High Resistivity of dc-Sputtered Metal Films

Abstract
Tungsten films were sputtered at 1.5‐kV cathode voltage under various sputtering conditions. It was found that their resistivities differ greatly, ranging from 5×103 μΩ. The higher‐resistance case corresponds to films deposited in the diode mode at 50‐μ argon pressure, and the lower to films deposited in the triode made at 2‐μ pressure. The higher‐resistivity tungsten films have properties similar to the so‐called ``low‐density tantalum'' and a host of other metal films which have been prepared under similar sputtering conditions. Analysis by rf spark‐source mass spectroscopy and electron microscopy support the theory that the high resistivity was caused by the incorporation of residual gases during the growth process.