In this paper the thermal stability of Ag-W film was determined from Ag diffusion onto SiO2 and was compared to that of pure Ag and Cu. Including W in the Ag films changes the film morphology and, as a result, the metal film stability. The metal films were deposited on SiO2/Si substrate by electroless (El) and Ion-Beam Sputtering (IBS) methods and MOS capacitors were prepared. The Ag diffusion onto SiO2 was studied at temperatures in the range of 450°C - 475°C using SIMS and AES depth profiling tools. The silver diffusivity in the oxide for Ag-W was in the range of 2 × 10-15 cm2/sec at 475°C. This is one order of magnitude less than that of pure Ag and Cu measured on similar devices. The experimental Ag diffusion measurements results indicate that silver transport through oxide is slower than that of Cu. The Ag diffusion profiles for Ion-Beam Sputtered Ag-W had lower Ag concentration and shallower depth in the oxide when compared to the samples made by electroless deposition.
- Ion-Beam Sputtering (IBS)