Methods and Apparatus for Metallic and Ceramic Nanocoatings for Accident Tolerant Nuclear Fuel, Particle Accelerators, and Aerospace Frontiers

Abstract

A system is described that includes: a sputtering target; an array of magnetic elements including multiple sets of magnets, the multiple sets of magnets being arranged to have a Hall effect region extending along the length of the sputtering target. An elongated tube of sputtering electrode material is interposed between the magnetic array and an object on which sputtering material from the sputtering target is to be deposited. During a direct current high-power impulse magnetron sputtering operation, the system is configured to perform deposition on the surface of the object by generating and controlling an ion and neutral particle flux in the following manner: providing a vacuum apparatus that includes a sputtering target holding electrode; first generating a high-power pulsed plasma magnetron discharge having a high-current negative direct current (DC) pulse to the sputtering target holding electrode; and second generating a configurable positive voltage jump pulse to the sputtering target holding electrode after termination of the negative DC pulse.

Description

[0001] Cross - reference to related applications

[0002] This application is a non - provisional application of U.S. Provisional Patent Application No. 62 / 810,230, filed on February 25, 2019, entitled "Methods and Apparatus for Metallic and Ceramic Coatings for Accident - Tolerant Nuclear Fuel", the entire content of which (including any references contained therein) is incorporated herein by reference.

[0003] This application relates to U.S. Non - Provisional Patent Application Serial No. 15 / 803,320, filed on November 3, 2017, entitled "Compact System for Directly Coupling RF Power into an RF Linear Accelerator", the entire content of which (including any references contained therein) is incorporated herein by reference.

[0004] This application relates to U.S. Non - Provisional Patent Application Serial No. 16 / 006,357, filed on June 12, 2018, entitled "Pulsed Power Module with Magnetron Sputtering and Pulsed and Ion Flux Control", the entire content of which (including any references contained therein) is incorporated herein by reference. Technical Field

[0005] The present disclosure generally relates to processes and apparatus for achieving durable high - strength / adhesive coatings. More particularly, the present disclosure relates to improved apparatus and processes for fabricating / forming coatings resistant to high - temperature oxidation for nuclear and aerospace applications. Background Art

[0006] There is a need for scalable manufacturing technologies for high - quality coatings for ATF nuclear fuel to provide: (1) enhanced safety under accident conditions within and outside the design basis (> 1200 °C), (2) provide better performance to be able to generate higher linear heat (> 7 kW / ft, > 20% upgrade) during baseline operation to be able to generate more energy from existing nuclear power plants, (3) be able to achieve higher fuel burn - up (> 80 MWd / kg U) with fewer fuel replacements, (4) low cost ($ + 30 / clad), (5) integration into existing production lines, inspection, and verification.

[0007] Westinghouse The fuel project is characterized by a set of short, medium, and long - term transformations to provide enhanced accident tolerance and improved fuel economy. Directly applied to Cold-sprayed Cr on [the object] is a favorable short-term insertion point (>2020). A complete change for SiC / SiCf cladding is a favorable long-term (>2030) transition point; however, SiC may be delayed due to high manufacturing costs and conventional challenges. There is a mid-term insertion possibility for new manufacturing technologies, which can provide superior Zr-based ATF solutions, and the synergy with SIC is ongoing. Additionally, there is an opportunity to directly apply thin film coatings to the fuel core to improve the margin of core-cladding interaction, reduce cleaning in the case of fuel rod leakage, and reduce fission gas release in transient scenarios.

[0008] The described technical approach is based on high-volume manufacturing methods for nano-layer erosion and fracture-resistant coatings, where high-power impulse magnetron sputtering (HiPIMS) with recent innovations is used. Xinghuo Industry's Positive Jump TM technology (patent pending) provides a way to increase deposition rate, adjust coating micro / macro structure, modify film stress, and control morphology. The manufacturing technology is suitable for coating ATF LWR claddings and pellets, and fast reactor fuels. Both metals and ceramics can be precisely deposited with good adhesion, graded composite nanostructures and laminates, radiation hardness, thermal shock resistance, and oxidation resistance.

[0009] The short-term path is to apply thin (<50μm) coatings to existing Zr fuel claddings and fuel cores to achieve improved accident tolerance and performance. Excellent summaries can be found in: Technical Status Report on Accident Tolerant Fuels for Light Water Reactors (OECD 2018, NEA 7317) and Light Water Reactor Durability Project Report (INL / EXT-12-27090).

[0010] The bottom-line constraint is to prevent coolant-cladding chemical interaction at low manufacturing costs with a negligible impact on neutron economy and thermal conductivity under normal or design basis accident conditions. The problems are to prevent coating delamination and improve the tolerance to bulging and bursting (creep), which are temperature-related and depend on internal stress, crack initiation sites, and microstructure release to prevent warping and film separation. Once the oxidation barrier is damaged, the underlying Zr will be eroded and lead to failure; therefore, engineering the coating to manage fracture (prevent crack formation and growth) and warping (film stress) is crucial for ATF cladding design. Fracture toughness is related to microstructure, inherent material properties, and the initial effective geometric defect radius of cracks:

[0011]

[0012] The smaller the effective defect length scale (a defectsize ) is, the higher the material fracture strength and resistance to thermal shock, swelling, and bulging. Additionally, grain boundaries / defect surfaces act as transport paths for accelerating internal oxidation (resulting in oxide stress and coating fragmentation); controlling them is key.

[0013] Thermal and environmental barrier coatings have been deposited in the past by sol-gel, electrophoretic deposition (EP), hot pressing, thermal plasma spraying, high-velocity cold spraying (CS), laser sintering, and physical vapor deposition (PVD). To not affect the overall cladding strength and microstructure below, all high-temperature processes are excluded to maintain conventional compliance and the long-term effects known under irradiation. Low-temperature processes (e.g., EP, CS, PVD) are favorable ways. However, each technique is basically limited by the defect length scale from intrinsic to technological. Electrophoretic deposition and cold spraying examples can present an "effective defect size" (on the order of.5 - 2 μm). Westinghouse performed lead test rod exposures for CS deposition of Cr on 9.5 mm for short-term ATF introduction.

[0014] In contrast, magnetron sputtering and cathode arc-based PVD are vacuum-based and grow films "atom by atom" through nucleation and energy ejection processes. The film quality is high, and both cermets can be deposited. However, the coating speed and cost are constraints. Compared with conventional cold spraying, such an approach can achieve a fracture toughness improvement of about 3.3 times (where the defect length scale is reduced). High-temperature vapor testing confirmed excellent oxidation resistance up to 1200 °C and minimal weight gain (from the dense Cr2O3 barrier) - exceeding EP and CS technologies.

[0015] The improved quality has led to further attention to PVD processing to provide greater ion energy to the surface to achieve greater adhesion and further improve the film microstructure using HiPIMS. See Wu, Journal of Nuclear Materials 504 (2018) 289 - 299. Areva (France) disclosed the results of using a metallic Cr coating on M5 alloy, showing a dense microstructure. See Bischoff, Nuclear Engineering and Technology, 50, (2018) 223 - 228. HiPIMS can be a low-temperature process, not modifying the microstructure of the underlying Zr substrate and forming a pore-free dense layer at the Cr-Zr interface. The oxidation resistance and high-temperature creep performance above 1200 °C are improved, indicating that PVD is promising for recent ATF solutions.

[0016] The advantages of PVD are as follows: During the deposition process, materials can be combined to functionally grade parameters (such as CTE) or form composite structures for stress control, crack prevention, hoop stress release, and erosion stopping. Westinghouse collaborated with researchers at the University of Pennsylvania to use a cathodic arc to produce 8 - 16 layers of TiN / TiAlN coatings approximately 1 μm thick. Erosion detection was successfully passed (autoclave for 90 days, 360 °C, 18.7 MPa). No cracks or delamination / fracture were observed, indicating good erosion resistance, where thin nitride layers are required to prevent Al migration and boehmite formation. However, the intrusion of macro particles (with defect sizes of approximately 0.5 - 2 μm) from the cathodic arc process is a problem at high temperatures. Lamination provides improvement, but the effectiveness is limited by the macro particle size - similar to cold spraying. Summary of the Invention

[0017] An exemplary example of a system is provided herein, including: a sputtering target; an array of magnetic elements including multiple sets of magnets arranged to have a Hall effect region extending along the length of the sputtering target. An elongated sputtering electrode material tube is interposed between the magnetic array and an object on which sputtering material from the sputtering target is to be deposited. During direct current high - power impulse magnetron sputtering operation, the system is configured to perform deposition on the surface of the object by generating and controlling ion and neutral particle fluxes in the following manner: providing a vacuum apparatus including a sputtering target holding electrode; first generating a high - power pulsed plasma magnetron discharge having a high - current negative direct current (DC) pulse to the sputtering target holding electrode; and after terminating the negative DC pulse, second generating a configurable positive voltage jump pulse to the sputtering target holding electrode. Brief Description of the Drawings

[0018] Although the aspects of the present invention are set forth in specific terms in the appended claims, the invention, and its advantages, are best understood from the following detailed description in conjunction with the accompanying drawings, in which:

[0019] Figure 1 Exemplary illustrations show an inverted - cylinder magnetron plasma deposition and etching system using magnetron sputtering;

[0020] Figure 2A and 2B Exemplary illustrations show a basic planar magnetron of the prior art, an inverted - cylinder magnetron with a single - anode configuration, and a column cathode configuration for sputtering;

[0021] Figure 3A and 3B Illustrations show prior - art structures for an inverted - cylinder magnetron configuration;

[0022] Figure 4In cross-section, an illustrative view shows details of one aspect of an illustrative example of the present disclosure, which is for providing high target utility and sputter re-capture on the side opposite the ICM target region;

[0023] Figure 5 An illustrative view shows the construction of an inverted cylinder magnetron, where the target electrode includes sections that can be easily fabricated and joined together to form a quasi-cylindrical shape;

[0024] Figure 6A and 6B An illustrative view shows another aspect of the present disclosure, where a radial magnetic field is used to establish a magnetron effect and an electron Hall effect transport for plasma formation, and also to form a magnetic null point for the plasma at the center of the inverted cylinder magnetron;

[0025] Figure 7 An illustrative cross-sectional side view of an example of the present disclosure shows that the magnetic field is concentrated near the sidewall of the target electrode and is minimized at the centerline;

[0026] Figure 8 An illustrative view shows an improved plasma confinement and power application according to the present disclosure, which is achieved by utilizing electron reflection energy transport to enhance on-axis ionization and plasma generation;

[0027] Figure 9 An illustrative view shows an inverted cylinder magnetron processing module having a central feed substrate passing along the axis, highlighting a 360-degree coating process and sputter re-capture applications;

[0028] Figure 10 An illustrative view shows one aspect of the present disclosure, where magnetic tips are applied to guide low-temperature plasma to the centerline to obtain a high proportion of captured ions from the bipolar well to the substrate;

[0029] Figure 11 An illustrative view shows an example of using a single continuous meandering magnetron path that extends along the target electrode, such as a path in the shape of a Greek palindrome;

[0030] Figure 12 A more detailed illustrative view shows a magnetic package geometry that facilitates a meandering magnetron path (which will generate a B field);

[0031] Figure 13 shows an illustrative view of an example of the present disclosure, where there is one or more (shown here as 3) circular, rectangular, or other continuous loops for generating a magnetic field on the target electrode;

