DEPOSITION OF FILMS USING ORGANOSILSESQUIOXANE-PRECURSORS

Abstract: There is provided an array of alkyl substituted silsesquioxane thin film precursors having a structure wherein alkyl groups are bonded to the silicon atoms of a silsesquioxane cage. The alkyl groups may be the same as, or different than the other alkyl groups. In a first aspect, the present invention provides a composition comprising a vaporized material having the formula [R-SiO1.5]x[H-SiO1.5]y, wherein x + y = n, n is an integer between 2 and 30, x is an integer between 1 and n and y is a whole number between 0 and n. R is a C1 to C100 alkyl group. Also provided are films made from these precursors and objects comprising these films.

Description: DEPOSITION OF FILMS USING ORGANOSILSESQUIOXANE-PRECURSORS Background of the Invention Semiconductors are widely used in integrated circuits for electronic applications, including high-speed computers and wireless communications. Such integrated circuits typically use multiple transistors fabricated in single crystal silicon. Many integrated circuits now contain multiple levels of metallization for interconnections. A single semiconductor microchip may have thousands, and even millions of transistors. Logically, a single microchip may also have millions of lines interconnecting the transistors. As device geometries shrink and functional density increases, it becomes imperative to reduce the capacitance between the lines. Line-to-line capacitance can build up to a point where delay time and crosstalk hinders device performance. Reducing the capacitance within these multi-level metallization systems reduces the RC constant, crosstalk voltage, and power dissipation between the lines. Typically, thin films of silicon dioxide are used as dielectric layers and to reduce the capacitance between functional components of the device. Such dielectric thin films serve many purposes, including preventing unwanted shorting of neighboring conductors or conducting levels, by acting as a rigid, insulating spacer; preventing corrosion or oxidation of metal conductors, by acting as a barrier to moisture and mobile ions; filling deep, narrow gaps between closely spaced conductors; and planarizing uneven circuit topography so that a level of conductors can then be reliably deposited on a film surface which is relatively flat. A significant limitation is that typically interlevel dielectric (ILD) and protective overcoat (PO) films must be formed at relatively low temperatures to avoid destruction of underlying conductors. Another very important consideration is that such dielectric films should have a low relative dielectric constant k, as compared to silicon dioxide (k = 3.9), to lower power consumption, crosstalk, and signal delay for closely spaced conductors. Recently, attempts have been made to use materials other than silicon dioxide. Notable materials include low-density materials, such as aerogels and silsesquioxanes. The dielectric constant of a porous dielectric, such as a silicon dioxide aerogel, can be as low as 1.2. This lower dielectric constant results in a reduction in the RC delay time. However, methods of making aerogels require a supercritical drying step. This step increases the cost and the complexity of semiconductor manufacturing. Films deposited from hydrogen silsesquioxane (HSQ) resins have been found to possess many of the properties desirable for ILD and PO applications. For example, Haluska e. α/ (U S Pat No 4,756,977, July 12, 1988) descπbe a film deposition technique compπsing diluting in a solvent a hydrogen silsesquioxane resin, applying this as a coating to a substrate, evaporating the solvent and ceramifying the coating by heating the substrate in air Others have found that by ceramifying such a coating in the presence of hydrogen gas (Ballance et al , U S Pat No 5,320,868, June 14, 1994) or inert gas (European Patent Application 9031 1008 8), the dielectπc constant of the final film may be lowered and/or stabilized as compared to ceramifying in air Each of these patents discloses the use of silsesquioxane resm dissolved in a solvent The resulting silsesquioxane solution is coated onto a substrate by a spin-on coating technique Limited effort has been directed towards chemical vapor deposition of silsesquioxane dielectπc coatings See, Gentle, U S Patent No 5,279,661, January 18, 1994 disclosing CVD of hydrogen silsesquioxane coatings on a substrate Although these coatings form useful dielectπc layers after cuπng, as device sizes progressively minimize, it is necessary to have available dielectπc thin films having a lower dielectπc constant than that provided by the simple hydrogen silsesquioxane films An array of low k thin films of different composition and precursors for these films which can be deposited onto a substrate using CVD would represent a significant advance in the art and would open avenues for continued device mmiatuπzation Quite surpπsingly, the present invention provides such films and precursors Summary Of The Invention It has now been discovered that silsesquioxanes having alkyl groups bonded to the silicon atoms of the silsesquioxane cage are useful precursors for low dielectric constant thin films The alkylated silsesquioxane cages are easily prepared using art- recognized techniques and fractions of these molecules can be deposited onto substrates using CVD Following its deposition onto a substrate, the alkylated silsesquioxane layer is cured, producing a low k dielectnc layer or film In a first aspect, the present invention provides a composition compπsing a vapoπzed mateπal having the formula [R-SiOi 5 ] x [H-SιOι 5 ] y , wherein x + y = n, n is an integer between 2 and 30, x is an integer between 1 and n and y is a whole number between 0 and n R is a Ci to oo alkyl group In a second aspect, the present invention provides a method of forming a low k dielectπc film The method compπses vapoπzing and depositing on a substrate a mateπal having the formula [R-SiOi 5 ] x [H-SιOι s] y , wherein x + y = n, n is an integer between 2 and 30, x is an integer between 1 and n and y is a whole number between 0 and n. R is a C] to Cioo alkyl group. In a third aspect, the invention provides a low k dielectric film compnsing a material having the formula [H a SιO b ] c [(R 1 ) a SιO b ]d[(R 2 )aSιO b ] n . In this formula R 1 and R 2 are members independently selected from to Cioo alkyl groups; a is less than or equal to 1 ; b is greater than or equal to 1 5. and c, d and n are members independently selected from the group consisting of the integers greater than 10 In a fourth aspect, the present invention provides an object compπsing a low k dielectπc film compπsing a mateπal having the formula [H a SιO b ] c [(R') a SιO b ] d [(R 2 ) a SιO b ] n . In this formula R 1 and R 2 are members independently selected from C, to Cioo alkyl groups; a is less than or equal to 1 ; b is greater than or equal to 1.5; and c, d and n are members independently selected from the group consisting of the integers greater than 10. These and other aspects and advantages of the present invention will be apparent from the detailed descπption that follows Brief Description Of The Figures Figure 1 is a group of three-dimensional structural formulae for the methyl- substituted silsesquioxanes of the invention. Figure 2 is a group of three-dimensional structural formulae for the alkyl- substituted silsesquioxanes of the invention. Figure 3 is a group of three-dimensional structural formulae for the alkyl- substituted silsesquioxanes of the invention, wherein each R group is the same as, or different from the other R groups Detailed Description Of The Invention And The Preferred Embodiments Abbreviations and Definitions "CVD," as used herein, refers to "chemical vapor deposition." "AHSQ," as used herein refers to "alkylated hydrogen silsesquioxanes." "ASQ," as used herein, refers to "alkylated silsesquioxanes." "ASX," as used herein, refers to "alkylated fluonnated siloxanes." "AHSX," as used herein, refers to "alkylated fluonnated hydrogen siloxanes." The terms "alkylated silsesquioxanes" and "alkylated hydrogen silsesquioxanes" are used herein to descπbe various silane resins having the formula [R-S1O 1 5 ],.