| AVS 64th International Symposium & Exhibition | |
| Thin Films Division | Thursday Sessions |
| Session TF-ThM |
| Session: | Area-selective Deposition and Infiltration Growth Methods |
| Presenter: | Elham Mohimi, University of Illinois at Urbana-Champaign |
| Authors: | E. Mohimi, University of Illinois at Urbana-Champaign Z. Zhang, University of Illinois at Urbana-Champaign S. Liu, University of Illinois at Urbana-Champaign B.B. Trinh, University of Illinois at Urbana-Champaign J.L. Mallek, MIT Lincoln Laboratory G.S. Girolami, University of Illinois at Urbana-Champaign J.R. Abelson, University of Illinois at Urbana-Champaign |
| Correspondent: | Click to Email |
In the fabrication of nanoscale devices, the top-down process of lithography and etching is time consuming and expensive. A proposed bottom-up approach – area selective growth – would enable device fabrication beyond conventional patterning limits: thin films would preferentially deposit onto pre-existing portions of a structure with no nucleation and growth on other surfaces. However, a selective process is subject to statistical failure – the nucleation of unwanted material – when it relies on the initial characteristics of the non-growth surface, either the inherent chemical properties or passivation pre-treatments. A robust process requires dynamic control of selectivity to ensure that no stray nucleation occurs on the intended non-growth surfaces for the total time required to deposit film on the device areas.
Here, we present a perfectly selective CVD method which involves adding a neutral molecule “inhibitor” to the process gas mixture: the inhibitor dynamically populates oxide surfaces and prevents nucleation while permitting the deposition of film on metal surfaces, where the inhibitor effect is weaker. Because the inhibitor concentration on the oxide surfaces is continuously replenished, it completely eliminates film nucleation on defects or impurity sites.
We previously demonstrated perfectly selective copper CVD using the Cu(hfac)VTMS precursor with additional VTMS as the inhibitor: no nucleation occurs on thermal SiO2 or on porous, carbon doped oxide, while copper growth occurs on areas covered with a ruthenium seed layer [1]. The excess VTMS scours Cu(hfac) intermediates off the dielectric surface prior to the disproportionation (growth) reaction. Here, we extend the method by using a different class of inhibitor molecules to afford the selective CVD of transition metals and their compounds on a wide variety of oxide substrates; and we explain the mechanism of selectivity .
1. S. Babar, E. Mohimi, B. Trinh, G. S. Girolami and J. R. Abelson, "Surface-selective chemical vapor deposition of copper films through the use of a molecular inhibitor," ECS J. Solid State Sci. Tech. 4(7), N60-63 (2015)