| 摘要 |
PURPOSE:To reduce over-etching through high speed etching of a film to be processed existing at the stepped part by diffusing impurity to the film to be processed formed at the stepped part. CONSTITUTION:A phosphor silicate glass (PSG) film 11 is deposited on a poly Si film 6 formed on a field oxide film 3 comprising the stepped part on an Si substrate 4. Then, when a PSG film 11 is etched, the PSG film 11 remains only at the side wall of stepped part of film 6. Next, phosphorus is diffused into the film 6 from the PSG film 11. Thereby, the phosphorus doped Si 12 is formed at the stepped part of film 6. The film 6 is then selectively etched through formation of resist in the desired pattern. At this time, an etching rate of Si 12 at the stepped part is faster several times than that of the non-doped film 6. Therefore, the Si 12 can be removed perfectly even if an excessive over-etching is not carried out. Accordingly, characteristic of transistor element is not deteriorated and accuracy of wiring pattern is not also degraded. |
