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
2002-10-04
2004-10-05
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
C430S907000, C526S242000, C526S247000, C526S281000, C526S320000, C526S346000, C526S334000, C526S326000
Reexamination Certificate
active
06800418
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a photosensitive polymer and a chemically amplified resist composition, and more particularly, to a fluorine-containing photosensitive polymer and a resist composition including the photosensitive polymer.
2. Description of the Related Art
As the manufacture of semiconductor devices becomes complicated and the integration density of semiconductor devices increases, there is a need to form a fine pattern. Furthermore, with regard to semiconductor devices of 1-Gigabit or greater, a pattern size having a design rule of 0.1 &mgr;m or less is needed. However, when a conventional photoresist material is exposed with KrF excimer laser (248 nm), there is a limitation in forming such fine patterns. For this reason, a lithography technique using a new exposure light source, ArF excimer laser (193 nm), has emerged, and the focus of the research on ArF resist compositions has been on acrylic polymers and COMAs (cycloolefin-maleic anhydrides).
For a smaller pattern size, there is extensive focus on lithography using short-wavelength generating F
2
(157 nm) excimer laser. Conventional KrF or ArF resists are unsuitable for use with the short-wavelength source of 157 nm due to their low transmittance. Therefore, a polymer with a novel structure which is transparent to a157-nm wavelength is more suitable. A chemical component dissolvable in developer includes phenol, carboxylic acid, &agr;-fluorocarbon-substituted alcohol, and hydroxy silane having a structure of formula 1 below:
Among these components, phenol and carboxylic acid have a very poor transmittance with respect to 157-nm beam. Whereas &agr;-fluorocarbon-substituted methanol and hydroxy silane are relatively more transparent at a wavelength of 157-nm. As a result, interest in studying &agr;-fluorocarbon-substituted methanol and hydroxy silane has increased.
According to recent research data, appropriate substitution of a phenolic or carboxylic derivative with fluorine is found to be effective for transmittance and contrast enhancement, suggesting its use as a polymer for a 157-nm exposure source (
Journal of Photopolymer Science and Technology,
Vol. 14, No. 4, 583-593, 2001;
Journal of Photopolymer Science and Technology,
Vol. 14, No. 4, 669-674, 2001).
Structures of fluorine-substituted photosensitive polymers for conventional resist compositions are shown in formula 2 below.
Despite the existence of the ether group in those structures of formula 2 above, advantages of a high transmittance due to the acrylate polymer and of their ease of preparation has increased use of those structures substituted with fluorocarbon to an appropriate degree. t-butyl trifluoromethyl acrylate is widely used as a monomer for enhancing contrast. An aromatic hydrocarbon monomer having a low transmittance at 157-nm can be changed into a hexafluoroisopropanol-substituted styrene structure with enhanced transmittance to be suitable as a resist material.
In addition, extensive research into resist compositions derived from acrylate polymers, non-carboxylic fluorinated vinyl ether polymers, and polymers with cyclic ether in their main chain, and copolymers of tetrafluoroethylene and norbornene derivatives known to be highly transparent at 157-nm, having structures of formula 3 below, are in progress.
In formula 3 above, R may be a methyl group, a t-butyl group, an adamantly group, a trifluoromethylnorbornyl group, or a hexafluoroisopropyl group.
A fluorinated polymer has excellent transmittance at 157-nm when it contains more fluorine atoms, but its enhanced hydrophobicity degrades adhesion to an underlayer. To date, resist materials having a suitable structure for 157-nm laser have not been found. Therefore, there is a need for a polymer having a high transmittance at 157-nm and without the aforementioned problems and thus be suitable as a resist material for F
2
excimer laser.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a photosensitive polymer having a structure to give a high transmittance at a F
2
excimer laser wavelength of 157 nm and good adhesion to an underlayer.
