| 摘要 |
PURPOSE:To obtain preferable FET without contamination of damage of an Si substrate surface by forming a Ta2O5 region on the substrate, then forming electrodes on part of the Ta2O5 region, and forming the remaining Ta2O5 region with etching gas having large selection ratio of Ta2O5/SiO2. CONSTITUTION:A Ta2O5 film 9 is formed on a region surrounded by an element separating region 8 on an Si substrate 7. Then, after a W electrode 10 is formed on partial region on the film 9, it is heated in team including H2 gas to form an SiO2 film 11 on the boundary between the film 9 and the substrate 7. In this case, since W has a trend to be reduced by H2, it is not oxidized. Then, the Ta2O5 on the film 11 is removed by etching with gas such as CCl4 gas having large selection ratio of Ta2O5/SiO2. Subsequently, the film 11 is removed with etchant containing HF. Thus, the surface of the substrate 7 and the region 12 are exposed without damage nor contamination. Thereafter, the substrate 7 is oxidized to form a gate oxide film. Thus, an FET is obtained in high yield with simplified steps. |
