Staircase structures for a three-dimensional (3D) memory device are disclosed. In some embodiments, the method includes disposing an alternating dielectric stack on a substrate with first and second dielectric layers alternatingly stacked on top of each other. Next, multiple division blocks can be formed in a staircase region. Each division block includes a first plurality of staircase steps in the first direction. Each staircase step in the first direction has two or more dielectric layer pairs. Then, a second plurality of staircase steps along a second direction, perpendicular to the first direction, can be formed. Each staircase step in the second direction includes the first plurality of staircase steps along the first direction. The method further includes forming an offset number of dielectric layer pairs between the multiple division blocks such that each dielectric layer pair is accessible from a top surface of a staircase step.