It is another object of the present invention to provide a resist composition allowing development with conventional developers and having a high transmittance at a F
2
excimer laser wavelength of 157 nm, good hydrophilicity, and good adhesion to an underlayer.
According to an aspect of the present invention, a photosensitive polymer is provided having an average molecular weight of about 3,000-100,000 with a repeating unit including a group of one of the structures of formula 4 below:
In the photosensitive polymer, the repeating unit may have a structure of formula 5 below:
where n is 0 or 1, and R
1
is a substituted or unsubstituted C
1
-C
5
hydrocarbon group.
The repeating unit of formula 5 above may be derived from a monomer of formula 6 below:
Alternatively, the repeating unit constituting the photosensitive polymer according to an embodiment of the present invention may have a structure of formula 7 below:
where n is 0 or 1, and R
2
is a substituted or unsubstituted C
1
-C
5
hydrocarbon group.
The repeating unit of formula 7 above may be derived from a monomer of formula 8 below:
Alternatively, the repeating unit constituting the photosensitive polymer according to an embodiment of the present invention may have a structure of formula 9 below:
where n is 0 or 1, and R
3
is a substituted or unsubstituted C
1
-C
5
hydrocarbon group.
The repeating unit of formula 9 above may be derived from a monomer of formula 10 below:
Alternatively, the repeating unit constituting the photosensitive polymer according to an embodiment of the present invention may have a structure of formula 11 below:
where R
4
is a substituted or unsubstituted C
1
-C
5
hydrocarbon group.
The repeating unit of formula 11 above may be derived from a monomer of formula 12 below:
Alternatively, the repeating unit constituting the photosensitive polymer according to an embodiment of the present invention may have a structure of formula 13 below:
The repeating unit of formula 13 above may be derived from a monomer of formula 14 below:
According to a second embodiment of the present invention, a photosensitive polymer is provided having an average molecular weight of about 3,000-100,000 with a first repeating unit having one group of a structure selected from formula 4 above and at least one second repeating unit selected from the group consisting of acrylate, methacrylate, maleic anhydride, norbornene, styrene, tetrafluoroethylene, and sulfur dioxide derivatives.
Alternatively, the photosensitive polymer according to the second embodiment of the present invention may have a structure of formula 15 below:
where n is 0 or 1; R
1
is a substituted or unsubstituted C
1
-C
5
a hydrocarbon group; R
5
is hydrogen atom, a methyl group, or a trifluoromethyl group; R
6
is a hydrogen atom or a substituted or unsubstituted C
1
-C
20
hydrocarbon group; and R
7
is hydrogen atom, a hydroxyl group, a nitrile group, a substituted or unsubstituted C
1
-C
12
alkyl group, a fluorinated C
1
-C
12
alkyl group, an alkoxy group, or an ester group. Preferably, R
6
is a C
4
-C
12
acid-labile group, and more preferably, a t-butyl group. Preferably, R
7
is a fluorinated C
3
-C
12
alkyl alcohol group or an acid-labile C
4
-C
12
ester group. For example, R
7
may be a 2-hydroxyhexafluoroisopropyl group, a t-butoxycarbonyloxyhexafluoroisopropyl group, or a 2-hydroxytrifluoroisopropyl group.
Alternatively, the photosensitive polymer according to the second embodiment of the present invention may have a structure of formula 16 below:
where n is 0 or 1; R
2
is a substituted or unsubstituted C
1
-C
5
hydrocarbon group; R
5
a is hydrogen atom, a methyl group, or a trifluoromethyl group; R
6
is a hydrogen atom or a substituted or unsubstituted C
1
-C
20
hydrocarbon group; and R
8
is a hydrogen atom, a hydroxyl group, a nitrile group, a substituted or unsubstituted C
1
-C
12
alkyl group, a fluo
Choi Sang-jun
Song Ki-yong
Woo Sang-gyun
Yoon Kwang-sub
Ashton Rosemary
F. Chau & Associates
Samsung Electronics
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