Research

Our group is mainly interested in the development of precursors and processes for atomic layer deposition (ALD); we were the first academic research group in Canada to work in this field.

As synthetic chemists, we try to determine the mechanism of the surface chemistry and thermal decomposition routes to better design precursors and tune our processes. We look at many different processes and target films, but some themes can broadly be drawn through our work.

Stepwise Mechanistic Chemistry

Mechanistic understanding allows a significant advantage to an ALD process: knowing how thermolysis occurs permits redesign of precursors or processes to exploit the mechanism to tune processes.

The standard mechanistic steps in metal-organic chemistry can illuminate thermal chemistry and surface chemistry. Our group has on this topic, and have used this understanding to detail surface and thermal chemistry, for instance, in and deposition chemistry.

Group 11 Compounds

We have been interested in group 11 metals for several years, and have contributed to precursor and process design for copper and gold metal ALD solutions.
We employ guanidinates, iminopyrrolidinates, and silylamides as anionic ligands for copper metal precursors, occasionally employing carbenes as a neutral coordination ligand to complete the coordination environment for Cu(I). The best example of a precursor is a hexamethyldisilazido N-heterocycliccarbene copper(I) that deposits or on silicon and glass.

We have also reported the first ALD deposition of , with followup examples of and processes. These processes use a trimethyl trimethylphosphine gold(III) precursor that is a liquid at room temperature and exhibits surprising stability to oxygen and water.

Chemistry of ALD – A Textbook

You can , and the Amazon author page can be found .

I hope it to be the backbone of a course on ALD chemistry; it isn鈥檛 comprehensive with respect to precursors or surface chemistry but rather goes through the core concepts of understanding ALD from a chemistry point of view.

Barry, S. T. Chemistry of Atomic Layer Deposition; De Gruyter.

Ligand Design

We developed iminopyrrolidinate ligands as an answer to the low-temperature thermolysis that can occur in amidinates and guanidinates. This took a LOT of thermolysis, modeling, and grad-student-hours. It might be my favourite chemistry we’ve done. The key message is:

iminopyrrolidinates tend to raise precursor thermolysis temperature by about 200掳C

Barry, S. T. Amidinates, Guanidinates and Iminopyrrolidinates: Understanding Precursor Thermolysis to Design a Better Ligand.聽Coord. Chem. Rev. 2013, 257, 3192 鈥� 3201.

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Precursors for CVD and ALD

In general, our group stays up at night worrying about five things:

melting point
chemical reactivity
thermal stability
volatility
self-limiting behaviour

We want to control these in all of our precursors. The key messages are:

thermal stability is key
“chemical reactivity” can mean both chemisorption as well as chemical potential of the surface moiety
designing precursors is not complicated, but it is difficult

Koponen, S. E.; Gordon, P. G.; Barry, S. T. Principles of Precursor Design for Vapour Deposition Methods. Polyhedron 2016, 108, 59 鈥� 66.