ADHESION PROMOTER AND SELF-PRIMING ARYLCYCLOBUTENE RESIN COMPOSITIONS

Abstract: A coating composition comprising: a hydrolyzed or partially hydrolyzed alkoxysilane, a solvent, and an arylcyclobutene; is useful in a variety of applications, including coatings for multichip modules, flat panel displays and integrated circuits. The preferred alkoxysilanes correspond to formula (I) wherein R is C1-C6 alkylidene, C1-C6 alkylene, arylene, or a direct bond; Y is C1-C6 alkyl, C2-C6 alkenyl, aryl, 3-methacryloxy, 3-acryloxy, 3-aminoethylamino, or 3-amino; R' is independently in each occurrence C1-C6 alkyl; and Z is C1-C6 alkyl, C2-C6 alkenyl or OR'.

Description: ADHESION PROMOTER AND SELF-PRIMING ARYLCYCLOBUTENE RESIN COMPOSITIONS The present invention relates to a coating composition and more particularly to a solution of a hydrolyzed or partially hydrolyzed alkoxysilane, and an arylcyclobutene resin, and to a solventless process for preparing hydrolyzed or partially hydrolyzed alkoxysilanes. It is known to use hydrolyzed alkoxysilanes as adhesion promoters or coupling agents for various polymeric materials. The hydrolyzed alkoxysilanes are typically used as a primer layer, that is, 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, most 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 forms 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 Cydotene ' (BCB) Coatings on Silicon Substrates, a prehydrolyzed solution of 3-methacryl-oxypropyltrimethoxysilane (MOPS) in methanol was used as an adhesion promoter for Cydotene " . 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. It is also known to hydrolyze specific silanes in the absence of a solvent. U.S. Patent No. 3,350,345 to Vanderbilt et al. describes a process of hydrolyzing specific silanes by adding water to hydrolyze at least one but not all of the alkoxy groups. The specific si lanes have reactive groups such as amino, mercapto, carboxyl or cyano, which self-catalyze the hydrolysis process. Accordingly, it remains highly desirable to provide coating compositions containing an arylcyclobutene which does not exhibit the foregoing disadvantages as well as to provide a process which does not use an organic solvent for hydrolyzing alkoxysilanes. One aspect of the present invention is a coating composition comprising : a) a hydrolyzed or partially hydrolyzed alkoxysilane, b) a solvent, and c) an arylcyclobutene. In a preferred embodiment, the coating composition comprises: a) an alkoxysilane of the formula: ( I ) Y-R-Si-OR ' I z wherein R is C r C 6 alkylidene, C C 6 alkyleπe, arylene, or a direct bond; Y is C r C 6 alkyl, C 2 -Cg alkenyl, aryl, 3-methacryloxy, 3-acryloxy, 3-aminoethyl-amino, or 3-amino; R' is independently in each occurrence C r C 6 alkyl; and Z is C r C 6 alkyl, C 2 -C6 alkenyl or OR', wherein the alkoxysilane has been hydrolyzed or partially hydrolyzed, (b) a solvent, and (c) an arylcyclobutene. In a most preferred embodiment, the coating composition comprises a partially hydrolyzed 3-methacryloxypropyltrimethoxysilane, mesitylene, and a bisbenzocyclobutene prepolymer. The coating compositions of the present invention offer significant economic advantages in that a separate adhesion promoter application step is not required. In another aspect, the present invention is a method of hydrolyzing an alkoxysilane which comprises adding sufficient water to hydrolyze at least one alkoxy group, optionally, in the presence of acidic or basic catalysts. In a preferred embodiment, 3-methacryloxypropyltrimethoxysilane is partially hydrolyzed in the presence of hydrochloric acid. 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. The alkoxysilanes which can be employed in the coating composition of the present invention can be any alkoxysilane or mixture thereof which are capable of forming a solution with the arylcyclobutene components in an organic liquid. Preferably, the alkoxysilanes are dialkoxy or trialkoxysilanes. More preferably, the alkoxysilanes correspond to the formula: ( I ) Y-R-Si-OR ' I z wherein R is alkylidene, Cy-Cβ alkylene, arylene, or a direct bond; Y is C 1 -C6 alkyl, 2 -C β alkenyl, aryl, 3-methacryloxy, 3-acryloxy, 3-aminoethylamino, or 3-amino; R' is independently in each occurrence C β alkyl; and Z is C C 6 alkyl, C 2 -Cβ alkenyl or 5 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 H2n)- • The term aryl refers to an aromatic radical, aromatic being defined as containing (4n + 2)π electrons as described in Morrison and Boyd, Organic Chemistry, 3rd Ed., 10 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, esters, amides; or acidic or basic moieties, that is 5 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-aminoethylaminopropyl-trialkoxysilane, a vinyltrialkoxysilane, 0 a benzyltri-alkoxysilane, a bicycloheptenyltrialkoxysiiane, a cyclohexenylethyltrialkoxysilane, a cyclohexyltri-alkoxysilane, a cyclopentadienylpropyltrialkoxysilane, a 7-octa-1- enyltrialkoxysilane, a phenethyltrialkoxysilane or an allyltrialkoxysiiane. The alkoxysilane is most preferably 3-methacryloxypropyl-trimethoxysilane. The alkoxysilanes are preferably hydrolyzed or partially hydrolyzed by the 5 soiventless process described hereinafter and can be used directly in the coating compositions. However, some alkoxysilanes hydrolyze so easily that hydrolysis prior to use in the composition of the present invention is not necessary. These alkoxysilanes hydrolyze self-catalytically when used in the composition of the present invention such that upon application to a substrate, the alkoxysilane is hydrolyzed by ambient air humidity. Such alkoxysilanes can be defined as 0 alkoxysilanes which, upon contact with water in the absence of a catalyst, hydrolyze in 30 minutes or less. Examples of such alkoxysilanes include 3-aminopropyltriethoxysilane and 3- aminoethylamino-propyltriethoxysilane. Alternatively, the hydrolyzed or partially hydrolyzed alkoxysilane can be prepared in a volatile solvent. In such case, all or most of the solvent must be removed prior to being incorporated into the coating composition of the present invention. 