| 摘要 |
PURPOSE:To form a tapered window, by forming a high concentration region on a PSG (phosphosilicate glass) film, opening a mouth thereon and applying a heat- treatment thereto. CONSTITUTION:When P ions are implanted to the PSG 2 coated with resist-mask 3, these are also implanted in the lateral direction. By means of a plasma etching in CF4 gas, a vertical window S can be formed. By removing the mask 3 and applying heat-treatment in the N2 at the temperature of 950 deg.C, the portion with high concentration of P is softened so that the peripheral part with a gentle inclination is formed. The softening temperature depends upon the amount of implanted P ions. With such an arrangement, the disconnection of wiring can be prevented and a semiconductor device with improved properties can be obtained, without exposing the formed gate oxidized film to such a high temperature as 950 deg.C. |
