Minimizing Film Stress and Degradation in Thin-Film Niobium Superconducting Cables

2017 ◽  
Vol 2017 (DPC) ◽  
pp. 1-25
Author(s):  
Vaibhav Gupta ◽  
John A. Sellers ◽  
Charles D. Ellis ◽  
Bhargav Yelamanchili ◽  
Simin Zou ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Transition Temperature ◽  
Critical Current ◽  
Vital Role ◽  
Curing Temperature ◽  
Film Stress ◽  
Superconducting Properties ◽  
Al Thin Film ◽  
Superconducting Cables

The future of superconducting and cryogenic electronic systems can significantly benefit from densely integrated superconducting multi-layer and multi-signal flexible cables due to the massive number of electrical interconnects needed in systems such as superconducting quantum computers and cryogenic detector arrays. In order to maintain superconductivity in niobium (Nb) thin films, film stress and degradation must be minimized. We are working towards configurations with embedded traces, where it is expected that the superconductor material will be subjected to subsequent fabrication steps that must not degrade the properties of the superconductor. We previously observed degradation of the superconducting properties of Nb, such as reduction of both transition temperature and critical current, as a result of curing a polyimide passivation layer at supplier recommended curing temperature (350 oC). The deterioration in the superconducting properties may be due to mechanical stress in the film or diffusion of impurities into the Nb during the curing process Film stress plays a vital role in the superconducting properties of Nb. Previous research by other groups has focused on in situ ion bombardment, substrate fixturing and wafer preparation in order to minimize film stress. In this work, we discuss the role of argon (Ar) pressure and power during Nb sputtering on the quality of Nb and Nb/Al thin films. By varying the Ar pressure and applied power during sputter deposition, we have produced both tensile and compressive films on flexible substrates in order to find the pressure that yields a near zero stress Nb and Nb/Al thin film at room temperature. A low stress Nb film was tested with a thin Al barrier layer (of the order of 10's of nm) between Nb and polyimide to protect the Nb superconductivity during the PI curing step. Nb traces with a thickness of roughly 250nm and a width of 50um were used for this work. Nb films deposited at different Ar pressures and power levels were tested for critical transition temperature (Tc), critical current (Ic), and sheet resistance (Ω/□), to compare the superconducting behavior of different Nb films. Details of the fabrication processes, experimental procedures and performance results will be presented. This work will help determine materials stacks-ups that may be useful for future multi-layer Nb-based flexible superconducting cables. Acknowledgment: We gratefully acknowledge financial support and technical guidance from Microsoft Research for this work.

Microstructural characterization of YBa2Cu3O7-x thin films formed by metalorganic CVD

1991 ◽  
Vol 49 ◽  
pp. 1080-1081
Author(s):  
P. Lu ◽  
W. Huang ◽  
C.S. Chern ◽  
Y.Q. Li ◽  
J. Zhao ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Film Growth ◽  
Chemical Vapor ◽  
Microstructural Characterization ◽  
Ion Milling ◽  
Conventional Grinding

The YBa2Cu3O7-x thin films formed by metalorganic chemical vapor deposition(MOCVD) have been reported to have excellent superconducting properties including a sharp zero resistance transition temperature (Tc) of 89 K and a high critical current density of 2.3x106 A/cm2 or higher. The origin of the high critical current in the thin film compared to bulk materials is attributed to its structural properties such as orientation, grain boundaries and defects on the scale of the coherent length. In this report, we present microstructural aspects of the thin films deposited on the (100) LaAlO3 substrate, which process the highest critical current density.Details of the thin film growth process have been reported elsewhere. The thin films were examined in both planar and cross-section view by electron microscopy. TEM sample preparation was carried out using conventional grinding, dimpling and ion milling techniques. Special care was taken to avoid exposure of the thin films to water during the preparation processes.

Microstructure Engineering of Binary Alloy Thin Films through Monte Carlo Simulation of Pt/Al Thin-film Precipitate-evolution

2015 ◽  
Vol 2 (7) ◽  
pp. 4100-4110
Author(s):  
Richard Harris ◽  
Jacobus Terblans ◽  
Hendrik Swart
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Binary Alloy ◽  
Al Thin Film ◽  
Precipitate Evolution

Large Area Uniform Deposition of YBa2Cu3O7 Thin Films by a 90° Off-axis Sputtering Technique

1995 ◽  
Vol 401 ◽  
Author(s):  
R. A. Rao ◽  
Q. Gan ◽  
C. B. Eom
Keyword(s):  
Thin Films ◽  
Transition Temperature ◽  
Uniform Thickness ◽  
Superconducting Properties ◽  
Large Area ◽  
Substrate Rotation ◽  
Single Target ◽  
High Transition ◽  
Substrate Position ◽  
Uniform Deposition

