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
2000-09-07
2001-09-04
Ashton, Rosemary E. (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
C430S923000
Reexamination Certificate
active
06284430
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a novel positive-working chemical-amplification photoresist composition capable of giving a very finely patterned resist layer having an excellently orthogonal cross sectional profile with high photosensitivity and pattern resolution on a substrate surface by patterning exposure using a KrF excimer laser beam and to a method for efficiently forming a very finely patterned resist layer of an isolated pattern having an excellently orthogonal cross sectional profile with fidelity to a photomask pattern by using the above mentioned photoresist composition.
As a trend in the manufacturing technology of semiconductor devices and liquid crystal display panels in recent years, extensive investigations are now under way to establish a photolithographic patterning process of a resist layer having a pattern resolution of as fine as 0.25 &mgr;m or even finer by the use of a positive-working chemical-amplification photoresist composition. Turning now to the problem of the light source for the pattern-wise exposure of the photoresist layer to comply with the requirement in the manufacture of semiconductor devices to accomplish finer and finer patterning, a photolithographic patterning technology for obtaining a patterned resist layer of 0.15 to 0.22 &mgr;m fineness by using a KrF excimer laser beam is the current target of the development works.
With an object to comply with the above mentioned requirements, a proposal is made in Japanese Patent Kokai 7-209868 for a positive-working chemical-amplification photoresist composition containing, as the film-forming resinous ingredient, a copolymeric resin consisting of hydroxyl group-containing styrene units, styrene units and tert-butyl (meth)acrylate units in a molar ratio of 40:20:40 or 33:17:50. The there proposed photoresist composition using a copolymeric resin with a relatively small amount of the hydroxyl group-containing styrene units or a relatively large amount of the tert-butyl (meth)acrylate units is not quite satisfactory when an extremely fine patterned resist layer with 0.15 to 0.22 &mgr;m fineness is formed therewith because the cross sectional profile of the patterned resist layer is not fully orthogonal as desired.
SUMMARY OF THE INVENTION
The present invention accordingly has an object to provide a novel positive-working chemical-amplification photoresist composition capable of giving a finely patterned resist layer with 0.15 to 0.22 &mgr;m fineness and an excellently orthogonal cross sectional profile with high photosensitivity and pattern resolution by the pattern-wise exposure with a KrF excimer laser beam and a method for efficiently forming a very finely patterned resist layer of an isolated pattern with high fidelity to the photomask pattern having an excellently orthogonal cross sectional profile by using the above mentioned photoresist composition.
Thus, the positive-working chemical-amplification photoresist composition provided by the present invention is a uniform blend which comprises, as a solution in an organic solvent:
(A) 100 parts by weight of a copolymeric resin capable of being imparted with increased solubility in an aqueous alkaline solution in the presence of an acid, which consists of from 50 to 85% by moles of hydroxyl group-containing styrene units, from 15 to 35% by moles of styrene units and from 2 to 20% by moles of tert-butyl (meth)acrylate units; and
(B) from 1 to 20 parts by weight of a radiation-sensitive acid-generating agent capable of releasing an acid by decomposition under irradiation with actinic rays.
Further, the method for the formation of a patterned resist layer is provided by the present invention which comprises the steps of:
(a) forming, on the surface of a substrate, a layer of the above defined positive-working chemical-amplification photoresist composition;
(b) subjecting the photoresist layer to a first heat treatment at a temperature in the range of from 100° C. to 110° C.;
(c) subjecting the photoresist layer to pattern-wise exposure to actinic rays;
(d) subjecting the photoresist layer to a second heat treatment at a temperature in the range of from 100° C. to 110° C. and
(e) subjecting the photoresist layer to a development treatment with an aqueous alkaline solution.
REFERENCES:
patent: 5679495 (1997-10-01), Yamachika et al.
patent: 5736296 (1998-04-01), Sato et al.
patent: 5861231 (1999-01-01), Barclay et al.
Oomori Katsumi
Sato Kazufumi
Uchida Ryusuke
Yukawa Hiroto
Ashton Rosemary E.
Tokyo Ohka Kogyo Co. Ltd.
Wenderoth, Ind & Ponack, L.L.P.
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