Methods of forming an array of elevationally-extending strings of memory cells individually comprising a programmable charge-storage transistor

A method of forming an array of elevationally-extending strings of memory cells comprises forming a stack comprising alternating insulative tiers and wordline tiers. A select gate tier is above an upper of the insulative tiers. Channel openings extend through the alternating tiers and the select gate tier. Charge-storage material is formed within the channel openings elevationally along the alternating tiers and the select gate tier. Sacrificial material is formed within the channel openings laterally over the charge-storage material that is laterally over the select gate tier and that is laterally over the alternating tiers. Elevationally-outer portions of each of the charge-storage material and the sacrificial material that are within the channel openings are etched. After such etching, the sacrificial material is removed from the channel openings. After such removing, insulative charge-passage material then channel material are formed within the channel openings laterally over the charge-storage material that is laterally over the wordline tiers. The wordline tiers are formed to comprise control-gate material having terminal ends corresponding to control-gate regions of individual memory cells and to have a charge-blocking region of the individual memory cells laterally between the charge-storage material and individual of the control-gate regions.