44  US 7,851,130 B2  43  -continued  In formulae (pl) to (pV), R$_{11 }$represents a methyl group, an  ethyl group, ann-propyl group, anisopropyl group, ann-butyl  group, an isobutyl group, or a sec-butyl group; and Z repre› sents an atomic group necessary to form a cycloalkyl group  together with a carbon atom.  R$_{12}$ , R 13 , R 14 , R $_{15 }$and R$_{16 }$each represents a straight chain  or branched alky 1 group or cycloalky 1 group having from 1 to  4 carbon atoms, provided that at least one of R$_{12 }$to R$_{14}$, or  either R$_{15 }$or R$_{16 }$represents a cycloalkyl group.  R$_{17}$ , R 18 , R 19 , R $_{20 }$and R$_{21 }$ each represents a hydrogen  atom, a straight chain or branched alkyl group or cycloalkyl  group having from 1 to 4 carbon atoms, provided that at least  one ofR$_{17 }$to  R$_{21 }$ represents a cycloalkyl group, and either R$_{19 }$ or  R$_{21 }$ represents a straight chain or branched alkyl group or  cycloalkyl group having from 1 to 4 carbon atoms.  R$_{22}$, R 23 , R $_{24 }$and R$_{25 }$each represents a hydrogen atom, a  straight chain or branched alkyl group or cycloalkyl group  having from 1 to 4 carbon atoms, provided that at least one of  R$_{22 }$to R$_{25 }$represents a cycloalkyl group, and R$_{23 }$and R$_{24 }$may  by bonded to each other to form a ring.  In formula (II-AB), R$_{11}$’ and R 12 ’ each represents a hydro› gen atom, a cyano group, a halogen atom, or an alkyl group.  Z’ contains bonded two carbon atoms (C----C) and repre- sents an atomic group to form an alicyclic structure.  Formula (II-AB) is more preferably represented by the  following formula (II-AB!) or (II-AB2).  As the resin having a monocyclic or polycyclic alicyclic  hydrocarbon structure and capable of decomposing by the  action of an acid to thereby increase the solubility in an alkali  developing solution (hereinafter also referred to as "alicyclic  hydrocarbon acid-decomposable resin"), resin containing at  least one repeating unit selected from the group consisting of  a repeating unit having a partial structure containing alicyclic  hydrocarbon represented by any of the following formulae  (pl) to (p V), and a repeating unit represented by the following  formula (II-AB) is preferred.  When the positive photosensitive composition in the inven› tion is irradiated withArF excimer laser beams, it is preferred  that resin (C) is resin having a monocyclic or polycyclic  alicyclic hydrocarbon structure and capable of decomposing  by the action of an acid to thereby increase the solubility in an  alkali developing solution.  The content of an acid-decomposable group is expressed  by B/(B+S), taking the number of the acid-decomposable  groups in the resin as (B), and the number of alkali-soluble  groups not protected with acid-eliminable groups as (S). The  content is preferably from 0.01 to 0.7, more preferably from  0.05 to 0.50, and still more preferably from 0.05 to 0.40.  In the above specific examples, tBu means at-butyl group.  (pll)  (pIII)  (p!V)  (pV)  R22  R23  0  -I  ~I  _II  R24  R2s  (R-17)  OH  OH  oyo........._ $_{tBu }$ 0  (R-15)  OH  (R-16)  (pl)  R11  $_{C}$l --- -’  ’  ’  .  \, .. _~i  -continued  (II-AB) 