Resistive random access memory and manufacturing method thereoff

A method for manufacturing a RRAM, comprising:

• forming an interlayer dielectric layer on a substrate;
• forming a first bottom contact structure and a second bottom contact structure in the interlayer dielectric layer, wherein a top surface of the first bottom contact structure, a top surface of the second bottom contact structure, and a top surface of the interlayer dielectric layer are coplanar;
• forming a first memory cell on the first bottom contact structure, wherein the first memory cell comprises a first bottom electrode layer, and the first bottom electrode layer comprises a first conductive region, and wherein a pattern in which the first conductive region is vertically projected on the first bottom contact structure is a first projection pattern;
• and
• forming a second memory cell on the second bottom contact structure, wherein the second memory cell comprises a second bottom electrode layer, and the second bottom electrode layer comprises a second conductive region, wherein a pattern in which the second conductive region is vertically projected on the second bottom contact structure is a second projection pattern, and wherein the second projection pattern is different from the first projection pattern,
• wherein the first bottom electrode layer further comprises a first insulating region, and the first bottom contact structure is in direct contact with the first insulating region and the first conductive region.