Uniting Lithographic Patterning and Topochemical Reaction for Processing of Functional Oxides for Electronic Applications

Drexel University, Philadelphia PA

Investigators

Abstract

This grant supports research into developing and understanding a new nanomanufacturing process to fabricate novel patterned materials, thereby generating fundamental innovations in advanced manufacturing and advancing the nation’s technological capabilities. Patterned materials are essential components in numerous societally-critical applications including electronics, communications, data storage, and sensing. However, current approaches to processing these structures result in patterns that are static and often limited in their functionality. This award supports fundamental research to provide the knowledge needed to realize new classes of patterned materials with properties that cannot be accessed through currently available processing approaches. This new manufacturing strategy combines industrially-relevant and scalable processes used to pattern materials with low-temperature chemical reactions to create oxide-based structures with tunable properties that can be reconfigured in response to external stimuli. The dynamic nature of these structures could serve as a platform for a new generation of adaptive devices. Therefore, the new manufacturing insights and approaches resulting from this project benefit the U.S. economy and society. The project provides research training to students on a variety of experimental skills sought by industry and engages local high school students in promoting engineering fields. Topochemical transformations are solid-state chemical reactions that alter composition but retain central features of the material structure. When carried out on lithographically-defined areas, these reactions enable the creation of oxide-based lateral patterns with controlled geometries, diverse chemistries, and new functionality not afforded by existing processing routes. However, the ability to harness the full technological potential of this manufacturing strategy rests on developing a fundamental scientific understanding of numerous aspects of the process. This research addresses these knowledge gaps to better understand the relevant mechanisms and kinetic limitations. The research team identifies the relationships between material composition, crystal structure and processing parameters by systematically varying the reactions on different patterned metal oxides. The team establishes the kinetic factors that set the ultimate limit on feature sizes in nanoscale patterns and enable the formation of non-binary structures and elucidate the stability and reconfigurability of the structures under applied electric fields and through sequential reaction steps. In doing so, the research enables manufacturing of lateral structures including functional oxide and oxyfluoride ABO3/ABO2F, e.g., SrFeO3/SrFeO2F patterns that facilitate applications such as reconfigurable or transient electronics, diffraction gratings, and sensors. 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.