Semiconductor memory device and method of manufacturing semiconductor memory device

A semiconductor memory device comprising:

• a stack having a first insulating layer, a first conductive layer, a second insulating layer, and a second conductive layer, the first conductive layer being stacked on the first insulating layer in a first direction, the second insulating layer being stacked on the first conductive layer in the first direction, and the second conductive layer being stacked on the second insulating layer in the first direction;
• a semiconductor layer provided through the first and second insulating layers and the first and second conductive layers;
• a memory layer provided between the stack and the semiconductor layer in a second direction intersecting with the first direction;
• a first insulation extending from the first insulating layer toward the semiconductor layer in the second direction;
• and
• a second insulation extending from the second insulating layer toward the semiconductor layer in the second direction,
• wherein the first insulation and the memory layer define a first interface therebetween in a cross-section along the first direction, the cross-section including the stack, the semiconductor layer, the memory layer and the first and second insulations, the first interface having a first point and a second point, the first point overlapping with a middle portion in the first direction of the first insulating layer, the second point overlapping with an end portion in the first direction of the first insulating layer,
• wherein the second insulation and the memory layer define a second interface therebetween in the cross-section, the second interface having a fourth point and a fifth point, the fourth point overlapping with a middle portion in the first direction of the second insulating layer, the fifth point overlapping with an end portion in the first direction of the second insulating layer,
• wherein the second point is closer to the first insulating layer in the second direction than the first point is,
• wherein the fifth point is closer to the second insulating layer in the second direction than the fourth point is,
• wherein the first interface curves from the first point to the second point to protrude toward the semiconductor layer, and
• wherein the second interface curves from the fourth point to the fifth point to protrude toward the semiconductor layer.

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

• alternately stacking a first layer and a second layer in a first direction to form a stack;
• partly removing the stack along the first direction to form an opening through the stack in the first direction, a first surface provided on the first layer and facing on the opening, and a second surface provided on the second layer and facing on the opening;
• forming a protective film onto the first surface;
• forming an insulation extending in a second direction intersecting with the first direction from the second surface toward the opening;
• removing the protective film;
• forming a memory layer onto the first surface and the insulation;
• forming a semiconductor layer onto an opposite side of the memory layer from the first surface and onto an opposite side of the memory layer from the insulation in the second direction;
• and
• removing the first layer to form a space and forming a third layer in the space.