Abstract: A microelectronic device comprises vertically alternating conductive structures and insulating structures arranged in tiers, each of the tiers individually comprising one of the conductive structures and one of the insulating structures; a staircase structure within the stack structure and having steps comprising edges of at least some of the tiers; a source tier underlying the stack structure and comprising: a source structure, and first discrete conductive structures horizontally separated from one another and the source structure by at least one dielectric material; conductive contact structures on the steps of the staircase structure; and first conductive pillar structures horizontally alternating with the conductive contact structures and vertically extending through the stack structure to the first discrete conductive structures of the source tier. A memory device, a 3D NAND Flash memory device, and an electronic system are also described.

Abstract: Some embodiments include an integrated assembly having a conductive expanse over conductive nodes. The conductive nodes include a first composition. A bottom surface of the conductive expanse includes a second composition which is different composition than the first composition. A stack is over the conductive expanse. The stack includes alternating first and second levels. Pillar structures extend vertically through the stack. Each of the pillar structures includes a post of conductive material laterally surrounded by an insulative liner. At least one of the posts extends through the conductive expanse to directly contact one of the conductive nodes. Some embodiments include methods of forming integrated assemblies.

Abstract: A microelectronic device comprises vertically alternating conductive structures and insulating structures arranged in tiers, each of the tiers individually comprising one of the conductive structures and one of the insulating structures; a staircase structure within the stack structure and having steps comprising edges of at least some of the tiers; a source tier underlying the stack structure and comprising: a source structure, and first discrete conductive structures horizontally separated from one another and the source structure by at least one dielectric material; conductive contact structures on the steps of the staircase structure; and first conductive pillar structures horizontally alternating with the conductive contact structures and vertically extending through the stack structure to the first discrete conductive structures of the source tier. A memory device, a 3D NAND Flash memory device, and an electronic system are also described.