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

A memory array comprising strings of memory cells, the memory array comprising:

• laterally-spaced memory blocks individually comprising a vertical stack comprising alternating insulative tiers and conductive tiers above a conductor tier, channel-material-string constructions of memory cells extending through the insulative tiers and the conductive tiers, the channel material of the channel-material-string constructions directly electrically coupling to conductor material of the conductor tier;
• and
• substructure material in the conductor tier that spans laterally-across and laterally-between bottoms of multiple of the channel-material-string constructions, the substructure material being of different composition from an upper portion of the conductor material, the substructure material comprising laterally-opposing sides that are spaced laterally-inward of laterally-opposing sides of the laterally-spaced memory blocks.

A memory array comprising strings of memory cells, the memory array comprising:

• laterally-spaced memory blocks individually comprising a vertical stack comprising alternating insulative tiers and conductive tiers above a conductor tier, channel-material-string constructions of memory cells extending through the insulative tiers and the conductive tiers, the channel material of the channel-material-string constructions directly electrically coupling to conductor material of the conductor tier;
• and
• substructure material in the conductor tier that spans laterally-across and laterally-between bottoms of multiple of the channel-material-string constructions, the substructure material being of different composition from an upper portion of the conductor material, the upper portion of the conductor material in the conductor tier being directly above the substructure material.