Nanotribological, nanomechanical and interfacial characterization of Atomic Layer Deposited TiO2 on a silicon substrate

For every coating it is critical that the coatings are sufficiently durable to withstand practical applications and that the films adhere well enough to the substrate. In this paper the nanotribological, nanomechanical and interfacial properties of 15-100 nm thick atomic layer deposited (ALD) TiO₂ coatings deposited at 110-300 °C were studied using a novel combination of nanoscratch and scanning nanowear testing. Thin film wear increased linearly with increasing scanning nanowear load. The film deposited at 300 °C was up to 58±11 %-points more wear-resistant compared to the films deposited at lower temperatures due to higher hardness and crystallinity of the film. Amorphous/nanocrystalline composite structure with agglomerated crystallites was observed with TiO₂ deposited at 200 °C and the agglomerates were up to 37±10 %-points more wear-resistant than the amorphous/nanocrystalline matrix. All of the tested films had excellent interfacial properties and no delamination was observed with the films outside of the scanned regions. These findings may prove useful in the development of tribological and mechanical characterization methods, and in developing thin film materials with enhanced properties tailored to their function. This will also help in the development and tuning of ALD processes.