Semiconductor device and method for fabricating the same

A method for fabricating a semiconductor device, comprising:

• depositing a first bottom electrode layer over a substrate;
• depositing a first resistance switching layer over the first bottom electrode layer;
• patterning the first resistance switching layer into a first resistance switching element over the first bottom electrode layer;
• forming a spacer around the first resistance switching element;
• patterning the first bottom electrode layer into a first bottom electrode below the first resistance switching element and the spacer;
• forming an interlayer dielectric layer surrounding the first resistance switching element and the spacer;
• depositing a second bottom electrode layer over the interlayer dielectric layer;
• depositing a second resistance switching layer over the second bottom electrode layer;
• and
• patterning the second resistance switching layer and the second bottom electrode layer respectively into a second resistance switching element and a second bottom electrode by a physical etching process.

A semiconductor device, comprising:

• a substrate;
• a first memory cell over the substrate, wherein the first memory cell comprises a first bottom electrode, a first resistance switching element over the first bottom electrode, and a first top electrode over the first resistance switching element;
• and
• a second memory cell over the substrate, wherein the second memory cell comprises a second bottom electrode, a second resistance switching element over the second bottom electrode, and a second top electrode over the second resistance switching element, wherein the second resistance switching element is larger than the first resistance switching element.