Slow Ramp Rate Research Articles

Rapid Sintering of Inkjet Printed Cu Complex Inks Using Laser in Air

Cu complex inks offer a facile and cost-effective alternative to commercial nanoparticle inks for printed electronics application. Cu complex inks are prepared by mixing Cu formate tetrahydrate (metal precursor) with amino-2-propanol (complexing agent) in a molar ratio of 1:2. A carrier solvent consisting of ethanol and ethylene glycol is then added to help adjust the rheological properties of the ink for printing purpose. The Cu complex ink having a viscosity of 12 mPa.s is then inkjet printed onto a polyimide substrate (thickness: 125 μm). After printing 10 layers, the ink is pre-dried under air at 100°C for 5 minutes followed by sintering using an IR laser (942 nm) to enable rapid thermal decomposition of the Cu formate. After sintering using a 100 W line beam laser scanned at 3 mm/sec under air; a contiguous and homogenous Cu metallic trace is formed with a minimum bulk resistivity of 4.8 μΩcm (2.84 times of bulk Cu). The laser sintered trace exhibited a highly compact and homogenous sintered structure after thermal decomposition compared to the conventional oven sintering process. Th result is remarkable and proves the importance of faster decomposition process. In contrast, sintering the same trace using slow ramp rate within the traditional oven sintering pr process, it is observed that a Cu metallic trace is formed with particles in the range of 2-5 μm that are sparsely distributed due to low metal content of Cu complex inks (< 10 metal wt.%). Due to sparse distribution of particles, a low bulk resistivity value of 102 μΩcm is obtained.

Novel Low Temperature and Low Pressure Sintering of ADAS Radar Sensor Antenna Stack

A low temperature and low pressure sintering of antenna stacks with the promising prospect of achieving a single step bonding process of multi-layer wave guide antennas for automotive radar sensors is demonstrated. Silver nanoparticles (Ag-NP) paste with the ability to sinter at 200°C in air allows for easy integration into standard surface mount device reflow process. The paste drying and sintering process of the Ag-NP paste is first optimized using dummy test chips to reduce the typical voiding and channeling in the interconnect when sintered without pressure. In especially, a slow ramp rate with an integrated predrying step is applied after placement of the test chips into the wet paste. Afterwards, the process is transferred to the antenna. However, pre-existing bending in the large antenna layers challenges the sintering process without pressure, e.g. larger amounts of paste need to be applied for compensation of the bending. Therefore, the use of a low bonding force in observed to improve the quality of the sintered interfaces. Near bulk like Ag sintered interconnects were realized.

Murchison Meteorite Analysis Using Tetramethylammonium Hydroxide (TMAH) Thermochemolysis Under Simulated Sample Analysis at Mars (SAM) Pyrolysis‐Gas Chromatography‐Mass Spectrometry Conditions

AbstractThe Sample Analysis at Mars (SAM) instrument aboard the Curiosity Rover at Gale crater can characterize organic molecules from scooped and drilled samples via pyrolysis of solid materials. In addition, SAM can conduct wet chemistry experiments which enhance the detection of organic molecules bound in macromolecules and convert polar organic compounds into volatile derivatives amenable to gas chromatography‐mass spectrometry analyses. Specifically, N‐tert‐butyldimethylsilyl‐N‐methyltrifluoroacetamide (MTBSTFA) is a silylation reagent whereas tetramethylammonium hydroxide (TMAH) is a thermochemolysis methylation reagent. Shortly after arriving at Mars, the SAM team discovered that at least one of the MTBSFTA cups was leaking, contributing to a continuous background inside SAM with the potential to interfere with future TMAH reactions. Therefore, here we characterized possible interactions between the two reagents to determine byproducts and implications for the detection of indigenous organics. SAM‐like pyrolysis experiments supplemented with flash pyrolysis were accordingly conducted with fragments of the Murchison meteorite as a reference for exogenous organic matter delivered to Mars. Flash TMAH experiments yielded various aromatic acids, dicarboxylic acids, and amino acids while SAM‐like pyrolysis presented mixtures of methylated and non‐methylated compounds due to decreased reaction efficiency at slower ramp rates. All experiments in the presence of simulated MTBSTFA vapor produced pervasive silylated byproducts which co‐elute and obscure the identification of Murchison‐derived compounds. Despite challenges, a significant diversity of pyrolyzates and TMAH derivatives could still be identified in flash pyrolysis in presence of MTBSTFA. However SAM‐like experiments with TMAH and MTBSTFA are hindered by both decreased methylation yields and additional co‐eluting compounds.

