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
2000-08-25
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
C430S920000, C430S921000, C540S460000, C540S461000, C540S477000, C548S420000, C548S425000, C548S452000, C546S183000, C568S030000, C568S031000, C568S034000
Reexamination Certificate
active
06482567
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to new photoacid generator compounds (“PAGs”) and photoresist compositions that comprise such compounds. In particular, the invention relates to oxime sulfonate and N-oxyimidosulfonate photoacid generator compounds. PAGs of the invention are preferably employed in resists imaged at short wavelengths, such as sub-300 nm and sub-200 nm, e.g. 248 nm, 193 nm and 157 nm and ionizing radiation such as EUV, IPL, E-beam and X-ray.
2. Background
Photoresists are photosensitive films for transfer of images to a substrate. They form negative or positive images. After coating a photoresist on a substrate, the coating is exposed through a patterned photomask to a source of activating energy such as ultraviolet light to form a latent image in the photoresist coating. The photomask has areas opaque and transparent to activating radiation that define an image desired to be transferred to the underlying substrate. A relief image is provided by development of the latent image pattern in the resist coating. The use of photoresists is generally described, for example, by Deforest, Photoresist Materials and Processes, McGraw Hill Book Company, New York (1975), and by Moreau, Semiconductor Lithography, Principals, Practices and Materials, Plenum Press, New York (1988).
Known photoresists can provide features having resolution and size sufficient for many existing commercial applications. However for many other applications, the need exists for new photoresists that can provide highly resolved images of submicron dimension.
Various attempts have been made to alter the make-up of photoresist compositions to improve performance of functional properties. Among other things, a variety of photoactive compounds have been reported for use in photoresist compositions. See, e.g., U.S. Pat. No. 4,450,360 and European Application 615163.
More recently, certain “chemically amplified” photoresist compositions have been reported. Such photoresists may be negative-acting or positive-acting and rely on multiple crosslinking events (in the case of a negative-acting resist) or deprotection reactions (in the case of a positive-acting resist) per unit of photogenerated acid. In other words, the photogenerated acid acts catalytically. In the case of positive chemically amplified resists, certain cationic photoinitiators have been used to induce cleavage of certain “blocking” groups pendant from a photoresist binder, or cleavage of certain groups that comprise a photoresist binder backbone. See, for example, U.S. Pat. Nos. 5,075,199; 4,968,851; 4,883,740; 4,810,613; and 4,491,628, and Canadian Patent Application 2,001,384. Upon selective cleavage of the blocking group through exposure of a coating layer of such a resist, a polar functional group is provided, e.g., carboxyl, phenol or imide, which results in different solubility characteristics in exposed and unexposed areas of the resist coating layer.
SUMMARY OF THE INVENTION
We have now discovered novel photoacid generator compounds (PAGs) for use in either positive-acting or negative-acting photoresist compositions. PAGs of the invention contain an oxime sulfonate group, and/or an N-oxyimidosulfonate group. PAGs of the invention are particularly useful as photoactive components of photoresists imaged at short wavelengths such as 248 nm, 193 nm and 157 nm or even higher energy exposures such as EUV, IPL, E-beam and X-ray.
We have found that excessive absorbance can remain an issue for resists imaged at short wavelengths such as 193 nm, even where the resist resin is optimized for low absorbance such as by having little or no aromatic content. In particular, we have found that a targeted absorption “budget” for a short wavelength resist may be substantially consumed by the resin component alone.
PAGs of the invention can exhibit good transparency especially at 193 nm. Accordingly, PAGs of the invention are particularly useful for photoresists imaged at short wavelengths such as 193 nm and 157 nm and can add minimal absorbance amounts to the formulated resist.
