Abstract:
High silicon-content resin composition that can be used to form thin film thermosets, useful in forming low k dielectric constant materials and as well as hard mask materials with anti-reflective properties for the photolithography industry are disclosed.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates generally to high silicon-content resin composition that can be used to form thin film thermosets, useful in forming low k dielectric constant materials and as well as hard mask materials with anti-reflective properties for the photolithography industry. 
     As the dimensions of microelectronic devices become smaller, the importance of fully exploiting the physical properties of the materials used in their manufacture becomes more essential. This is particularly true of the dielectric materials that are used to insulate metal lines, vias and electronic components from one another because of the contributions to capacitance that these materials make. Silicon dioxide has been employed within the industry as a dielectric material for the manufacture of devices for nearly three decades, but may become less suitable in the future because of its relatively high dielectric constant (k ˜ 4.1). Recently, however, siloxanes have made inroads into microlithography fabrication with low dielectric constant insulating layers and pattern transfer hard masks that exhibit antireflective properties. 
     Additionally, in current conventional semiconductor manufacturing, in order to prevent light reflection from being transmitted through the photo-resist, reflected off the substrate and back into the photoresist, where it can interfere with incoming light and so result in the uneven exposure of the photoresist, conventionally one or more antireflective layers may be deposited before the photoresist is deposited or spun on. In the absence of an antireflection coating, interference of reflected and incident exposure radiation can cause standing wave effects that distort the uniformity of the radiation through the thickness of the photoresist layer. Variations in reflectivity throughout the entire imaged areas can cause undesirable line width variation for features which are designed to have similar dimensions. 
     SUMMARY OF THE INVENTION 
     The present invention relates to a composition comprising: (a) a polymer comprising at least one repeating unit of formula ((A) j R 1 SiO (3-j)/2 ) and at least one repeating unit of formula ((A) k R 2 SiO (3-k)/2 ), where each R 1  individually is the same or different chromophore which absorbs at any actinic wavelength; each R 2  is individually selected from hydrogen, alkyl, alkenyl, cycloalkyl, and aralkyl; each A is an unreacted functional group of a monomer which forms either of the above repeating units; j and k are each integers that fall within the range 0≦j≦1 and 0≦k≦1, the ratio of R 1  to R 2  being from about 1:99 to about 60:40; (b) a halide source; and (c) a solvent. The polymer can also comprise an additional unit of formula (R f ) w (R g ) z SiO (4-w-z)/2 , where R f  and R g  are each individually selected from R 1  and R 2 ; and w and z are each integers within the limits 0≦(w or z)≦2 with the proviso that (4−w−z) does not equal 0. A method for forming an image on a substrate as well as an article of manufacture of a substrate, the inventive composition, and a photoresist are also provided. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention relates to a composition comprising: (a) a polymer comprising at least one repeating unit of formula ((A) j R 1 SiO (3-j)/2 ) and at least one repeating unit of formula ((A) k R 2 SiO (3-k)/2 ), where each R 1  individually is the same or different chromophore which absorbs at any actinic wavelength; each R 2  is individually selected from hydrogen, alkyl, alkenyl, cycloalkyl, and aralkyl; each A is an unreacted functional group of a monomer which forms either of the above repeating units; j and k are each integers that fall within the range 0≦j≦1 and 0≦k≦1, the ratio of R 1  to R 2  being from about 1:99 to about 60:40; (b) a halide source; and (c) a solvent. The polymer can also comprise an additional unit of formula (R f ) w (R g ) z SiO (4-w-z)/2 , where R f  and R g  are each individually selected from R 1  and R 2 ; and w and z are each integers within the limits 0≦(w or z)≦2 with the proviso that (4−w−z) does not equal 0. A method for forming an image on a substrate as well as an article of manufacture of a substrate, the inventive composition, and a photoresist are also provided. 
