| AVS 64th International Symposium & Exhibition | |
| Thin Films Division | Thursday Sessions |
| Session TF-ThM |
| Session: | Area-selective Deposition and Infiltration Growth Methods |
| Presenter: | Adrie Mackus, Eindhoven University of Technology, The Netherlands |
| Authors: | S.N. Chopra, Eindhoven University of Technology, The Netherlands M.F.J. Vos, Eindhoven University of Technology, The Netherlands J.G. Ekerdt, The University of Texas at Austin W.M.M. Kessels, Eindhoven University of Technology, The Netherlands A.J.M. Mackus, Eindhoven University of Technology, The Netherlands |
| Correspondent: | Click to Email |
Area-selective atomic layer deposition (ALD) is expected to be an enabling technology for the fabrication of future nanoelectronics with sub-10 nm dimensions. In practice it is extremely difficult to achieve high selectivity for area-selective ALD because of undesirable growth initiation on defects and impurities. Given that many processes exist for etching materials, novel combinations of area-selective ALD and etching are currently being considered to eliminate this unwanted growth.1 In this work, the selectivity of area-selective ALD of Ru on Pt patterns (metal-on-metal deposition) is improved by etching Ru using an O2 plasma after or during the deposition.
ALD of Ru was carried out using an ABC-type process consisting of ethylbenzene-cyclohexadiene Ru(0) precursor, O2 gas, and H2 gas steps. The additional H2 dosing step ensures that metallic Ru is deposited by reducing the RuO2 top layer every cycle. This ABC-type ALD process allows for Ru deposition at low temperatures to exploit the larger differences in growth rates on SiO2 versus Ru or Pt for achieving area-selective ALD. However, even at the low temperature of 150 ºC, for which 500 Ru ALD cycles on Ru resulted in 17.5 nm growth, undesirable Ru islands were observed on the SiO2 non-growth substrate.
When Ru is exposed to O3 or to an O2 plasma, RuO4 is formed as a volatile reaction product. Because O2 plasma has a high selectivity toward Ru etching, it can be used in a post-deposition treatment to eliminate residual Ru islands from the SiO2 non-growth substrate. Area-selective ALD with an almost perfect selectivity was obtained when performing supercycles consisting of Ru ABC cycles and an O2 plasma etch step every 100 cycles. The selectivity of the growth was investigated by performing Ru ALD on Pt-containing seed layers patterned by electron beam induced deposition (EBID) on SiO2 substrates.2 The O2 plasma etch does not significantly influence the properties of the Ru on the seed layer patterns as will be shown in the presentation.
1. R. Vallat, R. Gassiloud, B. Eychenne, and C. Vallée, J. Vac. Sci. Technol. A.35, O1B104 (2017)
2. A.J.M. Mackus, S.A.F. Dielissen, J.J.L. Mulders, and W.M.M. Kessels, Nanoscale 4, 4477 (2012).