Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
1998-08-24
2001-02-06
Dawson, Robert (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S315000, C524S366000, C524S356000, C524S570000, C524S588000, C524S483000, C524S859000, C525S105000, C525S106000, C525S474000, C525S479000
Reexamination Certificate
active
06184284
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a coating composition and more particularly to a solution of a hydrolyzed or partially hydrolyzed alkoxysilane, and a cross-linking polymeric resin (e.g., arylcyclobutene and polyphenylene resin) that produces a low dielectric constant polymer.
Hydrolyzed alkoxysilanes have been used as adhesion promoters or coupling agents for arylcyclobutene resins. However, these alkoxysilanes generally have not successfully coated substrates having surfaces composed of more than one material (e.g., a microelectronic device).
The hydrolyzed alkoxysilanes are typically used as a primer layer, i.e., they are applied to the substrate first, followed by application of the polymeric material. The alkoxysilanes are typically hydrolyzed to form aqueous and/or protic solutions before being applied as thin films. However, many organoalkoxy-silanes are not soluble in water and must be dissolved first in a compatible organic solvent, such as an alcohol. Unfortunately, upon application of the aqueous alkoxysilane/alcohol mixture, a discontinuous film may form which contains voids where the film has not covered the substrate.
It is also known that a hydrolyzed alkoxy-silane can be used as an adhesion promoter primer layer for arylcyclobutene resins. For example, in Proc. MRS, Vol. 323, pg. 365, 1994,
Adhesion of Cyclotene™
(
BCB
)
Coatings on Silicon Substrates,
a prehydrolyzed solution of 3-methacryloxypropyltrimethoxysilane (MOPS) in methanol was used as an adhesion promoter for CYCLOTENE™. However, the MOPS solution is extremely difficult to deposit uniformly, forming agglomerates on the surface, which leads to reliability problems when used in fabricated parts.
This is particularly evident when the substrate surface is comprised of more than one material such as a microelectronic device (e.g., integrated circuit, multichip module and flat panel display). A microelectronic device may be comprised of many materials that need to be adhered to by a coating. Materials at the surface of these devices may include, for example, silicon, aluminum, copper, tungsten, silver, gold, platinum, other polymers (e.g., epoxies, polyimides and polyamides), ceramics (e.g., silicas, titanium nitrides, silicon nitrides and silicon oxynitrides).
Currently, polyimide resins are generally the accepted polymeric material employed as thin film dielectrics in the electronics industry. However, polyimide resins tend to absorb water and hydrolyze which can lead to circuit corrosion. Metal ions may migrate into the dielectric polyimide layer requiring a barrier layer between the metal lines and polyimide dielectric. Polyimides may exhibit poor planarization and gap fill properties. Non-fluorinated polyimides may exhibit undesirably high dielectric constants.
Accordingly, it remains highly desirable to provide coating compositions that avoid one or more problems of the prior art such as one of those described above.
SUMMARY OF THE INVENTION
One aspect of the present invention is a coating composition comprising:
a) a hydrolyzed or partially hydrolyzed alkoxysilane,
b) a solvent consisting of an organic liquid or mixture of two or more organic liquids in which component (a) and component (c) are soluble and
c) a cross linking prepolymer, oligomer, resin or mixtures thereof that forms a low dielectric constant crosslinked polymer. In a preferred embodiment, the alkoxysilane is of the formula:
wherein R is C
1
-C
6
alkylidene, C
1
-C
6
alkylene, arylene, or a direct bond; Y is C
1
-C
6
alkyl, C
2
-C
6
alkenyl, aryl, 3-methacryloxy, 3-acryloxy, 3-aminoethyl-amino, or 3-amino; R′ is independently in each occurrence C
1
-C
6
alkyl; and Z is C
1
-C
6
alkyl, C
2
-C
6
alkenyl or OR′.
The coating compositions of the present invention offer advantages such as a separate adhesion promoter application step is not required and a coating can be prepared that is uniformly adhered to a substrate where the substrate surface is comprised of more than one material such as an microelectronic device.