From Independent to Related: Voltage Ramp Rate Effects on Self-Healing Scaling in Metallized Polypropylene Film Capacitors

Metallized polypropylene film capacitors (MPPFCs) are well-suited for high-frequency and high-electric-field applications, such as electric vehicles, aerospace, and pulsed power systems, due to their self-healing (SH) properties. However, the SH process is affected by operating conditions such as voltage level and ramp rate. It is not well understood whether the SH mechanism is consistent across various operating conditions, which may lead to inaccurate assessments of MPPFC reliability. This paper explores the effect of the DC voltage ramp rates on the SH performance of MPPFC. A more specific classification of SH processes under a high electrical field: independent SH (ISH) and related SH (RSH, composed of two or more sub-SHs). Additionally, the SH process of MPPFCs can be characterized using multiple Weibull subpopulation distributions for various voltage ramp rates. At slow ramp rates (<500 V/s), both ISH and RSH processes are present in the MPPFC, whereas at rapid ramp rates (≥500 V/s), the SH process is mainly dominated by ISH. Moreover, the cumulative SH energy of the MPPFC at the 30 V/s ramp rate is about 10 times that of the 900 V/s ramp rate. The ISH at the 900 V/s ramp rate causes several point-like damaged regions on the metalized PP film (~0.06% decrease in capacitance). In comparison, the RSH at the 30 V/s ramp rates induces clusters of holes across multiple layers in the MPPFC (~9.85% decrease in capacitance), implying that the MPPFC has overreached its expected lifetime.

A new approach to turbostratic carbon production via thermal salt-assisted treatment of graphite

Here graphite was found to undergo carbon/carbonate gasification at 800 °C, resulting in exfoliation of graphite to form turbostratic carbon. The lattice distance of graphene sheets in graphite are shown to undergo marked changes following treatment with molten ternary eutectic carbonate (Li2CO3: 43.5%, Na2CO3: 31.5%, K2CO3: 25%) during slow temperature ramping rates (5 °C/min) under N2 at temperatures above 750 °C. Initial findings suggest that approximately 50 wt% of graphite experiences interlayer expansion. The conventional d spacing of 0.34 nm is modified to a range of intervals between 0.41 nm and 1.22 nm. As a consequence of high operational temperature (800 °C), cations (Li+, Na+ and K+) as well as potentially the anion (CO32–) intercalate between graphitic layers and overcome Van der Waal force between layers. Employing a pressurized N2 environment of 5 bar and 10 bar successfully controls carbonate vaporization and decomposition, as well as inducing ordered layer manipulation to exfoliate more graphite planes from the edges towards deeper levels of the particles. Exploring parameters of both carbonate loading and treatment time in addition to pressure demonstrate that this work opens up a rich selection of parameters that can be used to produce carbons with tuned properties from graphite.

A new MgB2 bulk ring fabrication technique for use in magnetic shielding or bench-top NMR systems

We report a new methodology in bulk MgB2 ring production for use in small-scale magnetic shielding or bench-top nuclear magnetic resonance systems. This process is a modified field-assisted sintering technique (mFAST) which enables direct formation of the rings without the need for machining or additives into the precursor powder. The shielding and trapped field capabilities of three mFAST MgB2 rings were determined using zero-field- and field-cooled magnetic experiments. Individual bulks trap magnetic fields up to 1.24 T at 20 K comparable to the highest published data for a ring sample. It is anticipated that for many applications, multiple rings will be stacked to form the required experimental structure. We find, for the three ring stack, a trapped field of 2.04 T and a maximum shielded field of 1.74 T at 20 K. The major factor limiting performance at low temperatures are flux jumps which cause rapid loss of the trapped field or shielding capability. Preliminary studies of magnetic field ramp rate dependence on flux jumps were conducted illustrating that even at very slow ramp rates (0.007 T min−1) they remain a significant issue. Despite this concern, we conclude that mFAST represents an exciting new fabrication methodology for bulk MgB2 rings.

