| Pacific Rim Symposium on Surfaces, Coatings and Interfaces (PacSurf 2016) | |
| Thin Films | Monday Sessions |
| Session TF-MoM |
| Session: | Advances/Innovation in Synthesis & Characterization |
| Presenter: | Grzegorz Greczynski, Linköping University, Sweden |
| Authors: | G. Greczynski, Linköping University, Sweden J. Lu, Linköping University, Sweden O. Tengstrand, Linköping University, Sweden I. Petrov, Linköping University, Sweden, University of Illinois at Urbana-Champaign J.E. Greene, Linköping University, Sweden, University of Illinois at Urbana-Champaign W. Kölker, CemeCon AG, Germany S. Bolz, CemeCon AG, Germany C. Schiffers, CemeCon AG, Germany O. Lemmer, CemeCon AG, Germany L. Hultman, Linköping University, Sweden |
| Correspondent: | Click to Email |
Growth of thin films by physical vapor deposition (PVD) typically requires elevated substrate temperatures and/or ion irradiation to ensure high adatom mobilities necessary for film densification. However, obtaining densification via high incident gas-ion energies extracts a steep price in the form of residual ion-induced compressive stress resulting from both recoil implantation of surface atoms and trapping of rare-gas ions in the lattice. Our solution for these issues employs high-power pulsed magnetron sputtering (HIPIMS) owing to the high ionization degree of sputter-ejected metal atoms, and the time separation of metal- and gas-ion fluxes incident at the substrate. The former implies that ion fluxes originating from elemental targets operated in HIPIMS are distinctly different from those obtained during dc magnetron sputtering (DCMS). The latter feature allows us to suppress the role of gas-ion irradiation, by synchronizing the pulsed substrate bias with the metal-rich-plasma portion of the HIPIMS pulse.1
We carry out experiments in a hybrid configuration with one target powered by HIPIMS and the other operated in DCMS mode (HIPIMS/DCMS).2,3 This allows us to probe the roles of intense metal-ion fluxes from HIPIMS-powered targets on film growth kinetics, microstructure, and physical properties over a wide range of transition metal nitride M1M2N alloy compositions. Model materials systems include TiAlN, TiSiN, TiTaN, and TiAlTaN. In a series of extensive experiments, we established that the essential factors determining film growth pathways include (i) the average metal-ion momentum transfer per deposited atom , (ii) metal-ion charge state, and (iii) mass of metal ion assisting the growth.4
Based on the above results, a new PVD approach is proposed which relies on the hybrid concept to grow dense, hard, and stress-free thin films with no external heating.5 TiTaN and TiAlTaN film densification is achieved by pulsed synchronized bombardment with Ta+/Ta2+ metal ions which are film constituents; this, in turn, minimizes film stress. The preliminary results are very promising. For example, with as little as 8 mol% of TaN, fully-dense TiTaN alloys with high hardness and low residual stress can be obtained at temperatures Ts < 150 °C (due to plasma heating). This novel approach expands the PVD process envelope to allow the use of temperature-sensitive substrates, including plastics.
[1] G. Greczynski, J. Lu, J. Jensen, I. Petrov, J.E. Greene, S. Bolz, W. Kölker, Ch. Schiffers, O. Lemmer and L. Hultman, JVSTA 30 (2012) 061504-1
[2] G. Greczynski, J. Lu, M. Johansson, J. Jensen, I. Petrov, J.E. Greene, and L. Hultman, Surf. Coat. Technol. 206 (2012) 4202.
[3] G. Greczynski, J. Lu, M. Johansson, J. Jensen, I. Petrov, J.E. Greene, and L. Hultman, Vacuum 86 (2012) 1036
[4] G. Greczynski, J. Lu, J. Jensen, I. Petrov, J.E. Greene, S. Bolz, W. Kölker, Ch. Schiffers, O. Lemmer and L. Hultman, Thin Solid Films, 556 (2014) 87
[5] G. Greczynski, J. Lu, I. Petrov, J.E. Greene, S. Bolz, W. Kölker, Ch. Schiffers, O. Lemmer and L. Hultman, JVSTA 32 (2014) 041515