| PATENT NUMBER | This data is not available for free |
| PATENT GRANT DATE | September 11, 2001 |
| PATENT TITLE |
Polyphenylene oligomers and polymers |
| PATENT ABSTRACT | An oligomer, uncured polymer or cured polymer comprising the reaction product of one or more polyfunctional compounds containing two or more cyclopentadienone groups and at least one polyfunctional compound containing two or more aromatic acetylene groups wherein at least some of the polyfunctional compounds contain three or more reactive groups. Such oligomers and uncured polymers may be cured to form cured polymers which are useful as dielectrics in the microelectronics industry, especially for dielectrics in integrated circuits |
| PATENT INVENTORS | This data is not available for free |
| PATENT ASSIGNEE | This data is not available for free |
| PATENT FILE DATE | March 31, 1999 |
| PATENT REFERENCES CITED |
Dilthey et al., "On Tetraphenylcyclopentadienone and its Reduction Products, " J. Prakt. Chem., vol. 139, pp. 1-16 (1933). Havens et al. "Improved syntheses of Benzils as Polymer Intermediates,"Journal of Polymer Science, Polymer Chemistry Edition, vol. 19, pp. 1349-1356 (1981). Hyatt, "Synthesis of a Hexaalkynylhexaphenylbenzene,"Org. Prep. Proced. Int., vol. 23, No. 4, pp. 460-463 (1991). Jones et al. "Synthesis and characterization of multiple phenylethynybenzenes via cross-coupling with activated palladium catalyst, " Polymer, vol. 36, No. 1, pp. 187-192 (1995). Kumar et al., "Diels-Alder Polymerization between Bis(cyclopentadienones) and Acetylenes. A Versatile Route to New Highly Aromatic Polymers," Macromolecules, vol. 28, pp. 124-130 (1995). Kumar et al., "Hybrid Polyimide-Polyphenylenes by the Diels-Alder Polymerization Between Biscyclopentadienones and Ethynyl-Terminated Imides, " Acs Symp. Ser. vol. 614, pp. 518-526 (1995). Kumar et al., "The Diels-Alder Polymerization of Biscyclopentadienones and Ethynyl Terminated Imides," Polymeric Materials Science and Engineering, vol. 72, pp. 444-445 (1995). Morgenroth et al. "Polyphenylene Dendrimers: From Three-Dimensional Structures," Angew. Chem. Int. Ed. Engl., vol. 36, No. 6, pp. 631-634 (1997). Mukamal et al., "Diels-Alder Polymerizations: Polymers Containing Controlled Aromatic Segments," Polym. Prepr., vol. 8, pp. 496-500 (1967). Mukamal et al., "Diels-Alder Polymers. III. Polymers Containing Phenylated Phenylene Units, " Journal of Polymer Science, vol. 5, pp. 2721-2729 (1967). Ogliaruso et al., "Bistetracyclones" and "Bishexaphenylbenzenes," J. Org. Chem., vol. 28, pp. 2725-2728 (1963). Ogliaruso et al., "Bistetracyclones and Bishexaphenylbenzenes," J. Org. Chem., vol. 30, pp. 3354-3360 (1965). Ogliaruso et al., "Chemistry of Cyclopentadienones," Chemical Reviews, vol. 65, pp. 261-367 (1965). Reinhardt et al., "Pendant Oxy and Thioarylene Aromatic Heterocyclic Polymers, " Polym. Prepr., vol. 23, pp. 119-120 (1982). Reinhardt et al., "Phenylated Aromatic Heterocyclic Polyphenylenes Containing Pendant Diphenylether and Diphenylsulfide Groups, " Polym. Sci. Technol., vol. 25, pp. 41-53 (1984). Sastriet al., "Cure kinetics of a multisubstituted acetylenic monomer, " Polymer, vol. 36, No. 7, pp. 1449-1454 (1995). Stille, "Aromatic Polymers: Single-and Double-Stranded Chains, " J. Macromol. Sci.-Chem., vol. 3, pp. 1043-1065 (1969). Stille et al., "Cantenation and Kinetics of the Diels-Alder Step-Growth Reaction in the Synthesis of Phenylated Polyphenylenes," Macromolecules, vol. 5, pp. 49-55 (1972). Stille et al., "Diels-Alder Polymerizations: Polymers Containing Controlled Aromatic Segments," J. Polym. Sci., vol. 4, pp. 791-793 (1966). Stille et al., "Diels-Alder Polymerizations. IV. Polymers Containing Short Phenylene Blocks Connected by Alkylene Units," Macromolecules, vol. 1, pp. 431-436 (1968). Tour, "Soluble Oligo-and Ployphenylenes," Advanced Materials, vol. 6, No. 3, pp. 190-198 (1994). Wrasidlo et al., "Preparation of Poly(Octaphenyl-Tetraphenylene)," J. Polym. Sci., vol. 7, pp. 519-523 (1969). Eisenberg et al., Aromatic lonomer Membranes: Synthesis, Structure and Properties, Contemp. Top. Polym. Sci., vol. 5, pp. 375-400 (1984). Mehta et al., Synthesis and Characterization of Polymides Prepared via Diels-Alder Polymerization of a Bistetraphenylcyclopentadienone and Various Bisacetylenes, Polym. Prepr. (Am. Chem. Soc., Div. Polym. Chem.), vol. 36(1), pp. 505-506 (1995) --Chemical Abstract. Harris et al., Phenylated Polymides--{poly[oxy-6-2(1,3-dioxo-4,5,7-triphenylisoindolinediyl)-1,4-phe nyleneoxy-1,4-phenylene-2,6-(1,3-dioxo-4,5,7-triphenylisoindolinediyl)-1,4- phenylene]}, Macromol. Synth., vol. 8, pp. 75-78 (1982)--Chemical Abstract. Dineen et al., Synthesis of Diels-Alder Polymers via Benzyne Intermdiates, Polym Prepr., Am. Chem. Soc., Div. Polym. Chem., vol. 19(2), pp 34-9 (1978)--Chemical Abstract. Harvey et al., Synthesis and Electronic Spectra of Substituted Bis(hexaphenylbenzenes), J. Chem. Eng. Data, vol. 22(1), pp. 110-113 (1977)--Chemical Abstract. Harvey et al., Synthesis, Electronic Spectra, and Thermal Behavior of Bis(heptaphenylcycloheptatrienes), J. Org. Chem., vol. 41(21), pp 3374-3377 (1976)--Chemical Abstract. Stille et al., The Crosslinking of Thermally Stable Aromatic Polymers by Aryl Cyanate Cyclotrimerization, Macromolecules, vol. 9(3), pp. 516-523 (1976)--Chemical Abstract. Harris et al., Soluble Aromatic Polyimides. The Polymerization of Phenylated Bis(phthalic anhydrides) with Diamines, Appl. Polym. Symp., vol. 26 (Polym. Polcondensat), pp. 421-428 (1975)--Chemical Abstract. Harris et al., Soluble Aromatic Polyimides from Phenylated Dianhydrides, J. Polym Sci., Polym. Lett. Ed., vol. 13(5), pp. 283-285 (1975)--Chemical Abstract. Stille et al., Catenation and Kinetics of the Diess-Alder Step-growth Reaction in the Synthesis of Phenylated Polyphenylenes, Macromolecules, vol. 5(1), pp. 49-55 (1972)--Chemical Abstract |
| PATENT PARENT CASE TEXT | This data is not available for free |
| PATENT CLAIMS |
