TW241395B - Fabrication method for multi-level mask ROM - Google Patents

Abstract

A multi-level mask ROM which is applicable to one substrate includes: 1. formed multiple heavily doped source/drain on the substrate, and forming multiple bit lines by extending along the first direction; 2. forming multiple gate oxide on the substrate and extending along the second direction which is perpendicular to the first one, and forming transistor channel on the substrate between every two neighbor bit lines under the gate oxide; in which the gate oxide thickness is selected from one series sequences; 3. forming multiple gate electrodes on the gate oxide, and forming multiple bit lines by extending along the second direction; in which the transistor channel, the source/drain connected with the transistor channel, the gate oxide on the transistor channel and the gate transistor forms one memory cell together, by the thickness change of the gate oxide and changing threshold potential to form multi-level storage memory cell.