[0032] Figure 14A and 14B An illustrative view shows a structure that facilitates rotation of the magnetic assembly about the central axis or physical rotation of the target electrode to move the dense plasma sputtering zone and target erosion along an inverted cylinder magnetron sputtering system;

[0033] Figure 15A and 15B The exemplary illustration shows the disadvantages of conventional HiPIMS sputtering;

[0034] Figure 16A and 16B The exemplary illustration shows a cross-sectional solid model and a cross-sectional view, showing an example of the inverted cylinder magnetron structure disclosed herein;

[0035] Figure 17 The exemplary illustration shows a view, showing that a compact connection is feasible, where a multi-tip magnetic geometry is used to generate a dense plasma region for sputtering near the target electrode, while at the same time generating a strong secondary plasma near the center line for substrate immersion;

[0036] Figure 18A 、 18B 、Example 18C shows an example of ultrafast high-power pulsed sputtering and subsequent rapid plasma potential reversal to direct and capture a higher proportion of sputtered ions for conformal deposition on a substrate;

[0037] Figure 19A and 19B The exemplary illustration shows the advantage of a short burst pulse, which accelerates ions from a dense plasma region near the sputtering target and then deposits based on the adjustable energy imparted to the ions;

[0038] Figure 20 Highlighting the difference between the impulse + positive burst and the prior art power supply signal;

[0039] Figure 21 The exemplary illustration shows ultrafast high-power impulse magnetron sputtering and the potential distribution between the sputtering target and the substrate;

[0040] Figure 22 The exemplary illustration shows the evolution of ultrafast switching on the target electrode and the reversal of the positive voltage to a positive voltage and the potential distribution in the magnetic confinement region near the target electrode;

[0041] Figure 23 The exemplary illustration shows the evolution of the positive potential to a long burst phase, where the overall plasma potential increases and a conformal sheath forms on the substrate and other surfaces when the overall plasma makes a round trip;

[0042] Figure 24 The exemplary illustration shows an aspect of the present disclosure, where the substrate is treated with impulse + positive burst to perform various processing steps through a single processing system (with a seamless transition from one mode to the next);

[0043] Figure 25The exemplary illustration shows a sample impulse + positive jump pulse waveform, highlighting the main negative sputtering pulse and the short and long jump phases;

[0044] Figure 26 is a photograph of a conventional planar magnetron operation, which is achieved by ultrafast impulse deposition and etching (utilizing the superjump radio frequency (RF)-like modulation of the positive jump);

[0045] Figure 27A and 27B The photograph of... highlights the superjump mode for generating an extended plasma away from the magnetic field tip and etching on the substrate through the sample oscilloscope waveform (showing 77 kHz operation) and the extended superjump mode;

[0046] Figure 28A and 28B The exemplary illustration shows the online and batch manufacturing processes in batch mode using a dedicated single inverted cylinder magnetron sputtering / etching station (which has a linear feed through multiple in-line stations) or multiple deposition / etching heads with consistent operation;

[0047] Figure 29 The exemplary illustration shows an exemplary process workflow for an online inverted cylinder magnetron (ICM) manufacturing process for thin film multi-layer coatings on nuclear fuel claddings;

[0048] Figure 30 The exemplary illustration shows a continuous feed system that has an adapter plug to feed one or more nuclear fuel cladding tubes continuously through the ICM in-line deposition / etching system;

[0049] Figure 31A and 31B The exemplary illustration shows an adapter plug that supports multiple substrates and highlights that the ICM with magnetic null bipolar focusing (generating a high-density plasma) will form plasma immersion and conformal deposition on multiple substrates;

[0050] Figure 32 The exemplary illustration shows a typical process workflow for a batch ICM or a more traditional PVD / etching system (for thin film coatings), where an impulse + jump process is used for ultrafast pulses;

[0051] Figure 33 The exemplary illustration shows the traditional batch substrate rotation in an extended plasma field;

[0052] Figure 34A and 34B The exemplary illustration shows a series of prior art results of Cr on Zr and Zr alloy materials, where conventional sputtering + active substrate biasing (left) and conventional HiPIMS + active substrate biasing (right) are used;

[0053] Figure 35A and 35B The exemplary illustration shows the prior art methods and results of cathodic arc deposition of TiN and TiAlN multilayers for nuclear cladding coatings;

[0054] Figure 36A 、 36B Figures 36C, 36D show scanning electron micrographs of cracks separating the multilayer stack, where ultrafast pulsing + positive jump is used, including Cr / CrN, Hf / HfN, Zr / ZrN (with the same sputtering target and Ar / Ar+N2 reactive deposition) and Nb / Cr laminates (two independent sputtering targets in a single vacuum chamber);

[0055] Figure 37 The prior art of functionally graded nanolayer composites is shown, which can be grown similarly using pulsing + jump;

[0056] Figure 38 Highlight short-term cladding coatings (using metal Nb / Cr / Mo with nitride cladding layers), diffusion barriers, tensile-compressive stress management;

[0057] Figure 39 The exemplary illustration shows an embodiment of the present disclosure, which provides a multilayer coating, including: a wear-resistant layer, a corrosion-resistant layer, a crack arrest layer, a ductile (elastic) structure (using an engineered multilayer thin film composite strategy);

[0058] Figure 40 The exemplary illustration shows a schematic diagram of the Thornton / Anders structural region;

[0059] Figure 41A and 41B Highlight: For nuclear fuel after loading and welding, directly apply the thin film coating to the cladding and end plugs.

[0060] Figure 42A and 42B are photos of the pulsed + jumped Nb / Cr coating stack (water quenched at 20°C after heating at 1200°C in air for 5 minutes), without delamination, spalling, or film deterioration;

[0061] Figure 43A and 43B Illustrate an alternative embodiment of the present disclosure, where a cylindrical cathode uses a meandering magnetic continuous runway (or others) with an internal moving magnet;

[0062] Figure 44 is a series of scanning electron micrographs showing the Cr / Nb coating on the reference tube (prepared according to the pulsed + jumped method #59A), showing the Nb mixed layer, the Nb stress control layer (for ductility), and the interfacial Nb layer (for Cr adhesion);

[0063] Figure 45 is a series of scanning electron micrographs showing on the Cr / Nb coating on the reference tube (according to the impulse + jump method #59B), showing the Nb mixed layer, the Nb stress control layer (for ductility), and the interfacial Nb layer (for Cr adhesion);

[0064] Figure 46 The schematic block diagram of shows an exemplary example of the electrical arrangement between the ICM and the impulse system (for PVD / etch operations);

[0065] Figure 47 provides more details on improving deposition conformality and control (compared to the current state of the art);

[0066] Figure 48A and 48B The exemplary illustration shows an exemplary example of the present disclosure, facilitating the deposition of a coating onto an object and / or etching the inner surface of the object, and for combining internal deposition and etching processes with external processes;

[0067] Figure 49A 、 49B 、49C The exemplary illustration shows more details regarding the positive voltage reversal and subsequent RF-like oscillations in the super-jump operation mode, where the frequency is lower, the positive jump amplitude further decreases per cycle to reduce the effective RF bias potential, and the positive jump waveform (including multi-spectrum frequency components) is creatively modulated to drive a high-density plasma while maintaining a lower effective RF bias potential;

[0068] Figure 50A and 50B The exemplary illustration shows the applications disclosed herein;

[0069] Figure 51A and 51B are photos of the impulse 2-2 system and the impulse 20-20 system (serving as the power suppliers in the systems described herein in the embodiments of the present disclosure). Detailed Description

[0070] Using plasma sputtering of HiPIMS, due to the high proportion of ionization of sputtered target atoms, a dense adhesive film can be achieved. The systems and processes described herein provide ultra-sharp pulses to achieve >10A / cm through micro-arc suppression 2Current density. The process includes positive spike pulses that reverse the polarity on the sputtering target after a high current pulse to accelerate metal ions that would normally recycle to the target towards the substrate. Pulse amplitude, onset delay, and length are controlled to customize the ion energy distribution function reaching the substrate to be coated. This control provides a powerful source to change the materials designer's process to fine-tune properties in thin layers - ion beam assisted using materials you deposit at high deposition rates (a win-win scenario). Stress control, preferential grain growth, densification, and controlled ion energy allow deposition without substrate biasing and selective etching. By impulsive Coatings can be deposited directly on insulating surfaces with controlled ion energy to tune film properties.

[0071] The HiPIMS solution described herein according to the illustrative examples is ideal for reactive sputtering applications of borides, nitrides, carbides, and oxides. When using reactive HiPIMS positive spikes, (Nb / Cr / Mo, NbN / CrN / MoN, SiC / ZrC, SiC / Zr 11 B2) and nanocomposite layers of stabilizing materials (e.g., ppm La, Y) can be spatially modulated to construct functionally graded superlattices with an "engineered" maximum defect size and stress release. The modulated nanolayers allow variations in hardness and elastic modulus to achieve a hardness / toughness factor trade-off, which is important for managing thermal gradients. Hall-Petch strengthening, interface widening, and dislocation slip impedance from each successive multilayer enhance the coating. Residual stress is affected by the modulation ratio, material selection, and energy deposition during deposition / epitaxy. Also, as shown by the European Organization for Nuclear Research (CERN), Starfire technology is effective for 3D shapes and deposits on sidewalls and tangentially incident surfaces, i.e., coating the next-generation General Atomics SiC fiber cladding material (wound in a matrix).

[0072] A cylinder magnetron sputtering system (e.g., columnar or inverted) according to an example implementing the present disclosure employs a "meandering" or "Greek key" magnetic racetrack to have a continuous ExB Hall drift region that zigzags along the length of the sputtering chamber. The length of the cylinder magnetron is variable based on manufacturing. For example, a small system with a length of 5 cm has been created. It is envisioned that the diameter can be smaller (less than 3 cm) and larger (greater than 30 cm). Also, longer systems (magnetron length greater than 1 m) are envisioned.

[0073] In a particular illustrative example of such a sputtering system (for depositing high deposition rate coatings onto the interior of RF accelerators and superconducting cavities to achieve high quality films), a sputtering electrode material tube greater than 1 meter in length surrounds a magnetic array, the magnetic array including multiple sets of magnets arranged to have a Hall effect region that extends vertically over the length of a sputtering target greater than 1 meter long and forms approximately 8 channels in a Greek palindrome pattern on a 1.5 cm diameter sputtering target tube. The magnetic assembly is within the target material tube and filled with a cooling liquid to keep the target and magnets cooled. The sputtering target rotates relative to the magnets to achieve extremely high target utilization (e.g., greater than 90%). The compact geometry of the illustrative sputtering system facilitates sputter deposition in small tubes, cavities, and complex 3D structures.

[0074] Such a cylinder configuration is used, for example, to coat RFQ accelerator vanes and bonding locations within a vacuum chamber. The HiPIMS mentioned / described above facilitates / enables energy bombardment, good interface mixing, and a good adhesion film (which effectively seals welds, small pores, and plating defects).

[0075] The inverted magnetron physical configuration of the present disclosure flips the typical sputtering source / target orientation such that the object to be coated is near the geometric center and a larger sputtering target cylinder is located at the outer radius. The magnetic structure is distributed along the outer cylinder (which has provisions for cooling, rotation, and fixation). Since the Hall effect region is at the outer radius, there is a greater distance to travel and more magnetic material is required. However, there is a more active plasma wetting region (more cooling is available). Thus, higher electrical power can be transmitted to increase the deposition rate (e.g., 3 times that of a rotating or planar outward configuration). The above-described resulting configuration also captures sputtered material that misses the object to be coated and is retrieved for re-sputtering. The above inverted sputtering configuration further increases target utilization and helps reduce the cost of sputtering / coating materials.

