Semiconductor memory device and method of manufacturing the same

A semiconductor memory device, comprising:

• a semiconductor substrate;
• a stacked body having a plurality of first insulating layers and conductive layers stacked alternately on the semiconductor substrate;
• a columnar semiconductor layer being provided above the semiconductor substrate in the stacked body, being provided extending in a stacking direction of the stacked body and including a first portion and a second portion which is provided above the first portion;
• a memory layer provided on a side surface of the columnar semiconductor layer facing the stacked conductive layers and extending along the columnar semiconductor layer;
• and
• a second insulating layer provided between one of the first insulating layers of the stacked body and the conductive layer,
• the columnar semiconductor layer having a boundary of the first portion and the second portion, the boundary being close to the second insulating layer,
• an average value of an outer diameter of the memory layer facing a side surface of the second insulating layer being larger than that of the memory layer facing a side surface of a lowermost layer of the first insulating layers in the second portion, and
• a diameter of an inner sidewall of the second insulating layer facing a side surface of the memory layer increasing downwardly.