Tungsten–titanium diffusion barriers for silver metallization

Abstract 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 °C; after which, Ag agglomerated at 700 °C. Rutherford backscattering analysis showed that interfacial reactions took place at temperatures higher than 400 °C. Four point probe resistivity measurements showed that the films were stable up to 600 °C. At 700 °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.