Collaborative Research: US-Ireland R&D Partnership: Processing-Driven Nucleation Mediated Control for Manufacturing of Phase-Pure Ferroelectric Hafnia

James Madison University, Harrisonburg VA

Investigators

Abstract

This award supports research that will develop new knowledge related to the manufacturing of electronic materials that will not form naturally, but that exhibit useful properties. The material studied in this effort is hafnium oxide, which can have a specific arrangement of atoms that results in a spontaneous electric charge separation that can be changed with application of a sufficient voltage. This functionality is useful for future generations of low power computing and computer memory. This particular hafnium oxide structure is challenging to prepare and often contains regions with other atomic arrangements that do not exhibit the useful spontaneous charge separation property. This award will support fundamental research to provide the knowledge needed to directly and completely form the hafnium oxide structure of interest. This new process will overcome the challenges of structural purity that have hindered mass production of hafnium oxide-based computer memory devices and enable development of new computing elements that consume less power. Low power devices are needed to reduce the overall energy consumption related to computing. This will directly impact the US economy, national security, and society by enabling the development and manufacture of new microelectronic technologies that lead to new functionality and less energy consumption. This project involves researchers in the United States, the Republic of Ireland, and Northern Ireland, representing several disciplines, including materials science, electron and scanning probe microscopies, and physics. The multi-disciplinary and multi-national team will develop educational outreach materials and present them to students in economically disadvantaged areas to stimulate interest in science, technology, engineering, and mathematics and to show how science and engineering are global endeavors. The goal of this fundamental research project is to develop a scalable manufacturing method to prepare phase-pure ferroelectric hafnium oxide and hafnium zirconium oxide by atomic layer deposition. The project will utilize plasma-enhanced atomic layer deposition to prepare amorphous deposits of hafnium oxide and hafnium zirconium oxide. The impact of processing parameters on the amorphous structure and resulting phases will be characterized using X-ray Diffraction, Extended X-ray Absorption Fine Structure, Transmission Electron Microscopy, Electron Energy Loss Spectroscopy, Scanning Probe Microscopy, and electrical property measurements. The project will determine how amorphous structure bond length and atomic coordination impact the nucleating phase. By isolating the impact of atomic layer deposition process parameters on the amorphous structure and then determining how that leads to crystalline phase formation, a deterministic means to prepare phase-pure materials will result. The nano- and device-scale ferroelectric behavior will be quantified using advanced microscopies and the impact of phase impurities on material performance will be measured. The end result will be new knowledge of the impact of amorphous structure on crystallization of hafnium oxide-based materials and the impact of phase impurity on ferroelectric performance. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.