Investigation of lyophilized formulation susceptible to the ramp rate of shelf temperature in the primary drying process

In a series of our studies, we revealed that the ramp rate of shelf temperature in the primary drying process affects final product quality in an aggressive cycle (macroscopic collapse occurs at the slow ramp rate whereas acceptable lyophilized cake appearance is observed at the fast ramp rate). However, the studies were performed by disaccharide-based formulations, and whether the other formulations are susceptible to the ramp rate remained unclear. In the present study, the aqueous solutions of a representative bulking agent (mannitol, glycine, dextran, sucrose, trehalose and lactose) and protein model formulation with different levels of bovine serum albumin were lyophilized at different ramp rates. Macroscopic collapse occurred at the slow ramp cycle in a high concentration of disaccharide solutions, which have a low collapse temperature (Tc), and slow ramp-induced collapse was inhibited as the concentration was decreased. Also, drying failure in the slow ramp cycle was not confirmed in mannitol, glycine and dextran formulations. Furthermore, the slow ramp-induced collapse was inhibited as the concentration of the protein was increased. Thus, the amorphous-based formulation with low Tc containing a large amount of bulking agent was considered to be the formulation susceptible to the ramp rate.

Revealing cracking and breakage behaviours of gibbsite particles

Mitigating gibbsite particle cracking and breakage during industrial alumina production can increase the quality of smelter grade alumina product by reducing the ultrafine particle content. Therefore, it is essential to investigate the particle cracking during static calcination and the breakage of calcined gibbsite particles under external force. In this work, we investigated the impact of the calcination ramping rate and the crystallite size on gibbsite particle cracking during static calcination. A slow ramping rate and a large pristine crystallite size tend to increase particle cracking. Apart from the study of particle cracking behaviour, we also investigated the breakage of calcined gibbsite particle under external force. Cracks on the particle surface can initiate breakage within the crystallite and along the grain boundary under external force. The breakage within crystallite occurs as the cleavage of the crystallite, while the breakage along the grain boundary leads to the shedding of a whole crystallite. We further explored the factors influencing the strength of calcined gibbsite particles. With increasing calcination temperature, the strength of particle increases when gibbsite converts to boehmite, and then decreases when boehmite converts into amorphous alumina. Particles containing smaller crystallites and calcined with fast ramping rates exhibit higher resistance to breakage.

Maximum ramp rate estimation for active powers from generation units

Active powers from generation units are required to track changes of automatic generation control (AGC) commands from power grid dispatch centers. Maximum ramp rates are the fastest speeds in making required changes of active powers, and are valuable performance metrics for dispatching AGC commands to quickly suppress frequency fluctuations in power grids. This article proposes a method to estimate maximum ramp rates from historical data samples of active powers. The proposed method is composed by three steps to address some technical challenges. The first step resolves a challenge in separating original data samples of active powers into isolated data segments in piece-wise linear representations, from which amplitude changes and time durations of active powers are obtained. The second step selects pairs of large amplitude changes and short time durations being associated with sufficient local densities; doing so deals with the second challenge to achieve a maximum ramp rate estimate representing a repeatable rapidity, instead of an occasional largest ramp rate. In order to alleviate and quantify the negative noise effects as the third challenge, the last step of the proposed method builds linear regression models on the selected pairs of amplitude changes and time durations, and estimates the maximum ramp rates with their confidence intervals afterwards. Existing methods in the literature do not fully consider the three challenges, so that resulting estimates are either the mixtures of fast and slow ramp rates, or the contaminated ones with large errors. Numerical and industrial examples are provided to illustrate the proposed method and compare with existing ones.

