US 2019/0204738 Al  69  Jul. 4, 2019  [0672]  Based on the results listed in Table 4, it was  confirmed that the resist compositions of Examples 1 to 8 to  which the present invention had been applied had well› balanced sensitivity, resolution, and LWR, and the resolution  and LWR were improved.  [0673]  While preferred embodiments of the invention  have been described and illustrated above, it should be  understood that these are exemplary of the invention and are  not to be considered as limiting. Additions, omissions,  substitutions, and other modifications can be made without  departing from the spirit or scope of the present invention.  Accordingly, the invention is not to be considered as being  limited by the foregoing description, and is only limited by  the scope of the appended claims.  What is claimed is:  1.  A resist composition which generates an acid upon  exposure and whose solubility in a developing solution is  changed due to an action of the acid, the resist composition  comprising:  6.  The method of forming a resist pattern according to  claim  5,  wherein, in exposing the resist film, the resist film  is exposed to extreme ultraviolet rays (EUV) or electron  beams (EB).  *  *  *  *  *  developing the exposed resist film to form a resist pattern.  exposing the resist film; and  5.  A method of forming a resist pattern, comprising:  2.  The resist composition according to claim  1,  wherein a  ratio (molar ratio) of the constitutional unit (a0) to the  constitutional unit (al) (constitutional unit (a0)/constitu› tional unit (al)) is in a range of 8/2 to 1/9.  3.  The resist composition according to claim  1,  wherein a  total content of the constitutional unit (a0) and the consti› tutional unit (al) in the resin component (Al) is in a range  of 20% to 80% by mole with respect to all constitutional  units (100% by mole) constituting the resin component  (Al).  4.  The resist composition according to claim  1,  wherein  the resin component (Al) further has a constitutional unit  (al0-1) represented by Formula (al0-1),  forming a resist film on a support using the resist com- position according to claim  1;  wherein R represents a hydrogen atom, an alkyl group  having 1 to 5 carbon atoms, or a halogenated alkyl  group having 1 to 5 carbon atoms, Yax 1  represents a  single bond or a divalent linking group, Wax$^{1 }$represents  an  (naxl  +  1 )-valent aromatic hydrocarbon group, and  naxl  represents an integer of 1 or greater.  wherein the resin component (Al) has a constitutional  unit (a0) derived from a compound represented by  Formula (a0-1) and a constitutional unit (al) (where a  constitutional unit corresponding to the constitutional  unit (a0) is excluded) containing an acid decomposable  group whose polarity is increased due to the action of  the acid,  a resin component (Al) whose solubility in a developing  solution is changed due to the action of the acid,  wherein W represents a polymerizable group-containing  group, Ya 0  represents a carbon atom, Xa 0  represents a  group that forms a monocyclic aliphatic hydrocarbon  group together with Ya 0 ,  some or all hydrogen atoms in  the monocyclic aliphatic hydrocarbon group may be  substituted with substituents, and Ra 00  represents an  aromatic hydrocarbon group which may have a sub› stituent.  TABLE 4  Eop  Resolution  LWR  (mJ/cm 2 )  (nm)  (nm)  Example 1  126  39  5.5  Example 2  112  41  5.9  Example 3  127  41  5.8  Example 4  129  39  5.6  Example 5  136  41  6.0  Example 6  132  40  5.7  Example 7  133  40  5.6  Example 8  119  39  5.6  Comparative  108  43  6.3  Example 1  Comparative  129  45  6.5  Example 2  Comparative  131  43  6.3  Example 3  Comparative  130  44  6.3  Example 4  (al0-1)  (a0-1) 