arXiv subjects

Ronald G. Dixson

Publications and source records attributed to Ronald G. Dixson.

3 recordsLinked to original sources

arXiv2026

Titanic overconfidence -- dark uncertainty can sink hybrid metrology for semiconductor manufacturing

Hybrid metrology for semiconductor manufacturing is on a collision course with dark uncertainty. An IEEE technology roadmap for this venture has targeted a linewidth uncertainty of +/- 0.17 nm at 95 % coverage and advised the hybridization of results from different measurement methods to hit this target. Related studies have applied statistical models that require consistent results to compel a lower uncertainty, whereas inconsistent results are prevalent. We illuminate this lurking issue, studying how standard methods of uncertainty evaluation fail to account for the causes and effects of dark uncertainty. We revisit a comparison of imaging and scattering methods to measure linewidths of approximately 13 nm, applying contrasting statistical models to highlight the potential effect of dark uncertainty on hybrid metrology. A random effects model allows the combination of inconsistent results, accounting for dark uncertainty and estimating a total uncertainty of +/- 0.8 nm at 95 % coverage. In contrast, a common mean model requires consistent results for combination, ignoring dark uncertainty and underestimating the total uncertainty by as much as a factor of five. To avoid such titanic overconfidence, which can sink a venture, we outline good practices to reduce dark uncertainty and guide the combination of indeterminately consistent results.

physics.data-an↗

arXiv2023

Traceable localization enables accurate integration of quantum emitters and photonic structures with high yield

Traceability to the International System of Units (SI) is fundamental to measurement accuracy and reliability. In this study, we demonstrate subnanometer traceability of localization microscopy, establishing a metrological foundation for the maturation and application of super-resolution methods. To do so, we create a master standard by measuring the positions of submicrometer apertures in an array by traceable atomic-force microscopy. We perform correlative measurements of this master standard by optical microscopy, calibrating scale factor and correcting aberration effects. We introduce the concept of a localization uncertainty field due to optical localization errors and scale factor uncertainty, with regions of position traceability to within a 68 % coverage interval of +/- 1 nm. These results enable localization metrology with high throughput, which we apply to measure working standards that we fabricate by electron-beam lithography, validating the accuracy of mean pitch and closing the loop for disseminating and integrating reference arrays. We then apply our novel methods to calibrate an optical microscope with a sample cryostat, accounting for thermal contraction by use of a submicrometer pillar array in silicon as a reference material and elucidating complex distortion. This new calibration enables the accurate integration of quantum emitters and photonic structures with high yield, as we demonstrate theoretically through simulations of the dependence of the Purcell factor of radiative enhancement on registration errors across a wide field. Our study illuminates the challenges and opportunities of achieving traceable localization for comparison of position data across lithography and microscopy systems, from ambient to cryogenic temperatures.

physics.optics↗

arXiv2022

Sub-picoliter Traceability of Microdroplet Gravimetry and Microscopy

Gravimetry typically lacks the resolution to measure single microdroplets, whereas microscopy is often inaccurate beyond the resolution limit. To address these issues, we advance and integrate these complementary methods, introducing simultaneous measurements of the same microdroplets, comprehensive calibrations that are independently traceable to the International System of Units (SI), and Monte-Carlo evaluations of volumetric uncertainty. We achieve sub-picoliter agreement of measurements of microdroplets in flight with volumes of approximately 70 pL, with ensemble gravimetry and optical microscopy both yielding 95% coverage intervals of +/- 0.6 pL, or relative uncertainties of +/- 0.9%, and root-mean-square deviations of mean values between the two methods of 0.2 pL or 0.3%. These uncertainties match previous gravimetry results and improve upon previous microscopy results by an order of magnitude. Gravimetry precision depends on the continuity of droplet formation, whereas microscopy accuracy requires that optical diffraction from an edge reference matches that from a microdroplet. Applying our microscopy method, we jet and image water microdroplets suspending fluorescent nanoplastics, count nanoplastic particles after deposition and evaporation, and transfer volumetric traceability to number concentration. We expect that our methods will impact diverse fields involving dimensional metrology and volumetric analysis of microdroplets, including inkjet microfabrication, disease transmission, and industrial sprays.

physics.app-ph↗