Activation Energy Of Cu Research Articles

In situ scanning electron microscope comparison studies on electromigration of Cu and Cu(Sn) alloys for advanced chip interconnects

A high-resolution in situ SEM (scanning electron microscope) has been configured for real time comparison studies of the electromigration characteristics of Cu and Cu(Sn) alloys. Drift velocity test structures were fabricated and used to simulate the Cu line/W via structure in the multilevel interconnects. Electromigration comparison testings were carried out over a temperature range of 250 to 450 °C and current density of 5×105 to 2.1×106 A/cm2. Under these test conditions, the measured electromigration activation energy for Cu, Cu(0.5 wt %Sn), Cu(1.0 wt % Sn), and Cu(2 wt % Sn) are 0.73, 0.95, 1.25, and 1.14 eV, respectively. The measured critical length for Cu and Cu(Sn) alloys are ≂2.5 μm at a current density of 2.1×106 A/cm2. The observed average drift velocity of Cu mass transport in Cu(Sn) alloys changes with the depletion of Sn atoms which were also found to move in the direction of electron current. Eventually, the Cu mass transport rate reaches a value comparable to that in pure copper test stripes. The measured resistivity values of the Cu(0.5 wt % Sn) and Cu(1 wt % Sn) using Van der Pauw test structures are 2.4 and 2.9 μΩ cm, respectively. In comparison with Cu and Al(Cu) device interconnects, Cu(Sn) alloys exhibits higher electromigration activation energy, good resistance to hillocks and void formation and comparable resistivity. These characteristics clearly indicate the fact that Cu(Sn) alloys are potentially good candidate for advanced device interconnect applications where high-current density and good electromigration resistance are required.

Electromigration-resistant Cu-Pd alloy films

Copper is a prospective material for metal interconnects in microelectronic circuits since it has a high resistance to electromigration damage (EMD) and a low electrical resistivity. In the present work, a still higher resistance to EMD was achieved by alloying Cu with a small amount of Pd. Cu-Pd alloy films consisting of 0.5, 1.0 and 1.6 wt.% Pd were made on oxidized silicon wafers by vacuum evaporation. These films were EMD tested in a high vacuum system by an isothermal resistance change measurement method using a thin film thermistor technique. The activation energies of Cu, Cu-0.5 wt.% Pd, Cu-1.0 wt.% Pd and Cu-1.6 wt.% Pd films were found to be 0.79 eV, 1.01 eV, 1.26 eV and 1.15 eV, respectively. Scanning electron microscopy was used to characterize the Cu and Cu-Pd alloy films after EMD testing. Many of the hillocks that formed had crystalline facets. Film thinning and voiding were also observed, the former being more prominent in the alloy films than in pure Cu. X-ray energy spectroscopy showed that the hillocks on the Cu-Pd alloy films had a measurably lower Pd concentration than the hillock-free areas. Thus Cu appears to diffuse faster than Pd when electromigration takes place. These results show clearly that adding small amounts of Pd to Cu improves the EMD resistance of the stripe.

Redox behaviour of copper(II) tetrathia macrocyclic complexes

Electrochemical redox properties of copper(II) complexes with quadridentate macrocyclic ligands [12]aneS 4, [13]aneS 4 and iso[14]aneS 4 have been investigated. The cyclic voltammetry at a platinum electrode in acetonitrile shows in all cases a quasi- reversible CuL 2+/+ electrode reaction with a half-wave potential of 0.96–1.15 V versus SHE. The reversibility of the redox process was confirmed also coulometrically. The size of the cavity in the 14- membered ring as well as its conformation flexibility permits a tetrahedral environment and leads to the stabilization of the oxidation state of Cu(I) more than in the 12- and 13-membered ring systems. All three copper(II) complexes undergo autoreduction in acetonitrile solution. The reaction is of the first order with respect to the copper complex with the rate constant (1.9–3.2)×10 −5 s −1. Due to the change of the polyhedron structure the activation energy of Cu(iso[14]aneS 4) 2+ autoreduction is higher than that of complexes with smaller rings. The formal potentials as well as the process of autoreduction of copper(II) tetrathia macrocyclic complexes model the reactivity of ‘blue’ copper proteins.

Diffusion of implanted impurities in amorphous Si

The diffusion coefficients of Cu, Ag and Au have been measured in implanted, amorphous Si. The temperature dependences over the range 150–600° C are characterized by Arrhenius relationships with activation energies for Cu, Ag and Au of 1.25, 1.6 and 1.4 eV, respectively. Diffusion is concentration dependent. The diffusion coefficients correlate remarkably well, when extrapolated to high temperatures, with the corresponding slower or “substitutional-like” diffusion coefficients in crystalline Si.

Diffusion, Solubility and Segregation of Implanted Cu, Ag and Au in Amorphous Si

AbstractThe diffusion of Cu, Ag and Au has been measured in implanted, amorphous Si, over the range 150–600° C. The diffusion coefficients are characterized by Arrhenius relationships with activation energies for Cu, Ag and Au of 1.25, 1.6 and 1.4 eV respectively. The solubility of Au in amorphous Si was measured to be 6 orders of magnitude greater than crystalline Si at a temperature of 515°C. The Cu, Ag and Au are segregated ahead of the moving amorphous-crystalline interface. The presence of Au can increase the velocity of the interface.

Kinetics of liquid-solid ion-exchange reactions of transition metal ions in tin(IV) phosphate

A simple approach to liquid-solid ion exchange kinetics of Cu 2+, Zn 2+, Cd 2+, Co 2+ ions in tin(IV) phosphate under different conditions of temperature, exchange ion concentration, and the particle size of the exchanger has been reported. The kinetics were controlled by particle diffusion and the t 1 2 law operated to about 65–75% of exchange. The diffusion coefficients and activation energies were calculated. The activation energies of Cu 2+ and Co 2+ ions were found to be low when compared with Zn 2+ and Cd 2+ ions due to Jahn-Teller distortion.

マンガンノジュールの塩酸浸出反応速度

The leaching rate of a manganese nodule was discussed. The manganese nodule was crushed to 250 mesh under (-61μm) and leached with 1.0 N hydrochloric acid in the temperature range of 30 to 70°C. The results are summarized below.The leaching rate can be represented by the volume reaction model, and the leaching rate of Ni and Cu are the second order with respect to each content remained in the sample. The dissolution of Fe ceases on the way of leaching, and for the soluble portion of Fe the leaching rate of Fe is also the second order. The leaching behavior of Co is analogous to that of Mn, i. e., both of them dissolve only slightly at lower temperature, but highly at 70°C. The leaching rates of Co and Mn at 70°C are also the second order.The apparent activation energies for Cu, Ni and Fe leaching are 41.2, 81.1 and 43.3 kJ/mol, respectively, and the overall reaching rates appear to be controlled by the heterogeneous reaction.