The memory cell includes a first unit, a semiconductor layer, a second unit, and a doped region. The first unit includes a first gate, a first charge trapping layer, and a second charge trapping layer. The first and the second charge trapping layer are respectively disposed on both sides of the first gate. The semiconductor layer is disposed on the first unit. The second unit is disposed on the semiconductor layer and is in mirror symmetry to the first unit. The second unit includes a second gate and a third and a fourth charge trapping layer respectively disposed on both sides of the second gate. The doped region is disposed at both sides of the semiconductor layer and serves as a common source/drain region of both the first and the second unit.