Gottlieb Oehrlein - US grants

In this GOALI project, researchers at University of Maryland, UC Berkeley, Lam Research Corporation, Shipley Corporation, and ITC-Irst, Italy collaborate to address chemical and morphological stability of nanoscale features produced in organic materials exposed to plasma environments used for pattern transfer. The overall goal is to establish an atomistic understanding of the interactions of etching plasmas with organic materials used for patterning in nanoscale fabrication/manufacturing, and elucidating the physical/chemical prerequisites to prevent the introduction of feature surface and line edge roughness. The approach includes: 1)experiments with a broad set of relevant organic materials, supplied by Shipley, both model compounds and fully formulated resist systems to cover materials of interest for various lithographic approaches; 2)plasma processing of organic materials sets in a well-controlled, well-characterized and modeled reactor at U. MD; 3)complementary ionic and radical beam exposures at UC Berkeley; 4)comprehensive materials and surface and selected structure analysis at ITC IRST; 5)molecular dynamics simulations of the plasma surface interactions with model compounds at UC Berkeley; and 6)model formulation/verification, including runs in industrial plasma processing reactors at Lam Research.
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The project addresses basic research issues in a topical area of electronic materials with high technological relevance. The interaction of reactive and/or energetic fluxes of particles with macromolecules defining geometric features of devices on a substrate is ubiquitous in nanofabrication, and in integrated circuits and related industries. This project seeks to develop a framework of macromolecular features required for optimized plasma-durability of organic mask images. Fundamental understanding gained is expected to guide the development of next-generation pattern transfer technology. The collaborative aspect of the project provides special opportunities for education. Students will be trained in a technologically relevant area, with a strong emphasis on fundamental, mechanistic aspects of scientific/technical issues. Through the industrial collaboration with Lam Research Corporation and Shipley Corporation students will acquire a strong background in plasma technology, and advanced organic materials and resist system design. The collaboration with ITC-Irst, Italy provides an International component to the project, and the ability to leverage advanced characterization facilities for material and surface analysis. The work at the two universities is complementary, encompassing advanced facilities in state-of-the-art processing, diagnostics, experimental and computer simulation of plasma-surface interactions. The students and researchers involved in this project will experience a teamwork-oriented research environment from both academic and industrial perspectives, where complementarity of competencies fosters a spirit of leveraging interdependency for empowered thinking.
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National Science Foundation

ABSTRACT

PI name: Oehrlein, Gottlieb S.
Institution: University of Maryland
Proposal Number: 0506988

NIRT: Nanotechnological Manufacturing: Nanostructured Polymers Designed for Plasma/Energetic Beam Templating of Materials

This proposal was received in response to Nanoscale Science and Engineering initiative, NSF 04-043, category NIRT. The objective of the proposed research is to establish an atomistic understanding of the interactions of nanostructured polymers with the plasmas and energetic beams used during pattern transfer, and to identify the molecular design parameters and plasma processing parameters required to control patterning at nanoscale dimensions. A strong motivation for this proposal is the recognition that molecular design of organic materials for emerging nanolithographic approaches based on soft lithography and self-assembly is not constrained by the requirement for transparency at short optical wavelengths. This profound change provides the opportunity to design organic masking materials for greatly enhanced stability in plasma environments. The approach is to bring together an interdisciplinary team of academic and industrial researchers, who, through their combined expertise and research capabilities are positioned to significantly advance the cutting edge of controlled nanoscale patterning of materials. This includes design and synthesis of organic imaging materials; nanostructuring the materials using soft lithography and self-assembly, exposing the organic molecules to highly controlled and well-characterized plasma environments and energetic beams, and characterizing and simulating the changes of the chemistry, structure and topography induced by these interactions.

Successful completion of the project tasks will enable design of new nanoscale imaging materials with enhanced chemical and structural stability in plasma/energetic beam environments and will lead to the development of advanced plasma equipment\processes. These are prerequisites to controlled precision patterning of materials at the nanoscale, which is one of the critical foundations of future nanotechnological manufacturing. The interdisciplinary character and inter-dependence of the various research tasks along with the university-industry collaboration of this NIRT project provide unique educational opportunities for the students, post-doctoral fellows, faculty and industrial researchers involved, and will be used to enhance class-room based teaching.

