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polymerization. The anhydride moiety is a second functional group that is capable of reacting with a variety of other functional groups to afford covalently bonded products. An example of a functional group that an anhydride moiety can react with is a hydroxy group in an alcohol to form an ester linkage. Upon reaction of the anhydride moiety of ITA with a hydroxy group, there is formed an ester linkage and a free carboxyic acid moiety, which is a third functional group. The carboxylic acid functional group is useful in imparting aqueous processability to the resists of this invention. If a PAG is utilized having a hydroxy group, it is possible, as illustrated in some of the examples, to covalently link (tether) a PAG (or other photoactive components) to a branched polymer comprised of ITA comonomer or the like via this type of ester linkage ( or other covalent linkages, such as amide, etc.). 

[0079] The branched polymer may be prepared by any conventional addition polymerization process. The branched polymer, or comb polymer, may be prepared from one or more compatible ethylenically unsaturated macromer com› ponents and one or more compatible, conventional ethyl› enically unsaturated comonomer component(s). Preferred addition polymerizable, ethylenically unsaturated comono› mer components are acrylates, methacrylates, and styrenics as well as mixtures thereof. Suitable addition polymerizable, ethylenically unsaturated comonomer components include: tertiary-butyl methacrylate (tBMA), tertiary-butyl acrylate (tBA), methyl methacrylate (MMA); ethyl methacrylate (EMA); butyl methacrylate (EMA); 2-ethylhexyl methacry› late; methyl acrylate (MA); ethyl acrylate (EA); butyl acry› late (BA); 2-ethylhexyl acrylate; 2-hydroxyethyl methacry› late (HEMA); 2-hydroxyethyl acrylate (HEA); methacrylic acid (MAA); acrylic acid (AA); acrylonitrile (AN); meth› acrylonitrile (MAN); itaconic acid {IA) and itaconic acid anhydride (ITA), half ester and imide; maleic acid and maleic acid anhydride, half ester and imide; aminoethyl methacrylate; t-butyl aminoethyl methacrylate; dimethyl aminoethyl methacrylate; diethyl aminoethyl methacrylate; aminoethyl acrylate; dimethyl aminoethyl acrylate; diethyl aminoethyl acrylate; acrylamide; N-t-octyl acrylamide; vinyl methyl ethers; styrene (S); alpha-methyl styrene; vinyl acetate; vinyl chloride; and the like. The majority of the copolymerizable monomer must be acrylate or styrenic or copolymers of these monomers with acrylates and other vinyl monomers. 

[0080] Each constituent linear backbone segment and/or branch segment of the branched polymer of this invention may contain a variety of functional groups. A "functional group" is considered to be any moiety capable of being attached to a backbone segment or a branch segment by a direct valence bond or by a linking group. Illustrative of functional groups which can be borne by the backbone segment or the branch segments are -COOR 24 ; -OR 24 ; -SR $^{24 }$wherein R $^{24 }$can be hydrogen, alkyl group having 1 to 12 carbon atoms; cycloalkyl group of 3-12 carbon atoms; aryl, alkaryl or aralkyl group having 6 to 14 carbon atoms; a heterocyclic group containing 3 to 12 carbon atoms and additionally containing at least one S, 0, N or P atom; or -0R $^{27 }$where R $^{27 }$can be alkyl of 1-12 carbon atoms, aryl, alkaryl or aralkyl group having 6 to 14 carbon atoms; -CN; -NR2sR26 or 

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[0081] wherein R 25 and R 26 can be hydrogen, alkyl group having 1 to 12 carbon atoms; cycloalkyl group having of 3-12 carbon atoms; aryl, alkaryl, aralkyl of 6 to 14 carbon atoms; -CH$_{2}$0R $^{28 }$wherein R $^{28 }$is hydrogen, alkyl of 1 to 12 carbon atoms; or cycloalkyl of 3-12 carbon atoms, aryl, alkaryl, aralkyl having 6 to 14 carbon atoms, or together R 25 and R $^{26 }$can form a heterocyclic ring having 3 to 12 carbon atoms and containing at least one S, N, 0 or P; 

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[0082] wherein R 29 , R 30 and R 31 can be hydrogen, alkyl of 1 to 12 carbon atoms or cycloalkyl of 3-12 carbon atoms; aryl, alkaryl, aralkyl of 6 to 14 carbon atoms, or -COOR 24 or when taken together R 29 , R 30 and/or R 31 can form a cyclic group; -S0$_{3}$H; a urethane group; an isocyanate or blocked isocyanate group; a urea group; an oxirane group; an aziri› dine group; a quinone diazide group; an azo group; an azide group; a diazonium group; an acetylacetoxy group; -SiR $^{32}$R$^{33}$R $^{34 }$wherein R 32 , R $^{33 }$and R $^{34 }$can be alkyl having 1-12 carbon atoms or cycloalkyl of 3-12 carbon atoms or -OR 35 where R 35 is alkyl of 1-12 carbon atoms or cycloalkyl of 3-12 carbon atoms; aryl, alkaryl or aralkyl of 6 to 14 carbon atoms; or an -0S0$_{3}$R 36 , -OP0$_{2}$R 36 , -PO2I~t, -P R36R37R3s, -OPOR36, -SR36R37, or -N+R R $^{37}$R38 group (where R 36 , R 37 , and R 38 can be hydrogen, alkyl of 1 to 12 carbon atoms or cycloalkyl of 3-12 carbon atoms; aryl, alkaryl or aralkyl of 6 to 14 carbon atoms; or a salt or onium salt of any of the foregoing. Preferred functional groups are -COON, -OH, -NH$_{2}$, an amide group, a vinyl group, a urethane group, an isocyanate group, a blocked isocyanate group or combinations thereof. Functional groups may be located anywhere on the branched polymer. However, it is sometimes desirable to choose comonomers which impart bulk polymer characteristics to the linear backbone segment of the branched polymer and macromers which impart physical and chemical functional› ity to the branch segments in addition to hydrophilicity, such as solubility, reactivity, and the like. 

[0083] In certain preferred embodiments of this invention, the branched polymer contains functional groups that are compatible with the photoacid generator, said functional groups being distributed in the branched polymer such that 25 to 100% of the functional groups are present in the segment of the branched polymer containing a majority of the protected acid groups. These functional groups are desirable since having enhanced compatibility of the pho› toacid generator with the branched polymer segmented having the majority of protected acid groups results in higher photospeed and perhaps higher resolution and/or other desirable properties of resists comprised of these branched polymer(s) having these functional groups to pro› mote compatibility. For an ionic PAG, such as a triarylsul› fonium salt, functional groups that promote compatibility 

