Fabrication method for a 3-dimensional nor memory array

Abstract

A process for manufacturing a 3-dimensional memory structure includes: (a) providing one or more active layers over a planar surface of a semiconductor substrate, each active layer comprising (i) first and second semiconductor layers of a first conductivity; (ii) a dielectric layer separating the first and second semiconductor layer; and (ii) one or more sacrificial layers, at least one of sacrificial layers being adjacent the first semiconductor layer; (b) etching the active layers to create a plurality of active stacks and a first set of trenches each separating and exposing sidewalls of adjacent active stacks; (c) filling the first set of trenches by a silicon oxide; (d) patterning and etching the silicon oxide to create silicon oxide columns each abutting adjacent active stacks and to expose portions of one or more sidewalls of the active stacks; (e) removing the sacrificial layers from exposed portions of the sidewalls by isotropic etching through the exposed portions of the sidewalls of the active stacks to create corresponding cavities in the active layers; (f) filling the cavities in the active stacks by a metallic or conductor material; (g) recessing the dielectric layer from the exposed sidewalls of the active stacks; and (h) filling recesses in the dielectric layer by a third semiconductor layer of a second conductivity opposite the first conductivity.