Semiconductor storage device and method for manufacturing semiconductor storage device

A method for manufacturing a semiconductor storage device, the method comprising:

• forming a first stacked body including a device region and a mark region surrounding the device region;
• forming a plurality of first patterns in the device region of the first stacked body such that the plurality of first patterns extend in a stack direction of the first stacked body;
• forming a plurality of second patterns in the mark region of the first stacked body such that the plurality of second patterns each have a dimension identical to a dimension of each first pattern of the plurality of first patterns and the plurality of second patterns extend in the stack direction of the first stacked body;
• forming sacrificial layers inside the plurality of second patterns in the mark region;
• forming a mask pattern that covers a first region of the plurality of second patterns and exposes a second region of the plurality of second patterns such that the second region is surrounded by the first region;
• removing the sacrificial layers from the second patterns in the second region using the mask pattern and forming a first step down from the first region to the second region at a border portion between the first region and the second region;
• exposing at least a part of the sacrificial layer of one second pattern of the plurality of second patterns in the first region on a side surface of the first step facing the second region by setting back the side surface toward the first region;
• and
• forming a second step, transferred from the sacrificial layer of the second pattern exposed on the side surface of the first step, in a portion of a second stacked body overlying the second region by forming the second stacked body on the first stacked body.