NONVOLATILE SEMICONDUCTOR STORAGE DEVICE

摘要

PROBLEM TO BE SOLVED: To uniformize characteristics of memory cells in a lamination direction in a three-dimensional structure nonvolatile semiconductor storage device.SOLUTION: A nonvolatile semiconductor storage device comprises: lamination structure which are arranged in a first direction parallel with a surface of a semiconductor substrate and has a longer direction in a second direction which is parallel with the surface of the semiconductor substrate and crosses the first direction, and in which a plurality of semiconductor layers functioning as bodies of memory cells are laminated in a third direction perpendicular to the first direction and the second direction by sandwiching each of a plurality of interlayer insulation layers; a memory film which is formed on lateral faces of the lamination structures and includes a charge storage film of each memory cell; and a conductive film formed on the lateral faces of the lamination structures via the memory film. Each lamination structure has a cross section including the first and third directions and having a shape with a width which increases with the increasing distance from the side away from the semiconductor substrate toward the semiconductor substrate. The conductive film has a cross section including the second and third directions and having a shape with a width which increased from the side away from the semiconductor substrate toward the semiconductor substrate. At a predetermined part in the plurality of semiconductor layers, an impurity concentration is different in an upper layer from that in a lower layer.