Electron Beam Generated Plasmas for Ultra Low Te Processing

The Naval Research Laboratory (NRL) has developed a processing system based on an electron beam-generated plasma. Unlike conventional discharges produced by electric fields (DC, RF, microwave, etc.), ionization is driven by a high-energy (∼ few keV) electron beam, an approach that can be attractive to atomic layer processing applications. In particular, high electron densities (10101011 cm−3) can be produced in electron beam generated plasmas, where the electron temperature remains between 0.3 and 1.0 eV. Accordingly, a large flux of ions can be delivered to substrate surfaces with kinetic energies in the range of 1 to 5 eV. This provides the potential for controllably etching and/or engineering both the surface morphology and chemistry with monolayer precision. This work describes the electron beam driven plasma processing system, with particular attention paid to system characteristics and the ability to control the generation and delivery of ions to the surface and their energies. © The Author(s) 2015. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited. [DOI: 10.1149/2.0071506jss] All rights reserved.

[1]  S. H. North,et al.  Plasma-based surface modification of polystyrene microtiter plates for covalent immobilization of biomolecules. , 2010, ACS applied materials & interfaces.

[2]  E. Oks.  Plasma Cathode Electron Sources: Physics, Technology, Applications , 2006 .

[3]  R. Fernsler,et al.  Symmetric extraction of positive and negative ions from electron beam-generated ion–ion plasmas , 2009 .

[4]  R. Fernsler,et al.  Continuous and pulsed electron beam production from an uninterrupted plasma cathode , 2015 .

[5]  R. Fernsler,et al.  Study of plasma-polyethylene interactions using electron beam-generated plasmas produced in Ar/SF6 mixtures† , 2010 .

[6]  R. Fernsler,et al.  Large-Area Plasma Processing System , 1999, IEEE Conference Record - Abstracts. 1999 IEEE International Conference on Plasma Science. 26th IEEE International Conference (Cat. No.99CH36297).

[7]  A. Lichtenberg,et al.  Principles of Plasma Discharges and Materials Processing , 1994 .

[8]  Richard F. Fernsler,et al.  Electron-Beam-Generated Plasmas for Materials Processing , 2004 .

[9]  Richard A. Gottscho,et al.  The grand challenges of plasma etching: a manufacturing perspective , 2014 .

[10]  M. Lieberman,et al.  Ion energy distributions in rf sheaths; review, analysis and simulation , 1999 .

[11]  M. Kushner,et al.  Electron-beam controlled radio frequency discharges for plasma processing , 1996 .

[12]  R. Dugdale.  Soft vacuum processing of materials with electron beams , 1975 .

[13]  M. Kushner,et al.  Effect of nonsinusoidal bias waveforms on ion energy distributions and fluorocarbon plasma etch selectivity , 2005 .

[14]  R. Fernsler,et al.  Controlling the electron energy distribution function of electron beam generated plasmas with molecular gas concentration: II. Numerical modeling , 2013 .

[15]  J. Robinson,et al.  Aminated graphene for DNA attachment produced via plasma functionalization , 2012 .

[16]  Martin Lampe,et al.  Theoretical overview of the large-area plasma processing system (LAPPS) , 2000 .

[17]  Y. Aoyagi,et al.  Surface processes in digital etching of GaAs , 1993 .

[18]  K. Emery,et al.  Electron beam assisted chemical vapor deposition of SiO2 , 1983 .

[19]  R. Fernsler,et al.  On the extraction of positive and negative ions from electron-beam-generated plasmas , 2002 .

[20]  R. Fernsler,et al.  Experimental and theoretical evaluations of electron temperature in continuous electron beam generated plasmas , 2008 .

[21]  J. Robinson,et al.  Chemical gradients on graphene to drive droplet motion. , 2013, ACS nano.

[22]  J. Robinson,et al.  High-quality uniform dry transfer of graphene to polymers. , 2012, Nano letters.

[23]  R. Fernsler,et al.  The spatial profile of density in electron beam generated plasmas , 2014 .

[24]  Yasuhiro Yamamoto,et al.  Digital etching of GaAs: New approach of dry etching to atomic ordered processing , 1990 .

[25]  R. Fernsler,et al.  Etching with electron beam generated plasmas , 2004 .

[26]  David N Ruzic,et al.  Electric probes for low temperature plasmas , 1994 .

[27]  M. Funk,et al.  End-boundary sheath potential, electron and ion energy distribution in the low-pressure non-ambipolar electron plasma , 2013 .

[28]  R. Fernsler,et al.  Controlling the electron energy distribution function of electron beam generated plasmas with molecular gas concentration: I. Experimental results , 2013 .

[29]  A. Ali,et al.  High‐energy electron beam deposition and plasma velocity distribution in partially ionized N2 , 1990 .

[30]  I. L. Singer,et al.  Global model for plasmas generated by electron beams in low-pressure nitrogen , 2014 .

[31]  R. Fernsler,et al.  Scaling Relationship for Energetic Electron Beams Propagating in Air , 2008 .

[32]  R. Fernsler,et al.  Measurement of ion energy distributions using a combined energy and mass analyzer. , 2007, The Review of scientific instruments.

[33]  G. Oehrlein,et al.  Study of photoresist etching and roughness formation in electron-beam generated plasmas , 2007 .

[34]  S. Rauf.  Effect of bias voltage waveform on ion energy distribution , 2000 .

[35]  J. Coburn,et al.  Positive‐ion bombardment of substrates in rf diode glow discharge sputtering , 1972 .

[36]  Jung-hyung Kim,et al.  Analysis of the uncertainty in the measurement of electron densities in plasmas using the wave cutoff method , 2005 .

[37]  M. A. Biondi,et al.  ELECTRON TEMPERATURE DEPENDENCE OF RECOMBINATION OF O$sub 2$$sup +$ AND N$sub 2$$sup +$ IONS WITH ELECTRONS. , 1969 .

[38]  J. Rocca,et al.  Glow‐discharge‐created electron beams: Cathode materials, electron gun designs, and technological applications , 1984 .

[39]  R. Fernsler,et al.  Generation of electron-beam produced plasmas and applications to surface modification , 2004 .

[40]  H. Villinger,et al.  Charge transfer of Ar + + N 2 ⇄ N 2 + + Ar at near thermal energies , 1981 .

[41]  T. Hara,et al.  New Etching System with a Large Diameter Using Electron Beam Excited Plasma , 1992 .

[42]  J. E. Stevens,et al.  Uniformity of radio frequency bias voltages along conducting surfaces in a plasma , 1996 .

[43]  Jane P. Chang,et al.  Perspectives in nanoscale plasma etching: what are the ultimate limits? , 2011 .

[44]  D. Ruzic,et al.  An electron-beam plasma source and geometry for plasma processing , 1993 .

[45]  C. Muratore,et al.  Applications of electron-beam generated plasmas to materials processing , 2005, IEEE Transactions on Plasma Science.

[46]  Mark J. Kushner,et al.  Plasma atomic layer etching using conventional plasma equipment , 2009 .

[47]  A. Wendt,et al.  Tailored ion energy distributions at an rf-biased plasma electrode , 2010 .

[48]  R. Fernsler,et al.  Time-resolved diagnostics in a pulsed, electron beam-generated plasma , 2005, IEEE Transactions on Plasma Science.