| 摘要 |
PURPOSE:To enable a charge accumulation layer to be machined to an improved shape where dielectric breakdown is hard to occur by a process performing etching a capacity insulation film where one part is exposed by etching a cell plate and a process for etching the exposed charge accumulation layer and the cell plate simultaneously. CONSTITUTION:A thermal oxide 23, a polysilicon 22, and a PSG 21 are provided in sequence on a substrate 1 for forming a groove 16. A charge accumulation layer 3 is accumulated within the groove 16 and the charge accumulation layer 3 at the bottom surface is etched. A capacity insulation film 4 is formed on the surface of the charge accumulation layer 3, the groove 16 is embedded by a cell plate 14 consisting of polysilicon, the cell plate 14 is etched for exposing one part of the capacity insulation film 4. One part of this exposed capacity insulation film 4 is eliminated by fluoric acid or thermal phosphoric acid and then the charge accumulation layer 3 and the cell plate 14 are simultaneously dug by anisotropic etching. Then, after eliminating the protruded part of the capacity insulation film 4 with fluoric acid or thermal phosphoric acid, an insulation layer 5 is embedded. |
