Investigation of TiN Seed Layers for RABiTS Architectures With a Single-Crystal-Like Out-of-Plane Texture (original) (raw)
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Influence of Surface Faceting of RABiT-Type Metallic Substrate on Epitaxial Film Growth
IEEE Transactions on Applied Superconductivity, 2018
Surface faceting is a well-known phenomenon occurring in either metallic or oxide materials. It is due to thermal etching favoured by high-temperature annealing in vacuum, and leads to the formation of steps or facets on the surface. The occurrence of surface faceting on cube-textured metallic substrates for YBCO coated conductor has been only seldom reported and its influence on the epitaxial growth of both buffer and superconducting layers has never been considered. In this paper, we studied the effect of the annealing conditions on the surface morphology of Ni-and Ni-Cu-based cube-textured metallic substrates and the influence of the obtained surface morphology on epitaxial film grown by both physical vapour and chemical solution deposition techniques. We confirm that annealing in reducing atmosphere suppresses both surface faceting and grain boundary grooving. Such a surface is beneficial for epitaxial film growth as it leads to smoother and featureless surfaces. On the other hand, from a microstructural point of view, film deposition on a faceted substrate shows a sharper orientation.
IEEE Transactions on Applied Superconductivity, 2000
MgO films are widely used as the first buffer layer in IBAD-YBCO coated conductors, whereas there are only a few examples of its use in RABiTS YBCO coated conductors. Nevertheless MgO, though challenging in terms of lattice parameter and epitaxy, can effectively passivate the metal substrate thus enabling the use of Ni-Cu-based alloy tapes. Such substrates develop a very sharp cube texture and at the same time can be safely handled when their thickness is as low as 40 . Epitaxial MgO films were deposited by e-beam evaporation at 400 on biaxially textured metal substrates. A transient Pd layer as thin as 10 nm was used to alleviate the lattice mismatch between MgO and the substrate and to enhance film adhesion. Due to the reduced diffusion of oxygen in MgO, this template is effective against substrate oxidation even in the extreme conditions typical of the YBCO growth. On such a template, (LSMO) was epitaxially deposited by PLD. Moreover, (BZO) film was successfully deposited by CSD on MgO single crystal and is expected to epitaxially grow also on MgO film. Index Terms-E-beam evaporation, MgO buffer layer, nickel-copper alloy tape, YBCO coated conductor.
Iridium: an oxygen diffusion barrier and a conductive seed Layer for RABiTS-based coated conductors
IEEE Transactions on Applied Superconductivity, 2005
For power applications of YBa 2 Cu 3 O 7 (YBCO) coated conductors, it is necessary to electrically stabilize the conductor. An economic way to achieve this, which also benefits the engineering E , is to grow conductive buffer layers directly on textured Cu or Ni metal surfaces. However, due to poor oxidation resistance and high reactivity/diffusivity of Cu or Ni, an insulating oxide layer usually forms at the metal/substrate interface, degrading the electrical connectivity of the entire architecture. To overcome this problem, we have developed a new conductive, nonmagnetic buffer layer architecture of La 0 7 Sr 0 3 MnO 3 Ir on textured Ni-based tapes. This structure serves as a barrier to both inward diffusion of oxygen and outward diffusion of metal cations. Using PLD to grow YBCO, we demonstrate ideal electrical coupling to the metal substrate. Critical current ( c ) values for 1 m thick YBCO coatings exceed 100 A/cm-width at 77 K on a Ni-W RABiTS template.
Physica C-superconductivity and Its Applications, 2002
Fabrication of a biaxially textured, strengthened Ni substrate with small alloying additions of W and Fe is reported. The substrates have significantly improved mechanical properties compared to 99.99% Ni and surface characteristics which are similar to that of 99.99% Ni substrates. High quality oxide buffer layers can be deposited on these substrates without the need for any additional surface modification steps. Grain boundary misorientation distributions obtained from the substrate show a predominant fraction of low-angle grain boundaries. A high critical current density, J c , of 1.9 MA/cm 2 at 77 K, self-field is demonstrated on this substrate using a multilayer configuration of YBCO/CeO 2 /YSZ/ Y 2 O 3 / Ni-3at.%W-1.7at.%Fe. This translates to a I c /width of 59 A/cm at 77 K and self-field. J c at 0.5 T is reduced by only 21% indicating strongly-linked grain boundaries in the YBCO film on this substrate.
