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Electronic devices based on the high-temperature superconductor (YBCO) may deteriorate in the operating environment under the influence of moisture, atmospheric carbon dioxide and frequent thermal cycling. To avoid these impairments a passivation layer was developed which is deposited by polymerization of the silicon organic compound hexamethyldisilasane (HMDS-N) in a plasma enhanced chemical vapour deposition (PECVD) process. The 100 nm thin films exhibit excellent passivation properties which is confirmed by electrical transport measurements of passivated wide and 100 nm high YBCO lines and step edge Josephson junctions exposed to humidity and . No degradation in the critical parameters such as the critical current , the normal resistance and the flux-voltage modulation depth is observed on step edge dc-SQUIDs owing to the deposition of the passivation layer. Atomic force microscope (AFM) measurements show a smooth morphology of these layers without pinholes and an excellent coverage of the YBCO even at the edges of lines. Furthermore, the passivation layer can be used as an isolation and scratch protection between SQUIDs and thin-film flux transformers in flip-chip magnetometers.

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