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
2003-07-02
2004-08-03
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
C430S325000, C430S919000, C430S921000, C522S059000, C522S057000, C558S301000, C568S030000
Reexamination Certificate
active
06770420
ABSTRACT:
The present invention relates to specific oxime alkyl sulfonate compounds, i.e. compounds containing the structural unit
and to their use as photo-sensitive acid generator in chemically amplified photoresists, in printing plates, colour filters or image recording materials which are developable in alkaline medium, to their use as dissolution inhibitors in a corresponding positive photoresist, and to a process for the production of images using such resists, printing plates or image recording materials.
A chemically amplified photoresist will be understood as meaning a resist composition, the photosensitive component of which, when irradiated, generates only that amount of acid which is required to catalyse a chemical reaction of at least one acid-sensitive component of the resist, as a result of which the ultimate differences in solubility between irradiated and non-irradiated areas of the photoresist first develop.
Industrial paint formulations based on a large number of photosensitive oxime sulfonates and conventional acid-curable resins are disclosed in U.S. Pat. No. 4,540,598. These formulations are cured firstly with actinic light, especially with radiation in the range of 250 to 400 nanometers. The oxime sulfonates generate acid, so that a thermal cure in which the material also becomes insoluble in customary solvents is able to take place even at quite low temperatures. Nothing can be inferred about an imagewise exposure of corresponding resist films or about related problems as well as the image properties of the numerous formulations falling within the generic scope of the teaching of this patent specification. Oxime sulfonates, which are sparingly soluble in alkaline-aqueous developers, can be converted to the soluble form of the free acid by irradiation. Combined with a suitable film-forming resin, they can therefore be used as dissolution inhibitors for the production of positive resists.
Conventional positive photoresist compositions based on oxime sulfonates and alkali-soluble binders, typically cresol novolaks or hydroxymethacrylate/acrylic acid copolymers, are also known and are disclosed in EP-A-0 241 423. According to this reference, radiation of 200 to 600 nm can be used for exposing the resists. The shortcoming of these photo-resists is, however, that resolution and sensitivity are simultaneously never altogether satisfactory. This is particularly the case upon exposure to radiation in the range of the mercury i-line, which has a wavelength of 365 nanometers and is often used for the imagewise exposure of resist films, because mercury medium- and high-pressure lamps are inexpensive sources of radiation for producing radiation of these wavelengths with good intensity.
In the article “Photochemistry of Imino Sulfonate Compounds and Their Application to Chemically Amplified Resists” by Masamitsu Shirai and Masahiro Tsunooka; Journal of Photopolymer Science and Technology, Vol. 3(3), 1990, p. 301-304, there are also disclosed chemically amplified photoresist compositions based on oxime sulfonates as acid generator and poly(p-tert-butyloxycarbonyloxystyrene) as acid-sensitive component. The styrene component decomposes, catalysed by the acid generated by the acid generator upon exposure to irradiation to form poly(p-hydroxystyrene). This results in the exposed areas becoming soluble in alkaline developers so that positive images can be obtained with such developers. The described oxime sulfonates have an absorption maximum of about 250 nanometers in the UV/VIS spectrum, but have only low absorption for radiation in the wavelength of 313 nanometers and higher. Thus only a low sensitivity of the compositions to 313 nanometers radiation was found.
GB-A 2 306 958 describes the use of oxime sulfonates as photosensitive acid generators which are in particular suitable for use with light having a wavelength higher than 390 nm. However, the resolution and sensitivity of the resist formulations obtained with these initiators is not satisfactory.
Accordingly, there is still a need for reactive nonionic latent acid generators which are thermally and chemically stable and which, after being activated by light, in particular by radiation having the wavelength of the mercury i-line (365 nm), can be used as catalysts for different acid-catalysed reactions, such as polycondensation reactions, acid-catalysed depolymerisation reactions, acid-catalysed electrophilic substitution reactions or the acid-catalysed removal of protective groups. There is, in particular, a need for acid generators which can be activated with light and with which systems of higher sensivity and better resolution are obtained, having improved properties such as the form of the resist profiles and steepness of the side walls. Furthermore, there is a need for compounds which are converted to an acid when exposed to light and which can act as dissolution inhibitors in resist formulations.
U.S. Pat. No. 5,627,011 discloses the use of oxime sulfonate compounds in high-resolution i-line photoresists of high sensitivity. However, this publication only mentions oxime sulfonate compounds which can generate aromatic sulfonic acids. Surprisingly, it has now been found that resists of good sensitivity, resolution and having excellent resist profiles are obtained when an alkyl sulfonic acid is photochemically generated.
U.S. Pat. No. 4,451,286 discloses, among other oximes which do not contain any sulfonic acid groups, the compounds methylsulfonyloxyiminobenzylcyanide, methylsulfonyloxyiminonaphthylcyanide and methylsulfonyloxyimino-3-thiophenylcyanide in combination with chloroacetanilide compounds as plant protection agents.
This invention provides photoresist compositions having excellent resolution coupled with excellent sensitivity. These properties are observed especially when the resist compositions are exposed to radiation in the range of the mercury i-line which has a wavelength of about 365 nanometers.
Surprisingly, excellent resolution and outstanding sensitivity are achieved by using oxime alkyl sulfonates of formula I below which have been specially chosen with respect to the chromophoric part of the molecule as photoacid generators in chemically amplified photo-resist compositions which are developable in aqueous-alkaline media. This applies both to corresponding negative as well as to positive photoresists containing an acid-sensitive component that undergoes an acid-catalysed chemical reaction which changes the solubility of the compositions in aqueous-alkaline developers.
Accordingly, this invention relates to compositions which can be actived by light, comprising
a) at least one compound which may be crosslinked by the action of an acid and/or
b) at least one compound which changes its solubility under the action of an acid, and
c) as photoinitiator at least one compound of formula 1
R
0
is either an R
1
—X group or R
2
;
X is a direct bond or an oxygen atom;
R
1
is hydrogen, C
1
-C
4
alkyl which is unsubstituted or substituted by phenyl, OH or C
1
-C
4
-alkoxy or which may be interrupted by an —O-atom, or R
1
is a phenyl group which is unsubstituted or substituted by a substituent selected from the group consisting of chloro, bromo,
C
1
-C
4
alkyl and C
1
-C
4
alkyloxy;
R
2
is hydrogen or C
1
-C
4
alkyl; and
R
3
is straight-chain or branched C
1
-C
12
alkyl, which is unsubstituted or substituted by one or more than one halogen atoms, or is phenyl-C
1
-C
2
alkyl or campheryl, which composition can contain other photoinitiators, sensitisers and/or additives besides component c). The invention also relates to the use of compounds of formula 1 as photosensitive acid generators in a photoresist sensitive to radiation in a wavelength of up to 390 nanometers.
The invention further relates to chemically amplified photoresists which are developable in alkaline medium and which are sensitive to radiation in the range from 340 to 390 nanometers, which resists are based on oxime alkyl sulfonates as photosensitive acid generator and contain a compound of formula 1 as defined above as oxime alkyl sulfonate
De Leo Christoph
Dietliker Kurt
Kunz Martin
Yamato Hitoshi
Ashton Rosemary
Ciba Specialty Chemicals Corporation
Mansfield Kevin T.
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