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

A microelectronic device, comprising:

• a conductive stack structure vertically overlying a source structure and comprising alternating conductive structures and insulative structures arranged in tiers, the conductive stack structure comprising:
• a first deck structure;
• and
• a second deck structure vertically overlying the first deck structure;
• strings of memory cells vertically extending through the conductive stack structure;
• stair step structures within the first deck structure and having steps comprising lateral ends of the tiers;
• and
• a liner material on the steps of the stair step structures, a thickness of the liner material decreasing with an increasing distance from the source structure.

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

• forming stair step structures in a first deck structure;
• forming a liner material over steps of the stair step structures;
• forming an interdeck region vertically overlying the first deck structure and a second deck structure vertically overlying the interdeck region;
• forming additional stair step structures in and openings in the second deck structure vertically above and within horizontal boundaries of the stair step structures of the first deck structure;
• forming an additional liner material over additional steps of the additional stair step structures and within the openings in the second deck structure;
• removing portions of the additional liner material at lower vertical boundaries of the openings;
• and
• forming electrically conductive contact structures in contact with the steps of the stair step structures of the first deck structure and the additional steps of the additional stair step structures.

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

• forming a first oxide liner material over steps of stadium structures in a first deck structure;
• forming a first nitride liner material over the first oxide liner material;
• forming a second deck structure over the first deck structure;
• forming a second oxide liner material over steps of additional stadium structures in the second deck structure and over surfaces of openings within the second deck structure vertically overlying the stadium structures of the first deck structure;
• forming a second nitride liner material over the second oxide liner material;
• and
• removing laterally extending portions of the second nitride liner material within the openings in the second deck structure.

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, the at least one microelectronic device comprising:
• first stair step structures within a first deck structure comprising tiers of alternating conductive structures and insulative structures;
• second stair step structures within a second deck structure vertically overlying the first deck structure;
• and
• a nitride liner material adjacent the steps of the first stair step structures, a region between the first deck structure and the second deck structure free of the nitride liner material.