| 摘要 |
PURPOSE:To enable etching of Nb or T a metal in high reproducibility and controllability, by particularly reducing the mixing ratio of aqueous hydrogen peroxide to concentrated fluoric acid in a mixed solution of concentrated sulfuric acid, water, concentrated aqueous hydrogen peroxide and concentrated fluoric acid. CONSTITUTION:A metallic electrode containing Nb or Ta as main ingredients is etched by a solution obtained by mixing at volumetric ratio 30-50 of concentrated sulfuric acid, 45-65 of water, 0.2-3.0 of concentrated aqueous hydrogen peroxide and 1.0-5.0 of concentrated fluoric acid. By reducing the mixing ratio of the concentrated aqueous hydrogen peroxide and the concentrated fluoric acid particularly in this manner to suppress the etching rate of semiconductors, insulating films and metals other than Nb and Ta, Nb or Ta may be selectively etched in high reproducibility. If the solution temperature becomes lower than 0 deg.C the etching rate is abruptly decelerated, while if it becomes higher than 50 deg.C, uniform etching becomes impossible, and so it is preferred that the solution temperature is kept in the range of 0-50 deg.C. |
