Control of Etch Angle in NiobiumOriginal Publication Date: 1980-Aug-01Included in the Prior Art Database: 2005-Feb-13Niobium is used as a superconductor in many cryogenic devices. To create circuitry, etc., patterns are etched in niobium films using an etchant consisting of hydrofluoric acid, an oxidizing agent such as nitric acid, and water. Control of the etch angle - that is, the angle the etched surface makes with the substrate - is very important. Some times a steep angle is needed to sharply define close tolerance signal lines. On other layers, shallow angles are needed to provide better line edge coverage of subsequent layers of insulators, such as SiO and SiO(2).