| 摘要 |
PURPOSE:To prevent the generation of the residue of etching and stepped difference by forming a section to a trapezoid by utilizing the generation of the difference of etching rates by the difference of impurity concentration. CONSTITUTION:When a polycrystalline silicon film, impurity concentration therein is low in an upper section and high in a lower section, is patterned through anisotropic etching, a polycrystalline silicon film of an approximately vertical section is formed, and the extremely high accuracy of finishing is obtained. When oxidizing the surface, a silicon oxide film 8 acquired is thinned in an upper section and thickened in a lower section because the higher impurity concentration is, the higher the speed of oxidation becomes. The section of a polycrystalline silicon film 3'' takes an inverted trapezoid, but the section takes a trapezoid as a whole, there is hardly a danger of the generation of disconnection even when wiring is formed on the section so as to cross the section, and the high accuracy of finishing through anisotropic etching and the prevention of disconnection by the trapezoid section are attained simultaneously. |
