Method for producing a pattern forming method and a semiconductor device

A semiconductor device manufacturing apparatus includes: a first pattern forming unit for forming a first pattern by patterning a first mask material layer; a boundary layer forming unit for forming a boundary layer at sidewall portions and top portions of the first pattern; a second mask material layer forming unit for forming a second mask material layer so as to cover a surface of the boundary layer; a second mask material removing unit for removing a part of the second mask material layer to expose top portions of the boundary layer; a boundary layer etching unit for forming a second pattern by etching and removing the boundary layer and forming a void between the sidewall portions of the first pattern and the second mask material layer; and a trimming unit for reducing a width of the first pattern and a width of the second pattern to predetermined widths.