5 The alkoxysilanes useful in the practice of the present invention can be made by techniques well known in the art such as exemplified in Encyclopedia of Chemical Technology, Third Edition, Volume 20, pp., 916-918, 1982 and Silane Coupling Agents by Edwin P. Plueddemann, Chapter 2, pp.30-31, 1982. The solvent used in the film forming coating composition of the present invention can be any organic liquid or mixture of two or more organic liquids in which the adhesion promoter and the arylcyclobutene are soluble to produce a film forming composition. The solvent is preferably an aprotic solvent or one which is highly immiscible with water. Representative examples of solvents include aromatic hydrocarbons, ketones, esters, ethers or mixtures thereof. Preferably, the solvent is an aromatic hydrocarbon, more preferably toluene, xylene, mesitylene or an alkylnaphthalene and most preferably mesitylene. The arylcyclobutene used in the film forming coating compositions can be any arylcyclobutene which is capable of forming a solution with the hydrolyzed alkoxysilane in the organic liquid described previously. Arylcyclobutenes contain an aryl moiety to which one or more cyclobutene rings are fused. Examples of suitable aryl moieties include benzene, naphthalene, phenanthrene, anthracene, pyridine, a biaryl moiety, or 2 or more aromatic moieties bridged by alkylene or cycloalkylene moieties. Preferred aryl moieties are benzene, naphthalene, biphenyl, binaphthyl, diphenyl aikane or diphenyl cycloalkane moieties. The more preferred aryl moiety is a benzene moiety. Arylcyclobutenes and methods of making are well known in the art and are exemplified in U.S. Patent No.4,540,763 by Kirchoff, which is incorporated herein by reference. Preferred arylcyclobutenes correspond to the formula: wherein B is a direct bond or bridging member which comprises (1) a polyvalent inorganic radical, or (2) a polyvalent organic moiety which can contain (a) one or more heteroatoms comprising oxygen, sulfur, nitrogen, or phosphorus, or (b) one or more aromatic moieties; Ar is an aromatic radical which may be substituted; R is separately in each occurrence hydrogen or an electron-withdrawing or electron-donating substituent; m is an integer of 1 or 2 and n is an integer from 1 to 5, with the proviso that B can only be a direct bond wherein n is 2. In a more preferred embodiment, the arylcyclobutene is benzocyclobutene (the aromatic moiety is benzene and m is 1 ). Preferred benzocyclobutenes correspond to the formula: wherein a is separately in each occurrence the integer 0, 1, 2 or 3; and B, R, and n are as defined hereinbefore. These materials are further defined and taught in U.S. Patent Number 4,642,329 which is incorporated herein by reference. Additional compounds corresponding to Formula II wherein B contains Si are further defined and taught in US-A-4,999,449. Other U.S. Patents which disclose exemplary benzocyclobutene resins include US-A-4,687,823; US-A-4,730,030; US-A-4,759,874; US-A-4,783,514; US-A-4,812,588; US-A-4,826,997; US-A-4,973,636; and US-A-5,025,080, as well as WO 9312055. Mixtures or copolymers of two or more different arylcyclobutenes can also be employed. In addition, the composition can contain other monomers copolymerizable with the arylcyclobutene such as ethylenically unsaturated monomers, for example, styrenes, acrylates, divinylbenzene, and methacrylates, acetylenic monomers, for example, phenyl acetylene and diphenyl acetylene, and other monomers capable of polymerization with the arylcyclobutene. The arylcyclobutene can be used in the form of a monomer, an oligomer, a polymerized or copolymerized resin, a prepolymer, that is, a partially polymerized or copolymerized arylcyclobutene having reactive polymerization sites which provide for further polymerization, or a combination thereof. The coating compositions may also contain other additives to impart other useful properties to the film forming compositions. Such additives include but are not limited to photocrosslinking agents such as bis(arylazides), for example 2,6-bis(4azidobenzylidene)-4- ethylcyclohexanone or 2,2-bis(4-(4-azidophenoxy)-phenyl)propane, energy transfer agents (exemplified in WO 9312055), and anti-oxidants (exemplified in US-A-5,185,391). The amounts of the alkoxysilane, solvent, and arylcyclobutene employed in the coating composition is dependent upon a number of factors including the specific end-use application and the properties desired. One such application is an adhesion promoter primer coating. As mentioned, a promoter primer coating provides adhesive bonding between the surface to which it is applied and a subsequently applied coating layer. Alternatively, the composition is a self-priming coating. In such a case, the hydrolyzed alkoxysilane functions to provide adhesive bonding between the surface to which the self priming formulation is applied and the resultant arylcyclobutene film. In addition, it can also provide adhesive bonding to a subsequently applied surface. In general, a primer composition normally will contain lesser amounts of the arylcyclobutene than when the composition is used as a self-priming composition. In general, regardless of its intended end-use, the composition comprises from 0.01 to 10 weight percent hydrolyzed alkoxysilane, from 10 to 99.9 weight percent solvent, and from 0.01 to 90 weight percent arylcyclobutene, said weight percents being based on the total weight of the composition. o In general, when applied as an adhesion promoter primer coating application, the composition comprises from 0.01, more preferably from 0.2, most