Electroless deposition of novel Ag–W thin films

The seedless electroless deposition of silver–tungsten (Ag–W) thin films on silicon dioxide substrate was performed using wet palladium activation from ammonia–acetate and benzoate solutions. Introducing tungsten in the plating bath catalyzes the deposition for benzoic acid solution and decreases the deposition rate for ammonia–acetate solution. The tungsten content in the deposit was 0–1.0 at%, mainly in WO_x form. It was found that the electrical, optical, and mechanical properties of the Ag–W films depends on the W content in the deposit. The optimal Ag–W thin films that were deposited from either the ammonia–acetate or benzoate bath demonstrate good adhesion to the substrate, high brightness, and do not corrode at temperatures up to 350 °C in air. Sub-100 nm thick Ag–W deposits have demonstrated resistivity of about 4 μΩ cm after vacuum annealing at 350 °C for 1 h. Finally, we present the film microstructure characterization and discuss the possibility of using Ag–W thin films for advanced microelectronics metallization.