What is claimed is: 1. An oligomer, uncured polymer, or cured polymer having the formula: ##STR39## wherein P has the repeat structure: ##STR40## and wherein G has the structure: ##STR41## wherein R.sup.1 and R.sup.2 are independently H or unsubstituted or inertly substituted aromatic moieties, Ar.sup.4 is an aromatic moiety or an inertly substituted aromatic moiety, y and z are integers greater than or equal to 1 with the proviso that y+z is greater than or equal to 3, n and m are integers greater than or equal to 0 with the proviso that n+m is greater than or equal to 1. 2. An oligomer, uncured polymer or cured polymer composition comprising compounds having the formula: ##STR42## wherein Ar.sup.4 is an aromatic moiety or an inertly-substituted aromatic moiety, R.sup.1 and R.sup.2 are independently H or an unsubstituted or inertly-substituted aromatic moiety and x is an integer from 1 to about 50, wherein the composition is free of compounds having two or more cyclopentadienone groups and compounds having two or more acetylene groups. 3. An oligomer, uncured polymer or cured polymer composition consisting of compounds having the same formula: ##STR43## wherein Ar.sup.4 is an aromatic moiety or an inertly-substituted aromatic moiety, R.sup.1 and R.sup.2 are independently H or an unsubstituted or inertly-substituted aromatic moiety and x is an integer from 1 to about 50 and, optionally, one or more materials selected from the group consisting of organic solvent, adhesion promoter, reinforcing fibers or mats, fillers, pigments, lubricating polymers, and conductive particles. |
| PATENT DESCRIPTION |
BACKGROUND OF THE INVENTION This invention relates to polyphenylene oligomers and polymers and processes for preparing and using the same. Such oligomers and polymers may be useful as dielectric resins in microelectronics fabrication. Polymer dielectrics may be used as insulating layers between various circuits and layers within circuits in microelectronic devices such as integrated circuits, multichip modules, laminated circuit boards and the like. The microelectronics fabrication industry is moving toward smaller geometries in its devices to enable lower power and faster speeds. As the conductor lines become finer and more closely packed, the requirements of the dielectrics between such conductors become more stringent. While polymer dielectrics often provide lower dielectric constants than inorganic dielectrics such as silicon dioxide, they often present challenges to process integration during fabrication. For example, to replace silicon dioxide as a dielectric in integrated circuits, the dielectric must be able to withstand processing temperatures during metallization and annealing steps of the process. Preferably, the dielectric material should have a glass transition temperature greater than the processing temperature. The dielectric must also retain the desirable properties under device use conditions. For example, the dielectric should not absorb water which may cause an increase in the dielectric constant and potential corrosion of metal conductors. For some integration schemes, the oligomer should preferably planarize and gap fill a patterned surface when applied by conventional application techniques such as spin coating. Currently, polyimide resins are one class of materials which are employed as thin film dielectrics in the electronics industry. However, polyimide resins may 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. Kumar and Neenan, in Macromolecules, 1995, 28, pp 124-130, disclose numerous polyphenylenes made from biscyclopentadienones and bisacetylenes. They teach that the polyphenylenes have potential as photodefineable organic dielectrics. Wrasidlo and Augl, in J. Polym. Sci., Part B (1969), 7(7), 519-523, disclose the copolymerization of 1,4-bis(phenylethynyl)benzene with 3,3'-(1,4-phenylene)-bis(2,4,5-triphenylpentadienone). They report a soluble, yellow, infusible polymer was obtained. The materials described in Kumar and Wrasidlo are soluble but may not be suitable for some uses such as spin coating to fill gaps because the materials were polymerized to exhaustion of the cyclopentadienone moieties which provides relatively high molecular weights. The molecular weight may be too high to permit application by spin coating over a patterned surface containing gaps to be filled by the dielectric. Based on the reported glass transition temperatures, such materials may not be able to withstand the processing desired for interlayer dielectrics in integrated circuits. In U.S. Pat. Nos. 5,334,668; 5,236,686; 5,169,929; and 5,338,823, Tour describes several methods of preparing cross-linkable polyphenylene compositions for the preparation of glassy carbon. The polyphenylenes are made by polymerizing 1-bromo-4-lithiobenzene to form a brominated polyphenylene and then coupling substituted phenylacetylenes, such as phenylacetylenyl phenyl acetylene, to the residual bromines. The polyphenylenes have melting points around 200.degree. C. prior to crosslinking. It would be desirable to provide a polymer dielectric to the microelectronics fabrication industry which provides a reliably low dielectric constant, high thermal stability and a high glass transition temperature and which preferably, permits application by spin coating to planarize and fill gaps on a patterned surface. SUMMARY OF INVENTION In a first aspect, the present invention is an oligomer, uncured polymer or cured polymer comprising the reaction product of one or more polyfunctional compounds containing two or more cyclopentadienone groups and at least one polyfunctional compound containing two or more aromatic acetylene groups wherein at least some of the polyfunctional compounds contain three or more reactive groups. A reactive group, as used herein, is defined as a cyclopentadienone or acetylene group. An oligomer, as used herein, is defined as a reaction product of two or more