Cr Adhesion Layer Research Articles

PVD Coatings for Lightweight Bipolar Plates

Bipolar plates are one of the main components of proton exchange membrane fuel cells (PEMFCs). Their functions include distributing reactants, supporting the cell, and conducting heat and electricity. They account for a significant proportion of the fuel cell stack’s weight and volume. The main materials currently used for bipolar plates are graphite and stainless steel. Aluminium has a much lower density than steel and is easier to form than both steel and graphite. Its use, therefore, would allow fuel cells with higher power densities but is hindered due to it being prone to corrosion. This work focused on the development of corrosion-resistant and conductive coatings to address this issue. Carbon coatings with Ti and Cr adhesion layers were deposited on aluminium substrates using closed-field unbalanced magnetron sputtering. These coatings were tested for corrosion properties and performance on the cathode side of a single-cell fuel cell. Coated aluminium samples were also tested for their ability to maintain their corrosion protection after being formed. Coating with a Cr adhesion layer outperformed that with a Ti adhesion layer in both forming and fuel cell tests, demonstrating much lower performance degradation after accelerated stress testing.

Plasmonic sensing: FDTD calculations to interpret experimental LSPR water adsorption isotherms

Finite-Difference Time-Domain (FDTD) calculations are widely used to interpret experimental Localized Surface Plasmon Resonance (LSPR) spectra. With FDTD it is possible to predict the physical parameters of the nanostructures that will theoretically give the best experimental LSPR signals. This information is crucial for optimizing sample fabrication and saving significant time. FDTD is also essential to control and calibrate various parameters of the nanostructures and to understand effects such as a Cr adhesion layer and LSPR sensor size distribution. Finally, for water adsorption sensing, FDTD confirms that the LSPR peak shift strictly follows Campbell’s model, even at submonolayer coverage.

Formation of Cu Nanotwins on Silicon Carbide Wafers with Cr Adhesive Layer under Various Substrate Bias

This study focuses on the analyses of nano-twinned copper (Cu) films deposited through magnetron sputtering on silicon carbide (SiC) chips. The investigation encompasses the utilization of a chromium (Cr) adhesive layer coupled with varying voltage bias conditions. The goal is to comprehensively examine the influence of the adhesive layer and negative bias voltages, contributing to an enhanced understanding of materials engineering and bonding technologies for advanced applications. The formation of a nano-twinned structure and (111) surface orientation can be properly controlled by applied substrate bias. High-density nanotwinned structures were introduced into Cu films sputtered on SiC substrates with 82.3% of (111) orientation proportion at −150 V, much higher than the Cu film sputtered with another substrate bias. It is concluded that the sputtered Cu nanotwinned film formed with −150 V bias voltage has the potential to be employed as the interlayer for low-temperature direct bonding.

Patterned Adhesion Layer Enables Rugged Pd-MIS Hydrogen Sensors.

Rugged Pd-metal-insulator-semiconductor (Pd-MIS) hydrogen sensors for detecting charge-exchange particles in fusion reactors have been constructed by utilizing a novel patterned adhesion layer. Poor adhesion at the interface between Pd and SiO2 is a common failure mode for Pd-MIS devices, severely limiting the Pd thickness and their usefulness as hydrogen sensors. The mechanical integrity of the Pd coatings is of particular importance in magnetic fusion energy research where the Pd-MIS diodes are used to measure hydrogen charge-exchange neutral fluence at the wall in tokamaks. In this application, particularly thick Pd contacts are desirable to prevent damage caused by high-energy particles; however, such thick Pd coatings are prone to mechanical failure due to blistering and wire bond detachment during construction or operation. A continuous Ti or Cr adhesion layer is not possible for this application since it would interfere with H uptake at the SiO2 interface, which is essential for the device to generate a response. In this work, we demonstrate that a patterned Cr interlayer substantially improves adhesion while still providing access for hydrogen to reach the SiO2-Pd interface.

