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, comprising:

• forming a conductor tier comprising conductor material on a substrate;
• forming laterally-spaced memory-block regions individually comprising a vertical stack comprising alternating conductive tiers and insulative tiers directly above the conductor tier, channel-material strings extending through the conductive tiers and the insulative tiers, a lowest of the first tiers comprising sacrificial material;
• and
• forming at least one of (a) and (b), where,
• (a):
• an uppermost portion of the conductor material to comprise conductively-doped semiconductive material that comprises at least one of carbon, nitrogen, oxygen, metal, and n-type conductively-doped semiconductive material also comprising boron;
• and
• (b) overlying material that is directly above and of different composition from that of the sacrificial material of the lowest conductive tier and that comprises at least one of carbon, nitrogen, oxygen, metal, and n-type doped material also comprising boron.

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

• forming a conductor tier comprising conductor material on a substrate;
• forming laterally-spaced memory-block regions individually comprising a vertical stack comprising alternating first tiers and second tiers directly above the conductor tier, channel-material strings extending through the first tiers and the second tiers, a lowest of the first tiers comprising sacrificial polysilicon;
• forming at least one of (a) and (b), where,
• (a):
• an uppermost portion of the conductor material to comprise conductively-doped polysilicon of different composition from that of the sacrificial polysilicon and comprising at least one of carbon, nitrogen, oxygen, metal, and n-type conductively-doped polysilicon also comprising boron;
• and
• (b):
• non-sacrificial polysilicon directly above and of different composition from that of the sacrificial polysilicon and that comprises at least one of carbon, nitrogen, oxygen, metal, and n-type conductively-doped semiconductive material also comprising boron;
• forming horizontally-elongated trenches through the first tiers and the second tiers and that are individually laterally between immediately-adjacent of the memory-block regions and extend to the sacrificial polysilicon;
• through the horizontally-elongated trenches, replacing the sacrificial polysilicon of the lowest first tier with conducting material that directly electrically couples together the channel material of individual of the channel-material strings and the conductor material of the conductor tier;
• and
• through the horizontally-elongated trenches, replacing sacrificial material in the first tiers with conductive material and forming conductive gate lines therefrom.

A memory array comprising strings of memory cells, comprising:

• a conductor tier comprising conductor material;
• laterally-spaced memory blocks individually comprising a vertical stack comprising alternating insulative tiers and conductive tiers, channel-material strings of memory cells extending through the insulative tiers and the conductive tiers, conducting material of a lowest of the conductive tiers directly electrically coupling together the channel material of individual of the channel-material strings and the conductor material of the conductor tier;
• and
• an uppermost portion of the conductor material comprising conductively-doped semiconductive material that is directly against the conducting material, of different composition from that of the conducting material, and comprises at least one of carbon, nitrogen, oxygen, metal, and n-type conductively-doped semiconductive material also comprising boron.

A memory array comprising strings of memory cells, comprising:

• a conductor tier comprising conductor material;
• laterally-spaced memory blocks individually comprising a vertical stack comprising alternating insulative tiers and conductive tiers, channel-material strings of memory cells extending through the insulative tiers and the conductive tiers, conducting material of a lowest of the conductive tiers directly electrically coupling together the channel material of individual of the channel-material strings and the conductor material of the conductor tier;
• and
• overlying material that is directly above, directly against, and of different composition from that of the conducting material of the lowest conductive tier and comprises at least one of carbon, nitrogen, oxygen, metal, and n-type doped material also comprising boron.

A memory array comprising strings of memory cells, comprising:

• a conductor tier comprising conductor material;
• laterally-spaced memory blocks individually comprising a vertical stack comprising alternating insulative tiers and conductive tiers, channel-material strings of memory cells extending through the insulative tiers and the conductive tiers, conducting material of a lowest of the conductive tiers directly electrically coupling together the channel material of individual of the channel-material strings and the conductor material of the conductor tier;
• the conducting material comprising conductively-doped polysilicon;
• an uppermost portion of the conductor material comprising conductively-doped polysilicon that is directly against the conductively-doped polysilicon of the conducting material and that comprises at least one of carbon, nitrogen, oxygen, metal, and n-type conductively-doped polysilicon also comprising boron;
• polysilicon directly above and directly against the conductively-doped polysilicon of the conducting material and that comprises at least one of carbon, nitrogen, oxygen, metal, and n-type conductively-doped polysilicon also comprising boron;
• and
• the conductively-doped polysilicon of the conducting material having less, if any, of carbon, nitrogen, oxygen, the metal, and the n-type conductively-doped polysilicon also comprising boron than all carbon, nitrogen, oxygen, the metal, and the n-type conductively-doped polysilicon that is in each of said uppermost portion of the conductor material and said polysilicon that is directly above and directly against the conductively-doped polysilicon of the conducting material.