Patent ID: 8309469

Claim:
A method of fabricating a semiconductor device, comprising steps of: a first step of forming a plurality of core material patterns which are separated from each other above a substrate and comprise a first film; a second step of modifying surfaces of the core material patterns to form a second film which is selectively etchable with the first film internally remaining and which includes portions separated from each other above the substrate, the second film not covering a base layer of the core material patterns between the core material patterns; a subsequent step of forming a third film to cover upper surfaces and side surfaces of the portions of the second film and an upper surface of the substrate; a third step of etching back the third film to expose the upper surfaces of the portions of the second film and to expose the base layer of the core material patterns between the core material patterns, and causing the third film to selectively remain, the third film being formed on sidewalls of the core material patterns with the second film being interposed there between; a fourth step of selectively removing the second film with the first and third films remaining; and a fifth step of patterning the base layer with the first and third films both on the base layer serving as a mask after the second film has been removed, thereby forming a base layer pattern.