RRAM with high work function cap

A resistive random-access memory (RRAM) cell comprising:

• a bottom electrode;
• a metal oxide layer, the metal oxide layer having a central portion that is in direct contact with the bottom electrode, a peripheral portion that is nonplanar with the central portion, and a vertical portion between the central portion and the peripheral portion;
• a top electrode directly above the metal oxide layer;
• a dielectric layer underneath the peripheral portion of the metal oxide layer;
• and
• a bottom contact stud surrounded by the dielectric layer and in direct contact with the bottom electrode,
• wherein the bottom electrode and the bottom contact stud have a same contact area.

A method of forming a semiconductor structure comprising:

• receiving a contact structure having a contact area;
• forming a bottom electrode on top of the contact area;
• forming a metal oxide layer, the metal oxide layer having a central portion directly above and in contact with the bottom electrode and a peripheral portion above a dielectric layer, wherein the peripheral portion of the metal oxide layer is nonplanar with the central portion of the metal oxide layer;
• forming a top electrode layer above the metal oxide layer;
• and
• patterning the top electrode layer and the metal oxide layer,
• wherein the dielectric layer is above the contact structure and has an opening exposing the contact area of the contact structure, wherein forming the bottom electrode comprises selectively forming the bottom electrode on top of the exposed contact area inside the opening, the bottom electrode being surrounded by the dielectric layer.