SCANNING TUNNELING MICROSCOPE STUDY OF THE MORPHOLOGY OF CHEMICAL-VAPOR-DEPOSITED COPPER-FILMS AND ITS CORRELATION WITH RESISTIVITY

In this article we report the results of the scanning tunneling micros cope study of the surface morphology of copper films grown by metalorg anic chemical vapor deposition from the precursor Cu(tbaoac)(2). Films approximate to 100 nm in thickness were grown by varying the reactor pressure. The images reveal the crucial role of the reactor pressure a nd growth rate on the morphology and grain growth of the films. Films grown at a low growth rate have a smooth surface with small well conne cted grains of approximate to 10-40 nm diameter with relatively lower resistivity, while films grown at higher growth rates have rougher sur faces and larger grain sizes of approximate to 10-100 nm diameter with poor connectivity that leads to higher resistivity. file correlation of the morphology with resistivity (rho) and the temperature dependenc e of rho in the range 300-4.2 K was investigated. Comparison with the rho of pure bulk copper shows that these films have much higher resist ivities. A large part of the high resistivity at room temperature aris es from an enhanced temperature dependent part of rho and is not due t o an enhancement of the residual resistivity alone. The films exhibit deviations from Matthiessen's rule. From a semi-quantitative analysis of the data using existing theories we could assign the large rho as w ell as the temperature dependence of rho to grain boundary scattering and surface scattering. However, for T>50 K we find that an extra temp erature dependent rho term which may be related to enhancement of elec tron-phonon interactions by the rough film surface is required. (C) 19 97 American Institute of Physics.