132  US 9,703,193 B2  131  -continued  (6)  (7)  -continued  Of the foregoing second PAGs, those compounds having  an anion of formula (4A’) or (4D) are especially preferred  because of reduced acid diffusion and high solubility in  resist solvent, and those compounds having an anion of  formula (5’) are especially preferred because of minimized  acid diffusion.  An  appropriate amount of the PAG (D) added is  O  to 40  parts, more preferably 0.1 to 40 parts, and even more  preferably 0.1 to 20 parts by weight per 100 parts by weight  of the base resin (B).  An  amount in the range ensures good  resolution and leaves no foreign particles after resist devel› opment or during separation.  Component B  The resist composition may further comprise (E) a  quencher. As used herein, the "quencher" refers to a com› pound capable of suppressing the rate of diffusion when the  acid generated by the PAG diffuses within the resist film.  Suitable quenchers include primary, secondary and tertiary  amine compounds, specifically amine compounds having a  hydroxyl, ether, ester, lactone, cyano or sulfonate group, as  describedinJP-A2008-111103, paragraphs [0146] to [0164]  (U.S. Pat. No. 7,537,880), and compounds having primary  or secondary amine protected as a carbamate group, as  described in JP 3790649.  Also an onium salt of sulfonic acid which is not fluori- nated at a-position or carboxylic acid as represented by the  formula ( 6) or (7) is useful as the quencher.  Herein R 151 , R $^{152 }$and R$^{153 }$are each independently hydro› gen, halogen exclusive of fluorine, or a straight, branched or  cyclic C$_{1 }$-C$_{40 }$ monovalent hydrocarbon group which may  contain a heteroatom, any two or more of R 151 , R $^{152 }$and  R $^{153 }$may bond together to form a ring with the carbon atom  to which they are attached. R$^{154 }$is a straight, branched or  cyclic C$_{1 }$-C$_{40 }$ monovalent hydrocarbon group which may  contain a heteroatom. M+ is an onium cation.  The onium salt of sulfonic acid which is not fluorinated at  a-position is described in U.S. Pat. No. 8,795,942 (JP-A  2008-158339). The PAGs capable of generating sulfonio 