Three-dimensional memory and its fabrication method

Abstract

A method of fabricating a three-dimensional memory includes forming a laminated structure including stacked dummy gate layers and interlayer insulation layers on one side of a substrate. The respective adjacent dummy gate layers and interlayer insulation layers form staircase stairs. At least a part of the interlayer insulation layer of each of the staircase stairs is exposed. The method also includes forming a buffer layer covering the staircase stairs. The method further includes removing a part of the buffer layer covering the sidewalls of the staircase stairs to form spacing grooves. The method further includes forming a dielectric layer that fills the spacing grooves and covers the staircase stairs. The method further includes forming a contact hole penetrating through the dielectric layer and the buffer layer and extending to the dummy gate layer farthest from the substrate.