Electromigration temperature effects

Electrical Properties. Generally, deposited thin films have an electrical resistivity that is higher than that of the bulk material. This is often the result of the lower density and high surface-to-volume ratio in the film. In semiconductor films, the electron mobiHty and lifetime can be affected by the point defect concentration, which also affects electromigration. These effects are eliminated by depositing the film at low rates, high temperatures, and under very controUed conditions, such as are found in molecular beam epitaxy and vapor-phase epitaxy. 

Electromigration of the fast diffusers exhibit interesting and varied effects. The measured Z of the impurities is often found to be strongly dependent, not only on temperature but on composition, varying with increased solute content or the presence of a second component (such as Sn in Pb-Sn alloys). In some cases, neither temperature nor composition was found to ha ve an effect on electromigration behavior, while in others the temperature effect is sufficient to reverse the sign of Z changing the direction of atomic flow of the solute from the anode to the cathode. 

Cgo single molecules between electrodes fabricated by electromigration [103] to create single Cgo molecule transistors were measured at a temperature of 40 mK. The results showed the coexistence and competition of the effects of Coulomb repulsion, Kondo correlations and superconductivity [104]. The Kondo effect had been previously observed in similar devices [105]. Recently a SAM of a tricarboxylic acid fullerene derivative was used to fabricate a transistor. The SAM was created by allowing the fullerene compound to self assemble on top of an AI2O3 layer just above the aluminum drain electrode the source lead was created by... 

An applied electrical potential gradient can induce diffusion (electromigration) in metals due to a cross effect between the diffusing species and the flux of conduction electrons that will be present. When an electric field is applied to a dilute solution of interstitial atoms in a metal, there are two fluxes in the system a flux of conduction electrons, Jq, and a flux of the interstitials, J. For a system maintained at constant temperature with Fq = -V = E, Eq. 2.21 gives... 

Figure 8 Effect of solute concentration on electromigration dispersion. Conditions capillary, 38 cm to detector x 50 p.m buffer, 20 mM borate, pH 9.2 voltage, 25 kV temperature, 50°C injection, 1 s at 0.5 psi vacuum detection, UV, 230 nm solute naproxen. (Reprinted with permission from Ref. 52, copyright Marcel Dekker, Inc.)...

The progress achieved in the field of isotope electromigration in metals, salts, and aqueous solutions since the meeting on isotope separation in Paris in 1963 is reported. It is shown that the temperature dependence of the isotope effect in liquid metals leads to the conclusion that it is a result of classical atom—atom interactions. Isotope effects in molten salts are smaller than in classical ionic gases. A three stage model is proposed for an explanation of the temperature dependences of the isotope effects in molten salts. The available data of the relative difference in mobilities of isotopes in aqueous solutions are summarized. 

Fig. 3 Separation of barbital by the use of a capillary coated with (a and c) 10% T PAA and (b and d) 10% T poly(AA-co-IPAAM) containing 85% IPAAM. Experiments were carried out at (a and b) ambient temperature or (c and d) elevated temperature. Conditions capillary column, 50 cm x 0.075mm ID (25cm effective length) buffer, 100 mM Tris-150 mM boric acid (pH 8.3) field strength, 300 V/cm injection, electromigration for 5 sec at the side of cathode. Peak identification (1) phenobarbital (2) barbital (3) mephobarbital (4) amobarbital (5) secobarbital (6) pentobarbital (7) metharbital.

In the sputter deposition of aluminum conductor materials for semiconductor devices, it has been shown that a small partial pressure of nitrogen during sputter deposition can have an effect on the electromigration properties of the deposited aluminum film. In the case of reactive deposition, the residual gas partial pressure is high and has a major effect on the surface mobility and the development of columnar morphologies, even at high deposition temperatures. 

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