Patent ID: 6440803
Filing Date: 2002-08-27
Classification: H01L

Abstract:
A method of fabricating a mask ROM, comprising the steps of:forming a plurality of conductive strips on a substrate, wherein each conductive strip is formed with a cap layer on it; forming a first spacer and a second spacer on side-walls of each conductive strip, while the substrate under the first spacer is a first coding region and the substrate under the second spacer is a second coding region; forming a plurality of buried bit-lines in the substrate between the conductive strips, forming a first coding mask over the substrate, then performing a first tilt coding implantation to dope a part of the first coding regions; removing the first coding mask; forming a second coding mask over the substrate, then performing a second tilt coding implantation to dope a part of the second coding regions; removing the second coding mask; removing the cap layer; forming a first conductive layer over the substrate; and patterning the first conductive layer and the conductive strips successively to form a plurality of word-lines and a plurality of gates, respectively.