[0076] In an example of providing high throughput nanolayers, a production setup is provided where a ZIRLO (zirconium niobium alloy) tube is fed on one side and passes through multiple cylinder sputtering zones (e.g., rings) via a set of rollers or transfer rods, depositing successive layers of a specific material, alloy, or ceramic. For example, an Nb base layer is deposited and then Cr and Mo layers are deposited. The tube can first pass through the Nb zone, then into the Cr zone, and then into the Mo zone, so there is a continuous process flow and continuous in-line / serial production can be provided.

[0077] Another option includes having an anode electrode or corresponding target section that serves as a return electrode path for the HiPIMS current and provides a ground reference for floating ion potentials and sheath propagation for ion energy control.

[0078] One option is to have a linear target material located within a hexagon or polygon, which runs axially along the length of the sputtering chamber, with an independent solution for each target to achieve active cathodes and anodes. This allows resputtered material to be collected on the corresponding electrodes for collection and reuse. A movable mask can be used for such scenarios. The simplest arrangement (including linear feeding through multiple cylinder ring zones) has the maximum electric potential (where the ZIRLO rod passes through). Batch processing of multiple tubes can be provided, where this technique suspends multiple tubes in an inverted magnetron configuration for coating.

[0079] Alternatively, more traditional methods using a rotary sputtering target or a planar target can be used to sputter on a planar tube fixture to rotate multiple tubes in and out for continuous layer deposition and uniformity by rotation.

[0080] One possible benefit is to use soft X-rays for actinometric multilayer inspection regarding Bragg reflection to measure layer thickness and interface quality for rapid screening of film quality in addition to thickness. X-ray fluoroscopy and other non-destructive inspection methods can also be used for material composition and elemental ratio analysis.

[0081] The HiPIMS layer can prevent the formation of eutectics (which are harmful to Zr alloys). A Nb / Cr / Mo laminate structure can be provided for preventing Zr-Cr eutectics at 1333 °C and Zr-Mo eutectics at 1576 °C at the interface.

[0082] Advanced conductor nanolayer formulations, concepts, and functionally graded coating architectures can be formed, which provide oxidation resistance, corrosion resistance, increased hardness, provide diffusion barriers and rate-limiting steps (for degradation).

[0083] Reactive HiPIMS with positive jump pulses allows for adjusted ion energy control and film annealing, promoting specific phases, nanocrystallinity, etc.

[0084] (Nb / Cr / Mo, NbN / CrN / MoN, SiC / ZrC, SiC / Zr 11 B2) and nanocomposite layers of stabilizing materials (such as ppm La, Y) can be spatially modulated to construct functionally graded superlattices, which have "engineered" maximum defect sizes and stress release. The modulated nanolayers allow for changes in hardness and elastic modulus to achieve a trade-off of the hardness / toughness factor, which is important for managing thermal gradients. Hall-Petch strengthening, interface widening, and dislocation slip impedance from each successive multilayer enhance the coating. Composition gradients eliminate sudden transitions in thermal, elastic, and plastic mismatches at the interface to significantly reduce thermal and residual stresses at critical crack nucleation sites. The Stoney formula coating follows the thermal gradient. Improved sliding contact can be achieved by stopping depressions / notches and staggered frictional sliding.

[0085] The use of precise control of ion and neutral particle fluxes, energies, directions, and fluences to process substrates allows coating designers to functionally grade regions such that when the regions experience thermal stress from temperature increases, the film hardens. Alternatively, the coefficient of thermal expansion (CTE) tensors can be better matched such that there is less thermal stress over a greater range of operation. Thin and thick engineered films can be deposited to provide structural elements that remain encapsulated or fuel pellet retainers that limit bulging and bursting under accident conditions or higher fuel burnup. Another embodiment is to provide a structure that slows creep through HiPIMS films and grain size and grain morphology; nanocomposite layers can be designed to have less creep.

[0086] The proposed sputtering system can be highly adapted to various specific manufacturing needs. Multiple sputtering electrodes (guns) can be used to coat and grow films. The system is adapted to facilitate changing the pulse rate, grading material composition tuning to add alloys, adding stabilizers, or changing process conditions during operation. As will be described in more detail hereinafter, an important desired aspect in processing is to limit the time between processing steps to minimize contamination and introduce defects into the underlying film, interfaces, and deposits.

[0087] The system is adapted to apply thin layers for etch stop, etch stop, and / or crack propagation stop. The system can also provide chemical engineering barriers for diffusion and migration. The system is adapted to form alternating semiconductor / metal superlattice layers, thus affecting the electromigration potential and the diffusion transport driving potential to slow down its oxygen migration at high temperature locations. The Seebeck / Thompson effect regarding the recovery potential is used to limit ion movement.

[0088] In certain applications of improved coatings provided by the devices and processes described herein, the system provides enhanced coating performance and improvements under accident / failure conditions, enabling nuclear power plants to operate at higher linear heat rates. The Westinghouse AP1000 reactor is approved by the NRC (U.S. Nuclear Regulatory Commission) at 5.7 kW / ft. The reactor balance of the system is capable of handling much higher values. However, limits are set based on accident tolerance and failure conditions. As specified in 10 CFR 50.46, under a Loss of Coolant Accident (LOCA), the peak cladding temperature cannot exceed 1204°C, oxidation is less than 17% of the cladding thickness, H2 generation is less than 1% of the assumed maximum, and the maintainable cooling geometry must be maintained. Uncoated Zr cladding is oxidized by high-temperature steam and experiences bulging and bursting above 700°C: this is the limiting factor, and the 5.7 kW / ft linear value is set based on reactor travel time, thermal response, and the probability of cladding failure. However, the advanced multi-layer metal / ceramic cladding provided by Spark ImpulseTM and Positive PopTM technologies has oxidation resistance above 1300°C and significantly slows down cladding failure, provides significantly improved thermal stress and fracture toughness, increases compressive strength to minimize bulging / bursting, and enables higher linear heating values. Values greater than 7 kW / ft are not unreasonable for such accident-tolerant fuel designs, which is equivalent to an increase in power generation capacity of more than 25% for existing commercial nuclear power plants with minimal infrastructure changes.

[0089] The material sputtering systems and methods described herein provide a means for further improving stress management, which affects the overall bulging / bursting, LOCA (Loss of Coolant Accident) scenarios proposed for linear heat (power upgrade) values, and so on.

[0090] The currently pending U.S. application Ser. No. 16 / 006,357, filed Jun. 12, 2018, entitled “Pulsed Power Module with Pulse and Ion Flux Control for Magnetron Sputtering,” the content of which is hereby incorporated by reference in its entirety, including any references contained herein, describes high power impulse magnetron sputtering (HiPIMS), capable of achieving high yield deposition of high quality metal and ceramic films. The technology is beneficial for corrosion and wear resistant nanocomposites and multilayer films for improving adhesion, stress control, and fracture toughness. The voltage reversal feature (termed the positive spikeTM) increases deposition rates and provides process control (variables / features) for adjusting ion energy to control the micro / macrostructure and morphology of films on any substrate, including insulating or temperature sensitive materials. Starfire's impulseTM can deposit nanoengineered metal / ceramic layers that provide 3-10x improvement in managing thermal stress and resisting cracking. The technology is quite effective in reactive sputtering environments (for coating ceramic materials with low cost metal raw materials) and can impact other innovations in target utilization for an owner's target cost (meeting the price point of $30 / unit for ZIRLOTM tubes in the nuclear industry). The Starfire HiPIMS+ spike technology is also capable of transfer to future SiC ATF cladding concepts (such as General Atomics SiGATM).

[0091] Compared to other electrochemical techniques, cold spray, and plasma thermal deposition techniques and conventional PVD, the examples of the present disclosure provide stronger control, conformality, and the ability to tune processes at the nanoscale to the micron scale.

[0092] Turn to Figure 1, a high-level illustration is provided, which is an exemplary configuration (cross-sectional view) for processing a target object 100 according to the present disclosure. The outer encapsulation 110 includes: an array of magnetic assemblies 138 disposed around the sputtering target material 101 within a vacuum environment 111. The array of magnetic assemblies 138 is immersed in a cooling liquid 109 (such as water) to provide high heat dissipation capacity to facilitate maintaining the desired magnet temperature during system operation. The magnets of the magnetic assemblies are high-strength NdFeB permanent magnets in the example. The target holder 108 can serve as a heat conduction path between the cooling liquid 109 and the sputtering target material 101, and the target holder 108 can also serve as a barrier for the vacuum environment 111 to allow low pressure and controlled gas flow to provide production environment control. The magnetic assemblies 138 can be rotated within the outer encapsulation 110 in the example to provide a change in the position of the sputtering target 101 by the magnetic field represented by magnetic field lines (such as the lines 112 representing the magnetic field), so as to change the sputtering site (such as the sputtering site 102) under the dense plasma region (such as the dense plasma region 113) for generating sputtering ions and neutral particles 103 for the injection and etching of the target object 100. The substrate 106 of the target object 100 is located within the vacuum environment 111 and is subjected to bombardment by incident ions and neutral atoms 104, immersed in the secondary concentrated plasma 131, controllable energy active ions 169 from the positive pulse, and high capture efficiency ions 164 and thin film coatings 107 for forming deposition conformality. Figure 1 The inverted cylinder magnetron shown in the example in

[0093] allows re-deposition (for example, see the re-deposition path 105 of the material from the source sputtering site to the secondary sputtering site), and increases the utility of the sputtering target material 101 to achieve a longer processing life before the need to replace the sputtering material. High voltage electrical pulses are provided from an external power module (i.e., impulse Figure 1The physical / structural configuration of the components therein provides / facilitates controlled deposition and etching in a single plasma processing reactor by promoting plasma immersion, magnetron sputtering, plasma immersion, high-energy ion etching, and conformal engineering coatings on the substrate 106, such as nuclear fuel cladding materials.

[0094] There is significant background for thin film deposition for magnetron sputtering and physical vapor deposition techniques, including cathodic arc. Figure 2A Shows the basic planar magnetron of the prior art, highlighting the magnetic field confinement region, plasma generation region, target, and pole pieces for setting the plasma by applying a negative voltage to the target electrode. For small sputtering sources, permanent magnets are typically used to generate the magnetic field. Figure 2B Highlights the basic cylinder magnetron configuration, which uses a cylindrical cathode or an inverted cylinder setup, where the axial magnetic field in a solenoid configuration is driven by an external power supply.

[0095] Figure 3A Shows the prior art of Glocker et al. for an inverted cylinder magnetron, which has a central target electrode and two anode electrodes separated by limiters on both sides. The system utilizes two axial magnetic fields. Hardware commercialization (Kurt J. Lesker Company) has entered the VIPR optical coating platform. Figure 3B Shows the three-anode system of Tianzong Xu et al., which has an external wound solenoid electromagnetic coil. This system includes a third central anode that extends along the entire length of the sputtering chamber. The system is commercialized (Vactronix Scientific) for medical application coatings, namely, in-vivo medical coils and wires. These systems are intended for traditional physical vapor deposition (PVD) sputtering, which has a low ionization percentage and mainly sputtered neutral atom deposition, where the sputtering plasma is distributed circumferentially, rather than the highly localized distribution of the sputtering plasma due to the local magnetic components suitable for ultrafast HiPIMS and positive voltage reversal (as provided in the exemplary layout illustrated in Figure 1 ).

