Microelectronic devices with tier stacks with varied tier thicknesses, and related methods and systems

Abstract

Microelectronic devices include a stack structure of vertically alternating insulative and conductive structures arranged in tiers. The insulative structures of a lower portion of the stack structure are thicker than the insulative structures of an upper portion. The conductive structures of the lower portion are as thick, or thicker, than the conductive structures of the upper portion. At least one feature may taper in width and extend vertically through the stack structure. The thicker insulative structures of the lower portion extend a greater lateral distance from the at least one feature than the lateral distance, from the at least one feature, extended by the thinner insulative structures of the upper portion. During methods of forming such devices, sacrificial structures are removed from an initial stack of alternating insulative and sacrificial structures, leaving gaps between neighboring insulative structures. Conductive structures are then formed in the gaps. Systems are also disclosed.