Multilayer thin films of TiN/SiNx have been deposited onto heated Si 100 substrates (200℃) by reactive dc-magnetron sputtering from Ti and Si targets in an Ar-N2 gas mixture. The rotation speed of the substrate holder was varied from 1 to 20rpm, while target currents were held constant, to produce bilayer periods varying from approximately 22 to 0.6nm. These multilayer films were characterized by atomic force microscopy (AFM), cross-sectional transmission electron microscopy (TEM), scanning electron microscopy (SEM), and microhardness measurements. TEM and SEM studies showed elimination of columnar structure in TiN, owing to the incorporation of amorphous SiNx layers. The crystallinity of TiN and amorphous nature of SiNx were confirmed by high resolution TEM. An optimum rotation speed was observed, at which hardness was a maximum. The resulting bilayer period was found to be approximately 1.6nm,which resulted in a significant improvement in microhardness (～5TGPa). The rms surface roughness for this film was less than 1.5nm.