Memory Arrays Comprising Strings Of Memory Cells And Methods Used In Forming A Memory Array Comprising Strings Of Memory Cells

A method used in forming a memory array comprising strings of memory cells comprises forming a conductor tier comprising conductor material on a substrate. A stack comprising vertically-alternating first tiers and second tiers is formed above the conductor tier. The stack comprises laterally-spaced memory-block regions that have horizontally-elongated trenches there-between. Channel-material strings extend through the first tiers and the second tiers. Material of the first tiers is of different composition from material of the second tiers. A lowest of the first tiers comprises sacrificial material of different composition from the first-tier material there-above and from the second-tier material tier there-above. The sacrificial material is of different composition from that of an uppermost portion of the conductor material of the conductor tier. The sacrificial material is isotropically etched selectively relative to the uppermost portion of the conductor material of the conductor tier, selectively relative to the first-tier material there-above, and selectively relative to the second-tier material there-above. After the isotropic etching, conductive material is formed in the lowest first tier that directly electrically couples together the channel material of individual of the channel-material strings and the conductor material of the conductor tier. Other methods and structure independent of method are disclosed.