AbstractLarge area uniform deposition of Yba2Cu3O7 (YBCO) thin films on 8 inch diameter wafers, using a 3 inch diameter sputtering target and optimized substrate rotation in a single target 90° off-axis sputtering technique, is reported. The variation in thickness, composition and superconducting properties was studied as a function of substrate position on stationary and rotating substrates. The films deposited from a 3” target on rotating substrates displayed uniform thickness (< ±5% variation) and composition (< 2.3% deviation from target stoichiometry) and a consistently high transition temperature ( Tc > 88.3°K) over an 8” diameter area.

scholarly journals Structural and Electrical Comparison of Si and Zr Doped Hafnium Oxide Thin Films and Integrated FeFETs Utilizing Transmission Kikuchi Diffraction

Nanomaterials ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 384 ◽  
Author(s):  
Maximilian Lederer ◽  
Thomas Kämpfe ◽  
Norman Vogel ◽  
Dirk Utess ◽  
Beate Volkmann ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Hafnium Oxide ◽  
Orthorhombic Phase ◽  
Vital Role ◽  
Silicon On Insulator ◽  
Oxide Semiconductor ◽  
Electrical Measurements ◽  
Fully Depleted ◽  
Scanning Transmission

The microstructure of ferroelectric hafnium oxide plays a vital role for its application, e.g., non-volatile memories. In this study, transmission Kikuchi diffraction and scanning transmission electron microscopy STEM techniques are used to compare the crystallographic phase and orientation of Si and Zr doped HfO2 thin films as well as integrated in a 22 nm fully-depleted silicon-on-insulator (FDSOI) ferroelectric field effect transistor (FeFET). Both HfO2 films showed a predominately orthorhombic phase in accordance with electrical measurements and X-ray diffraction XRD data. Furthermore, a stronger texture is found for the microstructure of the Si doped HfO2 (HSO) thin film, which is attributed to stress conditions inside the film stack during crystallization. For the HSO thin film fabricated in a metal-oxide-semiconductor (MOS) like structure, a different microstructure, with no apparent texture as well as a different fraction of orthorhombic phase is observed. The 22 nm FDSOI FeFET showed an orthorhombic phase for the HSO layer, as well as an out-of-plane texture of the [111]-axis, which is preferable for the application as non-volatile memory.

scholarly journals Superconducting properties of very high quality NbN thin films grown by pulsed laser deposition

2019 ◽  
Vol 70 (7) ◽  
pp. 89-94
Author(s):  
Serhii Volkov ◽  
Maros Gregor ◽  
Tomas Roch ◽  
Leonid Satrapinskyy ◽  
Branislav Grančič ◽  
...  
Keyword(s):  
Thin Films ◽  
Transition Temperature ◽  
Superconducting Transition Temperature ◽  
Pulsed Laser ◽  
Domain Size ◽  
Superconducting Transition ◽  
Superconducting Properties ◽  
Si Substrate ◽  
Coherent Domain Size ◽  
Coherent Domain

Abstract In this work, we study the effect of the various substrates on the growth and superconducting properties of NbN thin films grown by using pulsed laser ablation in a N2 + 1%H2 atmosphere on MgO, Al2O3 and Si substrates. Structural and superconducting analyses of the films demonstrate that using MgO and Al2O3 substrates can significantly improve the film properties compared to Si substrate. The X-ray diffraction data indicate that MgO and Al2O3 substrates produce highly oriented superconducting NbN films with large coherent domain size in the out-of plane direction on the order of layer thickness and with a superconducting transition temperature of 13.1 K and 15.2 K, respectively. On the other hand, the NbN film grown on the Si substrate exhibits random polycrystalline orientation. Together with the smallest coherent domain size it leads to the lower critical temperature of 8.3 K. Finally, by using a passivation surface layer we are able to improve superconducting properties of NbN thin film and we observe superconducting transition temperature 16.6 K, the one of the highest value reported so far for 50 nm thick NbN film on sapphire.

A Comparison of Electromigration in Bulk and Thin - Film Aluminum

1995 ◽  
Vol 391 ◽  
Author(s):  
Anthony S. Oates
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Grain Size ◽  
Grain Boundaries ◽  
Drift Velocity ◽  
Integrated Circuit ◽  
Transport Mechanism ◽  
Dominant Mode ◽  
Velocity Data ◽  
Al Thin Film

AbstractThe dominant mode of electromigration in polycrystalline Al thin - film conductors is along grain boundaries when the conductor width is significantly larger than the grain size. Integrated circuit feature sizes, however, have now decreased to the point where microstructures are no longer polycrystalline, but are near - bamboo. Electromigration must operate along pathways other than grain boundaries in the bamboo segments. Here drift velocity data is presented for bamboo microstructures with widths down to 0.6 μm and compared with drift data available in the literature for thin films with a variety of microstructures and bulk Al. Bamboo films show lower drift velocities and higher activation energies for drift than polycrystalline films. The data for bamboo microstructures is consistent with drift measurements performed on bulk Al indicating that the transport mechanism in bamboo films is identical to that in bulk Al.