[H-SιOι 5 ] y , wherein x + y = n, n is an integer between 2 and 30, x is an integer between 1 and n and y is a whole number between 0 and n R is a Ci to Cioo alkyl group "Alkylated silsesquioxanes" refer to silsesquioxanes in which substantially every silicon atom has an alkyl group attached thereto 'Alkylated hydrogen silsesquioxanes" refer to silsesquioxanes having a mixture of alkylated silicon atoms and silicon atoms bearing hydrogen "Silsesquioxane" is used genencally herein to refer to both of the above- descπbed species Though not explicitly represented by this structure, these resins may contain a small number of silicon atoms which have either 0 or 2 hydrogen atoms or alkyl groups attached thereto due to vaπous factors involved in their formation or handling The terms "alkylated siloxane film" and "alkylated hydrogen siloxane film" refer to films resulting from cuπng the deposited silsesquioxane The films have the geneπc formula [H a SιO b ] c [(R') a SιO b ] d [(R 2 ) a SιO b ]„ In this formula R 1 and R 2 are members independently selected from d to Cioo alkyl groups, a is less than or equal to 1, b is greater than or equal to 1 5, and c, d and n are members independently selected from the group consisting of the integers greater than 10 "Low k," as used herein, refers to a dielectπc constant that is lower than that of an Sι0 2 film Introduction The present invention is based on the discovery that fractions of fully alkylated silsesquioxanes and alkylated hydrogen silsesquioxanes can be used to form coatings on vaπous substrates The compounds are deposited onto a substrate, such as a semiconductor wafer by CV D Following their deposition, the film is cured to produce a low k dielectπc film The films produced by the techniques descπbed herein are valuable as protective and dielectπc layers on substrates such as electronic devices The invention provides methods of forming low k dielectπc films Additionally, there is provided an array of low k films and compounds useful for forming these films The Compounds In a first aspect, the present invention provides a composition compπsing a vapoπzed mateπal having the formula [R-SiO, 5 ] x [H-SιOι 5 ] y , wherein x + y = n. n is an integer between 2 and 30, x is an integer between 1 and n and y is a whole number between 0 and n R is a Ci to Cioo alkyl group Presently preferred mole % carbon content is from about 20% to about 90%, more preferably from about 40% to about 80% The silsesquioxanes of the invention are alkyl-substituted molecules that, at higher values of n, exist as cage "T-n" molecules (e g , T-8, T-10, etc ) In a preferred embodiment, n is an integer with a value from 2 to 16 In a further preferred embodiment, n is an integer with a value from 8 to 12 These compounds can be synthesized by a number of art-recognized methods For example ASQ can be synthesized by the hydrolysis and condensation of R-S1-X 3 , wherein R is methyl or a C 2 -C 1 00 alkyl group In a preferred embodiment, the alkyl group is a Ci to C 2 o alkyl group In another preferred embodiment, the alkyl group is a d to Ciβ alkyl group In yet another preferred embodiment, the alkyl group is to Cβ The alkyl groups can be either straight- or branched chain alkyl groups In the formula provided above, X represents a species that is eliminated duπng hydrolysis Currently, preferred X groups are halogens, alkoxy groups and aryloxy groups, more preferably halogens and even more preferably CI The hydrolysis/condensation reactions preferably result in a fully condensed ASQ or AHSQ or the hydrolysis and/or condensation may be interrupted at an intermediate point such that partial hydrolysates (containing Si-OR, Si-Cl, etc ) and/or partial condensates (containing SiOH groups) are formed See, for example, Olsson, Arkiv Kemi 13 367-78 (1958), Barry et al , J Am Chem Soc 11 4248-52 (1955), and Dittmar et al , J Organomet Chem 489 185-194 (1995) In a preferred embodiment, the reaction produces substantially fully condensed silsesquioxanes ASQ and AHSQ having alkyl groups of more than one structure or composition substituted onto a single silicon framework are prepared by cohydrolysis of organotnhalosilanes or organotπalkoxysilanes where the components of the cohydrolysis reaction bear different alkyl groups at the silicon atom For example, the cohydrolysis of CH 3 S1CI 3 and CH 3 CH 2 S1CI 3 will provide a silsesquioxane having both methyl and ethyl functionality on the silicon atoms of the silsesquioxane See, for example, Hendan et al , J Organomet Chem 483 33-8 (1994) The alkyl content of the ASQ and AHSQ can be controlled by manipulation of the stoichiometry of the hydrolysis reaction The hydrolysis/condensation reactions can be performed in a number of different reaction milieus and the choice of appropπate reaction conditions is well within the abilities of those of skill in the art The hydrolysis and condensation polymeπzation is generally earned out using conventional equipment, by the addition of the organosilane monomer (or both monomers in the case of copolymeπzation) to an aqueous medium The aqueous medium can be simply water or it can be an aqueous alcohol Additionally, catalysts such as organic and/or inorganic acids or bases can be added to the reaction mixture For example, when silane alkoxides are utilized as precursors for the silsesquioxane, it is often desirable to use an acidic catalyst (e g , HC1) to facilitate the reaction Moreover, when silane ha des are utilized as precursors, a basic reaction environment often facilitates the reaction See, for example, Wacker et al , U S Patent No 5,047,492, September 10, 1991 The silane monomers (e g , CH3S1CI3, HS1CI 3 , etc ) can be added neat to the hydrolysis mixture or they can be first solubilized in a solvent (e g , hexanes, methylene chloπde, methanol, etc ) The monomer(s) is preferably added at a measured rate to the hydrolysis medium to obtain more precise control of the hydrolysis and condensation In a preferred embodiment, wherein two or more monomers are utilized, a mixture of the monomers is formed and then this mixture is added to the hydrolysis mixture Additional control of the hydrolysis and condensation polymeπzation reactions can also be obtained though adjustment of the temperature of the hydrolysis reaction medium, by maintaining the reaction temperature in the range of about 0 °C to about 50 °C Preferably, the temperature of the hydrolysis reaction medium is maintained at a temperature from about 0 °C to about 5 °C In yet another embodiment, alkylated silsesquioxanes are prepared by the cross- metathesis of alkenes with readily available vinyl-substituted silsesquioxanes This reaction is quite general and is unhindered by self-metathesis of the vinyl-substituted silsesquioxanes See, for example, Feher et al Chem Commun 13 1 185-1186 (1997) In a still further embodiment, the ASQ or AHSQ molecules are synthesized by hydrosilation of a precursor hydrogen silsesquioxane or AHSQ This method affords access to ASQ molecules and AHSQ molecules (mono-, di-, tπ-substituted, etc ), depending on the stoichiometry of the reaction between the silsesquioxane and the incoming hydrosilating species In a preferred embodiment, the silsesquioxane cage is hydrosilated with an alkene Hydrosilation reactions of the silsesquioxanes are typically earned out under catalytic