monomer units of the invention which will gap fill, that is, fill a rectangular trench which is one micrometer deep and one half micrometer across without leaving a void when cured. An uncured polymer, as used herein, is defined as a reaction product of monomers of the invention which no longer gap fills but which contains significant unreacted cyclopentadienone or acetylene functionality. A cured polymer, as used herein, is defined as a reaction product of monomers of the invention which contains no significant unreacted cyclopentadienone or acetylene functionality. Significant unreacted cyclopentadienone or acetylene functionality requires that said moieties be reactive to further advance the polymerization. A feature of the invention is that it comprises the reaction product of one or more polyfunctional compounds containing two or more cyclopentadienone groups and at least one polyfunctional compound containing two or more aromatic acetylene groups wherein at least some of the polyfunctional compounds contain three or more reactive groups. An advantage of such a reaction product is that it may gap fill and planarize patterned surfaces, and as cured have high thermal stability, a high glass transition temperature and a low dielectric constant. In a second, preferred aspect, the present invention is an oligomer, uncured polymer or cured polymer comprising the reaction product of one or more polyfunctional compounds containing two or more cyclopentadienone groups and one or more polyfunctional compounds containing two or more aromatic acetylene groups, wherein at least some of the polyfunctional compounds containing aromatic acetylene groups contain three or more acetylene groups. A feature of the second aspect of the invention is that it comprises the reaction product of at least one or more polyfunctional compounds containing two or more cyclopentadienone groups and at least one polyfunctional compound containing two or more aromatic acetylene groups, wherein at least some of the polyfunctional compounds containing aromatic acetylene groups contain three or more acetylene groups. An advantage of such a reaction product is that it may gap fill and planarize patterned surfaces, and as cured have high thermal stability, a high glass transition temperature and a low dielectric constant. High thermal stability, a high glass transition temperature, a low dielectric constant and the ability to gap fill and planarize patterned surfaces make the compositions of the invention suitable as polymer dielectrics in microelectronics fabrication. In particular, the combination of low dielectric constant, high thermal stability and high glass transition temperature permit the use of the compositions of the invention as interlayer dielectrics in integrated circuits. DETAILED DESCRIPTION OF THE INVENTION Preferably, the oligomers and polymers and corresponding starting monomers of the present invention are: I. Oligomers and Polymers of the General Formula: [A].sub.w [B].sub.z [EG].sub.v wherein A has the structure: ##STR1## and B has the structure: ##STR2## wherein EG are end groups having one or more of the structures: ##STR3## wherein R.sup.1 and R.sup.2 are independently H or an unsubstituted or inertly-substituted aromatic moiety and Ar.sup.1, Ar.sup.2 and Ar.sup.3 are independently an unsubstituted aromatic moiety or inertly-substituted aromatic moiety, M is a bond, and y is an integer of three or more, p is the number of unreacted acetylene groups in the given mer unit, r is one less than the number of reacted acetylene groups in the given mer unit and p+r=y-1, z is an integer from 0 to about 1000; w is an integer from 0 to about 1000 and v is an integer of two or more. Such oligomers and polymers can be prepared by reacting a biscyclopentadienone, an aromatic acetylene containing three or more acetylene moieties and, optionally, a polyfunctional compound containing two aromatic acetylene moieties. Such a reaction may be represented by the reaction of compounds of the formulas (a) a biscyclopentadienone of the formula: ##STR4## (b) a polyfunctional acetylene of the formula: ##STR5## (c) and, optionally, a diacetylene of the formula: R.sup.2 {character pullout}Ar.sup.2 {character pullout}R.sup.2 wherein R.sup.1, R.sup.2, Ar.sup.1, Ar.sup.2, Ar.sup.3 and y are as previously defined. The definition of aromatic moiety includes phenyl, polyaromatic and fused aromatic moieties. Inertly-substituted means the substituent groups are essentially inert to the cyclopentadienone and acetylene polymerization reactions and do not readily react under the conditions of use of the cured polymer in microelectronic devices with environmental species such as water. Such substituent groups include, for example, F, Cl, Br, --CF.sub.3, --OCH.sub.3, --OCF.sub.3, --O--Ph and alkyl of from one to eight carbon atoms, cycloalkyl of from three to about eight carbon atoms. For example, the moieties which can be unsubstituted or inertly-substituted aromatic moieties include: ##STR6## ##STR7## wherein Z can be: --O--, --S--, alkylene, --CF.sub.2 --, --CH.sub.2 --, --O-- CF.sub.2 --, perfluoroalkyl, perfluoroalkoxy, ##STR8## wherein each R.sup.3 is independently --H, --CH.sub.3, --CH.sub.2 CH.sub.3, --(CH.sub.2).sub.2 CH.sub.3 or Ph. Ph is phenyl. II. Polyphenylene Oligomers and Polymers of the General Formulas: ##STR9## wherein R.sup.1, R.sup.2, Ar.sup.1 and Ar.sup.2 are as def ined previously; and x is an integer from 1 to about 1000. Preferably, x is from 1 to about 50 and more preferably from 1 to about ten. Such oligomers and polymers can be prepared by the reaction of a biscyclopentadienone and a diacetylene of the general formulas: ##STR10## wherein R.sup.1, R.sup.2, Ar.sup.1 and Ar.sup.2 are as previously defined. III. Polyphenylene Oligomers and Polymers Represented by the Formula: ##STR11## wherein Ar.sup.4 is an aromatic moiety or an inertly-substituted aromatic moiety, R.sup.1, R.sup.2, and x