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

A memory device, comprising:

• a stack structure comprising conductive structures vertically interleaved with insulative structures;
• strings of memory cells vertically extending through the stack structure;
• a staircase structure within the stack structure defined by steps comprising lateral ends of the conductive structures and the insulative structures;
• and
• conductive contacts vertically extending through the stack structure, each of the conductive contacts individually comprising:
• a first portion vertically extending from an uppermost boundary of the stack structure to conductive material underlying a lowermost boundary of the stack structure;
• a second portion laterally surrounding the first portion and in physical contact with one of the conductive structures of the stack structure at an elevational level of one of the steps of the staircase structure;
• and
• at least one insulative liner material vertically overlying the staircase structure, the second portion of each of the conductive contacts laterally intervening between the first portion of each of the conductive contacts and the at least one insulative liner material.

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

• forming a stack structure over a source tier including conductive material, the stack structure comprising a vertically alternating sequence of insulative structures and additional insulative structures arranged in tiers, each of the tiers individually comprising at least one of the insulative structures and at least one of the additional insulative structures;
• forming at least one insulative liner material over a staircase structure within the stack structure, the staircase structure having steps comprising lateral edges of the tiers of the stack structure;
• forming first openings extending through the stack structure within a horizontal area of the staircase structure and exposing portions of the conductive material of the source tier;
• forming first sacrificial structures within the first openings;
• at least partially replacing the additional insulative structures with conductive structures;
• removing the first sacrificial structures to form contact openings extending to and exposing portions of additional conductive material underlying the conductive material of the source tier;
• forming support structures vertically extending through the stack structure and within a horizontal area of the staircase structure;
• forming conductive contacts within the contact openings, the conductive contacts vertically extending through the stack structure and horizontally neighboring the support structures within the horizontal area of the staircase structure, the conductive contacts in electrical communication with the additional conductive material, and each of the conductive contacts having a horizontally projecting portion in contact with one of the conductive structures of the stack structure at one of the steps of the staircase structure;
• and
• forming dielectric-filled trenches dividing the stack structure into multiple blocks individually including some of the conductive contacts and some of the support structures within horizontal boundaries of the blocks.

An electronic system, comprising:

• a processor operably coupled to an input device and an output device;
• and
• a memory device operably coupled to the processor, the memory device comprising:
• a stack structure comprising dielectric materials and conductive materials vertically alternating with the dielectric materials;
• conductive contacts vertically extending through the stack structure from an uppermost boundary of the stack structure to conductive routing structures underlying a lowermost boundary of the stack structure, at least some of the conductive materials of the stack structure in electrical communication with at least some of the conductive routing structures by way of the conductive contacts;
• strings of memory cells vertically extending through the stack structure;
• support structures horizontally neighboring the conductive contacts;
• and
• dielectric-filled trenches dividing the stack structure into multiple blocks individually including some of the conductive contacts and some of the support structures within horizontal boundaries of the blocks.