This award is made in response to a proposal submitted to and reviewed under the NSF/DOE Partnership in Basic Plasma Science and Engineering joint solicitation NSF 09-596. The award provides funds to support undergraduate participation in the overall research effort, which is being funded separately by the DOE under contract to University of Maryland (Grant DE-FG02-10ER55077).

The proposed research objective is to establish an atomistic understanding of interactions of low temperature plasma (LTP) with prototypical biological assays to achieve biological deactivation. While LTP treatment of biological cells and living tissue at both low and atmospheric pressure has been demonstrated as a versatile method to directly alter biological function of living matter in desirable ways, important scientific knowledge gaps exist and preclude rational development of these procedures. These gaps include understanding of ion-, energetic photon or reactive neutral initiated processes, changes in surface/near-surface properties of the treated biological entities and correlation with altered biological function, and lack of theoretical models capable to assist with interpretation of experimental observations and formulation of a consistent framework. Addressing these knowledge gaps requires an interdisciplinary team of investigators. The combined expertise available to this project includes biological assay methodologies, plasma-surface treatments and in-situ surface characterization, beam-surface interactions and molecular dynamics simulations of plasma/biological materials interactions, and interactions between lipid A/LPS and LBP at the atomic scale simulations using all-atom molecular mechanical force fields molecular dynamics simulations of proteins. The current team is thus positioned to significantly advance the scientific understanding of LTP treatment of biological matter for biological deactivation.

Successful completion of the project will provide the scientific foundation for LTP-based disinfection of medical instrumentation, packaging for food and medicines, other surfaces, and decontamination of biological warfare agents. The principles under study in this project are relevant to all applications of LTP to biological systems, cells and tissue, including the growing field of plasma medicine. The interdisciplinary character of this research provides unique educational opportunities for the students and faculty

The NSF support of undergraduate participation adds a broader educational impact through the early-year training of students by introducing them to scientific research as a possible career path.

1134273
Oehrlein

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.

Researchers from University of Maryland, College Park, and University of California, Berkeley, plan to investigate atmospheric pressure plasma (APP) sources for modification of selected model biomolecules and to establish a scientific framework for development of atmospheric pressure plasma applications in biotechnology and plasma medicine (or biomedicine). Non-equilibrium atmospheric pressure plasmas are powerful sources for reactive chemical species that can have profound biological effects, but the sources are complex, poorly understood, and are difficult to design and control. Our knowledge of the nature of the plasma-biomaterial interaction using such atmospheric pressure plasma sources is especially inadequate. This work combines plasma source characterization/simulations, plasma-surface (tissue) treatments/in-situ surface characterization with biological assay methodologies, and various characterization approaches, including magnetic resonance characterization of solid state and solution macromolecules. The broader impacts of this project go beyond the establishment of baseline methodologies that can be used to characterize and control interactions of APP sources with biological targets. As an enabling technology, approaches and concepts unveiled in this work can be broadly applied in diverse applications where the biological environment must be well-controlled, e.g. disinfection of packaging for food and medicines, modification of biological systems, cells and tissue, including the field of plasma medicine. The principles under study in this project are also relevant to all applications of APP for surface functionalization of organic materials such as polymers.

The project's first objective is to obtain a fundamental understanding of how fluxes of reactive species produced in two representative APP devices depend on source type, operating parameters and environmental conditions using relevant chemistries. The second objective is to expose selected biomolecules to well controlled species from these APP sources to induce atomistic modifications of the biomolecules. The changes in biomolecule properties (chemical, morphological etc) along with alterations in biological function will be characterized using an array of complementary methods. Furthermore, modifications in biological function will be correlated with the results of the comprehensive materials/surface characterizations to provide underlying chemical and biological mechanisms. The third objective is to obtain a scientific understanding of how water modulates APP-biomolecule interactions to affect its biological function. This includes establishment of differences in APP species fluxes, chemical/morphological changes in biomolecules, and their biological responses to bio-assays when water is present either in the gas stream passing through the APP source, the environment (humidity) or as a liquid on the surface of the biomolecule. The fourth objective is experimental validation of current computational efforts on simulating atomic-scale modifications of specific model biomolecules by reactive species produced by APP sources. This will be based on investigating biomolecules for which atomic-scale simulations of the interaction of reactive plasma species with these biomolecules have either been published, or are currently ongoing.