Highly elastic hard PECVD TiSiC:H/a-SiC:H coatings with enhanced erosion and corrosion resistance: The trampoline effect

Advanced protective coatings providing high resistance to solid particle erosion as well as corrosion require system designs that combine the controlled dissipation of impact energy with the suppressed diffusion of corrosive media. In the present work, we propose and investigate a coating architecture benefiting from a “trampoline” energy-damping effect in which a hard TiSiC:H layer on top of an elastic a-SiC:H underlayer is prepared by plasma enhanced chemical vapor deposition on aerospace-grade titanium (Ti6Al4V) alloy and stainless steel 410 (SS410) substrates provided with a Cr adhesion layer. In the first part of the work, we study the effect of hydrogen in the individual a-SiC:H films (determined by elastic recoil detection) on their morphology (using scanning electron microscopy) and the mechanical and tribological properties. The films exhibit a highly advantageous combination of properties such as high hardness (>20 GPa), high elastic recovery of up to 80%, low friction coefficient (μ = 0.15 against alumina counterpart), and excellent resistance to plastic deformation and elastic resilience, expressed by the hardness (H), reduced Young's modulus (Er), and the H/E, H3/Er2, and H2/Er ratios. In particular, the measured elastic strain-to-failure of the coatings reached an unusually high value of H/Er > 0.2, thus exceeding the super-elastic limit. Simultaneously, the a-SiC:H films provided an excellent corrosion and wear protection documented by a corrosion current that was found 103–104 times lower and a wear rate that was 34 times lower compared to the values for the bare SS410 substrate. When a top TiSiC:H layer (H = 30 GPa) was applied to complete a total thickness of 25 μm, the TiSiC:H/a-SiC:H system reduced the solid particle erosion rate (Al2O3 microparticles 50 μm in diameter, speed of 36 m/s, and 90° impact angle) by a factor of 37 for films exhibiting a composite H/E ratio of 0.26. The results of the present work show that hard and highly elastic a-SiC:H-based multilayer coating systems with selectively controlled mechanical, tribological, and corrosion properties are promising candidates for the protection of metallic materials in harsh environments.

Sensitivity Enhancement of Hybrid Two-Dimensional Nanomaterials-Based Surface Plasmon Resonance Biosensor.

In this work, we designed structures based on copper nanosubstrate with graphene and two-dimensional transition metal dichalcogenides (TMDC) in order to achieve an ultrasensitive surface plasmon resonance biosensor. This system contains seven components: SF11 triangular prism, BK-7 glass, Chromium (Cr) adhesion layer, thin copper film, layers of one of the types of transition metal dichalcogenides: MoS2, MoSe2, WS2 or WSe2 (defined as MX2), graphene, sensing layer with biomolecular analyte. Copper was chosen as a plasmonic material because it has a higher conductivity than gold which is commonly used in plasmonic sensors. Moreover, copper is a cheap and widespread material that is easy to produce on a large scale. We have carried out both theoretical and numerical sensitivity calculations of these kinds of structures using the Goos–Hänchen (GH) shift method. GH shift is lateral position displacement of the p-polarized reflected beam from a boundary of two media having different indices of refraction under total internal reflection condition and its value can be retrieved from the phase change of the beam. The SPR signal based on the GH shift is much more sensitive compared to other methods, including angular and wavelength scanning, due to much more abrupt phase change of the SPR reflected light than its intensity ones. By optimizing the parameters of the SPR sensing substrate, such as thickness of copper, number of layers of 2D materials and excitation wavelength, we theoretically showed an enhanced sensitivity with a detection limit 10−9 refractive index unit (RIU).

Development of the micro-RWELL discs for the CMD-3 detector

The CMD-3 is general purpose detector at the VEPP-2000 electron–positron collider at Budker Institute of Nuclear Physics. CMD-3 is intended to measure parameters of light vector mesons and main hadronic cross sections with accuracy better than 1% and study dynamics of multihadron production. In order to increase geometrical acceptance for charged particles and to improve precision of track polar angle measurements the end-cap discs based on micro-resistive-WELL (μ-RWELL) structures are proposed for the upgrade of the CMD-3 tracking system. Two μ-RWELL discs 50 cm in diameter were assembled and tested. The discs have two-layer readout structure with the top layer of quarter-rings with 2 mm pitch in radius and the bottom layer of sectors with average angular pitch of about 0.3 degrees. The quarter-rings occupy only 50% of the disc surface due to gaps between them, thus, allowing the signal to be induced on the bottom layer. The kapton foil with copper layer on top and high-resistivity DLC layer at the bottom, pierced with 80 micron diameter holes located at 140 micron from each other, is glued on top of the readout structure. With the first disc the manufacturer (CERN advanced PCB Workshop) could not reach proper insulation between the copper layer and the DLC and the copper was etched out leaving the disc with thin Ni–Cr adhesion layer on top. The second disc has copper layer on top of the μ-RWELL structure. The readout structure of the discs is connected to front-end electronics based on VMM3a ASICS. The results of study of the main parameters of the detectors with front-end electronics are reported in the paper.

