Hot Target. Physicochemical Model of Reactive Sputtering

Abstract

In this paper, we further develop the non-isothermal physicochemical model of reactive sputtering. A new version of the model describes the sputtering of a hot metal target in a mixture of argon and a reactive gas. The synthesis of the film on all surfaces of a vacuum chamber is specified as a surface chemical reaction. The basic postulate of chemical kinetics considering the Langmuir isotherm equation and the Arrhenius equation under non-isothermal conditions was used for mathematical description of the reaction. The dependence of target temperature on discharge current density is determined based on the measurement results of discharge spectra in the near-infrared range. A system of eight algebraic equations is proposed for the analytical description of the model. Using this system, the analysis of the effect of current density and reactive gas consumption on reactive sputtering of a hot titanium target in an argon + nitrogen mixture at a current density of 25–600 A/m² was performed. Warming up the target was established to shift the points of change in target operation modes to a region of lower nitrogen flow rates and reduce the hysteresis loop width as compared to a cold target. In this case, the effect of target evaporation on the process begins to occur at a current density of more than 400 A/m².