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Title: Computing light masks in neutral atom lithography

Abstract

In neutral atom lithography, a collimated beam of atoms is sent through a region of standing light waves created by interfering laser beams. The intensity distribution of the light field modulates the density distribution of the atoms transversal to the beam direction. The atomic beam materializes on a substrate, and the atoms are deposited in a pattern which mimics the intensity distribution of the light. It is thus possible to create nanostructures by a suitable adjustment of the light field. While the computation of the pattern of atoms generated by any given setup of laser beams with known amplitudes and phases is straightforward, the inverse problem of deducting the appropriate amplitude and phase of each single beam to create a prescribed pattern has to our knowledge not yet been addressed. We propose a numerical method to derive these values for a fixed setup of laser beams. We consider first the general case of unrelated beam directions and then specialize to setups which induce periodic patterns. The solution of the inverse problem is a two-step process: we use Fourier techniques to compute a set of characteristic amplitude values which enter the right-hand side of a nonlinear system of equations. This systemmore » is then solved iteratively by a coordinate descent method.« less

Authors:
 [1];  [2];  [3]
  1. Institute for Computational Engineering and Sciences, University of Texas at Austin, 1 University Station, C0200, Austin, TX 78712 (United States). E-mail: carsten@ices.utexas.edu
  2. Institut fuer Numerische Simulation, Universitaet Bonn, Wegelerstrasse 6, 53115 Bonn (Germany). E-mail: braun@ins.uni-bonn.de
  3. Institute for Computational Engineering and Sciences, University of Texas at Austin, 1 University Station, C0200, Austin, TX 78712 (United States). E-mail: kunoth@ins.uni-bonn.de
Publication Date:
OSTI Identifier:
20840370
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Computational Physics; Journal Volume: 220; Journal Issue: 1; Other Information: DOI: 10.1016/j.jcp.2006.07.012; PII: S0021-9991(06)00341-X; Copyright (c) 2006 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; AMPLITUDES; ATOMIC BEAMS; ATOMS; DENSITY; EQUATIONS; FOURIER TRANSFORMATION; LASERS; MATHEMATICAL SOLUTIONS; NANOSTRUCTURES; NONLINEAR PROBLEMS; PERIODICITY; SUBSTRATES; VISIBLE RADIATION

Citation Formats

Burstedde, Carsten, Braun, Juergen, and Kunoth, Angela. Computing light masks in neutral atom lithography. United States: N. p., 2006. Web. doi:10.1016/j.jcp.2006.07.012.
Burstedde, Carsten, Braun, Juergen, & Kunoth, Angela. Computing light masks in neutral atom lithography. United States. doi:10.1016/j.jcp.2006.07.012.
Burstedde, Carsten, Braun, Juergen, and Kunoth, Angela. Wed . "Computing light masks in neutral atom lithography". United States. doi:10.1016/j.jcp.2006.07.012.
@article{osti_20840370,
title = {Computing light masks in neutral atom lithography},
author = {Burstedde, Carsten and Braun, Juergen and Kunoth, Angela},
abstractNote = {In neutral atom lithography, a collimated beam of atoms is sent through a region of standing light waves created by interfering laser beams. The intensity distribution of the light field modulates the density distribution of the atoms transversal to the beam direction. The atomic beam materializes on a substrate, and the atoms are deposited in a pattern which mimics the intensity distribution of the light. It is thus possible to create nanostructures by a suitable adjustment of the light field. While the computation of the pattern of atoms generated by any given setup of laser beams with known amplitudes and phases is straightforward, the inverse problem of deducting the appropriate amplitude and phase of each single beam to create a prescribed pattern has to our knowledge not yet been addressed. We propose a numerical method to derive these values for a fixed setup of laser beams. We consider first the general case of unrelated beam directions and then specialize to setups which induce periodic patterns. The solution of the inverse problem is a two-step process: we use Fourier techniques to compute a set of characteristic amplitude values which enter the right-hand side of a nonlinear system of equations. This system is then solved iteratively by a coordinate descent method.},
doi = {10.1016/j.jcp.2006.07.012},
journal = {Journal of Computational Physics},
number = 1,
volume = 220,
place = {United States},
year = {Wed Dec 20 00:00:00 EST 2006},
month = {Wed Dec 20 00:00:00 EST 2006}
}
  • An analysis is presented of a method to protect the reticle (mask) in an extreme ultraviolet (EUV) mask inspection tool using a showerhead plenum to provide a continuous flow of clean gas over the surface of a reticle. The reticle is suspended in an inverted fashion (face down) within a stage/holder that moves back and forth over the showerhead plenum as the reticle is inspected. It is essential that no particles of 10-nm diameter or larger be deposited on the reticle during inspection. Particles can originate from multiple sources in the system, and mask protection from each source is explicitlymore » analyzed. The showerhead plate has an internal plenum with a solid conical wall isolating the aperture. The upper and lower surfaces of the plate are thin flat sheets of porous-metal material. These porous sheets form the top and bottom showerheads that supply the region between the showerhead plate and the reticle and the region between the conical aperture and the Optics Zone box with continuous flows of clean gas. The model studies show that the top showerhead provides robust reticle protection from particles of 10-nm diameter or larger originating from the Reticle Zone and from plenum surfaces contaminated by exposure to the Reticle Zone. Protection is achieved with negligible effect on EUV transmission. Furthermore, the bottom showerhead efficiently protects the reticle from nanoscale particles originating from the Optics Zone.« less
  • We studied the focusing of atoms by multiple layers of standing light waves in the context of atom lithography. In particular, atomic localization by a double-layer light mask is examined using the optimal squeezing approach. Operation of the focusing setup is analyzed both in the paraxial approximation and in the regime of nonlinear spatial squeezing for the thin-thin, as well as thin-thick, atom lens combinations. It is shown that the optimized double light mask may considerably reduce the imaging problems, improve the quality of focusing, and enhance the contrast ratio of the deposited structures.
  • The light-induced force on an atom is calculated for an arbitrary field configuration, taking into account the spontaneous emission and optical pumping processes as well as the degeneracy of atomic energy levels. Two types of the optical transitions are analyzed: J{yields}J with J a half-integer and J{yields}J+1 with J an arbitrary. Though the force is not potential in the general case, we introduce a scalar function {psi}, which plays a role of the potential energy, determining regions of localization of atoms. Applications of these results to atom nanolithography are discussed.
  • We have used an attenuated phase mask, a mask with a {pi}-phase shifting attenuator, in extreme ultraviolet lithography at 13.9 nm wavelength to produce resist profiles with sharper, more vertical sidewalls. {copyright} {ital 1997 American Vacuum Society.}
  • No abstract prepared.