Study of the optical properties of AlN/ZrN/AlN low-e coating

AlN/ZrN/AlN multilayers are deposited by magnetron sputtering onto borosilicate glass wafers. ZrN films have a high reflectivity in the IR range (∼85%) and AlN films have a high transmission in the visible range (∼90%). The multilayers are analysed in situ or after air contamination by X-ray photoelectron spectroscopy. This technique is used to analyse the interfaces. We observe the influence of the nitrogen partial pressure, bias voltage and post-annealing on the properties of the films (intermixing, oxygen diffusion). Then we correlate these results with the optical properties of the coating. The negative bias voltage has a great influence on the reflection of the multilayer coatings in the IR range. The layers intermixing at the interfaces are strongly dependant on the sputtered atoms energy at the surface of the growing film. This energy is controlled by the substrate bias voltage.