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
2002-03-11
2004-01-13
Baxter, Janet (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, C526S270000, C526S272000
Reexamination Certificate
active
06677102
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a chemical amplifying type positive resist composition used in the minute processing of a semiconductor.
A lithography process using a resist composition has usually been adopted in the minute processing of a semiconductor. In the lithography, the resolution can be improved with a decrease in wavelength of exposure light in principle as expressed by the equation of Rayleigh's diffraction limit. A g-line with a wavelength of 436 nm, an i-line with a wavelength of 365 nm, and a KrF excimer laser with a wavelength of 248 nm have been adopted as exposure light sources for lithography used in the manufacture of a semiconductor. Thus, the wavelength has become shorter year by year. An ArF excimer laser having a wavelength of 193 nm is considered to be promising as a next-generation exposure light source.
A lens used in an ArF excimer laser exposure machine has a shorter lifetime as compared with lenses for conventional exposure light sources. Accordingly, the shorter time required for exposure to ArF excimer laser light is desirable. For this reason, it is necessary to enhance the sensitivity of a resist. Consequently, there has been used a so-called chemical amplifying type resist, which utilizes the catalytic action of an acid generated by exposure and contains a resin having a group cleavable by the acid.
It is known that, desirably, resins used in a resist for ArF excimer laser exposure have no aromatic ring in order to ensure the transmittance of the resist, but have an alicyclic ring in place of an aromatic ring in order to impart a dry etching resistance thereto. Various kinds of resins such as those described in Journal of Photopolymer Science and Technology, Vol. 9, No. 3, pages 387-398 (1996) by D. C. Hofer, are heretofore known as such resins.
As a resin used in a resist for ArF excimer laser exposure, a mutual copolymer composed of a polymerization unit of alicyclic olefin and a polymerization unit of an unsaturated dicarboxylic acid anhydride (T. I. Wallow et al., Proc. SPIE, vol. 2724, pp. 355-364 (1996)), a polymer having an alicycliclactone structure unit (JP-A-2000-26446) and the like are known. However, any of such resins finds difficulty in providing dry etching resistance as high as that of an aromatic ring.
An object of the present invention is to provide a chemical amplifying type positive resist composition comprising a resin and an acid generating agent suitable for lithography using excimer laser light such as ArF and KrF, which is excellent in balance of performance of resolution and sensitivity and has high dry etching resistance.
The present inventors have found that a resist composition excellent in balance of performance such as resolution, profile, sensitivity and adhesion and high in dry etching resistance is obtainable by using a resin having a polymerization unit derived from a monomer having a specific structure, as a part of the polymerization units of a resin constituting a chemical amplifying type positive resist composition. The present invention has been completed based on this finding.
SUMMARY OF THE INVENTION
The present invention provides a chemical amplifying type positive resist composition comprising;
a resin having a polymerization unit derived from a monomer represented by the following formula (I):
wherein R
1
and R
2
independently represent hydrogen or an alkyl group having 1 to 4 carbons, and R
3
represents hydrogen or a methyl group;
the resin being insoluble in alkali itself but becoming alkali-soluble die to the action of an acid; and
an acid generating agent.
DESCRIPTION OF EMBODIMENTS
The resist composition of the present invention comprises a resin having a polymerization unit derived from a monomer represented by the formula (I) above as a resin component. Specific examples of the monomer represented by formula (I) include the following compounds with the one on the left being preferable.
The resin as a component of the positive resist composition of the present invention is insoluble in alkali but becomes soluble due to the action of an acid. The resin preferably contains a polymerization unit having a group deblocked due to the action of an acid.
Specific examples of the group deblocked due to the action of an acid include various types of carboxylic acid esters, including: alkyl esters having about 1 to 6 carbons typified by tert-butyl ester; acetal esters such as methoxymethyl ester, ethoxymethyl ester, 1-ethoxyethyl ester, 1-isobutoxyethyl ester, 1-isopropoxyethyl ester, 1-ethoxypropyl ester, 1-(2-methoxyethoxy)ethyl ester, 1-(2-acetoxyethoxy)ethyl ester, 1-[2-(1-adamantyloxy)ethoxy]ethyl ester, 1-[2-(1-adamantanecarbonyloxy)ethoxy]ethyl ester, tetrahydro-2-furyl ester and tetrahydro-2-pyranyl ester; and alicyclic esters such as 2-alkyl-2-adamantyl, 1-(1-adamantyl)-1-alkylalkyl and isobornyl ester.