     The polymer of the present invention contains repeating units ((A) j R 1 SiO (3-j)/2 ) and ((A) k R 2 SiO (3-k)/2 ), which be prepared by methods known to those skilled in the art, for example, by hydrolytic condensation reactions of trifunctional organosilicon monomers such as RSiA 3 , RSiCl 3 , a silane ester (RSi(OR x ) 3 , where R x  can be an alkyl group, RSi(acyloxy) 3 , or RSi(alkylketoxime) 3 , or a hydrolyzed form of the above, where R can be R 1  or R 2 . Further information on preparing polymers of the present invention can be found in U.S. Pat. Nos. 5,290,354; 5,320,868; and 6,770,726. These reactions can form small oligomers, complex resins and networks. 
     Examples of R 1 , chromophores, include, but are not limited to, unsubstituted and substituted fluorene, vinylenephenylene, anthracene, perylene, phenyl, benzyl, chalcone, phthalimide, pamoic acid, acridine, azo compounds, dibenzofuran, any derivatives thereof thiophenes, anthracene, naphthalene, benzene, chalcone, phthalimides, pamoic acid, acridine, azo compounds, chrysenes, pyrenes, fluoranthrenes, anthrones, benzophenones, thioxanthones, heterocyclic aromatic rings containing heteroatoms selected from oxygen, nitrogen, sulfur, and combinations thereof, as well as derivatives of the foregoing. 
     The alkyl, alkenyl, cycloalkyl, and aralkyl groups of R 2  can be unsubstituted or substituted. Suitable substituents include those which, in the context of this invention, do not alter the properties of the groups, such as e.g., a halogen atom (e.g., fluorine, chlorine, bromine, iodine), hydroxy, alkoxy, mercapto, alkylmercapto, nitro, nitroso, cyano, sulfoxy, and the like. Examples of alkyl include methyl, butyl, isoamyl, and the like, alkenyl such as vinyl, allyl, and the like, cycloalkyl such as cyclohexyl, cyclopentyl, adamantyl, and the like, alkoxy such as, for example, methoxy group, ethoxy group, hydroxyethoxy group, propoxy group, hydroxypropoxy group, n-butoxy group, isobutoxy group, sec-butoxy group and t-butoxy group, aralkyl such as benzyl group, phenethyl group and cumyl group, aryloxy such as phenoxy group, and aryloxycarbonyl group such as benzoyloxy group. 
     Examples of the polymers include poly(phenyl-methylsilsesquioxane), 90:10 phenyl:methyl; poly(phenyl-propylsilsesquioxane), 70:30 phenyl:propyl; poly(phenyl-vinylsilsesquioxane), 90:10 phenyl:vinyl; copolymerized phenylsilsesquioxane-benzylsilsesquioxane, poly(phenyl-isobutylsilsesquioxane), poly(phenyl-isoamylsilsesquioxane), poly(phenyl-n-hexylsilsequioxane), poly(phenyl-benzoylsilsesquioxane), poly(phenyl-p-phenoxy silsesquioxane), poly(naphthyl-methylsilsesquioxane), poly(anthryl-methylsilsesquioxane), (40% phenyl-45% methylsilsesquioxane)-(5% phenylmethylsiloxane)(10% diphenylsiloxane) terpolymer and the like, etc. The polymers can also contain one or more repeating units of formula (R f ) w (R g ) z SiO (4-w-z)/2 , where R f  and R g  are each individually selected from R 1  and R 2  as described above and w and z are each integers within the limits 0≦(w or z)≦2 with the proviso that (4−w−z) does not equal 0 or 3. 
     Another component of the composition is a halide source. The halide source can be just about any material which provides a halide anion to react with the polymer. Depending upon the application of the composition of the present invention, it may be more advantageous to use certain halide sources over other halide sources. Examples of halide sources include aliphatic quaternary ammonium salts (e.g., a tetraC 1-6  alkylammonium halide such as tetramethylammonium chloride, tetraethylammonium chloride, tetramethylammonium bromide and tetraethylammonium bromide, a triC 1-6  alkylC 8-20  alkylammonium halide such as trimethyllaurylammonium chloride and trimethyllaurylammonium bromide, a diC 1-6  alkyldiC 8-20  alkylammonium halide such as dimethyldilaurylammonium chloride and dimethyldilaurylammonium bromide), especially a tetraC 1-4  alkylammonium halide (e.g., a tetraC 1-2  alkylammonium halide), a triC 1-4  alkylC 10-16  alkylammonium halide (e.g., a triC 1-2  alkylC 10-14  alkylammonium halide), a diC 1-4  alkyldiC 10-16  alkylammonium halide (e.g., a diC 1-2  alkyldiC 10-14  alkylammonium halide), aliphatic/aryl quaternary ammonium salts (e.g., benzyltriC 1-16  alkyl ammonium halide). Examples of these salts include tetrabutylammonium chloride, benzyltrimethylammonium chloride, tetraethylammonium chloride, benzyltributylammonium chloride, cetyltrimethylammonium chloride, methyltrioctylammonium chloride, tetrabutylammonium chloride, benzyltrimethylammonium chloride, as well as the corresponding fluorides, bromides, and iodides. 
     Other examples of suitable halide sources are diquaternary ammonium dihalide salts such as compounds having the general formula
 