[0096] Figure 4Describe in detail one aspect of the present disclosure. The exemplary illustration shows high target utility and resputtering capture on the opposite side of the ICM target region. The sputtering target 401 has a locally dense plasma formation structure and ion sputtering at the sputtering position 402 (which causes the emission of sputtering ions and neutral particles 403). A portion of the ions and neutrals (e.g., the ions and neutrals along the path 404 towards the substrate surface) will impinge on the substrate 406 placed in a vacuum environment. The remaining portion of the ions and neutrals is guided to other regions of the sputtering target 401 for recapture (e.g., the ion / neutral particle path 405). This results in efficient material utilization because the material is efficiently reused, especially for long inverted cylinder magnetrons, where the length of the sputtering target 401 is significantly greater than the diameter (in terms of the length-to-diameter ratio). For Figure 4 the inverted cylinder magnetron sputtering system shown in

[0097] Figure 5 An embodiment of an inverted cylinder magnetron is illustrated, where the sputtering target electrode 501 is composed of a series of individual sections. Each section is, for example, manufactured and then joined together to form the quasi-cylindrical shape of the sputtering target electrode 501. The target holder 508 serves as a structural base / platform to: assist in forming the assembly of the individual sections of the sputtering target material 501 into a quasi-cylindrical shape, maintain the vacuum seal for the vacuum environment 511, allow contact with the liquid cooling 509 environment, and assist in positioning the sputtering target electrode 501 in the package 510. Using individual sections for the sputtering target material 501 is a desired manufacturing feature because an inverted cylinder of expensive target material may be difficult to obtain and it is more easily coordinated with planar workpieces. However, various configurations of the sputtering target material 501 structure are also feasible.

[0098] One aspect of the present disclosure is illustrated in Figure 6AIn the inverted cylinder magnetron configuration, a radial magnetic field is established, which is used to create a local magnetron effect (for plasma formation) and electron Hall effect transport. However, the inverted cylinder magnetron configuration also facilitates / enables: the formation of a magnetic null in the center of the inverted cylinder magnetron for plasma accumulation to achieve higher ionization, utilization of sputtering materials, and immersion of the substrate to be coated to achieve superlative surface conformality. The magnetic field lines 612 define regions of high-density plasma 613 at multiple locations along the sputtering target 601. The magnetic fields 612 have polarities such that they create a magnetic null or minimum 627 on the centerline, which becomes a site that allows secondary plasma accumulation and additional ionization. During operation of the system, the cold electrons near the magnetic null 627 are weakly confined and impede ion transport by ambipolar diffusion. This combination of resulting characteristics is used to achieve plasma immersion and concentration in the region of the magnetic null or minimum 627 onto any substrate. In the schematic case where there is no central null, here the magnetic field lines create a continuous large-area racetrack for electrons that terminates at the ends, achieved by using accelerating racetrack electrons and ions through a magnetic bottle (with high B) or through a large-volume low-density plasma (low B).

[0099] Figure 6B is a COMSOL model highlighting the magnetic B-field polarization 625 from three magnetic component positions along the azimuth around the enclosure 610. Opposite B-field polarizations 626 are visible in the magnetic flux return paths that alternate between the magnetic components. The magnetic nozzle / tip effect 630 is generated at multiple locations, enhancing the magnetic null or minimum 627 at the center of the system. The magnetic profile 628 is highlighted in a color-shaded legend, varying from 300 Gauss to less than 10 Gauss in the region. The magnetic null or minimum 627 provides a source for the generation, concentration, and localization of additional plasma to assist in the sputter deposition and etching of substrates for thin film processing, especially when coupled to an ultrafast HiPIMS plasma generation process (with a kick and positive spike rapid voltage reversal for guiding ion energy and conformal plasma sheath development).

[0100] Figure 7 The exemplary illustration shows a longitudinal cross-sectional view (i.e., side view) of the structure shown in a transverse cross-sectional view of the device according to the present disclosure in Figure 1 the. It shows magnetic field concentration near the sidewall of the target electrode and a magnetic field minimum on the centerline for plasma accumulation to form a low-impedance virtual anode and a path for pulsed current to travel to and from the location in the cylinder structure (illustrated in Figure 7 Figure 7 ​An electrode on either end of the ( ). The sputtering target electrode 701 has: one or more magnetic assemblies (not shown) that provide radial and axial magnetic field lines 712. The magnetic null or minimum point 727 is close to the centerline of the cylinder structure, forming a virtual electrode 715 for returning low-impedance current along the axis to a series of return electrodes 714 (located at the ends of the device, shown in the Figure 7 longitudinal cross-sectional view in). The return electrode 714 is isolated from the sputtering target electrode 701 by an insulator 716, and the insulator 716 is in turn protected from deposition by a shield 717. The shield 717 can be replaced when the target electrode 701 is replaced during a scheduled maintenance cycle. During intense ultra-short pulse plasma operation using pulsed HiPIMS (with a magnetic cusp effect from the magnetic field 712), a significant amount of plasma is generated and concentrated on the axis to create a virtual electrode 715 current path to complete the circuit. Thus, there is no need for a physical electrode to extend along the centerline axis.

[0101] Figure 8 Based on the above reference to Figure 7 the above features are further extended. In particular, Figure 8 exemplarily shows plasma accumulation and power utility using electron reflection energy transfer (to achieve enhanced ionization and generate plasma for lower pressure operation on the axis, improved ion ratio, conformal deposition, and target utility) during the operation of the disclosed device. Secondary electrons 818 released from the sputtering target surface or a dense plasma region (not shown) are accelerated along the centerline as illustrated by path 819 away from the sputtering target towards the virtual electrode, performing Hall trajectories. Due to the inverted cylinder magnetron configuration, electrons (such as electron 818) are reflected off the opposite side of the chamber (as shown at 820) and collide with background gas, sputtered metal, and ions, causing further ionization 821 and generating a local bulk plasma 823 near the centerline. Additional bulk plasma 823 is located in the magnetic null or minimum point 827 and has a low-impedance path towards the return electrode 814 to complete the circuit. Electron reflection (indicated by 820) is similar to the hollow cathode effect of a direct current (DC) discharge device, except that it feeds the bulk plasma in the magnetic null or minimum point 827 on the centerline to support Figure 7 the virtual electrode 715 shown in.

[0102] Figure 9 Based on the features shown in Figure 8 the above are further extended. In particular, Figure 9An exemplary detailed description of an inverted cylinder magnetron processing module having a center-fed substrate passing along an axis, highlighting a 360-degree coating process, a sputtering dense plasma region, and a re-sputtering application suitable for nuclear fuel cladding coating manufacturing. Ultra-short pulsed HiPIMS voltage-current pulses generate a dense plasma layer (region) 913 near the sputtering target 901 close to a magnetic field assembly (not shown). Ions from the dense plasma region 913 strike the sputtering target 901 at position 902 and generate sputtered ions and neutrals 903, which are incident (as shown at 904) onto the substrate 906 or are re-sputtered and captured (as shown at 905) at different positions on the sputtering target 901. Due to the ultra-fast pulsed nature of plasma generation and the HiPIMS process in the dense plasma layer 913, the voltage applied to the sputtering target 901 is localized near the dense plasma layer 913. Because of the time required for potential diffusion across magnetic field lines and the impedance difference between the return electrode and the virtual electrode (highlighted in Figure 7 ), a plasma potential drop is maintained. Similarly, applying a positive jump pulse takes advantage of the impedance and the diffusion time of the round-trip potential across magnetic field lines. The substrate 906 is then coated on its surface with a thin film 907. The substrate 906 is fed into or through the inverted cylinder magnetron reactor, for example, by a conveyor, holder, actuator device suitable for the application. The substrate 906 can also be connected to a bias power supply for applying a DC or pulsed bias to achieve additional charge collection and ion impact energy for deposition or etching.

[0103] The symmetric nature of an exemplary configuration of an inverted magnetron sputtering system is illustrated in Figure 10 wherein another aspect of the present disclosure is illustrated: using magnetic tips to guide a low-temperature plasma to the centerline of the chamber to achieve a high proportion of ions being captured from the bipolar well onto the substrate. The magnetic field 1012 is shaped and arranged for a magnetic nozzle / tip effect 1030, which produces a Grad B force term to aggregate / repel electrons away from higher magnetic field regions. The nozzle / tip effect 1030 has the result that the plasma is concentrated 1031 at the magnetic null or minimum point 1027. The net effect is additional ionization of the background gas, sputtered neutral metals, and additional charges for the positive jump effect and conformal deposition or etching on the substrate immersed in the region.

[0104] Another aspect of the present disclosure is illustrated exemplary in Figure 11 and relates to the use of a single continuous meandering magnetron path 1133 that extends along and around the sputtering target electrode 1101, for example, in a Greek palindrome shape 1134. The continuous loop 1135 allows the electron emission current to balance along the entire inverted cylinder magnetron. The spacing of the Greek palindrome shape 1134 can be customized to determine the amount of plasma coverage on the surface of the sputtering target electrode 1101. In Figure 10In the configuration shown, there are six (6) magnetic components, thereby forming twelve (12) different dense plasma regions, and the effective HiPIMS instantaneous coverage rate on the target surface is 33 - 50%. In engineering design, there is a trade-off between the plasma coverage percentage area (i.e., the 1134 sector length - the circumference of the sputtering target 1101), the peak current density (for the ionization percentage), the thermal heating capacity of the target material, and the magnetic nozzle / tip plasma concentration effect.

[0105] Go to Figure 12 , regarding illustrative examples of the structural geometry and arrangement of magnetic components within the entire magnetic package, further details are provided to facilitate the meandering magnetic control path (generating a B field for electron Hall effect drift, plasma generation, sputtering for target erosion uniformity, and adjusting the end curvature). In Figure 12 , the electrons 1218 follow the Hall trajectory along the magnetron runway (as shown by path 1233). The magnetic components are polarized in one direction in the first polarization component 1225 and paired with the opposite polarization component 1226 to generate the desired / required magnetic field for the E×B Hall effect drift direction 1229 and the constraints necessary to maintain the potential drop on the sputtering electrode. Considering a longer Greek palindrome sector to expand the meandering continuous runway, the steering configuration magnetic components (such as the steering component 1238) are magnetically modulated (as shown by the direction indicating arrow 1236) to generate the desired plasma density variation relative to the centerline of the main closed runway (indicated by 1237) on the axial sector. The entire magnetic package is, for example, immersed in a liquid coolant (near the sputtering target electrode and any target holder) and can be arranged to be rotatable relative to the target material surface to improve uniformity and operating stability.

[0106] Figure 13A and 13B Provide further illustrative examples of the disclosed devices described herein, which include: one or more (shown here as 3) discrete closed-loop runways (such as rectangles or other closed loops) that do not travel along the cylinder magnetron and are used as unconnected independent sputtering sources. Separate magnetic components 1338 are used to generate a magnetic field on the sputtering target 1301 (electrode). Each discrete closed runway 1337 is positioned relative to other parts of the system to achieve the desired magnetic effects within the vacuum environment 1311. This scenario is desired for one or two high-power magnetic components 1338 suitable for high-power impulse currents and generating dense plasma through some magnetic null points or minimum points on the centerline for forward sputtering deposition, immersion, and etching, and simultaneously balancing the power and thermal load on the sputtering target 1301. In one scenario, less than 33% of the sputtering target surface will be covered with plasma, thereby allowing an extremely high instantaneous current density (greater than 5 A / cm 2 ) during high duty cycle operation.