conditions In a presently preferred embodiment, the catalyst is a platinum catalyst, such as a chloroplatinic acid See, for example, Bolln et al , Chem Mater 9 1475-1479 (1997), Bassindale et al , In, TAILOR-MADE SILICON-OXYGEN COMPOUNDS, pp 171-176, Eds Corπu et al , Vieweg, Wiesbaden, Germany (1995), Calzaferπ et al , Helv Chim Acta l 1278-1280 (1991), Herren et al Helv Chim Ada 74 24-6 (1991), and Dittmar et al , J Organomet Chem 489 185-194 (1995) —> I Certain of the starting hydrogen silsesquioxane used in the hydrosilation reaction are commercially available. For example, the T-8 cage is commercially available (Aldrich Chemical Co., Dow Coming, Hitachi). Moreover, various methods for the production of hydrogen silsesquioxanes have been developed. For instance, Collins et al. in U.S. Pat. No. 3,615,272, which is incorporated herein by reference, describe a process of forming nearly fully condensed hydrogen silsesquioxane (which may contain up to 100-300 ppm silanol) comprising hydrolyzing trichlorosilane in a benzenesulfonic acid hydrate hydrolysis medium and then washing the resulting product with water or aqueous sulfuric acid. Similarly, Bank et al. in U.S. Patent No. 5,010,159, April 23, 1991 , disclose methods of forming hydrogen silsesquioxanes comprising hydrolyzing hydridosilanes in an arylsulfonic acid hydrate hydrolysis medium to form a resin which is then contacted with a neutralizing agent. A preferred embodiment of this latter process uses an acid to silane ratio of about 6/1. Higher order silsesquioxane cages (e.g., T-10, -12, etc.) can be prepared by, for example, partial rearrangement of octasilsesquioxane cages. These rearrangement reactions are catalyzed by compounds such as sodium acetate, sodium cyanate, sodium sulfite, sodium hydroxide and potassium carbonate. The reactions are generally carried out in an organic solvent, preferably acetone. See, for example, Rikowski et al., Polyhedron 16: 3357-3361 (1997). Recovery of the silsesquioxane reaction product from the aqueous reaction medium may be carried out using conventional techniques (e.g., solvent extraction with organic solvents that solubilize the reaction product but are immiscible with the aqueous reaction medium), salting-out of the silsesquioxane reaction product, and the like. The silsesquioxane reaction product can then be recovered by filtration or evaporation of the extract solvent as applicable. The compounds can be purified by techniques common in the art of organic chemistry including chromatography (e.g., gel permeation, silica gel, reverse-phase, HPLC, FPLC, etc.), crystallization, precipitation, fractionation, ultrafiltration, dialysis and the like. In a presently preferred embodiment, the desired material is purified by fractionation and precipitation. Art-recognized analytical methods can be used to characterize the compounds. Useful methods include spectroscopic techniques (e.g., Η, 13 C, 19 F NMR, infrared), mass spectrometry, gel permeation chromatography against a molecular weight standard, elemental analysis, melting point determination and the like. In a preferred embodiment, the compounds are characterized by a protocol involving each of these techniques. In an exemplary embodiment, a tπchlorosilane (~ 25g) is added drop-wise with stirπng to distilled water (-250 mL) and a non-polar solvent (e g , hexanes, toluene) at a temperature of about 0 °C Upon completion of the addition of the silane, the reaction is allowed to stir for between 10 minutes and 24 hours If a precipitate forms in the aqueous mixture, this mixture can be claπfied by filtration or centπfugation A.n organic solvent such as hexane is then added to the aqueous reaction medium The resulting mixture is stirred for a time sufficient to allow the extraction of the reaction product from the aqueous medium The organic layer is removed from the aqueous layer and the aqueous phase is extracted further with three washings of the organic solvent (~ 3 x 100 mL) The hexane washings are combined with the oπgmal organic phase extract, and the combined organic phase solution is dπed by contacting it with sodium sulfate, and thereafter it is filtered After evaporation of the solvent from the organic phase extract, the recovered reaction product is dπed under high vacuum to yield the desired product The product can be charactenzed by Η and 29 Sι NMR, mass spectrometry and elemental analysis The molecular weight of the product is determined by GPC relative to a standard, such as a polystyrene calibration standard Low k dielectπc films with desirable physical properties can also be prepared using copolymers of alkylsilanes copolymeπzed with tπchlorosilane In an exemplary embodiment, an AHSQ molecule is prepared by the hydrolysis condensation method In this embodiment, the alkyl content of the final product is controlled by the stoichiometπc ratio of the alkyl silane to tπchlorosilane Thus, to prepare a product that has an average of 3 1 methyl to hydrogen, methyltπchlorosilane (3 moles) and tnchlorosilane (1 mole) are combined, and the combined components are added dropwise with stirπng to distilled water (~ 250 mL) and a non-polar solvent at a temperature of about 0 °C After stirπng for a peπod of from about 10 minutes to about 24 hours, an organic solvent such as hexane (~ 250 mL) is added to the aqueous reaction medium to extract the reaction product from the aqueous medium, and the reaction mixture is stirred for ten minutes The work up of the reaction mixture and the characteπzation of the product are substantially similar to that descπbed for the homopolymer above In a preferred embodiment, the ASQ or AHSQ polymer is deposited by vapor deposition, however, certain of the above-descπbed reactions can lead to the production of ASQ and AHSQ polymers that have a molecular weight that is too high to allow these polymers to be vapoπzed in useful quantities Although, the volatile fraction can be vapoπzed and used to form a film, leaving behind the higher molecular weight fraction, in a preferred embodiment, the high molecular weight molecules are removed from the more volatile components of the product mixture prior to using these compounds for vapor deposition Separation of the high and low molecular weight fractions can be accomplished by a number of means including, for example, gel permeation chromatography, high performance liquid chromatography (HPLC), ultrafiltration, fractional crystallization and solvent fractionation Each of these methods is well known in the art and it is within the abilities of one of skill m the art to devise an appropπate punfication protocol for a particular mixture without undue experimentation When other deposition methods are utilized, the volatility of the film precursor is less of a concern In a preferred embodiment, using vapor deposition, the product mixture is fractionated to obtain the low molecular weight species that can be volatilized m the deposition process of this invention Any conventional technique for fractionating the polymer can be used herein Particularly preferred, however, is the use of a vaπety of fluids at, near or above their cπtical point This process is descπbed in Hanneman et al , U S Patent No 5,118,530, June 2, 1992 The process descπbed therein compπses (1) contacting the H-resin with a fluid at, near or above its cπtical point for a time sufficient to dissolve a fraction of the polymer, (2) separating the fluid containing the fraction from the residual polymer, and (3) recoveπng the desired fraction Specifically, the fractionation method involves charging an extraction vessel with a silsesquioxane product mixture and then passing an extraction fluid through the vessel The extraction fluid and its solubility characteπstics are controlled so that only the desired