preferably from 1.5 weight percent, to 10, more preferably 5, and most preferably to 2.5 weight percent of hydrolyzed alkoxysilane; from 75, more preferably 90, and most preferably 92.5 weight percent to 99.9, more preferably 99.5, and most preferably 98 weight percent of solvent, and from 0.01, 5 more preferably from 1 , and most preferably from 2 weight percent to 20, more preferably 10, and most preferably 5 weight percent of arylcyclobutene, said weight percents being based on the total weight of the composition. Alternatively, when employed as a self-priming coating application the composition comprises from 0.01, more preferably from 0.2, and most preferably from 0.5 weight percent to 5, more preferably to 3, and most preferably to 1 weight percent of hydrolyzed alkoxysilane; from 10, more preferably from 20, and most preferably from 35 weight percent to 95, more preferably to 90 and most preferably to 80 weight percent of solvent; and from 5, more preferably from 10, and most preferably from 20 weight percent to 90, more preferably to 80, and most preferably to 65 weight percent of arylcyclobutene, said weight percents being based on the total weight of the composition. In coating articles for use in electronics applications such as multichip modules, flat panel displays, and integrated circuits, representative substrates which can be coated with the coating composition include metals such as aluminum, copper, titanium and chrome; ceramics such as alumina, silica, MgO, BeO, including spinels, aluminum nitride, boron nitride, silicon nitride, gallium arsenide; and glasses such as fiber glass, lime glass, flint glass, borosilicate glass, Pyrex and Vycor. Preferably, if the substrate is a metal such as copper, it is treated with an etchant such as 1 percent acetic acid prior to application of the coating composition. Substrates commonly used in high density electronic circuitry, such as silicon, thermally oxidized silicon, GaAs, alumina and aluminum are commonly treated by processes such as oxygen plasma etching or RCA clean, to control surface chemistry. While the coating compositions can be applied using any of the techniques well known in the art, such as spray, brush, dip, meniscus, extrusion, capillary, curtain, and roll coating, they are typically advantageously applied at room temperature using conventional spin-coating techniques. In this application, the coating composition can be used as an adhesion promoter primer layer or as a self-priming BCB polymer layer. Typical thicknesses for adhesion promoter primer layers are between 100 to 1000 Angstroms, whereas the thickness of the self-priming polymer layer can vary from 0.5 to 25 microns. Multiple layers may be prepared using the composition either as an adhesion promoter primer or a self-priming polymer layer. The multi¬ layer coatings typically range between 10 to 500 microns and are preferably from 50 to 200 microns. The coating compositions of the present invention may also be subsequently coated with other polymeric materials such as other arylcyclobutene polymers and copolymers or any other polymeric material which will bond with the coating composition. After being applied, the coating compositions can be crosslinked, photocrosslinked, cured or soft cured. Photodefineable arylcyclobutenes are typically photocrossl inked prior to further cure. Conventional curing techniques such as electron beam, ultra violet, thermal radiation, or convection can also be employed. The degree of polymerization will depend upon the application involved. For instance, when additional layers will be applied, a soft cure or crosslinking of 80 to 85 percent (as measured by FTIR) is preferred and can be accomplished, for example, by heating at 220°C for 30 minutes. In the final stage of curing, crosslinking of more than 95 percent can be achieved, for example, by heating at 250 C C for 1 hour. The alkoxysilane used in the coating composition of the present invention is preferably prepared using a soiventless process in which the alkoxysilane is contacted with a sufficient amount of water to hydrolyze at least one alkoxy group. Optionally, an acidic or basic catalyst is also employed. The alkoxysilanes used in the process of hydrolysis can be any alkoxysilane which has no groups sufficiently acidic or basic to catalyze the hydrolysis reaction. Preferably, the alkoxysilanes are those which have been described previously in Formula (I), with the proviso that R is not 3-aminoethylamino or 3-amino and R, Y, and Z may only be further substituted with moieties which are substantially inert or nonreactive in the hydrolysis reaction. Examples of such inert substituents include but are not limited to halogens, alkyl, and aryl groups. More preferably, the alkoxysilane is a trialkoxysilane and is most preferably 3- methacryloxypropyltrimethoxysilane. The amount of water most advantageously employed in the hydrolysis reaction is dependent upon a variety of factors including the degree of hydrolysis desired. To achieve complete hydrolysis, a stoichiometric amount of water to completely hydrolyze the alkoxysilane is 1 molar equivalent of water for each molar equivalent of alkoxy group present on the alkoxysilane. In practice, less than a stoichiometric amount of water is required for complete hydrolysis since water is formed by condensation reactions during the hydrolysis. The amount of water used for desired hydrolysis in the present invention is preferably no more than a stoichiometric amount. Preferably from 10 percent to 80 percent of the stoichiometric amount of water needed for total hydrolysis is used, more preferably from 30 percent to 60 percent and most preferably 40 percent. The water used in the hydrolysis should be purified. Preferably, the water is deionized and microfiltered. The optional, but generally preferred, acidic or basic