are as previously defined, as can be prepared by the reaction of the cyclopentadienone functionality and the acetylene functionality of a polyfunctional compound of the general formula: ##STR12## wherein R.sup.1, R.sup.2 and Ar.sup.4 are as defined previously. IV. Polyphenylene Oligomers and Polymers Represented by the Formula: ##STR13## wherein EG is represented by any one of the formulas: ##STR14## wherein R.sup.1, R.sup.2, Ar.sup.4 and x are as defined previously, as can be prepared by the reaction of the cyclopentadienone functionality and the acetylene functionality of a polyfunctional compound of the general formula: ##STR15## wherein R.sup.1, R.sup.2 and Ar.sup.4 are as defined previously. A polyfunctional compound containing two or more aromatic cyclopentadienone moieties may be made by the condensation of benzils with benzyl ketones using conventional methods. Exemplary methods are disclosed in Kumar et al. Macromolecules, 1995, 28, 124-130; Ogliaruso et al., J. Org. Chem., 1965, 30, 3354; Ogliaruso et al., J. Org. Chem., 1963, 28, 2725; and U.S. Pat. No. 4,400,540; all of which are incorporated herein by reference. A polyfunctional compound containing two or more aromatic acetylene moieties may be made by conventional methods. An aromatic compound may be halogenated and then reacted with the appropriate substituted acetylene in the presence of an aryl ethynylation catalyst to replace the halogen with the substituted acetylene compound. Once the polyfunctional compound monomers are made, they are preferably purified. In particular, in preparation for use as an organic polymer dielectric, metals and ionic species are removed. For example, the polyfunctional compounds containing aromatic acetylene groups may be contacted with a water wash, an aliphatic hydrocarbon solvent and then dissolved in an aromatic solvent and filtered through a purified silica gel. This treatment can remove residual ethynylation catalyst. Additional recrystallizations may also help in removal of undesired impurities. While not intended to be bound by theory, it is believed that the polyphenylene oligomers and polymers are formed through the Diels Alder reaction of the cyclopentadienone groups with the acetylene groups when the mixtures of cyclopentadienones and acetylenes in solution are heated. These oligomers may contain cyclopentadienone and/or acetylene end groups and/or pendant groups. Upon further heating of the solution or an article coated with the solution, additional chain extension can occur through the Diels Alder reaction of the remaining cyclopentadienone end groups with the remaining acetylene groups resulting in an increase in molecular weight. Depending on the temperature used, reaction of the acetylene groups with each other may also occur. The oligomers and polymers are shown in the structures as having either cyclopentadienone and/or acetylene end groups and/or pendant groups. In general, the end groups will depend on the relative concentration of cyclopentadienone to Diels Alder reactive acetylene functionality employed in the reaction, with a stoichiometric excess of cyclopentadienone functionality giving more cyclopentadienone end groups and a stoichiometric excess of Diels Alder reactive acetylene functionality giving a greater proportion of acetylene end groups. A feature of a preferred embodiment of the invention is the halting of the polymerization reaction prior to the reaction of all the cyclopentadienone moieties. The oligomer may then be applied to a surface prior to advancing the polymerization to react the balance of the cyclopentadienone moieties. In such an oligomerized state the oligomer may planarize and gap fill when applied to a patterned surface. Preferably, at least ten percent of the cyclopentadienone moieties are unreacted. Most preferably, at least twenty percent of the cyclopentadienone moieties are unreacted. One may determine the percentage of unreacted cyclopentadienone moieties by spectral analysis. The cyclopentadienone moiety is highly colored in the visible spectrum with a distinct red or purple color which fades as the cyclopentadienone moieties react. Planarize, as used herein, means that an isolated feature may be planarized by seventy percent or more, preferably by eighty percent or more and most preferably by ninety percent or more. The percentage or degree of planarization is calculated from the equation: Percent Planarization=(1-t.sub.s /t.sub.m)100 when a layer of oligomer is coated over an isolated square line, one micrometer wide and one micrometer high at an average thickness of two microns and t.sub.s is the height of the oligomer or polymer over the feature above the average height of the oligomer or polymer and t.sub.m is the height of the feature (one micrometer). Use of this definition is illustrated, for example, in Proceedings of IEEE, Vol. 80, No. 12, December, 1992, at page 1948. While not being bound by theory, the preparation of the polyphenylene polymer can be represented generally as follows: ##STR16## wherein R.sup.1, R.sup.2, Ar.sup.1, Ar.sup.2 and x are as defined previously. Furthermore, while not specifically indicated in the structures, some of the carbonyl-bridged species may be present in the oligomers prepared, depending on the specific monomer and reaction conditions used. Upon further heating, the carbonyl bridging species will be essentially fully converted to the aromatic ring system. When more than one acetylene-containing monomer is used, the oligomers and polymers formed are random, while the structures as drawn may suggest blocks are formed. The Diels Alder reaction between the cyclopentadienone and acetylene functionality can take place to form either a para- or meta-attachment on the phenylated ring. Any inert organic solvent which can dissolve the monomers to the appropriate degree and can be heated to the appropriate polymerization temperature either at atmospheric, subatmospheric or