Ultra Thin TiN Films Prepared by an Advanced Ion-Plating Method

Abstract

We have prepared ultra thin TiN films using an advanced ion-plating (AIP) apparatus developed by ShinMaywa Industries. In AIP, RF and/or DC bias voltages are applied to the substrate holder and then a capacitor is formed between the substrate holder and the chamber. Eventually, it becomes easy to sustain a stable plasma at Ar pressures at as low as 10 -3 Pa. We clarified the characteristics of the AIP method through the deposition of ultra thin TiN films and examined new application areas for TiN thin films. TiN thin films (thickness: 5 and 25 nni) were prepared by AIP and also by DC sputtering without substrate heating. Then we measured the resistivity and observed the nanometer scale surface morphology of the thin films. Although the initial resistivities of both films were close (200 x 10 -8 Ω.m), the resistivity of the sputtered film ruse to twice that of the AIP film 50 hours later. Atomic force microscopy measurements showed flat, fine grains spread uniformly over the surface in the AIP film, while many isolated crystal islands were formed in the sputtered film. Our findings indicated that the AIP films have a potential use as wiring material. We thought that the AIP deposition enhances surface migration more than sputtering does as a result of efficient excitation of impinging TiN clusters in the Ar plasma region.