| 摘要 |
PURPOSE:To considerably increase the capacitance of a memory capacitor and to secure an excellent sensitivity characteristic by a method wherein a groove having a cross-sectional shape nearly equal to the base of a switching transistor is formed under its face in a substrate, a memory capacitor is formed by filling polysilicon via an insulating film formed on an inner wall of this groove and the polysilicon is in ohmic contact with the switching transistor. CONSTITUTION:A groove 44 having an area nearly equal to that of a MOSFET 42 is formed in a silicon substrate 41; a nitride film 51 is deposited on an inner wall of the groove 44; after that, polysilicon 52 is deposited inside the groove 44; thereby, a memory capacitor is formed. Then, the surface of a processed P-type silicon substrate 41 is oxidized thermally; an insulating film 43 is formed. Then, a contact hole 53 is formed in one part of the insulating film 43 in such a way that the polysilicon 52 is exposed; a drain 46, a channel 48 and a source 47 are formed. Then, a gate oxide film 49 is formed; after that, a gate electrode 50 is formed. Then, an insulating film 56 is formed; after that, a contact hole is formed; a word line 55 and a bit line 54 are in ohmic contact individually with the gate electrode 50 and the drain 46; this device is completed. |
