Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Reexamination Certificate
2001-06-05
2002-12-31
Trinh, Ba K. (Department: 1625)
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
C549S519000
Reexamination Certificate
active
06500971
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to novel ester compounds having alicyclic and oxirane structures which form polymers useful as a base resin to formulate a chemical amplification type resist composition adapted for microfabrication, and a method for preparing the same.
2. Prior Art
While a number of recent efforts are being made to achieve a finer pattern rule in the drive for higher integration and operating speeds in LSI devices, deep-ultraviolet lithography is thought to hold particular promise as the next generation in microfabrication technology. In particular, photolithography using a KrF or ArF excimer laser as the light source is strongly desired to reach the practical level as the micropatterning technique capable of achieving a feature size of 0.3 &mgr;m or less.
The resist materials for use in photolithography using light of an excimer laser, especially ArF excimer laser having a wavelength of 193 nm, are, of course, required to have a high transmittance to light of that wavelength. In addition, they are required to have an etching resistance sufficient to allow for film thickness reduction, a high sensitivity sufficient to eliminate any extra burden on the expensive optical material, and especially, a high resolution sufficient to form a precise micropattern. To meet these requirements, it is crucial to develop a base resin having a high transparency, rigidity and reactivity. None of the currently available polymers satisfy all of these requirements. Practically acceptable resist materials are not yet available.
Known high transparency resins include copolymers of acrylic or methacrylic acid derivatives and polymers containing in the backbone alicyclic compounds derived from norbornene derivatives. All these resins are unsatisfactory. For example, copolymers of acrylic or methacrylic acid derivatives are relatively easy to increase reactivity in that highly reactive monomers can be introduced and acid labile units can be increased as desired, but difficult to increase rigidity because of their backbone structure. On the other hand, the polymers containing alicyclic compounds in the backbone have rigidity within the acceptable range, but are less reactive with acid than poly(meth)acrylate because of their backbone structure, and difficult to increase reactivity because of the low flexibility of polymerization. Additionally, since the backbone is highly hydrophobic, these polymers are less adherent to substrates. Therefore, some resist compositions which are formulated using these polymers as the base resin fail to withstand etching although they have satisfactory sensitivity and resolution. Some other resist compositions are highly resistant to etching, but have low sensitivity and low resolution below the practically acceptable level.
SUMMARY OF THE INVENTION
An object of the invention is to provide a novel ester compound having alicyclic and oxirane structures useful as a monomer to form a polymer for use in the formulation of a photoresist composition which exhibits improved adhesion and transparency when processed by photolithography using light with a wavelength of less than 300 nm, especially ArF excimer laser light as the light source. Another object is to provide a method for preparing the ester compound.
We have found that ester compounds of the general formula (1) can be prepared in high yields by a simple process to be described later; that a polymer obtained using the ester compound has high transparency at the exposure wavelength of an excimer laser; and that a resist composition using the polymer as a base resin is fully adherent.
In one aspect, the invention provides an ester compound of the following general formula (1).
Herein R
1
is hydrogen or methyl, R
2
is a tertiary alkyl group of 4 to 20 carbon atoms, and k is 0 or 1.
Preferably the ester compound of formula (1) is represented by the following general formula (2) or (3).
Herein R
1
is hydrogen or methyl, R
3
, R
4
, R
5
, and R
6
are independently straight, branched or cyclic alkyl groups of 1 to 15 carbon atoms, and Z is a divalent hydrocarbon group of 4 to 15 carbon atoms which forms a ring with the carbon atom to which it is connected at both ends.
From a process aspect, the ester compound of the general formula (1) is prepared by effecting Darzen's reaction between a carbonyl compound of the following general formula (4) and a haloacetate compound of the following general formula (5) in the presence of a base according to the following reaction scheme.
Herein R
1
, R
2
and k are as defined above and X is a chlorine or bromine atom.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The ester compounds of the invention are of the following general formula (1).
Herein R
1
is hydrogen or methyl, R
2
is a tertiary alkyl group of 4 to 20 carbon atoms, and k is 0 or 1.
As the partial structure OR
2
, those of the following general formulas are preferred.
Herein R
3
, R
4
, R
5
, and R
6
are independently straight, branched or cyclic alkyl groups of 1 to 15 carbon atoms. Z is a divalent hydrocarbon group of 4 to 15 carbon atoms such as a straight, branched or cyclic alkylene or alkenylene group, which forms a ring with the carbon atom to which it is connected at opposite ends.
Examples of the C
1-15
alkyl groups represented by R
3
, R
4
, R
5
, and R
6
include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, cyclopentyl, cyclohexyl, methylcyclopentyl, ethylcyclopentyl, methylcyclohexyl, ethylcyclohexyl, bicyclo[2.2.1]heptyl, bicyclo[2.2.2]octyl, bicyclo[3.3.1]-nonyl, bicyclo[4.4.0]decanyl, tricyclo[5.2.1.0
2,6
]decanyl, tetracyclo[4.4.0.1
2,5
.1
7,10
]dodecanyl, and adamantyl. Examples of the rings that the divalent hydrocarbon group Z forms with the carbon atom include cyclopentane, cyclopentene, cyclohexane, cyclohexene, bicyclo[2.2.1]heptane, bicyclo[4.4.0]decane, tricyclo[5.2.1.0
2,6
]decane, tetracyclo[4.4.0.1
2,5
.1
7,10
]dodecane, and adamantane.
Of the ester compounds of formula (1), preferred are those of the following general formula (2) or (3).
Herein R
1
, R
3
, R
4
, R
5
, R
6
and Z are as defined above.
Illustrative, non-limiting, examples of the ester compounds of the formula (1) and especially formula (2) or (3) include those of the following structures.
The ester compound of the invention can be synthesized, for example, by effecting Darzen's reaction, also known as Darzen's condensation, between a carbonyl compound of the following general formula (4) and a haloacetate compound of the following general formula (5) in the presence of a base according to the following reaction scheme.
Herein R
1
, R
2
and k are as defined above and X is a chlorine or bromine atom.
The bases used herein include metal amides such as sodium amide, potassium amide, lithium diisopropylamide, potassium diisopropylamide, lithium dicyclohexylamide, potassium dicyclohexylamide, lithium 2,2,6,6-tetramethyl-piperidine, lithium bistrimethylsilylamide, sodium bistrimethylsilylamide, potassium bistrimethylsilylamide, lithium isopropylcyclohexylamide, and bromomagnesium diisopropylamide: alkoxides such as sodium methoxide, sodium ethoxide, lithium methoxide, lithium ethoxide, lithium tert-butoxide, and potassium tert-butoxide; inorganic hydroxides such as sodium hydroxide, lithium hydroxide, potassium hydroxide, barium hydroxide, and tetra-n-butylammonium hydroxide; inorganic carbonates such as sodium carbonate, sodium hydrogen carbonate, lithium carbonate and potassium carbonate; metal hydrides such as sodium hydride, lithium hydride, potassium hydride, and calcium hydride; and alkyl metal compounds such as trityl lithium, trityl sodium, trityl potassium, methyl lithium, phenyl lithium, sec-butyl lithium, tert-butyl lithium, and ethyl magnesium bromide, but are not limited thereto.
Upon reaction, the molar ratio of the compounds of formulas (4) and (5) may be selected as appropriate although
Hasegawa Koji
Hatakeyama Jun
Kinsho Takeshi
Nakashima Mutsuo
Nishi Tsunehiro
Millen White Zelano & Branigan P.C.
Shin-Etsu Chemical Co. , Ltd.
Trinh Ba K.
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