Study of interface reaction in a B4C/Cr mirror at elevated temperature using soft X-ray reflectivity.

Boron carbide is a prominent material for high-brilliance synchrotron optics as it remains stable up to very high temperatures. The present study shows a significant change taking place at 550°C in the buried interface region formed between the Cr adhesive layer and the native oxide layer present on the silicon substrate. An in situ annealing study is carried out at the Indus-1 Reflectivity beamline from room temperature to 550°C (100°C steps). The studied sample is a mirror-like boron carbide thin film of 400 Å thickness deposited with an adhesive layer of 20 Å Cr on a silicon substrate. The corresponding changes in the film structure are recorded using angle-dependent soft X-ray reflectivity measurements carried out in the region of the boron K-edge after each annealing temperature. Analyses performed using the Parratt recursive formalism reveal that the top boron carbide layer remains intact but interface reactions take place in the buried Cr-SiO2 region. After 300°C the Cr layer diffuses towards the substrate. At higher temperatures of 500°C and 550°C the Cr reacts with the native oxide layer and tends to form a low-density compound of chromium oxysilicide (CrSiOx). Depth profiling of Si and Cr distributions obtained from secondary ion mass spectroscopy measurements corroborate the layer model obtained from the soft X-ray reflectivity analyses. Details of the interface reaction taking place near the substrate region of boron carbide/Cr sample are discussed.

Precision fabrication of diamond micro-optic elements with hybrid SiO2/Cr etching masks

Diamond is opted for high-power optical systems due to excellent optical transparency, radiation, and thermal resistance, while the fabrication of micro-structures on diamond falls behind. Here we report a reliable fabrication method of diamond and fabricate a laminar grating with 2.90 μm period and 3.08 μm groove depth by directly laser writing(DLW) and reactive ions etching (RIE). We presented a micro-masks-less and high-temperature hybrid masks of diamond etching with dielectric SiO2 mask and Cr adhesive layer. We developed a statistical analysis method using Hough transform on SEM images, which could provide the quantitative results and monitor the variation of structures during fabrication process. The grating presents 28% diffraction efficiency in the 0th order and 9% in the ±1st order at 405 nm wavelength. The results of diffraction experiment are in close agreement with the rigorous coupled wave (RCWA) simulation.

Migration of adhesive material in electrostatically actuated MEMS switch

Microelectromechanical systems (MEMS) switches are attractive for many applications including radio frequency and microwave systems, logic devices, acceleration sensing and electric protection. However, low reliability limits the introduction of these devices into the commercial use. For two decades of research, many reliability issues have been successfully overcome, but some aspects have received little attention. The paper describes a failure mechanism of electrostatically actuated MEMS switch related to the migration of adhesive material in a dielectric substrate. The phenomenon is demonstrated for the device with Au and Pt electrodes deposited on Cr adhesion layer. After 102–105 working cycles, nanoscale structures consisting of Cr and C appear at the gate. The structures grow and coalesce into micron-sized formations that touch the beam during actuation and cause stiction or short circuiting. The material transfer takes place not only in the gap between the electrodes, but also around the gate and its connecting line, where Cr and C agglomerate into spots and droplets. In addition, the adhesive material migrates under the Au and Pt films, causing the delamination of electrodes from the substrate. A possible explanation of the described effect is the drift of Cr at the SiO2 surface under electric field. Chromium is widely used in microtechnology, but the field-induced migration was not reported previously. To all appearance, it became possible due to the features of the fabrication process. The conditions for the migration must be clarified in order to avoid this reliability issue for MEMS switches of various types and other microfabricated devices.

A new spalling mechanism of intermetallics from the adhesion layer in the terminal-stage reaction between Cu and Sn

Three-dimensional integrated circuits provide a promising approach to extend Moore's law by vertically stacking multiple functional chips with microbumps. However, with miniaturization, depletion of the wetting layer of under bump metallurgy becomes a worrisome possibility. Upon depletion of the wetting layer, the adhesion layer will be directly exposed to intermetallics at the terminal stage of solid-state reactions. In this study, the resulting spalling phenomenon is investigated for the first time. The microstructure evolution of ultrathin Cu–Sn microbumps shows that spalling of Cu6Sn5 and Cu3Sn from the Cr adhesion layer occurs when Cu is depleted. The driving force for spalling is the high interfacial energy between intermetallics and the Cr adhesion layer. To prevent such spalling, which deteriorates the integrity of the bumps, the Cu wetting layer must be at least 1.3 times thicker than that of Sn.

