A semiconductor structure is provided. The semiconductor structure includes a staircase structure including a first stair layer and a second stair layer on the first stair layer. The first stair layer comprises a first conductive film. The semiconductor structure includes a landing pad disposed on the first conductive film. The landing pad has a first pad sidewall facing toward the second stair layer, a first lateral gap distance between an upper portion of the first pad sidewall and the second stair layer is smaller than a second lateral gap distance between a lower portion of the first pad sidewall and the second stair layer.