A semiconductor device is provided. The semiconductor device includes a semiconductor substrate, and a memory cell disposed on the semiconductor substrate. The memory cell includes a selection transistor and a memory transistor. The selection transistor includes a selection gate, a first source, and a first drain. The memory transistor includes a floating gate, a control gate, a second source, a second drain, and a first insulating layer disposed between the floating gate and the control gate. The semiconductor device further includes a selection gate sidewall spacer disposed near an edge of a bit line of the selection gate of the selection transistor. The selection gate sidewall spacer is separated from the selection gate by a second insulating layer. The selection gate sidewall spacer and the control gate are formed of a first material.