| 摘要 |
PURPOSE:To enable the carrier injection to the gate, by increasing the dielectric constant of the gate insulator at the part where the source region and the Si substrate in the vicinity oppose with the floating gate film than that for the insulation film on other part. CONSTITUTION:Thick field SiO2 film 9 is formed at the both ends of the N type Si substrate 1, and thin gate SiO2 film 4 is coated at the region surrounded with this. Further, P ions are injected selectively with the film 4, heat treatment is made, this is changed into the PSG film 4a, the dielectric constant is taken as about 3.9 which is greater than the dielectric constant, about 3.5 of the film 4b remained and not made for ion injection. After that, the polycrystal Si layer 5 is deposited on the entire surface, the layer 5 and the films 4a and 4b are etched selectively, remaining the films 4a and 4b having the floating gate layer 5 on the surface of the center of the substrate 1. Further, in the substrate 1 outside, the source and drain regions 2, 3 of P<+> type are formed by diffusion, they are covered with the SiO2 film 6, and the electrodes 7 and 8 are attached by providing the opening. |
