Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Making electrical device
Reexamination Certificate
2002-11-15
2004-10-05
McPherson, John A. (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Making electrical device
C430S313000, C430S322000, C430S270100, C430S910000, C430S945000
Reexamination Certificate
active
06800423
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a radiation-sensitive composition used in the field of micro-machining technique, a microlithographic process using the same and a method for fabricating an electronic device, particularly a semiconductor device, which comprises said microlithographic process.
BACKGROUND OF THE INVENTION
Photolithographic techniques forming a micron-order or submicron-order fine patterns have played a core role of micro-machining technique used for the mass-production of electronic devices. The needs toward a higher degree of integration or density of the recent electronic devices, particularly semiconductor devices have led the micro-machining technique to highly progress. Particularly, as the minimum possible machining dimension has been micronized, the photolithographic technique has been increasingly developed with shortening in a wavelength of a light source from g-line (436 nm) and i-line (365 nm) of a high pressure mercury lamp to KrF excimer-laser (248 nm). With respect to a photoresist, a material thereof has changed with changes in the exposure wavelength. Although photoactive compounds or photosensitivity mechanisms are different from one another, an aqueous alkali development making use of solubility of a resin or high molecular material having a phenol structure to an aqueous alkali has been industrially used for the photoresist corresponding to respective wavelengths. Said resin or high molecular material contains a lot of aromatic rings, which have been chemically required from a viewpoint of improving etching resistance in a dry etching step carried out after formation of a resist pattern. Refer to: Elsa Reichmanis, Larry F. Thompson, Polymers in Microlithography; ACS Symposium Series 412; American Chemical Society: Washington, D.C., 1989; P. 1.
As a negative resist of the phenol structure-carrying resin, there are resists of a cross-linking type as disclosed in JP-A-62-164045 (U.S. Pat. No. 5,034,304) and those of a dissolution inhibition type as disclosed in JP-A-4-165359. In any case, submicron-order fine patterns can be formed with no swelling.
In recent years, as the photolithography wherein the minimum possible machining dimension is in a range of much more smaller than 0.25 &mgr;m, that using a light source of ArF excimer-laser (193 nm) has been greatly expected. However, said wavelength corresponds to the absorption maximum of the aromatic rings. Accordingly, in case of using the phenol structure-carrying photoresist material so far industrially used, it has been difficult to form fine resist patterns through the aqueous alkali development, because a latent image has restrictedly formed only on an extreme surface of the photoresist film. Refer to: J. Photopolym. Sci. Technol. 6(4), 473-490 (1993).
On the other hand, there have been proposed various resist materials having high dry etching resistance as well as high transmittance within said wavelength range. As a chemical structure other than the aromatic rings, which structure is capable of imparting the dry etching resistance to the resist materials, and which is transparent within a far ultraviolet region comprising the wavelength 193 nm of ArF excimer-laser, JP-A-4-39665 and JP-A-5-265212 disclose use of an adamantan structure, and JP-A-5-80515 and JP-A-5-257284 disclose use of norbornane structure. In addition to these structures, JP-A-7-28237 and JP-A-8-259626 disclose that an alicyclic structure such as a tricyclodecanyl group is generally effective.
With respect to a resist material, which is a high polymer having a chemical structure transparent within a far ultraviolet region comprising the wavelength 193 nm of ArF excimer-laser, and which is usable for the aqueous alkali development, it has been attempted to use a carboxylic acid structure of acrylic acid or methacrylic acid, as disclosed in JP-A-4-39665, JP-A-4-184345, JP-A-4-226461 and JP-A-5-80515. According to these attempts, the carboxylic acid structure of acrylic acid or methacrylic acid serves for solubility to the aqueous alkali as a portion soluble in a developer for the aqueous alkali development. Further, JP-A-8-259626 discloses a high molecular compound formed in a manner such that a carboxylic acid group is attached to an alicyclic structure introduced to a side chain of a methacrylic acid ester.
The phenol structure so far used as the alkali soluble group shows 10.0 of pKa (phenol). Whereas, aforesaid carboxylic acid structure shows a lower value, namely 4.8 of pKa (acetic acid), which means a high acidity. Therefore, in case of using such a carboxylic acid structure for a base resin as the alkali soluble group, rather a resin having such a carboxylic acid structure generally exhibits a large dissolution speed in an aqueous alkali, so long as a molar ratio is the same, and dissolves even in an alkali developer of a low concentration, in which a resin having a phenol structure does not dissolve. Refer to: Pine, Hendrickson, Cram, Hammond Organic Chemistry, Fourth Edition, P. 207.
In case of using the resin having a carboxylic acid as mentioned above, there has been left a problem such that when a cross linking agent as disclosed in JP-A-62-164045 is used, a high acidity carboxylic acid remains on a cross-linked portion, which is therefore subjected to penetration of an alkali developer, thereby causing swelling, and as a result, submicron-order fine patterns cannot be formed. Further, in case of using those capable of forming a compound having a dissolution inhibition action by an acid generated by exposure as disclosed in JP-A-4-165359, there has been left a problem such that the resin having a carboxylic acid gives no dissolution contrast and provides no negative resist.
On the contrary, JP-A-11-109627 discloses a method for forming a non-swelling negative pattern, which uses a phenomenon such that a hydroxycarboxylic acid structure changes to a lactone structure through intramolecular esterification by an acid-catalyzed reaction. The hydroxycarboxylic acid structure is effectively esterified in the molecule by acid-catalyzed reaction, thereby forming a lactone structure. As a result, a number of the carboxylic acid greatly decreases. Therefore, it is quite different from a cross-linking reaction occurring between molecules and showing almost no change in numbers of a carboxylic acid between an exposed portion and an unexposed portion. In conclusion, a developer is hard to penetrate in a portion insolubilized by exposure, and it is possible to control swelling of a pattern after development, which is a problem of a prior art.
With respect to the above-mentioned negative resist using lactonization, JP-A-2000-56459 reports use of a polymer of an &agr;-substituted acrylic acid ester having in its ester moiety a group capable of forming an ester in the molecule through the lactonization. Further, JP-A-2000-352821 reports use of a polymer of an acrylic acid ester or methacrylic acid ester having in its ester moiety a &dgr;-hydroxycarboxylic acid-carrying androsterone structure.
SUMMARY OF THE INVENTION
According to the above-mentioned negative resist using lactonization, the hydroxycarboxylic acid is effectively lactonized at an exposed portion, thereby greatly decreasing the number of carboxylic acid. As a result, a developer is hard to penetrate in a portion insolubilized by exposure, and swelling of a pattern after development, which is a problem of a prior art, can be controlled. However, even according to the above-mentioned system decreasing the carboxylic acid, in the formation of fine patterns of a 0.12 &mgr;m level, which has been required for the pattern formation in the field of ArF excimer-laser, there have been left problems such that penetration of a developer cannot be controlled completely, thereby causing swelling, and a resist film remains between lines of the pattern. As a result, a pattern having a good shape could not be obtained.
An object of the present invention is to provide a radiation-sensitive composition capable of forming a high resolution pattern, which is freed
Hattori Takashi
Yokoyama Yoshiyuki
Antonelli Terry Stout & Kraus LLP
Chacko-Davis Daborah
McPherson John A.
Renesas Technology Corp.
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