The linear or branched aliphatic hydrocarbon group pref› erably has 1 to 10 carbon atoms, more preferably 1 to 8 carbon 50  atoms, still more preferably 1 to 5 carbon atoms, and most  preferably 1 to 3 carbon atoms.  The linear aliphatic hydrocarbon group is preferably a  linear alkylene group, and specifically, examples thereof  include a methylene group [-CH$_{2}$ -],  an ethylene group 55  [-(CH$_{2}$ ) 2 -], r a trimethylene group [-(CH 2 ) 3 -], a tet› ramethylene group [-(CH$_{2}$ ) 4 -], and a pentamethylene  group [-(CH$_{2}$ ) 5 -].  The branched aliphatic hydrocarbon group is preferably a  branched alkylene group, and specifically, examples thereof  include alkylalkylene groups, including alkylmethylene  groups  such  as  ----CH(CH$_{3}$ )-,  ----CH(CH$_{2}$CH$_{3}$)-,  -C(CH$_{3}$ ) 2 -,  ----C(CH$_{3}$)(CH$_{2}$CH$_{3}$)-,  -C(CH$_{3}$ )  (CH$_{2}$CH$_{2}$CH$_{3}$)-, and ----C(CH$_{2}$CH$_{3}$ ) 2 -; alkylethylene  groups such as -CH(CH$_{3}$)CH$_{2}$-,  -CH(CH$_{3}$)CH(CH$_{3}$)-,  -C(CH$_{3}$ ) $_{2}$CH$_{2}$ -,  ----CH(CH$_{2}$CH$_{3}$)CH$_{2}$-,  and  -C(CH$_{2}$CH$_{3}$ ) $_{2}$----CH$_{2}$ -; alkyltrimethylene groups such as  Examples of the aliphatic hydrocarbon group include a  linear or branched aliphatic hydrocarbon group, and an ali› phatic hydrocarbon group containing a ring in a structure  thereof.  The aliphatic hydrocarbon group means a hydrocarbon  group having no aromaticity. The aliphatic hydrocarbon  group may be either saturated or unsaturated, and in general,  it is preferably saturated.  When Y 1  represents an optionally substituted divalent  hydrocarbon group, the hydrocarbon group may be an ali› phatic hydrocarbon group or an aromatic hydrocarbon group.  Aliphatic Hydrocarbon Group in Y 1  Preferred examples of the divalent linking group in Y 1  include an optionally substituted divalent hydrocarbon group  and a hetero atom-containing divalent linking group.  Optionally Substituted Divalent Hydrocarbon Group:  In the formula (a0-r-1), Y 1  represents a divalent linking  group.  In the formula, Y$^{1 }$represents a divalent linking group; each  ofR$^{2 }$and R$^{3 }$independently represents a group having Oto 20  carbon atoms, which is not a fluorine atom, and either R $^{2 }$or R 3  may form a ring with Y 1 ;  m represents an integer of 1 or more;  and  Mm+  represents an m-valent organic cation.  [Chemical formula 2]  (a0-r-1)  In the resist composition, the anion moiety of the partial  structure represented by the general formula (a0-r-1)  becomes an appropriate weakly acidic anion upon exposure  to exhibit a quenching (acid diffusion control) effect to thus  trap the acid generated upon exposure. In the formation of a  resist pattern, in exposed areas of a resist film, the partial  structure is decomposed upon exposure to lose acid diffusion  controlling properties (basicity), and thus the quenching  effect is not exhibited. In unexposed areas of the resist film,  the partial structure exhibits the quenching effect.  blended with the resist composition, or may be included in a  component other than the component (A).  US 9,052,592 B2  8  7  ----CH(CH$_{3}$)CH$_{2}$CH$_{2}$- and ----CH$_{2}$CH(CH$_{3}$)CH$_{2}$-; and  alkyltetramethylene  groups  such  as  -CH(CH$_{3}$ )  CH$_{2}$CH$_{2}$CH$_{2}$ - and -CH$_{2}$CH(CH$_{3}$)CH$_{2}$CH$_{2}$-. As the  alkyl group in the alkylalkylene group, a linear alkyl group  having 1 to 5 carbon atoms is preferable.  The linear or branched aliphatic hydrocarbon group may or  may not have a substituent. Examples of the substituent  include a fluorine atom, a fluorinated alkyl group having 1 to  5 carbon atoms, which is substituted with a fluorine atom, an  alkoxy group having 1 to 10 carbon atoms, an alkoxyalkyl  group having 2 to 15 carbon atoms, and a carbonyl group.  Examples of the aliphatic hydrocarbon group containing a  ring in a structure thereof include an optionally substituted  cyclic aliphatic hydrocarbon group containing a hetero atom  in a ring structure thereof (a group in which two hydrogen  atoms are eliminated from an aliphatic hydrocarbon ring), a  group in which the cyclic aliphatic hydrocarbon group is  bonded to the terminal of a linear or branched aliphatic hydro› carbon group, and a group in which the cyclic aliphatic hydro› carbon group intervenes on the way of a linear or branched  aliphatic hydrocarbon group. Examples of the linear or  branched aliphatic hydrocarbon group include the same  groups as those described above.  The cyclic aliphatic hydrocarbon group has preferably 3 to  20 carbon atoms, and more preferably 3 to 12 carbon atoms.  The cyclic aliphatic hydrocarbon group may be either a  polycyclic group or a monocyclic group. The monocyclic  alicyclic hydrocarbon group is preferably a group in which  two hydrogen atoms are eliminated from a monocycloalkane.  The monocycloalkane is preferably one having 3 to 6 carbon  atoms. Specifically, examples thereof include cyclopentane  and cyclohexane. The polycyclic alicyclic hydrocarbon group  is preferably a group in which two hydrogen atoms are elimi› nated from a polycycloalkane. The polycycloalkane prefer› ably has 7 to 12 carbon atoms. Specifically, examples thereof  include adamantane, norbornane, isobomane, tricyclode› cane, tetracyclododecane, and tricyclotetradecane.  The cyclic aliphatic hydrocarbon group may or may not  have a substituent. Examples of the substituent include an  alkyl group, an alkoxy group, a halogen atom, a halogenated  alkyl group, a hydroxyl group, and a carbonyl group.  The alkyl group as the substituent is preferably an alkyl  group having 1 to 5 carbon atoms, and most preferably a  methyl group, an ethyl group, a propyl group, an n-butyl  group, or a tert-butyl group.  The alkoxy group as the substituent is preferably an alkoxy  group having 1 to 5 carbon atoms, more preferably a methoxy  group, an ethoxy group, an n-propoxy group, an isopropoxy  group, an n-butoxy group, or a tert-butoxy group, and most  preferably a methoxy group or an ethoxy group.  Examples of the halogen atom as the substituent include a  fluorine atom, a chlorine atom, a bromine atom, and an iodine  atom, with a fluorine atom being preferable.  Examples of the halogenated alkyl group as the substituent  include a group in which some or all the hydrogen atoms of  the above-described alkyl group are substituted with the  above-described halogen atom.  In the cyclic aliphatic hydrocarbon group, some of the  carbon atoms constituting the ring structure thereof may be  substituted with a substituent containing a hetero atom. The  substituent containing a hetero atom is preferably ---0-,  ----C(=O)---0-, -S-, -S(=O)$_{2}$-, or -S(=O) 2 - 0-.  Linear or Branched Aliphatic Hydrocarbon Group  Aliphatic Hydrocarbon Group Containing Ring in Structure  Thereof 