catalysts may be any acidic or basic compound which will catalyze the hydrolysis of the alkoxysilane. Examples of acidic catalysts include but are not limited to hydrochloric acid, sulfuric acid, trifluoroacetic acid, chloroacetic acid, methane sulfonic acid, and phosphoric acid. Examples of basic catalysts include but are not limited to potassium hydroxide, sodium hydroxide, and 3- aminopropyltrialkoxysilaπes. More advantageously, the catalyst is acidic. Preferably, the acidic catalyst is hydrochloric acid, sulfuric acid, trifluoroacetic acid, methane sulfonic acid, or phosphoric acid. More preferably, the catalyst is hydrochloric acid, sulfuric acid, trifluoroacetic acid, or phosphoric acid, and most preferably hydrochloric acid. The catalyst is used in amounts sufficient to catalyze the hydrolysis reaction. The amount of catalyst most advantageously employed will depend upon a number of factors including the desired rate of hydrolysis, the catalyst, the alkoxysilane used, and the degree of hydrolysis desired. Preferably, the catalyst is present in amounts from 0 ppm to 50 ppm based ° n the amount of hydrolyzed alkoxysilane. More preferably, the catalyst is present in amounts from 2 ppm to 40 ppm and most preferably between 4 ppm to 30 ppm, based on the amount of hydrolyzed alkoxysilane. Hydrolysis of alkoxysilanes produces a mixture of nonhydrolyzed, partially hydrolyzed, fully hydrolyzed and oligomerized alkoxysilanes. Oligomerization occurs when a hydrolyzed or partially hydrolyzed alkoxysilane reacts with another alkoxysilane to produce water and an Si-O-Si bond. As used herein, the term "hydrolyzed alkoxysilane" encompasses any level of hydrolysis, partial or full, as well as oligomerized. In hydrolyzing the alkoxysilane, the alkoxysilane, water, and optional catalyst are mixed until the desired hydrolysis is complete. While the time to complete hydrolysis will vary depending on a number of factors, including the specific reactants employed, in general, hydrolysis is complete in a time from 2 minutes to 5 hours, preferably for 4 minutes to 2 hours, and more preferably for 10 minutes to 1 hour. In general, the alkoxysilane, water, and catalyst initially form a two-phase mixture which upon agitation and continuation of the hydrolysis reaction, becomes a single phase. The time required to form a single phase is dependent upon the alkoxysilane used and the temperature at which the ingredients are mixed; with less time being required at higher temperatures. Depending upon the catalyst type, its concentration and the alkoxysilane used, hydrolysis may be complete by the time a single phase is obtained, or additional time may be required to complete hydrolysis. In general, the mixture is agitated for 10 minutes to 2 hours after a single phase is obtained to complete the hydrolysis reaction. The temperature at which hydrolysis is conducted is preferably from 15'C to 100°C, more preferably from 20°C to 50°C and most preferably from 20°C to 25°C. Hydrolysis rates increase with increasing temperatures. Alternatively, the hydrolysis may be conducted in the absence of a catalyst. In this procedure, the alkoxysilane is mixed with water and stirred for a sufficient period of time for the desired extent of hydrolysis to occur. This method may take up to several days dependent upon the alkoxysilane and the temperature at which hydrolysis occurs. In some applications this method may be preferred when residual catalyst levels have an adverse effect on subsequent use of the alkoxysilane. The following examples are set forth to illustrate the present invention and should not be construed to limit its scope. In the examples, all parts and percentages are by weight unless otherwise indicated. Example 1 12.5 g (0.0503 mol) of 3-Methacryloxypropyl-trimethoxysilane (MOPS) containing 29 ppm HCl, and 1.09 g (0.0604 mol) deionized and microfiltered water (pH 6.8) (40 percent of theoretical needed for complete hydrolysis) is combined in a 2 oz. bottle. The two-phase mixture is agitated at 23°C. Hydrolysis proceeds and a single phase is produced in 8 minutes. Proton NMR (DCCI3; by measuring methanol by-product formation) indicatesthat hydrolysis is complete in an additional 8 to 5 minutes. At 15, 30, and 60 minute reaction times, 1.0 g samples are removed and diluted with 39.0 g methanol to give solutions at 2.5 weight percent solids. Approximately 10 mLs of the solution are dispensed with a syringe through a 0.5 micron filter onto oxidized silicon wafers rotating at 3000 RPM. The morphology of the resulting residue is observed with optical microscopy. CYCLOTENE'" 3022 resin, (a formulation manufactured by The Dow Chemical Company of tetramethyldivinylsiloxane bisbenzocyclobutene resin in mesitylene containing 4.0 weight percent (based on solids) AgeRite" MA antioxidant (manufactured by B.F. Goodrich)) is subsequently applied at a thickness of 10 microns, and cured at 250°C for one hour. Delamination of the cured coatings is evaluated by microindentation (as described in The Determination of Bond Strength of Polymeric Films by Indentation Debonding by H.D. Conway and J.P.R. Thomsin, in J. Adhesion Sei. Technol. 