Method for fabricating a floating gate memory device

摘要

Roughly described, a device having twin bit floating gate memory cells is fabricated by first providing a substrate having formed thereon, within a memory area, a composite charge storage film and a protective liner layer over the composite film. The memory area further includes oxide features over buried diffusion regions in the substrate, and polysilicon spacers over the composite film against the sidewalls of the oxide features. The method further involves etching an isolation trench through the composite film laterally between two of the oxide features, using the polysilicon spacers as a mask, and forming an insulator in the trench. A gate conductor is then formed overlying both the composite film and the filled isolation trench between the two oxide features.