Texture and electromigration lifetime improvements in layered Al-alloy metallization with underlying Ti by controlling water adsorption on SiO2 substrates

The effect of residual gas constituents and substrate temperature during Ti sputtering on the texture of TiN/Ti films deposited on SiO2/Si substrates has been investigated. The Ti(002) and TiN(lll) preferred texture of the films deposited at 350(degree)C was found to be improved drastically by increasing the H2O partial pressure from 1*10^-9 to 3 * 10^-8 Torr. Both of the Ti(002) and TiN(lll) textures showed a similar H2O partial pressure and substrate temperature dependence because of the epitaxial transfer between these planes. The improved Ti(002) texture was attributed to the self-assembly of Ti atoms on the SiO2 surface, which had a low surface free energy due to the formation of surface OH groups. Two kinds of layered Al-alloy interconnects, AlSiCu/Ti/TiN/Ti and AlCu/TiN/Ti, were fabricated with the highly textured TiN/Ti film, and their Al(lll) texture and electromigration lifetime were then evaluated. It was confirmed that both of the interconnects have strong Al(lll) texture and longer EM lifetimes. (C) 1999 Elsevier Science Ltd. All rights reserved.