Semiconductor memory device and method for manufacturing the same

A semiconductor memory device comprising:

• a stacked body including a plurality of conductive layers and a plurality of insulating layers, each of the conductive layers and the insulating layers being alternately disposed;
• a semiconductor pillar extending in a first direction inside the stacked body;
• a first insulating film provided in a space between the semiconductor pillar and the conductive layer;
• a first portion of a first electrode provided in a space between the first insulating film and the conductive layer so as to be in contact with a second direction side surface being opposite to the first direction of the insulating film and an outer surface of the first insulating film;
• a second portion of the first electrode provided in a space between the first insulating film and the conductive layer so as to be in contact with the first direction side surface of the insulating film and the first insulating film;
• and
• a third portion of the first electrode provided to be in contact with the first insulating film, the first portion of the first electrode and the second portion of the first electrode;
• and
• a second insulating film provided in a space between the first electrode and the conductive layer,
• an outer diameter of the first portion of the first electrode being larger than an outer diameter of the third portion of the first electrode,
• an outer diameter of the second portion of the first electrode being larger than an outer diameter of the third portion of the first electrode.

A method for manufacturing a semiconductor memory device comprising:

• forming of a first material layer performed by causing a first material to be accumulated;
• forming of a second material layer performed by causing a second material to be accumulated on the first material layer;
• forming of a third material layer performed by causing a third material to be accumulated on the second material layer;
• forming of a memory hole performed by penetrating a stacked body composed of the first material layer, the second material layer, and the third material layer in a stacking direction;
• removing of a portion of the second material layer on the memory hole side through the memory hole;
• causing a first conductive material to be accumulated in the memory hole;
• forming of a first portion of a first electrode made of the first conductive material in a space after the second material layer is removed, by performing etch-back on the first conductive material;
• removing a portion of each of the first material layer and the third material layer on the memory hole side through the memory hole;
• causing of a second conductive material to be accumulated in the memory hole;
• forming of a second portion of the first electrode made of the second conductive material in a first direction side space after the first material layer and the third material layer are removed, forming of a third portion of the first electrode made of the second conductive material in a second direction side being opposite to the first direction side space after the first material layer and the third material layer are removed, by performing etch-back on the second material layer;
• forming of a first insulating film on side surfaces of the first electrode;
• forming of a slit penetrating the stacked body in the stacking direction on sides of the memory hole;
• removing of the first material layer, the second material layer, and the third material layer through the slit;
• forming of a second insulating film on side surfaces of the first electrode through the slit;
• and
• forming of a second electrode on a front surface of the second insulating film through the slit.