Speaker: Theodosia Gougousi, Physics, U.
Date & Time: March 30, 2006 - 12:00pm
Location: Room 260 Wright-Rieman Chemistry
Nucleation, composition and morphology of metal oxide films using ALD and Supercritical CO2 assisted deposition
Laboratory for Surface Modification
Theodosia Gougousi, Physics, U. Maryland@Baltimore<br< a="">>12:00 Noon, Room 260 Wright-Rieman Chemistry
In the first part of my talk I will describe our recent work on supercritical fluid based thin film deposition. The objective of our work is to investigate whether solvation forces from supercritical fluids can be used to enable deposition of thin insulating films with good interfacial properties. Mainstream vacuum-based deposition techniques are usually mass transport limited by the low vapor pressure of the precursors, and proceed through a chemical reaction on a heated substrate (>300C). Our novel chemical approach is a low temperature (<150C), high pressure process that uses solvation forces from supercritical carbon dioxide to: a) transport high concentrations of soluble organic peroxides and metal organic precursors to a surface, b) provide energy for film formation, and c) accomplish reaction by-product removal. This research is important because fabrication of future nanoscale devices may entail formation of multilayer miniaturized structures on patterned surfaces, and may involve depositions on microporous structures and on temperature sensitive materials such as organic or biological molecules. Processing in supercritical carbon dioxide may provide a low temperature avenue for the deposition of uniform, high purity, thin films, with desirable interfacial properties and quality on patterned surfaces or microporous structures, impacting technological fields such nanoelectronics, molecular electronics, biocatalysis, NEMS and bioNEMS. Examples of thin films deposited with this technique include Al2O3 and Y2O3.
In the second part of my talk I will focus on some recent results we have obtained for ALD of HfO2 thin films from tetrakis ethylmethylamido hafnium (TEMAH) and H2O. We have examined the evolution of the film microstructure and interface during postdeposition anneals up to 900C using AFM, FTIR, XRD and XPS.