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

A memory device, comprising:

• a stack structure comprising alternating conductive structures and insulative structures arranged in tiers, each of the tiers individually comprising a conductive structure and an insulative structure;
• strings of memory cells vertically extending through the stack structure, the strings of memory cells comprising a channel material vertically extending through the stack structure;
• and
• a slot structure vertically extending through the stack structure to a source tier vertically underlying the stack structure, the slot structure comprising:
• a first insulative liner material in contact with sidewalls of the alternating conductive structures and insulative structures defining the slot structure;
• a second insulative liner material in contact with the first insulative liner material;
• and
• a first material contacting sidewalls of the second insulative liner material, at least some of the first material comprising grains extending from a first sidewall of the second insulative liner material to a second, opposing sidewall of the second insulative liner material.

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

• forming pillars comprising a channel material in an array region of a stack structure comprising a vertically alternating sequence of insulative structures and additional insulative structures;
• forming slots vertically extending through the stack structure;
• removing the additional insulative structures through the slots;
• forming conductive structures vertically between pairs of the insulative structures vertically neighboring one another after removing the additional insulative structures through the slots;
• forming an insulative liner material on sidewalls defining the slots;
• and
• forming grains of a first material on sidewalls of the insulative liner material, the grains of the first material laterally extending from a first sidewall of the insulative liner material to a second, opposing sidewall of the insulative liner material.

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:
• strings of memory cells vertically extending through a stack structure comprising a vertically alternating sequence of insulative structures and conductive structures;
• at least one slot structure vertically extending through the stack structure and separating the stack structure into block structures, each block structure comprising some of the strings of memory cells;
• and
• individual grains of a semiconductive material extending from a sidewall of an insulative liner material of the at least one slot structure to an opposite sidewall of the insulative liner material.