US Patent 7595145 Method of forming pattern of semiconductor device

A method of forming a pattern of a semiconductor device includes forming a hard mask layer over a semiconductor substrate and forming a photoresist film pattern over the hard mask layer. An outer portion of the photoresist film pattern is converted into an oxide layer having a first vertical wall, a second vertical wall, and a horizontal wall, wherein an inner portion of the photoresist film pattern is enclosed within the converted oxide layer. At least a portion of the horizontal wall is removed to expose the photoresist film pattern remaining within the converted oxide layer. The exposed photoresist film pattern is removed to form first and second oxide patterns corresponding to the first and second vertical walls, respectively, of the oxide layer. The hard mask layer is patterned using the first and second oxide patterns as etch masks. The semiconductor substrate is etched using the patterned hard mask layer.