superatmospheric pressure could be used. Examples of suitable solvents include mesitylene, pyridine, triethylamine, N-methylpyrrolidinone (NMP), methyl benzoate, ethyl benzoate, butyl benzoate, cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, cyclohexylpyrrolidinone, and ethers or hydroxy ethers such as dibenzylethers, diglyme, triglyme, diethylene glycol ethyl ether, diethylene glycol methyl ether, dipropylene glycol methyl ether, dipropylene glycol dimethyl ether, propylene glycol phenyl ether, propylene glycol methyl ether, tripropylene glycol methyl ether, toluene, mesitylene, xylene, benzene, dipropylene glycol monomethyl ether acetate, dichlorobenzene, propylene carbonate, naphthalene, diphenyl ether, butyrolactone, dimethylacetamide, dimethylformamide and mixtures thereof. The preferred solvents are mesitylene, N-methylpyrrolidinone (NMP), gamma-butyrolactone, diphenylether and mixtures thereof. Alternatively, the monomers can be reacted in one or more solvents at elevated temperature and the resulting solution of oligomers can be cooled and formulated with one or more additional solvents to aid in processing, for example. In another approach, the monomers can be reacted in one or more solvents at elevated temperature to form oligomers which can then be isolated by precipitation into a non-solvent or by some other means of solvent removal to give essentially solvent-free oligomers. These isolated oligomers can then be redissolved in one or more different solvents and the resultant solutions can be used for processing. The conditions under which the polymerization reaction is most advantageously conducted are dependent on a variety of factors, including the specific reactants and solvent. In general, the reaction is conducted under a non-oxidizing atmosphere such as a blanket of nitrogen or other inert gases. The reaction can be conducted neat (without solvent or other diluents). However, in order to ensure homogeneous reaction mixtures and to moderate exothermic reactions at such temperatures, it is often desirable to use inert organic solvents, such as those mentioned previously, for the reactants. The time and temperature most advantageously employed will vary depending on the specific monomers employed, particularly their reactivity, the specific oligomer or polymer desired, and the solvent. In general, the reaction to form the oligomers is conducted at a temperature of from about 150.degree. C. to about 250.degree. C. and for a time of from about 60 minutes to about 48 hours. At this point the oligomers may be isolated from the reaction mixture or used as is in the coating of a surface. Additional chain extension (advancement) may be conducted at a temperature of from about 100.degree. C. to about 475.degree. C., preferably from about 200.degree. C. to about 450.degree. C. and for a time of from about 1 minute to about 10 hours, more preferably from about 1 minute to about 1 hour. An uncured or cured polymer may be used for coating a surface by casting from a solvent. While such a polymer may not gap fill or planarize sufficiently, it may still be useful in a damascene process. The concentrations at which the monomers are most advantageously employed in the organic liquid reaction medium are dependent on a variety of factors including the specific monomers and organic liquid employed and the oligomer and polymer being prepared. In general, the monomers are employed in a cyclopentadienone to acetylene stoichiometric ratio of from about 1:1 to about 1:3, preferably at a 1:1 to 1:2 ratio. The oligomer or polymer can be directly cast as a film, applied as a coating or poured into a non-solvent to precipitate the oligomer or polymer. Water, methanol, ethanol and other similar polar liquids are typical non-solvents which can be used to precipitate the oligomer. Solid oligomer or polymer may be dissolved and processed from a suitable solvent. If the oligomer or polymer is obtained in solid form, it may be further processed using conventional compression molding techniques or melt spinning, casting or extrusion techniques provided the solid precursor has a sufficiently low glass transition temperature. More commonly, the oligomer or polymer is processed directly from the organic liquid reaction solution and the advantages of the present invention are more fully realized in that instance. Since the oligomer or polymer is soluble in the organic liquid reaction medium, the organic solution of the oligomer can be cast or applied and the solvent evaporated. Molecular weight increases (chain extension or advancement), and in some examples, crosslinking, to form the final polymer, occurs upon subsequent exposure to a sufficiently high temperature. The polymer of this invention may be used as one or more of the insulating or dielectric layers in single or multiple layer electrical interconnection architectures for integrated circuits, multichip modules, or flat panel displays. The polymer of the invention may be used as the sole dielectric in these applications or in conjunction with other organic polymers or inorganic dielectrics, such as silicon dioxide, silicon nitride, or silicon oxynitride. For example, coatings of oligomers and polymers of the invention, such as an electrically insulating coating used to fabricate interconnect structures on an electronic wafer, are easily prepared by spin-casting a film of, or otherwise coating a substrate with, the organic liquid solution of the oligomer or polymer and then evaporating the solvent and exposing the oligomer or polymer to temperatures sufficient to advance the oligomer or polymer to higher molecular weight, and in the most preferred examples, to a crosslinked polymer with high glass transition temperature. The polymers of the present invention are particularly useful as a low dielectric constant insulating material in the interconnect structure of an integrated circuit, such as those fabricated with silicon or