'Old Chemistries' for new applications: Perspectives for development of precursors for MOCVD and ALD applications

The concept of the transformation of molecules to materials has been well established in the field of chemical vapor deposition (CVD) and atomic layer deposition (ALD). However, materials scientists are always on the lookout for new materials with enhanced functionalities for eventual application in devices. New materials have become an integral part of modern day technology especially in the field of microelectronics and optoelectronics. The importance of CVD and ALD processes for high throughput and coating on complex device geometries is well recognized for these applications. Since the underlying precursor chemistry is one of the main parameters that dictate these processes, there is still scope for further exploratory research, in terms of precursor design and development that suits the demands of advanced technologies. A wide range of precursors can be used to realize specific class of materials but the trend recently has been driven by the reduced thermal budget needed especially for components employed in microelectronics and optoelectronics. The chronological developments in precursors for CVD/ALD point out that, designer precursors are set to play a major role in the field of materials engineering. The desirable growth conditions could be achieved with a proper selection of compounds which may stem from the available class of metal complexes or even engineered compounds. In this review article, the concept of utilizing 'old chemistries' for new CVD and ALD applications will be highlighted focussing on some representative functional materials namely group IV and rare earth oxides. Some of the very recent results on precursor development carried out in the Inorganic Materials Chemistry research group at Bochum, Germany are summarized.