Interfacial dopants for dual-dielectric, charge-storage cells

When a suitable interfacial dopant, such as W, is introduced at the interface between the dielectrics of a DDC cell, the write-erase characteristics of the cell are greatly improved. The useful range of the dopant concentration is determined to lie between about 10¹⁴ to 10¹⁵ atoms/cm². The interfacial dopant allows the fabrication of a DDC cell with relatively thick SiO2 layers (> 50 Å). The result is a substantially permanent memory cell that can still be subjected to electrical write-erase at reasonable gate-voltage conditions.