SEMICONDUCTOR MEMORY DEVICE AND MANUFACTURING METHOD THEREOF

A semiconductor memory device of embodiments includes a semiconductor substrate having a first and a second region adjacent to the first region in a first direction, a laminated body including electrode layers laminated on the semiconductor substrate in a second direction, a first insulator splitting the laminated body at the second region in a third direction, and extending in the first and second direction, and branching into two insulator films at the first region, and enclosing continuously a first portion of the laminated body, a contact portion extending in the first portion in the second direction, and a memory portion extending through the laminated body and the first insulator in the second direction at the second region. A first width in the third direction of the first portion is wider than a second width in the third direction of at least one of the electrode layers at the second region.