| 摘要 |
PURPOSE:To enable a stacked capacitor in high insulating breakdown strength to be formed by a method wherein polysilicon films are two-layer structured to be composed of a polysilicon layer in low electric resistance as a lower layer and another polysilicon layer doped with no impurity not to be heat- treated as an upper layer. CONSTITUTION:A CVD insulating film 1 is formed on a semiconductor substrate 13 and then a low resistant polysilicon layer 2 is formed on the CVD film 1. After formation of said polysilicon layer 2, a natural oxide film on the surface is removed by fluoric acid solution and then another polysilicon layer 3 700Angstrom thick is formed by pressure reduced CVD process again. This polysilicon layer 3 not doped with any impurity such as P or As etc., becomes a minute compact resistant layer in fine grain diameter. Next, the high resistant polysilicon layer 3 is thermal-oxidized to form a gate insulating film 4. After formation of the gate insulating film 4, polysilicon is formed by pressure reduced CVD process and doped with ordinary impurity to form a blade electrode 5 and a capacitor in high insulating breakdown strength. |