gallium arsenide. An integrated circuit would typically have multiple layers of metal conductors separated by one or more insulating materials. The polymer material of this invention can be used as insulation between discrete metal conductors in the same layer, and/or between conductor levels of the interconnect structure. The polymers of the present invention can also be used in combination with other materials, such as SiO.sub.2 or Si.sub.3 N.sub.4, in a composite interconnect structure. For example, the oligomers and polymers of the invention may be used in the process for making integrated circuit devices taught in U.S. Pat. No. 5,550,405; U.S. Pat. No. 5,591,677 and Hayashi et al., 1996 Symposium on VLSI Technology Digest of Technical Papers, pg 88-89, all of which are incorporated herein by reference. The oligomers and polymers of the invention may be substituted for the BCB or other resin disclosed in the process disclosed. The oligomer, uncured polymer or polymer of the invention may be used as a dielectric in the above taught processes or similar processes to fabricate an integrated circuit article comprising an active substrate containing transistors and an electrical interconnect structure containing patterned metal lines separated, at least partially, by layers or regions of the composition of the invention. The polymers of the present invention are also useful to planarize materials such as silicon wafers used in semiconductors to allow the production of smaller (higher density) circuitry. To achieve the desired planarity, a coating of the oligomer or polymer is applied from solution such as by spin coating or spray coating, to flow so as to level any roughness on the surface of the substrate. These methods are illustrated by such references as Jenekhe, S. A., Polymer Processing to Thin Films for Microelectronic Applications in Polymers for High Technology, Bowden et al. ed., American Chemical Society 1987, pp. 261-269. In the fabrication of microelectronic devices, relatively thin defect-free films, generally from 0.01 to 20, preferably from 0.1 to 2 micrometer thickness, can be deposited on a surface of a substrate for example silicon, silicon-containing materials, silicon dioxide, alumina, copper, silicon nitride, aluminum nitride, aluminum, quartz, and gallium arsenide. Coatings are conveniently prepared from solutions of an oligomer having a molecular weight, for example, of 3000 M.sub.n or less and 5200 M.sub.w or less, in a variety of organic solvents such as xylene, mesitylene, NMP, gamma-butyrolactone and n-butyl acetate. The dissolved oligomer or polymer can be cast onto a substrate by common spin and spray coating techniques. The thickness of the coating may be controlled by varying the percent solids, the molecular weight, and thus the viscosity of the solution as well as by varying the spin speed. The polyphenylene oligomer or polymer in this invention may be applied either by dip coating, spray coating, extrusion coating, or more preferably by spin coating. For all cases, the environment around the substrate and coating prior to cure may be controlled with respect to temperature and humidity. In particular, NMP may absorb water from the water vapor in the ambient air. When dissolved in NMP, one should protect the solution from moist air and cast the film in a low humidity environment. When using NMP as the solvent, preferably, the relative humidity is controlled at less than thirty percent and the temperature is controlled at 27 C or greater. The coating may be cured after application either with one or more hot plates, an oven, or a combination of these tools. Adhesion promoters, such as those based on silane chemistry, may be applied to the substrate prior to the application of the polyphenylene oligomer or polymer solution, or added directly to the solution. The oligomers and polymers of the present invention can be used in either a "damascene" metal inlay or subtractive metal patterning scheme for fabrication of integrated circuit interconnect structure. Processes for fabricating damascene lines and vias are known in the art. See for example U.S. Pat. Nos. 5,262,354 and 5,093,279. Patterning of the material may be done with typical reactive ion etch procedures using oxygen, argon, nitrogen, helium, carbon dioxide, fluorine containing compounds, or mixtures of these and other gases, using a photoresist "softmask", such as an epoxy novolac, or a photoresist in combination with an inorganic "hardmask" such as SiO.sub.2, Si.sub.3 N.sub.4, or metal. The oligomers and polymers may be used in conjunction with Al, Al alloys, Cu, Cu alloys, gold, silver, W, and other common metal conductor materials (for conductive lines and plugs) deposited by physical vapor deposition, chemical vapor deposition, evaporation, electroplating, electroless deposition, and other deposition methods. Additional metal layers to the basic metal conductors, such as tantalum, titanium, tungsten, chromium, cobalt, their alloys, or their nitrides, may be used to fill holes, enhance metal fill, enhance adhesion, provide a barrier, or modify metal reflectivity. Depending on the fabrication architecture, either metal or the dielectric material of this invention may be removed or planarized using chemical-mechanical polishing techniques. Multichip modules on active or passive substrates such as silicon, silicate glass, silicon carbide, aluminum, aluminum nitride, or FR-4, may be constructed with the polyphenylene polymer of this invention as a dielectric material. Flat panel displays on active or passive substrates such as silicon, silicate glass, silicon carbide, aluminum, aluminum nitride, or FR-4, may be constructed with the polyphenylene polymer of this invention as a dielectric material. The oligomers and polymers of the present invention may further be used as protective coatings on integrated circuit chips for protection against alpha particles. Semiconductor devices