US Patent 10355198 Memory device and fabrication method thereof

A memory device includes an MTJ structure and a first metal residue. The MTJ structure includes a top surface having a first width, a bottom surface having a second width greater than the first width, and a stepped sidewall structure between the top surface and the bottom surface. The stepped sidewall structure includes a first sidewall, a second sidewall, and an intermediary surface connecting the first sidewall to the second sidewall. The first metal residue is in contact with the first sidewall and not in contact with the second sidewall.