Superconducting NbTin Thin Films with Highly Uniform Properties over a ∅ 100 mm Wafer

David Johannes Thoen, Boy Gustaaf Cornelis Bos, E.A.F. Haalebos, T.M. Klapwijk, J.J.A. Baselmans, Akira Endo

Research output: Contribution to journalArticleScientificpeer-review

16 Citations (Scopus)

Abstract

Uniformity in thickness and electronic properties of superconducting niobium titanium nitride (NbTiN) thin films is a critical issue for upscaling superconducting electronics, such as microwave kinetic inductance detectors for submillimeter wave astronomy. In this article we make an experimental comparison between the uniformity of NbTiN thin films produced by two DC magnetron sputtering systems with vastly different target sizes: the Nordiko 2000 equipped with a circular nothing 100 mm target, and the Evatec LLS801 with a rectangular target of 127 mm × 444.5 mm. In addition to the films deposited staticly in both systems, we have also deposited films in the LLS801 while shuttling the substrate in front of the target, with the aim of further enhancing the uniformity. Among these three setups, the LLS801 system with substrate shuttling has yielded the highest uniformity in film thickness (±2%), effective resistivity (decreasing by 5% from center to edge), and superconducting critical temperature (Tc = 15.0 K-15.3 K) over a ∅ 100 mm wafer. However, the shuttling appears to increase the resistivity by almost a factor of 2 compared to static deposition. Surface SEM inspections suggest that the shuttling could have induced a different mode of microstructural film growth.
Original languageEnglish
Article number1500505
Pages (from-to)1-5
Number of pages5
JournalIEEE Transactions on Applied Superconductivity
Volume27
Issue number4
DOIs
Publication statusPublished - 2017

Keywords

  • Kinetic inductance detectors
  • reactive sputtering
  • superconducting device fabrication
  • superconducting thin films

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