A twin-ONO-type SONOS memory includes a semiconductor substrate having a source region, a drain region and a channel region between the source and drain regions, twin silicon oxide-silicon nitride-silicon oxide (ONO) dielectric layers, a first ONO dielectric layer being on the channel region and the source region and as second ONO dielectric layer being on the channel region and the drain region, and a control gate on the channel region, between the twin ONO dielectric layers, the twin ONO dielectric layers extending along at least lower lateral sides of the control gate adjacent the channel region, wherein the twin ONO dielectric layers extend towards the source and drain regions further than the control gate.