Memory device

A memory device, comprising:

• a substrate;
• a structure including a plurality of conductive layers stacked on the substrate;
• and
• a pillar arranged inside the structure, the pillar including:
• a core layer;
• a semiconductor layer extending in a direction perpendicular to a surface of the substrate and including a first portion on a side of an upper portion of the structure, and a second portion in contact with an outer surface of the core layer between the first portion of the semiconductor layer and the substrate;
• and
• a reformed layer having a lower end in contact with the first portion of the semiconductor layer.