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
1999-04-21
2004-10-19
Thornton, Yvette C. (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
C430S286100, C430S281100
Reexamination Certificate
active
06806022
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a positive photosensitive resin composition used in a production process of semiconductor devices, such as IC, production of circuit substrates for liquid crystal, thermal head and the like, and other photo-fabrication processes. To mention in detail, the invention is concerned with a positive photosensitive resin composition used appropriately for producing semiconductor elements by means of micro-lithography utilizing energy beams of short wavelengths, such as far ultraviolet rays, X-rays and electron beams. In particular, the invention relates to a positive photosensitive resin composition used advantageously for producing semiconductor elements by means of micro-lithography utilizing ArF excimer laser.
BACKGROUND OF THE INVENTION
In recent years the research and development for raising the integration degree of semiconductor integrated circuits has made rapid progress and, with the practical use of LSI and VLSI, the minimum pattern width of integrated circuits has reached the level of a sub-half micron. Further, the patterns are being fined.
Under these circumstances, requirements for photo-lithographic technology applied to fine pattern formation have become severer and severer. As one of means to aim at fining patterns, it is known to select light of shorter wavelengths as the exposure light for forming resist patterns.
For instance, in the production of DRAM having an integration degree up to 64 Mega-bit, i-ray (365 nm) of a high-pressure mercury lamp has so far been used as light source. In the mass production of 256 Mega-bit DRAM, KrF excimer laser (248 nm) has been put to practical use as a light source instead of i-ray. Further, light sources of shorter wavelengths have been investigated for the purpose of producing DRAM with an integration degree of 1 Giga-bit or above, and thereby the utilization of ArF excimer laser (193 nm), F
2
excimer laser (157 nm), X-rays and electron beams has been considered effective (Takumi Ueno et al.,
Short-wavelength Photoresist Materials—Micro-lithography for ULSI
, Bunshin Shuppan (1988)).
In particular, ArF excimer laser is evaluated as the light source for exposure arts in the next generation, and so it is desired to develop resist materials which are suitable for exposure to ArF excimer laser and can ensure high sensitivity, high resolution and excellent dry etching resistance.
As conventional resist materials for exposure to i-ray and KrF excimer laser, the resist materials containing aromatic polymers have widely been used with the intention of ensuring high dry etching resistance. For instance, there are known novolak resin resist and chemically amplified resist of polyvinylphenol type. However, the aromatic rings introduced for the purpose of conferring dry etching resistance on resist hardly transmit light in the wavelength region of ArF excimer laser, so that it is difficult for the light to arrive at the bottom of resist film. Therefore, the conventional resist materials cannot form patterns having satisfactory profile.
As a solution to a problem concerning the transparency of resist, the use of aromatic ring-free aliphatic polymers, such as polymethyl methacrylate, is known to be acceptable (
J. Vac. Sci. Technol
., B9, 3357 (1991)). However, such polymers are not practicable because sufficient dry etching resistance can hardly be expected therefrom. The greatest problem which confronts the development of resist materials for exposure to ArF excimer laser is to ensure both improved transparency and high dry etching resistance in the resist film.
So it was reported in
Proc. SPIE
, 1672, 66 (1992) that the resist materials containing alicyclic hydrocarbon groups instead of aromatic groups showed dry etching resistance similar to those containing aromatic groups and had weak absorption at 193 nm. As a result, the utilization of such polymers has energetically been studied in recent years.
Originally, the application of polymers containing alicyclic hydrocarbon groups to resist materials has been attempted from of old. For instance, the norbornene polymers are disclosed in JP-A-60-195542, JP-A-1-217453 and JP-A-2-59751 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”), and various alkali-soluble resins having cyclic aliphatic hydrocarbon skeletones and maleic anhydride units are disclosed in JP-A-2-146045.
Further, the copolymers of norbornene and acrylates protected by acid decomposable groups are disclosed in JP-A-5-80515, the copolymers having adamantane skeletons in side chains are disclosed in JP-A-4-39665, JP-A-5-265212, JP-A-5-80515 and JP-A-7-234511, the polymers having side chains to which are attached C
7
-C
12
aliphatic cyclic hydrocarbon groups containing bridged cyclic hydrocarbon groups, such as tricyclo[5,2,1,02,6]decanedimethylene group, tricyclo-[5,2,1,02,6]decanediyl group, norbornanediyl group, norbornanedimethyl group and adamantanediyl group, are disclosed in JP-A-7-252324 and JP-A-9-221526, and the polymers having side chains to which are attached tricyclodecanyl groups, dicylopentenyl groups, docyclopentenyloxyethyl groups, norbornyl groups or cyclohexyl groups are disclosed in JP-A-7-199467.
Furthermore, the polymers having cyclohexane and isobornyl skeletons in their main chains are disclosed in JP-A-9-325498, the polymers having main chains wherein are introduced various cyclic olefins, e.g., dicycloolefin, are disclosed in JP-A-9-230595, JP-A-9-244247, JP-A-10-10739, WO 97-33198, and European Patents 794,458 and 789,278. In addition, JP-A-8-82925 and JP-A-9-230597 disclose that the compounds having menthyl or menthyl derivative groups are preferable to the compounds having other terpenoid skeletons.
Separately from the aforementioned problem concerning resist properties, the generation of defects (voids) attributable to lithographic processes constitutes a major factor in lowering a yield, which has been a recent big problem to be tackled.
The development defects, for instance, are said to be attributable to air bubbles generated at the time of serving a developer and micro bubbles due to the gas dissolved in a developer (Hirano et al., The 42th Applied Physical Society Symposium 27p-ZW-9 (1996)). With the increase in diameter of wafers and amount of a developer jetted out, the air bubble-control measure becomes a matter of greater importance. As measures to prevent air bubbles, it has been attempted to improve an apparatus so as to softly jet out a developer (See a book, entitled “Contamination Control Techniques for ULSI Production”, p. 41, published by Science Forum Co. (1992)) and to reduce air bubbles by addition of a degassing mechanism for dissolved gas. However, these measures are not successful in reducing the defects to a satisfactory level.
As other measures to reduce development defects, the addition of a nonionic surfactant to a developer has been devised for improving the wettability of a developer to promote the release of air bubbles, and the affinity improvement has been attempted by finding out the most appropriate species and addition amount for the surfactant used in novolak resist (Hakushima et al., The 42th Applied Physical Society Symposium 27p-ZW-7 (1996)).
However, these measures are insufficient for the reduction of development defects in nonaromatic polymer-utilized ArF laser resist of chemical amplification type; on the contrary, they sometimes have adverse effect thereon. Therefore, no guidelines on what measure to take for reduction of development defects have been drawn up yet. In addition, raising the affinity of resist with the intention of reducing development defects tends to cause deterioration in residual film rate and profile, so that it is very difficult to ensure both reduced development defects and high quality of resist patterns.
Further, as reported by, e.g.,
Proc. SPIE
, 1672, 46 (1992),
Proc, SPIE
, 2438, 551 (1995),
Proc. SPIE
, 2438, 563 (1995),
Proc, SPIE
, 1925, 14 (1993),
J. Photopolym. Sci. Tech
., vol. 8, No. 4, 535 (1995
Aoai Toshiaki
Kawabe Yasumasa
Sato Kenichiro
Fuji Photo Film Co. , Ltd.
Sughrue & Mion, PLLC
Thornton Yvette C.
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