Barrier layers for word line contacts in a three-dimensional nand memory and fabrication methods thereof

Abstract

The present disclosure provides a method for forming a three-dimensional memory device. The method includes disposing an alternating dielectric stack on a substrate in a first direction perpendicular to the substrate; and forming a staircase structure and a dividing wall in the alternating dielectric stack. The staircase structure and the dividing wall extend in a second direction parallel to the substrate, and the dividing wall is adjacent to the staircase structure. The method also includes forming, sequentially on the staircase structure, a first barrier layer and a second barrier layer different from the first barrier layer. The method further includes forming a gate line slit (GLS) opening in the dividing wall. The GLS opening penetrates through the alternating dielectric stack in the first direction and is distant from the second barrier layer in a third direction that is parallel to the substrate and is perpendicular to the second direction.