| 摘要 |
PURPOSE:To form an upper layer electrode stably without leaving an electrode material in an unnecessary section by a method wherein the side surface of poly Si is oxidized, an oxide film is removed, residual poly Si is formed to a smooth sectional semicircular shape at a stepped section, an oxide film is shaped on the surface, and the upper layer electrode passing on the stepped section of lower-layer poly Si is formed. CONSTITUTION:The thin-films of SiO2 12 and Si3N4 13 and conductive poly Si 14 are superposed on a P-type Si substrate 11, a thermal oxide film 15 is shaped and Si3N4 16 is stacked. A resist mask 17 is executed, and the films 16-14 are removed through etching. When the resist 17 is taken away, the side surface of poly Si 14 is oxidized by the combustion of H and O at 800-900 deg.C and a poly Si oxide film 18 is shaped, even poly Si 14 in a section coated with Si3N4 16 is oxidized and a cross section is formed to a semicircular shape, and oxidation is completed in a short time. The oxide film 18 is removed through etching by a buffer HF liquid, and poly Si 14 and SiO2 15 at the top section of poly Si 14 are left. Si3N4 16, 13 and SiO2 12, 15 are removed through etching in succession, the surfaces are coated with SiO2 films 19, 20, and conductive poly Si 21 and Si3W2 22 are superposed. Since there is no stepped section, no residue is generated and no wiring is short-circuited when an upper layer electrode 23 is formed.
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