Memory arrays comprising strings of memory cells and methods used in forming a memory array comprising strings of memory cells

Abstract

A method used in forming a memory array comprising strings of memory cells comprises forming a lower portion of a stack that will comprise vertically-alternating first tiers and second tiers. The stack comprises laterally-spaced memory-block regions. Material of the first tiers is of different composition from material of the second tiers. The lower portion comprises an upper second tier comprising insulative material. The vertically-alternating first tiers and second tiers of an upper portion of the stack are formed above the lower portion. Channel-material strings are formed that extend through the upper portion to the lower portion. Horizontally-elongated lines are formed in the upper second tier longitudinally-along opposing lateral edges of the memory-block regions. Material of the lines is of different composition from that of the insulative material in the upper second tier that is laterally-between the lines. Horizontally-elongated trenches are formed into the stack that are individually between immediately-laterally-adjacent of the memory-block regions and that extend through the upper portion to the lower portion. Other embodiments, including structure independent of method, are disclosed.