molecular weight fractions of silsesquioxane are dissolved The solution with the desired fractions of silsesquioxane is then removed from the vessel leaving those silsesquioxane fractions not soluble in the fluid as well as any other insoluble mateπals such as gels or contaminants The desired silsesquioxane fraction is then recovered from the solution by alteπng the solubility characteπstics of the solvent an„ thereby, precipitating out the desired fraction These precipitates can then be collected by a process such as filtration or centπfugation The extraction fluid used m this process includes any compound which, when at, near or above its cπtical point, will dissolve the fraction of silsesquioxane desired and not dissolve the remaining fractions Additional consideration, however, is usually given to the cπtical temperature and pressure of the solvent compound so that unreasonable measures are not necessary to reach the appropπate point Examples of specific compounds that are functional include, but are not limited to, carbon dioxide and most low molecular weight hydrocarbons such as ethane or propane Additional methods of fractionation are disclosed in Katsutoshi et al , O S Patent No 5,486,546. January 23, 1996 By such methods, one can recover the desired fraction of an AHSQ or ASQ Other equivalent methods however, which result in obtaining the fractions descnbed herein are also contemplated For instance, methods such as solution fractionation or sublimation function herein (See, for example, Olsson et al Ar v Kemi 13 367-78 (1958)) When a vapor deposition method is used, the preferred fraction of silsesquioxane used in the process of this invention is one that can be volatilized under moderate temperature and/or vacuum conditions Generally, such fractions are those in which at least about 75% of the species have a molecular weight less than about 3000 Preferred herein, however, are those fractions in which at least about 75% of the species have a molecular weight less than about 1800, with those fractions in which at least about 75% of the species have a molecular weight between about 400 and 1600 being particularly preferred In preferred embodiments, this molecular weight range will correspond to compounds that are T-2 to T-30 cages For vapor deposition, preferred species correspond to compounds that are T-2 to T-16, and for spin on applications, T-12 to T-30 Additionally, it is contemplated that mixtures of silsesquioxanes containing components that are not easily vapoπzed can be used herein as the source of silsesquioxane vapor Volatilization of such mixtures, however, can leave a residue compπsing nonvolatile species This residue does not constitute an impediment to the use of silsesquioxane mixtures containing compounds having a broad range of molecular weights Chemical Vapor Deposition (CVD) Any deposition method known in the art can be used to produce a film using one or more compounds of the invention Deposition techniques of general applicability include, for example, spraying (e g , nebulizer under vacuum), spin-on, dip-coating, sputteπng, CVD, and the like Other coating methods will be apparent to those of skill in the art As the use of CVD is presently preferred, in a second aspect, the invention provides a method of forming a low k dielectπc film The method compπses vapoπzing and depositing on a substrate a mateπal having the formula [R-SiOi _] x [H-SιOι 5 ] y , wherein x + y = n, n is an integer between 2 and 30, x is an integer between 1 and n and y is a whole number between 0 and n R is a to Cioo alkyl group In an exemplary embodiment, the desired fraction of silsesquioxane is obtained, and it is placed into a CVD apparatus, vapoπzed and introduced into a deposition chamber containing the substrate to be coated Vapoπzation can be accomplished by heating the silsesquioxane sample above its vaporization point, by the use of vacuum, or by a combination of the above Generally, vapoπzation is accomplished at temperatures in the range of 50 °C - 300 °C under atmospheric pressure or at lower temperature (near room temperature) under vacuum The amount of silsesquioxane vapor used in the process of this invention is that which is sufficient to deposit the desired coating This can vary over a wide range depending on factors such as the desired coating thickness, the area to be coated, etc In addition, the vapor may be used at nearly any concentration desired If dilute vapor is to be used, it may be combined with nearly any compatible gas such as air, argon or helium The process of this invention can be used to deposit desirable coatings in a wide vaπety of thicknesses For instance, coatings in the range of from about a monolayer to greater than about 2-3 microns are possible Greater film thicknesses are possible where end use applications warrant such thicker films Multiple coating applications of layered thin films are preferred for prepaπng ceramic films that are 4 microns or more in thickness, to minimize stress cracking These coatings may also cover, or be covered by other coatings such as Sι0 2 coatings, Sιθ 2 /modιfyιng ceramic oxide layers, silicon containing coatings, silicon carbon containing coatings, silicon nitrogen containing coatings, silicon nitrogen carbon containing coatings, silicon oxygen nitrogen containing coatings, and/or diamond like carbon coatings Such coatings and their mechanism of deposition are known m the art For example, many are taught m Haluska, U S Patent No 4,973,526, November 27, 1990 The formation of the films of the invention is accomplished by a large v_.πe -, of techniques, which can conceptually be divided into two groups ( 1 ) film growth by interaction of a vapor-deposited species with the substrate, and (2) film formation by deposition without causing changes to the substrate or film mateπal See, for example, Bunshah et al, DEPOSITION TECHNOLOGIES FOR FILMS AND COATINGS, Noyes, Park Ridge, New Jersey, 1983, and Vossen et al , THIN FILM PROCESSES, Academic Press, New York, New York, 1978 The second group is most relevant to the present invention and it includes another three subclasses of deposition (a) chemical vapor deposition, or CVD, in which solid films are formed on a substrate by the chemical reaction of vapor phase chemicals that contain the required constituents; (b) physical vapor deposition, or PVD, in which the species of the thin film are physically dislodged from a source to form a vapor which is transported across a reduced pressure region to the substrate, where it condenses to form the thin film; and (c) coating of the substrate with a liquid, which is then dried to form the solid thin film. When a CVD process is used to form single-crystal thin films, the process is termed epitaxy. The formation of thin films by PVD includes the processes of sputtering and evaporation. There are currently three major types of chemical vapor deposition (CVD) processes, atmospheric pressure CVD (APCVD), low pressure (LPCVD) and plasma enhanced CVD (PECVD). Each of these methods has advantages and disadvantages. The choice of an appropriate CVD method and device for a particular application is well within the abilities of those of skill in the art. Atmospheric pressure CVD (APCVD) devices operate in a mass transport limited reaction mode at temperatures of approximately 400 °C. In mass-transport limited deposition, temperature control of the deposition chamber is less critical than in other methods: mass transport processes are only weakly dependent on temperature. As the arrival rate of the reactants is directly proportional to their concentration in the bulk gas, maintaining a homogeneous concentration of reactants in the bulk gas adjacent to the wafers is critical. Thus, to insure films of uniform thickness across a wafer, reactors