Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From silicon reactant having at least one...
Reexamination Certificate
2001-09-28
2004-07-27
Robertson, Jeffrey B. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From silicon reactant having at least one...
C528S012000, C528S033000, C528S041000, C525S474000
Reexamination Certificate
active
06767983
ABSTRACT:
FIELD OF TECHNOLOGY
This invention relates to silicone resins and photosensitive resin compositions containing the same useful as resist materials.
BACKGROUND TECHNOLOGY
In the fields of a variety of electronic devices including semiconductor devices that require microfabrication, there is a rising demand for higher density and higher degree of integration of devices and finer patterning has become essential to meet this demand. Moreover, in plasma display panels (PDP), barriers of a high aspect ratio, that is, a high ratio of height to width, are in demand in order to have light of high luminance emitted by enlarging the electric discharge space for display.
A method for obtaining higher resolution in patterning is to use light of shorter wavelength in patterning of photoresists. However, the use of shorter wavelength poses a problem of the depth of focus (DOF) becoming reduced with a drop in sensitivity and aspect ratio. Multi-level resist processes have been proposed to solve this problem. According to a process of this kind, a material such as novolac and polyimide that can be readily dry-etched by oxygen plasma is deposited by spin coating on a substrate and planarized, a resist resistant to dry etching by oxygen is applied to the surface of the planarized layer, a pattern is formed, and then the pattern is transferred to the bottom layer by anisotropic etching by oxygen plasma. As this process yields patterns of a high aspect ratio, developmental works are being conducted extensively on resist materials resistant to oxygen plasma etching.
Resist materials utilizing silicone resins are known to be highly resistant to oxygen plasma etching and, for example, compositions consisting of ladder type polysiloxane esters or polysiloxanes substituted with epoxy-containing alkyl groups and a photosensitive compound capable of generating acid upon exposure to light are proposed in JP 7-56354 (1995)A1 and JP 8-193167 (1996)A1. Moreover, resist compositions containing photosensitive silicone resins that are polysiloxanes to which a diazonaphthoquinonesulfonyloxy group and an azido group are linked are proposed in JP 6-27671 (1994)A1 and JP 6-95385 (1994)A1.
As for the barrier (rib) of a plasma display panel (PDP), a process for constructing a rib with the use of a paste formulated from photosensitive resins and inorganic powders to raise the aspect ratio is described in JP 10-62981 (1998)A1. The photosensitive resins in question are acrylic polymers and the like.
Polyorganosilsesquioxanes are occasionally abbreviated to polysiloxanes and they are known to occur in three types, that is, cage, ladder, and random. Their structures and methods of preparation are described in detail in the specifications of WO98/41566, JP 50-139900 (1975)A1, JP 6-329687 (1994)A1, JP 6-248082 (1994)A1 and elsewhere. A method for introducing functional groups to the ends of these polyorganosilsesquioxanes is also described in detail in the aforementioned WO98/41566.
An object of this invention is to provide photosensitive silicone resins which exhibit excellent performance as resist materials for multi-level resist processes and for forming PDP barriers. Another object of this invention is to provide resist materials which exhibit excellent plasma resistance (resistance to O
2
-RIE) and form patterns of a high aspect ratio.
DISCLOSURE OF THE INVENTION
This invention relates to silicone resins composed of polyorganosilsesquioxanes whose ends are partly or wholly linked to a triorganosilyl group represented by the following general formula (1)
(wherein R is a divalent organic group and R′ is a divalent group or a direct bond).
This invention also relates to the aforementioned silicone resins wherein the polyorganosilsesquioxanes have a repeating unit represented by the following general formula (2)
(wherein R
2
is an unsubstituted or substituted phenyl group) and the average number of repeating units is 2-5,000.
Furthermore, this invention relates to the aforementioned silicone resins wherein the polyorganosilsesquioxanes consist of one type or a mixture of two types or more selected from ladder type, cage type, and mixed cage-ladder type and the weight average molecular weight Mw is 800-100,000 as determined by gel permeation chromatography (GPC) and calibrated against polystyrene.
