Electrical Resistivity Of Copper Research Articles

The twin formation under electric current stressing and its effect on the properties of copper

Copper as one of the major electronic metals will experience electric current stressing during electronics application. The study comprehensively investigated microhardness and electrical resistivity variations of copper under current stressing at current densities 1.4 x 104 and 1.7 × 104 A/cm2 for up to 8 h. The variations in these properties were correlated with dislocation density and twin fraction. The dislocation density and twin fraction were estimated, respectively, with high resolution transmission electron microscope and Electron Backscatter Diffraction. The twin boundary acts as obstacle to dislocation movement as revealed by high resolution transmission electron microscopy. The twin boundary predominates over dislocation in governing the microhardness and electrical resistivity of copper under current stressing.

Comparison of CoW/SiO2 and CoB/SiO2 Interconnects from the Perspective of Electrical and Reliability Characteristics

As the feature size of integrated circuits has been scaled down to 10 nm, the rapid increase in the electrical resistance of copper (Cu) metallization has become a critical issue. To alleviate the resistance increases of Cu lines, co-sputtered CoW and CoB alloying metals were investigated as conductors and barriers in this study. Annealing CoM (M = W or B)/SiO2/p-Si structures reduced the resistivity of CoM alloys, removed sputtering-deposition-induced damage, and promoted adhesion. Additionally, both annealed CoW/SiO2 or CoB/SiO2 structures displayed a negligible Vfb shift from capacitance-voltage measurements under electrical stress, revealing an effective barrier capacity, which is attributed to the formation of MOx layers at the CoM/SiO2 interface. Based on the thermodynamics, the B2O3 layer tends to form more easily than the WOx layer. Hence, the annealed CoB/SiO2/p-Si MIS capacitor had a higher capacitance and a larger breakdown strength did than the annealed CoW/SiO2/p-Si MIS capacitor.

Copper–Carbon Nanotube Composites Enabled by Electrospinning for Advanced Conductors

The power losses associated with the electrical resistance of copper (Cu) have generated considerable interest in the development of advanced conductors that incorporate carbon nanotubes (CNTs) int...

Fabrication and characterization of electrically conductive copper coated poly(p-phenylene-2,6-benzobisoxazole) yarn

ABSTRACT In order to develop conductive materials with high tensile strength and high Young’s modulus, copper was deposited on the surface of Poly(p-phenylene- 2,6-benzobisoxazole) (PBO) yarn by electroless plating. Copper coated PBO yarns were characterized by SEM, XRD and XPS. Weight gain rate and electrical resistivity of copper coated PBO yarns were measured. The result shows that the copper layer is deposited uniformly and densely with high purity. The copper coated PBO yarn not only possesses excellent mechanical strength with a tenacity of 121.27 cN/tex but also exhibits excellent electrical conductivity with the resistivity of 4.20 × 10−7Ω·m under 3200cN tension force. In addition, the copper coated yarns can generate heat and the temperature of copper coated yarn maintains at 60°C with only 1.8 V. The result indicates that copper coated PBO yarn is promising conductive material. Therefore, copper coated PBO yarn can be applied in fields such as flexible sensor, e-textile and flexible heating pads.

Electrical Resistance of Copper at High Pressures and Temperatures: Equilibrium Model and Generation of Defects of the Crystal Structure under Shock Compression

Electrical Resistance of Copper at High Pressures and Temperatures: Equilibrium Model and Generation of Defects of the Crystal Structure under Shock Compression

Energy Efficient Strategies for Processing Rare Earth Permanent Magnets

Due to high magnetic fields causing strong interactions between permanent magnets and other ferromagnetic material, transport and handling of magnetized magnet bodies is challenging. To avoid undesired effects, such as influences on sensitive devices or difficult separation of the single magnets from stack, spacing and shielding of the magnet bodies is required leading to larger package sizes and thus in some cases higher energy demand during transport referred to the transported magnet mass. An optimization of the transport chain can be reached using the software tool presented in this paper. Further magnetizing high coercive rare earth magnets needs strong magnetic fields. To create the necessary field strength, copper coils are used requiring current strengths of several kA. Since the electrical resistance of copper differs from zero, this also means enormous thermal losses. Hence to reduce the losses and to avoid thermal damage of the coil, only short current pulses are applied generated by a pulse magnetizer. However, the efficiency of the process is very poor and lies in the lower per mil range. The presented paper explains the magnetization process in detail with focus on the losses within the magnetization device. Further different material parameters influencing the saturation field strength, such as conductivity, size and diameter to length ratio are presented and possibilities to improve the energy efficiency are shown.

