Influence of buffer layers and barrier metals on properties of (Ba, Sr)TiO3 films prepared by liquid source chemical vapor deposition

The characteristics, especially the electrical properties, of (Ba, Sr)TiO3 [BST] films obtained by a two-step process of liquid source chemical vapor deposition (CVD) on two types of substrates or Ru/Si and Ru/TiN/Ti/Si structures have been investigated. First, the studies on the best deposition conditions for BST buffer layers on Ru/Si substrates indicated that more crystallized buffer layers improved the electrical properties of the two-step-deposited BST films. The reproducibility of the measured thicknesses was 1.5% (1 sigma) and that for t(eq)-values of equivalent SiO2 thicknesses was 5.4% (1 sigma) for seven consecutive two-step runs on Ru/Si substrates. Moreover, the insertion of the barrier metals TiN/Ti between Ru and Si, which was stable enough for back-end processing at high temperatures, increased the degree of some crystal orientations of BST and Ru films; however, it hardly changed the electrical properties of the BST films deposited in two-steps.