This article studies the microstructure and mechanical properties of diamond-like carbon films (α-C), depending on their architecture. The bilayer (titanium/a-C) and (titanium nitride [TiN]/a-C) films were deposited from the flows of the metal plasma, formed through sputtering a titanium cathode by a direct current arc, and the carbon plasma, formed as a result of pulsed arc sputtering of a graphite cathode. The effect of titanium and TiN sublayers on the structure and mechanical properties of carbon films has been shown. It has been found that the catalytic effect of the sublayer is most pronounced when the carbon layer thickness is less than 90 nm; when the carbon layer thickness is less than 30 nm, the size of Csp² clusters decreases, and the fraction of atoms with Csp³ bonds increases. The annealing of the films does not significantly affect the behavior of the phase composition and the structure of the films with an increase in the carbon layer thickness. It has been demonstrated that the size dependences of the optical properties, which are manifested in a transparency increase and a change in the band gap when increasing the carbon layer thickness, are associated with the occurrence of mutual diffusion processes in the interfacial zone.