A method of manufacturing a code pattern on a semiconductor substrate with an array of substantially parallel buried bit lines integral therewith and with word lines above the buried bit lines, includes: forming a titanium nitride layer above the word lines, forming and patterning a code mask above the titanium nitride layer, implanting impurities into the substrate through openings in the code mask to form the code pattern, and performing rapid thermal annealing of the implant. The step height of the titanium nitride layer is employed to form the code identification on the substrate.