NONVOLATILE SEMICONDUCTOR STORAGE DEVICE

• Main Authors: SAKUMA YU, KIYOTOSHI MASAHIRO, SAKUMA KIWAMU
• Format: Patent
• Language: English; Japanese
• Published: 23.07.2015
• Subjects: BASIC ELECTRIC ELEMENTS; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR; ELECTRICITY; SEMICONDUCTOR DEVICES

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. 【課題】３次元構造の不揮発性半導体記憶装置において、積層方向のメモリセルの特性を均一化する。【解決手段】積層構造は、半導体基板の表面と水平な第１方向に配列され半導体基板の表面と水平で且つ第１方向と交差する第２方向を長手方向とし、メモリセルのボディとして機能する複数の半導体層を層間絶縁層を挟んで第１方向及び第２方向と垂直な第３方向に積層してなる。メモリ膜は、積層構造の側面に形成されメモリセルの電荷蓄積膜を含む。導電膜は、メモリ膜を介して積層構造の側面に形成される。積層構造は、第１及び第３方向を含む断面において半導体基板側から離れた側から半導体基板に向かうに従ってその幅が大きくなる形状を有する。導電膜は、第２及び第３方向を含む断面において半導体基板側から離れた側から半導体基板に向かうに従ってその幅が大きくなる形状を有する。複数の半導体層中の所定の部分における不純物濃度は、上層と下層とで異なる。【選択図】図１Ａ