| 摘要 |
PURPOSE:To improve the gate withstand voltage doing less damage to a gate oxide film caused by ion implantation by a method wherein impurity ions for adjusting threshold value voltage are implanted through a silicon nitride film and then another gate oxide film is formed. CONSTITUTION:A silicon oxide film 2 is formed on the surface of a P type silicon substrate 1 and then a silicon nitride film 3 is deposited on the film 2 to be patterned. Next, ion-implanted regions 4 forming channel cut regions 4A are formed using the Si3N4 film 3 as a mask. In order to form channel dose regions 11A, an ion implanted layer 11 and an ion implanted region 12 are formed respectively below the Si3N4 film 3 and in the region not coated with the Si3N4 film 3. Next, the channel cut regions 4A are formed below field oxide films 5 formed on the surface of region with no pattern of Si3N4 film 3. Then, an SiO2 gate oxide film 6 is formed on the Si exposed surface of Si substrate 1 to be coated with polysilicon and then doped with phosphorus to reduce the resistance. Finally, the gate oxide film 6 is patterned to form a gate electrode 8 while arsenic ions are implanted in the substrate 1 to form a source 9 and a drain 10.
|
