A novel 0.25 μm via plug process using low temperature CVD Al/TiN

A novel aluminum plug process is described which offers over a 3× reduction in via resistance as compared with current tungsten plug technology. The performance advantage of the new process is further enhanced by its compatibility with low thermal budget, low-k dielectric materials, allowing significant reduction in the overall interconnect RC time constant. Key features of the Al plug technology include an over-hang free MOCVD (metal organic CVD) TiN liner, a single step low temperature (260°C) chemical vapor deposition (LTCVD) of aluminum (resistivity <3 μohm-cm) and copper doping from an overlying PVD Al-Cu film. Double-level metal interconnects with 0.3 μm vias and integrated low-k dielectrics were successfully fabricated using the new CVD TiN/Al technology. The 0.3 μm diameter CVD Al plugs yielded >3× lower via resistance compared with W plugs (1.5 vs. 5.0 ohms) with no degradation in electromigration reliability