CNxTiy/TiN multilayers have been synthesized using dual-ion-beam deposition. X-ray photoelectron spectra of C 1s, Ti 2p, N 1s, and Si 2p electrons were investigated against the depth from the film surface. The results confirm the layered structure of the films. The Ti atoms contained in a CNxTiy layer sandwiched between two TiN layers are expected to come from interlayer diffusion of Ti atoms enhanced by ion beam irradiation during deposition. As a consequence, a CNxTiy layer contains a C–N phase, a Ti–N phase, and a T–C phase. The C–N phase contains 27 at. % nitrogen, less than the level required to form the hypothetical β-C3N4 phase, indicating that the multilayer structure containing TiN layers does not favor for increasing N content in the C–N phase of the CNxTiy layers. The Ti–N and Ti–C phases are about stoichiometric. The TiN layers comprise mainly a Ti–N phase, and a small fraction of the Ti–C phase, which are both stoichiometric. However, the bonding between C and N is weak. The hardness H and elastic modulus E of the films were investigated by nanoindentation experiments. The single-layer CN0.3 is the softest (H=11.4 GPa), and the single-layer TiN is the hardest (H=22 GPa) among the samples in the series. H and E increase with increasing TiN volume fraction, as well as the number of interface- - s. They also increase with increasing substrate temperature, possibly due to stronger interlayer diffusion of Ti atoms at higher temperature. © 1997 American Vacuum Society.