A semiconductor device includes an erase gate electrode, an erase gate dielectric, first and second floating gate electrodes, first and second control gate electrodes, a first select gate electrode, a second select gate electrode, a common source strap, and a silicide pad. The erase gate electrode is over a first portion of a substrate. The common source strap is over a second portion of the substrate, in which the common source strap and the erase gate electrode are arranged along a second direction perpendicular to the first direction. The silicide pad is under the common source strap and in the second portion of the substrate, wherein a top surface of the silicide pad is flatter than a bottom surface of the erase gate dielectric.