R is a C
1-10
alkyl group) and monomer units (b) of an alicyclic ethylenic monomer, an acid-generating compound (B) which generates an acid upon irradiation with light, and an organic solvent (C).
BEST MODE FOR CARRYING OUT THE INVENTION
Now, the composition of the present invention will be described in detail.
The fluoropolymer (A) comprising, as essential components, monomer units (a) of a fluorovinyl monomer having —CF
2
—OR and monomer units (b) of an alicyclic ethylenic monomer (hereinafter, monomers forming the respective monomer units will be referred to as (fluoro)monomer (a) and monomer (b), respectively).
The fluoromonomer (a) is a compound having an addition-polymerizable ethylenic double bond and preferably has fluorine atoms other than the fluorine atoms in —CF
2
—OR. —CF
2
—OR may be bonded to a carbon atom of the ethylenic double bond, but is preferably bonded to a carbon atom other than the carbon atom of the ethylenic double bond. Further, the ethylenic double bond is preferably an ethylenic double bond having fluorine atoms bonded, as represented by CF
2
═C.
The fluoromonomer (a) is preferably a compound represented by the following formula (1):
CF
2
═CF(O)
n
(CF
2
)
m
OR (1)
(wherein n is 0 or 1, m is an integer of from 1 to 5, and R is a C
1-10
alkyl group).
The fluoromonomer (a) represented by the formula (1) is more preferably a compound wherein n is 0 or 1, m is from 1 to 3, and R is a C
1-3
alkyl group. As the fluoromonomer (a), a fluoroalkene such as CF
2
═CFCF
2
OCH
3
, CF
2
═CFCF
2
OC
2
H
5
, CF
2
═CFCF
2
OC
3
H
7
, CF
2
═CFCF
2
CF
2
OCH
3
, CF
2
═CFCF
2
CF
2
OC
2
H
5
or CF
2
═CFCF
2
CF
2
OC
3
H
7
, and a fluorovinyl ether such as CF
2
═CFOCF
2
CF
2
OCH
3
, CF
2
═CFOCF
2
CF
2
OC
2
H
5
or CF
2
═CFOCF
2
CF
2
OC
3
H
7
may, for example, be specifically mentioned. These monomers may be used alone or in combination as a mixture of two or more of them.
Further, a monomer such as CF
2
═CFCF
2
OR can be synthesized by a reaction of a perfluoroallyl halide with a metal alkoxide (I. L. Knunyants et al, Chem. Abs., 52, 251(1958)).
Further, a monomer such as CF
2
═CFO(CF
2
)
m
OR can be synthesized by reacting the corresponding acid fluoride with hexafluoropropylene oxide, followed by pyrolysis (U.S. Pat. No. 4,358,412).
The alicyclic ethylenic monomer (b) is an alicyclic hydrocarbon having an addition-polymerizable ethylenic double bond. Some of the carbon atoms constituting the ring of the alicyclic hydrocarbon may be substituted by a bivalent atom such as an oxygen atom or a bivalent group such as —NH—. The ethylenic double bond may be present in the alicyclic ring or may be present outside of the alicyclic ring, or such double bonds may be present in the ring and outside the ring (usually, any one of the ethylenic double bonds would be involved in the polymerization reaction). Further, the alicyclic ring may be a single ring, a condensed polycyclic ring or any other ring. Further, the monomer (b) may have fluorine atoms or may have fluorine atoms, other hetero atoms or substituents. In a case where the monomer (b) has fluorine atoms, the monomer (b) is a compound which does not have the above-described —CF
2
—OR.
One of the monomers (b) is a monomer having an ethylenic double bond on at least one carbon atom constituting the alicyclic ring. Namely, it is a monomer having an ethylenic double bond between the adjacent carbon atoms among the carbon atoms constituting the alicyclic ring (a monomer having an ethylenic double bond in the alicyclic ring) or a monomer having an ethylenic double bond between a carbon atom constituting the alicyclic ring and a carbon atom outside of the alicyclic ring. In the monomer having an ethylenic double bond in the alicyclic ring, it may have two or more ethylenic double bonds in the alicyclic ring. The former monomer may, for example, be a cycloalkene or a bicycloalkene, and the latter monomer may, for example, be a monomer represented by the after-mentioned formula (3).
Another one of the monomers (b) is a monomer having an ethylenic double bond outside the alicyclic ring. It may, for example, be a cycloalkane, a bicycloalkane or a tricycloalkane having a vinyl group, a vinyloxy group, an allyl group or the like bonded thereto.
The following compounds may, for example, be mentioned as specific alicyclic ethylenic monomers (b). Vinyl cyclohexane, vinyl adamantane, vinyl norbornanes, vinyl bicyclooctane, cyclohexyl vinyl ether, adamantyl vinyl ethers, norbornyl vinyl ethers, bicyclooctyl vinyl ethers, norbornenes, norbornadienes, a compound represented by the following formula (2), and a compound represented by the following formula (3).
—CF
2
—OR in the fluoropolymer (A) will be cleaved under an acidic condition and will be converted to the corresponding ester group or an acid fluoride group. The ester group or the acid fluoride group will react with an alkaline aqueous solution (a developer) and will be converted to an alkali salt of a carboxylic acid, whereby the polymer will be water-soluble. Namely, the fluoropolymer (A) exhibits a developability when it is coexistent with the acid-generating compound (B).
The molar ratio of the monomer units (a) to the monomer units (b) in the fluoropolymer (A) is preferably such that monomer units (a)/monomer units (b)=30 to 70/70 to 30. If the proportion of the monomer units (a) is smaller than this, the light transmittance and the developability tend to be low, and if the proportion of the monomer units (b) is smaller than this, the heat resistance and etching durability tend to be low.
The fluoropolymer (A) may contain monomer units of a copolymerizable monomer, preferably a radical polymerizable monomer, other than the monomer units (a) and the monomer units (b), within a range not to impair its properties. The proportion of such other monomer units is preferably at most 15 mol %, based on the total monomer units.
The molecular weight of the fluoropolymer (A) is not particularly limited so long as it can be uniformly dissolved in the after-mentioned organic solvent and can be uniformly coated on a substrate. However, its number average molecular weight as calculated as polystyrene is usually from 1,000 to 100,000, preferably from 2,000 to 20,000. If the number average molecular weight is less than 1,000, troubles are likely to result, such that the resulting resist pattern tends to be defective, the film remaining rate after the development ten
Kaneko Isamu
Kawaguchi Yasuhide
Kodama Shun-ichi
Okada Shinji
Takebe Yoko
Asahi Glass Company Limited
Ashton Rosemary
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