Use of Selective CVD‐W with a Polyimide Mask for Local Interconnects

The use of selective chemically vapor deposited tungsten with a polyimide (P.I.) mask for local interconnects has been demonstrated with a sheet resistance of 0.60 Ω/□. The selective tungsten deposition conditions were examined. The growth rate (22-85 nm/min) was proportional to the SiH 4 partial pressure (0.15-0.60 mTorr). The W resistivity (14-26 μΩ-cm) and stress (5-19×10 9 dyne/cm 2 , in large features) decreased as the deposition temperature (300-360 o C) was increased. The selectivity was worse at higher deposition temperatures and improved for high WF 6 /SiH 4 ratio