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Totally Conductive and Anti-diffractive Planarized Grid for Electron Beam Lithography

IP.com Disclosure Number: IPCOM000108677D
Original Publication Date: 1992-Jun-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 2 page(s) / 59K

Publishing Venue

IBM

Related People

Enichen, WA: AUTHOR [+2]

Abstract

Electron beam lithography systems need to be calibrated to a known reference to remove distortions inherent in the deflection system. This has been done in the past by fabricating a mesh, or reference grid, of high atomic number material on a silicon wafer using integrated circuit manufacturing techniques. Also necessary is the measurement of the height of the grid because the differences in height between the substrate writing surface and the reference grid can result in an apparent magnification and rotation of the deflection field. If the difference in height is known, the deflection field can be corrected at the time of writing. The current reference grid is a metallic array of long bars in a silicon surface arranged at right angles to each other. The bars range from 2 to 5 um in width on 18.75 to 37.5 um centers.

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Totally Conductive and Anti-diffractive Planarized Grid for Electron Beam Lithography

       Electron beam lithography systems need to be calibrated
to a known reference to remove distortions inherent in the deflection
system.  This has been done in the past by fabricating a mesh, or
reference grid, of high atomic number material on a silicon wafer
using integrated circuit manufacturing techniques.  Also necessary is
the measurement of the height of the grid because the differences in
height between the substrate writing surface and the reference grid
can result in an apparent magnification and rotation of the
deflection field.  If the difference in height is known, the
deflection field can be corrected at the time of writing. The current
reference grid is a metallic array of long bars in a silicon surface
arranged at right angles to each other. The bars range from 2 to 5 um
in width on 18.75 to 37.5 um centers.  This reference grid has two
shortcomings:

                            (Image Omitted)

1.   The silicon space between the bars is highly susceptible to
oxidation, resulting in a surface that becomes non-conductive.  This
can cause errors in the measurement of the calibration grid.
2.   When the height is measured by the optical technique of
reflecting a light beam off the surface, an error can be introduced
due to the diffraction pattern produced by the periodic structure of
the grid.

      The two aforementioned shortco...