Sep. 10,2020  37  US 2020/0285152 Al  TABLE 9  PED  Resist  Eop  DOF LWR stability  composition  (mJ/cm 2 )  (nm)  (nm)  (%)  Comparative  2-14  CR-14  43.2  90  3.1  2.7  Example  2-15  CR-15  45.0  120  3.1  2.7  2-16  CR-16  49.2  60  3.2  2.6  2-17  CR-17  31.4  120  3.0  6.0  2-18  CR-18  31.8  120  3.6  2.6  2-19  CR-19  0  2-20  CR-20  22.5  210  2.8  4.0  2-21  CR-21  45.6  90  3.4  2.6  2-22  CR-22  0  2-23  CR-23  0  [0178]  As is evident from Tables 7 to 9, the positive resist  compositions within the scope of the invention show satis› factory results including a DOF value of 150 or higher, a  LWR value of2.6 to 3.1, and a size change by PED ofup to  2.7%. By contrast, the comparative positive resist compo› sitions are inferior in all of DOF, LWR and PED stability.  [0179]  Japanese Patent Application No. 2019-040330 is  incorporated herein by reference.  [0180]  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:  wherein R 1  and R 2  each are a hydroxyl group or a C$_{1}$-C$_{30 }$ monovalent hydrocarbon group which may contain a het› eroatom, R forms an aliphatic ring of 4 or 5 carbon atoms  with S+, m and n each are  O or 1, k is O or 1, and z- is an  organic anion,  wherein R 101 , R 102 , R 103 , R $^{104 }$and R$^{105 }$are each indepen› dently a C$_{1 }$-C$_{20 }$monovalent hydrocarbon group which may  contain a heteroatom, any two or more of R 101 , R $^{102 }$and  R $^{103 }$may bond together to form a ring with the sulfur atom  to which they are attached,  wherein R $^{12 }$and R $^{13 }$are each independently hydrogen or a  C$_{1 }$-C$_{20 }$monovalent hydrocarbon group which may contain a  heteroatom, R$^{12 }$and R$^{13 }$may bond together to form a ring  with the nitrogen atom to which they are attached, R $^{14 }$is a  C$_{1 }$-C$_{20 }$ divalent hydrocarbon group which may contain a  heteroatom, the broken line designates a valence bond, and  MA+  is a sulfonium cation having the formula (2A) or  iodonium cation having the formula (2B):  wherein A $^{1 }$is hydrogen or trifluoromethyl, R $^{11 }$is a nitrogen› containing heterocyclic group or a group having the formula  (2-1 ):  (A) 4.1 to 20 parts by weight of a first onium salt having  the formula (1 ),  (B) 2.3 to 8.8 parts by weight of a second onium salt  having the formula (2),  (C) 80 parts by weight of a base polymer adapted to  increase alkaline solubility under the action of acid, the  base polymer comprising acid labile group-containing  recurring units having the formula (a) and optionally  acid labile group-containing recurring units having the  formula (b ), with the proviso that when the acid labile  group-containing recurring units having formula (b) are  included, those recurring units containing an acid labile  group of at least 14 carbon atoms may be included in  an amount of up to 5 mo! % of the overall recurring  units, and  (D) 200 to 5,000 parts by weight of an organic solvent,  (2)  l  f  ,so- MA+  R11  o’ A  3  F  F  (2-1)  Rl2  \  14  N-R ---- /  Rl3  (2A)  (2B)  (a)  (b)  (1) 