A single-poly non-volatile memory unit includes: a semiconductor substrate having a first conductivity type; first, second and third OD regions disposed on the semiconductor substrate and separated from each other by an isolation region, wherein the first OD region and the second OD region are formed in a first ion well, and the first ion well has a second conductivity type; a first memory cell disposed on the first OD region, a second memory cell disposed on the second OD region. The first memory cell and the second memory cell exhibit an asymmetric memory cell layout structure with respect to an axis. An erase gate is disposed in the third OD region.