Articles you may be interested in Electron beam dot lithography for nanometer-scale tunnel junctions using a double-layered inorganic resistWe describe nanometer-scale feature definition in adsorbed hydrogen layers on Si͑001͒ surfaces by exposure to low energy electrons from a scanning tunneling microscope tip. Feature sizes range from Ͻ5 to Ͼ40 nm as a function of bias voltage ͑5-30 V͒ and exposure dose ͑1-10 4 C/cm͒. We show that the cross section for electron stimulated desorption of hydrogen has a threshold at 6 -8 eV and is nearly constant from 10 to 30 eV, so that above threshold the feature profiles are a direct reflection of the electron flux profile at the surface. Radial flux distributions are best fit by a simple exponential function, where the decay length is dependent primarily on the tip-sample separation. Low intensity tails at large radius are also observed for high bias emission. Comparison to field emission simulations shows that our tip has an ''effective radius'' of approximately 30 nm. Simulations demonstrate that tip geometry and tip-sample separation play the dominant role in defining the electron flux distribution, and that optimum beam diameter at the sample is obtained at small tip-sample separation ͑low bias͒ with sharp tips. We show that adsorbed hydrogen is a robust resist that can be used as a mask for selective area deposition of metals by chemical vapor deposition. Fe lines 10 nm wide are deposited by pyrolysis of Fe͑CO͒ 5 in areas where H has been desorbed, with minimal nucleation in the H-passivated areas.
Fabrication of complementary metal-oxide-semiconductor integrated nanomechanical devices by ion beam patterning J. Gas-assisted focused electron beam and ion beam processing and fabricationThis work demonstrates accurate focused ion beam sculpting of micron-scale curved shapes into initially planar solids. Sculpting is accomplished by varying the dose per pixel within individual boustrophedonic scans and accounting for the material-specific angle-dependent sputter yield and the ion beam spatial distribution. We refine this technique by demonstrating how a range of preferred dwell times leads to improved sculpting. An optimized dwell time range is delineated by two effects. Excessively large dwell times lead to enhanced deposition of ejected species, asymmetric milled features ͑when symmetric features are intended͒, and depths greater than intended values. These effects occur for dwell times such that the depth removed per pixel in a given scan is on the order of the width of the focused ion beam. On the other end of the dwell time range, inordinately low times lead to undesired ion milling outside targeted areas. Milling outside targeted regions, such as a circle or an ellipse, can occur because the ion beam is retraced to a rectilinear frame bounding the area. When dwell times are chosen to be on the order of the time to transit from the rectilinear frame to an outlined area edge, this leads to a significant dose over unintended areas, thereby producing a feature with irregular boundaries. Despite these two effects, a large range of acceptable dwell times ͑approximately three to four decades͒ can be established for milling most curved shapes. Hemispherical, parabolic, and sinusoidal features are demonstrated in Si͑100͒.
Nanometer-scale metal lines are fabricated onto Si(100) substrates by scanning tunneling microscope (STM) based lithography and subsequent chemical vapor deposition. An STM tip is first used to define areas for metal layer growth by electron stimulated desorption of adsorbed hydrogen. Exposure to Fe(CO)5 at 275 °C results in preferential deposition of Fe onto Si dangling bond sites (i.e., depassivated areas defined by the STM tip), while the monohydride resist remains intact in surrounding areas. Fe metal lines with widths ∼10 nm are constructed using this selective-area, autocatalytic growth technique.
This paper presents techniques for fabricating microscopic, curvilinear features in a variety of workpiece materials. Micro-grooving and micro.threading tools having cutting widths as small as 13 pm are made by focused ion beam sputtering and used for ultra-precision machining. Tool fabrication involves directing a 20 keV gallium beam at polished cylindrical punches made of cobalt M42 high-speed steel or C2 tungsten carbide to create a number of critical]y aligned facets. Sputtering produces rake facets of desired angle and cutting edges having radii of curvature equal to 0.4 pm. Clearance for minimizing frictional drag of a tool results from a particular ion bean-d target geometry that accounts for the sputter yield dependence on incidence angle. It is believed that geometrically specific cutting tools of this dimension have not been made previously. Numerically controlled, ultra-precision machining with micro-grooving tools results in a close match between tool width and feature size. Microtools are used to machine 13 pm wide, 4 pm deep, helical grooves in polymethyl methacrylate and 6061 Al cylindrical workplaces. Microgrooving tools are also used to fabricate sinusoidal cross-section features in planar metal samples.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.