[0107] Based onFigure 13A and 13B If the description / disclosure of Figure 14A and 14B is further extended, the exemplary illustration shows how the magnetic assembly rotates around the central axis, or how the physical rotation of the target electrode causes the dense plasma sputtering region and target erosion to move along the inverted cylinder magnetron sputtering system to achieve a target utilization rate significantly greater than 50%, a longer life, and maintain more uniform target sputtering. This is another aspect of the present disclosure. In particular, when the magnetic assembly 1438 (including the magnetic field polarization N 1425, which is connected to the magnetic polarization S 1426) rotates relative to the 1439 sputtering target or the sputtering target rotates relative to the 1440 magnetic assembly 1438, the dense plasma region 1413 sputters material from the target (leaving target erosion 1441) and sweeps azimuthally across the erosion configuration to produce erosion expansion 1442.

[0108] The effect of rotation 1439 or 1440 is threefold. It causes wear expansion on the kill bar 1401. It moves the dense plasma region 1413 to change the direction and source of sputtering ions and neutrals to achieve more uniform substrate processing. It also minimizes the collective V-grooves on the target electrode (which affect the stability of the HiPIMS process over time).

[0109] Figure 14A and 14B The exemplary illustration shows an unbalanced magnetic configuration where the polarity of the magnetic assembly 1438 is N-S and is arranged oppositely to another magnetic assembly of opposite polarity (i.e., S-N). The effect of this is to direct some of the magnetic field lines 1412 through the center of the vacuum environment 1411, thus providing a path for the plasma to travel back and forth across the device and bring additional ions to the substrate located at the center of the vacuum environment 1411.

[0110] Based on the extension of the V-groove effect, Figure 15A and 15B The exemplary illustration shows the effects presented during conventional HiPIMS sputtering of a stationary target, i.e., the formation of deep V-grooves, which leads to higher target cycling, efficiency losses, and changes in deposition parameters as the sputtering target ages. The disclosed device and its corresponding operation avoid the formation of deep V-grooves, maintain a high solid angle acceptance, minimal recirculation, and a higher deposition rate, improving the process stability over time.

[0111] Figure 15AThe figure shows a sputtering target 1501 that undergoes non-uniform erosion, resulting in the formation of deep erosion V-grooves (such as V-groove 1543). The magnetic assembly is located behind the target electrode 1501 and has a correspondingly higher B-field, deeper in the erosion V-groove 1543. Once the V-groove 1543 becomes slightly deeper than another groove, the resulting plasma density will increase to an extremely high density (as shown at 1544) relative to the density at the shallower adjacent location (as shown at 1513). As a result, more plasma flow enters the deeper V-groove 1543, leading to more sputtering and more local erosion relative to other locations on the sputtering target 1501. The sputtered material trajectory distribution 1545 will be similar to a cosine to cosine-squared distribution, depending on the uniformity factor and plasma conditions. When the V-groove 1543 becomes deeper relative to the groove width (as shown at 1545), the escape solid angle for sputtered neutrals and ions 1546 will become smaller and smaller from 2π steradians. This increases the recycling of sputtered material onto the sidewalls 1547, leading to a further enhanced growth of the deep V-groove 1543, which limits the deposition rate, increases the power deposition in the deep groove 1543, and heats the target electrode 1501. The conventional HiPIMS process has a higher sputtered atom recycling (back to the target electrode) and a smaller deposition rate (compared to DC magnetron sputtering). The effect of the decreasing escape solid angle 1546 is only one aspect of the process variations for the lifetime of the sputtering target 1501.

[0112] In Figure 15B the same sputtering target 1501 is illustratively shown in a configuration where a dense plasma region 1513 is distributed azimuthally along the target electrode using a rotating magnetic package or a rotating target electrode (already shown in Figure 14A and 14B ). The rotation of the dense plasma region 1513 expands the erosion track 1542 and minimizes the height of any V-groove to form a more uniform erosion configuration 1548. In an inverted cylinder magnetron setting (with a long axial length and a small diameter), the end effects are smaller compared to the azimuthal case, forming an almost normal sputtered material trajectory distribution 1545 (with a large escape solid angle 1549 and a small material recycling 1547). This is another aspect of applying the present disclosure to HiPIMS and high-current pulsed sputtering. The more uniform erosion 1548 results in fewer process variations, greater deposition stability, and improved target utilization performance.

[0113] Figure 16A is a CAD model, while Figure 16BThe cross-sectional view shows an illustrative example of an inverted cylinder magnetron device (where water flow is used doubly: to cool the hardware and to drive the magnet rotation to achieve target sputtering uniformity). The inverted cylinder magnetron head 1650 includes: an outer enclosure 1610 (containing the vacuum chamber 1554), the vacuum chamber 1554 also being used to mount the sputtering target 1601 (and its holder surrounding the substrate 1606), the substrate 1606 being fed axially through the magnetic assembly region 1624, the magnetic assembly region 1624 being mounted to the impeller 1652 to drive the magnet rotation, where water flow passes through the port 1651. Physical mounting and high voltage insulation are provided by 1653 and integrated into the enclosure 1610. This embodiment exhibits a tight coupling of the magnetic assembly 1624 to achieve a small diameter vacuum environment.

[0114] Figure 17 An illustrative display shows that a tight coupling (less than 4 inches in diameter) is feasible, where using this multi-tip geometry 1730 produces a dense plasma region (such as the dense plasma region 1713) for sputtering near the target electrode 1701, while producing a strong secondary plasma region 1723 near the centerline for substrate immersion, low pressure operation in metal mode, improved sputtering efficiency, and high ion capture efficiency on the substrate 1707 for surface treatment and coating. The high strength multi-tip geometry of multiple magnetic assemblies (such as the magnetic assembly 1738) allows for a high B-field near the target electrode 1701 (where there is a large magnetic null along the centerline) for the tight coupling of the inverted cylinder magnetron.

[0115] Figure 18A , 18B, The common exemplary illustration 18C shows: using ultrafast high-power pulsed sputtering and subsequent rapid plasma potential reversal to direct and capture a high proportion of sputtered ions for conformal deposition on a substrate. The basic operating principle of the impulse HiPIMS system is: a large-amplitude negative voltage pulse 1855 is applied to the target electrode 1801. The rapid potential change drives the formation of a plasma region in the high-B-field magnetic confinement region on the surface of the target electrode 1801. As ions sputter the target electrode and release multiple secondary electrons (enabling subsequent ionization and self-development to form a dense plasma region 1813), the plasma intensity rapidly increases. When sufficient sputtered atoms are released from the surface of the target electrode 1801, as the sputtered metal target atoms dominate over other gas species, the dense plasma region 1813 becomes "metal-dominated". This is reflected in the HiPIMS current waveform 1858, which has a peak and a roll-off (when the plasma becomes metal-dominated and saturated). Typical neutral particle energies of a few eV and ion energies of 2 - 20 eV are presented based on HiPIMS plasma measurements. The transit times 1861 for several selected categories are shown in the table. For a 3-inch distance, at 2 eV and 20 eV, they are on the order of 10 - 40 microseconds. The effective metal plasma time is approximated by the peak and roll-off in the current waveform 1858, plus the transit time 1861. The main negative voltage pulse 1855 terminates, and a positive voltage reversal is applied to significantly affect the potential structure within the vacuum environment (from negative 1865 to positive 1866). The transit ions and subsequently ionized neutrals 1862 are now accelerated towards the substrate 1806 due to the presence of a hindering positive potential at the target electrode 1801. The net effect of the positive jump is to converge the ions and plasma within the inverted-cylinder magnetron towards the substrate 1806 to achieve improved metal deposition and ion energy 1862 flowing towards the substrate (which is controlled by the amplitude of the positive jump 1866). Note that there are two different positive jump regions: the short jump 1856 and the long jump 1857. The short jump 1856 accelerates the ions from the dense plasma region 1813 away from the target electrode 1801. The long jump 1857 disposes of the evolution of the plasma potential, thus forming an overall plasma region towards the substrate and the return electrode (not shown). The short jump 1856 and the long jump 1857 are evident in the current waveform 1858, with different curves. The changes in the shape / duration of the short jump 1856 and the long jump 1857 adjust and tune the desired ratios of ions and neutrons, etching / deposition, instantaneous particle (thermal) loading, and effective ion energy. Such changes include alterations to the following: peak current in the HiPIMS waveform 1858, initiation of the metal mode 1813, ion / neutral transit time 1859, deposition rate, amplitudes of the short 1856 and long positive jumps 1857, any initiation delay 1860 in the positive jump (to separate the ions accelerated from the dense plasma region 1860 / overall plasma region), pressure, power, magnetic field strength, number of tips, and so on.Impact + positive jump provides additional process variables for optimizing substrate and thin film processing.

[0116] An effective strategy using the present invention is to adjust the amplitude of voltage waveform 1855 higher to achieve peak current waveform 1858, which exhibits an effective current density greater than 1 A / cm² on the sputtering target and has a sufficient metal mode region 1813 in the waveform, thus ensuring a large number of sputtered metal ions in the plasma and consequently rapidly traversing to the short positive jump 1856 with a minimum delay 1860 to accelerate as many ions as possible towards the substrate 1801. The pulse repetition rate is then maximized to transmit as many positive jump pulses as possible to the substrate, up to the system's thermal limit. More positive jump pulses (short jump pulses and long jump pulses) result in more ion flux 1862 being transmitted to the substrate 1806, denser plasma generation 1813, and ion multiplication in the overall plasma 1823 to enhance the immersion of the substrate 1806. 2 and

[0117] Figure 19A and 19B Based on Figure 18A 、 18B 、18C is further extended, where the nature of the short jump pulse 1967 (accelerating ions 1970 from the dense plasma region 1913 near the sputtering target 1901) and subsequent deposition based on the adjustable energy given to the ions is highlighted. The amplitude of the short jump 1967 accelerates ions with controllable energy 1969 from the dense plasma region 1913. If the positive jump pulse terminates rapidly, only the ions near the magnetic confinement region 1968 will be accelerated away. The trajectories of these short jump ions are approximately perpendicular to the B field, causing ion diffusion on the trajectory 1970. These ions will traverse the vacuum environment and impact the opposite side or interact with the substrate for surface modification. The benefit of the positive jump pulse is that through forced binding and injection, energy redeposition reduces dust formation on the surface of the sputtering target 1901. This minimizes loosely bound dust particles and their migration (which can fly off and land on the substrate, forming pinhole defects on the deposited thin film that can affect performance).

[0118] Figure 20 The illustrative diagram shows a comparison of conventional DC magnetron sputtering (low current, low ionization), pulsed DC (lower current, low ionization but more favorable for reactive gases), conventional HiPIMS (high current, high ionization but low deposition rate), and impact + positive jump (high current, higher ionization rate, and higher deposition rate). Typically, the HiPIMS plasma current density is about 0.3 A / cm². 2 Using an ultrafast impact followed by a positive jump pulse, it is possible to exceed 3 A / cm². 2and has good film properties and is used as a factor for designing an inverted magnetron structure to achieve high peak power for stronger ionization, conformal plasma etching, and deposition.

[0119] Figure 21 Adapted from US20180358213A1 and illustratively shows ultrafast high-power pulsed magnetron sputtering and the potential distribution between the sputtering target and the substrate.

