Engineering of complex electrode stacks for functional complex oxide active layers

The push towards higher functionality and lower power consumption in semiconductor devices is driving materials discovery for advanced technology nodes. Complex oxides offer a wide variety of functionalities such as high-k dielectrics, ferroelectrics, magnetics, multiferroics, semiconductors, and more, with highly tunable properties. This level of performance and tunability is due to the complex stoichiometries that are easily modified to target specific properties. However, control of the growth of these materials to yield devices with low variability is challenging, particularly on scales required for production. Furthermore, materials properties are sensitive to crystal and microstructure, interfaces and interfacial strain, oxygen content, and defect chemistries. One of the more promising short-term applications of complex oxides is for back end of line (BEOL) capacitors utilising either ferroelectrics or ultra-high-k dielectrics. These require growth under highly oxidising conditions that poses risk to the underlying Si-based structures, and so, electrode stacks must protect the underlying layers. Often, the contribution of these layers to device properties is overlooked in a “one-size-fits-all” approach. Yet, the oxygen barrier properties, interface effects, and work function engineering are all considerations with a complex interplay that can dramatically effect device performance.

This project will focus on understanding of this complex interplay of properties in order to engineer stack performance for optimal complex oxide capacitor performance. Materials exploration, growth and interface engineering, advanced characterisation will be conducted using imec’s state-of-the-art Materials and Interfaces lab allowing for agile research approaches. Thin films will be deposited by PVD sputtering or pulsed laser deposition (PLD) and characterized through a variety of structural and electrical measurement techniques. Process parameters will be explored to understand the effects of growth kinetics, and to work towards engineering the electrode materials for maximised performances. The insights gained here will further the materials science to enable advanced technology nodes using complex oxides.