MgO/TiN Buffer Layer Structures for Coated Conductor Development on Cu-based Substrates
IEEE Transactions on Applied Superconductivity, 2015
A MgO/TiN based multilayer structure suitable as buffer for the development of ReBa 2 Cu 3 O 7-x (RE = rare earth, Y)-based coated conductors has been developed. The epitaxial growth of TiN film on cube textured substrate was widely studied in terms of structural and morphological properties. TiN films were epitaxially grown on Ni-W substrates in a wide range of deposition condition. The TiN films are compact and dense with smooth surfaces. An MgO film deposited on the top of the TiN layer reproduces the characteristics of the underlying film. In order to test the TiN/MgO structure, a YBCO film was deposited using a SrTiO 3 film as cap layer. A Cu-based cube textured tape was employed as substrate, i.e., Ni-50%at. Cu-0.5%at. W. The YBCO film presents a major c-axis orientation with a sharp out-of-plane distribution. Zero-resistance critical temperature of about 85 K was obtained.
Development of cube textured Ni-W alloy substrates used for coated conductors
Journal of Physics: Conference Series, 2014
It is considered as a challenge for RABiTS route to get cube textured Ni-W alloy substrates with high mechanical and magnetic properties for coated conductors. The works of our group in recent years are summarized about different Ni-W substrates with high W content and composite tapes made by RABiTS technique. The fabrication process and the mechanism of cube texture formation in above different tapes are studied systematically. Compared with commercial Ni-5 at.%W substrate, these alloy substrates show a comparable texture quality and improved mechanical properties as well as reduced or zero magnetization especially in the novel composite substrates.
Microelectronic Engineering, 2008
ABSTRACT 3D integration is of high interest to overcome the future challenges that are to be met both by device interconnections and packaging. In between the challenges that are to be met to achieve this process is the via fill when making high aspect ratio vias and barrier and seed deposition layers deposition.In this paper, we showed that we were able to achieve a good continuity with a good conformality for barrier and seed layers in Aspect Ratio 10 vias, using respectively CVD TiN and eG ViaCoat™ Cu seed. The studied vias are 5 μm wide and 50 μm deep.We first demonstrated the continuity of the barrier by performing a HF-dip test on trenches structures and, after having run a DOE to optimize seed layer deposition recipe, we did some early test of via fill to assess the continuity of the barrier/seed stack.
Atomic layer deposition for high aspect ratio through silicon vias
Microelectronic Engineering, 2013
The paper presents atomic layer deposition (ALD) processes and process integration for the deposition of insulating liners, copper diffusion barriers, and seed layers for direct copper plating in high aspect ratio (>20:1) through silicon vias. A TaN-based copper diffusion barrier was deployed on an aluminum oxide insulating liner. The latter has the potential to act also as a dielectric barrier against copper diffusion according to BTS and TVS measurements. Furthermore, ruthenium ALD films applied as seed layers for direct copper plating were deposited with an intermediate annealing step to improve film adhesion and ensure the deposition of thick films without any delamination. The step coverage of the presented ALD processes was confirmed by SEM measurements on cross-sections of coated TSV structures. Finally a subsequent electrochemical deposition (ECD) of copper was conducted revealing the satisfying functionality of the Ru seed layer.
Development of 100% lattice match buffer layers on RABiTS Ni tapes by sol-gel
IEEE Transactions on Applied Superconductivity, 2003
Gd 2 O 3 -Yb 2 O 3 and Gd 2 O 3 -Ho 2 O 3 mixed RE oxides were used to produce buffer layers with a perfect lattice match with superconducting layer. Since these RE oxides are 100% miscible in each other, pseudocubic lattice parameter of the buffer layers can be modified by changing the ratio of components to perfectly match with any superconducting RE-123. Texture and the microstructure of the buffer layers were studied by XRD, Pole Figure and ESEM.
Development of Composite RABiTS Tapes for Coated Conductors
IEEE Transactions on Applied Superconductivity, 2015
Substrate materials are the key element of the coated conductors. There are two types of substrates-nontextured (stainless steel (SS) or Hastelloy alloys) and textured ones which are based on the Ni-W alloys. The main requirements for the textured tapes (RABiTS) are the presence of the highly pronounced biaxial cubic texture {100} < 100 > and low values of magnetic susceptibility. To realize these requirements RABiTS tapes of various kinds were developed-homogenous tapes from Ni-W alloys with W content 5.5-9 at.% and composite ones. Composite tapes consist of three layers-one of SS and two of Ni-W alloy with W content 6 at.%. Mechanical and magnetic properties of the tapes were investigated and the dependence of tapes texture quality from total accumulated deformations was studied. The ultimate tensile strength value of composite tapes was 750 ± 10 MPa. The conditions necessary to form the required {100} < 100 > texture are different for the homogeneous and composite tapes. According to the magnetic measurements saturation magnetization of composite tapes is about a factor of two lower than for similar homogeneous tapes.