Semiconductor memory device and method for manufacturing same

A method for manufacturing a semiconductor memory device, the method comprising:

• stacking a first insulating layer, a second insulating layer and a third insulating layer in order on a conductive layer;
• forming a fourth insulating layer on the third insulating layer, the fourth insulating layer including nitrogen and hydrogen bonds with a higher density than a density of nitrogen and hydrogen bonds in the second insulating layer;
• forming a fifth insulating layer on the fourth insulating layer;
• forming a first semiconductor layer extending through the first insulating layer and the second insulating layer in a first direction toward the third insulating layer from the conductive layer, the first semiconductor layer having an end portion positioned in the third insulating layer;
• forming a second semiconductor layer extending in the first direction through the fourth insulating layer and the fifth insulating layer, the second semiconductor layer being electrically connected to the first semiconductor layer;
• selectively removing the second insulating layer and the fourth insulating layer to form a first space and a second space, the second insulating layer being removed from the first space, the first insulating layer being exposed at the first space, and the fourth insulating layer being removed from the second space;
• forming a sixth insulating layer between the conductive layer and the first insulating layer by thermally oxidizing the conductive layer through the first insulating layer in the first space;
• and
• depositing metal layers respectively in the first space and the second space.

A semiconductor memory device comprising:

• a memory cell portion including:
• a plurality of electrode layers stacked in a first direction;
• and
• a columnar body extending through the electrode layers in the first direction and including a semiconductor layer extending in the first direction;
• and
• a peripheral portion provided around the memory cell portion, and including first and second insulating layers stacked in the first direction,
• the second insulating layer including nitrogen and hydrogen bonds with a higher density than a density of nitrogen and hydrogen bonds in the first insulating layer.