The state of coating–substrate interfacial region formed during TiO2 coating deposition by Gas Injection Magnetron Sputtering technique

Rafał Chodun , Katarzyna Nowakowska-Langier , Bartosz Wicher , Sebastian Okrasa , Roch Kwiatkowski , Dobromil Zaloga , Marlena Dypa , Krzysztof Zdunek

Abstract

This manuscript presents the nature of interaction of energetic plasmoids, generated in the Gas InjectionMagnetron Sputtering (GIMS) technique, with the surface of substrate or the coating–substrate system. We ex-pected that the plasma generated by a dynamic injection of gas (GIMS) is better ionized than the plasma gen-erated in stationary pressure in its standard range for magnetron sputtering. The GIMS technique operates underconditions that may favor the plasma species to retain their kinetic energy, limiting the probability of inter-molecular collisions events. In this experiment, the frequency of injecting small amounts of gas was used as aparameter to control the pressure amplitudes, thus achieving the conditions of plasma generation from sta-tionary, through quasi-stationary, to pulsed oscillations of pressure. The optical emission spectroscopy (OES)was used to evaluate the state of deposition environment in GIMS. Investigation showed that the plasmaspectrum consists of higher population of ions in the conditions of high amplitude of pressure oscillations. Thephase content of a titanium dioxide coating, deposited under various conditions of plasma generation, alsodepends on the energetic state of plasma. Raman spectroscopy proved that the stationary condition favors theanatase phase as the nucleation phase, while with the increase in the non-equilibrium of plasma, the metastablerutile phase is more expected. The effects of strong impingement of energetic species were observed, causingcrystallization of the amorphous phase of coatings, with sputtering of the substrate surface and the formation ofa specific type of coating–substrate interfacial region