Electroless and sputtered silver-tungsten thin films for microelectronics applications

Thin silver-tungsten (Ag-W) films have been deposited on Si and SiO2 substrates by electroless (El) and ion-beam sputtering (IBS) methods and their morphology was studied by optical and atomic force microscopy. Adding tungsten into the silver film significantly improved its corrosion stability, electrical, optical and mechanical properties. TEM microstructure investigation shown that W is introduced into Ag film in the form of WO3. In this paper we compare the resistance, reflectance and morphology, as determined by atomic force microscopy, of Ag-W films deposited by El and IBS methods for microelectronics application. Finally we present results of the Ag-W films study as barrier for silver metallization by MOS capacitors measurements. The capacitors exhibited almost ideal C-V high frequency characteristics and flat band voltage near to zero. The generation life-time (τ) and the recombination surface velocity (s) were of the same order of those for similar structures with Cu, Co and Al metallization. Those results indicate that Ag-W layers are MOS technology compatible and can be used in microelectronics as a new interconnect and metallization material.