| 摘要 |
PURPOSE:To inhibit the conversion difference of a pattern by a method wherein an inversion mask is formed, an oxide thick film is partially etched in an isotropic shape, the breaking of wiring of a stage difference section is prevented, anisotropic ethcing is conducted by the same mask and the remaining oxide film is removed. CONSTITUTION:The oxide thick film 22 and poly Si 23 are stacked on a P type Si substrate 21, a Si3N4 mask 24 is shaped, B ions 25 are implanted and an inversion preventive layer is formed. The poly Si 23 is oxized selectively, and SiO2 26 is shaped. The Si3N4 24 is removed and the poly Si 23 is etched using the SiO2 26 as a mask. When one part of the SiO2 22 is etched in the isotropic shape with NH4F while employing the film 23 as the inversion mask, the eave section of the film 23 is formed. When the remaining SiO2 22 is etched in the isotropic shape by reactive ions by using CF4+H2 by the same mask 23, etching advances vertically to the substrate. When the poly Si 23 is removed, the stage difference angular section 27 of the oxide thick film 22 can be etched without increasing the conversion difference of the pattern, the breaking of wiring at stages is prevented, and yield is improved. |
