| CPC H10B 43/27 (2023.02) [H01L 29/1037 (2013.01); H10B 41/27 (2023.02); H10B 41/35 (2023.02); H10B 43/35 (2023.02)] | 12 Claims |

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1. A method of forming an elevationally-extending string of memory cells, comprising:
forming a lower stack comprising first-alternating tiers comprising different composition first- and second-lower-stack materials, insulator material above the lower stack, and a lower opening extending through the insulator material and through the first-alternating tiers;
forming lower-stack-channel material in the lower opening;
forming laterally-central material in the lower opening, the laterally-central material comprising an uppermost region having dopant therein and a lowermost dopant-diffusion-barrier region;
forming conductive material in the lower opening electrically coupled with the lower-stack-channel material;
providing lower control-gate material laterally outward of the lower-stack-channel material; and
providing lower insulative-charge-passage material, lower charge-storage material, and a lower charge-blocking region laterally between the lower control-gate material and the lower-stack-channel material;
forming an upper stack comprising second-alternating tiers comprising different composition first and second-upper-stack materials elevationally over the lower stack, the laterally-central material in the lower opening, and the conductive material in the lower opening; the upper stack having an upper opening extending elevationally through the second-alternating tiers and to at least one of the laterally-central material and the conductive material in the lower opening;
forming upper-stack-channel material in the upper opening that is electrically coupled with the lower-stack-channel material through the conductive material in the lower opening;
providing upper control-gate material laterally outward of the respective upper stack-channel material; and
providing upper insulative-charge-passage material, upper charge-storage material, and an upper charge-blocking region laterally between the upper control-gate material and the upper stack-channel material.
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