May 12, 2005  8  US 2005/0100814 Al  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  [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;  [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 