A memory cell disposed on a substrate has a first gate structure and a second gate structure. The memory cell includes a first heavily doped region adjacent to an outer side of the first gate structure. Further, a first lightly doped drain (LDD) region with a first type dopant is between the first heavily doped region and the outer side of the first gate structure. A pocket doped region with a second type dopant is overlapping with the first LDD region. The second type dopant is opposite to the first type dopant in conductive type. A second heavily doped region is adjacent to an outer side of the second gate structure, opposite to the first heavily doped region. A second LDD region with the first type dopant is disposed between the first gate structure and the second gate structure.