that are operated in the mass transport limited regime must be designed so that all wafer surfaces are supplied with an equal flux of reactant. The most widely used APCVD reactor designs provide a uniform supply of reactants by horizontally positioning the wafers and moving them under a gas stream. In contrast to APCVD reactors, low pressure CVD (LPCVD) reactors operate in a reaction rate-limited mode. In processes that are run under reaction rate-limited conditions, the temperature of the process is an important parameter. To maintain a uniform deposition rate throughout a reactor, the reactor temperature must be homogeneous throughout the reactor and at all wafer surfaces. Under reaction rate- limited conditions the rate at which the deposited species arrive at the surface is not as critical as constant temperature. Thus, LPCVD reactors do not have to be designed to supply an invariant flux of reactants to all locations of a wafer surface. Under the low pressure of an LPCVD reactor, for example, operating at medium vacuum (30-250 Pa or 0.25-2.0 torr) and higher temperatures (550 -600 °C), the diffusivity of the deposited species is increased by a factor of approximately 1000 over the diffusivity at atmospheric pressure. The increased diffusivity is partially offset by the fact that the distance across which the reactants must diffuse increases by less than the square root of the pressure. The net effect is that there is more than an order of magnitude increase in the transport of reactants to the substrate surface and by-products away from the substrate surface LPCVD reactors are designed in two primary configurations (a) hoπzontal tube reactors; and (b) vertical flow isothermal reactors Hoπzontal tube, hot wall reactors are the most widely used LPCVD reactors in VLSI processing They are employed for depositing poly-Si, silicon nitride, and undoped and doped Sι0 2 films They find such broad applicability pnmaπly because of their supeπor economy, throughput, uniformity, and ability to accommodate large diameter (e g , 150 mm) wafers. The vertical flow isothermal LPCVD reactor further extends the distπbuted gas feed technique, so that each wafer receives an identical supply of fresh reactants Wafers are again stacked side by side, but are placed in perforated-quartz cages. The cages are positioned beneath long, perforated, quartz reaction-gas injector tubes, one tube for each reactant gas. Gas flows vertically from the injector tubes, through the cage perforations, past the wafers, parallel to the wafer surface and into exhaust slots below the cage The size, number, and location of cage perforations are used to control the flow of reactant gases to the wafer surfaces. By properly optimizing cage perforation design, each wafer can be supplied with identical quantities of fresh reactants from the vertically adjacent injector tubes. Thus, this design can avoid the wafer-to-wafer reactant depletion effects of the end- feed tube reactors, requires no temperature ramping, produces highly uniform depositions, and reportedly achieves low particulate contamination. The third major CVD deposition method is plasma enhanced CVD (PECVD) This method is categoπzed not only by pressure regime, but also by its method of energy input. Rather than relying solely on thermal energy to initiate and sustain chemical reactions, PECVD uses an rf-induced glow discharge to transfer energy into the reactant gases, allowing the substrate to remain at a lower temperature than in APCVD or LPCVD processes. Lower substrate temperature is the major advantage of PECVD, providing film deposition on substrates not having sufficient thermal stability to accept coating by other methods. PECVD can also enhance deposition rates over those achieved using thermal reactions. Moreover, PECVD can produce films having unique compositions and properties. Desirable properties such as good adhesion, low pinhole density, good step coverage, adequate electrical properties, and compatibility with fine-line pattern transfer processes, have led to application of these films in VLSI. PECVD requires control and optimization of several deposition parameters, including rf power density, frequency, and duty cycle. The deposition process is dependent in a complex and interdependent way on these parameters, as well as on the usual parameters of gas composition, flow rates, temperature, and pressure. Furthermore, as with LPCVD, the PECVD method is surface reaction limited, and adequate substrate temperature control is thus necessary to ensure uniform film thickness CVD systems usually contain the following components (a) gas sources, (b) gas feed lines, (c) mass-flow controllers for meteπng the gases into the system, (d) a reaction chamber or reactor, (e) a method for heating the wafers onto which the film is to be deposited, and in some types of systems, for adding additional energy by other means; and (f) temperature sensors LPCVD and PECVD systems also contain pumps for establishing the reduced pressure and exhausting the gases from the chamber. In a preferred embodiment, the films of the invention are produced using CVD with a heated substrate Cunng In a third aspect, the invention provides a low k dielectπc film compπsing a mateπal having the formula [H a SιO b ] c [(R 1 ) a SιO b ] d [(R 2 ) a SιO b ] n . In this formula R 1 and R 2 are members independently selected from to Cioo alkyl groups; a is less than or equal to 1, b is greater than or equal to 1.5; and c, d and n are members independently selected from the group consisting of the integers greater than 10, more preferably greater than 100, greater than 1000, greater than 10,000 or greater than 100,000. In a preferred embodiment, the precursor for this film is a silsesquioxane having the formula [R-SiOi 5 ] x [H-SιOι 5 ] y , wherein x + y = n, n is an integer between 2 and 30, x is an integer between 1 and n, and y is a whole number between 0 and n R is a Ci to Cioo alkyl group. In a further preferred embodiment, R is a C 2 to C_o alkyl group, preferably a C to C 40 alkyl group, and more preferably a C 6 to C 2 o alkyl group. This film is formed by cunng the film of silsesquioxane molecule deposited onto the substrate. When the alkyl group is a methyl group, the cured film contains methyl moieties. In contrast, when the alkyl group is a higher alkyl, C n (n =2 - 100), the process of cunng results in the extrusion of an alkene moiety having π-1 carbon atoms. The extrusion of the alkene moiety from the cunng film creates a pore in the film. The size of this pore can be manipulated by the size of the alkyl group of the film precursor Thus, films of varying porosity and, therefore, varying dielectnc constants can be formed using the methods of the invention. Thus, in a fourth aspect, the present invention provides a method for prepanng a porous low k dielectπc film having a preselected degree of porosity The film has the formula [H a SιO b ] c [(R') a SιO b ] d [(R 2 ) a SιO b ] n In this formula R 1 and R 2 are members independently selected from Q to Cioo alkyl groups, a is less than or equal to 1 , b is greater than or equal to 1 5, and c, d and n are members independently selected from the group consisting of the integers greater than 10 The method compπses depositing a film precursor compπsing a matenal having the formula [R-SιO t 5 ] x [H-SιOι 5 ] y wherein x - y = n, n is an integer between 2 and 30, x is an integer between 1 and n, y is a number between 0 and n, R is a C, to Cioo alkyl group and the R group is of a size sufficient to provide the preselected degree of porosity The deposited film precursor is then cured to produce the porous low k film As used herein, "degree of porosity" refers to both the size of the pores in the film and the number of pores per unit