Interdiffusion in copperndash;aluminum thin film bilayers. I. Structure and kinetics of sequential compound formation

摘要

Interdiffusion in Cundash;Al thin film bilayers at temperatures between 160 and 300thinsp;deg;C has been studied by a combination of glancinghyphen;incidence xhyphen;ray diffraction, Rutherford backscattering spectroscopy, and transmission electron diffraction and microscopy. A sequential intermetallic compound formation was observed in samples with an excess amount of Cu with thgr;hyphen;CuAl2forming first, followed by eegr;2hyphen;CuAl, and ggr;2hyphen;Cu9Al4. In samples with excess Al, the thgr;hyphen;CuAl2is the first and the last phase formed. The thickening of these compounds was found to obey a parabolic relationship with time, and especially the thickening of thgr;hyphen;CuAl2can be described by a prefactor of 7.4 cm2/s and an activation energy of 1.31 eV.