ЭЛЕКТРОСОПРОТИВЛЕНИЕ МЕДИ ПРИ УДАРНОМ СЖАТИИ: ЭКСПЕРИМЕНТАЛЬНЫЕ ДАННЫЕ

ЭЛЕКТРОСОПРОТИВЛЕНИЕ МЕДИ ПРИ УДАРНОМ СЖАТИИ: ЭКСПЕРИМЕНТАЛЬНЫЕ ДАННЫЕ

탄소섬유를 이용한 Polyethylene배관의 전기융착 기술

Fuel gas is an important energy source that is being increasingly used because of the convenience and clean energy provided. Natural gas is supplied to consumers safely through an underground gas-pipe network made of a polyethylene material. In electrofusion, which is one of the joining methods used, copper wire is used as the heating wire. However, it takes a long time for fusion to occur because the electrical resistance of copper is low. In this study, therefore, electrofusion was conducted by replacing the copper heating wire with carbon fiber to reduce the fusion time and improve the production when joining large pipes. Fusion and tensile tests were performed after the electrofusion joint was made in the polyethylene pipe using carbon fiber. The results showed that the fusion time was shorter and the temperature inside the pipe was higher with an increase in the current value. The ultimate tensile strength of specimens was higher than that of virgin polyethylene pipe, except for polyethylene pipes joined using a current of 0.8 A. The best fusion current value was 0.9 or 1.0 A because of the short fusion time and lack of transformation inside the pipe. Thus, it was shown that carbon fiber can be used to replace the copper heating wire.

Preparation by tape casting and hot pressing of copper carbon composites films

During this last decade, the use of metal matrix composites (MMCs) such as AlSiC or CuW for heat dissipation in microelectronic devices has been leading to the improvement of the reliability of electronic power modules. Today, the continuous increasing complexity, miniaturization and density of components in modern devices requires new heat dissipating films with high thermal conductivity, low coefficient of thermal expansion (CTE), and good machinability. This article presents the original use of copper carbon composites, made by tape casting and hot pressing, as heat dissipation materials. The tape casting process and the sintering have been adapted and optimised to obtain near fully dense, flat and homogeneous Cu/C composites. A good electrical contact between carbon fibres and copper matrix and a low porosity at matrix/copper interfaces allow obtaining a low electrical resistivity of 3.8 μΩ cm −1 for 35 vol.% carbon fibre (electrical resistivity of copper = 1.7 μΩ cm −1). The CTE and the thermal conductivity are strongly anisotropic due to the preferential orientation of carbon fibres in the plan of laminated sheets. Values in the parallel plan are, respectively, 9 × 10 −6 °C −1 and 160–210 W m −1 K −1 for 40 vol.% fibres. These CTE and thermal conductivity values are in agreement with the thermo-elastic Kerner's model and with the Hashin and Shtrikman model, respectively.