[(R′) 3 N + (Z) m N + (R′) 3 ](X − ) 2  
 
wherein each R′ is individually alkyl of from 1 to 20 carbon atoms, heteroalkyl of from 1 to 20 carbon atoms, aryl, heteroaryl, cycloalkyl of from 3 to 6 carbon atoms, cycloheteroalkyl of from 3 to 6 carbon atoms, or combinations thereof; N is the quadricoordinate element nitrogen, or the heteroatom nitrogen in an alicyclic, heteroalicyclic or heteroaromatic structure X is an anion; Z is a bridging member selected from the group consisting of alkyl of from 1 to 20 carbon atoms, alkenyl of from 2 to 20 carbon atoms, aryl, heteroalkyl of from 1 to 20 carbon atoms, heteroalkenyl of from 2 to 20 carbon atoms and heteroaryl; and m is 1 to 10. Examples of these compounds include [(CH 3 ) 3 N + (CH 2 ) 6 N + (CH 3 ) 3 ](Cl − ) 2 , [(C 3 H 7 ) 3 N + (CH 2 ) 6 N + (C 3 H 7 ) 3 ](Cl − ) 2 , [(CH 3 ) 3 N + (C 2 H 4 ) 6 N + (CH 3 ) 3 ](Br − ) 2 , [(C 6 H 5 ) 3 N + (CH 2 ) 6 N + (CH 3 ) 3 ](Cl − ) 2 , [(C 6 H 5 ) 3 N + (C 2 H 4 ) 2 N + (CH 3 ) 3 ](Cl − ) 2 , and the like, etc. Another example of a diquaternary ammonium halide salt is N,N′-difluoro-2,2′-bipyridinium (bistetrafluoroborate) (known as MEC-31). Yet another example is tetrakis(dimethylamino)ethene (TDAE)/CF3 complex.
 
     Other examples of halide sources include tetraalkylammonium dihalotriaryl(or trialkyl or mixtures of aryl and alkyl) disilicate which have the general formula
 
[aryl] q [alklyl] r Si[F] s  
 
where q is 1 or 2, r is 1 or 2, and s is 2 or 3.
 
     One example is a compound having the formula 
                                
where R 1  is zero to three substituents, each of which are independently alkyl, alkenyl, aryl alkanoyl, alkoxy, or nitro; and R 2  is an alkyl group, an example being tetrabutylammonium difluorotriphenylsilicate.
 
     Other examples are compounds having the formulae 
                                
where R 1  and R 2  are defined above.
 
     These types of salts are more fully described in U.S. Pat. Nos. 6,414,173 and 6,203,721, both of which are incorporated herein by reference. 
     Additional diquaternary ammonium halide salts are also diquaternary ammonium salts of DABCO (1,4-diazabicyclo[2.2.2]octane), shown by the formula 
                                
where n is 1 to 10 and X is a halide. These salts are more fully described in U.S. Pat. No. 4,559,213, which is incorporated herein by reference.
 
