Texture and electromigration lifetime improvements in layered Al-alloy metallization with underlying Ti by controlling water adsorption on SiO_2 substrates

摘要

The effect of residual gas constituents and substrate temperature during Ti sputtering on the texture of TiN/Ti films deposited on SiO_2/Si substrates has been investigted. The Ti(002) and TiN(111) preferred texture of the films deposited at 350degC was foun to be improved drastically by increasing the H_2O partial pressure from 1x10~-9 to 3x10~-8 Torr. Both of the Ti(002) and TiN(111) textures showed a similar H_2O partial pressure and substrate temperature dependence because fo the eptiaxial transfer between these planes. The improved ti(002) texture was attributed to the self-assembly of Ti atoms on the SiO_2 surface, which had a low surface free energy due to the foramtion of surface OH groups. Two kinds of layered Al-alloy interconnects, A1SiCu/Ti/TiN/Ti and AlCu/TiN/Ti, were fabracted with the highly textured TiN/Ti film, and their Al(111) texture and electromigration lifetime were then evaluated. It was confirmed that both of the interconnects have strong Al(111) texture and longer EM lifetimes.