Polymer compound for a chemical amplification resist and a fabrication process of a semiconductor device using such a chemical amplification resist

A resist composition, comprising:

• an acid-sensitive film-forming polymer insoluble to an alkaline solution;
• a carboxyl group bonding to a side chain of said polymer's main chain, said carboxyl group having a protective group;
• and an additional acidic functional group bonding to a side chain of said polymer main chain, said acidic functional group having an acid-cleavable protective group;
• said carboxyl group having, as said protective group, a lactone structure represented by a formula
• wherein n is an integer of 1-4, and R represents any of a hydrogen atom, an alkyl group, an alkoxyl group or an alkoxycarbonyl group and bonding to an arbitrary position of said lactone structure excluding a second position forming an ester bonding;
• and
• a photoacid generator causing a decomposition in response to an absorption of a radiation, said photoacid generator releasing an acid that causes a deprotection of said acid-cleavable protective group in response to said decomposition;
• said resist composition becoming soluble to said alkaline solution after said acid-cleavable protective group has caused said deprotection.

A method of forming a resist pattern, comprising the steps of:

• applying a resist composition on a substrate to form a resist film, said resist composition comprising:
• an acid-sensitive polymer compound insoluble to an alkaline solution, said acid-sensitive polymer compound comprising a film-forming polymer;
• a carboxyl group bonding to a side chain of said polymer main chain, said carboxyl group having a protective group;
• and an additional acidic functional group bonding to a side chain of said polymer main chain, said acidic functional group having an acid-cleavable protective group;
• said carboxyl group having, as said protective group, a lactone structure represented by a formula
• wherein n is an integer of 1-4, and R represents any of a hydrogen atom, an alkyl group, an alkoxyl group and an alkoxycarbonyl group and bonding to an arbitrary position of said lactone structure excluding a second position forming an ester bonding;
• and
• a photoacid generator causing a decomposition in response to an absorption of a radiation, said photoacid generator releasing an acid that causes a deprotection of said acid-cleavable protective group in response to said decomposition;
• said resist composition becoming soluble to said alkaline solution after said acid-cleavable protective group has caused said deprotection;
• exposing said resist film to an exposure radiation that induces said decomposition in said photoacid generator;
• and
• developing said resist film, after said process of exposing, by a basic solution.

A method of fabricating a semiconductor device, comprising the steps of:

• applying a resist composition on a substrate to form a resist film, said resist composition comprising:
• an acid-sensitive polymer compound insoluble to an alkaline solution, said acid-sensitive polymer compound comprising a film-forming polymer;
• a carboxyl group bonding to a side chain of said polymer main chain, said carboxyl group having a protective group;
• and an additional acidic functional group bonding to a side chain of said polymer main chain, said acidic functional group having an acid-cleavable protective group;
• said carboxyl group having, as said protective group, a lactone structure represented by formula
• wherein n is an integer of 1-4, and R represents any of a hydrogen atom, an alkyl group, an alkoxyl group or an alkoxycarbonyl group and connected to an arbitrary position of said lactone structure excluding a second position forming an ester bonding;
• and
• a photoacid generator causing a decomposition in response to an absorption of a radiation, said photoacid generator releasing an acid that causes a deprotection of said acid-cleavable protective group in response to said decomposition;
• said resist composition becoming soluble to said alkaline solution after said acid-cleavable protective group has caused said deprotection;
• exposing said resist film to an exposure radiation that induces said decomposition in said photoacid generator;
• developing said resist film, after said step of exposure, by a basic solution to form a resist pattern;
• and
• etching said substrate while using said resist pattern as a mask.