are susceptible to soft errors when alpha particles emitted from radioactive trace contaminants in the packaging or other nearby materials strike the active surface. An integrated circuit can be provided with a protective coating of the polymer of the present invention. Typically, an integrated circuit chip would be mounted on a substrate and held in place with an appropriate adhesive. A coating of the polymer of the present invention provides an alpha particle protection layer for the active surface of the chip. optionally, additional protection is provided by encapsulant made of, for example, epoxy or a silicone. The polymers of the present invention may also be used as a substrate (dielectric material) in circuit boards or printed wiring boards. The circuit board made up of the polymer of the present invention has mounted on its surface patterns for various electrical conductor circuits. The circuit board may include, in addition to the polymer of the present invention, various reinforcements, such as woven nonconducting fibers, such as glass cloth. Such circuit boards may be single sided, as well as double sided or multilayer. The polymers of the present invention may also be useful in reinforced composites in which a resin matrix polymer is reinforced with one or more reinforcing materials such as a reinforcing fiber or mat. Representative reinforcing materials include fiber glass, particularly fiber glass mats (woven or non-woven); graphite, particularly graphite mat (woven or non-woven); Kevlar.TM.; Nomex.TM.; and glass spheres. The composites can be made from preforms, dipping mats in monomer or oligomer, and resin transfer molding (where the mat is placed into the mold and monomer or prepolymer is added and heated to polymerize). Layer(s) of the polymers of the present invention may be patterned by such means as wet-etching, plasma-etching, reactive-ion etching (RIE), dry-etching, or photo laser ablation, such as illustrated by Polymers for Electronic Applications, Lai, CRC Press (1989) pp. 42-47. Patterning may be accomplished by multilevel techniques in which the pattern is lithographically defined in a resist layer coated on the polymeric dielectric layer and then etched into the bottom layer. A particularly useful technique involves masking the portions of oligomer or polymer not to be removed, removing the unmasked portions of oligomer or polymer, then curing the remaining oligomer or polymer, for example, thermally. In addition, the oligomer of the present invention may also be employed to make shaped articles, films, fibers, foams, and the like. In general, techniques well-known in the art for casting oligomers or polymers from solution may be employed in the preparation of such products. In preparing shaped polyphenylene oligomer or polymer articles, additives such as fillers, pigments, carbon black, conductive metal particles, abrasives and lubricating polymers may be employed. The method of incorporating the additives is not critical and they can conveniently be added to the oligomer or polymer solution prior to preparing the shaped article. The liquid compositions containing the oligomer or polymer, alone or also containing fillers, may be applied by any of the usual techniques (doctoring, rolling, dipping, brushing, spraying, spin coating, extrusion coating or meniscus coating) to a number of different substrates. If the polyphenylene oligomer or polymer is prepared in solid form, the additives can be added to the melt prior to processing into a shaped article. The oligomer and polymer of the present invention can be applied to various substrates by a number of methods such as, solution deposition, liquid-phase epitaxy, screen printing, melt-spinning, dip coating, roll coating, spinning, brushing (for example as a varnish), spray coating, powder coating, plasma-deposition, dispersion-spraying, solution-casting, slurry-spraying, dry-powder-spraying, fluidized bed techniques, welding, explosion methods including the Wire Explosion Spraying Method and explosion bonding, press bonding with heat, plasma polymerization, dispersion in a dispersion media with subsequent removal of dispersion media, pressure bonding, heat bonding with pressure, gaseous environment vulcanization, extruding molten polymer, hot-gas welding, baking, coating, and sintering. Mono- and multilayer films can also be deposited onto a substrate using a Langmuir-Blodgett technique at an air-water or other interface. When applying the oligomer or polymer of the invention from solution, specific conditions of polymerization and other processing parameters most advantageously employed are dependent on a variety of factors, particularly the specific oligomer or polymer being deposited, the conditions of coating, the coating quality and thickness, and the end-use application, with the solvent being selected accordingly. Representative solvents which can be employed are those described previously. Substrate(s) which can be coated with the oligomer or polymer of the invention can be any material which has sufficient integrity to be coated with the monomer, oligomer or polymer. Representative examples of substrates include wood, metal, ceramics, glass, other polymers, paper, paper board cloth, woven fibers, non-woven fiber mats, synthetic fibers, Kevlar.TM., carbon fibers, gallium arsenide, silicon and other inorganic substrates and their oxides. The substrates which are employed are selected based on the desired application. Exemplary materials include glass fibers (woven, non-woven or strands), ceramics, metals such as aluminum, magnesium, titanium, copper, chromium, gold, silver, tungsten, stainless steel, Hastalloy.TM., carbon steel, other metal alloys and their oxides, and thermoset and thermoplastic polymers such as epoxy resins, polyimides, perfluorocyclobutane polymers, benzocyclobutane polymers, polystyrene, polyamides, polycarbonates, polyarylene ethers and polyesters. The