Nonvolatile memory device and method for manufacturing nonvolatile memory device

A method for manufacturing a nonvolatile memory device,

• the device including memory cells stacked in a plurality of layers,
• each of the memory cells including:
• a first interconnection extending in a first direction;
• a second interconnection extending in a second direction nonparallel to the first direction;
• and
• a memory layer placed between the first interconnection and the second interconnection and reversibly transitioning between a first state and a second state by a current supplied via the first interconnection and the second interconnection,
• the method comprising:
• stacking a layer being to form the first interconnection, a layer being to form the memory layer, and a layer being to form the second interconnection in a third direction substantially perpendicular to the first direction and the second direction to form a stacked body;
• providing an etching mask having an opening on the stacked body;
• and
• forming an element isolation region by etching the stacked body via the etching mask, and
• an opening dimension of the etching mask being decreased with an increasing dimension in the third direction of the element isolation region in the providing the etching mask.

A method for manufacturing a nonvolatile memory device,

• the device including memory cells stacked in a plurality of layers,
• each of the memory cells including:
• a first interconnection extending in a first direction;
• a second interconnection extending in a second direction nonparallel to the first direction;
• and
• a memory layer placed between the first interconnection and the second interconnection and reversibly transitioning between a first state and a second state by a current supplied through the first interconnection and the second interconnection,
• the method comprising:
• stacking a layer being to form the first interconnection, a layer being to form the memory layer, and a layer being to form the second interconnection in a third direction substantially perpendicular to the first direction and the second direction to form a stacked body;
• providing an etching mask having an opening on the stacked body;
• performing etching of a smaller dimension than a dimension in the third direction of an element isolation region in the third direction using the etching mask;
• forming a protection layer at least on a side wall face of the etched stacked body;
• further etching to a dimension in the third direction of the element isolation region;
• and
• controlling a size of a cross section parallel to the first and the second direction of the element isolation region by etching a portion of the side wall face on which the protection layer is not formed.