Mechanism of collapse of amorphous-based lyophilized cake induced by slow ramp during the shelf ramp process

We previously found that a slow ramp rate during the shelf ramp process induced product collapse. However, the cause of the collapse could not be explained by the hypothesized mechanism of collapse. To identify the cause, drying parameters such as sublimation rate and dry layer resistance (Rp) were calculated from cycle data by mathematical model. As a result, the behavior of these parameters in the slow ramp cycles showed a different profile from that of the fast ramp cycles. From the cross-sectional appearance of the lyophilized cakes, the point at which the onset of collapse occurred in vial lyophilization during the slowest ramp cycle was estimated, and collapse occurred as expected, at a dry layer thickness (Ldry) = 1.5 mm in the Rp − Ldry profile. The time-point of Ldry = 1.5 mm corresponded to the shelf ramp process; the subliming ice front temperature (Ti) at this point was lower than the collapse temperature (Tc) measured by LT-FDM. Although Ti in the fastest ramp cycle exceeded the above temperature, no macroscopic collapse was observed. Thus, the real Tc during the shelf ramp process in vial lyophilization was decreased by the slow ramp rate, and this was considered the reason for collapse in the slow ramp cycle.

HESS Sizing Methodology for an Existing Thermal Generator for the Promotion of AGC Response Ability

Due to the increasing penetration of renewables, power systems with lower inertia may result in larger frequency excursion. The emergency of new inertia and fast-frequency response characteristics made energy storage systems (ESSs) much more attractive in recent years. ESS can largely improve the frequency regulation capability of a traditional thermal generating unit with relatively slow ramp rate. In this paper, a novel method for sizing a hybrid energy storage system (HESS) to improve automatic generation control (AGC) response of an existing thermal generator is presented, which strikes a right balance between the extra benefit from faster AGC response and the increased HESS cost. First, a novel control scheme for HESS is proposed to improve both the AGC response speed and the precision of a HESS-generator system. And then, based on the benefit analysis of AGC response, a novel cost-benefit-based optimization model is presented for HESS configuration with the aim of maximizing the AGC response benefit of HESS-generator system. Finally, using actual historical data, the simulation is conducted to demonstrate the effectiveness of the presented sizing methodology.

The Respiratory Compensation Point and the Deoxygenation Break Point Are Not Valid Surrogates for Critical Power and Maximum Lactate Steady State.

The Respiratory Compensation Point and the Deoxygenation Break Point Are Not Valid Surrogates for Critical Power and Maximum Lactate Steady State.

Battery Energy Storage Selection Based on a Novel Intermittent Wind Speed Model for Improving Power System Dynamic Reliability

Owing to intermittency of wind power and slow ramp rates of conventional generators, a considerable amount of wind energy cannot be effectively utilized during frequency control processes. This paper proposes a technique for power system planners and operators to select or commit power capacity and energy capacity of battery energy storage system (BESS) for mitigating the effects of intermittent wind speeds on reliability and economics. A novel procedure is proposed to determine intermittent wind speeds based on the chaos theory and intermittency-related parameters. The frequency-related reliability and economic indices of a power system with BESS are formulated based on frequency control processes. The effects of BESS on dynamic reliability and economics of a practical power system are investigated using the proposed techniques and models.

Improved Boiler-Turbine Coordinated Control of CHP Units with Heat Accumulators by Introducing Heat Source Regulation

It is significant for power system stability to improve the operation flexibility of grid-connected units. Such improvement has always been a hot topic, especially for coal-fired units. In recent decades, it has become increasingly urgent and challenging as large-scale fluctuant renewable energy is connected to the power grid. Boiler-turbine coordinated control strategy (CCS), which is employed to perform unit load control according to automatic generation control (AGC), has a slow ramp rate in general on account of large delay and inertia of boiler, so to improve the unit operating flexibility, it is necessary to explore usable heat storage and optimize the control strategy. In combined heat and power (CHP) units with heat accumulators, their heat and power are decoupled. Therefore the extraction steam that goes to the heating station can be regulated flexibly even operating in “heat-led mode”. The change of extraction steam flow has a significant influence on the turbine power output, so we propose to improve the load-following capability of CHP units by regulating the heat source flow. In this paper, the influencing model is set up, and it is about heat source flow variations on the electric power output. The load control strategy is further optimized and designed through combinations of CCS and heat source regulation. Finally simulations and analysis are performed on a 330MW CHP unit, and the results reveal that the power ramp rate with our strategy is two times faster than that with traditional strategy.

