Real time resistivity measurements during sputter deposition of ultrathin copper films

Abstract

Measurements of the electrical resistivity of thin copper films sputtered onto silicon dioxide, in real time, are reported. The electrical resistivity is shown to strongly depend on the film’s thickness for thicknesses below the bulk mean free path of copper (39 nm). Model fits to the electrical resistivity combined with ex situ atomic force microscopy and transmission electron microscopy suggest that the average grain size plays a dominant role in the resistivity during growth. Furthermore, observations are made on the relaxation of the electrical resistivity after the growth (by sputtering) is terminated, at room temperature. Both the magnitude and the time scale of change in the electrical resistivity are observed to be a function of the film’s thickness.