Advanced characterizations of fluorine-free tungsten film and its application as low resistance liner for PCRAM

The W liner with thicknesses ranging from 3 to 4 nm has been implemented on PCRAM structures in order to evaluate its impact on contact plug resistivity. First electrical results are promising and demonstrate the interest of using a F-free low resistance W liner. At the aspect ratio studied, the gain in terms of contact plug resistivity is about 20% compared to the process of reference using a TiN liner. Modeling shows that this benefit is mainly due to the reduction of interface resistances.