10  US 7,049,044 B2  9  particular propyl methacrylate POSS, which could afford  POSS even higher etch resistance.  General details of the preparation of a methacrylate-based  CA resist incorporating a polyhedral oligosilsesquioxane  (POSS) component are presented in Example 1,  and  Example 2 describes the characterization of these methacry› late-based CA resists. Table 2 presents the relative weight  percents of components loaded into the mixture to be  polymerized, and the percent composition of that component  in the resulting polymer, for four representative resist  samples with various POSS content. Table 2 also presents  the glass transition temperatures (Tg), weight-average  An illustration or schematic of the microstructure of one  embodiment, a copolymer containing methyl methacrylate  (MMA), t-butyl methacrylate (TBMA), methacrylic acid  (MAA), and the polyhedral oligosilsesquioxane, 3-(3,5,7,9,  11,13,15-heptacyclopentylpentacyclo-[9.5.1.1 3 • $^{9}$.1 5 • $^{15 }$.1 7 • 13 ]  octasiloxane-1-yl)propyl methacrylate (propyl methacrylate  POSS), is presented in FIG.  1.  While not wanting to be  bound by this statement, it is believed that because this  MMA/TBMA/MAA/POSS copolymer incorporates an inor› ganic moiety, here the POSS™ moiety with a cluster or  cage-like structure, is more etch resistant than organic units  without such a moiety. In addition, the silica cage of the  POSS unit is surrounded by bulky cyclopentyl groups in this  Further Examples of Ene-Functionalized POSS Molecules Used for  Preparing the Nanocomposite Negative Resists of FIGS. 1 and 2.  R  Structure  Substitutent  Name  Cyclohexyl  Tris(dimethylvinyl)cyclo- hexyl-POSS  cyclopentyl  Tris(dimethylvinyl)cyclo- pentyl-POSS  i-butyl  Tris(dimethylvinyl)isobutyl- POSS  O  Cyclohexyl  R  II  Cyclopentyl  \  o  ~ ~  i-butyl  Acrylocyclohexyl-POSS  Acrylocyclopentyl-POSS  Acryloisobutyl-POSS  o-Si_....... ......___Si  0  R.....__  I Io  I\  Si~ --..._si-O  I  O  \’R 0  O R_\  O  I  \p-Si...._ O f~i’-.......  S .  s•-0 R  1--.........-1 .............  R/  O  R  Methacrylcyclohexyl-POS S  Methacrylcyclopentyl-POSS  Methacrylisobutyl-POSS  Methacrylisooctyl-POSS  Cyclohexyl  Norbomenylethylcyclohexyl- POSS  cyclopentyl  Norbomenylethylcyclo- pentyl-POSS  i-butyl  Norbomenylethylisobutyl- POSS  TABLE I-continued 