Jul. 4, 2019  3  US 2019/0204738 Al  [0037]  As the alkyl group as a substituent at the a-posi› tion, a linear or branched alkyl group is preferable, and  specific examples thereof include alkyl groups of 1 to 5  carbon atoms, such as a methyl group, an ethyl group, a  propyl group, an isopropyl group, an n-butyl group, an  isobutyl group, a tert-butyl group, a pentyl group, an iso› pentyl group, and a neopentyl group.  [0038]  Specific examples of the halogenated alkyl group  as the substituent at the a-position include groups in which  some or all hydrogen atoms of the above-described "alkyl  group as the substituent at the a-position" are substituted  with halogen atoms. Examples of the halogen atom include  a fluorine atom, a chlorine atom, a bromine atom and an  iodine atom, and a fluorine atom is particularly preferable.  [0039]  Specific examples of the hydroxyalkyl group as the  substituent at the a-position include groups in which some  or all hydrogen atoms of the above-described "alkyl group  as the substituent at the a-position" are substituted with a  hydroxyl group. The number of hydroxyl groups in the  hydroxyalkyl group is preferably 1 to 5, and most preferably  1.  [0040]  In the present specification and the scope of the  present patent claims, asymmetric carbons may be present or  enantiomers or diastereomers may be present depending on  the structures of the chemical formulae. In this case, these  isomers are represented by one formula. These isomers may  be used alone or in the form of a mixture.  [0041]  (Resist Composition)  [0042]  The resist composition according to the present  embodiment is 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.  [0043]  Such a resist composition contains a base material  component (A) in which the solubility in a developing  solution is changed due to an action of the acid (hereinafter,  also referred to as "component (A)").  [0044]  In a case where a resist film is formed using the  resist composition according to the present embodiment and  the formed resist film is subjected to a selective exposure,  acid is generated at exposed portions of the resist film, and  the generated acid acts on the component (A) to change the  solubility of the component (A) in a developing solution,  whereas the solubility of the component (A) in a developing  solution is not changed at unexposed portions of the resist  film, thereby generating difference in solubility in a devel› oping solution between exposed portions and unexposed  portions of the resist film. Therefore, by subjecting the resist  film to development, the exposed portions of the resist film  are dissolved and removed to form a positive type resist  pattern in a case of a positive type resist, whereas the  unexposed portions of the resist film are dissolved and  removed to form a negative type resist pattern in a case of  a negative type resist.  [0045]  In the present specification, a resist composition  which forms a positive type resist pattern by dissolving and  removing the exposed portions of the resist film is called a  positive type resist composition, and a resist composition  which forms a negative type resist pattern by dissolving and  removing the unexposed portions of the resist film is called  a negative type resist composition.  [0046]  The resist composition of the present embodiment  may be a positive type resist composition or a negative type  resist composition.  [0058]  In general, as a non-polymer, any of those which  have a molecular weight in the range of 500 to less than  [0057]  The organic compound used as the base material  component is broadly classified into non-polymers and  polymers.  [0056]  In the present invention, the term "base material  component" indicates an organic compound capable of  forming a film, and is preferably an organic compound  having a molecular weight of 500 or greater. In a case where  the organic compound has a molecular weight of 500 or  greater, the film-forming ability is improved, and a resist  pattern at a nano level can be easily formed.  [0055]  The component (A) is a base material component  whose solubility in a developing solution is changed due to  an action of an acid.  [0054]  <Component (A)>  [0053]  It is particularly preferable that the resist compo› sition of the present embodiment corresponds to the case of  (1) described above.  [0052]  As the constitutional unit which generates acid  upon exposure, a known constitutional unit can be used.  [0051]  That is, in a case where the resist composition of  the present invention is the above-described resist compo› sition (2) or (3), the component (A) is a "base material  component which generates acid upon exposure and whose  solubility in a developing solution is changed due to an  action of an acid". In a case where the component (A) is a  base material component which generates an acid upon  exposure and whose solubility in a developing solution is  changed due to an action of an acid, the component (Al)  described below is preferably a polymeric compound which  generates an acid upon exposure and whose solubility in a  developing solution is changed due to an action of an acid.  As the polymeric compound, a copolymer having a consti› tutional unit which generates acid upon exposure can be  used.  [0050]  In the present embodiment, the resist composition  may be a resist composition (1) containing an acid generator  component (B) which generates acid upon exposure (here› inafter, referred to as "component (B)"); a resist composition  (2) in which the component (A) is a component which  generates acid upon exposure; or a resist composition (3) in  which the component (A) is a component which generates  acid upon exposure, and further containing an acid generator  component (B).  [0049]  The resist composition of the present embodiment  has a function of generating acid upon exposure, and in the  resist composition, the component (A) may generate an acid  upon exposure, or an additive component other than the  component (A) may generate an acid upon exposure.  [0048]  In other words, the resist composition of the pres› ent embodiment is a "positive type resist composition for an  alkali developing process" that forms a positive type resist  pattern in an alkali developing process and is a "negative  type resist composition for a solvent developing process"  that forms a negative type resist pattern in a solvent devel› oping process.  [0047]  Further, in the formation of a resist pattern, the  resist composition of the present embodiment can be applied  to an alkali developing process using an alkali developing  solution in the developing treatment, or a solvent developing  process using a developing solution containing an organic  solvent (organic developing solution) in the developing  treatment. 