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
2000-06-30
2001-11-13
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
C430S326000, C430S913000, C430S914000
Reexamination Certificate
active
06316159
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a chemical amplified photoresist composition. Especially relates to an improved lithographic chemical amplified photoresist composition and resin for using in the manufacture of integrated circuits.
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 polymer, which is adequate candidate for the photoresist for 193 nm lithography, is 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 composition of chemical amplified photoresist, which is applied in microlithography or 193 nm ArF lithography with high resolution, advantageous pattern and high sensitivity.
The present invention provides a chemical amplified photoresist composition, which comprises a photosensitive polymer containing the following structure unit of formula (II):
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.
The chemical amplified photoresist composition of the present invention is comprised of the photosensitive polymer containing the above structure unit of formula (II) as the major component and can be optionally mixed with photo-acid generator (PAG), acid quencher, additives and solvent.
The chemical amplified photoresist compositions of the present invention can be used in lithography, especially 193 nm lithography. The resolution, shape and sensitivity of the resist pattern formed from the photoresist composition of the present invention are excellent.
DETAILED DESCRIPTION OF THE INVENTION
The photosensitive polymer containing the structure unit of formula (II) can be prepared from the following formula (I) compound:
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.
Preferably, compound (I) is a monomer of polycycloalkyl acrylate which can be obtained from the of reaction of acryloyl chloride and tricycloalcohol or its derivatives.
Compound (I) can 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 polymers or copolymers polymerized or copolymerized from compound (I) contain the following structure unit of formula (II):
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.
The structure unit of the polymers or copolymers polymerized or copolymerized from compound (I) can be
The structure unit of the polymers or copolymers polymerized or copolymerized from compound (I) can be
in the above structure unit of formula (III), (IV), (VI), (VII) 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 are 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 photosensitive polymer containing the structure unit of formula (II) can combine with adequate photo-acid generator (PAG), acid quencher, additives or solvent to form chemical amplified photoresist compositions.
There is no special limit to photo-acid generators here. The acid created by UV illuminating will be allowed. The photo-acid generator suitable for the chemical amplified photoresist compositions of the present invention meet the requirement to maintain stable before exposure. Preferably, suitable photo-acid generator is
The chemical amplified photoresist composition of the present invention can further include acid scavengers to adjust the diffusion of acid. Suitable acid scavengers can be
The chemical amplified photoresist composition of the present invention can further include other additives to enhance the resistance of the resist surface to basic materials. In addition, surfactants can be added to the chemical amplified photoresist compositions of the present invention to improve characters of the coating formed from the compositions.
There is no special limit to the solvent of the chemical amplified photoresist compositions of the present invention. Preferably, the solvent suitable for the chemical amplified photoresist compositions of the present invention is higher alcohol (e.g. n-octanol), glycolic acid and its derivatives (e.g. methyl lactate, ethyl lactate and ethyl glycolate), glycollic ether and its derivatives (e.g. glycollic ethyl acetate, glycollic methyl acetate, glycerol methyl acetate), ketoesters (e.g. methyl acetoacetate, ethyl acetoacetate), alkoxy carboxylates (ethyl 2-ethoxyacetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, or methyl ethoxypropionate), ketones (methyl ethyl ketone, methyl pentyl ketone, acetylacetone cyclopentone, cyclohexone, or 2-hepatone) ketoethers (e.g. diacetoalcohol methyl ether), ketoalcohols (e.g. acetoalcohol or diacetone ), alcohol ethers (e.g. glycollic butyl ether or propylene glycol ethyl ether)amides (e.g. dimethylacetamide or dimethyl formamide), ethers (e.g. phenyl ether or triethylene glycol dimethyl ether) or mixture thereof. Preferably, the solvent of the chemical amp
Chang Shang-Wern
Li Yen-Cheng
Lin Shang-Ho
Ashton Rosemary
Bacon & Thomas
Everlight USA, Inc.
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