Jul.  18,  2019  2  US 2019/0219920 Al  DOCUMENTS OF RELATED ART  Patent Literature  SUMMARY OF THE INVENTION  [Chemical Formula 2]  [Chemical Formula 1]  [0025]  Specifically, a first aspect of the present invention  is a resist composition which generates acid upon exposure  and exhibits changed solubility in a developing solution  under action of acid, and which includes a resin component  (Al) which exhibits changed solubility in a developing  solution under action of acid, the resin component (Al)  including a polymeric compound (Al) having a structural  unit (a0) represented by general formula (a0-1) shown  below.  [0024]  For solving the above-mentioned problems, the  present invention employs the following aspects.  [0023]  The present invention takes the above cJrcum› stances into consideration, with an object of providing a  novel resin component useful as a base component of a resist  composition, a resist composition containing the resin com› ponent, and a method of forming a resist pattern using the  resist composition.  [0022]  However, in a conventional resist compos1t10n,  when it is attempted to improve sensitivity to an exposure  source such as EUV, it becomes difficult to obtain a resist  pattern having a desired shape. Therefore, it was difficult to  satisfy both the sensitivity and the pattern shape.  [0021]  As the lithography technique further progresses  and the miniaturization of the resist pattern progresses more  and more, for example, a target of the lithography performed  by extreme ultraviolet (EUV) or electron beam (EB) is to  form fine resist patterns of several tens of nanometers. As  miniaturization of resist pattern progress, resist composition  is demanded to exhibit improved sensitivity to the exposure  source and good lithography properties (resolution, reduced  roughness, and the like).  [0027]  A third aspect of the present invention is a poly› meric compound having a structural unit (a0) represented by  general formula ( a0-1) shown below.  [0026]  A second aspect of the present invention is a  method of forming a resist pattern, including: using a resist  composition according to the first aspect to form a resist  film, exposing the resist film, and developing the exposed  resist film to form a resist pattern.  In the formula, R represents a hydrogen atom, an alkyl group  of 1 to 5 carbon atoms or a halogenated alkyl group of 1 to  5 carbon atoms; Va$^{0 }$represents a divalent hydrocarbon group  which may have an ether bond; nao represents an integer of  0 to 2; Ra$^{00 }$represents an acid dissociable group represented  by general formula (a0-rl-1 ); Ra$^{01 }$represents a hydrocarbon  group which may have a substituent; Ra 02  represents a  hydrocarbon group which may have a substituent; Ra$^{01 }$and  Ra$^{02 }$may be mutually bonded to form a ring; Ya$^{0 }$represents  a quaternary carbon atom; Ra 031 , Ra 032  and Ra 033  each  independently represents a hydrocarbon group which may  have a substituent; provided that at least one ofRa 031 , Ra 032  and Ra$^{033 }$is a hydrocarbon group having a polar group; *  represents a valence bond.  [0020]  Due to further improvement in the performance  and downsize of electronic devices, in the pattern formation  in the production of semiconductor devices,  further  improvement in the lithography properties and the resist  pattern shape are demanded. However, there was still room  for improvement in the shape of a resist pattern formed using  a conventional resist composition. Moreover, there was  further demands for improvement in sensitivity and lithog› raphy properties.  [0019]  [Patent Document 3] Japanese Unexamined Patent  Application, First Publication No. 2015-169843  [0018]  [Patent Document 2] Japanese Unexamined Patent  Application, First Publication No. 2012-220800  [0017]  [Patent Literature 1] Japanese Unexamined Patent  Application, First Publication No. 2009-114381  (a0-1)  (a0-rl-1)  (a0-1) 