Three-dimensional memory device containing composite word lines including a respective fluorine-free capping sublayer and methods of forming the same

Abstract

A method of forming a memory device includes forming an alternating stack of insulating layers and sacrificial material layers over a substrate, forming memory openings through the alternating stack, forming memory opening fill structures in the memory openings including respective vertical stack of memory elements and a respective vertical semiconductor channel, forming a lateral isolation trench through the alternating stack, forming lateral recesses by removing the sacrificial material layers selective to the insulating layers and the memory opening fill structures, depositing a first tungsten layer in the lateral recesses using a first tungsten deposition process in which a fluorine-containing tungsten precursor gas is used as a reactant, and depositing a second tungsten layer on the first tungsten layer in the lateral recesses using a second tungsten deposition process in which a fluorine-free tungsten precursor gas is used as a reactant.