US 11,956,955 B2
Method used in forming a memory array comprising strings of memory cells in which liners are isotropically etched
John D. Hopkins, Meridian, ID (US); and Nancy M. Lomeli, Boise, ID (US)
Assigned to Micron Technology, Inc., Boise, ID (US)
Filed by Micron Technology, Inc., Boise, ID (US)
Filed on Jan. 15, 2021, as Appl. No. 17/150,322.
Prior Publication US 2022/0231042 A1, Jul. 21, 2022
Int. Cl. H10B 43/27 (2023.01); H01L 21/225 (2006.01); H10B 41/27 (2023.01)
CPC H10B 43/27 (2023.02) [H01L 21/2254 (2013.01); H10B 41/27 (2023.02)] 17 Claims
OG exemplary drawing
 
1. 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 a stack comprising vertically-alternating first tiers and second tiers above the conductor tier, material of the first tiers being of different composition from material of the second tiers;
forming vertically-extending channel-material strings into the stack;
forming a liner laterally-outside of individual of the channel-material strings in one of the first tiers and in one of the second tiers;
isotropically etching the liners to form void-spaces in the one second tier above the one first tier, individual of the void-spaces being laterally-between the individual channel-material strings and the second-tier material in the one second tier, the liners before and after the isotropically etching individually having their uppermost surface above the conductor tier, below a bottom of an uppermost of the first tiers, and below uppermost surfaces of the individual channel-material strings;
forming conductively-doped semiconductive material against sidewalls of the channel material of the channel-material strings in the one first tier and that extends upwardly into the void-spaces in the one second tier; and
heating the conductively-doped semiconductive material to diffuse conductivity-increasing dopants therein from the void-spaces laterally into the channel material laterally there-adjacent and upwardly into the channel material that is above the void-spaces.