     Other halide sources include alkali metal salts (e.g., LiCl, NaCl, KCl, KBr, etc), alkaline earth metal salts (e.g., CaCl 2 , MgCl 2 , etc), pyridinium salts such as benzyl-3-hydroxypyridinium chloride, imidazolidine salts such as 1,3-didecyl-2-methylimidazolium chloride, tetrazolium salts such as 2,3,5-triphenyl-tetrazolium chloride, and the like, etc. Yet other halide sources include halogenated organic compounds that can release halide by an elimination reaction under heat. 
     In many instances, the nitrogen atom in the above salts can be replaced with a Group VA element such as phosphorus, antimony, and arsenic, such as tetrabutylphosphonium chloride, tetramethylphosphonium chloride, tetraphenylphosphonium chloride, and the like. 
     Other halide sources include materials such as 1-fluoro-4-chloromethyl-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate) (tradename Selectfluor), 1-fluoro-4-hydroxy-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate) (tradename Accufluor), N,N′-difluoro-2,2′-bipyridinium bis(tetrafluoroborate), the ‘N—F’ reagents (e.g., R 2 N—F), the ‘[N—F] + ’ reagents (e.g., R 3 N + —F), 2,2-difluoro-1,3-dimethylimidazolidine, diethylaminosulfur trifluoride, R a R b N—CF 2 —R c , where R a  is hydrogen or alkyl and R b  and R c  are each selected from alkyl or aryl (tradename Fluorinox), perfluorobutanesulfonyl fluoride, and the like, etc. 
     The halide source is generally present in the composition from about 1 to about 20 percent based on the total resin solids of the composition. Applicants have found that best results of the present invention are achieved when the inventive compositions are allowed to stand for about twenty-four hours before being used to coat substrates, etc. 
     Another component in the inventive composition is a solvent. Suitable solvents for such photoresists may include for example ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, isophorone, methyl isoamyl ketone, 2-heptanone 4-hydroxy, and 4-methyl 2-pentanone; C 1  to C 10  aliphatic alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, phenol, and the like; aromatic group containing-alcohols such as benzyl alcohol; cyclic carbonates such as ethylene carbonate and propylene carbonate; aliphatic or aromatic hydrocarbons (for example, hexane, toluene, xylene, etc and the like); cyclic ethers, such as dioxane and tetrahydrofuran; ethylene glycol; propylene glycol; hexylene glycol; ether alcohols, for example, 1-butoxyethoxy-2-propanol, 3-methyl-3-methoxybutanol, ethylene glycol n-butyl ether, ethylene glycol phenyl ether, ethylene glycol monomethylether, ethylene glycol monoethylether, ethylene glycol propyl ether, diethylene glycol hexyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, diethylene glycol monopropyl ether, propylene glycol ethyl ether, propylene glycol isobutyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, propylene glycol monoethyl ether, propylene glycol n-propyl ether, propylene glycol phenyl ether, propylene glycol-t-butyl ether, dipropylene glycol ethyl ether, dipropylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monopropyl ether, triethylene glycol ethyl ether, triethylene glycol methyl ether, triethylene glycol n-butyl ether, tripropylene glycol methyl ether, tripropylene glycol n-butyl ether; ethylene glycol alkylether acetates such as methylcellosolve acetate and ethylcellosolve acetate; propylene glycol alkyletheracetates such as propylene glycol methylether acetate, propylene glycol ethylether acetate, propylene glycol propylether acetate, and propylene glycol butylether acetate; propylene glycol alkyletherpropionates such as propylene glycol methyletherpropionate, propylene glycol ethyletherpropionate, propylene glycol propyletherpropionate, and propylene glycol butyletherpropionate; 2-methoxyethyl ether (diglyme); solvents that have both ether and hydroxy moieties such as methoxy butanol, ethoxy butanol, methoxy propanol, and ethoxy propanol; esters such as methyl acetate, ethyl acetate, propyl acetate, and butyl acetate methyl-pyruvate, ethyl pyruvate; ethyl 2-hydroxy propionate, methyl 2-hydroxy 2-methyl propionate, ethyl 2-hydroxy 2-methyl propionate, methyl hydroxy acetate, ethyl hydroxy acetate, butyl hydroxy acetate, methyl lactate, ethyl lactate, propyl lactate, butyl lactate, methyl 3-hydroxy propionate, ethyl 3-hydroxy propionate, propyl 3-hydroxy propionate, butyl 3-hydroxy propionate, methyl 2-hydroxy 3-methyl butanoic acid, methyl methoxy acetate, ethyl methoxy acetate, propyl methoxy acetate, butyl methoxy acetate, methyl ethoxy acetate, ethyl ethoxy acetate, propyl ethoxy acetate, butyl ethoxy acetate, methyl propoxy acetate, ethyl propoxy acetate, propyl propoxy acetate, butyl propoxy acetate, methyl butoxy acetate, ethyl butoxy acetate, propyl butoxy acetate, butyl butoxy acetate, methyl 2-methoxy propionate, ethyl 2-methoxy propionate, propyl 2-methoxy propionate, butyl 2-methoxy propionate, methyl 2-ethoxypropionate, ethyl 2-ethoxypropionate, propyl 