Chromium thin film as a barrier to the interaction of Pd2Si with Al

Backscattering spectrometry with 2.3 and 2.0 MeV ⁴He⁺ have been used to study the role of Cr as a barrier in the interaction of Pd₂Si with Al. Samples of palladium silicide (Pd₂Si) grown on Si 〈100〉 single crystal and Al evaporated on top, in that order, showed a substantial intermixture of Pd₂Si and Al, and a non-uniform erosion of the Pd₂SiSi interface when heated between 300 and 450°C. With a thin layer of Cr(300–1500 Å) interposed between Pd and Al intermixing of Pd₂Si and Al was suppressed for temperatures up to 500°C and times up to 2 hr. In these samples distinct sublayers of Pd₂Si, CrSi₂ and CrAl_x (where the values of x depends on the relative thicknesses of Al and Cr) are formed. We have noted that whenever there is a thin unreached Cr layer the spectra of the distinct sublayers show sharp boundaries.