Effect of pulse configuration on the reactive deposition of TiN coatings using HiPIMS

Abstract

In this work, TiN coatings are deposited using three different series of pulse configurations. Each series consisted of a single pulse of 90 μs, chopped into 2-, 3-, and 6-pulse sequences, where the short delay time between the sequential chopped pulses have been varied from 10 to 300 μs. This allows control of the intensity of the target peak current, which in turn affects the deposition rate and mechanical properties of the growing coatings. Results show that changing the pulse configuration resulted in a deposition rate comprised between 4.4 and 5.2 μm/h. The change observed in deposition rate can be attributed to several phenomena known to reduce the deposition rate. This includes gas rarefaction, self-sputtering, target poisoning, and power loss resulting from the increase in circuit impedance when power is switched on and off during the pulsing process. It was shown that strategic selection of the pulse configuration plays a crucial role in mitigating the negative impact of these phenomena which opens up favorable conditions for a substantial enhancement in the deposition rate. In fact, the proper choice of pulse configuration can result in an enhanced deposition rate of up to 12.3 % compared to the conventional single pulse case. An overall slight increase in the average hardness from 18.7 GPa to 19.8 and 22 GPa for the 2-, 3-, and 6-pulse series respectively, while no noticeable structural changes were observed.