PURPOSE: To improve the selection ratio with a lower flattened layer while having practicable sensitivity by using a positive type resist material consisting of a copolymer of a styrene deriv. subjected to nucleus substitution by a substituent contg. an Si atom and SO2.
CONSTITUTION: This material is constituted of the positive type resist material consisting of the copolymer of the styrene deriv. subjected to the nucleus substitution by the substituent contg. at least one Si atom and the SO2 and, for example, the copolymer is expressed by the formula I. In the formula I, X denotes H or alkyl group; l is ≥1; Z denotes {Si(CH3)3}l, etc. The styrene deriv. subjected to the nucleus substitution by the substituent contg, the Si atom is used in this way. The selection ratio with the lower flattened layer in O2B-RIE (reactive ion etching using oxygen) is improved in this way. The decomposition efficiency when the resist is irradiated with radiations is, therefore, enhanced by introducing the C-S bond of small total energy into the main chain. The positive type resist having the practicable sensitivity is thus obtd.
NAKAMURA HIROKO
KODACHI AKIKO
