Activation energy for Ostwald ripening of Al2Cu in Al(4 wt. % Cu) thin films using a lateral diffusion couple

Abstract

The activation energy Ea for Ostwald ripening (coarsening) of Al2Cu(Θ phase) precipitates in Al(4 wt. % Cu) thin films was determined using a lateral diffusion couple. A 1 μm thick Al(4 wt. % Cu) blanket film was deposited on lines of Al2Cu embedded in SiO2. With annealing at temperatures between 400 and 450 °C (1.4–2.5 wt. % Cu in solution) for 1 to 80 h, Θ precipitates were dissolved in regions between 10 and 110 μm wide parallel to the Al2Cu lines. The width of this region increased as the square root of the annealing time. The Ea was determined to be 2.5±0.5 eV from an Arrhenius plot. This value is much larger than both the activation energies for Cu lattice and grain-boundary diffusion in Al. Understanding the coarsening kinetics of Al2Cu is important since the reliability of Al(Cu) metallizations is strongly dependent on the microstructure.

Selective epitaxial growth of dot structures on patterned Si substrates by gas source molecular beam epitaxy

“…The morphology of the samples was compared with that of the sample without any GI. Although the size of dots increased, the number of dots decreased as the GI increases, indicating that the dots under the equilibrium condition are coalesced [16], known as Ostwald ripening [19]. The migration length can be estimated as the average distance between dots as a function of GI.…”