3, 227, 1988). Values of bond strength are obtained from the level of delamination observed by optical microscopy. The effects of water level and reaction time on adhesion performance of methanol-based hydrolyzed MOPS adhesion promoters were observed. After application of the adhesion promoter, the morphology of the deposited residue was discontinuous, appearing in the form of droplets. In a similar fashion, adhesion promoter samples are prepared based on water levels which corresponded to 20, 60, 80, and 100 percent hydrolysis. Results are given in Table I. TABLE 1 Water Reaction Time Adhesion Morphology (%) (min) (MPa) 20 15 droplets 187 ± 3.9 20 30 droplets 172 ± 1 1.6 20 60 droplets 171 ± 3.1 40 15 droplets 187 ± 7.7 40 30 droplets 192 ± 2.4 40 60 droplets 191 ± 7.7 60 15 droplets 60 30 droplets 178 ± 8.2 60 60 droplets 152 ± 8.7 80 15 droplets 172 ± 3.8 80 30 droplets 162 ± 12.9 80 60 droplets 141 ± 9.7 100 15 droplets 126 ± 3.9 100 30 droplets 118 ± 3.7 100 60 droplets 124 ± 3.7 No promoter No promoter 73 ± 4.8 Example 2 A partially hydrolyzed MOPS is prepared using the same techniques used in Example 1 (40 percent water). After 1 hour reaction time at ambient temperature, portions of the neat hydrolyzed alkoxysilane are added to 5 percent solutions of Cydotene" 3022 in mesitylene to yield a series of adhesion promoter solutions in amounts to give solutions containing 0.5, 1.0, 2.5, and 5.0 percent of the hydrolyzed alkoxysilane. Each solution is evaluated for processability and adhesion performance to thermally oxidized silicon wafers (microindentation). Results are given in Table II. TABLE II Hydrolyzed MOPS Film-Forming Adhesion Concentration Ability (MPa) (wt%) 0.5 film-forming 206 ± 4.0 1.0 film-forming 183 ± 8.1 2.5 film-forming 184 ± 6.6 5.0 film-forming 198 ± 3.0 2.5% in isopropanol droplets 195 ± 6.2 2.5% in methanol droplets 204 ± 6.5 Hydrolyzed MOPS adhesion promoter formulations containing CYCLOTENE'" 3022 in mesitylene provide film forming compositions with good adhesion performance. Example 3 A partially hydrolyzed MOPS is prepared using the same conditions used in Example 1 (40 percent water). After 1 hour reaction time at 23°C, 0.10 g (0.1 weight percent) of the neat partially hydrolyzed MOPS is added to 100.0 g of the following dry etchable BCB formulation: 63.00 g 1,3-bis(2-bicyclo(4.2.0)octa-1,3,5-trien-3-ylethenyl)-1,1,3,3-tetramethyl disiloxane resin 2.63 g (poly)-1,2-dihydro-2,2,4-trimethylquinoline 34.37 g mesitylene The adhesion promoter and dry etchable BCB solution are shaken and allowed to stand until bubbles from the agitation are gone. This produces a self -primed dry etchable formulation with 0.1 percent of the adhesion promoter. Additional self-primed dry etchable formulations with 0.2, 0.5, and 1.0 percent of the adhesion promoter are prepared similarly by adding the appropriate amount of the neat partially hydrolyzed MOPS to 100.0 g samples of the dry etchable BCB formulation defined above. The dry etchable formulations are spin coated on 4 inch silicon wafers containing thermal oxide. Control formulations are also run containing no adhesion promoter(Comparative Examples). The wafers are then cured under nitrogen using the following ramped cure schedule: 5 minutes from approximately 23°C to 100°C, 15 minutes at 100°C; 15 minutes from 100°C to 150°C; 15 minutes at 150°C; 60 minutes from 150°C to 210°C; 40 minutes at 210°C. Adhesion performance is measured by micromdention measurements Results are given in Table III. TABLE III Hydrolyzed MOPS Concentration (wt%) Film Thickness (μm) Adhesion (MPa) 0 * 10 4 67.6 ± 5.9 0 * 10.2 68 4 ± 2.5 0.1 10.3 156.3 ± 3.4 0.1 10 6 164.9 ± 6.0 0.2 10.6 153.1 ± 4.5 0.2 10.4 163.6 ± 2.8 0.5 9.5 158 9 ± 3.8 0.5 10.3 177 9 ± 1 7 1.0 10.5 177.2 ± 4.2 1.0 10 7 183 9 ± 7 9 * Comparative Examples A self-priming CYCLOTENE'" 3022 formulation containing hydrolyzed MOPS adhesion promoter has considerably improved adhesion performance. Example 4 A partially hydrolyzed MOPS is prepared using the same conditions used in Example 1 (40 percent water) After 1 hour reaction time at ambient temperature, 0 084 g portions of the neat hydrolyzed MOPS are added to the following photosensitive BCB formulation: 14.93 g 1 ,3-bιs(2-bιcydo(4.2.0)octa- 1 ,3,5-trιen-3-ylethenyl)-1 , 1 ,3,3-tetramethyl disiloxane resin 0.31 g 2,6-bιs(4-azιdobenzyiιdene)-4-methylcyclohexanone 0.116 g 4,4 -diazιdophenyl sulfone 0.116 g 1,2-dihydro-2,2,4-trιmethylquιnoline 17.3 g mesitylene The adhesion promoter and photosensitive BCB solution were shaken and allowed to stand until bubbles from the agitation were gone This produces a self-priming photosensitive formulation with 0.5 percent of the hydrolyzed MOPS coupling agent This solution is compared to the unpπmed solution for stability, processabiiity, and adhesion performance to thermally oxidized silicon wafers (micromdention) (Comparative Example). Results are given in Table IV Table IV Hydrolyzed MOPS Concentration (wt%) Film Thickness (μm) Adhesion (MPa) 0.5 11.91 291 ± 9.0 0.5 11.96 289 ± 4.7 Comparative Example 0 11.71 98 ± 3.3 0 11.84 101 ± 1.6 0 Self-priming photodef ineable benzocyclobutene formulations containing hydrolyzed MOPS adhesion promoter provide substantial adhesion enhancement. Example 5 5 12.5 g (0.0503 mol) of 3-Methacryloxypropyl-trimethoxysilane (MOPS), 1.09 g (0.0604 mol) of 0.01 N aqueous HCl and 40 percent of the theoretical amount of deionized and microf iltered water (pH 6.8) needed for total hydrolysis are combined in a 2 oz. bottle. This acid level represents 30 ppm HCl in the hydrolyzed MOPS. The two-phase mixture is stirred at ambient temperature (23°C). Hydrolysis proceeds such that a single phase is produced in 8 o minutes. In the absence of the 30 ppm HCl, the mixture does not clearto one phase (little or no reaction) even after 48 hours. The experiment is repeated using 0.0050 N (15 ppm HCl) and 0.0025 N HCl (7.5 ppm HCl) and 0.0100, 0.0050, and 0.0025 N H 2 S0 . Results are given in Table V. TABLE V 5 Acid Concentration Time to Form Single Phase(min) (N) HCl H 2 S0 4 0.0100 8 8 0.0050 14 20 0.0025 44 75 The experiment is repeated to define the hydrolysis temperature, HCl catalyst level, time required to form a single phase and time required for complete hydrolysis (40 percent of theoretical). Proton NMR is used to measure time for complete hydrolysis; single phase times are observed visually. Results are given in Table VI. TABLE VI Reaction Single Phase Complete HCl conc(ppm) Temp.