Positive resist composition and patterning process using the same

A positive resist composition, wherein the positive resist composition contains at least, as a base resin, a polymer whose hydrogen atom of a phenolic hydroxide group is substituted by an acid labile group represented by the following general formula (1):

• (in the formula, R1 and R2 each represent independently any of a linear, a branched, and a cyclic alkyl group having 1 to 6 carbon atoms, and a hydrogen atom, R3 represents a group selected from a 1,2,3-indanyl group, a 1,2-acenaphthenyl group, a 1,2-aceanthrenyl group, and a 4,5-acephenanthrenyl group;
• here, the term 1,2- means 1-, 2-, or a mixture of them;
• similarly, the term 1,2,3- means 1-, 2-, 3-, or a mixture of them, and the term 4,5- means 4-, 5-, or a mixture of them).