A microelectronic device comprises a microelectronic device structure having a memory array region and a staircase region. The microelectronic device structure comprises a stack structure having tiers each comprising a conductive structure and an insulative structure; staircase structures confined within the staircase region and having steps comprising edges of the tiers of the stack structure within the deck and the additional deck; and semiconductive pillar structures confined within the memory array region and extending through the stack structures. The stack structure comprises a deck comprising a group of the tiers; an additional deck overlying the deck and comprising an additional group of the tiers; and an interdeck section between the deck and the additional deck and comprising a dielectric structure confined within the memory array region, and another group of the tiers within vertical boundaries of the dielectric structure and confined within the staircase region.