US 12,347,773 B2
Three-dimensional memory device containing variable thickness word lines with reduced length metal nitride diffusion barriers and methods for forming the same
Rahul Sharangpani, Fremont, CA (US); Raghuveer S. Makala, Campbell, CA (US); and Fei Zhou, San Jose, CA (US)
Assigned to Sandisk Technologies, Inc., Milpitas, CA (US)
Filed by SANDISK TECHNOLOGIES LLC, Addison, TX (US)
Filed on May 11, 2022, as Appl. No. 17/662,926.
Prior Publication US 2023/0369208 A1, Nov. 16, 2023
Int. Cl. H01L 23/528 (2006.01); H01L 23/535 (2006.01); H10B 41/27 (2023.01); H10B 43/27 (2023.01)
CPC H01L 23/5283 (2013.01) [H01L 23/535 (2013.01); H10B 41/27 (2023.02); H10B 43/27 (2023.02)] 11 Claims
OG exemplary drawing
 
11. A method of forming a semiconductor structure, the method comprising:
forming an alternating stack of insulating layers and sacrificial material layers over a substrate;
forming memory openings vertically extending through the alternating stack;
forming memory opening fill structures in the memory openings, wherein each of the memory opening fill structures comprises a respective vertical semiconductor channel and a respective vertical stack of memory elements;
forming backside trenches vertically extending through the alternating stack;
forming backside recesses by removing the sacrificial material layers selective to the insulating layers and the memory opening fill structures;
forming metal nitride liners in first volumes of the backside recesses that are more distal from the backside trenches than a threshold lateral spacing such that the metal nitride liners are not present in second volumes of the backside recesses that are less distal from the backside trenches than the threshold lateral spacing; and
forming respective metal fill material regions both in the second volumes of the backside recesses and on the metal nitride liners in the first volumes of the backside recesses;
wherein:
the metal fill material regions are formed by:
performing a first selective metal deposition process that grows a respective first metal fill material portion directly on each of the metal nitride liners; and
performing a second selective metal deposition process that grows two second metal fill material portions directly on each of the first metal fill material portions;
the first metal fill material portions comprise an upper laterally-extending portion and a lower laterally-extending portion that are separated from each other by a laterally-extending cavity after the first selective metal deposition process; and
the second metal fill material portions are formed within and fills the laterally-extending cavities.