Abstract: A method of fabricating a SONOS device, in which a first silicon oxide layer, a trapping layer, and a second silicon oxide layer are formed on the substrate. Then, a mask pattern is formed over the substrate to serve as a mask in the implantation process for forming the buried bit-lines. Afterward, a portion of the mask pattern is removed to increase the gap size of the mask pattern, then a pocket ion implantation is performed to form a pocket doped region at the periphery of the buried bit-line by using the mask pattern as a mask. Subsequently, the mask pattern is removed and a thermal process is conducted using the trapping layer as a mask to form a buried bit-line oxide layer. A word-line is subsequently formed over the substrate.

Abstract: A method of fabricating a mask ROM, in which conductive strips are formed with a cap layer on each of them, then a plurality of spacers are formed on the side-walls of the conductive strips, while the substrate under the spacers are used as the coding regions. The buried bit-lines are formed in the substrate between the spacers, then a two-step coding process is performed, wherein the coding regions at the first and the second side of the conductive strips are selectively doped by a first and a second tilt coding implantation with a first and a second coding mask. After the second mask layer and the cap layer are removed, a conductive layer is formed over the substrate, then the conductive layer and the conductive strips are patterned successively to form a plurality of word-lines and plural gates, respectively.