Structural investigation of Cr(Al)N/SiOx films prepared on Si substrates by differential pumping cosputtering.

Analytical electron microscopy revealed the structure and growth of hard coating Cr(Al)N/SiOx nanocomposite films prepared in a differential pumping cosputtering (DPCS) system, which has two chambers to sputter different materials and a rotating substrate holder. The substrate holder was heated at 250 °C and rotated at a speed as low as 1 rpm. In order to promote the adhesion between the substrate and composite film, transition layers were deposited on a (001) Si substrate by sputtering from the CrAl target with an Ar flow and a mixture flow of Ar and N2 (Ar/N2) gases, subsequently, prior to the composite film deposition. Then, the Cr(Al)N/SiOx nanocomposite film was fabricated on the transition layers by cosputtering from the CrAl target with the Ar/N2 gas flow and from the SiO2 target with the Ar gas flow. The film had a multilayer structure of ∼1.6 nm thick crystallite layers of Cr(Al)N similar to NaCl-type CrN and ∼1 nm thick amorphous silicon oxide layers. The structure of the transition layers was also elucidated. These results can help with the fabrication of new hard nanocomposite films by DPCS.