Patent ID: 8921155

Claim:
A method of making a resistive random access memory cell over a substrate, comprising: forming a first electrode layer over the substrate; forming a first copper layer over the first electrode layer and a copper oxide layer over the first copper layer, wherein the forming the first copper layer comprises forming an initial copper layer and oxidizing a top portion of the initial copper layer to leave the first copper layer and form the copper oxide layer; forming a second copper layer over the copper oxide layer; forming a second electrode layer over the second copper layer; etching the first copper layer, the copper oxide layer, second copper layer, and the second electrode layer to form a memory stack having a sidewall; forming a sidewall spacer in contact with the sidewall of the memory stack, wherein the sidewall spacer functions as a barrier to movement of oxygen vacancies into and out of the copper oxide layer, and wherein the sidewall spacer contacts each of the first copper layer, the copper oxide layer, the second copper layer, and the second electrode layer at the sidewall of the memory stack; and forming a dielectric layer around and over the memory stack and the sidewall spacer.