In situ study of dislocation behavior in columnar Al thin film on Si substrate during thermal cycling

In situ transmission electron microscopy (150 kV) has been employed to study the evolution of dislocation microstructures during relatively rapid thermal cycling of a 200 nm Al thin film on Si substrate. After a few thermal cycles between 150 and 500 °C, nearly stable Al columnar grain structure is established with average grain less than a μm. On rapid cooling (3-30+ °C/s) from 500 °C, dislocations first appear at a nominal temperature of 360-380 °C, quickly multiplying and forming planar glide plane arrays on further cooling. From a large number of such experiments we have attempted to deduce the dislocation evolution during thermal cycling in these polycrystalline Al films and to account qualitatively for the results on a simple dislocation model.