Atomic Scale Processing for the Ångström Era

Abstract

The shrinking of semiconductor devices, commonly marked by nanometer nodes, is now moving into the Ångstrom era, where material elements will be only hundreds of atoms wide and a few atoms thick. To augment common lithographic patterning, manufacturers are turning to area-selective deposition, ASD, to directly form device elements using molecular recognition and surface chemical contrast with Ångstrom-scale precision. At the industrial scale, a single ASD process step can create billions of nanometer-sized features aligned with atomic-scale precision across a full 300 mm diameter silicon wafer. Area-selective silicon epitaxy is used routinely for transistor contacts, but extension to other materials is needed. Recently, we found that ASD could be achieved at <300°C by combining chemical etching with atomic layer deposition so that deposition and etching occur simultaneously in parallel. For a range of materials and process conditions, thermodynamic modeling confirms that deposition and etching are both energetically favorable. Akin to high temperature selective epitaxy, the resulting net deposition is inherently self-aligned with the pre-patterned starting surface because the etching reaction locally consumes the deposition reactant, thereby avoiding unwanted nuclei. Using simultaneous deposition and etching, we show area-selective deposition of tungsten on nanopatterned surfaces. Modeling and initial experimental results show that the concept extends to a range of other material systems, indicating that simultaneous deposition and etching provides opportunities for low temperature bottom-up self-aligned patterning for electronic and other nanoscale systems.

About the speaker

Gregory Parsons, Celanese Acetate Professor of Chemical and Biomolecular Engineering at North Carolina State University, is internationally recognized for his work in atomic-scale synthesis and processing of advanced electronic and thin film materials.  Since joining NC State in 1992, he has been the lead advisor for more than 50 PhDs, many of whom are now recognized as research leaders in academia, industry, and national laboratories. His research, published in ~300 peer-reviewed articles, impacts fields including high-performance transistor devices, solar energy, advanced personal-protective materials, and others.  He earned a BA in Physics from the State University of New York and a PhD in Physics at NC State University and did post-doctoral research at IBM TJ Watson Research Center.

In 2001, through his service in the American Vacuum Society, he co-founded the annual International AVS Atomic Layer Deposition Conference, which has become the leading venue for academic and industrial interaction in the field. He is the recipient of an NSF Career Award, a Semiconductor Research Corporation Invention Award, and NC State’s RJ Reynolds Award, and was elected Fellow of the American Vacuum Society in 2005. In 2015 he received the ALD Innovation Award, the highest recognition of accomplishment in the ALD community. In addition, his contribution to preparing PhD students to have impact in the semiconductor industry was recognized by his receipt of the 2025 SRC Aristotle Award. Parsons is also recognized as an accomplished classroom teacher, being named in 2009 to NC State’s Academy of Outstanding Teachers.  

Gregory N. Parsons
Department of Chemical and Biomolecular Engineering
North Carolina State University, Raleigh, NC, USA
e-mail: gnp [at] ncsu [dot] edu (gnp[at]ncsu[dot]edu)