area The effect of any given R group on the degree of film porosity is easily determined Following a simple expeπmental protocol, one of skill can select a film precursor or series of film precursors that provide films with a preselected degree of porosity without undue expeπmentation In an exemplary expeπmental protocol, the size of the pores is vaπed over a seπes of films by the orderly vaπation of the size of the R group on the film precursor To a first approximation, an R group is selected, and the resulting pore size is estimated, on the basis of the van der Waals radius of the extruded alkene The van der Waals radius provides a useful parameter for estimating the size of the pore resulting from the extrusion of the alkene group To arrive at a desired level of porosity, a senes of films, having the same number of alkyl substituents, but varying in the size of the alkyl substituents is prepared and cured to produce the corresponding porous films The porosity of the films is then assessed by, inter alia, measuπng their density In another embodiment, the number of pores in a film is manipulated by varying the number of alkyl substituents on the film precursor The following discussion is generally applicable to the two aspects of the invention discussed immediately above Pπor to initiating the cunng process, a film reflow process can be performed to smooth the surface of the film After coating, silsesquioxane film reflow can be effected by raising the temperature of the substrate to a temperature between 120 °C and 200 °C, typically for about 5 minutes This step may be done in air, or in the cunng ambient, at a convenient pressure (typically atmosphenc) Alternately, this step can be combined with the following cunng step under most cunng conditions applicable to an ILD or PO deposition Prior art silsesquioxane-derived films have been cured in various ambients, resulting in widely varying properties. These ambients include air, ammonia, nitrogen, nitrogen/argon, and hydrogen/nitrogen. Generally, temperatures of about 400 °C and curing times of about 30 minutes to an hour are also taught in the pnor art. In particular, it has been found that curing in air produces a predominantly Si-0 film, curing in ammonia produces a silicon oxynitride type film, and curing in inert or reducing atmospheres results in films which retain some portion of the Si-H bonding inherent in uncured hydrogen silsesquioxane. The present invention is comprehended for use in silsesquioxane films dried and cured in all ambients, including reducing or inert ambients other than those discussed herein. Even films that are carefully cured under non-oxidizing conditions may eventually become exposed to moisture and/or oxygen, either during further processing of the device, during packaging, or in use. The invention is also comprehended for use with deposition methods that use trace amounts of a group VIII catalyst, such as Pt(acac) 2 , to further HSQ film curing. The formation of a silsesquioxane thin film is effected by processing the coated substrate, via treatment at moderately elevated temperatures or with UV irradiation, or an incident electron beam to convert the silsesquioxane molecule composition into a silsesquioxane thin film. This crosslinking conversion is carried out in a moisture- containing atmosphere containing at least about 0.5% relative humidity and preferably containing from about 15% relative humidity to about 100% relative humidity. The specified level of moisture may be present in the atmosphere during the entire processing procedure for forming the ceramic thin film or, alternatively, can be present during only a portion of the procedure. In addition to the moisture-containing atmosphere, and inert gases such as nitrogen, argon, helium or the like may be present or reactive gases such as air, oxygen, hydrogen chloride, ammonia and the like may be present. In one embodiment of this invention, the conversion of the silsesquioxane molecule on the coated substrate is accomplished via thermal processing, by heating the coated substrate. The temperature employed during the heating to form the thin film is moderate, preferably being at least about 100 °C, more preferably at least about 150 °C. Extremely high temperatures, which are often deleterious to other materials present on the substrate, e.g., particularly metallized electronic substrates, are generally unnecessary. Heating temperatures in the range of about 150 °C to about 700 °C are preferable, with temperatures in the range of about 200 °C to about 500 °C being more preferred. The exact temperature will depend on factors such as the particular substituted organosilsesquioxane molecule utilized, the composition of the atmosphere (including relative humidity), heating time, coating thickness and coating composition components The selection of appropπate conditions is well within the abilities of those of skill in the art Heating is generally conducted for a time sufficient to form the desired thin film The heating penod typically is in the range of up to about 6 hours Heating times of less than about 2 hours, e g . about 0 1 to about 2 hours, are preferred The heating procedure is generally conducted at ambient pressure (ι e , atmospheπc pressure), but subatmosphenc pressure or a partial vacuum or superatmospheπc pressures may also be employed Any method of heating, such as the use of a convection oven, rapid thermal processing, hot plate, or radiant or microwave energy is generally functional The rate of heating, moreover, is also not cntical, but it is most practical and preferred to heat as rapidly as possible In an alternative embodiment of this invention, the formation of a silsesquioxane thm film is accomplished by subjecting the coated substrate to ultraviolet (UV) irradiation or an electron beam Exposure of the coated substrate to such irradiation has been found to effect the desired crosshnking conversion of the silsesquioxane molecule in the coated substrate The irradiation treatment is ordinaπly earned out without subjecting the coated substrate to the elevated temperatures used m the thermal processing, but combinations of the irradiation and thermal processing treatments could be employed, if desired. The silsesquioxane thm films formed using irradiation-based processing are generally charactenzed as having higher Sι0 2 contents than typically result from thermal processing under otherwise identical coating conditions An advantage of the use of irradiation-based processing is that patterned films may be generated on a substrate by the selective focusing of the radiation Characteπzation Although the properties of a bulk mateπal are well charactenzed, the same matenal in its thin film form can have properties that are substantially different from those of the bulk mateπal One reason is that thm film properties are strongly influenced by surface properties, while in bulk mateπals this is not the case The thm film, by its very definition, has a substantially higher surface-to-volume ratio than does a bulk matenal The structure of thin films, and their method of preparation also play a vital role in determining the film properties There exists an array of art-recognized techniques for charactenzing thm films, including specular and off-specular x-ray and neutron reflectivity, energy-dispersive x-ray reflectivity, total external reflectance x-ray fluorescence MeV ion scatteπng atomic force microscopy and elhpsometry See, for example, Lin et al , Proc ACS PMSE 11 626 ( 1997), Wolf et al . SILICON PROCESSING FOR THE VLSI ERA, Volume 1 (Process Technology) (Lattice Press, Sunset Beach, Calif 1986), incorporated herein by reference Film thickness can be determined using commercially available instruments such as a Nanospec AFT Correction