US Patent 8659070 Semiconductor memory device and manufacturing method thereof

The semiconductor memory device of the present invention includes a plurality of memory strings having a plurality of electrically reprogrammable memory cells connected in series, the memory strings having a column shaped semiconductor, a first insulation film formed around the column shaped semiconductor, a charge accumulation layer formed around the first insulation film, a second insulation film formed around the charge accumulation film and a plurality of electrodes formed around the second insulation film, a bit line connected to one end of the memory strings via a plurality of selection transistors, and a conducting layer extending in two dimensions and in which the plurality of electrodes of the memory strings and the plurality of electrodes of different memory strings are shared respectively, wherein each end part of the conducting layer is formed in step shapes in a direction parallel with the bit line.