A method of forming a microelectronic device comprises forming isolated nitride structures on steps of stair step structures comprising stacked tiers comprising alternating levels of a first insulative material and a second insulative material, forming a photoresist material over some of the stair step structures, and replacing the isolated nitride structures and the second insulative material with an electrically conductive material to respectively form conductive pad structures and electrically conductive lines. Related microelectronic devices and electronic devices are also disclosed.