substrate can be the polymers of the present invention in cured form. The substrate may be of any shape, and the shape is dependent on the end-use application. For instance, the substrate may be in the form of a disk, plate, wire, tubes, board, sphere, rod, pipe, cylinder, brick, fiber, woven or non-woven fabric, yarn (including commingled yarns), ordered polymers, and woven or non-woven mat. In each case the substrate may be hollow or solid. In the case of hollow objects, the polymer layer(s) is on either or both the inside or outside of the substrate. The substrate may comprise a porous layer, such as graphite mat or fabric, glass mat or fabric, a scrim, and particulate material. The oligomers or polymers of the invention adhere directly to many materials such as compatible polymers, polymers having a common solvent, metals, particularly textured metals, silicon or silicon dioxide, especially etched silicon or silicon oxides, glass, silicon nitride, aluminum nitride, alumina, gallium arsenide, quartz, and ceramics. However, when increased adhesion is desired, a material may be introduced to improve adhesion. Representative examples of such adhesion promoting materials are silanes, preferably organosilanes such as trimethoxyvinylsilane, triethoxyvinylsilane, hexamethyldisilazane [(CH.sub.3).sub.3 --Si--NH--Si(CH.sub.3).sub.3 ], or an aminosilane coupler such as .gamma.-aminopropyltriethoxysilane, or a chelate such as aluminum monoethylacetoacetatediisopropylate [((isoC.sub.3 H.sub.7 O).sub.2 Al(OCOC.sub.2 H.sub.5 CHCOCH.sub.3))]. In some cases, the adhesion promoter is applied from 0.01 weight percent to 5 weight percent solution, excess solution is removed, and then the polyphenylene applied. In other cases, for example, a chelate of aluminum monoethylacetoacetatedi-isopropylate, can be incorporated onto a substrate by spreading a toluene solution of the chelate on a substrate and then baking the coated substrate at 350.degree. C. for 30 minutes in oxygen to form a very thin (for example 5 nanometer) adhesion promoting layer of aluminum oxide on the surface. Other means for depositing aluminum oxide are likewise suitable. Alternatively, the adhesion promoter, in an amount of, for example, from 0.05 weight percent to 5 weight percent based on the weight of the monomer, can be blended with the monomer before polymerization, negating the need for formation of an additional layer. Adhesion can also be enhanced by surface preparation such as texturizing (for example, scratching, etching, plasma treating, or buffing) or cleaning (for example, degreasing or sonic cleaning); otherwise treating (for example, plasma, solvent, SO.sub.3, plasma glow discharge, corona discharge, sodium, wet etching, or ozone treatments) or sand blasting the substrate's surface or using electron beam techniques such as 6 MeV fluorine ions; electrons at intensities of 50 to 2000V; hydrogen cations at 0.2 to 500 ev to 1 MeV; helium cations at 200 KeV to 1 MeV; fluorine or chlorine ions at 0.5 MeV; neon at 280 KeV; oxygen enriched flame treatment; or an accelerated argon ion treatment. For application of the oligomerized product of the reaction of 3,3'-(oxydi-1,4-phenylene)bis(2,4,5-triphenylcyclopentadienone) and 1,3,5-tris(phenylethynyl)benzene, a more preferred embodiment of the invention, a silane based adhesion promoter, containing 3-aminopropyl silane dissolved in methoxy propanol, available as VM-652 from DuPont or AP8000 from The Dow Chemical Company, is first applied to the wafer surface; spun slowly to spread across the entire surface; allowed to stand for 2 seconds; and finally spun dry at 3000 rpm for 10 seconds. A solution of the oligomer is dispensed, 4 mL for a 200 mm wafer, by a high precision pump/filtration system, Millipore Gen-2, onto the wafer surface as the wafer is spun at 750 rpm. The wafer rotation is accelerated to 2000 rpm immediately following the dispense of the polymer solution and held at that spin speed for 20 seconds. A continuous stream of mesitylene is applied to the backside of the wafer for 5 seconds during the dispense of the oligomer solution. After spin coating, the film is dried on a hot plate at 70 C for 20 seconds. After the dry-bake step, the 2 mm to 5 mm edge bead of the coating is removed with a continuous stream of mesitylene while the wafer is spun at 2000 rpm; either by application from the backside or directly from the top near the edge. After the edge bead removal, the oligomer is further polymerized on a hot plate at 325.degree. C. for 90 seconds under a nitrogen blanket. The film is crosslinked either on a hot plate at 450 C for 2 minutes under nitrogen or in a nitrogen purged oven at 450 C for 6 minutes. The oligomer or polymer of the invention can be applied in combination with other additives to obtain specific results. Representative of such additives are metal-containing compounds such as magnetic particles, for example, barium ferrite, iron oxide, optionally in a mixture with cobalt, or other metal containing particles for use in magnetic media, optical media, or other recording media; conductive particles such as metal or carbon for use as conductive sealants, conductive adhesives, conductive coatings, electromagnetic interference (EMI)/radio frequency interference (RFI) shielding coating, static dissipation, and electrical contacts. When using these additives, the oligomer or polymer of the invention may act as a binder. The oligomer or polymer of the invention may also be employed as protection against the environment (that is, protective against at least one substance or force in an object's environment, including conditions of manufacture, storage and use) such as coatings to impart surface passivation to metals, semiconductors, capacitors, inductors, conductors, solar cells, glass and glass fibers, quartz and quartz fibers. 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. |
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