Memory device and fabrication method thereof

A method for manufacturing a memory device, the method comprising:

• forming a dielectric layer over a substrate having an metallization pattern;
• forming an opening in the dielectric layer to expose the metallization pattern;
• overfilling the opening with a bottom electrode layer;
• patterning the bottom electrode layer to form a bottom electrode;
• and
• forming a stack over the bottom electrode after patterning the bottom electrode layer, the stack comprising a resistance switching element in contact with the bottom electrode and a top electrode over the resistance switching element.

A method for manufacturing a memory device, the method comprising:

• forming a bottom electrode over a substrate;
• forming an etch stop layer adjacent the bottom electrode after forming the bottom electrode;
• forming a stack over the bottom electrode, the stack comprising a resistance switching element in contact with the bottom electrode and a top electrode over the resistance switching element, wherein forming the stack is performed such that a bottom surface of the resistance switching element is above a top surface of the etch stop layer;
• forming a spacer layer over the stack;
• and
• etching the spacer layer to form a spacer, wherein the etch stop layer has a higher etch resistance to the etching the spacer layer than that of the spacer layer.