US Patent 7588986 Method of manufacturing a semiconductor device

According to an exemplary embodiment of the present invention, a method of manufacturing a semiconductor device having active regions including a SONOS device region, a high voltage device region, and a logic device region, includes defining the active regions by forming a device isolation region on a semiconductor substrate; performing ion-implantation in the SONOS device region to control a threshold voltage of a SONOS device; performing ion-implantation in the high voltage device region to form a well; performing ion-implantation in the SONOS device region and the logic device region to form a well; and forming an ONO pattern on the SONOS device region, generally by performing a photolithography and etching process on the ONO layer.