| 摘要 |
PURPOSE:To prevent a bird peak from taking place, by etching an SiO2 film formed on an Si substrate with an Si3N4 mask in the direction of the thickness thereof, developing a step thereto and oxidizing again. CONSTITUTION:An Si3N4 mask 13 is coated on an SiO2 film 12 on a P- type Si substrate 11, and by oxidation an SiO2 film 14 is formed. Then by means of HF liquid the film 14 is etched away to develop a step 15 and a shelf 16 thereto. By implanting B ions, forming a P reaction preventing layer 17, and applying a wet oxidation with the Si3N4 mask 13 at a high temperature, a field oxidized film 18 is formed on the same level as the substrate and the bird peak adjacent to the mask 13 can be prevented from taking place. Thereafter the mask 13 and the SiO2 film below the mask are removed, and by employing the exisiting method the MOSFET or the like is formed on the device forming region thereof. With an arrangement, a field oxidazed film can be formed with fairly good reproducibility without contamination thereto and a device with high resistance to pressure can be obtained where the B of anti-inversion does not diffuse to the device forming region and no wiring breakdown occurs. |
