| 摘要 |
PURPOSE:To make it possible to apply a three-layered film to an isolation structure by a simple process and to prevent breakdown of a thin insulating film at the bottom of a groove inviting a fault of all bits by a method wherein the inside of the groove of a silicon substrate is oxidized, thereon a nitride film is piled, the nitride film at the bottom of the groove is removed leaving a groove side wall, and the surface of the nitride film as well as the part from which the nitride film is removed are oxidized. CONSTITUTION:A sidewall of a groove and the bottom of a silicon substrate 1 having the excavated groove are oxidized, thereon a nitride film 3 is piled, the nitride film 3 of the groove bottom is removed leaving the nitride film 3 on the sidewall, the surface of the nitride film 3 and the part removed from the nitriding film 3 are oxidized 2, 5 so as to form the storage capacity part of dynamic RAM. For instance, the Si substrate 1, wherein the groove 10 is excavated, a storage node n<+> region 7 and a P<+> region 8 for isolation are formed, is thermally oxidized to form an oxide film 4, and thereon the silicon nitride film 3 is piled by a CVD method followed by partly removing the nitride film 3 on the groove bottom by anisotropic etching. Next, oxidation is performed to form the thin oxide film 2 on the surface of the nitride film 3 and the relatively thick oxide film 5 at the groove bottom followed by forming a polysilicon plate 6 on the groove 10. |