[0120] Figure 22 Adapted from US20180358213A1 and illustratively shows the ultrafast switching on the target electrode and the evolution of the positive voltage reversal to a positive voltage and the potential distribution in the magnetic confinement region near the target electrode: the short spike accelerates ions from the dense HiPIMS plasma region away from the target electrode (typically perpendicular to the magnetic field lines along grad B).

[0121] Figure 23 Adapted from US20180358213A1 and illustratively shows the evolution of the positive potential to the long spike phase, where the overall plasma potential increases and a conformal sheath forms on the substrate and other surfaces as the overall plasma travels back and forth.

[0122] One aspect of the disclosure provided herein is that during the operation of the devices described herein, it is possible to control the flux and energy of the ions deposited / impacted on the substrate to prepare and deposit thin films with engineering properties. Through the high level of customization provided by the combination of ultrafast high-current pulses (with a fast positive voltage reversal) and an inverted cylinder magnetron structure, superior novel films can be achieved, including advanced nanolayer composite structures and functional grade materials with specific properties (including oxidation resistance, thermal fracture toughness, crack arrest characteristics, diffusion barriers, and anti-wear, anti-corrosion, ductility, rigidity, lubricating properties, etc.).

[0123] Figure 24 Illustratively shows the core advantages according to the combination of cleaning, etching, ion implantation, adhesion control, stress management, and reactive / alloy deposition. Through precise ion energy control, ultrafast pulses with a positive spike voltage reversal can remove surface contaminants, etch near-surface damage, and form a hybrid interface for a good adhesion layer to support the stress control layer, which enables the growth of the overall film through a suitable interface and overcoat.

[0124] The above operations can be performed by a single processing system (with seamless transitions from one mode to the next) to avoid downtime, manipulation, dust / particle generation (pinhole defects), and adsorbed contaminants interfering with film quality. Under high vacuum conditions of 2e-6 Torr ultimate pressure, the empirical rule is that a single monolayer of material adheres to the substrate surface in 1 second. For traditional plasma processing (with different stations for cleaning, etching, and deposition separately), a simple transfer action between stations can take as long as 30 seconds, which can result in multiple layers of contaminants and unwanted materials on the surface, which can interfere with chemical reactions, surface adhesion, and film growth.

[0125] Figure 24 An illustrative example of a continuous processing timeline 2471 is provided, which shows that a system including the present disclosure can seamlessly transition immediately between cleaning, etching, implantation, and deposition without breaking the vacuum or the platform and having a serious impact on thin film quality. The substrate 2406 to be coated is initially processed by plasma cleaning (timeline 2471t0) to remove surface contaminants 2472, where low to medium plasma and ion energy are used to break surface bonds but do not allow contaminants to enter the subsurface. The process changes at timeline 2471t1 to energetic ion etching of near-surface flaws and impurities from the existing processing step 2473, where extremely high plasma and ion energy are used to physically remove the surface layer and etch into the bulk substrate material or the underlying film coating. The process changes at timeline 2471t2 to preferentially oriented energy deposition of a metal hybrid layer 2474, where high energy ion energy is used with combined deposition / etching. The process changes at timeline 2471t3 to deposit a fully dense adhesion layer, where medium energy ions are used. The process changes at timeline 2471t4 to deposit a stress control layer 2476, where variable ion energy and pulse timing are used. The process changes at timeline 2471t5 to deposit an overall film layer 2477, where variable ion energy and pulse timing applicable to the stress control layer 2476 are used. The process changes at timeline 2471t6 for the final processing step, depositing an optional interface or diffusion barrier layer 2478 and / or overcoat 2479, where high density plasma and reactive ion bombardment are used to form a nitride layer or alloy component. For each process to achieve its technical requirements, some of the process steps outlined above can be omitted or repeated in any desired combination.

[0126] Figure 24 The scenario shown is only one example of a seamless sequence transition, and there are many different viable combinations. The key point is that there is a timing of ion energy and ion flux to the substrate such that within less than 1 second the process completely changes to a different set of parameters without introducing impurities, contaminants, particles, and artifacts from the platform.

[0127] Figure 25The exemplary display presents exemplary voltage waveform 2555 and current waveform 2558 for a -750V, 2kA peak current HiPIMS pulse, achieving 5A / cm plasma current density on a cylinder magnetron (with a copper sputtering target, +200V positive spike pulse, 125A peak current), highlighting short spike 2556 and long spike 2557. The impulse techniques described herein drive plasma generation at high dI / dt to achieve rapid ionization for subsequent voltage reversal and positive spikes to accelerate ions and plasma into the substrate to achieve cleaning, etching, preferential orientation deposition, and deposition with stress and topography control. The techniques also allow synchronization with a pulsed DC bias supply for time-window acceleration into the substrate to achieve additional control, as taught in US20180358213A1. 2 Depending on local factors (such as pre-ionization, target material, magnetic field, pressure, geometric curvature, sputtering gas, surface chemistry, adsorbed gas, etc.), the main negative pulse on voltage waveform 2555 typically ranges from -400V to -1200V. Using an ultrafast switching topology, the typical high-current pulse width is less than 100 microseconds, typically in the range of 20 - 50 microseconds. The positive spike amplitude on voltage waveform 2555 typically ranges from +0 - 600V. For users who do not want a short spike ion population to accelerate away from the sputtering target (shown in the current waveform for short spike 2556), the start delay of the positive spike will be set to: typically set at 20 - 40 microseconds after this time period. The ionization rate and plasma density near the sputtering target are highly correlated with the effective current density. The effective current density ranges from 0.1 - 10A / cm

[0128] 2

[0129] Figure 26 ​​is a photograph of a conventional planar magnetron operation where an ultrafast short main pulse is used for deposition and subsequent RF-like modulation of a positive jump pulse to generate and maintain a secondary plasma having a positive electric potential with respect to the substrate for etching. Each pulse cycle will be a combination of deposition and etching, i.e., where a copper sputtering target is used to achieve preferential orientation copper deposition, e.g., Cu(211) / Cu(111) / Cu(100). The etching parameters are adjusted to achieve preferential orientation and epitaxial growth conditions. The sputtering target 2601 processes a negative main pulse and an RF-modulated positive pulse. The dense plasma region 2613 on the racetrack is bright white-green from Cu I and Cu II optical emission lines. The central plasma region 2680 excited by positive voltage RF modulation is pink from Ar I and Ar II excitation. The central plasma region 2680 extends all the way down to the insulating substrate 2682, presenting a combination of deposition and etching surfaces 2683. The conformal plasma sheath 2681 extends down to the insulating substrate 2682. A preferentially oriented film can be deposited by using a combination of deposition and etching.

[0130] Figure 27A and 27B The photograph of highlights the super-jump mode for generating an extended plasma away from the magnetic field tip and etching on the substrate by the sample oscilloscope waveform 2786( Figure 27A )(showing 77 kHz operation), the current waveform 2758 for RF-like oscillation, and the voltage waveform 2785 of RF-like voltage application. Figure 27B The photograph in shows the bare target electrode 2701 with no bright visible emission from the racetrack. The absence of any dense plasma region indicates that target sputtering has not occurred. The bright central plasma region 2780 follows the magnetic tip into the target electrode and travels back and forth to the target electrode 2701 at a higher positive electric potential. The resulting etching plasma extends until the substrate 2784, which has a visible plasma sheath 2781 (conformal with the sample). The super-jump mode can be maintained indefinitely under a range of operating conditions for direct etching. The super-jump can also be used on the substrate in combination with a negative DC bias to achieve additional material processing flexibility.

[0131] Since we have an inverted cylinder magnetron system associated with ultrafast pulses and polarity reversal capabilities and can adjust deposition and etching conditions in real time, we turn to an integrated processing system for producing nuclear fuel and cladding material coatings. Figure 28A and 28B illustrates an on-line process in batch mode using a dedicated single inverted cylinder magnetron sputtering / etching station 2787 (which has a linear feed through multiple on-line stations) or multiple deposition / etching heads 2788 with consistent operation( Figure 28A ) or a batch manufacturing process( Figure 28B ).

[0132] Figure 29 The exemplary illustration shows a process workflow for an on-line ICM manufacturing process, suitable for processing thin film multi-layer coatings on nuclear fuel claddings. In the on-line station mode, there will be a continuous vacuum processing line with pumping and material handling between stages. Each ICM station will be optimized for a specific process, and the nuclear cladding material will be fed through each ICM station at a constant linear rate as it is continuously processed from t0, t1, t2, t3, etc. A plurality of sputtering / etching stations clean 2972, etch 2973, mix 2974, bond 2975, stress manage 2976, integrally deposit 2977, add diffusion barriers and / or interface materials 2978, and cladding layers 2979, such as reactive nitride deposition. The control parameters are customized according to the process variables identified in block 2991 to affect the thin film properties. The loader can insert one or more fuel cladding sections (which will be processed by differential pumping, baking out, and transition through the continuous timeline 2971).

[0133] There are several technical challenges regarding the continuous feeding system. One challenge is to couple each fuel cladding section, allowing independent bias voltage and current paths through each substrate, providing a way to dissipate heat from the fuel cladding without exceeding the thermal limits of the underlying ZIRLO material, and to change the structural and physical properties of the material, such as ductility, strength, stress, etc. Since the fuel cladding section is about 400 cm long and 1 cm in diameter, having a large length-to-diameter ratio, a continuous feeding adapter can be used for support, fixation, transportation, electrical connection, and fluid connection. If a 40 cm linear property only sacrifices 10% of its total processing length, there is an inherent attraction for the on-line mode. Figure 30 An exemplary continuous feeding system is shown, which has an adapter plug 3089 to feed one or more nuclear fuel cladding tubes 3006 in a continuous manner through an ICM on-line deposition / etching system for a coating 3007. The example is shown in Figure 30 where the adapter plug supports 2 connections with internal fluid transportation; multiple variations are feasible.

[0134] Variations are shown in Figure 31A and 31BAmong them, it is illustrated that an online adapter plug 3189 is used to support multiple substrates, and it is highlighted that plasma immersion and conformal deposition 3131 on multiple substrates will be formed by using an ICM (with high-density plasma generation) having a magnetic null bipolar focus. Through magnetic rotation on a sputtering target (not shown) and the plasma immersion effect from the magnetic geometry and combined with a positive jump pulse, there is sufficient open space around the substrate for conformal deposition without substrate rotation. This is useful for composite online batch processing (with 1, 3, 4, 6 or more substrates), while still utilizing the additional plasma concentration and immersion effect (on the center line) of the inverted cylinder magnetron and the ion transit time (for deposition and etching).

[0135] Figure 32 A typical process workflow is illustrated for a batch processing system on a large chamber, constructed with a traditional PVD / etching system or a large-diameter ICM device, operating asynchronously or synchronously in series connection with an ultrafast pulse and a positive jump and / or bias. Two large vacuum chambers (supporting multiple nuclear fuel cladding tubes) will be processed collaboratively in parallel using multiple sputtering electrodes for cleaning, etching, mixing, bonding, stress management, and overall deposition. For each change in the basic material type, an additional chamber is required to maintain only one main element, i.e., Nb, Cr, Mo, etc., in each large vacuum chamber. Additional special diffusion barriers, interface materials, and non-nitride coating layers may require separate chambers for cleaning and etching preparation steps before deposition to obtain high-quality films. Parameters can be controlled to affect the film properties. It is continuously processed 3271 from t0, t1, t2, t3, etc. Multiple parallel sputtering / etching units will clean 3272, etch 3273, mix 3274, bond 3275, manage stress 3276, deposit overall 3277, add diffusion barriers and / or interface materials 3278, and coating layers 3279, such as reactive nitride deposition. Parameters 3291 can be controlled to affect the film properties.

