Internal stress and adhesive strength of reactive magnetron sputtered indium tin oxide films on acrylics

Indium tin oxide (ITO) films were deposited on acrylics by low temperature reactive magnetron sputtering. The effects of oxygen flow and film thickness on the internal stress and adhesion of ITO films on acrylics were evaluated. Results from the measurement of lattice parameters suggested that the internal compressive stress parallel to the film surface increased with increasing oxygen flow rate. This was possibly due to the peening effects of bombarding particles and the decrease in oxygen vacancies at relatively high oxygen flow. Observation of scratched surface after adhesion test showed that tensile bending moments occur within the coating as it was pushed down underneath the adhesion test indenter. The critical scratching load of ITO films invariably increased with oxygen flow and decreased with increasing thickness.