Iminopyrrolidine Ligand Design and Novel Group IV Precursors for Chemical Vapour and Atomic Layer Deposition

Yamile Wasslen
Abstract & Cover

Consistent downsizing of microelectronics due to Moore's law scaling of integrated circuits has pushed traditional design techniques to their micro-scale limitations. When approaching the nano-scale, the electrical properties of the widely used poly-silicon based metal-oxide-semiconductor field-effect transistor (MOSFET) change drastically and render the devices un-useable. For this reason, the development of new materials that maintain favourable electrical properties on a nano-scale, such as titanium, aluminum, and zirconium based metals, metal-nitrides and metal-oxides, have been of growing interest in research. Future circuit design will require an efficient means for controlled and uniform coating of ultra-thin films of next-generation microelectronic materials. Two interesting candidates for depositing thin films are atomic layer deposition (ALD) and chemical vapour deposition (CVD). The ability to control the uniformity of thin films using ALD and CVD depends on locating effective precursors for deposition. An effective precursor should be thermally stable, volatile, chemically reactive and self-limiting. Compounds with guanidinate and amidinate ligands make promising precursors due to their facile tunability, their volatility and their self-limiting properties. In this work amidinate and guanidinate precursors for ALD and CVD are developed and characterized. This work includes the synthesis of a novel iminopyrrolidine ligand and characterization to determine its potential as an ALD precursor ligand. The ligand showed thermal stability and a tunable melting point trend demonstrating potential as an effective ligand for ALD and CVD precursors. In addition, once the iminopyrrolidinate ligand was reacted with aluminum and titanium species, tunable melting points were observed for the resulting metal containing precursor species, offering potential flexibility in ALD process design. The synthesis and thermal chemistry of other novel heteroleptic titanium and zirconium species are also presented. The most promising precursors include the heteroleptic titanium +3 guanidinate and amidinate species for the deposition of TÌN/TÌO2 films. One of the guanidinate species was chosen for an exposure experiment on high surface area silica to study and determine the precursor chemistry with respect to nucleation between titanium and the substrate. The novel heteroleptic zirconium species presented in this work demonstrated two different bonding arrangements within the guanidinate family.

Source of Information
Thesis document
Carleton University
(Ottawa, Canada)
Other notes
First Barry Lab PhD
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