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

A method of forming a memory array comprising strings of memory cells, comprising:

• forming storage-material strings in a stack comprising vertically-alternating first tiers and second tiers, the second tiers comprising sacrificial material;
• forming horizontally-elongated trenches in the stack;
• through the trenches, removing the sacrificial material selectively relative to the first tiers;
• after the removing, diffusing material from the trenches into void space in the second tiers to the storage material of the storage-material strings in the second tiers to reduce intrinsic charge-transmissivity of at least some of the storage material of the storage-material strings in individual of the second tiers compared to intrinsic charge-transmissivity of the storage material of the storage-material strings in individual of the first tiers;
• and
• forming conductive lines in the first tiers and forming strings of memory cells in the stack comprising channel-material strings and the storage-material strings.

A memory array comprising strings of memory cells, comprising:

• a vertical stack comprising alternating insulative tiers and conductive tiers;
• strings of memory cells in the stack comprising channel-material strings and storage-material strings extending through the insulative tiers and the conductive tiers;
• and
• at least some of the storage material of the storage-material strings in individual of the insulative tiers being intrinsically less charge-transmissive than is the storage material in the storage-material strings in individual of the conductive tiers.

A memory array comprising strings of memory cells, comprising:

• a vertical stack comprising alternating insulative tiers and conductive tiers, the conductive tiers individually comprising conductive lines;
• strings of memory cells in the stack comprising channel-material strings and storage-material strings extending through the insulative tiers and the conductive tiers;
• individual of the memory cells being in individual of the conductive tiers and comprising the channel material of the channel-material strings, a gate region that is part of one of the conductive lines, and a memory structure laterally-between the gate region and the channel material;
• the memory structure comprising insulative charge-blocking material laterally-adjacent the gate region, insulative charge-passage material laterally-adjacent the channel material, and the storage material in the conductive tiers that is laterally-between the charge-blocking material and the insulative charge-passage material;
• and
• the storage material of the storage-material strings in individual of the insulative tiers at an interface (a) or at an interface (b) being intrinsically less charge-transmissive than is the storage material in the storage-material strings in the individual conductive tiers, where
• (a):
• of the insulative charge-blocking material and the storage material;
• and
• (b):
• of the insulative charge-passage material and the storage material.