A method of forming patterns of a semiconductor device comprises forming a number of first insulating patterns that define sidewalls by patterning a first insulating layer formed over a semiconductor substrate, forming second insulating patterns, each second insulating pattern comprising a horizontal portion having two ends and being parallel to the semiconductor substrate and spaced protruding portions protruding from both ends of the horizontal portion parallel to the sidewalls of the first insulating patterns, forming third insulating patterns each filling a space between the protruding portions, removing the protruding portions to form trenches, and forming conductive patterns within the respective trenches.