(°C) (min.) Hydrolysis (min.) 0 23 4320 8640 0 40 1140 2460 6 23 40 60 15 23 15 60 30 23 8 40 30 30 5 30 30 35 4 20 The single phase and complete hydrolysis columns refer to the amount of time required to reach these conditions. Although hydrolysis will occur in the absence of HCl, the reaction time is significantly shortened by the presence of trace amounts of HCl. The reaction temperature also greatly effects the time needed for the hydrolysis reaction, wherein higher temperatures decrease the amount of time significantly. Example 6 12.5 g (0.0565 mol) of 3-Aminopropyi-triethoxysilane (3-APS) and 1.22 g (0.0678 mol) deionized and microfiltered water (pH 6.8; 40 percent of theoretical needed fortotal hydrolysis) are combined in a 2 oz. bottle. The two-phase mixture is stirred magnetically at ambient temperature (23°C). Hydrolysis proceeds such that a single phase is produced in 60 minutes. Proton NMR (DMSO-d 6 ; by following ethanol formation) indicates that hydrolysis is essentially complete at 60 minutes. This material is used to make a self-priming formulation similar to that of Example 3. Example 7 11.87 g (0.0478 mol) of 3-Methacryloxy-propyltrimethoxysilane (MOPS), 0.56 g (0.00251 mol) of 3-aminopropyltriethoxysilane (3-APS); (MOPS/3-APS = 95/5 mol ratio) and 1.08 g (0.0604 mol) of deionized and microfiltered water (pH 6.8; 40 percent of theoretical needed fortotal hydrolysis) are combined in a 2 oz. bottle. The two-phase mixture is stirred at ambient temperature (23°C). Hydrolysis proceeds such that a single phase is produced in 25 minutes. Proton NMR (DMSO-d 6 ; by following ethanol formulation) indicates that hydrolysis is essentially complete at 30 minutes. Example 8 10.0 g (0.0657 mol) Vinyltrimethoxysilane and 1.46 g (0.081 1 mol) aqueous 0.01 N HCl, and 40 percent of the theoretical amount needed fortotal hydrolysis of deionized and microfiltered water (pH 6.8); are combined in a 2 oz. bottle. The two-phase mixture is stirred at ambient temperature (23 G C). Hydrolysis proceeds such that a single phase is produced in 1 minute. Proton NMR (DCCI3) indicates that hydrolysis is essentially complete in 20 minutes. A film forming formulation is prepared as in Example 2 using 2.5 percent of the 40 percent hydrolyzed vinyltrimethoxysilane, 5.0 percent Cydotene'" 3022, and 92.5 percent of mesitylene. The solution is evaluated for processability and adhesion performance to thermally oxidized silicon wafers by microindentation as in Example 2. The formulation is film forming and adhesion is 244 MPa. Example 9 10.0 g (0.0616 mol) of Allyltrimethoxysilane , 1.33 g (0.0739 mol) aqueous 0.01 N HCl and 40 percent of the theoretical amount needed for total hydrolysis of deionized and microfiltered water (pH 6.8); are combined in a 2 oz. bottle. The two-phase mixture is stirred at ambient temperature (23°C). Hydrolysis proceeds such that a single phase is produced in 3 minutes. Proton NMR (DCCI ) indicates that hydrolysis is essentially complete in 60 minutes. A film forming adhesion promoter formulation is prepared as in Example 8 using 2.5 weight percent of the 40 percent hydrolyzed allyltrimethoxysilane, 5.0 weight percent Cydotene'" 3022, and 92.5 weight percent of mesitylene. The solution is evaluated for processability and adhesion performance to thermally oxidized silicon wafers by microindentation as in Example 2. The formulation is film forming and the adhesion is 147 MPa. Example 10 The following formulation is made to hydrolyze the methyl esters on 3- methacryloxypropyltrimethoxy-silane (MOPS) : 48.06 g MOPS 48.06 g Methanol 4.81 g Water 0.96 g Trifluoroacetic Acid The formulation is allowed to stand at room temperature for 24 hours then filtered through Strong Base Resin Ion Exchange Beads (Dowex'" SBR-OH Anion OH Exchange Resin manufactured by The Dow Chemical Company) to remove the trifluoroacetic acid. 90.35 g of methanol is added during the filtration to rinse the solution from the beads completely. This material is placed in a vacuum evaporation flask in a warm water bath and the methanol is removed to leave the residual hydrolyzed MOPS. The hydrolyzed MOPS is added at 0.5 weight percent relative to solids to a 63 percent solids formulation of Cydotene'" 3022 in mesitylene. The resultant self-primed solution is deposited by spin-coating onto a thermally oxidized silicon wafer to a thickness of 12.4 μm. The adhesion is measured by microindentation and measures 160.5 MPa +_ 4.2 MPa. This value is an improvement when compared with typical values of 70 MPa obtained with non-primed resin. Example 1 1 A partially hydrolyzed MOPS is prepared using the same conditions used in Example 1 (40 percent water). After 1 hour reaction time at 23°C, 0.20 g (0.2 weight percent) of the neat partially hydrolyzed MOPS is added to 100.0 g of the following photosensitive BCB formulation: 45.00 g 1,3-bis(2-bicyclo(4.2.0)octa-1,3,5-trien-3-ylethenyl)-1,1,3,3-tetramethyl disiloxane resin 1.12 g 2,6-bis(4-azidobenzylidene)-4-ethylcydohexanone 1.47 g (poly)-1,2-dihydro-2,2,4-trimethylquinoline 52.41 g mesitylene The adhesion promoter and photosensitive BCB solution are shaken and allowed to stand until bubbles from the agitation are gone. This produces a self-primed photosensitive formulation with 0.2 percent of the adhesion promoter. A second self-primed photosensitive formulation with 0.5 percent of the adhesion promoter is prepared similarly by adding 0.50 g of the neat, partially hydrolyzed MOPS to a second 100.0 g sample of the photosensitive BCB formulation defined above. The self-primed formulations are spin coated on 4 inch silicon wafers containing thermal oxide, on which, half of the wafer contains a thin coating of sputtered aluminum. Control formulations are also run containing no adhesion promoter. After spin coating, the films are prebaked at 75°C for 2 minutes on a hot plate and then exposed through a test mask at a 365 nm