Characteristics and Thermal Behavior of Sputtered Titanium Thin Films on Various Substrates

Titanium films are growing in popularity and are soon expected to replace copper for metallization purposes. However the thermal stress behavior of titanium films had not been extensively studied and therefore not clearly understood. Thus the main goal of this work was to develop a systematic process to analyze and model the dσ/dT evolution between 20ºC and 300ºC in sputtered titanium thin films. A biaxial stress state has been legitimately assumed. In the laboratory titanium films with a nominal thickness of 200 nm were deposited on five different kinds of unheated substrates by RF magnetron sputtering. These substrates included titanium plate soda-lime glass and three kinds of p-type silicon wafers having crystallographic orientations of (100) (110) and (111). X-ray diffraction was used to characterize the crystallographic evolution with respect to temperature. By utilizing a heating chamber and special tooling the lattice spacings were measured in-situ and the thermal stress behaviors were estimated with either the sin2ψ method or the d-spacing method.