Control of Ti1-xSixN Nanostructure via Tunable Metal-ion Momentum Transfer During HIPIMS/DCMS Co-Deposition

Low-energy inert-gas ion irradiation of the film surface during refractory transition-metal (TM) nitride growth by conventional DC magnetron sputtering has been used widely to overcome the characteristically underdense microstructures with rough surfaces of layers deposited at low temperatures (Ts/Tm < 0.30, in which Ts is the film growth temperature and Tm is the melting point in K)i.

It has been recently demonstrated that high-power pulsed magnetron sputtering (HIPIMS) provides an alternative route for ion-assisted TM nitride film growth by using substrate bias synchronized to the metal-rich portion of the plasma pulse. It is possible to dramatically reduce or even eliminate stresses since metal (as opposed to inert-gas) ions are components of the film.ii, iii

HIPIMS/DCMS Configuration

In this project, a hybrid HIPIMS/DCMS two-target co-sputtering configuration is used, in which one target (either Si or Ti ) is powered by HIPIMS while the other is powered by DCMS, for growth of Ti1-xSixN films with compositions 0 ≤ x ≤ 0.26. Markedly different film growth pathways are obtained based on which target is powered by HIPIMS with, in both cases, a substrate bias applied in synchronous with the HIPIMS pulse. The observed divergence in phase content, film nanostructure and mechanical properties between layers grown in Ti-HIPIMS/Si-DCMS and Si-HIPIMS/Ti-DCMS configuration is because of distinctly different metal-ion irradiation conditions, Ti+/Ti2+ vs. Si+/Si2+, during film growth, as established by the ion mass spectrometry analyses carried out at the substrate position with a Hiden Analytical EQP 1000 instrument (Figure 1(a)-(b)).

Ion energy distribution functions measured at the substrate position for (a) singly-charged Ti+ and Si+ ions, and (b) doubly-charged Ti2+ and Si2+ ions during Ti-HIPIMS and Si-HIPIMS pulses; (c) plan-view STEM micrograph, and (d) plan-view EDX/STEM elemental maps of a Ti0.74Si0.26N Ti-HIPIMS/Si-DCMS film, showing spatial distributions, acquired from the area outlined in panel (c); (e) nanoindentation hardnesses H(x) of Ti-HIPIMS/Si-DCMS and Si-HIPIMS/Ti-DCMS Ti1-xSixN films grown on Si(001) substrates at Ts = 500 °C.

Figure 1. Ion energy distribution functions measured at the substrate position for (a) singly-charged Ti+ and Si+ ions, and (b) doubly-charged Ti2+ and Si2+ ions during Ti-HIPIMS and Si-HIPIMS pulses; (c) plan-view STEM micrograph, and (d) plan-view EDX/STEM elemental maps of a Ti0.74Si0.26N Ti-HIPIMS/Si-DCMS film, showing spatial distributions, acquired from the area outlined in panel (c); (e) nanoindentation hardnesses H(x) of Ti-HIPIMS/Si-DCMS and Si-HIPIMS/Ti-DCMS Ti1-xSixN films grown on Si(001) substrates at Ts = 500 °C.

Conclusion

Better mass match between incident Ti+ ions and the average film atomic mass, higher metal-ion/metal-atom ratios and a high fraction of doubly-ionized species leads to an average momentum transfer per deposited atom (pd) ~20 times higher for Ti-HIPIMS/Si-DCMS than during Si-HIPIMS/Ti-DCMS. This results in increased adatom mean free paths, leading to the segregation of smaller Si atoms to column boundaries and the formation of a nanocomposite structure comprising of TiN-rich nanocolumns encapsulated in SiNx tissue phases (cf. plan-view STEM micrograph in Figure 1(c), and EDX/STEM elemental maps in Figure 1(d)). Ti-HIPIMS/Si-DCMS Ti1-xSixN films are superhard over a composition range that is significantly wider than reported previously, 0.04 ≤ x ≤ 0.26, with a maximum hardness, H = 45 GPa, for layers with x = 0.13 (Figure 1(e)). However, residual stresses are also high with an average value of 7±1 GPa.

In sharp contrast, during Si-HIPIMS/Ti-DCMS Ti1-xSixN film growth, the flux of doubly-ionized metal ions is lower which, along with the lower mass of Si, low metal-ion/metal-atom flux ratio during HIPIMS pulses, and poorer mass match between incident Si+ ions and average film atomic mass results in comparatively low values. This leads to trapping of Si in the metastable Ti1-xSixN NaCl structure in order to form solid solutions over the highest compositional range yet reported, 0 ≤ x ≤ 0.24.

Project summary by:

G. Greczynski
Thin Film Physics Division
Department of Physics (IFM)
Linköping University
SE-581 83 Linköping
Sweden

Paper Reference

G. Greczynski et al., (2015) “Control of Ti1-xSixN nanostructure via tunable metal-ion momentum transfer during HIPIMS/DCMS co-deposition”, Surface and Coatings Technology 280, 174-184

References

i I. Petrov, P.B. Barna, L. Hultman, J.E. Greene J. Vac. Sci. Technol. A 21 (2003) 117

ii G. Greczynski, J. Lu, I. Petrov, J.E. Greene, S. Bolz, W. Kölker, Ch. Schiffers, O. Lemmer and L. Hultman, J. Vac. Sci. Technol. A 32 (2014) 041515.

iii G. Greczynski, J. Lu, J. Jensen, I. Petrov, J.E. Greene, S. Bolz, W. Kölker, Ch. Schiffers, O. Lemmer and L. Hultman, J. Vac. Sci. Technol. A 30 (2012) 061504.

This information has been sourced, reviewed and adapted from materials provided by Hiden Analytical.

For more information on this source, please visit Hiden Analytical.

Citations

Please use one of the following formats to cite this article in your essay, paper or report:

  • APA

    Hiden Analytical. (2019, July 22). Control of Ti1-xSixN Nanostructure via Tunable Metal-ion Momentum Transfer During HIPIMS/DCMS Co-Deposition. AZoM. Retrieved on September 17, 2019 from https://www.azom.com/article.aspx?ArticleID=14013.

  • MLA

    Hiden Analytical. "Control of Ti1-xSixN Nanostructure via Tunable Metal-ion Momentum Transfer During HIPIMS/DCMS Co-Deposition". AZoM. 17 September 2019. <https://www.azom.com/article.aspx?ArticleID=14013>.

  • Chicago

    Hiden Analytical. "Control of Ti1-xSixN Nanostructure via Tunable Metal-ion Momentum Transfer During HIPIMS/DCMS Co-Deposition". AZoM. https://www.azom.com/article.aspx?ArticleID=14013. (accessed September 17, 2019).

  • Harvard

    Hiden Analytical. 2019. Control of Ti1-xSixN Nanostructure via Tunable Metal-ion Momentum Transfer During HIPIMS/DCMS Co-Deposition. AZoM, viewed 17 September 2019, https://www.azom.com/article.aspx?ArticleID=14013.

Ask A Question

Do you have a question you'd like to ask regarding this article?

Leave your feedback
Submit