Initial reactions in Ti–Si bilayers: New indications from in situ measurements

The interactions occurring in a Ti–Si bilayer have been investigated by in situ resistance measurements and the reaction products have been analyzed by complementary techniques, such as x-ray diffraction, Auger electron spectroscopy, and MeV 4He+ Rutherford backscattering. The measurements were performed by heating the samples at a constant rate in the 5–425 °C/min range. The samples are 60 nm of titanium sputter deposited on 250 nm of a silicon film deposited by chemical vapor technique; the bilayers were placed on 650 nm of SiO2, thermally grown on p-type 〈100〉 silicon wafers. Samples were also prepared by reactively depositing 25 nm of TiN on the Ti film. The TiN cap, deposited without breaking the vacuum, protects the metal films from contaminants, namely oxygen, during handling and heat treatments. It has been shown that, at temperatures around 400 °C and before any massive Ti–Si interaction, the resistance increases. This effect, attributed in the literature to the silicon diffusion in the metal fil...