[0136] Figure 33Highlight the traditional batch substrate rotation in an extended plasma field, where large-diameter inverted cylinder magnetron cathodes operating in series / parallel are used. Multiple sputtering targets 3301 surround multiple substrates 3306 along the azimuthal direction around the centerline of the vacuum environment. Deposition and etching uniformity can be achieved by using a rotating magnetic assembly and / or the rotation of individual substrates 3392. In the case of a large-diameter chamber, the magnetic zero effect will be reduced, and the total plasma density will decrease when the power is spread over a larger space; however, the ion and neutron transit times are longer at a larger diameter, allowing for efficient ion capture using a positive jump positive potential regulation and / or a pulsed DC bias (applied directly to the substrate 3306). Ion and neutral emission 3303 will pass through the inner space of the substrate, still providing an opportunity for conformal deposition on the substrate 3306. Adding multiple ICM modules to the same vacuum chamber will allow for a higher total pulsed power for a given space and a larger area to extract power. The sputtering target raw material cost and manufacturing for the quasi-cylinder geometry are feasible.

[0137] Figure 34A and 34B Show the prior art of Cr on Zr and Zr alloy materials, where traditional DC sputtering + active substrate bias is used. Figure 34B Show the prior art of direct HiPIMS deposition of Cr coating onto M5 Zr alloy material (where active substrate bias is used). It should be noted the difference in film morphology from columnar fiber growth, where Figure 34A Show some vertical voids and grain boundary separation, Figure 34B Show a dense Cr layer on the M5 material.

[0138] Figure 35A Illustrate the cathodic arc process. Figure 35B Show the prior art of cathodic arc deposition of TiN and TiAlN multilayers for nuclear cladding coatings. Note the large number of macro-particle residues and pinhole defects on the film.

[0139] Figure 36A ,36B, 36C and 36D show the scanning electron micrographs of a 2 - 3μm thick multilayer stack separated by cracks (deposited on a specimen), where an ultrafast pulsed HiPIMS + positive jump system is used. Figure 36A is a Nb / Cr laminate (using two independent sputtering targets in a single vacuum chamber). Figure 36B is a Cr / CrN5 bilayer stack, where a single Cr sputtering target is used, the Cr layer is deposited by Ar gas, and the nitride layer is deposited by pure N2 gas. Figure 36C is a Hf / HfN5 bilayer stack, where a single Hf sputtering target is used, the Hf layer is deposited by Ar gas, and the nitride layer is deposited by an Ar + N2 mixture. Figure 36Dis a Zr / ZrN5 bilayer stack, where a single Zr sputtering target is used to deposit the Zr layer by Ar gas and the nitride layer by an Ar+N2 mixture. Attention should be paid to the ductility of the bilayer.

[0140] For cases where materials are exposed to high-temperature oxidation environments, when subjected to various extreme conditions (thermal deposition, thermal cycling, high mechanical loading) and when exposed to various environmental impacts (such as vapors, water, chemicals, salts, sand, particle erosion, etc.), the oxidation protection coating can maintain functionality and integrity. An example is nuclear fuel experiencing accident scenarios, including coolant loss, exposure to vapors, extreme temperatures, cold coolant quenching, etc. These operating conditions can lead to defects on the surface, which in the case of a single-layer coating would result in complete degradation of the coating performance and coating destruction. The accumulation and growth of defects can be stopped by thin-film structural nanolamination. In nanolaminated composite films, thin multi-layer coatings are deposited as layers such that the effective defect length scale is controlled and minimized to a small value, thereby ensuring film integrity, crack suppression, and effective management of thermal stress. These nanolaminated composite films can be used to enhance oxidation resistance in high-temperature environments, thereby enabling the use of materials that would otherwise be incompatible with high-temperature oxidation environments.

[0141] Figure 37 The prior art showing functional graded nanolayer composites that can be deposited using the present invention to achieve high-volume manufacturing with precision control and thick film stacks. For high-temperature oxidation resistance, at least two thin material layers are deposited, arranged in an alternating layer manner (ranging from 1 nm to 10 microns in thickness) to form a well-defined modulation length scale (defining the "characteristic defect length" scale). The thin material layers are small enough such that the layer periodicity magnitude is shorter than the wavelength of photons that would be emitted by blackbody spectra for radiative cooling, e.g., for a bilayer pair of 100 nm, the light wavelength is 1000 nm (10 times or less). The characteristic defect length sets the minimum crack distance before encountering another material plane and crack-stopping interface, thereby improving fracture toughness. The stopping of cracks will prevent the growth of extremely thick oxide scales (which reduces the emissivity of the material and leads to further local heating and runaway crack growth and film destruction). Smooth layers for reducing friction can be made using ultrafast HiPIMS pulses. The nanolayers allow the use of ultra-high-temperature ceramic materials selected from the group including: XB2, XO2, XN, or XF.

[0142] Figure 38The example highlights short-term cladding coatings (using metal Nb / Cr / Mo with nitride cladding layers), diffusion barriers, tensile-compressive stress management, improved fracture toughness, and thermal stress management, where a novel inverted cylinder magnetron is employed, having magnetic null trapping (for high ion trapping applications), dust particle mitigation, superior erosion control, and process stability, and impulse + jump integration (for cleaning, etching, mixing, bonding, reaction layer, and topography control). In the longer term, it is nanocomposites and functionally graded layers (spatial modulation), improved CTE matching and hoop stress management, superlattice structures (for ultra-high temperature oxidation resistance), stabilizers and diffusion inhibitors, scalability of fuel core coatings, cladding interiors for gas barrier control and wear resistance, and SiC materials.

[0143] Based on Figure 38 the concept in Figure 39 is extended,

[0144] Figure 40 Exemplary illustrations show engineered multi-layer nano / micron composite thin films. Substrate 3906 is cleaned and etched to reach the underlying bulk substrate material. A metal interface hybrid layer 3974 is introduced by combined deposition etching. Next, a fully dense adhesion layer 3975 is deposited, serving as a matrix for a ductile layer (elastic) to manage thermal expansion and mismatched CTE (coefficient of thermal expansion). An interface or diffusion barrier layer 3978 can be introduced to limit migration upon elevated temperature or galvanic potential. A crack arrest layer 3994 can be introduced to inhibit thermal shock and keep critical layers from catastrophic failure. A stress control layer 3976 can be added to manage the tensile-compressive stress and vertical stack engineering of thick films. The overall thin film layer 3977 can be introduced at multiple levels to provide the desired thickness performance. An erosion prevention 3992 and wear resistance 3993 layer can be added to achieve specific chemical resistance and hardness properties. A cladding layer 3979 can be added for lubrication and friction properties. Control of ion energy (E*) (through positive jump and impulse main pulses) and particle flux (T*) allows adjustment of the thin film microstructure and topography.The control of thin film microstructure and topography is extended by the illustration of Andre Anders' modified Thornton structure zone diagram (for overall energy condensation). For a given substrate-to-sputtering target distance, magnetic field geometry and field distribution, the adjustment of HiPIMS pulse amplitude, pulse width, timing, peak current density, repetition rate, and pressure allows the control of the main pulse particle flux (T*) (which is approximately the thermal peak). Strong short pulses with higher particle loading in a shorter time period have a high-temperature effect and allow the deposited material to equilibrate and adjust towards fibrous transition crystals (zone T), columnar crystals (zone 2), and recrystallized crystal structures (zone 3). For a given magnetic field, pointed magnetic null geometry, pressure, and available plasma from the main impulse HiPIMS pulse, the positive jump pulse amplitude, short / long jump pulses, start-up delay, and any super-jump effects (for RF-like oscillations) will allow the adjustment of the effective energy (E*) and the adjustment of thin film microstructure and topography. The basic control impulses and positive jumps allow movement everywhere on the Anders / Thornton SZD, even enabling fine-grained nanocrystalline films (with preferred orientation and low-temperature low-energy ion-assisted epitaxial growth regions) and dense amorphous glass films. Process engineering can be moved along the SZD to achieve tensile / compressive stress control, columnar growth / nanocrystals (with preferred orientation), etc.

[0145] Figure 41A and 41B The illustrative diagram shows additional figures highlighting the possibility of directly applying a HiPIMS thin film coating to nuclear fuel rod claddings and end plugs after fuel loading and welding. This has the advantage of covering the weld for protection.

[0146] Figure 42A and 42B The diagram shows the photo of a fuel cladding sample using impulse + positive jump coating, with an 8μm Nb / Cr double layer coating, flame heated in air to 1200°C for 5 minutes and then water quenched at 20°C, without delamination, spalling, or film deterioration (in addition, there is a slight oxide formation on the surface as expected).

[0147] Figure 43A and 43B The diagram shows an alternative embodiment of the present invention, where a cylindrical cathode uses a meandering magnetic continuous track (or others), with an internal moving magnet for better uniformity and less recirculation, for impulse + jump. A smaller version can be used for coating the interior of tubes, pipes, cylinders, etc. Here, the magnetic assembly 4338 is located within the target holder 4308 (integrated with the sputtering target material 4301). The magnetic assembly 4338 rotates internally 4339 to move the dense plasma region 4313 formed under the magnetic confinement zone 4329. The sputtered ions and neutrons 4303 are ejected outwards onto the coated object.

[0148] Figure 44 is a series of four scanning electron micrographs (at different magnifications) showing an 8 μm Cr / Nb coating on a reference tube (according to fabrication method #59A), showing an Nb mixing layer (to the underlying substrate 4406), an Nb stress control layer (for ductility), and an interfacial Nb layer (for Cr adhesion). The overall Cr film 4499 is completely dense, has a good microstructure, and has good adhesion to the Nb layer 4498.

[0149] Figure 45 is a series of four scanning electron micrographs (at different magnifications) showing an 8 μm Cr / Nb coating on a reference tube (according to fabrication method #59B), showing an Nb mixing layer (to the underlying substrate 4506), an Nb stress control layer (for ductility), and an interfacial Nb layer (for Cr adhesion). The overall Cr film 4599 is completely dense, has a good microstructure, and has good adhesion to the Nb layer 4598.

[0150] Figure 46 The schematic block diagram shows an exemplary example of the electrical component / circuit arrangement between a sputtering target electrode, a return electrode, a substrate, a plasma in a vacuum environment, and one or more pulsed HiPIMS pulse modules (its main and burst suppliers) and any pulsed bias pulse module suppliers. Figure 46 The schematic block diagram in outlines the general setup of a pulsed system for deposition and etching. High voltage electrical pulses are provided directly from an external pulse power module through a suitable insulated low impedance connection to the sputtering target. This allows for a low impedance electrical connection to the sputtering target holder through a rotating magnetic assembly for efficient power transfer and coupling. The pulsed modules are designed for parallel synchronous and asynchronous operation. Thus, multiple units can be pulsed in parallel to deliver the required power, rise time, plasma density, for sputtering target electrode configurations.

