US 2020/0133122 Al  104  Apr. 30, 2020  -continued  [0179]  Of the other PAGs, those compounds having an  anion of formula (3A’) or (3D) are especially preferred  because of reduced acid diffusion and high solubility in  resist solvent, and those compounds having an anion of  formula ( 4’) are especially preferred because of minimized  acid diffusion.  [0180]  When the resist composition contains the other  PAG (D), an appropriate amount of the PAG added is 0.1 to  40 parts, more preferably 0.5 to 20 parts by weight per 80  parts by weight of the base resin (B). As long as the amount  of component (D) is in the range, good resolution is achiev› able and the risk of foreign particles being formed after  development or during stripping of resist film is avoided.  The other PAG may be used alone or in admixture as  component (D).  CH3S03- CH3CH2S03- rfl  tt:J"so3- HO~s03- HO~S03- yO~S03- 0  (E) Quencher  [0181]  The resist composition may further include (E) a  quencher or acid diffusion controlling agent. As used herein,  the "quencher" refers to a compound capable of trapping the  acid generated by the PAG in the resist film to prevent the  acid from diffusing to the unexposed region thereof for  thereby forming the desired pattern.  [0182]  Typical of the quencher (E) are onium salts having  the formulae (5) and (6).  (5)  (6)  [0184]  Examples of the monovalent hydrocarbon group  Rq 1  include methyl, ethyl, propyl, isopropyl, n-butyl, sec› butyl, tert-butyl, n-pentyl, tert-pentyl, n-hexyl, n-octyl,  n-nonyl, n-decyl, cyclopentyl, cyclohexyl, 2-ethylhexyl,  cyclopentylmethyl,  cyclopentylethyl,  cyclopentylbutyl,  cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl, nor› bornyl, oxanorbomyl, tricyclo[5.2.l.0 2 • $^{6}$]decanyl, adaman› tyl, phenyl, naphthyl, and anthracenyl. In these groups, some  hydrogen may be substituted by a moiety containing a  heteroatom such as oxygen, sulfur, nitrogen or halogen, and  a moiety containing a heteroatom such as oxygen, sulfur or  nitrogen may intervene between carbon atoms, so that the  group may contain a hydroxyl moiety, cyano moiety, car› bonyl moiety, ether bond, ester bond, sulfonic acid ester  bond, carbonate bond, lactone ring, sultone ring, carboxylic  anhydride, or haloalkyl moiety. Examples of the monovalent  hydrocarbon group  Rq 2  include fluoroalkyl groups such as  trifluoromethyl and trifluoroethyl and fluoroaryl groups such  as pentafluorophenyl and 4-trifluoromethylphenyl as well as  the substituents exemplified above for  Rq 1 .  [0185]  Examples of the anion in the onium salt having  formula (5) are shown below, but not limited thereto.  [0183]  In formula (5), Rq 1  is hydrogen or a C$_{1 }$-C$_{40 }$mon› ovalent hydrocarbon group which may contain a heteroa› tom, exclusive of the group wherein hydrogen bonded to the  carbon atom at a-position relative to the sulfa group is  substituted by fluorine or fluoroalkyl. In formula (6),  Rq 2  is  hydrogen or a C$_{1 }$-C$_{40 }$monovalent hydrocarbon group which  may contain a heteroatom. The monovalent hydrocarbon  groups may be straight, branched or cyclic and examples  thereof are as exemplified above for R$^{112 }$in formula (3A’). 