Structural Characterization of Cobalt Thin Films Grown by Metal-Organic CVD

Authors


  • The authors thanks go to Dr. C.C. Tang at the Daresbury SRS for his help with X-ray experiments, Dr. M. Rotov (Keele) for help provided with the AFM study and Dr. G.W. Critchlow of the Institute for Surface Science and Technology at Loughborough University for Auger measurements. Dr. Chioncel thanks the UK Committee of Vice Chancellors and Principals for the award of an Overseas Research Scholarship.

Abstract

Cobalt thin films were produced by metal-organic CVD from C5H5Co(CO)2, at various temperatures and for various deposition times. The films have been grown onto glass substrates with no buffer. The crystalline structure, morphology, and composition of the films were analyzed by X-ray diffractometry (XRD), field-emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), and Auger electron spectroscopy (AES). Routine XRD patterns were collected in symmetric geometry for phase identification and the sin2ψ diffraction technique was employed to calculate the average in-plane stress. Structural studies indicate that the films tend to grow in island mode, as predicted by theory, and have a structure between that of face-centered cubic (fcc) and hexagonal close-packed (hcp) cobalt. There is significant in-plane tensile stress at the interface with the substrate, which relaxes to a compressive stress an order of magnitude lower at the surface. The films have a relatively low impurity content, as determined by AES, except near the surface.

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