Microelectronic devices including stair step structures, and related memory devices, electronic systems, and methods

A microelectronic device, comprising:

• a stack structure comprising alternating conductive structures and insulative structures arranged in tiers;
• a staircase structure within the stack structure and having steps comprising horizontal ends of the tiers;
• slot structures vertically extending through the stack structure and extending in a first horizontal direction;
• additional slot structures extending in the first horizontal direction between slot structures neighboring each other in a second horizontal direction;
• and
• support pillar structures vertically extending through the stack structure and arranged in rows, one of the rows of the support pillar structures at least partially intersected by one of the additional slot structures.

A memory device, comprising:

• a stack structure comprising a vertically alternating sequence of conductive structures and insulative structures arranged in tiers, the stack structure divided into block structures separated from one another by slot structures;
• strings of memory cells vertically extending through the stack structure;
• additional slot structures within horizontally boundaries of a block structure and extending substantially parallel to the slot structures, the additional slot structures dividing the block structure into sub-block structures, one or more of the sub-block structures having a different width than one or more of the other sub-block structures;
• and
• support pillar structures arranged in rows within each of the sub-block structures.

An electronic system, comprising:

• an input device;
• an output device;
• a processor device operably coupled to the input device and the output device;
• and
• a memory device operably coupled to the processor device and comprising at least one microelectronic device structure, the at least one microelectronic device structure comprising:
• a staircase structure within a stack structure and comprising a vertically alternating sequence of conductive structure and insulative structure arranged in tiers;
• support pillar structures extending through the stack structure, the support pillar structures arranged in rows located horizontally between first slot structures;
• and
• a second slot structure at least partially vertically extending into the stack structure and at least partially into support pillar structures of one of the rows of support pillar structures.