2-ethoxypropionate, butyl 2-ethoxypropionate, methyl 2-butoxypropionate, ethyl 2-butoxypropionate, propyl 2-butoxypropionate, butyl 2-butoxypropionate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, propyl 3-methoxypropionate, butyl 3-methoxypropionate, methyl 3-ethoxypropionate, ethyl 3-ethoxypropionate, propyl 3-ethoxypropionate, butyl 3-ethoxypropionate, methyl 3-propoxypropionate, ethyl 3-propoxypropionate, propyl 3-propoxypropionate, butyl 3-propoxypropionate, methyl 3-butoxypropionate, ethyl 3-butoxypropionate, propyl 3-butoxypropionate, and butyl 3-butoxypropionate; oxyisobutyric acid esters, for example, methyl-2-hydroxyisobutyrate, methyl α-methoxyisobutyrate, ethyl methoxyisobutyrate, methyl α-ethoxyisobutyrate, ethyl α-ethoxyisobutyrate, methyl β-methoxyisobutyrate, ethyl β-methoxyisobutyrate, methyl β-ethoxyisobutyrate, ethyl β-ethoxyisobutyrate, methyl β-isopropoxyisobutyrate, ethyl β-isopropoxyisobutyrate, isopropyl β-isopropoxyisobutyrate, butyl β-isopropoxyisobutyrate, methyl β-butoxyisobutyrate, ethyl β-butoxyisobutyrate, butyl β-butoxyisobutyrate, methyl α-hydroxyisobutyrate, ethyl α-hydroxyisobutyrate, isopropyl α-hydroxyisobutyrate, and butyl α-hydroxyisobutyrate; and other solvents such as dibasic esters, and gamma-butyrolactone; a ketone ether derivative such as diacetone alcohol methyl ether; a ketone alcohol derivative such as acetol or diacetone alcohol; lactones such as butyrolactone; an amide derivative such as dimethylacetamide or dimethylformamide, anisole, and mixtures thereof. It has been found that for enhanced stability and/or solubility, solvents selected from alcohols and ether alcohols are preferred. 
     An optional component which can be added to the composition is a porogen, which can be used to reduce the dielectric constant of film formed by the inventive composition. As used herein, by “porogen” is meant any pore-generating compounds, for example, a thermal- and/or radiation-labile organic polymer capable of decomposition to small molecules and subsequent volatilization to form a nanopore thereby). The conditions for forming such porous low-k dielectric layers are well known to those skilled in the art. 
     The composition of the present invention can be coated on the substrate using techniques well known to those skilled in the art, such as dipping, spincoating or spraying. The film thickness of the anti-reflective coating ranges from about 0.01 μm to about 1 μm. The coating can be heated on a hot plate or convection oven or other well known heating methods to remove any residual solvent and induce crosslinking if desired, and insolubilizing the anti-reflective coatings to prevent intermixing between the anti-reflective coating and the photoresist. 
     There are two types of photoresist compositions, negative-working and positive-working. When negative-working photoresist compositions are exposed image-wise to radiation, the areas of the resist composition exposed to the radiation become less soluble to a developer solution (e.g. a cross-linking reaction occurs) while the unexposed areas of the photoresist coating remain relatively soluble to such a solution. Thus, treatment of an exposed negative-working resist with a developer causes removal of the non-exposed areas of the photoresist coating and the creation of a negative image in the coating, thereby uncovering a desired portion of the underlying substrate surface on which the photoresist composition was deposited. 
     On the other hand, when positive-working photoresist compositions are exposed image-wise to radiation, those areas of the photoresist composition exposed to the radiation become more soluble to the developer solution (e.g. a rearrangement reaction occurs) while those areas not exposed remain relatively insoluble to the developer solution. Thus, treatment of an exposed positive-working photoresist with the developer causes removal of the exposed areas of the coating and the creation of a positive image in the photoresist coating. Again, a desired portion of the underlying surface is uncovered. 
     Negative working photoresist and positive working photoresist compositions and their use are well known to those skilled in the art. 
     A process of the instant invention comprises coating a substrate with a composition of the present invention and heating the substrate on a hotplate or convection oven or other well known heating methods at a sufficient temperature for sufficient length of time to remove the coating solvent, and crosslink the polymer, to a sufficient extent so that the coating is not soluble in the coating solution of a photoresist or in a aqueous alkaline developer. An edge bead remover may be applied to clean the edges of the substrate using processes well known in the art. The heating ranges in temperature from about 70° C. to about 250° C. If the temperature is below 70° C. then insufficient loss of solvent or insufficient amount of crosslinking may take place, and at temperatures above 250° C., the polymer may become chemically unstable. A film of a photoresist composition is then coated on top of the anti-reflective coating and baked to substantially remove the photoresist solvent. The photoresist is image-wise exposed and developed in an aqueous developer to remove the treated resist. An optional heating step can be incorporated into the process prior to development and after exposure. The process of coating and imaging photoresists is well known to those skilled in the art and is optimized for the specific type of resist used. The patterned substrate can then be dry etched in a suitable etch chamber to remove the exposed portions of the anti-reflective film, with the remaining photoresist acting as an etch mask. 