Metrological Characterization of Nuclear Magnetic Resonance Markers for Real-Time Field Control of the CERN ELENA Ring Dipoles

Field markers in particle accelerators are used to provide a digital trigger when the magnetic field reaches a pre-set threshold. This paper describes the results of a test campaign performed on the extra low energy antiproton decelerator’s main bending dipoles at the European Organization for Nuclear Research (CERN) investigating the behavior of nuclear magnetic resonance (NMR) markers in ramping fields. Following the conclusions of an off-line study using a spare dipole, a series of tests performed on the reference magnet powered in series with the ring showed an NMR signal with a reproducibility better than $9~\mu \text{T}$ at field levels lower than 47 mT, using slow ramp rates. This is promising for the real-time field control of the decelerator. For a high-field marker using high ramp rates, the reproducibility of the signal was found to be better than $3~\mu \text{T}$ .

Effects of temperature ramp rate during the primary drying process on the properties of amorphous-based lyophilized cake, Part 1: Cake characterization, collapse temperature and drying behavior

In the lyophilization process for injectable pharmaceuticals, the shelf of the lyophilizer is heated to the target temperature at a constant ramp rate during the primary drying process. Although the shelf temperature (Ts) and chamber pressure (Pc) have mainly been investigated to optimize the primary drying process, the impact of the ramp rate on the lyophilized cake properties is poorly understood. We evaluated the relationship between the ramp rate and cake properties using a model formulation containing 10% trehalose as a bulking agent. Elegant lyophilized cakes were obtained when lyophilization was conducted at a fast ramp rate. In contrast, the lyophilized cakes collapsed at slow ramp rate cycles. To identify the cause of collapse, the impact of the ramp rate on the collapse temperature (Tc) was evaluated by light transmission freeze-dry microscopy. The Tc decreased with the decrease in the ramp rate. Lower Tc and higher resistance of the dried matrix in the low sublimation state were hypothesized as the cause of the collapse. Numerous lyophilization runs were executed at different Ts and ramp rates. We confirmed that an increased ramp rate led to successful lyophilization at a higher Ts and that the drying time was significantly reduced.

A new general approach to synthesizing filled and yolk-shell structured metal oxide microspheres by applying a carbonaceous template.

New mechanisms were found for the formation of metal oxide microspheres with yolk-shell and filled structures by applying carbonaceous template microspheres with high porosity. Repeated impregnation first adopted to achieve a high loading rate of metal precursor in the carbonaceous template provided the breakthrough. The carbonaceous template with an appropriate loading rate of the metal precursor produced metal oxide microspheres with filled and yolk-shell structure depending on the ramping rate and oxygen concentration during the post-treatment process. Combustion of the carbonaceous template-which occurs during the moderate post-treatment process in air with a high oxygen concentration-must occur to form yolk-shell structured microspheres. On the other hand, the decomposition of carbon by post-treatment at a slow ramping rate in an atmosphere with a low oxygen concentration without burning produced filled-structured metal oxide microspheres. The carbonaceous template with a high loading rate of the metal precursor produced metal oxide microspheres with filled structures even at a fast ramping rate and high oxygen concentration during the post-treatment process. The new strategy was applied to synthesize various metal oxide microspheres including SnO2, Fe2O3, NiO, and Mn2O3 microspheres.

Effect of a slow ramp rate on exercise testing: a healthy volunteer study

Ramp rates for incremental ramp rate exercise testing are not fully standardised. The ramp rate may influence the values obtained during exercise testing. We compared a slow ramp rate (SR) (3watts/minute) to a fast ramp rate (FR) (20 watts/minute) in 8 fit non elite cyclists using cycle ergometry. We measured peak power ,oxygen consumption (VO2) at anaerobic threshold (AT) and maximumaerobic capacity (VO2 max). A lower mean peak work (369Watts vs 406 Watts, P=0.004), higher mean AT (42.1 ml/min/kg vs 38.6 ml/min/kg, p=0.16) , lower mean VO2 max (51.7 ml/min/kg vs 54 ml/min/kg p=0.25) and higher ratio of AT to VO2 max (0.82 vs 0.71 p = 0.03) were obtained using the SR protocol. These results suggest that ramp protocols need to be considered when interpreting exercise tests clinically. We suggest that further research is required to allow better standardising of ramp test protocols.

