Thickness measurement of thin-metal films by optical metrology

Abstract

Spectroscopic ellipsometry (SE) and resistivity measurements were used to characterize Nickel-metal films used for self-aligned silicidation process. Variable angle spectroscopic ellipsometer (VASE) in the VUV range of wavelengths was used to measure the thickness and optical properties of Nickel films. The thickness-dependent optical properties of thin-metal films are shown to be correlated to the change in electron relaxation time and resistivity. The change in electron relaxation time and resistivity can be traced to the change in grain boundary reflection coefficient and grain size. X-ray photoelectron spectroscopy (XPS) data aided with sputtering is used to show the evidence of the various stack layers that would be used in the VASE modeling. X-ray reflectivity (XRR) and Rutherford backscattered spectroscopy (RBS) measurements on thin-metal films were performed to complement the thickness measurements made with SE. © 2009 American Institute of Physics.