In another aspect, the present invention is an article comprising:
(a) a substrate that has a surface comprised of a first material that is a metal, ceramic or polymer and a second material that is (i) a metal, ceramic or polymer and (ii) different than the first material and
(b) a coating adhered to the surface of the substrate, the coating being comprised of a crosslinked low dielectric polymer of a crosslinking prepolymer, oligomer, resin or mixtures thereof and a hydrolyzed or partially hydrolyzed alkoxysilane.
Adhered, herein, is when the coating has a bond strength to the substrate of at least about 80 MPa regardless of the material the coating is bonded. Preferably the bond strength is at least about 100 MPa, more preferably at least about 125 MPa and most preferably at least about 200 MPa. Alternatively, adhered is when the coating passes the tape peel test described by ASTM Test Method D3359(B). Generally, the coating fails to pass the tape peel test when any part of the coating has bond strength of less than about 80 MPa.
Different material herein means the first material has a different chemistry than the second material. For example, the materials may be two different metals (e.g., copper and aluminum), two different ceramics (silica; alumina), two different polymers (e.g., polyimide; polyamide), a ceramic;metal, a ceramic;polymer, or a metal;polymer.
The coating compositions of the present invention are useful in a variety of applications, including coatings for multichip modules, flat panel displays and integrated circuits.
DETAILED DESCRIPTION OF THE INVENTION
The alkoxysilanes may be any alkoxysilane or mixture thereof capable of forming a solution with the cross linking prepolymer, oligomer, resin or mixtures thereof (herein referred to as polymer precursors) in an organic liquid. Preferably, the alkoxysilanes are dialkoxy or trialkoxysilanes. More preferably, the alkoxysilanes correspond to the formula (I):
wherein R is C
1
-C
6
alkylidene, C
1
-C
6
alkylene, arylene, or a direct bond; Y is C
1
-C
6
alkyl, C
2
-C
6
alkenyl, aryl, 3-methacryloxy, 3-acryloxy, 3-aminoethylamino, or 3-amino; R′ is independently in each occurrence C
1
-C
6
alkyl; and Z is C
1
-C
6
alkyl, C
2
-C
6
alkenyl or OR′.
The term alkylidene refers to aliphatic hydrocarbon radicals wherein attachment occurs on the same carbon. The term alkylene refers to radicals which correspond to the formula —(C
n
H
2n
)—. The term aryl refers to an aromatic radical, aromatic being defined as containing (4n+2)_ electrons as described in Morrison and Boyd,
Organic Chemistry,
3rd Ed., 1973. The term arylene refers to an aryl radical having two points of attachment. The term alkyl refers to saturated aliphatic groups such as methyl, ethyl, etc. Alkenyl refers to alkyl groups containing at least one double bond, such as ethylene, butylene, etc. The groups previously described may also contain other substituents, such as halogens, alkyl groups, aryl groups, and hetero groups such as ethers, oximino, esters, amides; or acidic or basic moieties, i.e., carboxylic, epoxy, amino, sulfonic, or mercapto, provided the alkoxysilane remains compatible with the other components of the coating composition.
Preferably the alkoxysilane is a trialkoxy-silane such as 3-methacryloxypropyltrialkoxysilane, 3-aminopropyltrialkoxysilane, 3-aminoethylaminopropyltrialkoxysilane, a vinyltrialkoxysilane, a benzyltrialkoxysilane, a bicycloheptenyltrialkoxysilane, a cyclohexenylethyltrialkoxysilane, a cyclohexyltrialkoxysilane, a cyclopentadienylpropyltrialkoxysilane, a 7-octa-1-enyltrialkoxysilane, a phenethyltrialkoxysilane or an allyltrialkoxysilane. The alkoxysilane is even more preferably 3-methacryloxypropyl-trimethoxysilane, vinyltriacetoxysilane, vinyltrimethoxysilane and vinyltriethyloxysilane. Most preferably the alkoxysilane is vinyltriacetoxysilane.
The alkoxysilanes are preferably hydrolyzed or partially hydrolyzed by the solventless process described hereinafter and can be used directly in t
Martin Brian B.
Stokich, Jr. Theodore M.
Townsend, III Paul H.
Dawson Robert
Robertson Jeffrey B.
The Dow Chemical Company
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