Patent ID: 11961801
Assignee: MICRON TECHNOLOGY, INC.
Field: Semiconductors (Electrical engineering)
Classification: CPC H | IPC H

Claim 27:
28. A method of forming integrated circuitry comprising:
forming two three-dimensional (3D) array regions that will individually comprise tiers of electronic components in a finished-circuitry construction, a stair-step region being between the two 3D-array regions, the two 3D-array regions and the stair-step region there-between collectively comprising a vertical stack comprising alternating first tiers and second tiers of different composition relative one another;
forming first stair-step structures that alternate with second stair-step structures along a first direction within the stair-step region;
the first stair-step structures being formed to comprise two opposing first flights of stairs in a first vertical cross-section along the first direction, the stairs in the first flights each having multiple different-depth treads in a second vertical cross-section that is along a second direction that is orthogonal to the first direction;
the second stair-step structures being formed to comprise two opposing second flights of stairs in the first vertical cross-section, the stairs in the second flights each having only a single one tread along the second direction;
the forming of the first stair-step structures comprising a first etching process, the first etching process comprising etching two and only two of the first tiers and etching two and only two of the second tiers in at least initially forming individual of the stairs of the first flights of stairs in the first vertical cross-section;
the forming of the second stair-step structures comprising a second etching process, the second etching process comprising etching one and only one of the first tiers and etching one and only one of the second tiers in at least initially forming individual of the stairs of the second flights of stairs in the first vertical cross-section; and
after the first etching process, etching the stairs of the first flights of stairs to form at least one of the different-depth treads.