Measurement of Effects of Different Substrates on the Mechanical Properties of Submicron Titanium Nickel Shape Memory Alloy Thin Film Using the Bulge Test.

This study investigated the effects of different substrates on the mechanical properties of Ti-60at%Ni shape memory alloys (SMA). Two types of samples were prepared for this experiment: (1) a Ti-60at%Ni deposited on SiNx, and (2) a Ti-60at%Ni deposited on SiNx/Cr; both had a 600 nm thick film of Ti-60at%Ni. Deposition was done using the physical vapor deposition (PVD) process, and the microstructural changes and crystallization phase changes were observed through scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results showed that the TiNi thin film with a Cr adhesion layer had better mechanical properties. The bulge test showed that TiNi thin film with a Cr adhesion had a higher Young’s modulus and lower residual stress. From the thermal cycling experiment, it was found that the Cr adhesion layer buffered the mismatch between TiNi and SiNx. Additionally, the thermal cycling test was also used to measure the thermal expansion coefficient of the films, and the fatigue test showed that the Cr layer significantly improved the fatigue resistance of the TiNi film.

Edge-Directed LTPS Via Flash Lamp Annealing Using a Cr Adhesion Layer for Improved Wettability

Flash lamp annealing (FLA) has been explored as an alternative to excimer laser annealed low-temperature polycrystalline silicon (LTPS) for display applications and has shown potential to streamline and decrease the cost of fabrication while maintaining electrical performance [1], [2]. In this method, amorphous silicon is exposed to a single pulse of light emitted from a xenon flash lamp, causing melting and recrystallization in an area of cm2 rather than nm2 in less than a millisecond. FLA has shown value in crystallizing silicon and activating dopants in both PFET and NFET thin-film transistors (TFTs) [3]. However, FLA suffers from inconsistent material uniformity, a consequence of large areas of silicon melting simultaneously. This can cause the molten silicon to de-wet from the oxide or nitride underlayer, leading to the formation of numerous randomized voids. Though previous studies have shown encouraging results when using this void-associated LTPS morphology, improved structure control is necessary to reduce the variance of FLA-LTPS device operation.Edge-directed LTPS has a distinctly different macroscopic morphology than the void associated material, with potential advantages in uniformity and electrical performance. Differences between these morphologies have been previously discussed [4], however in that work the realization of the edge-directed material was hardly intentional and the formation mechanism was not clearly determined. A repeatable and controllable method of producing edge-directed LTPS would effectively solve a key obstacle towards industrial integration of FLA, that of randomly-dispersed irregularities and material nonuniformity.In this work, a replicable morphology of FLA-LTPS is produced and analyzed by using a thin chromium underlayer to promote adhesion without rendering the silicon entirely conductive. With thickness reduced to < 10 nm, Cr does not absorb damaging amounts of energy from the FLA pulse, as opposed to other metal and ceramic layers, which could improve wettability. Chrome has been applied as a silicon underlayer in thin-film photovoltaic applications [5]. The result of this Cr adhesion layer beneath an a-Si mesa during FLA is a characteristic ridge-like pattern of grain formation, as shown in Figure 1A. Large, elongated domains oriented perpendicular to the edges of the silicon mesas are clearly visible. An abrupt ridge is seen equidistant between the long edges of this mesa, with further diagonal ridges present at a 45° angle from the corners. This structure suggests a propagation of crystallization that begins at the edge of the mesas and travels inwards, terminating when it reaches another advancing crystallization front. This structure is only realized when the Cr layer is a continuous film rather than discrete microparticles, suggesting that the effect is due to adhesion rather than metal-induced crystallization. Without this adhesion layer, the randomly-irregular structure seen in Figure 1B is produced. Figure 1C demonstrates atomic force microscopy on this ridge morphology. In this structure, a maximum height differential of around 55 nm between the tops of ridges and the lowest point on the mesa is demonstrated (ignoring scanning artifacts). This is significant, as the original thickness of amorphous silicon as deposited was only 60 nm, suggesting large-scale mass transfer during crystallization. However, dewetting behavior is minimized. The elongated structure, lack of voids, and edge-inward pattern of this morphology is hypothetically consistent with explosive crystallization [6], versus a quasi-equilibrium melt-phase which results in randomly-irregular material.Similar morphology has been demonstrated using excimer laser and continuous-wave laser annealing, in which only a small area of silicon is in liquid phase at any given moment [7], [8]. However, its formation in FLA, in which large areas are melted simultaneously, is an important step towards the commercial viability of flash lamp annealing. This polycrystalline material is being explored as a viable channel material for PFET TFTs. The apparent presence of micrometer-scale grains is expected to improve channel mobility [9], while providing a uniform and predictable structure, thus minimizing variance in device operation. Material properties and electrical characteristics will be presented. Figure 1

