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
2001-12-20
2003-12-30
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
C430S905000
Reexamination Certificate
active
06670095
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a positive-working resist composition for use in ultramicrolithographic process for the production of very-LSI (very large scale integration) or high capacity microchip or other photofabrication processes. More particularly, the present invention relates to a positive-working resist composition which eliminates edge roughness, provides an excellent profile and exhibits a high sensitivity.
BACKGROUND OF THE INVENTION
In recent years, the degree of integration of integrated circuits has increased more and more. Under these circumstances, it has become necessary to work ultrafine patterns comprising lines with a width of less than half micron in the art of production of semiconductor substrates for very-LSI, etc. To this end, the wavelength of light used in the exposure apparatus in photolithography has been reduced more and more to the extent of considering the use of excimer laser beam (e.g., XeCl, KrF, ArF), which has the shortest wavelength among far ultraviolet rays.
As a resist for forming a pattern in lithography in this wavelength range there is known a chemically amplified resist.
In general, chemically amplified resists can be roughly divided into three groups, i.e., two-component system, 2.5-component system and three-component system (common name). The two-component system chemically amplified resist comprises a compound which undergoes photodecomposition to generate an acid (hereinafter referred to as “photo-acid generator”) and a binder resin in combination. The binder resin contains in its molecule a group which decomposes when acted upon by an acid to increase the solubility of the resin in an alkaline developer (also referred to as “acid-decomposable group”) The 2.5-component system chemically amplified resin comprises a low molecular weight compound having an acid-decomposable group incorporated in such a two-component system. The three-component system chemically amplified resin comprises a photo-acid generator, an alkali-soluble resin and the foregoing low molecular weight compound in combination.
The foregoing chemically amplified resist can be used as a photoresist adapted for irradiation with ultraviolet ray or far ultraviolet ray. However, the use of the chemically amplified resist requires that some demands be met.
As a photoresist composition for ArF light source there has been proposed a resin which comprises an alicyclic hydrocarbon site incorporated therein to render the resin resistant to dry etching. However, the introduction of such an alicyclic hydrocarbon site causes the system to be extremely hydrophobic, making it difficult for the photoresist to be developed with an aqueous solution of tetramethyl ammonium hydroxide (hereinafter referred to as “TMAH”), which has heretofore been widely used as a resist developer, or causing the resist to be peeled off from the substrate during development.
In order to cope with the hydrophobicization of the resist, the mixing of the developer with an organic solvent such as isopropyl alcohol has been considered. Though attaining some good results, this approach cannot necessarily give complete solutions to the foregoing problems because it gives an apprehension that the resist film can swell and complicates the production process. For the part of improving the resist, many approaches have been proposed such as introducing a hydrophilic group to make up for various hydrophobic alicyclic hydrocarbon sites.
JP-A-10-10739 (The term “JP-A” as used herein means an “unexamined published Japanese patent application”) discloses an energy-sensitive resist material comprising a polymer obtained by the polymerization of a monomer having an alicyclic structure such as norbornene ring in its main chain, maleic anhydride and a monomer having carboxyl group. JP-A-10-111569 discloses a radiation-sensitive resin composition comprising a resin having an alicyclic skeleton in its main chain and a radiation-sensitive acid generator. JP-A-11-109632 discloses the use of a resin comprising a polar group-containing alicyclic functional group and an acid-decomposable group as a radiation-sensitive photographic material.
As mentioned above, it is usual that a resin containing an acid-decomposable group for use in photoresist adapted for exposure to far ultraviolet ray also contains an aliphatic cyclic hydrocarbon group in its molecule. The resulting resin is hydrophobic, causing some problems. In order to solve these problems, the foregoing various approaches have bee studied. However, these approaches leave much to be desired.
In recent years, with the demand for the reduction of the size of semiconductor chips, the size of fine semiconductor patterns has reached a range of from 0.13 &mgr;m to 0.35 &mgr;m. However, these compositions used for this purpose are disadvantageous in that the resolving power of line pattern is deteriorated by defects such as edge roughness of line pattern. The term “edge roughness” as used herein is meant to indicate that the pattern is observed uneven at the edge as viewed from above because the top and bottom edges of the line pattern of the resist are arranged irregularly along the line and in the vertical direction due to the characteristics of the resist.
As mentioned above, the conventional known technique on photoresist composition is liable to pattern edge roughness that makes it impossible to obtain a stable pattern. It has thus been desired to provide further improvements.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a high sensitivity chemically amplified positive-working resist composition which eliminates edge roughness on pattern and provides an excellent resist pattern profile.
The foregoing object of the present invention will become apparent from the following detailed description and examples.
The inventors made extensive studies of the constituents of chemically amplified positive-working resist composition. As a result, it was found that the use of a specific acid-decomposable resin makes it possible to accomplish the foregoing object of the present invention. The present invention has thus been worked out.
The foregoing object of the present invention is accomplished by the following constitutions.
(1) A positive-working resist composition comprising:
(A) a resin containing an alkali-soluble group protected by at least one of moieties containing alicyclic hydrocarbon represented by the following general formulae (pI) to (pVI) and having a monomer component content of 5% or less of the total pattern area as determined by gel permeation chromatography (GPC), which increases in its solution velocity with respect to an alkaline developer by the action of an acid:
wherein R
11
represents a methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group or sec-butyl group; Z represents an atomic group required to form an alicyclic hydrocarbon group with carbon atoms; R
12
to R
16
each independently represent a C
1-4
straight-chain or branched alkyl group or alicyclic hydrocarbon group, with the proviso that at least one of R
12
to R
14
or either R
15
or R
16
represents an alicyclic hydrocarbon group; R
17
to R
21
each independently represent a hydrogen atom, C
1-4
straight-chain or branched alkyl group or alicyclic hydrocarbon group, with the proviso that at least one of R
17
to R
21
represents an alicyclic hydrocarbon group and either R
19
or R
21
represents a C
1-4
straight-chain or branched alkyl group or alicyclic hydrocarbon group; and R
22
to R
25
each independently represent a C
1-4
straight-chain or branched alkyl group or alicyclic hydrocarbon group, with the proviso that at least one of R
22
to R
25
represents an alicyclic hydrocarbon group; and
(B) a compound which is capable of generating an acid by irradiation with an active ray or radiation.
(2) The positive-working resist composition according to Clause (1), wherein said resin (A) is one obtained by adding a reaction solution containing a monomer and a radical polymerization initiator
Aoai Toshiaki
Kodama Kunihiko
Sato Kenichiro
Ashton Rosemary
Fuji Photo Film Co. , Ltd.
Sughrue & Mion, PLLC
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