Coating processes – Direct application of electrical – magnetic – wave – or... – Polymerization of coating utilizing direct application of...
Reexamination Certificate
2002-07-22
2004-06-08
Teskin, Fred (Department: 1713)
Coating processes
Direct application of electrical, magnetic, wave, or...
Polymerization of coating utilizing direct application of...
C427S553000, C427S554000, C427S555000, C522S002000, C522S031000, C522S152000, C522S914000, C526S248000, C526S262000, C548S549000
Reexamination Certificate
active
06746722
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for pattern formation wherein a fine pattern used in fields such as semiconductor device and the like is formed. The present invention relates also to a chemically amplified resist used in pattern formation, a polymer useful for obtaining this resist composition, and a novel compound as a raw material for the polymer.
2. Description of the Related Art
In production of various electronic devices represented by semiconductor device, requiring microfabrication of half-micron order, demands for higher integration density and higher integration level of such devices are growing. Therefore, the requirement for the photolithography used for fine pattern formation is becoming increasingly severe. In production of, in particular, a DRAM having an integration level of 1 G bits or more wherein a processing technique of 0.13 &mgr;m or less is required, a photolithography using an ArF excimer laser (193 nm) is going to be utilized. In formation of an even finer pattern, utilization of a photolithography using a F
2
excimer laser (157 nm) has been considered recently (R. R. Kunz et al., Journal of Vacuum Science and Technology, Vol. B17 (No. 6), pp. 3267-3272 (1999)).
Hence, it is desired to develop a resist material corresponding to the photolithography by F
2
excimer laser beam. In developing a resist to be exposed to the F
2
excimer laser beam, the cost performance of laser must be improved because the gas as a raw material for the laser has a short life and the laser equipment is expensive. Therefore, a high resolution corresponding to finer pattern forming and a high sensitivity are strongly required for the resist. As the method for allowing a resist to have a high sensitivity, it is well known to use a chemically amplified resist using a photo acid generator as a sensitizer. As a typical example of such a chemically amplified resist, there is described, in JP-B-2-27660, a resist consisting of a combination of triphenylsulfonium hexafluoroarsenate and a poly (p-tert-butoxycarbonyloxy-&agr;-methylstyrene). Such a chemically amplified resist is currently in wide use as a resist for KrF excimer laser (248 nm) (for example, Hiroshi Ito and C. Grant Wilson, American Chemical Society Symposium Series, Vol. 242, pp. 11-23 (1984)). The feature of the chemically amplified resist lies in that the photo acid generator contained as a component generates a protonic acid when exposed to a light and, in the heat treatment after light exposure, the acid gives rise to an acid-catalyzed reaction with the resist resin, etc. In this way is achieved a sensitivity far higher than those of conventional resists whose photoreaction efficiency (the reaction per one photon) are less than 1. Most of the resists developed recently are chemically amplified type.
In the lithography using a light having a short wavelength of 180 nm or less typified by a F
2
excimer laser beam, however, the resist used therein for formation of a fine pattern needs to have a new property not exhibited by conventional materials, i.e. a transparency to a light of 180 nm or less to be applied.
In conventional resist materials for KrF excimer laser and ArF excimer laser, there are mostly used, as the resin component, a poly(p-vinylphenol), an alicyclic resin, etc. These resins, however, show very strong absorption to a light of 180 nm or less wavelength. Therefore, the most part of the light applied is absorbed at the surface of such a resist and the light applied does not reach a substrate on which the resist is coated, making it impossible to form a fine resist pattern. For this reason, it is impossible to use a conventional resin in a photolithography using a light of short wavelength of 180 nm or less. Hence, a resist resin transparent to a wavelength of 180 nm or less is desired strongly.
As the polymer compound having transparency to a F
2
excimer laser beam (157 nm), fluorine-containing resins are considered to be promising (R. R. Kunz et al., Journal of Vacuum Science and Technology, Vol. B17 (No. 6), pp. 3267-3272 (1999), and T. M. Bloomstein et al., Journal of Vacuum Science and Technology, Vol. B16 (No. 6), pp. 3154-3157 (1998)).
Conventional fluorine-containing resins typified by polytetrafluoroethylene, however, have no functional group such as to give rise to a chemical reaction by the action of an acid, resulting in a change in solubility in alkali developing solution and further have no polar group (resultantly have low adhesivity to substrate); therefore, can not be used as a resin for chemically amplified resist.
Hence, a new resin material for resist usable in a lithography using a light of 180 nm or less is desired strongly.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a chemically amplified resist composition which can be suitably used in a lithography using a light of 180 nm or less wavelength, which enables formation of a fine pattern. It is also an object of the present invention to provide a polymer suitable for obtaining the above resist composition, a novel compound suitable as a raw material for the polymer, and a method for pattern formation capable of forming a fine pattern using the above resist composition.
The present invention lies in a fluorine-containing phenylmaleimide derivative represented by the general formula (1).
(In the formula (1), one of R
1
, R
2
, R
3
, R
4
and R
5
is a hydroxy group, an alkoxyl group, or an acid-dissociable organic group of 20 or less carbon atoms capable of generating a hydroxy group when decomposed by an acid; at least two of the remainder are each a fluorine atom; and when there is still a remainder, it is a hydrogen atom.)
The present invention lies also in a polymer characterized by being obtained by polymerizing monomers containing the above fluorine-containing phenylmaleimide derivative.
The present invention lies further in a polymer characterized by containing at least a structural unit represented by the general formula (2) and having a weight-average molecular weight of 2,000 to 200,000.
(In the formula (2), one of R
1
, R
2
, R
3
, R
4
and R
5
is a hydroxy group, an alkoxyl group, or an acid-dissociable organic group of 20 or less carbon atoms capable of generating a hydroxy group when decomposed by an acid; at least two of the remainder are each a fluorine atom; and when there is still a remainder, it is a hydrogen atom.)
Preferably, the polymer contains, in addition to the structural unit represented by the general formula (2), a structural unit represented by the following general formula (3).
(In the above formula, R
6
, R
7
, R
8
and R
9
are each independently a hydrogen atom, a fluorine atom, a trifluoromethyl group, a hydroxy group, a hydroxyalkyl group, a 1,1,1,3,3,3-hexafluoro-2-hydroxyisopropyl group, a 1,1,1-trifluoro-2-trifluoromethyl-2-hydroxypropyl group, an acid-dissociable organic group of 20 or less carbon atoms capable of generating a 1,1,1,3,3,3-hexafluoro-2-hydroxyisopropyl group when decomposed by an acid, an acid-dissociable organic group of 20 or less carbon atoms capable of generating a 1,1,1-trifluoro-2-trifluoromethyl-2-hydroxypropyl group when decomposed by an acid, or an acid-dissociable organic group of 20 or less carbon atoms capable of generating a carboxy group when decomposed by an acid.)
Preferably, these polymers are a copolymer which contains, in addition to the structural unit represented by the general formula (2), at least one kind of other structural unit and wherein the proportion of the structural unit represented by the general formula (2) in the total structural units of the copolymer is 5 to 90 mole %.
The present invention further includes a chemically amplified resist composition characterized by containing at least the above polymer and a photo acid generator capable of generating an acid when exposed to a light and also characterized in that the proportion of the polymer to the total mass of the polymer and the photo acid generator is 70 to 99.8% by mass and the proportion
Maeda Katsumi
Nakano Kaichiro
NEC Corporation
Teskin Fred
Young & Thompson
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