Industrially-scaled room-temperature pulsed laser deposition of Ti-TiN multilayer coatings

The aim of the current work is the transfer of multilayer design knowledge on the Pulsed Laser Deposition (PLD) technique for industrially-scaled room-temperature growth of titanium – titanium nitride (Ti–TiN) structures. Because almost all PVD and CVD coating techniques require substrate temperatures > 200°C for sufficiently adhering and dense coatings, there is high demand for the development of large-area and high-rate low-temperature vacuum deposition process like the PLD, e.g. for the coating of temperature-sensitive or shapedistortion- sensitive materials and substrates. A pulsed Nd:YAG laser (wavelength: 1064 nm) was used for depositing alternately Ti and TiN layers in Ar and N₂ atmosphere, resp., forming nearly particulate-free, very smooth and dense 1 μm thick coatings. Starting from single layers, in multilayers with thicker individual layers hardness and scratch resistance (critical load in scratch tests) is decreased, but this trend is reversed in multilayers of very thin (< 100 nm)individual layers. In contrast, the compressive growth stress is dropping down continuously in the multilayers of increasing period numbers.