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
2000-09-14
2002-11-19
Ashton, Rosemary (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
C430S910000, C430S905000
Reexamination Certificate
active
06482568
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a radiation-sensitive resin composition. More particularly, the present invention relates to a radiation-sensitive resin composition suitable as a chemically-amplified resist useful for microfabrication utilizing various types of radiation, for example, deep ultraviolet rays such as a KrF excimer laser or ArF excimer laser, X-rays such as synchrotron radiation, or charged particle rays such as electron beams.
2. Description of Background Art
In the field of microfabrication represented by fabrication of integrated circuit devices, a lithographic technology enabling microfabrication with a line width of 0.20 &mgr;m or less has been demanded in order to achieve higher integration.
A conventional lithographic process utilizes near ultraviolet rays such as i-line as radiation. It is known in the art that microfabrication with a line width of sub-quarter micron or less is very difficult using near ultraviolet rays.
Therefore, use of radiation with a shorter wavelength has been studied for enabling microfabrication with a line width of 0.20 &mgr;m or less. As radiation with a shorter wavelength, deep ultraviolet rays represented by a line spectrum of a mercury lamp and an excimer laser, X-rays, electron beams, and the like can be given. Of these, a KrF excimer laser (wavelength: 248 nm) and an ArF excimer laser (wavelength: 193 nm) have attracted attention.
As a radiation-sensitive resin composition applicable to the shorter wavelength radiation, a number of compositions utilizing a chemical amplification effect between a component having an acid-dissociable functional group and a photoacid generator which generates an acid upon irradiation (hereinafter called “exposure”) has been proposed. Such a composition is hereinafter called a chemically-amplified radiation-sensitive composition.
As the chemically-amplified radiation-sensitive composition, Japanese Patent Publication No. 27660/1990 discloses a composition comprising a polymer containing a t-butyl ester group of carboxylic acid or a t-butyl carbonate group of phenol and a photoacid generator. This composition utilizes the effect of the polymer to release a t-butyl ester group or t-butyl carbonate group by the action of an acid generated upon exposure to form an acidic group such as a carboxylic group or a phenolic hydroxyl group, which renders an exposed area on a resist film readily soluble in an alkaline developer.
Most of conventional chemically-amplified radiation-sensitive compositions use a phenol resin as a base resin. Deep ultraviolet rays used as radiation for exposure are absorbed due to an aromatic ring in the resin and cannot sufficiently reach the lower layers of the resist film. Because of this, the dose of the radiation is greater in the upper layers and is smaller in the lower layers of the resist film. This causes a resist pattern to be thinner in the upper portion but to be thicker toward lower portion, thereby forming a trapezoid shape after development. No sufficient resolution can be obtained from such a resist film. Such a trapezoid shape formed after development cannot give a desired dimensional accuracy in the succeeding steps such as an etching step and an ion implantation step. In addition, if the configuration of the resist pattern is not rectangular on the upper portion, the resist disappears faster during dry etching, making it difficult to control etching conditions.
The shape of the resist pattern can be improved by increasing the radiation transmittance through the resist film. For example, (meth)acrylate resins represented by polymethylmethacrylate are desirable from the viewpoint of radiation transmittance due to superior transparency to deep ultraviolet rays. Japanese Patent Application Laid-open No. 226461/1992 proposes a chemically-amplified radiation-sensitive composition using a methacrylate resin. However, in spite of excellent micro-processing performance, this composition exhibits only poor dry etching resistance due to the absence of an aromatic ring, giving rise to difficulty to perform etching with high accuracy. This composition thus does not have both radiation transmittance and dry etching resistance at the same time.
A method of introducing an aliphatic ring into the resin component in the composition instead of an aromatic ring has been known as a means for improving dry etching resistance without impairing radiation transmittance of the resist made from a chemically-amplified radiation-sensitive composition. A chemically-amplified radiation-sensitive composition using a (meth)acrylate resin having an alicyclic ring is proposed in Japanese Patent Application Laid-open No. 234511/1995, for example.
This composition, however, comprises groups which are comparatively easily dissociated with conventional acids (for example, an acetal functional group such as a tetrahydropyranyl group) and groups which are comparatively difficult to be dissociated with acids (for example, a t-butyl functional group such as a t-butyl ester group, t-butyl carbonate group) as an acid-dissociable functional group as the resin component. The resin component possessing the former acid-dissociable functional group exhibits excellent basic characteristics as a resist such as superior sensitivity and excellent pattern shape, but has a problem of poor storage stability, whereas the resin component possessing the latter acid-dissociable functional group exhibits impaired resist characteristics, particularly in terms of sensitivity and pattern shape, in spite of excellent storage stability. In addition, inclusion of an alicyclic structure in the resin components increases hydrophobicity of the resin, resulting in poor adhesion to substrates.
Therefore, development of chemically-amplified radiation-sensitive compositions having superior transmittance of radiation represented by deep ultraviolet rays, excelling in dry etching resistance, sensitivity, resolution, and pattern shape, possessing superior storage stability, and exhibiting sufficient adhesion to substrates has been desired.
Accordingly, an object of the present invention is to provide a radiation-sensitive composition used as a chemically-amplified resist showing sensitivity to radiation such as deep ultraviolet rays represented by a KrF excimer laser and an ArF excimer laser, particularly exhibiting superior dry etching resistance without being affected by types of etching gases, having high radiation transmittance, exhibiting excellent basic characteristics as a resist such as sensitivity, resolution, and pattern shape, possessing excellent storage stability as a composition, and exhibiting sufficient adhesion to substrates.
SUMMARY OF THE INVENTION
According to the present invention, the above object can be achieved by a radiation-sensitive resin composition comprising:
(A) a resin containing an acid-dissociable group which is insoluble or scarcely soluble in alkali and becomes alkali soluble when the acid-dissociable group dissociates, the resin comprising the following recurring unit (I), recurring unit (II), and at least one of the recurring units (III-1) and (III-2);
wherein A and B independently represent a hydrogen atom or a linear or branched alkyl group having 1-4 carbon atoms; X and Y independently represent a hydrogen atom, a monovalent oxygen-containing polar group, or a monovalent nitrogen-containing polar group, provided that at least one of X and Y represents a monovalent oxygen-containing polar group or a monovalent nitrogen-containing polar group, otherwise X and Y form a dicarboxylic anhydride group in combination; and n is an integer from 0 to 2;
wherein R
1
represents a hydrogen atom or a methyl group; and R represents a group shown by the following formula (a);
wherein R
3
s individually represent a monovalent alicyclic hydrocarbon group having 4-20 carbon atoms, a derivative thereof, or a linear or branched alkyl group having 1-4 carbon atoms, provided that at least one of R
3
s is a monovalent alicyclic hydrocarbon group having 4-20 carb
Douki Katsuji
Ishii Hiroyuki
Kajita Toru
Murata Kiyoshi
Shimokawa Tsutomu
Ashton Rosemary
JSR Corporation
Kelber Steven B.
Piper Rudnick LLP
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