Enhancing Thermal Interface Conductance to Graphene Using Ni-Pd Alloy Contacts.

To identify superior thermal contacts to graphene, we implement a high-throughput methodology that systematically explores the Ni-Pd alloy composition spectrum and the effect of Cr adhesion layer thickness on thermal interface conductance with monolayer graphene. Frequency domain thermoreflectance measurements of two independently prepared Ni-Pd/Cr/graphene/SiO2 samples identify a maximum metal/graphene/SiO2 junction thermal interface conductance of 114 ± (39, 25) MW/m2 K and 113 ± (33, 22) MW/m2 K at ∼10 at. % Pd in Ni-nearly double the highest reported value for pure metals and 3 times that of pure Ni or Pd. The presence of Cr, at any thickness, suppresses this maximum. Although the origin of the peak is unresolved, we find that it correlates with a region of the Ni-Pd phase diagram that exhibits a miscibility gap. Cross-sectional imaging by high-resolution transmission electron microscopy identifies striations in the alloy at this particular composition, consistent with separation into multiple phases. Through this work, we draw attention to alloys in the search for better contacts to two-dimensional materials for next-generation devices.

Determining effective crack lengths from electrical measurements in polymer-supported thin films

Although it is evident that the formation of multiple through-thickness cracks in polymer-supported thin films leads to an increase of the electrical resistance, the attempts to quantify the dependence of resistance growth only based on the induced crack density have not yet been successful. In this paper a recently developed relationship, representing the resistance growth as a two-variable polynomial function of crack density and crack length, is utilized to analyze the crack patterns induced by monotonic and cyclic tensile loading of 250 nm thick Cu films with a 10 nm Cr adhesion layer on polyimide. It is demonstrated that by knowing the in-situ resistance during deformation and post-mortem linear density of induced cracks, it is possible to extract the effective crack lengths, a parameter which is often ignored during experimental characterization of the damage induced through mechanical loading. The described algorithm is not only much more cost-effective in comparison to time-consuming in-situ microscopy methods, it also reflects the reliability of the whole sample rather than of only selected surface areas.

PtIr protective coating system for precision glass molding tools: Design, evaluation and mechanism of degradation

During Precision Glass Molding (PGM), the molding tools have to withstand severe thermo-chemical and thermo-mechanical loads cyclically. To protect their high-quality surface against degradation and increase their service lifetime, protective coatings are applied on the molding tools. In this work, we designed four different PtIr protective coating systems, where the thickness of the PtIr layer and the adhesion layer were varied. Their lifetimes were evaluated and compared using an in-house built testing bench. Among all the studied coating systems, the protective coating, which consists of a 600-nm-thick PtIr layer and a 20-nm-thick Cr adhesion layer, showed the best durability. To understand the degradation mechanism of the coating during actual engineering production, an industrial PGM machine was used and emulation PGM tests were conducted. Detailed sample characterization was performed using an array of complementary techniques including white light interferometry (WLI), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), scanning transmission electron microscopy (STEM) and atom probe tomography (APT). Phenomena such as interdiffusion, oxidation, coating spallation and glass sticking on the coating were observed and are discussed in the context of optimization of the coating's performance and durability.