The ability to create devices with finer features over larger areas is crucial to technological innovation in both mature and emerging industries. In the semiconductor industry, progress in increasing circuit density has been maintained by using light of ever shorter wavelengths to produce circuit patterns, but this method is expensive and further improvements are nearing their limit. This Scalable NanoManufacturing (SNM) project will use three beams of visible light of different wavelengths to produce nanoscale features with the improved resolution required to produce high density integrated circuits. Because visible light is inexpensive to produce, propagate and manipulate, the method promises to lower the cost of cutting-edge nanomanufacturing by a factor of 10 or more. The project team will collaborate with major industrial developers and end-users to transfer the technology to practice, providing a major boost to American competitiveness in scalable nanomanufacturing. The ever more compact and powerful devices that this technology will produce have the potential to impact virtually every imaginable aspect of technology and every member of our society.

The project team has researched and proven 2-color approaches to photolithography that have made possible the creation of high-resolution features using visible light. The basis of these techniques is that one color of light is used to initiate chemistry and a second color is used to inhibit it. However, these methods are not yet capable of producing the resolution needed to satisfy the requirements of the next node of the Semiconductor Roadmap. The stumbling block for 2-color approaches has been that initiation of chemistry competes with deactivation. The proposed 3-color approaches circumvent this problem. One color of light pre-activates chemistry, a second color of light deactivates the molecules, and a third color of light transforms pre-activated molecules into activated molecules that then undergo chemistry. This approach provides a viable path to attaining sub-20-nm resolution for scalable nanomanufacturing in 2 and 3 dimensions. The project team combines expertise in photolithography, photochemistry, spectroscopy and pattern transfer to realize this vision. The team will work closely with industrial collaborators who have expertise in commercial photoresists, photolithographic tool components and photolithographic simulation methods to ensure that the research methods and materials used are compatible with the needs and processes of the semiconductor industry and other consumer product industries.

1703211 / 1703439
PI: Oehrlein, Gottlieb S. / Bruggeman, Peter J.

The collaborative research project aims at using a well-characterized atmospheric-pressure plasma source to enable well-controlled interactions of the plasma with earth-abundant catalysts. The activations of catalysts using plasmas holds great promise for increasing the efficiency of catalytic systems with potential applications in a broad spectrum industries, including chemical and materials synthesis, environmental remediation, and energy generation. The overriding goal of the project is to investigate the underlying mechanisms that are responsible for the synergistic effects of plasma with catalysts. The plan is to correlate the magnitude of the plasma catalytic synergistic effect(s) with incident reactive species fluxes, along with changes in catalyst surface properties, and surface electronic structure. A careful systematic comparison of the different catalysts may elucidate the microscopic origins of the synergistic effect and explore potential plasma activation of thermally inactive catalysts. The project may lead to better understanding of the requirements for plasma conditions and catalysts to fully exploit the synergistic potential of plasma-catalyst systems.

A mechanistic study is proposed that is aimed at providing atomistic insights to unravel the key mechanisms responsible for the synergistic effect(s) during plasma-catalyst interactions. Iron, nickel, cobalt, and copper supported catalysts (on alumina and silica supports) will be employed in this study. These catalysts vary strongly in thermal catalytic activities due to different electronic structure and surface-catalytic mechanisms. The investigation will be focused on studying atomistic surface modifications of the catalysts for the oxygen/methane model system as the plasma-surface interaction conditions are changed. This will include the impact of these surface changes on the products formed and their formation rates. Gas phase characterization will be achieved by molecular beam mass spectrometry and two-photon laser induced fluorescence. Surface characterization will include ellipsometry, ultra-violet and x-ray induced photoemission spectroscopy coupled with thermal desorption, and Fourier transform infrared spectroscopy. The proposed approach has the potential to make transformative changes to the current state-of-the-art by enabling a mechanistically informed design of catalysts ideally suited for plasma-catalyst synergies. In addition to training graduate and undergraduate students, the investigators plan to develop course material on plasma-catalysis and an interactive lecture for middle school students.