We work to observe individual ALD half-reactions using in-situ tools, including in-situ infrared transmission spectroscopy using the reaction shown schematically on the left. The second image shows results collected during ALD of aluminum oxide from trimethylaluminum and water. The mode changes reflect the change in surface termination.
As a recent example, we use in-situ IR to examine interactions between TMA and the polymer poly(methyl)methacrylate. The third image shows ab-initio quantum mechanical analysis of possible vibrational modes, and the fourth image shows the vibrational modes obtained experimentally. By comparing the predicted and observed spectra, we can identify likely product structures and reaction pathways, as shown on the bottom of the third image.
This and other in-situ characterization tools give us unique insights into many ALD reaction schemes, providing new understanding of ALD surface reactions and mechanisms to help design full-scale processes.
You can read more about this method and results in these journal publications:
- EC Dandley et al., “Temperature-dependent reaction between trimethylaluminum and poly(methyl methacrylate) during sequential vapor infiltration: experimental and ab initio analysis” Journal of Materials Chemistry C 2, 9416-9424 (2014)
- GN Parsons et al., “Mechanisms and reactions during atomic layer deposition on polymers” Coord. Chem. Rev 257 (2013) DOI: 10.1016/j.ccr.2013.07.001»