Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Forming nonplanar surface
Reexamination Certificate
1998-12-21
2001-02-20
Baxter, Janet (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Forming nonplanar surface
C430S330000, C430S331000, C430S270100, C430S281100
Reexamination Certificate
active
06190841
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a pattern forming process useful for fine patterning which is conducted in manufacturing processes of semiconductor elements or the like, and to a photosensitive composition.
BACKGROUND OF THE INVENTION
In manufacturing processes of electronic components such as LSIs, fine pattern techniques utilizing photolithography have conventionally been adopted. Namely, a resist solution is first coated onto the surface of a substrate or the like to form a resist film; and the resist film is subjected to pattern-wise exposure to light, or scanned by beams, and then developed by an alkaline developer to form a resist pattern. Subsequently, the substrate or the like is etched by utilizing this resist pattern as a mask to form minute lines and openings; and the remaining resist is finally removed.
To attain higher integration, there has also been studied the application of electron beam lithography to mass production as a method for precisely forming patterns at levels of sub-quarter microns or less. In general, however, electron beam lithography has such a drawback that it is poor in throughput as compared with conventional light projection. In order to overcome this drawback, studies are now being conducted on resists having high sensitivity to electron beams, particularly chemically sensitized resists.
In the case where a chemically amplified resist is used, a pattern is formed due to the difference in dissolution rate between the exposed area and unexposed area, which is produced by a reaction between the resist and an extremely small amount of an acidic catalyst generated by exposure. The acid generated may be deactivated by an extremely small amount of basic compounds present in the atmospheric environment, by basic compounds existing on the surface of a substrate on which the resist has been coated, by the surface of a substrate which shows the acid-trapping action, or by others. Therefore, there is such a possibility that the reproducibility of the characteristics of the resist, or the profile of the resist pattern is impaired. For this reason, an in-line system or the like in which no stagnation is caused in a series of steps from coating to development is required for manufacturing processes using chemically amplified resists. Moreover, chemically amplified resists are required to be used in an atmosphere which is cleaner than ever.
Thus, conventional chemically amplified resists tend to be affected, during the period between their production and use, by the environment or by materials used for their production. Therefore, it has been difficult to obtain patterns with high reproducibility by applying the resists to lithographic processes.
SUMMARY OF THE INVENTION
A pattern forming process of the present invention comprises the following steps of:
(1) preparing a photosensitive material by coating, onto the surface of a substrate, a photosensitive composition comprising the following components:
(a) an acid generator which generates an acid when irradiated with actinic radiation, and
(b) a compound containing carboxyl groups, which can decompose upon decarboxylation,
(2) subjecting the photosensitive material to pattern-wise exposure to actinic radiation, thereby allowing the acid generator (a) to generate an acid in the exposed area,
(3) neutralizing the acid generated in the exposed area with a basic compound (c),
(4) allowing the carboxyl group in the carboxyl-group-containing compound (b) in the unexposed area to cause decarboxylation by applying conditions under which the decarboxylation proceeds by being catalyzed by the basic compound (c), and
(5) developing the photosensitive material.
The present invention also relates to a photosensitive composition comprising the following components:
(a) an acid generator which generates an acid when irradiated with actinic radiation,
(b) a carboxyl-group-containing compound which can decompose upon decarboxylation, and
(c) a basic compound.
By the use of the pattern forming process of the present invention, a pattern can be formed with high reproducibility, without being affected by basic impurities present in the environment, especially in the air, or on the surface of a substrate.
Further, according to the present invention, there can be obtained a photosensitive composition with which a pattern can be formed with high reproducibility, without being affected by basic impurities present in the environment, especially in the air, or on the surface of a substrate.
REFERENCES:
patent: 5019488 (1991-05-01), Mammato et al.
patent: 5545509 (1996-08-01), Cameron et al.
patent: 5650261 (1997-07-01), Winkle
patent: 9-134003 (1997-05-01), None
patent: 4226464 A1 (1994-02-01), None
English translation of DE 4226464 A1 (Translated by Diplomatic Language Services, Inc.).
Kihara Naoko
Saito Satoshi
Ushirogouchi Toru
Baxter Janet
Kabushiki Kaisha Toshiba
Lee Sin J.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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