Nonvolatile semiconductor storage device including a plurality of memory strings

A nonvolatile semiconductor storage device comprising:

• a plurality of memory strings in which a plurality of electrically rewritable memory cells are connected in series,
• the memory strings comprising:
• a columnar semiconductor layer extending in a direction perpendicular to a substrate;
• a first conductive layer sandwiching a charge storing layer with the columnar semiconductor layer;
• a second conductive layer positioned below the first conductive layer and sandwiching a first insulating layer with the columnar semiconductor layer;
• a third conductive layer positioned above the first conductive layer and sandwiching a second insulating layer with the columnar semiconductor layer;
• and
• a metal layer in contact with at least one of the first, second, and third conductive layers,
• the first conductive layer, the second conductive layer, and the third conductive layer being made of polysilicon.