of film thickness for refractive index is frequently desirable Refractive index of thm films can be measured using an ehpsometer Such devices are commercially available (Rudolph) Other methods exist to charactenze surface roughness, film integπty, dielectπc constant and the like These methods are bπefly descnbed below It is well within the abilities of one of skill in the art to choose an appropπate method for determining a desired charactenstic of a film of the invention The out-of-plane thermal expansion of the thm films can be measured using a capacitance cell The sample is used to measure the capacitance of a precision parallel- plate capacitor of constant area so that the measured capacitance is inversely proportional to the actual sample thickness These measurements are typically made under conditions of controlled humidity The surface roughness of films occurs as a result of the randomness of the deposition process Real films almost always show surface roughness, even though this represents a higher energy state than that of a perfectly flat film Depositions at high temperatures tend to show less surface roughness This is because increased surface mobility from the higher substrate temperatures can lead to filling of the peaks and valleys On the other hand, higher temperatures can also lead to the development of crystal facets, which may continue to grow in favored directions, leading to increased surface roughness At low temperatures, the surface roughness as measured by surface area, tends to increase with increased film thickness. Oblique deposition that results in shadowing, also increases surface roughness Epitaxial and amorphous deposits have shown measured surface area nearly equal to the geometπcal area, implying the existence of very flat films This has been confirmed by Scanning Electron Micrography (SEM) examination of these films Thus, m a preferred embodiment, the surface roughness of the films of the invention is investigated by SEM and or AFM In a preferred embodiment, thin films of the invention are charactenzed further by being uniform and crack-free when viewed by electron micrography Infrared spectroscopy is also useful to characteπze the films of the invention For example, FTIR spectroscopy can provide information regarding the structure of films formed at different cure temperatures Different cure temperatures will frequently produce films having different IR spectra Moreover, infrared spectroscopy can be used to determine the silanol content of the thin film The organization of the film into a crystalline or amorphous structure can be determined using X-ray diffraction The density of the films of the invention can be vaned by selection of the film precursors Porosity develops during crosshnking of silsesquioxane molecules duπng the cunng stage The porosity of condensed silsesquioxane films is known to be a function of cure temperature both thickness and porosity decrease with increasing cure temperature due to densification The density of a thin film provides information about its physical structure Density is preferably determined by weighing the film and measunng its volume If a film is porous from the deposition process, it generally has a lower density than the bulk matenal The dielectnc constant of a particular film can be measured by the MOSCAP method which is known to one of skill in the art When the film is a component of a device with interconnect lines, the hne-to-line capacitance measurements can be earned out, for example, by using a 0 50/0 50 μm width/spacing comb structure Other methods for measunng dielectnc constants can be applied to the films of the present invention Substrate The choice of substrates to be coated is limited only by the need for thermal and chemical stability at the temperature and in the environment of the deposition vessel Thus, the substrate can be, for example, glass, metal, plastic, ceramic or the like It is particularly preferred herein, however, to coat electronic devices to provide a protective or dielectπc coating In an exemplary embodiment, the substrate is a semiconductor substrate (e g , of silicon) The substrate is functionalized with conductors which may be, for instance, formed of an alummum-0 5% copper alloy The dielectπc films of the present invention need not be deposited directly over a conducting layer (i e , other dielectnc layers may intervene or a conducting layer may not be present below the dielectnc film of the present invention) In general, the dielectnc film is deposited by, e g , CVD of a silsesquioxane film precursor over the substrate, followed by reflow and film cunng steps, which may be combined to convert the film to a final form Either dunng reflow or cunng (or between these steps), the film is typically subjected to a temperature between 120 °C and 200 °C for a peπod of time sufficient to produce silsesquioxane reflow and enhance the planaπzation of film In those substrates having interconnect lines, a metal layer is deposited and etched to form interconnect lines Any number of interconnect lines and interconnect line geometnes can be present Interconnect lines typically have a vertical thickness on the order of 0 5 - 2 0 micron and a hoπzontal thickness which vanes by design, but will typically be in the range of 0 25 to 1 micron After the formation of interconnect, a thm layer of a film of the invention or another film (e g , silicon dioxide) with a thickness on the order of 0 2-5 0 micron can optionally be deposited over the surface of the structure Objects Incorporating the Films In another aspect, the invention provides an object compnsing a low k dielectπc film, said film compπsing a mateπal having the formula [H a SιO b ] c [(R') a SιO b ] d [(R 2 ) a SιO b ] n In this formula R 1 and R 2 are members independently selected from Ci to Cioo alkyl groups, a is less than or equal to 1, b is greater than or equal to 1 5, and c, d and n are members independently selected from the group consisting of the integers greater than 10 Although the films of the invention can be incorporated into essentially any device or object in which a low k dielectπc film would have utility, in a preferred embodiment, the object compnses a wafer, preferably made of a matenal acting as a semiconductor Semiconductor wafers made of a vaπety of matenals are well known in the art and substantially all of these wafers are appropnate for coating with the films of the invention In a preferred embodiment, the compπses a member selected from Si, SiON, SiN, S1O 2 , Cu, Ta, TaN and combinations thereof, more piefciably Si, Sι0 2 and combinations thereof In another preferred embodiment, the wafer is metallized, preferably with a member selected from copper, titanium, titanium nitπde and combinations thereof It is understood that the examples and embodiments descπbed herein are for illustrative purposes only and that vaπous modifications or changes in light thereof will be suggested to persons skilled m the art and are to included within the spint and purview of this application and are considered within the scope of the appended claims All publications, patents, and patent applications cited herein are hereby incorporated by reference in their entirety for all purposes

