Patent ID: 6875659

Claim:
A method of code programming a ROM device having bit lines oriented in a first direction within a substrate, a gate oxide layer above the substrate, and word lines formed above the gate oxide layer in a second direction, the method comprising the following: forming a first implantation resistant layer over the word lines and the gate oxide layer; selectively exposing the first implantation resistant layer by preforming a plurality of exposures using a plurality of masks to develop first code openings, each first code opening being positioned over a word line and between two adjacent bit lines intersecting the word line at a gate region, wherein the first code openings are formed in a pattern in which substantially all of a predetermined selection of gate regions, which may be coded, of the ROM device openings are exposed; forming a second implantation resistant layer over the first code openings of the first implantation resistant layer; selectively exposing the second implantation resistant layer to develop second code openings therein, the second code openings being selected at predetermined locations according to a coding content of the ROM device; and implanting particles through the second code openings.