Factors which determine the orientation of CVD Al films grown on TiN

CVD Al deposited on a TiN/Ti liner followed by 'warm' PVD Al (Cu) is a promising approach for filling high aspect ratio vias. A highly (111) textured film is important to achieve high electromigration resistivity. The dependence of the Al orientation on the type of the underlying TIN liner and the mechanism responsible for this effect were investigated. HRTEM was used to characterize the structure of the Al grains (after 1 s of deposition), through to a continuous film, as well as the structure of the interface of thick Ai films with TiN. The microscopy results helped to explain the X-ray diffraction observations that on PVD TIN the Al film had a stronger (111) texture than on other TiN types. This is attributed to a topotaxial relationship, which forms during the nucleation stage of the CVD Al. (C) 1999 Elsevier Science Ltd. All rights reserved.