The PIs from University at Maryland (College Park) and IBM Research plan to study surface interaction mechanisms that will enable achievement of atomic precision in etching different materials when transferring lithographically defined templates during nanoscale structure fabrication in the semiconductor and related industries.
The use of ultra-thin gate dielectrics, ultra thin channels, and sub-20 nm film thicknesses in field effect transistors and other devices requires atomic scale etching control and selectivity. As critical dimensions approach the 10 nm scale, the need for an Atomic Layer Etching (ALE) method becomes essential. The objective of the proposed research is to establish what atomistic surface modifications produced in several model materials using plasma etching related equipment will enable directional and controlled removal of one atomic layer at a time from those surfaces. The researchers will employ controlled sequential reactions of surface passivation followed by directional low energy ion attack for "volatile product" removal to establish for what conditions self-limiting behavior with regard to both the reactive precursors and/or energetic ions/species that are used to remove the products can be established for prototypical materials/etching systems and how such a sequence can enable ALE. The approach includes replacing complex plasma-surface interaction steps by a sequence of individual, self-limiting surface reactions, quantitative, temporally resolved real-time characterization of surface modifications/atomistic thickness changes during processing, development of surface modification/etching models based on complementary vacuum beam studies performed in an ultra-high vacuum system, comparisons with theoretical precursor adsorption/ion-surface interaction models, and industrial studies of the above process parameter space using a variety of plasma reactors and aggressively-scaled semiconductor device structures, along with analytical and electrical characterizations of the impact on the semiconductor device fabrication space.
Intellectual Merit: The intellectual merit of this work derives from the fact that for anisotropic ALE, "etch product" removal must take place in a directional fashion, which is fundamentally different from widely used atomic layer deposition methods, where isotropic reaction(s) provide(s) a conformal coating. Elucidating the science underlying ALE presents novel incident particle flux/surface chemistry challenges and energetic species/surface interaction problems that are unique and offer opportunity for primary contributions.
Broader Impacts: Successful completion of the project tasks will enable controlled precision patterning of materials at the nanoscale, which will impact future efforts to design manufacturing processes required in diverse areas, including semiconductors, flexible carbon-based electronics, healthcare engineering and others. The academic/industrial collaboration provides unique educational opportunities for the students, faculty and researchers involved.