Conductive memory stack with non-uniform width

1. A method of making a plurality of conductive memory devices, each conductive memory device operable to be reversibly placed in multiple resistive states, the method comprising:

sputtering a bottom electrode layer;

sputtering a multi-resistive state element layer, the multi-resistive state element layer including a conductive perovskite;

sputtering a top electrode layer;

depositing a hard mask layer;

photo lithographically patterning the hard mask layer and the top electrode layer such that the patterned top electrode and hard mask have a first cross sectional area;

depositing a dielectric material;

etching the dielectric anisotropically to create a sidewall spacer at the edges of the top electrode;

etching the multi-resistive state element layer and the bottom electrode layer using the hard mask such that the etched bottom electrode and multi-resistive state element have a second cross sectional area that is larger than the first cross sectional area; and

wet etching the multi-resistive state element layer,

wherein the wet etching is performed after the etching of the multi-resistive state element layer, the etching of the multi-resistive state element layer forming multi-resistive state element sides, and

wherein the wet etching of the multi-resistive state element removes a thickness of 50-150 Å, thereby forming an undercut from the multi-resistive state element sides.