Direct Digital Secondary Electron Signal Acquisition Probe for Scanning Electron Microscope.
Department of Energy
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Small Business Information
145 Graham Ave, A217 ASTeCC, Lexington, KY, 40506-0286
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AbstractScienceTomorrow in collaboration with Dr. David C Joy, at the University of Tennessee Research is proposed to fabricate direct digital Quantitative Secondary Electron Detectors (QSED) for scanning electron microscopes (SEMs). If successful, commercial versions of the QSED would transform the SEM/STEM into a quantitative, metrological tool with enhanced capabilities that, in turn, would broaden research horizons across many industries. In Phase I the detector was fabricated and tested for sensitivities, noise reduction, DC offset elimination, and metrological capabilities (linearity, accuracy, etc.). 10X10 solid state devices were made using standard lithography planner process. The devices were wired, bonded, and assembled on to the microscope. The separated charge carrier were allowed to accumulate across the electrodes. The Charge were measured and correlated with Secondary electron collection. The results are achieved meeting the proposed objectives in Phase I: 1) QSED produces no more than -34dB of detector noise across its entire operating range results in improved SNR with QSED as characterized the detective quantum efficiency (DQE) being equal to geometric efficiency. 2) a near zero DC-offset (dynamic range & gt; -35 dB) achieved for all operating conditions demonstrating improved dynamic range, and 3) Demonstrated that the QSED image contrast achieves a nearly within R2 of 0.992 linear relationship with SE collections. A near (.8% of reading) linear relationship between pixel signal and collection, will enable quantitative, nanoscale, dimensional measurement from SEM images. Together milestones #1, #2, and #3, if successful achievement, demonstrates an improved signal-to- noise ratio, a practically unlimited dynamic range, and quantitative imaging in the sub-5nm regimes which are not possible with ET detectors. Thus, this approach could lead to transforming SEMs into commercially viable, quantitative metrology tools, both for the OEM and retrofit markets. This work will produce a crucial advancement in electron microscopy with wide-ranging applications. In Phase II scale up the Solid State Device Array (SSDA) and integrate electron counter in the device. Also, characterize the device to validate the design and develop compatible interface software. Integrate device and software for critical dimension measurement in sub-nanometer scale. Key advantages anticipated from this work: 1. Low noise will improve SEM resolution in nano-scale critical for dimensional metrology. 2. Quantitative measurement will enhance process control, improve reliability prediction and design validation in semiconductors, photo-voltaic, bio-medical devices and catalysts. 3. Video and dynamic-imaging will advance nano-scale research in pharmaceutical and semiconductor. 4. Lower cost will make high-performing electron microscopes affordable to more researchers. 5. Compact size and ease of integration will enable to retrofit and upgrade existing SEM/STEMs. In private briefings on this concept, this QSED idea has generated enthusiastic interest among a number of SEM makers, service companies and existing SEM users who have also offered to support ST in this project. The proposed QSED advance sits squarely in the middle of ScienceTomorrows mission and, if successful, will further the companys business strategy by launching an advanced, high-margin product that will enable the company and its partners to create at least 17 net-new jobs by the end of 2018.
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