Cu-Cu Die to Die Surface Activated Bonding in Atmospheric Environment Using Ar and Ar/N2 Plasma

System performance can be improved by stacking and vertically interconnecting distinct device layers by replacing long 2D interconnects with shorter vertical interconnects. This reduces power loss across interconnects while allowing the design of high bandwidth communication between the two dies which is challenging in a side by side placement. In order to allow communications between stacked dies, metallic connections are required. Cu-Cu solid state direct bonding is ideal to form the required metallic connections if the bonding process is compatible to semiconductor process technologies. Solid state direct bonding allows reduction in pitch size required for the bonding of interconnects from non-solid state bonding methods ( 1). Surface activated bonding (SAB) method is an attractive option for Cu-Cu bonding as the force application duration is considerably short compared to thermocompression while multiple wafers or dies can be processed together in the annealing process at less than 400 °C ( 2). However SAB is difficult for Cu-Cu in atmospheric condition and even more difficult for die to die bonding. Die to die bonding will allow flexibility and optimization in the design of the individual die in the case of heterogeneous integration. In this report, blanket and patterned Cu-Cu die to die SAB have been demonstrated. Two different types of plasma were used for the surface activation of Cu surfaces. Both Ar and Ar / N2plasma activation were performed on the Cu surfaces enabling direct bonding at room temperature, ambient air, and atmospheric pressure without any wet chemical process. Cu-Cu SAB samples with 2mm by 2mm bonding area were prepared for shear strength test. Bonding process was carried out in ambient air, and atmospheric pressure and room temperature with a bonding force of 500N for each sample for 5 minutes. After the bonding process, force was removed and annealing was carried out after multiple purges to form a N2 environment in the chamber. Annealing was carried out at 300 °C for 1 hr with a slow ramp rate. After annealing, the bonded dies were shear strength tested by a shear test machine. The bonded samples are shown in Figure 1. The shear strength results for the SAB with Ar plasma and Ar/N2plasma are shown in Figure 2. Most samples failed at the substrate while some have a mixture of both substrate and interface failure. Patterned dies with cross bridge kelvin resistor (CBKR) structure were also bonded together successfully. Each pair of top and bottom dies was sent for plasma activation together. After the plasma activation, the dies were immediately aligned and bonded together using a Finetech die bonder. The bonding force used in the bonding process was 210N for 4 minutes. After bonding a few set of dies, the samples were transferred into the wafer bonder for the annealing process. Annealing was carried out in N2environment at 300 °C for 1 hour with a slow ramp rate. After annealing, the samples were assessed to be bonded by shaking the dies in a waffle tray. The CBKR structures are shown in Figure 3 and the bonded samples in Figure 4. The dies were then tested electrically to ascertain that all CBKR structures were bonded. Blanket Cu-Cu die to die SAB have been demonstrated with Ar plasma and Ar/N2 plasma. Good shear strength results have been achieved from the bonded samples. CBKR structures patterned dies were also successfully bonded together. This shows that both Ar and Ar/N2plasma activation enables patterned die to die direct bonding at room temperature, ambient air, and atmospheric pressure without any wet chemical process. Works Cited T.Suga. Feasibility of surface activated bonding for ultra-fine pitch interconnection-a new concept of bump-less direct bonding for system level packaging. Electronic Components and Technology Conference, Las Vegas, NV, 2000; pp 702 - 705. T.Suga. Cu-Cu Room Temperature Bonding - Current Status of Surface Activated Bonding(SAB). ECS Transactions 2006, 3 (6), 155-163. Figure 1