Resistivity measurement of an a-axis-oriented YBa2Cu3O7–δ thin film at 450-650 °C

1993 ◽  
Vol 8 (4) ◽  
pp. 705-708 ◽  
Author(s):  
Toshio Usui ◽  
Akira Oishi ◽  
Hidekazu Teshima ◽  
Kazumi Ohata ◽  
Tadataka Morishita
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Ybco Film ◽  
Resistivity Measurement ◽  
Ambient Atmosphere ◽  
Reversible Change ◽  
Superconducting Properties ◽  
Ybco Thin Film

Resistivity measurement of an a-axis-oriented YBa2Cu3O7-δ (YBCO) thin film was carried out in a stream of O2/Ar mixtures at 450–650 °C. Rapidly reversible change in the resistivity of the YBCO film was observed as a function of the oxygen partial pressure in the ambient atmosphere due to the oxygen in-/out-diffusion in the YBCO film. Resistivity measurement of YBCO thin films at higher temperatures of 450–650 °C was found to be quite effective to predict the influence of fabricating processes on the superconducting properties of YBCO films.

Ion-Irradiation Effects in Tl2Ca2Ba2Cu3010 Superconductors

1989 ◽  
Vol 169 ◽  
Author(s):  
J. C. Barbour ◽  
J. F. Kwak ◽  
E. L. Venturini ◽  
D. S. Ginley ◽  
P. S. Peercy
Keyword(s):  
Thin Films ◽  
Transition Temperature ◽  
Ion Irradiation ◽  
Superconducting Properties ◽  
Irradiation Effects ◽  
Atomic Collisions ◽  
Dominant Mechanism ◽  
Resistivity Measurements ◽  
Helium Ion ◽  
Deposited Energy

AbstractThe effects of oxygen and helium ion irradiation on the superconducting properties of Tl2Ca2Ba2Cu3010 thin films were investigated. The transition temperature and width were monitored as a function of ion fluence using both magnetization and resistivity measurements. These data suggest that superconductivity is completely suppressed at 0.020 dpa for both He and 0 ion irradiation. Further, the rate of decrease in Tc as a function of deposited energy showed that the dominant mechanism causing damage-induced suppression of Tc in these films was from atomic collisions.

Effect of Pb Content on the Transformation of Sputtered PbxZr0.4Ti0.6O3 Thin Film

1993 ◽  
Vol 321 ◽  
Author(s):  
Jae-Hyun Joo ◽  
Deok-Sin Kill ◽  
Seung-Ki Joo
Keyword(s):  
Thin Film ◽  
Crystal Structure ◽  
Thin Films ◽  
Transition Temperature ◽  
Temperature Region ◽  
Transformation Temperature ◽  
Perovskite Phase ◽  
Effective Medium Approximation ◽  
Transformation Kinetics ◽  
Pzt Films

ABSTRACTPZT (PbxZr0.4Ti0.6O3) thin films were prepared by reactive co-sputtering and annealed by RTA (Rapid Thermal Annealing). Transformation kinetics and effect of Pb content on the transformation were intensively studied using EMA (Effective Medium Approximation). It has been found that depending on Pb content as well as RTA temperature, the crystal structure of PZT films changed greatly. It turned out that the transformation temperature for the perovskite phase can be lowered and the width of transition temperature region was reduced by increasing Pb content in the films. Dependence of transformation path on the Pb content has been studied.

Identification of the Failure Mechanism of a Thin Film on a Thick Substrate by Means of Synchrotron X-Ray Topography Combined with Transmission Electron Microscopy

1987 ◽  
Vol 108 ◽  
Author(s):  
D. Goyal ◽  
W. Ng ◽  
A. H. King ◽  
J. C. Bilello
Keyword(s):  
Thin Film ◽  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Film Thickness ◽  
Film Stress ◽  
Silicon Substrates ◽  
X Ray ◽  
Transmission Electron ◽  
Thick Substrate

ABSTRACTWe have used synchrotron x-ray topographic techniques to study the stresses in thin films formed upon silicon substrates either by evaporation or sputtering. It is found that the film stress generally decreases with increasing film thickness for evaporated films, but film delamination occurs at a well defined film thickness. Transmission electron microscope studies have been performed on the same specimens in order to reveal what mechanisms are involved with the delamination of the films.

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