SUBSTRATE FOR ELEMENT FORMATION

PURPOSE:To enable to perform the patterning both with excellent dimensional accuracy and reproducibility by a method wherein GGG (Gd, Ga and Garnet) is used for a substrate, and an etching solution of fluoric type is used when an Nb Josephson junction element is manufactured. CONSTITUTION:In the element forming method wherein Nb is coated on the substrate of Si plus SiO2 structure which has heretofore been in use, the reproducibility thereof is poor because its finishing point of etching is indistinct when an etching of fluoric acd type is performed. The GGG substrate has an excellent etching resistance property for fluoric acid, and its finishing point of etching is distinct because it is transparent, and an overetching can be prevented completely. As the above substrate is an insulated one, the manufacturing process for the substrate can also be shortened.