[0151] Figure 47Provide more details about improving deposition conformality and control (compared to the current state of the art). The overall plasma 4723 has the effect of shaping on the surface of the substrate 4706 to be coated and providing guiding ion energy quasi-orthogonal to the surface. Depending on the plasma density and the length of the effective plasma sheath 4781, the shaping of this overall plasma can be on the sub-mm length scale to achieve superior deposition conformality. The intense ultra-short pulses of the shock form extremely high plasma densities. Taking this into account, the plasma concentration effect 4731 and the magnetic nozzle / tip effect (not shown) originating from the magnetic field zero point or minimum effect cause a very high degree of ionization and a greater overall plasma density, thus causing a higher degree of conformality and ion capture efficiency 4764. The net effect of the above features is: superior control for engineering material coatings. The short spike 4768 and the long spike pulse 4769 cause a strong ion capture efficiency.

[0152] This improved ion capture efficiency 4764 and conforming sheath 4781 improve coating uniformity to enable complex parts with 3D geometries, such as turbine blades, aircraft leading edges, medical devices (such as expandable stents and coils), battery electrodes, solar materials, semiconductor devices, and so on.

[0153] Figure 48A The figure shows an illustrative example of the present disclosure, facilitating depositing a coating onto an object (such as a nuclear fuel cladding tube) and / or etching the inner surface of the object, where a magnetic structure located outside the object is used. The inner surface of the substrate 4806 is coated with ions and neutral particles 4804 originating from the sputtering target 4801 electrode, and the sputtering target electrode is biased by a voltage from a shock system (not shown). The magnetic field assembly 4838 is located outside the substrate 4806, preferably outside the vacuum environment and the cooling water, but close enough to generate a sufficient magnetic field 4812 to prompt the formation of a dense plasma 4813 within the substrate 4806 structure. In Figure 48A which, the substrate 4806 can itself be used as a return electrode for, for example, pulsed current or separated paths utilized along the axis or at the ends.

[0154] Figure 48BThe figure shows another scenario where the internal deposition and etching processes are combined with external processes. A substrate 4806 having inner and outer surfaces receives the deposition and etching of ions and neutrals 4804 from a dense plasma region 4813 (formed by a magnetic field 4812 from an external magnetic assembly 4838). The sputtering target 4801 can be pulsed synchronously, asynchronously, or in a manner that distributes ions and neutral particles 4804 with respect to a user application. For example, due to the larger surface area on the outer substrate 4801, its operating pulse frequency can be three times that of the central target 4801. The voltage, pulse width, and parameters can be adjusted to tune (over a wide range) the deposition and etching processes and the resulting outcomes. The material of the central sputtering target electrode 4801 can be different from that of the outer sputtering target 4801 to achieve different materials and applications. Exemplary internal coatings can be fission product diffusion barriers and anti-wear layers, where nuclear fuel contacts the inner wall of the cladding tube. This will be different from the external coatings (which are tailored towards oxidation resistance, high-temperature fracture toughness, and crack-resistant laminates).

[0155] Figure 49A More details are provided regarding the positive voltage reversal and subsequent RF-like oscillations in the superjump operating mode. The main negative pulse 4965 transitions to a short positive jump phase 4966 and a long jump phase 4967. The jump voltage is modulated 4985 to generate RF-like oscillations (frequency 4986). This has the effect of transferring energy to the electrons and being used to encourage ionization and generate additional plasma in the system. Depending on the positive jump voltage amplitude and local conditions, a quasi-steady-state RF plasma can be driven by this RF-like oscillation 4985 of the positive jump voltage to sustain the plasma. In one mode, the jump voltage simply turns on or off (floats), and the plasma naturally decays by diffusion. Before the oscillation changes back to its peak, the effective RF bias potential 4969 will naturally balance to play some role between the peak positive voltage and the falling voltage. The oscillation frequency allows the effective RF bias potential 4969 to be adjusted.

[0156] Figure 49B An example is shown where the frequency 4986 is lower, and the positive jump amplitude further decreases in each cycle to reduce the effective RF bias potential 4969.

[0157] Figure 49C It shows the creative modulation of the positive jump waveform (including multi-spectrum frequency components 4986) to drive a high-density plasma while maintaining a low effective RF bias potential 4969. Not shown but included for reference is the active modulation of the positive jump voltage between various set voltage set points, where a boost power module is used to define a customized voltage profile with respect to time. This is used to customize the plasma density and RF bias in each cycle or over time between multiple pulses. For example, waveform A is used for 1000 main pulses, and waveform B is used for 100 main pulses.

[0158] Figure 50A Exemplary illustrations show applications of the disclosure herein. Namely, thin film etching and deposition on particle accelerator electrodes and electromagnetic cavity structures. Figure 50A The figure shows a cross-sectional area of a four-wing radiofrequency quadrupole accelerator cavity. The four interior quadrants of this cavity are subject to strong electromagnetic fields and surface RF currents. To achieve a high acceleration gradient, extremely high electric fields are used. The quality of the surface coating in the cavity, its microstructure, and conductivity are extremely important for achieving high performance. The present disclosure, when implemented, allows for surface preparation, cleaning, etching, anvil bonding, and deposition of high-quality materials to improve performance. In this example, a sputtering target 5001 is inserted into a vacuum environment 5011 of an accelerator cavity substrate 5006. A magnetic field 5012 is generated within a magnetic assembly 5038 of the sputtering target 5001, and the magnetic field 5012 generates and sustains a dense plasma region 5013 required to generate ions and neutrals 5004 that are being deposited onto the substrate 5006.

[0159] Figure 50B The photograph shows four sputtering targets 5001 located within an accelerator cavity structure substrate 5006. The dense plasma region 0513 is clearly visible within the vacuum environment 5011. Highly conductive copper with a dense nanocrystalline structure can be deposited with a super-smooth surface roughness to withstand high electric field gradients. The nanocrystalline texture resists whisker growth on slip planes that would cause surface electric field concentration and ignition at high gradients. The present disclosure remedies this problem. Additionally, the present invention can also be used for superconducting films and layers, such as Nb, Nb / NbN, and the like. Using shock and positive jump and aspects of the present invention, the film morphology and crystallinity are controlled to achieve preferred crystal orientation, grain size, lattice plane matching, surface toughness, and other parameters that are beneficial for superior residual resistivity quantification, current density, and magnetic properties.

[0160] Figure 51A and 51B are photographs of a shock 2-2 system and a shock 20-20 system (used as power supplies in the systems described herein in the embodiments of the present disclosure).

[0161] All references cited herein (including publications, patent applications, and patents) are hereby incorporated by reference as if each reference were specifically and individually indicated to be incorporated by reference and were set forth in full herein.

[0162] In the context of describing the application environment of the present invention (especially in the application environment of the appended claims), the use of the expressions "a", "an", and "the" and similar referents should be understood to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by the context of application. The expressions "comprising", "having", "including", and "containing" should be understood as open-ended expressions (i.e., meaning "including but not limited to"), unless otherwise indicated. The ranges of values described herein are only intended to be used as a convenient way to separately refer to each individual value falling within the range, and unless otherwise indicated herein, each individual value is incorporated into the specification as if it were described separately herein. All methods described herein can be performed in any suitable order, unless otherwise indicated herein or clearly contradicted by the context of application. Any and all examples or exemplary language provided herein (e.g., "such as") are only intended to better illustrate the present invention and are not intended to limit the scope of the present invention, unless otherwise defined. The language in the patent document should be understood as: not identifying any unclaimed element as an essential element for practicing the present invention.

[0163] Exemplary embodiments known to the inventors are described herein for practicing the present invention. Variations of these embodiments will become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect those skilled in the art to employ such variations when appropriate, and the inventors intend for the present invention to be practiced otherwise than as specifically described herein. Accordingly, the present invention includes all modifications and equivalents of the subject matter defined in the appended claims as permitted by applicable law. Additionally, any combination of the above elements in all possible variations is covered by the present invention, unless otherwise indicated herein or clearly contradicted by the context of application.

Claims

1. A system, comprising: A sputtering target, formed in the shape of a cylinder or quasi-cylinder and made of sputtering target material, such that ions from a dense plasma region impinge on the sputtering target to generate sputtering ions and neutrals that are incident on a substrate; A magnetic element array, comprising multiple sets of permanent magnets, the multiple sets of permanent magnets being arranged to have a Hall effect region extending along the length of the sputtering target; Wherein, an elongated sputtering electrode material tube is interposed between the magnetic array and an object on which sputtering material from the sputtering target is to be deposited; Among them, the effective current density of the plasma is in the range of 0.1 - 10 A / cm 2 ; Wherein, during the plasma magnetron discharge operation, the system is configured to generate and control an ion and neutral particle flux to modify the surface of the object in the following manner: Providing a vacuum device that includes a sputtering target holding electrode; First generating a high-power pulsed plasma magnetron discharge with a high-current negative direct current (DC) pulse to the sputtering target holding electrode; After terminating the negative DC pulse, second generating a configurable positive voltage jump pulse to the sputtering target holding electrode; The magnetic element array is physically arranged along a continuous meandering path; Wherein the continuous meandering path includes a steering configuration magnetic assembly, and the steering configuration magnetic assembly is magnetically adjusted to produce a desired change in the magnetron discharge plasma density relative to the center line of the continuous meandering path.

2. The system according to claim 1, wherein, During the second generation process, a logic circuit configured by a program processor issues a control signal to a positive jump pulse power transistor to control the jump pulse performance of a maintained positive voltage jump pulse taken from the group including: start-up delay, amplitude, and duration.

3. The system according to claim 1, wherein, The magnetic array and the sputtering target rotate relative to each other along a common length axis.

4. The system according to claim 1, wherein, The magnetic element array is arranged to form a magnetic zero or minimum on the center line of the cylinder structure of the sputtering target.

5. The system according to claim 1, wherein, The system is configured to further perform a continuous composite production process, including a layer deposition operation and an etching process operation, and the continuous composite process is performed under the following circumstances: Without removing the object from the chamber within the system; By changing the timing and / or amplitude of the pulses during the first generation operation and / or the second generation operation.

6. The system according to claim 1, wherein, During the plasma magnetron discharge operation, the system is configured to apply a DC or pulsed bias to the object.

7. The system according to claim 1, wherein, The sputtering target includes: an elongated sputtering electrode material tube.

8. The system according to claim 1, wherein, The system is configured to generate and control an ion and neutral particle flux during a DC high-power pulsed magnetron sputtering operation to modify the surface of the object in the following manner; First generating a high-power pulsed plasma magnetron discharge with a high-current negative direct current (DC) pulse to the sputtering target holding electrode; After terminating the negative DC pulse, second generating a configurable positive voltage jump pulse to the sputtering target holding electrode.

9. The system according to claim 1, wherein, the magnetic element array is located outside the vacuum environment.

10. The system according to claim 1, wherein, a magnetic package including the magnetic element array is immersed in a liquid coolant in the vicinity of the sputtering target and any target holder.

11. The system according to claim 1, wherein, the magnetic element array includes one or more circular, rectangular, or other continuous loops to generate a magnetic field on the sputtering target.

12. The system according to claim 1, wherein, a plurality of cylinder sputtering zones are provided to deposit successive layers of a specific material, alloy, or ceramic, thereby providing continuous on-line production.

13. The system according to claim 1, wherein, high voltage electrical pulses are provided to the sputtering target through an insulating and low impedance connection.

14. The system according to claim 1, wherein, the sputtering target includes a plurality of separate sections, and each of the sections is connected to form a quasi-cylindrical shape.

15. The system according to claim 1, wherein, less than 33% of the surface of the sputtering target is covered with plasma.

16. The system according to claim 1, wherein, the effective HiPIMS instantaneous coverage rate on the surface of the sputtering target is 33 - 50%.

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