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

Abstract

Cobalt thin films were produced by metal-organic CVD from C 5 H 5 Co(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 sin 2 ψ 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 (hep) 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.