Patent ID: 7635627

Claim:
A method for fabricating a memory device comprising a dual bit memory cell, the method comprising the steps of: forming a first channel dielectric layer at a surface of a semiconductor substrate; depositing a layer of first conductive material overlying the first channel dielectric layer, the layer of first conductive material having a first thickness; patterning the layer of first conductive material and the first channel dielectric layer to form center gate electrodes formed of the first conductive material and exposing a portion of the surface of the semiconductor substrate between adjacent ones of the center gate electrodes; forming a layered structure comprising a tunnel dielectric layer, a charge storage layer and a second dielectric layer overlying the center gate electrode and the portion of the semiconductor substrate; depositing a layer of second conductive material overlying the layered structure; etching the layer of second conductive material to form a region of second conductive material overlying the portion of the semiconductor substrate and having a second thickness less than the first thickness, the step of etching the second conductive material exposing a portion of the layered structure at a sidewall of the center gate electrodes; forming sidewall spacers on the portion of the layered structure; etching the region of second conductive material and the layered structure using the sidewall spacers as an etch mask; ion implanting bit lines in the semiconductor substrate using the sidewall spacers as an implantation mask; depositing a third dielectric layer overlying the bit lines; etching the third dielectric layer and the sidewall spacers to expose a portion of the layer of first conductive material and a portion of the second conductive material; depositing a layer of third conductive material in contact with the portion of the layer of first conductive material and the layer of second conductive material; and patterning the layer of third conductive material to form a word line.