Mitigation of Long Whisker Growth Based upon the Dynamic Recrystallization Mechanism

The role of an Fe layer under a Sn layer to mitigate long whisker formation by the Fe/Sn interface through modification of the driving force for dynamic recrystallization (DRX) has been studied using a laboratory test vehicle with a Si (wafer) base material and evaporated layers of Cr (adhesion layer), Fe, and Sn. The latter two layers had thickness combinations of 10 nm Fe/0.5 μm Sn and 40 nm Fe/2.0 μm Sn. Aging was carried out for 9 days at temperature of 25°C, 60°C, and 100°C under stress conditions. Applied loads of 0 g or 500 g compression did not affect the results. Industrial test vehicles including electroplated layers of Sn and Fe (0.5 μm to 2.0 μm) were subjected to the same aging treatments. The absence of long whiskers and hillocks from the laboratory test vehicles indicated that the Fe/Sn interface altered the driving force of DRX rather than altering grain boundary mobility. The presence of depleted zones confirmed that the Fe layer did not affect the long-range diffusion. The industrial test samples showed that the Fe/Sn interface prevented the formation of long whiskers on the electroplated Sn films for similar aging conditions. The Fe layer provided a suitable barrier against Cu diffusion into the Sn layer. Copper in the Sn layer, even when only in solid solution, enhanced the DRX driving force for whisker growth.

Influence of ultrathin chromium adhesion layer on different metal thicknesses of SPR-based sensor using FDTD

Chromium (Cr) layer with ultrathin thickness plays significant role as adhesion layer to attach the prism with various metallic materials in a Surface Plasmon Resonance (SPR) sensor. In this research, the presence of fixed 0.5nm Cr adhesion layer has been investigated to evaluate its influence to reflectivity, resonance angle (θRes) and full-width at half maximum (FWHM) for different thickness of Gold (Au), Silver (Ag) and Copper (Cu) in the range of 20-60nm using finite-difference-time domain (FDTD) analysis. The results show the intensity of the maximum reflectivity (Rmax) decreased to 3-5% and the minimum reflection intensity (Rmin) changed from 2-14% depending on the thickness of the metallic layer. The lowest Rmin for each metals contributed by the presence of Cr adhesion layer was 6.06% 40nm Au, 11.7% 30nm Ag and 0.26% 40nm Cu. However, the resonance angle is almost same for all metals without influenced by the presence of ultrathin Cr adhesion layer. The optimum thickness of 50nm Au shows the same and highest sensitivity by 80.56°RIU for structure I and II. The FWHM increased when Cr adhesion layer exist and broadens the SPR curve. Therefore, the ultra-thin chromium layer has influenced the performance of the SPR sensor and highly dependent on the thickness of the metal.

Optimization of Mo/Cr bilayer back contacts for thin-film solar cells.

Molybdenum (Mo) is the most commonly used material as back contact in thin-film solar cells. Adhesion of Mo film to soda–lime glass (SLG) substrate is crucial to the performance of solar cells. In this study, an optimized bilayer structure made of a thin layer of Mo on an ultra-thin chromium (Cr) adhesion layer is used as the back contact for a copper zinc tin sulfide (CZTS) thin-film solar cell on a SLG substrate. DC magnetron sputtering is used for deposition of Mo and Cr films. The conductivity of Mo/Cr bilayer films, their microstructure and surface morphology are studied at different deposition powers and working pressures. Good adhesion to the SLG substrate has been achieved by means of an ultra-thin Cr layer under the Mo layer. By optimizing the deposition conditions we achieved low surface roughness, high optical reflectance and low sheet resistivity while we could decrease the back contact thickness to 600 nm. That is two thirds to half of the thickness that is currently being used for bilayer and single layer back contact for thin-film solar cells. We demonstrate the excellent properties of Mo/Cr bilayer as back contact of a CZTS solar cell.

Contamination-Free Graphene Transfer from Cu-Foil and Cu-Thin-Film/Sapphire

The separation of graphene grown on metallic catalyst by chemical vapor deposition (CVD) is essential for device applications. The transfer techniques of graphene from metallic catalyst to target substrate usually use the chemical etching method to dissolve the metallic catalyst. However, this causes not only high material cost but also environmental contamination in large-scale fabrication. We report a bubble transfer method to transfer graphene films to arbitrary substrate, which is nondestructive to both the graphene and the metallic catalyst. In addition, we report a type of metallic catalyst, which is 700 nm of Cu on sapphire substrate, which is hard enough to endure against any procedure in graphene growth and transfer. With the Cr adhesion layer between sapphire and Cu film, electrochemically delaminated graphene shows great quality during several growth cycles. The electrochemical bubble transfer method can offer high cost efficiency, little contamination and environmental advantages.