AFM Characterization of Ta-based Diffusion Barriers for Use in Future Semiconductor Metallization

Abstract

In this paper the investigation of r.f.-sputter-deposited Ta, Ta-N and Ta-N-O thin films is presented. Using atomic force microscopy in combination with sheet resistance measurements, Auger electron spectroscopy and x-ray diffraction, the thin film properties and microstructure are examined. Two crystalline modifications of Ta (tetragonal β-Ta and bcc α-Ta) are reported. By incorporation of nitrogen and/or oxygen into the Ta films, nanocrystalline and quasi-amorphous structures can be achieved. Finally, the usefulness of the films as diffusion barriers in Cu-based metallization systems is described.© 1997 John Wiley & Sons, Ltd.