wavelength using a 200 millijoules per square centimeter (mJ/cm 2 ) exposure dose. The image is produced using puddle development with a 32.5/67.5 solvent blend of Proglyde DMM/lsopar L. The wafers are then cured under nitrogen using the following ramped cure schedule: 5 minutes from approximately 23°C to 100°C, 15 minutes at 100°C; 15 minutes from 100°Cto 150°C; 15 minutes at 150°C; 60 minutes from 150°C to 210°C; 40 minutes at 210°C. Adhesion performance is measure by microindention measurements. Results are given in Table VII. TABLE VII Hydrolyzed MOPS Film Thickness Adhesion to Silicon Adhesion to Concentration (wt%) (μm) (MPa) Aluminum (MPa) 0 * 5.32 272.1 ± 2.9 70.1 ± 0.1 0 * 5.43 274.9 ± 2.0 66.5 ± 1.0 0.2 5.21 324.9 ± 3.5 331.9 ± 2.8 0.2 5.16 329.9 ± 4.9 329.5 ± 1.0 0.5 5.17 333.3 ± 5.9 369.3 ± 0.1 0.5 5.34 368.9 ± 0.9 383.0 ± 5.5 * Comparative Examples Adhesion to both Silicon and Aluminum is improved with the hydrolyzed MOPS composition. Example 12 A partially hydrolyzed MOPS is prepared using the same conditions used in Example 1 (40 percent water). After 1 hour reaction time at 23°C, 0.20 g (0.2 weight percent) of the neat partially hydrolyzed MOPS is added to 100.0 g of the following photosensitive BCB formulation: 38.00 g 1 ,3-bis(2-bicyclo(4.2.0)octa-1 ,3,5-trien-3-ylethenyl)-1 , 1 ,3,3-tetramethyl disiloxane resin 0.96 g 2,6-bis(4-azidobenzylideπe)-4-ethylcydohexanoπe 2.15 g 2,2-bis(4-(4-azidophenoxy)-phenyl)-propane 1.71 g (poly)-1,2-dihydro-2,2,4-trimethyl-quinoline 57.18 g mesitylene The adhesion promoter and photosensitive BCB solution are shaken and allowed to stand until bubbles from the agitation are gone. This produces a self-primed photosensitive formulation with 0.2 percent of the adhesion promoter. A second self-primed photosensitive formulation with 0.5 percent of the adhesion promoter is prepared similarly by adding 0.50 g of the neat, partially hydrolyzed MOPS to a second 100.0 g sample of the photosensitive BCB formulation defined above. The self-primed formulations are spin coated on 4 inch silicon wafers containing thermal oxide, on which, half of the wafer contains a thin coating of sputtered aluminum. Control formulations are also run containing no adhesion promoter. After spin coating, the films are prebaked at 75°C for 2 minutes on a hot plate and then exposed through a test mask at a 365 nm wavelength using a 200 mJ/cm 2 exposure dose. The image is produced using puddle development with a 32.5/67.5 solvent blend of Proglyde DMM/lsopar L. The wafers are then cured under nitrogen using the following ramped cure schedule: 5 minutes from approximately 23°C to 100°C, 15 minutes at 100°C; 15 minutes from 100°C to 150°C; 15 minutes at 150°C; 60 minutes from 150°C to 210°C; 40 minutes at 210°C. Adhesion performance is measure by microindention measurements. Results are given in Table VIII. TABLE VIII 5 Hydrolyzed MOPS Film Thickness Adhesion to Silicon Adhesion to Concentration (wt%) (μm) (MPa) Aluminum (MPa) 0 * 9.91 442.1 ± 8.6 62.8 ± 0.5 0 * 9.67 489.6 ± 3.9 61.5 ± 0.3 0.2 9.66 626.4 ± 1.0 558.4 ± 3.7 10 0.2 9.76 577.8 ± 5.8 542.1 ± 8.6 0.5 9.80 602.0 ± 3.4 582.3 ± 2.9 0.5 9.59 569.6 ± 2.2 549.2 ± 9.6 * Comparative Examples - .. Adhesion to both Silicon and Aluminum is improved with the hydrolyzed MOPS composition. Example 13 The formulation preparation procedures of Example 12 are repeated using 0.2 and 0.5 percent adhesion promoter in the following dry etchable BCB formulation: 63.00 g 1,3-bis(2-bicydo(4.2.0)octa-1,3,5-trien-3-ylethenyl)-1,1,3,3-tetramethyl disiloxane resin 20 2.63 g (poly)-1,2-dihydro-2,2,4-trimethyl-quinoline 34.37 g mesitylene The dry etchable formulations are spin coated on 4 inch silicon wafers containing thermal oxide. Control formulations are also run containing no adhesion -,r promoter(Comparative Examples). The wafers are then cured under nitrogen using the following ramped cure schedule: 5 minutes from approximately 23°C to 100°C, 15 minutes at 100°C; 15 minutes from 100°C to 150°C; 15 minutes at 150°C; 60 minutes from 150°Cto 210°C; 40 minutes at 210°C. Adhesion performance is measured by microindention measurements. Results are ,- listed in Table IX. 5 TABLE IX Hydrolyzed MOPS Film Thickness Adhesion to Silicon Adhesion to Concentration (wt%) (μm) (MPa) Aluminum (MPa) 0 * 9.44 74.1 ± 2.9 37.7 ± 1.5 0* 9.64 79.0 ± 3.7 42.1 ± 0.9 0.2 9.57 174.6 ± 2.7 80.2 ± 0.3 0.2 9.41 127.2 ± 3.4 69.8 ± 0.2 0.5 9.57 144.5 ± 0.6 84.7 ± 0.1 0.5 9.58 129.3 ± 0.9 84.3 ± 4.5 * Comparative Examples Adhesion to both Silicon and Aluminum is improved with the hydrolyzed MOPS composition. Example 14 3-Aminopropyltriethoxysilane (3-APS), (0.10 g, 0.2 weight percent) is added to 49.9 g of the same dry etchable BCB formulation of Example 13. The adhesion promoter and dry etchable BCB solution are shaken and allowed to stand until bubbles from the agitation are gone. This produces a self-primed dry etchable formulation with 0.2 percent of the adhesion promoter. A second self-primed dry etchable formulation with 0.5 percent of the adhesion promoter is prepared similarly by adding 0.25 g of the 3-APS to a second 49.9 g sample of the dry etchable BCB formulation. The dry etchable formulations are spin coated on 4 inch silicon wafers containing thermal oxide, on which, half of the wafer contains a thin coating of sputtered aluminum and cured as in Example 12. Adhesion performance is measured by microindention measurements. Results are listed in Table X. TABLE X 3-APS Concentration Film Thickness Adhesion to Silicon Adhesion to (wt%) (μm) (MPa) Aluminum (MPa) 0* 9.82 62.0 ± 1.3 32.8 ± 0.9 0* 9.76 65.9 ± 0.2 32.6 ± 0.3 0.2 9.84 115.8 ± 2.2 35.7 ± 1.3 0.2 9.82 123.5 ± 1.7 36.8 ± 1.9 0.5 9.88 110.9 ± 3.7 50.6 ± 1.5 0.5 9.44 111.6 ± 0.9 41.9 ± 3.4 * Comparative Examples Adhesion to both Silicon and Aluminum is improved with the 3-APS composition.

