12  US 7,504,193 B2  11  Also, a group having an acid-decomposable group may be  introduced into X 1  by modification. X 1  having introduced  thereinto an acid-decomposable group is, for example, rep› resented by the following formula:  The resin (A) preferably contains a repeating unit repre› sented by formula (III) in addition to the repeating units  represented by formulae  (I)  and (II):  wherein R 1  ?a  and R 18 a each independently represents a  hydrogen atom or an alkyl group, and p represents an integer  ofl to 4.  The organic group ofX 1  is preferably an acid-decompos› able group having at least one cyclic structure selected from  an alicyclic structure, an aromatic cyclic structure and a  crosslinked alicyclic structure, and the structure is preferably  a structure containing an aromatic group (particularly a phe› nyl group) or a structure containing an alicyclic or crosslinked  alicyclic structure represented by any one of the following  formulae (pl) to (pVI):  wherein  R$_{3 }$to Rs each independently represents a hydrogen atom, a  fluorine atom, a chlorine atom, a cyano group or an alkyl  group, and  X 1  represents a hydrogen atom or an organic group.  The alkyl group of R$_{3 }$ to Rs is preferably an alkyl group  having from 1 to 5 carbon atoms and examples thereof  include a methyl group, an ethyl group and a propyl group.  The organic group of X 1  is preferably an organic group  having from 1 to 40 carbon atoms and may be an acid› decomposable group or a non-acid-decomposable group.  In the case of a non-acid-decomposable group, examples of  the organic group include the same organic groups for the  non-acid-decomposable group ofR$_{2 }$ (since this is an organic  group, a halogen atom is not included).  Also, examples thereofinclude an alkyl group, a cycloalkyl  group, an alkenyl group, an aryl group, an alkyloxy group  ( excluding -O-tertiary alkyl group), an acyl group, a  cycloalkyloxy group, an alkenyloxy group, an aryloxy group,  an alkylcarbonyloxy group, an alkylamidomethyloxy group,  an alkylamide group, an arylamidomethyl group and an ary› lamide group.  Of these non-acid-decomposable groups, preferred are an  acyl group, an alkylcarbonyloxy group, an alkyloxy group, a  cycloalkyloxy group, an aryloxy group, an alkylamideoxy  group and an alkylamide group, and more preferred are an  acyl group, an alkylcarbonyloxy group, an alkyloxy group, a  cycloalkyloxy group and an aryloxy group.  In the non-acid-decomposable group, the alkyl group is  preferably an alkyl group having from  1 to 4 carbon atoms,  such as methyl group, ethyl group, propyl group, n-butyl  group, sec-butyl group and tert-butyl group; the cycloalkyl  group is preferably a cycloalkyl group having from 3 to 10  carbon atoms, such as cyclopropyl group, cyclobutyl group,  cyclohexyl group and adamantyl group; the alkenyl group is  preferably an alkenyl group having from  2 to 4 carbon atoms,  such as vinyl group, propenyl group, ally! group and butenyl  group; the aryl group is preferably an aryl group having from  6 to 14 carbon atoms, such as phenyl group, xylyl group,  toluyl group, cumenyl group, naphthyl group and anthracenyl  group; and the alkyloxy group is preferably an alkyloxy group  having from  1 to 4 carbon atoms, such as methoxy group,  ethoxy group, hydroxyethoxy group, propoxy group, hydrox› ypropoxy group, n-butoxy group, isobutoxy group and sec› butoxy group.  In the case of an acid-decomposable group, examples of  the organic group of X include ----C(R 11 a)(R 12 J(R$_{13}$a),  -CCR14J(R1sa)(OR16J  and  -CO---OC(R11a)CR12J  (Rl3a).  R 1  la  to  R$_{13}$ a  each independently represents an alkyl group,  a cycloalkyl group, an alkenyl group, an aralkyl group or an  aryl group. R 14 a and Risa each independently represents a  hydrogen atom or an alkyl group. R 16 a represents an alkyl  group, a cycloalkyl group, an alkenyl group, an aralkyl group  R 1  $_{7 }$to R$_{21 }$each independently represents a hydrogen atom,  a linear or branched alkyl group having from 1 to 4 carbon  R 12  to R 16  each independently represents a linear or  branched alkyl group having from 1 to 4 carbon atoms or an  alicyclic hydrocarbon group, provided that at least one ofR 12  to R 14  or either one of R 1 s and R 16  represents an alicyclic  hydrocarbon group,  Z represents an atomic group necessary for forming an  alicyclic hydrocarbon group together with the carbon atom,  R 11  represents a methyl group, an ethyl group, an n-propyl  group, an isopropyl group, an n-butyl group, an isobutyl  group or a sec-butyl group,  wherein  or an aryl group. Two ofR 11 a,  R$_{12}$a  and  R$_{13}$a,  or two ofR 14 a,  Risa and R 16 a may combine to form a ring.  -[C(R17aJ(R1sa)]p-----CO---OC(R11a)(R12a)(R13a)  (pV)  R22 R23  0  I  I  II  -C-CH-C-R24  I  R2s  (pVI)  (p!V)  (pIII)  (pll)  (pl)  (III) 