Electrical Behavior of Nano-Scaled Interconnects

AbstractSub-lithographic copper damascene lines were fabricated to investigate already today the physical phenomena and scaling limits of metallic conductors in the metallization systems of chip generations which are believed to be in production 10 years from now and later. Using standard manufacturing processes and state-of-the-art process tools, including standard lithography tools, narrow copper lines were fabricated at the expense of a relaxed pitch by use of a removable spacer technique. These copper nano interconnects were passivated and subjected to electrical measurements. Our results show that continuous down scaling to increase device performance will result in an unfavorable increase of the electrical resistivity of copper in stateof-the-art metallization schemes. Electrical measurements over a wide range of temperatures down to cryogenic temperatures reveal the limited potential of cooling to reduce resistivity of conductors as lateral dimensions will be shrinked down to the sub-100nm regime. By down scaling of copper diffusion barriers in damascene trenches, barrier functionality was demonstrated after high temperature anneals and excessive bias-temperature stress tests for films meeting or even exceeding end-of-roadmap thickness requirements. An analysis of the temperature dependence of the leakage current measured at very high electric fields applied between neighboring damascene lines suggests the conduction mechanism in the SiO2 used as intermetal dielectric to be Frenkel-Poole type rather than Schottky emission. Electromigration life times of sub-100nm copper lines embedded in oxide were found to be comparable with those obtained for similar structures fabricated with today's feature sizes.

Electrical resistivity of copper containing solid krypton precipitates

The resistivity of bulk Cu containing 3 atomic % Kr, in the form of nanoscale bubbles, has been measured over the temperature range 100-200K. Both the temperature dependence of the resistivity and the residual resistivity are compared with OFHC copper (0.9995 purity) and a 1.8% beryllium bronze, in half-hard and precipitation hardened condition. We find the temperature derivative of the resistivity to be 0.0101 ± 0.0003 μΩ cm K -1 , which is significantly higher than the value of 0.0068 ± 0.0004 μΩ cm K -1 for OFHC Cu determined in the same system. The extrapolated residual resistivity is 3.24 ± 0.14 μΩ cm compared to 7.23 ± 0.29 μΩ cm for Cu-Be.

Increase in Electrical Resistivity of Copper and Aluminum Fine Lines

The resistivities of thin films and fine lines of copper (Cu) and aluminum (Al) were measured by a resistance ratio method (referred to as “RR method” hereafter), which measures the ratio of room-temperature resistance to liquid-nitrogen-temperature resistance. This method can predict resistivity exactly without the need for precise and detailed line or film dimension measurements. Thinner films and finer lines have higher resistivities in the case of both Cu and Al, with Cu showing larger resistivity increases (films and lines) than Al . From the present data, we estimated the electron mean free path of Cu to be 55 nm, which is close to most of the previously reported values, and that of Al to be 22 nm. Line resistivities depend not only on the line width but also on line thickness. We propose a simple equation for expressing line resistivity in terms of line thickness and width.

Effect of Ti additions on the electrical resistivity of copper

Electrical resistivity of Cu Ti alloys containing 1.5, 2.7, 4.5 and 5.4 wt.% Ti, has been determined from the resistance values measured using Kelvins Bridge apparatus at room temperature. The resistivity in solution-treated alloys increases with Ti content linearly up to about 4.0 wt.% Ti, beyond which it decreases with further additions of Ti. However, in peak-aged condition, the resistivity continues to increase linearly up to 5.4 wt.% Ti without showing any decrease. Nordheim's rule of resistivity is followed up to approximately 4.0 wt.% Ti in the solution-treated alloys. Further, Nordheim's rule modified with the incorporation of the law of mixtures for two-phase systems ( ρ t = ρ m ν fm + ρ p ν fp) is obeyed right up to 5.4 wt.% Ti in the peak-aged alloys. The difference in behaviour is attributed to the fine scale precipitation formed during quenching in solution-treated Cu—4.5Ti and Cu—5.4Ti alloys, as revealed by transmission electron microscopy (TEM). The contribution to the total resistivity by β′-Cu 4Ti precipitate and prior cold deformation is considerable in deformed and peak-aged Cu Ti alloys.

