Patent ID: 6569713
Filing Date: 2003-05-27
Classification: H01L

Abstract:
A method of fabricating a read only memory, comprising:forming a plurality of columns of bit lines in a substrate; forming a plurality of rows of word lines crossing over the bit lines on the substrate, wherein a first column of channel region and a second column of channel region are respectively formed in the substrate between two alternate pairs of neighboring columns of the bit lines and under each row of the word lines; forming a photoresist layer on the substrate; performing a first exposure step on the photoresist layer covering the first channel region; performing a second exposure step on the photoresist layer covering the second channel region; performing a development step to remove the photoresist layer that has been exposed; using the remaining photoresist layer as a mask to perform an ion implantation step, so that a first coding area and a second coding area are formed on the first and second channel regions, respectively; and removing the photoresist layer.