Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Reexamination Certificate
2001-07-05
2002-10-29
Owens, Amelia (Department: 1625)
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
C549S326000
Reexamination Certificate
active
06472543
ABSTRACT:
This invention relates to novel lactone compounds useful as monomers to form base resins for use in chemically amplified resist compositions adapted for micropatterning lithography, and methods for preparing the same.
BACKGROUND OF THE INVENTION
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 an alicyclic compound derived from a norbornene derivative. 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 an alicyclic compound 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 freedom of polymerization. Additionally, since the backbone is highly hydrophobic, these polymers are less adherent when applied 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 lactone compound useful as a monomer to form a polymer for use in the formulation of a photoresist composition which exhibits firm adhesion and high 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 lactone compound.
We have found that a lactone compound of formula (1) can be prepared in high yields by a simple method to be described later, that a polymer obtained from this lactone compound has high transparency at the exposure wavelength of an excimer laser, and that a resist composition comprising the polymer as a base resin is improved in adhesion to substrates.
In one aspect, the invention provides a lactone compound of the following general formula (1).
Herein, k is 0 or 1 and m is an integer of 1 to 8.
In another aspect, the invention provides methods for preparing the lactone compound of formula (1).
A first method for preparing a lactone compound of formula (1) according to the invention involves the steps of reacting an oxirane compound of the following general formula (2) with a metallomalonate to form a hydroxy diester compound of the following general formula (3), followed by hydrolysis, decarboxylation and lactonization.
Herein, k and m are as defined above, R is alkyl such as methyl, ethyl or t-butyl, M is Li, Na, K, MgY or ZnY, and Y is halogen.
A second method for preparing a lactone compound of formula (1) according to the invention involves the steps of reacting an organometallic compound of the following general formula (4) with a 3-alkoxycarbonylpropionyl chloride to form a keto ester compound of the following general formula (5), followed by reduction and lactonization.
Herein, k, m, R and M are as defined above.
A third method for preparing a lactone compound of formula (1) according to the invention involves the steps of reacting an aldehyde compound of the following general formula (6) with lithium 3-lithiopropionate to form a hydroxycarboxylic acid compound of the following general formula (7), followed by lactonization.
Herein, k and m are as defined above.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The lactone compounds of the invention are of the following general formula (1).
Herein k is 0 or 1 and m is an integer of 1 to 8 (i.e., 1≦m≦8).
Illustrative examples of the lactone compound are given below.
It is believed that resist polymers obtained using these lactone compounds as the monomer exhibit good adhesion to substrates because the butyrolactone moiety regarded as a polar group that brings out adhesion is positioned at a site separated apart from the polymer backbone by an alkylene group. By selecting a lactone compound having an optimum alkylene chain as the monomer to form a polymer, the polymer as a whole can be adjusted to an appropriate compatibility and controlled in dissolution properties.
The lactone compounds of the invention can be produced by the following three methods, for example, but the invention is not limited to these methods.
The first method involves the steps of reacting an oxirane compound (2) with a metallomalonate to form a hydroxy diester compound (3), followed by hydrolysis, decarboxylation and lactonization, thereby producing the desired lactone compound (1).
Herein k and m are as defined above, R is an alkyl group such as methyl, ethyl or t-butyl, M is Li, Na, K, MgY or ZnY, and Y is a halogen atom.
The first step is to add a metallomalonate, prepared by a conventional method, to an oxirane compound (2) to form a hydroxy diester compound (3).
Ring opening of the oxirane ring occurs preferentially from the desired methylene terminal side over the sterically hindered methine side. The amount of metallomalonate used is preferably 0.9 to 3 mol, more preferably 1.0 to 1.8 mol per mol of the oxirane compound. Depending on reaction conditions, a solvent may be selected from ethers such as tetrahydrofuran, diethyl ether, di-n-butyl ether and 1,4-dioxane, hydrocarbons such as n-hexane, n-heptane, benzene, toluene, xylene and cumene, alcohols such as methanol, ethanol, isopropyl alcohol and tert-butyl alcohol, and polar aprotic solvents such as dimethyl sulfoxide and N,N-dimethylformamide, alone or in admixture of any. The reaction temperature and time vary over a wide range. In one example wherein sodium anions which are prepared from malonate and sodium alkoxide in dry alcohol are used as a reagent, the reaction temperature preferred for rapidly driving the reaction to completion is from room temperature to the reflux temperature, and especially from 50° C. to the reflux temperature. The reaction time is desirably determined by monitoring the reaction until the completion by gas chromatography (GC) or silica gel thin-layer chromatography (TLC) because higher yields are expectable. The reaction time is usually about 1 to about 20 hours. From the reaction mixture, the hydroxy diester compound (3) is obtained by a conventional aqueous work-up procedure. If necessary, the compound (3) may be purified by any conventional technique such as distillation, chromatography or recrystallization. Often the crude product has a sufficient purity as a substrate for the subsequen
Hasegawa Koji
Hatakeyama Jun
Kinsho Takeshi
Nakashima Mutsuo
Nishi Tsunehiro
Millen White Zelano & Branigan P.C.
Shin-Etsu Chemical Co. , Ltd.
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