Resistive Switching Comparison Between Cu/TaOx/Ru and Cu/TaOx/Pt

Building nonvolatile memory (NVM) directly into a CMOS low-k/Cu interconnect module would reduce latency in connectivity constrained computational devices and reduce chip’s footprint by stacking memory on top of the logic circuits. One strong candidate for NVM is the well-behaved and well-characterized Cu/TaOx/Pt resistive switching device. This device can be operated as a memory cell with copper (Cu) or oxygen vacancy (VO) conductive filaments (CF). Since platinum (Pt) is not an economic choice for industrial production and has been not used in back-end-of-line (BEOL), a BEOL-compatible replacement of Pt is highly desirable. A good candidate for a replacement of Pt is ruthenium (Ru) which has been already deployed in the CMOS BEOL as a possible replacement for Ta/TaN as the liner material. Ru is 45 times less expensive than Pt, and has similar properties as Pt. Pt and Ru are both transition metals with almost identical outer shell structure: Ru has one electron in the 5th orbital and 15 electrons in the 4th orbital, while the larger Pt atom has one electron in the 6th orbital and 17 electrons in the 5th orbital. Cu/TaOx/Pt and Cu/TaOx/Ru devices have been manufactured in the same way. All four layers, Cu, TaOx, Pt, Ru have been deposited by e-beam PVD, with the thicknesses 150 nm, 25 nm, 50 nm, 50 nm, respectively. The only difference in the deposition is the higher melting temperature for Ru of 2250 oC compared with 1768 oC for Pt. The electric characterization of both devices has shown many similarities and some notable differences. The forming and set voltages for Cu filaments in Ru devices are significantly higher (Vform(Ru)-Vform(Pt)»3V) than in Pt devices. This difference cannot be explained solely in terms of work function difference which is Df (Cu-Pt)=1.3eV and Df (Cu-Ru)=0.1eV. In resistive switching devices the resistance of the conductive filament (CF) is a strong function of the imposed compliance current, Icc. We find that the general behavior of Ron for Cu CF is similar for both devices. For Ru device, we find Ron(Icc)=1.75/Icc 1.04 while for Pt device Ron(Icc)=1.28/Icc 1.03. As shown elsewhere, with the exponent of Icc in the denominator being close to 1, the constants 1.75 V and 1.28 V can be interpreted as the lowest possible voltages under which the device can be set. This usually can be reached as a limiting case for very slow voltage ramp rates. The difference in the minimum set voltage extracted from Ron-Icc characteristics confirms that Vset voltages for Ru devices are significantly higher than for Cu devices. We have inquired as to the nature of the Cu filament in both devices by measuring the temperature coefficient of resistance (TCR); we find TCR(Ru-device)=0.00236K-1 and TCR(Pt-device)=0.00235K-1 for similar values of Ron which, within the accuracy of our measurement, means that the values are identical. We conclude that under a positive voltage stress applied to the Cu electrode, very similar Cu CFs are being formed. Moreover, these values are consistent with TCR values of Cu CFs observed in many other devices. We have also observed that for both devices TCR increases with decreasing Ron reaching a value of 0.0035K-1 at Ron=300 W. (For comparison TCR of bulk Cu is 0.0039K-1.) The major drawback of the Ru device is that while Pt devices can be switched repeatedly back and forth, Ru device are becoming not resettable after a few set-reset operations. The failure of the Ru devices after a few switching cycles is related to the high values of form and set voltages. We attribute this behavior to the reduced stopping power of Ru with respect to Cu diffusion compared with the stopping power of Pt. Because of the reduced stopping power in Ru, the Cu ions are not stopped sharply at the interface but migrate into the Ru electrode. The loss of Cu atoms has to be compensated by additional flux of Cu ions at higher voltages. At the same time, the loss of Cu at the base of the Cu filament, leads to a different geometrical shape of the filament. Whereas with a nearly perfect stopping power, the shape of the filament in the Pt device can be assumed to be conical with sharp tip at the Cu electrode, the shape of the Cu filament in the Ru device is more cylinder-like. It is known that filaments with no pronounced constriction are more difficult to rupture, which explains the limited switching cycles of the Ru device. The results are also compared with similar characteristics of Cu/TaOx/Ta devices.