Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acid esters
Reexamination Certificate
2000-06-30
2001-08-07
Gitomer, Ralph (Department: 1623)
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acid esters
C560S129000, C560S205000, C526S282000, C522S042000, C428S064200, C428S412000
Reexamination Certificate
active
06271412
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a novel compound. Especially relates to a photosensitive monomer.
BACKGROUND OF THE INVENTION
Current semiconductor industry trends indicate that availability of lithography below 0.18 &mgr;m is required for the development of high performance logic processors and 1-Gbit DRAM. In theory, there are two possible ways to get resist patterns with finer resolution, i.e. to shorten the wavelength of exposure light sources and to enlarge the numerical aperature (NA) of exposure systems.
KrF excimer laser (248 nm) steppers are widely used for the 0.25 &mgr;m UV lithography manufacturing process of semiconductor devices. Due to the improvement of optical elements such as high NA optical elements, phase shift mask, etc., the 248 nm KrF scanners now are capable of offering pilot run of 0.18 &mgr;m process and pioneer development of below 0.15 &mgr;m process. However, since there is a limit for wavelength shortening, the processing or manufacturing of finer masks becomes more and more difficult. To meet the urge demand of minimizing the size of IC devices, development of 193 nm (ArF excimer laser) lithography and resists are recognized as an alternative resolution recently.
Unfortunately, due to the strong absorption of aromatic rings that provides dry-etch resistance, the conventional chemical amplified resists based on phenol resin (248 nm) are totally opaque at 193 nm. To solve the problems, new polymers that exhibit low optical density at 193 nm are in great need now.
Generally speaking, the polymers which are adequate candidates for the photoresists for 193 nm lithography are required to meet six basic requirements:
(1) high transparency for 193 nm light source;
(2) good thermoplastic, ex. High glass transition temperature (Tg);
(3) high etch resistance;
(4) good adhesion and development for its composition;
(5) contained acid labile functional groups;
(6) be applied to general processes.
Recently, a tetrapolymer iBMA-MMA-tBMA-MMA (poly isobornyl methacrylate-methyl methacrylate-t-butyl methacrylate-methacrylic acid) is reported to be a possible resin system for ArF resist:
However, the tetrapolymer is also accompanied with undesirable adhesion and etch resistance. Therefore, a new resin for the compositions of resists is eager to be developed.
SUMMARY OF THE INVENTION
One object of the present invention is to provide a new monomer compound, which can be polymerized or copolymerized to be photosensitive polymers or copolymers.
The present invention provides a compound of the formula (I):
Wherein R is hydrogen or C
1
-C
4
alkyl group; R′ is C
1
-C
4
alkyl group; n is an integer of 2, 3, 4, 5 or 6.
Compounds of formula (I) can be copolymerized together with one or more vinyl monomers to form a photosensitive copolymer. The photosensitive copolymers can be used as components of chemical amplified photoresist compositions. The polymers or copolymers polymerized or copolymerized from compound (I) can be optionally mixed with photoacid generators, acid quenchers, additives or solvents to form photoresist compositions applied for general lithography process or 193 nm lithographic process.
DETAILED DESCRIPTION OF THE INVENTION
The compound of the present invention is a compound with formula (I):
wherein R represents H or alkyl group of C
1
-C
4
; R′ represents alkyl of C
1
-C
4
; n is an integer of 2, 3, 4, 5 or 6.
Preferably, compound (I) is a monomer of polycycloalkyl acrylate which can be obtained from the reaction of acryloyl chloride and tricycloalcohol or its derivatives.
Compound (I) can be polymerized to form polymers contain the following structure unit of formula (II):
wherein R, R′ and n are defined as the above.
Compound (I) also can be copolymerized with other vinyl monomers to form various copolymers with or without the assistance of catalysts.
There is no special limit for the application of the polymers or copolymers. However, if the polymers polymerized or copolymerized from compound (I) are expected to be transparent for the radiation with 193 nm wavelength, vinyl monomers free of aromatic rings are preferred.
Vinyl monomers suitable to copolymerized with compound (I) can be
The structure unit of the polymer or copolymers polymerized or copolymerized from compound (I) can be
in the above structure unit of formula (III) and (VIII) wherein g+h+i=1, more preferably g/(g+h+i)=0.1-0.5, h/(g+h+i)=0.1-0.5, and i/(g+h+i)=0.1-0.5; in the above structure unit of formula (V), wherein g+h+i+j=1, more preferably g/(g+h+i+j)=0.1-0.5, h/(g+h+i+j)=0.1-0.5, i/(g+h+i+j)=0.1-0.5, and j/(g+h+i+j)=0.1-0.5.
There is no special limit for the synthetical method of the polymers or copolymers from compound (I) of the present invention. Preferably, the polymerization or copolymerization of compound (I) or its mixture is initiated by initiators. Initiator used here can be any initiator used by the people who is skilled in the art. Preferably, the initiator is 2,2′-azo-bis-isobutyronitrile (AIBN) or dimethyl-2,2′-azo-bis-isobutyrate radical initiator (V-601).
The polymers or copolymers of present invention can combine with adequate photoacid generator (PAG), acid quencher, additives or solvent to form chemical amplified photoresist compositions.
The chemical amplified photoresist compositions of the present invention can be used in the process of lithography. Especially, the chemical amplified photoresist compositions of the present invention can be used in the process of 193 nm (ArF excimer laser) lithography.
REFERENCES:
patent: 4591626 (1986-05-01), Kawai et al.
patent: 4937118 (1990-06-01), Inagaki et al.
patent: 5318850 (1994-06-01), Pickett et al.
Landa et al., “Adamantane and derivatives. IX. The 2-substituted derivatives,” in Collect. Czech. Chem. Commun. (1967), 32(2), 570-5. (CA 1967:55094).
Chang Shang-Wern
Li Yen-Cheng
Lin Shang-Ho
Bacon & Thomas PLLC
Everlight USA, Inc.
Gitomer Ralph
Khare D.
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