The Influence of Stress on TiSi_2 Phase Formation

摘要

Thermal stress can be engineered in a thin film system by depositing a film with a different thermal expansion to that of the substrate on the back of the substrate. In this work the effect of stress on TiSi_2 formation was studied by depositing Si_3N_4 or SiO_2 layers of different thickness on the backside of Si(100) wafers. One set of samples had 400 nm SiO_2 on the back of the wafer and the other sets had 200 nm and 400 nm Si_3N_4 respectively. Rutherford Backscattering Spectrometry (RBS) and X-ray diffraction (XRD) measurements showed that the reaction was faster in samples with Si_3N_4 on the back of the wafer. The TiSi_2 formation kinetics was found to be linear with the cube root of the annealing time. The formation kinetics had an Arrhenius dependence on temperature. The apparent activation energy for all three types of samples was the same within experimental error. The growth rate of TiSi_2 on wafers with Si_3N_4 layers on the back was between 3 (600℃) and 5 times (490℃) faster than that on wafers with SiO_2 deposited on the backside.