Claims: CLAIMS: 1. A composition compπsing a mateπal having the formula [R-Sι0 1 5 ]χ[H-SιO, j] y , wherein R is a Ci to Cioo alkyl group, x - y = n n is an integer between 2 and 30, x is an integer between 1 and n, and y is a number between 0 and n 2. The composition according to claim 1, wherein said composition is in a vapor state 3. The composition according to claim 1, wherein n is a member selected from the group consisting of the integers from 6 to 16, inclusive 4. The composition according to claim 3, wherein n is a member selected from the group consisting of the integers from 8 to 12 5. The composition according to claim 1, wherein R is a Ci to C 20 straight- or branched-chain alkyl group 6. The composition according to claim 5, wherein R is a Ci to Ciβ straight- or branched-chain alkyl group 7. The composition according to claim 6, wherein R is a d to Cβ straight- or branched-chain alkyl group 8. The composition according to claim 1, wherein about 75% of said vapoπzed matenal has a molecular weight of less than about 3000 daltons 9. The composition according to claim 8, wherein about 75% of said vapoπzed mateπal has a molecular weight of less than about 1800 daltons 10. The composition according to claim 9, wherein about 75% of said vaponzed matenal has a molecular weight of less than about 1600 daltons 11. A method of forming a low k dielectnc film, said method compπsing (a) depositing onto a substrate, a material compπsing a film precursor having the formula [R-Sι0 1 5 ] x [H-Sι0 1 5 ] y , wherein x + y = n, n is an integer between 2 and 30, x is an integer between 1 and n, y is a whole number between 0 and n, R is a Ci to Cioo alkyl group 12. The method according to claim 11, wherein said depositing compπses a method selected from vapor deposition, spm-on, dip coating, spraying, sputtenng and combinations thereof 13. The method according to claim 16, wherein said vapor deposition compnses a member selected from chemical vapor deposition, physical vapor deposition and combinations thereof 14. The method according to claim 12, wherein said chemical vapor deposition compnses a member selected from atmosphenc chemical vapor deposition, low pressure chemical vapor deposition, plasma enhanced chemical vapor deposition and combinations thereof 15. A method of forming a low k dielectπc film, said method compnsmg (a) vaponzing a matenal to form a vapoπzed film precursor, said mateπal compπsing a film precursor having the formula [R-SiO, .] x [H-SiO, 5 ] y , wherein x + y = n, n is an integer between 2 and 30, x is an integer between 1 and n, y is a whole number between 0 and n, R is a Ci to Cioo alkyl group, and (b) depositing onto a substrate said vaponzed film precursor to form a deposited film precursor 16. The composition according to claim 15, wherein n is a member selected from the group consisting of the integers from 6 to 16, inclusive. 17. The method according to claim 16, wherein n is a member selected from the group consisting of the integers from 8 to 12. 18. The method according to claim 15, wherein R is C, to C 2 o straight- or branched-chain alkyl group. 19. The method according to claim 18, wherein R is a Ci to Ci 6 straight- or branched-chain alkyl group. 20. The method according to claim 19, wherein R is a Q to C 6 straight- or branched-chain alkyl group. 21. The method according to claim 15, wherein about 75% of said vaporized material has a molecular weight of less than about 3000 daltons. 22. The method according to claim 21, wherein about 75% of said vaporized material has a molecular weight of less than about 1800 daltons. 23. The method according to claim 22, wherein about 75% of said vaporized material has a molecular weight of less than about 1600 daltons. 24. The method according to claim 15, wherein said vaporizing is carried out at a temperature of from about 50 °C to about 300 °C. 25. The method according to claim 15, wherein said vaporizing is performed under vacuum. 26. The method according to claim 15, further comprising; (c) curing said deposited film precursor. 27. The method according to claim 26, wherein said curing is by a member selected from the group of heat, ultraviolet light, electron beam and combinations thereof. 28. The method according to claim 27, wherein said curing is accomplished by heating to a temperature of from about 150 °C to about 700 °C. _^ 29. The method according to claim 28, wherein said temperature is from about 200 °C to about 500 °C 30. A low k dielectπc film compnsing a mateπal having the formula [H a SιO b ] c [(R I )aSιO b ] d [(R 2 )_SιO b ] n , wherein R 1 and R 2 are members independently selected from Ci to Cioo alkyl groups, a is less than or equal to 1 , b is greater than or equal to 1 5, and c, d and n are members independently selected from the group consisting of the integers greater than 10 31. The method according to claim 30, wherein R 1 and R 2 are independently selected from Ci to C 2 o straight- or branched-chain alkyl group 32. The method according to claim 35, wherein R 1 and R 2 are independently selected from Ci to Ciβstraight- or branched-cham alkyl groups 33. The method according to claim 36, wherein R 1 and R 2 are independently selected from C \ to C straight- or branched-cham alkyl groups 34. The method according to claim 37, wherein R 1 and R 2 are both methyl groups 35. The film according to claim 30, wherein said film is a porous film 36. The film according to claim 30, wherein said film has a dielectπc constant of from about 0 1 to about 3 37. The film according to claim 36 , wherein said film has a dielectnc constant of from about 0 5 to about 2 38. A method for prepaπng a porous low k dielectnc film having a preselected degree of porosity, said film compnsing a matenal having the formula [H a SιO . ] . [(R l ) a SιO b M(R 2 )aSιO b ] n , wherein R 1 and R 2 are members independently selected from C, to Cioo alkyl groups, a is less than or equal to 1 , b is greater than or equal to 1 5, and c, d and n are members independently selected from the group consisting of the integers greater than 10, said method compnsing (a) depositing a film precursor to form a deposited film precursor, said film precursor comprising a mateπal having the formula [R-SiO, _] x [H-SiO, 5 ] y , wherein x + y = n, n is an integer between 2 and 30, x is an integer between 1 and n, y is a whole number between 0 and n, R is a Ci to Cioo alkyl group, and (b) cunng said deposited film precursor to form a low k dielectnc film with a preselected degree of porosity 39. The method according to claim 38, wherein said cunng is earned out using a method selected from the group of heat, ultraviolet light and combinations thereof 40. The method according to claim 39, wherein said cunng is earned out by heating to a temperature of from about 150 °C to about 700 °C 41. The method according to claim 40, wherein said temperature is fiom about 200 °C to about 500 °C. 42. The film according to claim 38, wherein said low k dielectnc film has a dielectnc constant of from about 0 1 to about 3 43. The film according to claim 42, wherein said low k dielectπc film has a dielectnc constant of from about 0 5 to about 2 44. An object compπsing a low k dielectnc film, said film compnsing a matenal having the formula [H a SiO b ] c [(R')aSiO b ] d [(R 2 ) a SiO b ] n , wherein R 1 and R 2 are members independently selected from Ci to Cioo alkyl groups; a is less than or equal to 1; b is greater than or equal to 1.5; and c, d and n are members independently selected from the group consisting of the integers greater than 10. 45. The object according to claim 44, wherein said object comprises a wafer. 46. The wafer according to claim 45, wherein said wafer comprises a member selected from Si, SiON, SiN, Siθ 2 , Cu, Ta, TaN and combinations thereof. 47. The wafer according to claim 45, wherein said wafer is a member selected from Si wafers, Si0 wafers and combinations thereof. 48. The wafer according to claim 47, wherein said wafer is metallized. 49. The metallized wafer according to claim 48, metallized with a member selected from copper, titanium, titanium nitride and combinations thereof.

Inventors: HACKER NIGEL P, HACKER, NIGEL, P.
Applicants: ALLIED SIGNAL INC, ALLIEDSIGNAL INC.
Application year: 2000
Main classification: C07F7
IPC codes: C07F7, C08G77, C23C14, C23C16, H01L21