Patent ID: 6620693
Filing Date: 2003-09-16
Classification: H01L

Abstract:
A method for fabricating a mask read-only memory (Mask ROM), comprising the steps of:forming a planar doped region in a substrate; forming a mask layer and a first patterned photoresist layer on the substrate; forming a plurality of trenches in the substrate by patterning the mask layer and the substrate with the first patterned photoresist layer as a mask to divide the planar doped region into a plurality of buried bit-lines; removing the first patterned photoresist layer; removing the mask layer; forming a gate dielectric layer on the substrate; forming a plurality of word-lines on the gate dielectric layer, wherein one portion of a bottom of each trench covered by one word-line serves as one coding region; forming a second patterned photoresist layer over the substrate, the second patterned photoresist layer having a plurality of openings over selected coding regions; and performing an ion implantation with the second patterned photoresist layer as a mask to form a plurality of doped coding regions from the selected coding regions.