| 摘要 |
PURPOSE:To enable to expose a semiconductor substrate by one time etching by a method wherein a silicon nitride film of oxidation-proof mask to be used when selective oxidation of the semiconductor substrate is pefromed is oxidized by the plasma anodic oxidation method. CONSTITUTION:The semiconductor substrate 1 is oxidized to form a silicon dioxide film 2 for buffer, and the Si nitride film 3 of the mask for oxidation- proof is formed thereon. At this time, the surface of the film 3 is also oxidized a little, and is converted into a silicon dioxide film 4. Then the film 3 is converted into a silicon dioxide film 6 completely by the plasma anodic oxidation method. At this time, Si of the substrate 1 and the film 3 can be oxidized with nearly the same speed. As a result, the film 3 is converted completely into the silicon dioxide film, and can be removed easily by performing etching using an etching liquid of fluoric acid. Accordingly the substrate 1 can be exposed by one time etching, and moreover judgement of the finishing point of etching can be made easily. |
