US 10,474,032 B2  16  15  A further preferred optional additive is one or more  surfactants, which can promote formation of a substantially  uniform coating layer of the overcoated composition. A  variety of surfactants may be employed. Suitable surfactants  may exhibit an amphiphilic nature, meaning that they can be  both hydrophilic and hydrophobic at the same time. Amphi› philic surfactants possess a hydrophilic head group or  groups, which have a strong affinity for water and a long  hydrophobic tail, which is organophilic and repels water.  Suitable surfactants may be ionic (i.e., anionic, cationic) or  nonionic. Further examples of surfactants include silicone  surfactants, poly(alkylene oxide) surfactants, and fluoro› chemical surfactants. Suitable non-ionic surfactants for use  in the aqueous solution include, but are not limited to, octyl  and nonyl phenol ethoxylates such as TRITONfi X-114,  X-102, X-45, X-15 and alcohol ethoxylates such as BRIJfi  56 (C$_{16}$H$_{33 }$ (OCH$_{2}$CH$_{2}$ ) $_{10}$OH)(ICl), BRIJfi 58 (C$_{16}$H$_{33 }$ (OCH$_{2}$CH$_{2}$ )  20OH)(IC1). Still further exemplary surfac› tants include alcohol (primary and secondary) ethoxylates,  amine ethoxylates, glucosides, glucamine, polyethylene gly› cols, poly(ethylene glycol-co-propylene glycol), or other  surfactants disclosed in  McCutcheon ’s Emulsifiers and  Detergents,  North American Edition for the Year 2000  published by Manufacturers Confectioners Publishing Co.  of Glen Rock, N.J.  Nonionic surfactants that are acetylenic dial derivatives  also can be suitable, including such surfactants of the  following Formulae IV and  V:  wherein in those Formulae IV and V R$_{1 }$ and R$_{4 }$ are a  straight or a branched alkyl chain suitably having from 3 to  10 carbon atoms; R$_{2 }$ and R$_{3 }$ are either Hor an alkyl chain  suitably having from 1 to 5 carbon atoms; and m, n, p, and  q are numbers that range from 0 to 20. Such surfactants are  commercially available from Air Products and Chemicals,  Inc. of Allentown, Pa. trade names of SURFYNOLfi and  DYNOLfi.  Additional suitable surfactants for use in coating compo› sitions of the invention include other polymeric compounds  such as the tri-block EO-PO-EO co-polymers PLURONICfi  25R2, L121, L123, L31, LSI, Ll0l and P123 (BASF, Inc.).  For at least certain applications, coating compositions that  contain one or more zwitterion surfactants also will be  suitable.  Additional optional additives for the coating composi› tions may include stabilizing agents which can promote  enhanced shelf life of the prepared composition. Suitable  stabilizing agents may include poly-acids such as diacids  and triacids e.g. citric acid, malonic acid. Additional stabi› lizing agents that may be suitable for coating compositions  of the invention may be a peroxide materials such as  reported in U.S. Pat. No. 6,750,257 and Japanese Patent  JP200204568681, which discloses use of hydrogen peroxide  as a stabilizing agent in an amount of 5 to 100 ppm in a  colloidal silica composition.  A yet further optional additive for coating compositions of  the invention will be one or more acids and/or acid generator  compounds. As discussed above, inclusion of an acid source  in a coating composition of the invention can provide  enhanced resolution of an image patterned in an underlying  photoresist layer, including to control the profile of devel› oped photoresist image. As shown in Example 14 which  follows, it has been found that the absence of an acid in an  overcoated coating composition of the invention can result  in undesired T-topping of developed resist image whereas  the inclusion of an acid source in an overcoated coating  composition of the invention can provide a desired rounded  profile of the imaged resist layer.  Suitable acid additives can be both organic and inorganic  acids. Exemplary acid additives include e.g. nitric acid,  sulfuric acid, trichloroacetic acid, trifluoroacetic acid, oxalic  acid, maleic acid, malonic acid, succinic acid, maleic acid,  citric acid, tartaric acid, para toluene sulfonic acid, trifluo- romethylbenzenesulfonic acid, camphor sulfonic acid, and  trifluoromethane sulfonic acid.  Suitable amounts of one or more acids in a coating  composition of the invention may vary within a wide range  and may be readily optimized for any particular composition  by simple testing (e.g. by evaluating resolution of under› coated imaged photoresist) and consideration of factors such  as acid pKa, mobility and size. Suitable acid loading levels  may include less than 5 weight percent of the fluid coating  composition, more preferably less than 1 weight percent of  the fluid coating composition, and even more preferably less  than 0.5% by weight of fluid coating composition, such as  within a range of from 0.1 to 0.4 weight percent of the fluid  coating composition.  Suitable acid generator compounds include photoacid  generator compounds and thermal acid generator com› pounds. Exemplary thermal acid generator compounds  include both ionic as well as substantially neutral thermal  acid generators, e.g. an ammonium arenesulfonate salt.  Suitable thermal acid generator compounds are commer- cially available such as from King Industries. Suitable  photoacid generator compounds to employ in a coating  composition include onium salts, particularly iodonium and  sulfonium compounds such as those discussed below with  respect to photoresists. Exemplary acid generator com- pounds that may be employed in a coating composition of  the invention include triphenyl sulfonium camphor sul› fonate, triphenyl sulfonium trifluormethane sulfonate, triph› enyl sulfonium trifluorooctane sulfonate, triphenyl sulfo› nium  trifluorobutane  sulfonate,  triphenyl  sulfonium  trifluormethylbenzene sulfonate, triphenyl sulfonium para› toluene sulfonate, ammonium camphor sulfonate, ammo› nium trifluormethane sulfonate, ammonium trifluorooctane  sulfonate, ammoniumtrifluorobutane sulfonate, ammonium  trifluormethylbenzene sulfonate, and ammonium para-tolu- ene sulfonate. Other photoacid generator compounds iden› tified below for use in connection with photoresists can be  employed in an overcoated coating composition of the  II  ~  O O n  ~  II  o~ 0