Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Forming nonplanar surface
Reexamination Certificate
1998-09-22
2001-05-15
Duda, Kathleen (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Forming nonplanar surface
C430S329000, C430S330000, C430S942000
Reexamination Certificate
active
06232046
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to patterning of a three-dimensional surface using dry resist technology, and in particular, to a process for improving the contrast in the patterning produced using polymerizable dry resists having a high silicon dioxide content.
RELATED TECHNOLOGY
Efforts have been underway for quite some time to produce and employ radiation-sensitive coatings to be applied in dry processes.
Efforts have been disclosed for producing electron-sensitive polymerizates in the gas discharge, the applications for which remain undetermined. See
1. O. Joubet, T. Weidmann, A. Joshi, R. Cirelli, S. Stein, J. T. C. Lee, S. Vaidya: “Plasma polymerized all-dry resist process for 0.25 &mgr;m photolithography”, J. Vac. Technol. B 12(6)(1995), 3909.
At the Techno Center in Moscow, a substance has been synthesized as dry resist for corpuscular beam and optical lithography. This substance works with a sensitivity similar to that of the known electron resist PMMA (polymethacrylate), but as a negative resist. This resist has a poor contrast, and its resolution capability is only conditionally suitable for solids used in lithography. It is vapor-deposited under a vacuum and also dry-developed under a vacuum. See
Layers After Photon, Electron, and X-ray Exposures”, SPIE 1361 (1990) 999.
Wet process steps become superfluous. Therefore, the resist is very clean in terms of the environment. See
3. V. P. Korchkov, T. N. Martynova, V. S. Damlovich: “Thin Solid Films”, vol. 101, 1983, pp. 369-372.
The resist has a high etch resistance to metal-etching plasma processes and is, therefore, preferably used as a good etching mask.
SUMMARY OF THE INVENTION
It is the aim of the present invention to effect a better contrast of the dry resist and an improved resolving power on solids, enabling the dry resist to be used for optical lithography as well. This not only guarantees a clean process control, but also ensures that no substances harmful to the environment or deleterious to health is released in the process.
The object of the present invention and achievement thereof are based on having a dry-etch step follow the thermal development of the dry resist, which will substantially improve, in particular, the contrast of the dry resist. During irradiation, the base material having a high silicon dioxide content polymerizes due to the bombardment by rays. Since during electron exposure, a large portion of the radiation is scattered into the vicinity of the exposed locations due to the proximity effect, a weakly polymerized material is found even in regions that are not directly exposed, and this material can no longer be removed by the thermal development. The process of the present invention is preferably directed to the removal of this weakly polymerized material that causes the poor contrast. This is based on an etch attack by reactive fluorine ions which are formed in the gas discharge in the parallel plate reactor out of CF
4
. In this way, the weakly polymerized material is likewise removed in a dry process. An additional aftertreatment is not needed. With the process of the present invention, one achieves an improved contrast, as well as an increased resist resolution capability.
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Babine Sergey
Dahm Gerold
Holopkin Alexey
Koops Hans Wilfried Peter
Deutsche Telekom AG
Duda Kathleen
Kenyon & Kenyon
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