Defect growth in multilayer chromium nitride/niobium nitride coatings produced by combined high power impulse magnetron sputtering and unbalance magnetron sputtering technique

In recent years, high power impulse magnetron sputtering (HIPIMS) has caught the attention of users due to its ability to produce dense coatings. However, microscopic studies have shown that HIPIMS deposited coatings can suffer from some surface imperfections even though the overall number of defects can be significantly lower compared to, for example, arc deposited coatings of similar thicknesses. Defects can degrade the coating performance thus any kind of defect is undesirable. To better understand the nature of these imperfections and the science of their formation, a series of chromium nitride/niobium nitride (CrN/NbN) coatings were deposited using HIPIMS technique combined with unbalanced magnetron sputtering (UBM) by varying deposition times (t=15 to 120min). All other deposition parameters were kept constant in order to deposit these coatings with a consistent deposition rate and stoichiometry.