The present invention discloses a chemically amplified (CA) resist composition for printing features having a dimension of about 30 nm or less and a method of forming a material structure having a pattern containing features having a dimension of about 30 nm or less by using the inventive CA resist. The CA resist composition comprises (a) about 1 to about 50 weight % of a copolymer, (b) about 0.02 to about 25 weight % of a photoacid generator, (c) about 47 to about 99 weight % of a solvent, and (d) about 0.004 to about 25 weight % of a base additive. The copolymer comprises at least one hydrophilic monomer unit containing one or more polar functional groups and at least one hydrophobic monomer unit containing one or more aromatic groups. Some, but not all, of the one or more polar functional groups in the copolymer are protected with acid labile moieties having a low activation energy.