Still more, this invention relates to the aforementioned silicone resins wherein R is —R
1
COOX
1
— or —R
1
COOX
1
—Si(CH
3
)
2
—O— (wherein R
1
is the divalent residue of a polycarboxylic acid or derivative thereof and X
1
is a divalent group).
Still further, this invention relates to photosensitive resin compositions formulated from the aforementioned silicone resins and a photogenerator of acid.
Finally, this invention relates to a process for preparing the aforementioned silicone resins which comprises treating polyorganosilsesquioxanes with X—Si(R
3
)
2
—Y or X—Si(R
3
)
2
OSi(R
3
)
2
—Y [wherein X and Y are groups capable of linking with carboxyl groups or functional groups capable of reacting with terminal OH groups or terminal OM groups is an alkali metal) of the backbone of polyorganosilsesquioxanes and R
3
is a monovalent organic group] to give modified polyorganosilsesquioxanes containing X or Y at all or a part of their terminal positions, and treating the terminal groups with t—BuOOC—R
1
—COOH (wherein t—Bu is t-butyl group and R
1
is the divalent residue of a polycarboxylic acid or derivative thereof). The group R
3
here is a monovalent organic group such as alkyl and aryl, preferably methyl, and R
3
in a given molecule may be of the same kind or of two or more kinds.
Photosensitive silicone resins of this invention are structurally polyorganosilsesquioxanes to which a triorganosilyl group represented by the aforementioned general formula (1) is linked to all or a part of the ends of the backbone chain. The backbone chain may be represented by the general formula (R
2
Si
2
O
3
)
n
and n designates the number of repetition and is 2 or more. Preferable polyorganosilsesquioxanes have a repeating unit represented by the aforementioned general formula (2) and the average number of repeating units is 2-5,000, more preferably 5-500. The group R
2
is a monovalent organic group and may be a hydrocarbon group such as aryl and alkyl and an alkoxy group, but R
2
is preferably an alkyl group with 1-6 carbon atoms or an unsubstituted or substituted phenyl group, more preferably a phenyl group.
In the triorganosilyl group represented by the general formula (1), R is a divalent organic group and, as indicated by the aforementioned general formula (1), R may be said to contain the residue of a carboxylic acid. The group R′ designates a divalent group or a direct bond and, in the case of a divalent group, it is linked on the other side to the terminal Si—O— group of polyorganosilsesquioxanes. The t-butyl group at the end of of the triorganosilyl group comes off to leave a free carboxyl group behind when it contacts the acid generated from a photogenerator of acid thereby enhancing the the alkali solubility of silicone resins and it is this property that is utilized in patterning.
Carboxylic acids which give the divalent group R include monocarboxylic acids such as benzoic acid and acetic acid and polycarboxylic acids and they are preferably polycarboxylic acids. Such polycarboxylic acids include pyromellitic acid, trimellitic acid, phthalic acid, biphenyldicarboxylic acid, biphenyltetracarboxylic acid, biphenylhexacarboxylic acid, benzophenonedicarboxylic acid, benzophenonetetracarboxylic acid, diphenyl ether dicarboxylic acid, diphenyl ether tetracarboxylic acid, diphenyl sulfone dicarboxylic acid, diphenyl sulfone tetracarboxylic acid, diphenyl sulfide dicarboxylic acid, diphenyl sulfide tetracarboxylic acid, benzanilidedicarboxylic acid, benzanilidetricarboxylic acid, benzanilidetetracarboxylic acid, benzanilidepentacarboxylic acid, cyclohexanedicarboxylic acid, cyclohexenedicarboxylic acid, succinic acid, adipic acid, maleic acid, and fumaric acid.
In the case of polycarboxylic acids, the carboxyl
Fujiyama Takeshi
Teramoto Takero
Birch & Stewart Kolasch & Birch, LLP
Nippon Steel Chemical Co. Ltd.
Robertson Jeffrey B.
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