Microelectronic devices including staircase structures, and related memory devices, electronic systems, and methods

A memory device, comprising:

• a stack structure comprising tiers comprising alternating conductive structures and insulating structures over a source tier;
• a staircase structure having steps comprising horizontal ends of at least some of the tiers;
• conductive contact structures in electrical communication with the steps of the staircase structure;
• support pillar structures extending through the stack structure and horizontally offset from the conductive contact structures;
• data lines over the stack structure;
• strings of memory cells extending through the stack structure and in electrical communication with the source tier and the data lines;
• and
• a bridge structure between a first support pillar structure and a second support pillar structure adjacent the first support pillar structure, the bridge structure comprising an electrically insulating material electrically isolating conductive contact structures adjacent the first support pillar structure and the second support pillar structure from each other.

A method of forming a microelectronic device, the method comprising:

• forming openings through a stack structure comprising vertically alternating insulating structures and other insulating structures arranged in tiers and defining a staircase structure having steps comprising edges of at least some of the tiers, the openings extending through at least one seam within an insulating material over the staircase structure;
• forming an insulating liner material within the openings and within the at least one seam to form support pillar structures, at least some of the support pillar structures adjacent on another coupled together by a bridge structure comprising the insulating liner material;
• replacing the other insulating structures with a conductive material to form conductive structures;
• and
• forming conductive contact structures electrically coupled to the conductive structures of the staircase structure to be laterally offset from the support pillar 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 comprising:
• a stack structure comprising tiers of alternating conductive structures and insulating structures;
• a staircase structure within the stack structures and comprising steps comprising edges of the conductive structures of the alternating conductive structures and insulating structures;
• conductive contact structures electrically coupled to the conductive structures of the staircase structure;
• support pillar structures horizontally offset from the conductive contact structures and comprising an electrically insulating material extending through the stack structure;
• and
• bridge structures extending between at least some of the support pillar structures and electrically isolating the conductive contact structures from each other.