Effect of Direct Current Pulse Discharge on Electrical Resistivity of Copper and Iron Powder Compacts

The relationship between the number of pulses and the specific resistivity for the copper and iron powder compacts has been investigated to reveal the phenomena which are caused between powder particles in the early stage in the spark sintering process. The values of specific resistivity of the both powder compacts decrease with increasing the number of pulses, and the rates of decrease of specific resistivity increase with decreasing applied punch pressures. The limited variations of the relative densities of compacts are observed in the continuously pulse discharge process. Therefore, it is considered that the specific resistivity of compacts are decreased, not because their relative densities are changed but because the properties of the contact area between powder particles are changed by the pulse discharge. Where, this change of the properties is caused by the dielectric breakdown of the oxide film between the powder particle surfaces in the pulse discharge process. The metallic contact parts are created between the powder particles after this dielectric breakdown. It is suggested on the basis of the simple model of electric resistance of a compact that the fraction of the metallic contact area created by the dielectric breakdown of the oxide film is extremely small. Furthermore, it is assumed on the basis of the first order equation of the chemical reaction that the rate of the creation of the metallic contact area between powder particles per pulse discharge is proportional to the fraction of the contact area consisting of an oxide film between particles. The relationship between the number of pulses and the specific resistivity of compacts can be explained quantitatively by this assumption.

Effect of plastic deformation on the electrical resistivity of metals

Results from measurements of the electrical resistivity of copper and aluminum conductors under the action of a plane shock wave, and also analysis of the relationship between the electrical resistivity and the hydrostatic pressure and of the theoretical temperature dependence of the electrical resistivity, has made it possible to elucidate the role of defect formation due to the plastic deformation of the metal and to determine its contribution to the increase in electrical resisitivity of the metal. It has been established that the concentration of defects depends on the pressure gradient in a plane shock wave.

Electrical resistivity of copper reinforced with short carbon fibres

The electrical resistivity of copper reinforced with short aligned carbon fibres has been measured in axial and transverse directions as a function of fibre content. The results have been considered in the light of predictions from the Eshelby equivalent homogeneous inclusion method for modelling of conduction. Higher resistivities, particularly for transverse current flow, were observed than is predicted on the basis of an isotropic matrix resistivity equal to that of unreinforced copper. This is thought to be explicable in terms of the effect of relatively high levels of elongated porosity present in the specimens examined.

Electrical resistivity of copper and nickel thin-film interconnections

The resistivity and temperature coefficient of resistivity of copper and nickel thin films used as high-density interconnections in hybrid packages have been measured in the temperature interval 298–723 K. The effects of film thickness, deposition conditions, and postdeposition anneal were analyzed in detail. Minimum as-deposited resistivities approximately 18% and 80% above bulk values could be achieved under optimized deposition conditions for 1-μm-thick copper and nickel films, respectively. Contributions to the resistivity values attributable to electron scattering at phonons, surfaces, impurities, grain boundaries, and intragranular defects were also established. Although subsequent annealing had little impact on the resistivity of copper, a significant reduction in the resistivity of nickel was observed, due primarily to dislocation sinking. Lastly, the relationship of resistivity to the temperature coefficient of resistivity for both metal films was found to be in agreement with Matthiessen’s rule.

Thermal conductivity and electrical resistivity of copper in intense magnetic fields at low temperatures

Thermal conductivity and electrical resistivity of copper in intense magnetic fields at low temperatures

On the low-temperature electrical resistivity of copper and gold

The electron-phonon contribution to the low-temperature electrical resistivity of copper and gold is calculated using two plane-wave states for the electrons and the eight-cone model for describing the Fermi surface. The approximate T4 behaviour which has been observed recently for copper and gold is examined in terms of the calculated electron-phonon contribution plus a suitable electron-electron term. The results of the calculations are presented and discussed.

Electrical resistivity of copper, gold, palladium, and silver

In this work, recommended values for the electrical resistivity as a function of temperature from the cryogenic region to well beyond the melting point are given for bulk pure copper, gold, palladium, and silver. In addition to the total electrical resistivity values for the solid state, intrinsic electrical resistivity values are presented from cryogenic temperatures to the melting point. The values are corrected for the change in geometry due to thermal expansion. The recommendations are based on theoretical considerations and on the experimental data found in the open literature. That available experimental data together with information pertaining to the specimen characterization and measurement conditions are included in this work. The methods of data evaluation and other considerations used in arriving at the recommendations are described. For the solid state, an interpolation scheme is given to aid in the determination of values between those supplied in the tables; for the liquid state, equations are given.