Patent ID: 7645672

Claim:
A method for fabricating a mask ROM comprising: depositing an insulating film on a semiconductor substrate having a device isolation region and an active region; forming BN junction regions by implanting impurity ions to predetermined portions of the substrate, wherein forming the BN junction regions comprises: depositing a nitride film on the insulating film; forming nitride film patterns by selectively removing the nitride film; forming first sidewall spacers at sides of the nitride film patterns; implanting impurity ions into the semiconductor substrate using the nitride film patterns and the first sidewall spacers as masks to form the BN junction regions; and removing the nitride film patterns and the spacers; forming first electrode layers by depositing polysilicon on the insulating film and selectively removing the polysilicon; forming second sidewall spacers at sides of the first electrode layers; and forming second electrode layers between the second sidewall spacers.