Semiconductor memory device

A semiconductor memory device, comprising:

• a stack of insulating layers and conductive layers alternating with one another along a first direction orthogonal to layer planes of the insulating and conductive layers;
• and
• a plurality of core members spaced from each other in a second direction parallel to the layer planes of the insulating and conductive layers, each core member extending through the stack in the first direction, wherein
• a first semiconductor portion is on an outer periphery of each core member between the core member and each conductive layer in the stack in the second direction, the first semiconductor portion having a first thickness in the second direction from the core member and a first impurity concentration, and
• a second semiconductor portion is on the outer periphery of each core member between the core member and each insulating layer in the stack, the second semiconductor portion having a second thickness in the second direction from the core member that is greater than the first thickness and a second impurity concentration that is different from the first impurity concentration.

A method of manufacturing a semiconductor device, comprising:

• forming a stack of insulating layers and sacrificial layers alternating along a first direction;
• forming a hole extending through the stack in the first direction;
• exposing the hole to an etchant which preferentially removes material of the insulating layers and recessing the insulating layers from a sidewall of the hole;
• forming a charge accumulation layer on the sidewall of the hole;
• forming a first semiconductor film of a first conductivity type on the charge accumulation layer;
• removing a portion of the first semiconductor film and leaving portions of the first semiconductor film in recesses corresponding to the recessed insulating layers;
• forming a second semiconductor film on the charge accumulation layer and the remaining portions of the first semiconductor film;
• filing the hole with a core member material;
• removing the sacrificial films and leaving voids between adjacent insulating layers;
• and
• filling the voids with a conductive material.