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
2002-02-20
2004-02-24
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
C430S905000, C430S907000, C430S910000, C430S914000, C430S919000, C430S920000, C430S921000, C430S925000, C430S325000, C430S326000, C549S263000, C549S265000, C549S295000, C549S323000, C526S270000
Reexamination Certificate
active
06696217
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a chemically amplified resist composition and, more particularly, to a monomer having a lactone group, and a polymer and a resist composition prepared using the monomer.
2. Description of the Related Art
As manufacturing processes of semiconductor devices become more complicated and as integration density of semiconductor devices increases, the need to be able to form fine patterns also increases. As an example, in semiconductor memory devices having 1-Gigabit or more storage capacity, a pattern size having a design rule of 0.2 &mgr;m or less is needed. However, when a conventional photoresist material is exposed with a KrF excimer laser (248 nm wavelength), there is a limitation to forming such fine patterns. For this reason, a lithography technique using a new exposure light source, an ArF excimer laser (193 nm wavelength), has emerged.
Almost all well-known ArF resist compositions contain (meth)acryl-based polymers. Among these polymers, a methacrylate copolymer having an alicyclic protecting group, which is expressed by the formula below, has been suggested (
J. Photopolym. Sci. Technol.,
9(3), pp. 509 (1996)).
This polymer has an adamantyl group, which contributes to enhancing resistance to dry etching, and a lactone group, which improves adhesiveness, in its methacrylate backbone. As a result, the resolution of the resist and the depth of focus has improved. However, resistance to dry etching is still weak, and serious line edge roughness is observed after line patterns are formed from the resist layer.
Another drawback of the polymer having the formula shown above is that the raw material used to synthesis the polymer is expensive. In particular, the manufacturing cost of a polymer having a lactone group, which is introduced to improve adhesiveness, is so high that its practical use as a resist is difficult. Therefore, there is a need for a new polymer capable of replacing costly polymers for practical use.
As an example of another conventional resist composition, a cycloolefin-maleic anhydride (COMA) alternating polymer having the following formula has been suggested (
J. Photopolym. Sci. Technol., Vol.
12(4), pp. 553 (1999), and U.S. Pat. No. 5,843,624)
In the production of copolymer, such as a COMA alternating polymer having the formula shown above, the production cost of raw materials is cheap, whereas yield of the polymer sharply decreases. In addition, the transmittance of the polymer is very low at a short wavelength region, for example at 193 nm. The synthetic polymers have in their backbone the alicyclic group, which shows prominent hydrophobicity, and as a result, adhesiveness to neighboring material layers is very poor.
To improve the resolution of resist layer, the polymer system must be charged with a polar group. In recent years, a technique of introducing a lactone group into a methacrylate monomer having an alicyclic protecting group, using the following alicyclic compounds with lactone group, has been suggested so as to enhance the resistance to dry etching (
Journal of Photopolymer. Science of Technology,
Vol. 13, No. 4 (2000), pp. 601-606, and Japanese Patent Publication No. P2000-26446A):
Unfortunately, yield of the monomer having the formula shown above is so low as to cause an increase in manufacturing cost.
SUMMARY OF THE INVENTION
A feature of an embodiment of the present invention is a photosensitive monomer comprising an adhesive lactone group having both a double bond capable of forming a polymer and a photosensitive group.
Another feature of an embodiment of the present invention is a photosensitive polymer having an adhesive lactone group in its backbone and comprising a photosensitive group.
Yet another feature of an embodiment of the present invention is to provide a resist composition that can be produced at low cost with improvements in terms of dry etching resistance, adhesiveness to underlying material layers, line edge roughness of line patterns, and contrast characteristic, which are essential to realize fine patterns.
In accordance with a first embodiment of the present invention, there is provided a photosensitive monomer including a methylene butyrolactone derivative represented by the following formula:
wherein R
1
is a hydrogen atom or alkyl group, R
2
is an acid-labile group, X is a hydrogen atom, or substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, and Y is a substituted or unsubstitued alkyl group or alicyclic hydrocarbon group having 1 to 20 carbon atoms.
