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Title: Atomic-scale thermocapillary flow in focused ion beam milling

Focused ion beams provide a means of nanometer-scale manufacturing and material processing, which is used for applications such as forming nanometer-scale pores in thin films for DNA sequencing. We investigate such a configuration with Ga{sup +} bombardment of a Si thin-film target using molecular dynamics simulation. For a range of ion intensities in a realistic configuration, a recirculating melt region develops, which is seen to flow with a symmetrical pattern, counter to how it would flow were it driven by the ion momentum flux. Such flow is potentially important for the shape and composition of the formed structures. Relevant stress scales and estimated physical properties of silicon under these extreme conditions support the importance thermocapillary effects. A flow model with Marangoni forcing, based upon the temperature gradient and geometry from the atomistic simulation, indeed reproduces the flow and thus could be used to anticipate such flows and their influence in applications.
Authors:
; ;  [1]
  1. Mechanical Science and Engineering and Aerospace Engineering, University of Illinois at Urbana–Champaign, 1206 West Green Street MC-244, Urbana, Illinois 61801 (United States)
Publication Date:
OSTI Identifier:
22403228
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Fluids (1994); Journal Volume: 27; Journal Issue: 5; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 74 ATOMIC AND MOLECULAR PHYSICS; CAPILLARY FLOW; COMPUTERIZED SIMULATION; DNA SEQUENCING; FLOW MODELS; GALLIUM IONS; GEOMETRY; ION BEAMS; MILLING; MOLECULAR DYNAMICS METHOD; PHYSICAL PROPERTIES; PROCESSING; SILICON; STRESSES; TEMPERATURE GRADIENTS; THIN FILMS