We propose and demonstrate the application of a test structure to characterize electrical properties of ultra-thin titanium nitride films passivated by a non-conducting amorphous silicon layer. The amorphous silicon layer is used to prevent the oxidation of the conducting layer. Platinum electrodes are realized on top of the a-Si. Good electrical contact between TiN and Pt is subsequently obtained by the silicidation reaction of a-Si and Pt at a relatively low temperature.