A three-dimensional (3D) memory device includes interleaved conductive layers and dielectric layers. Edges of the conductive layers and dielectric layers define a plurality of stairs. The 3D memory device may also include a plurality of landing structures each disposed on a respective conductive layer at a respective stair. Each of the landing structures comprises a first layer of a first material and a second layer of a second material. The first layer is over the second layer. The second material is different from the first material.