| AVS 62nd International Symposium & Exhibition | |
| Advanced Surface Engineering | Tuesday Sessions |
| Session SE+PS-TuA |
| Session: | Pulsed Plasmas in Surface Engineering |
| Presenter: | Grzegorz Greczynski, Linköping University, Sweden |
| Authors: | G. Greczynski, Linköping University, Sweden I. Petrov, University of Illinois at Urbana Champaign J.E. Greene, University of Illinois at Urbana-Champaign L. Hultman, Linköping University, Sweden |
| Correspondent: | Click to Email |
Energy- and time-dependent mass spectroscopy is used to determine the relative number density of singly- and multiply-charged metal ions incident at the substrate during high-power pulsed magnetron sputtering (HIPIMS) as a function of the average noble-gas ionization potential. We selected Ti as the sputtering target since the microstructure, phase composition, properties, and stress-state of Ti-based ceramic thin films grown by HIPIMS are known to be strongly dependent on the charge state of Tin+ (n = 1, 2, …) ions incident at the film growth surface. [1,2] Mass spectroscopy results show that the flux of Tin+ with n > 2 is insignificant; thus, the Ti2+/Ti+ integrated flux ratio JTi2+/JTi+ is measured at the substrate position as a function of the choice of noble gas -- Ne, Ar, Kr, Xe, as well as Ne/Ar, Kr/Ar, and Xe/Ar mixtures -- supporting the plasma. We demonstrate that by changing noble-gas mixtures, JTi2+ varies by more than two orders of magnitude with only a small change in JTi+. This allows the ratio JTi2+/JTi+ to be continuously tuned from less than 0.01 with Xe, which has a low first-ionization potential IP1, to 0.62 with Ne which has a high IP1. The value for Xe, IP1Xe = 12.16 Ev, is larger than the first ionization potential of Ti, IP1Ti = 6.85 Ev, but less than the second Ti ionization potential, IP2Ti = 13.62 Ev. For Ne, however, IP1Ne = 21.63 Ev is greater than both IP1Ti and IP2Ti. Therefore, the high-energy tail of the plasma-electron energy distribution can be systematically adjusted, allowing JTi2+/JTi+ to be controllably varied over a very wide range, from 0.01 with Xe to 0.62 with Ne. [3]
[1] G. Greczynski, J. Lu, M. Johansson, J. Jensen, I. Petrov, J.E. Greene, and L. Hultman, Surf. Coat. Technol. 206 (2012) 4202
[2] G. Greczynski, J. Lu, M. Johansson, J. Jensen, I. Petrov, J.E. Greene, and L. Hultman, Vacuum 86 (2012) 1036
[3] G. Greczynski, I. Petrov, J.E. Greene, and L. Hultman, Vacuum 116 (2015) 36