Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Forming nonplanar surface
Reexamination Certificate
2001-05-03
2003-03-18
Dawson, Robert (Department: 1712)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Forming nonplanar surface
C526S279000, C526S328500, C526S307400, C526S342000, C526S347000, C528S310000, 56, 56, 56, C564S048000
Reexamination Certificate
active
06534250
ABSTRACT:
BACKGROUND OF THE INVENTION
With the increasing growth of semiconductor and microelectronic technology, optical materials have attracted considerable attention since they can meet the demanding performance requirements for telecommunication, data communication and information storage systems.[1,2] One of the most interesting and useful classes of optical materials is photo-reactive polymers, which undergo photo-transformation under direct ultraviolet (UV) or visible (Vis) light irradiation. Recently, the synthesis of photo-reactive polymers has developed to a widespread research area, due to their applications in photoresists,[3] microlithography,[4] holographic data storage,[5] and as photocurable adhesives in optical interconnections.[6]
There are several curable molecular and polymeric systems currently available, these systems usually contain reactive acetylene, epoxide/amine or anhydride groups, as curing agents, and benzocyclobutene (BCB). The problems or weaknesses associated with these curing systems are: high curing temperature is required; environmentally harmful gases are released during the curing procedure; large amounts thereof are required, thereby increasing the production cost and causing voids in molded articles; the area of application is confined due to the lack of interpolymer coupling reactions and only based on dimerization and Diels-Alder cycloaddition reactions with respect to the BCB chemistry. Above all, these curing systems are not best suited to the UV curing process, as they require the use of photoinitiators and photochemically generated acid or base catalysts.
The chemistry of most photo-reactive polymers used in photoresists is based on the incorporation of a functionally photosensitive moiety, for instance, carbon-carbon double bond,[6] epoxide,[6] Novolak/diazoquinone[4b] or photogenerated acid group[4b]. These systems need a photoinitiator, photosensitizer, or a photoacid generator to carry out the photoreactions. If a direct photocurable system consisting of a photo-reactive latent group were available, the cure formulation would be simpler and stable without at least a photoacid/base generator and the cost of fabrication process would be reduced. The incorporation of a latent photo-reactive group into a polymer allows the structural control and tailoring of inherent properties of the polymer.
Benzocyclobutenone (BCBO), that can be easily prepared in large quantities from anthranilic acid, homophthalic anhydride, or o-toluoyl chloride according to known methods[7], has been reported to undergo electrocyclic ring-opening upon thermolysis[8,9] or photolysis[8,10] to give a reactive ketene, &agr;-oxo-o-quinodimethane. Besides the facile thermal[4+2] cycloaddition reaction with dienophiles such as carbonyls,[11] and [60]fullerene[12], it has been demonstrated that the thermally-generated ketene (at 150° C.) also undergoes a coupling reaction with a variety of alcohols to form esters in high yields[13]. An earlier patent (Z. Y. Wang, U.S. Pat. No. 5,869,693) teaches the preparation of a variety of functionalized benzocyclobutenones, particularly 5-aminobenzocyclobutenone, and the polymers derived therefrom. Further, it teaches thermally induced crosslinking and curing with the functionalized benzocyclobutenones.
If the reaction of BCBO with itself or alcohol could also be done under UV irradiation at ambient temperature, BCBO could thus be considered as a latent photo-reactive group, and used as a curing agent for UV-Vis curing of polymers.
There is a need for a UV curing agent that is latent reactive or thermally stable at ambient temperatures and up to 250° C.
There is a need for having such a UV-Vis curing agent that can be easily functionalized and incorporated into a wide spectrum of polymers that are either known and in commercial production or disclosed in the literature.
There is a need for having such a UV-Vis curing agent that survives the polymerization conditions and remains inactive until being triggered by UV-Vis irradiation at ambient temperatures. There is a need for a UV-Vis curing process during which no volatile small molecules are generated.
There is a need for a new type of photo-reactive polymer capable of undergoing grafting and crosslinking by simple UV-Vis irradiation, without using any catalysts or photosensitizers. There is a need for a new type of photo-reactive polymer capable of providing a fine pattern in a submicron to centimeter resolution on different substrates, by simple UV-Vis curing processes without using any catalysts raid or photosensitizers.
SUMMARY OF THE INVENTION
The present invention relates broadly to a series of functionalized photo-reactive benzocyclobutenones that can be used for photochemically crosslinking a variety of hydroxy- or amino-containing polymers.
This invention also relates to a series of polymer compositions that undergo grafting or crosslinking by UV-Vis irradiation to produce polymeric products having an improved balance of properties, and which can be used for surface modification and photochemically forming patterned coatings on substrates.
In particular, the present invention discloses the functionalization of BCBO, the incorporation of BCBO as a latent UV curing agent in a wide spectrum of addition and condensation polymers, and the UV curing procedures and applications thereof of said polymers in surface modification and photopatterning according to their the photo grafting and photo crosslinking reactions.
In accordance with the invention there is provided BCBO derivatives represented by the formulae (I) and (II):
wherein R is —SH, —SO
2
Cl, —SO
3
H, N-substituted group or other electron-withdrawing or electron-donating groups; wherein X is a polyvalent organic bridging group.
In accordance with another aspect of the invention there is provided BCBO-containing copolymers represented by the formulae III-VI:
wherein R is alkyl, aryl, haloalkyl, hydroxyalkyl, —CN, —CONH
2
, —Si(OCH
3
)
3
,
hydroxyalkyl, cyanoalkyl, epoxyalkyl, alkoxy, ether, ester or acetate; and R
1
is H or a methyl group.
In still another aspect of the invention there is provided BCBO-containing terpolymers represented by the formulae VII-X:
wherein R is alkyl, aryl, haloalkyl, hydroxyalkyl, —CN, —CONH
2
, —Si(OCH
3
)
3
,
hydroxyalkyl, cyanoalkyl, epoxyalkyl, alkoxy, ether, ester, acetate; R
1
is H or methyl group; R
3
is alkyl, aryl, or an ester moiety.
The alkyl radicals and moieties in the aforementioned definitions of R typically have 1 to 10, preferably 1 to 6, more preferably 1 to 4 carbon atoms.
The aryl radical in the aforementioned definitions of R typically has 6 to 10 carbon atoms, for example phenyl or naphthyl, and may be unsubstituted or substituted; typical substituents are one or more of alkyl, alkoxy and halogen, in which the alkyl and alkoxy have 1 to 10, preferably 1 to 6, more preferably 1 to 4 carbon atoms; and the halogen is fluorine, chlorine, bromine or iodine.
The values n and m in the above formulae identify the number of repeat units, each of n and m being in the range of 0.1 to 0.9. The designation
as in [
] is convention for identifying a polymer backbone to which the pendant groups shown in the formulae are attached.
In general the copolymers and terpolymers of formula (III) to (X) have a weight average molecular weight of 3,000 to 100,000, preferably 3,000 to 60,000, more preferably 5,000 to 30,000.
In formula (III) n is less than 1; and in formula (VII) m
and m+n should both be less than 1.
DETAILED DESCRIPTION OF THE INVENTION
The present invention provides generally a new type of photo-crosslinker and photo-reactive polymers capable of undergoing grafting and crosslinking upon UV-Vis irradiation, without using any catalysts or photosensitizers. Specifically, the photochemistry based on the reaction of benzocyclobutenone with itself and alcohol is exploited, and the use of benz
Gao Jian Ping
Kuang Li
Wang Zhi Yuan
(Ogilvy Renault)
Carleton University
Dawson Robert
Peng Kuo-Liang
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