     The following specific examples will provide detailed illustrations of the methods of producing and utilizing compositions of the present invention. These examples are not intended, however, to limit or restrict the scope of the invention in any way and should not be construed as providing conditions, parameters or values which must be utilized exclusively in order to practice the present invention. 
     Example 1 
     Poly(phenyl-methylsilsesquioxane) 90:10 phenyl:methyl, was obtained from Gelest. A solution of 2.5 weight % of poly(phenyl-methylsilsesquioxane) 90:10 phenyl:methyl in propylene glycol monomethyl ether was made. Varying amounts of tetrabutylammonium chloride, from 2 weight % to 10 weight % based on the solid content of the poly(phenyl-methylsilsesquioxane), were added to aliquots of the solution and mixed. The aliquots were allowed to stand for 24 hours. Aliquots of each solution were then placed on different silicon wafers and spun cast at 2000 rpm to form film thicknesses of 60 nm (when measured after heating). The coated wafers were then heated at 250° C. The film thickness was measured by VASE. The coated wafers were then soaked in propylene glycol monomethyl ether acetate for 30 seconds and the film thickness was measure on a VASE. As the amount of tetrabutylammonium chloride was increased from 0 weight % to 10 weight %, there was complete film loss at 0 weight % of tetrabutylammonium chloride and then from 2.5 weight % to 10 weight % of tetrabutylammonium chloride, the film thickness loss ranged from 2 to 3.5 nm. 
     Example 2 
     Ten grams of poly(phenyl-propylsilsesquioxane) [70:30 phenyl:propyl; available from Gelest, Inc., Morrisville, Pa.] and 130 g of ethyl lactate were combined by stirring in a bottle. After letting the formulation stand for one day, an aliquot of the formulation was spin coated onto a silicon wafer and the wafer was heated to 200° C. The film was tested for solubility by submerging part of the wafer in PGMEA. All of the film was removed in the soaked regions. This test was repeated using 250 and 300° C. bakes and the results were the same. 
     Example 3 
     Five grams of poly(phenyl-propylsilsesquioxane) [70:30 phenyl:propyl; available from Gelest, Inc., Morrisville, Pa.], 95 g of ethyl lactate and 0.25 g of tetrabutylammonium difluorotriphenylsilicate were combined with mixing in a suitable bottle. After letting the formulation stand for one day, an aliquot of the formulation was spin coated onto a silicon wafer and the wafer was heated to 150° C. The film was tested for solubility by submerging part of the wafer in PGMEA. All film in the soaked area remained. When higher temperatures were used to bake the films, the films in the soaked areas were not affected. When the wafer was not baked, the film is completely removed. 
     Example 4 
     Five grams of poly(phenyl-propylsilsesquioxane) [70:30 phenyl:propyl; available from Gelest, Inc., Morrisville, Pa.], 100 g of ArF thinner (available from AZ Electronic Materials) and 0.25 g of tetrabutylammonium fluoride were combined with mixing in a suitable bottle. After letting the formulation stand for one day, an aliquot of the formulation was spin coated onto a silicon wafer and the wafer was heated to 250° C. The film was tested for solubility by submerging part of the wafer in PGMEA. All film in the soaked area remained. When higher temperatures were used to bake the films, the films in the soaked areas were not affected. When the wafer was not baked, the film is completely removed. 
     Example 5 
     Two ml aliquots of Example 1 were placed into suitable bottles and four different formulations were made by adding varying amounts of a 5% solution of tetrabutylammonium chloride (TBAC) in PGME with stirring: (a) 0 drop of 5% solution of TBAC [control]; (b) 1 drop of 5% solution of TBAC; (c) 5 drops of 5% solution of TBAC; and (d) 15 drops of 5% solution of TBAC. After letting the formulations stand for one day, aliquots of each formulation were spin coated onto a silicon wafer and the wafer was heated to 250° C. The film formed by each aliquot of formulation was tested for solubility by submerging part of the wafer in PGMEA. Except for the formulation with no TBAC ((a); control), all other films remained intact and were cured.