A nondestructive, noncontact, optical method was successfully developed to measure thicknesses of titanium and titanium silicide thin films by observing infrared transmissions. These transmissions can be substantial for film thicknesses of up to 850 Å in titanium and 1000 Å in titanium silicide. The technique provides a convenient and reliable means for in‐line process monitoring of a Ti‐salicide (titanium self‐aligned silicide) process module for gate, source, and drain formation in integrated circuits. A linear relationship between absorbance and film thickness was obtained for titanium and titanium silicide films. This behavior can be explained very well by the classical wave propagation theory of metallic films.