NONDESTRUCTIVE CHARACTERIZATION OF THE UNIFORMITY OF THIN COBALT DISILICIDE FILMS BY RAMAN MICROPROBE MEASUREMENTS

The ability of microRaman spectroscopy for the non-destructive characterization of the uniformity of thin silicide films on Si is analyzed. The technique is applied to characterize thin polycrystalline and epitaxial CoSi2 films. The absorption coefficient of these films, alpha, at the excitation wavelength of 514.5 nm is determined from Raman scattering measurements in combination with Rutherford backscattering spectrometry. Using this value, the thickness uniformity of the layers can be investigated by microRaman spectroscopy with a lateral resolution below the size of the devices to be defined on the structures. Moreover, even if alpha is not known, the product ad can be calculated in a straightforward way from Raman measurements, where d is the film thickness. By monitoring this product, the homogeneity of the layers can be analyzed. The results obtained are discussed in terms of the different processing of the layers. Finally, the ability of the technique for the characterization of the films is studied as a function of their thickness.