ELLIPSOMETRY AND TRANSPORT STUDIES OF THIN-FILM METAL NITRIDES

The results of a systematic spectroellipsometric and conductivity stud y of metallic titanium nitride thin films grown on silicon by the ion- beam-assisted deposition technique are presented. The directly measure d electrical resistivity is correlated with the contactless, non-invas ive ellipsometric method of extractings the free- and bound-carrier re sponse in the infrared, visible, and ultraviolet spectral ranges. The d.c. resistivity of TiN films ranges from similar to 100 to similar to 500 mu Omega cm. The high polarizibility of free carriers at optical frequencies presents non-trivial problems of the measurement optimizat ion. The merit of the ellipsometric data taken at proper angles of inc idence in different spectral ranges is discussed for homogeneous and g raded layers. For TiN films of a good structural quality, the extrapol ation of ellipsometric results is found to be in a fair agreement with d.c. data, providing an optical, contactless way of measuring the ele ctrical conductivity. This can be achieved even with a very simple nea r-infrared ellipsometer. (C) 1998 Elsevier Science S.A. All rights res erved.