Selective silicon dioxide etchant for superconductor integrated circuits

摘要

This is an improved method for providing silicon dioxide with openings which expose contact pad areas for connections to superconductor in the preparation of superconducting integrated circuits. It relates to the type of method which utilizes depositing of a silicon dioxide film on a substrate (including over superconductor conductor patterns on the substrate surface), placing a resist film on the silicon dioxide film, patterning the resist film to expose portions of the silicon dioxide, and reactive ion etching the exposed portions of the silicon dioxide film to expose contact pad areas of superconductor. The improvement utilizes an etchant gas consisting essentially of 50-95 volume percent nitrogen trifluoride and 5-50 volume percent rare gas (preferably about 77 volume percent nitrogen trifluoride, with argon or neon or mixtures thereof as the rare gas) for the reactive ion etching of the exposed portions of the silicon dioxide film. Thus a carbon-containig etchant is not used and polymer by-products of the etching process are essentially completely avoided.