Method used in forming memory circuitry comprising stairs in a stair-step region using first and second layers of imageable resist

Abstract

A method used in forming memory circuitry comprises forming a stack comprising vertically-alternating first tiers and second tiers. The stack extends from a memory-array region into a stair-step region. The first tiers are conductive and the second tiers are insulative at least in a finished-circuitry construction. A first layer of imageable resist is exposed to actinic radiation and developed to form a first opening there-through in the stair-step region. The developed first layer is used in a plurality of alternating etching and lateral-trimming steps that widens the first opening and forms two opposing flights of stairs in the stack in the stair-step region. A second layer of imageable resist is formed directly above the two opposing flights of stairs. The second layer is exposed to actinic radiation and developed to form a second opening there-through. The second opening exposes all of the stairs of one of the two opposing flights. The second layer is directly above all of the stairs in the other of the two opposing flights. The developed second layer is used in a plurality of alternating etching and lateral-trimming steps that widens the second opening, lengthens at least one of the two opposing flights of stairs, and extends the two opposing flights of stairs deeper into the stack. Other embodiments, including structure, are disclosed.