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[0017] [Patent Literature 1] Japanese Unexamined Patent Application, First Publication No. 2009-114381 

[0018] [Patent Document 2] Japanese Unexamined Patent Application, First Publication No. 2012-220800 

[0019] [Patent Document 3] Japanese Unexamined Patent Application, First Publication No. 2015-169843 

[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. 

[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). 

[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. 

[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. 

[0024] For solving the above-mentioned problems, the present invention employs the following aspects. 

[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. 

## DOCUMENTS OF RELATED ART 

## SUMMARY OF THE INVENTION 

## Patent Literature 

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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. 

[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. 

[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. 

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