Methods of forming fine patterns of semiconductor device

Abstract

A method of forming fine patterns of a semiconductor device is provided. The method includes forming plural preliminary first mask patterns, which are spaced apart from each other by a first distance in a direction parallel to a surface of a substrate, on the substrate; forming an acid solution layer on the substrate to cover the plural preliminary first mask patterns; forming plural first mask patterns which are spaced apart from each other by a second distance larger than the first distance, of which upper and side portions are surrounded by acid diffusion regions having first solubility; exposing the first acid diffusion regions by removing the acid solution layer; forming a second mask layer having second solubility lower than the first solubility in spaces between the acid diffusion regions; and forming plural second mask patterns located between the plural first mask patterns, respectively, by removing the acid diffusion regions by the dissolvent.