A Surface Characterization and Depth Profiling Study of Conventional Electrodeposited Chromium Films. 3

In this study the composition and chemical interactions of chromium layers produced in a conventional Sargent bath have been examined using Auger electron spectroscopy (AES), electron spectroscopy for chemical analysis (ESCA), ion scattering spectroscopy (ISS), and depth profiling before and after annealing the sample in air or vacuum. Future comparisons between these results and similar results obtained from chromium layers prepared by the amorphous bright chromium deposition (ABCD) method (Hoshino, S.; Laitinen, H. A.; Hoflund, G. B. J. Electrochem. Soc. 1986,133, 681) should be useful in understanding why the ABCD films behave differently than conventional Cr films. ABCD films have many desirable properties compared to deposits produced by conventional methods. Most importantly, the hardness of ABCD films increases with annealing temperature up to 700 degrees C, whereas the hardness of conventional chromium films decreases. The results of this study indicate that S, C, Cl, O, Ca, K, and Na are incorporated into the conventional chromium films from the electrolytic bath. Cr is present as a sulfide, metal, and oxides. Annealing the sample in air or vacuum (10(-4) Torr) causes sulfur to desorb from the surface probably as SO2. Annealing the sample in high vacuum (5 x 10(-9) Torr) causes sulfur to segregate to the surface and remain there while oxygen migrates to the surface and desorbs. This results in conversion of the surface chromium oxides into Cr2S3 and metallic Cr. Carbon present in the background gas during annealing is adsorbed and incorporated into the bulk of the film.