The monomer from which the polymerization unit having a carboxylic acid ester described above is derived may be an acrylic one such as methacrylic acid ester and acrylic acid ester, or an alicyclic monomer with a carboxylic ester group bound thereto, such as norbornene carboxylic acid ester, tricyclodecene carboxylic acid ester and tetracyclodecene carboxylic acid ester. Otherwise, it may be an ester formed by an alicyclic group of an alicyclic carboxylic acid ester and an acrylic acid or a methacrylic acid, as described in Iwasa et al., Journal of Photopolymer Science and Technology, Vol. 9, No. 3, pp. 447-456 (1996).
Among the monomers described above, one having a bulky group containing an alicyclic group such as 2-alkyl-2-adamantyl and 1-(1-adamantyl)-1-alkylalkyl, as the group deblocked due to the action of an acid, is preferably used because such a monomer exhibits excellent resolution. Examples of the monomer having a bulky group containing an alicyclic group include (meta)acrylic acid 2-alkyl-2-adamantyl, (meta)acrylic acid 1-(1-adamantyl)-1-alkylalkyl, 5-norbornene-2-carboxylic acid 2-alkyl-2-adamantyl and 5-norbornene-2-carboxylic acid 1-(1-adamantyl)-1-alkylalkyl.
Among others, use of (meta)acrylic acid 2-alkyl-2-adamantyl as the monomer is preferred for its excellent resolution. Typical examples of the (meta)acrylic acid 2-alkyl-2-adamantyl include acrylic acid 2-methyl-2-adamantyl, methacrylic acid 2-methyl-2-adamantyl, acrylic acid 2-ethyl-2-adamantyl, methacrylic acid 2-ethyl-2-adamantyl and acrylic acid 2-n butyl-2-adamantyl. Among others, acrylic acid 2-methyl-2-adamantyl and methacrylic acid 2-methyl-2-adamantyl are preferred.
Another monomer having a group deblocked due to the action of an acid may also be used as required.
The resin according to the present invention may also have a polymerization unit derived from a monomer having no group deblocked due to the action of an acid. Examples of such a monomer include (meta)acrylic acid esters, alicyclic olefins, unsaturated dicarboxylic acid anhydrides and (meta)acrylonitrile. Specifically, the following compounds are included:
3-hydroxy-1-adamantyl acrylate;
3-hydroxy-1-adamantyl methacrylate;
3,5-dihydroxy-1-adamantyl methacrylate;
&agr;-acryloyloxy-&ggr;-butyrolactone;
&agr;-methacryloyloxy-&ggr;-butyrolactone;
&bgr;-acryloyloxy-&ggr;-butyrolactone;
&bgr;-methacryloyloxy-&ggr;-butyrolactone;
5-acryloyloxy-2,6-norbornane carbolactone;
5-methacryloyloxy-2,6-norbornane carbolactone;
2-norbornen;
2-hydroxy-5-norbornen;
5-norbornen-2-carboxylate;
methyl 5-norbornen-2-carboxylate;
5-norbornen-2-carboxylate-t-butyl
1-cyclohexyl-1-methylethyl 5-norbornen-2-carboxylate;
1-(4-methylcyclohexyl)-1-methylethyl 5-norbornen-2-carboxylate;
1-(4-hydroxycyclohexyl)-1-methylethyl 5-norbornen-2-carboxylate;
1-methyl-1-(4-oxocyclohexyl)ethyl 5-norbornen-2-carboxylate;
1-(1-adamantyl)-1-methylethyl 5-norbornen-2-carboxylate;
1-methylcyclohexyl 5-norbornen-2-carboxylate;
2-methyl-2-adamantyl 5-norbornen-2-carboxylate;
2-ethyl-2-adamantyl 5-norbornen-2-carboxylate;
2-hydroxy-1-ethyl 5-norbornen-2-carboxylate;
5-norbornen-2-methanol;
5-norbornen-2,3-dicarboxylic acid anhydride; etc.;
maleic
Fujishima Hiroaki
Miya Yoshiko
Uetani Yasunori
Baxter Janet
Sumitomo Chemical Company Limited
Thornton Yvette C.
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