Claims: CLAIMS: 1. A composition comprising: a) a hydrolyzed or partially hydrolyzed alkoxysilane, b) a solvent, and c) an arylcyclobutene. 2. The composition of Claim 1 wherein the alkoxysilane is of the formula: z Y-R-Si-OR ' I z wherein R is Ci-Cε alkylidene, Ci-Cβ alkylene, arylene, or a direct bond; Y is C>-Cβ alkyl, C 2 -C6 alkenyl, aryl, 3-methacryloxy, 3-acryloxy, 3-aminoethylamino, or 3-amino; R' is independently in each occurrence Ci-Cβ alkyl; and Z is C^ alkyl, C 2 -C6 alkenyl or OR'. 3. The composition of Claim 2 wherein Y is 3-methacryloxy, 3-amino, 3- aminoethylamino, allyl or vinyl. 4. The composition of Claim 3 wherein the alkoxysilane is 3- methacryloxypropyltrimethoxy-silane. 5. The composition of Claim 3 wherein the alkoxysilane is 3- aminopropyltriethoxysilane. 6. The composition of Claim 1 wherein the solvent is an aromatic hydrocarbon, an aprotic solvent, a ketone, ester, ether or mixture thereof. 7. The composition of Claim 6 wherein the solvent is mesitylene, toluene, xylene, or alkylnaphthalene. 8. The composition of Claim 7 wherein the solvent is mesitylene. 9. The composition of Claim 1 wherein the arylcyclobutene is a benzocydobutene. 10. The composition of Claim 9 wherein the benzocydobutene is a prepolymer. 1 1. The composition of Claim 10 wherein the prepolymer is tetramethyldivinylsiloxane-bisbenzocyclobutene prepolymer. 12. The composition of Claim 1 wherein the hydrolyzed or partially hydrolyzed alkoxysilane is from 0.01 to 10 weight percent, the solvent is from 10 to 99.9 weight percent, and the arylcyclobutene is 0.01 to 90 weight percent, said weight percents being based on the total weight of the composition. 13. The composition of Claim 12 wherein the hydrolyzed or partially hydrolyzed alkoxysilane is from 0.2 to 5 weight percent, the solvent is from 40 to 99.5 weight percent, and the arylcyclobutene is from 1 to 80 weight percent, said weight percents being based on the total weight of the composition. 14. The composition of Claim 1 which additionally contains one or more photocrosslinking agents. 15. The composition of Claim 14 wherein the photocrosslinking agent is a bis- (arylazide). 16. The composition of Claim 15 wherein the bis-(arylazide) is 2,6- bis(4azidobenzylidene)-4-ethylcydohexanone or 2,2-bis(4-(4-azidophenoxy)-phenyl)propane. 17. The composition of Claim 1 which also contains an antioxidant. 18. A composition comprising a) an alkoxysilane which is readily hydrolyzed self-catalytically, b) a solvent, and c) an arylcyclobutene. 19. The composition of Claim 18, wherein the alkoxysilane is 3- aminopropyltriaikoxysilane or 3-aminoethylamino-propyltrialkoxysilane. 20. The composition of Claim 19, wherein the alkoxysilane is 3- aminopropyltriethoxysilane. 21. The composition of Claim 18 wherein the alkoxysilane is from 0.01 to 10 weight percent, the solvent is from 10 to 99.9 weight percent, and the arylcyclobutene is 0.01 to 90 weight percent, said weight percents being based on the total weight of the composition. 22. The composition of Claim 18 wherein the solvent is mesitylene, toluene, xylene, or alkylnaphthalene. 23. The composition of Claim 22 wherein the solvent is mesitylene. 24. The composition of Claim 18 wherein the arylcyclobutene is a benzocydobutene. 25. The composition of Claim 24 wherein the benzocydobutene is a prepolymer. 26. The composition of Claim 25 wherein the prepolymer is tetramethyldivinylsiloxane-bisbenzocydo-butene prepolymer. 27. A soiventless process for hydrolyzing an alkoxysilane of the formula: wherein R is C C6 alkylidene, C«-C 6 alkylene, arylene, or a direct bond; Y is C Cβ alkyl, C 2 -C 6 alkenyl, aryl, 3-methacryloxy, or 3-acryloxy,; R' is independently in each occurrence alkyl; and Z is Cι-C 6 alkyl, C 2 -C 6 alkenyl or OR', comprising adding sufficient water to hydrolyze at least one of the alkoxy groups, optionally in the presence of an acidic or basic catalyst. 28. The process of Claim 27 wherein the alkoxysilane is 3- methacryloxypropyltrialkoxysilane. 29. The process of Claim 27 wherein the catalyst is an acidic catalyst. 30. The process of Claim 29 wherein the catalyst is selected from the group consisting of hydrochloric acid, sulfuric acid, methanesulfonic acid and phosphoric acid. 31. The process of Claim 30 wherein the catalyst is hydrochloric acid. 32. The process of Claim 27 wherein the catalyst is a basic catalyst. 33. The process of Claim 27 in the absence of an acidic or basic catalyst.

Inventors: FRYE DONALD C, HARRIS ROBERT F, SCHMIDT DONALD L, TOWNSEND PAUL H III, FRYE, DONALD, C., HARRIS, ROBERT, F., SCHMIDT, DONALD, L., TOWNSEND, PAUL, H., III
Applicants: DOW CHEMICAL CO, THE DOW CHEMICAL COMPANY
Application year: 1995
Main classification: C09D183
IPC codes: C09D165, C09D183