Radiation imagery chemistry: process – composition – or product th – Diazo reproduction – process – composition – or product – Composition or product which contains radiation sensitive...
Reexamination Certificate
1997-02-07
2004-04-27
Chu, John S. (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Diazo reproduction, process, composition, or product
Composition or product which contains radiation sensitive...
C430S270100, C430S905000
Reexamination Certificate
active
06727032
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a radiation-sensitive resin composition, and particularly to a radiation-sensitive resin composition which can be favorably used as a chemically amplified photoresist useful in micro-processing using various radiations, e.g., far-ultraviolet radiation such as KrF excimer laser or ArF excimer laser, X rays such as synchrotron radiation, charged particle radiation such as electron beam, etc.
2. Description of the Prior Art
In the field of micro-processing represented by. fabrication of integrated circuit elemental devices, to realize a higher degree of integration, lithography technology capable of micro-processing on the order of sub-half micron (0.25 &mgr;m or less) is recently under development, and it is expected that micro-processing on the order of sub-quarter micron (0.25 &mgr;m or less) will be required in the near future.
In the conventional lithography processing, near ultra-violet radiation such as i-line and the like are used as radiation. However, it is said to be extremely difficult to realize micro-processing on the order of sub-quarter micron with near ultra-violet radiation.
Thus, to enable micro-processing on the order of sub-quarter micron, the use of radiations with shorter wave lengths is considered. Radiations having such short wave lengths include, for example, a bright line spectrum of mercury lamps, far-ultraviolet radiations represented by excimer lasers, X rays, electron beam, etc. Out of these, KrF excimer laser or ArF excimer laser attracts particular attention.
As a radiation-sensitive resin composition suited for irradiation with excimer lasers, there have been proposed many compositions (hereinafter, referred to as “chemically amplified radiation-sensitive composition”) using chemical amplification action effected by a component containing an acid-cleavable functional group and a component which generates an acid upon irradiation with radiation (hereinafter, referred to as “acid-generating agent”).
For example, Japanese Patent Publication (kokoku) No. 2-27660 discloses, as one of the chemically amplified radiation-sensitive compositions, a composition comprising a polymer having a t-butyl ester group of a carboxylic acid or a t-butyl carbonate group of a phenol, and an acid-generating agent. This composition uses the phenomenon that the t-butyl ester group or the t-butyl carbonate group present in the polymer cleaves by the catalytic action of an acid generated by irradiation, so that the polymer comes to have acidic groups of carboxyl or phenol group, and the irradiated areas of the photoresist film thereby become readily soluble in alkaline developing solution.
Most of the chemically amplified radiation-sensitive compositions known heretofore, are based on a phenolic resin. The phenolic resin has a drawback that when far ultraviolet radiation is used as radiation, the far ultraviolet radiation is absorbed by aromatic rings in the resin, and therefore the far ultraviolet radiation can not reach the lower portion near the substrate of the photoresist film sufficiently. For this, irradiation dose is larger at the upper portion of the photoresist film but on the other hand it is smaller at the lower portion, resulting in the problem that the photoresist pattern after development forms a tapered resist profile, that is, the width is smaller at the upper portion and become larger at the lower portion. This means that sufficient resolution can not be obtained. It is also a problem that if the developed photoresist pattern is tapered, desired dimensional accuracy can not be achieved at subsequent steps, i.e., at the steps of etching, ion implantation, etc. Furthermore, if the upper portion of the photoresist pattern in section is not rectangular, the rate of loss of the photoresist caused by dry etching is increased, so that the etching conditions can be controlled with difficulty.
The shape of a photoresist pattern in section can be improved by increasing the transmittance of the photoresist film with respect to radiation. For example, since (meth)acrylate resins represented by polymethyl methacrylate have a high transparency with respect to far ultraviolet radiation, they are very favorable resins from the viewpoint of transmittance of radiation. For example, Japanese Laid-open Patent Publication (kokai) No. 4-226461 discloses a chemically amplified radiation-sensitive resin composition using a methacrylate resin. Although this composition is excellent in performance of micro-processing, it has a drawback of poor dry etching resistance because it contains no aromatic rings. Also, in this case, etching processing with high accuracy can be conducted with difficulty.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a radiation-sensitive resin composition which is particularly excellent in transparency with respect to radiation and dry etching resistance and which can give a photoresist pattern excellent in adhesion to substrates, sensitivity, resolution, developability, etc., as a chemically amplified photoresist sensitive to activated radiations, for example, far ultraviolet radiation represented by KrF excimer laser or Arf excimer laser.
The present invention provides a radiation-sensitive resin composition comprising (A) a resin containing an alicyclic skeleton in the backbone, and (B) a radiation-sensitive acid-generating agent capable of generating an acid upon irradiation.
The radiation-sensitive resin composition of the present invention is, as a chemically amplified photoresist, excellent particularly in transparency for radiation and dry etching resistance, and can form a photoresist pattern excellent in adhesion to substrates, sensitivity, resolution and developability. The composition can be very suitably used in the production of semiconductor devices of which miniaturization will further proceed in the future.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The following terms are herein used to generically have the meaning below.
The term “(cyclo)alkane” includes alkane and cycloalkane, “(cyclo)alkyl” includes alkyl and cycloalkyl, “(cyclo)alkoxy” includes alkoxy and cycloalkoxy, and “(cyclo)acyl” includes acyl and cycloalkylcarbonyl.
The term “(meth)acrylic acid” includes acrylic acid and methacrylic acid, and “(meth)acrylate” includes acrylate and methacrylate.
The term “(co)polymer” includes homopolymer and copolymer, and “(co)polymerization” includes homopolymerization and copolymerization.
The present invention will now be described in detail.
Resin (A)
The alicyclic skeleton contained in the resin comprising an alicyclic skeleton in the backbone (hereinafter, referred to as “resin (A)”) may be monocyclic as in the skeletons derived from cycloalkanes or polycyclic as in the skeletons derived from bicyclo[2.2.1]heptane, tetracyclo[4.4.0.1
2,5
.1
7,10
]dodecane or the like. The resin (A) may contain one or more kinds of alicyclic skeletons.
Said alicyclic skeleton may contain at least one group which is cleaved by an acid (hereinafter, referred to as “acid-cleavable group”) at any position thereon. The alicyclic skeleton may optionally contain one or more substituents other than the acid-cleavable group, e.g., a halogen atom, a monovalent hydrocarbon group having 1 to 10 carbon atoms, a monovalent halogenated hydrocarbon group having 1 to 10 carbon atoms at any position thereon.
The use of the resin (A) comprising an alicyclic skeleton in the backbone according to the present invention, has been able to provide a radiation-sensitive resin composition which is particularly excellent in transparency with respect to radiation and dry etching resistance, and which can give a photoresist pattern excellent in adhesion to substrates, sensitivity, resolution, developability, etc., as a photoresist.
The resin (A) used in the present invention is preferably a resin which is insoluble or slightly soluble in alkali in itself but which has at least one acid-cleavable group to be cleaved by the catalytic action of a
Iwanaga Shin-ichiro
Kajita Toru
Ota Toshiyuki
Suwa Mitsuhito
Chu John S.
JSR Corporation
Kelber Steven B.
Piper Rudnick LLP
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