A de novo, genetically engineered 687 residue polypeptide expressed in E. coli has been found to form highly rectilinear, beta-sheet containing fibrillar structures. Tapping-mode atomic force microscopy, deep-UV Raman spectroscopy, and transmission electron microscopy definitively established the tendency of the fibrils to predominantly display an apparently planar bilayer or ribbon assemblage. The ordered self-assembly of designed, extremely repetitive, high molecular weight peptides is a harbinger of the utility of similar materials in nanoscience and engineering applications.

Sputter deposition has been investigated as a tool for manufacturing proton-exchange membrane fuel cell ͑PEMFC͒ electrodes with improved performance and catalyst utilization vs. ink-based electrodes. Sputter-depositing a single layer of Pt on the gas diffusion layer provided better performance ͑0.28 A/cm 2 at 0.6 V͒ than sputtering the Pt directly onto a Nafion membrane ͑0.065 A/cm 2 at 0.6 V͒ and equaled the performance of the baseline for an equivalent Pt loading. Sputter-depositing alternating layers of Pt and Nafion-carbon ink ͑NCI͒ onto the membrane did not increase the performance over the baseline as measured in amperes per centimeter squared due to the excessive thickness of the NCI ͑the NCI accounted for 99.9% of the electrode thickness͒. However, three and six layer Pt/NCI membrane electrode assemblies ͑MEAs͒ resulted in Pt activities double that of the 905 A/g at 0.6 V achieved by the ink-based baseline. Decreasing the thickness of each NCI layer increased the performance of the six-layered Pt/NCI MEA from 0.132 to 0.170 A/cm 2 at 0.6 V, providing an activity of 2650 A/g at 0.6 V. It is likely that by further decreasing the ratio of NCI to Pt in these electrodes, Pt activity, and PEMFC electrode performance can be increased.

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Placing a layer of Ru atop a Pt anode increases the carbon monoxide tolerance of proton-exchange membrane fuel cells when oxygen is added to the fuel stream. Sputter-deposited Ru filter anodes composed of a single Ru layer and three Ru layers separated by Nafion-carbon ink, respectively, were compared to Pt, Pt:Ru alloy, and an ink-based Ru filter anodes. The amount of Pt in each anode was 0.15 normalmg/cm2 and the amount of Ru in each Ru-containing anode was 0.080 normalmg/cm2. For an anode feed consisting of hydrogen, 200 ppm CO, and 2% O2 (in the form of an air bleed), all Ru filter anodes outperformed the Pt:Ru alloy. The performance of the normalPt+normalsingle­normallayer sputtered Ru filter was double that of the Pt:Ru alloy (0.205 vs. 0.103A/cm2 at 0.6 V). The performance was also significantly greater than that of the ink-based Ru filter false(0.149A/cm2 at 0.6 V). Within the filter region of the anode, it is likely that the decreased hydrogen kinetics of the Ru (compared to Pt) allow for more of the OHnormalads formed from oxygen in the fuel stream to oxidize adsorbed CO to CO2. © 2002 The Electrochemical Society. All rights reserved.

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With the continuous shrinkage of feature dimensions on IC in the semiconductor industry, the measurement uncertainty is becoming one of the major components that have to be controlled in order to guarantee sufficient production yield. Already at the R&D level, we have to cope up with the accurate measurements of sub-40nm dense trenches and contact holes coming from 193 immersion lithography or E-Beam lithography. By using top-down CD-SEM it is currently impossible to extract profile information. Moreover, electron proximity effect leads to non-negligible CD bias in the final measurements. To enable measurement of challenging dimensions with better measurement and reduced measurement uncertainty we have explored and fine tuned an alternative 3D-AFM mode (so-called DT mode) for CD measurements purpose. Theoretically, this mode is supposed to be dedicated only for height measurement but for certain applications it could be extended to reach the nanometer scale accuracy of CD-measurements employing certain optimized scan parameters.In this paper, we will present and discuss results obtained related to the use of this particular mode for CD measurement purpose versus conventional 3D-AFM CD Mode that shows important limitations for aggressive trenches dimensions measurements. We will also present some results related to the use of advanced 3D-AFM tips (typically of 28nm diameter) that have been used with the enhanced DT mode parameters. Example of applications will be shown with typical sub-45nm trenches measurements dedicated to advanced lithography process development that will demonstrate that we have succeed to push ahead the limit of the 3D-AFM technology in measuring the tight dimensions that would allow to continue its use for current and upcoming technology nodes. Finally, we introduce the concept of hybrid metrology in order to smartly use the benefit of reference metrology (i.e 3D-AFM) through the optimization of CD-SEM algorithm that could be used for example for OPC model optimization.

Integrated circuit (IC) technology is changing in multiple ways: 193i to extreme ultraviolet exposure, planar to nonplanar device architecture, from single exposure lithography to multiple exposure and directed selfassembly (DSA) patterning, and so on. Critical dimension (CD) control requirement is becoming stringent and more exhaustive: CD and process windows are shrinking, three-sigma CD control of <2 nm is required in complex geometries, and a metrology uncertainty of <0.2 nm is required to achieve the target CD control for advanced IC nodes (e.g., 14, 10, and 7 nm nodes). There are fundamental capability and accuracy limits in all the metrology techniques that are detrimental to the success of advanced IC nodes. Reference or physical CD metrology is provided by atomic force microscopy (CD-AFM) and TEM while workhorse metrology is provided by CD-SEM, scatterometry, and model-based infrared reflectrometry (MBIR). Precision alone is not sufficient for moving forward. No single technique is sufficient to ensure the required accuracy of patterning. The accuracy of CD-AFM is ∼1 nm and the precision in TEM is poor due to limited statistics. CD scanning electron microscopy (CD-SEM), scatterometry, and MBIR need to be calibrated by reference measurements for ensuring the accuracy of patterned CDs and patterning models. There is a dire need for a measurement with <0.5 nm accuracy and the industry currently does not have that capability with inline measurements. Being aware of the capability gaps for various metrology techniques, we have employed data processing techniques and predictive data analytics, along with patterning simulation and metrology models and data integration techniques to selected applications demonstrating the potential solution and practicality of such an approach to enhance CD metrology accuracy. Data from multiple metrology techniques have been analyzed in multiple ways to extract information with associated uncertainties and integrated to extract the useful and more accurate CD and profile information of the structures. This paper presents the optimization of scatterometry and MBIR model calibration and the feasibility to extrapolate not only in design and process space but also from one process step to a previous process step. A well-calibrated scatterometry model or patterning simulation model can be used to accurately extrapolate and interpolate in the design and process space for lithography patterning where AFM is not capable of accurately measuring sub-40 nm trenches. The uncertainty associated with extrapolation can be large and needs to be minimized. We have made use of measurements from CD-SEM and CD-AFM, along with the patterning and scatterometry simulation models to estimate the uncertainty associated with extrapolation and the methods to reduce it. For the first time, we have reported the application of machine learning (artificial neural networks) to the resist shrinkage systematic phenomenon to accurately predict the preshrink CD based on supervised learning using the CD-AFM data. ...