Growth and characterization of zirconium oxynitride films prepared by reactive direct current magnetron sputtering

Thin films of zirconium oxynitrides have been deposited onto Si(100) substrates at room temperature by reactive dc magnetron sputtering of a metallic Zr target in an argon–oxygen–nitrogen atmosphere. To prepare oxynitride films the sum of the O2 and N2 flow was kept at 3.5 sccm, while the relative nitrogen content of this mixture was changed stepwise from 0% to 100%. The film structure was determined by x-ray diffraction, while x-ray reflectometry was employed to determine the thickness, density, and surface roughness of the films. The optical properties have been studied by spectroscopic reflectance measurements. X-ray diffraction (XRD) determines that the as-deposited films are crystalline and do not change their monoclinic ZrO2 crystal structure even for nitrogen flows up to 80%. For pure argon–nitrogen sputtering, on the contrary, cubic zirconium nitride (ZrN) has been formed. Nevertheless, even though the crystal structure does not change with increasing nitrogen flow up to 80%, there is clear eviden...