An oxidized region is arranged between a substrate of semiconductor material and a nitride liner, which covers wordline stacks of a memory cell array and intermediate areas of the substrate, and is provided to separate the nitride liner both from the substrate and from a memory layer sequence of dielectric materials that is provided for charge-trapping. The nitride liner is used as an etching stop layer in the formation of sidewall spacers used in a peripheral area to produce source/drain junctions of transistors of the addressing circuitry.