Jul.  30,  2020  38  US 2020/0241417 Al  the pattern or the pattern profile is degraded. The influences  of Mw and Mw/Mn become stronger as the pattern rule  becomes finer. Therefore, the base polymer should prefer› ably have a narrow dispersity (Mw/Mn) of 1.0 to 2.0,  especially 1.0 to 1.5, in order to provide a resist composition  suitable for micropatterning to a small feature size.  [0093]  It is understood that a blend of two or more  polymers which differ in compositional ratio, Mw or  Mw/Mn is acceptable.  [0094]  Acid Generator  [0095]  The resist composition may comprise an acid gen› erator capable of generating a strong acid (referred to as acid  generator of addition type, hereinafter). As used herein, the  term "strong acid" refers to a compound having a sufficient  acidity to induce deprotection reaction of an acid labile  group on the base polymer in the case of a chemically  amplified positive resist composition, or a compound having  a sufficient acidity to induce acid-catalyzed polarity switch  reaction or crosslinking reaction in the case of a chemically  amplified negative resist composition. The inclusion of such  an acid generator ensures that the amine compound func› tions as a quencher and the inventive resist composition  functions as a chemically amplified positive or negative  resist composition.  [0096]  The acid generator is typically a compound (PAG)  capable of generating an acid upon exposure to actinic ray  or radiation. Although the PAG used herein may be any  compound capable of generating an acid upon exposure to  high-energy radiation, those compounds capable of gener› ating sulfonic acid, imide acid (imidic acid) or methide acid  are preferred. Suitable PAGs include sulfouitan salts, iodo› nium salts, sulfonyldiazomethane, N-sulfonyloxyimide, and  oxime-O-sulfonate acid generators. Exemplary PAGs are  described in JP-A 2008-111103, paragraphs [0122]-[0142]  (U.S. Pat. No. 7,537,880).  [0097]  As the PAG used herein, sulfonium salts having the  formula (1-1) and iodonium salts having the formula (1-2)  are also preferred.  (1-1)  (1-2)  R104  I  1+  x- i  RIOS  [0098]  In formulae (1-1) and (1-2), R 101 , R 102 , R 103 , R 104  and R 105  are each independently a C$_{1}$-C$_{20 }$ monovalent  hydrocarbon group which may contain a heteroatom. Any  two ofR 101 , R $^{102 }$and R$^{103 }$may bond together to form a ring  with the sulfur atom to which they are attached. The  monovalent hydrocarbon group may be straight, branched or  cyclic, and examples thereof include those exemplified  above for R$^{21 }$to R$^{28 }$in formulae (fl) to (f3).  [0099]  Example of the cation in the sulfonium salt having  formula (1-1) are shown below, but not limited thereto. 