More particularly, in a first aspect of the invention, oxime sulfonate PAGs are provided wherein the oxime carbon has one or two electron-withdrawing substituents. Preferred oxime sulfonate PAGs of the invention include those of the following Formula I:
RR′C═NOS(O)
2
Y I
wherein at least one of R and R′ is an electron-withdrawing moiety such as cyano; nitro; haloalkyl particularly fluoroalkyl such as —CF
3
, —CF
2
CF
3
and other perfluoroalkyl; alkanoyl; alkylsulfinyl; alkylsulfonyl; and the like;
if only one of R and R′ is an electron-withdrawing moiety, then one of R and R′ is suitably carbocyclic aryl such as optionally substituted phenyl and optionally substituted naphthyl; optionally substituted alkyl; optionally substituted alkenyl; optionally substituted alkynyl; optionally substituted alkoxy; optionally substituted heteroalicyclic or heteroaromatic suitably having 1-3 rings with 3-8 ring members per ring and 1-3 N, O or S atoms;
Y is a non-hydrogen substituent such as optionally substituted alkyl; optionally substituted alkenyl; optionally substituted alkynyl; optionally substituted alkoxy; optionally substituted alkylthio; optionally substituted alkylsulfinyl; optionally substituted carbocyclic aryl such as phenyl, naphthyl; and the like; or optionally substituted heteroalicyclic or heteroaromatic suitably having 1-3 rings with 3-8 ring members per ring and 1-3 N, O or S atoms, such as thienyl, and the like.
Preferably, R is an electron-withdrawing group and R′ is a carbocyclic aryl or heteroalicyclic or heteroaromatic group. Cyano is a preferred R group. A particularly preferred R group is halo-alkyl such as C
1-16
haloalkyl, particularly fluoroalkyl such as C
1-16
perfluoroalkyl e.g., such as trifluoromethyl, pentafluoroethyl, perfluorobutane and the like.
Preferred R′ groups include optionally substituted naphthyl, optionally substituted thienyl and optionally substituted pentafluorophenyl.
R and R′ may be the same, or more typically R and R′ are different.
In Formula I, preferred Y groups may be electron-withdrawing groups (to provide a stronger photoacid) such as haloalkyl, particularly perhaloalkyl such as perfluoroalkyl e.g. C
1-12
perfluoroalkyl; carbocyclic aryl such as phenyl, naphthyl and the like, particularly substituted with one or more electron-withdrawing substituents such as nitro, cyano, halo (especially fluoro) with pentafluorophenyl being particularly preferred. Electron-donating groups also will be suitable Y groups such as optionally substituted alkyl, although perhaps less preferred.
In a further aspect of the invention, N-oxyimidosulfonate PAGs are provided that preferably contain two or more N-oxyimidosulfonate groups in a single PAG compound. Such compounds are capable of generating a molar excess of photogenerated acid per mole of the PAG compound.
Bis-N-oxyimidosulfonate compounds are generally preferred, i.e. PAGs that contain two N-oxyimidosulfonate groups. Also preferred are N-oxyimidosulfonate compounds that do not contain an aromatic group. In particular, preferred are compounds of the following Formula IIA:
wherein Y′ and Y″ are the same or different non-hydrogen substituent such as the groups specified for Y in Formula I above;
and the dotted lines indicate covalent linkage (to provide a single compound) between the two N-oxyimidosulfonate groups.
A variety of linkages between the N-oxyimidosulfonate groups are suitable. For example, the N-oxyimidosulfonate groups can each form 5, 6, 7, or 8-membered fused rings, such as PAGs of the following Formula IIB:
wherein Y′ and Y″ are the same or different non-hydrogen substituent as defined in Formula I above;
m, m′, n, and n′ are each independently 0, 1 or 2, and the sum of each of m and m′ and of n and n′ does not exceed 3.
Generally preferred PAGs of Formula IIB include those where m, m′, n, and n′ are each zero, i.e. PAGs
Cameron James F.
Pohlers Gerhard
Ashton Rosemary
Corless Peter F.
Edwards & Angell LLP
Frickey Darryl P.
Shipley Company L.L.C.
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