Methods of forming microelectronic devices, and related microelectronic devices

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

• forming a first block region and a second block region separated from one another by a staircase structure coupled to global word lines;
• forming a pattern of openings vertically extending through a vertically alternating sequence of insulative material and additional insulative material within in each of the first block region and the second block region, the pattern of openings comprising groups of openings;
• merging openings within respective groups of openings to form merged openings;
• and
• forming thin film transistors within the merged openings.

A microelectronic device, comprising:

• a stack structure comprising tiers respectively including a local word line structure;
• global word lines vertically overlapping the stack structure;
• and
• transistors at vertical positions of the tiers of the stack structure and respectively comprising:
• a first source/drain region coupled to one of the global word lines;
• a second source/drain region coupled to a local word line;
• and
• a channel region horizontally extending from the first source/drain region to the second source/drain region, the channel region comprising:
• a relatively smaller width than each of the first source/drain region and the second source/drain region in a first horizontal direction;
• and
• a relatively larger length than each of the first source/drain region and the second source/drain region in a second horizontal direction different than the first horizontal direction;
• and
• a gate horizontally neighboring the channel region.