Preferably, R
2
is a t-butyl, a tetrahydropyranyl, or a substituted or unsubstituted alicyclic hydrocarbon group having 6 to 20 carbon atoms.
When R
2
is an alicyclic hydrocarbon group, R
2
may be 1-methyl-1-cyclohexyl, 1-ethyl-1-cyclohexyl, 2-methyl-2-norbornyl, 2-ethyl-2-norbornyl, 2-methyl-2-isobornyl, 2-ethyl-2-isobornyl, 8-methyl-8-tricyclo[5.2.1.0
2,6
]decanyl, 8-ethyl-8-tricyclo[5.2.1.0
2,6
]decanyl, 2-methyl-2-adamantyl, 2-ethyl-2-adamantyl, 1-adamantyl-1-methylethyl, 2-methyl-2-fenchyl or 2-ethyl-2-fenchyl.
In the photosensitive monomer, Y is an alicyclic hydrocarbon group and represented by the following formula:
wherein R
1
, R
2
and X are as defined above.
In another aspect of the first embodiment of the present invention, there is provided a photosensitive monomer comprising a methylene butyrolactone derivative represented by the following formula:
wherein R
1
is a hydrogen atom or alkyl group and R
2
is an acid-labile group.
In accordance with a second embodiment of the present invention featuring a photosensitive polymer having an adhesive lactone group in its backbone and comprising a photosensitive group, there is provided a photosensitive polymer having the following formula:
wherein R
1
is a hydrogen atom or alkyl group, R
2
is an acid-labile group, X is a hydrogen atom, or substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, and Y is a substituted or unsubstitued alkyl group or alicyclic hydrocarbon group having 1 to 20 carbon atoms.
In accordance with another aspect of the second embodiment of the present invention, there is provided a photosensitive polymer having the following formula:
wherein R
1
and R
2
are as defined above.
In accordance with still another aspect of the second embodiment of the present invention, there is provided a photosensitive polymer including (a) a monomer unit represented by the following formula:
wherein R
1
is a hydrogen atom or alkyl group, R
2
is an acid-labile group, X is a hydrogen atom, or substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, and Y is a substituted or unsubstitued alkyl group or alicyclic hydrocarbon group having 1 to 20 carbon atoms, and (b) at least one comonomer unit selected from the group consisting of an acrylate or methacrylate monomer unit, a maleic anhydride monomer unit and a norbornene monomer unit.
In the second embodiment of the present invention, the comonomer unit may include an acrylate or methacrylate monomer unit, and the photosensitive polymer has the following formula:
wherein R
3
is a hydrogen atom or methyl group, R
4
is an acid-labile group, 0<m<1, 0<n<1 and m+n=1. Also, R
2
and R
4
are preferably independently t-butyl, tetrahydropyranyl, or substituted or unsubstituted alicyclic hydrocarbon group having 6 to 20 carbon atoms. Alternatively, R
2
and R
4
are preferably independently 1-methyl-1-cyclohexyl, 1-ethyl-1-cyclohexyl, 2-methyl-2-norbornyl, 2-ethyl-2-norbornyl, 2-methyl-2-isobornyl, 2-ethyl-2-isobornyl, 8-methyl-8-tricyclo[5.2.1.0
2,6
]decanyl, 8-ethyl-8-tricyclo[5.2.1.0
2,6
]decanyl, 2-methyl-2-adamantyl, 2-ethyl-2-adamantyl, 1-adamantyl-1-methylethyl, 2-methyl-2-fenchyl or 2-ethyl-2-fenchyl.
Moreover, in the second embodiment of the present invention, the comonomer unit may include a maleic anhydride monomer unit, and the photosensitive polymer has the following formula:
wherein 0<m<1, 0<p<1 and m+p=1.
Alternativ
Woo Sang-gyun
Yoon Kwang-sub
Baxter Janet
Lee Sin J.
Lee & Sterba, P.C.
Samsung Electronics Co,. Ltd.
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