May  12, 2005  4  US 2005/0100814 Al  fluoroalkyl group of from 1 to about 10 carbon atoms. The  fluorine-containing copolymers of this invention can be  comprised of any integral number of additional fluorine› containing comonomers, which include, but are not limited  to, those listed supra. Preferred comonomers are tetrafluo› roethylene, chlorotrifluoroethylene, hexafluoropropylene,  trifluoroethylene and RfOCF=CF$_{2}$ ,  wherein Rf is a satu› rated fluoroalkyl group of from 1 to about 10 carbon atoms.  More preferred comonomers are tetrafluoroethylene, chlo› rotrifluoroethylene,  hexafluoropropylene,  and  RfOCF=CF$_{2}$ ,  wherein Rf is a saturated perfluoroalkyl group  of from 1 to about 10 carbon atoms. Most preferred comono› mers are tetrafluoroethylene and chlorotrifluoroethylene.  [0054]  Representative comonomers having structure  H  include, but are not limited to:  [0048]  that undergoes free radical polymerization will  afford a polymer having a repeat unit:  [0049]  where  P,  Q, S, and T independently can represent,  but are not limited to,  H,  F, Cl, Br, an alkyl group containing  1 to 14 carbon atoms, aryl, aralkyl group containing 6 to 14  carbon atoms or a cycloalkyl group containing 3 to 14  carbon atoms.  [0050]  If  only one ethylenically unsaturated compound  undergoes polymerization, the resulting polymer is a  homopolymer.  If  two or more distinct ethylenically unsat› urated compounds undergo polymerization, the resulting  polymer is a copolymer.  [0051]  Some representative examples of ethylenically  unsaturated compounds and their corresponding repeat units  are given below:  [0055]  Representative comonomers having structure I  include, but are not limited to:  [0052]  In the sections that follow, the photoresist compo› sitions of this invention are described in terms of their  component parts.  [0053]  The photoresists of this invention comprise a fluo› rine-containing copolymer comprising a repeat unit derived  from at least one ethylenically unsaturated compound char› acterized in that at least one ethylenically unsaturated com› pound is polycyclic and at least one ethylenically unsatur› ated compound contains at least one fluorine  atom  covalently attached to an ethylenically unsaturated carbon  atom. Representative ethylenically unsaturated compounds  that are suitable for the fluorine-containing copolymers of  this invention include, but are not limited to, tetrafluoroet› hylene, chlorotrifluoroethylene, hexafluoropropylene, trif› luoroethylene, vinylidene fluoride, vinyl fluoride, perfluoro› (2,2-dimethyl-1,3-dioxole ),  perfluoro-(2-methylene-4- methyl-1,3-dioxolane, CF$_{2}$=CFO(CF$_{2}$),CF=CF$_{2}$ ,  where t  is 1 or 2, and RfOCF=CF$_{2 }$ wherein Rf is a saturated  [0057]  Representative comonomers having structure  K  include, but are not limited to:  \  c=c  I  \  S  T  \  -f  ’/  \  S  T  F  F  \  I  c=c  I  \  F  F  H  H  \  I  c=c  I  \  H  0  \ ~o  C  \  CH3  F  F  \  I  -ff-er  F  F  H  H  \  I  -ff-er  H  $^{0 }$\~O  C  \ $_{CH3 }$ [0056]  Representative comonomers having structure  J  include, but are not limited to:  H  H  \  I  c=c  I  \  H  $^{0 }$\~O,  C  H  H  \  I  c=c  I  \  H  0 