Semiconductor memory device and method of manufacturing the same

A semiconductor memory device comprising:

• a plurality of first conductive layers arranged in a stacking direction;
• a bit line disposed on one side in the stacking direction with respect to the plurality of first conductive layers and extending in a first direction intersecting with the stacking direction;
• a plurality of second conductive layers disposed at a position between the plurality of first conductive layers and the bit line, the position overlapping with the plurality of first conductive layers viewing from the stacking direction, the plurality of second conductive layers being arranged in the first direction;
• a semiconductor layer extending in the stacking direction and opposed to the plurality of first conductive layers and one of the plurality of second conductive layers, the semiconductor layer being electrically connected to the bit line;
• an electric charge accumulating film disposed between the plurality of first conductive layers and the semiconductor layer;
• and
• a plurality of first insulating layers disposed between the semiconductor layer and the bit line in the stacking direction and arranged in the first direction corresponding to the plurality of second conductive layers, the plurality of first insulating layers containing nitrogen (N) and silicon (Si).

A method of manufacturing a semiconductor memory device, comprising:

• forming a plurality of sacrifice layers containing nitrogen (N) and silicon (Si) and arranged in a stacking direction;
• forming a memory hole passing through the plurality of sacrifice layers and extending in the stacking direction;
• forming an electric charge accumulating film and a semiconductor layer inside the memory hole;
• forming a stopper insulating layer containing nitrogen (N) and silicon (Si) and covering the plurality of sacrifice layers, the electric charge accumulating film, and the semiconductor layer;
• forming a first protective layer covering the stopper insulating layer;
• forming a first trench extending in the stacking direction and separating the first protective layer, the stopper insulating layer, and the plurality of sacrifice layers in a first direction intersecting with the stacking direction to expose a part of the first protective layer, a part of the stopper insulating layer, and parts of the plurality of sacrifice layers to an inside of the first trench;
• forming a second protective layer inside the first trench;
• removing a portion covering the stopper insulating layer of the second protective layer with a portion covering the plurality of sacrifice layers of the second protective layer remaining to expose a part of the stopper insulating layer to the inside of the first trench;
• forming a third protective layer on the exposed part to the first trench of the stopper insulating layer to form a structure in which the stopper insulating layer is not exposed in the first trench;
• removing the portion covering the plurality of sacrifice layers of the second protective layer to expose the plurality of sacrifice layers to the inside of the first trench;
• removing the plurality of sacrifice layers through the first trench to form a plurality of cavities arranged in the stacking direction;
• and
• forming a plurality of conductive layers arranged in the stacking direction in the plurality of cavities.