| 摘要 |
PURPOSE:To prevent the short channel effect as well as to contrive high integration of the dynamic memory device by a method wherein the channel forming region of the FET to be used for the transfer of a policrystalline Si is dug down deeper than the N-layer to be used for source and drain. CONSTITUTION:A field oxide film 33 is formed on a p type Si substrate 31 overlapping a p<+> layer 32. An N-layer 34 is formed on the surface of the film 33, and a thin exide film 35, a polycrystalline film Si 36 and an oxide film 37 are laminated, an aperture is selectively provided, and the N-layer 34 is exposed. Then, a polycrystalline Si layer 38 and a tick oxide film 39 are laminated, a selective etching is performed, the N-layer 34 is removed by performing a reactive ion etching using the films 37 and 39 as a mask, and the surface of the channel section is dug down deeper than the layer 34. A gate oxide film 40 is formed on the exposed p type substrate, and an oxide film is formed on the polycrystalline Si films 36 and 38. Besides, a gate 41 to be used for the transfer of polycrystalline Si is provided, and an oxide film 42 is covered on the above. According to this constitution, the channel section is formed lower than the N type source and drain region, short channel effect is prevented, and memory holding is prerformed positively, thereby enabling to miniaturize the subject device. |
