US 2020/0209747 Al  110  Jul. 2, 2020  TABLE I-continued  Polymer  Acid generator  Quencher  Organic solvent  (pbw)  (pbw)  (pbw)  (pbw)  Comparative  1  Comparative  PAG-1  Q-1  PGMEA (2,000)  Example  Polymer 1  (25.0)  (3.00)  DAA (500)  (100)  2  Comparative  PAG-1  PGMEA (2,000)  Polymer 2  (25.0)  DAA (500)  (100)  3  Comparative  Q-1  PGMEA (2,000)  Polymer 3  (3.00)  DAA (500)  (100)  PEB temp. Sensitivity CDU  (" c.)  (mJ/cm 2 )  (nm)  95  30  5.6  95  38  4.7  95  35  3.9  [0220]  It  is demonstrated in Table  1  that positive resist  compositions comprising a base polymer comprising recur› ring units containing iodine and amino offer a high sensi› tivity and improved CDU.  [0221]  Japanese Patent Application No. 2018-244436 is  incorporated herein by reference.  [0222]  Although some preferred embodiments have been  described, many modifications and variations may be made  thereto in light of the above teachings.  It  is therefore to be  understood that the invention may be practiced otherwise  than as specifically described without departing from the  scope of the appended claims.  1.  A positive resist composition comprising a base poly› mer comprising recurring units containing an optionally  substituted amino group and iodine.  2.  The resist composition of claim  1  wherein the recurring  units containing an optionally substituted amino group and  iodine have the formula (a):  together to form a ring with the nitrogen atom to which they  are attached, the ring may contain an ether bond, m is an  integer of  1  to  4,  n is  1  or 2, p is an integer of O to 3, and  2sm+n+ps5.  3.  The resist composition of claim  1  wherein the base  polymer further comprises recurring units having a carboxyl  group substituted with an acid labile group and/or recurring  units having a phenolic hydroxyl group substituted with an  acid labile group.  4.  The resist composition of claim  3  wherein the recurring  units having a carboxyl group substituted with an acid labile  group and the recurring units having a phenolic hydroxyl  group substituted with an acid labile group are recurring  units having the formula (b  1)  and recurring units having the  formula (b2), respectively,  (a)  (bl)  (b2)  wherein  RA  is hydrogen or methyl, X 1  is a single bond,  phenylene, naphthylene, or a C$_{1 }$-C$_{12 }$linking group contain› ing an ester bond, ether bond or lactone ring, X 2  is a single  bond or a C$_{1 }$-C$_{12 }$ divalent hydrocarbon group which may  contain hydroxyl, ether bond or ester bond, R is hydroxyl,  carboxyl, C$_{1 }$-C$_{4 }$ straight or branched alkyl group, C$_{1 }$-C$_{4 }$ straight or branched alkoxy group, C$_{2}$-C$_{5 }$ straight or  branched alkoxycarbonyl group, C$_{2}$ -C$_{5 }$ straight or branched  acyl group, C$_{2}$ -C$_{5 }$ straight or branched acyloxy group, or  halogen exclusive of iodine, R 1  and R 2  are each indepen› dently hydrogen, C$_{1 }$-C$_{6 }$ alkyl group, C$_{2}$ -C$_{5 }$ alkenyl group,  C$_{2}$ -C$_{6 }$ alkynyl group, C$_{2}$-C$_{7 }$ acyl group, C$_{2}$-C$_{7 }$ alkoxycar› bonyl group, C$_{2}$-C$_{7 }$ alkenyloxycarbonyl group, C$_{2}$ -C$_{7 }$ alky› nyloxycarbonyl group, C$_{7}$-C$_{12 }$ aryloxycarbonyl group, or  C$_{1}$-C$_{12 }$ aralkyloxycarbonyl group, R 1  and R 2  may bond  wherein  RA  is each independently hydrogen or methyl, Y$^{1 }$is  a single bond, phenylene, naphthylene, or a C$_{1 }$-C$_{12 }$linking  group containing an ester bond, ether bond or lactone ring,  Y 2  is a single bond, ester bond or amide bond, R $^{11 }$and R  12  are each independently an acid labile group, R$^{13 }$is fluorine,  trifluoromethyl, cyano, or a C$_{1 }$-C$_{6 }$ alkyl group, R  14  is a  single bond or C$_{1 }$-C$_{6 }$ straight or branched alkanediyl group  in which some carbon may be replaced by an ether or ester  bond, a is  1  or 2, and b is an integer of O to  4.  5.  The resist composition of claim  1  wherein the base  polymer further comprises recurring units ( c) containing an  adhesive group selected from the group consisting of  hydroxyl, carboxyl, lactone ring, carbonate, thiocarbonate, 