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
2002-05-29
2004-06-01
Schilling, Richard L. (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
C430S907000, C430S914000
Reexamination Certificate
active
06743565
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a positive resist composition (i.e., a positive-working positive resist composition) which is suitably used for the microlithography process at the production of VLSI (super LSI) or high-capacity microchip, or other photo-fabrication processes. More specifically, the present invention relates to a positive resist composition capable of forming a highly accurate pattern using vacuum ultraviolet light of 160 nm or less.
BACKGROUND OF THE INVENTION
The integration degree of integrated circuits is recently more and more increasing and in the production of a semiconductor substrate of VLSI or the like, an ultrafine pattern comprising lines having a width of quarter-micron or less must be processed. According to one known technique for achieving refinement of a pattern, a resist pattern is formed using an exposure light source having a shorter wavelength. This technique can be described using the following Rayleigh's formula showing the resolution (line width) R of an optical system:
R=k·&lgr;/NA
(wherein &lgr; is a wavelength of the exposure light source, NA is a numerical aperture of the lens and k is a process constant). As seen from this formula, a higher resolution, namely, a smaller R value can be obtained by reducing the wavelength &lgr; of the exposure light source.
For example, in the production of a semiconductor device having an integration degree up to 64 M bits, the i-line (365 nm) of a high-pressure mercury lamp is used at present as the light source. As for the positive resist capable of coping with this light source, a large number of compositions containing a novolak resin and a naphthoquinonediazide compound as the photosensitive material have been developed and these compositions are satisfactorily effective in the process of a line width up to about 0.3 &mgr;m. In the production of a semiconductor device having an integration degree of 256 M bits or more, a KrF excimer laser (248 nm) is used as the exposure light source in place of the i-line.
Furthermore, with an attempt to produce a semiconductor device having an integration degree of 1 G bits or more, use of an ArF excimer laser (193 nm) and for forming a pattern of 0.1 &mgr;m or less, use of an F
2
excimer laser (157 nm), which are a light source having a further shorter wavelength, are being studied.
In order to keep up with these light sources having a shorter wavelength, the constituent components of the resist material and the compound structure thereof are greatly changed. More specifically, the conventional resist containing a novolak resin and a naphthoquinone-diazide compound has a large absorption in the far ultraviolet region of 248 nm and light of sufficiently high intensity cannot reach the resist bottom, as a result, only a low-sensitive and tapered pattern can be obtained.
For solving this problem, a so-called chemical amplification-type resist has been developed. This is a composition mainly comprising a resin which has a basic skeleton of poly(hydroxystyrene) having small absorption in the region of 248 nm and is protected by an acid decomposable group, where a compound capable of generating an acid upon irradiation of far ultraviolet light (acid generator) is used in combination. The chemical amplification-type resist changes the solubility in a developer by the catalytic decomposition reaction of an acid generated in the exposed area and therefore, a high-sensitivity and high-resolution pattern can be formed.
The acid decomposable resin and the acid generator which can be effectively used in the chemical amplification-type resist are described in a large number of papers and patents such as
Polym. Eng. Sci.
, Vol. 23, page 1012 (1983),
ACS. Sym.
, Vol. 242, page 11 (1984),
Macromolecules
, Vol. 21, page 1475 (1988),
Yuki Gosei Kagaku Kyokai Shi
(
Journal of Organic Synthesis Chemistry Society
), Vol. 49, page 437 (1991),
Bisai Kako to Resist
(
Fine Working and Resist
), Kyoritsu Shuppan (1987). In the case of using ArF excimer laser light (193 nm), since the compound having an aromatic group substantially has large absorption in the wavelength region of 193 nm, even the above-described chemical amplification-type resist cannot provide a sufficiently high performance.
In order to solve this problem, the chemical amplification-type resist is improved by using an acid decomposable resin where an alicyclic structure having no absorption at 193 nm is introduced into the main or side chain of the polymer, in place of the acid decomposable resin having a basic skeleton of poly(hydroxystyrene).
This alicyclic structure-type acid decomposable resin is described, for example, in JP-A-4-39665 (the term “JP-A” as used herein means an “unexamined published Japanese patent application), JP-A-7-234511, JP-A-9-73173, JP-A-7-199467, JP-A-8-259626, JP-A-9-221519, JP-A-10-10739, JP-A-9-230595, JP-A-10-111569, JP-A-10-218947, JP-A-10-153864 and WO-97/33198.
It is, however, found that even this alicyclic structure-type resin has large absorption in the region of 157 nm and with an F
2
excimer laser light (157 nm), the objective pattern of 0.1 &mgr;m or less cannot be obtained. On the other hand, a resin where a fluorine atom (perfluoro structure) is introduced is reported to have high transparency to light at 157 nm (see,
Proc. SPIE.
, Vol. 3678, page 13 (1999)) and the structures of effective fluororesins are described in
Proc. SPIE.
, Vol. 3999, page 330 (2000), ibid., page 357 (2000), ibid., page 365 (2000) and WO-00/17712.
However, these resists having fluororesin are not sufficiently high in the dry etching resistance and also, due to their peculiar water repellency or oil repellency ascribable to the perfluoro structure, the coatability (uniformity of the coated surface) is in need of improvement. Furthermore, reduction in the development defect is demanded.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a positive(-working) resist composition suitable for use with an exposure light source of 160 nm or less, particularly, F
2
excimer laser light (157 nm). More specifically, the object of the present invention is to provide a positive(-working) resist composition capable of exhibiting sufficiently high transparency on use of a light source of 157 nm and also satisfying the requirements in regard to the coatability and development defect.
Another object of the present invention is to provide a positive(-working) resist composition capable of forming a pattern with good sensitivity and high resolution and exhibiting excellent dry etching resistance.
As a result of extensive investigations by taking notice of various properties described above, the present inventors have found that the objects of the present invention can be attained by the use of the following specific composition. The present invention has been accomplished based on this finding.
More specifically, the present invention has the following constructions.
(1) A positive resist composition comprising (A) a resin containing at least one repeating unit represented by the following formula (I) and at least one repeating unit represented by formula (VII), which decomposes under the action of an acid to increase the solubility in an alkali developer, and (B) a compound capable of generating an acid upon irradiation with actinic rays or radiation:
wherein R
1
represents a hydrogen atom, a halogen atom, a cyano group, an alkyl group which may have a substituent, or a haloalkyl group which may have a substituent; R
2
and R
3
, which may be the same or different, each represents a hydrogen atom, a hydroxyl group, a halogen atom, a cyano group, an alkoxy group, an acyl group, an alkyl group which may have a substituent, a cycloalkyl group which may have a substituent, an alkenyl group which may have a substituent, an aralkyl group which may have a substituent, or an aryl group which may have a substituent; and R
4
represents a hydrogen atom, an alkyl group which may have a substituent, a perfluoroalkyl group which may have a substi
Fujimori Toru
Kanna Shinichi
Mizutani Kazuyoshi
Fuji Photo Film Co. , Ltd.
Schilling Richard L.
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