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
2001-04-26
2003-05-20
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, C430S910000, C526S272000, C526S281000, C526S283000, C528S298000, C528S300000, C528S302000
Reexamination Certificate
active
06566038
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to (i) a polymer comprising units having an electron attractive group at a specific position, (ii) a resist composition comprising the polymer, having improved transparency and hence, a high resolution, and in particular, suitable as micropatterning material for VLSI fabrication, and (iii) a patterning process using the resist composition.
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, robustness 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 robustness because of their backbone structure. On the other hand, the polymers containing an alicyclic compound in the backbone have robustness 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 these resins are less transparent than poly(meth)acrylates, they tend to further exaggerate the shortage of reactivity. Therefore, for both poly(meth)acrylates and polymers containing an alicyclic compound in the backbone, 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 (i) a polymer featuring both robustness and transparency, (ii) a resist composition comprising the polymer, having a significantly higher sensitivity, resolution, and etching resistance than prior art resist compositions, and (iii) a patterning process using the resist composition.
It has been found that a polymer comprising units of formulas (1) and (2) to be defined below and having a weight average molecular weight of 1,000 to 500,000 has very high transparency owing to the inclusion of an electron attractive group at a specific position, and that a resist composition comprising the polymer has a significantly high sensitivity, resolution, and etching resistance and is thus quite useful in precise micropatterning.
In a first aspect, the invention provides a polymer comprising units of the following general formula (1) and units of the following general formula (2) and having a weight average molecular weight of 1,000 to 500,000.
Herein R
1
is hydrogen, methyl or CH
2
CO
2
R
3
, R
2
is hydrogen, methyl or CO
2
R
3
, R
3
is a straight, branched or cyclic alkyl group of 1 to 15 carbon atoms, R
4
is a halogen atom or an acyloxy, alkoxycarbonyloxy or alkylsulfonyloxy group of 1 to 15 carbon atoms in which some or all of the hydrogen atoms on the constituent carbon atoms may be substituted with halogen atoms, R
5
is hydrogen or a straight, branched or cyclic alkyl group of 1 to 10 carbon atoms, R
6
is an acid labile group, Z is a single bond or a divalent straight, branched or cyclic hydrocarbon group of 1 to 10 carbon atoms, and k is 0 or 1. W is —O— or —(NR)— wherein R is hydrogen or a straight, branched or cyclic alkyl group of 1 to 15 carbon atoms.
Typical of the units of formula (1) are units of the following general formula (3) or (4).
Herein R
1
to R
5
, Z, and k are as defined above. R
7
to R
10
are independently selected from straight, branched or cyclic alkyl groups of 1 to 8 carbon atoms and substituted or unsubstituted aryl groups of 6 to 20 carbon atoms, and Y is a divalent hydrocarbon group of 4 to 15 carbon atoms which may contain a hetero atom and which forms a ring with the carbon atom to which it is connected at opposite ends.
The polymer may further include units of at least one of the following formulas (5) to (8).
Herein R
1
, R
2
and k are as defined above. At least one of R
11
to R
14
is a carboxyl or hydroxyl-containing monovalent hydrocarbon group of 1 to 15 carbon atoms, and the remainders are independently hydrogen or a straight, branched or cyclic alkyl group of 1 to 15 carbon atoms, or R
11
to R
14
, taken together, may form a ring, and when they form a ring, at least one of R
11
to R
14
is a carboxyl or hydroxyl-containing divalent hydrocarbon group of 1 to 15 carbon atoms, and the remainders are independently a single bond or a straight, branched or cyclic alkylene group of 1 to 15 carbon atoms. At least one of R
15
to R
18
is a monovalent hydrocarbon group of 2 to 15 carbon atoms containing a —CO
2
— partial structure, and the remainders are independently hydrogen or a straight, branched or cyclic alkyl group of 1 to 15 carbon atoms, or R
15
to R
18
, taken together, may form a ring, and when they form a ring, at least one of R
15
to R
18
is a divalent hydrocarbon group of 1 to 15 carbon atoms containing a —CO
2
— partial structure, and the remainders are independently a single bond or a straight, branched or cyclic alkylene group of 1 to 15 carbon atoms. R
19
is a polycyclic hydrocarbon group of 7 to 15 carbon atoms or an alkyl group containing such a polycyclic hydrocarbon group. R
20
is an acid labile group. X is —CH
2
— or —O—.
In a second aspect, the invention provides a resist composition comprising the polymer defined above.
In a third aspect, the invention provides a process for forming a resist pattern comprising the steps of applying the resist composition onto a substrate to form a coating; heat treating the coating and then exposing it to high-energy radiation or electron beams through a photo mask; and optionally heat treating the exposed coating and developing it with a developer.
In the units of formula (1), an electron attractive group has been introduced on the carbon atom adjoining the aliphatic ring that constitutes the backbone. The electron attractive group introduced alters the overall electron distribution and steric structure of the polymer and as a consequence, remarkably improves transparency for the reason which is unknown, and especially at the wavelength of 193 nm, to an equivalent level to poly(meth)acrylate. Accordingly, a resist composition using the polymer as a base resin eliminates the drawbacks of forward tapered shape and short-dissolution as found in prior art resist compositions, without detracting from the etching resistance and other advantages of a polymer containing an alicyclic compound in the backbone.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The polymer or high molecular weight compound
Hasegawa Koji
Hatakeyama Jun
Kinsho Takeshi
Nakashima Mutsuo
Nishi Tsunehiro
Baxter Janet
Millen White Zelano & Branigan P.C.
Shin-Etsu Chemical Co. , Ltd.
Thornton Yvette C.
LandOfFree
Polymers, resist compositions and patterning process does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Polymers, resist compositions and patterning process, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Polymers, resist compositions and patterning process will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3035598