Semiconductor memory device and method for manufacturing same
According to one embodiment, a method for manufacturing a semiconductor memory device includes: forming a stacked body including insulating films stacked alternately with electrode films, a memory hole is made in one portion of the stacked body to extend in a stacking direction, a charge storage layer is provided on an inner surface of the memory hole, a semiconductor member is provided in the memory hole; forming a hard mask on the stacked body, the hard mask has a plurality of holes of mutually different sizes; plugging the smallest of the holes while shrinking the other holes by depositing a mask material; making contact holes by removing a prescribed number of the insulating films and a prescribed number of the electrode films in regions directly under the other holes by performing etching using the mask material and the hard mask as a mask; and filling conductive material into the contact holes.
1. A semiconductor memory device, comprising:
a stacked body including a plurality of electrode films stacked alternately with a plurality of insulating films, a configuration of an end portion of the stacked body being a stairstep configuration including a terrace formed for each of the electrode films;
contacts, each of the contacts having a lower end connected to a portion of the electrode film forming the terrace;
a semiconductor member provided inside a portion of the stacked body other than the end portion to extend in a stacking direction of the insulating films and the electrode films; and
a charge storage layer provided between the electrode film and the semiconductor member,
an upper end portion of one of the contacts connected to one of the electrode films being thicker than an upper end portion of one other of the contacts connected to one other of the electrode films positioned higher than the one of the electrode films, the one of the contacts being finer downward in stages, and the one of the contacts becoming discontinuously finer at a level of the electrode film.
2. The device according to claim 1 , wherein the terraces are arranged in a chessboard-like configuration as viewed from the stacking direction.
3. The device according to claim 2 , wherein
diameters of the upper end portions of the contacts arranged along a first direction are different from each other,
(n−1) electrode films are interposed between two of the electrode films respectively connected to two of the contacts mutually adjacent in the first direction, and
two of the electrode films respectively connected to two of the contacts mutually adjacent in a second direction are adjacent to each other in the stacking direction,
the first direction and the second direction are two directions of the arrangement of the terraces, m is a number of the terraces arranged in the first direction, n is a number of the terraces arranged in the second direction.
4. The device according to claim 3 , wherein the value of n is not less than the value of m.
5. The device according to claim 1 , wherein a surface area of a lower end of the one of the contacts is equal to a surface area of a lower end of the one other of the contacts.
6. The device according to claim 1 , wherein the one of the contacts is discontinuously finer at a level of the electrode film in two stages.
7. The device according to claim 1 , wherein the one of the contacts is discontinuously finer at a level of the electrode film in three stages.
8. The device according to claim 1 , wherein the one of the contacts is discontinuously finer at a level of the electrode film in four stages.