Nanoscale friction of partially oxidized silicon nitride thin films

The nanoscale friction of partially oxidized silicon nitride thin films deposited by reactive magnetron sputtering was investigated. Post deposition thermal annealing in O2, trying to simulate the oxidation by atmospheric oxygen in working conditions, formed a partially oxidized layer at the surface with maximum thickness around 10nm. Unidirectional sliding tests showed a decrease of the low-load friction coefficients of the sliding pair for the samples annealed in oxygen as compared to the non-annealed ones. The results are discussed on the lights of our extension of the crystal chemistry model, which establishes a relationship between ionic potential and friction coefficient. ► The nanoscale friction behavior of partially oxidized Si3N4 thin films is studied. ► A modification of the crystal chemistry model for tribology is suggested. ► Ultra-low friction coefficients for SiOxNy are observed.