| 摘要 |
PURPOSE:To improve write-erase characteristics of a non volatile semiconductor memory and stabilize its operation by forming the gate electrode provided on a non volatile semiconductor memory having a stacked-gate type MOS structure by empolying a two-layer structure comprising a floating gate electrode and a controlled- gate electrode. CONSTITUTION:On the periphery of the surface of a P type Si substrate 1 of surface index (100) or the like, a thick field SiO2 film 3 is formed, and the substrate 1 surrounded therewith is coated with a thin first gate SiO2 film 4. Then, a polycrystalline Si layer 5 to be a floating gate and a second gate SiO2 film 6 are grown being piled and extending over from the film 4 to the circumferential edge of the film 3, and N type impurity ions are implanted in order to provide the film 5 with conductivity. Then, a controlled-gate electrode 7 of polycrystalline Si is provided in the center of the film 6, and by using the electode 7 as a mask, the film 6, the layer 5 and the film 4 on both sides thereof are etched to remove. In the exposed substrate 1, an N type source region 8 and drain region 9 are formed by diffusion. Then, the electrode 7 is doped with an N type impurity to provide it with high conductivity. Thereby, the layer 5 and the electrode 7 provide an electrode having a two-layer structure. |
