| 摘要 |
PURPOSE:To improve the dielectric strength in a memory cell, by providing an insulation film formed of silicon oxide containing an appropriate quantity of metallic atoms, between a floating gate and a control gate. CONSTITUTION:A silicon substrate 1 is provided with a field insulation film 2 and a gate insulation film 3. Polycrystalline silicon is deposited on the gate insulation film 3 and patterned to form a floating gate 4. A film 10 of WSi2 for example is deposited on the whole surface and heat treated. The surface of the film 10 and the surface of the floating gate 4 are oxidized to form an insulation film 5. Thus, a small quantity of W atoms are left in the silicon oxide. Polycrystalline silicon is then deposited on the whole surface and pat terned so that a control gate 6 is formed on the gate 4. Finally, source/drain regions 7 and 7 are provided by ion implantation or the like and thus a memory cell is completed. According to this construction, the W atoms, which serve as traps, capture electrons and polarize them. The field concentration is thereby decreased and therefore the field dielectric strength can be improved. |
