Tungsten-titanium diffusion barriers for silver metallization

Diffusion barrier properties and thermal stability of reactive sputtered W-Ti films between Ag and Si were studied using X-ray diffractometry, X-ray fluorescence spectrometry, Rutherford backscattering spectrometry, four point probe analysis, and field emission scanning electron microscopy. These films were annealed in vacuum at different temperatures for 1 h. Silver layers were found to be stable up to 600 degrees C after which, Ag agglomerated at 700 degrees C. Rutherford backscattering analysis showed that interfacial reactions took place at temperatures higher than 400 degrees C. Four point probe resistivity measurements showed that the films were stable up to 600 degrees C. At 700 degrees C the resistivity increased abnormally. These results support further investigation of W-Ti films as a potential barrier layer for Ag metallization in the high temperature electronics. (c) 2006 Elsevier B.V. All rights reserved.