Fabrication of Nb/Al/AlOx/Al/Nb Josephson tunnel junctions by reactive ion etching with SF6

Adelerhof, D.J. and Bijlsma, M.E. and Fransen, P.B.M. and Weiman, T. and Flokstra, J. and Rogalla, H. (1993) Fabrication of Nb/Al/AlOx/Al/Nb Josephson tunnel junctions by reactive ion etching with SF6. Physica C: Superconductivity, 209 (4). pp. 477-485. ISSN 0921-4534

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Abstract:	High quality Nb/Al,AlOx/Al/Nb Josephson tunnel junctions have been made with the help of a fabrication process based on reactive ion etching of Nb in SF6. The Vm value of these junctions is typically 60–70 mV at 4.2 K. At 1.6 K, a Vm of 4.1 V has been measured, which is the highest value that has ever been reported for this type of junction. The area of the junctions ranges from 1 to 25 μm2. By burying the Nb/Al,AlOx/Al/Nb trilayer in the substrate, a planarized junction configuration has been obtained. Reactive ion etching of Nb in SF6 plasmas has been studied in detail. Anisotropic etch profiles can be obtained because of the formation of a resistant layer during etching, which prevents etching of Nb under the photoresist. The etching process has been monitored with a spectrometer. The fluorine emission at 703.7 nm is shown to be suitable for end point detection.
Item Type:	Article
Copyright:	© 1993 Elsevier Science
Faculty:	Science and Technology (TNW)
Research Group:	Low Temperatures - Biomagnetism (LT)
Link to this item:	http://purl.utwente.nl/publications/23807
Official URL:	http://dx.doi.org/10.1016/0921-4534(93)90563-6
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